Patent Description:
Polyester resins have excellent mechanical characteristics and heat resistance. Also, various physical properties can be imparted to polyester resins by selecting a constituent raw-material monomer. Therefore, polyester resins have been used for paints, adhesives, coating agents, or molded articles and the like. In the polyester resins, however, a functional group contributing to a chemical reaction is generally only a hydroxyl group or a carboxyl group at a polymer terminal. Therefore, it has been known to provide polyester resins with a branched molecular chain for the purpose of an increase of a hydrophilic group contributing to improvement of reactivity with a curing agent and to emulsification dispersibility for forming an aqueous system. Patent Document <NUM> describes a water dispersion of a polyester resin having a branched structure to increase the terminal carboxyl group concentration and having excellent long-term storage stability. Patent Document <NUM> describes a water dispersion of a polyester resin having a branched structure to increase the molecular-terminal hydroxyl group concentration and having excellent reactivity with a curing agent. Patent Document <NUM> describes a polyester resin for paint having a branched structure introduced into only a molecular terminal thereof to increase the carboxyl group concentration and having strong reactivity with a curing agent. Patent Document <NUM> proposes a method which does not depend on the branched structure. Specifically, the method includes performing copolymerization through a depolymerization reaction by adding an oligomer compound (such as polyglycerin) having many hydroxyl groups to a polymerized melted straight-chain polyester resin. Patent Document <NUM> describes a grafting reaction product and a method for producing the same. Patent Document <NUM> describes an aqueous dispersion of a copolymer polyester resin and a method for producing the same. Patent Document <NUM> describes a polycarbonate which is excellent in heat resistance and water resistance and has an excellent color tone and a method for producing the polycarbonate efficiently. Patent Document <NUM> describes a clear vanish composition. Patent Document <NUM> describes a polyester resin composition and a packaging material made therefrom.

In the polyester resins described in Patent Documents <NUM> and <NUM>, a risk of gelation during polymerization increases due to the branched structure introduced into the polymer molecular chain thereof. Accordingly, it is impossible to give a high-molecular-weight polyester resin. In the polyester resin described in Patent Document <NUM>, it is impossible to sufficiently increase the terminal group concentration even when having a branched structure introduced into only a molecular terminal thereof, because high-molecular-weight polymers inevitably have low terminal group concentration. In the polyester resin described in Patent Document <NUM>, it is impossible to avoid a decrease in molecular weight due to the depolymerization reaction. Also, it has not been easy to control the decreased molecular weight in a prescribed range.

The present invention has been made with such background conventional technical problems. That is, an object of the present invention is to provide: a modified copolymerized polyester resin that has excellent reactivity with a curing agent, enables achievement of high molecular weight, and further has good storage stability when used to prepare a water dispersion; and a water dispersion containing the modified copolymerized polyester resin.

As a result of extensive investigations, the inventors of the present application have found that the above problem can be solved by the following means and achieved the present invention. Thus, the present invention comprises the following constitutions.

A modified copolymerized polyester resin (B) having a structure in which a copolymerized polyester resin (A) has an unsaturated polyvalent carboxylic acid added to a side chain thereof, and the copolymerized polyester resin (A) contains, as copolymerization components, at least two members selected from the group consisting of: a copolymerization component having an alicyclic structure (component x); a copolymerization component having six or more continuous methylene groups (component y); and an acyclic aliphatic copolymerization component having a tertiary carbon atom and a molecular weight of more than <NUM> (component z).

The unsaturated polyvalent carboxylic acid is preferably maleic acid, itaconic acid, or an anhydride thereof. The copolymerized polyester resin (A) preferably has an acid value of <NUM> eq/ton or less.

A water dispersion containing the modified copolymerized polyester resin (B).

The modified copolymerized polyester resin according to the present invention contains copolymerization monomer components each of which has a specific structure, i.e., the component x, the component y, and the component z, to allow efficient progress of a radical addition reaction of the unsaturated polyvalent carboxylic acid by an organic peroxide catalyst. As a result, the modified copolymerized polyester resin according to the present invention exhibits excellent reactivity with various curing agents. Further, it is possible to prepare an aqueous dispersion, using the carboxyl group (unsaturated carboxylic acid) added to the side chain. Accordingly, the modified copolymerized polyester resin according to the present invention has good storage stability. The addition reaction does not accompany a partial cleavage reaction of a polymer chain. Further, the addition reaction does not require copolymerization of a large amount of a branch-type copolymerization monomer component, unlike a convention manner for introducing a hydrophilic polar group into a polyester resin. Therefore, the addition reaction enables acquisition of a high-molecular-weight modified copolymerized polyester resin.

As hereunder, embodiments of the present invention will be explained.

A copolymerized polyester resin (A) used in the present invention contains, as copolymerization components, at least two members selected from the group consisting of : a copolymerization component having an alicyclic structure (component x) ; a copolymerization component having six or more continuous methylene groups (component y); and an acyclic aliphatic copolymerization component having a tertiary carbon atom and a molecular weight of more than <NUM> (component z).

Component x is a copolymerization component having an alicyclic structure (Hereinafter, it is simply called as "component x"). The introduction of the component x is achieved by copolymerizing a monomer raw material, as described below, having an alicyclic structure. Examples of the component x include dibasic acid raw materials such as <NUM>,<NUM>-cyclohexanedicarboxylic acid, <NUM>,<NUM>-cyclohexanedicarboxylic acid, <NUM>,<NUM>-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride, <NUM>-methylhexahydrophtalic anhydride, and <NUM>-cyclohexene-<NUM>, <NUM>-dicarboxylic acid; and glycol raw materials such as <NUM>,<NUM>-bis(hydroxymethyl)cyclohexane, <NUM>,<NUM>-bis(hydroxymethyl)cyclohexane, <NUM>,<NUM>-bis(hydroxyethyl)cyclohexane, <NUM>,<NUM>-bis(hydroxypropyl)cyclohexane, <NUM>,<NUM>-bis(hydroxymethoxy)cyclohexane, <NUM>,<NUM>-bis(hydroxyethoxy)cyclohexane, <NUM>,<NUM>-bis(<NUM>-hydroxymethoxycyclohexyl)propane, <NUM>,<NUM>-bis(<NUM>-hydroxyethoxycyclohexyl)propane, bis(<NUM>-hydroxycyclohexyl)methane, <NUM>,<NUM>-bis(<NUM>-hydroxycyclohexyl)propane, and <NUM>(<NUM>),<NUM>(<NUM>)-tricyclo [<NUM>. <NUM><NUM>,<NUM>]decanedimethanol. Among the dibasic acid raw materials of these monomer raw materials having an alicyclic structure, <NUM>,<NUM>-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride, or <NUM>-methylhexahydrophthalic anhydride is preferable. Among the glycol raw materials having an alicyclic structure, <NUM>,<NUM>-bis(hydroxymethyl)cyclohexane is preferable in terms of general versatility and copolymerization reactivity. These materials can be used alone or in combination of two or more materials.

Component y is a copolymerization component having six or more continuous methylene groups (Hereinafter, it is simply called as "component y"). The number of continuous methylene groups is acceptable as long as it is six or more, and it may be seven or more, or eight or more. The upper limit is preferably <NUM> or less, further preferably <NUM> or less, and furthermore preferably <NUM> or less. The component y preferably has no tertiary carbon atom and no alicyclic structure. Examples of the component y include dibasic acids such as suberic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; and glycols such as <NUM>,<NUM>-hexanediol, <NUM>,<NUM>-heptanediol, <NUM>,<NUM>-octanediol, <NUM>,<NUM>-nonanediol, <NUM>,<NUM>-decanediol, <NUM>,<NUM>-undecanediol, and <NUM>,<NUM>-dodecanediol. Among these materials, sebacic acid and <NUM>,<NUM>-hexanediol are preferable in terms of general versatility. These materials can be used alone or in combination of two or more materials.

Component z is an acyclic aliphatic copolymerization component having a tertiary carbon atom and a molecular weight of more than <NUM> (Hereinafter, it is simply called as "component z"). The number of tertiary carbon atom contained in the component z is acceptable as long as it is at least one, and it may be two or more. Further, molecular weight is acceptable as long as it is over <NUM>. The molecular weight is preferably <NUM> or more, further preferably <NUM> or more, and furthermore preferably <NUM> or more. Further, the molecular weight is preferably <NUM> or less, further preferably <NUM> or less, and furthermore preferably <NUM> or less. Setting the molecular weight within the above range enables achievement of high molecular weight of the modified copolymerized polyester resin (B). The component z preferably has no six or more continuous methylene groups. The component z has no alicyclic structure such as a cyclohexyl ring, or no aromatic structure such as a benzene ring. Specific examples of the component z include dibasic acids such as <NUM>-ethyladipic acid, <NUM>-ethyladipic acid, <NUM>-isopropyladipic acid, <NUM>,<NUM>-dimethyladipic acid, <NUM>-methylsuberic acid, <NUM>-methylsuberic acid, and <NUM>-methylsuberic acid; and glycols such as <NUM>,<NUM>-diethyl-<NUM>,<NUM>-pentanediol, <NUM>,<NUM>-diethyl-<NUM>,<NUM>-pentanediol, <NUM>,<NUM>-diethyl-<NUM>,<NUM>-pentanediol, <NUM>,<NUM>-diethyl-<NUM>,<NUM>-pentanediol, <NUM>,<NUM>-diethyl-<NUM>,<NUM>-pentanediol, <NUM>,<NUM>-diethyl-<NUM>,<NUM>-pentanediol, <NUM>-ethyl-<NUM>-isopropyl-<NUM>,<NUM>-pentanediol, <NUM>-methyl-<NUM>,<NUM>-pentanediol, <NUM>-ethyl-<NUM>,<NUM>-pentanediol, <NUM>-propyl-<NUM>,<NUM>-pentanediol, <NUM>-ethyl-<NUM>,<NUM>-hexanediol, <NUM>-octyl-<NUM>,<NUM>-pentanediol, and <NUM>,<NUM>,<NUM>-trmethyl-<NUM>,<NUM>-pentanediol. These materials can be used alone or in combination of two or more materials. Among these materials, <NUM>,<NUM>-diethyl-<NUM>,<NUM>-pentanediol is preferable in terms of addition efficiency of the unsaturated polyvalent carboxylic acid.

The total amount of the component x, the component y, and the component z to be copolymerized in the copolymerized polyester resin (A) used in the present invention is preferably <NUM> mol% or more, further preferably <NUM> mol% or more, and furthermore preferably <NUM> mol% or more of all the copolymerization components. Also, the total amount is preferably <NUM> mol% or less, further preferably <NUM> mol% or less, and furthermore preferably <NUM> mol% or less. Setting the total amount to the lower-limit value or more enables sufficient addition of the unsaturated polyvalent carboxylic acid to the copolymerized polyester resin (A). Setting the total amount to the upper-limit value or less enables suppression of occurrence of a gel component during an addition modification reaction. The total amount of the component y and the component z is preferably <NUM> mol% or less, and more preferably <NUM> mol% or less. Setting the total amount to <NUM> mol% or less prevents the copolymerized polyester resin (A) from having an excessively low glass transition temperature and enables the copolymerized polyester resin (A) to maintain excellent resin physical properties including strength and flexibility unique to polyester resins. The lower limit is not particularly limited and may be even <NUM> mol%. The lower limit is preferably <NUM> mol% or more, and more preferably <NUM> mol% or more.

As to the copolymerization monomer material other than the component x, the component y, and the component z to be copolymerized in the copolymerized polyester resin (A) used in the present invention, examples of an acid component include aromatic dibasic acids such as terephthalic acid, isophthalic acid, ortho-phthalic acid, <NUM>,<NUM>-naphthalenedicarboxylic acid, <NUM>,<NUM>-naphthalenedicarboxylic acid, and anhydrides thereof; and aliphatic dibasic acids such as succinic acid, glutaric acid, and adipic acid. These materials can be used alone or in combination of two or more materials. An aromatic dibasic acid is preferable in terms of the physical properties of the obtained modified copolymerized polyester resin (B). Terephthalic acid, isophthalic acid, and <NUM>,-<NUM>-naphthalenedicarboxylic acid are preferable in terms of general versatility and copolymerization reactivity of the raw material. Examples of a glycol component include aliphatic diols such as ethylene glycol, <NUM>,<NUM>-propylene glycol, <NUM>,<NUM>-propylene glycol, <NUM>,<NUM>-butylene glycol, <NUM>,<NUM>-butylene glycol, <NUM>,<NUM>-butylene glycol, <NUM>,<NUM>-butylene glycol, <NUM>-methyl-<NUM>,<NUM>-propylene glycol, neopentyl glycol, <NUM>,<NUM>-dimethyl-<NUM>-hydroxypropyl-<NUM>',<NUM>'-dimethyl-<NUM>-hydroxypropan oate, and <NUM>,<NUM>-diethyl-<NUM>,<NUM>-propylene glycol; and aromatic diols such as an ethylene oxide adduct of bisphenol A. These materials can be used alone or in combination of two or more materials. Among these glycol raw materials, ethylene glycol, <NUM>,<NUM>-propylene glycol, neopentyl glycol, and <NUM>-methyl-<NUM>,<NUM>-propylene glycol are preferable in terms of general versatility and copolymerization reactivity. Most preferable one is <NUM>-methyl-<NUM>,<NUM>-propylene glycol.

In the copolymerized polyester resin (A) of the present invention, a polyfunctional compound other than the foregoing acid components and glycol components (such as trimethylol propane, trimellitic acid, or trimellitic anhydride) can be copolymerized within the range not to allow gelation of the copolymerized polyester resin (A), so as to more easily achieve high molecular weight. When the polyfunctional compound is copolymerized, the copolymerization amount thereof is preferably <NUM> mol% or more, and more preferably <NUM> mol% or more, relative to all the copolymerization components defined as <NUM> mol%. The upper limit is preferably <NUM> mol% or less, and more preferably <NUM> mol% or less. Further, the copolymerized polyester resin (A) used in the present invention can be, after the polymerization reaction, subjected to an addition modification reaction (post-addition) of an acid compound such as trimellitic acid to a molecular terminal, so as to add an acid value. The acid addition achieved by adding the acid compound to the molecular terminal enables the modified copolymerized polyester resin (B), which has undergone addition modification of the unsaturated polyvalent carboxylic acid, to be more easily dispersed in water and to produce a water dispersion having improved storage stability. When an acid anhydride is copolymerized, the copolymerization amount thereof is preferably <NUM> mol% or more, and more preferably <NUM> mol% or more, relative to all the copolymerization components defined as <NUM> mol%. The upper limit is preferably <NUM> mol% or less, and more preferably <NUM> mol% or less.

The polymerization for the copolymerized polyester resin (A) is performed by performing a transesterification reaction or an esterification reaction in advance between the acid component and the glycol component in an excess amount relative to the amount of the acid component to prepare an oligomer, and thereafter removing the glycol component under high temperature and high vacuum to finish the polymerization reaction. Next, the modification addition reaction of the unsaturated polyvalent carboxylic acid component is preferably performed. Performing such a polymerization and modification method enables acquisition of the modified copolymerized polyester resin (B) having a functional group at a site other than a polymer terminal.

The copolymerized polyester resin (A) preferably has an acid value of <NUM> eq/ton or less, further preferably <NUM> eq/ton or less, and furthermore preferably <NUM> eq/ton or less. Acquisition of an addition amount (acid value) of more than <NUM> eq/ton requires a decrease in molecular weight so as to increase the number of terminal groups of the copolymerized polyester resin (A), sometimes resulting in deficient aggregation force of the obtained resin. The acquisition otherwise requires introduction of a branched component having three or more functional groups, increasing a risk of gelation. On the other hand, the acid value is preferably <NUM> eq/ton or more, further preferably <NUM> eq/ton or more, furthermore preferably <NUM> eq/ton or more, and particularly preferably <NUM> eq/ton or more. Setting the acid value within the above range enables acquisition of the modified copolymerized polyester resin (B) having a high molecular weight and good storage stability.

The copolymerized polyester resin (A) used in the present invention can be synthesized by a conventionally well-known method. Examples of the method include a method for performing an esterification reaction between a mixture of the various dicarboxylic acid compounds described above and an excess equivalent of the glycol component in a melted state and then performing a polymerization reaction under high temperature and high vacuum; and a method for performing a transesterification reaction between a mixture of dialkyl ester compounds of the carboxylic acids described above and an excess amount of the glycol component and then performing a polymerization reaction under high temperature and high vacuum. As to a polymerization catalyst, a generally used compound, i.e., a titanium-based, zinc-based, antimony-based, magnesium-based, or germanium-based compound, can be used.

The copolymerized polyester resin (A) preferably has a number-average molecular weight in GPC analysis with a polystyrene standard of <NUM>,<NUM> to <NUM>,<NUM>, and more preferably <NUM>,<NUM> to <NUM>,<NUM>. Setting the number-average molecular weight to <NUM>,<NUM> or more increases aggregation force of the copolymerized polyester resin (A), leading to acquisition of a good coating film. On the other hand, setting the number-average molecular weight to <NUM>,<NUM> or less prevents the copolymerized polyester resin in a melted state or a solution state from having excessively high viscosity, facilitating the modification addition reaction of the unsaturated polyvalent carboxylic acid.

The copolymerized polyester resin (A) preferably has a glass transition temperature of -<NUM> or higher, further preferably -<NUM> or higher, and furthermore preferably -<NUM> or higher. Also, the glass transition temperature is preferably <NUM> or lower, further preferably <NUM> or lower, and furthermore preferably <NUM> or lower. Setting the glass transition temperature within the above range facilitates the modification addition reaction of the unsaturated polyvalent carboxylic acid.

The unsaturated polyvalent carboxylic acid used in the present invention is not particularly limited as long as it is a compound having at least one unsaturated bond and two or more carboxyl groups per one molecule. The unsaturated polyvalent carboxylic acid may have two or more unsaturated bonds per one molecule. Examples of the unsaturated polyvalent carboxylic acid include maleic acid and an anhydride thereof, itaconic acid and an anhydride thereof, fumaric acid and an anhydride thereof, citraconic acid and an anhydride thereof, mesaconic acid and an anhydride thereof, <NUM>-pentenedioic acid and an anhydride thereof, <NUM>-dodecenylsuccinic acid and an anhydride thereof, octenylsuccinic acid and an anhydride thereof, dimer acid, and various unsaturated fatty acids contained in vegetable oil. These materials can be used alone or in combination of two or more materials. Maleic acid, itaconic acid, and anhydrides thereof are preferable in terms of reactivity and general versatility.

The modified copolymerized polyester resin (B) has a structure in which the copolymerized polyester resin (A) has the unsaturated polyvalent carboxylic acid added to a side chain thereof. The modified copolymerized polyester resin (B) may have a structure in which the unsaturated polyvalent carboxylic acid is added not only to the side chain but also to a terminal of the copolymerized polyester resin (A). The addition amount of the unsaturated polyvalent carboxylic acid (modification amount) is preferably <NUM> mass% or more, further preferably <NUM> mass% or more, and furthermore preferably <NUM> mass% or more, in the modified copolymerized polyester resin (B). Also, the addition amount (modification amount) is preferably <NUM> mass% or less, more preferably less than <NUM> mass%, further preferably <NUM> mass% or less, furthermore preferably <NUM> mass% or less, and particularly preferably <NUM> mass% or less. Setting the addition amount within the above range enables the modified copolymerized polyester resin (B) to be formed into a water dispersion and further enables the water dispersion containing the modified copolymerized polyester resin (B) to have good storage stability.

The addition reaction of the unsaturated polyvalent carboxylic acid (modification reaction) can be performed, for example, by a solution reaction of reacting the copolymerized polyester resin (A) in an organic solvent or by a melting reaction using a twin screw extruder. Examples of the organic solvent used in the solution reaction include aromatic organic solvents such as toluene and xylene; aliphatic organic solvents such as n-hexane; alicyclic organic solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane; ketone-based organic solvents such as acetone and methyl ethyl ketone; and alcohol-based organic solvents such as methanol and ethanol. These solvents can be used alone or in combination. Above all, an aromatic organic solvent or a mixed solvent containing an aromatic organic solvent are preferable. Of these reactions, the solution reaction enables an unreacted unsaturated polyvalent carboxylic acid component to be removed by subjecting the product obtained after the reaction (the copolymerized polyester resin (B) component) to a reprecipitation treatment using an alcohol such as methanol, water, or a mixed solution thereof.

As to a reaction catalyst for the addition reaction of the unsaturated polyvalent carboxylic acid, various radical initiator catalysts can be used, but particularly an organic peroxide catalyst is preferable. Examples include peroxides such as di-tert-butyl peroxyphthalate, tert-butyl hydroperoxide, dicumyl peroxide, tert-butyl cumyl peroxide, tert-butyl peroxyisopropyl monocarbonate, <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-di(tert-butylperoxy)hexane, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxy-<NUM>-ethylhexanoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, di-tert-butyl peroxide, and lauroyl peroxide; and azonitriles such as azobisisobutyronitrile and azobisisopropionitrile. Among these organic peroxide catalysts, di-tert-butyl peroxide, tert-butyl cumyl peroxide, tert-butyl peroxyisopropyl monocarbonate, and <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-di(tert-butylperoxy)hexane are preferable from the view point of addition reaction efficiency.

The modified copolymerized polyester resin (B) preferably has a number-average molecular weight in GPC analysis with a polystyrene standard of <NUM>,<NUM> to <NUM>,<NUM>, and more preferably <NUM>,<NUM> to <NUM>,<NUM>. Setting the number-average molecular weight within the above range increases aggregation force of the modified copolymerized polyester resin (B), leading to acquisition of a good coating film.

The water dispersion according to the present invention is a dispersion containing the modified copolymerized polyester resin (B) and water. The water dispersion preferably further contains a basic material. The water dispersion preferably has a resin (modified copolymerized polyester resin (B)) concentration of <NUM> mass% or more, and more preferably <NUM> mass% or more. Also, the concentration is preferably <NUM> mass% or less, and more preferably <NUM> mass% or less.

The basic material is not particularly limited, but is preferably a volatile basic material. Above all, ammonia and amines are preferable. The amines are not particularly limited, and examples include monomethylamine, dimethylamine, trimethylamine, monoethylamine, mono-n-propylamine, dimethyl-n-propylamine, monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-aminoethylethanolamine, N-methyldiethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, N,N-dimethylethanolamine, and N,N-dimethylpropanolamine. Most preferable ones are triethylamine and N,N-dimethylethanolamine. These volatile amines can be used alone or in combination of two or more amines.

The blend ratio of the basic material is preferably <NUM> part by mass or more, further preferably <NUM> part by mass or more, furthermore preferably <NUM> parts by mass or more, and particularly preferably <NUM> parts by mass or more, relative to <NUM> parts by mass of the modified copolymerized polyester resin (B). Also, the blend ratio is preferably <NUM> parts by mass or less, further preferably <NUM> parts by mass or less, furthermore preferably <NUM> parts by mass or less, and particularly preferably <NUM> parts by mass or less. Setting the blend ratio within the above range prevents the dispersed particles from excessively increasing the particle size thereof, resulting in good storage stability of the water dispersion. Further, such a setting leads to acquisition of a coating film having good water resistance.

The particles of the modified copolymerized polyester resin (B) in the water dispersion preferably have a Z-average particle size of <NUM> or less, further preferably <NUM> or less, furthermore preferably <NUM> or less, and particularly preferably <NUM> or less. The lower limit is not particularly limited, but it is industrially alright if the Z-average particle size is <NUM> or more. The particles having a Z-average particle size within the above range allow the water dispersion to have excellent storage stability, and to have good handleability when used in paints, inks, coating agents, adhesives, and the like.

The water dispersion is preferably basic. The water dispersion preferably has a pH of <NUM> or more, further preferably <NUM> or more, furthermore preferably <NUM> or more, and particularly preferably <NUM> or more. The upper limit is not particularly limited, but it is preferably <NUM> or less, and more preferably <NUM> or less. The pH within the above range enables the water dispersion to have excellent storage stability.

The water dispersion preferably has a viscosity of <NUM> mPa·s or more, and more preferably <NUM> mPa·s or more. The viscosity is preferably <NUM> mPa·s or less, and more preferably <NUM> mPa·s or less. The viscosity within the above range allows the water dispersion to have excellent storage stability, and to have good handleability when used in paints, inks, coating agents, adhesives, and the like.

The water dispersion preferably has a solid content concentration of <NUM> mass% or more, more preferably <NUM> mass% or more. The solid content concentration is preferably <NUM> mass% or less, and more preferably <NUM> mass% or less.

In the water dispersion according to the present invention containing the modified copolymerized polyester resin (B), various curing agents and curing reaction catalysts can be blended for the purpose of improving strength of the coating film, imparting solvent resistance and heat resistance, and improving adhesive strength to a substrate, and the thus-obtained water dispersion can be used as coating agents or adhesives. Examples of the curing agents include a polyfunctional epoxy compound, a blend of a polyfunctional epoxy compound with an oxazoline compound and/or an acid anhydride, and a polyfunctional isocyanate compound. As to the curing reaction catalysts, general catalysts such as an organic amine-based or organic phosphorus-based catalyst are effective for a polyfunctional epoxy compound. For a polyfunctional isocyanate compound, for example, a general organic tin-based, organic bismuth-based, or organic amine-based catalyst is effective, but the curing reaction is progressed even without a catalyst.

The polyfunctional epoxy resin is not particularly limited as long as it has two or more epoxy groups per one molecule. Specific examples include glycidyl ether of bisphenol A and an oligomer thereof, diglycidyl orthophthalate, diglycidyl isophthalate, diglycidyl terephthalate, diglycidyl p-hydroxybenzoate, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, diglycidyl succinate, diglycidyl adipate, diglycidyl sebacate, ethylene glycol diglycidyl ester, propylene glycol diglycidyl ester, <NUM>,<NUM>-butanediol diglycidyl ester, <NUM>,<NUM>-hexanediol diglycidyl ester, and polyalkylene glycol diglycidyl esters, triglycidyl trimellitate, triglycidyl isocyanurate, <NUM>,<NUM>-glycidyloxybenzene, diglycidylpropylene urea, glycerol triglycidyl ether, trimethylolethane glycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, and triglycidyl ether of a glycerol alkylene oxide adduct. These materials can be used alone or in combination of two or more materials.

The polyfunctional isocyanate compound is not particularly limited as long as it has two or more isocyanate groups per one molecule. Specific examples include, but are not limited to, aromatic, alicyclic, or aliphatic polyisocyanate compounds, and both low-molecular-weight compounds and high-molecular-weight compounds are acceptable. Examples include tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and trimers of these isocyanate compounds, and isocyanate-terminated compounds obtained by reacting the foregoing isocyanate compounds with active hydrogen compounds such as ethylene glycol, trimethylol propane, propylene glycol, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, polyester polyols, polyether polyols, and polyamides. These materials can be used alone or in combination of two or more materials.

The blend ratio of the curing agent is preferably <NUM> part by mass or more, further preferably <NUM> parts by mass or more, and furthermore preferably <NUM> parts by mass or more, relative to <NUM> parts by mass of the modified copolymerized polyester resin (B). Also, the blend ratio is preferably <NUM> parts by mass or less, further preferably <NUM> parts by mass or less, and furthermore preferably <NUM> parts by mass or less. Setting the blend ratio of the curing agent within the above range allows the water dispersion to give a coating film having good hardness, fastness, adhesion strength, and flexing property.

The reactivity between the modified copolymerized polyester resin (B) and the curing agent can be obtained by gel (solvent-insoluble component) fraction. The water dispersion preferably has a gel fraction of <NUM>% or more, further preferably <NUM>% or more, furthermore preferably <NUM>% or more, and particularly preferably <NUM>% or more. It may be even <NUM>%. The water dispersion having a gel fraction of the above value or more has good reactivity between the modified copolymerized polyester resin (B) and the curing agent and can give a coating film having excellent curing properties.

A method for emulsification-dispersing the modified copolymerized polyester resin (B) according to the present invention in water includes: heating and dissolving the modified copolymerized polyester resin (B) in a water-soluble ketone-based solvent such as methyl ethyl ketone (MEK), or a water-soluble ether-based solvent such as tetrahydrofuran (THF), and water; adding a basic material to the obtained mixture; and removing the ketone-based solvent and the ether-based solvent after cooling the mixture. The method enables acquisition of a stable water dispersion substantially without using an emulsifier.

The water dispersion containing the modified copolymerized polyester resin (B) according to the present invention preferably contains substantially no emulsifier. The phrase "contains substantially no emulsifier" means that the water dispersion preferably has an emulsifier content of <NUM> mass% or less, further preferably <NUM> mass% or less, furthermore preferably <NUM> mass% or less, and particularly preferably <NUM> mass% or less. It may be even <NUM> mass%. The water dispersion containing substantially no emulsifier allows the coating film to have good water resistance.

The water dispersion containing the modified copolymerized polyester resin (B) according to the present invention may contain a small amount of an organic solvent. The content of the organic solvent is preferably <NUM> mass% or less, and more preferably <NUM> mass% or less.

The present invention will now be illustrated as hereunder by Examples although the present invention is not limited thereto. The term simply reading "part (s) " in Examples and Comparative Examples stands for that/those by mass. Each of the measurements and evaluations was carried out in accordance with the following methods.

Four milligrams of a sample (copolymerized polyester resin (A) or modified copolymerized polyester resin (B)) was dissolved in <NUM> of tetrahydrofuran and then filtered with a polytetrafluoroethylene membrane filter having a pore diameter of <NUM>. This obtained filtrate was used as a sample solution, and measured for the number-average molecular weight, with gel permeation chromatography (GPC) 150C manufactured by Waters Corporation, using tetrahydrofuran as a carrier solvent, at a flow rate of <NUM>/min. As to a column, three columns, i.e., Shodex KF-<NUM>, KF-<NUM>, and KF-<NUM> manufactured by Showa Denko K. , were connected with each other. The column temperature was set to <NUM>. A polystyrene standard was used as a molecular weight standard. Calculation was performed, with a part corresponding to a molecular weight of less than <NUM> removed.

Zero point two grams of a sample (copolymerized polyester resin (A) or modified copolymerized polyester resin (B)) was precisely weighed out, dissolved in <NUM> of chloroform, and then measured for the acid value, with a <NUM> N NaOH ethanol solution, using phenolphthalein as an indicator. The measured value was expressed by equivalent (eq) in <NUM> ton of resin solid content.

Five milligrams of a sample (copolymerized polyester resin (A)) was put on an aluminum sample pan, hermetically sealed therein, and measured for the glass transition temperature, using differential scanning calorimeter DSC-<NUM> manufactured by Seiko Instruments Inc. First, the sample was cooled with liquid nitrogen to -<NUM> and next heated to <NUM> at a temperature rise rate of <NUM>/min. The glass transition temperature was determined by the temperature (°C) at the intersection between an extended line of the base line showing temperatures of the glass transition temperature or lower (before appearance of the endothermic peak) and a tangent representing the maximum inclination of the transition part in the endothermic curve obtained during the temperature-rise process.

A sample (copolymerized polyester resin (A)) was dissolved in chloroform-d and subjected to determination of the resin composition ratio by <NUM>H-NMR, using nuclear magnetic resonance (NMR) analyzer "MR-<NUM>" manufactured by Varian, Inc.

A sample (copolymerized polyester resin (A)) was dissolved in a mixed solution containing methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio) to prepare a solution having a resin solid content concentration of <NUM> mass%. This solution was applied to a <NUM>-µm-thick OPP film (non-corona treated surface) and dried in a hot-air dying oven set at <NUM> for <NUM> minutes to prepare a film having a dry coating film thickness of <NUM>. Next, five test pieces in <NUM> × <NUM> were cut out. The OPP film was peeled from each of the test pieces. The test pieces were measured for the breaking strength and the breaking elongation, using Shimadzu AUTOGRAPH AG-Xplus. With the upper and lower grip margins of the test piece set to <NUM>, the breaking strength and the breaking elongation were measured at a tensile speed of <NUM>/min and <NUM>. The average value of the measured values (n = <NUM>) was used as the breaking strength and the breaking elongation.

Confirmation of whether or not the copolymerized polyester resin is formed into an adduct of the above-mentioned acid was performed by separating a component having a number-average molecular weight of <NUM> or more using LC-9210NEXT (preparative GPC) manufactured by Japan Analytical Industry Co. under the following conditions and subjecting the component to <NUM>H-NMR and HMBC spectrum analysis.

A modified copolymerized polyester resin (B) component having a molecular weight of <NUM> or more was separated on the basis of a calibration curve created using a polystyrene standard. The separated solution was dry-solidified by blowing nitrogen, then dissolved again in chloroform-d or a mixture of chloroform-d and DMSO-d (vol. ratio <NUM> : <NUM>), and subjected to <NUM>H-NMR measurement and <NUM>H-<NUM>C-HMBC measurement.

As to a measuring apparatus, NMR apparatus AVANCE-NEO600 manufactured by Bruker Corporation was used. In the <NUM>H-NMR measurement, <NUM> of the separated solution was dissolved in <NUM> of the foregoing solvent, then charged into a NMR tube, and subjected to <NUM>H-NMR measurement. Chloroform-d or DMSO-d was used as a lock solvent. The wait time was <NUM> second. The acquisition time was <NUM> seconds. The cumulated number was <NUM>.

The peak of CH<NUM> or CH at the α position with respect to the carbonyl bond of added maleic acid or itaconic acid is, in <NUM>H-NMR, detected as a broad peak in a region of <NUM> to <NUM> ppm, with the peak of chloroform set to <NUM> ppm or the peak of DMSO set to <NUM> ppm. When the separated component having a molecular weight of <NUM> or more is confirmed to have the corresponding peak and thereafter a HMBC spectrum allows confirmation of a correlation peak between the corresponding peak and the peak derived from C=O at around <NUM> ppm in <NUM>C-NMR, the separated component was determined to be an acid adduct.

Twenty parts of a solution (<NUM> mass%) having undergone an addition reaction of the unsaturated polyvalent carboxylic acid (modification reaction) was dried in a hot-air oven set at <NUM> for <NUM> minutes to prepare a cast film. The obtained cast film was dissolved in tetrahydrofuran so as to form a <NUM> mass% solution of the resin solid content. Thirty parts of this <NUM> mass% solution was gradually added into <NUM> of deionized water under vigorous stirring. The solution was all added in about <NUM> minutes, and the obtained mixture was left while continuously stirred for <NUM> minutes. Next, the obtained precipitated resin content was collected by a filter, dried at room temperature in a nitrogen flow, and dissolved in a mixed solvent of methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio) so as to prepare a <NUM> mass% solution. Twenty parts of the obtained <NUM> mass% solution was gradually added to <NUM> of methanol under vigorous stirring, and all added in about <NUM> minutes. The obtained mixture was left while continuously stirred for <NUM> minutes. The obtained precipitated resin content was collected by filter and dried at room temperature in a nitrogen flow. The obtained solid resin was measured for the acid value according to foregoing (<NUM>) "Method for measuring acid value". Using the measured acid value*, the addition amount when maleic acid was added or when itaconic acid was added was calculated by the following calculation formula.

In <NUM> parts of a <NUM> mass% solution of the modified copolymerized polyester resin (B) were blended <NUM> part of YD-<NUM> (bisphenol A epoxy resin manufactured by Nippon Steel & Sumikin Chemical Co. ), and <NUM> part of UCAT-18X (manufactured by San-Apro Ltd. ) as a reaction catalyst. The obtained mixture was applied to a corona-treated surface of a <NUM>-µm-thick PET film, using a doctor blade with a gap of <NUM>. The film was retained in an oven set at <NUM> for <NUM> minutes, then taken out, and cut out into a <NUM> × <NUM> strip test piece. The test piece was precisely weighed, then immersed in a mixed solvent of methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio), and left at room temperature for <NUM> hour. The test piece was taken out and dried, and then precisely weighed again. The change in mass between before and after the immersion was determined from the following gel (solvent-insoluble component) fraction calculation formula, and defined as an indicator of curing properties.

In <NUM> parts of a <NUM> mass% solution of the modified copolymerized polyester resin (B) were blended <NUM> part of Coronate HX (polyfunctional isocyanate manufactured by Tosoh Corporation). The obtained mixture was applied to a corona-treated surface of a <NUM>-µm-thick PET film, using a doctor blade with a gap of <NUM>. The film was dried in an oven set at <NUM> for <NUM> minutes, then taken out and retained in an incubator at <NUM> for <NUM> hours. The taken-out dried coating film was cut out into a <NUM> × <NUM> strip test piece. The test piece was precisely weighed, then immersed in a mixed solvent of methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio), and left at room temperature for <NUM> hour. The test piece was taken out and dried, and then precisely weighed again. The change in mass between before and after the immersion was determined from the gel (solvent-insoluble component) fraction calculation formula in a way similar to the evaluation of epoxy curing properties, and defined as an indicator of curing properties.

Using "Viscometer TV-<NUM>" (E-type viscometer) manufactured by Toki Sangyo Co. , <NUM> of a sample was measured for the viscosity under the conditions of rotor No. <NUM>° (= <NUM>') × R24, range H, a rotation rate of <NUM> rpm, and <NUM>.

Using "pH meter F52" manufactured by HORIBA, Ltd. , the pH of a water dispersion was measured at <NUM>. Calibration of the pH meter was performed by three-point calibration, using a phthalate pH standard solution (pH: <NUM>), a neutral phosphate pH standard solution (pH: <NUM>), and a borate pH standard solution (pH: <NUM>) (all manufactured by Wako Pure Chemical Industries, Ltd.

Using fiber-optics particle analyzer "FPAR-<NUM>" manufactured by Otsuka Electronics Co. , the average particle size of a water dispersion was measured by a dynamic light scattering method. A water dispersion having a solid content concentration of about <NUM> mass% was diluted with deionized water. The quantity of light was adjusted to the range of <NUM> to <NUM> cps. The measurement was performed with a measurement time of <NUM> seconds and a measurement temperature of <NUM>. The obtained value was defined as the average particle size.

About <NUM> of a sample water dispersion (emulsion) was poured into a <NUM>-ml glass weighing bottle and precisely weighed. Next, the weighing bottle into which the sample had been poured was dried by a hot-air drier set at <NUM> for <NUM> hours. The taken-out weighing bottle was put in a desiccator, and left and cooled at room temperature for <NUM> minutes. The weighing bottle was taken out from the desiccator. The mass was precisely weighed. The solid content concentration (mass%) of the water dispersion (emulsion) was calculated from the change in mass between before and after the hot-air drying (following formula).

A water dispersion (emulsion) directly after preparation and a water dispersion (emulsion) stored for <NUM> months at <NUM> in a still condition were observed for the change over time of the average particle size, the pH, the viscosity, the solid content concentration, and the number-average molecular weight. Table <NUM> shows the results.

The abbreviations of the compounds shown in the Tables of Examples stand for the following compounds.

Described below are synthesis examples, reference synthesis examples and comparative synthesis examples of the copolymerized polyester resin (A) and the modified copolymerized polyester resin (B) used in examples, reference synthesis examples and comparative examples of the present invention.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of dimethyl isophthalate, <NUM> parts of <NUM>,<NUM>-cyclohexanedimethanol, <NUM> parts of <NUM>-methyl-<NUM>,<NUM>-propyleneglycol, and <NUM> part of tetra-n-butyl titanate as a catalyst. The obtained mixture was subjected to a transesterification reaction at <NUM> to <NUM> for <NUM> hours. After confirming distillation of a prescribed amount of methanol, the reaction temperature was raised to <NUM>, and the generated condensation water was distilled away under reduced pressure. While the reaction temperature was gradually raised, the degree of reduction in pressure was gradually lowered so as to allow the temperature and the pressure to eventually reach <NUM> and <NUM> Torr in <NUM> minutes, and the polymerization reaction was finished. Next, the reaction system was returned to ordinary pressure, the temperature in the system was lowered to <NUM> while nitrogen gas was sealed in the system, and <NUM> parts of trimellitic acid was charged into the system. While the temperature in the system was maintained at <NUM>, the system was stirred in a nitrogen atmosphere for <NUM> minutes, and the addition reaction of trimellitic acid was finished. The melted copolymerized polyester resin was taken out from the flask into a heat-resistant tray, and measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, glass transition temperature: <NUM>, breaking strength: <NUM> MPa, and breaking elongation: <NUM>%. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A)A crushed into flakes, <NUM> parts of toluene, and <NUM> parts of maleic anhydride. The obtained reaction system was subjected to a nitrogen purge. The temperature in the vessel was raised to <NUM> while the reaction system was gently stirred. The reaction system was stirred for <NUM> hour so as to dissolve the copolymerized polyester resin (A) A and maleic anhydride. Next, <NUM> parts of di-tert-butyl peroxide was charged, and the temperature in the reaction system was raised to <NUM> while the reaction system was stirred at high speed. After a reaction was conducted at <NUM> for <NUM> hours, the reaction system was cooled. When the temperature was lowered to <NUM> or lower, the reaction system was returned to ordinary pressure. Three hundred and forty-five parts of methyl ethyl ketone was charged so as to dilute the reaction system into a solid content of <NUM> mass%. The obtained solution having a solid content concentration of the modified copolymerized polyester resin (B) a of about <NUM> mass% was dried in a hot-air oven set at <NUM> for <NUM> minutes so as to prepare a cast film. The prepared cast film was analyzed so as to confirm addition of maleic anhydride, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B) a was confirmed to have maleic anhydride added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of dimethyl isophthalate, <NUM> parts of <NUM>,<NUM>-cyclohexanedimethanol, <NUM> parts of <NUM>-methyl-<NUM>,<NUM>-propyleneglycol, and <NUM> part of tetra-n-butyl titanate as a catalyst. The obtained mixture was subjected to a transesterification reaction at <NUM> to <NUM> for <NUM> hours. After confirming distillation of a prescribed amount of methanol, <NUM> parts of <NUM>,<NUM>-cyclohexanedicarboxylic acid was charged, the reaction temperature was gradually raised to <NUM>, and the generated condensation water was distilled away. After the temperature reached <NUM>, the condensation water which was further generated was distilled away under reduced pressure. While the reaction temperature was gradually raised, the degree of reduction in pressure was gradually lowered so as to allow the temperature and the pressure to eventually reach <NUM> and <NUM> Torr in <NUM> minutes, and the polymerization reaction was finished. Next, the reaction system was returned to ordinary pressure, the temperature in the system was lowered to <NUM> while nitrogen gas was sealed in the system, and <NUM> parts of trimellitic acid was charged into the system. While the temperature in the system was maintained at <NUM>, the system was stirred in a nitrogen atmosphere for <NUM> minutes, and the addition reaction of trimellitic acid was finished. The melted copolymerized polyester resin was taken out from the flask into a heat-resistant tray, and measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, glass transition temperature: <NUM>, breaking strength: <NUM> MPa, and breaking elongation: <NUM>%. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A) B crushed into flakes, <NUM> parts of toluene, and <NUM> parts of itaconic anhydride. The obtained reaction system was subjected to a nitrogen purge. The temperature in the vessel was raised to <NUM> while the reaction system was gently stirred. The reaction system was stirred for <NUM> hour so as to dissolve the copolymerized polyester resin (A) B and itaconic anhydride. Next, <NUM> parts of di-tert-butyl peroxide was charged, and the temperature in the reaction system was raised to <NUM> while the reaction system was stirred at high speed. After a reaction was conducted at <NUM> for <NUM> hours, the reaction system was cooled. When the temperature was lowered to <NUM> or lower, the reaction system was returned to ordinary pressure. Three hundred and forty-eight parts of methyl ethyl ketone was charged so as to dilute the reaction system into a solid content of <NUM> mass%. The obtained solution having a solid content concentration of the modified copolymerized polyester resin (B)b of about <NUM> mass% was dried in a hot-air oven set at <NUM> for <NUM> minutes so as to prepare a cast film. The prepared cast film was analyzed so as to confirm addition of itaconic anhydride, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B)b was confirmed to have itaconic anhydride added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of dimethyl isophthalate, <NUM> parts of neopentyl glycol, <NUM> parts of ethylene glycol, and <NUM> part of tetra-n-butyl titanate as a catalyst. The obtained mixture was subjected to a transesterification reaction at <NUM> to <NUM> for <NUM> hours. After confirming distillation of a prescribed amount of methanol, <NUM> parts of sebacic acid was charged, the reaction temperature was gradually raised to <NUM>, and the generated condensation water was distilled away. After the temperature reached <NUM>, the condensation water which was further generated was distilled away under reduced pressure. While the reaction temperature was gradually raised, the degree of reduction in pressure was gradually lowered so as to allow the temperature and the pressure to eventually reach <NUM> and <NUM> Torr in <NUM> minutes, and the polymerization reaction was finished. The melted copolymerized polyester resin was taken out from the flask into a heat-resistant tray, and measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, glass transition temperature: <NUM>, breaking strength: <NUM> MPa, and breaking elongation: <NUM>%. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A) C crushed into flakes, <NUM> parts of toluene, and <NUM> parts of maleic anhydride. The obtained reaction system was subjected to a nitrogen purge. The temperature in the vessel was raised to <NUM> while the reaction system was gently stirred. The reaction system was stirred for <NUM> hour so as to dissolve the copolymerized polyester resin (A) C and maleic anhydride. Next, <NUM> parts of di-tert-butyl peroxide was charged, and the temperature in the reaction system was raised to <NUM> while the reaction system was stirred at high speed. After a reaction was conducted at <NUM> for <NUM> hours, the reaction system was cooled. When the temperature was lowered to <NUM> or lower, the reaction system was returned to ordinary pressure. Three hundred parts of methyl ethyl ketone was charged so as to dilute the reaction system.

Five hundred parts of the obtained reaction product solution was returned to room temperature and gradually added to <NUM> of methyl alcohol under vigorous stirring, and allowed to precipitate a resin content. The precipitated modified copolymerized polyester (B)c was separated by a filter and dried. It was analyzed so as to confirm addition of maleic anhydride, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B)c was confirmed to have maleic anhydride added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of dimethyl isophthalate, <NUM> parts of <NUM>,<NUM>-cyclohexanedimethanol, <NUM> parts of <NUM>-methyl-<NUM>,<NUM>-propyleneglycol, <NUM> parts of <NUM>,<NUM>-diethyl-<NUM>,<NUM>-pentanediol, and <NUM> part of tetra-n-butyl titanate as a catalyst. Thereafter, procedures were conducted in a way similar to the polymerization in the Reference Synthesis Example <NUM> (copolymerized polyester resin (A)A). The obtained resin was measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, glass transition temperature: <NUM>, breaking strength: <NUM> MPa, and breaking elongation: <NUM>%. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A) D crushed into flakes, <NUM> parts of toluene, and <NUM> parts of maleic anhydride. The modification reaction was conducted in a way similar to the Reference Synthesis Example <NUM>. The obtained solution having a solid content concentration of the modified copolymerized polyester resin (B)d of about <NUM> mass% was dried in a hot-air oven set at <NUM> for <NUM> minutes so as to prepare a cast film. The prepared cast film was analyzed so as to confirm addition of maleic anhydride, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B)d was confirmed to have maleic anhydride added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl isophthalate, <NUM> parts of <NUM>,<NUM>-cyclohexanedimethanol, <NUM> parts of neopentyl glycol, <NUM> parts of <NUM>,<NUM>-hexanediol, and <NUM> part of tetra-n-butyl titanate as a catalyst. The obtained mixture was subjected to a transesterification reaction at <NUM> to <NUM> for <NUM> hours. After confirming distillation of a prescribed amount of methanol, <NUM> parts of ortho-phthalic anhydride and <NUM> parts of trimellitic acid were added, the reaction temperature was gradually raised to <NUM>, and the generated condensation water was distilled away. Thereafter, procedures were conducted in a way similar to the copolymerized polyester resin (A)A of the Reference Synthesis Example <NUM> and the copolymerized polyester resin (A)E was obtained. The obtained resin was measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, glass transition temperature: <NUM>, breaking strength: <NUM> MPa, and breaking elongation: <NUM>%. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A)E crushed into flakes, <NUM> parts of toluene, and <NUM> parts of itaconic acid. The modification reaction was conducted in a way similar to the Reference Synthesis Example <NUM>. The obtained solution having a solid content concentration of the modified copolymerized polyester resin (B)e of about <NUM> mass% was dried in a hot-air oven set at <NUM> for <NUM> minutes so as to prepare a cast film. The prepared cast film was analyzed so as to confirm addition of itaconic acid, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B)e was confirmed to have itaconic acid added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A) F crushed into flakes, <NUM> parts of toluene, and <NUM> parts of maleic anhydride. The obtained reaction system was subjected to a nitrogen purge. Thereafter, procedures were conducted in a way similar to the modification reaction in the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B)c).

Procedures were conducted in a way similar to the purification procedure in the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B)c). The obtained modified copolymerized polyester resin (B)f was analyzed so as to confirm addition of maleic anhydride, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B)f was confirmed to have maleic anhydride added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of <NUM>,<NUM>-cyclohexanedimethanol, <NUM> parts of <NUM>-methyl-<NUM>,<NUM>-propyleneglycol, and <NUM> part of tetra-n-butyl titanate as a catalyst. The obtained mixture was subjected to a transesterification reaction at <NUM> to <NUM> for <NUM> hours. After confirming distillation of a prescribed amount of methanol, <NUM> parts of <NUM>,<NUM>-cyclohexanedicarboxylic acid was charged, the reaction temperature was gradually raised to <NUM>, and the generated condensation water was distilled away. After the temperature reached <NUM>, the condensation water which was further generated was distilled away under reduced pressure. While the reaction temperature was gradually raised, the degree of reduction in pressure was gradually lowered so as to allow the temperature and the pressure to eventually reach <NUM> and <NUM> Torr in <NUM> minutes, and the polymerization reaction was finished. The melted copolymerized polyester resin was taken out from the flask into a heat-resistant tray, and measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, glass transition temperature: <NUM>, breaking strength: <NUM> MPa, and breaking elongation: <NUM>%. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A) G crushed into flakes, <NUM> parts of toluene, and <NUM> parts of maleic anhydride. The obtained reaction system was subjected to a nitrogen purge. Thereafter, procedures were conducted in a way similar to the modification reaction in the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B)c). However, it was observed that a gel-like substance adhered on an inner wall of the reaction vessel when the addition modification reaction was finished.

Procedures were conducted in a way similar to the purification procedure in the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B)c). The obtained modified copolymerized polyester resin (B)g was analyzed so as to confirm addition of maleic anhydride, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B)g was confirmed to have maleic anhydride added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of <NUM>-methyl-<NUM>,<NUM>-propyleneglycol, <NUM> parts of <NUM>,<NUM>-diethyl-<NUM>,<NUM>-pentanediol, and <NUM> part of tetra-n-butyl titanate as a catalyst. The obtained mixture was subjected to a transesterification reaction at <NUM> to <NUM> for <NUM> hours. After confirming distillation of a prescribed amount of methanol, <NUM> parts of <NUM>,<NUM>-cyclohexanedicarboxylic acid and <NUM> parts of sebacic acid were charged. Thereafter, procedures were conducted in a way similar to the Synthesis Example <NUM> (copolymerized polyester resin (A)B). The obtained resin was measured for the resin composition, the number-average molecular weight, the acid value, and the glass transition temperature. The breaking strength and the breaking elongation of the film could not be measured because the resin could not form a film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, and glass transition temperature: -<NUM>. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A)H having a shape of finely-cut sheet, <NUM> parts of toluene, and <NUM> parts of itaconic acid. The modification reaction was conducted in a way similar to the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B) a). The obtained solution having a solid content concentration of the modified copolymerized polyester resin (B)h of about <NUM> mass% was dried in a hot-air oven set at <NUM> for <NUM> minutes so as to prepare a cast film. The prepared cast film was analyzed so as to confirm addition of itaconic acid, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B)h was confirmed to have itaconic acid added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of dimethyl isophthalate, <NUM> parts of trimellitic acid, <NUM> parts of ethylene glycol, <NUM> parts of <NUM>,<NUM>-propylene glycol, and <NUM> part of tetra-n-butyl titanate as a catalyst. Thereafter, procedures were conducted in a way similar to the Reference Synthesis Example <NUM> (copolymerized polyester resin (A)A) and the copolymerized polyester resin (A)I was obtained. The obtained resin was measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, glass transition temperature: <NUM>, breaking strength: <NUM> MPa, and breaking elongation: <NUM>%. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A) I crushed into flakes, <NUM> parts of toluene, and <NUM> parts of maleic anhydride. The obtained reaction system was subjected to a nitrogen purge. Thereafter, procedures were conducted in a way similar to the modification reaction in the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B)c).

Procedures were conducted in a way similar to the purification procedure in the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B)c). The obtained modified copolymerized polyester resin (B)i was analyzed so as to confirm addition of maleic anhydride, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B)i was confirmed to have maleic anhydride added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of dimethyl isophthalate, <NUM> parts of ethylene glycol, <NUM> parts of neopentyl glycol, and <NUM> part of tetra-n-butyl titanate as a catalyst. The obtained mixture was subjected to a transesterification reaction at <NUM> to <NUM> for <NUM> hours. After confirming distillation of a prescribed amount of methanol, the reaction temperature was raised to <NUM>, and the generated condensation water was distilled away under reduced pressure. While the reaction temperature was gradually raised, the degree of reduction in pressure was gradually lowered so as to allow the temperature and the pressure to eventually reach <NUM> and <NUM> Torr in <NUM> minutes, and the polymerization reaction was finished. The melted copolymerized polyester resin J was taken out from the flask into a heat-resistant tray, and measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, glass transition temperature: <NUM>, breaking strength: <NUM> MPa, and breaking elongation: <NUM>%. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A) J crushed into flakes, <NUM> parts of toluene, and <NUM> parts of maleic anhydride. The obtained reaction system was subjected to a nitrogen purge. Thereafter, procedures were conducted in a way similar to the modification reaction in the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B)c).

Procedures were conducted in a way similar to the purification procedure in the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B)c). The obtained modified copolymerized polyester resin (B) j was analyzed so as to confirm addition of itaconic acid, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B) j was confirmed to have itaconic acid added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of ethylene glycol, <NUM> parts of <NUM>,<NUM>-propylene glycol, and <NUM> part of tetra-n-butyl titanate as a catalyst. The obtained mixture was subjected to a transesterification reaction at <NUM> to <NUM> for <NUM> hours. After confirming distillation of a prescribed amount of methanol, <NUM> parts of adipic acid was charged, the reaction temperature was gradually raised to <NUM>, and the generated condensation water was distilled away. After the temperature reached <NUM>, the condensation water which was further generated was distilled away under reduced pressure. While the reaction temperature was gradually raised, the degree of reduction in pressure was gradually lowered so as to allow the temperature and the pressure to eventually reach <NUM> and <NUM> Torr in <NUM> minutes, and the polymerization reaction was finished. The melted copolymerized polyester resin was taken out from the flask into a heat-resistant tray, and measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, glass transition temperature: <NUM>, breaking strength: <NUM> MPa, and breaking elongation: <NUM>%. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A)K crushed into flakes, <NUM> parts of toluene, and <NUM> parts of maleic anhydride. The obtained reaction system was subjected to a nitrogen purge. Thereafter, procedures were conducted in a way similar to the modification reaction in the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B) a). The obtained solution having a solid content concentration of the modified copolymerized polyester resin (B)k of about <NUM> mass% was dried in a hot-air oven set at <NUM> for <NUM> minutes so as to prepare a cast film. The prepared cast film was analyzed so as to confirm addition of maleic anhydride, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B)k was confirmed to have maleic anhydride added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of dimethyl isophthalate, <NUM> parts of <NUM>-methyl-<NUM>,<NUM>-propyleneglycol, <NUM> parts of <NUM>,<NUM>-butanediol, and <NUM> part of tetra-n-butyl titanate as a catalyst. The obtained mixture was subjected to a transesterification reaction at <NUM> to <NUM> for <NUM> hours. After confirming distillation of a prescribed amount of methanol, <NUM> parts of adipic acid and <NUM> parts of trimellitic acid were charged, and the reaction temperature was gradually raised to <NUM>, and the generated condensation water was distilled away. Thereafter, procedures were conducted in a way similar to the polymerization reaction in the Reference Synthesis Example <NUM> (copolymerized polyester resin (A)A). After the polymerization reaction was finished, the temperature in the system was lowered to <NUM> under a nitrogen atmosphere, <NUM> parts of trimellitic acid was charged into the system, and the addition reaction of trimellitic acid was finished in a way similar to the Reference Synthesis Example <NUM> (copolymerized polyester resin (A)A), whereby the copolymerized polyester resin (A) L was obtained. The obtained copolymerized polyester resin was measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, glass transition temperature: <NUM>, breaking strength: <NUM> MPa, and breaking elongation: <NUM>%. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A) L crushed into flakes, <NUM> parts of toluene, and <NUM> parts of maleic anhydride. The obtained reaction system was subjected to a nitrogen purge. Thereafter, procedures were conducted in a way similar to the modification reaction in the Reference Synthesis Example <NUM> (modified copolymerized polyester resin (B) a). The obtained solution having a solid content concentration of the modified copolymerized polyester resin (B)l of about <NUM> mass% was dried in a hot-air oven set at <NUM> for <NUM> minutes so as to prepare a cast film. The prepared cast film was analyzed so as to confirm addition of maleic anhydride, determine the addition amount thereof, and measure the number-average molecular weight. As a result of the measurement, the modified copolymerized polyester resin (B) l was confirmed to have maleic anhydride added thereto. The value determined as the addition amount was <NUM> mass%, and the number-average molecular weight was <NUM>. Table <NUM> shows these results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a Liebig condenser were charged <NUM> parts of dimethyl terephthalate, <NUM> parts of dimethyl isophthalate, <NUM> parts of trimellitic acid, <NUM> parts of <NUM>,<NUM>-cyclohexanedimethanol, <NUM> parts of <NUM>-methyl-<NUM>,<NUM>-propyleneglycol, and <NUM> part of tetra-n-butyl titanate as a catalyst. The obtained mixture was subjected to a transesterification reaction at <NUM> to <NUM> for <NUM> hours. After confirming distillation of a prescribed amount of methanol, the reaction temperature was raised to <NUM>, and the generated condensation water was distilled away under reduced pressure. While the reaction temperature was gradually raised, the degree of reduction in pressure was gradually lowered so as to allow the temperature and the pressure to eventually reach <NUM> and <NUM> Torr in <NUM> minutes, and the polymerization reaction was finished. Next, the reaction system was returned to ordinary pressure, the temperature in the system was lowered to <NUM> while nitrogen gas was sealed in the system, and <NUM> parts of trimellitic acid was charged into the system. While the temperature in the system was maintained at <NUM>, the system was stirred in a nitrogen atmosphere for <NUM> minutes, and the addition reaction of trimellitic acid was finished. The melted copolymerized polyester resin was taken out from the flask into a heat-resistant tray, and measured for the resin composition, the number-average molecular weight, the acid value, the glass transition temperature, and the breaking strength and the breaking elongation of the film. The obtained measurement results were number-average molecular weight: <NUM>, acid value: <NUM> eq/ton, and glass transition temperature: <NUM>. The breaking strength and breaking elongation could not be measured because the film was brittle. Table <NUM> shows these measurement results together with a result of analyzing the resin composition.

Comparative Synthesis Examples <NUM> to <NUM> each represent a case wherein the essential components (the component x, the component y, and the component z) of the copolymerized polyester resin (A) of the present invention are not contained in the copolymerization composition. Comparative Synthesis Example <NUM> represents a case wherein an acid addition treatment was performed by a conventional method.

Described below are Examples, Reference Examples and Comparative Examples using the modified copolymerized polyester resins (B) obtained in the Synthesis Examples, Reference Synthesis Examples and the Comparative Synthesis Examples.

Evaluation was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using a <NUM> mass% solution of the modified copolymerized polyester resin (B)a obtained in Reference Synthesis Example <NUM>. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A)A crushed into flakes, <NUM> parts of toluene, and <NUM> parts of maleic anhydride. The obtained reaction system was subjected to a nitrogen purge. The temperature in the vessel was raised to <NUM> while the reaction system was gently stirred. The reaction system was stirred for <NUM> hour so as to dissolve the copolymerized polyester resin (A)A and maleic anhydride. Next, <NUM> parts of di-tert-butyl peroxide was charged, and the temperature in the reaction system was raised to <NUM> while the reaction system was stirred at high speed. After a reaction was conducted at <NUM> for <NUM> hours, the reaction system was cooled. When the temperature was lowered to <NUM> or lower, the reaction system was returned to ordinary pressure. Next, the temperature of the reaction system was raised again, and <NUM> parts of toluene was distilled away at <NUM>. Then, <NUM> parts of deionized water, <NUM> parts of tetrahydrofuran, and <NUM> parts of isopropyl alcohol were charged, and the temperature in the system was set to <NUM>. After stirring for <NUM> hours, <NUM> parts of dimethylaminoethanol was added, and the system was gradually cooled to <NUM> over <NUM> hours. Next, the organic solvent component was distilled away at a degree of reduction in pressure of <NUM> kPa, and thus a water dispersion (emulsion) Ea having a solid content concentration of about <NUM> mass% was obtained. The water dispersion Ea was measured for the Z-average particle size, the pH, the viscosity, the solid content concentration, and the number-average molecular weight. Table <NUM> shows the results of the measurement. According thereto, Z-average particle size is <NUM>, pH is <NUM>, viscosity is <NUM> mPa · s, solid content concentration is <NUM> mass%, and number-average molecular weight is <NUM>. Further, the water dispersion Ea was left (to stand still) at <NUM> for <NUM> months and measured for the change over time. The same table shows the results.

Evaluation was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using a <NUM> mass% solution of the modified copolymerized polyester resin (B)b obtained in Synthesis Example <NUM>. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results.

Into a <NUM>-L inner-volume reaction vessel of an autoclave were charged <NUM> parts of the copolymerized polyester resin (A)B crushed into flakes, <NUM> parts of toluene, and <NUM> parts of itaconic anhydride. The obtained reaction system was subjected to a nitrogen purge. The temperature in the vessel was raised to <NUM> while the reaction system was gently stirred. The reaction system was stirred for <NUM> hour so as to dissolve the copolymerized polyester resin (A)B and itaconic anhydride. Next, <NUM> parts of di-tert-butyl peroxide was charged, and the temperature in the reaction system was raised to <NUM> while the reaction system was stirred at high speed. After a reaction was conducted at <NUM> for <NUM> hours, the reaction system was cooled. When the temperature was lowered to <NUM> or lower, the reaction system was returned to ordinary pressure. Next, the temperature of the reaction system was raised again, and <NUM> parts of toluene was distilled away at <NUM>. Then, <NUM> parts of deionized water, <NUM> parts of tetrahydrofuran, and <NUM> parts of isopropyl alcohol were charged, and the temperature in the system was set to <NUM>. After stirring for <NUM> hours, <NUM> parts of dimethylaminoethanol was added, and the system was gradually cooled to <NUM> over <NUM> hours. Next, the organic solvent component was distilled away at a degree of reduction in pressure of <NUM> kPa, and thus a water dispersion (emulsion) Eb having a solid content concentration of about <NUM> mass% was obtained. The water dispersion Eb was measured for the average particle size, the pH, the viscosity, the solid content concentration, and the number-average molecular weight. Table <NUM> shows the results of the measurement. According thereto, average particle size is <NUM>, pH is <NUM>, viscosity is <NUM> mPa · s, solid content concentration is <NUM> mass%, and number-average molecular weight is <NUM>. Further, the water dispersion Eb was left (to stand still) at <NUM> for <NUM> months and measured for the change over time. The same table shows the results.

The purified resin of the modified copolymerized polyester resin (B)c obtained in Reference Synthesis Example <NUM> was dissolved in a mixed solution containing methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio) to prepare a solution having a resin solid content concentration of <NUM> mass%. Evaluation was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using this <NUM> mass% solution. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results.

Into a <NUM>-L four-necked flask equipped with a stirrer, a thermometer, and a condenser were charged <NUM> parts of the modified copolymerized polyester resin (B)c after the purification, <NUM> parts of tetrahydrofuran, <NUM> parts of isopropyl alcohol, <NUM> parts of methyl ethyl ketone, and <NUM> parts of deionized water. The temperature in the flask was raised to <NUM> while the reaction system was stirred. After stirring for <NUM> hours, <NUM> parts of dimethylaminoethanol was added, and the system was gradually cooled to <NUM> over <NUM> hours. Next, the organic solvent component was distilled away at a degree of reduction in pressure of <NUM> kPa, and thus a water dispersion (emulsion) Ec having a solid content concentration of about <NUM> mass% was obtained. The water dispersion Ec was measured for the average particle size, the pH, the viscosity, the solid content concentration, and the number-average molecular weight. Table <NUM> shows the results of the measurement. According thereto, average particle size is <NUM>, pH is <NUM>, viscosity is <NUM> mPa · s, solid content concentration is <NUM> mass%, and number-average molecular weight is <NUM>. Further, the water dispersion Ec was left (to stand still) at <NUM> for <NUM> months and measured for the change over time. The same table shows the results.

Evaluation of epoxy curing properties and isocyanate curing properties was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using a <NUM> mass% solution of the modified copolymerized polyester resin (B)d obtained in Synthesis Example <NUM>. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. A water dispersion (emulsion) Ed was prepared in a way similar to the Reference Example <NUM> (water dispersion Ea), except that the copolymerized polyester resin was changed to the copolymerized polyester resin (A)D. The water dispersion Ed was measured for various properties. Table <NUM> shows the results of the measurement. According thereto, average particle size is <NUM>, pH is <NUM>, viscosity is <NUM> mPa · s, solid content concentration is <NUM> mass%, and number-average molecular weight is <NUM>. Further, the water dispersion Ed was left (to stand still) at <NUM> for <NUM> months and measured for the change over time. The same table shows the results.

Evaluation of epoxy curing properties and isocyanate curing properties was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using a <NUM> mass% solution of the modified copolymerized polyester resin (B)e obtained in Synthesis Example <NUM>. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. A water dispersion (emulsion) Ee was prepared in a way similar to the Reference Example <NUM> (water dispersion Ea), except that the copolymerized polyester resin was changed to the copolymerized polyester resin (A)E. The water dispersion Ee was measured for various properties. Table <NUM> shows the results of the measurement. According thereto, average particle size is <NUM>, pH is <NUM>, viscosity is <NUM> mPa · s, solid content concentration is <NUM> mass%, and number-average molecular weight is <NUM>. Further, the water dispersion Ee was left (to stand still) at <NUM> for <NUM> months and measured for the change over time. The same table shows the results.

The purified resin of the modified copolymerized polyester resin (B)f obtained in Reference Synthesis Example <NUM> was dissolved in a mixed solution containing methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio) to prepare a solution having a resin solid content concentration of <NUM> mass%. Evaluation was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using this <NUM> mass% solution. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. A water dispersion (emulsion) Ef was prepared in a way similar to the Reference Example <NUM> (water dispersion Ec), except that the modified copolymerized polyester resin was changed to the purified resin of the modified copolymerized polyester resin (B)f. The water dispersion Ef was measured for various properties. Table <NUM> shows the results of the measurement. According thereto, average particle size is <NUM>, pH is <NUM>, viscosity is <NUM> mPa·s, solid content concentration is <NUM> mass%, and number-average molecular weight is <NUM>. Further, the water dispersion Ef was left (to stand still) at <NUM> for <NUM> months and measured for the change over time. The same table shows the results.

The purified resin of the modified copolymerized polyester resin (B)g obtained in Synthesis Example <NUM> was dissolved in a mixed solution containing methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio) to prepare a solution having a resin solid content concentration of <NUM> mass%. Evaluation was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using this <NUM> mass% solution. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. A water dispersion (emulsion) Eg was prepared in a way similar to the Reference Example <NUM> (water dispersion Ec), except that the modified copolymerized polyester resin was changed to the purified resin of the modified copolymerized polyester resin (B) g. The water dispersion Eg was measured for various properties. Table <NUM> shows the results of the measurement. According thereto, average particle size is <NUM>, pH is <NUM>, viscosity is <NUM> mPa · s, solid content concentration is <NUM> mass%, and number-average molecular weight is <NUM>. Further, the water dispersion Eg was left (to stand still) at <NUM> for <NUM> months and measured for the change over time. The same table shows the results.

Evaluation of epoxy curing properties and isocyanate curing properties was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using a <NUM> mass% solution of the modified copolymerized polyester resin (B)h obtained in Synthesis Example <NUM>. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. A water dispersion (emulsion) Eh was prepared in a way similar to the Reference Example <NUM> (water dispersion Ea), except that the copolymerized polyester resin was changed to the copolymerized polyester resin (A)H. The water dispersion Eh was measured for various properties. Table <NUM> shows the results of the measurement. According thereto, average particle size is <NUM>, pH is <NUM>, viscosity is <NUM> mPa · s, solid content concentration is <NUM> mass%, and number-average molecular weight is <NUM>. Further, the water dispersion Eh was left (to stand still) at <NUM> for <NUM> months and measured for the change over time. The same table shows the results.

The purified resin of the modified copolymerized polyester resin (B)i obtained in Comparative Synthesis Example <NUM> was dissolved in a mixed solution containing methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio) to prepare a solution having a resin solid content concentration of <NUM> mass%. Evaluation was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using this <NUM> mass% solution. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. We tried to prepare a water dispersion (emulsion) Ei in a way similar to the Reference Example <NUM> (water dispersion Ec), except that the modified copolymerized polyester resin was changed to the purified resin of the modified copolymerized polyester resin (B)i. However, we could not obtain any water dispersion (emulsion).

The purified resin of the modified copolymerized polyester resin (B) j obtained in Comparative Synthesis Example <NUM> was dissolved in a mixed solution containing methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio) to prepare a solution having a resin solid content concentration of <NUM> mass%. Evaluation was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using this <NUM> mass% solution. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. We tried to prepare a water dispersion (emulsion) Ej in a way similar to the Reference Example <NUM> (water dispersion Ec), except that the modified copolymerized polyester resin was changed to the purified resin of the modified copolymerized polyester resin (B)j. However, we could not obtain any water dispersion (emulsion).

Evaluation of epoxy curing properties and isocyanate curing properties was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using a <NUM> mass% solution of the modified copolymerized polyester resin (B)k obtained in Comparative Synthesis Example <NUM>. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. We tried to prepare a water dispersion (emulsion) Ek in a way similar to the Reference Example <NUM> (water dispersion Ea), except that the copolymerized polyester resin was changed to the copolymerized polyester resin (A)K. However, we could not obtain any water dispersion (emulsion).

Evaluation of epoxy curing properties and isocyanate curing properties was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using a <NUM> mass% solution of the modified copolymerized polyester resin (B)l obtained in Comparative Synthesis Example <NUM>. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. A water dispersion (emulsion) El was prepared in a way similar to the Reference Example <NUM> (water dispersion Ea), except that the copolymerized polyester resin was changed to the copolymerized polyester resin (A)L. The water dispersion Ed was measured for various properties. Table <NUM> shows the results of the measurement. According thereto, average particle size is <NUM>, pH is <NUM>, viscosity is <NUM> mPa·s, solid content concentration is <NUM> mass%, and number-average molecular weight is <NUM>. The water dispersion El was left (to stand still) at <NUM> for <NUM> months. The water dispersion was aggregated. Accordingly , it was impossible to measure the change of various properties over time.

The copolymerized polyester resin (A)A obtained in Reference Synthesis Example <NUM> without being subjected to the acid addition modification was dissolved in a mixed solution containing methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio) to prepare a solution having a resin solid content concentration of <NUM> mass%. Evaluation was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using this <NUM> mass% solution. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. We tried to prepared a water dispersion (emulsion) of the copolymerized polyester resin (A)A instead of the purified resin of the modified copolymerized polyester resin (B)c in a way similar to the Reference Example <NUM> (water dispersion Ec). However, we could not obtain any water dispersion (emulsion).

The copolymerized polyester resin (A)C obtained in Reference Synthesis Example <NUM> without being subjected to the acid addition modification was dissolved in a mixed solution containing methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio) to prepare a solution having a resin solid content concentration of <NUM> mass%. Evaluation was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using this <NUM> mass% solution. The values of gel fraction representing the curing properties were <NUM>% and <NUM>%, respectively. Table <NUM> shows the results. We tried to prepare a water dispersion (emulsion) of the copolymerized polyester resin (A)C instead of the purified resin of the modified copolymerized polyester resin (B)c in a way similar to the Reference Example <NUM> (water dispersion Ec). However, we could not obtain any water dispersion (emulsion).

The copolymerized polyester resin (A)M obtained in Comparative Synthesis Example <NUM> without being subjected to the acid addition modification was dissolved in a mixed solution containing methyl ethyl ketone and toluene at <NUM> : <NUM> (mass ratio) to prepare a solution having a resin solid content concentration of <NUM> mass%. Evaluation was performed according to the foregoing methods for evaluating the epoxy curing properties and the isocyanate curing properties, using this <NUM> mass% solution. The values of gel fraction representing the curing properties were <<NUM>% and <NUM>%, respectively. Table <NUM> shows the results. We tried to prepare a water dispersion (emulsion) of the copolymerized polyester resin (A)M instead of the purified resin of the modified copolymerized polyester resin (B)c in a way similar to the Reference Example <NUM> (water dispersion Ec). However, we could not obtain any water dispersion (emulsion).

Comparative Examples <NUM> to <NUM> each represent a case of using a copolymerized polyester resin not containing, as copolymerization components, the essential components (the component x, the component y, and the component z) of the copolymerized polyester resin (A) of the present invention. Comparative Examples <NUM> to <NUM> each represent a case of using a copolymerized polyester resin that contained the essential components but was not subjected to the acid addition modification of the present invention. As clarified by Tables <NUM>, <NUM>, and <NUM>, the acid addition modification reaction of the present invention hardly causes a decrease in molecular weight of the base polyester resin between before and after the modification. Also in the process of emulsification-dispersing the acid-added-and-modified resin in water, no remarkable decrease in molecular weight between before and after the emulsification process was observed, and a water dispersion of the copolymerized polyester resin having a high molecular weight and excellent storage stability can be obtained. Further, as clarified by Table <NUM>, it is understandable that the acid-added-and-modified copolymerized polyester resin (B) according to the present invention has excellent low-temperature reactivity with an epoxy curing agent and an isocyanate curing agent.

Claim 1:
A modified copolymerized polyester resin (B) having a structure in which a copolymerized polyester resin (A) has an unsaturated polyvalent carboxylic acid added to a side chain thereof, and the copolymerized polyester resin (A) contains, as copolymerization components, at least two members selected from the group consisting of: a copolymerization component having an alicyclic structure (component x); a copolymerization component having six or more continuous methylene groups (component y); and an acyclic aliphatic copolymerization component having a tertiary carbon atom and a molecular weight of more than <NUM> (component z).