JP3279897B2 - Wood cement board manufacturing method - Google Patents

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 wood cement board mainly used for construction.

[0002]

2. Description of the Related Art Conventionally, a wood cement board in which a wood reinforcing material such as a piece of wood, wool, wood pulp or the like is mixed with cement has been provided as a building board such as an outer wall material or an inner wall material. As a method of manufacturing the wood cement board, a molding material in which a wood reinforcing material is mixed with a cement-based inorganic powder such as cement has been recently sprayed on a template to form a mat, and the mat is heated and pressed to form a primary material. A dry method in which a cured product is manufactured, and then the primary cured product is demolded and cured so as to be finally cured has been awarded. According to the dry method, a wood cement board having a three-dimensional uneven pattern on its surface is easily manufactured, and such a wood cement board is highly evaluated as an outer wall material.

[0003]

However, in the above-mentioned conventional dry production method, although the hardening of the cement-based inorganic powder is promoted by heating and pressing, it takes 10 to 10 days to reach the demolding after pressing. It requires a long period of time, and the efficiency of use of the template is poor, and there is a problem that a large number of templates are required to cope with mass production, and the investment in the template becomes large. (Eg, Japanese Patent Application Laid-Open No. 54-48821).
issue). The reason why it takes a long time before demolding after pressing is that cement-based inorganic powders require a long time for hydration and hardening, and when demolded in a short time, the molding material causes springback. It is mentioned that a molded article having a desired shape cannot be obtained. Particularly in some tree species such as larch, yellow lauan, etc., when a cement hardening inhibitor such as saccharides contained in wood acts on the cement inorganic powder, it inhibits the hardening of the cement inorganic powder. Further, the curing time is delayed, and the curing often becomes poor, making molding impossible. However, from the viewpoint of effectively utilizing the world's timber resources, it is desirable to use any tree species as the raw material, and it is also desirable to use wood scrap generated by dismantling buildings, etc. A wide variety of tree species are used in the wood scrap, and therefore, the wood scrap often includes a tree species containing a large amount of the saccharide, and it is difficult to sort out and remove only such a tree species, and Very laborious. Furthermore, even if it is the same tree species, there is a problem that the sugar content differs between the core material and the sapwood, and the time from press molding to demolding varies greatly. Therefore, there has been a long-awaited demand for a method of manufacturing a wood cement board that shortens the time from press forming to demolding and keeps it substantially constant irrespective of the type of wood reinforcing material, core material, or sapwood.

[0004]

According to the present invention, as a means for solving the above-mentioned conventional problems, a cement-based inorganic powder 45 is used.
To 80 parts by weight, 8 to 40 parts by weight of silica fine powder, 10 to 35 parts by weight of wood reinforcing material, and 2 to 15 parts by weight of an alkali metal silicate mixed with 100 parts by weight of the cement-based inorganic powder. Forming the mat by spraying a molding material having a water content adjusted to 40 to 60% by weight on a mold plate to form a mat; pressing the mat and spraying water vapor to perform a primary curing; and a primary curing. It is intended to provide a method for producing a wood cement board comprising a step 3, in which a mat is cured in an autoclave under high temperature and pressure in a water-containing state and finally cured, and the above steps 1, 2, and 3.

[Cement-based inorganic powder] The cement-based inorganic powder used in the present invention includes calcium silicate and / or
Alternatively, it is a hydraulic inorganic powder containing aluminum silicate as a main component, and examples of such an inorganic powder include Portland cement and alumina cement.

[Silica Fine Powder] The silica fine powder used in the present invention is, for example, a silica substance containing 55% by weight or more of a silica component such as fine silica powder, silica sand, fly ash, silica fume, volcanic ash, and clay. These silica fine powders may be used alone or in combination of two or more.

[Wood reinforcement] Wood reinforcement, wood wool, wood chip, wood fiber, wood pulp, wood fiber bundle, etc. are used as wood reinforcement in the present invention. A material containing lignocellulose as a main component such as fiber, bacas, fir, rice straw, etc. may be mixed. Preferred wood reinforcing materials are wood pieces having a width of 0.5 to 2.0 mm, a length of 1 to 20 mm, a length to thickness ratio of 20 to 30 and a diameter of 0.1 to 0.1 mm.
There are 2.0 mm, 2-35 mm long branches and / or curved and / or bent wood fiber bundles.

[Inorganic lightweight body] In the present invention, an inorganic lightweight body may be added in addition to the cement-based inorganic powder and the wood reinforcing material. Examples of the inorganic lightweight body include perlite, shirasu balloon, expanded shale, expanded clay, calcined diatomaceous earth, coal waste, and crushed foam concrete. The inorganic lightweight body is usually added in an amount of 30 parts by weight or less based on the total solid content of the mixture.

[Alkali metal silicate] The alkali metal silicate used in the present invention includes lithium silicate, potassium silicate, sodium silicate and the like. Desirable alkali metal silicates include potassium silicate and sodium silicate which are inexpensive and readily available. The molar ratio of the desired silicate and an alkali metal in said alkali metal silicate is _{Si O 2 / Na 2 O =} 2~4, Si O 2 / K 2
O = 3-4.

[Third component] If desired, the above composition may further contain a cement hardening accelerator such as aluminum sulfate, magnesium sulfate, calcium sulfate and aluminate, or a waterproofing agent such as wax, wax, paraffin, surfactant and silicone. Or a water repellent may be added.

[Manufacture of Wood Cement Board] In order to manufacture the wood cement board of the present invention, a prescribed amount of the above composition is usually mixed to prepare a molding material. In this case, 45 to 80 parts by weight of the cement-based inorganic powder, 8 to 40 parts by weight of the silica fine powder, 10 to 35 parts by weight of the wood reinforcing material, and 100 parts by weight of the alkali metal silicate are added to 100 parts by weight of the cement-based inorganic powder. 2 for
The mixture is added and mixed at a ratio of １５15% by weight, and water is added to the mixture to adjust the water content to 40〜60% by weight to obtain a molding material. As a preferable preparation method, the above-mentioned wood reinforcing material and the above-mentioned alkali metal silicate salt diluted with water are mixed to allow the alkali metal silicate salt to penetrate into the wood reinforcing material, and then the above-mentioned cement-based inorganic powder and aggregate, etc. Is added and mixed. The molding material thus prepared is sprayed on a template to form a mat (step 1). Next, the periphery of the mat is sealed with a seal frame material and pressed, and steam is injected and heated to accelerate the curing reaction of the mat, and the size and specific gravity of the mat are regulated by the seal frame material. The mat is primarily cured by holding the water vapor inside the seal frame material (step 2). The pressure of the steam applied in the heating and pressing is 0.12 to
The injection time is usually 2 to 10 seconds, the pressing pressure is usually 2 to 5 MPa, and the pressing time is usually 2 minutes or more and 20 minutes or less. ~ 15 minutes. If the steam injection time is less than 2 seconds, the primary curing of the mat becomes insufficient, and the demolding workability tends to deteriorate, and the strength and freeze-thaw resistance of the obtained product may not be satisfied. In this case, the primary cured material of the mat may burst, so in this case, before releasing the primary cured product, maintain the pressure-tightened state.Open the pressure reducing valve etc. to reduce the internal pressure of the mat in the seal frame material. It is necessary to gradually lower to prevent the primary cured product from bursting. The primary cured material of the mat obtained after the above-mentioned pressing is subjected to autoclave curing under high temperature and high pressure in a water-containing state (step 3). The conditions for the above-mentioned autoclave curing are usually set at a temperature of 130 to 165 ° C. and a saturated steam pressure of 0.28 to 0.73 MPa, and under these conditions, the curing time is 5 to 15 hours. The primary cured product is finally cured by short-time curing in the autoclave. After the curing, the product is subjected to a surface treatment if necessary through a drying process to obtain a product. Except for the above embodiment, in the pressing step, the steam may be jetted from the back surface of the mat, or may be jetted from both the front and back surfaces. The wood cement board of the present invention may have a two-layer structure or a three-layer structure. In the case of a two-layer structure, first, a molding material in which a wood reinforcing material having a fine particle diameter is mixed is sprayed on a template, and then a molding material in which a wood reinforcing material having a large particle diameter is mixed thereon is molded. A mat having a two-layer structure is formed by spraying on a board, and the mat is heated and pressed to form a surface layer portion having a dense structure using a molding material in which a wood reinforcing material having a fine particle diameter is mixed. A back layer having a rough structure is formed by a molding material mixed with a wood reinforcement having a large diameter. Furthermore, in the case of a three-layer structure, a molding material in which a wood reinforcing material having a fine particle diameter is mixed is further sprayed thereon to form a three-layer structure mat, and the mat is heated and pressed to obtain the above-described particle diameter. The layer made of the molding material in which the wood reinforcing material having a large particle size is mixed is used as the core layer portion, and the layer made of the molding material in which the wood reinforcing material having a small particle diameter is mixed is used as the back layer portion. In the case of forming a three-layer structure, two mats having the two-layer structure may be stacked and heated and pressed. In this case, the mat is laminated so that layers of a molding material mixed with a woody fiber having a large particle diameter are in contact with each other.

[0012]

The molding material comprising a mixture of a cement-based inorganic powder, a silica fine powder, a wood reinforcing material, an alkali metal silicate and, if desired, an inorganic lightweight body is formed as a mat on a template, When the mat is pressed and water vapor is injected, the mat is rapidly heated to the inside, and the alkali metal silicate rapidly reacts with the cement-based inorganic powder and the silica fine powder. That is, an alkali metal component of the alkali metal silicate (Li ₂ O, K ₂ O, Na ₂ O, etc.)
And the silica fine powder accelerate the hydration hardening of the cement-based inorganic powder, and the silicic acid (SiO ₂ ) gels and reacts with the lime (CaO) of the cement-based inorganic powder to produce wood. Even when the reinforcing material contains a cement hardening inhibitor such as a saccharide, the hardening of the cement-based inorganic powder proceeds smoothly as a whole on the mat. Since the mat which has been primarily cured in this way has a sufficient primary strength for the demolding operation, it can be demolded by pressing for a short time (preferably 2 to 15 minutes). When the aqueous alkali metal silicate solution is first infiltrated into the wood reinforcing material, the above-mentioned reaction is performed with the cement-based inorganic powder around which the aqueous alkali metal silicate solution is present from the wood reinforcing material by pressing. . In this case, when the wood reinforcement contains a cement hardening inhibitor, the surface of the wood reinforcement is coated with the alkali metal silicate when the aqueous solution of the alkali metal silicate is penetrated into the wood reinforcement. In this state, the elution of the cement hardening inhibitor contained in the wood reinforcing material is prevented, so that the hardening of the cement inorganic powder proceeds more smoothly. The primary curing mat is finally cured in a short time by curing under high temperature and pressure in an autoclave.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] FIGS. 1 to 5 show one embodiment of a process for manufacturing a wood cement board of the present invention. In FIG. 1, the conveyor
(2) transports the template (1) in the direction of the arrow, and
The mold release agent is sprayed from the spray nozzle (3) on the mold surface,
Next, the template (1) is introduced into the forming device (4) by the conveyor (2). The forming device (4) is opposed to a forming chamber (5), a blowing chamber (7) in which a blower (6) provided at an outlet of the forming chamber (5) is installed, and the blowing chamber (7). A back blower (8) provided at an inlet of the forming chamber (5), a hopper (9) provided at a ceiling of the forming chamber (5), and a molding material supply conveyor connected to the hopper (9). (10) and a molding material supply sieve (11) installed on the conveyor (10).

The molding material R is sprayed from the sieve (11) onto a conveyor (10) and is supplied to a hopper of a forming chamber (5).
From (9) into the forming chamber (5),
It is scattered and deposited on the template (1) introduced by the conveyor (2) into the forming chamber (5). At this time, air is blown from the blower (6) of the blower chamber (7) to the inlet side, the molding material R is selected by air, and the molding material R in which the wood reinforcing material having a fine particle diameter is mixed is placed on the lower side. The molding material R in which the wood reinforcing material having a large size is mixed is set to the upper side. At this time, the reverse air is blown to the outlet side by the reverse air blower (8), and the molding material R is scattered and deposited also on a portion which becomes a blind spot with respect to the air blow from the air blower (6) due to the unevenness of the mold surface of the mold plate (1). So that In this way, a mat (12) having a dense structure on the lower side and a coarse structure on the upper side is formed, and the mat (12) is trimmed to a predetermined size, if necessary, and then the pressing device shown in FIG. Introduced in 13).

The pressing device (13) includes a surface plate (15) installed on a base (14) and a lower pressure plate (heat plate) mounted on the surface plate (15). 16), a movable plate (18) attached to the lower end of the hydraulic cylinder (17), an upper pressure plate (19) which is a hot plate attached below the movable plate (18), A steam injection plate (20) mounted below the pressure plate (19),
A seal frame member (22) which is a seal means disposed below the steam injection plate (20) and suspended by a link (21).
And a frame (23) that supports the hydraulic cylinder (17) and guides the movable plate (18). The above steam injection board (20)
As shown in FIG. 3, is a main body (24), a steam pipe (25) inserted into the main body (24), and a number of nozzles which are inserted from the steam pipe (25) and open on the lower surface of the main body (24). It consists of a pipe (26).

The mat (12) formed by the forming device (4) is introduced into the pressing device (13) and set on a lower pressing plate (16) as shown in FIG.
As shown in the figure, the lower pressurizing plate (16) and the upper pressurizing plate (19) are pressed together and the periphery thereof is sealed with a seal frame (22).
As described above, the pressing pressure in this case is usually 2 to 5 MPa. Then, when the predetermined pressure is reached, steam is injected from the steam injection plate (20) to the mat (12) through the steam pipe (25) and the nozzle pipe (26). As described above, the pressure of the steam is 0.12 to 0.30 MPa, and the injection time is usually 2 to 10 seconds. In this case, a releasable net or mat, such as a glass fiber net coated with Teflon resin, may be interposed between the mat (12) and the steam jet plate (20) so that steam can pass through. Further, instead of the sealing frame member (22), a sealing means such as a rubber belt or a heat-resistant adhesive tape may be used for sealing.

As described above, by the steam jetting on the mat (12), the hardening proceeds smoothly by the reaction between the cement-based inorganic powder and the alkali metal silicate, and the primary strength is reduced in a short time (usually within 5 minutes). And the demolding work becomes easier. As described above, the primary strength of the mat (12) is improved in a short time during the press forming, and the demolding operation is facilitated, so that the upper pressing plate (19) of the pressing device (13) is raised. The mold is opened, and the primary curing mat (27) shown in FIG. 5 is removed from the mold plate (1).

Embodiments 2 to 11 Using the forming apparatus (4) and the pressing apparatus (13) of Embodiment 1, Tables 1 and 2 were used.
The wood cement board samples 1 to 10 were manufactured using the molding material having the following composition under the pressing curing conditions shown in Tables 1 and 2. Wood cement board samples 1 to 10 produced in Examples 2 to 16 above
The physical properties of are shown in Table 1.

[0019]

[Table 1]

[Comparative Examples 1 to 3] Using the forming material (4) and the pressing device (13) of Example 1 and the molding material having the composition shown in Table 2, wood materials were obtained under the pressing curing conditions shown in Table 2. Cement board samples 11 to 13 were manufactured. Table 2 shows the physical properties of the wood cement board samples 11 to 13 manufactured in Comparative Examples 1 to 3.

[0021]

[Table 2]

[Discussion] Sample 11 of Comparative Example 1 contains silica fume, which is a fine silica powder, in an amount of less than 8 parts by weight, and has a low mixing ratio of silica component to cement-based inorganic powder. An attempt was made to produce calcium silicate from hydrothermal synthesis by curing under high temperature and high pressure in an autoclave, but the strength development was slightly lower than that of Samples 1 to 10 of Examples of the present invention, and the freeze-thaw resistance was poor. It was enough. Sample 13 of Comparative Example 3 had the same composition as Sample 2 of Example 3 and was subjected to natural curing for 7 days in place of autoclave curing. In natural curing, the calcium silicate reaction was continued for as long as 14 days. And the desired physical properties could not be obtained. On the other hand, the products of Examples 1 to 10 are
Both exhibit good physical properties with excellent freeze-thaw resistance.

[0023]

According to the present invention, the pressing time can be greatly reduced in the present invention, so that the investment in the mold plate can be greatly reduced, and curing at a high temperature and high pressure in an autoclave can reduce the natural curing. The curing process time can be greatly reduced, and construction waste can be reused regardless of the type of wood reinforcing material, and a wood cement board with extremely efficient thickness and stable physical properties can be manufactured.

[Brief description of the drawings]

 1 to 5 show one embodiment of the present invention.

FIG. 1 is a process chart of mat forming.

FIG. 2 is a schematic view of a pressing device.

FIG. 3 is a schematic cross-sectional view of a steam injection board.

FIG. 4 is a schematic view of a pressing device in a pressed state.

FIG. 5 is a side sectional view of a molded product.

[Explanation of symbols]

 12 Mat 13 Pressing device 27 Primary curing mat

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // (C04B 28/02 C04B 14:04 Z 14:04 18:06 18:06 22:08 A 22:08 16:02) Z 16: 02) B28B 11 / 00A (56) References JP-A-3-131554 (JP, A) JP-A-3-218955 (JP, A) JP-A-7-69692 (JP, A) JP-A-55- 154366 (JP, A) JP-A-8-259302 (JP, A) JP-A-8-225379 (JP, A) JP-T-62-500930 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 28/02 C04B 16/02 C04B 18/26 C04B 18/24 C04B 22/06-22/16

Claims (5)

(57) [Claims] 1 to 45 parts by weight of a cement-based inorganic powder, 8 to 40 parts by weight of a silica fine powder, 10 to 35 parts by weight of a wood reinforcing material, and 10 parts by weight of an alkali metal silicate.
Step 1 of forming a mat by spraying a molding material in which the water content of a mixture obtained by mixing 2 to 15 parts by weight with respect to 0 part by weight is adjusted to 40 to 60% by weight, and forming the mat; Step 2 of primary hardening by spraying water vapor. Step 3 of curing the primary-cured mat under high temperature and pressure in an autoclave in a water-containing state and finally hardening the same. Production method 2. The method for producing a wood cement board according to claim 1, wherein an inorganic lightweight body is further added to said molding material in an amount of 30 parts by weight or less. 3. The wood cement board according to claim 1, wherein the alkali metal silicate is one or more alkali metal silicates selected from lithium silicate, potassium silicate and sodium silicate. Production method 4. The water vapor pressure in step 2 is 0.12 to 0.1.
The method for producing a wood cement board according to claim 1, wherein the pressure is 30 MPa, the injection time is 2 to 10 seconds, and the pressing time is 2 minutes to 20 minutes. 5. An autoclave curing condition in the step 3 is a temperature of 130 to 165 ° C. and a saturated steam pressure of 0.28 to 0.7.
The method for producing a wood cement board according to claim 1, wherein the curing time is 3 MPa and the curing time is 5 to 15 hours.