JPH081631A - Gypsum board manufacturing method - Google Patents

Abstract

(57) [Summary] [Structure] A gypsum kneaded material for forming an outer layer is supplied onto the belt conveyor 4 to form a first layer 11, and a gypsum kneaded material containing bubbles is supplied onto the first layer 11. Then, the second layer 12 is formed, and the gypsum kneaded product for forming the outer layer is further supplied thereon to form the third layer 13, and then the gypsum is cured. Third
A heater 10 is provided so that the layer can be heated from above. [Effect] A gypsum board with extremely small warpage can be efficiently manufactured in a short time.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing gypsum board, and more particularly to a method for producing a gypsum board having a three-layer structure. 2. Description of the Related Art A gypsum board having a three-layer structure is such that a lightweight intermediate layer 2 containing air bubbles is interposed between a pair of dense outer layers 1 and 3 as shown in FIG. is there. As shown in FIG. 2, this gypsum board having a three-layer structure supplies a gypsum kneaded material for forming an outer layer onto a belt conveyor 4 to form a first layer 11, and the gypsum board is formed on the first layer 11. Supplying a gypsum kneaded material containing bubbles to form a second layer 12, and further supplying a gypsum kneaded material for forming an outer layer thereon to form a third layer 13, and then hardening the gypsum. Is manufactured by. The gypsum kneaded product for forming the outer layer is obtained by kneading calcined gypsum, glass fiber and water in the mixer 5. The gypsum kneaded material for forming the intermediate layer is a material in which bubbles are supplied to the kneaded material so as to contain air bubbles. The bubbles are formed by stirring a mixed liquid of polyvinyl alcohol (PVA) and water together with air in the foaming machine 6 to foam. Reference numerals 7, 8 and 9 in FIG. 2 denote plates (forming spatula) for pressing and kneading the kneaded material. [0007] According to the above-mentioned conventional method for manufacturing a gypsum board, there is a problem that the manufactured gypsum board is easily warped or peeled. That is, when the gypsum kneaded product hardens, the gypsum expands. However, when the first, second and third layers are laminated at different times as shown in FIG. 2, the first layer is hardened to some extent. After the progress, since the third layer is supplied on the second layer, the third layer continues to expand even when the first layer is terminated (the curing reaction is completed), and as a result, the third layer is the first layer. Will spread more than. As a result, a warp in which the third layer side is convex and the first layer side is concave is likely to occur. In addition, peeling between layers easily occurs. A method for producing a gypsum board according to the present invention is a gypsum board having a three-layer structure in which a lightweight intermediate layer containing bubbles is interposed between a pair of dense outer layers. A method for producing, wherein a gypsum kneaded product for forming an outer layer is supplied onto a conveyor to form a first layer, and a bubble-containing gypsum kneaded product for forming an intermediate layer is supplied onto the first layer to form a second layer. Further, in the method for producing a gypsum board in which a gypsum kneaded product for forming an outer layer is further supplied onto the second layer to form a third layer, the third layer is heated by a heater from above to cure the third layer. It is characterized by promoting. According to the method for producing a gypsum board of the present invention, since the hardening of the third layer is promoted, the end points of the first layer and the third layer coincide or come close to each other, and Warpage is prevented. Further, the production line can be shortened as much as the termination of the third layer is accelerated. FIG. 1 is a sectional view for explaining the method of the embodiment, in which a heater 10 is provided so that the third layer can be heated from above. The other configuration of FIG. 1 is the same as that of FIG. 2, and the same reference numerals are given to the same portions and the description thereof will be omitted. By providing the heater 10 as described above, the hardening of the third layer is promoted, so that the finish times of the first layer and the third layer coincide or come close to each other, and warp of the gypsum board is prevented. become. Further, the production line can be shortened as much as the termination of the third layer is accelerated. In the present invention, a setting retarder may be added to the first layer 11 and a hardening accelerator may be added to the third layer. However, since the heater 10 is provided, a gypsum board having high flatness can be manufactured without using such an additive. A specific manufacturing example will be described below. Example 1 Width 600 mm, thickness 60 mm, outer layer thickness 5 m each
A gypsum board having a thickness of m and an intermediate layer thickness of 50 mm was manufactured as shown in FIG. 1 using the following materials. The following composition is the composition amount per 2.4 m of gypsum board. Composition of outer layer: 10 kg of gypsum, 9 kg of water, 50 g of glass fiber Composition of intermediate layer: 10 kg of gypsum, 8 kg of water, 1 glass fiber
00g, PVA 10g Belt conveyor feed rate: 1.8m / min Heater: 85mm away from the top surface of the third layer, total output 12
A kW heater is installed. As a result, a gypsum board with almost no warp could be manufactured. In addition, the temperature in the third layer was measured by a thermocouple to
The termination time in the layer was measured and found to be 15 minutes. Comparative Example 1 A gypsum board was manufactured in the same manner as in Example 1 except that the heater was stopped. The obtained gypsum board had a maximum warp of 8 mm at 4 m. Also, the closing time of the third layer is 2
It was 1 minute. As described above, according to the method for producing a gypsum board of the present invention, a gypsum board having a very small warp can be produced efficiently in a short time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a method for manufacturing a gypsum board according to an embodiment. FIG. 2 is a cross-sectional view showing a method for manufacturing a gypsum board according to a conventional example. FIG. 3 is a cross-sectional view of a gypsum board [Description of symbols] 1,3 Outer layer 2 Intermediate layer 5 Mixer 6 Foaming machine 10 Heater 11 First layer 12 Second layer 13 Third layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number of the agency FI Technical indication location // E04F 13/14 102 A 9127-2E (72) Inventor Toshiaki Kakinuma 1 Kitabukurocho, Omiya City, Saitama Prefecture 297-chome, Mitsubishi Materials Corporation Cement Research Center

Claims (1)

What is claimed is: 1. A method for producing a gypsum board having a three-layer structure in which a lightweight intermediate layer containing air bubbles is interposed between a pair of dense outer layers, which conveys a gypsum kneaded product for forming an outer layer. Is supplied to the above to form a first layer, the bubble-containing gypsum kneaded product for forming an intermediate layer is supplied to the first layer to form a second layer, and the gypsum kneaded product for forming an outer layer is further formed on the second layer. A method for producing a gypsum board that is supplied to form a third layer, wherein the third layer is heated from above by a heater to accelerate the hardening of the third layer.