JP3177663B2 - Painting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a topcoat, for example, a method for applying a topcoat used for building exteriors, automobiles, industrial machines, steel furniture, household appliances, plastics and the like.

[0002]

2. Description of the Related Art A vinyl polymer containing a hydrolyzable silyl group (a silicon-containing group to which a hydrolyzable group is bonded) is cured at room temperature, and is used to cure concrete, glass, steel plate, aluminum and the like. It has been found that this resin has good adhesion to inorganic substances and excellent weather resistance, and has already been applied for a patent (JP-A-54-36395). However, this vinyl polymer is not always satisfactory in adhesion to organic substances, and contains a hydrolyzable silyl group for the purpose of imparting excellent weather resistance, acid resistance, etc. after applying an undercoat or an intermediate coating. When the vinyl polymer was overcoated, the adhesion between the coating films was sometimes insufficient.

[0003]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above problems, and as a result, have completed the present invention.

[0004] That is, the coating method of the present invention is characterized in that an undercoat or an intermediate coating which is at least one selected from the group consisting of an oil paint, a synthetic resin paint, a cellulose paint and a water-soluble paint is applied, (A) a vinyl resin having a main chain substantially composed of a vinyl polymer and having at least one silicon-containing group to which a hydrolyzable group is bonded (hereinafter, also referred to as a hydrolyzable silyl group) in one molecule; And (b) a method of applying an overcoat mainly containing a curable composition comprising a curing catalyst, wherein the undercoat or the intermediate paint comprises: (c) a main chain substantially consisting of a vinyl polymer. A vinyl resin having at least one hydrolyzable silyl group in one molecule and further containing a repeating unit derived from a vinyl monomer having a hydroxyl group as a copolymerization component; It is characterized by being included.

[0005] The curable composition for a top coating composition used in the present invention comprises, as a component (a), a main chain substantially consisting of a vinyl polymer, and at least one hydrolyzable silyl group per molecule. (Hereinafter, also referred to as a hydrolyzable silyl group-containing vinyl resin).

[0006] Since the main chain of the hydrolyzable silyl group-containing vinyl resin is substantially composed of a vinyl polymer, the cured product has excellent weather resistance, chemical resistance, etc., and can be obtained by changing the copolymer composition. A wide variety of resin designs from soft to hard are possible. In addition, since there is at least one, preferably two or more hydrolyzable silyl groups in one molecule, which are hydrolyzed into silanol groups in the presence of moisture, and further form siloxane bonds to be cured, the In the presence,
In addition to being able to cure at room temperature and producing chemically stable siloxane bonds, the weather resistance of the cured product,
Chemical resistance can be further improved.

[0007] The molecular weight of the hydrolyzable silyl group-containing vinyl resin is not particularly limited. However, from the viewpoints of workability, stability, appearance of the coating film (gloss value, visual evaluation), etc. Those having a molecular weight of about 2,000 to 80,000, particularly preferably about 3,000 to 25,000 are generally used.

The above-mentioned hydrolyzable silyl group-containing vinyl resin can be obtained, for example, by copolymerizing a vinyl monomer and a hydrolyzable silyl group-containing monomer. It may contain a urethane bond or a siloxane bond in the following ranges.

The vinyl monomer used for producing the hydrolyzable silyl group-containing vinyl resin which is the component (a) used in the present invention is not particularly limited. Specific examples thereof include, for example, methyl (meth) Acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-
Ethylhexyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, perfluorocyclohexyl (meth) acrylate, (meth ) Acrylonitrile, glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide, α-ethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N, N- Dimethylacrylamide, N-methylacrylamide, acryloylmorpholine, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acyl Rate, N- methylol (meth) acrylamide, Toagosei Chemical Industry Co., Ltd. Aronikusu M-5700, AS-6 is a Toagosei Chemical Industrial Co., Ltd. macromonomer, AN-6, AA-6, AB
-6, AK-5, Plac manufactured by Daicel Chemical Industries, Ltd.
cel FA-1, Placel FA-3, Pla
ccel FA-4, Placel FM-1, Pl
accel FM-4; a phosphate ester group which is a condensation product of a hydroxyalkyl ester of an α, β-ethylenically unsaturated carboxylic acid such as a hydroxyalkyl ester of (meth) acrylic acid and a phosphoric acid or a phosphoric acid ester Containing vinyl compound; aromatic hydrocarbon vinyl compound such as styrene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, 4-hydroxystyrene, vinyltoluene; unsaturated carboxylic acid such as maleic acid, fumaric acid, itaconic acid Acids, their salts (alkali metal salts, ammonium salts, amine salts, etc.), their acid anhydrides (maleic anhydride, etc.), or those having 1 carbon atom
Esters of unsaturated carboxylic acids such as diesters or half-esters with linear or branched alcohols of from 20 to 20; vinyl esters and allyl compounds such as vinyl acetate, vinyl propionate and diallyl phthalate; amino acids such as vinyl pyridine and aminoethyl vinyl ether Group-containing vinyl compounds; amide group-containing vinyl compounds such as itaconic acid diamide, crotonamide, maleic acid diamide, fumaric acid diamide, N-vinylpyrrolidone;
Hydroxyethyl vinyl ether, methyl vinyl ether, cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene, butadiene,
Other vinyl compounds such as isoprene, fluoroolefin maleimide, N-vinylimidazole, and vinyl sulfonic acid are exemplified. These vinyl monomers may be used alone or in combination of two or more.

Specific examples of the hydrolyzable silyl group-containing monomer include silane derivatives having an unsaturated bond in the molecule, for example,

Embedded image

Embedded image

Embedded image And a (meth) acrylate having an alkoxysilyl group at a terminal via a urethane bond or a siloxane bond. These hydrolyzable silyl group-containing monomers may be used alone or in combination of two or more.

The method for producing the copolymer of the hydrolyzable silyl group-containing monomer and the vinyl monomer is not particularly limited, and examples thereof include JP-A-54-36395 and JP-A-57-36395.
Nos. 36109 and 58-157810, and the solution polymerization method using an azo radical initiator such as azobisisobutyronitrile is particularly easy to handle. It is preferable from the point of view.

If necessary, for example, n-dodecyl mercaptan, t-dodecyl mercaptan, n-butyl mercaptan, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane,
γ-mercaptopropylmethyldimethoxysilane, γ-
Mercaptopropyl methyl diethoxy _{silane, (CH 3 O) 3 Si} -S-S-Si (OCH 3) 3, (CH 3 O) of _{3 Si-S 8 -Si (OCH} 3) 3 chain transfer agent such as 1 By using more than one species, the molecular weight can be adjusted. When a chain transfer agent having a hydrolyzable silyl group in the molecule, for example, γ-mercaptopropyltrimethoxysilane, is added to the monomer mixture solution and continuously added, hydrolysis to the terminal of the vinyl polymer occurs simultaneously with the action of controlling the molecular weight. This is useful because a reactive silyl group can be introduced.

Examples of the solvent used for the solution polymerization include:
For example, hydrocarbons such as toluene, xylene, n-hexane and cyclohexane; acetates such as ethyl acetate and butyl acetate; alcohols such as methanol, ethanol, isopropanol and n-butanol; ethyl cellosolve, butyl cellosolve, cellosolve acetate and the like Ethers: ketones such as methyl ethyl ketone, ethyl acetoacetate, acetylacetone, diacetone alcohol, methyl isobutyl ketone, and acetone, but are not limited thereto, and any non-reactive solvent can be used. .

Specific examples of the curing catalyst which is the component (b) used in the present invention include organic tin compounds such as dibutyltin dilaurate, dibutyltin dimaleate, dioctyltin dilaurate, dioctyltin dimaleate, and tin octylate; Acids, phosphoric acids or phosphates such as monomethyl phosphate, monoethyl phosphate, monobutyl phosphate, monooctyl phosphate, monodecyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate, didecyl phosphate; alkyl titanates; Tris (ethyl acetoacetate)
Organic aluminum compounds such as aluminum, tris (acetylacetonato) aluminum; organic zirconium compounds such as tetrabutylzirconate, tetrakis (acetylacetonato) zirconium, tetraisobutylzirconate, butoxytris (acetylacetonato) zirconium; Acid, adipic acid, azelaic acid, sebacic acid, itaconic acid, citric acid, succinic acid, phthalic acid, trimellitic acid, pyromellitic acid, acid anhydrides of these, acid compounds such as paratoluenesulfonic acid; hexylamine, dihexylamine Amines such as -2-ethylhexylamine, N, N-dimethyldodecylamine and dodecylamine; mixtures or reactants of these amines with acidic phosphate esters; alkalis such as sodium hydroxide and potassium hydroxide Such as a compound, and the like.

Among these curing catalysts, an organotin compound,
Acidic phosphates, mixtures or reactants of acidic phosphates and amines, saturated or unsaturated polycarboxylic acids or anhydrides thereof, reactive silicon compounds, organic titanate compounds, organic aluminum compounds, or mixtures thereof It has high activity and is preferable.

The amount of the curing catalyst to be added to 100 parts (parts by weight, hereinafter the same) of the hydrolyzable silyl group-containing vinyl resin is generally 0.01 to 20 parts, preferably 0.01 to 20 parts.
10 parts.

The curable composition for a top coat used in the present invention may or may not use a dehydrating agent. However, in order to ensure long-term stability and stability without any problem even when used repeatedly. , It is preferable to use one or more dehydrating agents.

Specific examples of the dehydrating agent include, for example, methyl orthoformate, ethyl orthoformate, methyl orthoacetate, ethyl orthoacetate, methyltrimethoxysilane, γ
-Hydrolysable ester compounds such as methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, methyl silicate and ethyl silicate. These hydrolyzable ester compounds may be added at any stage before, during, or after the polymerization of the vinyl resin having a hydrolyzable silyl group.

Component (c) added to the undercoat or intermediate coating (the main chain is substantially composed of a vinyl polymer,
Having at least one hydrolyzable silyl group per molecule,
Further, a vinyl resin containing a repeating unit derived from a vinyl monomer having a hydroxyl group as a copolymer component)
Overcoated to contain hydrolyzable silyl groups (a)
Reacts with components and improves adhesion. The component (c) contains a repeating unit derived from a vinyl monomer having a hydroxyl group as a copolymer component, and therefore has a high polarity and improves compatibility with an undercoat or intermediate coating.
In addition, the hydroxyl group in the copolymer component may react, and the component (c) has a strong affinity with the undercoat or the intermediate coating, thereby contributing to the improvement of the adhesion to the component (a).

The number average molecular weight of the component (c) is about 2,000 to 25,000 from the viewpoint of stability and adhesion.
Particularly preferably, it is 3,000 to 15,000.
To obtain the component (c), a hydrolyzable silyl group-containing monomer, a vinyl monomer, a polymerization method and a chain transfer described in the component (a), except that a vinyl monomer having a hydroxyl group is copolymerized as an essential component. Agents, solvents and dehydrating agents can be used.

Examples of the vinyl monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
-Hydroxyethyl vinyl ether, N-methylol (meth) acrylamide, Alonix 5700, 4-hydroxystyrene manufactured by Toa Gosei Chemical Industry Co., Ltd., HE-10, HE-20, HP- manufactured by Nippon Shokubai Chemical Industry Co., Ltd.
No. 10 and HP-20 (both terminally hydroxylated acrylate oligomers), Blemmer PP series (polypropylene glycol methacrylate), Blemmer PE series (polyethylene glycol monomethacrylate), Blemmer PEP, manufactured by NOF Corporation
Series (polyethylene glycol polypropylene glycol methacrylate), Blemmer AP-400 (polypropylene glycol monoacrylate), Blemmer AE-350 (polyethylene glycol monoacrylate), Blemmer NKH-5050 (polypropylene glycol polytrimethylene monoacrylate) and Blemmer GLM (glycerol monoacrylate) Methacrylate), ε-caprolactone-modified hydroxyalkyl vinyl monomers obtained by reacting a hydroxyl group-containing vinyl compound with ε-caprolactone, and the like. In particular, when an ε-caprolactone-modified hydroxyalkylvinyl-based monomer is used, the obtained component (c) has a high polarity since it has a polyester moiety, and has good compatibility with an undercoat or intermediate coating. Also, because the hydroxyl group is separated from the main chain via the polyester site,
The expression of the effect of the hydroxyl group is effective.

Representative examples of the ε-caprolactone-modified hydroxyalkyl vinyl monomer include, for example, those represented by the formula

Embedded image (Wherein, R represents H or CH ₃ , and n represents an integer of 1 or more) Placel FA-1 (R = H, n =
1), Placel FA-3 (R = H, n = 3),
Placel FA-4 (R = H, n = 4), Pla
_{ccel FM-1 (R = CH} 3, n = 1) and Pl
_{accel FM-4 (R = CH} 3, n = 4), UCC
TONE M-100 (R = H, n = 2) and TONE M-201 (R = CH ₃ , n = 1) manufactured by K.K.

[0023] These hydroxyl group-containing vinyl monomers include
Seeds may be used, or two or more kinds may be used in combination.

The hydroxyl value of the component (c) is 0.5 to 100 mgKOH / g, preferably 1 to 50 mgKOH / g, based on the resin solid content of the component (c). 0.5mg KO
If it is less than H / g, the adhesion is reduced, and 100 mgKOH / g
If it exceeds, the stability decreases.

The amount of the component (c) to be added to the undercoat or intermediate coating is determined by the amount of the base material of the undercoat or intermediate coating.
The resin solid content is 0.5 to 50 parts, preferably 1 to 30 parts, based on 0 part. If it is less than 0.5 part, there is no effect of improving the adhesion, and if it exceeds 50 parts, the storage stability decreases.

The undercoat or intermediate paint to which the component (c) is added includes oil paints, synthetic resin paints, cellulose paints, and water-soluble paints. It is particularly effective for synthetic resin coatings, and is particularly effective for polyurethane coatings, thermosetting acrylic resin coatings, and aminoalkyd resin coatings. This is presumably because the hydroxyl group contained in the component (c) reacts with an isocyanate group of the polyurethane coating, melamine of the aminoalkyd resin coating, a thermosetting acrylic resin coating, and the like.

[0027]

Next, the present invention will be described based on embodiments.

Synthesis Example 1 Component (a) (hydrolyzable silyl)
Xylene was charged into a reactor equipped with a stirrer, a thermometer, a nitrogen inlet tube, a dropping funnel and a cooling tube for synthesizing a group-containing vinyl resin), and
Heated to 0 ° C. In this reactor, 375 g of n-butyl acrylate, 535 g of methyl methacrylate, 80 g of γ-methacryloxypropyltrimethoxysilane, 10 g of acrylamide and 9 g of azobisisobutyronitrile
Was continuously added over 3 hours. After completion of the addition, a separately prepared solution of 1 g of azobisisobutyronitrile and 70 g of toluene was added over 1 hour, and after 1 hour, polymerization was carried out to obtain a hydrolyzable silyl group-containing vinyl resin (a). I got

The obtained resin solution was diluted with xylene to obtain 5
It was adjusted to 0% to obtain a colorless transparent liquid having a viscosity of 800 cp (23 ° C.). The number average molecular weight of the obtained resin measured by GPC (gel permeation chromatography) is about 15,000.
It was 0.

Synthesis Example 2 Component (c) (Hydroxy group-containing
A non-volatile content of 5 was obtained in the same manner as in Synthesis Example 1 except that the use ratios of the synthetic monomer and the initiator of the decomposable silyl group-containing vinyl resin were changed as shown below.
0%, number average molecular weight 4,000, hydroxyl value 8.6 mgK
An OH / g hydroxyl group-containing hydrolyzable silyl group-containing vinyl resin (c) was obtained.

N-butyl acrylate 420 g methyl methacrylate 360 g γ-methacryloxypropyltrimethoxysilane 150 g Placel FA-3 70 g azobisisobutyronitrile 55 g

Example 1 and Comparative Example 1 An iron plate was ground with ^# 240 abrasive paper and degreased with xylene. The iron plate was spray-coated with a paint prepared by adding a prescribed amount of (c) obtained in Synthesis Example 2 to 100 g of a commercially available acrylic urethane resin paint white enamel base material and 20 g of an acrylic urethane curing agent, and then diluting with a thinner. . After standing at room temperature for 7 days, the diluted solution (solid content: 100 g) obtained in Synthesis Example 1 (solid content: 100 g) and dioctyltin dimaleate (curing catalyst) (5 g) were mixed with the painted iron plate, and the paint was diluted with thinner. Was spray painted. Table 1 shows the results of the adhesion test (Example 1) after leaving at room temperature for 7 days. Table 1 also shows the results when (c) was not added (Comparative Example 1).

Example 2 and Comparative Example 2 On an iron plate prepared in the same manner as in Example 1, a commercially available acrylic melamine resin paint 100 g of a white enamel base material was prepared.
A paint diluted with a thinner after adding 10 g of (c) obtained in the above was spray-applied and baked at 140 ° C. for 30 minutes.
After the temperature of the sample plate returned to room temperature, the diluted solution of (a) obtained in Synthesis Example 1 (solid content: 100 g) was mixed with 5 g of dioctyltin dimaleate, followed by spray coating with a paint diluted with a thinner. After baking at 120 ° C. for 20 minutes, an adhesion test was performed (Example 2). Table 1 also shows the results when (c) was not added (Comparative Example 2).

[0034]

[Table 1]

[0035]

According to the coating method of the present invention, the top coat containing the hydrolyzable silyl group-containing vinyl resin is at least selected from the group consisting of oil paints, synthetic resin paints, cellulose paints and water-soluble paints. Even when overcoated on a kind of undercoat or intermediate coating, the adhesion between the coatings is good.

Continuation of the front page (51) Int.Cl. ⁷ identification code FI C09D 183/00 C09D 183/00 (58) Field surveyed (Int.Cl. ⁷ , DB name) B05D 1/36 B05D 7/24 302 C09D 183 / 00

Claims (3)

(57) [Claims] 1. An oil-based paint, a synthetic resin paint, and a cellulose resin, respectively.
Selected from the group consisting of base paints and water-soluble paints.
At least one kind of undercoat or intermediate paint is applied, and (a) the main chain is substantially composed of a vinyl polymer, and at least one silicon-containing group to which a hydrolyzable group is bonded is contained in one molecule. A method for applying an overcoating composition comprising a curable composition comprising a vinyl resin having one resin and (b) a curing catalyst as a main component, wherein (c) the main chain is substantially A vinyl-based polymer having at least one silicon-containing group bonded to a hydrolyzable group per molecule, and further containing a repeating unit derived from a vinyl-based monomer having a hydroxyl group as a copolymerization component. A coating method comprising a vinyl resin. 2. The synthetic resin paint is a polyurethane paint,
Thermosetting acrylic resin coating and amino alkyd resin coating
At least one member selected from the group consisting of fees
Item 1. The coating method according to Item 1. 3. Hydroxyl which is a copolymer component in the component (c)
Group-containing vinyl monomer is modified with ε-caprolactone
Claim 1 or Claim 2 which is a hydroxyalkyl vinyl monomer.
Is the coating method described in 2.