JPH07124927A - Wood piece cement board - Google Patents

Abstract

PURPOSE:To form a wood piece cement board having a three-dimensional effect by a method wherein a weight ratio of a cement to wood pieces in a center layer of a wood piece cement board of a three-layer structure is determined to be larger than that in surface and back layers. CONSTITUTION:A wood piece cement board of a three-layer structure is formed by integrally compressing a surface layer 6, a back layer 4, and a center layer 5, each of which contains wood pieces and a cement as essential components. A weight ratio of a cement to wood pieces in the center layer 5 is determined to be larger than that in the surface and back layers 6, 4. Namely, a weight ratio of a cement to wood pieces in a dry state in the surface and back layers 6, 4 is 1.5-4.0, and a weight ratio of a cement to wood pieces in the center layer 5 is 2.0-10.0. In this manner, the center layer 5 in a dense state is hard to compress, and the surface and back layers 6, 4 in a coarse state are easy to compress and can be embossed at a low pressure. Therefore, a wood piece cement board having a three-dimensional effect can be produced at a higher productivity, and a required surface strength can be ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wood chip cement board capable of forming a deep embossed pattern with a low pressing pressure.

[0002]

2. Description of the Related Art Conventionally, a wood chip cement board has a non-combustible and non-destructive property that cement has.
It is a material that takes into account the lightness, toughness, and workability of wood, and is widely used as a building board. Then, in order to enhance the cosmetic property, for example, as shown in FIGS. 3 and 4, a mixture 2 of wood chips and cement is sprinkled and deposited on the plate 1, and the plate 3 having an uneven pattern is placed thereon. Then, the wood chip cement board having an embossed pattern was formed.

However, according to the above-mentioned method, it is difficult to form a deep embossed pattern due to the elasticity of the wood piece, and a wood piece cement board having a rich three-dimensional effect cannot be obtained.

For this reason, it has been considered to form a deep embossed pattern by press forming at a higher pressure, but if press forming at a higher pressure, the density of the whole wood chip cement board increases and the workability deteriorates. In addition, large-scale equipment is required for press molding at a higher pressure, and a long pressing time is required, resulting in a problem of reduced productivity.

Therefore, for example, as shown in Japanese Patent Publication No. 5-46289, a mixture of cement and small-sized wood chips is sprinkled on the upper surface of a template having an uneven pattern,
There is disclosed a method for producing a building board having a clear and fine uneven pattern by spraying and depositing a mixture obtained by mixing cement and wood particles having a large particle size and pressing the mixture.

However, in order to manufacture the building board, it is necessary to prepare at least two kinds of wood chips having different particle sizes, which complicates the manufacturing process and increases the production cost. Moreover, since the surface layer of the building board is made of wood chips having a small grain size, it is difficult to obtain desired toughness and surface strength. Therefore, it is conceivable to mix wood chips having a larger particle size in the lower layer in order to increase the strength, but there is a problem that chipping or cracking of the surface layer is unavoidable.

In view of the above problems, it is an object of the present invention to provide a wood chip cement board which is inexpensive in production cost, has a desired surface strength, is excellent in productivity and workability, and has a rich three-dimensional effect. .

[0008]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventors of the present invention have, as a result of intensive research, mixed more cement into the center layer of the three-layered wood chip cement board than in the front and back layers. By doing so, it was found that the central layer becomes dense and it is difficult to compress during pressing, while the front and back layers are easily compressed, and a deep embossed pattern is obtained despite the wood piece rich, and based on this finding The present invention has been completed.

The gist of the present invention is a wood chip cement board having a three-layer structure formed by pressing and integrating a front and back layer and a central layer containing wood chips and cement as essential components, and having an uneven pattern on at least one surface. In the wood chip cement board, the weight ratio of cement to wood chips in the central layer is made larger than the weight ratio of cement to wood chips in the front and back layers. The weight ratio of cement to wood chips in the front and back layers is 1.5 to 4.0 times the dry weight of wood chips, and the weight ratio of cement to wood chips in the central layer is 2.0 to 10 times the dry weight of wood chips. .0
It is preferably doubled.

Any piece of wood can be used as long as it is used for a normal piece of wood cement board, and the kind, shape and size of the wood is not particularly limited, but the size of the wood piece is from 1 to 20 in length.
mm, thickness 0.1-2.0 mm is preferable. This is because the desired strength cannot be obtained outside this range. The amount of wood chips added to the front and back layers is preferably 15 to 40% by weight based on the dry weight of the solid content of the front and back layers. If it is less than 15% by weight, the front and back layers become dense and it becomes difficult to compress at the time of pressing.
This is because if it exceeds 0% by weight, the amount of cement will be smaller than that of wood chips and the strength will decrease. The amount of wood chips added to the center layer is 5 to 35% of the weight of the solid content of the center layer.
It is preferably in the weight%. When it is less than 5% by weight,
This is because it becomes brittle and the strength decreases, and when it exceeds 35% by weight, the central layer becomes rough and is easily compressed, and the front and back layers are hard to be compressed accordingly.

Examples of the cement include Portland cement, blast furnace cement, silica cement and the like, and these can be used alone or in combination. The amount of cement added to the front and back layers is preferably 60 to 80% by weight of the solid content of the front and back layers. This is because if it is less than 60% by weight, the amount of cement with respect to the wood chips is small and the strength is lowered, and if it exceeds 80% by weight, it becomes too dense and difficult to be compressed. The amount of cement added to the central layer is preferably 65 to 90% by weight based on the weight of the solid content of the central layer. This is because if it is less than 65% by weight, the amount of cement with respect to the wood chips is small and the strength is reduced. If it exceeds 90% by weight, it becomes brittle and the strength is reduced
Because it becomes heavy.

The weight ratio of cement to the wood chips to be mixed is 1.5 to the dry weight of the wood chips in the front and back layers.
4.0 times, 2.0 to the dry weight of wood chips in the center layer
It is preferably 10.0 times. This is because if the weight ratio of the front and back layers is less than 1.5 times, the wood cement plate having desired strength cannot be obtained because the amount of cement added is small. Also, if the weight ratio exceeds 4.0 times, the amount of cement added is large, so that the desired uneven pattern cannot be formed due to a dense state, and further, the wood content relatively decreases, This is because the toughness is reduced and practically sufficient strength cannot be obtained. The weight ratio in the central layer is, for example, 1.5% in the front and back layers.
If it is twice, it is necessary to be at least 2.0 times or more to form a deep embossed pattern.
It is preferably 0.0 times or less. If it exceeds 10.0 times, the content of wood will decrease and the toughness will decrease, so that practically sufficient strength will not be obtained and it will become too heavy.

The wood chips and the cement are not limited to the simple substance, but may be contained in a pulverized product of the hydrated and hardened wood-containing cement. Examples of the hydrated-hardened wood-containing cement hardened product include wood chips cement plates, and scraps, cuttings, defective products, and construction wastes produced by cutting. Examples of the pulverized product include those obtained by crushing the end material of the wood chip cement plate with a crusher such as a jaw crusher, and then further finely crushing with a hammer mill or the like. Use of the hardened wood-containing cement thus hydrated has an advantage that waste products can be effectively used.

The smaller the particle size of the crushed product,
It is preferable because the decrease in strength of the wood chip cement plate is reduced and the surface becomes smooth. However, if it is attempted to obtain a pulverized product having a small particle size, the pulverization takes time and the production cost increases, so that the particle size is preferably 0.1 to 5.0 mm. This is because if the particle size is less than 0.1 mm, the production cost will greatly increase, and if it exceeds 5.0 mm, the desired strength cannot be obtained.

The added amount of the crushed material is preferably 50% by weight or less (particularly 20% by weight or less in the front and back layers and 80% by weight or less in the central layer) of the total weight of the wood cement plate. . This is because if it exceeds this, the desired strength cannot be obtained.

The water added to form the wood chip cement board is preferably 30 to 60% by weight of the total wood chip cement board. This is because if it is out of this range, the desired strength cannot be secured.

In addition to the above raw materials, additives may be added if necessary. As the additive, for example,
Examples include hardening accelerators such as magnesium chloride, which may be of a commonly used quality. However, the amount added is preferably 10% by weight or less of the total weight. If it exceeds this, not only is the curing rate too fast and it is difficult to mold, but also chlorine ions cause the metal parts to rust significantly.

Next, a method for manufacturing a wood chip cement board will be described. First, the mixing method of the raw materials can be arbitrarily selected from conventional methods according to the raw materials used, the compounding ratio, etc., and is not particularly limited, but for example, a wood chip and a crushed product of a wood chip cement board are put into a mixer. And mix, and then add water and mix, then add magnesium chloride and mix,
Finally, cement may be added and mixed to obtain a mixture for front and back layers. The center layer mixture may also be treated similarly.

In the case of a three-layer structure, for example, as shown in FIG. 1, the mixture is uniformly dispersed and sequentially deposited on the upper surface of the plate 1 to form a back layer 4, a center layer 5 and a surface layer 6. Should be laminated, and it is not necessary to apply an adhesive between each layer.

Next, molding, pressing and curing can be arbitrarily selected from the conventional methods for producing a wood chip cement board, whereby a wood chip cement board having a deep uneven pattern on the surface of the surface layer 6 can be obtained (FIG. 2). Needless to say, the pulverized product may be mixed only in the central layer.

[0021]

Therefore, according to the present invention, since the central layer has a higher cement content than the front and back layers and is in a dense state,
When the press working is applied, the central layer is less likely to be compressed than the front and back layers, and the front and back layers are more strongly compressed.

[0022]

EXAMPLES Next, examples according to the present invention will be described. (Example) In the ratio shown in Table 1, commercially available ordinary Portland cement as a cement and a maximum particle size of 5 mm as a piece of wood
Below, a maximum particle size of 2 obtained by crushing a mixture of cedar and cypress with a thickness of 0.4 mm or less and mill ends of a wood chip cement board as a crushed product.
A mixture for front and back layers and a mixture for center layer were obtained by mixing and stirring a pulverized product having a size of not more than mm, magnesium chloride, and water. Since the wood chips and the pulverized products have a non-uniform water content, they were blended after being dried in advance to a water content of 1% or less.

The mixture for the center layer is in the above-mentioned proportion,
Add wood chips and crushed wood chip cement plates to a mixer and mix for 10 seconds, then add water and mix for 35 seconds, then add magnesium chloride and mix for 35 seconds, and finally add cement It was obtained by mixing for 90 seconds. Also,
The mixture for the front and back layers was also obtained by treating in the same manner as the mixture for the central layer, except for the step of mixing the wood chips and the pulverized product.

[0024]

[Table 1]

Next, the front and back layer mixture was evenly spread and deposited on the metal plate so as to be 25% by weight of the total weight of the wood chip cement plate, and then the center layer mixture was deposited on the upper surface thereof. The wood chip cement board is evenly sprayed and laminated so as to be 50% by weight of the total weight, and further, the front and back layer mixture is evenly sprayed and laminated on the upper surface thereof so as to be 25% by weight of the total weight. A laminate having a thickness of 29.1 mm was obtained. Then, this laminated body was compressed with a pressure of about 40 kgf / cm ² , and allowed to cure for 12 hours in that state to give a thickness of 1
A 1.8 mm 3-layer structured wood chip cement board was obtained and used as a sample.

(Comparative Example) The same raw materials as those used in Examples were used, and the mixture obtained by mixing in the same ratio as in Example in the proportions shown in Table 1 was placed on the same plate as in Examples. It was evenly sprayed, accumulated and laminated to obtain a laminate having a thickness of 29.0 mm. And, this laminated body is 55 kgf / cm ²
It is compressed with a pressure of 1 and cured as in the example to a thickness of 11.9.
A wood piece cement board having a single-layer structure of mm was obtained and used as a sample.

The samples of the above Examples and Comparative Examples were subjected to various tests, and the measurement results obtained are shown in Table 2.

[0028]

[Table 2]

As is clear from the measurement results shown in Table 2,
Overall thickness before and after pressing, compressibility, specific gravity, embossing depth,
It was found that the bending strength of the example was about the same as that of the comparative example. In addition, since the same embossed pattern can be formed at a pressure lower than that of the comparative example by about 30% in the example, it was found that the example is easier to form a desired embossed pattern.

In particular, in the examples, since the amount of fine cement added is large in the central layer and it is in a dense state,
The compression ratio of the central layer alone is small. On the other hand, in the front and back layers of the example, since the amount of cement added is relatively small and in a rough state, the compression ratio of the front and back layers alone is large, and the wood becomes rich due to compression, so the desired surface strength is obtained. Has the advantage that

[0031]

As is apparent from the above description, according to the wood chip cement board of the present invention, since the central layer has a large cement content and is in a dense state, it is difficult to compress, while the front and back layers are Since it has a large amount of wood chips and is in a rough state, it is easily compressed. Therefore, by press compression, a wood chip rich and deep embossed pattern is formed on the front and back layers, and a wood chip cement board with a rich three-dimensional effect can be obtained. Further, since the front and back layers are more easily compressed than the center layer and can be compressed at a low pressure, large equipment is not required and the compression can be performed in a short pressing time, so that the productivity is improved. Furthermore, since it can be compressed with a low pressure, the density of the whole wood chip cement plate does not become high as in the conventional example, and not only the workability does not decrease, but also
The front and back layers are rich in wood, and the desired surface strength can be secured. Since the desired wood chip cement board can be obtained simply by changing the mixing ratio of wood chips and cement, there is no need to prepare two kinds of wood chips as in the conventional example, the manufacturing process is not complicated, and the production cost is low. It has the effect of not increasing.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view before pressing and molding a wood chip cement board according to the present invention.

FIG. 2 is a partial cross-sectional view after pressing and molding a wood chip cement board according to the present invention.

FIG. 3 is a partial cross-sectional view before pressing and molding a wood chip cement board according to a conventional example.

FIG. 4 is a partial cross-sectional view after pressing and molding a wood chip cement board according to a conventional example.

[Explanation of symbols]

 1, 3 ... Plate, 4 ... Back layer, 5 ... Center layer, 6 ... Surface layer.

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Claims (2)

[Claims] 1. A wood chip cement board having a three-layer structure formed by compressing and integrating a wood chip and a front and back layer containing cement as an essential component and a center layer, and having a concavo-convex pattern on at least one surface thereof. A wood chip cement board, characterized in that the weight ratio of cement to wood chips in the above is larger than the weight ratio of cement to wood chips in the front and back layers. 2. The weight ratio of cement to wood chips in the front and back layers is 1.5 to 4.0 times the dry weight of wood chips, and the weight ratio of cement to wood chips in the central layer is:
The wood chip cement board according to claim 1, wherein the dry weight of the wood chip is 2.0 to 10.0 times.