JPH0368911B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a repairable light-colored solid paint, more specifically a beige based on a melamine alkyd resin paint for use as a top coat;
This relates to yellow solid paint.

[Conventional technology]

BACKGROUND OF THE INVENTION When painting exterior panels of automobiles, paint defects often include lumps called lumps in the paint film, or so-called sag, which is caused by dripping and solidifying paint fluid. In order to repair these paint defects, polishing repair has traditionally been performed, for example, by removing most of the spots and sagging using a grindstone, etc., and then repairing using a paste or liquid abrasive containing abrasive grains. .

[Problem to be solved by the invention]

However, this polishing repairability differs depending on the presence or absence of pigment in the paint and the difference in color tone. For example, in the case of a clear paint that does not contain pigments, it is easy to repair by polishing, or among solid paints that contain pigments, dark-colored paints such as black will have noticeable polishing scratches, but they can be repaired with some effort. However, light-colored paints such as beige or yellow leave polishing marks that cannot be repaired no matter how much effort you put into it. Especially in the case of beige paint, polishing marks are easily visible and can easily become a problem. Conventionally, countermeasures against such poor polishing include (a) increasing the melamine ratio in the melamine alkyd resin, which is a paint component, to make the paint film harder and less susceptible to polishing scratches, and (b) making the paint harder to scratch. Methods such as reducing the amount of carbon in the paint to make defects less visible were taken, but they were not very effective and repairs could not be done with beige or yellow solid paints, and repainting was often required.

Means for Solving the Problems The present invention is intended to solve the problems of the prior art described above. The purpose is to provide beige and yellow light colored solid paints that are less susceptible to scratches during polishing and repair. The light color solid paint of the present invention is a melamine alkyd resin paint for use as a top coat, and when the solid content of the paint is 100% by weight, (1) For beige paints, the following pigment composition: 20% by weight < Titanium oxide＜22wt% 0.1wt%≦Iron oxide yellow and red＜
3% by weight 0.1% by weight≦Carbon<1% by weight (2) For yellow paints, the following pigment composition: 23% by weight<Titanium oxide<25% by weight 1% by weight<Iron oxide yellow<8% by weight 0% by weight< It is characterized by carbon <0.1% by weight. The present inventors found that in the case of beige and yellow solid paints, abrasive scratches caused by polishing repairs are mainly caused by the falling off or exposure of the titanium oxide pigment contained in the paint from the paint film surface; The present invention was achieved by discovering that there are few scratches on the surface of the resin component. Therefore, modification of the resin, such as an increase in the melamine ratio, only has a negative effect on the physical properties and is hardly effective in reducing polishing scratches, and the concentration and dispersibility of the titanium oxide pigment pose problems. The dispersibility of titanium oxide pigments decreases as the concentration increases, and even if the titanium oxide pigment is uniformly dispersed in the paint liquid, agglomeration may occur when the melamine alkyd resin solidifies. Countermeasures using titanium surface treatment are also difficult. Therefore, lowering the concentration of titanium oxide pigment is a simple and effective method. The present inventors have discovered the hiding properties, impact resistance, and
After considering various physical properties such as adhesion, we investigated various paint formulations and found that under the following conditions, the polishing marks were less noticeable and the polishing repairability was good. That is, among light-colored solid paints based on melamine alkyd resin paints (this is used, for example, for top coating of automobile bodies), beige and yellow solid paints have the above structure,
In addition, if possible, all pigments are blended so that the thickness of the hiding film in the JIS K5400 paint film hiding test (using white and black standard hiding paper) is 40μ or less. In the beige and yellow solid paints of the present invention, if the amount of the titanium oxide pigment exceeds the above numerical range, scratches will become noticeable when the paint film is repaired; If it is lower than that, the concealability will deteriorate. Furthermore, if the amounts of the iron oxide pigment and the carbon pigment are outside the respective numerical ranges, preferred color tones for both beige and yellow colors will not be produced. The melamine alkyd resin and each pigment used in the light solid paint of the present invention may be selected from among commonly used ones (for example, commercially available products).

[Effect]

By setting the optimum pigment composition for beige and yellow light solid paints based on melamine alkyd resin paints,
Polishing and repairability can be improved while maintaining hiding properties and color tones equivalent to those of conventional paints of the same type. Figures 1 and 2 show examples of the effect of titanium oxide content on polishing repair, where the titanium oxide content contained in the paint film is 5% or less (5% as an example) and 30% or more (5% or more as an example). As an example, an example of the sample polished surface in the case of 45%) is shown. When the titanium oxide content is low, only resin polishing scratches 1 are produced on the coating film surface, and when it is high, resin polishing scratches 1 and traces 2 of falling titanium oxide are produced. If the surface is repeatedly polished, the polishing scratches 1 on the resin will disappear, but the traces 2 of the titanium oxide falling off will not disappear. The polishing repair was carried out in the following manner and order. Removing blemishes with a whetstone → Rough sharpening with a powdered abrasive → Finishing with a liquid abrasive

【Example】

The present invention will be explained in more detail with reference to the following examples and comparative examples. Example 1 Production of beige paint The following paints were used as components. Each paint consists of a melamine alkyd resin, a pigment (not included in the diluted paint), and a solvent. (a) Paint containing titanium oxide, solid content 70% by weight (including 50% by weight pigment) (b) Paint containing iron oxide yellow, solid content 60% by weight (including 16.7% by weight pigment) (c) Paint containing iron oxide red, solid content 60 Weight% (of which pigment is 16.7% by weight) (d) Carbon-containing paint Solid content 60% by weight (of which pigment is 4.8% by weight) (e) Diluted paint Solid content (melamine alkyd resin only) 60% by weight Above component (a) 262.0 parts by weight, component (b) 72.5 parts by weight,
3.9 parts by weight of component (c) and 13.9 parts by weight of component (d) were mixed and kneaded, and further 331.8 parts by weight of component (e) were mixed and thoroughly kneaded to obtain the beige paint of the present invention. Example 2 Production of yellow paint The following paints were used as components. Each paint consists of a melamine alkyd resin, a pigment (not included in the diluted paint), and a solvent. (a) Paint containing titanium oxide 70% by weight solids (of which 50% by weight is pigment) (b)′ Paint containing yellow iron oxide 60% by weight solids (33.3% by weight of pigment) (d) Paint containing carbon 60% by weight solids % (including 4.8% by weight of pigment) (e) Diluted paint Solid content (melamine alkyd resin only) 60% by weight Component (a) 244.3 parts by weight, component (b) '72.5 parts by weight,
Mix and knead 0.5 parts by weight of component (d), and then add component (e).
219.2 parts by weight were mixed and thoroughly kneaded to obtain the yellow paint of the present invention. Comparative Example 1 Production of beige paint The same paints as in Example 1 were used as components. 262.9 parts by weight of component (a), 71.6 parts by weight of component (b),
2.9 parts by weight of component (c) and 10.4 parts by weight of component (d) were mixed and kneaded, and further 164.1 parts by weight of component (e) were mixed and thoroughly kneaded to obtain a beige paint of a comparative example. Comparative Example 2 Manufacture of yellow paint The same paints as in Example 2 (component (c)
(excluding) were used. Mix and knead 234.0 parts by weight of the component (a) and 90.5 parts by weight of component (b), and further mix 204.8 parts by weight of component (e),
The mixture was sufficiently kneaded to obtain a yellow paint of a comparative example. Performance evaluation test Each of the paints of Examples 1 and 2 and Comparative Examples 1 and 2 was spray-painted onto a specified sheet to a dry film thickness of 30 μm, left at room temperature for 10 minutes, and then baked at 140°C for 30 minutes. Each test coating was obtained. Tables 1 and 2 show the pigment compositions and coating film appearance evaluation results of the present invention examples and conventional examples for beige and yellow paints.

【table】

[Table] In addition, a polishing repair test was conducted on the resulting coating film. Polishing repair was carried out in the following manner and order. Remove blemishes with a whetstone → Rough sharpen with a kneaded abrasive → Finish with a liquid abrasive (containing abrasive grains) Sample pieces polished after applying beige paint are shown in Figure 3 (Comparative Example 1) and Figure 4 (Example) Shown in 1). Compared to FIG. 3, in FIG. 4, the number of traces of titanium oxide falling off on the polished surface was reduced by half, and it was found that the surface condition, that is, the smoothness, had improved to a level that did not cause any problems even by visual evaluation.

【Effect of the invention】

As mentioned above, the light solid paint of the present invention has the same hiding power and color tone as conventional paints of the same type.
Furthermore, by using the paint of the present invention, it was possible to easily obtain a paint film with fewer scratches on the polished surface of the paint film and with an excellent appearance even after polishing and repair. In addition, the light solid paint of the present invention can lower the pigment concentration in the paint compared to conventional similar paints, which has a secondary cost reduction effect, and also increases the resin content in the paint film. The gloss, sharpness, weather resistance, impact resistance, and adhesion of the coating film have also been improved.

[Brief explanation of drawings]

Figure 1 is a plan view showing a polished surface of a paint film with a titanium oxide content of 5% or less (5% as an example), and Figure 2 is a plan view showing a polished surface of a paint film with a titanium oxide content of 30% or more (an example is 45%).
%), FIG. 3 is a plan view showing a conventional polished surface of a beige-based paint film, and FIG. 4 is a plan view showing a polished surface of a beige-based paint film of the present invention. In the figure, 1...Resin polishing scratches, 2...Titanium oxide falling marks.

Claims (1)

[Claims] 1. In a melamine alkyd resin paint for use as a top coat, when the solid content of the paint is 100% by weight, (1) For beige paints, the following pigment composition: 20% by weight < oxidation Titanium<22wt% 0.1wt%≦Iron oxide yellow and red<
3% by weight 0.1% by weight≦Carbon<1% by weight (2) For yellow paints, the following pigment composition: 23% by weight<Titanium oxide<25% by weight 1% by weight<Iron oxide yellow<8% by weight 0% by weight≧ A light colored solid paint characterized by carbon <0.1% by weight.