JPS5825111B2 - Suiseinetsukoseihiohoisoseibutsu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous thermosetting coating composition capable of forming a coating film with excellent coating surface condition and coating performance, and with extremely little sagging or flaking.

Conventionally, organic solvent solution-type coating compositions have been widely used as general-purpose coating compositions; These organic solvents have been released into the atmosphere during the painting and drying process of materials, and it has been pointed out that these organic solvents released into the atmosphere cause air pollution and are also undesirable from the perspective of resource conservation. has been done.

Therefore, there is a strong desire to develop a new general-purpose coating composition that can replace these organic solvent solution type coating compositions, especially a thermosetting coating composition 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, which is desirable from the point of view of resource conservation. In addition, it has the excellent advantage that there is no risk of fire, explosion, or poisoning to the human body during handling.

However, coating films formed from thermosetting coating compositions mainly containing latex have a higher resistance to water as a solvent in the coating film than coating films formed from coating compositions mainly containing water-soluble resins. Because the evaporation rate is very high, paint film defects such as wrinkles and sagging are less likely to occur, and the resulting paint film has excellent mechanical properties, but has poor water resistance and corrosion resistance. The surface condition of the coating film is also not good.

For this reason, although 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 the solid content of the coating composition at a coating suitable viscosity is low, and moreover, it is difficult to form a coating film. The evaporation rate of the water present in the paint film is low, so the underarms and
Paint film defects such as sagging are likely to occur, making it difficult to apply a thick film in 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. .

Therefore, the coating film formed from the coating material made of such a water-soluble resin solution has good alkali resistance, acid resistance, solvent resistance,
The disadvantage is that it has poor stain resistance.

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 (I)/(II)-75/25-30/7 for water-soluble resin, which is a salt of a copolymer containing a hydroxyalkyl ester of α/β-monoethylenically unsaturated carboxylic acid.
By mixing a thermosetting formaldehyde condensation product into the dispersion obtained by mixing at a resin weight ratio of 0 (resin weight ratio), the mechanical properties and chemical resistance of the coating film are excellent and the same as that of organic solvent solution type coating compositions. Although we have discovered and applied for a patent for an aqueous thermosetting coating composition that has a coating surface condition (glossiness) represented by gloss value and image clarity, there are still no problems with the coating film formed from the coating material obtained using this technology. Compared to coatings formed from organic solvent solution type coating materials, they have better solvent resistance, stain resistance, flexibility,
The coating film performance, such as water resistance and boiling water resistance, is not sufficient, and the path to developing new applications is limited.

Therefore, the present inventors aimed to eliminate the above-mentioned disadvantages by introducing into a water-soluble resin a specific amount of a functional group capable of crosslinking with the hydroxyalkyl group contained in the resin constituting the latex. The present invention was completed by finding a way to achieve the object.

The gist of the present invention is that 5 to 20 mol% of monomer (1) which is a hydroxyalkyl ester of α/β-monoethylenically unsaturated carboxylic acid and α/β-monoethylenically unsaturated carboxylic acid are 1 to 6 mol% of a certain monomer (3),
20 to 94 mol% of monomer (4), which is a copolymerizable monomer whose homopolymer glass transition temperature is 20°C or higher, and other α/β monoethylenically unsaturated compounds that can be copolymerized with these monomers A total of 10 monomers (5) in a proportion of 74 mol% or less
A copolymer latex (I) copolymerized in the presence of a combined emulsifier so that the concentration is 0 mol %, and a monomer that is an N-alkoxymethylated product of α/β-monoethylenically unsaturated carboxylic acid amide. (2) or monomer (2) and monomer (
Monomers in a ratio of 5 to 30 mol% in total of 1), 3 to 20 mol% of monomer (3), 20 to 94 mol% of monomer (5), and 72 mol% or less of monomer (5) (I)/(II)-s o / 20-3
Dispersion liquid (A) obtained by mixing at 0/70 (resin weight ratio)
J and water-soluble or water-dispersible thermosetting formaldehyde (B
) and (A)/(B) -95/5 to 60/40 (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 dihydric 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-oec-butoxymethyl (meth)acrylamide, N-t-butoxymethyl (meth)acrylamide, ) acrylamide, N-isobutoxymethyl (meth)acrylamide, and the like.

When producing latex, it is necessary that the amount of copolymerized monomer (1) having a hydroxyl group be 5 to 20 mol%.

If the copolymerization amount of monomer (1) is 5 mol% or less.

This is not preferable because the crosslinking density of the coating film formed from the mixture of the latex and the water-soluble resin cannot be increased, making it impossible to form a coating film with excellent coating performance.

In addition, a large amount of free hydroxyl groups may remain in the coating film formed from a coating material made using a latex containing a copolymer with a large copolymerization amount of monomer (1) exceeding 20 mol%. This is not preferable because the water resistance, stain resistance, and flexibility of the coating film tend to deteriorate.

In addition, when producing a water-soluble resin, monomer (2) containing an N-alkoxymethylamide group or a monomer containing 5 mol% or more of monomer (2) and in combination with monomer (1) is used. It is necessary to copolymerize the mixture in a proportion of 5 to 30 mol %.

If the copolymerization amount of these monomers is too small, the crosslinking density of the coating film formed from the coating material composition containing this water-soluble resin will decrease and the formation of a uniform and dense crosslinked structure will be inhibited. This is not preferable because it becomes difficult to form a coating film having the performance aimed at by the present invention.

In addition, when the amount of copolymerization of these monomers increases, the stain resistance of coating films formed from coating materials containing these water-soluble resins decreases.
This is not preferable because it reduces flexibility.

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

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

This monomer is a component that increases the mechanical stability and freeze-thaw stability of the latex obtained, and is also a component that can improve the mechanical properties and chemical resistance of the coating film formed from the coating material containing this latex. However, the viscosity of coating materials containing latex with a copolymerization amount of monomer (3) greater than 6 mol % increases, making them difficult to handle, and the coating film formed from such coating materials Not only will the chemical properties and chemical resistance deteriorate, but the aesthetic appearance will be significantly impaired.

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 mol%.

A copolymer in which the copolymerization amount of monomer (3) exceeds 20 mol % becomes extremely hydrophilic, increases the viscosity of the aqueous resin solution, and makes it difficult to handle. A coating film formed from a coating material containing an aqueous resin is not preferable because it has significantly poor water resistance and alkali resistance.

When manufacturing a water-soluble resin by solution polymerization, it is preferable to select and use acrylic acid, methacrylic acid, and itaconic acid among these monomers, with itaconic acid being the most effective.

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, and Examples include methacrylic acid esters represented by butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, etc., styrene, vinyltoluene, α-methylstyrene (meth)acrylonitrile, vinyl acetate, etc., and these comonomers are used in the present invention. In order to improve the properties of the coating film formed from the coating material, it is necessary to copolymerize the latex and the water-soluble resin within the above-mentioned range.

Specific examples of monomer (5) include methyl acrylate, ethyl acrylate, H-propyl acrylate, isopropyl acrylate, n-butyl acrylate, OEC
-butyl acrylate, t-butyl acrylate, inbutyl acrylate, n-hexyl acrylate, 2-
Etherhexyl acrylate, n-octyl acrylate, lauryl acrylate, tridecyl acrylate,
Monoesters of acrylic acid represented by stearyl acrylate, cyclohexyl acrylate, etc. and alkanols having 1 to 18 carbon atoms and glass transition temperature of 20℃
methacrylic acid esters, such as n-hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylates and (meth)acrylamides, and their methylolated products, N-N-dimethyl Examples include aminoethyl (meth)acrylate and glycidyl (meth)acrylate.

The copolymer latex used in carrying out the present invention is usually a combination of the above-mentioned monomers in specified amounts.

It can be produced by emulsion polymerization, but the reaction temperature of the polymerization system is 20 to 100°C, preferably 30 to 80°C.
This is the range.

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, regenerating surfactants, polymeric surfactants, polyvinyl alcohol, starch, Water-soluble polymers such as dextrin, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, 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 adjusted to a value of 7 to 11. It is preferable to use this method because it increases the stability of the latex, makes it easier to handle, and avoids troubles during the production of the covering material.

Ammonia, primary amines, secondary amines, tertiary amines, sodium hydroxide, potassium hydroxide, etc. are used as alkali-based substances to adjust the pH of the latex, but the storage stability of the coating composition Considering the characteristics of the coating film formed from the coating material of the invention, 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, after diluting the acid copolymer latex obtained in the same manner as in the above latex production with water as necessary, add the alkali substance used in the production of the above latex. A water-soluble resin can be obtained by adding it and making it water-soluble.

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-glopanol, Impropatol, OEC-butanol, isobutanol, celerols such as methylcellulose, ethylcelorilbu, butelcelorilbu, carpitols such as methylcalpitol, etelcalpitol, bunalcarbitol, acetone The polymerization is preferably carried out using a water-soluble or relatively water-soluble solvent such as diacetone alcohol, or a mixture of these solvents at a temperature of 50 to 150°C.

To make an aqueous solution of a water-soluble resin using this solution polymerization method, after the polymerization is completed, an alkali substance is added to this organic solvent solution, and the water removed as a salt is added to make an aqueous resin solution. Therefore, it is convenient.

Depending on the type of polymerization solvent used, latex particles may aggregate when mixed with latex; in such a case, the polymerization solvent may be removed or replaced by a solvent replacement method.

If necessary, in addition to the above-mentioned solvents, a solvent that is sparingly soluble or insoluble in water, such as toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, etc., may be used to prevent latex particles from coagulating when the latex and water-soluble resin are mixed. It is necessary to adjust the amount used so that the viscosity does not increase significantly.

The present invention provides a copolymer latex (
I) and the above-mentioned water-soluble tree shredder in the resin weight ratio (■)/(I
I)=80/20~30/70 preferably 75/25~
A water-soluble or water-dispersible formaldehyde condensation product (B) is added to the dispersion (A) obtained by mixing the water-soluble or water-dispersible formaldehyde condensation product (A).
/(B)=9515 to 60/40 (resin weight ratio).

Various coating properties 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 because the water-soluble resin (6) in the paint film forms a coating film with latex (I) in the paint film formation process.
) Since the coating film is formed while filling the gaps between the particles, the M
This is thought to be because the FT (minimum film formation temperature) does not appear, making it possible to form a coating film with uniform characteristics.

In addition, the resin contained in the latex constituting the coating material of the present invention has a hydroxyalkyl ester group as a crosslinking reactive group, and the water-soluble resin has an N-alkoxymethyl group or a crosslinking reactive group as a crosslinking reactive group. Furthermore, since it contains a hydroxyalkyl ester group, it is possible to easily form a tight crosslink between the two during the baking process of the coating film, which improves the mechanical properties of the resulting coating film, such as chemical resistance, water resistance, boiling water resistance,
Various coating properties such as 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 (11) is in the range of 80/20 to 30/70, and the ratio of water-soluble resin is 20/20 to 30/70.
If the coating material is less than M in the coating film formation process,
This is preferable because FT appears and it becomes extremely difficult to form a coating film with uniform properties.On the other hand, if the proportion of water-soluble resin used exceeds 70% by weight, the coating material may sag or sag during the coating film forming process. This is undesirable because coating defects such as wrinkles are likely to occur and the properties of the resulting coating film, such as alkali resistance, acid resistance, solvent resistance, and stain resistance, are rapidly reduced.

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 hole, and coating films formed from coating materials containing less than 5% by weight of these condensation products. is undesirable because its mechanical and chemical properties deteriorate; on the other hand, a coating film formed from a coating material containing more than 40% by weight of this condensation product deteriorates its flexibility, This is not preferable because mechanical coating film properties such as micro-impact resistance, acid resistance, water resistance, boiling water resistance, and other properties 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 water-soluble Jugetsu@Shun using a ball mill, third mill, three-roll mill, etc., and then this pigment paste is prepared. It is preferable to use a method in which a latex thermosetting formaldehyde resin and, if necessary, a water-soluble resin are added and mixed.

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

The coating material composition of the present invention is preferably used after adjusting its pH value to a range of 7 to 11, preferably 8 to 10.

In addition, the coating film formed from this coating material is heated to a temperature of 100 to 300℃.
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 can also be applied to spray coating methods, flaking printing methods, curtain flow coating methods, which have been conventionally used as coating methods for organic solvent-based coating materials.
It can be easily coated by methods such as electrostatic coating, and various objects such as metal, asbestos, wood, stone, textiles, and leather paper can be coated.

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. , to best demonstrate 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 tube, and inert gas inlet. (Levenol Wz: manufactured by Kao Atlas Co., Ltd.) 4.0 parts was added and nitrogen gas was blown in for 15 minutes to deoxidize.

Next, the internal temperature was heated to 60°C, and then 4.0 parts of the surfactant aqueous solution, 0.23 parts of ammonium persulfate, and 0.15 parts of acidic sodium sulfite were added to 15 parts of deionized water.
Styrene 42 parts (42.2 mol%) Ethyl acrylate 43 parts (44.9 mol%) 2-hydroxyethene 13 parts (10.5 mol%) Methacrylic acid 2 (2.4 mol %) was added dropwise from separate dropping funnels over 2 hours while maintaining the internal temperature at 60°C±1°C.

When the reaction was completed by keeping the same temperature for 3 hours after dropping, the solid content was 41.5%, pH was 2.47, and viscosity was 63 cps.
Measured with CB type viscometer, rotation speed 60 rpm, 20°C)
B-dimethylaminoethanol was added to this latex to adjust the pH to 9.0 to obtain latex (L-1).

(1-2) Production of water-soluble resin In a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer, 39 parts (40.7 mol%) of styrene, 39 parts (42.3 mol%) of ethyl acrylate, and 10 parts (6.9 mol%) lyacrylamide 2-hydroxye 5 parts (4.2 mol%) methyl methacrylate toitaconic acid 7 parts (5.8 mol%) Methyl cellosolve 66.7 parts n-octermel 3.0 parts Add 0.5 part of captan azobisisobutyl ronitrile, heat from room temperature to 75°C under stirring for 2 hours, and then keep at 75°C for 6 hours.

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 liquid temperature was raised to 85°C and kept at 85°C for 4 hours to complete the polymerization.

The obtained resin solution had a solid content of 60.2%, an acid value of 31.5,
The Gardner bubble viscosity was z4.

9.6 parts of β-dimethylaminoethanol was added to 172.6 parts of this m-lipid solution, followed by 89 parts of deionized water to obtain a water-soluble resin (W-1) with a solid content of 39.7%.

(1-3) Preparation method of pigment paste (P-1) for production of pigment coating composition> Titanium oxide 150 parts 25% aqueous solution of dispersant 6 parts antifoaming agent
0.3 parts deionized water
The 46-part product was linearized in a ball mill for 2 days to obtain a pigment paste (P-1).

<Preparation method of pigment paste (P-2)> Titanium oxide R-820 200 parts Water-soluble resin (W-1) 50 parts Antifoaming agent 0.4 parts Deionized water 60 parts The prepared product was mixed in a ball mill for 2 days. A pigment paste (p-2) was obtained.

<Enamel compounding method> Water-soluble resin (W-1), latex (L-1), and methoxymethylmelamine resin M in which some methylol groups remain are added to the above pigment pastes (P-1) and (P-2). The resins were mixed in a weight ratio as shown in Table 1 to prepare 10 kinds of enamels.

In this case, the mixing ratio of the aqueous resin dispersion and the melamine resin was 85/15 in resin weight ratio, and the pigment weight concentration was 45%.

Add β-dimethylaminoethanol to these enamels to pH = 9.0 to 9.5, then add deionized water if necessary and place in food cup #4.
The viscosity was adjusted to 20±2 seconds.

These diluted enamels were spray painted onto a zinc phosphate treated polished mild steel plate and then baked at 160°C for 20 minutes.

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

The coating films made in Experiment Nos. 1.2 and 3 were poor in gloss, corrosion resistance, and boiling water resistance.

On the other hand, as is clear from the results shown in Experiment Nos. 7, 8, 9 and 10, if these paints do not take a sufficiently long setting time, they tend to form wrinkles and the painting workability becomes poor.

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

Furthermore, the paints shown in Experiment Nos. 4 to 6, which are the coating materials of the present invention, do not easily flake even if the setting time is short, and the glossiness of the coated surface and overall coating performance are excellent.

Example 2 (2-1) Production of latex 21 parts (23.2 mol%) of styrene 21 parts (23.2 mol%) methyl Methacrylate - 21 parts (24.0 mol%) n-Butylacryle 48 parts (43.0 mol%) -2-hydroxyethe 8 parts (7.1 mol%) Methacrylate 2 parts (2.7 mol%) Emulsion polymerization was carried out using the method (mol%) to obtain a solid content of 40.6% and a pH of 2.45.
A latex with a viscosity of 61 cps was obtained. β-dimethylaminoethanol was added to the latex to adjust the pH to 9.0 to obtain a latex (L-2).

(2-2) Production of water-soluble resin from solution polymer Styrene 20 is exactly the same as the method for producing water-soluble resin shown in Example 1 (1-2) except that the following monomer mixture (B) is used. Parts (22.2 mol%) Methyl methacrylate - 20 parts (23.1 mol%) N-butyl acrylate 44 parts (39.6 mol%) -N-methoxymethyl 8 parts (S, O mol%) Acrylamide Itaconic acid 8 parts (7.1 mol%) n-octyl mer strength 30 parts Solution polymerization was carried out under butane conditions, solid content 60.3%, acid value 36
．． 4. A resin solution with a Gardner bubble viscosity of 2-21 was obtained.

To 172.6 parts of this resin solution, 10.9 parts of β-dimethylaminoethanol was added, followed by 89 parts of deionized water to obtain a water-soluble resin (W-2) with a solid content of 39.2%.

(2-3) Manufacture of pigment coating composition Pigment paste (pigment paste) (
P-3) was obtained.

Latex/water-soluble resin is 70/30 (resin weight ratio) using pigment paste (P-3), water-soluble resin (W-2), latex (L-2), and methoxymethyl melamine resin.
, (latex + water-soluble resin)/methoxymethylmelamine resin 85/15 (resin weight ratio), pigment weight concentration 40
Create enamel by blending in such a way that the
A paint was prepared by diluting with deionized water to a viscosity of 35 parts 2 seconds in Ford Cup #4.

This paint was applied to a 0.3 mm zinc phosphate treated galvanized steel plate using a bar coater, and 10 minutes after setting, 26
It was baked and dried at 0°C for 60 seconds.

The thickness of the resulting coating film was 18 μm, the gloss value (60° specular reflectance) was 86, and the coating surface was in good condition.

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 19 parts (20, 2 mol%) Methyl methacrylate 19 parts (21.1 mol%) N-butyl acrylate 44 parts (38.1 mol%) N-methoxymethylate 8 parts (7.7 mol%) Ruacrylamide methacrylic acid 10 parts ( 12.9 mol %) t-dodecylmel 3.0 parts Captan Emulsion polymerization was carried out to obtain a latex with a solid content of 40.6%, a pH of 2.25, and a viscosity of 53 cps.

After adding 153 parts of deionized water to 255 parts of the produced latex, 10.4 parts of β-dimethylaminoethanol was added and stirred at 40°C for a period of time to make the latex solubilized. 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.

Titanium oxide 200 parts Water-soluble resin (W-3) 80 parts Antifoaming agent 0.4 parts Deionized water 30 Part Pigment paste (P-4) Water-soluble resin (W- 3) Latex (L-2) Using methoxymethyl melamine resin, latex/water-soluble resin is 70/30 (resin weight ratio),
(Latex + water-soluble resin)/methoxymethylmelamine resin is 85/15 (resin weight ratio), pigment weight concentration is 4
0% enamel was blended and painted in the same manner as in Example 2 and baked and dried.

The resulting coating film had a film thickness of 17 μm and a gloss value of 83, showing a good coating surface condition, as well as 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 α・β-monoethylenically unsaturated carboxylic acid as monomer (3), copolymerizable monomer (4) whose homopolymer has a glass transition temperature of 20°C or higher, and other copolymerizable α・Using monomer (5), β-monoethylenically unsaturated compound is added to monomer (1) 5 to 5 in the presence of an emulsifier.
20 mol%, monomer (3) 1-6 mol%, monomer (4)
20 to 94 mol%, and monomer (5) 74 mol% or less, for a total of 100 mol%. I), monomer (2) or monomer (2) of 5 to 30 mol % in combination with monomer (1) and monomer (3) of 3 to 20 mol % Mol%, monomer (4) 20-92
mol% and monomer (5) at a ratio of 72 mol% or less to a total of 100 mol%. I
)/(II)-80/20 to 30/70 (resin weight ratio) *, S and water-soluble or water-dispersible thermosetting formaldehyde condensation product 'tkB) are mixed (A)
/(B)-9515 to 60/40 (resin weight ratio) aqueous thermosetting coating composition.