Patent Publication Number: US-2011059320-A1

Title: Interlayer film for laminated glass, laminated glass, and zinc oxide fine particle dispersion

Description:
TECHNICAL FIELD 
     The present invention relates to an interlayer film for a laminated glass in which zinc oxide fine particles are excellently dispersed, a laminated glass, and a zinc oxide fine particle dispersion. 
     BACKGROUND ART 
     A laminated glass is a safety glass because few glass fragments are scattered even if it is broken by impact from the outside. A laminated glass is widely employed in the windowpanes of motor vehicles such as automobiles, aircrafts, buildings and the like. Examples of a laminated glass include a laminated glass produced by interposing an interlayer film for a laminated glass, which contains a plasticizer and a polyvinyl butyral resin, between at least a pair of glasses. 
     However, there has been a problem that a laminated glass cannot shield infrared rays sufficiently, though it shows excellent safety. The wavelength range of infrared rays is in long-wavelength side as compared to that of visible light and is 780 nm or more. An amount of infrared energy is about 10% of an amount of ultraviolet energy. However, since infrared rays absorbed in a material are emitted as heat, infrared rays raise the ambient temperature. Accordingly, interrupting the infrared transmission through front and side windshields of automobiles can suppress the temperature rise inside the automobiles. In recent years, there has been a need for reduction of infrared transmittance of a laminated glass because an opening area of an automobile tends to be increased. 
     Patent Document 1 discloses an interlayer film for a laminated glass containing heat shielding fine particles, such as tin-doped indium oxide fine particles and antimony-doped tin oxide fine particles, and a polyvinyl acetal resin. The laminated glass with use of an interlayer film for a laminated glass, in which heat shielding fine particles are dispersed, is excellent in heat shielding property. 
     Since the price of the heat shielding fine particles such as tin-doped indium oxide fine particles and antimony-doped tin oxide fine particles is soaring, use of zinc oxide fine particles as heat shielding fine particles is considered. 
     However, it is difficult to uniformly disperse zinc oxide fine particles in a thermoplastic resin such as a polyvinyl acetal resin, and therefore, there has been a problem that a laminated glass using an interlayer film for a laminated glass containing zinc oxide fine particles has high haze, so that visible light transmittance is reduced. 
     Patent Document 2 discloses phosphate ester as a dispersant for increasing dispersibility of heat shielding fine particles such as tin-doped indium oxide fine particles and antimony-doped tin oxide fine particles. However, there has been a problem that use of zinc oxide fine particles and phosphate ester in combination cannot increase dispersibility of zinc oxide fine particles. 
     Patent Document No. 1: WO01/25162 
     Patent Document No. 2: Japanese Kokai Publication No. 2001-302288 (JP-A 2001-302288) 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     It is an object of the present invention to provide an interlayer film for a laminated glass in which zinc oxide fine particles are excellently dispersed, a laminated glass, and a zinc oxide fine particle dispersion. 
     Means for Solving the Problems 
     An interlayer film for a laminated glass according to the present invention comprises: zinc oxide fine particles containing a trivalent metallic element; a thermoplastic resin; a dispersant; and a plasticizer, the dispersant having a structure represented by the following general formula (1) and having an HLB value of 8 to 12: 
     
       
         
         
             
             
         
       
     
     wherein R 1  represents an alkyl group having 5 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms, R 2  represents an alkylene group having 2 to 5 carbon atoms, R 3  represents a hydrogen atom or R 4 (OR 5 ) n —, wherein R 4  represents an alkyl group having 5 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms, and R 5  represents an alkylene group having 2 to 5 carbon atoms, and “n” is an integer of 1 or more. 
     The following will discuss the present invention in detail. 
     The interlayer film for a laminated glass according to the present invention comprises: zinc oxide fine particles containing a trivalent metallic element; a thermoplastic resin; a dispersant; and a plasticizer. 
     The interlayer film for a laminated glass according to the present invention comprises zinc oxide fine particles containing a trivalent metallic element. 
     The interlayer film for a laminated glass according to the present invention, in which zinc oxide fine particles are excellently dispersed, can be obtained by combining the zinc oxide fine particles and the specific dispersant to be mentioned later. 
     With respect to the zinc oxide fine particles containing a trivalent metallic element, it is preferable to use zinc oxide fine particles doped with the trivalent metallic element. 
     The trivalent metallic element is not particularly limited, and examples thereof include gallium, aluminum, indium, and the like. The trivalent metallic element is preferably gallium among them. Two or more kinds of zinc oxide fine particles having different trivalent metallic elements may be used in combination. 
     Furthermore, zinc oxide fine particles containing the trivalent metallic element and zinc oxide fine particles containing an element other than the trivalent metallic element may be used in combination, and zinc oxide fine particles containing the trivalent metallic element and an element other than the trivalent metallic element maybe used. 
     A content of the trivalent metallic element in the zinc oxide fine particles containing a trivalent metallic element is not particularly limited; a preferred lower limit of the percentage of the number of moles of the trivalent metallic element to the total number of moles of the zinc element and the trivalent metallic element is 1.0 mol %, and a preferred upper limit thereof is 10 mol %. When the percentage of the number of moles of the trivalent metallic element is less than 1.0 mol %, infrared transmittance of the laminated glass may not decrease; and when it exceeds 10 mol %, it maybe difficult to produce zinc oxide fine particles. A more preferred lower limit of the percentage of the number of moles is 1.5 mol %, and a further preferred lower limit thereof is 2.0 mol %. A more preferred upper limit thereof is 8.0 mol %, and a further preferred lower limit thereof is 6.0 mol %. 
     The method for producing the zinc oxide fine particles containing a trivalent metallic element is not particularly limited, and conventional methods can be used. Examples of the method for producing the zinc oxide fine particles containing a trivalent metallic element include a coprecipitation method, a sintering method, an arc-discharge gas phase method, a spray pyrolysis method, and the like. 
     In the coprecipitation method, there is produced an aqueous solution containing: a water-soluble zinc compound such as zinc sulfate, zinc nitrate, zinc chloride, zinc carbonate, and zinc acetate; and a water-soluble salt of a trivalent metallic element. The coprecipite of the zinc compound is generated by neutralizing the aqueous solution. The obtained coprecipitate is fired under reducing atmosphere, and thereby it is possible to produce zinc oxide fine particles containing a trivalent metallic element. 
     In the arc-discharge gas phase method, for example, by reacting zinc vapor and vapor of a trivalent metallic element by using an oxidizing gas, it is possible to produce zinc oxide fine particles containing a trivalent metallic element. 
     In the spray pyrolysis method, an aqueous solution containing a water-soluble zinc compound and a water-soluble salt of a trivalent metallic element is finely sprayed into fire, hot combustion gases, or plazma, by using a nozzle. Subsequently, the water-soluble salt of a trivalent metallic element is thermally decomposed, or a metal ion of the trivalent metallic element is oxidized with an oxidizing gas, whereby it is possible to produce zinc oxide fine particles containing a trivalent metallic element. 
     The water-soluble salt of a trivalent metallic element is not particularly limited, and examples thereof include an inorganic salt and an organic salt of the metallic element, and the like. The inorganic salt of the metallic element is not particularly limited, and examples thereof include halide, carbonate, bicarbonate, nitrate, sulfate, phosphate, silicate, and borate of the metallic element, and the like. The organic salt of the metallic element is not particularly limited, and examples thereof include organic acid salts such as acetate, oxalate, formate, glycolate, citrate, and the like. Further, the salt of the metallic element may be a double salt of an inorganic salt and an organic salt. 
     The volume average particle diameter of the zinc oxide fine particles containing a trivalent metallic element is not particularly limited, and a preferred upper limit thereof is 500 nm. When the volume average particle diameter is more than 500 nm, visible light transmittance of the obtained laminated glass may be reduced. A more preferred upper limit of the volume average particle diameter is 200 nm. A further preferred upper limit thereof is 100 nm, and a particularly preferred upper limit thereof is 60 nm. 
     A content of the zinc oxide fine particles containing a trivalent metallic element in the interlayer film for a laminated glass of the present invention is not particularly limited. A preferred lower limit thereof is 0.01 parts by weight and a preferred upper limit thereof is 5.0 parts by weight, with respect to 100 parts by weight of the thermoplastic resin. When the content of the zinc oxide fine particles containing a trivalent metallic element is less than 0.01 parts by weight, the infrared transmittance of the obtained laminated glass may not be reduced. When the content of the zinc oxide fine particles containing a trivalent metallic element is more than 5.0 parts by weight, the visible light transmittance of the obtained laminated glass maybe reduced. A more preferred lower limit of the content of the zinc oxide fine particles containing a trivalent metallic element is 0.03 parts by weight and a more preferred upper limit thereof is 3.0 parts by weight. 
     The interlayer film for a laminated glass according to the present invention comprises a dispersant. 
     The dispersant has a structure represented by the following general formula (1), and has an HLB value of 8 to 12. 
     
       
         
         
             
             
         
       
     
     wherein R 1  represents an alkyl group having 5 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms, R 2  represents an alkylene group having 2 to 5 carbon atoms, R 3  represents a hydrogen atom or R 4 (OR 5 ) n —, wherein R 4  represents an alkyl group having 5 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms and R 5  represents an alkylene group having 2 to 5 carbon atoms, and “n” is an integer of 1 or more. 
     The interlayer film for a laminated glass according to the present invention, in which zinc oxide fine particles are excellently dispersed, can be obtained by combining the dispersant with the zinc oxide fine particles. 
     When R 1  and R 4  in the general formula (1) are alkyl groups, the lower limit of the number of carbon atoms of R 1  and R 4  in the general formula (1) is 5, and the upper limit thereof is 14. When the number of carbon atoms of R 1  and R 4  is less than five, since the hydrophilicity of the alkyl group of the dispersant is strong, the dispersant may not be compatible with a thermoplastic resin or a plasticizer. Consequently, visible light transmittance of the laminated glass decreases. When the number of carbon atoms of R 1  and R 4  exceeds 14, since lipophilic property of the alkyl group of the dispersant is strong, the dispersant may not be compatible with a thermoplastic resin or a plasticizer. Consequently, visible light transmittance of the laminated glass decreases. A preferred lower limit of the number of carbon atoms of R 1  and R 4  is 6, a more preferred lower limit thereof is 8, and a preferred upper limit thereof is 13. It is to be noted that R 1  and R 4  may be the same or different alkyl groups, and are preferably the same alkyl groups. 
     When R 1  and R 4  in the general formula (1) are aryl groups, the lower limit of the number of carbon atoms of R 1  and R 4  in the general formula (1) is 6, the upper limit thereof is 14. When the number of carbon atoms of R 1  and R 4  exceeds 14, since the lipophilic property of the aryl group of the dispersant is strong, the dispersant may not be compatible with a thermoplastic resin or a plasticizer. Consequently, visible light transmittance of the laminated glass decreases. A preferred lower limit of the number of carbon atoms of R 1  and R 4  is 7, a more preferred lower limit thereof is 9, and a particularly preferable lower limit thereof is 11. Because of its excellent compatibility with a thermoplastic resin or a plasticizer, R 1  and R 4  in the general formula (1) are preferably 2-ethylhexyl groups or tridecyl groups. It is to be noted that R 1  and R 4  maybe the same or different aryl groups, and are preferably the same aryl groups. 
     R 2  and R 5  in the general formula (1) represent alkylene groups each having 2 to 5 carbon atoms. R 2  and R 5  are preferably alkylene groups having 2 to 4 carbon atoms, more preferably ethylene groups, propylene groups, or butylene groups, further preferably ethylene groups or propylene groups, and particularly preferably ethylene groups. 
     R 2  and R 5  may be the same or different alkylene groups, and are preferably the same alkylene groups. 
     The symbol “n” in the general formula (1) is an integer of 1 or more. The symbol “n” in the general formula (1) is related to the HLB value of the dispersant. As “n” in the general formula (1) becomes larger, the molecular weight of the hydrophilic group of the dispersant increases, and therefore, the HLB value of the dispersant rises. As “n” in the general formula (1) becomes smaller, the molecular weight of the hydrophilic group of the dispersant decreases, and therefore, the HLB value of the dispersant falls. 
     When “n” is zero, since the dispersant is less likely to adhere to the zinc oxide fine particles, the zinc oxide fine particles agglomerate. A preferred upper limit of “n” in the general formula (1) is 50, and a more preferred upper limit thereof is 20. When “n” exceeds 50, since the dispersant excessively adhere to the zinc oxide fine particles, the zinc oxide fine particles may agglomerate. 
     It is to be noted that the HLB value can be adjusted by controlling the value of “n” in the general formula (1). Upon using, in combination, two or more kinds of dispersants having a structure represented by the general formula (1), the HLB value can be controlled by adjusting the blending ratio of the dispersant. 
     The lower limit of the HLB value of the dispersant is 8, and the upper limit thereof is 12. When the HLB value is less than 8, since lipophilic property of the dispersant is strong, the dispersant is less likely to be compatible with a thermoplastic resin or a plasticizer. Consequently, visible light transmittance of the laminated glass decreases. When the HLB value exceeds 12, since hydrophilicity of the dispersant is strong, the dispersant is less likely to be compatible with a thermoplastic resin or a plasticizer. Consequently, visible light transmittance of the laminated glass decreases. A preferred lower limit of the HLB value is 8.5, a more preferred lower limit thereof is 9, a preferred upper limit thereof is 11, and a more preferred upper limit thereof is 10. 
     It is to be noted that the HLB value of the present invention is defined by the following equation by the Griffin method. 
         HLB  value=20×(molecular weight of hydrophilic group of dispersant/molecular weight of dispersant)
 
     Here, the molecular weight of the hydrophilic group means the total atomic weight of —(OR 2 ) n — and —(OR 5 ) n —. Upon using, in combination, two or more kinds of dispersants having a structure represented by the general formula (1), the HLB value of the present invention is defined by the following equation. 
         HLB  value=20×(number-average molecular weight of hydrophilic group of dispersant/number-average molecular weight of dispersant)
 
     The dispersant is not particularly limited, and examples thereof include: a dispersant having a structure represented by the general formula (1) in which R 2  represents an isobutyl group having 5 carbon atoms (R 2  represents an ethylene group, R 3  represents a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represents an isobutyl group and R 5  represents an ethylene group, the HLB value is 11.0, and “n” is an integer of 1 or more); a dispersant having a structure represented by the general formula (1) in which R 1  represents a 2-ethylhexyl group having 8 carbon atoms (R 2  represents an ethylene group, R 3  represents a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represents a 2-ethylhexyl group and R 5  represents an ethylene group, the HLB value is 10.0, and “n” is an integer of 1 or more); a dispersant having a structure represented by the general formula (1) in which R 1  represents a lauryl group having 12 carbon atoms (R 2  represents an ethylene group, R 3  represents a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represents a lauryl group and R 5  represents an ethylene group, the HLB value is 8.0, and “n” is an integer of 1 or more); a dispersant having a structure represented by the general formula (1) in which R 1  represents a tridecyl group having 13 carbon atoms (R 2  represents an ethylene group, R 3  represents a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represents a tridecyl group and R 5  represents an ethylene group, the HLB value is 9.4, and “n” is an integer of 1 or more); a dispersant having a structure represented by the general formula (1) in which R 1  represents an octylphenyl group having 14 carbon atoms (R 2  represents an ethylene group, R 3  represents a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represents an octylphenyl group and R 5  represents an ethylene group, the HLB value is 12.0, and “n” is an integer of 1 or more); a dispersant having a structure represented by the general formula (1) in which R 1  represents a 2-ethylhexyl group having 8 carbon atoms (R 2  represents a propylene group, R 3  represents a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represents a 2-ethylhexyl group and R 5  represents a propylene group, the HLB value is 9.4, and “n” is an integer of 1 or more); a dispersant having a structure represented by the general formula (1) in which R 1  represents a 2-ethylhexyl group having 8 carbon atoms (R 2  represents a butylene group, R 3  represents a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represents a 2-ethylhexyl group and R 5  represents a butylene group, the HLB value is 8.8, and “n” is an integer of 1 or more); and the like. 
     The dispersant having a structure represented by the general formula (1) is commercially available from Dai-ichi Kogyo Seiyaku Co., Ltd. and TOHO Chemical Industry Co., LTD., for example. It is to be noted that many commercial dispersants having a structure represented by the general formula (1) may be a mixture of the dispersant in which R 3  is a hydrogen atom and the dispersant in which R 3  is R 4 (OR 5 ) n —, or a mixture of a plurality of dispersants having different R 1  and “n”. 
     A content of the dispersant in the interlayer film for a laminated glass according to the present invention is not particularly limited; a preferred lower limit thereof is 1.0 part by weight and a preferred upper limit thereof is 50 parts by weight, with respect to 100 parts by weight of the zinc oxide fine particles. When the content of the dispersant is less than 1.0 part by weight, since dispersibility of the zinc oxide fine particles decreases, visible light transmittance of the laminated glass may fall. When the content of the dispersant exceeds 50 parts by weight, the haze of the laminated glass may become higher or the adhesion between the interlayer film for a laminated glass and glass may decline. A more preferred lower limit of the content of the dispersant is 2.0 parts by weight, a further preferred lower limit thereof is 3.0 parts by weight, a more preferred upper limit thereof is 40 parts by weight, and a further preferred upper limit thereof is 35 parts by weight. 
     The interlayer film for a laminated glass according to the present invention contains a thermoplastic resin. 
     The thermoplastic resin is not particularly limited, and examples thereof include a polyvinyl acetal resin, an ethylene-vinyl acetate copolymer resin, an ethylene-acryl copolymer resin, a polyurethane resin, a polyurethane resin containing a sulfur element, a polyvinyl alcohol resin, and the like. The polyvinyl acetal resin is preferable among them because of its excellent adhesion to glass. 
     The polyvinyl acetal resin can be produced by acetalizing polyvinyl alcohol with aldehyde. Two or more kinds of the polyvinyl acetal resin may be used in combination if necessary. 
     A preferred lower limit of the acetalization degree of the polyvinyl acetal resin is 40 mol %, a preferred upper limit thereof is 85 mol %, a more preferred lower limit thereof is 60 mol %, and a more preferred upper limit thereof is 75 mol %. 
     The polyvinyl alcohol can be produced by saponifying polyvinyl acetate. 
     The saponification degree of the polyvinyl alcohol is preferably 80 to 99.8 mol %. 
     A preferred lower limit of the polymerization degree of the polyvinyl alcohol is 200, and a preferred upper limit thereof is 3000. When the polymerization degree is less than 200, penetration resistance of the laminated glass may decrease. When the polymerization degree exceeds 3000, molding of the interlayer film for a laminated glass may be difficult. Amore preferred lower limit of the polymerization degree is 500, and a more preferred upper limit thereof is 2000. 
     The aldehyde is not particularly limited, and aldehyde having 1 to 10 carbon atoms is suitably used. The aldehyde having 1 to 10 carbon atoms is not particularly limited, and examples thereof include n-butylaldehyde, isobutylaldehyde, n-valeraldehyde, 2-ethylbutylaldehyde, n-hexylaldehyde, n-octylaldehyde, n-nonylaldehyde, n-decylaldehyde, formaldehyde, acetaldehyde, benzaldehyde, and the like. In particular, n-butylaldehyde, n-hexylaldehyde, and n-valeraldehyde are preferable, and n-butylaldehyde having 4 carbon atoms is more preferable. Each of these aldehydes may be used alone or two or more kinds of these may be used in combination. 
     The interlayer film for a laminated glass of the present invention contains a plasticizer. 
     The plasticizer is not particularly limited, and examples thereof include organic ester plasticizers such as monobasic organic acid ester and polybasic organic acid ester, phosphate plasticizers such as an organic phosphate plasticizer and an organic phosphite plasticizer, and the like. 
     The monobasic organic acid ester is not particularly limited, and examples thereof include glycol esters obtained by reacting a glycol such as triethylene glycol, tetraethylene glycol, and tripropylene glycol, with a monobasic organic acid such as butyric acid, isobutyric acid, caproic acid, 2-ethylbutyric acid, heptylic acid, n-octylic acid, 2-ethylhexylic acid, pelargonic acid (n-nonylic acid), and decylic acid. In particular, triethylene glycol dialkyl acid ester such as triethylene glycol dicaproate, triethylene glycol di-2-ethylbutyrate, triethylene glycol di-n-octylate, and triethylene glycol di-2-ethylhexylate is preferable. 
     The polybasic organic acid ester is not particularly limited, and examples thereof include an ester compound of a polybasic organic acid, such as adipic acid, sebacic acid and azelaic acid, and alcohol having a straight-chain or branch structure and having 4 to 8 carbon atoms. In particular, dibutyl sebacate, dioctyl azelate, and dibutylcarbitol adipate are preferable. 
     The organic ester plasticizer is not particularly limited, and examples thereof include triethylene glycol di-2-ethylbutyrate, triethylene glycol di-2-ethylhexanoate, triethylene glycol dicaprylate, triethylene glycol di-n-octanoate, triethylene glycol di-n-heptanoate, tetraethylene glycol di-n-heptanoate, dibutyl sebacate, dioctyl azelate, dibutylcarbitol adipate, ethylene glycol di-2-ethylbutyrate, 1,3-propylene glycol di-2-ethylbutyrate, 1,4-butylene glycol di-2-ethylbutyrate, 1,2-butylene glycol di-2-ethylenebutyrate, diethylene glycol di-2-ethylbutyrate, diethylene glycol di-2-ethylhexanoate, dipropylene glycol di-2-ethylbutyrate, triethylene glycol di-2-ethylpentanoate, tetraethylene glycol di-2-ethylbutyrate, diethylene glycol dicaprylate, triethylene glycol di-n-heptanoate, tetraethylene glycol di-n-heptanoate, triethylene glycol di-2-ethylbutyrate, triethylene glycol bis(2-ethylbutyrate), triethylene glycol di(2-ethylhexanoate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyl adipate, a mixture of heptyl adipate and nonyl adipate, diisononyl adipate, heptyl nonyl adipate, dibutyl sebacate, and the like. 
     The organic phosphate plasticizer is not particularly limited, and examples thereof include tributoxyethyl phosphate, isodecyl phenylphosphate, triisopropyl phosphate, and the like. 
     The plasticizer is preferably at least one kind selected from the group consisting of dihexyl adipate (DHA), triethylene glycol di-2-ethylhexanoate (3GO), tetraethylene glycol di-2-ethylhexanoate (4GO), triethylene glycol di-2-ethylbutyrate (3GH), tetraethylene glycol di-2-ethylbutyrate (4GH), tetraethylene glycol diheptanoate (4G7), and triethylene glycol diheptanoate (3G7). 
     Since the plasticizer is less likely to be hydrolyzed, the plasticizer is preferably a diester compound such as triethylene glycol di-2-ethylhexanoate (3GO), triethylene glycol di-2-ethylbutyrate (3GH), tetraethylene glycol di-2-ethylhexanoate (4GO), and tetraethylene glycol diheptanoate (4G7). The plasticizer is more preferably tetraethylene glycol di-2-ethylhexanoate (4GO), tetraethylene glycol diheptanoate (4G7), and triethylene glycol di-2-ethylhexanoate (3GO). The plasticizer is further preferably triethylene glycol di-2-ethylhexanoate. 
     A content of the plasticizer in the interlayer film for a lamination glass of the present invention is not particularly limited. A preferred lower limit thereof is 25 parts by weight and a preferred upper limit thereof is 60 parts by weight, with respect to 100 parts by weight of the thermoplastic resin. When the content of the plasticizer is less than 25 parts by weight, penetration resistance of the obtained laminated glass may be deteriorated. When the content of the plasticizer is more than 60 parts by weight, a bleed out of the plasticizer may be caused. A more preferred lower limit of the content of the plasticizer is 30 parts by weight and a more preferred upper limit thereof is 50 parts by weight. 
     The interlayer film for a laminated glass of the present invention may contain a heat ray absorbent other than the zinc oxide fine particles containing a trivalent metallic element. The heat ray absorbent is not particularly limited, and examples thereof include tin-doped indium oxide fine particles, antimony-doped tin oxide fine particles, metal-doped tungsten oxide fine particles, lanthanum hexaboride fine particles, a phthalocyanine compound, and the like. In particular, the heat ray absorbent is preferably tin-doped indium oxide fine particles. 
     The interlayer film for a laminated glass of the present invention may contain additives such as a dispersing agent, an antioxidant, a light stabilizer, a flame retardant, an antistatic agent, an adhesion regulator, a moisture resistant agent, a heat reflecting agent, a fluorescent bleach, and a blue pigment. 
     The interlayer film for a laminated glass of the present invention may contain the dispersing agent. The dispersing agent is not particularly limited, and examples thereof include alcohol and the like. The alcohol is not particularly limited, and examples thereof include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butyl alcohol, 1-pentanol, isoamyl alcohol, s-amyl alcohol, 3-pentanol, tert-amyl alcohol, n-hexanol, methyl amyl alcohol, 2-ethylbutanol, n-heptanol, 2-heptanol, 3-heptanol, n-octanol, 2-octanol, 2-ethylhexanol, 3,5,5-trimethyl hexanol, nonanol, n-decanol, undecanol, trimethylnonyl alcohol, tetradecanol, heptadecanol, cyclohexanol, 2-methyl cyclohexanol, benzyl alcohol, and the like. 
     The interlayer film for a laminated glass according to the present invention may have a single-layered structure consisting only of one layer, or have a multi-layered structure obtained by laminating a plurality of layers. 
     The interlayer film for a laminated glass according to the present invention may have a multi-layered structure obtained by laminating two or more resin layers comprising a heat ray shielding layer. The heat ray shielding layer contains: the zinc oxide fine particles containing a trivalent metallic element; the thermoplastic resin; the dispersant having a structure represented by said general formula (1); and the plasticizer. In the multi-layered structure, two or more resin layers comprising at least a heat ray shielding layer may be laminated. The multi-layered structure preferably has at least three resin layers, and for example, any one layer of an outermost layer, an intermediate layer, and another outermost layer may be a heat ray shielding layer. 
     Moreover, when the interlayer film has the intermediate layer in which the polyvinyl acetal resin has an amount of hydroxyl groups of 15 to 25 mol %, an acetylation degree of 8 to 18 mol %, and an acetalization degree of 60 to 71 mol %, and the plasticizer has a content of 50 to 70 parts by weight with respect to 100 parts by weight of the polyvinyl acetal resin, the sound insulation of the laminated glass can be improved. 
     The method for producing the interlayer film for a laminated glass according to the present invention is not particularly limited, and for example, there is produced a zinc oxide fine particle dispersion comprising: zinc oxide fine particles containing a trivalent metallic element; the dispersant; and the plasticizer. The zinc oxide fine particle dispersion, the plasticizer, and the thermoplastic resin are kneaded to mold an interlayer film for a laminated glass. 
     The kneading method is not particularly limited, and examples thereof include a method using an extruder, a plastograph, a kneader, a Banbury mixer, a calender roll, and the like. The method using an extruder is preferable among them. 
     The method for molding the interlayer film for a laminated glass is not particularly limited, and examples thereof include an extrusion method, a calender method, a pressing method, and the like. 
     The zinc oxide fine particles are uniformly dispersed in the interlayer film for a laminated glass according to the present invention. Therefore, a laminated glass obtained by using the interlayer film for a laminated glass according to the present invention has a very high visible light transmittance. 
     The laminated glass obtained by using the interlayer film for a laminated glass according to the present invention constitutes one aspect of the present invention. 
     The laminated glass of the present invention is a laminated glass in which the interlayer film for a laminated glass according to the present invention is interposed between at least a pair of glass. 
     A glass plate used for the laminated glass of the present invention is not particularly limited, and examples thereof include: inorganic glass such as float plate glass, polished plate glass, molded plate glass, meshed plate glass, wired plate glass, colored plate glass, heat ray absorbing glass, heat reflecting glass, and green glass; plastic plates such as a polycarbonate plate and a polyacrylate plate; and the like. 
     The method for producing the laminated glass of the present invention is not particularly limited, and conventional methods can be used. 
     Since the laminated glass of the present invention is obtained by using the interlayer film for a laminated glass according to the present invention, it can be used suitably for windshields of motor vehicles such as automobiles. 
     A zinc oxide fine particle dispersion in which the zinc oxide fine particles are dispersed, namely, a zinc oxide fine particle dispersion comprising: zinc oxide fine particles containing a trivalent metallic element; a dispersant; and a plasticizer, wherein the dispersant having a structure represented by the above general formula (1) and having an HLB value of 8 to 12, also constitutes one aspect of the present invention. 
     Effects of the Invention 
     The present invention makes it possible to provide an interlayer film for a laminated glass in which zinc oxide fine particles are excellently dispersed, a laminated glass, and a zinc oxide fine particle dispersion. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. 
     EXAMPLE 1 
     (1) Production of a Zinc Oxide Fine Particle Dispersion 
     An amount of 30 parts by weight of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element (volume average particle diameter: 20 nm), 267 parts by weight of triethylene glycol di-2-ethylhexanoate as a plasticizer, 3 parts by weight of polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a 2-ethylhexyl group having 8 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a 2-ethylhexyl group and R 5  represented an ethylene group, the HLB value was 10, and “n” was an integer of 1 or more) as a dispersant, and 1125 parts by weight of zirconia beads were mixed to obtain a mixture. The obtained mixture is dispersed for four hours by using a batch-type bead mill to produce a zinc oxide fine particle dispersion. 
     (2) Production of an Interlayer film for a Laminated Glass 
     An amount of 12.6 parts by weight of the obtained zinc oxide fine particle dispersion and 100 parts by weight of a polyvinyl butyral resin (PVB: average polymerization degree of 1700, butyralization degree of 68.5 mol %, 30.6 mol % of hydroxyl group, and 0.9 mol % of acetyl group) as a thermoplastic resin were mixed. As a plasticizer, triethylene glycol di-2-ethylhexanoate was further added in such a manner that the total amount of the plasticizer reached 40 parts by weight with respect to 100 parts by weight of the thermoplastic resin, and the mixture was mixed to produce a thermoplastic resin composition. 
     The obtained thermoplastic resin composition was molded by using a counter-rotating twin-screw extruder to produce an interlayer film for a laminated glass having a thickness of 760 μm. 
     (3) Production of a Laminated Glass 
     The obtained interlayer film for a laminated glass was interposed between two sheets of clear float glass (5 cm in height×5 cm in width×2.5 mm in thickness). The laminated body was placed in a vacuum bag and the vacuum bag was deaerated to 933.2 hPa. Subsequently, the vacuum bag was heated until the interior temperature of the vacuum bag reached 100° C. and the vacuum bag was maintained at the temperature for 20 minutes. The vacuum bag was naturally cooled and the temporarily-bonded laminated glass was taken out. The temporarily-bonded laminated glass was autoclaved at a temperature of 135° C. and at a pressure of 1.2 MPa for 20 minutes to produce a laminated glass. 
     EXAMPLE 2 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a tridecyl group having 13 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a tridecyl group and R 5  represented an ethylene group, the HLB value was 9.4, and “n” was an integer of 1 or more) was used as a dispersant. 
     EXAMPLE 3 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a lauryl group having 12 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a lauryl group and R 5  represented an ethylene group, the HLB value was 8.0, and “n” was an integer of 1 or more) was used as a dispersant. 
     EXAMPLE 4 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented an isobutyl group having 5 carbon atoms, R 2  represented an ethylene group, R 3  represents a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented an isobutyl group and R 5  represented an ethylene group, the HLB value was 11.0, and “n” was an integer of 1 or more) was used as a dispersant. 
     EXAMPLE 5 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented an octylphenyl group having 14 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented an octylphenyl group and R 5  represented an ethylene group, the HLB value was 12.0, and “n” was an integer of 1 or more) was used as a dispersant. 
     COMPARATIVE EXAMPLE 1 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that a thermoplastic resin composition was obtained by mixing 100 parts by weight of a polyvinyl butyral resin and 40 parts by weight of triethylene glycol di-2-ethylhexanoate. 
     COMPARATIVE EXAMPLE 2 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a nonylphenyl group having 15 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a nonylphenyl group and R 5  represented an ethylene group, the HLB value was 11.0, and “n” was an integer of 1 or more) was used as a dispersant and the composition ratio was adjusted as shown in Table 1. 
     COMPARATIVE EXAMPLE 3 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a lauryl group having 12 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a lauryl group and R 5  represented an ethylene group, the HLB value was 12.3, and “n” was an integer of 1 or more) was used as a dispersant and the composition ratio was adjusted as shown in Table 1. 
     COMPARATIVE EXAMPLE 4 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a butyl group having 4 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a butyl group and R 5  represented an ethylene group, the HLB value was 10.0, and “n” was an integer of 1 or more) was used as a dispersant and the composition ratio was adjusted as shown in Table 1. 
     &lt;Evaluation&gt; 
     The zinc oxide fine particle dispersions obtained in Examples 1 to 5 and in Comparative Examples 2 to 4, and the laminated glasses obtained in Examples 1 to 5 and in Comparative Examples 1 to 4 were evaluated as follows. 
     Table 1 shows the results. 
     (1) Evaluations on Visible Light Transmittance (Tv) and Infrared Transmittance (Tir) of Zinc Oxide Fine Particle Dispersions 
     The zinc oxide fine particle dispersion was diluted with the used plasticizer to the particle concentration shown in Table 1. The visible light transmittance (Tv) and the infrared transmittance (Tir) of the diluted zinc oxide fine particle dispersion were measured by using a spectrophotometer (“U-4100” produced by Hitachi High-Technologies Corporation), in conformity with JIS R 3106 (1998). It is to be noted that a quartz cell having a light path length of 1 mm was used. 
     (2) Evaluations on Visible Light Transmittance (Tv) and Infrared Transmittance (Tir) of Laminated Glasses 
     The visible light transmittance (Tv) and the infrared transmittance (Tir) of the laminated glass were measured by using a spectrophotometer (“U-4100” produced by Hitachi High-Technologies Corporation), in conformity with JIS R 3106 (1998). 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
            
               
                   
                 Example 1 
                 Example 2 
                 Example 3 
                 Example 4 
                 Example 5 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Dispersant 
                 R 1  in general formula (1) 
                 2-ethylhexyl 
                 tridecyl 
                 lauryl 
                 isobutyl 
                 octylphenyl 
               
               
                   
                   
                 group 
                 group 
                 group 
                 group 
                 group 
               
               
                   
                 The number of carbon atoms 
                 8 
                 13 
                 12 
                 5 
                 14 
               
               
                   
                 of R 1   
               
               
                   
                 Alkylene portion of 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
               
               
                   
                 polyoxyalkylene 
               
               
                   
                 HLB value 
                 10.0 
                 9.4 
                 8.0 
                 11.0 
                 12.0 
               
               
                 Zinc oxide fine particles 
                 Trivalent metal species 
                 gallium 
                 gallium 
                 gallium 
                 gallium 
                 gallium 
               
               
                 containing trivalent 
                 Content ratio of trivalent 
                 4 
                 4 
                 4 
                 4 
                 4 
               
               
                 metallic element 
                 metal (mol %) 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Zinc oxide fine 
                 Composition 
                 Zinc oxide fine particles 
                 30 
                 30 
                 30 
                 30 
                 30 
               
               
                 particle 
                 (parts by 
                 Plasticizer (3GO) 
                 267 
                 267 
                 267 
                 267 
                 267 
               
               
                 dispersion 
                 weight) 
                 Dispersant 
                 3 
                 3 
                 3 
                 3 
                 3 
               
               
                   
                 Physical 
                 Particle concentration 
                 0.90 
                 0.90 
                 0.90 
                 0.90 
                 0.90 
               
               
                   
                 properties 
                 (% by weight) 
               
               
                   
                   
                 Tv (%) 
                 81.7 
                 81.5 
                 81.4 
                 81.0 
                 81.3 
               
               
                   
                   
                 Tir (%) 
                 82.7 
                 82.7 
                 82.5 
                 82.3 
                 82.5 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Composition of 
                 Zinc oxide fine particle 
                 12.6 
                 12.6 
                 12.6 
                 12.6 
                 12.6 
               
               
                 interlayer film 
                 dispersion 
               
               
                 for laminated glass 
                 Polyvinyl butyral 
                 100 
                 100 
                 100 
                 100 
                 100 
               
               
                 (parts by weight) 
                 Plasticizer (total amount) 
                 40 
                 40 
                 40 
                 40 
                 40 
               
               
                 Physical properties 
                 Particle concentration 
                 0.89 
                 0.89 
                 0.89 
                 0.89 
                 0.89 
               
               
                 of laminated glass 
                 (% by weight) 
               
               
                   
                 Tv (%) 
                 76.1 
                 76.0 
                 75.8 
                 75.8 
                 75.9 
               
               
                   
                 Tir (%) 
                 64.9 
                 64.9 
                 64.8 
                 64.7 
                 64.8 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Comparative 
                 Comparative 
                 Comparative 
                 Comparative 
               
               
                   
                 Example 1 
                 Example 2 
                 Example 3 
                 Example 4 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Dispersant 
                 R 1  in general formula (1) 
                 — 
                 nonylphenyl 
                 lauryl 
                 butyl 
               
               
                   
                   
                   
                   
                 group 
                 group 
                 group 
               
               
                   
                   
                 The number of carbon atoms 
                 — 
                 15 
                 12 
                 4 
               
               
                   
                   
                 of R 1   
               
               
                   
                   
                 Alkylene portion of 
                 — 
                 ethylene 
                 ethylene 
                 ethylene 
               
               
                   
                   
                 polyoxyalkylene 
               
               
                   
                   
                 HLB value 
                 — 
                 11.0 
                 12.3 
                 10.0 
               
               
                   
                 Zinc oxide fine particles 
                 Trivalent metal species 
                 — 
                 gallium 
                 gallium 
                 gallium 
               
               
                   
                 containing trivalent 
                 Content ratio of trivalent 
                 — 
                 4 
                 4 
                 4 
               
               
                   
                 metallic element 
                 metal (mol %) 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 Zinc oxide fine 
                 Composition 
                 Zinc oxide fine particles 
                 — 
                 30 
                 30 
                 30 
               
               
                   
                 particle 
                 (parts by 
                 Plasticizer (3GO) 
                 — 
                 267 
                 267 
                 267 
               
               
                   
                 dispersion 
                 weight) 
                 Dispersant 
                 — 
                 3 
                 3 
                 3 
               
               
                   
                   
                 Physical 
                 Particle concentration 
                 — 
                 0.52 
                 0.50 
                 0.46 
               
               
                   
                   
                 properties 
                 (% by weight) 
               
               
                   
                   
                   
                 Tv (%) 
                 — 
                 68.1 
                 67.1 
                 65.8 
               
               
                   
                   
                   
                 Tir (%) 
                 — 
                 82.9 
                 82.9 
                 82.9 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Composition of 
                 Zinc oxide fine particle 
                 — 
                 7.4 
                 7.1 
                 6.8 
               
               
                   
                 interlayer film for 
                 dispersion 
               
               
                   
                 laminated glass 
                 Polyvinyl butyral 
                 100 
                 100 
                 100 
                 100 
               
               
                   
                 (parts by weight) 
                 Plasticizer (total amount) 
                 40 
                 40 
                 40 
                 40 
               
               
                   
                 Physical properties 
                 Particle concentration 
                 — 
                 0.53 
                 0.50 
                 0.48 
               
               
                   
                 of laminated glass 
                 (% by weight) 
               
               
                   
                   
                 Tv (%) 
                 89.0 
                 66.4 
                 66.8 
                 65.5 
               
               
                   
                   
                 Tir (%) 
                 75.0 
                 65.0 
                 65.0 
                 65.0 
               
               
                   
                   
               
            
           
         
       
     
     EXAMPLE 6 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of aluminum as a trivalent metallic element were used instead of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, and the composition ratio was adjusted as shown in Table 2. 
     EXAMPLE 7 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 2, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of aluminum as a trivalent metallic element were used instead of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, and the composition ratio was adjusted as shown in Table 2. 
     EXAMPLE 8 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 3, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of aluminum as a trivalent metallic element were used instead of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, and the composition ratio was adjusted as shown in Table 2. 
     EXAMPLE 9 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 4, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of aluminum as a trivalent metallic element were used instead of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, and the composition ratio was adjusted as shown in Table 2. 
     EXAMPLE 10 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 5, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of aluminum as a trivalent metallic element were used instead of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, and the composition ratio was adjusted as shown in Table 2. 
     &lt;Evaluation&gt; 
     The zinc oxide fine particle dispersions and the laminated glasses obtained in Examples 6 to 10 were evaluated in the same manner as in Example 1. 
     Table 2 shows the results. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Example 6 
                 Example 7 
                 Example 8 
                 Example 9 
                 Example 10 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Dispersant 
                 R 1  in general formula (1) 
                 2-ethylhexyl 
                 tridecyl 
                 lauryl 
                 isobutyl 
                 octylphenyl 
               
               
                   
                   
                 group 
                 group 
                 group 
                 group 
                 group 
               
               
                   
                 The number of carbon atoms 
                 8 
                 13 
                 12 
                 5 
                 14 
               
               
                   
                 of R 1   
               
               
                   
                 Alkylene portion of 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
               
               
                   
                 polyoxyalkylene 
               
               
                   
                 HLB value 
                 10.0 
                 9.4 
                 8.0 
                 11.0 
                 12.0 
               
               
                 Zinc oxide fine particles 
                 Trivalent metal species 
                 aluminum 
                 aluminum 
                 aluminum 
                 aluminum 
                 aluminum 
               
               
                 containing trivalent 
                 Content ratio of trivalent 
                 4 
                 4 
                 4 
                 4 
                 4 
               
               
                 metallic element 
                 metal (mol %) 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Zinc oxide firm 
                 Composition 
                 Zinc oxide fine particles 
                 30 
                 30 
                 30 
                 30 
                 30 
               
               
                 particle 
                 (parts by 
                 Plasticizer (3GO) 
                 267 
                 267 
                 267 
                 267 
                 267 
               
               
                 dispersion 
                 weight) 
                 Dispersant 
                 3 
                 3 
                 3 
                 3 
                 3 
               
               
                   
                 Physical 
                 Particle concentration 
                 0.92 
                 0.92 
                 0.92 
                 0.92 
                 0.92 
               
               
                   
                 properties 
                 (% by weight) 
               
               
                   
                   
                 Tv (%) 
                 81.1 
                 80.9 
                 80.7 
                 80.4 
                 80.6 
               
               
                   
                   
                 Tir (%) 
                 82.7 
                 82.7 
                 82.6 
                 82.7 
                 82.7 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Composition of 
                 Zinc oxide fine particle 
                 12.9 
                 12.9 
                 12.9 
                 12.9 
                 12.9 
               
               
                 interlayer film for 
                 dispersion 
               
               
                 laminated glass 
                 Poly vinyl butyral 
                 100 
                 100 
                 100 
                 100 
                 100 
               
               
                 (parts by weight) 
                 Plasticizer (total amount) 
                 40 
                 40 
                 40 
                 40 
                 40 
               
               
                 Physical properties 
                 Particle concentration 
                 0.91 
                 0.91 
                 0.91 
                 0.91 
                 0.91 
               
               
                 of laminated glass 
                 (% by weight) 
               
               
                   
                 Tv (%) 
                 76.0 
                 75.9 
                 75.8 
                 75.7 
                 75.7 
               
               
                   
                 Tir (%) 
                 65.0 
                 64.9 
                 65.0 
                 65.0 
                 65.0 
               
               
                   
               
            
           
         
       
     
     EXAMPLE 11 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of indium as a trivalent metallic element were used instead of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, and the composition ratio was adjusted as shown in Table 3. 
     EXAMPLE 12 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 2, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of indium as a trivalent metallic element were used instead of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, and the composition ratio was adjusted as shown in Table 3. 
     EXAMPLE 13 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 3, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of indium as a trivalent metallic element were used instead of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, and the composition ratio was adjusted as shown in Table 3. 
     EXAMPLE 14 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 4, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of indium as a trivalent metallic element were used instead of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, and the composition ratio was adjusted as shown in Table 3. 
     EXAMPLE 15 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 5, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of indium as a trivalent metallic element were used instead of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, and the composition ratio was adjusted as shown in Table 3. 
     &lt;Evaluation&gt; 
     The zinc oxide fine particle dispersions and the laminated glasses obtained in Examples 11 to 15 were evaluated in the same manner as in Example 1. 
     Table 3 shows the results. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Example 11 
                 Example 12 
                 Example 13 
                 Example 14 
                 Example 15 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Dispersant 
                 R 1  in general formula (1) 
                 2-ethylhexyl 
                 tridecyl 
                 lauryl 
                 isobutyl 
                 octylphenyl 
               
               
                   
                   
                 group 
                 group 
                 group 
                 group 
                 group 
               
               
                   
                 The number of carbon atoms 
                 8 
                 13 
                 12 
                 5 
                 14 
               
               
                   
                 of R 1   
               
               
                   
                 Alkylene portion of 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
               
               
                   
                 polyoxyalkylene 
               
               
                   
                 HLB value 
                 10.0 
                 9.4 
                 8.0 
                 11.0 
                 12.0 
               
               
                 Zinc oxide fine particles 
                 Trivalent metal species 
                 indium 
                 indium 
                 indium 
                 indium 
                 indium 
               
               
                 containing trivalent 
                 Content ratio of trivalent 
                 4 
                 4 
                 4 
                 4 
                 4 
               
               
                 metallic element 
                 metal (mol %) 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Zinc oxide fine 
                 Composition 
                 Zinc oxide fine particles 
                 30 
                 30 
                 30 
                 30 
                 30 
               
               
                 particle 
                 (parts by 
                 Plasticizer (3GO) 
                 267 
                 267 
                 267 
                 267 
                 267 
               
               
                 dispersion 
                 weight) 
                 Dispersant 
                 3 
                 3 
                 3 
                 3 
                 3 
               
               
                   
                 Physical 
                 Particle concentration 
                 0.95 
                 0.95 
                 0.95 
                 0.95 
                 0.95 
               
               
                   
                 properties 
                 (% by weight) 
               
               
                   
                   
                 Tv (%) 
                 80.3 
                 80.1 
                 79.8 
                 79.8 
                 79.7 
               
               
                   
                   
                 Tir (%) 
                 82.7 
                 82.6 
                 82.6 
                 82.7 
                 82.7 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Composition of 
                 Zinc oxide fine particle 
                 13.3 
                 13.3 
                 13.3 
                 13.3 
                 13.3 
               
               
                 interlayer film for 
                 dispersion 
               
               
                 laminated glass 
                 Polyvinyl butyral 
                 100 
                 100 
                 100 
                 100 
                 100 
               
               
                 (parts by weight) 
                 Plasticizer (total amount) 
                 40 
                 40 
                 40 
                 40 
                 40 
               
               
                 Physical properties of laminated glass 
                 Particle concentration 
                 0.94 
                 0.94 
                 0.94 
                 0.94 
                 0.94 
               
               
                   
                 (% by weight) 
               
               
                   
                 Tv (%) 
                 75.5 
                 75.3 
                 75.3 
                 75.2 
                 75.1 
               
               
                   
                 Tir (%) 
                 65.0 
                 65.0 
                 65.0 
                 65.0 
                 65.0 
               
               
                   
               
            
           
         
       
     
     EXAMPLE 16 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that as a dispersant, polyoxypropylene alkylether phosphate ester (in the general formula (1), R 1  represented a 2-ethylhexyl group having 8 carbon atoms, R 2  represented a propylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a 2-ethylhexyl group and R 5  represented a propylene group, the HLB value was 9.4, and “n” was an integer of 1 or more) was used instead of polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a 2-ethylhexyl group having 8 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a 2-ethylhexyl group and R 5  represented an ethylene group, the HLB value was 10, and “n” was an integer of 1 or more). 
     EXAMPLE 17 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 16, except that polyoxybuthylene alkylether phosphate ester (in the general formula (1), R 1  represented a 2-ethylhexyl group having 8 carbon atoms, R 2  represented an buthylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a 2-ethylhexyl group and R 5  represented an buthylene group, the HLB value was 8.8, and “n” was an integer of 1 or more) was used as a dispersant. 
     &lt;Evaluation&gt; 
     The zinc oxide fine particle dispersions and the laminated glasses obtained in Examples 16 to 17 were evaluated in the same manner as in Example 1. 
     Table 4 shows the results. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 Example 16 
                 Example 17 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Dispersant 
                 R 1  in general formula (1) 
                 2-ethylhexyl 
                 2-ethylhexyl 
               
               
                   
                   
                 group 
                 group 
               
               
                   
                 The number of carbon atoms of R 1   
                 8 
                 8 
               
               
                   
                 Alkylene portion of polyoxyalkylene 
                 propylene 
                 butylene 
               
               
                   
                 HLB value 
                 9.4 
                 8.8 
               
               
                 Zinc oxide fine particles containing 
                 Trivalent metal species 
                 gallium 
                 gallium 
               
               
                 trivalent metallic element 
                 Content ratio of trivalent metal 
                 4 
                 4 
               
               
                   
                 (mol %) 
               
            
           
           
               
               
               
               
               
            
               
                 Zinc oxide fine 
                 Composition 
                 Zinc oxide fine particles 
                 30 
                 30 
               
               
                 particle dispersion 
                 (parts by weight) 
                 Plasticizer (3GO) 
                 267 
                 267 
               
               
                   
                   
                 Dispersant 
                 3 
                 3 
               
               
                   
                 Physical properties 
                 Particle concentration 
                 0.90 
                 0.90 
               
               
                   
                   
                 (% by weight) 
               
               
                   
                   
                 Tv (%) 
                 80.1 
                 79.5 
               
               
                   
                   
                 Tir (%) 
                 82.6 
                 82.5 
               
            
           
           
               
               
               
               
            
               
                 Composition of interlayer film 
                 Zinc oxide fine particle dispersion 
                 12.6 
                 12.6 
               
               
                 for laminated glass 
                 Polyvinyl butyral 
                 100 
                 100 
               
               
                 (parts by weight) 
                 Plasticizer (total amount) 
                 40 
                 40 
               
               
                 Physical properties of laminated glass 
                 Particle concentration 
                 0.89 
                 0.89 
               
               
                   
                 (% by weight) 
               
               
                   
                 Tv (%) 
                 75.3 
                 75.3 
               
               
                   
                 Tir (%) 
                 65.0 
                 64.9 
               
               
                   
               
            
           
         
       
     
     EXAMPLE 18 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 1, except that the blending amount of the zinc oxide fine particle dispersion for producing an interlayer film for a laminated glass was changed to 16.8 parts by weight. 
     EXAMPLE 19 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 18, except that the blending amount of the zinc oxide fine particle dispersion for producing an interlayer film for a laminated glass was changed to 19.3 parts by weight. 
     EXAMPLE 20 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 18, except that the blending amount of a dispersant for producing a zinc oxide fine particle dispersion was changed to 1 part by weight, and the blending amount of the zinc oxide fine particle dispersion for producing an interlayer film for a laminated glass was changed to 12.6 parts by weight. 
     EXAMPLE 21 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 18, except that the blending amount of a dispersant for producing a zinc oxide fine particle dispersion was changed to 10 parts by weight, and the blending amount of the zinc oxide fine particle dispersion for producing an interlayer film for a laminated glass was changed to 12.6 parts by weight. 
     EXAMPLE 22 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 18, except that the blending amount of a plasticizer for producing a zinc oxide fine particle dispersion was changed to 200 parts by weight, 67 parts by weight of ethanol was blended instead, and the blending amount of the zinc oxide fine particle dispersion for producing an interlayer film for a laminated glass was changed to 12.6 parts by weight. 
     EXAMPLE 23 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 22, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a tridecyl group having 13 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a tridecyl group and R 5  represented an ethylene group, the HLB value was 9.4, and “n” was an integer of 1 or more) was used as a dispersant. 
     EXAMPLE 24 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 18, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a 2-ethylhexyl group having 8 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a 2-ethylhexyl group and R 5  represented an ethylene group, the HLB value was 10.0, and “n” was an integer of 1 or more) was used as a dispersant, and zinc oxide fine particles (volume average particle diameter: 20 nm) containing 2 mol % of gallium as a trivalent metallic element were used, and the blending amount of the zinc oxide fine particle dispersion for producing an interlayer film for a laminated glass was changed to 14.0 parts by weight. 
     EXAMPLE 25 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 24, except that zinc oxide fine particles containing 6 mol % of gallium as a trivalent metallic element were used, and the blending amount of the zinc oxide fine particle dispersion for producing an interlayer film for a laminated glass was changed to 15.4 parts by weight. 
     EXAMPLE 26 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 24, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a 2-ethylhexyl group having 8 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a 2-ethylhexyl group and R 5  represented an ethylene group, the HLB value was 9.2, and “n” was an integer of 1 or more) was used as a dispersant, and zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of gallium as a trivalent metallic element were used, and the blending amount of the zinc oxide fine particle dispersion for producing an interlayer film for a laminated glass was changed to 12.6 parts by weight. 
     EXAMPLE 27 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 24, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of gallium as a trivalent metallic element and zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element were used, tetraethylene glycol di-2-ethylhexanoate (4GO) was used as the plasticizer for producing a zinc oxide fine particle dispersion, and the blending amount of the zinc oxide fine particle dispersion for producing an interlayer film for a laminated glass was changed to 12.6 parts by weight. 
     EXAMPLE 28 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 24, except that zinc oxide fine particles (volume average particle diameter: 20 nm) containing 4 mol % of gallium as a trivalent metallic element were used, tetraethylene glycol diheptanoate (4G7) was used as the plasticizer for producing a zinc oxide fine particle dispersion, and the blending amount of the zinc oxide fine particle dispersion for producing an interlayer film for a laminated glass was changed to 12.6 parts by weight. 
     &lt;Evaluation&gt; 
     The zinc oxide fine particle dispersions and the laminated glasses obtained in Examples 18 to 28 were evaluated in the same manner as in Example 1. 
     Table 5 shows the results. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 5 
               
               
                   
                   
               
             
            
               
                   
                 Example 18 
                 Example 19 
                 Example 20 
                 Example 21 
                 Example 22 
                 Example 23 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Dispersant 
                 R 1  in general formula (1) 
                 2-ethylhexyl 
                 2-ethylhexyl 
                 2-ethylhexyl 
                 2-ethylhexyl 
                 2-ethylhexyl 
                 tridecyl 
               
               
                   
                   
                 group 
                 group 
                 group 
                 group 
                 group 
                 group 
               
               
                   
                 The number of carton atoms 
                 8 
                 8 
                 8 
                 8 
                 8 
                 13 
               
               
                   
                 of R 1   
               
               
                   
                 Alkylene portion of 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
               
               
                   
                 polyoxyalkylene 
               
               
                   
                 HLB value 
                 10.0 
                 10.0 
                 10.0 
                 10.0 
                 10.0 
                 9.4 
               
               
                 Zinc oxide fine particles 
                 Trivalent metal species 
                 gallium 
                 gallium 
                 gallium 
                 gallium 
                 gallium 
                 gallium 
               
               
                 containing trivalent 
                 Content ratio of trivalent 
                 4 
                 4 
                 4 
                 4 
                 4 
                 4 
               
               
                 metallic element 
                 metal (mol %) 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Zinc oxide fine 
                 Composition 
                 Zinc oxide fine particles 
                 30 
                 30 
                 30 
                 30 
                 30 
                 30 
               
               
                 particle 
                 (parts by 
                 Plasticizer (3GO) 
                 267 
                 267 
                 267 
                 267 
                 200 
                 200 
               
               
                 dispersion 
                 weight) 
                 Dispersant 
                 3 
                 3 
                 1 
                 10 
                 3 
                 3 
               
               
                   
                   
                 Ethanol 
                 — 
                 — 
                 — 
                 — 
                 67 
                 67 
               
               
                   
                 Physical 
                 Particle concentration 
                 0.90 
                 0.90 
                 0.90 
                 0.90 
                 0.90 
                 0.90 
               
               
                   
                 properties 
                 (% by weight) 
               
               
                   
                   
                 Tv (%) 
                 81.7 
                 81.7 
                 81.7 
                 81.5 
                 81.9 
                 81.7 
               
               
                   
                   
                 Tir (%) 
                 82.7 
                 82.7 
                 82.7 
                 82.7 
                 82.8 
                 82.7 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Composition of 
                 Zinc oxide fine particle 
                 16.8 
                 19.3 
                 12.6 
                 12.6 
                 12.6 
                 12.6 
               
               
                 interlayer film for 
                 dispersion 
               
               
                 laminated glass 
                 Polyvinyl butyral 
                 100 
                 100 
                 100 
                 100 
                 100 
                 100 
               
               
                 (parts by weight) 
                 Plasticizer (total amount) 
                 40 
                 40 
                 40 
                 40 
                 40 
                 40 
               
               
                 Physical properties 
                 Particle concentration 
                 1.18 
                 1.36 
                 0.90 
                 0.87 
                 0.89 
                 0.89 
               
               
                 of laminated glass 
                 (% by weight) 
               
               
                   
                 Tv (%) 
                 72.4 
                 70.2 
                 75.8 
                 76.0 
                 76.2 
                 76.2 
               
               
                   
                 Tir (%) 
                 62.3 
                 60.9 
                 64.8 
                 64.9 
                 65.0 
                 65.0 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Example 24 
                 Example 25 
                 Example 26 
                 Example 27 
                 Example 28 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 Dispersant 
                 R 1  in general formula (1) 
                 2-ethylhexyl 
                 2-ethylhoxyl 
                 2-ethylhexyl 
                 2-ethylhexyl 
                 2-ethylhexyl 
               
               
                   
                   
                   
                 group 
                 group 
                 group 
                 group 
                 group 
               
               
                   
                   
                 The number of carton atoms 
                 8 
                 8 
                 8 
                 8 
                 8 
               
               
                   
                   
                 of R 1   
               
               
                   
                   
                 Alkylene portion of 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
                 ethylene 
               
               
                   
                   
                 polyoxyalkylene 
               
               
                   
                   
                 HLB value 
                 10.0 
                 10.0 
                 9.2 
                 10.0 
                 10.0 
               
               
                   
                 Zinc oxide fine particles 
                 Trivalent metal species 
                 gallium 
                 gallium 
                 gallium 
                 gallium 
                 gallium 
               
               
                   
                 containing trivalent 
                 Content ratio of trivalent 
                 2 
                 6 
                 4 
                 4 
                 4 
               
               
                   
                 metallic element 
                 metal (mol %) 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Zinc oxide fine 
                 Composition 
                 Zinc oxide fine particles 
                 30 
                 30 
                 30 
                 30 
                 30 
               
               
                   
                 particle 
                 (parts by 
                 Plasticizer (3GO) 
                 267 
                 267 
                 267 
                 267 
                 267 
               
               
                   
                 dispersion 
                 weight) 
                   
                   
                   
                   
                 (4GO) 
                 (4G7) 
               
               
                   
                   
                   
                 Dispersant 
                 3 
                 3 
                 3 
                 3 
                 3 
               
               
                   
                   
                   
                 Ethanol 
                 — 
                 — 
                 — 
                 — 
                 — 
               
               
                   
                   
                 Physical 
                 Particle concentration 
                 1.00 
                 1.10 
                 0.90 
                 0.90 
                 0.90 
               
               
                   
                   
                 properties 
                 (% by weight) 
               
               
                   
                   
                   
                 Tv (%) 
                 80.6 
                 79.9 
                 81.6 
                 81.5 
                 81.1 
               
               
                   
                   
                   
                 Tir (%) 
                 82.7 
                 82.7 
                 82.7 
                 82.7 
                 82.7 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 Composition of 
                 Zinc oxide fine particle 
                 14.0 
                 15.4 
                 12.6 
                 12.6 
                 12.6 
               
               
                   
                 interlayer film for 
                 dispersion 
               
               
                   
                 laminated glass 
                 Polyvinyl butyral 
                 100 
                 100 
                 100 
                 100 
                 100 
               
               
                   
                 (parts by weight) 
                 Plasticizer (total amount) 
                 40 
                 40 
                 40 
                 40 
                 40 
               
               
                   
                 Physical properties 
                 Particle concentration 
                 0.99 
                 1.09 
                 0.89 
                 0.89 
                 0.89 
               
               
                   
                 of laminated glass 
                 (% by weight) 
               
               
                   
                   
                 Tv (%) 
                 75.4 
                 74.9 
                 76.0 
                 75.9 
                 75.7 
               
               
                   
                   
                 Tir (%) 
                 64.9 
                 64.9 
                 64.9 
                 64.9 
                 64.9 
               
               
                   
                   
               
            
           
         
       
     
     EXAMPLE 29 
     (1) Production of a Zinc Oxide Fine Particle Dispersion 
     An amount of 30 parts by weight of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, 267 parts by weight of triethylene glycol di-2-ethylhexanoate as a plasticizer, 3 parts by weight of polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a 2-ethylhexyl group having 8 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a 2-ethylhexyl group and R 5  represented an ethylene group, the HLB value was 10.0, and “n” was an integer of 1 or more) as a dispersant, and 1125 parts by weight of zirconia beads were mixed to obtain a mixture. The obtained mixture was dispersed for four hours by using a batch-type bead mill to produce a zinc oxide fine particle dispersion. 
     (2) Production of a Tin-Doped Indium Oxide Fine Particle Dispersion 
     An amount of 30 parts by weight of tin-doped indium oxide fine particles, 267 parts by weight of triethylene glycol di-2-ethylhexanoate as a plasticizer, 3 parts by weight of polyphosphate salt as a dispersant, and 1125 parts by weight of zirconia beads were mixed to obtain a mixture. The obtained mixture was dispersed for four hours by using a batch-type bead mill to produce a tin-doped indium oxide fine particle dispersion. 
     (3) Production of an Interlayer Film for a Laminated Glass 
     An amount of 8.82 parts by weight of the obtained zinc oxide fine particle dispersion, 0.70 parts by weight of the obtained tin-doped indium oxide fine particle dispersion, and 100 parts by weight of a polyvinyl butyral resin as a thermoplastic resin were mixed. Triethylene glycol di-2-ethylhexanoate was further added as a plasticizer in such a manner that the total amount of the plasticizer reached 40 parts by weight with respect to 100 parts by weight of the thermoplastic resin, and the mixture was mixed to produce a thermoplastic resin composition. 
     The obtained thermoplastic resin composition was molded by using a counter-rotating twin-screw extruder to produce an interlayer film for a laminated glass having a thickness of 760 μm. 
     (4) Production of a Laminated Glass 
     The obtained interlayer film for a laminated glass was interposed between two sheets of clear float glass (5 cm in height×5 cm in width×2.5 mm in thickness). The laminated body was placed in a vacuum bag and the vacuum bag was deaerated to 933.2 hPa. Subsequently, the vacuum bag was heated until the interior temperature of the vacuum bag reached 100° C. and maintained at the temperature for 20 minutes. The vacuum bag was naturally cooled and the temporarily-bonded laminated glass was taken out. The temporarily-bonded laminated glass was autoclaved at a temperature of 135° C. and at a pressure of 1.2 MPa for 20 minutes to produce a laminated glass. 
     EXAMPLE 30 
     An interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 29, except that the blending amount of the zinc oxide fine particle dispersion was changed to 7.00 parts by weight and the blending amount of the tin-doped indium oxide fine particle dispersion was changed to 1.40 parts by weight for producing an interlayer film for a laminated glass. 
     EXAMPLE 31 
     An interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 29, except that the blending amount of the zinc oxide fine particle dispersion was changed to 0.70 parts by weight and the blending amount of the tin-doped indium oxide fine particle dispersion was changed to 2.80 parts by weight for producing an interlayer film for a laminated glass. 
     &lt;Evaluation&gt; 
     The laminated glasses obtained in Examples 29 to 31 were evaluated in the same manner as in Example 1. 
     Table 6 shows the results. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 6 
               
               
                   
                   
               
               
                   
                 Example 29 
                 Example 30 
                 Example 31 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Composition of interlayer film 
                 Zinc oxide fine particle dispersion 
                 8.82 
                 7.00 
                 0.70 
               
               
                 for laminated glass 
                 Tin-doped indium oxide 
                 0.70 
                 1.40 
                 2.80 
               
               
                 (parts by weight) 
                 fine particle dispersion 
               
               
                   
                 Polyvinyl butyral 
                 100 
                 100 
                 100 
               
               
                   
                 Plasticizer (total amount) 
                 40 
                 40 
                 40 
               
               
                 Physical properties of 
                 Concentration of zinc oxide fine particles 
                 0.63 
                 0.50 
                 0.05 
               
               
                 laminated glass 
                 (% by weight) 
               
               
                   
                 Concentration of tin-doped indium oxide fine 
                 0.05 
                 0.10 
                 0.20 
               
               
                   
                 particles (% by weight) 
               
               
                   
                 Tv (%) 
                 79.3 
                 74.6 
                 73.7 
               
               
                   
                 Tir (%) 
                 61.1 
                 57.4 
                 51.2 
               
               
                   
               
            
           
         
       
     
     EXAMPLE 32 
     (1) Production of a Zinc Oxide Fine Particle Dispersion 
     An amount of 30 parts by weight of zinc oxide fine particles containing 4 mol % of gallium as a trivalent metallic element, 267 parts by weight of triethylene glycol di-2-ethylhexanoate as a plasticizer, 3 parts by weight of polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a 2-ethylhexyl group having 8 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a 2-ethylhexyl group and R 5  represented an ethylene group, the HLB value was 10.0, and “n” was an integer of 1 or more) as a dispersant, and 1125 parts by weight of zirconia beads were mixed to obtain a mixture. The obtained mixture was dispersed for four hours by using a batch-type bead mill to produce a zinc oxide fine particle dispersion. 
     (2) Production of an Interlayer Film for a Laminated Glass 
     An amount of 16.0 parts by weight of the obtained zinc oxide fine particle dispersion, and 100 parts by weight of a polyvinyl butyral resin (PVB: average polymerization degree of 1700, butyralization degree of 68.5 mol %, 30.6 mol % of hydroxyl group, and 0.9 mol % of acetyl group) as a thermoplastic resin were mixed. Triethylene glycol di-2-ethylhexanoate was further added as a plasticizer in such a manner that the total amount of the plasticizer reached 40 parts by weight with respect to 100 parts by weight of the thermoplastic resin, and the mixture was mixed to produce a thermoplastic resin composition (a skin layer). 
     On the other hand, triethylene glycol di-2-ethylhexanoate was added as a plasticizer in such a manner that the total amount of the plasticizer reached 60 parts by weight with respect to 100 parts by weight of a polyvinyl butyral resin (PVB: average polymerization degree of 2450, butyralization degree of 65.5 mol %, 20. 1 mol % of hydroxyl group, and 13.4 mol % of acetyl group), and the mixture was mixed to produce another thermoplastic composition (an intermediate layer). 
     The obtained thermoplastic resin compositions (the skin layer and the intermediate layer) were molded by using a counter-rotating twin-screw extruder to produce an interlayer film for a laminated glass comprising an intermediate layer (thickness of 100 μm) sandwiched between the skin layers (thickness of 330 μm each). 
     (3) Production of a Laminated Glass 
     The obtained interlayer film for a laminated glass was interposed between two sheets of clear float glass (5 cm in height×5 cm in width×2.5 mm in thickness). The laminated body was placed in a vacuum bag and the vacuum bag was deaerated to 933.2 hPa. Subsequently, the vacuum bag was heated until the interior temperature of the vacuum bag reached 100° C. and maintained at the temperature for 20 minutes. The vacuum bag was naturally cooled and the temporarily-bonded laminated glass was taken out. The temporarily-bonded laminated glass was autoclaved at a temperature of 135° C. and at a pressure of 1.2 MPa for 20 minutes to produce a laminated glass. 
     EXAMPLE 33 
     A zinc oxide fine particle dispersion, an interlayer film for a laminated glass, and a laminated glass were produced in the same manner as in Example 32, except that polyoxyethylene alkylether phosphate ester (in the general formula (1), R 1  represented a tridecyl group having 13 carbon atoms, R 2  represented an ethylene group, R 3  represented a mixture of a hydrogen atom and R 4 (OR 5 ) n —, wherein R 4  represented a tridecyl group and R 5  represented an ethylene group, the HLB value was 9.4, and “n” was an integer of 1 or more) was used as a dispersant. 
     &lt;Evaluation&gt; 
     The laminated glasses obtained in Examples 32 to 33 were evaluated in the same manner as in Example 1. 
     Table 7 shows the results. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 7 
               
               
                   
                   
               
               
                   
                 Example 32 
                 Example 33 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Dispersant 
                 R 1  in general formula (1) 
                 2-ethylhexyl 
                 tridecyl 
               
               
                   
                   
                 group 
                 group 
               
               
                   
                 The number of carbon atoms of R 1   
                 8 
                 13 
               
               
                   
                 Alkylene portion of polyoxyalkylene 
                 ethylene 
                 ethylene 
               
               
                   
                 HLB value 
                 10.0 
                 9.4 
               
               
                 Zinc oxide fine particles containing trivalent 
                 Trivalent metal species 
                 gallium 
                 gallium 
               
               
                 metallic element 
                 Content ratio of trivalent metal 
                 4 
                 4 
               
               
                   
                 (mol %) 
               
            
           
           
               
               
               
               
               
            
               
                 Zinc oxide fine 
                 Composition 
                 Zinc oxide fine particles 
                 30 
                 30 
               
               
                 particle dispersion 
                 (parts by weight) 
                 Plasticizer (3GO) 
                 267 
                 267 
               
               
                   
                   
                 Dispersant 
                 3 
                 3 
               
               
                   
                 Physical properties 
                 Particle concentration 
                 0.90 
                 0.90 
               
               
                   
                   
                 (% by weight) 
               
               
                   
                   
                 Tv (%) 
                 81.7 
                 81.5 
               
               
                   
                   
                 Tir (%) 
                 82.7 
                 82.7 
               
            
           
           
               
               
               
               
            
               
                 Composition of interlayer film 
                 Zinc oxide fine particle dispersion 
                 16.0 
                 16.0 
               
               
                 for laminated glass (skin layer) 
                 Polyvinyl butyral 
                 100 
                 100 
               
               
                 (parts by weight) 
                 Plasticizer (total amount) 
                 40 
                 40 
               
               
                 Physical properties of laminated glass 
                 Tv (%) 
                 76.1 
                 76.1 
               
               
                   
                 Tir (%) 
                 64.9 
                 64.9 
               
               
                   
               
            
           
         
       
     
     INDUSTRIAL APPLICABILITY 
     The present invention makes it possible to provide an interlayer film for a laminated glass in which zinc oxide fine particles are excellently dispersed, a laminated glass, and a zinc oxide fine particle dispersion.