Aqueous curable polyester resin composition and two-liquid curable adhesive using the same

Abstract

To provide a resin composition comprising a copolymerized polyester resin which has easily water-dispersible properties without requiring an organic solvent or an emulsifier and reacts with a multifunctional epoxy resin under room temperature to exhibit, for example, a stable adhesive function as an adhesive.SOLUTION: There is provided an aqueous curable polyester resin composition comprising the following components A, B and C. Component A): a copolymerized polyester resin satisfying the following (1) to (4). (1) The acid value is 700 eq / ton or more. (2) The number average molecular weight is more than 5000. (3) The polycarboxylic acid component is constituted from an aromatic polycarboxylic acid component. (4) The polyol component contains a linear glycol compound. Component B): a basic neutralizing agent. Component C): a water-soluble multifunctional epoxy resin having 4 or more epoxy functional groups on average in one molecule.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an aqueous curable resin composition which forms a film at room temperature without requiring an organic solvent or a film-forming assistant, and in which a curing reaction proceeds at room temperature, and which is suitable for use in paints, coating agents, adhesives, and the like. More specifically, the present invention relates to a two-component curing aqueous adhesive using the same. [Background technology]

[0002] Polyester resins have excellent mechanical properties and heat resistance, and can be given a variety of physical properties by selecting the raw monomers that make up the resins, so they are used in paints, adhesives, coatings, molded products, etc. In recent years, due to environmental concerns, regulations on the emission of volatile organic solvents have become stricter, and paints, inks, adhesives, coatings, pressure sensitive adhesives, sealants, primers, and various treatment agents for textile products and paper products are shifting from conventional organic solvent-based to water-based, high solid, and powder-based. Among these, water-based solutions using water dispersions are being widely adopted in various industries as the most versatile method in terms of ease of use and improvement of the working environment. In particular, there has been an increase in the number of cases in which water dispersions that do not contain any organic solvents are adopted recently.

[0003] Conventionally, methods for preparing an aqueous dispersion of a polyester resin that does not contain any organic solvent include (1) a method in which a polyester resin having a hydrophilic functional group in its molecular chain is once dissolved in a water-soluble organic solvent having a boiling point lower than that of water, and water is gradually added to the system to emulsify it, and then the organic solvent is removed by distillation or the like, or (2) a method in which a polyester resin having a hydrophilic functional group in its molecular chain is dissolved in a mixture of an organic solvent and water, and then the organic solvent component is removed. Patent documents 1 to 3 describe examples of such methods, but there are problems in that the use of an organic solvent in the aqueous dispersion process of a polyester resin deteriorates the working environment, and the process takes time, resulting in poor working efficiency. Patent document 4 also discloses an example of an aqueous dispersion that does not require an organic solvent in the manufacturing process, in which a hydrophilic polymer is used as an emulsifier and a polylactic acid resin is dispersed in water in the presence of the emulsifier, but in this case, problems arise in that the coexistence of the emulsifier reduces the resin properties, adhesive performance, or water resistance of the coating film.

[0004] In view of the above, there is a demand for an aqueous dispersion of a polyester resin that does not use organic solvents or emulsifiers in the production process. Patent Documents 5 to 7 have proposed methods that do not use organic solvents or emulsifiers in the production process. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 7-82381 [Patent Document 2] Patent Publication 2009-51965 [Patent Document 3] Patent Publication No. 2007-277497 [Patent Document 4] Patent Publication No. 2008-13657 [Patent Document 5] Special Public Notice 47-40873 [Patent Document 6] International Publication 2019 / 111746 [Patent Document 7] Patent Publication No. 2003-192886 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the water-soluble copolyester described in Patent Document 5 has an extremely high sulfonate group concentration, and the sulfonate remains even after drying, which causes a problem in water resistance when the coating is formed. It is possible to make an aqueous dispersion without containing an organic solvent and an emulsifier, that is, it is brittle, and there is a problem that sufficient adhesive strength is not developed when used as an adhesive. It is also possible to add a curing agent to impart cohesive strength, but as described in the examples, it is necessary to provide a curing reaction treatment process to promote curing. In addition, Patent Document 7 proposes an aqueous dispersion obtained by emulsifying a polyester resin having a high concentration of hydroxyl groups and carboxyl groups and a special polyvalent carboxylic acid compound having an alkyl group or an alkenyl group from a molten state using a rotary type continuous dispersion device, and a resin composition containing a water-soluble epoxy resin and no emulsifier or organic solvent. However, the particle size of the obtained aqueous dispersion of the polyester resin is coarse, and the storage stability is insufficient.

[0007] The present invention has been made with the above-mentioned problem-solving in mind. That is, the present invention relates to an aqueous curable polyester resin composition that can be easily dispersed in water without the presence of an organic solvent or an emulsifier and can form a stable aqueous dispersion of fine particles. The resin composition does not require special curing reaction conditions, and the curing reaction proceeds without a catalyst at room temperature to obtain cohesive force. Therefore, when used as an adhesive, it exhibits sufficient adhesive strength and is characterized by excellent water resistance after drying of the coating film. [Means for solving the problem]

[0008] As a result of extensive investigations, the present inventors have found that the above problems can be solved by the means described below, and have arrived at the present invention.

[0009] [1] A water-based curable polyester resin composition containing components A, B and C below. Component A) A copolymer polyester resin that satisfies the following (1) to (4): (1) Acid value is 700 eq / ton or more (2) Number average molecular weight exceeds 5,000 (3) The polycarboxylic acid component is composed of an aromatic polycarboxylic acid component. (4) The polyol component contains a linear glycol compound B) Basic neutralizer C) Water-soluble multifunctional epoxy resin with an average of 4 or more epoxy functional groups per molecule [2] The aqueous curable polyester resin composition according to [1], containing 70 mol % or more of a linear glycol compound, based on 100 mol % of the total polyol components of the component A. [3] The aqueous curable polyester resin composition according to [1] or [2], wherein the linear glycol compound comprises an alkylene glycol and an ether glycol. [4] The aqueous curable polyester resin composition according to any one of [1] to [3], wherein the composition contains an ether glycol in an amount of from 5 mol % to 40 mol % relative to the total amount of the polyol components in the component A being 100 mol %. [5] The aqueous curable polyester resin composition according to any one of [1] to [4], wherein the ether glycol is diethylene glycol. [6] A two-component curing adhesive comprising the aqueous curing polyester resin composition according to any one of [1] to [5]. Effect of the Invention

[0010] The copolymer polyester resin (A component) is water-dispersible in the presence of a basic neutralizer (B component) without the need for an organic solvent or an emulsifier, and forms a stable aqueous dispersion. By having an appropriate molecular weight, acid value, and specific structure, the following functions can be achieved simultaneously. That is, by reacting with a water-soluble multifunctional epoxy resin (C component) having an average epoxy functional group number of 4 or more per molecule at room temperature, a three-dimensional network structure is formed, and the cohesive force of the resin composition can be improved. Therefore, when used as an adhesive, stable adhesive performance can be obtained. In addition, there is no need to increase the sulfonate group concentration to produce an aqueous dispersion, and the water resistance after drying of the coating film is also excellent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following describes an embodiment of the present invention, but the present invention is not limited to this and can be practiced in various modified forms within the scope of the description.

[0012] The aqueous curable polyester resin composition of the present invention contains a copolymerized polyester resin (Component A), a basic neutralizing agent (Component B), and a water-soluble polyfunctional epoxy resin (Component C) having an average number of epoxy functional groups per molecule of 4 or more.

[0013] <Component A: Copolymerized Polyester Resin> As an example of the copolymerized polyester resin (Component A) used in the present invention, it has a structure obtained by polymerizing a polycarboxylic acid component and a polyol component. The polycarboxylic acid and the polyalcohol are each composed of one or more selected components.

[0014] In the copolymerized polyester resin (Component A) used in the present invention, the polycarboxylic acid component is composed of an aromatic polycarboxylic acid component. Examples of the aromatic polycarboxylic acid include, as a bifunctional carboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, etc., and as a trifunctional or higher-functional carboxylic acid, trimellitic acid, pyromellitic acid, and their anhydrides, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, etc. One or more of these can be used. From the viewpoint of the general availability of raw materials, among them, terephthalic acid, isophthalic acid, and orthophthalic acid are preferable. By being composed of an aromatic polycarboxylic acid, it is possible to make the resulting solid polyester resin into pellets or flakes, and the handleability is particularly excellent.

[0015] When using a trifunctional or higher-functional carboxylic acid as the aromatic polycarboxylic acid, it is preferably used in the range of 10 mol% or less when the total polycarboxylic acid component is 100 mol%. More preferably, it is 7 mol% or less, and still more preferably, it is 5 mol% or less. By setting it below the lower limit value, it is easy to copolymerize within the range where the resulting polyester resin does not gel.

[0016] The copolymerized polyester resin (component A) used in the present invention contains a linear glycol compound as a polyol component. Examples of the linear glycol compound include alkylene glycol and ether glycol. Examples of the alkylene glycol include ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol, and examples of the ether glycol include diethylene glycol and triethylene glycol.

[0017] When the polyester resin (component A) copolymerized with these linear glycols is used as an adhesive layer for laminating a film substrate such as PET, it has the effect of improving the peel strength in an uncured state without blending a curing agent. When the total polyol component of the copolymerized polyester resin is taken as 100 mol%, the linear glycol compound is preferably contained at 70 mol% or more, more preferably at 80 mol% or more, and even more preferably at 90 mol% or more, and thus the adhesive strength in an uncured state is better.

[0018] Among the linear glycol compounds, the ether glycols are highly hydrophilic and are expected to enhance the water dispersion function of the copolymerized polyester resin (component A). Among them, diethylene glycol is preferred from the viewpoint of versatility of the raw material. When the total glycol component is taken as 100 mol%, the copolymerization amount of the ether glycol is preferably 5 mol% to 40 mol%, more preferably 10 % to 30 mol%, and most preferably 15 mol% to 25 mol%. If it is less than 5 mol%, the hydrophilicity improvement effect by copolymerization cannot be obtained sufficiently, and if it exceeds 40 mol%, the glass transition temperature of the copolymerized polyester resin produced is low, and the solid resin becomes difficult to handle in pellet or flake form. In addition, as the linear alkylene glycol, ethylene glycol is preferable from the viewpoint of being difficult to lower the glass transition temperature, considering the versatility of the raw material and the fact that the copolymerized polyester resin produced can be handled in pellet or flake form.

[0019] The polyol component more preferably contains an alkylene glycol and an ether glycol as the linear glycol compound.

[0020] Examples of polyol components other than the linear glycols include branched glycol compounds such as aliphatic polyols such as 1,2-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 2-methyl-1,3-propylene glycol, neopentyl glycol, 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropanate, and 2,2-diethyl-1,3-propylene glycol; and 1,3-bis(hydroxymethyl)cyclohexane and 1,4-bis(hydroxymethyl)cyclohexane. 1,4-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxyethyl)cyclohexane, 1,4-bis(hydroxypropyl)cyclohexane, 1,4-bis(hydroxymethoxy)cyclohexane, 1,4-bis(hydroxyethoxy)cyclohexane, 2,2-bis(4-hydroxymethoxycyclohexyl)propane, 2,2-bis(4-hydroxyethoxycyclohexyl)propane, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane, 3(4),8(9)-tricyclo[5.2.1.0 2,6] Alicyclic polyols such as decanedimethanol and aromatic polyols such as ethylene oxide adducts of bisphenol A can also be used. These can be used alone or in combination of two or more. When using these other glycol components, 1,2-propylene glycol, 2-methyl-1,3-propylene glycol, neopentyl glycol, and 1,4-bis(hydroxymethyl)cyclohexane are preferred from the viewpoint of versatility and not excessively lowering the glass transition temperature of the resulting copolymerized polyester resin. The copolymerization amount of these branched glycol components is preferably less than 30 mol%, more preferably less than 15 mol%, and even more preferably less than 10 mol%, when the total polyol component amount is taken as 100 mol%, and may be 0 mol%. If the copolymerization amount of these glycol components exceeds 30 mol%, the cohesive force of the resulting copolymerized polyester resin is weakened, and especially when used as an adhesive layer for a film substrate such as PET, the peel strength tends to be significantly reduced in an uncured state without containing a curing agent.

[0021] In addition to the polycarboxylic acid component and the polyol component, the copolymerized polyester resin (component A) may be copolymerized with a polyol compound having three or more functional groups, such as glycerin, trimethylolpropane, pentaerythritol, or dipentaerythritol, to the extent that the copolymerized polyester resin (component A) does not gel, to facilitate higher molecular weight, or to provide a reaction site with an acid anhydride compound added after the polymerization reaction described below. When the polyol compound having three or more functional groups is copolymerized, the copolymerization amount is preferably 0.5 mol% or more, more preferably 1 mol% or more, when the total glycol component amount of the copolymerized polyester resin (component A) is 100 mol%. The upper limit is preferably 10 mol% or less, more preferably 8 mol% or less. If it exceeds 10 mol%, the molecular weight distribution of the copolymerized polyester resin produced tends to be broadened and gelation tends to occur easily.

[0022] In addition, the copolymer polyester resin (component A) used in the present invention can be subjected to an addition reaction (post-addition) of a carboxylic acid anhydride compound such as trimellitic acid at the molecular terminal after the polymerization reaction is completed, thereby imparting an acid value. When the carboxylic acid anhydride compound is added by reaction, the amount of addition is 5 mol% or more, more preferably 8 mol%, assuming that the total carboxylic acid components are 100 mol%. The upper limit is preferably 20 mol % or less, more preferably 15 mol % or less. If it is less than 5 mol %, a sufficient acid value for water dispersion cannot be added, and if it exceeds 20 mol %, a large amount of unreacted carboxylic anhydride compound that is not added tends to remain.

[0023] The acid value of the copolymerized polyester resin (A component) of the present invention is 700 eq / ton or more, preferably 800 eq / ton or more, more preferably 900 eq / ton or more. If it is less than 700 eq / ton, it is difficult to disperse in water under conditions in which no organic solvent or emulsifier is present, or the storage stability of the prepared water dispersion is poor, and sediment is likely to form during storage. It is also preferably 1500 eq / ton or less, more preferably 1400 eq / ton or less, and even more preferably 1300 eq / ton or less. On the other hand, if an attempt is made to introduce an acid value of more than 1500 eq / ton, it is necessary to further increase the number of terminal groups of the polyester resin in order to secure the addition reaction site of the carboxylic acid anhydride, so that it is necessary to further reduce the molecular weight or further branch the molecular chain. If the molecular weight is further reduced, even if the C component of the present invention is blended, a sufficient crosslinked structure is not formed in the reaction at room temperature, and a cured coating film having cohesive force is not formed. In addition, if the molecular chain is further branched, gel components are easily formed during the polymerization reaction, and stable productivity cannot be obtained.

[0024] The concentration of the sulfonic acid metal salt in the copolymerized polyester resin (component A) in the present invention is preferably less than 50 eq / ton. More preferably, it is 20 eq / ton or less, further preferably, it is 10 eq / ton or less, and particularly preferably, it is 5 eq / ton or less. By making it less than 50 eq / ton, the water resistance of the obtained coating film is improved.

[0025] The number average molecular weight of the copolymerized polyester resin (component A) of the present invention is more than 5000, preferably 5500 or more, more preferably 6000 or more. It is also preferably 10000 or less, more preferably 8000 or less. If the number average molecular weight is 5000 or less, the cohesive strength of the resin is insufficient, and when used as an adhesive, sufficient adhesive strength is not exhibited. In addition, since it cannot react with the water-soluble multifunctional epoxy resin (component C) at room temperature to form a sufficient three-dimensional crosslinked structure, it is difficult to improve the cohesive strength as a composition, and it is difficult to obtain the effect of adding component C. On the other hand, if it exceeds 10000, the cohesive strength of the copolymerized polyester resin becomes high, and it tends to be difficult to easily disperse it in water under conditions without organic solvents or emulsifiers.

[0026] The molecular weight distribution of the copolymerized polyester resin (component A) of the present invention is preferably 2.1 or more, more preferably 2.5 or more, and most preferably 3.0 or more, in view of the curability with the water-soluble multifunctional epoxy resin. Also, it is preferably 10.0 or less, more preferably 8.0 or less. If it is 2.0 or less, the amount of branched high molecular weight components is reduced, so that the reaction with the water-soluble multifunctional epoxy resin at room temperature tends to be difficult to proceed sufficiently. On the other hand, if it exceeds 10.0, a gel-like component is easily generated during the production of the resin, and productivity may deteriorate. The molecular weight distribution of the copolymerized polyester resin (component A) of the present invention can be easily changed by controlling the polymerization reaction time. In particular, the longer the addition reaction time in the step of adding a multifunctional carboxylic anhydride such as trimellitic acid after the polymerization reaction is completed, the larger the molecular weight distribution becomes.

[0027] The glass transition temperature of the copolyester resin (Component A) is preferably 30°C or higher, more preferably 35°C or higher, and even more preferably 40°C or higher. Also, it is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. If it is less than 30°C, it may be difficult to handle the solid resin in the form of pellets or flakes. Also, during storage of the solid resin, the degradation reaction due to hydrolysis tends to proceed easily. On the other hand, if it exceeds 100°C, the cohesive force of the resin becomes too high, and it may be difficult to disperse it in water easily.

[0028] The copolyester resin (Component A) used in the present invention can be synthesized by a conventionally well-known method. To give an example, after subjecting the mixture of the polycarboxylic acid and an excess equivalent of the polyol component to an esterification reaction in a molten state, polymerization is carried out to a predetermined molecular weight while distilling off the excess equivalent of the glycol component under a high-temperature nitrogen gas stream, and an addition reaction of an acid anhydride is carried out in a nitrogen gas atmosphere, or a method in which a mixture of dialkyl ester compounds of the polycarboxylic acid and an excess amount of the glycol component are subjected to a transesterification reaction, and then polymerization and an addition reaction of an acid anhydride compound are carried out in the same manner under a normal-pressure high-temperature nitrogen stream can be mentioned. As the polymerization catalyst, generally used compounds such as titanium-based, zinc-based, antimony-based, magnesium-based, and germanium-based compounds can be used.

[0029] <Component B: Basic neutralizing agent> The basic neutralizing agent for dispersing the copolymerized polyester resin (component A) of the present invention in water is not particularly limited, but volatile basic substances are preferred, and among them, ammonia and amines are preferred. The amines are not particularly limited, but 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 (dimethylaminoethanol), and N,N-dimethylpropanolamine, etc. Particularly preferred are triethylamine and N,N-dimethylethanolamine (dimethylaminoethanol). These volatile amines can be used alone or in combination of two or more. These amine compounds can be added in an amount of 0.8 to 1.5 times the equivalent amount based on the acid value of the copolymerized polyester resin (component A). More preferably, it is 1.0 to 1.2 times the equivalent amount. If it is less than 0.8 times the equivalent amount, the storage stability of the aqueous dispersion tends to deteriorate, and if it exceeds 1.5 times the equivalent amount, the pH of the aqueous dispersion becomes too high, and the hydrolysis reaction of the copolymerized polyester resin component tends to proceed during storage.

[0030] The aqueous dispersion of the copolymerized polyester resin (component A) of the present invention can be obtained by simply stirring and mixing component A and component B in warm water at 60°C to 90°C. At that time, it is not necessary to coexist an organic solvent or an emulsifier. Therefore, it is preferable that the water-based curable polyester resin composition of the present invention substantially does not contain an organic solvent and an emulsifier, that is, the content of the organic solvent and the emulsifier is less than 1 part by mass with respect to 100 parts by mass (in terms of solid content) of the copolymerized polyester resin (component A). More preferably, it is less than 0.5 part by mass, still more preferably less than 0.1 part by mass, and most preferably it does not contain these.

[0031] <Component C: Water-soluble polyfunctional epoxy resin> The water-soluble multifunctional epoxy resin (component C) used in combination with the copolymer polyester resin (component A) as the water-based curable polyester resin composition of the present invention has an average epoxy functional group number of 4 or more per molecule. If the epoxy resin has an average epoxy functional group number of less than 4 per molecule, sufficient crosslink density cannot be obtained by reaction with component A at room temperature, and a cured coating film having cohesive strength cannot be formed. As a result, when used as an adhesive, sufficient adhesive strength cannot be obtained. The average epoxy functional group number per molecule can be determined by analyzing the multifunctional epoxy resin by GPC and dividing the number average molecular weight obtained by the epoxy equivalent. The water-soluble multifunctional epoxy resin (component C) of the present invention is not particularly limited as long as it is water-soluble and has an average epoxy functional group number of 4 or more per molecule. For example, an adduct of a glycidyl group to a sorbitol skeleton or a glycerin skeleton can be mentioned. Specific product names include Denacol EX-612, EX-614, EX-614B, EX-512, and EX-521 manufactured by Nagase ChemteX Corporation, and these can be used alone or in combination of two or more. Of these, Denacol EX-521 and EX-614B, which have the largest number of functional groups per molecule, are most preferred. The blending ratio of these water-soluble multifunctional epoxy resins (component C) is a copolymer polyester. The ratio of the epoxy group equivalent of component C to the acid value of the resin (component A) is preferably 0.8 to 2.0, and more preferably 1.0 to 1.5. If it is less than 0.8, a sufficient crosslinked structure may not be formed, and if it exceeds 2.0, the cured product may become brittle.

[0032] The aqueous curable polyester resin composition of the present invention can be cured at room temperature without the addition of a curing catalyst (general amine-based or phosphorus-based curing catalyst) to form a coating film. Therefore, it is preferable that the aqueous curable polyester resin composition of the present invention does not substantially contain a curing catalyst, that is, the content of the curing agent is preferably less than 1 part by mass (solid content equivalent) per 100 parts by mass (solid content equivalent) of the copolymerized polyester resin (component A). More preferably, it is less than 0.5 parts by mass, even more preferably, it is less than 0.1 parts by mass, and most preferably, it does not contain a curing catalyst.

[0033] The copolymerized polyester resin (component A) of the present invention can be used as a water-based curable resin composition by blending a water-soluble multifunctional epoxy resin and a water-soluble multifunctional isocyanate compound. The water-based curable polyester resin composition of the present invention does not contain an organic solvent or an emulsifier, and does not require an organic solvent in the preparation process or in the use process. It can be used as an adhesive or coating agent that is friendly to the production and use working environment.

[0034] The two-component curing adhesive of the present invention is used by blending the aqueous dispersion of the copolymerized polyester resin (component A) emulsified in water by a basic neutralizer (component B) with the water-soluble multifunctional epoxy resin (component C) before use, and applying it to a substrate as an adhesive. The aqueous dispersion and the water-soluble multifunctional epoxy resin can be blended using a stirring device such as a mixer, or can be easily mixed by hand using a spatula or a spatula. If necessary, amine-based, phenol-based, or acid anhydride-based curing agents, or curing accelerators such as tertiary amines, imidazoles, and phosphorus compounds, and organic or inorganic fillers can also be blended. The two-component curing adhesive of the present invention can be used for bonding to various substrates, but is preferably suitable for bonding to polyester substrates, and more preferably is bonded to a PET film substrate by heat-sealing, whereby it exerts particularly excellent effects. EXAMPLES

[0035] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the examples and comparative examples, parts simply indicate parts by mass. The measurement and evaluation methods used in this specification are as follows.

[0036] (1) Number average molecular weight and molecular weight distribution 15 mg of a sample (copolymerized polyester resin (component A)) was dissolved in 5 mL of tetrahydrofuran, and then filtered through a membrane filter made of polytetrafluoroethylene with a pore size of 0.2 μm. This was used as a sample solution, and was measured at a flow rate of 1 ml / min using a Waters gel permeation chromatography (GPC) 150C with tetrahydrofuran as a carrier solvent. Three columns, made by Showa Denko KF-802, KF-804, and KF-806, were connected as columns, and the column temperature was set to 30°C. A polystyrene standard substance was used as a molecular weight standard sample, and calculations were performed excluding the portion corresponding to a molecular weight of less than 1000. The analysis of the chart obtained by the measurement was performed by analyzing the main peak, and the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) were obtained.

[0037] (2) Acid value 0.2 g of the sample (copolymer polyester resin (component A)) was precisely weighed out and dissolved in 20 ml of chloroform. The content was then measured using a 0.1 N sodium hydroxide (NaOH) ethanol solution with phenolphthalein as an indicator, and the measured value was expressed as the equivalent weight (eq) per ton of resin solids.

[0038] (3) Glass transition temperature 5 mg of a sample (copolymer polyester resin (component A)) was placed in an aluminum sample pan and sealed, and was measured using a differential scanning calorimeter DSC-220 manufactured by Seiko Instruments Inc. First, the sample was cooled to -50°C with liquid nitrogen, and then heated to 200°C at a heating rate of 20°C / min. In the endothermic curve obtained during the heating process, the temperature (°C) was determined as the intersection point between an extension line of the baseline below the glass transition temperature (before the endothermic peak appears) and a tangent line showing the maximum slope in the transition section.

[0039] (4) Polyester resin composition The sample (copolymer polyester resin (component A)) was dissolved in chloroform-d, and the resulting solution was analyzed using a Varian MR-400 nuclear magnetic resonance analyzer. 1 The resin composition ratio was determined by H-NMR.

[0040] (5) Evaluation of water dispersibility Copolymer polyester resin (component A) was crushed with a hammer into flakes with a particle diameter of 1 cm or less, and stirred in deionized water at 70°C to 80°C in the presence of 1.05 equivalents of dimethylaminoethanol relative to the acid value of component A so that the resin solids concentration was 25% by weight. The vessel used was a 500 ml glass four-neck flask equipped with a thermometer, condenser, and stirring rod, and the stirring rod used two paddle blades, with the rotation speed set to 100 rpm. The state after stirring for 2 hours was evaluated using the following indicators. 〇: No undulant remains ×: Unemulsified matter remains or no emulsification at all

[0041] (6) Measurement of viscosity of aqueous dispersion (emulsion) Using a Toki Sangyo Co., Ltd. "Viscometer TV-22" (E-type viscometer), 0.6 g of sample was measured under the conditions of rotor No. 0.8° (=48') x R24, range H, rotation speed 5 rpm, and 25°C.

[0042] (7) Measurement of pH of aqueous dispersion (emulsion) The value was measured at 25°C using a "pH meter F-52" manufactured by Horiba, Ltd. The measurement instrument was calibrated at three points using a phthalate pH standard solution (pH: 4.01), a neutral phosphate pH standard solution (pH: 6.86), and a borate pH standard solution (pH: 9.18) manufactured by Wako Pure Chemical Industries, Ltd.

[0043] (8) Measurement of average particle size of water dispersion (emulsion) Measurement was performed by dynamic light scattering using a concentrated particle size analyzer "FPAR-1000" manufactured by Otsuka Electronics Co., Ltd. An aqueous dispersion with a solid content concentration of about 25% by mass was diluted with deionized water, and the light intensity was adjusted to a range of 15,000 to 40,000 cps. Measurement was performed for 60 seconds at a temperature of 25°C, and the average particle size obtained by histogram analysis was used.

[0044] (9) Storage stability evaluation of aqueous dispersion The water dispersion having a resin solid content of 25% by weight obtained in the above evaluation of water dispersibility was allowed to stand for one month in an atmosphere at 25° C., and was evaluated according to the following indices. 〇: Retains the initial state ×: Sedimentation or increased viscosity was observed

[0045] (10) Evaluation of room temperature epoxy curing The copolymer polyester resin (A component) was dispersed in water with a basic neutralizer (B component), and Denacol EX521 (Nagase Chemte) was added as a water-soluble multifunctional epoxy resin (C component) to the water dispersion. Polyglycerol polyglycidyl ether type multifunctional epoxy resin (manufactured by Epoxy Corporation) was mixed so that the epoxy value relative to the acid value of component A was 1.3, and coated on the corona-treated surface of a 25 μm thick PET film so that the coating thickness after drying was about 10 μm. In the comparative example, the epoxy value relative to the acid value of the polyester resin was also mixed so that it was 1.3. The coated sample was air-dried for 3 hours at a room temperature of about 20 degrees, and then stored in an incubator at 25 ° C. After storage, 1 day, 3 days, and 5 days later, strip-shaped coating film test pieces of 2 cm × 10 cm were cut out. The test pieces were precisely weighed, then immersed in a mixed solvent of methyl ethyl ketone / toluene = 50 / 50 (mass ratio), and left at room temperature at about 20 ° C. for 1 hour. The test pieces were taken out and dried, and then precisely weighed again, and the mass change before and after immersion was calculated from the following gel (solvent insoluble component) fraction calculation formula, which was used as an index of curability. Gel fraction (%) = (dry mass of test piece after immersion - mass of 2 cm x 10 cm base film) / (mass of test piece before immersion - mass of 2 cm x 10 cm base film) x 100 For the coated sample after standing at 25° for 5 days, the following evaluation index was assigned based on the gel fraction (%) calculated using the above formula. Gel fraction (%): 70% or more and 100% or less... 〇 Gel fraction (%): 50% or more and less than 70%... △ Gel fraction (%): Less than 50% ×

[0046] (11) Evaluation of PET film adhesion-1 [PET adhesion of uncured sample (copolymer polyester resin (component A) alone)] The aqueous dispersion of copolymerized polyester resin (component A) prepared in the above "(5) Evaluation of water dispersibility" was coated on the non-corona treated side of a 25 μm thick PET film using a wire bar without blending with a water-soluble multifunctional epoxy resin (component C), and dried for 3 minutes in a hot air drying oven at 120°C to produce a coating film with a thickness of approximately 5 μm. Next, a rectangular coated film sample with a width of 1 inch was cut out, and the coated surfaces were overlapped and melt-bonded at 180°C for 1 second under a pressure of 3 kgf / cm2. The obtained test piece was then subjected to a fusion bonding test using an autograph "AG-X" manufactured by Shimadzu Corporation. The 90° peel strength was measured at a pulling speed of 20 mm / min using a "plus" tester. 1.0N / inch or more 〇 0.1N / inch or more and less than 1.0N / inch...△ Less than 0.1N / inch ×

[0047] (12) Evaluation of PET film adhesion-2 [Evaluation as a water-based curable polyester resin composition] The water-soluble multifunctional epoxy resin (component C) was mixed with the water dispersion of the copolymerized polyester resin (component A) prepared in the above "(5) Evaluation of water dispersibility" so that the epoxy group equivalent to the acid value of component A was 1.3 times, and an adhesion test piece was prepared in the same manner as in the above "(11) Evaluation of adhesion -1". The obtained adhesion test piece was stored in a 25°C incubator, and after 30 minutes, 24 hours, and 72 hours, the test piece was removed and the 90° peel strength was measured at a pulling speed of 20 mm / min using an autograph "AG-X plus" manufactured by Shimadzu Corporation. The evaluation was performed using a water-soluble multifunctional epoxy resin "Denacol EX-521" (epoxy equivalent: 183 g / equivalent) manufactured by Nagase Chemtec Corporation as the above C component. For the system containing component C, the peel strength after being left at 25°C for 72 hours was used to assign an evaluation index as follows: 5N / inch or more 〇 3N / inch or more and less than 5N / inch...△ Less than 3N / inch...×

[0048] The abbreviations of the compounds shown in the tables in the following examples respectively represent the following compounds. T: Terephthalic acid I: Isophthalic acid O: Orthophthalic acid TMA: Trimellitic acid DEG: Diethylene glycol EG: Ethylene glycol 1,5-PD: 1,5-pentanediol 2MG: 2-methyl-1,3-propylene glycol NPG: Neopentyl glycol CHDM: 1,4-cyclohexanedimethanol (1,4-bis(hydroxymethyl)cyclohexane) TMP: Trimethylolpropane GL: Glycerin DMAE: Dimethylaminoethanol Denacol EX-521: Water-soluble multifunctional epoxy resin manufactured by Nagase ChemteX Corporation GPC measurement number average molecular weight: 1200 Epoxy equivalent: 183g / eq. Epoxy functionality: 6.55 / molecule Denacol EX-313: Water-soluble multifunctional epoxy resin manufactured by Nagase ChemteX Corporation GPC measurement number average molecular weight:<500 Epoxy equivalent: 141g / eq. Epoxy Functionality:<4 Denacol EX-421: Water-soluble multifunctional epoxy resin manufactured by Nagase ChemteX Corporation GPC measurement number average molecular weight: 600 Epoxy equivalent: 159g / eq. Epoxy functionality: 3.77 / molecule

[0049] The synthesis examples and comparative synthesis examples of the copolymer polyester resin (component A) used in the examples and comparative examples of the present invention are shown below.

[0050] Synthesis Example 1 [Synthesis of copolymer polyester resin (component A) A1)] A 2L four-neck flask equipped with a stirring rod, a thermometer, and a Liebig condenser was charged with 291 parts of dimethyl terephthalate, 41 parts of diethylene glycol, 127 parts of ethylene glycol, 16 parts of trimethylolpropane, and 0.2 parts of tetra-n-butyl titanate as a catalyst, and the transesterification reaction was carried out at 190°C to 230°C for 3 hours. After confirming that a predetermined amount of methanol had been distilled, 74 parts of orthophthalic acid was charged, and the esterification reaction was carried out at 230°C to 250°C for 2 hours, and the resulting condensed water was distilled off. Next, nitrogen gas was sealed in while maintaining the temperature at 250°C, and the mixture was stirred for 3 hours while distilling off an excess amount of glycol components, and then the reaction temperature was cooled to 190°C in 30 minutes. While keeping the reaction system under nitrogen gas atmosphere, 46 parts of trimellitic acid was charged and stirred at the same temperature for 3 hours, and the molten copolymer polyester resin A1 was taken out of the flask into a heat-resistant tray and the resin composition, number average molecular weight, acid value, and glass transition temperature were measured. The measurement results obtained were number average molecular weight: 7600, molecular weight distribution: 9.1, acid value: 980eq / ton, and glass transition temperature: 51℃, and are shown in Table 1 together with the resin composition analysis results.

[0051] Synthesis Examples 2-6, Comparative Synthesis Examples 7-12 [Synthesis of copolymer polyester resins (component A) A2 to A12)] Copolymer polyester resins A2 to A12 were synthesized in the same manner as in Synthesis Example 1, except that the addition reaction time of trimellitic acid was changed as follows. The resin composition (unit in the table is mol%), number average molecular weight, molecular weight distribution, acid value, and glass transition temperature of each resin were measured, and the results are shown in Table 1. Trimellitic acid addition reaction time: A2, A7, A8, A12...1 hour A6, A11 1.5 hours A3, A4, A5 2 hours A9, A10 2.5 hours

[0052] Example 1 [Emulsion of Copolymer Polyester Resin A1 and Evaluation of Water Dispersion] 50 parts of the copolymer polyester resin (A1) obtained in Synthesis Example 1 was mixed with 4.43 parts of dimethylaminoethanol (DMAE) as component B, and emulsified in 150 parts of deionized water according to the method of (5) above. The E-type viscosity of the obtained aqueous dispersion was 8.1 cps, the pH was 7.4, and the average particle size was 266 nm. The aqueous dispersion maintained the same state as immediately after emulsification even after storage at 25°C for 1 month, and no precipitated components were observed. The obtained aqueous dispersion was named D1, and the results are summarized in Table 2.

[0053] [Evaluation of epoxy curability of copolymer polyester resin A1, and PET film adhesion in uncured and cured systems (PET film adhesion-1, -2)] According to the above evaluation method, the epoxy curing property and PET adhesion property of the copolymer polyester resin (A1) were evaluated. The epoxy curing property was 78%, 86%, and 90% after 1 day, 3 days, and 5 days at 25°C, respectively. The PET film adhesion property was 3.5N / inch for the uncured system (PET film adhesion property-1), and 5.6N / inch, 8.2N / inch, and 8.2N / inch for the cured system (PET film adhesion property-2) at 25°C x 30 minutes, 25°C x 24 hours, and 25°C x 72 hours, respectively. The results are shown in Table 3.

[0054] Examples 2 to 6 and Comparative Examples 7 to 14 [Evaluation of Emulsification and Water Dispersion of Copolymer Polyester Resins A2 to A12] Copolymer polyester resins A2 to A12 were emulsified in the same manner as in Example 1, and the resulting aqueous dispersions were named D2 to D12, respectively. The evaluation results are shown in Table 2.

[0055] [Evaluation of epoxy curability of copolymer polyester resins A2 to A12, and PET film adhesion in uncured and cured systems (PET film adhesion-1, -2)] The epoxy curing property and PET adhesion were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0056] [Table-1]

[0057] [Table-2]

[0058] [Table-3]

[0059] Comparative Examples 7 and 8 are examples in which the copolymer polyester resin (component A) has an acid value of 700 eq / ton or more but a number average molecular weight of less than 5000. An aqueous dispersion can be easily formed by adding a basic neutralizer (component B) without the need for an organic solvent or emulsifier. However, even when a water-soluble multifunctional epoxy resin (component C) is added, the curing reaction does not proceed sufficiently at room temperature (25°C), and PET adhesiveness is not expressed. Comparative Example 9 is an example in which the copolymer polyester resin (component A) has a number average molecular weight of 5000 or more but an acid value of less than 700. Although the acid value is insufficient, the diethylene glycol copolymer component of the copolymer polyester resin (component A) is used, and the acid value is less than 700. Although it can be dispersed in water by the effect of diethylene glycol (DEG), the water dispersion produced generates sediment during storage, and the storage stability is poor. Comparative Examples 10 and 11 are examples in which the number average molecular weight of component A is 5000 or more, but the acid value is less than 700, and diethylene glycol (DEG) is not copolymerized with component A, so that it is not easy to form a water dispersion under conditions without organic solvents or emulsifiers. Comparative Example 12 is an example in which the acid value of component A is less than 700 eq / ton, and the number average molecular weight is also less than 5000. It can be easily made into a water dispersion, but sediment generates immediately after dispersion, and the storage stability is poor. In addition, since both the number average molecular weight and the acid value are low, the curing reactivity with component C is extremely poor, and PET adhesiveness is not expressed. Comparative Examples 13 and 14 are examples in which the average number of epoxy functional groups per molecule of the water-soluble multifunctional epoxy resin used is less than 4, and the copolymer polyester resin (component A) used is the A(2) used in Example 2, but these examples do not provide sufficient curing properties and do not exhibit sufficient PET adhesive strength. [Industrial Applicability]

[0060] The copolymer polyester resin (component A) of the present invention has an appropriate molecular weight and acid value, so it can be easily dispersed in water without the need for organic solvents or emulsifiers, and undergoes a curing reaction with a water-soluble multifunctional epoxy resin having a specific structure at room temperature without a catalyst. It can be used as a primer for painting, printing, adhesion, and coating, as well as a paint, ink, coating agent, and adhesive, making it an environmentally friendly material.

Claims

1. A water-based curable polyester resin composition containing components A, B and C below. Component A) A copolymer polyester resin that satisfies the following (1) to (4): (1) Acid value is 700 eq / ton or more (2) Number average molecular weight exceeds 5,000 (3) The polycarboxylic acid component is composed of an aromatic polycarboxylic acid component. (4) The polyol component contains a linear glycol compound. B component) Basic neutralizing agent Component C) A water-soluble multifunctional epoxy resin having an average epoxy functional group number of 4 or more per molecule.

2. 2. The waterborne curable polyester resin composition according to claim 1, wherein the composition contains a linear glycol compound in an amount of 70 mol % or more when the total amount of the polyol components in the component A is taken as 100 mol %.

3. 3. The waterborne curable polyester resin composition according to claim 1, wherein the linear glycol compound comprises an alkylene glycol and an ether glycol.

4. 3. The waterborne curable polyester resin composition according to claim 1, wherein the composition contains an ether glycol in an amount of from 5 mol % to 40 mol % based on the total amount of the polyol components in the component A being 100 mol %.

5. The aqueous curable polyester resin composition according to claim 3, wherein the ether glycol is diethylene glycol.

6. A two-component curing adhesive comprising the waterborne curable polyester resin composition according to claim 1 or 2.

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