JPH06279728A - Coating application method - Google Patents

Abstract

PURPOSE:To form a decorative coating film excellent in adhesion with a topcoating film by coating part of the surface of a specific cured topcoating film with a decorative coating compsn. obtd. by adding a phosphoric ester to a specific two-coating compsn. CONSTITUTION:Part of the surface of a cured topcoating film having a static glass transition point of 60-130 deg.C t is coated with a decorative coating compsn. mainly comprising a hydroxylated resin (e.g. a polyester polyol or an acrylic polyol), a polyisocyanate compd. (e.g tolylene diisocyanate or diphenylmethane diisocyanate), and a phosphoric ester (e.g. monoethyl phosphate) in such a manner that a decorative coating film is formed in a shape of lines, characters, or patterns. Since the resin reacts easily with the isocyanate compd. to crosslink at a room temp., they are stored separately and mixed just before they are used. The ester is pref. premixed into the ester and/or the isocyanate compd. The addition of the ester improves the adhesion between the topcoating film and the decorative coating film.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a coating method for improving the design or beauty of a cured topcoat surface by further applying a cosmetic coating in the shape of letters, patterns or lines. The present invention relates to a coating method in which the adhesion between the coated surface and the cosmetic coating film is improved.

[0002]

2. Description of the Related Art A coating material for cosmetics is partially applied in a shape such as a line, a pattern or a character on the outer panel portion of an automobile, especially a door locker portion, which has been overcoated to improve its design and beauty. There are many things that can be improved. As this cosmetic coating, a room-temperature-drying coating containing a drying oil-modified alkyd resin as a main component has been used so far, but it has a defect of poor abrasion resistance and weather resistance. As a solution to these drawbacks, a two-pack type coating containing a hydroxyl group-containing resin and a polyisocyanate compound as main components is used.

On the other hand, on the other hand, top coats having excellent acid resistance due to global environmental pollution and improved scratch resistance have been developed, and the surface of these top coats is more common than conventional ones. In addition, it has been pointed out that the above two-component cosmetic coating composition has insufficient adhesion to the top coating film due to its high static glass transition temperature, and its solution is desired. Generally, the static glass transition temperature of a top-coat cured coating having improved acid resistance and scratch resistance is 6
It is contained in the range of 0 to 130 ° C., and the static glass transition temperature of a usual coating film is lower than that.

Further, there is also a problem that a coating film is easily peeled off due to collision of pebbles flipped up during traveling, so-called chipping phenomenon easily occurs.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and is characterized in that a phosphoric acid ester is added to the above-mentioned two-pack type paint as a cosmetic paint.

That is, according to the present invention, a cosmetic coating composition containing a hydroxyl group-containing resin, a polyisocyanate compound and a phosphoric acid ester as a main component on a part of a cured topcoat film surface having a static glass transition temperature of 60 to 130 ° C. The present invention relates to a coating method characterized by coating.

The method of the present invention will be specifically described below.

The cosmetic coating used in the present invention contains a hydroxyl group-containing resin, a polyisocyanate compound and a phosphoric acid ester as main components.

The hydroxyl group-containing resin is a resin having at least two hydroxyl groups in one molecule, and for example, polyester polyol or acrylic polyol is preferably used.

The polyester polyol can be obtained by esterifying a polyhydric alcohol having two or more hydroxyl groups in one molecule with a polybasic acid having two or more carboxyl groups in one molecule. The polybasic acid may be saturated or unsaturated, and a monocarboxylic acid may be used together. The polyester polyol has a number average molecular weight of about 1,000 to 8,000, a hydroxyl value of 25 to 150,
50 to 80 is particularly preferable. Further, an acid value of 20 or less is suitable.

The acrylic polyol is a polymer obtained by polymerizing only an acrylic monomer having a polymerizable double bond and a hydroxyl group in one molecule, or polymerizing the acrylic monomer and another polymerizable monomer. Examples of the other polymerizable monomer include those having only a polymerizable double bond as a functional group in one molecule, and further polymerizable monomers having a functional group other than a hydroxyl group such as a carboxyl group, a glycidyl group and an amino group. The acrylic polyol has a number average molecular weight of about 5,000 to 30,000 and a hydroxyl value of 25 to 1
50, especially 50-80 is preferable. Further, an acid value of 20 or less is suitable.

The polyisocyanate compound is a compound having two or more free isocyanate groups in one molecule. Specific examples thereof include aliphatic, alicyclic and aromatic polyisocyanates, of which tolylene diisocyanate and diphenylmethane diisocyanate (MD
I)), xylylene diisocyanate, naphthylene diisocyanate, and other aromatic compounds are preferred.

Examples of the phosphoric acid ester include monoethyl phosphate, monobutyl phosphate, monopropyl phosphate, monooctyl phosphate, diethyl phosphate, dibutyl phosphate, dipropyl phosphate, dioctyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl. Phosphoric acid alkyl esters such as phosphate and tributoxyethyl phosphate can be preferably used, but halogen-containing phosphoric acid esters, aromatic ring-containing phosphoric acid esters, higher alkyl phosphoric acid esters and the like other than these can also be applied. Of these, monoalkyl phosphates are particularly preferable.

The cosmetic coating contains the above-mentioned hydroxyl group-containing resin, polyisocyanate compound and phosphoric ester as main components, and the composition ratio of these components can be arbitrarily selected according to the purpose. For example, the hydroxyl group-containing resin and the polyisocyanate compound are preferably such that the isocyanate group of the polyisocyanate compound is in the range of 0.6 to 1.3 per one hydroxyl group of the hydroxyl group-containing resin, and the phosphoric acid ester is both of these components. 0.05 per 100 parts by weight
-5 parts by weight, especially 0.1-2 parts by weight are suitable.

In the cosmetic coating composition used in the present invention, the hydroxyl group-containing resin and the polyisocyanate compound readily undergo a crosslinking reaction at room temperature. Therefore, both components should be separated during storage and mixed immediately before use. Preferably. It is preferable that the phosphoric acid ester is premixed in either or both components. Then, these components can be dissolved or dispersed in an organic solvent having no functional group that reacts with an isocyanate group.

If necessary, the cosmetic coating may further include
It is also possible to mix a color pigment, a metallic pigment, an extender pigment, a matte pigment and the like.

According to the present invention, the cosmetic paint is applied to a shape such as a line, a character or a pattern and has a static glass transition temperature of 60 to 13.
It is characterized in that it is applied on the surface of the cured top coat which is 0 ° C. This top coating film has improved acid resistance, scratch resistance, etc., has an inactive surface, and has a static glass transition temperature of 60 to 130 ° C., particularly 68 to 10 ° C.
It is preferable to apply the cosmetic coating to the surface of the top coating film cured at 0 ° C.

Since the above-mentioned top coating film is inactive, the conventional cosmetic coating has insufficient adhesion, but the cosmetic coating of the present invention eliminates all such defects and exhibits excellent adhesion.

As the paint for forming the top coat film having such a static glass transition temperature, for example, a resin containing a hydroxyl group and a carboxyl group (which may further include a glycidyl group), a hydroxyl group and a glycidyl group (further A top coat containing a resin containing a carboxyl group) and a melamine resin as main components; a top coat containing a resin containing a hydroxyl group and a silanol group (which may be an alkoxysilane group) and a melamine resin as a main component Paints; top-coat paints containing hydroxyl group-containing resins, melamine resins and polysiloxane resins as main components; and the like, and these coating films are cured by a plurality of different crosslinking reactions.

In the present invention, the static glass transition temperature of the top coating film, which is the surface to be coated of the cosmetic coating, is determined by pressing the probe with a load of 2 g against the surface of the cured top coating film to determine the temperature of the coating film. The temperature was raised at a rate of 5 ° C./minute to measure the temperature (° C.) at which the coating softened and the probe penetrated into the coating, which was taken as the static glass transition temperature of the top coating. This measurement is performed by Rigaku Denki Co., Ltd.
Analysis) was used.

In the present invention, the coating of the cosmetic coating on the surface of the cured coating film is carried out by a known method. For example, after coating the coating with an undesired portion with a masking tape or the like, only the desired portion is coated. The cosmetic coating can be applied to the cured coating surface in any shape by applying the cosmetic coating by a method such as spray coating or electrostatic coating, and then removing and removing the masking tape. The coating film for cosmetics is cured by leaving it at room temperature, but it can be cured by heating, and the film thickness is, for example, about 5-10.
0 μm is suitable.

The coating film for cosmetics formed according to the present invention has markedly improved adhesion to the surface to be coated (cured coating) and chipping resistance. It was also found that the weather resistance, abrasion resistance, and corrosion resistance were good.

[0023]

EXAMPLES Next, examples of the present invention and comparative examples will be described.

I. Sample 1. To be coated Steel plate coated with cationic electrodeposition paint and intermediate paint,
A white topcoating material containing a hydroxyl group-containing silanol group-containing acrylic resin and a melamine resin as a main component was applied (film thickness: 20 μm) and heated at 160 ° C. for 20 minutes to form a cured topcoating film. . The static glass transition temperature of the cured coating film was 70 ° C.

2. Cosmetic coating (i) Hydroxyl group-containing acrylic resin (number average molecular weight 1000
0, a hydroxyl value of 75, an acid value of 14) and MDI were mixed at a hydroxyl group: isocyanate group = 1: 1 (molar ratio), and phosphoric acid ester (monobutyl phosphate, “MP-
4 ", manufactured by Daihachi Chemical Co., Ltd.) is added in an amount of 0.2 part by weight per 100 parts by weight of the total amount of the hydroxyl group-containing acrylic resin and MDI. A mixed solvent of toluene: xylene = 1: 1 (weight ratio) was used as the organic solvent, and the solid content was adjusted to 60% by weight. Further, 5 parts by weight of carbon black pigment was mixed with 100 parts by weight of the hydroxyl group-containing acrylic resin and MDI in total.

(Ii) Hydroxyl group-containing polyester resin (number average molecular weight 2000, hydroxyl value 40, acid value 14) and MDI
And hydroxyl group: isocyanate group = 1: 1 (molar ratio), and further phosphoric acid ester (“MP-4”) is 0.4 parts by weight per 100 parts by weight of the total hydroxyl group-containing polyester resin and MDI. It is the added paint. A mixed solvent of toluene: xylene = 1: 1 (weight ratio) was used as the organic solvent, and the solid content was adjusted to 60% by weight. In addition, carbon black pigment and hydroxyl group-containing acrylic resin and MD
5 parts by weight were mixed per 100 parts by weight in total with I.

(Iii) The phosphoric acid ester is deleted from the composition of (i) above.

(IV) A composition obtained by removing the phosphate ester from the composition of (ii) above.

II. Examples 1 and 2 and Comparative Examples 1 and 2 The coating materials (i) to (iV) for cosmetics were applied to the above-mentioned objects, and 7
It was heated at 0 ° C. for 30 minutes to be cured. The results of the performance test of the obtained coating film are also shown in Table 1.

[0030]

[Table 1]

The test method is as follows.

Adhesiveness: Cut 100 pieces of 2 × 2 mm goggles on the surface of the coating film with a knife to reach the base material, affix adhesive cellophane tape to the coating surface, and then rapidly peel it off. Then, the number of remaining streaks in the coating film was examined.

◯: 100 pieces remained, x: 80 pieces or less remained.

Chipping resistance: The test piece was mounted on a test piece holder, and crushed stones were shot at the angle of 90 ° to the coated surface under the following conditions.

(1) Test equipment: Q-G-R gravelometer (product of Q panel company), (2) Stone to be sprayed: No. 7 crushed stone, (3) Amount of stone to be sprayed: about 100 g, ( 4) Spraying air pressure: about 4.5 Kg / cm ² , (5) Test temperature: about 20 ° C.

The state of the coated surface was visually observed and evaluated according to the following criteria.

◯: Slight scratches are recognized on a part of the cosmetic coating film.

Δ: Some scratches due to impact are observed on the cosmetic coating film.

X: Many scratches due to impact are observed on the cosmetic coating film.

Weather resistance: JIS K 5400-9.8.
According to 1, in the sunshine carbon arc system, 400
This is the result of a time test.

◯: No abnormality (discoloration, blistering, etc.)

Abrasion resistance: JIS K 5400-8.9
The test was carried out in accordance with the above, and the weight loss of the coating film after 1000 rotations of the wear wheel was examined.

◯: 0.2 mg or less.

Corrosion resistance: A salt spray resistance test was conducted according to JIS K 5400-9.1. The coating film was cross-cut with a knife so as to reach the substrate as a test plate, and the coating film after the test for 10 days was observed.

◯: Slight rust generation from the cut portion, Δ: Slight rust generation from the cut portion, ×: Rust generation significantly from the cut portion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Nakamura No. 1 in Hirajyo, Miyoshi-cho, Nishikamo-gun, Aichi Prefecture Kansai Paint Co., Ltd. Address in Kansai Paint Co., Ltd. (72) Inventor Hiroaki Kiyata No. 1 flat land in Zuijoji, Miyoshi-cho, Nishikamo-gun, Aichi Prefecture Kansai Paint Co., Ltd.

Claims (1)

[Claims] 1. A coating comprising a hydroxyl group-containing resin, a polyisocyanate compound and a phosphoric acid ester as a main component is applied to a part of the surface of a cured topcoat film having a static glass transition temperature of 60 to 130 ° C. How to paint.