JPH06238615A - Heat treating method of woody material - Google Patents

Abstract

PURPOSE:To obtain a woody material suitable for building houses or furnitures by ameliorating dimensional stability or surface property of the woody material in a simple way. CONSTITUTION:A woody material 18 arranged between heating boards, a sealing material and a thickness regulating jig are arranged at the wood material and its periphery, and the woody material is heated by the heating boards and/or high-frequency heating as occasion demands in a state that the woody material is compacted. This processing can be carried out by using a compacting device having the heating boards to be used for compacting timbers and manufacturing composite materials, so that the processing itself is simplified and productivity will be largely improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method for wood materials, and more particularly, to obtain wood materials suitable for use in construction or furniture by improving the dimensional stability or surface characteristics of the wood materials. The present invention relates to a heat treatment method for wood materials that can be used.

[0002]

2. Description of the Related Art In recent years, high-quality hardwood materials have decreased and it is no longer possible to obtain a sufficient supply. Therefore, softwood materials, medium-quality fiberboard (MDF), particle board and the like have been attracting attention as alternative materials for hardwood materials. However, softwoods are generally softer than hardwoods, and surface properties such as surface hardness and abrasion resistance of surfaces are required for use as architectural or furniture materials.
There was a problem in durability against moisture and heat and strength.
Swelling of MDF and particle board in the thickness direction with respect to water has been a serious problem.

Therefore, a softwood is boiled or steamed to soften it, and then hot pressed with a flat plate press to consolidate the softwood to a thickness of about 20 to 70% of the initial thickness. Is publicly known. When the softwood is consolidated, the above-mentioned surface properties, durability and strength can be remarkably achieved. However, there is a drawback that the softwood material, which has been compacted and improved in performance, is restored to its original state.

Restoration of the above-mentioned consolidated softwood material, MDF,
In order to prevent the swelling of the particle board in the thickness direction, it has been attempted to subject these wood materials to chemical treatment such as acetylation and formalization, but this method is environmentally preferable because a large amount of chemicals are used. However, there are drawbacks such as not being possible, it is difficult to uniformly treat the entire wood material, and the treatment process is complicated and the cost is high. In addition, if it is a consolidated softwood material, phenol resin,
It has also been attempted to impregnate a polyester resin or the like with WPC (wood / plastic composite material) treatment,
This method also has the drawback that it is difficult to uniformly treat the entire wood material as in the above-mentioned chemical treatment, and the treatment process is complicated and the cost is high. There was also a drawback of losing the characteristics.

Another method is to put the consolidated wood material in an autoclave and treat it with high-pressure steam at 160 to 220 ° C. for several minutes to prevent the consolidated wood material from being restored. It was difficult for the high-pressure steam to penetrate inside the wood (particularly the center of the wood), the treatment effect was not uniform, and the treatment conditions of the center and the periphery of the wood were often different.

[0006] The applicant of the present invention has conducted diligent research to solve the inconveniences of the conventional methods for treating wood materials, and can prevent the consolidated wood materials from being restored to the original thickness by moisture or heat. A new treatment method for wood materials, which enables the wood materials to be uniformly and efficiently processed over the whole wood material, has been devised and already applied (Japanese Patent Application No. 4-26922).
No. 5).

This treatment method is a method of treating a wood material by heating the compression-molded wood material in a closed pressure vessel by high frequency heating while restraining deformation to vaporize water in the wood material under high pressure. Thus, it has become possible to obtain a consolidated wood material suitable for construction or furniture, which has improved surface characteristics such as surface hardness and abrasion resistance of the surface and has a reduced expansion coefficient against moisture and heat.

[0008]

Although the above-mentioned treatment method is practically effective, it requires a step of treating the wood material in the pressure vessel, and therefore the process is complicated and the apparatus itself is large. It had to be a large scale.
The present inventor continues further research on a method of treating wood materials, to the same extent as in the case where the wood materials are not treated in the pressure vessel but only in the pressure vessel using the hot platen. Therefore, the inventors have perceived that a wood material having a low expansion coefficient, that is, improved dimensional accuracy and improved surface characteristics can be obtained, and the present invention has been accomplished.

[0009]

That is, according to the present invention, a wooden material and a sealing material and a thickness regulating jig are arranged around the wooden material between the heating plates, and the wooden material is sandwiched between the heating plates. Disclosed is a method for heat-treating a wood material, which comprises heating the wood material with. The present invention also arranges a wood material and a sealing material and a thickness control jig around the wood material between the heating plates, and heats the wood material while sandwiching and consolidating the wood material between the heating plates. Also disclosed is a method for heat treating a wood material, which is characterized by

The wood material can be heated by a heating plate, high frequency heating, or both. Next, the present invention will be described in more detail. In the present invention, the wood material includes not only solid wood but also processed materials such as MDF and particle board, and the same purpose can be achieved. Further, although the effect is particularly exerted by applying the present invention to a softwood material which is generally considered to be soft as a solid material, it can also be applied to a hardwood material.

As the hot platen, a normal hot platen used for compression of wood and production of composite materials can be optionally used, but the hot platen is not limited to this. Further, high-frequency heating including microwave heating (hereinafter referred to as high-frequency heating) may be used as the heating means, and a known microwave generator or high-frequency generator may be provided in the vicinity of the wood material to be treated in that case. Be prepared.

At the time of processing, a wood material having a predetermined thickness and size is placed between the heating plates. Next, on 4 laps of wood,
An elastic sealing material having a height somewhat higher than the thickness of the wood material as the final product is arranged, and a thickness regulating jig having the same height as the thickness of the wood material as the desired final product is arranged outside the sealing material. Deploy. As the elastic sealing material, any material can be used as long as it has a sealing function that does not let water vapor generated from the inside of the wood material leak to the outside by heating the wood material and has heat resistance and compressibility, but the silicone elastic packing material is Particularly preferred. Further, as the material of the thickness regulating jig, any member having required rigidity and heat resistance can be used, but aluminum material, stainless material, etc. are preferable, and stainless material is particularly preferable.

In one embodiment of the present invention, after the sealing material and the thickness regulating jig are arranged around the wooden material, the heating plates are brought close to each other until they come into contact with the surface of the wooden material, and the first heating plate is used at that position. The following heating is performed. It is desirable that the heating is performed at a temperature at which water inside the wood material can be evaporated. This heating softens the wood material to some extent. In this state, the heating platen is brought closer until it is regulated by the thickness regulating jig. As a result, the wood material is compacted and the four circumferences of the wood material are kept sealed by the surrounding sealing material.

In that state, the secondary heating by the heating plate is further continued. It is necessary that the heating temperature at this time is equal to or higher than the temperature at which the water contained in the wood material evaporates. You may change the heating temperature stepwise,
For example, discoloration due to heat on the surface of the wood material can be prevented as much as possible by initially setting the temperature to about 200 ° C. and gradually lowering the temperature with time, or by heating at a lower temperature after a predetermined time has elapsed.

In another aspect of the present invention, high frequency heating is used instead of heating with a heating plate. In this case, a more uniform heat treatment is performed because water is uniformly vaporized from the inside of the wood material. In still another aspect of the present invention, heating with a heating plate and high frequency heating are performed simultaneously. In this case, the processing cycle can be further shortened.

In still another embodiment of the present invention, the wood material placed on the hot platen has an initial thickness of about the same as the desired final product thickness. In that case, the wood material is not subjected to the consolidation treatment in particular, and the hot platen is approached from the beginning until it is regulated by the thickness regulating jig. In that state, heating with a heating plate and / or high frequency is performed. When it is necessary to densify and improve the surface condition like softwood, it is preferable to prepare a material thicker than the final product. In the case of a material such as a particle board that does not need to be consolidated, it is possible to prepare a material having almost the same thickness as the final product and perform the treatment without consolidation.

Further, in the case of a material produced by reworking an intermediate material such as MDF or particle board as the material, the treatment according to the present invention may be carried out in the step of forming into a wooden material, and produced as a wooden material. The processed product may be subjected to post-treatment (therefore, in the present invention, the term "wood material" is used to include an intermediate material in the molding process).

After the predetermined heating is completed, the pressure is released. The decompression may be performed gradually over a certain period of time, or may be performed in a so-called cold state by supplying cooling water to the hot platen. According to the experiment, when the decompression is performed in the cold state, the dimensional change rate of the final product obtained is smaller than that in the case of other decompression, and the surface state is finished beautifully.

[0019]

EXAMPLES The present invention will be described below with reference to examples. [Example 1] A wooden material was compacted and sealed between hot plates and heated by the hot plates. A plurality of cedar materials having a moisture content of 20%, a thickness of 30 mm, a width of 150 mm and a length of 600 mm were prepared as wood materials, and the present invention was carried out by dividing them into four groups.

For all groups, each cedar material was placed on the lower heating plate of a pressing device with a heating plate, and the height of the cedar materials was 32 at four laps.
An elastic silicon material having a width of 30 mm and a width of 30 mm was used as a sealing member, and a stainless material having a height of 12 mm and a width of 50 mm was arranged as a thickness regulating jig on four circumferences of the sealing member. After setting the heating plate to 200 ° C, move the heating plate to make contact with the cedar wood and perform the first heating for 5 minutes, then operate the pressing device to restrict the movement of the heating plate by the thickness control jig. The wood material was gradually consolidated by moving the wood material until it reached the temperature. As a result, the cedar wood was compacted to a compression rate of about 60%.

In that state, as the second heating, the first group and the second group were heated at 200 ° C. for 10 minutes by the hot platen, and then the first group was gradually decompressed over 5 minutes, For group 2, the pressure was gradually released over a period of 5 minutes while supplying cooling water to the hot platen. Further, the third group and the fourth group
Similarly, the group was heated at 200 ° C. for 20 minutes on the hot plate, and then gradually decompressed for the third group over 5 minutes, and for the fourth group, the hot water was supplied to the hot plate for 5 minutes. Over time, the pressure was gradually released.

Each of the final products after depressurization was boiled in a boiling furnace for 2 hours and then absolutely dried, and the thickness of each was measured, and the radial thickness swelling rate and recovery rate were calculated by the following equations. Was measured at. The results are shown in Table 1
Shown in. Thickness swelling rate = (thickness after boiling for 2 hours-absolute dry thickness before boiling)
/ (Absolute dry thickness before boiling) x 100% recovery rate = (thickness after absolute boiling after boiling for 2 hours-thickness after consolidation) /
(Thickness before consolidation-thickness after consolidation) x 100% Furthermore, for each cedar wood, the time required from the start to the end of the treatment was measured for each group. The results are also shown in Tables 1 to 4. The surface condition was very hard, and the finish was smooth and beautiful.

Comparative Example 1 A cedar material having the same dimensions as used in Example 1 was immersed in hot water of 95 ° C. for 20 minutes to be softened by heating as a first step (boiling treatment), and then 105 ° C. Using the hot pressing machine set to, the compaction rate was 60%. Next, the cedar wood was divided into two groups, and in the second step, steam treatment under high temperature and high pressure was performed using an autoclave while restraining the deformation with a stainless steel jig, 4 minutes for the first group, and 2 minutes for the second group. For 8 minutes. The steam used is 10 kgf /
In cm ² , the temperature inside the autoclave was 180 ° C. For each group, the pressure inside the autoclave was gradually released to obtain a treated wood material.

For each of them, the thickness swelling rate and the recovery rate in the radial direction were measured at the end portion and the central portion in the same manner as in Example 1. The results are shown in Tables 5 and 6. Similarly,
For each cedar wood, the time required from the start to the end of the treatment was measured for each group. The results are also shown in Tables 5 and 6.
Although the surface condition was hard, it was not as good as that of Example 1, and a clear difference was visually observed.

Example 2 Water content 10%, thickness 15 mm,
A plurality of white oak sapwood with a width of 150 mm and a length of 600 mm were prepared and divided into four groups. Each group was subjected to the same treatment as in Example 1 and the same method except that a stainless material having a height of 15 mm and a width of 50 mm was placed as a thickness control jig and the first step including consolidation was not performed. Radial thickness swell and treatment cycle measurements were taken. The results are shown in Tables 7 to 10. As in the case of Example 1, the surface condition was very hard and smooth, and the finish was beautiful.

[Comparative Example 2] White oak sapwood having the same size as that used in Example 2 was divided into two groups, which were not subjected to boiling treatment and consolidation treatment, and had a height of 15 mm as a thickness regulating jig. The same treatment as in Comparative Example 1 was performed except that a stainless steel material having a width of 50 mm was arranged, and the radial thickness swelling ratio and the treatment cycle were measured by the same method. The results are shown in 11 to 12 of Table 1. Although the surface condition was hard, it was not as great as that of Example 2, and a clear difference was visually observed.

Comparative Example 3 The white oak sapwood used in Example 2 was boiled as it was in a boiling furnace for 2 hours, and then its thickness was measured to measure the radial thickness swelling ratio. The results are shown in 13 of Table 1.

[0028]

[Table 1]

[Discussion of Table 1] As is clear from Table 1, the wood materials treated in accordance with the present invention are superior in most cases in both radial thickness swelling rate and recovery rate to those obtained by autoclaving. It can be seen that there is an improvement in dimensional stability. The thickness swelling rate and recovery rate in the central part are improved in all cases measured, demonstrating the superiority of the present invention. In particular, the so-called hot cold treatment has a great effect. It can also be seen that the processing time is shortened and the productivity is improved. Furthermore, it can be seen that the surface condition is very beautiful compared to the others.

[Embodiment 3] A wooden material was compacted and sealed between hot plates, and heating was performed by both a hot plate and high frequency heating using a pressing device capable of high frequency heating. Water content of wood is 20
%, A thickness of 30 mm, a width of 150 mm, and a length of 600 mm were prepared. Each cedar material is placed on the lower heating plate of a pressing device having a heating plate, and an elastic silicon material having a height of 32 mm and a width of 30 mm is used as a sealing member on the four circumferences of the cedar material, and further placed on the four circumferences of the sealing member. A stainless material having a length of 12 mm and a width of 50 mm was arranged as a thickness control jig.

While maintaining the heating plate at 180 ° C., the heating plates are moved until they come into contact with the wood material, and in that state, the heating plate and 13.
It was heated for 2 minutes at a high frequency of 56MHz and an output of 200V / 8Kw. Then, it was gradually tightened to be consolidated at a compression rate of 60%. Then, using the same high frequency with the hot plate,
The consolidated wood material was permanently fixed by heating for 4, 6 and 8 minutes. During heating, the pressure of the steam generated from the inside of the wood material and sealed between the heating plates was adjusted by the pressure control valve so that the pressure was 10 kgf / cm ² . After heating for a predetermined time, the sealed water vapor was gradually discharged to release the pressure.

In the same manner as in Example 1, the radial thickness swelling ratio and the recovery ratio were measured at the end and the center. The results are shown in Tables 1 to 3. Similarly,
For each cedar wood, the time required from the start to the end of the treatment was measured for each group. The results are also shown in Tables 1 to 3.
The surface condition was very hard, and the finish was smooth and beautiful.

Example 4 The same cedar material as in Example 3 was used and the same treatment was carried out. However, for decompression, cooling water was passed through the hot plate at a stretch to bring the cold plate into the cold state in order to rapidly lower the temperature of the treated material. For each of them, the thickness swelling ratio and the recovery ratio in the radial direction were measured at the end portion and the central portion in the same manner as in Example 1. The results are shown in 4 of Table 2
6 shows. Similarly, for each cedar wood, the time required from the start to the end of the treatment was measured for each group. The results are also in Table 2
4-6. The surface condition was very hard, and the finish was smoother and more beautiful than in the case of Example 3.

[Comparative Example 4] The same wood used in Example 3 was used, inserted between hot presses capable of high frequency heating provided in a closed pressure vessel, and heated for 2 minutes at a high frequency of 27 MHz and an output of 200 V / 8 kW. I went. Then, it was gradually tightened to be consolidated at a compression rate of 60%. Subsequently, the same high frequency was used to further heat for 4, 6 and 8 minutes to permanently fix the consolidated wood material. The pressure in the container was adjusted by a pressure control valve so as to maintain 10 kgf / cm ² . After heating for a predetermined time, steam in the container was gradually exhausted to decompress the hot press.

In the same manner as in Example 1, the radial thickness swelling rate and the recovery rate were measured at the end and the center. The results are shown in 7 to 9 of Table 2. Similarly,
The time required from the start to the end of the treatment was measured for each group. The results are also shown in Tables 7 to 9. Although the surface condition was hard, it was not as good as that of Example 3, and a clear difference was visually observed.

[Example 5] Water content 10%, thickness 15 mm,
A plurality of white oak sapwood with a width of 150 mm and a length of 600 mm were prepared and divided into three groups. Do not perform the first step including consolidation and height as a thickness control jig is 15 mm,
Each group was subjected to the same treatment as in Example 3 except that a stainless steel material having a width of 50 mm was arranged, and the radial thickness swelling ratio was measured by the same method. The results are shown in Table 2
2 shows. Similarly, the time required from the start to the end of the treatment was measured for each group. The results are also shown in Tables 10 to 12. The surface condition was very hard, and the finish was smooth and beautiful.

[Comparative Example 5] White oak sapwood having the same size as that used in Example 5 was divided into three groups, which were deformed by a jig made of stainless steel without performing boiling treatment and consolidation treatment. While restrained, steam treatment under high temperature and high pressure was performed for 4 to 6 minutes using an autoclave. The steam used was 10 kgf / cm ² , and the temperature inside the autoclave was 180.
Maintained at 0 ° C. For each group, the pressure inside the autoclave was gradually released to obtain a treated wood material.

For each of them, the thickness swelling ratio in the radial direction was measured in the same manner as in Example 5. The results are shown in Table 2 from 13 onwards.
Shown in 15. Similarly, the time required from the start to the end of the treatment was measured for each group. The results are also shown in Tables 13 to 15. Although the surface condition was hard, it was not as great as that of Example 5, and a clear difference was visually observed.

[Comparative Example 6] The same white oak material as used in Example 5 was boiled as it was in a boiling furnace for 2 hours, and then the thickness was measured to measure the radial thickness swelling ratio. The results are shown in 16 of Table 2.

[0040]

[Table 2]

[Discussion of Table 2] As is clear from Table 2, the wood materials treated according to the present invention are superior in most cases to the radial thickness swelling rate and the recovery rate as compared with those subjected to the autoclave treatment. It can be seen that there is an improvement in dimensional stability. The thickness swelling rate and recovery rate in the central part are improved in all cases measured, demonstrating the superiority of the present invention. In particular, the so-called hot cold treatment has a great effect.

It can also be seen that the processing time is shortened and the productivity is improved. Furthermore, it can be seen that the surface condition is very beautiful compared to the others.

[0043]

According to the treatment method of the present invention, it is possible to obtain a wood material which has a small dimensional change after treatment and has improved surface characteristics. Moreover, the method of the present invention can be carried out using a clamping device used for clamping wood and producing composites. Therefore, it is not necessary to prepare a large-scale and difficult-to-operate device such as a pressure vessel, and the process itself is simplified, so that the productivity is significantly improved.

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[Procedure amendment]

[Submission date] January 13, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

[Comparative Example 4] The same wood used in Example 3 was used and inserted between hot presses capable of high frequency heating provided in a closed pressure vessel, and 13.56 MHz, output 200 V.
Heating was performed for 2 minutes with a high frequency of 8 kW. Then, it was gradually tightened to be consolidated at a compression rate of 60%. Subsequently, the same high frequency was used to further heat for 4, 6 and 8 minutes to permanently fix the consolidated wood material. The pressure in the container was adjusted by a pressure control valve so as to maintain 10 kgf / cm ² . After heating for a predetermined time, the steam in the container was gradually exhausted to decompress the hot press.

Claims (5)

[Claims] 1. A wood material and a sealing material and a thickness regulating jig around the wood material are arranged between the heating plates, and the wood material is heated while the wood material is sandwiched between the heating plates. Heat treatment method for wood. 2. A wood material and a sealing material and a thickness control jig are disposed around the wood board between the heating boards, and the wood material is heated while sandwiching and consolidating the wood material between the hot boards. A heat treatment method for wood materials, which is characterized in that 3. The heat treatment method for a wood material according to claim 1, wherein the wood material is heated by a hot platen. 4. The heat treatment method for a wood material according to claim 1, wherein the wood material is heated by high-frequency heating. 5. The heat treatment method for a wood material according to claim 1, wherein the wood material is heated by both a heating plate and high frequency heating.