JP5312154B2 - Wood board drying treatment method - Google Patents

Description

  The present invention relates to a method for drying a wooden board used for building materials and the like. More specifically, the present invention relates to a drying method for drying a wooden board using a hot plate press and further improving the material.

  Conventionally, in the drying process of a wooden board using a hot plate press, in order to release the water vapor generated inside the wooden board during hot pressing, (1) the press is opened lightly at an appropriate time interval, A method of so-called “breathing” that dissipates water vapor, (2) a method of inserting a special mesh between the heat plate and the wood board that allows the passage of water vapor with almost no heat conduction. .

  However, in the breathing method of (1), when the thickness of the wooden board is increased and the temperature of the hot plate is increased, high-pressure steam gathers in the middle layer of the wooden board, and the pressure (pressing pressure) is applied during breathing. Even if it is opened for a moment, the water vapor suddenly expands inside the wooden board, and the wooden board is crushed from the inside. Therefore, in this method, it is forbidden to raise the temperature of the hot plate extremely and to increase the thickness of the wood plate, and the application range is usually limited to a thin plate of 10 mm or less.

  On the other hand, in the mesh insertion method of (2), since it is not necessary to loosen the pressure of the press during the drying process, there is no fear that the wooden board will be blasted even if the temperature of the hot plate is slightly increased. Therefore, dry cracking of the wooden board can be avoided if the pressing is continued over time until the moisture gradient in the thickness direction of the wooden board falls within the allowable range. However, also in this case, since the water vapor gathered inside the wooden board is diffused from the surface of the wooden board, the worse the drying efficiency becomes unavoidable as the thicker the wooden board becomes. In addition, when the mesh is inserted, the impression of the mesh remains on both the front and back sides of the wooden board, which causes a problem in use.

  On the other hand, the present applicant has already disclosed in Patent Document 1 that two wooden boards each having a large number of communication grooves formed on the back surface are overlapped so that the back surfaces face each other, and are formed by communication grooves. A method of discharging water vapor from the hollow portion by drying a hot plate in the form of a composite plate having a portion is proposed. In conventional hot plate drying of wooden boards, there is a problem that the thickness of the wooden board and the temperature of the hot board are limited because it does not have the function of discharging the generated water vapor from the middle layer of the wooden board. In the invention described in Document 1, by discharging water vapor from the hollow portion formed on the back surface of the wooden board, the drying efficiency can be improved without limiting the thickness of the wooden board or the temperature of the hot board. ing.

JP 2008-18643 A

However, even in the invention described in Patent Document 1, the following problems remain. In the hot plate drying process of the composite plate having the hollow portion, moisture movement is promoted from the hot plate side toward the hollow portion inside the wooden board. Then, after a while after the hot plate drying process is started, the surface of the wooden board is almost completely dry, but the vicinity of the communication groove on the back surface is kept in a humid state for a long time. For this reason, there are significant differences in the materials such as the dimensional stability of the wooden board after drying between the front and back surfaces of the wooden board, which is a major obstacle to the use of the product.
In other words, a significant speed difference is caused in the drying treatment conditions in the thickness direction of the wood board, and as a result, the material in the thickness direction of the product becomes non-uniform, resulting in inconvenience depending on the purpose of use of the product.

  The following causes are considered for this. According to previous studies, wood components such as hemicellulose and lignin are gradually decomposed when kept at high temperature and pressure in the presence of water vapor, and the resulting free radicals (radicals) undergo a whimsical recombination. do. The material of the wood material changes depending on the degree of decomposition and recombination. Here, this decomposition / recombination is abbreviated and simply called “reaction”. Although this “reaction” is caused by the presence of water vapor, it has been experimentally clarified that this “reaction” does not occur at a wet site where a large amount of condensed water or the like inside the material exists.

  In the hot plate drying process, the moisture contained in the wood material heated by the hot plate moves and stays toward the back of the material while repeating vaporization and condensation, and is sequentially discharged to the outside from the communication groove formed on the back. The However, since this moisture transfer and discharge takes a relatively long time, in the meantime, in the layer close to the hot plate in the wooden board (layer close to the front surface), the “reaction” occurs successively, but the layer close to the back surface. Then, the “reaction” is inhibited by the retention of condensed water. As a result, the material in the thickness direction of the product becomes non-uniform.

  The present invention solves the above-mentioned conventional problems, and can achieve a drying efficiency without limiting the thickness of the wood board or the temperature of the hot board, and can obtain a wood board of a uniform material. A method is provided.

The method for drying treatment of a wood board according to claim 1 has a plate-like hygroscopic property and water absorption property in which a space portion communicating with at least one end surface is formed between two wood boards which are materials to be treated. The material to be treated is hot-pressed by a hot plate press in a state where an exhaust member made of a material is arranged.
Here, “hygroscopic” refers to the property of absorbing water vapor (gaseous moisture), and “water absorption” refers to the property of absorbing water (liquid moisture).

The invention according to claim 2 is the method for drying treatment of wood board according to claim 1, wherein the exhaust member, characterized in that it is a wood material.

The invention according to claim 3 is the wood board drying method according to claim 1 or 2 , wherein the moisture content of the exhaust member is lower than the moisture content of the material to be treated before the drying treatment. It is characterized by.

According to a fourth aspect of the present invention, in the wood board drying method according to any one of the first to third aspects, the space portion is at least one of a front surface and a back surface of the exhaust member. It is characterized by communicating with.

According to a fifth aspect of the present invention, in the wood board drying method according to the fourth aspect , the space portion is a groove formed on the front and back surfaces of the exhaust member.

According to a sixth aspect of the present invention, in the wood board drying method according to any one of the first to fifth aspects, an enclosing member is provided around the material to be treated, and the woody material is subjected to heat pressure. In addition to forming a water vapor chamber that holds the water vapor discharged from the plate inside, and providing a leakage means for leaking the water vapor in the water vapor chamber to the outside at the time of hot pressure, the water vapor partial pressure in the water vapor chamber at the time of hot pressure is almost constant It is characterized by adjusting to.

The invention according to claim 7 is the method for drying treatment of a wood board according to claim 6 , wherein the water vapor partial pressure is within the range of 60 to 90% of the saturated water vapor pressure at the temperature of the hot plate of the hot plate press. It is characterized by being adjusted almost constant.

The invention according to claim 8 is the wood board drying method according to claim 6 or claim 7 , further comprising a water supply means for supplying water to the interface between the hot plate of the hot plate press and the wooden board, When the leakage of water vapor by the leakage means becomes excessive, the water vapor is replenished to adjust the water vapor partial pressure to be substantially constant.

According to the first aspect of the present invention, since the plate-like exhaust member is disposed between the two wooden boards as the material to be treated, the hot pressing is performed by the hot press, so the wooden board heated by the hot board Although the contained water moves from the front surface of the wooden board toward the back surface and stays, it can be sequentially discharged outside through the space of the exhaust member. Furthermore, the moisture content that has moved from the front surface to the back surface of the wooden board can be temporarily retained inside the exhaust member. As a result, most of the portion where the above-mentioned “reaction” is inhibited can be limited to the exhaust member. As a result, the material of the wood board can be finished uniformly.
Moreover, since the space part connected to the at least 1 end surface is formed in the exhaust member, the water | moisture content temporarily retained can be discharged | emitted from a space part as water vapor | steam.
Moreover, since the exhaust member is made of a hygroscopic and water-absorbing material, the contained moisture that has moved from the front surface of the wooden board toward the back surface can be more effectively absorbed and retained in the interior. Thereby, the above-mentioned “reaction” is not inhibited on the back side of the wood board, and as a result, a wood board having a uniform material can be obtained.

According to the invention described in claim 2 , since the exhaust member is a wood material, it is excellent in hygroscopicity and water absorption, and the processing of the space portion is easy.

Further, according to the invention described in claim 3 , since the moisture content of the exhaust member is lower than the moisture content of the material to be treated before the drying treatment, the moisture content that has moved from the surface of the wooden board toward the back surface Can be more effectively absorbed and retained in the interior.

Moreover, according to the invention of claim 4 , since the space portion communicates with at least one of the front surface and the back surface of the exhaust member, the moisture content that has moved from the front surface of the wooden board toward the back surface is reduced. It can be easily absorbed from the front or back surface of the exhaust member. Furthermore, the moisture content that has been absorbed and retained inside can be easily discharged from the end face of the exhaust member through the communicating space.

According to the fifth aspect of the present invention, since the space is a groove formed on the front and back surfaces of the exhaust member, the water vapor can be easily discharged to the outside by a simple process.

Further, according to the invention described in claim 6 , by providing the surrounding member around the material to be treated, it is possible to form a water vapor chamber that holds the water vapor discharged from the wooden board at the time of hot pressure inside. Furthermore, by providing a leakage means for leaking water vapor in the water vapor chamber to the outside, a flow of water vapor can be created, and the water vapor chamber can be uniformly filled with water vapor. As a result, the water vapor partial pressure in the water vapor chamber at the time of hot pressure can be adjusted to be substantially constant. Thereby, the moisture movement in the wooden board proceeds slowly, and the wooden board can be dried in an atmosphere having a constant water vapor partial pressure. In particular, if the atmosphere reaches the saturated water vapor pressure, condensed water may stay in the wood board and the "reaction" may occur non-uniformly, but there is no excess or deficiency by controlling the water vapor partial pressure. Can be charged. And the variation in the material after drying can be decreased.

According to the invention of claim 7 , the water vapor partial pressure is adjusted to be substantially constant within a range of 60 to 90% of the saturated water vapor pressure at the temperature of the hot plate of the hot plate press. Can be effectively adjusted.

Further, according to the invention described in claim 8 , by providing a water replenishing means for replenishing water at the interface between the hot plate and the wood board, water is replenished when the leakage of water vapor by the leakage means becomes excessive. Thus, the water vapor partial pressure can be adjusted to be substantially constant. As a result, moisture is given to the surface of the wood material, while the water vapor in the water vapor chamber is leaked by the leakage means to create a flow of water vapor with a constant partial pressure, and more accurately "reaction" inside the wood material during the drying process. Can be prevented from occurring unevenly. In particular, when the wood board is thick, the water vapor is diluted in the part close to the hot plate due to the movement or “reaction” consumed inside, and it is difficult to supplement it from the surroundings. It becomes insufficient. For this reason, it is effective to always supply a water vapor to the interface between the hot plate and the wooden board, and at the same time to leak the water vapor to the outside by the leakage means so as to always make a water vapor flow.

  As described above, according to the present invention, it is possible to obtain a wooden board of a uniform material by making the “reaction” generated inside the wooden material uniform.

It is a perspective view which shows the member for exhaust_gas | exhaustion which concerns on Embodiment 1-3. It is a front view which shows the laminated body which concerns on Embodiment 1-3. It is a front view which shows the drying process state of the wooden board which concerns on Embodiment 1. FIG. It is a figure which shows the flow of the drying process of the wooden board which concerns on Embodiment 1. FIG. It is a figure which shows the flow of the drying process of the wooden board which concerns on other embodiment. It is a front view which shows the member for exhaust_gas | exhaustion which concerns on other embodiment. It is a front view which shows the member for exhaust_gas | exhaustion which concerns on other embodiment. It is a front view which shows the drying process state of the wooden board which concerns on Embodiment 2. FIG. It is a front view which shows the drying process state of the wooden board which concerns on other embodiment. It is a front view which shows the drying process state of the wooden board which concerns on Embodiment 3. FIG.

  Next, with reference to FIG. 1 thru | or FIG. 4, the drying processing method of the wooden board which concerns on Embodiment 1 of this invention is demonstrated. FIG. 1 is a perspective view showing an exhaust member 2 according to the first embodiment, and FIG. 2 is a front view showing a laminated body 4 according to the first embodiment. FIG. 3 is a front view showing a state of drying processing of the wooden board according to the first embodiment, and FIG. 4 is a diagram showing a flow of drying processing of the wooden board according to the first embodiment.

  First, the exhaust member 2 used in the wood board drying process according to the present embodiment will be described. As shown in FIG. 1, the exhaust member 2 is a plate-like member. As shown in FIG. 2, the exhaust member 2 is inserted between the wooden boards 1a and 1b, which are materials to be processed, and discharges moisture contained in the wooden boards 1a and 1b. During the movement and discharge of the water, which takes a long time, the water contained in the wooden boards 1a and 1b is temporarily retained in the exhaust member 2 and then used to sequentially discharge it as water vapor.

  Although various materials can be used for the exhaust member 2, it is preferable to use a material having hygroscopicity and water absorption for the moisture retention function. Here, “hygroscopic” refers to the property of absorbing water vapor (gaseous moisture), and “water absorption” refers to the property of absorbing water (liquid moisture). For example, it is preferable to use wood materials such as wood materials and plywood, and inorganic materials such as calcium silicate plates and cement plates. Moreover, it is preferable that the moisture content of the exhaust member 2 is lower than the moisture content of the wooden boards 1a and 1b, which are the materials to be treated, before the drying treatment. Hereinafter, the exhaust member 2 in the present embodiment will be described as a wood material.

  A groove 3a is formed on the surface of the exhaust member 2, and similarly, a groove 3b is formed on the back surface. The groove 3a is formed by inserting a plurality of saws at an arbitrary angle with respect to the fiber direction of the wood material so that moisture can be easily discharged through the cell cavity. The groove 3b is formed by inserting a plurality of saws so as to be orthogonal to the saws on the surface. The grooves 3 a and 3 b are space portions that communicate with the end surface of the exhaust member 2.

  The thickness required for the exhaust member 2 needs to be changed depending on the initial moisture content of the wooden boards 1a and 1b, which are materials to be treated, and the moisture content of the exhaust member 2. For example, assuming that the initial moisture content of the wooden boards 1a and 1b is 70% or less and the moisture content of the exhaust member 2 is about 10%, the thickness is estimated from the maximum amount of moisture that the exhaust member 2 can hold. It is sufficient that the thickness is equal to or somewhat thinner than the thickness of each of the wooden boards 1a and 1b.

  The pitch of the grooves 3a, 3b of the exhaust member 2 is about twice the thickness of this member, and the depth of cut of the grooves 3a, 3b is such that the upper and lower grooves are connected and water vapor is easily discharged. It may be a little deeper than 1/2. The groove width is suitably 2 to 3 mm.

  Next, the drying process process by a hot plate press is demonstrated. First, as shown in FIG. 2, an exhaust member 2 is inserted between two wood boards 1a and 1b, which are materials to be processed, to form a three-layer laminate 4. And as shown in FIG. 3, the comprised laminated body 4 is inserted between the hot plates 5a and 5b of a hot plate press, and a drying process is performed by heat conduction from the hot plates 5a and 5b while suppressing lightly. FIG. 4 shows the flow of this drying process.

  In this drying process, the atmosphere surrounding the laminate 4 is 1 atm throughout, and the temperature of the hot plate is usually in the range of 160 to 220 ° C. In the initial stage of drying, in the portion where the heat plate 5a and the wood plate 1a are in contact and the portion where the heat plate 5b and the wood plate 1b are in contact with each other, the water in the wood plate is vigorously vaporized and there is no escape, so that the wood gradually becomes high-pressure steam. Expands toward the inside of the board.

  Within the range where the high-pressure steam spreads, the “reaction” of the wood component occurs, but when the range is dried and the water vapor moves toward the middle layer, the “reaction” ends. On the other hand, since the water vapor is supersaturated and condensed at the tip of the high-pressure water vapor moving toward the middle layer, no “reaction” occurs.

  Such a belt-like “reaction” region moves toward the middle layer of the wood board as time passes, and is driven into the exhaust member 2 at the final stage of the drying process. And the water | moisture content which stayed temporarily inside the member 2 for exhaust_gas | exhaustion is discharged | emitted outside as water vapor | steam. Therefore, a “reaction” occurs also on the back side of the wooden boards 1a and 1b, and the interior of the wooden materials 1a and 1b finally becomes uniform. Note that the moving speed of the belt-like “reaction” region in the first embodiment depends on the initial moisture content of the material to be treated.

As described above, according to the wood board drying method according to the first embodiment, the plate-like exhaust member 2 is disposed between the two wood boards 1a and 1b, which are the materials to be processed, in the hot press. Therefore, the moisture contained in the wooden boards 1a and 1b heated by the hot plates 5a and 5b moves and stays from the front surfaces of the wooden boards 1a and 1b to the back surface. It can be discharged to the outside through the grooves 3a and 3b. Further, the contained moisture that has moved from the front surface to the back surface of the wooden boards 1a, 1b can be temporarily retained in the exhaust member 2. As a result, most of the portion where the above-mentioned “reaction” is inhibited can be limited to the exhaust member 2, and as a result, the materials of the wood boards 1 a and 1 b can be finished uniformly.
Further, since the exhaust member 2 is formed with the grooves 3a and 3b communicating with the end face, the temporarily contained moisture can be discharged from the grooves 3a and 3b as water vapor.

  Further, by using a hygroscopic and water-absorbing material for the exhaust member 2, the contained moisture that has moved from the front to the back of the wooden boards 1 a and 1 b is more effectively absorbed and retained in the interior. Can be made. Thereby, the "reaction" mentioned above is not inhibited on the back surface side of the wooden boards 1a and 1b, and as a result, a wooden board having a uniform material can be obtained.

  Moreover, if a wood material is used for the exhaust member 2, it is excellent in hygroscopicity and water absorption, and the processing of the groove portions 3a and 3b which are space portions is easy.

  Further, before the drying process, the moisture content of the exhaust member 2 is lower than the moisture content of the wood boards 1a and 1b, which are the materials to be treated, so that the wood boards 1a and 1b move from the front surface to the back surface. The contained moisture that has been absorbed can be more effectively absorbed and retained in the interior.

  Further, by forming the grooves 3a and 3b on the front and back surfaces of the exhaust member 2 to form space portions, it is possible to easily discharge water vapor to the outside by simple processing.

  In the first embodiment, the exhaust member 2 is inserted between the two wood boards 1a and 1b, which are materials to be processed, to form a three-layer laminate 4, and then the laminate 4 is heated. Although it is inserted between the hot plates 5a and 5b of the press, it is not always necessary to configure the laminate 4. For example, as shown in FIG. 5, the exhaust member 2 may be installed in advance on the press side like a board surface of a multi-stage press, and the material to be processed may be inserted later.

  Further, the number of the grooves 3a and 3b of the exhaust member 2 is not particularly limited, and it is not always necessary to communicate with all the end surfaces, and it is sufficient that the exhaust members 2 communicate with at least one end surface. However, in order to effectively discharge water vapor, it is preferable to communicate with many end faces.

  6 and 7 show an exhaust member according to another embodiment. As shown in FIG. 6, the exhaust member 12 is a plate-like member in which holes 13 and 14 are formed in the horizontal direction as a space. The hole 13 communicates from the end surface of the exhaust member 12 to the end surface (from the front side to the back side in FIG. 6). Similarly, the hole 14 communicates from the end surface of the exhaust member 12 to the end surface (from the right side to the left side in FIG. 6). As a result, the hole 13 and the hole 14 are orthogonal to each other. By forming the holes 13 and 14 in this way, the contained moisture that has been absorbed and retained inside can be discharged from the end face of the exhaust member 12 through the communicating holes 13 and 14. In order to effectively discharge water vapor, the space portion preferably communicates with a large number of end faces. However, either one of the holes 13 and the holes 14 is provided, or the end faces are moved from the end faces to the end faces. The effect can also be obtained by a method of communicating with only one end face without communicating.

  As shown in FIG. 7, the exhaust member 22 is a plate-like member in which holes 23 and 24 are formed in the horizontal direction and holes 25 are formed in the vertical direction as space portions. Similar to the exhaust member 12 shown in FIG. 6, the hole 23 and the hole 24 are orthogonal to each other. On the other hand, the hole 25 is opened from the front and back surfaces of the exhaust member 22 and communicates with the hole 23 and the hole 24. As a result, a space is formed by the holes 23, 24, and 25 so that the end surface and the front and back surfaces of the exhaust member 22 communicate with each other. As described above, the space portion communicates with the front and back surfaces of the exhaust member 22 so that the contained moisture that has moved from the surface of the wooden board toward the back surface is easily absorbed from the front and back surfaces of the exhaust member 22. be able to. Furthermore, the moisture content that has been absorbed and retained therein can be easily discharged from the end face of the exhaust member 22 through the communicating holes 25, 23, and 24. The holes 23 and 24 may communicate with both the front surface and the back surface, or may communicate with either one.

  Next, with reference to FIG. 8, the drying processing method of the wooden board which concerns on Embodiment 2 of this invention is demonstrated. FIG. 8 is a front view showing a dry treatment state of the wooden board according to the second embodiment. In addition, the same code | symbol is attached | subjected to the part same as Embodiment 1, and description is abbreviate | omitted.

  The wood board drying method according to the second embodiment is different from the first embodiment in that a water vapor chamber is formed. As shown in FIG. 8, a surrounding member 6 is provided around the laminated body 4 composed of the wooden boards 1 a and 1 b and the exhaust member 2. For example, a steel frame can be used as the surrounding member 6. The enclosing member 6 forms a water vapor chamber 11 that retains the water vapor discharged from the wood boards 1a and 1b during hot press.

  In addition, the surrounding member 6 is provided with a leakage means including an exhaust pipe 7 and a pressure reducing control valve 8 so that the water vapor in the water vapor chamber 11 is leaked to the outside during the heat pressure. With such a configuration, the partial pressure of water vapor in the water vapor chamber 11 at the time of hot pressure can be adjusted to be substantially constant.

  When the wood materials 1a and 1b are hot-pressed in the water vapor chamber 11, the water vapor partial pressure in the water vapor chamber 11 rises and eventually reaches a saturated vapor pressure. In this state, a slight local temperature change occurs. In addition, the water vapor only condenses and evaporates inside the wood material, and the material does not dry, and depending on the location, excess water remains as free water, so the “reaction” is locally inhibited.

  In order to avoid this adverse effect, in the second embodiment, the decompression control valve 8 is operated to discharge water vapor to the outside through the exhaust pipe 7 and adjust the water vapor partial pressure in the water vapor chamber to be substantially constant. The water vapor partial pressure to be adjusted is preferably 60 to 90% of the saturated water vapor pressure at the hot plate temperature of the hot plate press, as shown in the experimental results described later.

  In this range of water vapor partial pressure, the drying rate of the wood material and the degree of “reaction” can be executed in various balances. For example, when the water vapor partial pressure is adjusted to 60%, the drying of the wood material is accelerated, but the degree of uniformity of the product material is low. Moreover, when adjusted to 90%, it takes a long time to dry the wooden material, but the degree of uniformity of the product material is high. Therefore, the adjustment of the water vapor partial pressure may be selected according to the intended use of the product.

  Thus, according to the drying method of the wooden board which concerns on Embodiment 2, by providing the surrounding member 6 around the wooden boards 1a and 1b which are to-be-processed materials, it discharges | emits from the wooden boards 1a and 1b at the time of a hot press. It is possible to form the water vapor chamber 11 that holds the water vapor inside. Furthermore, by providing leakage means (exhaust pipe 7 and pressure reducing adjustment valve 8) for leaking the water vapor in the water vapor chamber 11 to the outside, a flow of water vapor can be created, and the water vapor chamber 11 is uniformly filled with water vapor. be able to. As a result, the water vapor partial pressure in the water vapor chamber 11 at the time of hot pressure can be adjusted to be substantially constant. Thereby, moisture movement in the wooden boards 1a and 1b proceeds slowly, and the wooden boards 1a and 1b can be dried in an atmosphere of a constant water vapor partial pressure. In particular, if the atmosphere reaches the saturated water vapor pressure, condensed water may stay in the wooden boards 1a and 1b, and "reaction" may occur non-uniformly. It can be filled with water vapor without water. And the variation in the material after drying can be decreased.

  Moreover, by adjusting the water vapor partial pressure to be substantially constant within the range of 60 to 90% of the saturated water vapor pressure at the temperature of the hot plates 5a and 5b of the hot plate press, the variation in the material after drying is effectively adjusted. can do.

  In the second embodiment, as shown in FIG. 8, the surrounding member 6 is provided between the hot plates 5a and 5b. However, if the surrounding member 6 can surround the wood materials 1a and 1b which are materials to be processed. Good. For example, as shown in FIG. 9, it is good also as a structure which surrounds the hot plates 5a and 5b.

  Next, with reference to FIG. 10, the drying processing method of the wooden board which concerns on Embodiment 3 of this invention is demonstrated. FIG. 10 is a front view illustrating a dry treatment state of the wooden board according to the third embodiment. In addition, the same code | symbol is attached | subjected to the part same as Embodiment 1 and Embodiment 2, and description is abbreviate | omitted.

  The wood board drying method according to the third embodiment is different from the second embodiment in that water supply means is provided. As shown in FIG. 10, ventilation members 9a and 9b having a smooth surface such as a wire net and steam spray plates 10a and 10b are provided above and below the laminate 4 composed of the exhaust member 2 and the wood boards 1a and 1b. It is set over again. Of these, the upper steam spray plate 10a and the ventilation member 9a may be fixed in advance to the heat plate 5a, and the lower steam spray plate 10b and the ventilation member 9b may be fixed in advance to the heat plate 5b. These water replenishing means can replenish water to the interface between the hot plate 5a and the wooden board 1a and the interface between the hot plate 5b and the wooden board 1b at the time of hot pressure. When the leakage of water becomes excessive, the water vapor partial pressure can be adjusted to be almost constant by supplying water.

  Here, according to the calculation, if the volume of the water vapor chamber surrounding the wood board having a specific gravity of 0.5 is about several times the volume of the wood board, the space is filled with saturated water vapor at 180 ° C., for example. The amount of water required for this is a slight amount corresponding to 10% in terms of the moisture content of the wooden board. Therefore, most of the water that comes out in the hot plate drying process of wet wood board is unnecessary for "reaction". In order to quickly discharge this excess water, the surrounding water vapor partial pressure should be as low as possible in the first half of the drying process. However, in the drying process of a thick wooden board, if this is accelerated too quickly, there will be a shortage of water vapor necessary for the “reaction” in the part close to the hot plate of the wooden material, resulting in unevenness in the material of the product. It becomes.

  Thus, in the third embodiment, water vapor adjusted to a constant partial pressure (preferably within a range of 60 to 90% of the saturated water vapor pressure at the temperature of the hot plate) is injected from the water vapor injection plates 10a and 10b. This water vapor injection need not be performed at the initial stage of the drying process because the water vapor partial pressure in the water vapor chamber 11 is higher. Rather, only the exhaust from the exhaust pipe 7 may be used. However, at the end of the drying process, there is a tendency for water vapor to be insufficient at the interface between the hot plate and the wood material, so that it is necessary to send water vapor from the water vapor spray plates 10a and 10b to the interface so that the "reaction" occurs uniformly. There is. In addition, the timing which sends water vapor | steam changes with the gas permeability of a wooden board, and the adjustment state of water vapor leak.

  As described above, according to the wood board drying method according to the third embodiment, the water supply means (water vapor spray boards 10a and 10b) for supplying water to the interfaces between the hot plates 5a and 5b and the wood boards 1a and 1b is provided. Thus, when the leakage of water vapor by the leakage means (the exhaust pipe 7 and the pressure reducing adjustment valve 8) becomes excessive, it is possible to replenish water and adjust the water vapor partial pressure to be substantially constant. As a result, moisture is given to the surfaces of the wood materials 1a and 1b, while the water vapor in the water vapor chamber 11 is leaked by the leakage means (the exhaust pipe 7 and the pressure reducing control valve 8) to create a flow of water vapor with a constant partial pressure. Thus, it is possible to avoid the occurrence of “reaction” in the woody materials 1a and 1b during the drying process more accurately. In particular, when the wooden boards 1a and 1b are thick, the water vapor is diluted in the portion close to the hot plates 5a and 5b due to the movement or "reaction" consumed inside, and it is difficult to supplement it from the surroundings. As a result, water vapor is partially insufficient. For this reason, water is supplied to the interface between the hot plates 5a and 5b and the wood plates 1a and 1b, and at the same time, the water vapor is leaked to the outside by the leakage means (the exhaust pipe 7 and the pressure reducing valve 8), so It is effective to make.

  Table 1 shows the experimental results of the veneer modification in which the hot plate drying was performed by the wood board drying method according to the third embodiment.

  As shown in Table 1, the width direction and the length direction are modified in any of Examples 1 to 6 as compared with the comparative example (one obtained by drying the roll dryer). On the other hand, the thickness direction is not modified in Example 1 in which the regulated vapor pressure is 38% of the saturated vapor pressure. Further, the reforming effect of Example 5 in which the regulated vapor pressure is 85% of the saturated vapor pressure is generally large. From this experimental result, it can be seen that a favorable reforming effect can be obtained by adjusting the regulated vapor pressure to 60 to 90% of the saturated vapor pressure.

  As described above, according to the present invention, it is possible to obtain a wooden board of a uniform material by making the “reaction” generated inside the wooden material uniform.

DESCRIPTION OF SYMBOLS 1a Wood board 1b Wood board 2 Exhaust member 3a Groove 3b Groove 4 Laminate 5a Hot plate 5b Hot plate 6 Enclosing member 7 Exhaust pipe 8 Depressurization regulating valve 9a Vent member 9b Vent member 10a Steam jet plate 10b Steam jet plate 11 Steam chamber 12 exhaust member 13 hole 14 hole 22 exhaust member 23 hole 24 hole 25 hole

Claims (8)

In a state where an exhaust member made of a plate-like hygroscopic and water-absorbing material in which a space portion communicating with at least one end surface is disposed between two wood boards as the material to be treated is disposed. A method for drying a wooden board, characterized in that the material is hot pressed by a hot plate press. 2. The method for drying a wood board according to claim 1 , wherein the exhaust member is a wood material. The wood board drying method according to claim 1 or 2 , wherein a moisture content of the exhaust member is lower than a moisture content of the material to be treated before the drying treatment. The space portion, a method for drying treatment of wood board according to any one of claims 1 to 3, characterized in that at least Tsueto communication surface and the back surface of the exhaust member. The said space part is the groove | channel formed in the front and back of the said exhaust member, The drying processing method of the wooden board of Claim 4 characterized by the above-mentioned. Leakage that provides an enclosing member around the material to be treated to form a water vapor chamber that internally retains water vapor discharged from the wood board during hot pressure, and leaks water vapor in the water vapor chamber to the outside during hot pressure Providing means,
The method for drying a wood board according to any one of claims 1 to 5 , wherein a partial pressure of water vapor in the water vapor chamber at the time of hot pressure is adjusted to be substantially constant. The method for drying a wood board according to claim 6 , wherein the water vapor partial pressure is adjusted to be substantially constant within a range of 60 to 90% of a saturated water vapor pressure at a temperature of a hot plate of the hot plate press. . A water replenishing means for replenishing water is provided at the interface between the hot plate of the hot plate press and the wooden board, and when the leakage of water vapor by the leakage means becomes excessive, water is replenished to substantially reduce the water vapor partial pressure. The method for drying treatment of a wood board according to claim 6 or 7 , wherein the method is adjusted to be constant.

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