JPS61162567A - Intercoating coating - Google Patents

Abstract

PURPOSE:To provide the titled coating made up of the primary coating and the secondary one different in the barium sulfate content each other, capable of giving laminated coating film with high smoothness and small absorption on laminating said two sorts of coatings on ion plate of, e.g., automobile. CONSTITUTION:The objective intercoating coating made up of (A) the primary coating prepared by incorporating the base pigment with 40-50wt% of barium sulfate and coloring pigment and (B) the secondary coating prepared by incorporating the base pigment with coloring pigment and 20-40wt% of barium sulfate, pref. in a weight ratio of titanium dioxide to the barium sulfate 2/1-3/1. These two components are subjected to laminated coating in putting to practical use.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for forming a laminated coating film for automobiles, etc.

In particular, it relates to a laminated intermediate coating film with excellent smoothness and low suction.

Conventional technology In automobiles, etc., an undercoat of N-coated paint is applied to the steel plate, which is the material to be coated, to ensure anti-corrosion performance, then an intermediate coat is applied to reinforce the anti-corrosion performance and ensure the finish of the top coat, and then a top coat is applied. are layered.

Improving the appearance of automobile paint using such paint systems is a major theme for each automobile manufacturer, and they are reviewing the painting process, ensuring the performance of the paint that matches the painting process, and the performance of the paint that compensates for defects in the material. is required.

The pigment composition of conventional intermediate paints is selected according to various required properties.For example, calcium carbonate has excellent coating workability, but it contains a large amount of aqueous solution and has poor moisture resistance and water resistance. In addition, it is difficult to produce gloss.

On the other hand, in order to provide chipping resistance,
No. 657.53-45813 etc. propose scale-like pigments such as talc and mica. Extender pigments with large particle sizes such as talc, mica, or aluminum silicate have the effect of preventing chipping and smoothing out the rough edges of the material, and although there is no problem with water resistance, they tend to absorb top coat paint when used in large quantities. It is difficult to obtain a coating film with excellent gloss. For example, amorphous pigments such as talc partially protrude from the surface of the intermediate coat and absorb resin from the top coat, reducing gloss.

Therefore, it has conventionally been difficult to satisfy both the improvement of smoothness and the prevention of suction.

Problems to be Solved by the Invention The present invention improves the defects of the coated material due to the intermediate coating film, which could not be solved by the above-mentioned prior art, and also improves the coating by preventing the suction and flow of the top coat. The objective is to form a laminated coating film with excellent film smoothness and gloss.

The body of an automobile is basically represented by a horizontal part and a vertical part.

Especially in the horizontal areas, the roughness and undulations of the iron plate material are easy to stand out, and to what extent can we smooth out the roughness that cannot be covered with electrodeposition paint or undercoat?

Another issue is how much the intermediate coat can absorb the top coat.

On the other hand, the topcoat has a larger contribution to the finish of the vertical parts, but
The intermediate coating should also be smooth, and the intermediate coating should not run easily, which is also a condition for obtaining a good finish.

In the present invention, the undercoat is a cationic or anionic electrodeposition paint, and the topcoat is a conventionally known solid type alkyd/melamine resin paint or a metallic type made of acrylic resin.

Intermediate paints generally used for automobile painting use polyester resins, melamine resins, and epoxy resins as vehicles, and the same applies to the present invention.

The present inventor studied pigments such as barium sulfate, titanium, and talc and found the following advantages.

The most important pigment in the present invention is barium sulfate, and barium sulfate has good water resistance because it has a small amount of aqueous solution, has a large particle size, is almost spherical in shape, and has a small specific surface area and oil absorption ( Table 1) It was found that the suction of the top coat was small and the scratch hiding properties of the coated object were good.

Margin Table 1-(1) Below Margin Table 1-(1) There are many types of barium sulfate as commercial products, but among them, those with an average particle size of about 0.1 to 0.3μ (Sakai Kagaku Variace B- 30) is most effective for the present invention. Barium sulfate BF-1,8F- finer than Variace 8-30
No. 10, BF-20, etc. do not absorb the topcoat and can be used in combination with Variace B30, but they are not sufficient for the purpose of improving the appearance because they do not have the ability to hide scratches on the object to be coated. It is presumed that a pigment having a particle size close to 0.15μ is suitable for the purpose of the present invention because it is suitable for filling the undulations of the material.

If the particle size is smaller than this, it will have little effect on smoothing the roughness of the material, and if it is too large, the coating surface will become rough and the suction of the top coat will increase, which is not preferable.

Coloring pigments include organic pigments such as cyanine blue, permanent red, and Hansa yellow, and inorganic pigments include carbon black and Bengara. Among them, titanium is the best, and any known type used in ordinary intermediate coatings and top coatings may be used. However, if weather resistance is required as an intermediate coat, the rutile type is preferred over the anatase type.

Further preferred is titanium produced by the chlorine method.

Among the above-mentioned pigments, barium sulfate has the best ability to hide scratches on objects to be coated, and its ability to absorb top coat paint is comparable to that of titanium. The reason for this is that barium sulfate has a slightly smaller particle size than titanium and has a relatively spherical shape, so it has a relatively small specific surface area.

The ratio of titanium to barium sulfate contained in the second intermediate coating is 2:1 to 3:1, which improves the appearance the most, and the reason why this range is most effective is that this ratio is close-packed. It is considered that it will be a combination.

If necessary, add 2 to 1 part of talc to every pigment valve in the paint.
0χ can be blended. If there is too little talc, the adhesion with the top coat will be poor, and if there is too much, the appearance will deteriorate.

First, talc is mainly effective in hiding scratches on the coated object and improving adhesion between the intermediate coat and top coat. Average particle size is 90% of primary particles
The average particle size is preferably less than 5μ, preferably 2 to 5μ.
It is good to have something of a certain degree. If a pigment with a large particle size is used in large amounts, it will be difficult to obtain a smooth skin, and if a small amount is used, it will be difficult to obtain an effect on the adhesion between the intermediate coat and the top coat.

As mentioned above, in the present invention, the type and amount of pigment used are most important.

The above-mentioned barium sulfate, titanium, and talc can be used in combination with other pigments, and it is also possible to introduce coloring pigments for the purpose of coloring, or to design a color intermediate coating that does not contain titanium at all.

It is necessary that the barium sulfate content in the first and second intermediate coatings composed of the above-mentioned pigment and vehicle be 40 to 50% by weight.

If it is less than 40% by weight, the effect of hiding scratches on the coated object will be poor;
If it exceeds 50% by weight, precipitation tends to occur and storage stability is poor.

The second intermediate coating needs to contain 20 to 40% by weight of barium sulfate.

If it is less than 20% by weight, the effect of hiding scratches on the object to be coated will be low, and if it exceeds 40% by weight, it will tend to settle and have poor storage stability, and the top coat will absorb more.

The first and second intermediate coats and the second intermediate coat, which are composed of pigments and vehicles, can be easily made into paints using a conventionally known SG mill.

In order to achieve a smooth finish, the intermediate coating material produced in this manner needs to be applied with good atomization, and it is preferable to apply it by air spray, mini-bell, or the like.

It is necessary to apply two coats and two bakes of the first intermediate coat paint and the second intermediate coat paint of the present invention, and wet
It cannot be fully effective when wet.

The effect of applying the intermediate coat of the present invention twice is that the first intermediate coat has the ability to hide scratches on the object to be coated, and the second intermediate coat has the function of eliminating topcoat suction.

It was most effective for the appearance to apply 40μ or more for the first intermediate coat and 30μ or more for the second intermediate coat.

*1 Almatex C3P-40260 manufactured by Mitsui Toatsu Co., Ltd.
% varnish was used.

*2 Super Hetsukamin G manufactured by Dainippon Ink and Chemicals
-821-6060%') It is for Niswo.

*3 Epicoat 1001 manufactured by Shell Chemical Industries *4 Mixed solvent of xylene: ethyl acetate: n-butanol = 1:1:1 *520" gloss JIS-54006,7 *6 manufactured by Nippon Paint Co., Ltd. Image sharpness measurement Machine*1 surface roughness meter S
urrcom Model 5uRFO7B*8 Adhesion An intermediate coating was applied on the electrodeposited film and baked at 140°C for 30 minutes. On this coating film, a non-sand red metallic paint was applied at 2c/lb and baked at 140°C for 30 minutes. This coating film was measured at -20℃ using a gravelometer at an angle of 4.
5'', 100 g of No. 7 crushed stone, and adhesion test results between intermediate coat and top coat at 2 Ky air pressure.

Table 2 Paint (Formulation) 1 to 3 Table 3 Comparison (Formulation) 1.2 Example 10
Apply Power Top tJ-30 (electrodeposition paint made by Nippon Paint Co., Ltd.) to a steel plate with air spray at a dry film thickness of 3.
It was coated with a thickness of 5 to 40μ and baked at 140°C for 30 minutes.

In addition to this, paint (formulation) 1 to 3, and comparison (formulation) 1 to
Apply 2 to 30-40μ of the first and second intermediate coats using air spray.
, apply 30 to 40μ of secondary intermediate coating, and heat at 140℃
I baked it separately.

In addition, super laminated paint is used as a top coat and as a base coat.
-Tsuku Open-12 red metallic paint, superlac 0-70 clear (acrylic resin paint made by Nippon Paint Co., Ltd.) as a clear coat (at 2 c/lb) 20/3
A test piece was prepared by painting 0μ. The performance of the coating film subjected to rqi according to the method of the present invention was measured for the following items.

To determine the degree to which the intermediate coat fills in the roughness of the base and contributes to the finished appearance, we use a surface roughness meter to determine the scratch hiding ability of the base, and to determine the degree to which the top coat is absorbed into the intermediate coat, we measure 20° gloss, smoothness, and brightness. NPIG whose image quality is most similar to visual appearance
Values and intermediate coat/top coat adhesion were measured.

Table 4 Evaluation Results Example ◎ Comparative Example with No Abnormality In addition, it has become possible to achieve both contradictory performance requirements that could not be achieved in the past, such as preventing suction and improving the appearance of the topcoat film.

Claims (1)

[Claims] 1. 40 to 50% by weight of barium sulfate in the pigment of the paint
and a first intermediate coating containing a colored pigment, and a second intermediate coating containing a colored pigment and 20 to 40% by weight of barium sulfate in the pigment content of the coating. 2. The laminated coating film according to claim 1, wherein the blending ratio of titanium and barium sulfate contained in the second intermediate coating is 2:1 to 3:1.