JP3136048B2 - How to stabilize wood - 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 stabilizing a wood material, and more particularly to a method for stabilizing a wood material by reducing the rate at which the wood material expands and contracts by absorbing and releasing water.

[0002]

2. Description of the Related Art Wood materials such as a natural veneer, a medium fiber board (MDF), and a particle board repeatedly expand and contract due to water absorption and release, and have poor dimensional stability. Conventionally, various proposals have been made to improve the dimensional stability of wood materials. For example, wood material is boiled or steamed to soften it, then hot-pressed with a hot-plate press to compress it to a thickness of about 20 to 70% of its initial thickness, and cooling water is applied to the hot plate of the hot-plate press. 2. Description of the Related Art A technique is known in which a product is taken out after circulating to reduce the vapor pressure existing inside the wood material. This method improves the surface properties, durability and strength of the wood. However, cooling is performed by circulating cooling water through a hot plate, and energy loss due to repetition of a heating step and a cooling step is large,
A hot plate press with a complicated structure was required.

[0003] As another method, the wood material which has been treated and compacted between the hot plates of the hot plate press as described above is again put into an autoclave, and treated with high-pressure steam at 160 to 220 ° C for several minutes, whereby A method for improving the dimensional stability of compacted wood is known, but this method has difficulty in penetrating high-pressure steam into the wood (especially the center of the wood),
The processing effect was not uniform, and the processing state of the central part and the peripheral part of the wooden material often differed.

As still another method, a wooden material is inserted between hot platen presses provided in a closed pressure vessel, and compressed while heating while restraining deformation to convert the water inside the wooden material into high-pressure steam. There is known a method for treating wood materials by using such methods. Although this method is intended to improve the dimensional stability of the compacted wood material and is practically effective, it requires a process of treating the wood material in a pressure vessel, so that the process is complicated. In addition, the apparatus itself must be large-scale.

[0005] An object of the present invention is to eliminate the above-mentioned disadvantages of the conventional method for stabilizing the size of a wooden material, and more specifically, to use the conventional method for treating a wooden material. It is an object of the present invention to provide a method for stabilizing a wood material which can use a normal hot platen press as it is and can perform a dimensional stabilization process on the wood material with reduced energy loss.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve the object, a method for stabilizing a wooden material according to the present invention comprises a method for stabilizing a wooden material in a closed space formed between hot plates of a hot plate press. Placed and heated to stabilize the wood by converting the water inside the wood into high-pressure steam, and at a rate at which tissue destruction does not occur due to the rapid release of the high-pressure steam accumulated inside the wood after the heat treatment. It is characterized in that the pressure in the closed space is gradually released.

In the present invention, the wood material may be not only a natural veneer but also a processed material such as MDF or particle board. Further, the wood material arranged in the closed space may be a wood material not subjected to the heat softening treatment, and may be a wood material after heat softening by a conventionally known method, for example, a boiling or steaming treatment method. Is also good. Means for heating the wood material in the enclosed space is optional, but may be performed only with a hot plate provided in a normal hot plate press used for compression of wood and production of a composite material. High-frequency heating including microwave heating (hereinafter, referred to as high-frequency heating) may be used alone or additionally. In this case, a known microwave generator or high-frequency generator is provided near the wood material to be processed.

Means for arranging the wood material in the closed space between the hot plates of the hot plate press is arbitrary, but as an embodiment, a predetermined material is provided inside a rigid container which has pressure resistance and heat resistance and can be freely opened and closed. After accommodating the wood material to be treated measured to the thickness and the size of the rigid container, the rigid container may be placed between the hot plates, and the inside of the rigid container may be sealed by being sandwiched by the hot plates. As an embodiment, a wood material measured to a predetermined thickness and size is placed in a space defined by an elastic sealing material having a height slightly higher than the thickness of the wood material as a final product, and the elastic sealing material is heated. The internal space may be sealed by sandwiching and compressing between the boards. In the latter embodiment, a thickness regulating jig is preferably arranged outside the elastic sealing material at the same height as the thickness of the wood material as the desired end product.

The case where the method of stabilizing a wooden material according to the present invention by forming a closed space using a rigid container will be described in more detail with reference to FIGS. The rigid container 1 used preferably comprises a container body 10 having a space S for accommodating a wooden material 40 therein and a flat lid 20. Further, a steam vent hole 15 to the outside is provided in a side wall portion of the container body 10, and an appropriate pipe 1 is provided in the steam vent hole 15.
6 and a flow control valve 17 is attached to the pipe 16. The material of the rigid container 1 is preferably stainless steel, but is not limited thereto. Any material having resistance to temperature and pressure during the stabilization process can be used. For example, a heat-resistant resin material such as an iron material, an aluminum material, an epoxy-based, a silicon-based, and a polycarbonate-based material can be used. A sealing material 30 such as a heat-resistant silicon material is preferably attached to a portion where the container body 10 is surface-connected to the lid 20. Although not particularly shown, another sealing material such as an elastic silicon material may be separately arranged around the housed wooden material 40, and in this case, the sealing material 30 is not necessarily required.

The depth H of the space S formed inside the container body 1 is shallower (lower) (ie, H <h) than the thickness h of the wooden material 40 to be treated before treatment. And When H <h, the dimensional stabilization process proceeds together with the compaction of the wooden material, and when H = h, only the dimensional stabilization proceeds. At the time of treatment, wood material 4 to be treated
0 is housed in the internal space S of the container body 10, covered, and placed between hot plates of a hot plate press. The wood material 40 may not be heat-softened, or may be heat-softened by boiling or steaming. The hot plates 50 and 50 are brought closer to each other until they come into contact with the rigid container 1, and further close until the lid 20 comes into contact with the container main body 10.
As a result, the wood material 40 is compressed in the rigid container 1 and placed in a sealed state (as described above, no compression is performed when H = h). In this state, heating by a hot platen (and high-frequency heating if necessary) is performed. The heating temperature at this time needs to be higher than the temperature at which the water contained in the wood material evaporates. By heating, the water inside the wood material is turned into steam and filled in the closed space and the wood material as high-pressure steam (the heating temperature may be changed stepwise). Thereby, the heat treatment of the wood material proceeds.

When the predetermined heat treatment has progressed, the heating is terminated and the pressure is released. Decompression is performed by adjusting the opening of the flow control valve 17 and gradually discharging high-pressure steam in the closed space to the outside. Thereby, the pressure in the closed space gradually decreases. According to the experiments of the present inventors, when depressurization is rapidly performed at the end of the heat treatment, high-pressure water vapor accumulated inside the wood material is released to the outside at once, so that the wood material is It was confirmed that the tissue was destroyed, thereby cracking the wood surface and inside. By gradually releasing the high-pressure steam in the closed space, the occurrence of such cracks is reliably avoided.

Although the time required for decompression varies depending on the type of wood material and the heat treatment conditions, it is preferable that the time is about 1 to 5 minutes. When the pressure in the closed space becomes substantially zero, the hot plate of the hot plate press is separated and the treated wood material is taken out from the rigid container, whereby the method for stabilizing the wood material according to the present invention is completed. Next, a case where a closed space is formed using an elastic sealing material and the method for stabilizing a wooden material according to the present invention is performed will be described with reference to FIG.

At the time of heat treatment, a wooden material 40 measured to a predetermined thickness and size is placed between hot plates. As in the case described above, this wood material may not be subjected to the heat softening treatment, or may be the wood material after heat softening by the boiling or steaming treatment method. Next, an elastic sealing material 60 having a height slightly higher than the thickness of the wood material as the final product is disposed on the four circumferences of the wood material 40, and the desired wood product as the final product is disposed outside the sealing material 60. A thickness regulating jig 70 having the same height as the thickness is arranged. As the elastic sealing material 60, any material that has a sealing function of preventing water vapor generated from the inside of the wood material by heating the wood material 40 from leaking outside and has heat resistance and compressibility can be used. Materials are particularly preferred. Also, the thickness regulating jig 7
Although any material having a required rigidity and heat resistance can be used for the material of 0, an aluminum material, a stainless material, or the like is preferable, and a stainless material is particularly preferable.

In this state, the hot plates are brought closer to each other until they are regulated by the thickness regulating jig. As a result, the wood material is compacted (similar to the above case, the wood material 40 is not compressed when the thickness of the wood material 40 and the height of the thickness regulating jig 70 are the same), and four rounds of the wood material 40 are elastically sealed. The material 60 is hermetically sealed. Then, by performing heating with a hot platen (and by high-frequency heating as necessary), the stabilization process (consolidation process and stabilization process in some cases) of the wood material proceeds as described above. After the predetermined heating, the pressure is released. In this case as well, heat is applied so that the high-pressure water vapor accumulated in the wood is released to the outside at one time, causing damage to the wood structure and causing no cracks on the surface or inside the wood. Lift the board very slowly.

With the rise of the hot platen, the elastic sealing material 60 which has been kept in a sealed state by being compressed by the hot platen is gradually released from the compressed state, and the degree of sealing gradually decreases. Thereby, the high-pressure steam in the enclosed space is gradually released to the outside, and the internal pressure gradually decreases,
Finally, it is almost zero. In this state, the hot plates are largely separated from each other, and the processed wood material is taken out from the hot plate, thereby completing the method for stabilizing the wood material according to the present invention.

[0016]

According to the method for stabilizing wood material of the present invention, a processed wood material having improved dimensional stability and a stable surface condition can be obtained without circulating cooling water inside the hot platen after the heating step. can get. No cooling process by cooling water circulation is required, so there is no energy loss due to repetition of heating and cooling processes, and a hot plate press with a complicated structure is required because no cooling water circulation system is required The configuration of the hot plate press required for the processing can be simplified.

Further, the method for stabilizing a wood material according to the present invention is applicable to a case where a dimensional stabilization process is performed simultaneously with a compaction, and a case where a dimensional stabilization process is performed on a wood material which has been boiled or steamed by another processing apparatus. In addition, in the case where only the dimensional stabilization processing is performed without performing the consolidation, any of the methods can be easily performed.

[0018]

The present invention will be described below with reference to examples. [Example 1] As wood material, water content 20%, thickness h = 3
A cedar material of 0 mm, width w = 150 mm, and length l = 600 mm was prepared, placed in a stainless steel rigid container having the shape shown in FIG. 1, and compressed and heated. The dimensions of the internal space formed in the container main body 10 of the stainless steel rigid container 1 are height H = 12 mm, width W = 160 mm, and length L = 610 mm.
And a 10 mm thick stainless steel plate was used as the lid 20. A heat-resistant elastic silicone packing 30 was attached to the upper edge of the container body 10 on four sides thereof.

The container main body 10 containing the cedar material and the lid 20 placed on the upper part thereof are arranged on the lower platen of a platen press having a platen. After the platen is set at 200 ° C., the pressure is 50 kgf.
The lid 20 was brought into contact with the upper edge of the container body 10 by moving the hot platen at / cm ² . In this state, heating is continued for 5 minutes and 10 minutes, and then the steam vent valve 17 attached to the side wall of the closed container 10 is opened, and high-pressure steam in the container is slowly drained over 3 minutes. When the pressure became 0, the hot platen was decompressed and isolated, and the container was taken out from between the hot plates to obtain a consolidated wood material. The cedar wood, which was initially 30 mm thick, was compressed to 12 mm (compression rate 60%).

[Comparative Example 1] After heating the wooden material in the same manner as in Example 1, cooling water was supplied to the hot platen, and after 5 minutes, the pressure was released. I got

[Example 2] As a wood material, a water content of 10
%, Thickness h = 9 mm, width w = 150 mm, length l = 60
A 0 mm phenolic resin-adhered (P type) particle board is prepared, and it is housed in the same stainless steel rigid container 1 used in Example 1 except that the height of the internal space H is 9 mm, and heated similarly. did. After a lapse of a predetermined time, the pressure on the hot platen is slowly released over 4 minutes while the temperature of the hot platen is raised very slowly, and when the pressure in the container becomes zero, the hot platen is decompressed, isolated, and heated. The container was taken out from between the panels to obtain a dimensionally stabilized particle board.

[Comparative Example 2] After heating the wooden material in the same manner as in Example 2, cooling water was supplied to the hot platen, and after 5 minutes, the pressure was released. Particle board was obtained.

Each of the test specimens prepared in Examples 1 and 2 and Comparative Examples 1 and 2 was boiled in a boiling tank for 2 hours, dried to absolute dryness, each thickness was measured, and the recovery rate was measured by the following equation. .

Further, 15 × from the central portion of each test piece
A test piece of 15 × 15 mm was taken out, and the saturated thickness expansion coefficient (ASE) was calculated by the following formula (1 hour at 25 ° C. under reduced pressure water absorption, then 2
(Immersion for 3 hours) was measured.

Comparative Example 3 Further, as Comparative Example 3, the untreated P-type particle board having a thickness of 12 mm was similarly measured for the recovery rate and the saturated thickness expansion rate (ASE). Table 1 shows the results.

[0026]

[Table 1]

[Consideration] As can be seen from the results in Table 1,
According to the method according to the present invention, there is almost no difference in the recovery rate and the saturated water expansion rate between those that have been decompressed according to the present invention and those that have been decompressed by supplying cooling water to the hot platen. It can be seen that the same stabilized wood material under the decompression treatment by supplying cooling water to the hot platen with a simple operation can be obtained. In addition, good results were obtained even when compared with the non-treated example of Comparative Example 3, which proves the effect of the present invention.

[0028]

According to the method for stabilizing wood material of the present invention,
Without circulating cooling water inside the hot plate after the heating process,
A wood material with improved dimensional stability can be obtained. As a result, it is possible to eliminate energy loss due to the repetition of the heating step and the cooling step, which contributes to energy saving, shortens the processing time, and does not require a hot plate press having a complicated structure such as a water circulation mechanism. Cost can also be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a rigid container used in an embodiment of the method of the present invention.

FIG. 2 is a diagram illustrating an embodiment of a method for stabilizing a wooden material using the rigid container of FIG.

FIG. 3 is a diagram for explaining another embodiment of the method of the present invention.

[Description of Signs] 1 ... rigid container, 10 ... container body, 15 ... steam vent hole, 1
6 ... piping, 17 ... flow control valve, 20 ... lid, 30 ... sealing material, 40 ... wood material, 50 ... hot platen

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-91611 (JP, A) JP-A-4-135702 (JP, A) JP-A-57-53304 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B27K 5/00

Claims (3)

(57) [Claims] 1. A wooden material is arranged and heated in a closed space formed between hot plates of a hot plate press, and the water inside the wooden material is converted into high-pressure steam to stabilize the wooden material. A method for stabilizing a wood material, characterized by gradually releasing pressure in the closed space at a speed that does not cause tissue destruction due to rapid release of high-pressure steam accumulated inside the wood material. 2. A closed space formed between hot plates of a hot plate press.
Placing wood material in the space has pressure resistance and heat resistance.
And a predetermined thickness inside a rigid container that can be freely opened and closed.
After storing the wood material to be treated measured to the size,
By placing a rigid container between the hot plates and sealing it,
2. A method for stabilizing wood material according to claim 1, wherein
Law. 3. A closed space formed between hot plates of a hot plate press.
Placing wood material in the space is a
Compartment with elastic sealing material somewhat higher than the thickness of the material
Wooden material measured to the specified thickness and size in the space
And compress the elastic sealing material by sandwiching it between hot plates.
The wood material according to claim 1, wherein
Stabilization method.