JP7448179B2 - Compression bonded board material and method for manufacturing compression bonded board material - Google Patents

Description

The present invention relates to a compression-joined board material and a method for manufacturing a compression-joined board material, and particularly to a method for manufacturing a compression-joint board material and a compression-joint board material in which board materials are joined by heating and compression.

Conventionally, coniferous trees such as cedar grow quickly but have a small specific gravity and are soft, so when used for furniture etc., the surface tends to be easily scratched, and when used as building materials, there is a risk of insufficient strength, etc. was there.

Therefore, as shown in Patent Document 1, it has been conventionally practiced to compress wood such as coniferous trees to increase the strength of the wood. Specifically, a wood compression processing method involves heating and softening wood such as cedar using steam and high-frequency dielectric heating in a high-temperature, high-pressure container, and then compression-molding and fixing the compressed shape in a high-temperature, high-pressure atmosphere. is disclosed.

According to this wood compression processing method, the wood absorbs water vapor and its temperature rises, and at the same time, the temperature rises from inside due to high-frequency dielectric heating, and the wood is heated and softened rapidly. By applying mechanical compressive force in this state, the fine cavities that mainly exist in the earlywood region become smaller and compressed, resulting in a hard and strong wood.

Japanese Patent Application Publication No. 5-50409

However, according to Patent Document 1, wood compression is performed on logs and grained materials, and when the grained materials are heated and compressed in the thickness direction, if the grained materials include knots, Large compressive stress is generated at the joints, which may cause cracks and cracks. Additionally, around the knots, if there is any disturbance or inclination in the fiber direction of the grain of the tree, a relatively large compressive stress will be generated, which may cause cracks or cracks. Furthermore, when compressing grained materials in the thickness direction that has additional grains that transition from grain to straight grain, there is a risk of cracks or cracks occurring during compression since the back side of the grained materials is straight grained. . In particular, if there are continuous knots or straight-grained portions from the front surface to the back surface, problems such as cracks and cracks during compression are noticeable. In order to avoid such problems, it is conceivable to select only planks without knots or straight-grained parts when harvesting the wood, but this would reduce the yield and result in a situation that goes against the effective use of wood resources.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a compression-bonded board material and a compression-bonded board material that are free from cracks or cracks even if the board has knots or straight-grained parts. The purpose of this invention is to provide a method for manufacturing the same.

The compression bonded board material according to claim 1 for achieving the above object,
In a compression bonded board material formed by joining at least two planks and heating and compressing them,
The at least two boards to be joined each have a knot and/or a straight grain part,
The at least two sheets of grain material are joined such that the grain surfaces thereof are joined to each other and the outermost surface thereof is the grain surface, and are bonded by being heated and compressed toward the joint surface. ,
The knots and/or straight grain portions present in each of the at least two sheets of grain material are arranged so as not to overlap each other in the thickness direction perpendicular to the joint surface.

According to this configuration, in the case of grained materials that would cause cracks or cracks if compressed as they are due to the presence of knots, at least two grained materials can be joined and used. Boards that could not be used alone can now be used as compressed wood. In other words, even if there are knots and/or straight-grained portions in the planks to be joined, they do not overlap in the thickness direction with the knots and/or straight-grained portions in the stacked planks, so they are not compressed. When this happens, the knots and/or straight-grained sections are more flexibly received in the normal plank section, avoiding stress concentrations. Therefore, the compression-bonded board material according to the present invention is a compression-bonded board material that does not have cracks or cracks in knots or straight-grained portions.

The method for producing a compression bonded board material according to claim 2 for achieving the above object includes:
In the method for manufacturing compression bonded grain material for producing the compression bonded grain material according to claim 1,
a joining step of joining at least two sheets of grained material each having knots and/or straight-grained portions to each other at the grain surface so that the outermost surface thereof is the grain surface;
a heating compression step of heating and compressing the joined board material in its thickness direction,
The joining of the planks in the joining step is characterized in that the mutual joints and/or straight-grained portions are arranged so as not to overlap each other in the thickness direction perpendicular to the joining surface .

According to this method, the knots and/or straight-grained portions present in each plate material to be joined are arranged so that they do not overlap each other in the thickness direction, and the knots and/or straight grain portions present in each plate material are arranged so that they do not overlap each other in the thickness direction. The pressure from the grain side of the outermost surface that acts on the knots and/or straight-grained portions is absorbed by the opposing grain material that has become soft during heating and compression from the knots and/or straight-grained portions. Therefore, it is possible to prevent the occurrence of cracks and cracks due to concentration of stress in knots and straight-grained parts, and to obtain compression-bonded board material that is free from cracks and cracks even if the board has knots and straight-grained parts. This makes it possible to utilize wood with knots and/or straight-grained parts as wood for compression.

Further, the method for manufacturing a compression bonded grain material according to claim 3 is the method for manufacturing a compression bonded grain material according to claim 2, which includes:
The joining of the planks in the joining step is such that when the knots and/or straight-grained portions are present on the surfaces of the planks to be joined, the knots and/or straight-grained portions are opposite to each other on the joining surface. It is characterized by being arranged so that it does not occur.

According to this method, it is possible to avoid heating and compressing the knots and/or straight-grained portions that are exposed on the joining surface while being brought into contact with each other and joined together. Therefore, the stress in the knots and/or straight-grained portions is absorbed by the soft grained portions, and cracks and cracks are effectively prevented from occurring in those portions. In particular, knots and/or straight-grained portions that continuously exist between the front and back surfaces of the grained material are prevented from overlapping each other in the thickness direction, and the occurrence of cracks and cracks is more accurately avoided.

The method for manufacturing a compression bonded grain material according to claim 4 is the method for manufacturing a compression bonded grain material according to claim 2, comprising:
Before the heat compression step, an adhesive application step is performed in which a thermosetting adhesive is applied to the joint surfaces of the two planks facing each other at the joint surface, and during the subsequent heat compression step, the It is characterized in that the thermosetting adhesive is cured.

According to this method, the applied adhesive is cured during the heating and compression process, so the number of steps can be reduced compared to a method in which the adhesive is heated and compressed after it has hardened. In other words, compared to the case where adhesive is applied to two facing planks, the adhesive is cured, and then heated and compressed, it is possible to apply a thermosetting adhesive to the facing two planks. It is possible to shorten the working time by carrying out the heat compression process without waiting for the coating material to be applied to the grain material and hardened.

According to the present invention, even if the grained material has knots or straight-grained parts, the stress concentrated there during compression is absorbed by the opposing grained material, so the compression-jointed grained material is free from cracks and cracks. This opens the door to the use of softwood planks with knots and straight-grained parts, which were unsuitable as compressed wood, as compressed wood. This makes it possible to contribute to the effective use of wood resources.

FIG. 2 is a perspective view of a compression bonded board material of the present invention. FIG. 2 is a perspective view of two planks immediately before a joining process. It is a flowchart of the manufacturing method of the compression bonded board material based on this Embodiment. FIG. 2 is a vertical cross-sectional view schematically showing a wood compression device used in a compression molding process. It is a schematic front view explaining a heating compression process.

The compression bonded board material according to this embodiment will be explained in detail with reference to FIG. 1.

In this embodiment, an example is shown in which two sheets of grain material are compressed and joined. In this application, this grain material is wood cut from coniferous trees and/or hardwoods. Examples of coniferous trees include, but are not limited to, cedar, pine, cypress, hemlock, spruce, fir tree, Japanese yew, Japanese yew, and Japanese cypress. Furthermore, examples of broad-leaved trees include, but are not limited to, those with small specific gravity such as thorn, lily, and lily. In this application, grained wood is wood that is sawn from logs in the tangential direction of the annual rings, and refers to so-called core-free wood that is obtained by removing the center of the annual rings. In addition, the term "grained wood" includes "sawn wood" which is intermediate between straight-grained and board-grained wood. Here, straight-grain refers to the grain of wood where the growth rings that appear when the log is sawn towards the center are parallel, and the wood obtained by sawing in this way is called straight-grain wood. Furthermore, grained wood has a wood surface and a wood back surface, and the surface closer to the center of the growth rings is called the wood back surface, and the surface farther from the center of the growth rings is called the wood surface.

<Compression bonded board material>
FIG. 1 is a diagram showing a compression bonded board material 10 according to the present invention, which was produced in practice, and is shown as a perspective view. Knots 20 and straight-grained portions 22 are present in the grain material 12, one of the grain materials (12, 14) to be joined.

What is characteristic about the compression bonded board material 10 according to the present invention is the position and thickness of the knots and straight-grained portions of the board material 14 to which the knots 20 and straight-grained portions 22 present in one of the board-grained materials 12 are joined. This means that they do not overlap in the horizontal direction (direction perpendicular to the joint surface). When a material having knots and/or straight grain portions is used as the grain material 14, the positions of the knots and/or straight grain portions in the thickness direction are arranged so as not to overlap with each other.

FIG. 2 is a perspective view showing two planks 12 and 14 in a joining process, which will be described later with reference to FIG. Knots 20-1 are present on the outer surface of the grain material 12. Although it cannot be seen from this drawing whether this node 20-1 exists only on the outer surface side or is exposed on the joint surface side, it is the same in either case, and in the thickness direction, it is exposed on the other side. It is understood that there is no overlap with the knots and/or straight grain portions on the wood 14 side.

Further, a straight-grained portion 22 is partially present on the grain surface of the grained material 12 on the joint surface side with the grained material 14, and is opposed to the grained portion of the grained material 14 .

In this state, the grained material 12 and the grained material 14 are joined at their grain surfaces, and compressed in a process described later to form the compressed and bonded grained material 10 as shown in FIG. In the compression bonded grain material 10, the knots 20-1 and the straight grain portions 22 present in the grain material 12 can avoid the occurrence of cracks or cracks when only the grain material 12 is compressed. That is, during compression, the knots 20-1 and straight-grained portions 22 present in the grained material 12 are received by the grained portions of the grained material 14, which are softer than the knots and straight-grained portions during heat compression. , damage due to stress concentration is avoided.

In addition, in the compression bonded board material 10 according to the present embodiment, the thickness of the board materials 12 and 14 is 28 mm, respectively, and the thickness of the compression bonded board material 10 obtained by joining and compressing them is 28 mm. The length was 28 mm. In other embodiments, a 21 mm thick compression bonded board was obtained by using a 14 mm thick board and a 28 mm thick board.

Further, in this embodiment, a compression-bonded plate material is manufactured using two sheets of grain material, but a compression-bonded board material is also manufactured using three sheets of grain material. Specifically, two boards with a thickness of 7 mm and a board with a thickness of 28 mm are used to create a compressed joint board with a thickness of 21 mm, and two boards with a thickness of 14 mm. A compression bonded board with a thickness of 28 mm was also obtained using a board with a thickness of 28 mm.

Further, in this embodiment, the knots and/or straight grain portions present in each of the grain materials 12 and 14 are arranged so as not to overlap with each other in the direction perpendicular to the joint surface . Furthermore , even when the knots 20-1 of the grain material 12 penetrate through both the front and back surfaces, a compression-bonded grain material 10 without cracking or cracking can be obtained.

In addition, if there are knots and/or straight-grained parts inside the grained wood but are not exposed on the surface, and if their presence can be determined, it is better to avoid overlapping in the thickness direction, but if If it exists inside where it cannot be detected, the stress is dispersed by the grains on the outside, so cracks and cracks may be avoided.

Further, in this embodiment, the back sides of the wood are joined together, but regardless of this, the back side of the wood becomes softer when heated than the front side of the wood. can do.

In addition, the compression bonded board material 10 according to the present embodiment is produced by applying a thermosetting adhesive to the two board materials 12 and 14 and joining them together, and then applying the thermosetting adhesive during the subsequent heat compression process. is in a hardened form, but the knots and/or straight-grained portions of the two boards bite into the opposing boards, so it is possible for the two boards to be firmly joined without applying an adhesive.

<Manufacturing method of compression bonded board material>
FIG. 3 shows a flow of a method for manufacturing a compression bonded board material according to the present embodiment, and will be described in detail with reference to FIGS. 2, 4, and 5. FIG. 2 is a perspective view showing the two planks 12 and 14 immediately before the joining process. FIG. 4 is a longitudinal sectional view schematically showing a wood compression device used in the compression molding process. FIG. 5 is a schematic front view illustrating the heating compression process.

Grain material to be compressed and joined is prepared (step S10: grain material preparation step). This embodiment will be explained by taking as an example a case where two sheets of grain material as shown in FIG. 2 are joined. This process is a process of cutting the grained materials to be joined into a predetermined size, and at the same time checking the knots and straight-grained parts that exist in each. It is also preferable to confirm in this step whether existing knots and/or straight-grained portions can be joined without overlapping each other.

The size of the two grain materials was 119 mm x 275 mm x 28 mm, respectively. The thickness of each grain material is 28 mm, and the thickness of the grain material is preferably 10 mm or more and 50 mm or less. If the thickness is less than 10 mm, the stress acting on the knots and straight-grained portions may not be sufficiently absorbed, and there is a risk that cracks or cracks may occur in the grained material. Moreover, in the case of 50 mm or more, the wood compression device becomes large-scale, and the time required for the steaming or heating compression process becomes too long, which is not practical.

Next, after the grain material preparation step, each of the grain materials 12 and 14 is steamed (step S12: steaming treatment step). Steaming can be performed using, for example, a steamer. The steaming time can be, for example, 60° C. or higher and 150° C. or lower for about 30 minutes. This steaming process softens each grain material. In this state after softening, wood has a high compressive strength in the fiber direction in terms of knots, and the strength of the tree rings (winter part) in the straight-grained part is high, so the strength remains higher than that of the grain part. ing. On the other hand, the grain part is in an appropriate softened state.

Next, an adhesive is applied to the joint surfaces of the two planks to be joined (step S14: adhesive application step). Adhesives include water-based polymer isocyanate adhesives, vinyl acetate resin adhesives, urea resin-based adhesives, epoxy resin-based adhesives, phenolic resin-based adhesives, Various adhesives can be used, such as synthetic rubber adhesives. Both are thermosetting adhesives. Since the applied adhesive is cured during the heat compression process (step S18), the number of steps can be reduced compared to a method in which heat compression is performed after the adhesive is cured. In other words, compared to the case where adhesive is applied to two facing planks, the adhesive is cured, and then heated and compressed, it is possible to apply a thermosetting adhesive to the facing two planks. The work time can be shortened by carrying out the heat compression process without waiting for the coating on the grain materials 12 and 14 to harden.

After the adhesive application step, the two grain materials 12 and 14 are joined together at their grain surfaces (step S16: joining step). Note that the applied adhesive is not shown in FIG. The two grained materials 12 and 14 each have a wood surface 12a, 14a (the one closer to the outer skin of the tree) and a wood back surface 12b, 14b (the one closer to the core of the tree). The back sides are facing each other. Further, the upper grained material 12 has knots 20-1 and 20-2 as described above, and also has a straight-grained portion 22 as seen from the cross section. This straight-grained portion 22 is exposed on the joint surface .

However, if there is a knot in a part of the plank material 14 that is hidden in the drawing, make sure that the knot does not overlap with the node 20-2 of the plank material 12. A joining process is performed by moving the grain material 12 in the direction of the arrow, and a bonded grain material 17 (see FIG. 5) is obtained.

Next, a heating compression step (step S18) is performed. Before explaining this, the wood compression device 50 used in this process will be explained.

As shown in FIG. 4, the wood compression device 50 has a bottom portion 52a in which the joint board material 17 is placed, a box-shaped lower mold 52 with an open top surface, and a lower mold 52. It has a basic configuration including a compression mold 56 consisting of a plate-shaped upper mold 54 constituting the lid. The upper mold 54 is movable in the direction of coming into contact with and separating from the lower mold 52 (in the direction of arrow 150), and when it comes into contact with the lower mold 52, the compression mold 56 is in a closed state, and a sealed mold interior space 58 is formed. is configured. Note that an O-ring 53 is fitted into a groove provided at the upper edge of the lower mold 52, and when the O-ring 53 comes into close contact with the upper mold 54, the inner mold space 58 is sealed.

The upper mold 54 is provided with a pipe 62 through which steam 60 (described later) flows and a pipe 66 through which cooling water 64 (described later) flows, and the lower mold 52 is provided with a pipe 68 through which steam 60 flows and a cooling A conduit 70 through which water 64 flows is provided. Further, the lower mold 52 includes a pipe line 72 for introducing steam 60 into the mold inner space 58, a pipe line 74 for discharging the steam 60 from the mold inner space 58, and a pipe line 74 for discharging water in the mold inner space 58. A conduit 76 is provided for this purpose.

A steam line 78 is provided upstream of the upper mold 54 and the lower mold 52 for introducing steam 60 into the pipe line 62, the pipe line 68, and the pipe line 72. A steam path 80 is provided for discharging steam 60 from within conduit 62, conduit 68, and conduit 74.

Furthermore, a cooling water system line 82 is provided upstream of the upper mold 54 and the lower mold 52 for introducing the cooling water 64 into the pipe line 66 and the pipe line 70, and downstream of the upper mold 54 and the lower mold 52. The pipe 66, the pipe 70, and a drainage path 84 for discharging waste water from the pipe 76 are provided.

The steam path 78 upstream of the compression mold 56 is provided with valves 86 , 90 , and 88 that can open and close the paths, respectively, before reaching the pipes 62 , 72 , and 68 . 80 is provided with valves 92, 94, and 96, respectively, which can open and close the paths downstream of conduits 62, 74, and 68, respectively.

In addition, the cooling water path 82 upstream of the compression mold 56 is provided with valves 98 and 100 that can open and close the paths, respectively, before reaching the pipes 66 and 70. are provided with valves 102, 104 and 106 that can open and close the paths downstream of conduits 66, 76 and 70, respectively. Note that a pressure gauge 108 is provided between the valve 90 and the pipe line 72.

Hereinafter, the heating compression process according to this embodiment will be explained. The heat compression step (step S18) in this embodiment specifically includes a heat softening operation and a compression operation.

As shown in FIG. 5(a), the wood surface 14a of the board 14 is placed on the bottom 52a of the lower mold 52 of the compression mold 56 after being steamed, coated with adhesive, and bonded. They are placed so that they are in contact with each other. As described above, the grain material 12 and the grain material 14 are adjusted in the grain material preparation step (step S10) so that the knots and straight-grained portions do not overlap in the direction perpendicular to the joining surfaces.

Next, the upper mold 54 of the wood compression device 50 is moved in a direction closer to the lower mold 52, and the lower surface of the upper mold 54 is brought into contact with the upper wooden surface 12a of the grain material 12. In addition, in FIG. 5, the compression mold 56 is shown in a simplified manner so that the opened and closed states can be seen.

Then, with the upper mold 54 in contact with the wooden surface 12a of the plank material 12 and the lower mold 52 in contact with the wooden surface 14a of the plank material 14, steam 60 is sent into the upper mold 54 and the lower mold 52, The temperatures of the upper mold 54 and the lower mold 52 are gradually increased. The temperature is raised from around room temperature (approximately 15 to 20° C.) to approximately 110 to 130° C., and is maintained constant at that temperature (heat softening treatment operation).

To raise the temperature, the valves 92 and 96 downstream of the compression mold 56 are closed, and the valves 86 and 88 upstream of the compression mold 56 are gradually opened, and the high temperature steam 60 is gradually introduced into the upper mold 54 and the lower mold 52. This is done by (see Figure 4). The temperature can be kept constant by adjusting the opening amounts of the valves 86 and 88 that feed the steam 60 and the opening amounts of the valves 92 and 96 that discharge the steam 60. The heating and softening treatment of the grain material 12 and the grain material 14 by the wood compression device 50 is performed approximately 0 to 10 minutes after the start of temperature rise. Through the above processing, the grain material 12 and the grain material 14 of the joint grain material 17 are heated and softened.

After the wood compression device 50 heats and softens the grain material 12 and the grain material 14, as shown in FIG. The grain material 14 is compressed in the thickness direction, that is, in the direction in which the annual rings are stacked (compression processing operation). At this time, by sealing the valves 90, 94, and 104, the mold interior space 58 becomes a completely sealed space. In this state, the temperature of the upper mold 54 and the lower mold 52 is further raised to about 150° C. to 180° C., and the high temperature state is maintained for about 30 to 120 minutes from the start of heating.

Then, the pressure in the mold space increases due to the thermal expansion of the air in the mold space 58 and the generation of water vapor due to the evaporation of moisture in the grain material 12 and the grain material 14, and the pressure in the mold interior space increases, and the grain material compressed under this increased pressure. 12 and the grain material 14 will be treated with high-temperature steam. As a result, the stress accumulated inside the grain material 12 and the grain material 14 is significantly relaxed in a short time, and the compressed shape is fixed, and at the same time, the joint surface 16 of the grain material 12 and the grain material 14 is fixed. The applied adhesive is cured, and a compression bonded board material 10 is obtained. Here, in this embodiment, no steam is introduced into the mold interior space 58. However, if the amount of water vapor is insufficient due to the evaporation of water from the grain material 12 and the grain material 14, or if the pressure in the mold space 58 is low, the opening amount of the valve 90 is increased to increase the amount of steam and the pressure. can be increased. Conversely, if the pressure is high, the valve 94 may be slightly opened to reduce the pressure. Note that the pressure in the mold interior space 58 can be monitored by a pressure gauge 108.

In the compression treatment operation of the jointed grain material 17, the knots and straight grain portions existing in the grain material 12 remain stronger than the grain portions even after softening as described above, so they are not softened by the compression treatment. This will cut into the grain portion of the joined surface of the grained material 14. Similarly, the knots present in the grain material 14 will dig into the grain portions of the grain material 12 during the compression process. That is, it is flexibly received by the soft grain portion of the grain material 12. Therefore, whereas stress concentrated at knots and straight-grained parts would cause cracks and cracks in the grain material, stress concentrated at knots and straight-grained parts is now absorbed by the softened parts of the opposing grained material. Therefore, the occurrence of cracks and cracks can be prevented.

Here, the compression rate of the joint plate material 17 is determined by the thickness of the plate material 12 and the plate material 14 before compression, the height of the O-ring 53, and the flat metal plate that can be placed on the bottom 52a of the lower die 52. It can be adjusted by adjusting the thickness of the wood (not shown), and can be adjusted to a maximum of about 70% if the grain is made of coniferous wood. It should be noted that the compression rate of 70% means that the joint board material having a total thickness of 10 cm is compressed to a thickness of 3 cm.

Thereafter, the temperature of the upper die 54 and the lower die 52 is lowered to about 20 to 40°C, and maintained for 30 to 60 minutes to cool the compression bonded board material 10 (step 20: cooling treatment step, Figure 5(c)). Cooling is accomplished by closing the valves 86 and 88, opening the valves 92, 94, and 96 to exhaust the steam 60 from the upper mold 54, the lower mold 52, and the mold interior space 58, and opening the valves 98, 100, 102, and 106. This is done by flowing cooling water 64 into the upper mold 54 and lower mold 52. Thereafter, the upper mold 54 is moved in a direction away from the lower mold 52. In this way, the compression bonded board material 10 can be obtained.

According to the above-mentioned method for producing compression-jointed board material, the existing knots and/or straight-grained portions are arranged so that they do not overlap in the thickness direction with the knots and/or straight-grained portions of the board to be joined. During the heating and compression process, stress from the outside acting on the knots and/or straight-grained portions present in each grain material is absorbed by the opposing grained portion. Therefore, it is possible to prevent the occurrence of cracks and cracks due to concentration of stress in knots and straight-grained parts, and to obtain compression-bonded board material that is free from cracks and cracks even if the board has knots and straight-grained parts. be able to.

As a result, it is now possible to effectively utilize wood with a knotted grain or wood with a straight grain, which had previously been avoided as wood for compression, without having to be discarded. Material resource conservation is achieved.

Note that the present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the spirit of the invention. For example, the heat compression process is carried out using the wood compression device 50 and compression treatment after heat softening treatment, but the present invention is not limited to this. Any treatment that can heat and compress wood to fix it can be carried out using any device. For example, the material may be heated and softened by steam and high-frequency induction heating in a high-temperature, high-pressure container, and then compression molded to fix the compressed shape in a high-temperature, high-pressure atmosphere.

It is also possible to perform a drying set using a lithographic press or roll press, and then perform fixation treatments such as heat treatment, high-pressure steam treatment, high-frequency induction heating treatment, microwave heating treatment, chemical treatment, and resin impregnation treatment. be.

The grained materials used in the above-described embodiments are those in which the grained materials 12 and 14 have knots or straight-grained portions. In particular , it functions particularly effectively for wood grains that have knots that penetrate between the front and back surfaces. In other words, if there are knots penetrating between the front and back surfaces, cracks or cracks will occur during compression, so they are not used, but it is best to oppose the grained part of the board where there are no knots or straight-grained parts. This creates a path for utilization.

10 Compression bonded board material 12 Board material 12a Wood surface 12b Wood back surface 14 Board material 14a Wood surface 14b Wood back surface 16 Joint surface 17 Bonded board material 20 Knot 22 Straight grain portion 50 Wood compression device 58 Space inside compression mold

Claims (4)

In a compression bonded board material formed by joining at least two planks and heating and compressing them,
The at least two boards to be joined each have a knot and/or a straight grain part,
The at least two sheets of grain material are joined such that the grain surfaces thereof are joined to each other and the outermost surface thereof is the grain surface, and are bonded by being heated and compressed toward the joint surface. ,
Compression bonded board material, characterized in that knots and/or straight grain portions present in each of the at least two board materials are arranged so as not to overlap each other in the thickness direction perpendicular to the joint surface. In the method for manufacturing compression bonded grain material for producing the compression bonded grain material according to claim 1,
a joining step of joining at least two sheets of grained material each having knots and/or straight-grained portions to each other at the grain surface so that the outermost surface thereof is the grain surface;
a heating compression step of heating and compressing the joined board material in its thickness direction,
The joining of the grained materials in the joining step is performed by arranging the joints and/or the straight grain portions such that they do not overlap each other in the thickness direction perpendicular to the joining surface. A method for manufacturing jointed board materials. The joining of the planks in the joining step is such that when the knots and/or straight-grained portions are present on the surfaces of the planks to be joined, the knots and/or straight-grained portions are opposite to each other on the joining surface. 3. The method of manufacturing a compression bonded board material according to claim 2, wherein the method is carried out by arranging the compression bonding so as not to cause any damage. Before the heating and compression step, an adhesive application step is performed in which a thermosetting adhesive is applied to the joint surfaces of the two facing planks at the joint surface,
4. The method of manufacturing a compression bonded board material according to claim 2, wherein the thermosetting adhesive is cured during the subsequent heating and compression step.

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