Joint member and method for manufacturing the same

Abstract

To provide a joint member obtained by strongly joining a wooden material with a non-wooden material.SOLUTION: There is provided a joint member obtained by joining and integrating a wooden material with a non-wooden material whose surface comprises a recess and / or a protrusion. The wooden material that enters an inside of the recess or a periphery of the protrusion of the non-wooden material is filled therein without destroying cell walls of wooden fiber cells in a state in which the mutual positional relation between the wooden fiber cells is changed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a joint member in which a wood-based material and a non-wood-based material are joined together to form an integrated member, and to a method for manufacturing the joint member. [Background technology]

[0002] When manufacturing components by joining wood-based materials such as wood or bamboo with non-wood-based materials such as metal, the joining methods can include mechanical methods that use fastening parts such as bolts, chemical methods that use adhesives, and composite methods that combine these. These joining methods are used appropriately depending on the application, the environment, and economics.

[0003] Meanwhile, the present inventors' group has discovered a phenomenon in which swollen wood material is softened by applying heat and pressure to it, causing it to plastically flow, and has proposed a technique related to the molding of wood-based materials that utilizes this plastic flow (e.g., Patent Documents 1-3). This type of flow molding technique for wood-based materials can cause a larger amount of deformation, because it causes deformation by changing the position due to the sliding (flow) phenomenon between wood cells, compared to a method such as compression processing, which causes shape changes by densifying the material through the blocking of the internal cavities of wood cells. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication WO2018 / 096820 [Patent Document 2] JP 2018-196946 A [Patent Document 3] JP 2019-188648 A [Patent Document 4] International Publication WO2019 / 004315 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of conventional joining methods, the strength of the wood-based material at the joint between wood-based and non-wood-based materials is the rate-limiting factor for the joint strength, so problems arise in that the joint strength cannot exceed the material strength of the wood-based material, and that the effort and cost required for adhesion, bolt fastening, etc. Another problem is that the initial fastening force and adhesive force gradually decrease due to dimensional changes caused by swelling and shrinkage of the wood-based material, stress relaxation, creep, etc., and the joint strength of the members decreases.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a joint member in which a wood-based material and a non-wood-based material are firmly joined by utilizing knowledge of flow molding technology for wood-based materials. Another aim of the present invention is to provide a method for manufacturing such a joint member that requires less labor and cost than conventional methods. [Means for solving the problem]

[0007] In order to solve the above problems, the joining member of the present invention is a joining member in which a wood-based material and a non-wood-based material having a concave portion and / or a convex portion on a surface are joined and integrated, The wood-based material is characterized in that the relative positions of wood fiber cells are changed as they penetrate into and fill the recesses or the periphery of the protrusions of the non-wood-based material.

[0008] The building materials, automobile materials, furniture, daily necessities, and electrical appliance materials of the present invention are characterized by including the above-mentioned joining member.

[0009] The method for producing a joint member of the present invention includes the following steps: A first step of inserting a wood-based material into a mold in which a non-wood-based material having a concave and / or convex portion on a surface thereof has been placed; and A second step of heating the mold to heat and soften the wood-based material and pressurizing the wood-based material to cause it to plastically flow. Including, The second process is characterized in that the wood-based material penetrates and fills the recesses or the protrusions of the non-wood-based material through plastic flow, thereby bonding and integrating the wood-based material and the non-wood-based material. Effect of the Invention

[0010] The joining member of the present invention joins wood-based and non-wood-based materials by the plastically flowed wood-based material penetrating into the recesses or around the protrusions on the surface of the non-wood-based material, and has excellent joining strength and stability of dimensions and physical properties.

[0011] The manufacturing method of the joining member of the present invention is a method similar to insert molding in general resin molding, and can produce a joining member between wood-based materials and non-wood-based materials in a single processing step, thereby reducing the effort and cost required for bonding, bolting, etc., which are involved in conventional methods of joining wood-based materials. [Brief description of the drawings]

[0012] [Figure 1] 1A to 1C are schematic diagrams illustrating cross sections of a bonded member illustrating one embodiment of a method for producing a bonded member of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing a cross section of a member joined by nailing. [Diagram 3] 3 is a cross-sectional photograph of a joint member of Example 1 and Comparative Example 1. [Figure 4] 4 is an enlarged photograph of a joint portion of the joint members of Example 1 and Comparative Example 1. [Diagram 5] 3 is a micrograph of a joint between the joint members of Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, one embodiment of the joining member of the present invention will be described.

[0014] In the joining member of the present invention, a wood-based material and a non-wood-based material are joined and integrated. In the joining member of the present invention, the wood-based material is filled into the recesses or around the protrusions on the surface of the non-wood-based material with the cell walls of the wood fiber cells hardly destroyed and with the relative positions of the wood fiber cells changed. The filled wood fiber cells are compacted (densified) by deformation of the cell walls.

[0015] The wood-based material is not particularly limited, but examples thereof include wood, bamboo, veneer, chips, wood flour, wood fiber, bamboo fiber, hemp fiber, kenaf fiber, etc. In order to strengthen the joint with a non-wood-based material, it is effective to use a wood-based material in which wood fiber cells having excellent strength properties are not divided, and in this case, the length of the wood-based material in the fiber direction is preferably 5 mm or more.

[0016] The wood-based material also contains water, the weight of which is 1 to 200% and preferably 1 to 30% based on the dry weight of the wood-based material.

[0017] Furthermore, the wood-based material used may be one impregnated with resin (hereinafter, a wood-based material impregnated with resin may be referred to as a "wood-based composite material"). In this case, the weight of the resin contained in the wood-based composite material is preferably 1 to 60% of the total weight of the wood-based composite material, and more preferably 20 to 60%.

[0018] As the resin, a thermosetting resin or a thermoplastic resin can be appropriately used which improves the fluidity of the wood-based material and also functions as an adhesive for the non-wood-based material to be joined.

[0019] Examples of the thermosetting resin include one or more of various resins such as phenol, epoxy, unsaturated polyester, urea, melamine, diallyl phthalate, silicon, vinyl ester, polyimide, polyurethane, etc. The resin may also contain additives such as a curing agent.

[0020] Examples of thermoplastic resins include one or more of various resins such as polyolefins such as acrylic, polyethylene, and polypropylene, cyclic polyolefins, polystyrene, esters such as phthalic acid esters, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polytetrafluoroethylene, polyamides such as ABS, AS, and nylon, polyacetal, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, polysulfone, polyethersulfone, amorphous polyarylate, liquid crystal polymer, polyether ether ketone, polyimide, and polyamideimide.

[0021] The non-wood-based material is not particularly limited, but examples thereof include inorganic materials, organic materials, and composite materials thereof.

[0022] Examples of inorganic materials include metals, ceramics, glass, carbon, minerals, various inorganic compounds, and the like.

[0023] Examples of organic materials include natural and artificial materials such as plastics, rubber, paper, cotton, and various organic compounds.

[0024] Furthermore, the surface of the non-wood-based material may be coated with various coating agents such as paints and adhesives.

[0025] The hardness and strength of the non-wood-based material are not particularly limited, but may be appropriately selected so as not to deform or break under the pressure applied during joining. In addition, the non-wood-based material is preferably harder than the wood-based material or wood-based composite material during plastic flow, which will be described later.

[0026] The size and shape of the non-wood-based material are not particularly limited, but the surface has at least one of a concave portion and a convex portion. One or more concave portions or convex portions may be formed. Here, the concave portions of the non-wood-based material include various shapes such as grooves, gaps, notches, depressions, and holes, and the convex portions of the non-wood-based material include various shapes such as protrusions, steps, and convex stripes. More specifically, for example, in the case of the concave portions, the depth can be 0.05 to 100 mm, and the diameter or width can be 0.1 to 100 mm, preferably the depth can be 0.1 to 10 mm, and the diameter or width can be 1 to 10 mm. For example, in the case of the convex portions, the height can be 0.05 to 100 mm, and the diameter or width can be 0.1 to 100 mm, preferably the height can be 0.1 to 10 mm, and the diameter or width can be 1 to 10 mm.

[0027] When the depth and width of the recesses and the height and width of the protrusions are within these ranges, as described below, wood fiber cells of the plastically fluidized wood-based material can easily penetrate into the recesses and around the protrusions of the non-wood-based material, thereby increasing the bonding strength between the wood-based material and the non-wood-based material.

[0028] Furthermore, wood-based materials may be subjected to various modification treatments for the purpose of improving, for example, fire resistance, durability, weather resistance, dimensional stability, moldability, etc. Specifically, examples of chemical modification treatments include treatments with known esterifying agents and etherifying agents, and the esterification treatment proposed by the present inventors and the manufacturing method for modified wood (Patent Document 4) may also be considered.

[0029] The bonding member of the present invention has excellent bonding strength and stability of dimensions and physical properties, and can therefore be used, for example, as building materials, automobile materials, furniture, daily necessities, and electrical appliance materials.

[0030] Next, an embodiment of the method for producing a bonded member of the present invention will be described. Fig. 1 is a schematic diagram showing a cross section of a bonded member illustrating an embodiment of the method for producing a bonded member of the present invention. Descriptions common to those described for the bonded member of the present invention will be omitted.

[0031] The method for producing a joining member of the present invention includes the steps of: A first step of inserting a wood-based material into a mold in which a non-wood-based material having a concave and / or convex portion on a surface is placed; and A second step of heating the mold to heat and soften the wood-based material and pressurizing the wood-based material to cause it to plastically flow. Contains:

[0032] Each step will be described below.

[0033] In the first step, the wood-based material is poured into a mold in which a non-wood-based material has been placed. The mold is not particularly limited, and a mold used for insert molding in general resin molding can be used. The non-wood-based material can be fixed in the mold in advance, and the wood-based material is poured into the mold.

[0034] In the second step, the die is heated to heat and soften the wood-based material, and pressure is applied to the wood-based material to cause it to plastically flow.

[0035] In this second step, the swollen wood material, which is an aggregate structure in which fibrous cells are aligned in a specific direction, is heated to soften it, and pressure is applied, utilizing the phenomenon in which plastic flow occurs while generally maintaining the cellular structure. In the second step, the plastic flow causes the wood material to penetrate and fill the recesses or protrusions of the non-wood material, joining and integrating the wood and non-wood materials.

[0036] In the present invention, "plastic flow" refers to a state in which wood fiber cells of wood-based materials change position relative to each other with almost no destruction of the cell walls that the cells originally have, and the deformation remains even after the external force is removed. For example, as shown in Figure 2, when a nail is driven into a wood-based material, the cell walls of the wood fiber cells at the contact surface between the nail and the wood-based material are destroyed, causing cell deformation and destruction, but the relative positions of the wood fiber cells do not change.

[0037] In the embodiment shown in FIG. 1, the metal mold is heated and the wood-based material is pressed from above with a die (punch), thereby heating and pressurizing the wood-based material.

[0038] The heating temperature of the mold is set to a temperature range in which the wood-based material to be charged is softened and then hardened, and is lower than the thermal decomposition temperature of the wood-based material. Specifically, the heating temperature of the mold is preferably 20 to 200°C, and more preferably 100 to 180°C. Moreover, these temperature ranges may be set in one step, or the set temperatures for softening and hardening the wood-based material may be changed in steps. In order to shorten the molding time, a relatively high temperature setting (150 It is also possible to carry out the heating at a temperature of up to 180°C.

[0039] The pressure applied when the mold is heated can be in the range of 1 to 600 MPa. In order to sufficiently plastically flow the wood-based material, the pressure can be preferably in the range of 5 to 600 MPa. The upper limit of the pressure can be set within a range in which the non-wood-based material to be joined is not deformed.

[0040] In addition, the time for which the pressure load is maintained (pressurization time) must be long enough to allow the wood-based material to fully harden. For example, when the wood-based material is impregnated with a thermosetting resin, it is desirable to allow the resin to fully harden at the heating temperature. Although this depends on the resin used, a range of 10 seconds to 30 minutes can be exemplified. In addition, when the wood-based material is impregnated with a thermoplastic resin, it is desirable to allow the resin to harden by cooling. Although this depends on the cooling speed of the mold, a range of 10 seconds to 60 minutes can be exemplified.

[0041] As shown in Fig. 1, in the method for producing a joint member of the present invention, wood fiber cells with excellent strength properties penetrate into the recesses or around the protrusions of the non-wood-based material, thereby obtaining a joint member with a strongly reinforced joint. In addition, by randomly orienting the wood fiber cells that penetrate into the recesses or around the protrusions of the non-wood-based material, the anisotropy of the material strength of the wood-based material can be eliminated, and the mechanical anisotropy at the joint can be eliminated. By firmly adhering the wood-based material and the non-wood-based material and increasing the material strength and dimensional stability of the wood-based material or wood-based composite material in the vicinity of the adhesive portion, a joint member with higher joint strength and less susceptible to environmental changes can be provided.

[0042] The method for manufacturing the joint member of the present invention is similar to insert molding in general resin molding, and can produce a joint member between wood-based materials and non-wood-based materials in a single processing step, thereby reducing the labor and cost required for bonding, bolting, etc., which are required in conventional methods for joining wood-based materials.

[0043] The joint member and the method for manufacturing the joint member of the present invention are not limited to the above-described embodiment. EXAMPLES

[0044] The bonded member of the present invention and the method for producing the same will be described below with reference to examples. However, the bonded member of the present invention and the method for producing the same are not limited to the following examples.

[0045] <1> Manufacturing of joining materials The wood-based composite material used was a cedar veneer impregnated with phenolic resin.

[0046] The cedar veneer was impregnated with water-soluble phenolic resin (solid concentration 30%) by reducing pressure and applying pressure, and then dried in air at 35°C or less. As a result, a wood-based composite material was produced that contained 50% resin by weight relative to the total weight of the cedar veneer.

[0047] The non-wood-based material to be joined was a brass fitting (vertical knurled cap nut M10, length 22 mm, diameter 13 mm) with a groove on the surface that is a maximum of 0.5 mm deep and 3 mm wide.

[0048] Then, the non-wood-based material was fixed in advance inside a mold (retainer), and the wood-based composite material was layered and placed between the molds. While the mold was heated from the outside to approximately 160°C, the materials were integrated by applying pressure of 135 MPa with a uniaxial press for 12 minutes to form a door handle-shaped joining member (Example 1).

[0049] <2> Observation of the axial cross section of the joint Figure 3 shows the above. <1> FIG. 3(b) shows a photograph of an axial cross section of the joining member of Example 1 produced by the conventional joining method (adhesive). FIG. 3(a) shows a photograph of an axial cross section of a conventional door handle (wooden molded product) produced by a conventional joining method (adhesive) as Comparative Example 1. The door handle of Comparative Example 1 was produced by cutting a piece of solid wood (beech) not impregnated with resin into the outer shape of a door handle, applying a surface coating, cutting a pilot hole of 13 mm in diameter and 50 mm deep in the direction of the wood grain, and inserting a non-wood-based material coated with epoxy resin into this hole.

[0050] FIG. 4 shows enlarged photographs of the joints of the joint members of Comparative Example 1 and Example 1.

[0051] In Comparative Example 1 (Figure 4(a)), only adhesive penetrates into the grooves of the non-wood material, and the wood and non-wood material are joined via the adhesive, whereas in Example 1 (Figure 4(b)), it was confirmed that the wood composite material penetrates into the grooves of the non-wood material and is integrated.

[0052] FIG. 5 shows a further enlarged micrograph of the joints of the joint members of Comparative Example 1 and Example 1.

[0053] In Comparative Example 1 (Fig. 5(a)(c)), only the adhesive penetrated into the grooves of the non-wood-based material (brass), and no wood cell fibers penetrated. Furthermore, even on the surface of the non-wood-based material other than the grooves, the wood cell fibers and the non-wood-based material were not in direct contact with each other, but were bonded via a layer of adhesive (Fig. 5(c)).

[0054] On the other hand, in Example 1 (FIGS. 5(b)(d)), wood fiber cells had infiltrated into the grooves of the non-wood material and were integrated with the surface of the non-wood material. The wood fiber cells were shaped by changing the relative positions of the cells while maintaining their original cell wall structure. Furthermore, it was confirmed that the internal cavities of the wood fiber cells were blocked or filled with the impregnating resin, increasing the density.

[0055] <3> Pull-out test of joint members the above <1> A pull-out test was conducted on the joined non-wood-based materials using the wooden handle (wood molded product) of the comparative example and the door handle (wood flow molded product) of Example 1 produced in the above. The test machine used was an Autograph AG 5kN (manufactured by Shimadzu Corporation). A bolt (M10) was inserted into an insert nut on the brass metal fitting of the non-wood-based material and fixed to the base of the test machine, and the head of the handle was pulled at 5 mm / min. The load (pull-out load) when the brass fitting was pulled out was measured as an index of the pull-out strength.

[0056] The results are shown in Table 1.

[0057] [Table 1]

[0058] These results confirmed that the joining member of Example 1 had a pull-out load (i.e., pull-out strength) that was more than 10 times higher than that of the joining member using conventional adhesives (Comparative Example 1), and had excellent joining strength between wood-based composite materials and non-wood-based materials.

[0059] Similarly, a conventional joint member using wood screws (Comparative Example 2) and a joint member using nailing (Comparative Example 3) were prepared, and a pull-out test was conducted on the jointed non-wood-based materials. The joint member using wood screws in Comparative Example 2 was prepared by cutting a pilot hole with a diameter of 3 mm and a depth of 12.5 mm in a solid wood (beech) not impregnated with resin in the direction of the wood grain, and screwing a wood screw with a nominal diameter of 4.5 mm and a length of 38 mm to a depth of 25 mm into the hole. The joint member using nailing in Comparative Example 3 was prepared by driving a nail with a thickness of 2.8 mm and a length of 50 mm to a depth of 27 mm into a solid wood (beech) not impregnated with resin, without drilling a pilot hole, in the direction of the grain. The test machine used was an Autograph AG-X plus 20kN (manufactured by Shimadzu Corporation). It was confirmed that the joint member in Example 1 had a significantly improved joint strength between the wood-based composite material and the non-wood-based material compared to the joint members in Comparative Examples 2 and 3.

[0060] The reasons why the joining member of Example 1 has excellent joining strength are thought to be that in addition to the effect of the strong cell walls of the wood fiber cells being hardly destroyed and penetrating into and filling the recesses or around the protrusions on the surface of the non-wood-based material, the mechanical strength of the cell walls themselves is strengthened by the hardening of the resin impregnated into the wood fiber cells, and further, the filled wood fiber cells are consolidated (densified) by deformation of the cell walls. [Industrial Applicability]

[0061] The joining member of the present invention has a higher joining strength than conventional joining members between wood-based materials and non-wood-based materials, and can be used, for example, as non-structural or structural members for buildings. In addition, since the joining member can be molded into a wide variety of shapes at the same time as joining, it can be used in a wide range of applications, such as automotive members such as interior panels, home appliance members such as housings for electrical appliances, structural members such as building materials, furniture, and daily necessities.

Claims

1. A joining member in which a non-wood-based member having a columnar shape and a recess on its side peripheral surface is included inside a wood-based member, and the non-wood-based member and the wood-based member are joined and integrated by fitting together at the recess, The wood-based component has a joint portion which fills the inside of the recess of the non-wood-based component and is deformed by plastic flow so as to change the relative positions of the wood fiber cells due to sliding between the wood fiber cells without destroying the cell walls of the wood fiber cells, thereby allowing the wood fiber cells to enter the inside of the recess of the non-wood-based component and thereby increasing material strength.

2. 2. The joint member according to claim 1, wherein the wood fiber cells are densified at the joint.

3. 3. The joint member according to claim 2, wherein the joint portion has a material strength higher than other portions of the wood-based members other than the joint portion.

4. 4. The joining member according to claim 1, wherein the wood-based members are impregnated with a thermosetting resin or a thermoplastic resin.

5. A method for manufacturing a joint member in which a non-wood-based member having a columnar shape and a recess on a side peripheral surface is included inside a wood-based member, and the non-wood-based member and the wood-based member are joined and integrated by fitting the recess, A first step of inserting the wood-based component into a bag-shaped mold having an opening, in which the non-wood-based component is placed with the axis of the column facing the opening; a second step of heating the die to heat the wood-based component and soften it with water contained in the swollen wood-based component, and pressurizing the wood-based component through the opening along the axis to fill the interior of the die and cause it to plastically flow into the recess of the non-wood-based component, a second step of pressing the wood-based component so as to fill the inside of the recess in the non-wood-based component and to cause the wood fiber cells to plastically flow and deform so as to enter the recess in the non-wood-based component by changing the relative positions of the wood fiber cells due to sliding between the wood fiber cells without destroying the cell walls of the wood fiber cells, thereby providing a joint with increased material strength.

6. 6. The method for manufacturing a joint member according to claim 5, wherein the wood fiber cells are densified at the joint portion.

7. 7. The method for manufacturing a joint member according to claim 5, wherein the first step includes a step of impregnating the wood-based members with resin before the wood-based members are placed in the mold.

8. 6. The method for manufacturing a joint member according to claim 5, wherein the non-wood-based member is made of a material that is not deformed or destroyed by the pressure applied in the second step.

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