JPH05309330A - Formation of film - Google Patents

Abstract

PURPOSE:To make it possible to form a film with excellent film finishing properties and adhesion to a raw material by using a specific resin and a specific organic solution-type paint composition as a paint composition for a coloring base film, and further, using a specific organic solution-type as a paint composition for clear film. CONSTITUTION:A curable film formed by using a melamine-curable paint is used as a raw material, then a coloring base film and a clear film are sequentially formed on the curable film, and both films are cured, as a method for forming a film. An organic solution-type paint composition B used as a paint composition for a colored film consists of a resin A having at least, one type selected between silanol group and a hydrolyzable group connected directly to a silica atom, hydroxyl group and epoxy group, metal flake powder and/or mica powder as essential ingredients. In addition, an organic solution-type paint composition C used as a clear paint contains a resin A as a paint composition and a metal chelate product as essential ingredients.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel method for forming a coating film.

[0002]

2. Description of the Related Art As an automotive top coating,
Currently, the mainstream paints are thermosetting acrylic resin / melamine resin-based paints, thermosetting polyester resin / melamine resin-based paints, etc. There is room for improvement.
There is also a problem that the low temperature curability is not sufficient. Further, there are still problems such as a coating film being cracked by a condensate (formalin, etc.) generated during baking and environmental pollution.

The applicant of the present invention has proposed an automotive coating composition in Japanese Patent Application Laid-Open No. 2-160879 as a coating excellent in low temperature curability. The coating composition is a silicone coating composition prepared by blending a metal chelate compound with a copolymer having a silanol group- and / or alkoxysilane group-containing polysiloxane macromonomer and an oxirane group-containing vinyl monomer as monomer components. A melamine cured coating is used as the material, and this is applied to both a metallic base coat (a mixture of aluminum flake pigment in the paint) and a clear top coat. When the film is baked, the base coat and the top coat are discolored to deteriorate the appearance, and the adhesion between the material melamine cured coating film and the base coat is poor.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned drawbacks, the present inventors have found that in a method of curing a coating film using a silanol group, a hydroxyl group and an epoxy group as a functional group, As a coating composition for forming a colored base coating film, it has been found that a coating composition having no metal chelate compound can provide a coating film excellent in discoloration resistance of the coating film and adhesion to the material, and the present invention It came to completion.

That is, the present invention uses a cured coating film formed of a melamine curable coating material as a raw material, and a colored base coating film and a clear coating film are sequentially formed on the cured coating film, and then both coating films are cured to form a coating film. In the method, as the coating composition (I) for forming a colored base coating film, (A) a resin having at least one group selected from a silanol group and a hydrolyzable group directly bonded to a silicon atom, a hydroxyl group and an epoxy group. And (B) a coating composition (II) for forming a clear coating film using an organic solution type coating composition containing metal flake powder and / or mica powder as an essential component
And (C) an organic solution type coating composition containing a metal chelate compound as an essential component.

In the present invention, the hydrolyzable group possessed by the resin (A) is a residue which is hydrolyzed in the presence of water to form a hydroxysilane group, for example, a C _1-5 alkoxy group; a phenoxy group. Aryloxy groups such as tolyloxy group, paramethoxyphenoxy group, paranitrophenoxy group and benzyloxy group; acetoxy group, propionyloxy group, butanoyloxy group, benzoyloxy group,
A residue such as an acyloxy group such as a phenylacetoxy group and a formyloxy group is included.

The resin (A) used in the method of the present invention will be described.

The resin (A) includes silanol groups and /
Alternatively, a resin having a hydrolyzable group directly bonded to a silicon atom (hereinafter, these groups are simply referred to as “reactive silicon group”), an epoxy group and a hydroxyl group, which are the same or different, is included.

Examples of the resin containing the reactive silicon group, the epoxy group and the hydroxyl group in the same resin include, for example, a polymerizable unsaturated monomer (a) having a reactive silicon group and an epoxy group-containing polymerizable unsaturated monomer. Examples include copolymers obtained by radical polymerization reaction of the monomer (b), the hydroxyl group-containing polymerizable unsaturated monomer (c) and, if necessary, other polymerizable unsaturated monomer (d) other than the above. Be done.

The copolymer has an average of one or more, preferably an average of about 2 or more, reactive silicon groups in one molecule, and an average of about 1 or more, preferably an average of about 2 to 40 epoxies in one molecule. It is preferable to have a group and an average of about 2 to 200 hydroxyl groups in one molecule from the viewpoint of curability and coating finish. In order to contain the number of these functional groups in the resin, the monomers (a) to (d) may be blended so that the blending ratio falls within the range.

The average molecular weight of the copolymer is about 1,0.
00-200,000, preferably 3,000-10
10,000 is desirable.

Examples of the polymerizable unsaturated monomer (a) having a reactive silicon group include γ- (meth) acryloxypropyltrimethoxysilane, γ (meth) acryloxypropyltriethoxysilane, γ (meth ) Silane compounds such as acryloxypropyltrisilanol, γ- (meth) acryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-styrylethyltrimethoxysilane, allyltriethoxysilane; the silane compounds And a reaction product with a trialkoxy or trihydroxysilane compound (for example, methyltrimethoxysilane, phenyltrimethoxysilane, methyltrisilanol) (for example, JP-A-2-1608).
Polysiloxane-based macromonomers described in JP-A No. 79) can be preferably used.

Epoxy group-containing polymerizable unsaturated monomer (b)
As the above, a polymerizable unsaturated monomer having an alicyclic epoxy group is preferable from the viewpoint of curability, and for example, JP-A-2-160
Examples thereof include alicyclic vinyl monomers represented by the general formulas (4) to (18) described in Japanese Patent No. 879.

Examples of the hydroxyl group-containing polymerizable unsaturated monomer (c) include hydroxyethyl (meth) acrylate,
Hydroxyalkyl esters of (meth) acrylic acid such as hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate; (poly) alkylene glycols such as ethylene glycol mono (meth) acrylate and polyethylene glycol mono (meth) acrylate Mono (meth) acrylates; hydroxyalkyl vinyl ethers such as hydroxybutyl vinyl ether; allyl alcohols such as allyl alcohol, methallyl alcohol; lactones (for example, ε-caprolactone, γ-valerolactone) Examples include adducts.

Further, other polymerizable unsaturated monomer (d)
As, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
C _1-24 alkyl or cycloalkyl esters of (meth) acrylic acid such as hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, styrene, vinyltoluene, etc. Perfluoroalkyl (meth) acrylates such as perfluorobutylethyl (meth) acrylate, perfluoroisononylethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, and (meth) Acrylonitriles, olefins,
Fluoroolefins, vinyl esters, cyclohexyl or alkyl vinyl ethers, aryl ethers and the like can be mentioned.

The resin containing a reactive silicon group, an epoxy group and a hydroxyl group differently is a mixed resin of a resin having a reactive silicon group and an epoxy group-containing resin,
And two kinds of mixed resins having a hydroxyl group on one or both of these resins; three kinds of mixed resins of a resin having a reactive silicon group, an epoxy group containing resin and a hydroxyl group containing resin.

Examples of the resin having a reactive silicon group include
An average molecular weight of 1,000 to 200,000 having an average of about 1 or more reactive silicon groups in one molecule (when a hydroxyl group is contained, an average of about 1 to 400 is preferable in one molecule).
0 resin can be used. Specifically, the resin includes the polymerizable unsaturated monomer (a) having the reactive silicon group, and optionally the hydroxyl group-containing polymerizable unsaturated monomer (c) and the other polymerizable unsaturated. A (co) polymer obtained by radically polymerizing the monomer (d) can be used.

As the epoxy group-containing resin,
Average of more than 2 molecules in one molecule (preferably up to 300 molecules)
A resin having an average molecular weight of 1,000 to 200,000 and having an epoxy group (in the case of containing a hydroxyl group, an average of about 1 to 400 is preferable in one molecule) can be used. Specifically, the resin includes the epoxy group-containing polymerizable unsaturated monomer (b) and, if necessary, the hydroxyl group-containing polymerizable unsaturated monomer (c) and the other polymerizable unsaturated monomer. A (co) polymer obtained by subjecting the body (d) to a radical polymerization reaction can be used.

The hydroxyl group-containing resin has an average molecular weight of 1,000 to 2 having an average of about 2 or more hydroxyl groups in one molecule.
0,000 resins can be used. The resin is specifically (co) polymer obtained by radical polymerization reaction of the above-mentioned hydroxyl group-containing polymerizable unsaturated monomer (c) and, if necessary, other polymerizable unsaturated monomer (d). Coalescence can be used.

In the case of a two-component mixed resin of a resin having a reactive silicon group and a resin having an epoxy group, the compounding ratio of the above resin is about 5 to 95% by weight, preferably about 20 to 80% by weight.
% By weight, the latter about 95-5% by weight, preferably about 80-2.
0% by weight is desirable, and in the case of a three-component mixed resin of a resin having a reactive silicon group, an epoxy group-containing resin and a hydroxyl group-containing resin, the resin having a reactive silicon group is about 5 to 9
5% by weight, preferably about 20-80% by weight, epoxy group-containing resin about 95-5% by weight, preferably about 80-20% by weight, hydroxyl group-containing resin about 0.1-40% by weight, preferably about 1- 20% by weight is desirable.

Examples of the above resin include hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, ether solvents such as dioxane and ethylene glycol diethyl ether. It is used in the form of a solution type, a dispersion type, a non-aqueous dispersion type or the like dissolved or dispersed in a solvent, an alcohol solvent such as butanol or propanol, an aliphatic hydrocarbon such as pentane, hexane or heptane.

The coating composition (I) used in the method of the present invention will be described.

The coating composition (I) is an organic solution type coating composition containing the resin (A) and metal flake powder and / or mica powder (B).

Metal flake powder and mica powder (B)
Is to give a metallic feeling to the coating film, and examples of the metal flakes include aluminum flakes, nickel flakes, copper flakes, brass flakes, and chrome flakes, and mica powders include pearl mica and colored pearls. Examples include mica. The metal flake powder and the mica powder (B) are generally added in an amount of about 1 to 20 parts by weight based on 100 parts by weight of the resin (A) solid content.

In the coating composition (I), in addition to the above-mentioned components, if necessary, organic pigments, inorganic pigments, pigment dispersants, polymer fine particles, ultraviolet absorbers, coating surface adjusting agents, curing catalysts, cellulose acetates. (And derivatives thereof) and other additives for paints may be added.

The pigment which may be incorporated in the paint is
For example, organic pigments (for example, quinacridone type such as quinacridone red, azo type such as pigment red, phthalocyanine type such as phthalocyanine blue, phthalocyanine green, etc.), inorganic pigments (for example, titanium oxide, barium sulfate,
Calcium carbonate, barita, clay, silica, etc.), carbon-based pigments (carbon black), and the like.

Further, the coating composition (I
I) will be described.

The coating composition (II) is an organic solvent type coating composition containing the resin (A) and the following metal chelate compound (C) as essential components.

The metal chelate compound (C) is, for example, a chelate compound capable of forming a keto / enol tautomer in a metal alkoxide in which an alkoxy group is bonded to a metal such as aluminum, titanium, zirconium, calcium or barium. Coordinated metal chelate compounds are included. Among the above, aluminum, titanium,
A metal chelate compound such as zirconium is preferable, and specifically, diisopropoxyethylacetoacetate aluminum, tris (ethylacetoacetate) aluminum, isopropoxybis (ethylacetoacetate) aluminum, monoacetylacetonato bis (ethylacetoacetate). ) Aluminum, Tris (n
-Propylacetoacetate) aluminum, tris (n-butylacetoacetate) aluminum, monoethylacetoacetate bis (acetylacetonate)
Aluminum chelate compounds such as aluminum, tris (acetylacetonato) aluminum, tris (propionylacetonato) aluminum, acetylacetonato bis (propionylacetonato) aluminum; diisopropoxy bis (ethylacetoacetate titanium, diiso Titanium chelate compounds such as propoxy bis (acetylacetonato) titanium; zirconium chelate compounds such as tetrakis (n-propylacetoacetate) zirconium, tetrakis (acetylacetonato) zirconium, tetrakis (ethylacetoacetate) zirconium, etc. Among these, aluminum chelate compounds are more preferable.

The compounding ratio of the metal chelate compound (C) is 0.0 with respect to 100 parts by weight (solid content) of the resin (A).
The amount is 1 to 20 parts by weight, preferably 0.1 to 10 parts by weight. If the amount of the metal chelate compound (C) is less than 0.01 parts by weight, curability and finish of the coating film are deteriorated, and if it exceeds 20 parts by weight, finish and water resistance of the coating film are deteriorated, which is not preferable.

If necessary, the coating composition (II) may be blended with an ultraviolet absorber, polymer fine particles, extender pigment, antioxidant, light stabilizer, and various other additives for coatings. Further, a coloring pigment can be blended as necessary so that the colored base coating film is not completely hidden.

In the method of the present invention, for example, a chemically treated steel sheet is coated with an electrodeposition paint, and an intermediate coating paint (may be omitted).
Coating composition, a primer suitable for various plastic materials, an intermediate coating composition (sometimes omitted), etc. as a material, the coating composition (I) is applied, and then the coating composition. It can be carried out by painting the object (II). The above-mentioned electrodeposition paints and intermediate coatings differ depending on the type of paint, but are usually at 140-190 ° C for 30-
Bake for 90 minutes. The coating of the coating compositions (I) and (II) can be performed using a conventional coating method, for example, an electrostatic coating or a non-electrostatic coating machine. The thickness of the colored base coat formed from the coating composition (I) is preferably about 10 to 50 μm (after curing). After coating the coating composition (I),
The coating composition (II) is applied after being left at room temperature for several minutes or forcedly dried at about 50 to 80 ° C. for several minutes. The thickness of the clear coating film formed by the coating composition (II) is 20 to 100.
μm (after curing) is preferred. Then, the article to be coated is 120-
It can be cured by heating at about 180 ° C. for about 30 to 90 minutes.

[0033]

In the method of the present invention, it is an important requirement that the coating composition (I) for forming a colored base coating film does not contain a metal chelate compound.

That is, the resin (A) component in the coating composition (I) does not cure as a single coating film without the presence of a metal chelate catalyst, but in the method of the present invention, the colored base coating film and the clear coating film are heated. At this time, a part of the metal chelate component in the clear coating film penetrates into the colored base coating film, whereby the colored base coating film and the clear coating film are simultaneously cured, and the coating film finish (discoloration resistance) and material (melamine curing) A coating film having excellent adhesion to a coating film) can be formed.

[0035]

The present invention will be described in detail below with reference to examples.

Resin (a) Production Example Methyltrimethoxysilane 2720 g γ-methacryloxypropyltrimethoxysilane 256 g Deionized water 1134 g 6% hydrochloric acid 2 g Hydroquinone 1 g The mixture is reacted at 80 ° C. for 5 hours to obtain a polysiloxane macromonomer. It was The obtained polysiloxane-based macromonomer had a number average molecular weight of 2000, and had one vinyl group (polymerizable unsaturated bond) and four hydroxyl groups per molecule on average.

Next, the above polysiloxane macromonomer 100 g methyl methacrylate 300 g ethyl methacrylate 200 g

[0038]

[Chemical 1]

2-Hydroxyethyl acrylate 100 g Azobisisobutyronitrile 10 g of a mixture 100 parts of an equal weight mixture of butanol and xylene 100
It was dropped into 0 g and polymerized at 120 ° C. to obtain a transparent solid content 50% by weight copolymer. The number average molecular weight of the copolymer is about 40.
It was 000.

Resin (b) Solid content was the same as that of resin (a) except that 200 g of n-butyl methacrylate and 300 g of cyclohexyl methacrylate were used in place of 300 g of methyl methacrylate and 200 g of ethyl methacrylate in resin (a). 50% by weight, copolymer number average molecular weight number 40
000 transparent copolymers were obtained.

Resin (c) Production Example γ-methacryloxypropyltrimethoxysilane 100 g Ethyl acrylate 200 g Methyl methacrylate 300 g

[0042]

[Chemical 2]

Hydroxybutyl acrylate 100 g Mixture of 10 g of azobisisobutyronitrile 10 g of an equal weight mixture of butanol and xylene 100
The mixture was added dropwise to 0 g and reacted at 120 ° C. to obtain a transparent copolymer having a solid content of 50% by weight and a copolymer number average molecular weight of about 20,000.

Resin (d) Production Example Resin (c) had the same composition and composition as resin (c) except that 200 g of ethyl acrylate and 300 g of methyl methacrylate were replaced with 150 g of styrene, 200 g of cyclohexyl methacrylate and 150 g of tert-butyl methacrylate. By the method, a transparent copolymer having a solid content of 50% by weight and a number average molecular weight of the copolymer of about 2000 was obtained.

Resin (e) Production Example Methyl methacrylate 400 g γ-methacryloxypropylmethyldimethoxysilane 150 g

[0046]

[Chemical 3]

2-Hydroxyethyl Methacrylate 100 g Azobisisobutyronitrile 10 g of a mixture of butanol and xylene in an equal amount of 1000
It was added dropwise to g and reacted at 120 ° C. to obtain a transparent copolymer having a solid content of 50% by weight and a copolymer number average molecular weight of about 20,000.

Resin (f) Production Example Resin (e) was prepared in the same manner as resin (e) except that methylmethacrylate was replaced with cyclohexylmethacrylate. Solid content was 50% by weight and copolymer number average molecular weight was about 50% by weight. 2000 transparent copolymers were obtained.

Colored base coating composition I-1-3 200 g of a 50% solution of the resins (a), (c) and (e).
5 g of Europearl (trade name, manufactured by Marl Corporation) was blended with each of them, and then a paint viscosity of 13 seconds (Ford Cup No.
The coating compositions I-1, 2, and 3 were prepared in the order of using the resins (a), (c), and (e).

Coating Composition I-4 for Colored Base Coating Film Tris (propionylpropionate) aluminum was added to the above-mentioned coating composition I-1 in an amount of 100 g of resin (a) (solid content).
To 1 g to obtain a coating composition I-4.

Clear coating composition II-1 to 200: 200 g of a 50% solution of the resins (b), (d) and (f).
1 g of tris (propionylpropionate) aluminum was added to each of the above, and coating compositions II-1 to 3 were obtained in the order of using the resins (b), (d) and (f).

Preparation of Material An epoxy resin-based cationic electrodeposition coating was applied (25 μm) to a dull steel plate (chemical conversion treatment), followed by heating and curing at 170 ° C. for 30 minutes, and then as an intermediate coating, Rugerbake AM (trademark, Kansai Paint ( Co., Ltd., polyester resin / melamine resin-based automotive paint) was applied to a dry film thickness of 30 μm, and baked at 140 ° C. for 30 minutes. Next, the coated surface was water-polished with # 400 sandpaper, drained and dried, and the coated surface was wiped with petroleum benzine as a material.

Example A coating composition I for a colored base coating film was spray-coated on the above material so that the dry film thickness was about 15 μm, followed by splashing off, and then a coating composition II for a clear coating film was dried. Is spray-painted so that
A coating film was formed by baking at 30 ° C. for 30 minutes.

Comparative Example 1 A coating film was formed in the same manner as in Examples by using the combination of the coating compositions I and II shown in Table 1.

Comparative Example 2 The coating composition I-1 was spray coated on the material so that the dry film thickness was about 15 μm, and baked at 140 ° C. for 30 minutes.

The results are summarized in Table 1.

[0057]

[Table 1]

Coating film performance Discoloration resistance: 140 ° C.-30 minutes overbaking was performed to compare with the original coating film. O indicates that no discoloration was observed, Δ indicates that slight discoloration was observed, and x indicates that significant discoloration was observed.

Solvent resistance: The state of the coating film was examined by immersing it in Nisseki Silver Gasoline (trade name, manufactured by Nippon Oil Co., Ltd.) for one day. ◯ means that there is no abnormality, Δ means that gloss is generated, and × means that it is swollen or dissolved.

Adhesiveness: Using a cutter knife to reach the substrate, draw 11 parallel and 11 vertical and horizontal parallel lines at 1 mm intervals at approximately the center of the test piece so that 100 squares can be formed in 1 cm ^2. The cut surface was cut into scratches, and an adhesive cellophane tape was attached to the coated surface, and the coated surface after the tape was peeled off was evaluated. O indicates that no peeling of the coating film was observed, Δ indicates that slight peeling was observed between the material and the colored base coating film, and X indicates that a large amount of interlayer peeling was observed.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C09D 5/00 PPF 6904-4J 5/36 PRD 7211-4J 5/38 PRF 7211-4J 163/00 PJD 8830-4J 201/06 PDJ 7415-4J 201/10 PDP 7415-4J

Claims (1)

[Claims] 1. A method for forming a coating film, comprising a cured coating film formed of a melamine-curable coating material as a raw material, a colored base coating film and a clear coating film being sequentially formed thereon, and then curing both coating films. As a coating composition (I) for forming a colored base coating film, (A) a resin having at least one group selected from a silanol group and a hydrolyzable group directly bonded to a silicon atom, a hydroxyl group and an epoxy group, and (B) ) A coating composition (II) for forming a clear coating film using an organic solution coating composition containing metal flake powder and / or mica powder as an essential component, as described above in (A) and (C).
A method for forming a coating film, which comprises using an organic solution type coating composition containing a metal chelate compound as an essential component.