JPH0826285B2 - Surface coating method for inorganic board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface coating method for an inorganic plate material. More specifically, in order to make the most of the coloring of the base, clear or color clear coating finish is required, and weather resistance is required. The present invention relates to a surface coating method for an inorganic plate material.

[Conventional technology]

Inorganic plate materials molded from a compound such as cement are very widely used.However, if these plate materials are left as they are, the surface coloring is grayish black to grayish white achromatic and poor in aesthetics. In addition, it is usual to carry out color coating of various colors.

[Problems of conventional technology]

By the way, the inorganic plate material is also required to have weather resistance of the coating film for the roof material, the exterior wall plate, etc., and an ultraviolet absorber is often used in the paint for this purpose, but these are very expensive. There is a problem that cost reduction cannot be achieved.

In order to solve such a problem, it is possible to use an extender pigment instead of the ultraviolet shielding agent, but since the particles generally have a spherical shape, ultraviolet rays easily pass through the gaps between the particles,
Therefore, there is a problem that deterioration due to ultraviolet rays or impartation of weather resistance is not a fundamental solution due to the degree of problem.

However, if the amount of the above particles added is increased so that no gaps are formed at all, the ultraviolet ray shielding will be complete, but the underlying color will be completely hidden, and in the case of clear coating, there is a drawback that that meaning is lost.

[Problems to be Solved by the Invention]

In view of the above problems, the present invention has been made for the purpose of obtaining a surface coating method for an inorganic plate material, which enables effective use of a base color, clear coating, and at the same time can block ultraviolet rays and can be carried out at low cost. Is.

[Technology that has solved the problem]

That is, the surface coating method of the inorganic plate material of the present invention is the same as the coating resin on the surface of the inorganic plate material made of a hydraulic material such as cement colored undercoat, and the major axis is 10μ.
The present invention is characterized in that a clear coating material or a color clear coating material is prepared by adding 0.1 to 20% of the following scale-like pigment to the coating resin.

[Action]

In the present invention, the inorganic plate material itself means a cement compound formed by a conventionally known means, and there is no particular point to note.

Further, as the background color paint applied to the surface of the plate material, a conventionally well-known one such as emulsion paint is used.

In the present invention, the clear coating of the surface of the underlying color, or as a color clear coating, has a refractive index equal to that of the coating resin, and has a major axis of 10 μm or less on the resin.
Use a clear paint or color clear paint containing 1 to 20%.

In the above, in the case of an acrylic resin as a clear paint or a color clear paint, since the refractive index is 1.40 to 1.45, the scale-like pigment, the refractive index of the resin is equivalent to
Mica, talc powder, kaolin, etc. having a refractive index of 1.55 to 1.59 are used.

These scale-like pigments have a low hiding power for the underlying color due to the refractive index, and therefore have transparency, and at the same time also shield against ultraviolet rays, the weather resistance is significantly enhanced.

The size of the particles of the scale-like pigment is 10 μm or less in major axis, and if it is larger than this, it is preferable from the viewpoint of UV shielding, but transparency is rapidly lost, and it becomes useless as a clear paint. .

Further, the addition amount of 0.1 to 20% with respect to the coating resin is that if it is less than 0.1%, there is no ultraviolet shielding effect, and if it is more than 20%, the hiding power is increased despite the particle size limitation. It becomes strong and cannot be used as a clear paint.

〔Example〕

 Next, an embodiment of the present invention will be described.

(Example) A red base coat was applied to the surface of the fiber-reinforced cement board obtained by a conventional method with an acrylic styrene emulsion paint,
A clear paint having the composition shown in Table 1 was spray-coated thereon to a thickness of 20 μm and dried in a hot air drying oven at 100 ° C for 10 minutes.

The right column of Table 1 shows Comparative Examples, Comparative Example 1 containing no scale-like pigment and Comparative Example 2 using a benzophenone-based UV absorber.

The acrylic styrene emulsion in Table 1 has a solid content of 50.
% With a refractive index of 1.40 to 1.45, and mica or talc with a refractive index of 1.55 to 1.59. The numbers in the table indicate parts by weight.

Exposure test of the above paint trial plate in Okinawa for 2 years,
Accelerated weathering test for 1000 hours with sunshine weather meter and UV transmittance of 30 for film with 12μ thickness
When the transmittance (%) at 0 nm was tested by a spectrophotometer, the results shown in Table 2 were obtained.

[Effect] As described above, the present invention is a clear paint or a color clear paint, but has a high ultraviolet shielding effect, can significantly improve the weather resistance of the coating film, and uses an expensive ultraviolet absorber. Since it does not have to be performed, there is an effect that it can be implemented at low cost.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area C08L 101/00 C09D 5/00 PPC

Claims (1)

[Claims] 1. A scaly pigment having a refractive index equivalent to that of a paint resin and having a major axis of 10 μm or less is added to the paint resin on the surface of an inorganic plate made of a hydraulic material such as cement with a base coloration in an amount of 0.1 to 20. % Of a clear paint or a color clear paint is applied to the surface of an inorganic plate material.