JPH09111180A - Aqueous paint composition - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide an aqueous coating composition having excellent dispersion stability and improved smoothness of the coated surface after coating. (In the formula, R ¹ is hydrogen or a methyl group, R ² and R ³ are hydrogen or an alkyl group having 1 to 4 carbon atoms, R ⁴ is hydrogen, an alkyl group having 1 to 4 carbon atoms, —CH ₂ C ₆ H ₅ ,
- (CH _{2) 2} SCH ₃ or _{- (CH 2) m -CO 2} H (m is 1
Or 2) and n is 0, 1 or 2.
The polymer, copolymer or graft polymer obtained from N- (meth) acryloylaminocarboxylic acid represented by

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to N-as a monomer.
The present invention relates to an aqueous paint composition using a resin for an aqueous paint containing a (carboxyalkyl group) -substituted (meth) acrylamide.

[0002]

2. Description of the Related Art Conventionally, a paint is diluted with an organic solvent from the viewpoint of ease of application and the like, but the organic solvent contained in the paint is volatilized at the time of coating and released to the atmosphere. This deteriorates the work environment and adversely affects the worker. In recent years, various solvent regulations have been implemented due to the influence of the diffusion of organic solvents in the atmosphere on the global environment.
Therefore, the importance of water-based paints has been increasing year by year as a measure to reduce organic solvents in paints.

However, although the boiling point of water is relatively low, it is difficult to evaporate, so that the coating viscosity of the coating is unlikely to increase, and sagging easily occurs. Further, since the surface tension of water is large, it wets the object to be coated. There are some problems with conventional water-based paints, such as poor performance, rough skin at the thin film portion, and easy cratering and craters, and there is a demand for water-based paints with excellent performance.

[0004]

DISCLOSURE OF THE INVENTION The object of the present invention is that conventional water-based paints are inferior to solvent-based paints, they are excellent in the smoothness and glossiness of the coating surface, and they are excellent in coating workability and coating quality. The problem is to obtain a water-based paint with good performance.

[0005]

Means for Solving the Problems As a result of intensive investigations by the present inventors to obtain a water-based coating having excellent performance in terms of coating workability and coating quality, it has been identified as a water-soluble polymer monomer in the water-based coating. The present invention has been completed by finding that a water-based paint having improved performance can be obtained by using a certain type of N-substituted (meth) acrylamides.

That is, the gist of the present invention is the following general formula (1):

[0007]

Embedded image (In the formula, R ¹ is hydrogen or a methyl group, R ² and R ³ are hydrogen or an alkyl group having 1 to 4 carbon atoms, R ⁴ is hydrogen, an alkyl group having 1 to 4 carbon atoms, —CH ₂ C ₆ H ₅ ,
- (CH _{2) 2} SCH ₃ or _{- (CH 2) m -CO 2} H (m is 1
Or 2) and n is 0, 1 or 2.
And a polymer, a copolymer, or a graft polymer obtained from N- (meth) acryloylaminocarboxylic acid.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. The compound represented by the general formula (1) in the present invention is an N-acryloyl or N-methacryloyl derivative of aminocarboxylic acid. These compounds are easily synthesized by known methods. For example, Japanese Patent Publication No. 63-4
In 1952, acryloyl chloride or methacryloyl chloride is added to various amino acids by Shotten-B.
A method of obtaining the corresponding N-acryloyl or N-methacryloyl amino acid by reacting by the Aumann method is disclosed. In addition, it is 7-4940
In Japanese Patent Publication No. 3, various aminonitriles are reacted with N-acryloyl chloride or N-methacryloyl chloride for amidation, and then the nitrile group is hydrolyzed to give the corresponding N-acryloyl or N-methacryloylaminocarboxylic acid. A method of obtaining is disclosed.

As the compound represented by the general formula (1),
Specifically, N-acryloylglycine, N-acryloylalanine, N-acryloylaspartic acid, N-acryloylglutamic acid, N-methacryloylglycine, N-methacryloylalanine, N-methacryloylaspartic acid, N-methacryloylglutamic acid, N
-Acryloyl-β-alanine, N-acryloyl-
2,2-dimethyl-β-alanine, N-methacryloyl-β-alanine, N-methacryloyl-2,2-dimethyl-β-alanine and the like can be exemplified, and preferably N-acryloyl aspartic acid is exemplified. You can

The compound represented by the general formula (1) may have an asymmetric carbon atom depending on the kind of the substituent, but in the present invention, either an optically active form or a racemic form may be used. Further, as the polymer obtained from the compound represented by the general formula (1) in the present invention, for example, the polymer represented by the formula (2) can be obtained by a generally known polymerization method.

[0011]

Embedded image (In the formula, R ¹ , R ² , R ³ , R ⁴ and n are the same as those in the general formula (1))

Further, various copolymers can be obtained by a generally known copolymerization method using the compound represented by the general formula (1) as a comonomer. Other monomers for copolymerization include acrylic acid and its esters, acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl acrylate, methacrylic acid and its esters, acrylamide, N-methyl acrylamide, N-methylol. Acrylamide, N-methoxymethyl acrylamide, acrylonitrile, vinyl acetate,
Styrene etc. can be illustrated.

Further, it is also preferable that the compound represented by the general formula (1) is grafted onto a reactive resin such as an epoxy resin. As the epoxy resin used, an aromatic epoxy resin is particularly suitable. As a method of grafting,
A general method of grafting can be applied, for example, by water-soluble by graft-polymerizing an epoxy resin and a compound represented by the formula (1) with a radical initiator such as benzoyl peroxide in an organic solvent. A graft polymerization composition of is obtained.

An aqueous paint is obtained by a generally known method using a polymer, a copolymer or a graft polymer obtained from the compound of the general formula (1) obtained by the above method as a main component or an accessory component. Can be done. In the present invention, the compounding amount of the polymer or copolymer obtained from the compound of the general formula (1) is not particularly limited, but is usually in the range of 0.5 to 50% by weight based on the coating solid content. It is blended so that.

As a typical polymerization method, a solvent in which the raw materials are soluble, for example, water, methanol, ethanol or a mixed solvent thereof is used, and benzoyl peroxide, azoisobutyronitrile or the like is added as a polymerization initiator, and the mixture is mixed at room temperature or Polymerize under heating conditions. The obtained polymer can be isolated by precipitating with a poor solvent such as acetone or by distilling off the reaction solvent.

In the composition of the present invention, the desired aqueous coating composition can be obtained according to the generally known formulation of the water-soluble resin in addition to the water-soluble resin obtained from the general formula (1). That is, an epoxy resin, a phenol resin, a melamine resin, a reactive resin such as an isocyanate resin, water, a cosolvent such as alcohols and glycols, a neutralizing agent, a cross-linking agent, a pigment, a dye, a wax, an anti-agglomeration agent, A leveling agent, a defoaming agent, etc. can be used as appropriate. 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 includes metals such as tin plate, aluminum, tin-free steel, iron, zinc, copper, galvanized steel sheet and alloy-plated steel sheet, and these metals are subjected to phosphate treatment or chromate treatment. Chemical conversion treated metal,
It can be applied to wood, plastics, concrete, etc. The thickness of the coating film may be appropriately selected depending on the application, but is usually 3 to 20 μm, and it can be applied by roll coating, spray coating, brush coating, roller coating, or the like. The drying conditions of the coating film may be appropriately selected depending on the composition to be used, and it is usually baked at 120 to 250 ° C. for about 10 to 30 seconds.

The coating composition obtained by the present invention has excellent dispersibility and can prepare a high-concentration resin solution, so that it is possible to reduce the amount of solvent used. Also, it has excellent viscosity characteristics and can obtain a smooth coated surface. Further, the obtained coated surface has high fastness and excellent scratch resistance. Hereinafter, embodiments of the present invention will be shown by examples, but the present invention is not limited to the following examples.

[0019]

【Example】

(Example 1) Production of N-acryloyl-L-aspartic acid 25.41 g of sodium hydroxide, L-aspartic acid 2
6.62 g was dissolved in water, and 19.0 g of acryloyl chloride was added dropwise thereto while keeping the temperature at 10 ° C or lower. After completion of dropping, the mixture was stirred at room temperature for 1 hour, and after completion of the reaction, it was neutralized with 61.9 g of concentrated hydrochloric acid. The reaction solution was extracted with ethyl acetate, and the solvent was distilled off to give 32.89 g of crystals of N-acryloyl-L-aspartic acid (yield 88
%).

(Example 2) Production of N-acryloyl-L-aspartic acid-containing copolymer solution Ethylene glycol mono was placed in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen inlet. 100 g of butyl ether was weighed. Next, N-acryloyl-L-aspartic acid 33.5 g and styrene 1
7.4 g, methyl methacrylate 61.3 g, 2-hydroxyethyl methacrylate 45.3 g, butyl acrylate 95.3 g, and benzoyl peroxide 2.8 g were weighed in a beaker and well stirred to prepare a monomer mixture solution. The temperature of the solvent in the flask was adjusted to 100 ° C., and the monomer mixture solution was added dropwise at this temperature from the dropping funnel over 2 hours. The reaction was further continued at 100 ° C. for 2 hours to complete the copolymerization reaction. Then, 26.5 g of melamine resin ("Uban 20SE" manufactured by Mitsui Toatsu Chemicals, Inc.) and 152 g of ion-exchanged water were added to obtain 531 g of a coating composition.

Example 3 In Example 2, acrylic acid 3 was used instead of N-acryloyl-L-aspartic acid.
The same operation was performed except that 5.2 g was added to obtain 533 g of a coating composition.

Example 4 A coating composition was prepared in the same manner as in Example 2 except that 17.2 g of acrylamide and 16.5 g of acrylic acid were added instead of N-acryloyl-L-aspartic acid. 532 g were obtained.

(Examples 5 to 7) The coating compositions obtained in Examples 2 to 4 were placed on a vertically placed steel plate in air at a temperature of 25 ° C and a humidity of 80% to obtain a dry film thickness of 20 microns. Spray painted. Then, the coated plate was baked at 130 ° C. for 30 minutes in a dryer to prepare a test plate. The workability (sagging) and the appearance (unevenness) of the obtained test plate were visually evaluated.

[0024]

[Table 1] ──────────────────── Working Examples Workability (Drop) Appearance (Mura) ─────────────── ───── 5 ○ ○ 6 × × 7 △ △ ────────────────────

[0025]

EFFECTS OF THE INVENTION An aqueous coating composition having excellent workability and appearance can be obtained.

Claims (2)

[Claims] (1) The following general formula (1): (In the formula, R ¹ is hydrogen or a methyl group, R ² and R ³ are hydrogen or an alkyl group having 1 to 4 carbon atoms, R ⁴ is hydrogen, an alkyl group having 1 to 4 carbon atoms, —CH ₂ C ₆ H ₅ ,
- (CH _{2) 2} SCH ₃ or _{- (CH 2) m -CO 2} H (m is 1
Or 2) and n is 0, 1 or 2.
An aqueous coating composition comprising a polymer, copolymer or graft polymer obtained from N- (meth) acryloylaminocarboxylic acid represented by 2. The coating composition according to claim 1, wherein in the general formula (1), R ¹ , R ² and R ³ are hydrogen, R ⁴ is —CH ₂ —CO ₂ H, and n is 0. Stuff.