JPS5825113B2 - Suiseinetsukoseihiohoisoseibutsu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous thermosetting coating composition with a low organic solvent content, which is capable of forming a coating film with excellent coating surface condition and coating performance, and with extremely low occurrence of sagging and wrinkling. be.

Conventionally, organic solvent solution-type coating compositions have been widely used as general-purpose coating compositions, but these coating compositions contain large amounts of organic solvents that do not form a coating film. During the painting and drying process of wood, a huge amount of these organic solvents are released into the atmosphere, which causes air pollution and is also important from the perspective of saving resources. It has been pointed out that it is undesirable.

Therefore, there is a strong desire to develop new general-purpose coating compositions that can replace these organic solvent solution type coating compositions, especially thermosetting coating compositions used in industrial coatings.

In addition, aqueous thermosetting coating compositions using water as a medium have been developed as coating materials without the above-mentioned disadvantages, particularly aqueous polymer dispersions (hereinafter abbreviated as latex) obtained by emulsion polymerization or aqueous solutions of water-soluble resins. (hereinafter abbreviated as water-soluble resin) are known, and since these water-based coating compositions use water as a medium, they are less likely to cause air pollution and are desirable from the point of view of resource conservation. Not only is it easy to use, but it also has the excellent advantage that there is no risk of fire, explosion, or poisoning to humans when handling it.

However, coating films formed from thermosetting coating compositions mainly containing latex have a lower evaporation rate of water, which is a solvent, from the coating film than coating films formed from coating compositions mainly containing water-soluble resins. Since the coating film is large, it is difficult to cause coating defects such as wrinkles and sagging, and the resulting coating film has excellent mechanical properties, but it has poor water resistance and corrosion resistance, and it is difficult to produce coatings formed from enamel mixed with pigments. The coating surface condition of the film is also not good.

For this reason, although a number of thermosetting aqueous coating compositions mainly containing latex have been proposed, their practical use has only been limited to some fields of application where these drawbacks are not a problem.

In addition, a coating film formed from a thermosetting coating composition mainly containing a water-soluble resin can provide a coating film with a good surface condition, but it is also possible to obtain a coating film with a low solids content at a coating suitable viscosity. Since the evaporation rate of water present in the film is low, coating film defects such as wrinkles and sagging are likely to occur, and it is difficult to paint a thick film with one coat.

In addition, water-soluble resins are made of polymers containing many hydrophilic functional groups, and aqueous liquids containing such polymers tend to have high viscosity, so it is necessary to reduce the molecular weight of the polymers contained therein. do not have.

Therefore, the coating film formed from a coating material made of such a water-soluble resin solution has a drawback that its alkali resistance, acid resistance, solvent resistance, stain resistance, etc. are poor.

The present inventors have previously studied with the aim of improving the drawbacks of coating materials made of latex or water-soluble resin, and have developed a copolymer containing a hydroxyalkyl ester of α/β-monoethylenically unsaturated carboxylic acid. Combined latex (I)
and a water-soluble resin (II) which is a salt of a copolymer containing a hydroxyalkyl ester of an α/β-monoethylenically unsaturated carboxylic acid (I)/(n)-75/25-30
By mixing a thermosetting formaldehyde condensation product into the dispersion obtained by mixing at a ratio of resin weight of /70 (resin weight ratio), it is possible to improve the mechanical properties and chemical resistance of the coating film, and to create a coating composition that is compatible with organic solvent solution type coating compositions. Although we have found a water-based thermosetting coating composition with a similar coating surface condition (glossy window) represented by similar gloss values and image clarity and applied for a patent, the coating film formed from the coating material obtained using this technology still has organic properties. Compared to coatings formed from solvent-based coating materials, coating properties such as solvent resistance, stain resistance, flexibility, water resistance, and boiling water resistance are not sufficient, and the path to developing new applications is limited. There is.

Therefore, the present inventors investigated with the aim of resolving the above-mentioned disadvantages, and introduced specific amounts of hydroxyalkyl ester groups and N-alkoxymethylamide groups as crosslinking reactive groups contained in the resin constituting the latex. The present invention was completed by discovering that the object could be achieved by using the following method.

The gist of the present invention is hydroxyalkyl esters of α,β-monoethylenically unsaturated carboxylic acids.

Monomer (1) and a monomer (
5 to 30 mol% of a monomer mixture of 2.5797.5 to 97.5/2.5 (mole ratio) of 2) and a monomer ( 3) 1-6
mol%, 20 to 94 mol% of monomer (4) whose homopolymer has a glass transition temperature of 20°C or higher, and other α/β-monoethylenically unsaturated compounds that can be copolymerized with these. A latex (I) of a copolymer copolymerized in the presence of a combined emulsifier in a proportion of 74 mol% or less of monomer (5) to a total of 100 mol%, and the above monomer (1) or 5 to 30 mol% of at least one of the monomers (2), 3 to 20 mol% of the monomer (3), and 20 to 94 mol% of the monomer (4)
, a water-soluble resin (II) which is a salt of a copolymer copolymerized by combining monomer (5) at a ratio of 72 mol% or less to a total of 100 mol% (I) / (II) ~ 80/
Dispersion liquid (A) obtained by mixing 20 to 30/70 (resin weight ratio) and water-soluble or water-dispersible thermosetting formaldehyde (B) (A)/(B) = 95/5 to 6
An aqueous thermosetting coating composition characterized by being mixed at a ratio of 0/40 (resin weight ratio).

Specific examples of hydroxyalkyl esters of α/β-monoethylenically unsaturated carboxylic acids, which are monomers (1) used to produce the copolymer latex and water-soluble resin used in carrying out the present invention. Examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4- Examples include monoesters of α/β-monoethylenically unsaturated carboxylic acids such as acrylic acid and methacrylic acid, typified by hydroxybutyl (meth)acrylate, and polyhydric alcohols.

Specific examples of N-alkoxymethylated α/β-monoethylenically unsaturated carboxylic acid amide of monomer (2) include N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, -n-propoxymethyl (meth)acrylamide, N-inpropoxymethyl (meth)acrylamide, N-n-butoxymethyl (meth)acrylamide, N-Dec-butoxymethyl (meth)acrylamide, N-t-butoxymethyl (meth)acrylamide, ) acrylamide, N-imbutoxymethyl (meth)acrylamide, and the like.

When producing latex, the copolymerization amount of the hydroxy group-containing monomer (1), which is a crosslinking functional group, and the monomer (2) having an N-alkoxymethylamide group is determined by the amount of copolymerization between the monomer (1) and the monomer (2), which are crosslinked functional groups. 2) and molar ratio of 2.5797.5 to 97.572
．． It is necessary to copolymerize the mixture at a ratio of 5 to 30 mol %.

If the mixing ratio of these monomers is outside the above range, that is, if a monomer mixture containing a large amount of hydroxyl group-containing vinyl monomer is used, the hydrophilicity of the resulting latex will be higher than the hydrophilicity of the latex targeted by the present invention. A coating film formed from a resin composition composed of such latex and a water-soluble resin has higher hydrophilicity than a coating film formed from the coating material of the present invention, and has excellent water resistance, alkali resistance, and resistance. This is not preferable because it tends to reduce coating film performance such as chemical properties.

In addition, the coating film formed from the coating material made of latex and water-soluble resin using a monomer mixture containing a large amount of N-alkoxymethylamide group-containing monomer has stain resistance, impact resistance, chemical resistance, and other coating properties. This is not preferable because the membrane performance tends to deteriorate.

Furthermore, it is difficult to form a coating film as the object of the present invention from a coating material containing latex in which the copolymerization amount of these monomer mixtures is less than 5 mol%; It is not possible to form a coating film with excellent flexibility, chemical resistance, alkali resistance, and other mechanical properties from a coating material containing latex with a content of 30 mol % or more.

In addition, when producing a water-soluble resin, the above-mentioned monomer (1
) or at least one of the monomers (2) at 5 to 30 mol%
It is necessary to copolymerize at a certain ratio.

Coating materials containing water-soluble resins in which the copolymerization amount of these monomers is less than 5 mol% cannot form a coating film in which the latex layer and the water-soluble resin layer are integrated through a crosslinked structure, resulting in an aesthetically pleasing appearance. It is not possible to form a coating film that has excellent properties and coating performance.

On the other hand, coatings formed from coatings made of latex and water-soluble polymers with a copolymerization amount of more than 30 mol% of these monomers have poor stain resistance, impact resistance, flexibility, etc. This is not desirable because it causes a decline in behavioral performance.

In particular, in the present invention, monomers (
A mixture of 1) and monomer (2), especially 2.5/97.5
The coating material made of water-soluble resin and latex obtained when using a monomer mixture with a ratio of ~97.5/2.5 (mole ratio) has excellent miscibility with the pigment itself and The coating film formed from such a coating material of the present invention can have an extremely uniform crosslinked structure, and also forms a coating film with particularly excellent chemical resistance, alkali resistance, and other mechanical properties. I like it because I can do it.

Specific examples of the α/β-monoethylenically unsaturated carboxylic acid, which is the monomer (3), include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, etc., or these dibasic acids and monohydric acids. Examples include monoesters with alcohols.

In the production of latex, it is effective to select and use methacrylic acid and acrylic acid from among these monomers, considering the copolymerizability in emulsion polymerization, and the copolymerization amount is 1 to 6 mol%. The preferred range is 1 to 4 mol%.

This monomer is a component that increases the mechanical stability and freeze-thaw stability of latex, and also improves the mechanical properties and chemical resistance of coating films formed from coating materials made of latex and water-soluble resin. A coating material made of a copolymer latex and a water-soluble resin in which the copolymerized amount of monomer 3) exceeds 6 mol% has a high viscosity.
In addition to being difficult to handle, the coating film formed from such coating materials not only deteriorates in appearance, but also deteriorates in mechanical properties and
This is not preferable because the coating properties such as chemical resistance deteriorate.

Further, the amount of copolymerization of monomer (3) in producing the water-soluble resin needs to be in the range of 3 to 20 mol%, preferably 5 to 15%.

A salt of a copolymer in which the amount of copolymerized monomer (3) exceeds 20 mol % becomes significantly hydrophilic and has a high viscosity, making it difficult to handle.

Furthermore, a coating film formed from a coating material made of such a water-soluble polymer and latex is not preferable because it has significantly poor water resistance and alkali resistance.

When manufacturing a water-soluble resin using the solution polymerization method, it is best to select and use acrylic acid, methacrylic acid, and itaconic acid from among these monomers (3). Get results.

Specific examples of the monomer (4) having a glass transition temperature of 20°C or higher include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, Dec-butyl methacrylate, t-butyl methacrylate, Inbutyl methacrylate, cyclohexyl methacrylate,
Examples include methacrylic acid esters represented by phenyl methacrylate and benzyl methacrylate, styrene, vinyltoluene, α-methylstyrene, (meth)acrylonitrile, and vinyl acetate.

These monomers are necessary components to improve the properties of the coating film formed from the coating material of the present invention, and can be copolymerized in the latex and water-soluble resin in the proportions described above. is necessary.

Specific examples of monomer (5) include methyl acrylate,
Ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, l)
6cm butyl acrylate, t-butyl acrylate,
Inbutyl acrylate, n-hexyl acrylate,
Monoesters of acrylic acid and alkanols having 1 to 18 carbon atoms, such as 2-ethylhexyl acrylate, n-octyl acrylate, lauryl acrylate, tridecyl acrylate, stearyl acrylate, and cyclohexyl acrylate, and glass transition points. 20
methacrylic acid esters such as n-hexyl methacrylate, n-octyl methacrylate, 2-
Ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, etc. (meth)acrylamide, N-methylol (meth)acrylamide, N
-N-dimethylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, etc. can be mentioned.

To make the copolymer latex used in carrying out the present invention, the above-mentioned monomers may be combined in specified amounts and produced using a conventional emulsion polymerization method, but the reaction temperature of the polymerization system is preferably 20-100°C. Preferably, the temperature is in the range of 30 to 80°C.

Radical release initiators are used as the polymerization initiator, and redox initiators are particularly effective.

Anionic surfactants, nonionic surfactants, and mixtures thereof are effective as emulsifiers, but cationic surfactants, surfactants, polymeric surfactants, polyvinyl alcohol, and starch are effective as emulsifiers. Water-soluble polymers such as , dextrin, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, etc. can also be used sometimes.

A chain transfer agent may be used to adjust the molecular weight of the copolymer, and water-insoluble or poorly water-soluble mercaptans are effective.

The pH value of the copolymer latex produced by emulsion polymerization usually has a value of 2 to 5, but when producing the coating composition of the present invention, the pH value of the latex is set to 7 to 1.
It is preferable to use the latex after adjusting it to a value of H, since the stability of the latex is increased, it is easier to handle, and troubles during the production of the covering material can be avoided.

The alkaline substances used to adjust the pH of the latex include ammonia, primary amines, secondary amines, tertiary amines, sodium hydroxide, potassium hydroxide, etc. Considering the characteristics of the coating film formed from the coating material, it is preferable to use volatile tertiary amines such as triethylamine and dimethylaminoethanol.

The water-soluble resin used in the present invention can be produced by various methods such as bulk polymerization, solution polymerization, and emulsion polymerization.

When producing a water-soluble resin by emulsion polymerization, the acid copolymer latex obtained in the same manner as in the production of latex above is diluted with water as necessary, and then the alkali substance used in the production of the above latex is added to the acid copolymer latex. A water-soluble resin can be obtained by adding it.

In addition, when producing a water-soluble resin by solution polymerization, a radical release initiator such as benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, azobisisobutyronitrile, etc. is used as a polymerization catalyst, and a polymerization solvent is used as a polymerization solvent. methanol, ethanol,
Alcohols such as n-propatool, isopropatool, Dec-butanol, and imbutanol; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve; calpitols such as methyl calpitol, ethyl calpitol, and butyl calpitol; acetone, It is preferable to carry out the polymerization using a water-soluble or water-relatively soluble solvent such as acetone alcohol, or a mixture of these solvents at a temperature of 50 to 150°C.

In order to make an aqueous solution of a water-soluble resin using the solution polymerization method, after the completion of polymerization, an alkali substance is added to the organic solvent solution to form a salt, and a water-soluble resin solution can be obtained by adding drained water.

In addition to the above-mentioned solvents, solvents that are sparingly soluble or insoluble in water, such as toluene, xylene, methyl ethyl ketone, methyl imbutyl ketone, ethyl acetate, butyl acetate, etc., can also be used as the polymerization agent. When mixing with a water-soluble resin, the latex particles may coagulate or thicken significantly, so to prevent this from occurring, it is necessary to reduce or eliminate the amount of these organic solvents used. It is.

For the production of water-soluble resins, it is industrially advantageous to directly add an alkaline substance to the latex or organic solvent solution to make it water-soluble, as described above, but once the acid copolymer is isolated, it is introduced into water. It is also possible to use a method in which the above-mentioned alkaline substance is added and, if necessary, stirred and dissolved under heating.

In the present invention, the copolymer latex (I) prepared as described above and the above-mentioned water-soluble resin are mixed in a resin weight ratio of (I)/(
III)-8o/20~30/70 preferably 75
The water-soluble or water-dispersible formaldehyde condensation product (B) (
It is necessary to mix A)/(B) at a ratio of -95/5 to 60/40 (resin weight ratio).

Various film performances such as finished appearance, water resistance, boiling water resistance, alkali resistance, mechanical properties, and flexibility of the coating film formed from the coating material obtained by the present invention are different from conventional organic solvent-based coatings. The reason why it is possible to form a paint film with no color loss compared to the performance of a paint film formed from a coating material is that in the process of forming the paint film, the water-soluble resin (II) is mixed with the latex (I) in the paint film. ) Since coating film formation takes place while filling the gaps between particles, the MFT (minimum film formation This is thought to be because the temperature no longer appears, making it possible to form a coating film with uniform characteristics.

Further, the resin contained in the latex constituting the coating material of the present invention contains a combination of a hydroxyalkyl ester group and an N-alkoxymethylamide group in a specific amount as a crosslinking reactive group, while the aqueous solution Since the resin contains at least one type of N-alkoxymethyl group or hydroxyalkyl ester as a crosslinking reactive group, a tight crosslinking bond can be easily formed between the two during the baking process of the coating film. Therefore, the mechanical properties of the resulting coating film, such as chemical resistance, water resistance, boiling water resistance, and flexibility, can be significantly improved.

When carrying out the present invention, it is necessary that the mixing ratio of latex (I) and water-soluble resin is in the range of 80/20 to 30/70, and the proportion of water-soluble resin is 20% by weight.
If the amount of coating material is less than 70% by weight, MFT will appear in the coating film formation process and it will be extremely difficult to form a coating film with uniform properties, so it is not preferable. In addition, coating materials are more likely to cause coating defects such as sagging and wrinkles during the coating film formation process, and the resulting coating film has poor alkali resistance, acid resistance,
This is not preferable because the coating film properties such as solvent resistance and stain resistance suddenly deteriorate.

Specific examples of water-soluble or water-dispersible thermosetting formaldehyde condensation products used in carrying out the present invention include formaldehyde and phenol, urea, thiourea, N-N
- Examples include condensation products with ethylene urea and aminotriazines, such as melamine, benzoguanamine, acetoguanamine, etc., and condensation products in which the methylolamino groups of these condensation products are partially or fully alkoxylated with lower alcohols. be able to.

It is necessary to use these formaldehyde condensation products in a range of 5 to 40% by weight based on the resin dispersion (A), and it is necessary to use a coating material containing less than 5% by weight of this condensation product. A coating film formed from a coating material containing more than 40% by weight of this condensation product is undesirable because its mechanical and chemical properties deteriorate. This is undesirable because mechanical coating film properties such as flexibility and impact-coagulation resistance, as well as properties such as acid resistance, water resistance, and boiling water resistance, tend to deteriorate rapidly.

The coating compositions of the invention can be used as clear or pigmented or dyed enamels.

To make enamel from the coating composition of the present invention, first, a pigment paste is made by kneading the pigment and the water-soluble resin (II) using a ball mill, third mill, three-roll mill, etc., and then this pigment paste and It is preferable to use a method of adding and mixing a latex thermosetting formaldehyde resin and, if necessary, a water-soluble resin.

The colored coating material thus obtained has good pigment dispersion stability and can form a colored coating film with excellent performance, although the main component of the coating material is latex.

The coating material composition of the present invention is preferably used by adjusting its pH value to a range of 7 to 11, preferably 8 to IO.

In addition, the coating film formed from this coating material is
It is desirable to select a desired temperature and time within a temperature range of 1 to 60 minutes for baking time.

In addition, although the coating material of the present invention is a water-based coating material, it also uses spray coating methods, brush printing methods, curtain flow coating methods, and electrostatic coating methods that have been conventionally used as coating methods for organic solvent-based coating materials. It can be easily painted using methods such as metal, asbestos, wood, stone, etc.
It can be applied to various materials such as textiles and leather paper.

In particular, when used as a coating material for metal materials that requires good chemical resistance, stain resistance, water resistance, boiling water resistance, and mechanical properties, as well as the formation of a coating film with good surface condition. , maximize its effectiveness.

The present invention will be explained in more detail with reference to Examples below.

Example 1 (1-1,) Production of latex 129 parts of deionized water and a 25% aqueous solution of surfactant were placed in a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping port, and inert gas inlet. (Manufactured by Kao Atlas: Lehesol W
Z ) 4.0 parts were added and nitrogen gas was blown in for 15 minutes to deoxidize.

Next, the internal temperature was heated to 60°C, and then an aqueous solution of 4.0 parts of Lebenol WZ, 0.23 parts of ammonium persulfate, and 0.15 parts of sodium acid sulfite dissolved in 15 parts of deionized water and 33.2 parts of styrene were added. part (33-6 mol%)
, 49.8 parts (52.5 mol%) of ethyl acrylate,
1010 parts of 2-hydroxyethyl methacrylate (8,
1 mol%), N-butoxymethylacrylamide 5.0
(3.4 mol %) and 2.0 parts (2.4 mol %) of methacrylic acid were added dropwise separately over 2 hours.

During the reaction, nitrogen gas is continuously blown into the surface to keep the internal temperature at 60 parts and 1°C.
When the reaction was completed, the solid content was 41.0% and the pH was 2.58.
Viscosity 45 cps (B-type viscometer, rotation speed 6 Orpm, 2
A latex of pH-9.0 was obtained by adding β-dimethylaminoethanol to this latex.
latex (L-1) was obtained.

7l-2) Production of water-soluble resin from solution polymer In a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer, 31.2 parts (32.2 mol%) of styrene and 46.8 parts (50.2 mol%) of ethyl acrylate were added. 3 mol%) 2-hydroxyethyl 10.0 parts (8.3 mol%) N-butoxymethyl methacrylate 5.0 parts (3.4 mol%) Acrylamide itaconic acid 7.0 parts (5.8 mol%) ) Methyl cellosolve 66.7 parts n-octyl mer strength 3.0 parts Butaneazobisin butyro 0.5 parts Nitrile was added and heated from room temperature to 75°C over 2 hours with stirring, then for 6 hours. Keep at 75°C.

0.1 part, 0.2 part, 0.3 part per hour after heating to 75°C
part, 0.4 part, 0.5 part, 0.6 part of azobisisobutyronitrile.

Thereafter, the temperature was raised to 85°C and the temperature was maintained at 85°C for 4 hours to complete the polymerization, resulting in a resin solution having a solid content concentration of 60.4%, an acid value of 32.1, and a Gardner bubble viscosity of z3 (20°C).

After adding 9.6 parts of β-dimethylamine ethanol to 172.6 parts of this resin solution, 89 parts of deionized water was added to obtain a water-soluble resin (W-1) with a solid content of 39.8%.

Preparation method of pigment paste (P-1) Titanium oxide 150 Partial dispersant 25% aqueous solution (Kao Atla 6 parts Demol EP manufactured by Kao Su Co., Ltd.) Antifoaming agent 0.3 parts Deionized water 46 parts or more were kneaded in a ball mill for 2 days. A pigment paste (p-i) was obtained.

Preparation method of pigment paste (P-2)> 200 parts of titanium oxide, 50 parts of water-soluble resin, 0.4 parts of tri-butyl phosphate, and 60 parts of deionized water or more were kneaded in a ball mill for 2 days to form a pigment paste (P-2). -2) was obtained.

Blending method of enamel> The pigment pastes (P-1) and (P-2) are mixed with a water-soluble resin (W-1), a latex (L-1) and a methoxymethyl melamine resin partially containing residual methylol groups (Nippon Car A latex resin/water-soluble resin ratio as shown in Table 1 was obtained by adding Nikaratsuku MW) manufactured by Baito Co., Ltd., and the amount of melamine resin was 15% by weight, and the weight concentration of pigment was 45% by weight.

After adding β-dimethylamine ethanol to the pH of these enamels to 9.0 to 9.5, deionized water was added if necessary to prepare Ford cup #4.
The time was adjusted to 20±2 seconds.

After spray painting these diluted enamels on a polished mild steel plate (0.8 mm) treated with zinc phosphate,
Baked at 0°C for 20 minutes.

Table 1 shows the surface condition and film performance of the obtained coating film.

The coating film shown in Experiment No. 1, 2.3 had poor gloss, corrosion resistance, and boiling water resistance on the painted surface, and Experiment No. 7.8.9
The paints shown in , IO tend to flake off unless a sufficiently long setting time is allowed, resulting in poor painting workability.

Furthermore, the staining resistance, alkali resistance, acid resistance, corrosion resistance, and boiling water resistance of the coating film are poor.

The paints shown in Experiment Nos. 4 to 6 do not easily peel off even if the setting time is short, and the glossiness of the painted surface and overall film performance are excellent.

The temperature at the time of painting was 20-23℃, and the relative humidity was 60-23℃.
It was 70%.

Example 2 (2-1) Production of latex In the production of latex shown in (1,-1) of Example 1, 21.0 parts (23,0 parts) of styrene was used as the monomer mixture.
2.10 parts (mol%) of methyl methacrylate (24.0 mol%), 41.0 parts (36.6 mol%) of n-butyl acrylate, 2-hydroxyethyl methacrylate) 10.
Exactly the same polymerization method except for 3 using 0 parts (8.8 mol%), 5.0 parts (5.0 mol%) of N-methoxymethylacrylamide, and 2.0 parts (2.6 mol%) of methacrylic acid. Solid content 40.2%, pH 2.48, viscosity 54 cps
of latex was obtained.

A latex (L-2) whose pH was adjusted to 9.0 by adding β-dimethylaminoethanol to this latex was obtained.

(2-2) Production of water-soluble resin from solution polymer In the method for producing water-soluble resin shown in (1-2) of Example 1, 20.0 parts (22.0 mol%) of styrene was used as the monomer mixture.
), 20.0 parts of methyl methacrylate (22.9 mol%
), n-butyl acrylate 37.0 parts (33°2 mol%) N-methoxymethyl acrylamide 15 parts (14,
9 mol%), 8 parts of itaconic acid (7.0 mol%), and 3.0 parts of n-octyl mercaptan, and the same polymerization method was used except for 3 to obtain a solid content of 60.6% and an acid value of 36.
．． 4. A resin solution with a Gardner bubble viscosity of 2-2° was obtained.

To 172.6 parts of this resin solution, 1069 parts of B-dimethylaminoethanol was added, followed by 89 parts of deionized water to obtain a water-soluble resin (W-2) with a solid content of 39.5%.

(2-3) Production of pigment coating composition Pigment paste (P-3) was prepared in exactly the same manner as shown in Example I (1-3) except that the water-soluble resin (W-2) was used. I got it.

Using pigment paste (P-3), water-soluble resin (W-2), latex (L-2), and methoxymethyl melamine resin, the latex/water-soluble resin (resin weight ratio) was 70730.
, (latex + water-soluble resin)/methoxymethylmelamine resin (resin weight ratio) is 85715, pigment weight concentration 40
% enamel, 35 parts 2 in Ford Cup #4
It was diluted with deionized water to a viscosity of seconds.

A 0.3 mm galvanized steel plate treated with zinc phosphate was coated with a Percoater, and after 10 minutes of setting, it was baked and dried at 260°C for 60 seconds.

The thickness of the resulting coating film was 20 μm, the gloss value (600 specular reflectance) was 84, and the coating surface condition was good.

In addition, mechanical properties (hardness, impact resistance, Erichsen, flexibility, etc.), solvent resistance, stain resistance, and corrosion resistance were also good.

Example 3 (3-1) Production of water-soluble resin from latex In the production of latex shown in (1-1) of Example 1, 19.0 parts (20.4 mol%) of styrene was used as the monomer mixture (8). ) Methyl methacrylate) 19.0 parts (21.3 mol%), n-butyl acrylate 37.0 parts (32.4 mol%), 2-hydroxyethyl methacrylate 15.0
parts (12.9 mol%), methacrylic acid l010 parts (13
, 0 mol%), solid content 40.2% pH 2.31 by carrying out polymerization in exactly the same manner except that floatation polymerization was carried out using 3.0 parts of t-dodecyl mercaptan.
, a latex with a viscosity of 50 cps was obtained.

After adding 153 parts of deionized water to 255 parts of the produced latex, 1014 parts of β-dimethylaminoethanol was added and stirred for 3 hours at 40°C to make the latex water-soluble and water-soluble resin (W-, - 3) was obtained.

(3-2) Production of pigment coating composition Pigment paste (P-4) having the following ratio was obtained according to the production of pigment paste (P-2) in Example 1.

200 parts of titanium oxide R-820 Distributed on top of 80 parts of water-soluble resin (W-3) 0.4 parts of triisobutyl phosphate 30 parts of deionized water W
-3), latex (L-2), methoxymethyl melamine resin (W22), latex/water soluble resin (resin weight ratio) is 70730, (latex + water soluble resin)/methoxy methyl melamine resin An enamel with a weight ratio of 85/15 and a pigment weight concentration of 40% was mixed, and painted and baked in the same manner as in Example 2.

The resulting coating film has a film thickness of 18 μm and a gloss value of 82, showing a good surface condition, and also has good mechanical properties (hardness, impact resistance, Erichsen, flexibility, etc.), solvent resistance, stain resistance, and corrosion resistance. It was good.

Claims (1)

[Claims] 1 Monomer (1) is a hydroxyalkyl ester of α/β-monoethylenically unsaturated carboxylic acid, monomer (2) is an N~alkoxymethylated product of α/β-monoethylenically unsaturated carboxylic acid amide, α/β-monoethylenically unsaturated carboxylic acid is used as the monomer (3), and other copolymerizable monomers whose homopolymer glass transition temperature is 20°C or higher are used as the monomer (4).
), a copolymerizable α/β-monoethylenically unsaturated compound other than the above is mixed with monomer (1) and monomer (2) using monomer (5) in the presence of an emulsifier. 5797.5-97
．． 5/2.5 (molar ratio) mixture of monomers 5 to 30
Mol% and monomer (3) 1 to 6 mol%, monomer (4) 20
An aqueous dispersion (I) of a copolymer obtained by copolymerizing a copolymer with a total of 100 mol% of 94 mol% of monomer (5) and 75 mol% of monomer (5) or less; 1) and at least one of monomer (2) 5 to 30 mol%, monomer (3) 3 to 20 mol%, monomer (4) 20 to 30 mol%
A water-soluble resin (n) which is a salt of a copolymer copolymerized in a water-soluble organic solvent in such a manner that 92 mol% of monomer (5) and 72 mol% or less of monomer (5) become a total of 100 mol%.
A dispersion (A) obtained by mixing (I)/(II) = 80/20 to 30/70 (resin weight ratio) and a water-soluble or water-dispersible thermosetting formaldehyde condensation product (B)
An aqueous thermosetting coating material composition characterized by mixing (A)/(B) -9515 to 60/40 (resin weight ratio).