JP3153122B2 - Compressed wood and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compressed wood material obtained by heating and compressing a wood material and a method for producing the same.

[0002]

2. Description of the Related Art A conventional compressed wood material is manufactured by humidifying and heating a wood material in a wet state or in a steam atmosphere to obtain a high water content and high temperature state, and then heating and compressing the wood material.

[0003] The above prior art is to obtain a compressed wood material by heating and compressing the wood material at a high temperature in the presence of a large amount of water in the wood material, and to soften wood components such as cellulose, hemicellulose and lignin. In particular, for hemicellulose and lignin, which are non-crystalline components, water largely acts as a plasticizer to lower their softening temperatures to about 60 ° C., respectively, and to perform heat compression while increasing the plasticity of wood. is there.

[0004]

However, in the case of the prior art in which a wooden material is heated and compressed in a high water content state,
The high steam pressure of water present inside the wood material acts as a force to restore the compressed state when the pressure is released, and it is difficult to maintain the compressed state in combination with the springback phenomenon due to the pressure release. .

[0005] Particularly, in the case of wood materials having a low specific gravity,
Although compression is easily performed, puncturing (delamination) may occur due to the instantaneous release of the high vapor pressure of water when the compression is released.

In order to prevent the effect of high steam pressure, cooling may be considered while maintaining the compression-compressed state, but it is not practical because productivity is extremely low and cost is greatly increased.

[0007] Further, even if the compressed state can be maintained, the wood material is compressed over the entire wood material in a high water content state, so that the wood material has a high specific gravity. This means that the volume is reduced by maintaining the compressed state,
This means lower product yields and significantly higher costs.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel compressed wood material capable of solving the above-mentioned problems of the prior art and a method for producing the same.

That is, in the compressed wood material according to the present invention, a high specific gravity layer compressed by heating and compression is provided on each of the front and back surfaces and the center in the thickness direction of the wood material whose water content is adjusted to a fiber saturation point or less. It is characterized by becoming.

The method for producing a compressed wood material according to the present invention is characterized in that the wood material whose water content is adjusted to a fiber saturation point or less is heated and compressed at a temperature equal to or higher than the softening point of cellulose which is a crystal component of the wood material. Thereafter, the wood material is decompressed, and after lowering the material temperature of the wood material, it is heated and compressed again at a temperature equal to or higher than the softening point of cellulose, and then decompressed and cooled, whereby the front and back surfaces of the wood material and its thickness direction are reduced. It is characterized in that a high specific gravity layer compressed by heat compression is formed at the center.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Wood materials include sawn or glued wood, laminated veneer, plywood, particle board, and the like.
A processing material such as a fiberboard is used.

As these wood materials, both softwood materials and hardwood materials can be used, and particularly soft materials and low specific gravity materials are suitably used.

Wood materials have a water content below the fiber saturation point,
Preferably, it is adjusted to 35% or less. For this reason, when a sawn timber is used as a wooden material, it is obtained by drying the timber before sawing and then turning it into a sawn timber or by drying the sawn timber without drying. When a processed material is used, the water content is adjusted to a fiber saturation point or lower during the manufacturing process.

[0014] Next, a wood material having a water content adjusted to a fiber saturation point or lower is set between hot plates of a hot press apparatus to which a thickness regulating jig (generally called a distance bar) for regulating a distance between upper and lower hot plates is attached. Insert the material.

The thickness regulating jig used at this time is thicker than the thickness of the compressed wood material to be finally obtained.

The hot pressing of a wooden material in a hot press is performed at a temperature equal to or higher than the softening point of cellulose, which is a crystalline component of the wooden material.

The softening point temperature of cellulose, which is a crystalline component in wood material, varies slightly depending on the tree species, but is generally about 20%.
The temperature is 0 to 250 ° C., and is substantially constant irrespective of the water content of the wood material. Therefore, in the present invention, the heat pressure temperature is set to 2
It is necessary to perform pressure clamping at a temperature of at least 00 ° C.

The softening points of hemicellulose and lignin, which are non-crystalline components of wood, vary greatly depending on the water content of the wood, and the softening points of hemicellulose and lignin in a completely dry state are about 180 ° C. and about 15 ° C., respectively.
Although the temperature is 0 ° C, the softening point temperature decreases to around 60 ° C at a water content of 35%, which is the fiber saturation point of the wood material. Therefore, in the present invention using a wood material whose water content is adjusted to a fiber saturation point or lower, by hot-pressing at a temperature equal to or higher than the softening point of cellulose, cellulose as a crystalline component is thermally softened, and at the same time, an amorphous component is used. Some hemicellulose and lignin also soften and melt.

The pressing time and pressing pressure are arbitrarily set according to the type of wood used, the type of wood, the specific gravity of the wood itself, the softness, and the like. The pressure is preferably 5 to 25 kg / cm ² .

In the wood material heated and compressed between the upper and lower hot plates of the hot press device, the heat of the hot plate is transmitted to the front and back portions, and the front and back portions undergo thermal softening and compression by the compressive force. Due to the adjusted water content below the point, the heat transfer is transferred into the interior at a relatively slow rate, so that only the front and back parts of the wood are compressed early.

After the wood material whose front and back parts are compressed as described above is decompressed.

Next, after lowering the material temperature of the wood material, the wood material is heated and compressed again at a temperature equal to or higher than the softening point of cellulose which is a crystalline component of the wood material.

The lowering of the temperature of the wooden material is carried out by cooling or allowing the wooden material to stand naturally and lowering the temperature of the wooden material to 100 ° C. or lower, preferably 80 ° C. or lower. 10
By lowering the temperature of the wooden material to 0 ° C. or less, the crystalline component cellulose, the non-crystalline component hemicellulose, and the lignin softened or softened and melted by the previous heating and compression are fixed inside the wooden material and compressed. The front and back of the wood material is fixed.

The wood material whose temperature has been lowered is inserted between the hot plates of a hot press apparatus provided with a thickness regulating jig for controlling the distance between the upper and lower hot plates, and the temperature is higher than the softening point of cellulose. Is heated and compressed.

At this time, a jig having a thickness substantially equal to the thickness of the compressed wood material to be finally obtained is used as the thickness regulating jig. In addition, the thickness regulating jig has a thickness of 60 times the thickness of the first wooden material.
Those having a thickness of about 95%, more preferably 65-92% are suitably used. In other words, the thickness regulating jig is attached so that the compression ratio for the first wooden material is 5 to 40%, more preferably 8 to 35%.

If the compression ratio of the wood material is less than 5%, the compression on both the front and back surfaces becomes insufficient, and the strength required as a high specific gravity layer cannot be obtained. Conversely, the compression ratio is 40%
When the compression ratio exceeds, the compression of both front and back surfaces is performed sufficiently to obtain the necessary strength as a high specific gravity layer, but the overall specific gravity increases, causing weight increase, and reducing the volume by giving an excessive compression ratio That is, it is not preferable because the loss of the raw material increases, the yield decreases, and the cost increases.

The compression ratio of the wood material is within the above range,
It can be arbitrarily selected according to the type of wood, specific gravity, hardness of the front and back surfaces to be obtained, and the like, and a thickness regulating jig is set according to the selected compression ratio.

The pressing time and the pressing pressure are arbitrarily set according to the type of wood used, the type of wood, the specific gravity of the timber itself, the softness and the like. The pressure is preferably 5 to 25 kg / cm ² .

Since the wood material is previously hot-pressed once with a hot press, the front and back portions are compressed, and the heat causes the water content to evaporate in the front and back portions and near the front and back inner layers. It is almost dry. Since the wood material in such a state is heated and compressed again at a temperature (200 ° C. or more) higher than the softening point of cellulose, the front and back are already compressed by the previous hot-pressing and almost in a completely dry state. The compression does not proceed further in the part and the vicinity of the inner layer, and the crystalline component cellulose and the non-crystalline components hemicellulose and lignin are heated at the center in the thickness direction of the wood material which is maintained at a relatively high water content. The material is softened or melted, and the compression proceeds by the compression force generated by pressing.

After the wood material is compressed at the center in the thickness direction as described above, the wood material is decompressed and cooled.

The hardness of the high specific gravity layer on the front and back surfaces of the wooden material is based on JIS
1.5 in the wood hardness test method according to Z-2007
It is preferably at least kgf / mm ² , and the hardness of the high specific gravity layer formed at the center in the thickness direction is preferably at least 1.2 kgf / mm ² in the same test method.
As a result, the impact resistance of the surface becomes sufficient and it is hard to be damaged, while improving the bending strength of the material itself,
Improves dimensional stability as a wood material by reducing hydrophobicity, swelling rate, and water absorption rate. In addition, the numerical value of the hardness by the said test method is measured in the state which each high specific gravity layer was exposed to the outer surface by grinding etc.

As described above, the high specific gravity layer 2, which has been compressed by heating and compression, is placed on the front and back surfaces and the center in the thickness direction of the wood material whose moisture content has been adjusted to the fiber saturation point or lower.
2 and 2 are provided, whereby the compressed wood 1 of the present invention is obtained (FIG. 1).

Such a wooden board may be provided with a direct makeup such as a base treatment, a coloring coating, a pattern printing, a top coating, or a decorative material such as a veneer, a decorative paper, a decorative synthetic resin film, etc., as necessary. Is preferably used as a base material of a decorative board on which overlay makeup is applied, and the decorative board is effectively used as a building material, a fitting, or a furniture material.

[0034]

According to the present invention, a high specific gravity layer is formed on each of the front and back surfaces of the wooden material and the center in the thickness direction without increasing the overall specific gravity, so that the bending strength and the surface smoothness are reduced while being lightweight. Since the properties and surface hardness are improved and the balance between the front and back is maintained, a compressed wood material that does not generate warpage or twist can be obtained.

The high specific gravity layer formed on each of the front and back surfaces and the center in the thickness direction is compressed after cellulose as a crystalline component of wood material is softened, and hemicellulose and lignin as non-crystalline components are softened and melted. Since it is formed by curing to a high specific gravity, it becomes a hydrophobic film, and in combination with the reduction of hydrophilicity by compression, the swelling rate and water absorption rate can be reduced, greatly improving the dimensional stability of wood materials To improve.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a compressed wood material according to the present invention.

[Explanation of symbols]

 1 Compressed wood 2 High specific gravity layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-225905 (JP, A) JP-A-9-225906 (JP, A) JP-A-61-31205 (JP, A) JP-A-6-31905 238615 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B27K 5/00 B27K 5/06

Claims (2)

(57) [Claims] 1. A compression method characterized in that a high specific gravity layer compressed by heat compression is provided on each of the front and back surfaces of a wood material whose water content is adjusted to a fiber saturation point or less and its center in the thickness direction. Wood material. 2. A wood material having a water content adjusted to a fiber saturation point or less is heated and compressed at a temperature equal to or higher than a softening point of cellulose which is a crystalline component of the wood material, and then decompressed to reduce the wood temperature of the wood material. After the temperature is lowered, the material is heated and compressed again at a temperature equal to or higher than the softening point of the cellulose, and then decompressed and cooled. A method for producing a compressed wood material, comprising forming a specific gravity layer.