JPH0621243B2 - Paint composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coating composition, and more particularly to a coating composition which gives a coating film having excellent interlayer adhesion which can be suitably used particularly for coating automobiles.

Conventional technology The coating system for automobiles is the undercoating film for electrodeposition / intermediate coating film /
It is usually formed from a system such as a top coating film. In this case, it is necessary to obtain sufficient adhesiveness between the coating films, and this interlayer adhesiveness is a particularly required performance under the condition where an impact is applied.

In order to improve such interlayer adhesion, for example, a method of reducing the compounding amount of a curing agent such as a melamine resin in a coating composition for undercoating, intermediate coating and / or topcoating is used. If the blending amount is too small, the cross-linking density of the coating film will decrease, so this is not a preferred method.

It has also been practiced to add phosphoric acid to a coating composition and to use it as an undercoat in direct contact with the iron surface to react with the iron surface to enhance interlayer adhesion between the undercoat and the undercoat coating film. Further, JP-A-57-57759 discloses that dinonylnaphthalene disulfonic acid is added to an intermediate coating as a curing accelerator, and xylene sulfonic acid, paratoluene sulfonic acid, dodecylbenzene sulfonic acid, etc. are disclosed. It has been disclosed that it has been conventionally known to be compounded as a curing accelerator. However, in such a conventionally known method, it is not effective to apply the method of enhancing the adhesion between the metal material and the coating film to the multilayer coating film as it is, and the acid is merely used for promoting the reaction between the base resin and the melamine resin. It is blended for the purpose, and the adhesion of a normal multilayer coating film is good,
For example, there is a drawback in that the undercoating paint is overbaked or that it is insufficient under severe conditions in which adhesion due to chipping at a low temperature becomes a problem.

Therefore, the present invention improves the interlayer adhesion of a multilayer coating film, and particularly to not only a paint coating film using a synthetic resin as a vehicle but also a molded synthetic resin for a wide range of substrates. An object of the present invention is to provide a coating composition which gives a coating film having excellent interlayer adhesion.

According to the present invention, at least one phosphoric acid compound selected from the group of phosphoric acid dioxane adduct, phosphoric acid alkyl ester, phenyl acid phosphate and derivatives thereof and an organic solvent type A coating composition containing a thermosetting resin as a vehicle is provided.

The coating composition according to the present invention is a dioxane adduct of phosphoric acid,
At least one phosphoric acid compound selected from alkyl phosphates, phenyl acid phosphates and their derivatives is preferably contained in an amount of 0.05 to 3% by weight. A multilayer coating film having improved interlayer adhesion can be obtained by coating and baking at least the lower layer of the film according to a conventional method and then applying the upper layer coating and baking.

Examples of the phosphoric acid compound as the component (b) used in the present invention include phosphoric acid dioxane adducts, butyl acid phosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, β-chloroethyl acid phosphate, and di (2 Examples thereof include phosphoric acid alkyl esters such as -ethylhexyl) phosphate, phenyl acid phosphate and derivatives thereof.

Thus, according to the present invention, by adding a phosphoric acid compound to the coating material of the lower layer of the multilayer coating film, since a polar phosphoric acid group exists on the surface of the coating film after baking, this polar group is an upper layer. It is considered to improve the adhesion to the coating film.

According to the present invention, the phosphoric acid compound is preferably added to the coating material in an amount of 0.05 to 3% by weight. If the content is less than 0.05% by weight, the effect of improving the adhesion is not always sufficient, and if it is more than 3% by weight, the appearance of the coating film tends to deteriorate, which is not preferable. A particularly preferable blending amount is 0.2 to 1% by weight.

The coating composition according to the present invention can be produced in the same manner as a conventionally known general coating material, for example, a solid color alkyd melamine coating material for a top coating material for automobiles. All you have to do is

The coating composition according to the present invention includes, for example, an intermediate coating of a topcoat (1), a topcoat (2), a recoating of a topcoat (1), a topcoat (1), and a topcoat (2). It can be applied as a top coat (1) paint for tone painting. Examples of other paints of the above coating system include alkyd melamine paints, polyester melamine paints, acrylic melamine paints, alkyd urethane paints, polyester urethane paints, acrylic urethane paints and other thermosetting paints, chlorinated polyolefin paints and polyester resin materials. Any of the above thermoplastic paints may be used.

The coating composition according to the present invention can be suitably used for coatings for automobile bodies, as well as coatings for which a multi-layer coating film is applied to home electric appliances, metal products and the like.

Examples Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the technical scope of the present invention is not limited to these Examples.

Example 1 An intermediate coating composition having the following composition was diluted with thinner (Toluol / Solvesso 100 / Solvesso 150 = 4/3/3) (Note: Solvesso 100 and 150 ... Trademark of Exxon's aromatic hydrocarbon mixed solvent). 4 Ford cup diluted to 25 seconds, treated with zinc phosphate of size 0.8 x 100 x 300 mm, and coated on a cation-deposited dull steel plate to a thickness of 35 to 40 microns at 140 ° C. The baking was repeated for 30 minutes and then at 140 ° C. for 30 minutes twice.

On top of these coated intermediate coatings, Nippon Paint Co., Ltd. metallic paint Superlace M-90 Silver and clear paint Superlace O-28M clear are applied wet-on-wet to a thickness of 20 microns and 35 microns respectively. And baked at 140 ° C. for 20 minutes.

The coated plate thus obtained was subjected to initial speed at a temperature of -20 ° C and an angle of 45 ° using a diamond shot tester (Suga tester).
30 diamonds were applied to each coated plate at 90 km / h, 130 km / h and 170 km / h. The diamond-contacted portion was pressure-bonded with a commercially available cellophane tape, and was rapidly peeled off to peel off the coating film having weak adhesion. In this way calculate the total peeling area between the intermediate coating and the metallic coating,
The obtained results are shown in Table 1.

Example 2 A solid color paint having the following composition was prepared. First, each composition having the following dispersion composition was pigment-dispersed with Red Devil for 1 hour, and then each composition having a dissolution composition having a pigment particle size of 5μ or less was added with a grind gauge, and mixed by a disper for 15 minutes. The desired solid color paint was prepared.

A dull steel sheet having a size of 0.8 mm × 90 mm × 300 mm, which had been subjected to a conversion treatment with zinc phosphate, was further subjected to cation electrodeposition and an intermediate coating film, and the sanded product was used as a test piece for a coating test. Solvento 100: Solvesso 150 mixed in a ratio of 2: 1 to paint with a No. 4 Ford cup 25
The viscosity is adjusted in seconds, and the viscosity-adjusted solid color paints F to H are applied on the test piece to a thickness of 30 to 35 microns.
It was baked at 0 ° C for 20 minutes. Solid color paints F to I are applied on it under the same conditions without sanding.
It was baked at 20 minutes. After cooling, the adhesion between solid color coatings was tested. In the test, according to JIS K5400 6.1.5. Method, cellophane tape was pressure-bonded to the test piece and the number of remaining squares when peeled off was compared.

The results are as shown in Table 2.

Example 3 An intermediate coating composition having the following composition was prepared.

First, the dispersion formulation is pigment dispersed with red devil for 1 hour,
After confirming that the pigment particle size was 5 m or less with a grind gauge, the dispersion was taken out, the following melt-blended mixture was added thereto, and the mixture was mixed with a disper for 15 minutes to prepare an intended intermediate coating composition. .

A dull steel sheet having a size of 0.8 mm × 90 mm × 300 mm, which had been subjected to a chemical conversion treatment of zinc phosphate, was further subjected to cationic electrodeposition and an intermediate coating film, and sanded to be used as a test piece. Immediately after the production of the intermediate coating composition, this is diluted thinner (butyl acetate, toluene, methyl isobutyl ketone,
The viscosity was adjusted to 20 seconds with a No. 4 Ford cup with a mixture of cellosolve acetate in a ratio of 1: 1 :: 1: 1), and the intermediate coating composition with the viscosity adjusted was coated at 25 to 30 microns, and the temperature was adjusted to 120 ° C.
It was baked at 60 minutes. On top of that, Sonrid color paint S having the following composition was prepared without sanding, and diluted thinner (butyl acetate, cellosolve acetate 1:
(Mixture 1) was adjusted to a viscosity of 20 seconds with a No. 4 Ford cup, coated to a thickness of 30 to 35 microns, and baked at 90 ° C. for 20 minutes.

Solid color paint S compounding (parts by weight) Desmophen TP KL-2332 (Note 1) 64 Carbon black 2.3 Bayer silicone oil OL (Note 2) 0.03 Modacraw 0.01 Zn Octoate 0.06 Cellosolve acetate 15 Butyl acetate 15 Sumidule N-75 34 ( Note 1) Bayer AG polyester resin (solid content 80%) (Note 2) Bayer AG silicone oil Table 3 shows the results of interlayer adhesion between the intermediate coating and the solid color tested in the same manner as in Example 1. Show.

Effects of the Invention As described above, by using the coating composition according to the present invention, it is possible to significantly improve the interlayer adhesion between the lower layer coating film and the upper layer coating film in the coating of a multilayer coating film, such as an automobile. It is suitable as a coating material for multilayer coating film.

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Claims (1)

[Claims] 1. A vehicle containing at least one phosphoric acid compound selected from the group of phosphoric acid dioxane adducts, phosphoric acid alkyl esters, phenyl acid phosphates and derivatives thereof and an organic solvent type thermosetting resin. Coating composition.