JP2000350962A5 - - Google Patents

Description

[Claim 1]
In a coating method in which a water-based paint is applied to the surface of a lightweight cellular concrete panel, the water-based paint has a viscosity of 1 dPa · s to 30 dPa · s immediately before the coating and a dry solid content of 50 to 80% by weight. A method for painting a lightweight cellular concrete panel, which is characterized by using a material having properties.

0002.
PROBLEM TO BE SOLVED: To apply a paint 60 to the panel surface and efficiently apply the paint 60 to the inside of the micropore 2 because a large number of micropores 2 are present on the panel surface of a lightweight cellular concrete panel (hereinafter referred to as a panel 1). A coating method is known in which the panel surface is filled without causing pinholes. For example, there is a method in which the paint 60 is sprayed onto the surface of the panel 1 with a spray gun, and then air is sprayed onto the painted surface from a nozzle having a slit-shaped outlet. (Japanese Unexamined Patent Publication No. 7-195027) At this time, in order to form a uniform thin coating film on the surface of the panel 1 having severe surface irregularities, the paint 60 can spread uniformly on the surface of the panel 1 and can stay to some extent1. Those with a low viscosity of ~ 30 dPa · s were considered to be suitable.

0004
[Means for Solving the Problem] The present inventor has studied diligently on this problem, and found that the cause of pinholes largely depends on the amount of dry solids excluding volatile components in the paint. I found. Therefore, in the coating method of applying the water-based paint to the surface of the panel , the paint properties of the water-based paint have a viscosity of 1 dPa · s to 30 dPa · s immediately before the coating and a dry solid content of 50 to 80% by weight. It was decided to use the one equipped with. The viscosity in the text is measured using a rotary B-type viscometer (manufactured by Lyon). Further, the lightweight aerated concrete panel is a panel for a building material containing cement as a raw material, which contains air bubbles and has air bubbles opened on the panel surface.

The operation of the present invention will be described below. When the viscosity immediately before application of the paint is 1 dPa · s to 30 dPa · s, a uniform thin coating film can be formed on the surface even if the panel has severe surface irregularities. Further, when the dry solid content is 50 to 80% by weight, the solid content prevents the air from rising from the inside of the micropore in the coating film in the process of drying the paint. As a result, it becomes difficult for air from the inside to reach the panel surface, and the paint bridge formed at the micropore opening remains as a coating film without breaking, so that pinholes are less likely to occur on the panel surface after drying. Become.

The present invention, on the surface of the panel 1, a coating method where the amount of dry solids with a viscosity just before coating is 1dPa · s~ 3 0dPa · s is applied to the aqueous coating 6 is 50 to 80 wt%.

By passing the panel 1 through the paint spraying step X and the air spraying step Y configured as described above, the panel 1 is painted as follows. A spray gun 7 having a discharge hole diameter of 6 mm is installed so that the distance between the lower end thereof and the surface (top surface) of the panel 1 is 30 cm. The water-based undercoat paint 6 having a viscosity of 25 dPa · s from these spray guns 7 ^{is placed on compressed air at a pressure of 4 kgf / cm 2} and applied to the surface of the panel 1. At this time, the water-based undercoat paint 6 contains 65% by weight of a dry solid content composed of an acrylic resin and an extender pigment 3, and the extender pigment 3 composed of a coloring pigment, calcium carbonate, talc, clay, and fibers is a water-based undercoat paint 6. It is a paint of an acrylic synthetic resin emulsion contained in an amount of 45% by weight.

(Comparative Example) By the same coating method as in Example, however, the undercoat paint has a viscosity of 25 dPa · s, a dry solid content of 40% by weight consisting of an acrylic resin and an extender pigment 3, and a coloring pigment, calcium carbonate, talc, etc. Using an acrylic synthetic resin emulsion paint containing 20% by weight of the extender pigment 3 composed of clay and fibers, the paint ^{was placed on compressed air at a pressure of 4 kgf / cm 2} and 1.0 kg on the surface of the panel 1. / M ^{2 was} applied. The number of pinholes on the surface of the panel 1 thus obtained after drying is also shown in Table 1.