JPH0230650A - Production of wooden cement board - Google Patents

Abstract

PURPOSE:To rapidly and efficiently obtain a wooden cement board by setting pot life and hot-pressing time of a mixture consisting essentially of a wooden material and cement within specific ranges and adding a specified amount of anhydrous aluminum sulfate which is a cement hardening accelerator to the mixture so as to satisfy the afore-mentioned conditions. CONSTITUTION:A mixture, consisting essentially of a wooden material and cement and having pot life set within 30min and hot-pressing time set at 20-60min is formed and hot-pressed to produce a wooden cement board. In the process, anhydrous aluminum sulfate having 5,000-15,000cm<2>/g Blaine specific surface area as a hardening accelerator for the cement in an amount of 2-8% in outer percentage based on the cement weight is added to the afore-mentioned mixture. If treatment for detoxifying hydration inhibitory components of the cement caused by the wooden material is required, a saturated aqueous solution of aluminum sulfate as the cement hardening accelerator in an amount of 0.2-0.6% in outer percentage based on the cement weight expressed in terms of Al2(SO4)3 is added and anhydrous aluminum sulfate in an amount of 1.8-7.4% in outer percentage based on the cement weight is added.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technology for producing wood cement boards by hot pressing and a technology for insolubilizing components that inhibit cement hydration using components of wood chips.

[Conventional technology] Wood cement board is JIS^5404r wood wool cement board.
and JIS^5417r Wood Chip Cement Board J Wood Chip Cement Board The general manufacturing method of the above-mentioned wood wool cement board and wood chip cement board is as follows.

First, the wood wool cement board has a thickness of 0.3 to 0.7 mm, a width of 5”-1.0 mm, and a length of 4 mm compared to the wood from which the bark has been removed.
00 to 700s+s so-called wood wool is produced, and this is the primary component of the main raw material. This wood wool may elute the hydration inhibiting components of Portland cement used depending on the tree species, resulting in poor hardening of the cement.
H)2 etc. may render these hydration inhibiting components harmless. The blending ratio of raw materials is 40 to 45 in absolute dry terms based on wood wool.
%, portland cement 55-60%, water/cement ratio 45-60%. After mixing these components, the mixture is primarily formed onto the lower plate using a dispersing machine having a dispersion function such as a bin roller so as to have a uniform thickness.

Next, multiple pieces of the primary molded material are stacked to form 0,3
Secondary molding is performed at a pressure of ~2 kg/Cm2.

A restraining jig is used to prevent the pressure from escaping during the secondary forming process, and the cement is removed from the press to harden and maintain the strength required to maintain the thickness of the plate during pressing.
Cured for 24 hours. After that, the restraint jig is removed, and the product is made into a product through the steps of curing (usually about 1 to 2 weeks), drying, and cutting.

On the other hand, the manufacturing method for wood chip cement boards is almost the same as that for wood wool cement boards, but the difference is that instead of using wood wool, the thickness is 0.1
~0.5I, width 0.1~51, length 0.2~110ll
1 wood chips are used, and the mixing ratio is also high in cement: 20-30% wood chips (absolutely dried JE), 70-80% cement,
The water-cement ratio is 55-65% and the pressure is 15-40%.
ky/Cm2.

However, the main plate is still removed from the lower plate 20 to 24 hours after the cement has hardened using a jig for restraining the pressure.

Wood wool cement board has a small amount of cement and the secondary molding pressure is low, so the bulk density of the product is 0.4 to 0.7 g/crs.
Because it is quasi-noncombustible and has excellent heat insulation properties, it is used as a base material for ceiling panels and interior and exterior exteriors. Wood chip cement boards also have a bulk density of 1.1 because they contain a large amount of cement and require high secondary forming pressure. ~
It has a high bending strength of 1,3 y/cm” and a bending strength of 100 to 1
Because it has a weight of 30 kg/cm2, it is used in areas that require strength, such as flooring and exterior coverings.

The method of manufacturing wood wool cement board or wood chip cement board as described above has the following disadvantages: ■ It takes 20 to 24 hours to form the base board from the lower board; ■ It takes a long time to form the membrane board. Therefore, a large number of lower plates are required; a jig for holding the secondary molding pressure is required; a process for removing the jig for holding the secondary molding pressure is required.

In order to eliminate such drawbacks, Japanese Patent Application Laid-Open No. 55-1543
Publication No. 136 discloses a method for producing a wood cement board by passing a mixture containing wood material and cement as main components through a molding process and a pressing process, in which a cement hardening accelerator is added to the mixture at an appropriate stage before the molding process. A method for manufacturing a wood cement board is disclosed, which is characterized in that it contains additives such as paper, bulbs, and cloth impregnated with.

In this method, the cement hardening accelerator begins to ooze out from the additives due to the pressure applied during the pressing process, which causes the molded product to harden. Therefore, multiple molded products are stored and pressed together. It is something that you will be able to do.

[Problems to be Solved by the Invention] However, the above method does not allow fibrous materials such as paper, valves, cloth, etc., which are easily impregnated with and exuded with an aqueous cement hardening accelerator solution, into a mixture mainly composed of wood materials and cement. Because the curing accelerator is only partially distributed,
There are problems such as the pot life fluctuates and the strength varies.

Therefore, an object of the present invention is to provide a method for quickly and efficiently manufacturing wood-cement board using a wood material and a cement-based mixture with predetermined pot life and hot pressing time. It is in.

[Means for Solving the Problems] That is, the present invention molds and hot presses a mixture whose main components are wood material and cement, with a pot life of 30 minutes or less and a hot press time of 20 to 60 minutes. In the method for producing a wood cement board, the Blaine specific surface area 500 is added to the mixture as a cement hardening accelerator.
The present invention relates to a method for producing a wood cement board, characterized in that 2 to 8% by weight of anhydrous aluminum sulfate is added to the weight of cement in an amount of 0 to 15,000 cm2/g.

Furthermore, the present invention provides a method for producing a wood cement board, which comprises molding and hot pressing a mixture mainly composed of wood materials and cement, with a pot life of 30 minutes or less and a hot pressing time of 20 to 60 minutes. In A I!, a saturated aluminum sulfate aqueous solution was added to the mixture as a cement hardening accelerator. Add 0.2 to 0.6% of the weight of cement in terms of 2(S O4)3, and add anhydrous aluminum sulfate in an amount of 1.8 to 0.6% of the weight of cement.
It relates to a method for manufacturing a wood cement board characterized by adding 7.4%.

[Function] Any conventional mixture containing wood material and cement as main components can be used in the method of the present invention. Also, the water/cement ratio is 50~
It is sufficient if it is about 70%.

Anhydrous aluminum sulfate, which is a cement hardening accelerator added to the mixture, dissolves only about 6% in the mixed water at room temperature, but dissolves about 30% at a temperature of about 4 o'd;
At about 0°C, almost all (about 98%) dissolves, forming an aqueous solution. This A 11C8O4)3 aqueous solution and 3CaO・5if2.2 Ca0-, which is the main component of Portland cement.
It reacts with Siot to produce ettringite and harden the cement.

For example, in the former case, A12(so4)3+2(3CaO・5iO2)earth=3CaO−A1. O,・3CaSO+・32112
Ettringite is produced by the reaction of 0+ 2SiO2 (amorphous). This ettringite expands in volume by about 8 times, and if the ettringite production reaction occurs during the pressing process and chemical prestress is created inside the wood cement board, it is possible to quickly remove the board by pressing in a short time. .

In the method of the present invention, in order to improve the production efficiency when manufacturing wood cement boards by forming ettringite as described above, the pot life of the mixture containing wood material and cement as the main components is within 30 minutes, and the hot pressing time is 20 to 20 minutes. The characteristic is that a condition of 60 minutes was set, and in order to satisfy this set condition, the following two methods were adopted for the addition of anhydrous aluminum sulfate, which is a cement hardening accelerator:
■Brain specific surface area 5000-15000cm” /
Add 2 to 8% by weight of anhydrous aluminum sulfate based on the weight of cement: ■Add saturated aluminum sulfate aqueous solution to A II! 2 (S.O.
n＞*Converted amount is 0.2 to 0 when divided by weight of cement
．． 6% and anhydrous aluminum sulfate is added in an amount of 1.8 to 7.4% based on the weight of the cement.

The dissolution rate of anhydrous aluminum sulfate in water is, for example, A12
It is very slow compared to other aluminum sulfates such as C8O+)-.16 H20 to 18 H20, and this can be used to adjust the timing of the above-mentioned ethrin guide generation, that is, the setting conditions of the mixed liquid.

Here, in the method (2), the Blaine specific surface area of anhydrous aluminum sulfate is 5000 to 15000 cM
The reason for using this is that the specific surface area is 5000cm2/
If the specific surface area is less than 15,000, it will be difficult to dissolve, resulting in a concentration gradient and variations in strength.
This is because when the dissolution rate exceeds cm''/g, the dissolution rate increases rapidly, resulting in a shortened pot life.

In addition, when manufacturing wood cement boards, water phase inhibiting components of cement caused by the wood materials blended as described above may be eluted, and treatment is required to render these water phase inhibiting components harmless. In some cases,

In the method of the present invention, this detoxification treatment is carried out using two methods. One method is to add anhydrous aluminum sulfate to a mixture whose main components are wood material and cement, and further add a component selected from the group consisting of sulfuric acid, nitric acid, aluminum chloride, and ferrous chloride. can be done. The mechanism behind why these components are effective for detoxification treatment is unknown. If this component is added in an amount of 0.5 to 5% based on the weight of cement, it is effective for detoxification treatment.

The second method of detoxification treatment is the above-mentioned method (2) in which saturated aluminum sulfate is used together with anhydrous aluminum sulfate. Although the mechanism of this detoxification treatment is also unknown, detoxification treatment can be performed by adding a portion of anhydrous aluminum sulfate, which is added as a cement hardening accelerator, as a saturated aluminum sulfate aqueous solution. This saturated aluminum sulfate aqueous solution acts as a cement hardening accelerator as well as a detoxifying action. Saturated Fift acid diluminium alkate solution l! If 0.2 to 0.6% of 2 (S O <) is added to the weight of cement in terms of a converted amount, it is effective for detoxification treatment.

In the method of the present invention, the total amount of anhydrous aluminum sulfate or anhydrous aluminum sulfate and a saturated aluminum sulfate aqueous solution is 2 to 8% of the weight of cement in terms of A12 (SQ, )3. If the proportion is less than 2%, the strength will be low, which is undesirable, and if it exceeds 8%, ettringite will rapidly form in large quantities during mixing, which is not preferable.

Hot press conditions are, for example, 20 to 30 ky/cm2
In this case, it is preferable to pressurize for 40 to 60 minutes when the temperature is 50°C, and for 20 to 30 minutes when the temperature is 95°C.

[Example] The method for manufacturing a wood cement board according to the present invention will be further explained below with reference to Examples.

Fire m, moisture content 40.7%, thickness 0.15-0.5 mm, width 0.
2-1.75 mm, length 0.3-0.5 ml 11-inch red pine wood chips have an absolute dry weight of 17.6% and a total water content (including the water content of the wood chips) of 29.8% in the paddle. Rotation speed 720
After adding it to the rpm mixer and mixing for 30 seconds,
Add 52.6% of early strength cement, mix for 30 seconds, then add 5% of anhydrous aluminum sulfate powder (manufactured by Daimei Kagaku Kogyo Co., Ltd.) with a Blaine specific surface area of 7000cm2/g, and then add 30% of the cement. A raw material mixture was obtained by mixing for a second. The pot life of this product was as shown in Table 1.

Next, the obtained raw material mixture is 60X300X300i+
After 15 minutes of putting the wood chips and the total amount of water into an A-shaped frame, hot pressing was carried out using a press for 60 minutes at a pressure of 25 kg/cI112 and a temperature of 50 ± 5°C, and immediately the membrane was formed. A specimen was obtained by preparing a plate.

This specimen was heated at a temperature of 30±1℃ and a humidity of 86 to 90%.
After curing for a day, cut into 50 x 200 x 200 mm.
It was made to have a constant weight in an electric dryer at 45±2°C and then subjected to a bending test.

The obtained results are also listed in Table 1.

Fruit 1 l Anhydrous aluminum sulfate with Blaine specific surface area of 12000
A specimen was obtained in the same manner as in Example 1 except that the value was changed to cm'/g.

The characteristics of the obtained specimens are also listed in Table 1.

Support 1" Σ Instead of anhydrous aluminum sulfate, add saturated aluminum sulfate aqueous solution in an amount so that A[2(SQ,)3 is converted to 0.2% of the external ratio of cement and Blaine specific surface area 120QO
A specimen was obtained in the same manner as in Example 1 except that 4.8% of anhydrous aluminum sulfate (cm2/g) was used in combination.

The characteristics of the obtained specimens are also listed in Table 1.

As a cement hardening accelerator, instead of anhydrous aluminum sulfate, 5% of triethanolamine was added, and an aluminum sulfate aqueous solution was added with 12us O<)*5% of the converted amount or no additives. A comparative product was prepared under the same conditions as in Example 1, and a bending test was conducted in the same manner as in Example 1.

The obtained results are also listed in Table 1.

Table 1: Fruit M Raw Nibi L A piece of Karamatsu wood having almost the same dimensions as the piece of red pine wood in Example 1 (the hydration inhibiting effect of cement is much greater than that of a piece of red pine wood) with a moisture content of 39.5% was completely dried. Dissolve 17.6% by weight, 29.8% total water (including the water content of wood chips), and 1st class reagent sulfuric acid and nitric acid with 2% of the cement or 1 part of the added water. mixer and mix for 30 seconds, then add 52.6% early strength cement, mix for another 30 seconds, and then add Blaine ratio surface W112000611.
2/g of anhydrous aluminum sulfate was added to the cement in an amount of 5% and mixed in the same manner for 30 seconds to obtain a raw material mixture.

The pot life of this product was as shown in Table 2.

Next, the obtained raw material mixture was placed on a 60x3
00x300+a- form frame, 15 minutes after putting in the wood chips and the total amount of water, use a press machine to make 25
Hot pressing was carried out for 40 minutes at a pressure of 50±5° C. and a pressure of 1.5 kg/cm”, and a mother plate was immediately applied to obtain a specimen.

This specimen was heated at a temperature of 30±1℃ and a humidity of 86 to 90%.
- After curing for one day, the pieces were cut into 50 x 200 x 200 mm, dried in an electric dryer at 45±2°C to a constant weight, and then subjected to a bending strength test.

The obtained results are also listed in Table 2.

A specimen was obtained in the same manner as in Example 4, except that 5% of anhydrous aluminum sulfate having a specific surface area of 12,000 cm2/g was added to the early strength cement.

The obtained results are also listed in Table 2.

First λ - All at once [Effects of the Invention] According to the present invention, a wood cement board can be manufactured in a short time and without requiring a jig to maintain secondary forming pressure.

Patent applicant: Onoda Cement Co., Ltd.

Claims (1)

[Claims] 1. Pot life within 30 minutes, hot press time from 20 to
In a method for manufacturing a wood cement board, which comprises molding and hot pressing a mixture mainly composed of wood material and cement for 60 minutes, the mixture is added with a Blaine specific surface area of 5000 to 150 as a cement hardening accelerator.
1. A method for producing a wood cement board, which comprises adding 2 to 8% of anhydrous aluminum sulfate to the weight of cement. 2. Pot life is within 30 minutes, hot press time is 20~
In a method for producing a wood cement board, which comprises molding and hot pressing a mixture mainly composed of wood material and cement for 60 minutes, a saturated aluminum sulfate aqueous solution is added to the mixture as a cement hardening accelerator.
_2(SO_4)_3 Add 0.2 to 0.6% based on the weight of cement, and add 1.8 to 7.4% of anhydrous aluminum sulfate based on the weight of cement. A method for manufacturing a wood cement board, characterized by: 3. Claim 1 or 2, wherein a component selected from the group consisting of sulfuric acid, nitric acid, aluminum chloride and ferrous chloride is further added to the mixture in an amount of 0.5 to 5% based on the weight of the cement.
The method for manufacturing the wood cement board described.