JP2685517B2 - Wood cement board manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a technique for producing a wood cement board by hot pressing and a technique for insolubilizing a hydration inhibiting component of cement by a component of wood chips.

[Prior art] Wood cement board is JIS A 5404 "wood wool cement board" and JI
SA 5417 can be roughly divided into "wooden cement boards".

The general method for producing the above-mentioned wood wool cement board and wood chip cement board is as follows.

First, wood wool cement boards are manufactured from so-called wood wool with a thickness of 0.3 to 0.7 mm, a width of 5 to 10 mm, and a length of 400 to 700 mm, which is the main raw material. It becomes one component of. This wood wool elutes the hydration-inhibiting component of Portland cement used depending on the tree species, and may cause hardening of the cement, so MgSO ₄ , CaCl ₂ ,
These hydration inhibiting components may be rendered harmless by Ca (OH) ₂ or the like. The mixing ratio of raw materials is 40 to 45 in terms of absolute dryness of wood wool.
%, Portland cement 55-60%, water / cement ratio
45-60%. After mixing these components, primary molding is performed on the lower plate using a disperser having a dispersing function such as a pin roller so that the lower plate has a uniform thickness. Next, stack a plurality of the primary molded products and apply a pressure of 0.3-2 kg / cm ² to 2
Next molded.

It is carried out from the press using a restraint jig that does not release the pressure during secondary molding, the cement hardens, and strength is developed until the plate thickness during pressing is maintained.
It is cured for 24 hours. After that, the restraint jig is removed, curing (usually about 1 to 2 weeks), drying, and cutting are performed, and the product is manufactured.

On the other hand, the wood chip cement board is almost the same as the method for manufacturing the wood wool cement board, except that the difference is that the wood wool has a thickness of 0.1
~ 0.5 mm, width 0.1 ~ 5 mm, length 0.2 ~ 10 mm wood pieces are used, and the mixing ratio is large, with a large amount of cement, and wood quality (converted to dryness) 20 to 30
%, Cement 70 to 80%, water cement ratio 55 to 65%, and secondary molding at a pressure of 15 to 40 kg / cm ² .

However, it is still removed from the lower plate 20 to 24 hours after the cement hardens using the jig for restraining the pressure.

Wood wool cement board has a small amount of cement and a low secondary molding pressure, resulting in a low bulk density of 0.4 to 0.7 g / cm ^3, and a semi-inflammable and excellent heat insulating property, so ceiling boards and interior / exterior As the base material of, and wood chip cement board has a large amount of cement,
Since the secondary molding pressure is high, the bulk density is also high at 1.1 to 1.3 g / cm ³ , and the bending strength is 100 to 130 kg / cm ² , so it is used in parts requiring strength such as flooring and exterior. There is.

The above-mentioned method for producing a wood wool cement board or a wood chip cement board has the following drawbacks: It takes 20 to 24 hours to remove the lower plate from the lower plate; Requires a large number of lower plates; requires a jig for holding the secondary molding pressure; requires a step of removing the jig for holding the secondary molding pressure.

In order to eliminate such drawbacks, in JP-A-55-154366, in a method of producing a wood cement board through a molding process and a pressing process, a mixture containing a wood material and cement as main components is molded. Disclosed is a method for producing a wood cement board, which is characterized in that the mixture is made to contain additives such as paper, pulp, cloth and the like containing a cement hardening accelerator at an appropriate stage before the process. In this method, the cement hardening accelerator oozes out from the additives only when pressure is applied in the pressing step, and the molded product is hardened by it, so multiple molded products are stored and pressed together. You will be able to do that.

[Problems to be Solved by the Invention] However, the above-mentioned method is used to prepare a mixture of a fibrous substance, such as paper, pulp, or cloth, which is easily impregnated with and exudes an aqueous solution of a cement hardening accelerator, from which a wood material and cement are the main components. Since the curing accelerator is only partially spread because of being compounded, there is a problem that the pot life varies and the strength varies.

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

[Means for Solving the Problems] That is, according to the present invention, a mixture containing a wood material and cement as main components is molded and hot-pressed 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 consisting of, the mixture has a Blaine specific surface area of 5000 to 1500 as a hardening accelerator for cement.
The present invention relates to a method for producing a wood cement board, which comprises adding 0 cm ² / g of anhydrous aluminum sulfate in an amount of 2 to 8% by weight based on the weight of cement.

Furthermore, the present invention is a method for producing a wood cement board, which comprises molding and hot pressing a mixture having a pot life of 30 minutes or less and a hot pressing time of 20 to 60 minutes, which is mainly composed of a wood material and cement. In the above, as a hardening accelerator for cement, a saturated aluminum sulfate aqueous solution is added to the mixture in an amount of Al ₂ (SO ₄ ) ₃ equivalent to 0.2 to an outer percentage based on the weight of the cement.
The present invention relates to a method for producing a wood cement board, characterized in that 0.6% is added, and 1.8 to 7.4% of anhydrous aluminum sulfate is added to the weight of cement in an outer proportion.

[Operation] As the mixture mainly composed of the wood material and cement used in the method of the present invention, any conventional mixture can be used. Also, the water / cement ratio is 50-
It may be about 70%.

Anhydrous aluminum sulphate, which is a cement hardening accelerator added to the mixture, dissolves only about 6% at room temperature in the compounded water, but it dissolves about 30% at about 40 ° C and almost all at about 60 ° C (about 98%) dissolves and becomes an aqueous solution. This Al
₂ (SO ₄ ) ₃ aqueous solution and the main component of Voltland cement 3
CaO · SiO ₂ and 2CaO · SiO ₂ react to form ettringite and harden the cement. For example, in the former case, ettringite is generated by the reaction of Al ₂ (SO ₄ ) ₃ +2 (3CaO · SiO ₂ ) + water = 3CaO · Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O + 2SiO ₂ (amorphous). This ettringite causes a volume expansion of about 8 times, and if chemical prestress is generated inside the wood cement board by causing the ettringite formation reaction during the pressing process, it is possible to immediately remove the board by pressing for a short time. .

In the method of the present invention, in order to improve the production efficiency when producing a wood cement board by the above-mentioned ettringite formation, the pot life of the mixture containing wood material and cement as the main component is within 30 minutes, and the hot pressing time is 20 to It is characterized by setting the condition of 60 minutes and adopting the following two methods for adding anhydrous aluminum sulfate, which is a cement hardening accelerator, in order to satisfy this setting condition: Blaine specific surface area 5000 to 15000 cm the ² / g anhydrous aluminum sulfate is added 2-8% by weight outer percentage relative to the weight of the cement; 0.2 outside split based on the weight of the cement of a saturated aqueous solution of aluminum sulfate with Al ₂ (SO _{4) 3} in terms of weight Add 0.6% and add anhydrous aluminum sulfate to the weight of cement 1.8-7.4%
Added.

The dissolution rate of anhydrous aluminum sulfate in water is, for example, Al
₂ (SO ₄ ) ₃・ 16H ₂ O ~ 18H ₂ O It is very slow compared to other aluminum sulfates such as O, and it is used to adjust the above-mentioned ettringite formation timing, that is, the set condition of the mixed solution. You can

Here, the reason for using those having a Blaine specific surface area of 5000 to 15000 cm ² / g as anhydrous aluminum sulfate in the method is that the specific surface area of less than 5000 cm ² / g causes a concentration gradient because it is difficult to dissolve, resulting in variations in strength. Bring Also, if the specific surface area exceeds 15000 cm ² / g, the dissolution rate will rapidly increase and the pot life will be shortened.

Further, when producing a wood cement board, the hydration inhibiting component of the cement due to the wood material blended as described above may be eluted, and a treatment for detoxifying the hydration inhibiting component is necessary. There are cases where

In the method of the present invention, this detoxification treatment is carried out by two methods. The first method is to add anhydrous aluminum sulfate to a mixture containing wood material and cement as main components, and further add a component selected from the group consisting of sulfuric acid, nitric acid, aluminum chloride and ferric chloride II. Can be done. The mechanism of why these components are effective in detoxification treatment is unknown. Addition of 0.5 to 5% of the above components relative to the weight of cement is effective for detoxifying treatment.

The second method of detoxification is the above using saturated aluminum sulfate with anhydrous aluminum sulfate. Although the mechanism of this detoxification treatment is not clear, detoxification treatment can be performed by adding a part of anhydrous aluminum sulfate added as a hardening accelerator for cement as a saturated aluminum sulfate aqueous solution. This saturated aluminum sulfate aqueous solution acts as a detoxifying treatment and also as a cement hardening accelerator. Saturated aluminum sulfate aqueous solution
Al ₂ (SO ₄ ) ₃ equivalent amount of 0.2 to 0 in proportion to the weight of cement.
Addition of 6% is effective for detoxification treatment.

In the present invention, the total amount of anhydrous aluminum sulfate or anhydrous aluminum sulfate and a saturated aqueous solution of aluminum sulfate is _{2 to} the weight of the cement in terms of Al ₂ (SO ₄ ) _{3 in} proportion to the total.
8%. If the ratio is less than 2%, the strength is low, which is not preferable, and if it exceeds 8%, ettringite is rapidly produced in large amounts during mixing, which is not preferable.

When hot press conditions are, for example, 20 to 30 kg / cm ² , temperature
Pressurization is preferably 40 to 60 minutes at 50 ° C and 20 to 30 minutes at 95 ° C.

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

Example 1 Amount of 40.7% water content of 0.15 to 0.5 mm in thickness, 0.2 to 1.75 mm in width and 0.3 to 0.5 mm in length of red pine wood chips to 17.6% in absolute dry weight, and total water content (water content of wood chips 29.8% is put into a mixer with a paddle rotation speed of 720 rpm, and after mixing for 30 seconds,
52.6% of early-strength cement was added and mixed for 30 seconds, and then 5% of anhydrous aluminum sulfate powder with a Blaine specific surface area of 7000 cm ² / g (manufactured by Daimei Kagaku Kogyo Co., Ltd.) was added to the cement, and further for 30 seconds. A raw material mixture was obtained by mixing. The pot life of this product was as shown in Table 1.

Next, the obtained raw material mixture was placed in a frame of 60 × 300 × 300 mm.
15 minutes after the next molding and adding the wood chips and the total amount of water, hot pressing was performed at a pressure of 25 kg / cm ² and a temperature of 50 ± 5 ° C. for 60 minutes using a press machine, and immediately removed from the test piece. Got

This specimen was aged at a temperature of 30 ± 1 ℃ and a humidity of 86-90% for 7 days, then cut into 50 × 200 × 200mm, and made a constant weight with an electric heat dryer at 45 ± 2 ℃, and then subjected to a bending test. I served.

 The results obtained are shown in Table 1.

Example 2 Anhydrous aluminum sulfate having a Blaine specific surface area of 12000 cm ²
A sample was obtained by the same method as in Example 1 except that the sample was changed to / g.

 The characteristics of the obtained specimen are also shown in Table 1.

Example 3 Instead of anhydrous aluminum sulfate, an amount of a saturated aluminum sulfate aqueous solution and 4.8% of anhydrous aluminum sulfate having a Blaine specific surface area of 12000 cm ² / g were calculated so as to be 0.2% based on Al ₂ (SO ₄ ) _{3 in} terms of Al ₂ (SO ₄ ) _3. Specimens were obtained in the same manner as in Example 1 except that they were used in combination.

 The characteristics of the obtained specimen are also shown in Table 1.

Comparative Examples 1-3 As a cement hardening accelerator, 5% of triethanolamine was added instead of anhydrous aluminum sulfate, and 5% of an aqueous solution of aluminum sulfate was added in an amount equivalent to Al ₂ (SO ₄ ) ₃ or not added. Was used under the same conditions as in Example 1, and a bending test was conducted in the same manner as in Example 1.

 The results obtained are shown in Table 1.

Examples 4 to 7 The water content of 39.5% of a piece of Karamatsu wood (having a significantly higher hydration inhibiting effect on cement than that of Akamatsu wood) having a size similar to that of the piece of Akamatsu wood of Example 1 was changed to 17.6% by absolute dry weight. And total water content (including water content of wood chips) 29.8% and reagent grade sulfuric acid and nitric acid 2% or 1% of added water to cement
2% of the aluminum chloride solution and ferric chloride solution dissolved in 1 part of the cement was added to the mixer at a paddle rotation speed of 720 rpm, and the mixture was mixed for 30 seconds.
, Mix for an additional 30 seconds, then
12000 cm ² / g of anhydrous aluminum sulfate was added to the cement in an amount of 5% by external splitting, and similarly mixed 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 the lower plate 60 × 30.
After the primary molding in a 0 × 300 mm frame, 15 minutes after adding the wood chips and the total amount of water, use a press machine to produce a pressure of 25 kg / cm ² , 50
Hot pressing was performed for 40 minutes at a temperature of ± 5 ° C., and immediately removed to obtain a test piece.

This specimen was aged at a temperature of 30 ± 1 ℃ and a humidity of 86-90% for 7 days, then cut into 50 × 200 × 200mm and made to a constant weight with an electric heat dryer at 45 ± 2 ℃, and then subjected to a bending strength test. I went to

 The results obtained are shown in Table 2.

Comparative Example 4 Specimens were obtained in the same manner as in Example 4 except that anhydrous aluminum sulfate having a Blaine specific surface area of 12000 cm ² / g was added to the early-strength cement in an amount of 5% by external splitting.

 The results obtained are shown in Table 2.

[Effects of the Invention] According to the present invention, a wood cement board can be manufactured in a short time and without the need for a jig for holding the secondary molding pressure.

Claims (3)

(57) [Claims] 1. The pot life is within 30 minutes, and hot press time is
In a method for producing a wood cement board, which comprises molding and hot pressing a mixture containing a wood material and cement as main components set to 20 to 60 minutes, the mixture has a Blaine specific surface area of 5000 to 15000 cm as a hardening accelerator for cement. ²
A method for producing a wood cement board, characterized in that / g of anhydrous aluminum sulfate is added in an amount of 2 to 8% based on the weight of the cement. 2. The pot life is within 30 minutes, and the hot press time is
In a method for producing a wood cement board, which comprises molding and hot-pressing a mixture containing a wood material and cement set to 20 to 60 minutes, a saturated aluminum sulfate aqueous solution is added to the mixture as a hardening accelerator for cement.
₂ (SO ₄ ) ₃ equivalent amount 0.2 to 0.6
%, And 1.8 to 7.4% of anhydrous aluminum sulfate is added to the weight of the cement as a percentage, and the method for producing a wood cement board. 3. The woody material according to claim 1 or 2, wherein a component selected from the group consisting of sulfuric acid, nitric acid, aluminum chloride and ferric chloride II is added to the mixture in an amount of 0.5 to 5% based on the weight of the cement. Cement board manufacturing method.