Method for manufacturing plant fiber-containing resin boards

Abstract

This invention provides a method for manufacturing plant fiber-containing resin boards that allows for easy recycling of unwanted scraps and has a high material yield. [Solution] A method for manufacturing a plant fiber-containing resin board, comprising: a web forming step of mixing and depositing plant fibers and thermoplastic resin fibers to form a web 10L; a restraining step of restraining a portion of the web 10L to a predetermined shape; a molded web forming step of removing at least a portion of the unrestrained portion of the web 10L to form a molded web 10M of the predetermined shape; and a heat press molding step of heat press molding the molded web 10M.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a method for manufacturing a plant fiber-containing resin board.

Background Art

[0002] Conventionally, as a method for manufacturing a board member using plant fibers, for example, the method described in Patent Document 1 is known. According to Patent Document 1, PP resin fibers spun from PP resin and kenaf fibers opened from kenaf are put into a mixer, formed into a mat shape by a former, and then hot-pressed into a predetermined thickness by a press machine, and cut into a desired raw fabric size by a cutting machine to obtain a fiber board for thermoforming. Then, the obtained fiber board for thermoforming is heated by a heater, and then the fiber board for thermoforming is set in the upper and lower molds for cold press forming, and the upper and lower molds for cold press forming are clamped to form an interior base material having a desired curved surface shape. When forming PP resin fibers and kenaf fibers into a mat shape by a former, in order to maintain the shape of the mat, the fibers are usually entangled with each other using a needle punch or the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The manufacturing method described above generates a large amount of scrap material when the interior base material is finally press-molded. Therefore, there is a demand for higher material yield. Recycling the resulting scrap material is one way to increase material yield, but recycling is not easy because the plant fibers in the scrap material are bound together with thermoplastic resins such as PP. In addition, when obtaining recycled material, the scrap material is finely crushed, which shortens the length of the plant fibers in the recycled material, resulting in a loss of the original strength.

[0005] The technology disclosed herein was developed based on the circumstances described above, and aims to provide a method for manufacturing plant fiber-containing resin boards that allows for easy recycling of unwanted scraps and has a high material yield. [Means for solving the problem]

[0006] To solve the above problems, the method for manufacturing a plant fiber-containing resin board disclosed herein includes a web forming step of mixing and depositing plant fibers and thermoplastic resin fibers to form a web; a restraining step of restraining a part of the web to a predetermined shape; a molded web forming step of removing at least a part of the unrestrained portion of the web to form a molded web of the predetermined shape; and a heat press molding step of heat press molding the molded web.

[0007] According to the above manufacturing method, by forming a molded web by constraining a portion of the web to a shape close to that of the finished plant fiber-containing resin board, the amount of scrap material generated during the subsequent heat press molding can be reduced. Furthermore, the plant fibers and thermoplastic resin fibers contained in the portion (scrap material) removed in the molded web formation process are the same plant fibers and thermoplastic resin fibers as they were before being deposited in the web formation process, so they maintain their original properties such as fiber length, and thus the scrap material can be recycled directly in the web formation process. Moreover, since the fibers are not entangled, they can be easily untangled, and no special equipment for entangled fibers is required, thus preventing an increase in manufacturing costs.

[0008] In this way, scrap materials generated during the web forming process can be easily recycled, improving material yield compared to conventional methods.

[0009] In the restraining step, a portion of the web may be restrained by applying a pressing jig of a predetermined shape, and in the web forming step, the portion not restrained by the pressing jig may be removed.

[0010] Furthermore, in the restraining step, a portion of the web may be restrained while being compressed into the predetermined shape. With such a manufacturing method, the fibers in the web in the portion restrained (compressed) by the pressing jig become less likely to move, so in the molded web forming step performed after the restraining step, the restrained (compressed) portion becomes less likely to be removed.

[0011] In the aforementioned web forming process, any portion not restrained by the pressing jig may be removed by suction.

[0012] In the aforementioned web forming process, the portion not restrained by the pressing jig may be removed by holding it and tearing it away from the portion restrained by the pressing jig.

[0013] In the aforementioned web forming process, any portion not restrained by the pressing jig may be removed by cutting.

[0014] A welding step may be included between the molded web forming step and the heat press forming step, in which a portion of the molded web is welded. With such a manufacturing method, the shape of the molded web is stabilized, improving operability when moving or transporting the molded web. In addition, peeling, distortion, and tearing are less likely to occur during the heat press forming step.

[0015] In the molded web forming step, a portion of the unconstrained part of the web may be left partially intact to form a basis distribution of the plant fibers and thermoplastic resin fibers within the surface of the molded web.

[0016] In steps other than the aforementioned heat press molding process, the web may be sucked from the base portion on which it is placed. With such a manufacturing method, the web, which is in a state of being easily crumbled, can be stably held on the base portion.

[0017] Furthermore, the web removed in the web forming process may be reused as a raw material for the web in the web forming process. [Effects of the Invention]

[0018] The technology disclosed herein provides a method for manufacturing plant fiber-containing resin boards that allows for easy recycling of unwanted scraps and has a high material yield. [Brief explanation of the drawing]

[0019] [Figure 1] An explanatory diagram illustrating the flow of the manufacturing method for the trim board of Embodiment 1 (web formation process to molded web formation process). [Figure 2] Perspective view showing the restraint process (before restraint) [Figure 3] Perspective view showing the restraint process (after restraint) [Figure 4] Cross-sectional view showing the restraining process (after restraint) [Figure 5] Cross-sectional view showing the formed web forming process (before suction) [Figure 6] Cross-sectional view showing the formed web forming process (after suction) [Figure 7] Cross-sectional view showing the formed web forming process (after restraint release) [Figure 8] Perspective view showing the welding process (after welding) [Figure 9] Cross-sectional view showing the welding process (before welding) [Figure 10] Cross-sectional view showing the welding process (during welding) [Figure 11] Cross-sectional view showing the welding process (after welding) [Figure 12] Explanatory drawing for explaining the flow of the method for manufacturing a trim board (welding process to trim board forming process) [Figure 13] Cross-sectional view of the trim board of Embodiment 2 [Figure 14] Cross-sectional view showing the formed web forming process (before suction) [Figure 15] Cross-sectional view showing the formed web forming process (after suction) [Figure 16] Cross-sectional view showing the formed web forming process (after restraint release) [Figure 17] Cross-sectional view showing the formed web forming process (before suction) of another embodiment [Figure 18] Cross-sectional view showing the formed web forming process (before removal) of another embodiment [Figure 19] Cross-sectional view showing the formed web forming process (after removal) [Figure 20] Cross-sectional view showing the formed web forming process (before cutting) of another embodiment [Figure 21] Cross-sectional view showing the formed web forming process (after cutting) [Figure 22] Cross-sectional view showing the formed web forming process (before cutting) of another embodiment [Figure 23] Cross-sectional view showing the formed web forming process (after cutting) [Figure 24] Perspective view showing the welding process (after welding) of another embodiment [Modes for carrying out the invention]

[0020] <Embodiment 1> Embodiment 1 will be explained with reference to Figures 1 to 12. This embodiment describes a method for manufacturing a trim board (an example of a plant fiber-containing resin board) 10 that constitutes the door trim of an automobile (vehicle) door.

[0021] The trim board 10 is composed of plant fibers and thermoplastic resin. Specifically, the trim board 10 is constructed in which the plant fibers are bonded together by the thermoplastic resin. Therefore, the trim board 10 is a lightweight material while maintaining a predetermined rigidity.

[0022] Plant fibers are fibers derived from plants. Examples of plant fibers include fibers obtained from various plant bodies such as kenaf, flax, hemp, jute, Manila hemp, sisal, ganpi, mitsumata, kozo, banana, pineapple, coconut, corn, sugarcane, bagasse, palm, papyrus, reed, esparto, survivalgrass, wheat, rice, bamboo, various coniferous trees (such as cedar and cypress), broad-leaved trees, and cotton. The part of the plant body used as plant fiber is not particularly limited; as long as fibers can be extracted, any part of the plant body, including non-woody parts, stems, roots, leaves, and woody parts, may be used.

[0023] Furthermore, kenaf fiber is preferred as the plant fiber. Kenaf is an extremely fast-growing annual plant and has excellent carbon dioxide absorption capabilities, thus contributing to the reduction of carbon dioxide in the atmosphere and the effective use of forest resources. In addition, bast plant fibers such as kenaf are preferable in terms of weight reduction because the fibers themselves contain voids. In this embodiment, kenaf fiber with an average fiber diameter of 80 μm to 100 μm is used as the plant fiber.

[0024] On the other hand, the thermoplastic resin constituting the trim board 10 mainly functions as a binder resin, and various thermoplastic resins can be used. Examples of thermoplastic resins include polyolefin resins, polyester resins, polystyrene, acrylic resins (resins obtained using methacrylate and / or acrylate, etc.), polyamide resins, polycarbonate resins, polyacetal resins, and ABS resins. Among these, polyolefin resins include polypropylene, polyethylene, ethylene-propylene copolymers (ethylene-propylene block copolymers, ethylene-propylene random copolymers), etc. Examples of polyester resins include aliphatic polyester resins such as polylactic acid, polycaprolactone, and polybutylene succinate, as well as aromatic polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate. Only one of these thermoplastic resins may be used, or two or more may be used in combination. In this embodiment, polypropylene is used as the thermoplastic resin.

[0025] Next, the manufacturing method of the trim board 10 of this embodiment will be described. The trim board 10 is manufactured by sequentially performing the following steps: web formation step, restraint step, molded web formation step, welding step, pre-board formation step (an example of a heated press molding step), and trim board molding step (an example of a heated press molding step). Each step will be described in detail below. Figures 1 and 12 are explanatory diagrams illustrating the flow of each step.

[0026] <Web Formation Process> First, a web 10L is formed by depositing a mixed fiber 11, which is a mixture of kenaf fiber (plant fiber) and polypropylene fiber (PP fiber, thermoplastic resin fiber). The web 10L is manufactured using a web manufacturing apparatus 20.

[0027] As shown in Figure 1, the web manufacturing apparatus 20 is configured to include a fiber supply unit 21, a feed conveyor 22, a fiber opening cylinder 23, a conveyor (an example of a base unit) 26, and a suction device 27.

[0028] The mixed fibers 11 of kenaf fibers and PP fibers, which are fed into the fiber supply unit 21 and mixed, are supplied to the fiber opening cylinder 23 by the feed conveyor 22. The fiber opening cylinder 23 has a cylindrical cylinder body 23A with multiple protrusions 23B on its surface (outer surface) and rotates clockwise in Figure 1 around the central axis L1. The rotating fiber opening cylinder 23 is capable of opening the mixed fibers 11 sent from the feed conveyor 22 by scratching them with the protrusions 23B. As the fiber opening cylinder 23 rotates, the mixed fibers 11 are caught on the surface (protrusions 23B) of the fiber opening cylinder 23 and transported upward, and then released into the air by the centrifugal force caused by the rotation of the fiber opening cylinder 23. In Figure 1, the direction of rotation of the fiber opening cylinder 23 is indicated by the arrow A1.

[0029] A walker roller 24 and a stripper roller 25 are provided on the outer circumference of the fiber-opening cylinder 23, and multiple protrusions are formed on each of their surfaces. The walker roller 24 has the function of opening the mixed fibers 11 by passing them between itself and the fiber-opening cylinder 23, and the stripper roller 25 has the function of peeling off the mixed fibers 11 that are attached to the surface of the walker roller 24.

[0030] The conveyor 26 is a mesh conveyor with a mesh-like structure, and it is possible to deposit the mixed fibers 11 on its upper surface. A suction device 27 is located below the conveyor 26, and by sucking in air, the mixed fibers 11 can be sucked onto the upper surface of the conveyor 26. The conveyor 26 forms a web 10L by transporting the layer of mixed fibers 11 to the right side of Figure 1 while depositing the mixed fibers 11 on its upper surface. The direction of transport of the mixed fibers 11 (web 10L) by the conveyor 26 is indicated by arrow A2.

[0031] <Restraint process and molded web formation process> Next, the obtained web 10L is constrained into a predetermined shape (constraining step) and the unconstrained portions are removed (molded web formation step). The area within the dotted rectangle in Figure 1 shows the constraint step and the molded web formation step, Figures 2 to 4 show specific examples of the constraint step, and Figures 5 to 7 show specific examples of the molded web formation step.

[0032] As shown in Figures 2 to 4, the pressing jig 31 is brought close to the web 10L, which is being sucked onto the upper surface of the conveyor 26, and a portion of the web 10L is restrained by pressing it with a predetermined pressing force. The pressing jig 31 has a flat, plate-shaped main body 32 that is slightly larger than the product shape of the trim board 10, and has a plurality of protrusions 33 on the lower surface of the main body 32. These protrusions 33 pierce the web 10L, thereby restraining a portion of the web 10L into a predetermined planar shape. At this time, as shown in Figure 4, the pressing force of the pressing jig 31 is set to compress the web 10L.

[0033] The conveyor 26 is continuous with the web manufacturing apparatus 20, and a suction device 27 is positioned below the conveyor 26, similar to the web manufacturing apparatus 20. It is preferable that the suction by the suction device 27 in this restraining process is within the same range as the restraining range of the pressing jig 31 (see Figure 4).

[0034] As shown in Figures 3 and 4, once a predetermined area of ​​the web 10L is restrained by the pressing jig 31, a suction machine 34 is brought close from the side of the pressing jig 31, and the unrestrained outer peripheral portion of the web 10L is sucked up by the suction machine 34 (see Figure 5, molded web formation process). At this time, the portion of the web 10L that is restrained by the pressing jig 31 remains on the conveyor 26 without being sucked up (see Figure 6). Subsequently, when the suction machine 34 and the pressing jig 31 are retracted and the pressing state is released, a molded web 10M of a predetermined shape is obtained, in which the portion that was restrained by the pressing jig 31 remains on the conveyor 26 and the bulge returns to its original state (see Figure 7).

[0035] Furthermore, the scraps 10E1 of the molded web 10M removed during this molded web formation process are recovered for recycling (see Figure 1). These scraps 10E1 of the molded web 10M are the mixed fibers 11 themselves, and their fiber length remains the same. Also, since they are not entangled, they can be directly fed into the fiber supply unit 21 for reuse.

[0036] <Welding process> Next, a portion of the molded web 10M obtained in the molded web formation process is welded to prevent the shape of the molded web 10M from collapsing. Figures 8 to 11 show examples of spot welding performed at multiple locations in the thickness direction of the molded web 10M using a cylindrical horn 40 across the entire molded web 10M. Hereinafter, the molded web 10M after welding will be referred to as the welded molded web 10W. Figure 11 shows an example of the welded molded web 10W, where the portion other than the welded part 12 is in a state where unmelted mixed fibers 11 are laminated.

[0037] In this way, by welding a portion of the molded web 10M, the welded molded web 10W becomes less prone to collapse, and the operability when moving or transporting the molded web 10M (welded molded web 10W) ​​afterwards is improved. Furthermore, in this welding process, the shape of the welded molded web 10W can be maintained more stably by welding the front and back surfaces of the molded web 10M sandwiched between, for example, a polypropylene spunbond nonwoven fabric.

[0038] <Pre-board formation process> Next, the welded molded web 10W is moved to the heating and pressing device 50 to form the pre-board 10P (see Figure 12). The heating and pressing device 50 consists of, for example, a hot plate press or a hot belt press, and is equipped with a heating means such as a heater that generates heat when electricity is applied. The PP fibers in the welded molded web 10W melt or soften when heated. Then, the welded molded web 10W is pressed while being heated or after being heated. After that, the molten (or softened) PP resin cools and solidifies, acting as a binder and binding the kenaf fibers together. In other words, a flat pre-board 10P is formed.

[0039] <Trim board molding process> Next, the trim board forming process is carried out using the press forming apparatus 60. As schematically shown in Figure 12, the press forming apparatus 60 is equipped with a mold 61 consisting of an upper mold 62 and a lower mold 63, and the pre-board 10P is formed to conform to the shape of the mold 61. The mold 61 is configured such that the upper mold 62, which is a movable mold, can be moved relative to the fixed lower mold 63 by a drive device (e.g., an electric motor, air cylinder, hydraulic cylinder, etc.) and the mold 61 can be closed and opened by moving the upper mold 62 closer to and further away from the lower mold 63.

[0040] In the trim board molding process, first, the pre-board 10P described above is heated to soften the PP resin, and the heated pre-board 10P is placed on the lower mold 63. Then, as shown in Figure 12, when the upper mold 62 is lowered and the molding die 61 is closed, the pre-board 10P is molded into a predetermined shape and compressed in the thickness direction between the upper mold 62 and the lower mold 63, which have a clearance between them.

[0041] At this time, scrap material 10E2 is generated around the outer perimeter of the pre-board 10P. However, as mentioned above, the pre-board 10P is slightly larger than the product shape of the trim board 10, so the amount of scrap material 10E2 generated is small.

[0042] Then, the upper mold 62 and the lower mold 63 are cooled, and the PP resin contained in the pre-board 10P solidifies. After that, the mold 61 is opened and the trim board 10 is demolded. This completes the manufacturing of the trim board 10.

[0043] Next, the effects will be described. The manufacturing method of the trim board 10 of this embodiment includes a web forming step of mixing and depositing kenaf fibers and PP fibers to form a web 10L, a restraining step of restraining a part of the web 10L into a predetermined shape, a molded web forming step of removing the unrestrained part of the web 10L to form a molded web 10M of a predetermined shape, and a pre-board forming step and a trim board forming step of heat-press molding the molded web 10M.

[0044] According to the above manufacturing method, by constraining a portion of the web 10L to a shape close to the shape of the finished trim board 10 to form the molded web 10M, the amount of scrap material 10E2 generated during the subsequent trim board molding process can be reduced. Furthermore, the kenaf fibers and PP fibers contained in the portion removed in the molded web forming process (scrap material 10E1) are the same kenaf fibers and PP fibers as they were before being deposited in the web forming process, and therefore maintain their original characteristics such as fiber length, making it possible to recycle the scrap material 10E1 directly in the web forming process. Moreover, since the fibers are not entangled, they can be easily untangled, and no special equipment is required to open entangled fibers, thus preventing an increase in manufacturing costs.

[0045] Furthermore, in the restraining process, a portion of the web 10L is compressed and restrained by applying a pressing jig 31 of a predetermined shape (slightly larger than the product shape of the trim board 10), and in the molded web formation process, the portion that was not restrained (compressed) by the pressing jig 31 is removed. With this manufacturing method, the fibers in the web 10L in the portion restrained (compressed) by the pressing jig 31 become less likely to move, so in the molded web formation process performed after the restraining process, the restrained (compressed) portion becomes more difficult to remove.

[0046] Furthermore, in the molding web formation process, any parts not restrained by the pressing jig 31 are removed by suction.

[0047] Furthermore, the manufacturing method includes a welding step between the molded web formation step and the pre-board formation step, in which a portion of the molded web 10M is welded. With this manufacturing method, the shape of the welded molded web 10W is stabilized, improving the operability when moving or transporting the welded molded web 10W. In addition, peeling, distortion, and tearing are less likely to occur in the pre-board formation step and the trim board formation step.

[0048] Furthermore, in processes other than the pre-board forming process and the trim board forming process, the webs 10L and 10M are sucked from the conveyor 26 side where they are placed. With this manufacturing method, the webs 10L and 10M, which are in a state of being easily crumbled, can be stably held on the conveyor 26.

[0049] Furthermore, the scrap material 10E1 of the web 10L removed in the web forming process is reused as raw material for the web 10L in the web forming process.

[0050] Thus, according to the manufacturing method of the trim board 10 of this embodiment, the scrap material 10E1 generated in the molding web formation process can be easily recycled, and a manufacturing method for the trim board 10 with a high material yield can be provided.

[0051] <Embodiment 2> Next, Embodiment 2 will be described with reference to Figures 13 to 16. In the following description, only the parts that differ from Embodiment 1 will be explained, the same reference numerals will be used for parts that are the same as in Embodiment 1, and redundant explanations will be omitted.

[0052] The trim board 110 manufactured by the manufacturing method according to this embodiment has a distribution of basis weight within its surface, as shown in Figure 13. Specifically, the central part 110A of the trim board 110 shown in Figure 13 has a lower basis weight compared to the surrounding peripheral part 110B.

[0053] The manufacturing method for the trim board 110 of this embodiment first involves performing a web forming process similar to that of Embodiment 1. In the subsequent restraining process, the pressing jig 131 used differs from Embodiment 1 in that, as shown in Figure 14, it has an opening 135 that penetrates the board surface in the center of the main body 132. When the web 110L is compressed and restrained with such a pressing jig 131, the portion of the web 110L corresponding to the opening 135 is not restrained, and when a portion of the web 110L is removed by suction during the molded web forming process, the portion corresponding to the opening 135 can also be removed.

[0054] In this embodiment, as shown in Figure 15, the portion of the web 110L that is located outside the main body 132 of the retaining jig 131 is completely removed, but only a portion of the web 110L that corresponds to the opening 135 of the main body 132 (the unrestrained portion) is removed, leaving a portion of it intact.

[0055] Subsequently, by releasing the restraint by the holding jig 131 and going through the welding process, pre-board forming process, and trim board forming process, similar to Embodiment 1 above, a trim board 110 can be manufactured having a surface weight distribution in which the surface weight is low in the portion corresponding to the opening 135 (central portion 110A) and high in the other portions (peripheral portion 110B).

[0056] <Other Embodiments> The technologies disclosed herein are not limited to the embodiments described above in the description and drawings, but also include, for example, the following embodiments.

[0057] (1) In the above embodiment 1, in the molded web forming process, the unrestrained portion of the web 10L is removed by suction from the side using a suction machine 34. However, the suction direction is not limited to the above embodiment, and for example, as shown in Figure 17, suction may be performed from above. Furthermore, the method for removing the unrestrained portion of the web 10L is not limited to the above embodiment. For example, as shown in Figures 18 and 19, the portion not restrained by the pressing jig 31 may be held by a holding member 36 and removed by tearing it from the portion restrained by the pressing jig 31. Alternatively, as shown in Figures 20 to 23, the portion not restrained by the pressing jig 31 may be removed by cutting it with scissors 37 or a cutting machine 38.

[0058] (2) In the above embodiment, the webs 10L and 110L are shown to be compressed by the pressing jigs 31 and 131 during the restraining process, but the technical scope also includes a configuration in which the pressing jigs are applied but not compressed.

[0059] (3) Furthermore, the restraining method in the restraining process is not limited to the above embodiment, and can be modified in various ways, such as using a restraining jig without the protrusion 33 or covering it with a box-shaped restraining jig.

[0060] (4) The welding process may be omitted. Furthermore, the welding method in the welding process is not limited to the above embodiment. For example, as shown in Figure 24, the outer circumference of the molded web 10M may be line-welded with a linear horn 41, and the inside may be spot-welded with a cylindrical horn 40. Alternatively, the method can be modified as appropriate, such as compressing the molded web 10M and surface welding it with a knurled surface.

[0061] (5) The pre-board formation process can be omitted. In that case, the molded web 10M or the welded molded web 10W can be directly heat-press-formed.

[0062] (6) The technologies disclosed herein are not limited to the trim board 10 of a vehicle door trim, but can be modified and applied in various ways to other vehicle interior materials such as pillar garnishes, ceiling materials, console boxes, dashboards, various instrument panels, deck trims, and other vehicle interior materials, as well as to vehicle interior materials for railways, airplanes, ships, etc., and to applications other than vehicle interior materials. [Explanation of Symbols]

[0063] 10: Trim board (plant fiber-containing resin board) 10E1, 10E2: Scrap material 10L, 110L: Web 10M: Molded web 10P: Pre-board 10W: Welded molded web 11: Mixed fiber (plant fiber and thermoplastic resin fiber) 12: Welded section 26: Conveyor (base section) 27: Suction device 31, 131: Pressing jig 34: Suction machine 40: Cylindrical horn 41: Linear horn 50: Heating and pressurizing device 60: Press molding device

Claims

1. A web-forming step involves mixing plant fibers and thermoplastic resin fibers and depositing them to form a web, A restraining step of restraining a portion of the web into a predetermined shape, A molded web forming step of forming a molded web of a predetermined shape by removing at least a portion of the unrestrained part of the web, A method for manufacturing a plant fiber-containing resin board, comprising a heat press molding step of heat press molding the molded web.

2. In the aforementioned restraining step, a portion of the web is restrained by applying the predetermined shape of the pressing jig. A method for producing a plant fiber-containing resin board according to claim 1, wherein the portion not restrained by the pressing jig is removed in the molding web forming step.

3. The method for manufacturing a plant fiber-containing resin board according to claim 2, wherein in the restraining step, a part of the web is restrained while being compressed into the predetermined shape.

4. A method for producing a plant fiber-containing resin board according to claim 2 or 3, wherein in the molding web forming step, the portion that was not restrained by the pressing jig is removed by suction.

5. A method for manufacturing a plant fiber-containing resin board according to claim 2 or 3, wherein in the molding web forming step, the portion not restrained by the pressing jig is held and removed by tearing it from the portion restrained by the pressing jig.

6. A method for producing a plant fiber-containing resin board according to claim 2 or 3, wherein in the molding web forming step, the portion that was not restrained by the pressing jig is removed by cutting.

7. A method for producing a plant fiber-containing resin board according to claim 1 or claim 2, comprising a welding step of welding a part of the molded web between the molded web forming step and the heat press molding step.

8. A method for producing a plant fiber-containing resin board according to claim 1 or 2, wherein in the molded web forming step, a portion of the unrestrained part of the web is left partially intact, thereby forming a basis distribution of the plant fibers and the thermoplastic resin fibers within the surface of the molded web.

9. A method for manufacturing a plant fiber-containing resin board according to claim 1 or claim 2, wherein in a step other than the heat press molding step, the web is sucked from the base portion side on which the web is placed.

10. A method for producing a plant fiber-containing resin board according to claim 1 or 2, wherein the web removed in the molding web forming step is reused as a raw material for the web in the web forming step.

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