JP2005194494A - Method for producing aqueous polyester resin composition, thermosetting water-borne coating composition obtained by using aqueous polyester resin composition and coating material obtained by using thermosetting water-borne coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an aqueous polymer molecule polyester resin dispersion having an excellent storage stability. <P>SOLUTION: The method for producing the aqueous polyester resin composition obtained by neutralizing with a basic compound at least a part of carboxy group of a carboxy group-containing polyester resin (C) obtained by reacting a carboxylic acid anhydride group-containing compound (B) with a hydroxy group of a hydroxy group-containing polyester resin (A) and then dispersing or dissolving it in the water, wherein the hydroxy group-containing polyester resin (A) comprises two polyester resins having a specific molecular weight and a hydroxy value, and the carboxylic acid anhydride group-containing compound (B) is a compound having two or more carboxylic acid anhydride groups per molecule in at least 25 mol%, and further the carboxy group-containing polyester resin (C) has an acid value of 10 to 50mgKOH/g. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing an aqueous polyester resin composition having excellent storage stability, and a thermosetting aqueous solution containing the aqueous polyester resin composition obtained by using the method for producing an aqueous polyester resin composition. The present invention relates to a coating composition, and relates to a coated article obtained using the thermosetting water-based coating composition.

  In recent years, switching from solvent-based paints to water-based paints has been promoted in consideration of environmental pollution. As water-based paints for cans, particularly for cans or can lids, various proposals have been made to use epoxy resins as binders because of their excellent properties. Among them, there is a composition in which an epoxy resin is modified with a high acid value acrylic resin, an excess carboxyl group is neutralized with ammonia or amine, and this is dispersed in water. For example, using a radical generating catalyst such as benzoyl peroxide, graft polymerization of an acrylic monomer containing a carboxyl group-containing monomer to the main chain of the epoxy resin, and dispersing in water using a basic compound such as ammonia or amine It is disclosed (see Patent Document 1 etc.).

  However, epoxy resins are hard and cannot be applied to those that require strict processing. Instead, various water-based resin compositions in which a high acid value polyester resin is neutralized with a base such as amine and dispersed or dissolved are proposed. Has been.

  In general, the higher the polymer, the better the workability of the polyester resin. Therefore, a high-molecular polyester resin having a number average molecular weight of 10,000 or more is used in solvent-based paints. However, since the high-molecular polyester resin is linear and has a hydroxyl group or a carboxyl group only at its end, even if the carboxyl group is increased by adding a carboxylic acid anhydride to the hydroxyl group, a sufficient amount necessary for water dispersion is sufficient. It was difficult to introduce the carboxyl group of the resin, and it was difficult to use it in water-based paints.

  In order to solve the above problem, a method of using a carboxylic acid polyanhydride as at least a part of the carboxylic acid anhydride is disclosed (for example, see Patent Document 2).

  In this method, a plurality of polyester resins are bonded through a carboxylic acid polyanhydride, and at that time, a plurality of carboxyl groups are generated at the bonding portion. For this reason, it is advantageous to introduce a large number of carboxyl groups, but if the molecular weight of the polyester resin before bonding is high, the tendency to gel during synthesis is strong, and the amount of carboxylic acid polyanhydride is kept low, The molecular weight of the polyester resin before bonding is lowered, and there is a problem that a sufficient amount of carboxyl groups necessary for water dispersion cannot be introduced or the processability is lowered.

Japanese Patent Laid-Open No. 53-1228 JP 2003-89746 A

  An object of the present invention is to provide a method for producing an aqueous polyester resin composition having excellent storage stability.

  As a result of intensive studies to solve the above problems, the present inventors have found that a high molecular weight polyester resin contains two or more polyester resins in a molecule that have a molecular weight lower than that of the high molecular weight polyester resin and sufficiently contain hydroxyl groups. The present invention was completed by finding that an aqueous polyester resin composition excellent in storage stability can be obtained without reducing the processability of a high molecular weight polyester resin by bonding via a compound having a carboxylic acid anhydride group. It came to do.

  Thus, in the present invention, at least a part of the carboxyl groups of the carboxyl group-containing polyester resin (C) obtained by reacting the hydroxyl group of the hydroxyl group-containing polyester resin (A) with the carboxylic acid anhydride group-containing compound (B) is a basic compound. In the method for producing an aqueous polyester resin composition which is neutralized and dispersed or dissolved in water, the hydroxyl group-containing polyester resin (A) has a number average molecular weight of 3,000 to 7,000 and a hydroxyl value of 15 to 50 mgKOH / g. A polyester resin (a) of 50 to 95% by weight, and a high molecular weight polyester resin (b) having a number average molecular weight of 8,000 to 50,000 and a hydroxyl value of 1 to 10 mgKOH / g, At least 25 mol% of the carboxylic acid anhydride group-containing compound (B) contains two or more carboxylic acid anhydrides in one molecule. Further, the present invention relates to a method for producing an aqueous polyester resin composition excellent in storage stability, wherein the carboxyl group-containing polyester resin (C) has an acid value of 10 to 50 mgKOH / g. .

  The present invention also relates to a thermosetting aqueous coating composition comprising 1 to 50 parts by weight of a crosslinking agent (D) based on 100 parts by weight of resin solids of an aqueous polyester resin composition obtained using the above production method. Related to things.

  Furthermore, this invention relates to the coated article obtained by apply | coating the said thermosetting water-based coating composition on a metal raw material, and baking.

  By using the method for producing an aqueous polyester resin composition of the present invention, an aqueous polyester resin composition having excellent performance such as curability and storage stability can be produced. It is useful as a thermosetting water-based coating composition for coating inner and outer surfaces such as metal closures and metal caps, particularly the inner surface of cans and the inner surface of can lids.

  The present invention relates to a method for producing an aqueous polyester resin composition having excellent storage stability. The aqueous polyester resin composition contains a carboxylic acid anhydride group-containing compound (B) on the hydroxyl group of the hydroxyl group-containing polyester resin (A). ) Is reacted with at least part of the carboxyl groups of the carboxyl group-containing polyester resin (C) with a basic compound and dispersed or dissolved in water.

Hydroxyl-containing polyester resin (A)
The hydroxyl group-containing polyester resin (A) used in the present invention has a number average molecular weight of 3,000 to 7,000, preferably 4 from the viewpoint of processability of the resin and reactivity with the carboxylic anhydride group-containing compound (B). Polyester resin (a) having a hydroxyl value of 15 to 50 mg KOH / g, preferably 20 to 40 mg KOH / g, and a number average molecular weight of 8,000 to 50,000, preferably 9,000 to 30,000. And a high molecular weight polyester resin (b) having a hydroxyl value of 1 to 10 mg KOH / g, preferably 2 to 8 mg KOH / g, based on the total amount of the polyester resin (a) and the high molecular weight polyester resin (b). The polyester resin (a) is 50 to 95% by weight, preferably 60 to 90% by weight, and the high molecular weight polyester resin (b) is 5 to 5%. Wt%, it has suitable are those preferably comprising 10 to 40 wt%.

  In addition, the number average molecular weight in this invention is the value measured by gel permeation chromatography (GPC) (polystyrene conversion).

  The polyester resin (a) is an esterified product of a polybasic acid component and a polyhydric alcohol component.

  The polybasic acid component is, for example, selected from phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, hexahydroisophthalic acid, hexahydroterephthalic acid, succinic acid, adipic acid, sebacic acid, etc. One or more dibasic acids are mainly used, and monobasic acids such as benzoic acid, crotonic acid, and pt-butylbenzoic acid as necessary; trimellitic anhydride, methylcyclohexeric tricarboxylic acid, pyromellitic anhydride A tribasic or higher polybasic acid such as is used in combination. These polybasic acid components can be used alone or in admixture of two or more.

  Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, Dihydric alcohols such as 3-methylpentanediol, 1,4-hexanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol are mainly used, and glycerin, trimethylolethane, A trihydric or higher polyhydric alcohol such as methylolpropane and pentaerythritol can be used in combination. These polyhydric alcohols can be used alone or in admixture of two or more.

  The esterification reaction of both components can be performed by a known method. In the esterification reaction, it can also be obtained by performing a transesterification reaction using a lower alkyl ester of a polybasic acid (eg, methyl ester, ethyl ester, etc.) instead of the polybasic acid. The transesterification reaction of both components can be performed by a known method.

  The high molecular weight polyester resin (b) can be obtained by the same raw materials and production methods as described in the polyester resin (a), but the ratio of aromatic dicarboxylic acid in the polybasic acid component is particularly high. Is 50 to 100 mol%, and the proportion of terephthalic acid in the aromatic dicarboxylic acid is 20 to 100 mol%. Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, and 1,2-propylene. Use of dihydric alcohols such as glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, and 1,4-butanediol is preferred from the viewpoint of increasing the molecular weight of the resin and the hardness of the coating film. .

Carboxylic anhydride group-containing compound (B)
The carboxylic acid anhydride group-containing compound (B) to be reacted with the hydroxyl group of the hydroxyl group-containing polyester resin (A) contains at least one carboxylic acid anhydride group in the compound and contains a carboxylic acid anhydride group. In order to stably disperse in water the polyester resin obtained that at least 25 mol%, particularly 28 mol% or more of the compound is a compound (c) having two or more carboxylic anhydride groups in one molecule. Is preferred.

  Examples of the compound having one carboxylic anhydride group in one molecule include phthalic anhydride, succinic anhydride, maleic anhydride, itaconic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, etc. Can be mentioned.

  Examples of the compound (c) having two or more carboxylic anhydride groups in one molecule include pyromellitic anhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3, Examples thereof include 4-pentanetetracarboxylic dianhydride, ethylene glycol bistrimellitate dianhydride, 2,2 ′, 3,3′-diphenyltetracarboxylic dianhydride, and the like, among which ethylene glycol bistrimellitate It is preferable for stably dispersing the polyester resin from which dianhydride is obtained in water.

Carboxyl group-containing polyester resin (C)
A carboxyl group-containing polyester resin (C) can be obtained by reacting the hydroxyl group of the hydroxyl group-containing polyester resin (A) with a carboxylic acid anhydride group-containing compound (B). The reaction temperature is about 100 to 150 ° C., the polyester resin (a), the high molecular weight polyester resin (b), a compound having one carboxylic anhydride group in one molecule, and two or more carboxylic acids in one molecule. The addition order of the compound having an acid anhydride group can be appropriately selected in consideration of the production stability during synthesis and the water dispersibility of the resin after production. In addition, when the hydroxyl group-containing polyester resin (A) is dissolved, an organic solvent that does not contain a hydroxyl group may be added to assist dissolution.

  When the carboxylic acid anhydride group of the carboxylic acid anhydride group-containing compound (B) reacts with the hydroxyl group of the hydroxyl group-containing polyester resin (A), the carboxylic acid anhydride group opens to generate a carboxyl group. The addition amount of the carboxylic acid anhydride group-containing compound (B) is adjusted so that the resulting carboxyl group-containing polyester resin (C) has an acid value in the range of 10 to 50 mgKOH / g, particularly 15 to 40 mgKOH / g. It is suitable from the viewpoint of production stability of the aqueous polyester resin composition.

  A stable aqueous polyester resin composition can be obtained by neutralizing part or all of the carboxyl groups of the carboxyl group-containing polyester resin (C) obtained above with a basic compound and dispersing or dissolving in water. .

  As the basic compound used for neutralization, amines and ammonia are preferably used. Representative examples of the amines include, for example, triethylamine, triethanolamine, dimethylethanolamine, diethylethanolamine, morpholine, etc. Among them, triethylamine and dimethylethanolamine are particularly preferable.

Thermosetting aqueous coating composition A thermosetting aqueous coating composition can be obtained by adding a crosslinking agent (D) to the aqueous polyester resin composition obtained by the production method of the present invention.

  Examples of the crosslinking agent (D) include a resol type phenol resin, an amino resin, and an epoxy resin. When used as a paint for the inner surface of a can or can lid, a resol type phenol resin is particularly preferable.

  When a resol type phenol resin or amino resin is used as the crosslinking agent, the carboxyl group-containing polyester resin (C) preferably contains a hydroxyl group. The amount of the hydroxyl group is preferably 2 to 40 mg KOH / g, particularly about 3 to 25 mg KOH / g in terms of crosslinkability.

  The above-mentioned resol type phenol resin cross-linking agent is obtained by heating and condensing phenols and formaldehydes in the presence of a reaction catalyst to introduce a methylol group. The introduced methylol group is alkyl etherified. It may be.

  Examples of the phenol component constituting the phenol resin include o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, 2,5-xylenol, and p-tert-aminophenol. , Bifunctional phenols such as p-nonylphenol and p-cyclohexylphenol, trifunctional phenols such as coalic acid, m-cresol, m-ethylphenol, 3,5-xylenol, m-methoxyphenol, 2,4- Examples thereof include monofunctional phenols such as xylenol and 2,6-xylenol, and tetrafunctional phenols such as bisphenol B and bisphenol F, or a combination of two or more. Here, it is desirable not to use a bisphenol A type phenol resin because bisphenol A may be eluted. These may be used alone or in combination of two or more.

  Examples of formaldehydes used in the production of the phenol resin crosslinking agent include formaldehyde, paraformaldehyde, trioxane, and the like, and they can be used alone or in combination of two or more.

  The content of the crosslinking agent (D) in the thermosetting aqueous coating composition is 1 to 50 parts by weight of the crosslinking agent (D) based on 100 parts by weight of the resin solid content of the aqueous polyester resin composition. The content of about 3 to 20 parts by weight is preferable from the viewpoint of crosslinkability.

  Conventionally known coating additives such as a reaction catalyst, a repellent agent, a surfactant, an antifoaming agent, a leveling agent, and a lubricant can be added to the thermosetting aqueous coating composition as necessary. .

  The use of the thermosetting water-based coating composition of the present invention is not particularly limited, and is used for automobiles; for general industrial use; for metal cans, metal can lids, metal closures, metal caps, and the like. However, it can be particularly suitably used as a coating composition for inner surfaces of metal cans, metal can lids, metal closures, metal caps and the like.

  As a covering material, for example, a metal plate such as an aluminum plate or a steel plate, a plated steel plate in which zinc, chromium, tin, aluminum or the like is plated on the surface of the steel plate, the surface of these steel plates is chromic acid, iron phosphate, It can be applied to various metal materials such as treated steel sheets that are chemically treated with zinc phosphate or the like. As a means for applying the composition to the surface of the metal material, any known method such as roll coating, spray coating, brush coating, spray coating, immersion electrodeposition, etc. can be used. The coating film thickness is usually in the range of about 2 to 30 μm as a cured coating film, and the baking of the coating film is generally about 150 ° C. to about 280 ° C., preferably about 180 ° C. to about 220 ° C. It is performed for ˜600 seconds, preferably about 30 to 300 seconds.

  In the case of can applications, the metal material may be coated after being processed into a can shape or a can lid shape, or may be processed into a can shape or a can lid shape after being previously coated on a flat plate.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Hereinafter, both “parts” and “%” are based on weight.

Synthetic synthesis example 1 of polyester resin
In a glass four-necked flask equipped with a thermometer, stirrer, condenser and water separator, 126.3 parts of ethylene glycol, 133.3 parts of 2-methyl-1,3-propanediol, 17.0 parts of glycerin, Add 0.37 parts monobutyltin oxide and a small amount of silicon antifoaming agent and heat to 120 ° C, then add 191.2 parts cyclohexanedicarboxylic acid, 258.1 parts terephthalic acid and 153.6 parts isophthalic acid to 160 ° C. The temperature rose. Thereafter, the temperature was raised to 200 ° C. over 2 hours, maintained at that temperature for 1 hour, and then heated to 240 ° C. while removing condensed water over 2 hours. When the mixed solution became transparent, 37.5 parts of xylene was added, the reaction temperature was 220 ° C., and separation of condensed water by azeotropy was continued. Thereafter, the viscosity of the resin is measured every 1 hour, and the reaction is terminated when the viscosity of the resin diluted to 40% with cyclohequinone becomes Z ₂ by the Gardner viscosity. A polyester resin (a1) of 24 mg KOH / g was obtained.

Synthesis example 2
To a glass four-necked flask equipped with a thermometer, stirrer, condenser and water separator, add 100 parts of m-cresol, 178 parts of 37% aqueous formaldehyde solution and 1 part of sodium hydroxide, and react at 60 ° C. for 3 hours. And then dehydrated at 50 ° C. under reduced pressure for 1 hour. Subsequently, 100 parts of n-butanol and 3 parts of phosphoric acid were added and reacted at 110 to 120 ° C. for 2 hours. After completion of the reaction, the resulting solution was filtered to remove sodium phosphate, which was obtained by filtration to obtain a resol type phenol resin liquid (d1) having a solid content of about 50%. The obtained resin had a number average molecular weight of about 750 and a gelation time of 150 seconds measured at 185 ° C.

Production Example 1 of aqueous polyester resin composition
In a glass four-necked flask equipped with a thermometer, a stirrer, and a cooling tube, 193.5 parts of the polyester resin (a1) obtained in Synthesis Example 1, “UE3201” (high molecular weight polyester resin manufactured by Unitika Ltd., number average molecular weight) About 20,000, hydroxyl value 3 mg KOH / g) 46.7 parts and cyclohexanone 41.1 parts were added, and the mixture was heated to 150 ° C. and mixed with stirring. After the liquid became uniform and transparent, a carboxylic acid anhydride group-containing compound was obtained. 2.0 parts of maleic anhydride, 1.5 parts of trimellitic anhydride, 4.1 parts of ethylene glycol bistrimellitate dianhydride which is a compound having two carboxylic anhydride groups in one molecule and 10 parts % Tributylamine diluted solution (diluted with methyl ethyl ketone) was added and reacted for 2 hours to obtain a carboxyl group-containing polyester resin. The acid value of the resin was 20 mgKOH / g. To this resin, 13.7 parts of propylpropylene glycol, 27.4 parts of ethylene glycol monohexyl ether and 55.6 parts of ethylene glycol monobutyl ether were added and stirred at 100 ° C. for 40 minutes, then cooled to 50 ° C., and triethylamine 5 The aqueous polyester resin composition A-1 was obtained by adding 0.05 part and neutralizing, Furthermore, 467.5 parts of deionized water was dripped over 40 minutes, stirring.

  The amount of the compound having two or more carboxylic acid anhydride groups in one molecule in the carboxylic acid anhydride group-containing compound is 26.3 mol%.

Example 2
In a glass four-necked flask equipped with a thermometer, a stirrer, and a cooling tube, 193.5 parts of the polyester resin (a1) obtained in Synthesis Example 1, “UE3201” (high molecular weight polyester resin manufactured by Unitika Ltd., number average molecular weight) About 20,000, hydroxyl value 3 mg KOH / g) 46.7 parts and cyclohexanone 41.1 parts were added, and the mixture was heated to 150 ° C. and mixed with stirring. After the liquid became uniform and transparent, a carboxylic acid anhydride group-containing compound was obtained. Then, 2.0 parts of maleic anhydride and 1.5 parts of trimellitic anhydride were added, and 0.5 part of 10% tributylamine diluted solution (diluted with methyl ethyl ketone) was further added and reacted for 2 hours. Thereafter, 4.1 parts of ethylene glycol bistrimellitic dianhydride which is a compound having two carboxylic anhydride groups in one molecule and 0.3 part of 10% tributylamine diluted solution (diluted with methyl ethyl ketone) were further added. Reaction was performed for 2 hours to obtain a carboxyl group-containing polyester resin. The acid value of the resin was 20 mgKOH / g. To this resin, 13.7 parts of propylpropylene glycol, 27.4 parts of ethylene glycol monohexyl ether and 55.6 parts of ethylene glycol monobutyl ether were added and stirred at 100 ° C. for 40 minutes, then cooled to 50 ° C., and triethylamine 5 0.0 part was added, and it neutralized, Furthermore, 467.5 parts of deionized water was dripped over 40 minutes, stirring, and aqueous polyester resin composition A-2 was obtained.

  The amount of the compound having two or more carboxylic acid anhydride groups in one molecule in the carboxylic acid anhydride group-containing compound is 26.3 mol%.

Example 3
Add 193.5 parts of the polyester resin (a1) obtained in Synthesis Example 1 and 35 parts of cyclohexanone to a glass four-necked flask equipped with a thermometer, a stirrer, and a cooling tube, and raise the temperature to 150 ° C. with stirring and mixing. After the liquid became uniform and transparent, 2.0 parts of maleic anhydride and 1.5 parts of trimellitic anhydride, which are carboxylic anhydride group-containing compounds, were added, and 10% tributylamine diluted solution (diluted with methyl ethyl ketone) 0 .5 parts was added and reacted for 2 hours. Then, after adding 46.7 parts of "UE3201" (Unitika high molecular weight polyester resin, number average molecular weight of about 20,000, hydroxyl value of 3 mgKOH / g) and 6.1 parts of cyclohexanone, the mixture was dissolved over 1 hour. Add 4.1 parts of ethylene glycol bis trimellitate dianhydride which is a compound having two carboxylic acid anhydride groups and 0.3 part of 10% tributylamine diluted solution (diluted with methyl ethyl ketone), and further react for 2 hours. Thus, a carboxyl group-containing polyester resin was obtained. The acid value of the resin was 20 mgKOH / g. To this resin, 13.7 parts of propylpropylene glycol, 27.4 parts of ethylene glycol monohexyl ether and 55.6 parts of ethylene glycol monobutyl ether were added and stirred at 100 ° C. for 40 minutes, then cooled to 50 ° C., and triethylamine 5 The aqueous polyester resin composition A-3 was obtained by adding 0.05 part and neutralizing, Furthermore, 467.5 parts of deionized water was dripped over 40 minutes, stirring.

  The amount of the compound having two or more carboxylic acid anhydride groups in one molecule in the carboxylic acid anhydride group-containing compound is 26.3 mol%.

Example 4
In Example 1, the amount of ethylene glycol bistrimellitic dianhydride was changed from 4.1 parts to 6.2 parts, and the amount of trimellitic anhydride was changed from 1.5 parts to 0.8 parts. In the same manner as in No. 1, aqueous polyester resin composition A-4 was obtained.

  The acid value of the carboxyl group-containing polyester resin obtained during the production is 20 mgKOH / g, and the amount of the compound having two or more carboxylic anhydride groups in one molecule in the carboxylic anhydride group-containing compound is 38. 1 mol%.

Example 5
In Example 2, the amount of the polyester resin (a1) was changed from 193.5 parts to 180.2 parts, and the amount of the high molecular weight polyester resin “UE3201” was changed from 46.7 parts to 60 parts. In the same manner as in Example 1, an aqueous polyester resin composition A-5 was obtained.

  The acid value of the carboxyl group-containing polyester resin obtained during the production is 20 mgKOH / g, and the amount of the compound having two or more carboxylic anhydride groups in one molecule in the carboxylic anhydride group-containing compound is 26. 3 mol%.

Example 6
Example 3 is the same as Example 3 except that the amount of the polyester resin (a1) is changed from 193.5 parts to 160 parts and the amount of the high molecular weight polyester resin “UE3201” is changed from 46.7 parts to 80 parts. The aqueous polyester resin composition A-6 was obtained.

  The acid value of the carboxyl group-containing polyester resin obtained during the production is 22 mgKOH / g, and the amount of the compound having two or more carboxylic anhydride groups in one molecule in the carboxylic anhydride group-containing compound is 26. 3 mol%.

Example 7
In Example 3, manufacture was carried out in the same manner as in Example 3 except that the amount of ethylene glycol bistrimellitate dianhydride was changed from 4.1 parts to 16.0 parts, and an aqueous polyester resin composition A-7 was prepared. Obtained.

  The acid value of the carboxyl group-containing polyester resin obtained during the production is 28 mgKOH / g, and the amount of the compound having two or more carboxylic anhydride groups in one molecule in the carboxylic anhydride group-containing compound is 58. 3 mol%.

Example 8
In Example 2, it manufactured like Example 2 except having changed the quantity of trimellitic anhydride from 1.5 parts to 0.8 parts, and obtained water-based polyester resin composition A-8.

  The acid value of the carboxyl group-containing polyester resin obtained during the production is 16 mg KOH / g, and the amount of the compound having two or more carboxylic anhydride groups in one molecule in the carboxylic anhydride group-containing compound is 29. 0 mol%.

Example 9
In Example 3, high molecular weight polyester resin “UE3201” was changed to “UE3200” (high molecular weight polyester resin manufactured by Unitika Ltd., number average molecular weight of about 16,000, hydroxyl value 6 mgKOH / g). The aqueous polyester resin composition A-9 was obtained.

  The acid value of the carboxyl group-containing polyester resin obtained during the production is 20 mgKOH / g, and the amount of the compound having two or more carboxylic anhydride groups in one molecule in the carboxylic anhydride group-containing compound is 26. 3 mol%.

Comparative Example 1
Example 1 Example 1 except that the amount of ethylene glycol bistrimellitic dianhydride is changed from 4.1 parts to 0.4 parts and the amount of trimellitic anhydride is changed from 1.5 parts to 3.2 parts. 1 was produced in the same manner as in Example 1 to obtain an aqueous polyester resin composition B-1.

  The acid value of the carboxyl group-containing polyester resin obtained during the production is 20 mgKOH / g, and the amount of the compound having two or more carboxylic anhydride groups in one molecule in the carboxylic anhydride group-containing compound is 3. 3 mol%.

Comparative Example 2
Example 3 Example 3 is the same as Example 3 except that the amount of the polyester resin (a1) is changed from 193.5 parts to 80 parts and the amount of the high molecular weight polyester resin “UE3201” is changed from 46.7 parts to 160 parts. The aqueous polyester resin composition B-2 was obtained.

  The acid value of the carboxyl group-containing polyester resin obtained during the production is 15 mg KOH / g, and the amount of the compound having two or more carboxylic anhydride groups in one molecule in the carboxylic anhydride group-containing compound is 26. 3 mol%.

Comparative Example 3
In Example 1, the amount of trimellitic anhydride is 1.5 to 0 parts, the amount of maleic anhydride is 2.0 to 0 parts, and the amount of ethylene glycol bistrimellitate dianhydride is 4.1 parts. Manufacture was carried out in the same manner as in Example 1 except that the content was changed to 0.4 part, and an aqueous polyester resin composition B-3 was obtained.

  The acid value of the carboxyl group-containing polyester resin obtained during the production is 8 mgKOH / g, and the amount of the compound having two or more carboxylic anhydride groups in one molecule in the carboxylic anhydride group-containing compound is 100 mol. %.

Properties of Aqueous Polyester Resin Composition Each aqueous polyester resin composition obtained in the above Examples and Comparative Examples was tested for initial dispersion state and storage property. The test method was performed according to the following, and the results obtained are shown in Table 1 below.

Initial dispersion state: The state of the aqueous liquid immediately after production of the aqueous polyester resin composition was visually evaluated according to the following criteria.
○: No abnormality such as separation and sedimentation.
Δ: Some separation but no sedimentation.
X: Separation and sedimentation are observed.

Storage property: After the aqueous polyester resin composition was stored in a constant temperature room at 40 ° C. for 30 days, the state of the liquid was visually evaluated according to the following criteria.
○: No abnormality such as separation and sedimentation.
Δ: Some separation but no sedimentation.
X: Separation and sedimentation are observed.

Production Examples 8 to 15 and Comparative Examples 4 to 7 for thermosetting water-based coating compositions
The resol type phenol resin (d1) was blended in solid content according to the blending composition shown in Table 2 below with respect to 100 parts of solid content of each aqueous polyester resin composition obtained in the above Examples and Comparative Examples. The coating was produced by mixing and stirring the carboxyl group-containing polyester resin and the resol type phenol resin before neutralization at the time when the carboxyl group-containing polyester resin was obtained, and then neutralizing the resin and dispersing in water. .

Preparation of test coating plate and performance test plate Each thermosetting water-based paint composition prepared in the above examples and comparative examples was applied to an aluminum material having a thickness of 0.26 mm with a bar coater so that the cured film thickness was 5 μm. Then, it was dried by heating so that the maximum material temperature reached 260 ° C. in 15 seconds to obtain a test coated plate.

  About each obtained test coating plate, the sclerosis | hardenability of the coating film was evaluated by the following method. The obtained results are shown in Table 2 below.

Curability: A test coating plate having a known weight and coating weight was placed in a flask containing methyl ethyl ketone, and the flask was heated to reflux methyl ethyl ketone for 1 hour. After cooling, the test coated plate was taken out and dried, the weight of the coated plate was measured, the coating film residual rate was calculated from the coating film weight before and after the test by the following formula, and the curability was evaluated according to the following criteria.
Coating film residual ratio (%) = 100 × film weight after test / film weight before test ○: Coating film residual ratio is 80% or more.
(Triangle | delta): The coating-film residual ratio is 60% or more and less than 80%.
X: The coating film residual rate is less than 60%.

Claims (6)

At least part of the carboxyl groups of the carboxyl group-containing polyester resin (C) obtained by reacting the hydroxyl group of the hydroxyl group-containing polyester resin (A) with the carboxylic acid anhydride group-containing compound (B) is neutralized with a basic compound, In the method for producing an aqueous polyester resin composition dispersed or dissolved in the polyester resin (a), the hydroxyl group-containing polyester resin (A) is a polyester resin having a number average molecular weight of 3,000 to 7,000 and a hydroxyl value of 15 to 50 mgKOH / g (a ) 50 to 95% by weight, and a high molecular weight polyester resin (b) having a number average molecular weight of 8,000 to 50,000 and a hydroxyl value of 1 to 10 mg KOH / g, and the carboxylic acid anhydride. A compound in which at least 25 mol% of the group-containing compound (B) has two or more carboxylic acid anhydride groups in one molecule ( ), And further, the production method of the aqueous polyester resin composition having excellent storage stability, wherein the acid value of the carboxyl group-containing polyester resin (C) is 10 to 50 mgKOH / g. The method for producing an aqueous polyester resin composition according to claim 1, wherein the compound (c) having two or more carboxylic acid anhydride groups in one molecule is ethylene glycol bistrimellitate dianhydride. It contains 1 to 50 parts by weight of the crosslinking agent (D) based on 100 parts by weight of the resin solid content of the aqueous polyester resin composition obtained using the method for producing an aqueous polyester resin composition according to claim 1 or 2. A thermosetting aqueous coating composition. The thermosetting water-based coating composition according to claim 3, wherein the crosslinking agent (D) is a resol type phenol resin. A coated article obtained by applying the thermosetting aqueous coating composition according to claim 3 or 4 onto a metal material and baking it. A can obtained by applying the thermosetting aqueous coating composition according to claim 3 or 4 onto a metal material and baking it.