JPS6020335B2 - Manufacturing method of glass fiber reinforced cement board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a glass fiber reinforced cement board.

Conventionally, asbestos-cement boards have been used as building materials for interior and exterior walls.

However, stone wire cement boards have drawbacks such as poor impact resistance and easy breakage or scattering regardless of the amount of asbestos contained, which has been considered a defect of asbestos cement boards.

Recently, asbestos dust and asbestos contain carcinogenic substances, etc., which are a source of pollution, and furthermore, due to the depletion of asbestos fiber resources, costs have increased, so it has become necessary to manufacture fiber-reinforced cement boards that do not use asbestos at all. is desired.

A method has been proposed in which synthetic fibers such as nylon or polypropylene, or even glass fibers, are mixed into the slurry during sanding of the cement board as fibers for reinforcing the cement board.

However, when synthetic fibers were used, the modulus of elasticity of the fibers was low, and no improvement in bending strength was observed, so the expected effects were not obtained. In addition, when glass fibers are used, if they are mixed during the pulper or chest process, which is the slurry preparation process, non-uniform dispersion occurs in the slurry where asbestos does not exist, resulting in a phenomenon where only the glass fibers fall off from the wire mesh of the cylinder during papermaking. Moreover, the cement particles tend to fall off from the wire mesh, and the specific gravity of the manufactured cement board does not increase, resulting in low mechanical strength such as bending strength, which is not preferable.

As a method to avoid this problem, for example, a method is proposed in which cement paste is sprayed onto the wire mesh or felt of a papermaking cylinder rotating under suction, and glass fiber is sprayed onto the cement layer (Tokubatsu No. 51-25519). ) Or a method in which a slurry in which glass fibers are dispersed in a solution of a surfactant or the same effective drug is poured into the wire mesh of a cylinder immediately before the completion of paper making of cement slurry, and the slurry is dispersed in the upper layer of the paper making (
Samurai Seki Publication No. 51-6951) and the like have been proposed.

However, in the cement board that can be made using this method, the glass fibers are unevenly dispersed in the inner layer, forming a dense layer of glass fibers and a cement layer, and furthermore, due to the presence of micro voids between the layers, delamination and bending strength are reduced. It has defects such as causing deterioration. The present inventors have completed the present invention through intensive research to solve the above-mentioned problems, and the purpose of the present invention is to solve the above-mentioned problems without making any changes to the cement board manufacturing process and equipment using the conventional papermaking method. Another object of the present invention is to provide a method for manufacturing a glass fiber reinforced cement board that does not use asbestos at all and has excellent impact resistance and bending strength.

That is, the present invention provides cement with a weight percent of at least 5 and a glass composition of at least 5 mole percent, Si02
50~69Zr02 9~1
4R20 10~25K20
1-7 R'0 0-10 CaF2 0-2 &○ 0-7 P2Q O-5 Other metal oxides 0-10 F O-3 [However, R is Na, Li, and the sum of R and K20 is 14 to 25 mol%.

R' is an alkaline earth metal or Zn, Mn, Pb. Other metal oxides include N203, Ti02, Fe203, C
eQ, Sn02, etc., and fluoride can be converted into F2. ] and containing 0.5 to 5% by weight of alkali-resistant glass fibers with an alkali solubility of 4% or less, 2 to 5% by weight of pulp, and 0.5 to 2% by weight of fibrous material. This is a method for manufacturing a glass fiber reinforced cement board, which is characterized by paper-making.

The alkali solubility shown in the present invention is a glass fiber diameter of 13±0.
．． This figure shows the weight loss of the glass fibers as a percentage when the glass fibers were soaked in 100 g of a 10% NaOH aqueous solution of 9 g for 1 hour. The glass fiber used in the present invention is a glass fiber having the above composition range and an alkali solubility of 4% or less, and has corrosion resistance against strong alkaline components of cement during the preparation of papermaking slurry and the papermaking process. Therefore, it can provide an excellent reinforcing effect to the cement board. The thickness of the alkali-resistant glass fiber used in the present invention is preferably in the range of 6 to 2 mm, and if the fiber diameter is less than the above range, the tensile strength per single fiber is undesirably low. If the content exceeds the above range, handling of the fibers becomes difficult, and the adhesive strength with the cement matrix decreases, resulting in a small reinforcing effect.

The fiber length of the glass fiber is preferably in the range of 3 to 5 mm, particularly 6 to 25 mm.

If the fiber length is smaller than this range, the crack prevention effect and reinforcing effect of the cement board will not be obtained, and conversely, if it exceeds 5 sides, the uniform dispersion in the raw material slurry will decrease and a homogeneous glass fiber reinforced cement will not be obtained. I can't get the board. The number of alkali-resistant glass fibers that can be mixed into the slurry is at most 10.
Chopped strands consisting of 0 strands are preferred.

If the number of fibers exceeds 100, the glass fibers will settle in the chest or vat, causing separation from other papermaking components, and will be difficult to get on the wire mesh of the cylinder, which is not preferable. The content of the glass fiber in the raw material is 0.5~
A range of 5% by weight is desirable, and a range of 1 to 3% by weight is particularly preferred. If it is less than 0.5% by weight, the contribution to strength will be small, and if it exceeds 5% by weight, fibers will become entangled and the strength will decrease, which is inappropriate.

Further, the amount of pulp mixed is preferably in the range of 2 to 5% by weight, and most preferably in the range of 3 to 4.5% by weight. Contamination amount is 2%
If it is less than that, not only the glass fibers but also the cement particles will settle in the slurry, and the cement will pass through the wire mesh of the cylinder, making it impossible to obtain a cement board with a high specific gravity, which is not preferable. On the other hand, if it exceeds 5% by weight, the water absorption of the cement board will increase, resulting in a decrease in dimensional stability and strength, and the organic components in the cement board will increase, resulting in a decrease in thermal properties, which is not preferable. Furthermore, the fibrous material referred to in the present invention is an inorganic fiber other than asbestos, such as rock wire, silica alumina fiber, potassium titanate fiber, etc.

Since the fibers are inorganic, they have excellent heat resistance, and since the fibers themselves do not absorb water, the dimensional stability of the cement board is low, which is preferable. The fibrous material has the effect of enveloping the glass fibers and uniformly dispersing them in the slurry by interacting with the pulp, and has the effect of making it easier to get on the wire mesh of the cylinder, and also has the effect of preventing cement particles from falling off the wire mesh. However, the amount mixed in the raw materials is 0.5 to 20% by weight.
A range of is preferred. If the mixed amount is less than 0.5% by weight, the above-mentioned effect will be small and the cement particles will fall off from the wire mesh, making it impossible to obtain a cement board with a high specific gravity, which is not preferable.
If the amount exceeds 20% by weight, the fibrous material and the glass fibers become entangled in lumps, causing a boring phenomenon and making it impossible to obtain a homogeneous cement board. The content of cement, which is the main component of the raw material shown in the present invention, is at least 5% by weight, and if the amount of cement is less than 5% by weight, the strength of the cement board will decrease,
This is not preferable because it causes practical problems.

The cement is a general hydraulic cement, such as ordinary or early-strength Bortland cement, alumina cement, fly-ash cement, and silica cement.
Further, admixtures that can be added to the cement include, for example, powdered fillers such as calcium carbonate, resin emulsions such as acrylic and ethylene, colored pigments, and synthetic fibers such as nylon or polypropylene, which may be selected as appropriate. It can be used. The method for preparing the slurry consisting of the above raw materials is to first mix the cement, the above pulp fibrous material and the alkali-resistant glass fiber in a dry state, then transfer this to a waste frame tank, add water and further mix it for a second time. This may be carried out by either a dry method in which the slurry is fed to the pad, or by mixing the raw materials and water in a pulper to form a slurry, which is then sent to a chest and then supplied to the pad.

Further, the alkali-resistant glass fiber may be mixed at the pulper mixing stage or at the chest stage.

The raw material slurry in the pad prepared by this method is rolled onto a cylinder of 50 to 60 mesh by a conventional method, and while being dehydrated in a suction box, it is wound up on a making roll until it reaches a predetermined thickness and cut. A flat plate-shaped raw slope is obtained. The green slope is pressure molded or molded into a corrugated shape and then cured by a conventional method to obtain a glass fiber reinforced cement board. Since the glass fiber reinforced cement board produced by the method of the present invention does not use asbestos at all, it does not cause pollution problems due to asbestos dust or asbestos containing carcinogenic substances, and has excellent mechanical strength and heat resistance against bending and impact. The resulting cement board is suitable for building materials, particularly interior and exterior wall materials, roof panels, partition materials, ceiling materials, sandwich panels, etc.

The present invention will be explained below with reference to Examples.

Example 1 Specified amount of ordinary boltland cement, 14% calcium carbonate
wt%, pulp 4wt% and glass composition mol% Si
02:66, Zr02:11, Na20:18, K20
:1, B203:4 alkali-resistant glass fiber (
Alkali solubility 2.5%, fiber diameter 13 threads, fiber length 1 material,
A raw material consisting of 2% by weight (Shito number of 50 pieces) and a predetermined amount of rock wool (Asano mineral fiber: powdered wire) is thoroughly mixed with a pulper, transferred to a chest, and further sent to a vat (
(However, the batt concentration is 10%), was applied to the felt at a speed of 30 mm/min using four 50 mesh wire mesh cylinders, wound on a making roll, and then cut at a rate of 10 k9/min.
After being pressure-molded using ground pressure, a sheet was placed over the mold and the product was cured at room temperature for two weeks.

The specific gravity and bending strength of the obtained glass fiber reinforced cement board were measured. The results are shown in Table 1. Table 1 Rock wool amount is 0.
When the amount was less than 5% by weight, the pulp and alkali-resistant glass fibers were separated from the cement particles, and the cement matrix often flowed out from the wire mesh, and the specific gravity did not increase, making it impossible to obtain a homogeneous cement board.

Moreover, if the amount exceeds 2% by weight, the rock wool becomes entangled and a boring phenomenon occurs, making it impossible to obtain a uniform cement board. Example 2 A predetermined amount of ordinary boltland cement and pulp, 8% by weight of the rock wool used in Example 1, and a glass composition of mol% S
j02:66.2, Zrbi:12.0, Na20:13
．． Enter K20: 3. Ca0:4. Furi 03: Alkali-resistant glass fiber with an alkali solubility of 1.0% (alkali solubility 2.0%)
, fiber diameter 10 french, fiber length 19 side collection number 50)2. A raw material having a weight percent of The bending strength and drying shrinkage were measured.

The results are shown in Table 2.

Table 2 When the pulp amount was less than 2% by weight, the cement particles tended to sink, and more cement particles flowed out from the wire mesh of the cylinder, and the specific gravity of the cement board did not increase, resulting in low bending strength.

If the amount exceeds 5% by weight, some fibers become entangled in the slurry, resulting in poor paper formability, and the drying shrinkage rate also increases, making it impossible to obtain a homogeneous cement board with excellent dimensional stability. Example 3 8% by weight of ordinary Bolland cement, 4% pulp
2% by weight, 6% by weight of silica-alumina fibers, 8% by weight of calcium carbonate, and 2% by weight of glass fibers with different alkali solubility (fiber diameter 1 or fiber length 13 side, number of fibers 50) with the glass composition shown in Table 3. The raw boards obtained by mixing and forming a slurry were press-molded at a press pressure of 10 kg/cm, and then covered with a sheet and cured at room temperature for two weeks.

The specific gravity and bending strength of the obtained glass fiber reinforced cement board were measured. The results are shown in Table 4. As can be seen from Table 3 and Table 4, glass fibers with alkali solubility exceeding 4% have a significant decrease in strength due to erosion by the alkali IJ component of the cement in the slurry during papermaking and during curing.
Almost no reinforcing effect on the cement board was obtained.

Example 4 Ordinary Boltland cement and the alkali-resistant glass fiber used in Example 1 were prepared using a specified amount of raw materials consisting of 4% by weight of pulp, 5% by weight of natural cotton (Asano mineral fiber: powdered cotton), and 11% by weight of calcium carbonate. After uniformly mixing in a pulper, a green slope was created using a paper machine and pressure molded at a pressure of 10k9/c, followed by curing for two weeks at room temperature, and the specific gravity and bending strength were measured.

The results are shown in Table 5. Table 5 When the amount of alkali-resistant glass fiber was 0.5% by weight, there was almost no reinforcing effect, and when it exceeded 5% by weight, the fibers were poorly dispersed, resulting in a cement board with uneven bending strength. .

Example 5 Ordinary boltland cement 8% by weight, pulp 4% by weight
, rock wool (Asano mineral fiber: powder wire) 6% by weight
, and a raw material consisting of 2% by weight of alkali-resistant glass fiber (alkali solubility 2.5%, fiber length 19 side) having a predetermined fiber diameter and number of fibers having the composition used in Example 1. A green board was prepared using a paper making machine, pressure molded to 10k9/base, and then cured at room temperature for two weeks.

Table 6 shows the results of measuring specific gravity and bending strength. 6th
If the surface alkali-resistant glass fiber is less than 6 points, the glass fibers will be severely broken at the fracture surface of the cement board where the bending strength was measured, and if it exceeds 2 points, most of the fibers will be glued to the cement matrix. The properties were poor and the reinforcing effect was small.

Furthermore, when the number of fibers exceeds 10, the alkali-resistant glass fibers tend to settle in the vat, making it impossible to obtain a homogeneous cement board.

Claims (1)

[Claims] 1 At least 50% by weight of cement or mol% of glass composition SiO_2 50-69 ZrO_2 9-14 R_2O 10-25 K_2O 1-7 R'O 0-10 CaF_2 0-2 B_2O_3 0- 7 P_2O_5 0-5 Other metal oxides 0-10 F_2 0-3 [However, R is Na, Li, and R_2O and K_2O
The total amount is 14 to 25 mol%. R' is an alkaline earth metal or Zn, Mn, Pb. Other metal oxides include Al_2O_3, TiO_2, Fe_
2O_3, CeO_2, SnO_2, etc., and fluoride can be converted into F_2. ] and has an alkali solubility of 4% or less.
．． 1. A method for manufacturing a glass fiber reinforced cement board, which comprises forming an aqueous slurry containing 5 to 5% by weight of bulp, 2 to 5% by weight of bulp, and 0.5 to 20% by weight of fibrous material.
2. The method for manufacturing a glass fiber reinforced cement board according to claim 1, wherein the alkali-resistant glass fibers are chopped strands having a fiber diameter of 60 to 20 μm and a bundle of at most 100 fibers. 3. The method for manufacturing a glass fiber reinforced cement board according to claims 1 and 2, wherein the fibrous material is rock wool.