Abstract:
A new epoxy resin represented by following general formula comprising, possessing one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular, and said epoxy resin is useful for photo curing method. 
     
       
                 
         
             
             
         
       
       
         wherein 
         E: epoxy resin residue 
         c: 1, 2, 3 
         d: 1, 2,3 
         c+d=4

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an epoxy resin which is useful for photo curing, an epoxy resin composition and an epoxy resin cured product, in particular, a new epoxy resin, an epoxy resin compound and an epoxy resin cured product of the present invention are useful for a paint, an adherent, a photo art, a sealing agent, a molding agent and a material for electric or electronic photo circuit. 
       DESCRIPTION OF THE PRIOR ART 
       [0002]    In general, an epoxy resin is widely used for electronic parts, electric machine and tools, car parts, FRP or sport supplies because of excellent adhesive property, heat resistance and molding ability. A cured product of epoxy resin can be obtained by heating an epoxy resin using a curing agent. As a curing agent to be used, amine curing agents or acid anhydride agents can be mentioned. However, term for usable of an epoxy resin composition that uses these curing agents is limited because curing reaction progresses gradually at room temperature and viscosity becomes thicker. 
         [0003]    By a photo curing method which cures epoxy resin using a photo polymerization initiator, an epoxy resin composition having excellently better preservation stability than using said amine agents or photo polymerization initiator can be obtained, because curing reaction does not cause as long as photo energy is not irradiated. 
         [0004]    A photo curing method of an epoxy resin is characterized to blend a photo polymerization initiator, and a composition which provides pliability and improves reacting ability by blending polyols is general (not patent document 1). Since reacting speed of epoxy group of epoxy resin with primary hydroxyl group of polyols is faster than reaction speed of epoxy groups each other, reacting ability is improved (not patent document 2). However, if the molecular weight of the blended polyols is low, problem of volatilization at curing process or problem of unsaturated curing by moisture absorption are pointed out. Further, when the molecular weight of the blended polyols is high, problem of deterioration of heat resistance caused by decrease of crosslinking density is caused. 
         [0005]    Not patent document 1: The Dow Chemical company “CYRACURE Cycloaliphatic Epoxides Cationic UV Cure” 
         [0006]    Not patent document 2: “Hikari Oyo Gijyutsu•Zairyo Jiten” 
       OBJECT OF THE INVENTION 
       [0007]    The inventors of the present invention investigated a new epoxy resin that is useful to a photo curing method, and have found out that a new epoxy resin possesses one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular represented by specific general formula can provide a epoxy resin composition or epoxy resin cured product not only whose reacting ability is improved and pliability is provided, but also problems of volatilization, higher moisture absorption and lower heat resistance, which are pointed out in conventional polyols blended epoxy resin composition or epoxy resin cured product, are dissolved, and accomplished present invention. And the object of the present invention is to provide an epoxy resin, an epoxy resin composition and epoxy resin cured product which can dissolve the problems that conventional epoxy resin, epoxy resin composition and epoxy resin cured product have, that is, problems of volatilization, moisture absorption and heat resistance caused by blending polyols. 
         [0008]    Above mentioned object is accomplished by using a new epoxy resin represented by general formula 1 comprising, possessing one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular. 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    a: 0, 1, 2, 3, . . .
 
b: 0, 1, 2, 3, . . .
 
c: 0, 1, 2, 3, . . .
 
d: 1, 2, 3, . . .
 
         [0009]    wherein a+c: 1, 2, 3, . . . 
         [0000]    l: 1, 2, 3, . . .
 
m: 0, 1
 
(EP) is a reaction residue of epoxy resin and is specifically represented by general formulae 2 and 3.
 
(E) is a reaction residue of epoxy resin and is specifically represented by general formulae 4 and 5.
 
(X) is a carbon alone or hydrocarbon group and can contain nitrogen atom, phosphorus atom, oxygen atom or sulfur atom.
 
(A) is a hydrocarbon group of acid anhydride residue and can contain nitrogen atom, phosphorus atom, oxygen atom or sulfur atom.
 
R is a hydrogen or hydrocarbon group and can contain nitrogen atom, phosphorus atom, oxygen atom or sulfur atom.
 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    n: 1, 2, 3, . . .
 
Y is a hydrocarbon group and can contain nitrogen atom, phosphorus atom, oxygen atom or sulfur atom, further can be a structure of linear, branch, ring, aromatic ring or heterocyclic.
 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    q: 1, 2, 3, . . .
 
r: 1,2
 
Q is a hydrocarbon group and can contain nitrogen atom, phosphorus atom, oxygen atom or sulfur atom, further can be a structure of linear, branch, ring, aromatic ring or heterocyclic.
 
Z indicates —O—, —COO—, —N═
 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    u: 0, 1, 2, 3, . . .
 
t: 1, 2, 3, . . .
 
Y′ is a hydrocarbon group and can contain nitrogen atom, phosphorus atom, oxygen atom or sulfur atom, further can be a structure of linear, branch, ring, aromatic ring or heterocyclic.
 
         [0000]    
       
                 
         
             
             
         
       
     
         [0000]    w: 1, 2
 
x: 0, 1, 2, 3, . . .
 
y: 1, 2, 3, . . .
 
Q′ is a hydrocarbon group and can contain nitrogen atom, phosphorus atom, oxygen atom or sulfur atom, further can be a structure of linear, branch, ring, aromatic ring or heterocyclic.
 
Z′ indicates —O—, —COO—, —N═.
 
     
    
     
       BRIEF ILLUSTRATION OF DRAWINGS 
         [0010]      FIG. 1  shows molecular weight distribution by GPC of epoxy resin obtained in Example 1. 
           [0011]      FIG. 2  shows measuring results of FTIR of epoxy resin obtained in Example 1. 
           [0012]      FIG. 3  shows molecular weight distribution by GPC of epoxy resin obtained in Example 5. 
           [0013]      FIG. 4  shows measuring results of FTIR of epoxy resin obtained in Example 5. 
           [0014]      FIG. 5  shows molecular weight distribution by GPC of epoxy resin obtained in Example 6. 
           [0015]      FIG. 6  shows measuring results of FTIR of epoxy resin obtained in Example 6. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Details of the present invention will be illustrated as follows. 
         [0017]    New epoxy resin in the present invention is represented by general formula 1, which possesses one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular. 
         [0018]    As one method to prepare the new epoxy resin of present invention, a method to react all carboxyl groups of the compound which has one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular with an epoxy group. 
         [0019]    As a specific example of the compound which has one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular, glycolic acid, dimethylolpropionic acid or dimethylolbutanoic acid can be mentioned. Further, said compound can be obtained by reacting alcohols possessing 2 or more than 2 primary hydroxyl groups in one molecular with carboxylic acids containing acid anhydride, however, is not limited to these compounds and can be used by mixing 2 or more of these compounds. 
         [0020]    As a epoxy resin which reacts with the compound which has one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular, public known epoxy resin can be used, and specifically, BPA epoxy resins of Tohto Kasei Co., Ltd, such as EPOTOHTO YD-128, EPOTOHTO YD-8125, EPOTOHTO YD-127, EPOTOHTO YD-825GS, EPOTOHTO YD-134, EPOTOHTO YD-011, EPOTOHTO YD-012, EPOTOHTO YD-013, EPOTOHTO YD-901, EPOTOHTO YD-902 or EPOTOHTO YD-903, BPF epoxy resins such as EPOTOHTO YDF-170, EPOTOHTO YDF-8170, EPOTOHTO YDF-870GS, EPOTOHTO YDF-2001 or EPOTOHTO YDF-2004, novolac epoxy resins such as EPOTOHTO YDPN-638, EPOTOHTO YDCN-701, EPOTOHTO YDCN-702 or EPOTOHTO YDCN-703, aralkyl novolac epoxy resins such as ESN-175, ESN-375 or ESN 485, amine epoxy resins such as EPOTOHTO YH-434 or YH-434L, glycydil ester epoxy resins such as EPOTOHTO YD-171 or YD-172, aliphatic epoxy resins such as EPOTOHTO YH-300, EPOTOHTO ZX-1542, EPOTOHTO PG-207 or EPOTOHTO PG-207GS, alicyclic epoxy resin such as EPOTOHTO ST-3000 or EPOTOHTO ZX-1658, EPOTOHTO ZX-1658GS, EPOTOHTO ZX-1715, HBPA-DGE, DCPD-EP or TCPD-EP which are products of Maruzen Petrochemical Co., Ltd., YX8000 or YX8034 which are products of Japan Epoxy resin Co., Ltd., CELLOXIDE 2021, CELLOXIDE 2021A, CELLOXIDE 2021P or CELLOXIDE 3000 of Daicel Chemical Industries, Ltd or hydrogenated dimer acid epoxy resin can be mentioned, however, is not limited to these compounds and can be used together with. 
         [0021]    Reaction is carried out by blending more than 1.1 mol, desirably, more than 2.0 mol, more desirably more than 3.0 mol of epoxy group to 1.0 mol of carboxyl group. 
         [0022]    Reaction between the compound which has one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular and epoxy resin can be carried out by public known method for synthesis. That is, the reaction can be carried out by blending the compound which has one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular and epoxy resin and heating. Inactive solvent or catalyst can be used, if necessary. Reaction temperature is from 50° C. to 200° C., desirably from 80° C. to 180° C. End point of the reaction can be decided by confirming vanish of carboxyl group by an instrumental analysis or by confirming degree of acid by chemical analysis. Reaction time is from 1 hour to 6 hours. 
         [0023]    As a usable inactive solvent, solvent that does not have hydroxyl group is desirable, and specifically, benzene, toluene or xylene can be mentioned, however, is not intending to be limited to these solvents and can be used together with. 
         [0024]    As a usable catalyst, imidazoles such as 2-methylimidazol or 2-ethyl-4-methylimidazol, phosphines such as triphenyl phosphine, tritolyl phosphine, tris(2,6-dimethoxyphenyl)phosphine or phosphonium salts such as tetrabutylphosphoniumbromide, tetrabutylphosphoniumiodide, ethyltriphenylphosphoniumbromide or ethyltriphenylphosphoniumiodide can be mentioned, however, is not intending to be limited to these solvents and can be used together with. 
         [0025]    The compound which has one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular can be also obtained by reacting alcohols having two or more than two primary hydroxyl group in one molecular with carboxylic acids containing acid anhydride. 
         [0026]    At the reaction, the compound which has one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular can be obtained by carrying out the reaction so as the acid anhydride equivalent to 1 equivalent of primary hydroxyl group to be smaller than 1 equivalent. If the reaction is carried out by 1 equivalent of acid anhydride to 1 equivalent of primary hydroxyl group, the epoxy resin of this invention can not be obtained because the primary hydroxyl group does not remain. Further, if the equivalent of acid anhydride to 1 equivalent of primary hydroxyl group is larger than 1 equivalent, there is possibility of gelation at the reaction with epoxy resins because acid anhydride remains. Desirable equivalent of acid anhydride is smaller than 1 and more than 0.5 equivalent. By adjusting equivalent of primary hydroxyl group and equivalent of acid anhydride, primary hydroxyl group can be adjusted voluntarily. 
         [0027]    As an alcohol having two or more than two primary hydroxyl group in one molecular, divalent alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, neopentylglycol, 1,6-hexane diol, 1, 8-octane diol, cyclohexanedimethanol or spiroglycol, trivalent alcohols such as glycerin, trimethylolethane, trimethylolpropane or hexanetriol, polyvalent alcohols such as sorbitol, sucrose, pentaerythritol, ditrimethylolethane, ditrimethylolpropane or dipentaerythritol, alkyleneoxide adduct of these alcohols can be mentioned, however, is not intending to be limited to these compounds, and these compounds can be used together with. 
         [0028]    As an acid anhydride, itaconic acid anhydride, citraconic acid anhydride, 2-carboxy-ethyl-methyl-phosphinic acid anhydride, phthalic acid anhydride, hexahidrophthalic acid anhydride, tetrahydrophthalic acid anhydride, methylhexahydrophthalic acid anhydride, methyltetrahydro phthalic acid anhydride, methylnadic acid anhydride, dodecylsuccinic acid anhydride, pyromellitic acid anhydride, benzophenonetetracarboxylic acid anhydride, ethylene glycolbis (anhytrotrimellit), methylcyclohexene tetracarboxilic acid anhydride, trimellitic acid anhydride, naphthalic acid anhydride or acid anhydride disclosed in JP H6-80765 publication can be mentioned, however, is not intending to be limited to these compounds, and these compounds can be used together with. 
         [0029]    Reaction of alcohols with carboxylic acid containing acid anhydride can be progressed by blending prescribed amount and heating. At the reaction, inactivated solvent or catalyst can be used, if necessary. Reaction temperature is from 50° C. to 180° C., desirably from 80° C. to 150° C. End point of the reaction can be decided by confirming vanish of acid anhydride by an instrumental analysis or by confirming degree of acid by chemical analysis. Reaction time is from 1 hour to 6 hours. 
         [0030]    As an inactivated solvent which is usable at the reaction, it is necessary that the reacted product can be dissolved, and specifically, benzene, toluene, xylene or methylisobutylketone can be mentioned. However, is not intending to be limited to these compounds, and these compounds can be used together with. 
         [0031]    By reacting a compound processing two or more carboxyl group in one molecular with epoxy resins possessing one or more than one primary hydroxyl group and two or more than two epoxy group in one molecular, a new epoxy resin which has one or more than one primary hydroxyl group and one or more than one epoxy group in one molecular can be synthesized too. 
         [0032]    As a compound possessing two or more than two carboxyl group in one molecular, oxalic acid, malonic acid, fumaric acid, sussinic acid, glutaric acid, adipic acid, phthalic acid, maleic acid, sebacic acid, itaconic acid, citraconic acid, cyclohexanetricarboxylic acid or naphthalene dicarboxylic acid can be mentioned. Further, the compound which has more than two carboxyl group in one molecular can be also synthesized by reacting afore mentioned alcohols possessing two or more than two primary hydroxyl group in one molecular with carboxylic acids containing acid anhydride. At the reaction, primary hydroxyl group can be remained. 
         [0033]    An epoxy resin possessing one or more than one primary hydroxyl group in one molecular can be obtained by adjusting amount of alkali, amount of catalyst, reaction temperature or reaction time so as to add epoxy group remaining primary hydroxyl group at the epoxylization of a compound possessing two or more than two primary hydroxyl group. 
         [0034]    A compound possessing two or more than two carboxyl group in one molecular and an epoxy resin possessing one or more than one primary hydroxyl group and two or more than two epoxy group in one molecular can be reacted by public known method. That is, blending prescribed amount of these two compounds and by heating. At the reaction, inactivated solvent or catalyst can be used, if necessary. Reaction temperature is from 50° C. to 200° C., desirably from 80° C. to 180° C. End point of the reaction can be decided by confirming vanish of carboxyl group by an instrumental analysis or by confirming degree of acid by chemical analysis. Reaction time is from 1 hour to 6 hours. 
         [0035]    Epoxy resin composition of the present invention is adjusted so as equivalent of epoxy group to 1 equivalent of primary hydroxyl group to be within 5 to 50 range by blending new epoxy resin of present invention and/or other epoxy resin. By this adjustment, high reacting ability and excellent heat resistance of cured product are accomplished. 
         [0036]    If equivalent of epoxy resin to equivalent of primary hydroxyl group is smaller than 5 or more than 50, heat resistance is deteriorated. 
         [0037]    As a curing agent usable for an epoxy resin composition of the present invention, a photo polymerization initiator can be mentioned. As a specific example of a photo polymerization initiator, onium salts such as Lewis acid, Br ønsted acid, sulfonium salt, iodonium salt or diazonium salt can be mentioned. Among these compounds sulfonium salt is desirable, and among sulfonium salts, aromatic sulfonium salt is more desirable. Specifically, SANAIDO SI-60L, SANAIDO SI-80L or SANAIDO SI-100L (products of Sanshin Chemical Industry Co., Ltd.), ADEKA OPTOMER-SP-150 or ADEKA OPTOMER-SP-170 (products of Adeka Industries Co., Ltd.), CI-5102 (product of Nippon Soda Co., Ltd.), CYRACURE UV1-6976 or CYRACURE UV1-6992 (products of The Dow Chemical Co., Ltd.) can be mentioned. However, is not intending to be limited to these compounds, and these compounds can be used together with. 
         [0038]    Although blending amount of said photo polymerization initiator differs according to light irradiation condition, kind of epoxy resin and amount thereof, kind of photo polymerization initiator or thickness and shape of cured product, from 0.01 weight parts to 10 weight parts to 100 weight parts of epoxy resin. 
         [0039]    The epoxy resin composition of the present invention can blend sensitizer, anti aging agent, stabilizer, plasticizer, wax, leveling agent, filler, pigment, dye, flame retardant, foaming agent, antistatic agent, anti mildew agent, viscosity controlling agent or solvents can be blended besides photo polymerization initiator. Further, epoxy resin besides the new epoxy resin of the present invention can be blended in the range not to spoil the effect of the present invention. 
         [0040]    The epoxy resin cured product of the present invention can be obtained by photo irradiation and/or heating of the epoxy resin composition of the present invention. 
         [0041]    As a light to be irradiated at the curing process of the epoxy resin composition of the present invention, any kind of light which can cure by said photo polymerization initiator can be used according to the kind of photo polymerization initiator. 
         [0042]    In a case when UV light is used as above mentioned light, light source is not restricted, and for example, ordinary UV light irradiation source such as fluorescent lamp or high pressure mercury lamp can be used. Further, as a light source, low pressure mercury lamp, xenon lamp, metal halide lamp, sterilization lamp, lazar light or LE light can be used. 
         [0043]    Although illuminance, irradiation amount and irradiation time of said light differs according to kind and amount of the photo polymerization initiator, and epoxy resin backbone of the present invention, adducts and thickness, can be voluntarily adjusted according to physical property of cured product. 
         [0044]    As carried out ordinary in photo curing method, heat curing can be carried out before and after photo irradiation, and curing can be more progressed. 
         [0045]    By use of epoxy resin composition obtained by the photo polymerization method in which new epoxy resin of the present invention is contained as an essential gradient, epoxy resin composition and epoxy resin cured product that dissolves problems of volatilization, high moisture absorption or lower heat resistance which was the problem of conventional epoxy resin composition and epoxy resin cured product can be obtained. 
       EXAMPLES 
       [0046]    The present invention will be illustrated more in detail according to Examples, however, not intending to limit the scope of claims of the present invention to Examples. 
       Example 1 
       [0047]    34.0 parts of pentaerythritol (number-averaged number of functional group in one molecular; 4, product of Mithubishi Gas Chemicals Company, INC.), 134.3 parts of RIKACID MH-700 (methylhexahydrophthalic acid anhydride, product of New Japan Chemical Co., Ltd.) and 30.0 parts of toluene are poured into a separable flask with a condenser, and heated with stirring in nitrogen gas atmosphere. Acid anhydride group to primary hydroxyl group is 0.799. Reaction is carried out at 130° C., and confirmed that acid anhydride is vanished, then 617.4 parts of HBPA-DGE (hydrogenated BPA epoxy resin, product of Maruzen Petrochemical Co., Ltd.,) is added, heated and homogenized. As a catalyst, 0.1 parts of TPP-BB (n-butyltriphenyl -phosphoniumbromide, product of Hokko Chemical Industry Co., Ltd.) is dissolved in acetone and added. Reaction is carried out at 150° C., and reaction is stopped by confirming that acid number becomes zero. Epoxy equivalent of the obtained epoxy resin is 420.8 g/eq and equivalent of primary hydroxyl group is 3261 g/eq. Molar ratio of epoxy group and primary hydroxyl group is 9.31. Molecular weight distribution by GPC is shown in  FIG. 1  and measuring result of FTIR is shown in  FIG. 2 . 
       Example 2 
       [0048]    Same processes to Example 1 are carried out except changing parts of RIKACID MH-700 to 151.0 parts and parts of HBPA-DGE to 753.1 parts. Acid anhydride group to primary hydroxyl group is 0.899. Epoxy equivalent of the obtained epoxy resin is 381.9 g/eq and equivalent of primary hydroxyl group is 2160 g/eq. Molar ratio of epoxy group and primary hydroxyl group is 24.28. 
       Example 3 
       [0049]    Same processes to Example 1 are carried out except changing parts of RIKACID MH-700 to 159.6 parts and parts of HBPA-DGE to 667.0 parts. Acid anhydride group to primary hydroxyl group is 0.950. Epoxy equivalent of the obtained epoxy resin is 408.9 g/eq and equivalent of primary hydroxyl group is 17212 g/eq. Molar ratio of epoxy group and primary hydroxyl group is 42.09. 
       Example 4 
       [0050]    Same processes to Example 1 are carried out except changing parts of RIKACID MH-700 to 100.7 parts and changing epoxy resin to 280.0 parts of HBPA-DGE and 280.0 parts of CELLOXIDE 2021. Acid anhydride group to primary hydroxyl group is 0.599. Epoxy equivalent of the obtained epoxy resin is 273.5 g/eq and equivalent of primary hydroxyl group is 1734 g/eq. Molar ratio of epoxy group and primary hydroxyl group is 6.34. 
       Example 5 
       [0051]    Same processes to Example 1 are carried out except changing acid anhydride to 167.5 parts of RIKACID HNA-100 (methylnadic acid anhydride) and changing epoxy resin to 491.5 parts of CELLOXIDE 2021 and 216.1 parts of ZX-1658 (epoxidized product of cyclohexanedimethanol, primary hydroxyl group equivalent is 1105 g/eq, product of Tohto Kasei Co., Ltd). Acid anhydride group to primary hydroxyl group is 0.901. Epoxy equivalent of the obtained epoxy resin is 491.5 g/eq and equivalent of primary hydroxyl group is 1734 g/eq. Molar ratio of epoxy group and primary hydroxyl group is 13.11. Molecular weight distribution by GPC is shown in  FIG. 3  and measuring result of FTIR is shown in  FIG. 4 . 
       Example 6 
       [0052]    Same processes to Example 1 are carried out except changing acid anhydride to 184.0 parts of RIKACID HNA-100 and changing epoxy resin to 435.7 parts of CELLOXIDE 2021 and 230.9 parts of ZX-1658. Acid anhydride group to primary hydroxyl group is 1.000. Epoxy equivalent of the obtained epoxy resin is 252.6 g/eq and equivalent of primary hydroxyl group is 4233 g/eq. Molar ratio of epoxy group and primary hydroxyl group is 16.76. Molecular weight distribution by GPC is shown in  FIG. 5  and measuring result of FTIR is shown in  FIG. 6 . 
       Comparative Example 1 
       [0053]    Same processes to Example 1 are carried out except changing acid anhydride to 100.7 parts of RIKACID MH-700 and changing epoxy resin to 459.0 parts of HBPA-DGE. Epoxy equivalent of the obtained epoxy resin is 450.7 g/eq and equivalent of primary hydroxyl group is 1482 g/eq. Molar ratio of epoxy group and primary hydroxyl group is 3.29. 
       Comparative Example 2 
       [0054]    Same processes to Example 1 are carried out except changing acid anhydride to 115.4 parts of RIKACID MH-700 and changing epoxy resin to 528.8 parts of HBPA-DGE. Epoxy equivalent of the obtained epoxy resin is 435.1 g/eq and equivalent of primary hydroxyl group is 2166 g/eq. Molar ratio of epoxy group and primary hydroxyl group is 4.98. 
       Comparative Example 3 
       [0055]    Same processes to Example 1 are carried out except changing acid anhydride to 168.0 parts of RIKACID MH-700 and changing epoxy resin to 699.8 parts of HBPA-DGE. Epoxy equivalent of the obtained epoxy resin is 418.2 g/eq and equivalent of primary hydroxyl group is not existing. 
         [0056]    100 parts of obtained epoxy resins are respectively dissolved in cyclohexanon and 0.5 parts of CYRACURE UVI-6976 (Product of The Dow chemical Company) is blended as a photo polymerization initiator. Said liquid is coated on a releasing film using a bar coater and solvent is removed at 150° C. for 30 minutes, and light is irradiated by 10 mW illuminance and 8 J/cm 2  integrated light amount at 365 nm wave length using Unicure system UVX-01212S1CS01(product of USHIO INC.), lamp type UVL-1500M2-N1, further cured at 150° C. for 60 minutes, then cured product is obtained. 
         [0057]    Cured product is removed from the releasing film and glass transition point is measured by EXSTAR6200DSC (product of SII Nano Technology Inc.). Measuring condition is follows. Temperature is programmed from room temperature to 200° C. by 10° C./min temperature-programming speed, and first changing point at 2 nd  cycle is measured as glass transition point. Results are summarized in Table 1. 
         [0058]    Infra red absorption spectrum is measured by 1760×(product of Perkin Elmer Japan Co., Ltd.). Molecular distribution is measured by liquid chromatography HLC-8120 (product of Tosoh Corporation.). 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                   
                 Comp. 
                 Comp. 
                 Comp. 
               
               
                   
                 Example 1 
                 Example 2 
                 Example 3 
                 Example 4 
                 Example 5 
                 Example 6 
                 Exp. 1 
                 Exp. 2 
                 Exp. 1 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 pentaerythritol 
                 34.0 
                 34.0 
                 34.0 
                 34.0 
                 34.0 
                 34.0 
                 34.0 
                 34.0 
                 34.0 
               
               
                 methylhexahydrophthalic acid 
                 134.3 
                 151.0 
                 159.6 
                 100.7 
                   
                   
                 100.7 
                 115.4 
                 168.0 
               
               
                 anhydride 
               
               
                 methylnadic acid anhydride 
                   
                   
                   
                   
                 165.7 
                 184.0 
               
               
                 toluene 
                 30.0 
                   
                 34.2 
                 15.0 
                 35.2 
                 38.5 
                 23.8 
                 26.4 
                 35.6 
               
               
                 acid anhydride group to primary 
                 0.799 
                 0.899 
                 0.950 
                 0.599 
                 0.901 
                 1.000 
                 0.599 
                 0.687 
                 1.000 
               
               
                 hydroxyl group 
               
               
                 HBPA-DGE 
                 617.4 
                 753.1 
                 667.0 
                 280.0 
                   
                   
                 459.0 
                 528.8 
                 699.8 
               
               
                 CELLOXIDE 2021 
                   
                   
                   
                 280.0 
                 491.5 
                 435.7 
               
               
                 ZX-1658 
                   
                   
                   
                   
                 216.1 
                 230.9 
               
               
                 epoxy equivalent 
                 420.8 
                 381.9 
                 408.9 
                 273.5 
                 234.5 
                 252.6 
                 450.7 
                 435.1 
                 418.2 
               
               
                 primary hydroxyl group 
                 3917 
                 9271 
                 17212 
                 1734 
                 3075 
                 4233 
                 1482 
                 2166 
                 — 
               
               
                 equivalent 
               
               
                 epoxy group to primary 
                 9.31 
                 24.28 
                 42.09 
                 6.34 
                 13.11 
                 16.76 
                 3.29 
                 4.98 
                 — 
               
               
                 hydroxyl group 
               
               
                 DSC Tg (° C.) 
                 94.1 
                 94.7 
                 92.8 
                 131.1 
                 160.6 
                 156.6 
                 87.8 
                 90.5 
                 90.6 
               
               
                   
               
             
          
         
       
     
         [0059]    As clearly understood from comparison of Examples 1-3 with Comparative Examples 1-3, heat resistance of the new epoxy resin which possesses both primary hydroxyl group and epoxy group is improved in photo curing method. Further, it is clearly understood that equivalent ratio of epoxy group and primary hydroxyl group is desirably 5 to 50. As shown in Example 6, when new epoxy resin having a primary hydroxyl group and an epoxy group is synthesized by using epoxy resin having a primary hydroxyl group, heat resistance is improved too. 
       INDUSTRIAL APPLICABILITY 
       [0060]    Since the new epoxy resin of the present invention needs not to blend polyols, problems of compatibility such as separation or white turbidity caused in blending process can be dissolved. In an epoxy resin composition of the present invention, problem caused by migration of polyol to the surface and adsorb humid in air, that is problem of high moisture absorption is also dissolved. Further, since monomer is not existing, problem of volatilization does not cause. Since primary hydroxyl group and epoxy group are existing in one molecular, crosslinking density of cured product becomes high and heat resistance becomes better than that of epoxy resin to which polyol is blended.