JPH05202320A - Resin composition for matte electrodeposition coating - Google Patents

Abstract

PURPOSE:To provide the subject resin composition for an anionic matte electrodeposition coating, excellent in adhesion, matting properties, weather resistance, hardness, chemical resistance, etc. CONSTITUTION:An aqueous resin is synthesized by polymerizing 70 to 98wt.% mixture composed of (a) a polymerizable unsaturated acid monomer and (b) a polymerizable unsaturated monomer and 2 to 30wt.% (c) unsaturated polysiloxane compound. The resultant aqueous resin is blended with an amino resin (d).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for a matte electrodeposition coating having durability.

[0002]

2. Description of the Related Art Conventionally, various methods have been proposed as a method for matting the surface of an electrodeposition coating film. For example, a method in which an inorganic transparent pigment is mixed in an electrodeposition coating material, and the resin for coating and the inorganic transparent pigment are simultaneously deposited on the surface to be coated by electrodeposition coating to make it matte. A method in which an amino acid-curable anionic electrodeposition coating material contains an organic acid having a sulfonic acid group or a sulfuric acid ester group and is subjected to electrodeposition coating to make it matte (JP-A Nos. 52-137444 and 52-152). 137
No. 445, No. 52-137446, No. 56-
106977, Japanese Patent Laid-Open No. 3-139574). Then, a method of copolymerizing an unsaturated alkoxysilane compound with a resin for electrodeposition coating to obtain an amino resin curing type (Japanese Patent Publication No. 62-24519, JP-A-2-255871).
Japanese Patent Publication No. 3-160074).

However, among the above methods, the method of adding an inorganic transparent pigment has a large difference in specific gravity between the inorganic transparent pigments in the electrodeposition paint bath, so that process control such as stirring of the bath is indispensable for uniformization. It becomes difficult and it is difficult to stabilize the matting degree. In addition, in the method of adding an organic acid to the amino resin curable anionic electrodeposition coating, there is a difference in electrophoretic velocity and deposition characteristics between the coating resin and the acid, which makes it difficult to control the process in the bath of the electrodeposition coating. Becomes In addition, the resin composition for electrodeposition coating obtained by copolymerizing an unsaturated alkoxysilane compound does not have the above-mentioned problem, but this method has a three-dimensional siloxane bond due to a chemical reaction originated from hydrolysis of alkoxysilane. It aims at the matte effect due to diffuse reflection of light by making the coating a fine rough surface by utilizing the phenomenon that occurs in the resin particles for electrodeposition coating containing amino resin, but the gel content changes with time etc. Therefore, it is difficult to always obtain a uniform rough surface, and the management of the matte degree is a problem.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to solving the above-mentioned problems, and mainly comprises an acrylic-silicone graft copolymer obtained by copolymerizing an acrylic component and an unsaturated polysiloxane component. An object of the present invention is to provide an anionic electrodeposition coating material having matte properties and durability.
The present invention does not aim at the diffuse reflection effect of light by forming a rough surface on the coating surface of the conventional method, but the polysiloxane component (sea) and the acrylic resin component (matrix) which are microphase separated in the coating surface. The aim is to diffusely reflect light due to the difference in refractive index between and.

[0005]

The present invention provides a resin composition for anionic matte electrodeposition coating composition which can achieve the above objects. That is, the present invention is a polymerizable unsaturated acid monomer
An aqueous resin obtained by polymerizing 70 to 98% by weight of the total of (a) and the polymerizable unsaturated monomer (b) and 2 to 30% by weight of the unsaturated polysiloxane compound (c), and (d) The present invention relates to a resin composition for an anion matte electrodeposition coating composition comprising an amino resin.

The present invention will be described in more detail below. The present invention comprises a polymerizable unsaturated acid monomer (a), a polymerizable unsaturated monomer (b) and an unsaturated polysiloxane compound (c) in a hydrophilic solvent in the presence of a radical polymerization initiator. A stable fine particle dispersion is prepared by neutralizing a graft copolymer solution of a vinyl monomer and polysiloxane polymerized by heat polymerization with ammonia and / or amines, and then adding deionized water. The present invention relates to a resin composition for anionic matte electrodeposition coating composition, which is obtained by blending the amino resin (d) with the aqueous resin obtained as above.

It goes without saying that the component (a) used in the production of the graft copolymer is necessary in the step of making the resulting graft copolymer aqueous and in the anion electrodeposition coating process. Specific examples of the component (a) that can be used include (meth) acrylic acid, maleic acid, fumaric acid and itaconic acid, and these can be used alone or in combination. The component (a) that can be used is acid phosphooxyethyl.
(Meth) acrylate, acid phosphooxypropyl
Unsaturated organic phosphoric acids such as (meth) acrylate, acid phosphooxypolyoxyethylene glycol mono (meth) acrylate, acid phosphooxypolyoxypropylene glycol mono (meth) acrylate; vinyl sulfonic acid, 2-acrylamido-2-methyl Unsaturated organic sulfonic acids such as propane sulfonic acid and p-styrene sulfonic acid can be used, but (meth) acrylic acid is particularly preferable. Although the amount of the component (a) used varies depending on the properties of the monomer to be copolymerized and the reaction conditions, it is usually 15 to 150 in acid value, preferably 20 to 100.

Specific examples of the component (b) used for producing the graft copolymer include (meth) having 1 to 8 carbon atoms.
Acrylic esters such as methyl (meth) acrylate, ethyl, isopropyl, n-butyl, isobutyl,
2-ethylhexyl, 2-hydroxyethyl, hydroxypropyl; vinyl esters of alkane monocarboxylic acids having 1 to 12 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl-n-butyrate, vinyl versatate; unsaturated amides. Or an imide, such as (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, alkoxymethyl (meth) acrylamide, such as N-butoxymethyl (meth). Acrylamide, maleic imide, maleic diamide; vinyl aromatic monomers such as styrene,
Examples include P-methylstyrene.

In general, any monomer can be used as the monomer of the present invention as long as it has a radical-polymerizable monomer, and a halogen-containing vinyl compound such as vinyl chloride, vinylidene chloride or vinylidene fluoride; ethylene. , 1,3-
Examples thereof include mono- or di-olefins such as butadiene; α-β olefinically unsaturated acids such as esters of maleic acid and fumaric acid; and other (meth) acrylonitrile. These monomers can be used alone or in combination. The total amount of components (a) and (b) used is 70-
It is 98% by weight.

Next, the component (c) used in the graft polymerization is represented by the general formula [I]

[Chemical 1] [In the formula, R ₁ is hydrogen or a methyl group, and R ₂ is (CH ₂ ).
_l (wherein l is 0 or an integer of 1 to 6), R ₃ is the same or different and is a lower alkyl group, R ₄ is the same or different and is a halogen atom-substituted or unsubstituted alkyl group or phenyl group, A represents an ester or amide bond, and n is 17 to 270], and the lower alkyl group is, for example, methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl. , Carbon number such as hexyl group
-6 linear or branched alkyl groups.
The halogen atom-substituted alkyl group is a halogenated version of the above alkyl group, for example, chloromethyl, bromomethyl, trifluoromethyl, 2-chloroethyl, 3-chloropropyl, 3-bromopropyl, 3,
Examples include 3,3-trifluoropropyl and 1,1,2,2-tetrahydroperfluorooctyl groups. Further, as the halogen atom, a fluorine atom, a chlorine atom, a bromine atom,
Iodine atoms are included. The amount used is 2 to 30% by weight. When the amount used is less than 2% by weight, there is almost no matting effect due to the copolymerization of the compound, and when it exceeds 30% by weight, the components (a) and (b) are Not only is it difficult to copolymerize with the components, but it is uneconomical. The molecular weight of the component (c) is preferably 1,500 to 20,000, more preferably 2,000 to 15,000. Molecular weight is 1,5
If it is less than 00, there is almost no matting effect, and conversely it is 20,0.
If it exceeds 00, copolymerization becomes difficult.

Specific examples of the hydrophilic solvent used for the graft copolymerization include monoalcohols having 1 to 4 carbon atoms, such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol,
Isobutyl alcohol and t-butyl alcohol; ethylene glycol and its derivatives such as ethylene glycol monomethyl ether, monomethyl ether acetate, monoethyl ether, diethyl ether, monoethyl ether acetate, monoisopropyl ether,
Monobutyl ether, diethyl ether, monoethyl ether acetate, monoisopropyl ether, monobutyl ether acetate; diethylene glycol and its derivatives, for example, diethylene glycol monomethyl ether, monoethyl ether, monoethyl ether acetate, mono-n-butyl ether, mono-t-butyl ether. , Dimethyl ether, methyl ethyl ether,
Diethyl ether monoacetate; triethylene glycol and its derivatives, such as triethylene glycol monomethyl ether, monoethyl ether; propylene glycol and its derivatives, such as propylene glycol monomethyl ether, monoethyl ether, mono-
n-butyl ether, mono-t-butyl ether, methyl ether acetate; dipropylene glycol and its derivatives, such as dipropylene glycol monomethyl ether, monoethyl ether; tripropylene glycol and its derivatives, such as tripropylene glycol monomethyl ether; glycerin and Derivatives thereof, such as glycerin monoacetate; trimethylene glycol and its derivatives, such as 1-butoxy-ethoxypropanol, 3,3-dimethyl-3-methoxypropanol; butanediol and its derivatives, such as 3-methoxybutanol, 3-methyl. -3-Methoxybutanol, 3-methoxybutyl acetate, 3-methyl-3-
Methoxybutyl acetate, 3-methyl-1,3-butanediol; acetylene glycol derivatives, such as 2,
4,7,9-Tetramethyl-5-decyne-4,7-diol and its ethylene oxide adduct, 2,6-dimethyl-4-octyne-3,6-diol; other dioxane, 1,5-pentanediol , Hexylene glycol, trimethylolpropane, 1,2,6-hexanetriol, low molecular weight polyethylene glycol, etc. are generally mentioned, but in general, monoalkyl ethers of ethylene glycol or propylene glycol and those with monoalcohols having 4 or less carbon atoms. Combined use is preferred. These solvents can be used alone or in combination.

The polymerization initiator used in the graft copolymerization reaction may be a peroxide-type and / or azo-type radical polymerization initiator, and specifically, a peroxide-type, for example, a ketone such as methyl ethyl ketone peroxide and methyl isobutyl ketone peroxide. Peroxide; lauroyl peroxide, benzoyl peroxide, p-
Diacyl peroxides such as chlorobenzoyl peroxide; 2,4,4-trimethylpentyl-2-hydroperoxide, cumene hydroperoxide,
Hydroperoxides such as t-butyl hydroperoxide; Dialkyl peroxides such as dicumyl peroxide and di-t-butyl peroxide; Butyl-4,4-di (t-butylperoxy) pentoate, ethyl-3, Examples include peroxyketals such as 3-di (t-amylperoxy) butyrate; alkyl peresters; percarbonates. In the azo system, for example, 2,2'-azobisisobutyronitrile, 1,1 '
-Azobis (cyclohexane-1-carbonitrile) and other azonitriles; 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] Examples include azoamidine. It should be noted that these radical polymerization initiators may be used in combination with a reducing agent such as an organic amine to form a redox system.

The neutralizing agent for the polymerized graft copolymer solution is ammonia and / or amines. Specific examples of amines that can be used include alkylamines such as diethylamine, triethylamine, diisopropylamine and trimethylamine; Examples include alkanolamines such as diethanolamine and triethanolamine; alkylalkanolamines such as dimethylaminoethanol. The amount of amines used varies depending on the concentration (acid value) and type of the polymerizable unsaturated acid monomer used, but it is usually 50 to 95 mol% with respect to the acid groups.

Next, a method for producing the graft copolymer will be described. Since the method for producing the graft copolymer of the present invention is a solution polymerization which is generally carried out, a known method can be adopted. That is, the method of charging the hydrophilic solvents of the components (a), (b) and (c) may be batch charging or divided charging, and the reaction temperature is usually 60 to 140 ° C.
The reaction time is about 4 to 12 hours. If necessary, various chain transfer agents such as octyl mercaptan, lauryl mercaptan, β-mercaptopropionic acid and octyl thioglycolate may be used for controlling the molecular weight. The polymerized graft copolymer solution is neutralized with ammonia and / or amines, and then deionized water is gradually added to form a stable aqueous fine particle dispersion.

Anion type matte electrodeposition coating composition is obtained by blending the aqueous fine particle dispersion thus obtained with amino resin (d) as a curing agent. Examples of the amino resin (d) used in the matte electrodeposition coating include melamine resin, urea resin, benzoguanamine resin, etc. which have been conventionally used, but alkoxymethyl melamine resin is particularly preferable, and methyl etherification type is particularly preferable. Alternatively, a mixed etherification type with an alcohol having 4 or less carbon atoms is preferable. However, the amino resin may be added to the aqueous fine particle dispersion before or after the addition of water to make it aqueous. The mixing ratio of the aqueous fine particle dispersion and the amino resin is usually in the range of 9: 1 to 3: 7 in terms of solid content weight ratio.

The composition for anionic matte electrodeposition coating composition of the present invention comprises Japanese Patent Application No. 3-338498 or Japanese Patent Application No. 3-3.
The anion electrodeposition coating resin obtained in No. 46384 can be blended and used. By blending it, it is possible to control the balance between the matte effect and smoothness of the surface.

[0017]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The "parts" in the examples and comparative examples are "parts by weight" unless otherwise specified.

Example 1 In a 500 ml four-necked flask equipped with a stirrer, heat exchanger and thermometer, ethylene glycol monomethyl ether 2 was added.
6 parts, butyl acrylate 35 parts, methyl methacrylate 3
5 parts, 10 parts of 2-hydroxyethyl methacrylate, 10 parts of methacrylic acid, and silaplane FM-0725
[In the general formula [I], R ₁ , R ₃ , and R ₄ are methyl groups, R ₂ is a propylene group, A is an ester bond, and n is methacryloyloxypropyl polydimethyl represented by about 131 (molecular weight of about 10,000). Siloxane: product of Chisso Co., Ltd.] 10 parts were charged, and azobisisobutyronitrile 0.7 was added with stirring.
The parts are warmed after dissolution. When the solution temperature reached around 80 ° C. due to heating, a rapid reaction occurred, so the solution was cooled. After 2 hours and 4 hours of reaction at about 90 ° C., 15.5 parts of an ethylene glycol monomethyl ether solution containing 0.5 part of azobisisobutyronitrile were added half by half. After reacting for another 2 hours, the mixture was cooled to 60 ° C. and neutralized with 9.4 parts of triethylamine. Then, as a curing agent, an alkoxymethyl melamine resin [NICALAC MX-4
0: Sanwa Chemical Co., Ltd.] 40 parts and a solution consisting of 10 parts of ethylene glycol monoethyl ether was added, and then 260 parts of deionized water was gradually added to make the solution water-soluble to obtain a stable fine particle dispersion. Various properties of this fine particle dispersion are shown in Table 1.

Examples 2 to 4 The same reaction apparatus as in Example 1 was used and the reaction method was adopted, except that the formulation shown in Table 1 was followed. Various properties of the obtained fine particle dispersion are shown in Table 1.

Comparative Example 1 The procedure of Examples 2 to 4 was repeated, except that the formulation shown in Table 1 was followed. The results are shown in Table 1.

[0021]

[Table 1]

Next, the anion electrodeposition coating of the fine particle dispersions obtained in Examples 1 to 4 and Comparative Example 1 was carried out by diluting with the deionized water so that the concentration of the fine particle dispersion was 10%. It was The results of the anionic electrodeposition coating are shown in Table 2.

The objects to be coated, the conditions for electrodeposition coating, and the method for evaluating the coating film performance used were as follows.

A) Aluminum plate: JIS H4.00
0 (A1050P) 1.5 × 35 × 70 mm b) Anodizing: ・ Immersion in 10% NaOH aqueous solution for 2 minutes / 60 ° C., followed by deionized water cleaning ・ 15% HNO ₃ aqueous solution for 30 seconds / 25 ° C. Ionized water washing ・ 30% / 15% H ₂ SO ₄ aqueous solution at 1 A / dm ² current
After energizing at 30 ° C, washing with deionized water c) Electrodeposition coating: voltage 150 V, 2 minutes / 25 ° C, distance between electrodes 150 mm d) Film thickness: using a film thickness meter (Isoscope MP2, manufactured by Helmto Fisher) Measurement e) Smoothness: Visual observation of the appearance of the coating film after painting
Checking irregularities and pinholes f) Adhesiveness: Put 1 mm interval goggles (10 × 10) on the coated surface, attach cellophane tape and then peel off, and evaluate by the number of remaining coatings) Gloss: Gloss meter [Digital variable angle gloss meter UGV-5D,
Suga Test Instruments Co., Ltd.] is used to measure 60-degree specular gloss. H) Weather resistance: Gloss retention rate (%) after 1000 hours of sunshine weatherometer Li) Pencil hardness: "Mitsubishi Uni" (Mitsubishi Pencil ( [Products] to evaluate the hardness until the coating film is scratched.)) Alkali resistance: The coating film was applied to a 5% NaCO ₃ aqueous solution to give 24 coatings.
Observing the state after immersion for 20 hours at 20 ° C) Acid resistance: Coating film in 5% H ₂ SO ₄ aqueous solution for 24 hours / 2
Observe the condition after soaking at 0 ℃

[0025]

[Table 2]

[0026]

INDUSTRIAL APPLICABILITY The resin composition of the present invention is useful as a durable anionic matte electrodeposition coating composition.

Claims (1)

[Claims] 1. The total amount of the polymerizable unsaturated acid monomer (a) and the polymerizable unsaturated monomer (b) is 70 to 98% by weight and 2 to 30% by weight of the unsaturated polysiloxane compound (c). An anionic matte electrodeposition coating resin composition comprising an aqueous resin obtained by polymerizing a.