JPH06293865A - Water-based coating composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition, excellent in lubricity of films, processability, film surface appearance, film performance and coating stability and useful as a coating for beverage cans, etc., by dissolving or dispersing a sucrose ester of a fatty acid in a water-based coating. CONSTITUTION:This coating composition is obtained by dissolving or dispersing sucrose ester of a fatty acid, preferably a compound expressed by the formula [R is H or R<1>CO {R<1> is 10-22C alkyl or alkenyl}] in a water-based coating. Furthermore, the water-based coating preferably contains a graft substance of an aromatic epoxy resin with an acrylic resin of a high acid value as a water-dispersible resin component and a phenol resin or an amino resin is preferably contained as a cross-linkable resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based coating composition in which a fatty acid sucrose ester is used as one component of a water-based coating to improve the lubricity and processability of a coating film.

[0002]

2. Description of the Related Art Conventionally, as a manufacturing process for cans (beverage cans, food cans, sanitary cans, etc.), bottle caps, etc., metal plates have been coated with paint in advance.
Next, it is often adopted that the coated metal plate is subjected to forming processing such as pressing, punching, winding and bending, to obtain a desired product. Also,
Regarding paints used in these processes, organic solvent-based paints are being changed to water-based paints containing water as a main dispersion medium in view of pollution prevention, resource saving, and improvement of safety and health.

In such a process, in order to prevent the coating film from being scratched, cracked, peeled or the like due to the molding process of the coated metal plate, a wax is blended in the above water-based coating material so that the formed coating surface has slipperiness. It is given. It is already known that mixing the wax in the paint reduces the frictional resistance of the coated surface and improves the moldability, but sufficient research has not been done on the method of mixing the wax in the water-based paint. However, various problems have been raised and their improvement is desired in the transition to water-based paints.

That is, conventionally, a wax emulsion in which a wax is dispersed in water in the form of fine particles using a surfactant or the like as an emulsifier, or a hydrophilic group (for example, a carboxyl group) is used.
It was common to use an aqueous solution or dispersion of a modified wax obtained by introducing and neutralizing the above, and mixing it in an aqueous paint.

However, in the water-based paint mixed with wax by such a method, the wax particles and the resin particles of the water-based paint exist separately and separately.
In the process of forming the coating film, the wax particles hinder the uniform fusion of the resin particles of the water-based coating material, making it difficult to form a continuous fusion coating film with the resin, and the physical performance of the coating film deteriorates. In addition, the wax particles aggregate during storage of the coating material to cause cissing and dents in the coating film, and further progress of aggregation may cause phase separation between the wax and the water-based coating material. Further, if a large amount of a surfactant is mixed in the water-based paint, the adhesion, water resistance, processability, weather resistance and the like of the coating film may be deteriorated. Further, since the emulsifier is originally water-soluble, when the paint is used for the inner surface of the can, the emulsifier in the coating film is eluted into the contents of the can, so that there is a problem in hygiene and flavor.

In addition, flexible and tough coating film properties are required for applications in which severe processing such as easy open end of cans is performed.

Vinyl chloride resin-based organosol paints have been developed as organic solvent paints satisfying the above requirements. This paint is useful as a paint that does not require repair because it has excellent adhesion to metal materials and workability, but when used as the paint on the inside of metal cans, it is an epoxidized oil component that is a plasticizer or stabilizer. However, there is a drawback that it is extracted and transferred to the contents, which is not preferable in food hygiene and changes the flavor of the contents. In addition to this, the viscosity of the paint is increased or the workability is changed due to aging, and it is extremely difficult to control the paint. In addition, it is technically difficult to make the vinyl chloride-based organosol paint aqueous.

[0008]

Therefore, the inventors of the present invention have earnestly studied in order to obtain a water-based paint which is excellent in the lubricity and processability of the paint film and has no problem in the appearance of the paint surface, paint film performance and paint stability. As a result, they have found that the desired coating material can be obtained by incorporating a fatty acid sucrose ester into the water-based coating material, and have completed the present invention.

That is, the present invention relates to "1. Water-based coating composition characterized in that a fatty acid sucrose ester is dissolved or dispersed in the water-based coating".

The present invention also relates to "2. the above aqueous coating composition wherein the fatty acid sucrose ester is a compound represented by the following general formula [1]".

[0011]

[Chemical 2]

(Wherein R is the same or different and represents a hydrogen atom or an acyl group represented by R ¹ OC-, and 8
At least one R out of R is R ¹ OC-,
R ¹ represents an alkyl group or an alkenyl group having 10 to 22 carbon atoms. )

The present invention further provides "3. Aqueous coating composition according to the above item 1 or 2, wherein the aqueous coating composition contains a graft product of an aromatic epoxy resin and a high acid value acrylic resin as a water-dispersible resin component." Regarding

The present invention also relates to "the water-based coating composition according to the above item 3, wherein the water-based coating contains a phenol resin or an amino resin as a cross-linking resin".

The water-based paint in the present invention is a thermoplastic or thermosetting paint in which a water-soluble or water-dispersible resin as a vehicle component is dissolved as it is or is neutralized and stably dispersed in an aqueous medium by neutralization. be able to.

The above water-soluble or water-dispersible resin has a hydrophilic functional group (eg, carboxyl group, sulfonic acid group,
A resin having a phosphoric acid group, a boric acid group, a hydroxyl group, an ether group, etc.) in its skeleton, which can be water-dispersed as it is or by neutralizing with a basic compound. Examples of the polyester resin, alkyd resin, acrylic resin, epoxy resin, epoxy resin and epoxy resin and a high acid value acrylic resin having the above-mentioned functional group produced by a method known per se using a compound having the above-mentioned functional group And non-neutralized resins such as polybutadiene and resins obtained by neutralizing the functional groups in these non-neutralized resins with the above compounds. These can be used alone or in combination of two or more. .

Examples of the basic compound used for neutralizing the above functional groups include alkali metal compounds, ammonia, primary, secondary and tertiary alkylamines, and aliphatic amines, alkanolamines and aliphatic cyclic amines. Can be given.

Among the above water-dispersible resins, among the epoxy resins, a graft product of an aromatic epoxy resin and a high acid value acrylic resin is particularly preferable. This graft product can be produced, for example, by the method shown below. (I) An aromatic epoxy resin and a carboxyl group-containing acrylic resin are subjected to an ester addition reaction in an organic solvent solution in the presence of a tertiary amine. (II) In an organic solvent solution, a radical polymerizable unsaturated monomer is graft-polymerized with an aromatic epoxy resin in the presence of a radical generator such as benzoyl peroxide.

As the aromatic epoxy resin, for example, epichlorohydrin and bisphenol are condensed to a high molecular weight in the presence of an alkali catalyst, and epichlorohydrin and bisphenol are condensed to a low molecular weight epoxy resin in the presence of an alkali catalyst. In addition to those obtained by polyaddition reaction of this low molecular weight epoxy resin and bisphenol, an epoxy ester resin in which a dibasic acid is combined may be used. Here, as the dibasic acid,
Formula HOOC- (CH _{2) n} -COOH (wherein n is. Represents an integer of 1 to 12) are used compounds preferably represented by, in particular, succinic acid, adipic acid, pimelic acid, azelaic Examples thereof include acid, sebacic acid, dodecanedioic acid, hexahydrophthalic acid and the like. As the bisphenol, bisphenol A and bisphenol F are preferably used, or a mixture of both may be used.

Specific examples of such epoxy resin include, for example, Epicoat 1004 (epoxy equivalent of about 900, number average molecular weight of about 1,400), Epicoat 1007 (epoxy equivalent of about 1,700, number average molecular weight of about 100,000 manufactured by Shell Chemical Co., Ltd. 2,900), Epicoat 1009 (epoxy equivalent of about 3,500, number average molecular weight about 3,750), Epicoat 1010 (epoxy equivalent of about 4,500, number average molecular weight about 5,500) and the like.

The number of epoxy groups per molecule of the epoxy resin is not particularly limited, and is appropriately selected depending on the reaction mode of the reaction for obtaining a graft product of the epoxy resin and the carboxyl group-containing acrylic resin. . That is, when the reaction form is the (I) ester addition reaction, the average number of epoxy groups per molecule of the epoxy resin is 0.5 to 2, and preferably 0.5 to 1.6. Good. Further, when the reaction form is a graft reaction of an acrylic monomer containing a carboxyl group-containing acrylic monomer by hydrogen abstraction of the epoxy resin main chain, the epoxy group may not substantially exist in the epoxy resin.

The number average molecular weight of the epoxy resin is usually 1,400 from the viewpoint of retort processability and viscosity.
To about 8,000 are preferred, and 2,900 to 7,000
More preferably, it is about the degree.

As the carboxyl group-containing acrylic resin used in the above esterification reaction, at least one of carboxyl group-containing radically polymerizable unsaturated monomers such as the following group (a), or if necessary, copolymerization therewith An acrylic resin obtained by copolymerizing a radically polymerizable unsaturated monomer such as possible group (b) can be exemplified.

(A) α, β-ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid and the like.

(B) Acrylic acid or methacrylic acid such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate and the like having a hydroxyalkyl ester having 1 to 8 carbon atoms; methyl acrylate, Methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2
-Ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, decyl acrylate, etc. Acrylic acid or methacrylic acid having 1 to 24 carbon atoms alkyl or cycloalkyl ester; acrylamide; Methacrylamide, N-methyl acrylamide, N-ethyl methacrylamide, diacetone acrylamide, N-methylol acrylamide, N-
Acrylic or methacrylamide such as methylol methacrylamide, N-methoxymethyl acrylamide, N-butoxymethyl acrylamide, etc. or derivatives thereof; aromatic vinyl monomers such as styrene, vinyltoluene, α-methylstyrene; vinyl propionate, acetic acid Vinyl monomers such as vinyl, acrylonitrile, methacrylonitrile, vinyl propionate, vinyl pivalate and Veova monomer (manufactured by Shell Chemical Co.).

Examples of preferable combinations of the above unsaturated monomers include (a) methyl methacrylate / 2-ethylhexyl acrylate / acrylic acid, (b) styrene / methyl methacrylate / ethyl acrylate / methacrylic acid. , (C) styrene / ethyl acrylate / methacrylic acid, (d) methyl methacrylate / ethyl acrylate / acrylic acid and the like.

The carboxyl group-containing acrylic resin can be easily prepared, for example, by a solution polymerization method using the above-mentioned unsaturated monomer in the presence of an initiator for radical polymerization. The number average molecular weight of the carboxyl group-containing acrylic resin is usually about 5,000 to 100,000,
Moreover, the acid value is preferably in the range of about 50 to 500 in terms of resin solid content.

In the above (I) ester addition reaction, the solid content concentration of the aromatic epoxy resin and the carboxyl group-containing acrylic resin used is not particularly limited.
It is desirable that the range is such that the optimum viscosity of these resins is obtained. Further, the tertiary amine is preferably used in the range of usually 0.1 to 1 equivalent with respect to the epoxy group of the aromatic epoxy resin.

The above-mentioned ester addition reaction can be carried out by a conventionally known method. For example, an organic solvent solution of an aromatic epoxy resin and an organic solvent solution of a carboxyl group-containing acrylic resin are uniformly mixed and then The reaction is preferably carried out in the presence of an aqueous solution of a tertiary amine at a reaction temperature of usually 60 to 130 ° C. for about 1 to 6 hours until the epoxy groups are substantially consumed.

The radically polymerizable unsaturated monomer used when the grafted product of the epoxy resin and the high acid value acrylic resin is obtained by the above-mentioned (II) graft polymerization reaction is used in the above (I) ester addition reaction. The same monomers as the radically polymerizable unsaturated monomers of the groups (a) and (b) used for producing the carboxyl group-containing acrylic resin can be mentioned.

In the above graft polymerization reaction, the ratio of the aromatic epoxy resin and the radically polymerizable unsaturated monomer used is not particularly limited, but usually the former: the latter = 9.
5 to 70% by weight: 5 to 30% by weight is preferable. In this case, the carboxyl group-containing radically polymerizable unsaturated monomer is preferably used in an amount of 20 to 80% by weight based on the total radically polymerizable monomers. Further, the radical generator is preferably used in an amount of usually 3 to 15% by weight based on the radically polymerizable unsaturated monomer.

The above-mentioned graft polymerization reaction can be carried out by a conventionally known method, for example, a radical polymerization property obtained by uniformly mixing a radical generator with an organic solvent solution of an aromatic epoxy resin heated at 80 to 150 ° C. It can be carried out by adding the unsaturated monomer for 1 to 3 hours and maintaining the same temperature for 1 to 3 hours.

The organic solvent used in the above (I) ester addition reaction and (II) graft polymerization reaction is
With an organic solvent that dissolves an aromatic epoxy resin and a carboxyl group-containing acrylic resin and that is compatible with water that does not interfere with the formation of an emulsion when the carboxylate of the reaction product of these resins is diluted with water. As far as there is a certain one, any conventionally known one can be used.

Representative examples of the above organic solvent include isopropanol, butyl alcohol, 2-hydroxy-4-methylpentane, 2-ethylhexyl alcohol, cyclohexanol, ethylene glycol, diethylene glycol, 1,3-butylene glycol, ethylene glycol monoethyl. Examples thereof include alcohols such as ether, ethylene glycol monobutyl ether, and diethylene glycol monomethyl ether, cellosolve solvents, and carbitol solvents. It is also possible to use an inert organic solvent which is immiscible with water, and examples of such an organic solvent include aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, and ketones such as acetone and methyl ethyl ketone. And the like.

The grafted product of the aromatic epoxy resin and the high acid value acrylic resin can be made into a water-dispersible resin by neutralizing at least a part of the carboxyl groups in the resin with a basic compound. As the basic compound used for neutralizing the carboxyl group, conventionally known compounds can be widely used as long as they are generally used for neutralizing the carboxyl group. For example, any primary amine, secondary amine, Examples include tertiary amines and quaternary ammonium salts. More specifically, methylamine, ethylamine, n-propylamine, isopropylamine, n-hexylamine, monoethanolamine, propanolamine, benzylamine, dimethylamine, dibutylamine, dihexylamine, methylethanolamine, diethanolamine, triethylamine. , Diethylethanolamine, dimethylcyclohexylamine, triethanolamine, tributylamine, dimethyl n-butylamine, tripropylamine, γ-picoline, tetrahexyl ammonium hydroxide and the like. The amount of such a neutralizing agent to be used is usually a neutralizing equivalent of 0.1 to 2 with respect to the carboxyl group in the reaction product. The neutralization treatment with the neutralizing agent can also be performed by a conventionally known method.

In the water-based coating composition of the present invention, when the water-dispersible resin has a crosslinkable functional group such as a hydroxyl group, a crosslinking agent reactive with the crosslinkable functional group is added to improve curability. can do. For example, when the water-dispersible resin is a graft product of the aromatic epoxy resin and the high acid value acrylic resin, a hydroxyl group, a carboxyl group or the like is present as a crosslinkable functional group, and a phenol resin or an amino group is used as the crosslinking agent. A resin or the like can be blended.

Examples of the phenol resin include a resol type phenol resin prepared by subjecting a phenol such as phenol or bisphenol A and a formaldehyde to a condensation reaction in the presence of a reaction catalyst to introduce a methylol group. Examples of the amino resin include a methylolated amino resin obtained by reacting an amino component such as melamine, urea, benzoguanamine, spiroguanamine and dicyandiamide with an aldehyde. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like. Further, a part of the methylol group of this methylolated amino resin is replaced with methyl alcohol, ethyl alcohol, n-butyl alcohol,
An etherified product having an alcohol having 1 to 8 carbon atoms such as isobutyl alcohol can also be used. These crosslinked resins are usually used in an amount of 1
It is preferably used in the range of -40 parts by weight, more preferably 5-30 parts by weight.

In the composition of the present invention, a fatty acid sucrose ester is dissolved or dispersed in an aqueous paint containing the water-dispersible resin as a vehicle component. The fatty acid sucrose ester is at least one of the eight hydroxyl groups present in sucrose.
One is a polyester ester of a monoester, diester or triester or higher esterified with a fatty acid, or a mixture of two or more kinds of these esters.

The above fatty acid has 11 to 2 carbon atoms.
Saturated or unsaturated fatty acids of 3 are preferred, and specific examples include lauric acid, olein stage, myristic acid, palmitic acid,
Examples thereof include stearic acid and behenic acid. As the fatty acid sucrose ester, those represented by the following general formula [1] are preferable.

[0040]

[Chemical 3]

(Wherein R is the same or different and represents a hydrogen atom or an acyl group represented by R ¹ OC-, and at least one R out of 8 R is R ¹ OC-,
¹ represents an alkyl group or an alkenyl group having 10 to 22 carbon atoms. )

Commercial products of the above fatty acid sucrose ester include, for example, Ryoto Sugar Ester S-170, S-770 and S-167 manufactured by Mitsubishi Kasei Foods Co., Ltd.
0, the same O-1570, the same B-370, Daiichi Kogyo Seiyaku Co., Ltd. DK ester F-50, the same F-110, the same F-160, etc. are mentioned. Esters of fatty acids and sucrose are described in detail in "Sugar Ester Monogatari" published by Daiichi Kogyo Seiyaku Co., Ltd. (published in 1984).

[0043]

The composition of the present invention is excellent in slipperiness and processability of the resulting coating film. The reason is that the fatty acid sucrose ester exhibits slipperiness due to a fatty acid residue, for example, a long-chain hydrocarbon chain which is R ¹ in the above formula [1], and the fatty acid sucrose ester has a hydroxyl group. Since it also has good surface activity and adapts well to an aqueous medium, in the course of drying the coating film, these hydroxyl groups are functional groups in the resin that is the vehicle component, such as a carboxyl group and a functional group in the cross-linking agent, such as a methylol group. By reacting and binding, the fatty acid sucrose ester is fixed to the coating film and plasticizes the coating film, whereby a coating film having excellent processability can be obtained. Furthermore, as described above, since the fatty acid sucrose ester is fixed to the coating film, the fatty acid sucrose ester is almost eluted from the coating film even when the composition of the present invention is used as a paint for the inner surface of a can or by high temperature water treatment in a sterilization treatment step or the like. do not do.

In the composition of the present invention, the amount of the above fatty acid sucrose ester is not particularly limited, but it is usually
It is blended so as to be in the range of 0.5 to 30% by weight with respect to the coating solid content. As a method of dissolving or dispersing the fatty acid sucrose ester in the water-based paint, the fatty acid sucrose ester is directly or previously dissolved or dispersed in water, and then mixed with a coating resin aqueous liquid and, if necessary, other coating additives and stirred. Or a method in which the resin solution for paint before water-solubilization is heated to a temperature higher than the melting point of the fatty acid sucrose ester, usually 40 to 100 ° C., the fatty acid sucrose ester is melted and uniformly mixed into Examples include a method in which a solvating agent and water are gradually added, dispersed in water, and optionally mixed with other paint additives and stirred.

In the composition of the present invention, a water-dispersible resin,
In addition to the fatty acid sucrose ester and water, a pigment, a dye, a wax, an anti-agglomeration agent, a leveling agent, an antifoaming agent and the like can be appropriately added in addition to the neutralizing agent and the crosslinking agent, if necessary. The solid content concentration of the aqueous coating composition of the present invention is not particularly limited, but it is usually used in the range of 20 to 45% by weight.

The water-based coating composition of the present invention is a metal such as tin plate, aluminum, tin-free steel, iron, zinc, copper, galvanized steel plate, alloy-plated steel plate, etc., and these metals are subjected to phosphate treatment or chromate treatment. It can be applied to chemical conversion treated metal, wood, plastics, concrete, etc. The coating thickness may be appropriately selected depending on the application, but is usually 3 to 20 μm, and roll coating
It can be applied by spray coating, brush coating, roller coating, or the like. The drying conditions of the coating film may be appropriately selected depending on the type of resin used, and the resin is a graft product of an aromatic epoxy resin and a high acid value acrylic resin or a graft product of this graft product and a phenol resin or an amino resin. When it is a combination, it is usually 120 to 250 ° C.
It is baked for about 10 seconds to about 30 minutes.

When the composition of the present invention is used for cans,
Normally, tin plate so that the dry film thickness is about 3 to about 8 μm,
It is painted on metal plates such as aluminum and tin-free steel.

[0048]

EFFECTS OF THE INVENTION The aqueous coating composition of the present invention contains a fatty acid sucrose ester, and therefore has excellent lubricity and processability of the coating film, and has problems in coating surface appearance, coating performance and coating stability. Since it is a non-paint, and the coating film has excellent lubricity and processability, it is particularly useful in can applications where severe processing is required.

[0049]

EXAMPLES The present invention will be further clarified with reference to the following examples. Incidentally, in the following, simply, “part” and “%” mean “part by weight” and “% by weight”, respectively.

<Production of Acrylic Resin Solution Containing Carboxyl Group> Production Example 1 400 parts of butanol were weighed in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen inlet. Next, 174 parts of methacrylic acid, 87 parts of styrene, 29 parts of ethyl acrylate, and 14.5 parts of benzoyl peroxide (75% water-wet product) were weighed in a beaker and thoroughly mixed and stirred to prepare a preliminary mixture. The temperature of butanol in the flask was heated to 105 ° C., at which temperature the premix was added dropwise from the dropping funnel over 3 hours. The temperature was maintained for another 2 hours to complete the copolymerization reaction. Then add 290 parts of 2-butoxyethanol,
Viscosity 370 centipoise, resin acid value 390, solid content 30
% Carboxyl group-containing acrylic resin solution (hereinafter referred to as “acrylic resin solution A”) was obtained.

<Production of Epoxy Resin Solution> Production Example 2 Epicoat 828 (Epoxy resin manufactured by Yuka Shell Co., epoxy equivalent 190, viscosity about 130 poise, 25 ° C.) 50
5 parts, 286 parts of bisphenol A, 0.5 parts of tri-n-butylamine and 88 parts of methyl isobutyl ketone were placed in a reaction vessel and heated to 135 ° C. under a nitrogen stream,
The contents exothermed to 180 ° C. This product was cooled to 160 ° C and reacted for about 3 hours to give an epoxy value of 0.02.
5. Solution viscosity (Gardner-Holt viscosity of butyl carbitol solution with 40% resin content at 25 ° C) 90% of Z ₄
An epoxy resin solution (hereinafter referred to as "epoxy resin solution B") was obtained.

Production Example 3 Epicoat 807 (Epoxy resin manufactured by Yuka Shell Co., epoxy equivalent about 170, viscosity about 130 poise, 25 ° C.) 46
When 2 parts, 274 parts of bisphenol F, 0.5 part of tri-n-butylamine and 82 parts of methyl isobutyl ketone were placed in a reaction vessel and heated to 135 ° C. under a nitrogen stream,
The contents exothermed to 180 ° C. This product was cooled to 160 ° C and reacted for about 3 hours to give an epoxy value of 0.02.
4. Solution viscosity (Gardner-Holt viscosity of butyl carbitol solution with 40% resin content at 25 ° C) 90% of Z ₂
An epoxy resin solution (hereinafter referred to as "epoxy resin solution C") was obtained.

<Production of Phenol Resin Solution> Production Example 4 228 parts of bisphenol A, 122 parts of 37% aqueous formaldehyde solution and 2 parts of caustic soda were charged into a reaction kettle equipped with a stirrer and a reflux condenser, and the temperature was raised to 60 ° C. for 3 hours. It was made to react. Then, 2.45 parts of sulfuric acid was added thereto, and n-
228 parts of butanol was added, and azeotropic dehydration was performed by heating at a reduced pressure of 650 mmHg. After depressurizing to a concentration of 80%, it was diluted to 60% with n-butanol to obtain monomethylol 60.
%, 30% dimethylol compound, and a phenol resin solution having an average number of methylol groups of 1.2 per bisphenol A unit (hereinafter referred to as “phenol resin solution D”) were obtained.

Production Example 5 228 parts of bisphenol A, 216 parts of 37% aqueous formaldehyde solution and 2 parts of caustic soda were charged into a reaction kettle equipped with a stirrer and a reflux condenser, heated to 100 ° C. and reacted for 4 hours. Then, 2.45 parts of sulfuric acid was added to this, and further n
-228 parts of butanol was added, and azeotropic dehydration was performed by heating at a reduced pressure of 650 mmHg. The pressure was reduced to 80% and then diluted to 60% with n-butanol to obtain a phenol resin solution having an average number of methylol groups of 1.8 per 1 unit of bisphenol A (hereinafter referred to as "phenol resin solution E").

<Production of Aqueous Coating Composition> Example 1 Composition (1) Acrylic resin solution A 150 parts (2) Epoxy resin solution B 283 parts (3) n-Butanol 86 parts (4) 2-Butoxyethanol 47 parts (5) Deionized water 3.2 parts (6) Dimethylaminoethanol 5.3 parts (7) Dimethylaminoethanol 9.5 parts (8) Phenol resin solution D 150 parts (9) Deionized water 466 parts 1,200 parts in total Put the above (1) to (4) in a reaction vessel, and under a nitrogen stream,
The resin component was dissolved by heating to 15 ° C. After dissolution 10
Cool to 5 ℃, add in the order of (5) ~ (6), 105 ℃
Held for 3 hours. The reaction product has an acrylic resin / epoxy resin solid content weight ratio of 15/85. The reaction is
The acid value was measured and tracked, and the acid value was 51 at the reaction end point. Then (3) was added after 3 hours and (8) after 5 minutes.
Was added and hot blended at 105 ° C. for 30 minutes. Then, (9) was added over 30 minutes and dispersed in water to obtain a resin dispersion.

Separately, Ryoto Sugar Ester S-1
670 (manufactured by Mitsubishi Kasei Foods Co., Ltd., a mixture of sucrose stearate with about 75% monoester and about 25% di- or triester or higher polyester) in 90 parts of deionized water at 80 ° C The mixture was added and dissolved to obtain a fatty acid sucrose ester aqueous solution. 60 ℃ in this aqueous solution
The above resin dispersion held in was gradually added with stirring to obtain a stable aqueous coating composition having a solid content of about 30%.

Example 2 An aqueous coating composition was obtained in the same manner as in Example 1 except that the phenol resin solution E was used in the same amount instead of the phenol resin solution D. Example 3 An aqueous coating composition was obtained in the same manner as in Example 1 except that the same amount of the epoxy resin solution C was used instead of the epoxy resin solution B.

Example 4 Composition (1) Epoxy resin solution B 283 parts (2) n-butanol 121 parts (3) 2-butoxyethanol 117 parts (4) Methacrylic acid 27 parts (5) Styrene 13.5 parts ( 6) Ethyl acrylate 4.5 parts (7) Benzoyl peroxide 3 parts (8) Dimethylaminoethanol 14.8 parts (9) Phenol resin solution D 150 parts (10) Ryoto sugar ester 270 (Note 1) 78 parts (11) Deionized water 748.2 parts Total 1,560 parts

The above-mentioned (1) to (3) were placed in a reaction vessel and heated to 115 ° C. under a nitrogen stream to dissolve the resin component. Then, the mixture of (4) to (7) was added dropwise over 1 hour,
Further, the mixture was reacted at 115 ° C. for 2 hours. Then cool to 105 ° C., add (8) and after 5 minutes add (9)
Hot blended at 05 ° C for 30 minutes. After that, it was cooled to 80 ° C., and (10) was added thereto and melted. Then, while maintaining the temperature at 80 ° C., 3 (11) was added with stirring.
It was gradually added over 0 minutes to obtain a stable aqueous coating composition having a solid content of about 30%. (Note 1) Ryoto Sugar Ester 270: A sucrose stearate ester produced by Mitsubishi Kasei Foods Co., Ltd., which is a mixture of about 10% monoester and about 90% di- or triester or higher polyester.

Comparative Example 1 In Example 1, (9) Deionized water amount of 466 parts was changed to 5
A solid content of about 30% was obtained in the same manner as in Example 1 except that the amount was changed to 66 parts and the fatty acid sucrose ester aqueous solution was not added.
A water-based paint of

Comparative Example 2 In Example 4, (10) Ryoto-sugar ester 270 was not blended, and (11) Deionized water amount 74
A water-based paint having a solid content of about 30% was obtained in the same manner as in Example 2 except that 8.2 parts was changed to 566.2 parts.

Each of the water-based paints obtained in the above Examples and Comparative Examples was tested for adhesion of coating film, boiling water resistance, processability, flavor of water extract, and stability of paint over time. The test method was as follows.
The test results are shown in Table 1 below.

Test method Preparation of test coated plate: An aluminum plate having a thickness of 0.3 mm was coated with a bar coater so that the dry coating film weight was 120 mg / 100 cm ^2, and after setting at 100 ° C. for 2 minutes,
A test plate was obtained by baking in a dryer for 30 seconds at an ambient temperature of 280 ° C. and a wind speed of 25 m / min so that the maximum temperature reached by the material was 260 ° C. This test plate was subjected to tests of adhesion, slipperiness, processability, chloroform extraction amount, and boiling water resistance. A water extract flavor was prepared in the same manner as the above test plate except that 0.1 mm thick aluminum foil was used instead of the 0.3 mm thick aluminum plate and the atmosphere temperature of the dryer was 275 ° C. A test plate was obtained for testing of sex and potassium permanganate consumption.

Adhesion: A knife is used to make 11 cuts in each of the length and width in a width of about 1.5 mm using a knife on the coating surface of the test coated plate. A cellophane adhesive tape with a width of 24 mm is adhered, and the adhesiveness of the eye area when strongly peeled off is observed. ◯: No peeling at all △: Slight peeling off ×: Significant peeling off

Sliding property: EGAN SLIP TESTER at 20 ° C.
(Thwing Albert Instrument Company, USA), a weight of a steel ball three-point contact type with a load of 3 kg is set on a test plate, and the dynamic friction coefficient at a moving speed of 10 cm / min is measured.

Workability: Using a special goby folding DuPont impact tester in a room at 20 ° C., two aluminum plates having a thickness of 0.3 mm are provided between the bent portions of the test coated plate whose bottom is folded in two. It is sandwiched and set in the tester, and the contact surface is flat with a weight of 3 kg.
After dropping the iron weight of 50cm from the height of 50cm to give an impact to the bending part, energize the bending tip with an applied voltage of 6.5V for 6 seconds, and the current value of the bending tip 20mm width (mA) To measure. ◎: Less than 1mA ○: 1mA or more and less than 5mA △: 5mA or more and less than 10mA ×: 10mA or more

Chloroform extraction amount: test coated plate 10 cm ×
Was cut into a size of 10 cm, the ratio of the application area and the chloroform amount is set to be 1 cm ^2/1 cc, it was immersed in chloroform of boiling. Extract with boiling chloroform for 1 hour. The ratio of the extracted amount to the coating film weight of the test coated plate before treatment is expressed as a percentage.

Boiling resistance: test coated plate at 100 ° C., 30
Min., After immersion in boiling water, the appearance of the coating film is visually evaluated, and the coated plate after the test is evaluated for adhesion by the same evaluation method as the above adhesion test. Regarding the appearance of the coating film, those with no abnormalities such as whitening or blistering are marked with a circle.

Flavorability of water extract: A test coated plate coated with an aluminum foil having a thickness of 0.1 mm was treated with activated carbon so that the amount of tap water treated with activated carbon was 1 cc per 1 cm ² of the coating area. Put in a glass bottle, cover with a lid, 12
After sterilizing treatment at 5 ° C for 30 minutes, a flavor test of the content liquid is performed. ◯: No change was observed at all Δ: There was a slight change ×: There was a significant change

Potassium permanganate consumption: The liquid obtained in the flavor test of the above water extract was measured according to the test method described in the Food Sanitation Law (Ministry of Health and Welfare 434). Consumption
Expressed in ppm.

Stability of paint over time: 100 ml of water-based paint was placed in a glass wide-mouthed bottle having an inner volume of 100 ml and sealed, and
Stored in a constant temperature bath at ℃ for 1 month and then opened and inspected to check the presence of skin on the liquid surface, viscosity of water-based paint, average particle size of dispersed particles Compare. ○: Almost no change △: Slight change ×: Significant change

[0072]

[Table 1]

Claims (4)

[Claims] 1. An aqueous coating composition comprising a fatty acid sucrose ester dissolved or dispersed in the aqueous coating. 2. A fatty acid sucrose ester is represented by the following general formula [1]:
The coating composition according to claim 1, which is a compound represented by: [Chemical 1] (In the formula, R is the same or different and is a hydrogen atom or R ¹ OC-
And an at least one R out of the eight R is R ¹ OC—, and R ¹ represents an alkyl group or an alkenyl group having 10 to 22 carbon atoms. ) 3. The aqueous coating composition according to claim 1 or 2, wherein the aqueous coating contains a graft product of an aromatic epoxy resin and a high acid value acrylic resin as a water-dispersible resin component. 4. The aqueous paint composition according to claim 3, wherein the aqueous paint contains a phenol resin or an amino resin as a cross-linking resin.