JPH06238616A - Heat processing method of woody material - Google Patents

Abstract

PURPOSE:To obtain a woody material suitable for building houses and furnitures by ameliorating dimensional stability and surface property of the woody material in a simple way. CONSTITUTION:A woody maternal 15 arranged between heating boards, a sealing material and a thickness regulating jig are arranged at the woody material and its periphery, and high pressure steam is supplied to the wood material by the heating boards from the surfaces of the heating boards 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 capable of supplying the high pressure steam to be used for compacting timbers and manufacturing composite materials, so that the processing itself is simplified, thereby largely improving productivity.

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.

For this reason, softwood is boiled or steamed to be softened, 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, the force of the softwood that has been consolidated due to the action of one or both of moisture and heat to return to its original state. 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 restoration of the consolidated wood material. According to the method, it was difficult for the high-pressure steam to penetrate into the wood material (particularly the central portion of the wood material), the treatment effect was not uniform, and the treatment conditions of the central portion and the peripheral portion of the wood material 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 for treating a wood material, and the same as in the case where the wood material is not treated in the pressure vessel but only in the pressing device using the heating plate, in the pressure vessel. The present invention was accomplished by recognizing that a wood material having a low expansion coefficient, that is, improved dimensional accuracy and improved surface characteristics can be obtained.

[0009]

That is, according to the present invention, a wooden material is placed between hot plates and a sealing material and a thickness-regulating jig are arranged around the wooden members so that the wood plate can be removed from the hot plate surface with respect to the wooden material. A method for heat treating a wood material characterized by supplying high-pressure steam, and arranging a wood material between hot plates, arranging a sealing material and a thickness control jig around the wood material and by a hot plate. Disclosed is a method for heat treating a wood material, characterized in that high-pressure steam is supplied to the wood material from the surface of the heating plate in a state where the wood material is consolidated.

In the present invention, it is also possible to donate the chemical together with the high-pressure steam, and at that time, the chemical can uniformly treat the whole wood material, and at the same time, the disadvantages of the conventional chemical treatment are also present. Can be resolved. 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 heating plate, a heating plate capable of supplying high-pressure steam, which is usually used for compressing wood and manufacturing composite materials, can be used, but is not limited thereto. A wood material having a predetermined thickness and size is placed between the heating plates, preferably on the lower heating plate. Next, an elastic sealing material having a height slightly higher than the thickness of the wood material as the final product is arranged on four laps of the wood material, and the same thickness as the desired thickness of the wood material as the final product is provided outside the sealing material. Place a height thickness control jig. As the elastic sealing material, any material can be used as long as it has a sealing function of not leaking the high-pressure steam ejected from the surface of the hot plate to the outside and has heat resistance and compressibility, but the silicon elastic packing material is particularly preferable. . Also, as the material of the thickness control jig, any member having the required rigidity and heat resistance can be used, but aluminum material, stainless steel material, etc. are preferable,
Stainless steel is particularly preferable.

After arranging the sealing material and the thickness regulating jig around the wooden material, the hot plates are brought close to each other until they are finally regulated by the regulating jig. In this state, high pressure steam is ejected from the surface of the heating plate toward the wood material for a predetermined amount (for a predetermined time). This ejection may be performed stepwise by changing ejection conditions (time, temperature, pressure, amount, etc.). As a result, the water vapor supplied from the surface of the hot platen comes from the front surface and the back surface of the wood material, and also from four laps of the wood material when a space is provided between the wood material and the sealing material arranged around the wood material. , The necessary treatment proceeds by penetrating to the central part inside.

The optimum treatment conditions are experimentally determined depending on the type and size of the target wood material, but in the case of ordinary softwood, the temperature of the hot platen during the injection of high pressure steam is 150 ° C. It is preferable to maintain at ~ 250 ° C, and the pressure of high-pressure steam is several kgf / cm ^{2 to} 30 kgf / cm ² ,
The temperature is preferably about 150 ° C to 230 ° C. As will be described later, when the high-pressure steam is supplied stepwise in the first step and the second step, the first step is 5 kgf / cm ^{2 to} 7 kgf.
/ cm ^2, preferably so as to be 10kgf / cm ² ~30kgf / cm ² about a second step. The injection time of high-pressure steam is preferably about 1 to 10 minutes.

When the high-pressure steam is supplied, a chemical agent for chemical treatment such as acetylation or formalization, or a plasticizing agent such as ammonia gas or low molecular weight phenol may be simultaneously supplied. The chemical, together with high-pressure steam, uniformly impregnates the entire wood material. The initial thickness of the wood material placed on the hot platen may be approximately the same as the thickness of the desired final product, or may be up to about 300% greater than that. . In the former case, the consolidation process is not performed in particular, and in the latter case, a predetermined consolidation process is performed. Also,
In the latter case, the hot platen is moved and the primary high-pressure steam supply process is performed in a state where the hot platen is in contact with the wood material, and the wood plate is softened again by the thickness control jig. You may make it move until it is regulated and perform a 2nd high pressure steam supply process after that.

That is, 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. 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 process of forming into a wooden material, and the material produced as a wooden material. May be performed as a post-treatment (therefore, the term "wood material" used in the present invention also includes an intermediate material in the molding process).

After the supply of the predetermined high pressure steam 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, the dimensional change rate of the obtained final product was smaller and the surface condition was smoother when the decompression was performed in the cold state than when the decompression was gradually performed.

[0017]

EXAMPLES The present invention will be described below with reference to examples. [Example 1] Water content 20%, thickness 30 mm, width 150 mm,
A plurality of cedar materials having a length of 600 mm were prepared, 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 having a heating plate capable of supplying high-pressure steam from the surface, and the elasticity of the height of 32 mm and the width of 30 mm was set on four circumferences of the cedar material. A silicon material 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 control jig on four circumferences of the sealing member. After setting the heating plate to 180 ° C, move the heating plate to bring it into contact with the cedar wood, and as the first step, 6 kgf / cm ² ,
High-pressure steam having a temperature of 158 ° C. was jetted from the surface of the heating plate for 4 minutes. At the final stage of jetting, the pressing device was operated to bring the hot platen closer until the movement was restricted by the thickness control jig. As a result, the cedar wood was compacted to a compression rate of 60%.

In that state, in the second step, high-pressure steam of 10 kgf / cm ² and a temperature of about 180 ° C. was jetted from the surface of the heating plate for 4 minutes for the first and second groups. Then the first
For the group, the pressure was gradually released over a period of 5 minutes while the supply of high-pressure steam was stopped. For the second group, after the supply of high-pressure steam was stopped, cooling water was supplied to the heating plate, and the pressure was gradually released over 5 minutes. Further, for the third group and the fourth group, the same high-pressure steam was jetted from the surface of the heating plate for 8 minutes.
Thereafter, with respect to the third group, the pressure was gradually released over a period of 5 minutes while the supply of high-pressure steam was stopped. For the fourth group, the supply of high-pressure steam was stopped, and then the pressure was gradually released over a period of 5 minutes while cooling water was supplied to the hot platen.

Each of the final products after depressurization was boiled for 2 hours in a boiling tank and then absolutely dried, and the thickness of each was measured, and the thickness swelling rate and the recovery rate in the radial direction were calculated by the following equations at the end and the center. Was measured at. The results are shown in Tables 1 to 4. 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 at 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.

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 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 a height regulating jig having a height of 15 mm. 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 tank for 2 hours, then the thickness was measured, and the radial thickness swelling ratio and the treatment cycle were measured by the same method. I went. The results are shown in 13 of Table 1.

Example 3 In this example, the formalization treatment was carried out at the same time. First, a plurality of white oak sapwood having the same dimensions as those used in Example 2 were prepared and divided into two groups. Located in the lower hot platen of the pressing device having a hot platen capable of supplying high-pressure steam from the surface of each, the elastic silicone material of 32 mm in height and 30 mm in width is used as a sealing member on the four laps of the white oak sapwood. , 4 of the sealing member
A stainless material having a height of 15 mm and a width of 50 mm was arranged around the circumference as a thickness control jig.

After the heating platen was set at 180 ° C., the heating platen was moved and brought into contact with the white oak sapwood, and 5 g of formaldehyde vapor containing 2% by weight of SO ₂ prepared in advance (1 g in terms of volume) / L) was injected into the space between the heating plates at the same time as high pressure steam of 10 kgf / cm ² and a temperature of 158 ° C. The injection was carried out for 4 minutes for the first group and for 8 minutes for the other groups, and after the injection for all the groups, the pressure was gradually released over 5 minutes with the supply of high-pressure steam stopped.

After the depressurization, each group was subjected to the same treatment as in the other examples, and the radial thickness swelling ratio and the treatment cycle were measured by the same method. The results are shown in Table 1.
14-15.

[0029]

[Table 1]

[Discussion] As is clear from Table 1, the treatment according to the present invention is carried out by injecting high-pressure steam from the surface of the heating plate onto the wood material. Including, the pressure density becomes higher near the surface than inside, and a hard and smooth surface can be obtained. In most cases, both the radial thickness swelling rate and the recovery rate are superior to those obtained by the autoclave treatment, and the dimensional stability is improved. The thickness swelling and recovery in the central part is improved in all cases measured, demonstrating the superiority of the 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 that of the surface.

[0032]

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 by using a pressing device having a heating plate capable of supplying high-pressure steam used for pressing wood and manufacturing composite materials. Therefore, it is not necessary to prepare a large-scale apparatus such as a pressure vessel which is complicated and difficult to operate, and the processing itself is simplified, so that the productivity is significantly improved.

Claims (3)

[Claims] 1. High-pressure steam is supplied to the wood material from the surface of the heat plate in a state in which a wood material and a sealing material and a thickness control jig around the wood material are arranged between the heat plates. Heat treatment method for wood. 2. A wood material is arranged between the heat plates, a wood material and a sealing material and a thickness regulating jig are arranged around the wood material, and the wood material is compacted by the heat plate. A method for heat treatment of wood material, characterized in that high-pressure steam is supplied to the wood material from the surface. 3. The heat treatment method for a wood material according to claim 1, wherein the chemical is supplied together with high-pressure steam.