JPH09286010A - Production of inorganic cement panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold the continuity of a green sheet even when a highly conc. slurry is formed into a sheet shape by a papermaking method to obtain an inorg. cement panel good in texture by forming the green sheet from the highly conc. slurry by a papermaking method and sprinkling a low conc. slurry over the green sheet at a time of dehydration. SOLUTION: When felt 1 is sent to allow a highly conc. slurry to flow out of a flow box 3, a green sheet 2 is continuously fed by the felt 1 while sucked and dehydrated in a suction zone 5. When the green sheet 2 is fed by the felt 1, a low. conc. slurry 7 is sprinckled over the green sheet 2 from a hopper 6 and allowed to flow in the material exhausted parts or nest parts of the green sheet 2 to hold the continuity of the green sheet 2. The green sheet 2 is sucked and dehydrated to be adjusted to a predetermined water content and subsequently formed into a predetermined shape by a press and aged in an autoclave to form an inorg. cement panel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an inorganic cement board used as a building material such as a roof tile or an exterior material.

[0002]

2. Description of the Related Art Conventionally, when an inorganic cement board is manufactured, a green sheet is formed by making a slurry containing a cement and an aggregate as a main component and a fiber component mixed therein, and the green sheet is sucked and dehydrated while being conveyed. It was designed to lower the water content.

[0003]

By the way, in the manufacturing method as described above, when a high-concentration slurry is continuously formed into a green sheet and dehydrated while the green sheet is conveyed, the material of the green sheet is It is the current situation that the slurry concentration cannot be increased because of the discontinuity of the powder and the deterioration of the surface texture.

The present invention has been made in view of the above points, and an object of the present invention is to obtain a green sheet which maintains the continuity of a green sheet even when a high concentration slurry is produced.

[0005]

In order to solve the above problems, the method for producing an inorganic cement board according to the present invention is a method for producing an inorganic cement board by making a slurry containing a cement and an aggregate as a main component and a fiber component. In the method for producing the above, after a high-concentration slurry is formed into a green sheet and then the green sheet is dehydrated, a low-concentration slurry is sprinkled on the green sheet. By spraying a low-concentration slurry onto a green sheet formed by making a high-concentration slurry, it is possible to reduce the defects in the green sheet by filling the cut parts and cavities of the green sheet with the low-concentration slurry. Therefore, it is possible to obtain a green sheet which maintains the continuity and has a good texture.

[0006]

1 shows an apparatus for producing an inorganic cement board. Reference numeral 1 is a felt for making a slurry and carrying the paper-made green sheet 2. Reference numeral 3 is a flow box for letting out the slurry, and a high-concentration slurry 4 is loaded inside. This high-concentration slurry 4 has a solid content of 30 to 70% by weight. Reference numeral 5 denotes a suction zone arranged below the felt 1, which sucks and dehydrates the green sheet 2. Reference numeral 6 is a hopper for spraying the slurry, and is loaded with a low-concentration slurry 7. This low-concentration slurry 7 has a solid content of 10% by weight or less.

However, when the felt 1 is sent and the high-concentration slurry 4 is flown out from the flow box 3, the green sheet 2 is continuously made into paper, and the green sheet 2 is conveyed by the felt 1 and sucked from the suction zone 5. Be dehydrated. When the green sheet 2 is conveyed by the felt 1, the low-concentration slurry 7 is sprayed from the hopper 6, and the low-concentration slurry 7 is poured into the material cut portion or the nest portion (pulp rich portion) of the green sheet 2, Continuity is imparted to the green sheet 2. Then, the green sheet 2 is sucked and dehydrated to have a predetermined water content. After that, the green sheet 2 is molded into a predetermined shape by a pressing device and cured by autoclave curing or the like to form a molded body of an inorganic cement plate.

In the above embodiment, the green sheet 2 is made into paper by pouring out the high-concentration slurry 4 from the flow box 3. However, in other paper making machines such as a Fourdrinier paper making machine. The green sheet 2 may be made into paper.

[0009]

[Example] Cement, silica sand, and silica sand powder were mixed at a weight ratio of 4: 1: 3, and pulp was added at a ratio of 5% by weight, and water was added to the mixture to prepare a high-concentration slurry. did. This high-concentration slurry is charged on the felt from the flow box with a Minitest paper machine to make green sheets, and in the dehydration process of the green sheets, the low-concentration slurry is poured onto the green sheets and dehydrated.
It was pressed at kgf / cm ² , and autoclaved at 170 ° C. for 5 hours to obtain a molded body. Bending strength and frost damage resistance (ASTM-A method) of this sample were measured. Table 1 shows the results.

[0010]

[Table 1]

From these results, the paper made with the high-concentration slurry has many defects and is inferior in strength and durability. However, by pouring the low-concentration slurry into the paper, the defects are reduced and sufficient strength and durability are obtained. You can see that you can get it. Further, as the pulp in the low-concentration slurry to be added later, a hardwood pulp having a relatively short fiber length is suitable, and it is understood that adding sepiolite is effective.

[0012]

As described above, according to the present invention, since a low-concentration slurry is sprayed on a green sheet formed by forming a high-concentration slurry into paper, a material cut portion or a nest portion of the high-concentration slurry green sheet is removed. Even if it is possible to reduce defects in the green sheet by filling it with a low-concentration slurry and improve productivity by forming the green sheet with a high-concentration slurry, it is possible to maintain the continuity of the green sheet and It is possible to obtain a product having a good texture, and since there are few defects in the green sheet, it is possible to obtain a product having strength and durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a manufacturing apparatus for explaining a manufacturing method of the present invention.

[Explanation of symbols]

 2 Green sheet 4 High concentration slurry 7 Low concentration slurry

Claims (1)

[Claims] 1. A method for producing an inorganic cement board by making a slurry containing a fiber component containing cement and an aggregate as main components, and forming a green sheet by making a high-concentration slurry, and then forming a green sheet. A method for producing an inorganic cement board, which comprises spraying a low-concentration slurry on a green sheet when dewatering the.