JPS5947270A - Resin composition for matte electrodeposition coating - Google Patents

Abstract

PURPOSE:To provide a resin compsn. which makes it possible to carry out uniform matte electrodeposition coating on the surfaces of metal goods, containing a specified alpha,beta-ethylenically unsaturated carboxylic acid resin and an alkoxylated methylolmelamine as film-forming components. CONSTITUTION:5-95pts.wt. alpha,beta-ethylenically unsaturated carboxylic acid resin having a second-order transition point of 50 deg.C or above, such as acrylic (co) polymer having an acid value of 10-200, 95-5pts.wt. alkoxylated methylolmelamine such as methoxy/butoxy-mixed methylolmelamine (MX-40, a product of Sanwa Chemical K.K.) and an acid such as p-toluenesulfonic acid are mixed together in an org. solvent such as alcohol or Cellosolve with stirring to obtain a resin compsn. for matte electrodeposition coating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition for matte electrodeposition coating that forms a uniform matte electrodeposition coating film by electrodeposition coating.

Conventionally, many methods have been proposed for obtaining a matte electrodeposited coating film. For example, (1) a method of treating the electrodeposition coating with an alcohol solution or an alcohol-containing aqueous solution (see Japanese Patent Publication No. 46-22351); (2) a method of treating the electrodeposition coating with hot water containing or without acid before baking; or a method of treating with heated steam (see Japanese Patent Publication No. 47-51927), (3) a method of cleaning the electrodeposited coating with a cationic surfactant (see Japanese Patent Publication No. 48-4447), (4) A method of treating the electrodeposited coating before baking with an aqueous solution of an organic or inorganic acid (see Publication Nos. 1973-11!+7444-157446), (5)
A method in which the electrodeposition coating film is washed and then treated with an aqueous salt solution (see Japanese Patent Application Laid-Open No. 56-9592), a method in which the electrodeposition coating film is formed and then treated with chemicals, or ( 6) A method of electrodeposition coating by dispersing a matting agent in the electrodeposition paint (Japanese Patent Laid-Open No. 5
6-16569) etc. are known.

However, the method of treating the coating film with chemicals etc. after forming the electrodeposited coating film does not produce a sufficient matting effect, and the degree of matting changes with changes in the condition of the treatment solution, resulting in uniform matting. There is a problem that a stable coating film cannot be obtained. Furthermore, since this method adds one step to the conventional electrodeposition coating process, there is the problem of reduced work efficiency, and for these reasons, it has not yet been implemented on a practical scale. is the current situation.

However, the method of blending a matting agent into the paint to make the coating film matte has been practiced for many years in coating methods other than electrodeposition coating.

However, it is difficult to utilize this method (4) in electrodeposition coating. For example, when using an electrodeposition paint in which fine silica powder is dispersed as a matting agent, the fine silica powder tends to settle, resulting in a significant difference in the degree of matting between the top and bottom surfaces of the object being coated. , there was a problem of making the paint unstable.

On the other hand, it is known from the above (6) to add a solvent-insoluble particulate polymerization reaction product to a paint as a matting agent. This method has the advantage of eliminating the need for conventional mechanical pulverization processes such as crushing or dispersing the matting agent. The tendency of the reaction products to settle is unavoidable, so that the problem still remains that uniform matte coatings cannot be obtained.

The present inventors have developed a technique that differs from these known techniques, in that they can achieve a glossy finish by simply performing ordinary electrodeposition coating without dispersing a matting agent or treating the electrodeposition coating with chemicals. As a result of research into a resin composition for matte electrocoating that can form an electrostatic coating, the present invention (5) was completed.

That is, an object of the present invention is to provide a resin composition for matte electrodeposition coating, which forms a matte electrodeposition coating film having a uniform and unique texture when used as an electrodeposition coating.

To summarize the present invention, the present invention provides that the resin composition comprises (a)
α,β-ethylenically unsaturated polycarboxylic acid resin having a secondary transition point of 50° C. or higher; and (b) an alkoxylated methylolmelamine in which at least a portion of the methylol group is alkoxylated with a lower alcohol as a coating film-forming component; The present invention relates to a resin composition for matte electrodeposition coating, which is a composition containing as an active ingredient a product obtained by mixing component @) and component (tl).

The unique features of the present invention will be explained in detail. The α,β-ethylenically unsaturated polycarboxylic acid resin used in the present invention includes α,
It is required that it be obtained by reacting a β-ethylenically unsaturated carboxylic acid with a copolymerizable monomer, and that its secondary transition point is 50° C. or higher.

(g) In the present invention, the secondary transition point of α,β-ethylenically unsaturated polycarboxylic acid resin is specified as 50°C or higher.The reason is that when electrodeposition coating is applied, the deposited resin coating film is heated and dried. This is because the coating film surface is prevented from becoming flat due to thermal melting of the resin, and the unevenness of the coating film during electrodeposition is maintained as it is, resulting in a matte appearance.

In conventional electrodeposition coating, the aim was to obtain excellent coating film gloss, so the secondary transition point of α,β-ethylenically unsaturated polycarboxylic acid resin used in electrodeposition paint is usually 10 to 10. A temperature range of 35°C is used. Therefore, if the secondary transition point is less than 50° C., the gloss of the electrodeposition coating film tends to improve, which is not desirable as a resin composition intended for forming a matte electrodeposition coating film of the present invention.

Suitable α,β-ethylenically unsaturated polycarboxylic acid resins have an acid value of about 10 to 200. acid value is 10
If the acid value is less than 200, the acid value cannot be sufficiently dispersed in water and is unstable when used as a paint (7). Undesirable because the coating film has poor rolling properties.

Examples of suitable α,β-ethylenically unsaturated carboxylic acids include acrylic acid, α-chloroacrylic acid, methacrylic acid, itaconic acid, maleic anhydride, maleic acid, fumaric acid, crotonic acid, citraconic acid and mezaconic acid. alone or in mixtures or their functional derivatives having at least one carboxyl group, such as partial esters or amides of unsaturated polymerizable di- or poly-carboxylic acids.

Examples of monomers copolymerizable with pseudo-β-ethylenically unsaturated carboxylic acids include esters of α,β-ethylenically unsaturated carboxylic acids, such as alkyl and oxyalkyl esters, and derivatives such as amides; Saturated polyester or polyester
There are derivatives of carboxylic acids that do not contain free carboxyl groups, such as diethyl maleate and dibutyl maleate.

(8) Other polymerizable vinyl or vinylidene compounds such as styrene, alkylstyrenes and acrylonitrile can also be used.

Examples of alkyl esters of α,β-ethylenically unsaturated carboxylic acids include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,
n-propyl acrylate), n-propyl methacrylate, inpropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate,
Acrylamide, diethylene glycol monoacrylate, diethylene glycol methacrylate, methacrylamide, methylol acrylamide, methylol methacrylamide, diacetone acrylamide, diacetone methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, hexyl acrylate, 2-ethylhexyl methacrylate, heptyl These include acrylate and heptyl methacrylate (9). Also, hydroxyalkyl or alkoxyalkyl esters of α,β-ethylenically unsaturated carboxylic acids and α
, β-ethylenically unsaturated carboxylic acid amide or α, β-
Examples of derivatives of ethylenically unsaturated carboxylic acid amide include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3
-hydroxypropyl acrylate and 3-hydroxypropyl methacrylamide.

On the other hand, the alkoxylated methylol melamine may be one in which at least a portion of the methylol group is alkoxylated with a lower alcohol. Low 7 /l/ :l-
One or more of the following are used: alcohol, methyl alcohol, ethyl alcohol, flobyl alcohol, isopropyl alcohol, and hyphthylalnyl.

The above α and β in the resin composition for matte electrodeposition coating of the present invention
- The composition ratio of unsaturated polycarboxylic acid resin and alkoxylated methylol melamine is (10) α,β-ethylenically unsaturated polycarboxylic acid resin 5 to 95
It can be used in a range of 95 to 5 parts by weight of the alkoxylated methylolmelamine.

The resin composition of the present invention can be produced, for example, by the following method.

In a container equipped with a stirring plate thermometer, a) a secondary transition point of 5
After adding the α,β-ethylenically unsaturated polycarboxylic acid resin at 0° C. or higher, b) alkoxylated methylolmelamine, and an organic solvent, the mixture is stirred and thoroughly mixed.

Examples of organic solvents include methanol, ethanol, n
-7' lovanol, isopropyl alcohol, n-butanol, isobutanol, 8ele-butanol, t-
Alcohols such as butanol, pentanol, etc., cellosolves such as butyl cellosolve, ethyl cellosolve, isoprobyl cellosolve, butyl cellosolve, 8eC-butyl cellosolve, etc. are used.

In the resin composition of the present invention, desirable results can be obtained when an acid is blended. This is presumed to be because the acid acts as a crosslinking catalyst during heating and baking of the electrodeposited (11) coating.

Acids that can be blended into the resin composition in the present invention include organic acids and/or inorganic acids. Examples of organic acids include formic acid, acetic acid, oxalic acid, and sulfonic acid compounds, while examples of inorganic acids include sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid.

In the present invention, at least one type of organic acid or inorganic acid, or a mixture of an organic acid and an inorganic acid can be used.

In the present invention, it is desirable to use a sulfonic acid compound because it exhibits particularly excellent effects. Sulfonic acid compounds include aliphatic sulfonic acids and aromatic sulfonic acids.

Examples of aliphatic sulfonic acids include alkanesulfonic acids such as methanesulfonic acid and ethanesulfonic acid; examples of aromatic sulfonic acids include m-nonylbenzenesulfonic acid, p-f sylbenzenesulfonic acid, and p-undecylbenzenesulfonic acid. A(12) alkylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, diakylnaphthalenesulfonic acid, dialkylnaphthalenesulfonic acid, such as p-dodecylbenzenesulfonic acid and p-)luenesulfonic acid;
Dialkylnaphthalenesulfonic acids or disulfonic acids such as dioctylnaphthalene disulfonic acid and didecylnaphthalene disulfonic acid are used.

The acid is preferably added at the time of mixing the resin composition, but it can also be added after mixing.

Further, in the present invention, a base can be added together with the acid or after mixing to neutralize the acid.

Furthermore, an acid salt obtained by neutralizing the acid with a base in advance can also be blended.

As the base for neutralizing the acid, conventional neutralizing agents such as ammonia, inorganic bases and organic nitrogen bases can be used, and organic nitrogen bases are particularly preferred. Furthermore, among the organic nitrogen bases, those that are sparingly soluble or insoluble in water are particularly desirable. Examples are long-chain alkyl amines or amines containing aralkyl groups.

(13) When using the resin composition of the present invention as a material for electrodeposition coating, after adding an organic amine and/or ammonia to make the α,β-ethylenically unsaturated polycarboxylic acid resin water-dispersible,
Dilute to an appropriate resin solids concentration before use. In that case, colorants and other additives commonly used in electrodeposition coating may be mixed and used.

When a conductive article is electrodeposited in the paint thus prepared, a uniform matte coating can be obtained regardless of the shape or size of the article.

The ammonia or organic amine used to make the α,β-ethylenically unsaturated polycarboxylic acid resin water-dispersible includes ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine. , diisopropylamine, triisopropylamine, monobutylamines, diptylamines and tributylamines, etc., monoethanolamine, jetanolamine (14), triethanolamine, monoisopropylamine, diisopropylamine, etc. alkylene polyamines such as ethylene diamine, propylene diamine, diethylene triamine and triethylene tetramine, alkylene imines such as ethylene imine and propylene imine etc. , piperazine, morpholine, pyrazine and pyridine.

The resin composition of the present invention can be applied directly on a conventional electrodeposition coating line using the same method, and there is no need to use a method using an electrodeposition paint containing a matting agent or a method in which the electrodeposition coating film is post-treated with chemicals. It has the advantage that a stable and uniform matte coating film, which is impossible to achieve, can be obtained at all times. (Particularly when the optimum formulation is used, the gloss value becomes very small.) Furthermore, the coating film obtained by electrodepositing the resin composition of the present invention has excellent adhesion to the object to be coated,
Some also have excellent coating properties such as acid resistance, alkali resistance, and boiling water resistance.

(15) Examples will be shown below to explain the present invention in more detail. However, the present invention is not limited thereto.

In addition, parts on each side mean parts by weight.

Production Example 1 [Synthesis of component (a)] In a reaction vessel equipped with a stirrer, a thermometer, and a reflux condenser, 8 parts of methacrylic acid, 10 parts of 2-ethylhexyl acrylate, 62 parts of methyl methacrylate, 2 -10 parts of hydroxyethyl methacrylate, 34 parts of butyl cellosolve, 30 parts of isopropyl alcohol, and 1.5 parts of azobisin butylonitrile were added and stirred at reflux temperature for 6 hours. The obtained α,β-ethylenically unsaturated polycarboxylic acid resin had a secondary transition point of 60° C. and an acid value of 52.

Production Example 2 (Comparative Example) The same method as in Production Example 1 was repeated except that the amounts used were changed to 42 parts of 2-ethylhexyl acrylate and 40 parts of methyl methacrylate, and α,β-ethylenically unsaturated Polycal (16) Bonic acid resin was obtained. This had a secondary transition point of 20.6°C and an acid value of 52.

Example 1 In a container equipped with a stirrer and a thermometer, 10 of the α,β-ethylenically unsaturated polycarbo/acid resin solution obtained in Production Example 1 was placed.
0 parts and methoxy/butoxy mixed methylolmelamine (
Product name: M! -40, manufactured by Tamayo Chemical Co., Ltd.) and stirred. After stirring for 12 hours, the mixing was completed to obtain a resin composition.

Example 2 In the method of Example 10, para-toluenesulfonic acid 0.
A resin composition was obtained in the same manner except that 2 parts were mixed and stirred for 1 hour.

Example 3 A resin composition (17) was prepared in the same manner as in Example 1, except that part of paradodecylbenzenesulfonic acid CLS and 2 parts of tri-n-butylamine a were blended and mixed by stirring for 1 hour. I got it.

Example 4 The same method as in Example 1 was repeated except that 05 parts of a salt obtained by neutralizing varadodecylbenzenesulfonic acid with tri-n-butylamine was added and mixed by stirring for 1 hour. A resin composition was obtained.

Example 5 In the method of Example 1, 0.3 part of varadodecylbenzenesulfonic acid was blended, and after stirring for 1 hour,
A resin composition was obtained in the same manner except that 2 parts of di-n-butylamine α was added and mixed by stirring for 2 hours.

Comparative example 1 In the method of Example 1, α obtained in Production Example 2.

Resin compositions were obtained in the same manner except that a β-ethylenically unsaturated polycarboxylic acid resin solution was used.

Application example (electrodeposition coating experiment example) Each of the resin compositions (18) obtained in Examples 1 to 5 and Comparative Example 1 was neutralized with triethylamine and diluted with deionized water to reduce the resin solid content. A 10% by weight electrodeposition paint was prepared.

An unsealed anodized aluminum extruded shape with inorganic electrolytic coloring (amber color) applied to each electrodeposition paint was immersed as an anode.
A stainless steel plate is provided as a counter electrode, and the voltage is 180 volts.
Direct current was applied for one minute. Next, after washing with water, it was heated and dried at 180° C. for 30 minutes. As a result, the gloss of the electrodeposited coating film obtained and the physical and chemical properties of the coating film were as shown in Table 1 below.

In addition, the coating film gloss is determined by 60° specular reflectance (J-K5Z-87
41) The hardness of the coating film was determined by the pencil scratch test (JIE
I H-8602) K), the alkali resistance of the coating film is
1% NaOH, 40 hour spot test (J Engineering 8 H-8
6f! According to 2), the acid resistance of the coating film is 5% H2F3
04. The boiling water resistance of the coating film was determined by a 24-hour spot test, by immersion at 100°C for 5 hours (J Engineering 5H-8602), and by a coating film adhesion test (T Engineering 5H-8602). Yes.

(19) (20) As is clear from the above results (Table 1), the resin composition for matte electrodeposition coating according to the present invention has a uniform and unique texture when used as an electrodeposition paint. A matte coating film can be formed.

Patent applicant Honey Kasei Co., Ltd. Agent Hiroshi Nakamoto Same as above, Akira Ii (21)

Claims (1)

[Scope of Claims] 1. The resin composition comprises (a) an α,β-ethylenically unsaturated polycarboxylic acid resin having a secondary transition point of 50°C or higher; and...)
The film-forming component is alkoxylated methylolmelane, in which at least a portion of the methylol groups are alkoxylated with a lower alcohol, and the product obtained by mixing components (a) and (kl) is contained as an active component. A resin composition for matte electrodeposition coating, characterized in that it is a composition. 2. The resin composition is a composition containing a product obtained by adding an inorganic acid and/or an organic acid during or after mixing components (a) and (1)) and mixing them. A resin composition for matte electrodeposition coating according to claim 1. (5) The resin composition is obtained by adding an inorganic acid and/or an organic acid and a base during or after mixing components (a) and (1)) and mixing them (1°). The resin composition for matte electrodeposition coating according to claim 1, which is a composition containing the following: tun The resin composition is prepared by adding a salt of an inorganic acid and/or an organic acid during or after mixing the components (a) and (b),
The resin composition for matte electrodeposition coating according to claim 1, which is a composition containing a product obtained by mixing them. 5. The resin composition is obtained by adding an inorganic acid and/or an organic acid during or after mixing components (a) and (1)), mixing them, and then neutralizing the nucleic acid with a base. The resin composition for matte electrodeposition coating according to claim 4, which is a composition containing a product including a salt of an inorganic acid and/or a salt of an organic acid. & The resin composition is prepared by adding organic amine and/or ammonia after mixing component (a) and component (b), and
, for matte electrodeposition coating according to any one of claims 1 to 5, which is a composition containing a product obtained by neutralizing a β-ethylenically unsaturated polycarboxylic acid resin. Resin set (2) Paraboloid. Z The matte electrodeposition coating according to any one of claims 1 to 6, wherein the ra) component is an α,β-ethylenically unsaturated polycarboxylic acid resin having an acid value of 10 to 200. Resin composition.