JP3011945B2 - Curable composition for multilayer coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention has at least one silicon-containing group (hereinafter also referred to as a hydrolyzable silyl group) bonded to a hydrolyzable group per molecule. And a vinyl resin containing a unit derived from a vinyl monomer having a specific amino group as a copolymer component, and a curing catalyst, and are applied on a coating film from a synthetic resin emulsion multilayer coating material. And a curable composition for multilayer coating. More specifically, the present invention relates to the curable composition particularly useful as a coating agent having improved coatability.

[Problems to be solved by conventional technologies and inventions]

The hydrolyzable silyl group-containing vinyl polymer cures at room temperature, has good adhesion to inorganic substances such as concrete, glass, steel plate, and aluminum, and is found to be a resin with excellent weather resistance, and has already been applied for a patent. (Japanese
No. 54-36395).

However, this vinyl polymer is not always satisfactory in adhesion to organic substances. For example, when a multi-layer coating is performed to form a multi-layer coating film, an intermediate coating material is applied and then a top coating is applied. The top coating is applied one to several days after the intermediate coating. However, when the main material of the intermediate coating material is a thermoplastic resin such as an acrylic emulsion, their adhesion may be insufficient and lifting (chipping) may occur. I could not get a face.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the above problems, and as a result, have completed the present invention. That is, the present invention provides: <a> a silicon-containing group (hydrolyzable silyl group) in which the main chain is substantially composed of a vinyl polymer and is bonded to a hydrolyzable group;
And at least one dialkylaminoalkyl acrylate as a copolymer component in one polymer molecule.
A vinyl resin containing a unit derived from at least one member selected from the group consisting of dialkylaminoalkyl methacrylate, N-dialkylaminoalkylacrylamide and N-dialkylaminoalkylmethacrylamide, and <b> a curing catalyst, comprising: The present invention relates to a curable composition for multi-layer coating applied on a coating film from a resin emulsion-based multi-layer finish coating material.

〔Example〕

The composition of the present invention has at least one hydrolyzable silyl group per molecule in which the main chain as the component (a) is substantially composed of a vinyl polymer, and is bonded to a hydrolyzable group, Further, as a copolymer component, dialkylaminoalkyl acrylate, dialkylaminoalkyl methacrylate,
N-dialkylaminoalkylacrylamide and N
A vinyl resin containing a unit derived from at least one kind selected from the group consisting of -dialkylaminoalkyl methacrylamide (hereinafter, also referred to as a vinyl monomer having an amino group or an amino group-containing monomer) Degradable silyl group-containing vinyl resin).

Because the main chain of the hydrolyzable silyl group-containing vinyl resin is substantially composed of a vinyl polymer, the weather resistance of the cured product,
It is excellent in chemical resistance and the like, and by changing the copolymer composition, it is possible to design a wide range of resins from soft to hard. In addition, since there is at least one, and preferably two or more hydrolyzable silyl groups in a molecule which hydrolyze into silanol groups in the presence of moisture and further form and cure siloxane bonds, the presence of moisture In addition, the composition can be cured at room temperature, and the weatherability and chemical resistance of the cured product can be further improved to form a chemically stable siloxane bond. Furthermore, since a unit derived from a vinyl monomer having an amino group (amino group-containing monomer) is contained in the hydrolyzable silyl group-containing vinyl resin, the adhesion to the base material, particularly to organic substances, is reduced. And the lifting is remarkably improved.

Although the molecular weight of the hydrolyzable silyl group-containing vinyl resin is not particularly limited, the number average molecular weight is 20 from the viewpoints of workability, stability, and appearance (gloss value, visual evaluation) of the coating film.
Those having about 00 to 80,000, particularly preferably about 3000 to 25,000 are generally used.

The hydrolyzable silyl group-containing vinyl resin can be obtained, for example, by copolymerizing a vinyl monomer, a hydrolyzable silyl group-containing monomer, and an amino group-containing monomer. It may contain a urethane bond or a siloxane bond in a range of 50% or less.

The vinyl monomer used for producing the hydrolyzable silyl group-containing vinyl resin as the component (a) used in the present invention is not particularly limited. For example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) )
Acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth)
Acrylate, cyclohexyl (meth) acrylate,
Esters of acrylic acid and methacrylic acid such as trifluoroethyl (meth) acrylate and pentafluoropropyl (meth) acrylate; polycarboxylic acids (maleic acid,
Esters of unsaturated polycarboxylic acids such as diesters or half esters of fumaric acid, itaconic acid, etc. and C1-C20 linear or branched alcohols; styrene, α-methylstyrene, chlorostyrene, styrenesulfone Acids, 4-hydroxystyrene, aromatic hydrocarbon vinyl compounds such as vinyltoluene; vinyl acetate;
Vinyl ester and allyl ester compounds such as vinyl propionate and diallyl phthalate; vinyl compounds containing a nitrile group such as (meth) acrylonitrile; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy Ethyl vinyl ether, N-methylol (meth) acrylamide, Alonix 5700 (manufactured by Toa Gosei Co., Ltd.), Placce
l FA-1, Placcel FA-4, Placcel FM-1, Placcel
Hydroxyl-containing vinyl compounds such as FM-4 (all manufactured by Daicel Chemical Industries, Ltd.); (meth) acrylic acid, maleic acid,
Acids such as fumaric acid and itaconic acid, salts thereof (alkali metal salts, ammonium salts, amine salts, etc.); acid anhydrides of unsaturated carboxylic acids such as maleic anhydride; vinyl methyl ether, vinyl chloride, vinylidene chloride, chloroprene And other vinyl compounds such as propylene, butadiene, isoprene, maleimide, N-vinylimidazole and vinylsulfonic acid. These vinyl monomers may be used alone or in combination of two or more.

Specific examples of the hydrolyzable silyl group-containing monomer include a silane derivative having an unsaturated engagement in the molecule, for example, And so on. These hydrolyzable silyl group-containing monomers may be used alone or in combination of two or more.

Specific examples of the dialkylaminoalkyl (meth) acrylate contained in the amino group-containing monomer include, for example, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate Acrylate and the like;
Specific examples of -dialkylaminoalkyl (meth) acrylamide include N-dimethylaminoethyl (meth) acrylamide, N-diethylaminoethyl (meth) acrylamide, N-dimethylaminopropyl (meth) acrylamide, N-diethylaminopropyl (meth) Acrylamide and the like. These amino group-containing monomers may be used alone or in combination of two or more.

These are desirable from the viewpoint of good cost and good recoatability.

The content of the unit derived from the amino group-containing monomer,
0.1 to 50% in hydrolyzable silyl group-containing vinyl resin
(% By weight, the same applies hereinafter), preferably 0.5 to 20%
Is more preferred.

The method for producing the copolymer of these hydrolyzable silyl group-containing monomer, amino group-containing monomer and vinyl monomer is not particularly limited, and examples thereof include JP-A-54-36395 and JP-A-54-36395.
Nos. 7-36109, 58-157810 and the like, 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-mercaptopropylmethyldiethoxysilane, (CH ₃ O) ₃ Si-SS
The molecular weight can be adjusted by using one or more chain transfer agents such as —Si (OCH ₃ ) ₃ and (CH ₃ O) ₃ Si—S ₈ —Si (OCH ₃ ) ₃ . A chain transfer agent having a hydrolyzable silyl group in the molecule, such as γ-mercaptopropyltrimethoxysilane, is added to the monomer mixed solution and continuously added to the end of the vinyl polymer simultaneously with the action of controlling the molecular weight. This is useful because a hydrolyzable 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; methanol, ethanol, isopropanol,
alcohols such as n-butanol; ethers such as ethyl cellosolve, butyl cellosolve, and cellosolve acetate; ketones such as methyl ethyl ketone, ethyl acetoacetate, acetylacetone, diacetone alcohol, methyl isobutyl ketone, and acetone, but are not limited thereto. However, any non-reactive solvent can be used.

Specific examples of the curing catalyst that is the component (b) used in the present invention include, for example, organic tin compounds such as dibutyltin dilaurate, dibutyltin dimaleate, dioctyltin dilaurate, dioctyltin dimaleate, and tin octylate; phosphoric acid, monomethyl phosphate, Phosphoric acid or phosphate such as monoethyl phosphate, monobutyl phosphate, monooctyl phosphate, monodecyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate, didecyl phosphate; alkyl titanate; organoaluminum; maleic acid And acidic compounds such as p-toluenesulfonic acid; alkaline compounds such as sodium hydroxide and potassium hydroxide, but are not limited thereto. No. These curing catalysts may be used alone or in combination of two or more.

The amount of the curing catalyst added to 100 parts of the hydrolyzable silyl group-containing vinyl resin (parts by weight, the same applies hereinafter) is generally 0.1%.
01 to 20 parts, preferably 0.01 to 10 parts.

A dehydrating agent may or may not be used in the curable composition for multilayer coating of the present invention. However, in order to ensure long-term stability and stability without any problem even when repeatedly used, 1
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-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, methylsilicate, ethylsilicate And the like. These hydrolyzable ester compounds may be added before, during or after the polymerization of the silyl group-containing vinyl copolymer.

Further, the curable composition for multilayer coating of the present invention contains one or more amines having a silicon group bonded to at least one hydrolyzable group in one molecule as an adhesion improving component. I can do it.

Specific examples of the adhesion improving component include, for example, γ-
A silane coupling agent such as aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane; a silane coupling agent containing the amino group and ethylene oxide, butylene oxide, Epichlorohydrin, epoxidized soybean oil, and other epicoats manufactured by Ciel
Reaction products with a compound containing an epoxy group such as 828, Epicoat 1001 and the like.

The composition of the present invention as described above is usually a transparent liquid of several centipoise to tens of thousands of centipoise, although it varies depending on the use, the type and amount of the additive, and the like.

The composition of the present invention further includes various pigments depending on the application,
Additives such as dyes, ultraviolet absorbers, anti-settling agents, leveling agents; fibrous resins such as nitrocellulose and cellulose acetate butyrate; alkyd resins, acrylic resins, vinyl chloride resins, chlorinated propylene resins, and chlorinated rubber And resins such as polyvinyl butyral.

The composition of the present invention is useful as a coating agent having improved coating properties, especially lifting properties.

 Next, the composition of the present invention will be described based on examples.

Synthesis Example 1 A reactor equipped with a stirrer, a thermometer, a nitrogen inlet tube, a dropping funnel and a cooling tube was charged with 360 g of xylene, and heated at 110 ° C.
Heated. In this reactor, n-butyl acrylate 28
1 g, methyl methacrylate 552 g, γ-methacryloxypropyltrimethoxysilane 117 g, dimethylaminoethyl methacrylate 50 g, and azobisisobutyronitrile
A solution consisting of 8.5 g was added continuously over 3 hours. After the completion of the monomer addition, a separately prepared solution of 0.5 g of azobisisobutyronitrile and 200 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 1).

The obtained resin solution had a nonvolatile content of 63%, and was diluted with xylene to be adjusted to 50% to obtain a colorless transparent liquid having a viscosity of 1300 cp (23 ° C.). The number average molecular weight determined by the GPC method was about 15,000.

Synthetic Examples 2 to 8 The hydrolyzable silyl group-containing vinyl resin as the component (a) of the present invention was prepared in the same manner as in Synthetic Example 1 except that the proportions of the monomers used were changed as shown in Table 1. (A-2)-
A 50% solution of (a-4) was obtained. For comparative examples, hydrolyzable silyl group-containing vinyl resins (a-5) to (a-) each containing no vinyl monomer having an amino group as a copolymerization component were used.
A 50% solution of 8) was obtained in the same manner as described above.

Using the obtained resin solutions (a-1) to (a-8),
Titanium oxide (CR-90 manufactured by Ishihara Sangyo Co., Ltd.) was dispersed so as to have a PWC (weight% of the pigment based on the total solid content) of 40% and a paint solid content concentration of 60% to prepare a white enamel. Dispersion was performed for 2 hours on a paint shaker using glass beads.

Examples 1 to 4 and Comparative Examples 1 to 4 A commercially available synthetic resin emulsion-based multi-layer finish coating material was applied on a slate such that the film thickness after leaving at room temperature for 1 day was 3 mm. After standing at room temperature for one day, dioctyltin maleate and γ-
One part of (β-aminoethylamino) propyltrimethoxysilane was added to 100 parts of the resin solids, and diluted with a thinner to a solid concentration of 45%. It was painted to become. after that,
On the first, third, fifth and seventh days, a brush coating was applied to a dry film thickness of about 50 μm, a recoat test was performed, and the occurrence of lifting (thickness) was visually observed. Second result
It is shown in the table.

In Table 2, .largecircle. Indicates that no shrinkage occurs, .DELTA. Indicates that slight shrinkage occurs, and x indicates that shrinkage occurs.

[Effects of the Invention] A paint prepared using the curable composition for multilayer coating of the present invention has an effect of forming an excellent coating film which does not generate lifting even when overcoated on an organic coating. You can see that there is.

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-57-172949 (JP, A) JP-A-57-105446 (JP, A) JP-A-57-63351 (JP, A) JP-A-57-172351 55954 (JP, A) JP-A-57-21410 (JP, A) JP-A-57-174341 (JP, A)

Claims (2)

(57) [Claims] 1. <a> The main chain is substantially composed of a vinyl polymer, and has at least one silicon-containing group (hydrolyzable silyl group) bonded to a hydrolyzable group in one molecule. A vinyl resin containing, as a copolymerization component, a unit derived from at least one selected from the group consisting of dialkylaminoalkyl acrylate, dialkylaminoalkyl methacrylate, N-dialkylaminoalkyl acrylamide and N-dialkylaminoalkyl methacrylamide; b> Curing catalyst A curable composition for a multilayer coating which is applied on a coating film from a synthetic resin emulsion-based multilayer coating material. 2. The content of a unit derived from at least one selected from the group consisting of dialkylaminoalkyl acrylate, dialkylaminoalkyl methacrylate, N-dialkylaminoalkyl acrylamide and N-dialkylaminoalkyl methacrylamide is 0.5 to 0.5. Two
The composition according to claim 1, which is 0% by weight.