JPH1110617A - Manufacture of fiber-reinforced cement plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display a strength of a product by executing an autoclave curing after natural curing while pressurizing a manufacturing plate for high pressure compressing it to a predetermined thickness to feed by a dry manufacturing method of a fiber-reinforced cement plate reinforced by pulp fiber, thereby preventing a plate thickness increase in a spring back after high pressure pressurizing by a grain roll. SOLUTION: Normal Portland cement, crystalline silica, dry open pulp fiber, polypropylene fiber and amorphous silica are mixed, kneaded, scattered in a laminar state in a predetermined thickness on a wetted molding belt, scattered by spraying from its surface with water necessary for curing, primarily pressurized, secondarily pressurized and molded. The plate-like materials of predetermined number are stacked as a block 1, upper and lower caul plates 2 are provided on the block 1, and compressed by a press 3. Peripheries of the plates 2 are thoroughly tightly fastened by clampers 4 in the state at it is, then removed from the press 3, naturally cured, and then autoclave cured. Thus, its texture is very densified to form the fiber-reinforced cement plate having extremely high strength and low water absorption ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber reinforced cement board, and more particularly to an improvement in a case where a fiber reinforced cement board using pulp fibers as a reinforcing fiber is formed by a so-called dry manufacturing method.

[0002]

2. Description of the Related Art As architectural plate materials such as wall plates and roof materials,
BACKGROUND ART Cement building boards using pulp fibers as reinforcing fibers are very widely used.

[0003] Among these methods for producing architectural plate materials, a dry production method is known as a production method suitable for relatively thin wall boards and roof materials. In this dry manufacturing method, a mixture of cement, silica sand, aggregate, pulp fiber, etc. is sprayed in a layered manner to a predetermined thickness on a moistened forming belt, and water necessary for curing is further sprayed. The body is finally made into a plate by high-pressure and high-pressure compression to a certain thickness, cut, and cured by autoclaving to obtain a product.

[0004]

The fiber-reinforced cement boards which do not use asbestos and which do not contain asbestos generally have problems such as insufficient bending strength, flexibility and impact strength.

[0005] For this reason, fine silica such as crystalline silica or amorphous silica fume having a Blaine value of 8000 cm ² / g or more is blended into a cement compound to increase the bond strength itself of the cement matrix, thereby increasing the bending strength and the like. Ensuring flexibility is being performed.

However, when a sheet material is formed by a dry manufacturing method with this composition, there are the following problems. That is, in the final stage of the dry process, high pressure is applied, for example, to a linear pressure of 700 kg / cm with Glen Roll for the purpose of increasing product density and improving strength. As a result, the elasticity causes the product to spring back.

Assuming that the plate thickness immediately after compression by a pressing device such as a Glen roll is t, the restoration increase amount of the plate pressure due to the springback reaches a maximum of 1.3 t until the plate material is cured during natural curing thereafter. There was a problem that the microstructure became coarse and the product strength was not improved only in proportion to the amount of fine silica added.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and when a plate is made by a dry process using a pulp fiber-containing composition, the thickness is increased by springback after high-pressure pressing with a Glen roll or the like. The purpose of the present invention is to prevent the occurrence of the problem and to exert the product strength corresponding to the added amount of the fine silica.

[0009]

According to a first aspect of the present invention, there is provided a method of manufacturing a fiber reinforced cement board in which pulp fibers are used as a reinforcing fiber. The plate body is subjected to natural curing while being pressurized, and then to autoclave curing.

[0010] That is, after being compressed under high pressure by a Glen roll, the plate body is cured while being pressed, so that springback is completely suppressed and the product strength is improved. According to a second aspect of the present invention, there is provided a method of manufacturing a fiber-reinforced cement board in which pulp fibers are used as reinforcing fibers. And natural curing, followed by autoclave curing.

In this case, after compression by a pressing device such as a Glen roll, the springback is completely suppressed by the pressing device, so that a plate material excellent in strength can be obtained. The stacking number of the multi-stage should be 50 sheets or more, and the press pressure should be 3 to 20MPa.
a is desirable. If the pressure is lower than 3 MPa, it is difficult to completely suppress springback with a stacking number of 50 sheets or more, and the effect of strength improvement cannot be sufficiently obtained. Becomes uneconomical.

According to a third aspect of the present invention, there is provided a method of manufacturing a fiber-reinforced cement board using pulp fibers as a reinforcing fiber, in a so-called dry manufacturing method, wherein the plate-making bodies which are delivered under high pressure to a constant thickness are stacked in multiple stages. In this state, the pressurized multi-stage stacked body is tightened in the thickness direction with a fastener, and natural curing is performed in that state, and then autoclave curing is performed.

In this case, since the compressed state is maintained by the tightening device after the pressing, the springback is completely suppressed.
Handling such as loading and unloading of products after pressing becomes possible.
In addition, it is desirable that the stacking number and the pressing pressure of the multi-stage are set to the same conditions as in the second aspect.

[0014]

Next, an embodiment of the present invention will be described.
Normal Portland cement as cement in Table 1, crystalline silica having a Blaine value of 3,700 cm ² / g as silica, NBKP as pulp, dry defibrated pulp fiber, and polypropylene fiber with an average length of 6 mm as synthetic fiber (trade name of Tezac Corporation) "Taphrite" Amorphous silica (trade name "Elchem 940" manufactured by Elchem Co., Ltd.) was used as silica fume, and three types of compounding raw materials A, B, and C were adjusted as the compounding amounts shown in Table 1, respectively. The numbers in the table indicate% by weight.

[0015]

[Table 1]

The raw materials A, B, and C are kneaded with a universal kneader (type 25AM) for 10 minutes, and the raw materials A, B, and C, which have been uniformly mixed, are coated on a wetted belt having a predetermined thickness. Spraying water necessary for curing from the surface, press for 10 seconds at primary pressure 1MPa, press for 10 seconds at secondary pressure 10MPa, vertical and horizontal 100mm × 15
A sample plate having a thickness of 0 mm, a thickness of about 4 mm when pressed, and a weight of 300 g per sheet (260 g of dry raw material, 20 g of back water, 20 g of front spray water) was formed.

Next, the above-mentioned plate-like bodies are piled up every five sheets and divided into two groups, one of which is naturally cured at room temperature while being pressed with a compressive force of 10 MPa, and the other is cured. One was naturally cured at room temperature without pressure.

The curing time of the natural curing was 24 hours, and after this natural curing, autoclave curing was performed at 8.5 atmG × 15 hours. The flexural strength of the plate after autoclaving was measured in accordance with the JIS No. Bending Strength Test for the material subjected to natural curing without compression and the material subjected to natural curing while compressing. Tables 2 and 3 Was the result.

The numerical values in Tables 2 and 3 are average values of five test plates. As is clear from the comparison between Tables 2 and 3, the plate thickness after autoclaving is 17% lower in the blends A and B in the compressed (Table 3) than in the uncompressed (Table 2). In the same C, the springback was effectively reduced by 13%, and the flexural strength was increased by 16% in the mixture A with the compression strength (Table 3) compared with that in the non-compression (Table 2), 39% increase, same C 57
%, And a marked improvement in strength was observed.

Further, it was found that the water absorption was lower by 45 to 65% in the case of compression (Table 3) than in the case of no compression (Table 2). In addition, the pore volume, which indicates the fineness of the microstructure, shows a difference of two orders of magnitude in the order of 10 ^-2 in the case of compression (Table 3) compared to that in the case of no compression (Table 2). The plane strength indicating the tensile strength was also a measured value more than doubled.

[0021]

[Table 2]

[0022]

[Table 3]

Next, the actual size of the roofing material is 450 mm × 90.
A plate having a thickness of 0 mm was molded using the blend B by a dry process. As shown in FIG. 1, this plate-like body is stacked every 100 sheets, and this is made into one block 1 to produce 9 blocks.
20MPa, the other one is compressed at a pressure of 10MPa, and the other one is compressed at a pressure of 3MPa and tightened as it is around the abutment plates 2, 2 with fasteners 4 ... 4, and then removed from the press device 3 5-48 After curing for natural time, autoclave curing was performed for 8.5 atmG for 15 hours.

In the dry manufacturing method, the amount of water used is very small, and even if the block 1 is compressed at a high pressure in order to spray particulate matter such as granules on the surface, the plate-like bodies will not block each other. Absent.

The bending strength of the plate after autoclaving is
It is divided into the one that has been subjected to natural curing without compression and the one that has undergone natural curing while compressing with the fastener 4, and five samples are randomly sampled from each block in accordance with the JIS No. 5 bending strength test. When the bending strength was measured, the result shown in FIG. 2 was obtained.

In FIG. 2, the horizontal axis indicates the time during which natural curing was performed in a compressed state or a non-compressed state, and the vertical axis indicates the average value of the bending strength of the corresponding final product. As is clear from FIG. 2, it was found that the strength of the material naturally cured in the compressed state sharply increased from around 10 hours after the curing time passed, and the tendency appeared from the compression force of 3 MPa.

Instead of the contact plates 2 and 2 and the fasteners 4... 4, plate materials 1 stacked in a cassette case 5 are stored as shown in FIG. It is placed and pressed by a pressing device 3 with a compressive force of 20 to 3 MPa, and the pressing member 6 is locked in the engaging hole formed in the side surface of the cassette case 5 while pressing, and the abutment plate 2 is fixed.
Thereafter, natural curing was performed in the same manner as in the above example, and then autoclave curing was performed.

In this case, almost the same results as shown in FIGS. 1 and 2 and Table 2 were obtained. In addition, the same result was obtained when the plate-like bodies were similarly molded and the strength was measured for the blends A and C.

[0029]

As described above, according to the present invention, even when a blending material containing pulp fiber as a reinforcing fiber is used in a dry manufacturing method, the springback after high-pressure press compression of a Glen roll or the like is almost completely suppressed, and the state is maintained. Thus, the board is cured and hardened, so that the structure is extremely densified, and a fiber-reinforced cement board having extremely high strength and low water absorption can be manufactured.

[Brief description of the drawings]

FIG. 1 is a front view of an apparatus for performing the method of the present invention.

FIG. 2 is a graph showing the strength of a product obtained by the method of the present invention.

FIG. 3 is a sectional view of another apparatus for performing the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stacked plate material 2 Patch plate 3 Press device 4 Fastener 5 Cassette case 6 Locking tool

Claims (3)

[Claims] In a so-called dry manufacturing method of a fiber reinforced cement board using pulp fiber as a reinforcing fiber, a sheet body compressed and sent to a predetermined thickness under high pressure is subjected to natural curing while being pressurized, and then to autoclave curing. A method for producing a fiber-reinforced cement board, characterized in that: 2. In a so-called dry process for producing a fiber-reinforced cement board using pulp fiber as a reinforcing fiber, natural hardening is performed while applying a pressing force by stacking plate-making bodies which are compressed and sent out to a certain thickness under high pressure, Thereafter, a method for producing a fiber-reinforced cement board, which comprises performing autoclave curing. 3. In a so-called dry process for producing a fiber-reinforced cement board using pulp fibers as reinforcing fibers, a plate made of high-pressure compressed to a constant thickness and sent out is stacked in multiple stages and press-compressed. A method for producing a fiber-reinforced cement board, comprising tightening a multi-stacked body in a thickness direction with a fastener, performing natural curing in that state, and then performing autoclave curing.