JPS6127356B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a decorative asbestos cement board having a colored layer on its surface. There are wet methods and dry methods for manufacturing asbestos cement boards. In the wet method, the method of forming a colored layer on the surface of an asbestos cement board is to add a coloring agent to the paper-made cylinder butt, which is the method that adds color to the raw board immediately after paper-making. Methods such as applying slurry by spraying are used, but no matter which method is used, the ratio of kneading water in the colored slurry is too large, resulting in a colored layer that is thin and has a low density. At most
The limit was 0.05 to 0.1 mm. The decorative asbestos cement board formed by the wet method has a thin colored layer and a low density, so it has poor weather resistance and abrasion resistance, and has high moisture permeability and is easily warped. On the other hand, in the dry method, in order to form a colored layer on the surface of an asbestos cement board, the amount of asbestos in the colored layer must be increased and the thickness must be increased, otherwise a uniform and good colored layer cannot be obtained, resulting in high costs. The present invention has been made in view of the above points, and its purpose is to reduce the proportion of kneading water in the colored slurry by preparing the colored slurry by adding a water reducing agent. The colored slurry with high water content can form a thick and dense colored layer on the surface of the asbestos cement board, and coating the surface of the asbestos cement board with a thick and dense colored layer improves weather resistance and abrasion resistance. Provided is a method for manufacturing a decorative asbestos cement board, which can improve the surface temperature of the board, and also prevent the occurrence of warping due to a decrease in moisture permeability on the surface side because the surface is dense with a colored layer, and further reduce the cost of the colored layer. There is something to do. The present invention will be explained in detail below. First, cement, granulated blast furnace slag, pigment, kneading water, and water reducing agent are mixed into the pulverized product obtained by pulverizing short fiber asbestos and asbestos cement board, and if necessary, silica powder is added to give a color with a low water content. Prepare slurry. This colored slurry contains a water-reducing agent, which reduces the interfacial tension between the mixing water and cement or asbestos, increasing the dispersion and wetting effects of the mixing water. It is possible to prepare a low water content by reducing the proportion of kneading water in the colored slurry, and because of the water reducing agent, the colored slurry can be kneaded uniformly, and the colored slurry that has been hardened has a high density and strength. It has become possible to improve weather resistance and moisture permeation prevention properties. Further, as the water reducing agent to be added to the colored slurry, lignin sulfonate, other sulfonate, polyoxyethylene alkyl allyl ether, polyol complex, etc. can be used. A slurry prepared by kneading cement, asbestos, fibrous materials, etc. is formed into a plate using a paper-making machine to form a raw board made of asbestos cement using a wet process, and then the above-mentioned colored slurry is applied to the surface of the raw board before hardening. A colored layer is applied to almost the entire surface of the raw board by spraying, etc., and then dehydrated by a press to integrate the raw board and the colored layer, and then the raw board and the colored layer are cured and hardened. As shown in the attached diagram, a decorative asbestos cement board is obtained in which the surface of the asbestos cement board 1 is coated with a colored layer 2 that is thicker and has a higher density than the asbestos cement board 1, and the obtained decorative asbestos cement board is used for roofing. It is used as wood and wall material. 3 in the figure is a resin layer when the surface is coated. As mentioned above, by adding a water reducing agent to the colored slurry, the interfacial tension between the kneading water in the colored slurry and cement or asbestos is reduced and the dispersion and wetting effects of the kneading water are enhanced, thus increasing the coloring. Slurry can be prepared to have a low water content by reducing the blending ratio of kneading water. In addition, the uniformity of the colored slurry can be improved because of the water reducing agent, and the hardened colored slurry has a high density and can improve strength, weather resistance, and moisture permeation prevention properties. Since the colored layer 2 is formed on the surface of the asbestos cement board 1 using the colored slurry with a low water content having the above features, the surface of the asbestos cement board 1 is thicker than that formed with the conventional colored slurry with a high water content. Moreover, it is coated with a colored layer 2 with a higher density than the asbestos cement board 1, and therefore, the surface side of the decorative asbestos cement board has a thick and high density colored layer 2, so it has poor weather resistance and abrasion resistance. In addition, since the surface is dense with the high-density colored layer 2, the moisture permeability from the surface side is reduced and the occurrence of warping can be prevented. Furthermore, by adding a water reducing agent to the colored slurry, it becomes possible to use a pulverized asbestos cement as the main component of the colored slurry, and the colored layer 2 can be provided at low cost. In the present invention, since the colored slurry is prepared by adding a water reducing agent as described above, the proportion of kneading water in the colored slurry can be reduced, and the colored slurry with a low water content can be coated thickly on the surface of the asbestos cement board. A high-density colored layer can be formed, and the surface of the asbestos cement board can be covered with a thick, high-density colored layer, so the weather resistance and abrasion resistance of the decorative asbestos cement board can be improved. Furthermore, since the surface is dense with the colored layer, the moisture permeability of the surface side is reduced, thereby preventing the occurrence of warping, and further reducing the cost of the colored layer. Furthermore, by applying a colored slurry to the surface of the asbestos cement raw board formed by a wet method and integrating it, the adhesion of the colored layer can be improved. The present invention will be specifically explained below using examples. Examples 1 and 2

【table】

[Table] The colored slurry shown in Table 1 (Example 1) and the colored slurry shown in Table 2 (Example) were sprayed onto the surface of an asbestos cement raw board made by a wet method to form a colored layer on the surface of the raw board. The asbestos cement board 1 was formed and then dehydrated in a press to integrate the green board and the colored layer, and then cured and hardened to obtain a decorative asbestos cement board having a colored layer 2 on the surface of the asbestos cement board 1 as shown in the attached figure. The thickness of the asbestos cement board 1 obtained in Examples 1 and 2 was 5.0 to 5.5 mm and the density was 1.6, and the thickness of the colored layer 2 was 0.2 to 0.5 mm and the density was 20. Example 1,
Table 3 shows the moisture permeability of the decorative asbestos cement board No. 2 and the conventional asbestos cement board.

【table】

[Table] As is clear from Table 3, the moisture permeability of the decorative asbestos cement boards of Examples 1 and 2 was much lower than that of the conventional ones, and the weather resistance and abrasion resistance were also excellent.

[Brief explanation of the drawing]

The attached drawing is a partial cross-sectional view of a decorative asbestos cement board obtained in one embodiment of the present invention, in which 1 is an asbestos cement board, 2 is a colored layer, and 3 is a resin layer.

Claims (1)

[Claims] 1. Prepare a colored slurry with a low water content by blending asbestos, pigment, kneading water, and water reducing agent with cement, and apply the above colored slurry to the surface of an asbestos cement green board formed by a wet method to form a colored layer. A method for manufacturing a decorative asbestos cement board, which comprises: dehydrating the board to integrate the green board and the colored layer; and curing and curing the board.