JPH0826810A - Manufacture of composite board using acetyl cellulose - Google Patents

Abstract

PURPOSE:To obtain a no-asbestos-fiber composite board having the same or a higher level of physical properties than the case where asbestos fiber is used by molding a mixture of a siliceous raw material, a calcareous raw material, an acetyl cellulose having a low acetyl value and water followed by steam aging. CONSTITUTION:This composite board is obtained by molding a mixture of a siliceous raw material, a calcareous raw material, acety] cellulose acetylated at the level where the obtained acetyl cellulose is essentially insoluble in water followed by steam aging. The acetyl value of the acetyl cellulose is usually about 0.5-8.4. Further, fiber lengths of the acetyl cellulose are usually 0.1-10.0mm.

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 composite board which does not use asbestos fibers and has physical properties equal to or higher than those when asbestos fibers are used.

[0002]

2. Description of the Related Art Conventionally, when a composite board is manufactured by steam curing, for example, siliceous raw materials such as silica sand, diatomaceous earth, and silica, and calcareous raw materials such as lime and gypsum are pulverized,
After mixing, asbestos fibers are mixed with this, and then water is added to the obtained mixture at an appropriate ratio, molded and transferred to an autoclave for steam curing. In this case, the asbestos fiber used has an affinity for inorganic raw materials,
Due to its excellent heat resistance and alkali resistance, and its low price, it has been used in large quantities as a raw material for inorganic boards. However, in recent years, asbestos fiber has been revealed to be a carcinogen, and its use is being prohibited by law in Europe and the United States from the viewpoint of occupational hygiene and environmental protection, and the development of alternative fiber of asbestos fiber is strongly demanded. Was there.

[0003]

A number of proposals have already been made as fibers that can replace asbestos fibers, for example, various synthetic fibers such as polypropylene, polyamide, polyimide, polyester, polyvinyl alcohol and pulp,
In addition, inorganic fibers such as glass fiber, carbon fiber, steel fiber and the like can be mentioned. In order to substitute asbestos fibers, it is necessary to maintain the fiber form in steam curing, have a high affinity with inorganic raw materials, prevent the fibers from falling out easily, and have alkali resistance and the like. . Among these fibers, pulp has been noted for its excellent heat resistance, alkali resistance, and light weight, but on the other hand, it has high water absorption, which causes dispersibility and reinforcement. There were problems such as not being enough. Therefore, the present invention provides a method for producing a composite board which does not use asbestos fibers and has physical properties equal to or higher than those when asbestos fibers are used, for example, bending strength.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the siliceous raw material and the calcareous raw material are acetylated to such an extent that they are substantially insoluble. By molding a mixture of acetylated fibrin and water and steam curing, a composite board with the same or better physical properties as a composite board manufactured using asbestos fibers, even though asbestos fibers are not used. The inventors have found that a board can be manufactured and have reached the present invention. That is, the present invention is characterized by performing steam curing after molding a mixture of siliceous raw material, calcareous material, acetylated fibrin acetylated to such an extent that it is substantially insoluble, and water. The present invention relates to a board manufacturing method.

The present invention will be described in detail below.
The siliceous raw material used in the present invention can be used without particular limitation as long as it is conventionally used for producing a composite board by steam curing. Examples of such siliceous raw materials include silica sand, diatomaceous earth, silica stone,
Blast furnace slag, fly ash, etc. can be mentioned.
The siliceous raw material is added to improve miscibility with other components.
It is preferably in a crushed state. For example,
The pulverized state is preferably a powder state. The particle size of the siliceous raw material in powder state is generally 0.1 to 1000 μm,
It is preferably 1 to 200 μm. The calcareous raw material can be used without particular limitation, as long as it is conventionally used when a composite board is produced by steam curing. Examples of such calcareous raw materials include lime (for example, quick lime and slaked lime) and gypsum. The calcareous raw material used in the present invention is preferably in a pulverized state in order to improve miscibility with other components. For example, the pulverized state is preferably a powder state. The particle size of the calcareous raw material in powder state is generally 0.1 to 1000 μm, preferably 1 to 200 μm. As the siliceous raw material and the calcareous raw material, raw materials in which these raw materials are preliminarily blended may be used. Examples of such a raw material include cement. Examples of such cement include cement such as hydraulic cement. Further, as a preferable cement, for example, Portland cement can be mentioned. In addition,
For example, in the case of Portland Senment, the siliceous raw material is mixed in about 22%, while the calcareous raw material is mixed in about 64%. The particle size of such a raw material is similar to that of the siliceous raw material and the calcareous raw material.

The acetylated fibrin used in the present invention is a fibrin (cellulose) acetylated to such an extent that it is substantially insoluble. That is, the acetyl number at which the acetylated fibrin is practically insoluble is 8.4 or less, preferably 8.0 or less. When the acetyl value is more than 8.4, the part of partially dissolved acetylated fibrin increases and the part existing in the fibrous state relatively decreases. As a result, the acetylated fibrin cannot actually exert its effect as a reinforcing material for the composite board. On the other hand, the acetyl value is
If it is less than 0.5, preferably less than 1.0, in the case of the extrusion method, the water absorption of the acetylated fibrin is too large, so that a cotton lump portion is generated by the stirring operation. Further, in the case of the paper-making method, the filterability of water is low, which causes uneven quality of the composite board, which is not preferable. If the acetyl value is less than 6.0, the strength of the composite board will be slightly lowered. Therefore, the acetyl value is usually 0.5 to
It is 8.4, preferably 1.0 to 8.0, and more preferably 1.0 to 6.0. Here, the acetyl value of the acetylated fibrin is represented by the number of milligrams of potassium hydroxide necessary for neutralizing acetic acid produced by saponifying 1 gram of the acetylated fibrin. Acetylation is generally at room temperature to 200
It is carried out by reacting the fibrin with, for example, acetic anhydride at ℃, preferably 50-140 ℃. If the temperature is too low, the efficiency of acetylation is poor,
Not preferred. On the other hand, if the temperature is too high, the acetylation reaction will be too fast, and it will be difficult to obtain the desired acetyl value, which is also not preferable. The acetylation time varies depending on the acetylation temperature, but is generally 30 minutes to 8 hours, preferably 50 minutes to 6 hours.

The acetylated fibrin is preferably in the form of short fibers so as to be uniformly dispersed in the composite board. The fiber length of acetylated fibrin is generally 0.1 to 1
It is 0.0 mm, preferably 0.5 to 5.0 mm.
When the fiber length is shorter than 0.1 mm, the reinforcing property becomes poor and the strength of the composite board is deteriorated, which is not preferable. On the other hand, if the fiber length is longer than 10.0 mm, the dispersibility tends to decrease, and the strength and the like of the composite board cannot be sufficiently exhibited, which is not preferable.
The fineness of acetylated fibrin is generally 0.1 to 3
It is 0.0 denier, preferably 0.1 to 10.0 denier. When the fineness is smaller than 0.1 denier, the strength of the fibers becomes insufficient, and it becomes difficult to improve the strength of the composite board, which is not preferable. On the other hand, when the fineness is greater than 10.0 denier, the interfacial adhesive strength with the inorganic raw material is likely to decrease, which is not preferable.

The composite board of the present invention can be manufactured by forming a mixture of a siliceous raw material, a calcareous raw material, an acetylated fibrin and water into a predetermined shape and then steam curing the mixture. The siliceous raw material is generally used at 5 to 70%, preferably 10 to 60%, based on the weight of the siliceous raw material, the calcareous raw material and the acetylated fibrin. If the amount of the siliceous raw material is too large, the strength of the composite board is likely to decrease, which is not preferable. On the other hand, when the amount of the siliceous raw material is too small, the specific gravity becomes large and it becomes difficult to reduce the weight, which is not preferable. The calcareous raw material is generally used in an amount of 15 to 60%, preferably 20 to 55%, based on the weight of siliceous raw material, calcareous raw material and acetylated fibrin.
If the amount of calcareous raw material is too large, the shrinkage of the composite board tends to increase, which is not preferable. On the other hand, when the amount of calcareous raw material is too small, defective curing or delayed curing tends to occur, which is not preferable. The acetylated fibrin is generally used in an amount of 0.5 to 30%, preferably 3 to 20% based on the weight of the siliceous raw material, the calcareous raw material and the acetylated fibrin. If the amount of acetylated fibrin is too large, the strength of the composite board tends to decrease, which is not preferable. On the other hand, if the amount of acetylated fiber is too small, defective molding tends to occur, which is not preferable. The amount of water is such that the amount of water after molding is generally 5 to 300%, preferably 10 to 200% with respect to the weight of siliceous raw material, calcareous raw material and acetylated fibrin. In advance, after mixing a large amount of water to make a slurry, let the water leak out,
It is also possible to obtain a desired water content after molding. If the amount of water is too small before molding, it becomes difficult to mix, and it becomes difficult to obtain a composite board of uniform quality, which is not preferable.
On the other hand, if the amount of water is too large, the shape retention of the molded product deteriorates, which is not preferable. It should be noted that, if necessary, additives such as a curing accelerator, a curing retarder, and a fiber dispersant may be blended with the above-mentioned blended raw material.

The stirring of the raw material mixture consisting of the siliceous raw material, the calcareous raw material, the acetylated fibrin and water is not particularly limited, but illustratively, a paddle mixer, a propeller mixer, a pot mixer and the like. It can be performed using a stirrer. The shape of the compound at the time of molding is generally rectangular, for example, a plate shape such as a square or a rectangle,
Various shapes can be used depending on the place where the composite board is used. For example, an elliptical or circular plate shape and the like can be mentioned. The shaped body is then conveyed, for example, into an autoclave, where it is subjected to steam curing. During this curing process, the acetylated fibrin is saponified. Therefore, in the molded body, the saponified acetylated fiber is
It is considered that ionic bonding with calcium in the calcareous raw material greatly improves the bending strength of the composite board. Steam curing is a method of heating and curing a molded body with steam. The pressure at this time is generally 5 to 2 as a gauge pressure.
00 kg / cm ² , preferably 9 to 100 kg / cm ² . If the pressure is less than 5 kg / cm ² , it is not preferable because the aggregates are likely to adhere to each other or the aggregates and the fibers tend to be insufficiently adhered. On the other hand, when the pressure is higher than 200 kg / cm ² , the specific gravity of the composite board tends to increase, which is not preferable. The temperature for steam curing is generally 65 to 300 ° C, preferably 150 to 250 ° C. If the temperature is lower than 65 ° C, the bonding of aggregates is likely to be delayed, which is not preferable. On the other hand, if the temperature is higher than 300 ° C., the composite board is likely to undergo discoloration or shrinkage, which is also not preferable. The steam curing time is generally 3 to 25 hours, preferably 5 to 18 hours. If less than 3 hours,
This is not preferable because the aggregate is insufficiently bonded and the strength of the composite board is likely to decrease. On the other hand, when the treatment is performed for longer than 25 hours, defective shrinkage of the composite board and reduction in productivity are likely to occur, which is also not preferable.

[0010]

The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples. The bending strength of the composite board in the examples was measured by the following method. Bending strength According to JIS A 1408, breaking load P (kg
f) was measured. Then, the three-point bending strength (kgf / cm ² ) was measured according to σ = 3PL / 2bh ² . In addition, below, this 3-point bending strength is only called bending strength.

However, P: breaking load (kgf) L: span length 15 cm b: width of test piece 15 cm h: thickness of test piece (thickness of composite board shown in Example (c
m))

Example 1 33.3 parts by weight of ramie fiber was added to 66.7 parts by weight of acetic anhydride and treated at 130 ° C. for 5 hours. Then, after drying the acetylated ramie fiber at 105 ° C. for 1 hour,
The solution was neutralized with an aqueous NaOH solution having a concentration of 50 g / liter, washed with water, and dried at 105 ° C. for 1 hour to obtain an acetylated fiber having an acetyl value of 4.5%. Similarly, the cotton fiber and the pulp are treated so that the acetyl value is 4.
8% and 5.2% acetylated fibrin was obtained. Then
The obtained acetylated ramie fiber and cotton fiber were cut to a constant length of 3 mm with a cutter. On the other hand, the acetylated pulp was obtained as it was as short fibers (2 mm). On the other hand, powdered diatomaceous earth (particle size 80 μm
) And powdered Portland cement (silicic raw material 22)
%) Powdered siliceous raw material (particle size 100 μm), 53 parts by weight, and powdered Portland cement as calcareous raw material (calcium raw material 64%) derived calcareous raw material (particle size 100 μm)
m) 38 parts by weight, 5 parts by weight of the acetylated short fibers, and 20 parts by weight of water were uniformly mixed using a mixer. Then, the mixture was put in a mold in an amount of 1.15 g / cm ² and a pressure of 95 kg / cm ² was applied, and as a result, a rectangular flat plate-like semi-plastic molded body was obtained. Then, steam curing was performed in saturated steam at 180 ° C. for 16 hours to obtain a composite board having a thickness of about 0.5 cm. As a comparative example, an asbestos fiber-containing composite board was obtained by the same method as above except that asbestos fibers were used instead of acetylated fibrin. Further, a composite board was obtained in the same manner as above except that non-acetylated ramie fiber, cotton fiber or pulp was used. When the bending strength of the obtained composite board was measured, it was as shown in Table 1 below.

[0013]

[Table 1] Table 1 Sample Acetylated fibrin mixing ratio Bending strength (parts by weight) (kgf / cm ² ) Example Acetylated ramie fiber 5 282 〃 Acetylated cotton fiber 5 264 〃 Acetylated pulp 5 259 Comparative example Asbestos fiber 5 255 〃 Ramie fiber 5 219 〃 Cotton fiber 5 203 〃 Pulp 5 197

From Table 1 above, a composite board having a bending strength equal to or higher than that of the composite board produced using asbestos fiber was obtained by using the acetylated fibrin. In addition, the composite board manufactured using acetylated fiber is
It can be seen that the bending strength is increased by about 30% as compared with the composite board produced by using the non-acetylated fibrin.

Example 2 An acetylated fiber material was produced from ramie fibers in the same manner as in Example 1 except that the treatment was carried out at the treatment temperatures and the treatment times shown in Table 2 below. In addition, the acetylated ramie fiber (No. 5) acetylated at a temperature of 150 ° C. for 5 hours was
Partial dissolution of fibers was observed. Then, the acetylated ramie fiber was cut to a constant length of 3 mm with a cutter in the same manner as in Example 1 to obtain an acetylated ramie short fiber. Furthermore, in the same manner as in Example 1, the acetylated ramie short fibers were
A semi-plastic molding was obtained by mixing with powdered diatomaceous earth, powdered Portland cement and water and then molded. Then
Steam curing was performed in the same manner as in Example 1, and the thickness was about 0.
A 5 cm composite board was produced. When the bending strength of the obtained composite board was measured, the results shown in Table 2 below were obtained.

[0016]

[Table 2] Table 2 Sample No. Acetylation temperature Acetylation time Acetyl number Bending strength (℃) (min) (kgf / cm ² ) 1 60 60 0.5 222 2 80 60 1.1 258 3 130 300 4.5 282 4 140 300 6.0 275 5 150 300 8.4 223

Judging from the bending strength, the acetylated fibrin used in the present invention has an acetyl value of 0.5 to 8.4, and the acetyl value is preferably 1.
It can be seen that a strength equal to or higher than that of the asbestos-containing composite board is obtained at 1 to 6.0.

Example 3 An acetylated fiber having an acetyl value of 4.5% was obtained from the ramie fiber in the same manner as in Example 1. This acetylated fiber material was cut into a constant length with a cutter into each fiber length shown in Table 3 below to obtain an acetylated ramie short fiber. On the other hand, powdered diatomaceous earth (particle size 80 μm) and powdered siliceous raw material (particle size 100 μm) derived from powdered Portland cement (silicic acid raw material 22%), 12 parts by weight, and powdered Portland cement (calcic raw material) as siliceous raw material. 64%) derived from calcareous raw material (particle size 100 μm) 4 parts by weight, powdered slaked lime (particle size 65 μm) 6 parts by weight, and the above acetylated fibrin 5
By weight, 80 parts by weight of water and a mixture of 80 parts by weight of water were uniformly mixed into a slurry. Then add 5.4 of the mixture to the formwork.
An amount of g / cm ² was added, a pressure of 9.0 kg / cm ² was applied through a 60-mesh wire net, and a drainage treatment was performed to obtain a rectangular flat plate-like semi-plastic molded product (water content: 70%). .
Finally, steam curing was performed in saturated steam at 180 ° C. for 6 hours to manufacture a composite board having a thickness of about 1.3 cm. When the bending strength of the obtained composite board was measured, the results shown in Table 3 below were obtained. As a comparative example, an asbestos-blended composite board was produced in the same manner as above except that 5 parts by weight of asbestos was blended in place of the acetylated fibrin. Table 3 also shows the bending strength data of the composite board.

[0019]

[Table 3] Table 3 Sample No. Acetylated ramie fiber length Bending strength (mm) (kgf / cm ² ) 1 0.5 73 2 3.0 3.0 79 3 5.0 5.0 81 4 10.0 71 Asbestos blended product 70

Judging from the bending strength, it is found that the fiber length of the acetylated fiber used in the present invention is preferably 0.1 to 10.0 mm. Further, it can be seen that the bending strength of the composite board of the present invention is equal to or higher than that of the asbestos-containing composite board of the comparative example.

[0021]

The strength of the composite board obtained by steam curing using the acetylated fibrin of the present invention is equal to or higher than that of the conventional composite board using the asbestos fiber as the reinforcing fiber, and as a substitute for the asbestos fiber. It has superior strength compared to the composite board containing the short fibrous fibers used. Therefore,
INDUSTRIAL APPLICABILITY The composite board of the present invention has usefulness as a building material such as a wall material, a floor material, a board, and a civil engineering material without adversely affecting the working environment.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C04B 16:02) Z 111: 12

Claims (3)

[Claims] 1. A composite characterized by performing steam curing after forming a mixture of a siliceous raw material, a calcareous raw material, an acetylated fibrin substance acetylated to a degree that is substantially insoluble, and water. Board manufacturing method. 2. The acetyl number of the acetylated fibrin is
The manufacturing method according to claim 1, which is 0.5 to 8.4. 3. The length of the acetylated fibrin is 0.1.
The manufacturing method according to claim 1, which has a thickness of about 10.0 mm.