JP4283484B2 - Wood cement board and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The object is to provide a lightweight and high-strength wood cement board and a method for producing the same.
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, ceramic siding excellent in fire resistance and durability has been used as an inorganic molded body. For example, a hard wood piece cement board is formed by integrally molding a piece of wood with cement as a binder and exhibits strength as a siding board by curing at room temperature, but requires a large amount of cement, so it has a high specific gravity. For this reason, some pearlite is added to reduce the weight as disclosed in JP-A-3-218955, but the amount of pearlite is limited because the strength is reduced, and there is a limit to the weight reduction. It was. Therefore, as in Japanese Patent Application No. 11-72036 (Japanese Patent Laid-Open No. 2000-264701), a method for obtaining a lightweight inorganic molded body while adding a large amount of an inorganic foam has been proposed. A wood cement board having high bending strength has been desired.
[0003]
In view of the above problems, an object of the present invention is to provide a high-strength and lightweight wood cement board and a method for producing the same.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, a wood cement board according to the present invention is obtained by mixing a hydraulic material containing an amorphous siliceous material, an inorganic foam and a wood material, and then adding and mixing water. In the wood cement board obtained by pressure-molding the mixture and curing in an autoclave, the hydraulic material has a calcium / silica molar ratio of 0.6 to 1.8, a brain specific surface area of 3800 cm ² / g or more, and an alkali content. 0.6 to 1.0 part by weight with respect to 100 parts by weight of the hydraulic material, alkali sulfate is added as an additive to the hydraulic material, and the inorganic foam is under a water pressure of 5 Mpa. The bulk density is at least one selected from the group consisting of pearlite, obsidian foam, and shirasu foam, and the solid component of the mixture is 35 to 70% by weight of the hydraulic material. It is constituted comprising inorganic foam 10 to 25 wt%.
[0005]
The hydraulic material is made of Portland cement and fly ash, and the content of 3CaO.SiO _{2 in} Portland cement is more preferably 63% or more.
[0006]
Further, the method for producing a wood cement board according to the present invention comprises mixing a hydraulic material containing an amorphous siliceous raw material, an inorganic foam and a wood material, and then adding and mixing water to obtain a mixture, In the method for producing a wood cement board for autoclave curing after pressure-molding the mixture, the hydraulic material has a calcium / silica molar ratio of 0.6 to 1.8 and a brain specific surface area of 3800 cm ² / g or more. The alkali content is 0.6 to 1.0 parts by weight with respect to 100 parts by weight of the hydraulic material, alkali sulfate is added as an additive to the hydraulic material, and the inorganic foam is 5 Mpa. At least one selected from the group consisting of pearlite, obsidian foam, and shirasu foam with a bulk density under water pressure of 0.4, and the solid component of the mixture includes 35 to 35 of the hydraulic material. 0 wt%, the inorganic foam is a process comprising mixing 10 to 25 wt%.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The wood cement board according to the present invention is obtained by mixing a hydraulic material containing an amorphous siliceous material, an inorganic foam and a wood material, and then adding and mixing water, and then pressing and molding the mixture obtained. , Autoclave cured.
[0008]
The hydraulic material is used as a binder for inorganic foam and wood material, which will be described later, and is made of amorphous siliceous material such as fly ash, fine powder of blast furnace slag, diatomaceous earth, shirasu, and silica fume.
[0009]
The hydraulic material has a calcium / silica molar ratio of 0.6 to 1.8, a Blaine specific surface area of 3800 cm ² / g or more, and an alkali content in the hydraulic material of 0.6 to 1.0. It needs to be part by weight.
[0010]
If the calcium / silica molar ratio is 0.6 to 1.8, the product of hydrate is the largest, and the highest strength is obtained particularly when the molar ratio is around 1.2. When the molar ratio is less than 0.6, calcium is insufficient and hydration does not proceed. When the molar ratio exceeds 1.8, a hydrate with a high calcium content is generated and the reaction of silica proceeds. Because there is no.
Moreover, if the Blaine specific surface area is 3800 cm ² / g or more, the reaction is enhanced and the strength is developed, but if it is less than 3800 cm ² / g, the desired strength cannot be obtained.
Furthermore, an appropriate amount of alkali increases the reactivity of the amorphous siliceous raw material and increases the strength of the obtained wood cement board, so that its content is preferably 0.6 to 1.0 parts by weight. When the content is less than 0.6 parts by weight, the reactivity of the amorphous silicic acid raw material cannot be increased, and when the alkali content exceeds 1.0 parts by weight, the strength of the hydrate It is because it reduces.
[0011]
Examples of the cement used for the hydraulic material include Portland cement such as ordinary Portland cement and early-strength Portland cement, and alumina cement. The addition amount as the hydraulic material is preferably 35 to 70% by weight. If the addition amount is less than 35% by weight, the strength as a molded body cannot be maintained. If the addition amount exceeds 70% by weight, the addition amount of the inorganic foam or wood material becomes relatively low, and the desired wood cement board is obtained. It is because it cannot be obtained.
[0012]
In particular, the hydraulic material is composed of Portland cement and fly ash, and the content of C ₃ S (generic name for 3CaO · SiO ₂ ) in Portland cement is preferably 63% or more. Fly ash is preferable because it contains an appropriate amount of alkali and is highly reactive. This is because if the content of C ₃ S in Portland cement is 63% or more, the initial reactivity is high and the final strength is increased.
[0013]
Additives can be used to adjust the amount of alkali in the hydraulic material. Examples of the additive include alkali sulfates such as sodium sulfate and potassium sulfate.
[0014]
The inorganic foam is for reducing the weight of the wood cement board and improving the surface property, and examples thereof include perlite, obsidian foam, and shirasu foam.
[0015]
The addition amount of the inorganic foam is preferably 10 to 25% by weight. This is because if the addition is less than 10% by weight, the weight cannot be reduced sufficiently. On the other hand, if the addition amount exceeds 25% by weight, the addition amount of cement or wood material becomes relatively low, and a desired strength cannot be obtained.
[0016]
Moreover, it is preferable to use the said inorganic foam that the bulk density under the water pressure of the average particle diameter of 50-300 micrometers and 5 Mpa is 0.5 or less.
This is because if the average particle diameter of the inorganic foam is less than 50 μm, the film thickness of the shell of the foam becomes thicker than the particle diameter, so that the bulk density increases and becomes heavy. Further, if the average particle diameter exceeds 300 μm, the film thickness of the foam shell becomes thin and it is easy to break.
[0017]
Furthermore, the reason why the bulk density when compressed by applying a water pressure of 5 MPa is 0.5 or less is that if the bulk density exceeds 0.5, even if added, it does not contribute to weight reduction. The reason why 5 Mpa is used as the reference pressure is to prevent the inorganic foam from being destroyed by the pressure at the time of press molding, which is substantially equal to the pressure at the time of press molding the wood cement board. Therefore, according to the present invention, the inorganic foam is not destroyed even during press molding, and a wooden cement board having a smooth and sharp embossed surface can be obtained while maintaining weight reduction.
[0018]
The method for measuring the bulk density and volume compressibility of these inorganic foams is performed as follows.
When measuring the bulk density of an inorganic foam, put the inorganic foam in a 100 cc stainless steel container, tapping it up and down 180 times, and then measuring the bulk density with a powder tester (manufactured by Hosokawa Micron), a dedicated measuring device. taking measurement.
Next, the foam whose bulk density has been measured is put into a plastic bag or the like, and the air in the bag is evacuated with a vacuum pump, followed by sealing and sealing. And this bag is put into the pressurization tank filled with 3 liters of water, and it pressurizes for 60 second with a hydrostatic pressure of 5 Mpa with a hydraulic pump. Next, the inorganic foam is taken out from the bag and tapped in the same manner as described above to measure the bulk density.
[0019]
In addition, you may add 1-5 weight% of hardening accelerators, such as aluminum chloride, magnesium chloride, and calcium chloride, to a wooden cement board as needed.
[0020]
The wood material is added to increase the strength of the fragile inorganic molded body, and examples thereof include wood fibers and wood pieces, but the tree species is not limited. And it is preferable that the addition amount of a wood material is 10 to 25 weight%. This is because if the addition amount is less than 10% by weight, the reinforcing effect is insufficient, and if it exceeds 25% by weight, there is a problem in terms of fire resistance.
[0021]
The manufacturing method of the wood cement board concerning this invention is demonstrated.
First, a hydraulic material, an inorganic foam, and a wood material are mixed in a dry manner to obtain a mixture in which the inorganic foam and the hydraulic material are uniformly mixed between the wood materials. Then, 30 to 50% by weight of water is added to this mixture and further mixed. Next, as a method of pressure molding, the obtained mixture is sprayed on a plate and deposited in a mat shape, and this is press-molded, followed by primary curing and curing. Furthermore, secondary curing is carried out in an autoclave, and calcium silicate hydrate is produced by reacting calcium and silica, thereby obtaining a wood cement board exhibiting strength.
[0022]
According to this embodiment, since the hydraulic material, the inorganic foam, and the wooden material are put into a mixer and mixed in a dry manner, a mixture in which the inorganic foam and the hydraulic material are uniformly mixed between the wooden materials is obtained. It is done.
In addition, 30 to 50% by weight of water is added to the uniformly mixed mixture and mixed, so that water is not adsorbed excessively only on the wood material, but also adsorbed uniformly on the inorganic foam and the gaps between them. The For this reason, the wood material does not become lumpy, and a mixture in which the wood material, the inorganic foam and the hydraulic material are uniformly mixed is obtained.
[0023]
The reason why the amount of water added to the mixture is 30 to 50% by weight is that when the amount added is less than 30% by weight, the amount of water with respect to the hydraulic material becomes too small and a predetermined strength cannot be obtained. It is. On the other hand, if it exceeds 50% by weight, the water content becomes excessive and the woody material tends to become lumpy, and the water absorption rate of the molded article after the hydraulic material is cured increases.
[0024]
After spraying the mixture onto the plate and depositing it in a 30-100 mm thick mat, place the embossed plate on the top surface and mold it with a press machine. Harden. The primary curing is preferably performed at a temperature of 50 to 80 ° C. for 8 hours or longer.
The primary curing may be performed by steam curing, and the steam curing time is shortened by increasing the steam curing temperature. However, if the temperature is excessively increased, the board is dried and a predetermined strength cannot be obtained. For this reason, the steam curing temperature is preferably 50 to 80 ° C., but from the viewpoint of productivity, the steam curing time is usually preferably within 24 hours.
[0025]
Secondary curing in the autoclave after removing the embossed plate is mainly to react calcium and silica, which are hydraulic materials, to produce calcium silicate hydrate, and to obtain the final wood cement board that exhibits practical strength. It is this process. Since cement is hydrated and hardened by primary curing and then secondary curing is performed by autoclave, the calcium of cement in the hydraulic material, amorphous silicic acid raw material such as fly ash in the hydraulic material, and inorganic The amorphous component of the foam reacts to produce calcium silicate hydrate, and a wood cement board having a desired strength is obtained. The secondary curing by autoclave is preferably at a temperature of 150 to 220 ° C. If the autoclave curing temperature is raised, a high-strength wood cement board can be produced in a short time, but if it exceeds 220 ° C., wood materials such as wood chips and wood fibers will deteriorate and the strength will be lowered. Moreover, if it is less than 150 degreeC, in order to obtain sufficient intensity | strength, a curing time becomes remarkably long and is unpreferable. The autoclave curing time varies depending on the temperature, but is preferably 1 to 24 hours, preferably 3 to 8 hours.
[0026]
According to the present invention, it is possible to obtain a high-strength molded body that is lightweight and in which fibers are uniformly distributed. For this reason, it is not necessary to use a multi-layered inorganic molded body in which a core layer having a low density is sandwiched between front and back layers having a high density and a high strength as in the prior art, and a single-layer structure may be used, thereby increasing productivity. . However, in the present invention, it is a matter of course that the composition ratio of the front and back layers and the core layer may be changed to have a three-layer structure.
[0027]
【Example】
(Example 1 to Example 10)
The raw materials in the composition ratio shown in FIG. 1, especially Portland cement with different C ₃ S amount as cement of hydraulic material, fly ash as amorphous siliceous raw material of hydraulic material, potassium sulfate as an additive, inorganic material Shirasu foam or perlite as the foam, powdered material made of waste wood cement board as the return material, wood chips as the wood material, and calcium chloride as the hardening accelerator were blended. And after mixing the said raw material with a mixer for 2 minutes, 45 weight part of water was added with respect to 100 weight part of solid components, and also mixed for 30 seconds, and the mixture was obtained.
[0028]
Next, the mixture was spread on a stainless steel plate and deposited in a mat shape having a thickness of 40 mm, and then a resin plate was placed on the upper surface and sandwiched, and a plurality of mats in this state were stacked. And after pressurizing with the pressure of about 5 Mpa and clamp-fixing as it is, primary curing was carried out on conditions of temperature 70 degreeC and 10 hours, and the said mat was hardened until the intensity | strength which can be handled was obtained. And after removing the plate, it was subjected to secondary curing in an autoclave at a temperature of 165 ° C. for 6 hours to obtain a final wood cement board. A sample was cut out from the obtained wood cement board, and specific gravity and bending strength were measured. The measurement results are shown in FIG. In addition, the measurement of bending strength was performed according to JIS-A-1408.
[0029]
(Comparative Examples 1-7)
Regarding Comparative Examples 1 to 7, wood cement is produced in the same manner as in Example 1 except that the raw materials are blended at the composition ratio shown in FIG. 2 and that a part of the silica powder is used as the crystalline siliceous raw material. A plate was obtained and its physical properties were measured. The measurement results are shown in FIG.
[0030]
From FIG. 1 and FIG. 2, it is clear that the specific gravity of the example and the comparative example are all equal, but none of the comparative examples exceeds the bending strength of 10 (N / mm ² ).
Then, from comparison between Examples 1 to 10 and Comparative Example 1, it was found that when the siliceous raw material was crystalline, desired bending strength could not be obtained and the reactivity decreased.
From Comparative Examples 2 and 3, when the calcium / silica molar ratio is smaller than 0.6, the cement is insufficient, so that a desired strength cannot be obtained. When the calcium / silica molar ratio is larger than 1.8, the silicic acid is insufficient. It was found that the desired strength could not be obtained.
From a comparison between Example 7 and Comparative Example 4, it was found that when the brain ratio of the mixed cement was 3500 cm ² / g or less, a predetermined strength could not be obtained.
From Comparative Examples 5 and 6, if the alkali amount is not 0.6 or more and 1.0 or less, the desired strength cannot be obtained, and from Comparative Example 7, the inorganic foam has low compression strength, that is, after compression. It has been found that the desired strength cannot be secured when the bulk density is 0.5 or more.
[0031]
【The invention's effect】
According to the wood cement board concerning this invention, there exists an effect that the lightweight wood cement board which has desired intensity | strength can be obtained.
[Brief description of the drawings]
FIG. 1 is a chart showing an example of a wood cement board according to the present invention.
FIG. 2 is a chart showing a comparative example of a wood cement board according to the present invention.

Claims (3)

After mixing the hydraulic material containing the amorphous siliceous raw material, the inorganic foam and the wooden material, water is added and the mixture obtained by mixing is pressure-molded and autoclaved in the wooden cement board,
The hydraulic material has a calcium / silica molar ratio of 0.6 to 1.8, a Blaine specific surface area of 3800 cm ² / g or more, and an alkali content of 0.6 to 1 with respect to 100 parts by weight of the hydraulic material. 0.0 part by weight, alkali sulfate is added as an additive to the hydraulic material,
The inorganic foam is at least one selected from the group consisting of pearlite, obsidian foam, and shirasu foam having a bulk density of 0.4 at a water pressure of 5 Mpa,
The solid component of the mixture contains 35 to 70% by weight of the hydraulic material and 10 to 25% by weight of the inorganic foam. _2. The wood cement board according to claim 1, wherein the hydraulic material is made of Portland cement and fly ash, and the content of 3CaO.SiO ₂ in the Portland cement is 63% or more. After mixing hydraulic material, inorganic foam and wood material containing amorphous siliceous raw material, water is added and mixed to obtain a mixture. After this mixture is pressure-molded, wood cement is cured by autoclave In the manufacturing method of a board,
The hydraulic material has a calcium / silica molar ratio of 0.6 to 1.8, a Blaine specific surface area of 3800 cm ² / g or more, and an alkali content of 0.6 to 1 with respect to 100 parts by weight of the hydraulic material. 0.0 part by weight, alkali sulfate is added as an additive to the hydraulic material,
The inorganic foam is at least one selected from the group consisting of pearlite, obsidian foam, and shirasu foam having a bulk density of 0.4 at a water pressure of 5 Mpa,
A solid component of the mixture is obtained by mixing 35 to 70% by weight of the hydraulic material and 10 to 25% by weight of the inorganic foam.

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