Manufacturing method of plant fiber-containing resin board

Abstract

To provide a manufacturing method of a plant fiber-containing resin board capable of reducing raw material cost and equipment cost, and capable of manufacturing the resin board more easily.SOLUTION: A manufacturing method of a plant fiber-containing resin board includes: an expansion step for expanding a bundle 20 of plant fibers in a planar manner in the form that plant fibers 21 are oriented in one direction; a fiber-containing resin sheet formation step for forming a fiber-containing resin sheet 23 in which the plant fibers 21 are bound with a thermoplastic resin by impregnating the planarly-expanded plant fibers 21 with the thermoplastic resin and curing it; a cut step for cutting a fiber-containing resin sheet 34 to form a plurality of fiber-containing resin pieces 24; a laminate formation step for forming a laminate 25 in which the plurality of fiber-containing resin pieces 24 are planarly arranged and laminated; and a heat-press molding step for manufacturing a plant fiber-containing resin board 10 by heat-pressing the laminate 25.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] A conventional method for manufacturing a board member using, for example, plant fibers is described in Patent Document 1. Patent Document 1 describes a method for obtaining a fiberboard for thermoforming by mixing kenaf fibers, which have been defibrated and cut into short pieces, with short PP resin fibers in a mixer, forming the mat into a mat using a former, and then compressing and molding the mat to a predetermined thickness using a press, followed by cutting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-179716 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the conventional manufacturing method described above, a resin board that has high rigidity and excellent handleability even at a low basis weight can be obtained, but there has been a demand for further cost reduction and simplification of the manufacturing method.

[0005] The technology disclosed in this specification was developed based on the above circumstances, and aims to provide a method for manufacturing plant fiber-containing resin boards that can reduce raw material costs and equipment costs and are easier to manufacture. [Means for solving the problem]

[0006] The technology disclosed in this specification, which was completed to solve the above-mentioned problems, is a method for manufacturing a plant fiber-containing resin board, including: an unfolding step in which bundles of plant fibers obtained from plants are spread out in a plane so that the plant fibers are oriented in one direction; a fiber-containing resin sheet forming step in which the plant fibers spread out in a plane are impregnated with a thermoplastic resin and cured to form a fiber-containing resin sheet in which the plant fibers are bonded by the thermoplastic resin; a cutting step in which the fiber-containing resin sheet is cut to form a plurality of fiber-containing resin pieces; a laminate forming step in which a plurality of the fiber-containing resin pieces are arranged in a plane and stacked to form a laminate; and a hot-press molding step in which the laminate is hot-pressed to produce a plant fiber-containing resin board in which the plurality of fiber-containing resin pieces are integrated and molded into a predetermined shape.

[0007] Compared to conventional methods for producing plant fiber-containing resin boards from mats formed by mixing short-cut plant fibers and thermoplastic resin fibers, this manufacturing method allows the use of inexpensive thermoplastic resin in pellet or film form rather than processed fibrous form. Furthermore, it eliminates the need for a mixing device for mixing the plant fibers and thermoplastic resin fibers or an interlacing device for forming the mat, thereby reducing material and equipment costs compared to conventional methods. Furthermore, compared to conventional manufacturing methods, it is possible to suppress the generation of plant fiber dust, thereby improving material yield. In other words, it is possible to produce plant fiber-containing resin boards simply and inexpensively.

[0008] Furthermore, since the plant fibers can be contained in a longer state than in conventional plant fiber-containing resin boards, the strength and rigidity of the plant fiber-containing resin board can be increased, which in turn leads to a reduction in the weight of the plant fiber-containing board.

[0009] In the spreading step, the bundle of plant fibers may be spread out in a planar form while bonds between the plant fibers remain in a direction intersecting the orientation direction of the plant fibers.

[0010] The above-mentioned manufacturing method can improve the strength and rigidity of the resulting plant fiber-containing resin board in the direction crossing the orientation of the plant fibers, compared to when the bundles of plant fibers are completely opened like combing. Furthermore, by bonding the plant fibers together, it is possible to reduce the content of thermoplastic resin, thereby achieving weight reduction.

[0011] In the fiber-containing resin sheet forming step, the thermoplastic resin film may be heated while being superimposed on the plant fibers, thereby impregnating the plant fibers with the thermoplastic resin. According to this production method, the plant fibers can be easily and uniformly impregnated with the thermoplastic resin in the plane direction.

[0012] In the cutting step, the fiber-containing resin sheet may be cut along the orientation direction of the plant fibers and in a direction intersecting the orientation direction of the plant fibers, and in the laminate forming step, the plurality of fiber-containing resin pieces may be randomly arranged and laminated so that the orientation directions of the plant fibers contained in the fiber-containing resin pieces arranged adjacent to each other are different. According to this manufacturing method, a plant fiber-containing resin board having uniform basis weight and strength directionality as a whole can be obtained.

[0013] In the cutting step, the fiber-containing resin sheet may be cut along the orientation direction of the plant fibers, and in the laminate forming step, a plurality of the fiber-containing resin pieces may be arranged and laminated so that the orientation direction of the plant fibers is the same. According to this manufacturing method, a plant fiber-containing resin board having a beautiful wood-grain design surface can be obtained. [Effects of the Invention]

[0014] According to the technology disclosed in this specification, it is possible to reduce raw material costs and equipment costs, and to provide a method for manufacturing a plant fiber-containing resin board that is easier to manufacture. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view showing a trim board according to a first embodiment; [Figure 2] (A) A perspective view of a kenaf fiber bundle. (B) A perspective view showing the kenaf fiber bundle in an unfolded state (unfolding process). [Figure 3] A partially enlarged schematic diagram showing kenaf fibers in an unfolded state [Figure 4] (A) A perspective view showing a state in which a polypropylene film is superimposed on spread kenaf fibers (fiber-containing resin sheet forming process). (B) A perspective view of a fiber-containing resin sheet. [Figure 5] An explanatory diagram showing the cutting process [Figure 6] Plan view of the laminate (laminate formation process) [Figure 7] A side view showing the pre-board placed in the mold (heat press molding process) [Figure 8] Front view of trim board [Figure 9] (A) Plan view of the laminate of the second embodiment (laminate formation step) (B) Front view of the trim board [Figure 10] (A) Plan view of the laminate of the third embodiment (laminate formation step) (B) Front view of the trim board DETAILED DESCRIPTION OF THE INVENTION

[0016] <Embodiment 1> A first embodiment will be described with reference to Figs. 1 to 8. In this embodiment, a trim board 10 for a vehicle will be illustrated as a plant fiber-containing resin board. The trim board 10 forms part of a door trim attached to the interior side of a door panel of a vehicle door such as an automobile, and is an interior material that forms the wall surface of the vehicle interior and improves the appearance and comfort of the vehicle interior. As shown in Fig. 1, the trim board 10 is configured to include a substantially flat, plate-like flat portion 11 and an upright wall portion 12 rising from the edge of the flat portion 11. The trim board 10 is mainly configured with a base material 13 containing plant fiber and a thermoplastic resin. The interior surface of the base material 13 of the trim board 10 may be covered with a skin (not shown).

[0017] Plant fibers are fibers derived from plants. Examples of plant fibers include fibers obtained from various plants such as kenaf, flax, hemp, jute, Manila hemp, sisal, gampi, mitsumata, kozo, banana, pineapple, coconut, corn, sugarcane, bagasse, palm, papyrus, reed, esparto, sabaigrass, wheat, rice, bamboo, various coniferous trees (such as cedar and cypress), broadleaf trees, and cotton. The part of the plant used as the plant fiber is not particularly limited, and may be any part of the plant, such as non-woody parts, stems, roots, leaves, and woody parts, as long as fiber can be extracted.

[0018] Plant fibers can be obtained by, for example, subjecting the above-mentioned plants to a retting process. Specifically, the plant body is immersed in water, and the binding components contained in the plant body (components such as pectin that bind plant fibers together within the plant body) are decomposed by the action of microorganisms and enzymes in the water, and the parts other than the plant fiber are removed, thereby obtaining plant fibers. This retting process loosens the bonds between the plant fibers, rather than leaving them completely separate, and forms bundles that can be easily disassembled.

[0019] The average fiber length of the plant fibers obtained in this manner is not particularly limited, but is preferably 500 to 4000 mm. The average diameter of the plant fiber bundles is preferably 10 to 20 mm. Furthermore, the average diameter of each plant fiber is preferably 50 to 150 μm, and more preferably 80 to 100 μm.

[0020] Kenaf fiber is preferred as the plant fiber. Kenaf is an annual plant that grows extremely quickly and has excellent carbon dioxide absorption properties, which can contribute to reducing the amount of carbon dioxide in the atmosphere and making effective use of forest resources. Furthermore, bast plant fibers such as kenaf have voids in the fiber itself, making them preferable in terms of weight reduction. In this embodiment, kenaf fiber with an average fiber diameter of 80 μm to 100 μm is used as the plant fiber.

[0021] On the other hand, the thermoplastic resin constituting the base material 13 of the trim board 10 of this embodiment mainly functions as a binder resin, and various thermoplastic resins can be used. Examples of thermoplastic resins include polyolefin resin, polyester resin, polystyrene, acrylic resin (resin obtained using methacrylate and / or acrylate, etc.), polyamide resin, polycarbonate resin, polyacetal resin, and ABS resin. 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, and aromatic polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate. These thermoplastic resins may be used alone or in combination. In this embodiment, polypropylene is used as the thermoplastic resin.

[0022] The trim board 10 of this embodiment contains a plurality of kenaf fiber groups in the base material 13, each group comprising a plurality of kenaf fibers 21 oriented in one direction. More specifically, each kenaf fiber group is made up of a plurality of kenaf fibers, each having a length of, for example, 10 to 100 mm, oriented in one direction and arranged generally horizontally (in a state where the fibers are arranged in a direction intersecting the orientation direction) so as to spread in the plane direction of the base material 13. A plurality of such kenaf fiber groups spread out in a plane such that the kenaf fibers in each kenaf fiber group are randomly oriented so that the orientation direction of the kenaf fibers in adjacent kenaf fiber groups does not match, and a plurality of such kenaf fiber groups are overlapped in the thickness direction of the base material 13. Note that the orientation direction of the kenaf fibers in a kenaf fiber group is considered to be generally oriented in one direction even if some of the fibers are not oriented in the above-mentioned one direction.

[0023] In the trim board 10 of this embodiment, the content (mass %) of the kenaf fibers 21 is 35 mass % or more, preferably 40 mass % or more, and 80 mass % or less, preferably 50 mass % or less. When the content of the kenaf fibers is within this range, the trim board 10 is ensured to be lightweight or rigid, and impact resistance is easily ensured.

[0024] Next, we will explain the manufacturing method of the trim board 10. The trim board 10 of this embodiment is manufactured using long kenaf fiber bundles 20 obtained by a retting process in which harvested kenaf is soaked in water, the outer bark and the bast are separated using the power of microorganisms in the water, and the kenaf fibers are extracted from the bast.

[0025] <Development process> In the spreading process, a kenaf fiber bundle (an example of a plant fiber bundle) 20 obtained from kenaf and bundled into a long cylindrical shape as shown in Fig. 2(A) is opened and spread out into a planar shape by loosening it in a lateral direction (Y direction) that intersects with the extension direction (X direction) of the fiber bundle 20 as shown in Fig. 2(B). Each of the many kenaf fibers 21 that constitute the kenaf fiber bundle 20 is kept in a state of being oriented generally along the extension direction of the kenaf fiber bundle 20.

[0026] The planar shape refers to a state in which a large number of kenaf fibers 21 are arranged side by side in the horizontal direction (a direction intersecting the extending direction of the kenaf fibers 21). The large number of kenaf fibers 21 do not all have to be arranged side by side in the horizontal direction, and in reality, a plurality of fibers are overlapped in the vertical direction (Z direction) to form a nearly flat surface as a whole.

[0027] 3 is an enlarged plan view schematically illustrating a portion of kenaf fibers 21 spread out in a plane, and numerous lines extending vertically in the figure represent the kenaf fibers 21. Each kenaf fiber 21 is oriented generally in one direction (X direction, the vertical direction in FIG. 3), but some of them form a portion (21C in FIG. 3) that extends in the horizontal direction (a direction intersecting with the X direction) so as to bridge between adjacent kenaf fibers 21. In other words, the kenaf fibers 21 arranged horizontally are in a state in which bonds such as entanglement or snagging remain between the kenaf fibers 21 in a direction intersecting with their orientation direction.

[0028] In this embodiment, the length of the kenaf fiber bundle 20 before spreading is approximately 500 to 4000 mm, and the diameter is approximately 10 to 20 mm. After spreading, the width (dimension in the Y direction) of the plurality of kenaf fibers 21 arranged side by side is approximately 200 mm, and the thickness (dimension in the Z direction) is 0.1 to 0.3 mm. When spreading the kenaf fiber bundle 20 into a planar shape, the width of the kenaf fibers 21 arranged side by side after spreading is preferably 5 times or more, and more preferably 10 times or more, the diameter of the kenaf fiber bundle 20.

[0029] <Fiber-containing resin sheet forming process> Next, the plurality of kenaf fibers 21 spread out in a plane are impregnated with polypropylene, a thermoplastic resin. Specifically, as shown in FIG. 4(A), a polypropylene film 30 stretched into a film shape is placed over the plurality of kenaf fibers 21 arranged side by side, and heated to melt the polypropylene, thereby impregnating the kenaf fibers 21. At this time, pressure is applied from the film 30 side toward the kenaf fibers 21 side, allowing the polypropylene to be uniformly distributed throughout. Thereafter, the polypropylene is cooled and hardened to form a fiber-containing resin sheet 23 in which the kenaf fibers 21 are bound by the polypropylene resin (see FIG. 4(B)).

[0030] In this embodiment, the thickness of the polypropylene film 30 used is set to 0.1 to 0.3 mm.

[0031] <Cutting process> Next, the obtained fiber-containing resin sheet 23 is cut in a direction along the orientation direction of the kenaf fibers 21 (X direction in FIG. 5) and in a direction perpendicular to the orientation direction (Y direction in FIG. 5) to form a plurality of rectangular fiber-containing resin pieces 24. The kenaf fibers 21 contained in each fiber-containing resin piece 24 are oriented generally in the longitudinal direction within the fiber-containing resin piece 24, but some kenaf fibers 21 extend in a direction intersecting the longitudinal direction (see FIG. 3). The dimensions of each cut fiber-containing resin piece 24 are 5 to 100 mm in the direction along the orientation direction of the kenaf fibers 21 and 1 to 100 mm in the direction perpendicular to the orientation direction of the kenaf fibers 21.

[0032] <Laminate formation process> Next, the obtained plurality of rectangular fiber-containing resin pieces 24 are spread out and arranged in a plane and stacked in the thickness direction to form a laminate 25. The kenaf fibers 21 in one fiber-containing resin piece 24 are arranged and stacked randomly (without directionality) so that the orientation direction of the kenaf fibers 21 in adjacent fiber-containing resin pieces 24 does not match. Figure 6 is a plan view that schematically shows a laminate 25 in which the fiber-containing resin pieces 24 are arranged and stacked in a plane, and the numerous pieces scattered in random orientations in the figure represent the fiber-containing resin pieces 24.

[0033] In this embodiment, the overall dimensions of the laminate 25 are 1000 mm long, 1500 mm wide, and 50 mm thick.

[0034] <Pre-board forming process> Next, the formed laminate 25 is hot-pressed using, for example, a hot plate press or a hot belt press. The laminate 25 of the fiber-containing resin pieces 24 is pressurized while being heated or after being heated. The heating temperature is set to a temperature equal to or higher than the melting point of the polypropylene (thermoplastic resin) contained in the laminate 25. This melts the polypropylene contained in the laminate 25 (fiber-containing resin pieces 24), and adjacent fiber-containing resin pieces 24 are bonded together. In other words, a flat pre-board 26 is formed in which the kenaf fibers 21 in different fiber-containing resin pieces 24 contained in the laminate 25 are bonded together by the polypropylene. The pre-board 26 is in a state before being molded into the product shape of the trim board 10.

[0035] <Hot press molding process> The pre-board 26 thus formed is heated and then set between the upper and lower dies 41 and 42 of the molding die 40, which are in the open state, and then the upper and lower dies 41 and 42 are closed to press-form the pre-board into a predetermined shape (see FIG. 7). After the polypropylene has cooled, the pre-board 26 is removed from the die, completing the trim board 10 (base material 13) (see FIG. 8).

[0036] Next, the effects of this embodiment will be described. The manufacturing method of the trim board 10 of this embodiment includes the following steps: a spreading step of spreading kenaf fiber bundles 20 obtained from kenaf in a planar form with the kenaf fibers 21 oriented in one direction; a fiber-containing resin sheet forming step of impregnating the planarly spread kenaf fibers 21 with polypropylene (thermoplastic resin) and curing the impregnated kenaf fibers 21 to form a fiber-containing resin sheet 23 in which the kenaf fibers 21 are bonded by the polypropylene; a cutting step of cutting the fiber-containing resin sheet 23 to form a plurality of fiber-containing resin pieces 24; a laminate forming step of arranging and stacking the plurality of fiber-containing resin pieces 24 in a planar form to form a laminate 25; and a hot-press molding step of hot-pressing the laminate 25 to manufacture the trim board 10 in which the plurality of fiber-containing resin pieces 24 are integrated and molded into a predetermined shape.

[0037] Compared to conventional methods for producing plant fiber-containing resin boards from a mat formed by mixing short-cut plant fibers and thermoplastic resin fibers, this manufacturing method allows the use of inexpensive thermoplastic resin in pellet or film form rather than processed fibrous form. Furthermore, it eliminates the need for a mixing device for mixing the plant fibers and thermoplastic resin fibers or a mat-forming device, for example, a confounding device, thereby reducing material and equipment costs compared to conventional methods. Specifically, it eliminates the need for consumables such as garnet wire and needle punches. Furthermore, compared to conventional manufacturing methods, it reduces the generation of plant fiber dust, thereby improving material yield. In other words, it is possible to produce trim boards 10 easily and inexpensively.

[0038] Furthermore, since the kenaf fibers can be contained in a longer dimension than conventional ones, the strength and rigidity of the trim board 10 can be increased, which in turn leads to a reduction in the weight of the trim board 10.

[0039] In the spreading step, the kenaf fiber bundles 20 are spread out in a planar shape while the bonds between the kenaf fibers in the horizontal direction intersecting the orientation direction of the kenaf fibers 21 remain.

[0040] The above manufacturing method can increase the strength and rigidity of the resulting trim board 10 in a direction intersecting the orientation direction of the kenaf fibers 21, compared to when the kenaf fiber bundles 20 are completely opened as if combed. Furthermore, bonding of the kenaf fibers 21 together can reduce the content of thermoplastic resins such as polypropylene, thereby achieving weight reduction.

[0041] Furthermore, in the fiber-containing resin sheet forming process, the polypropylene film 30 is heated while overlapping the horizontally arranged kenaf fibers 21, thereby impregnating the kenaf fibers 21 with polypropylene. According to this manufacturing method, the kenaf fibers 21 can be easily and uniformly impregnated with polypropylene in the surface direction.

[0042] In the cutting step, the fiber-containing resin sheet 23 is cut along the orientation direction of the kenaf fibers 21 and in a direction intersecting the orientation direction of the kenaf fibers 21, and in the laminate formation step, the plurality of fiber-containing resin pieces 24 are randomly arranged and laminated so that the orientation directions of the kenaf fibers 21 contained in adjacent fiber-containing resin pieces 24 are different. This manufacturing method makes it possible to obtain a trim board 10 with uniform overall basis weight and strength directionality.

[0043] <Embodiment 2> This embodiment differs from the above embodiment in that in the cutting step, the fiber-containing resin sheet 23 is cut into wide tiles rather than into strips. Other parts that overlap with the first embodiment will not be described. The cutting direction is only perpendicular to the orientation direction of the kenaf fibers 21. The dimensions of each cut-out fiber-containing resin piece 124 are approximately square, with each side being the length dimension in the width direction of the fiber-containing resin sheet 23. In other words, each fiber-containing resin piece 124 is approximately square, with each side being approximately 200 mm. Note that if the widths of the base and tip sides of the multiple kenaf fibers 21 spread out in a planar form in the fiber-containing resin sheet forming step are different, and the cutting step involves cutting only in a direction perpendicular to the orientation direction of the kenaf fibers 21, the fiber-containing resin piece 124 may be trapezoidal.

[0044] In the laminate formation process, a plurality of such tile-shaped fiber-containing resin pieces 124 are arranged in a planar shape with one side extending in the same direction and stacked (see FIG. 9(A)). At this time, the orientation directions of the kenaf fibers 21 in the fiber-containing resin pieces 124 are a mixture of those extending in the X direction and those extending in the Y direction in FIG.

[0045] According to a trim board 110 (substrate 113) (see Figure 9 (B)) molded from such a laminate 125, the kenaf fibers 21 in the fiber-containing resin pieces 24 are bonded in the horizontal direction (the direction intersecting the extension direction of the kenaf fibers 21) more than in embodiment 1, thereby further increasing the strength and rigidity of the trim board 110.

[0046] <Embodiment 3> This embodiment differs from the above embodiment in that in the cutting step, the fiber-containing resin sheet 23 is cut only along the extending direction of the kenaf fibers 21. In other words, the fiber-containing resin pieces 224 are formed into elongated strips.

[0047] In the laminate formation process, the plurality of band-shaped fiber-containing resin pieces 224 are arranged in a planar manner with the kenaf fibers 21 extending in the same direction, and laminated (see FIG. 10(A)). A trim board 210 (base material 213) molded from such a laminate 225 can express a beautiful design like wood grain (see FIG. 10(B)).

[0048] <Other embodiments> The technology disclosed in this specification is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included in the technical scope.

[0049] (1) In the above embodiment, a polypropylene film 30 is superimposed on a plurality of kenaf fibers 21 arranged side by side, and the polypropylene is heated to melt the polypropylene and impregnate the kenaf fibers 21. However, the method of impregnating plant fibers with a thermoplastic resin is not limited to the above embodiment. For example, plant fibers may be impregnated with a thermoplastic resin by melting thermoplastic resin pellets in a hopper and extruding them with an extruder, or by spraying the molten thermoplastic resin.

[0050] (2) Furthermore, pressure does not necessarily need to be applied when the thermoplastic resin is impregnated into the plant fibers.

[0051] (3) In the cutting step, the fiber-containing resin sheet can be cut into any shape, not limited to the above-described embodiment. Furthermore, the orientation of the fiber-containing resin pieces when they are arranged and stacked in a planar form in the laminate formation step is not limited to the above-described embodiment, but can be changed as desired.

[0052] (4) The pre-board forming step can be omitted. In such a case, for example, a method is available in which the laminate is formed on a sheet-like support member, and the laminate together with the support member is placed in a mold and press-molded.

[0053] (5) The technology disclosed in this specification is not limited to the trim board 10 of a vehicle door trim, but can be applied to various plant fiber-containing resin boards. [Explanation of symbols]

[0054] 10, 110, 210: Trim board (plant fiber-containing resin board) 13, 113, 213: Base material (plant fiber-containing resin board) 20: Kenaf fiber bundle (plant fiber bundle) 21: Kenaf fiber (plant fiber) 23: Fiber-containing resin sheet 24, 124, 224: Fiber-containing resin piece 25, 125, 225: Laminate 26: Pre-board 30: Polypropylene film (film-like thermoplastic resin) 40: Molding mold

Claims

1. a spreading step of spreading the bundle of plant fibers obtained from the plant into a plane shape in such a way that the plant fibers are oriented in one direction; A fiber-containing resin sheet forming process in which the plant fibers spread out in a plane are impregnated with a thermoplastic resin and cured to form a fiber-containing resin sheet in which the plant fibers are bound by the thermoplastic resin; a cutting step of cutting the fiber-containing resin sheet to form a plurality of fiber-containing resin pieces; a laminate forming step of forming a laminate by arranging and stacking a plurality of the fiber-containing resin pieces in a planar shape; A method for manufacturing a plant fiber-containing resin board, comprising: a heat press molding process in which the laminate is heat pressed to integrate multiple fiber-containing resin pieces and produce a plant fiber-containing resin board molded into a predetermined shape.

2. 2. The method for manufacturing a plant fiber-containing resin board according to claim 1, wherein in the spreading step, the bundle of plant fibers is spread out in a planar form while the bonds between the plant fibers in a direction intersecting the orientation direction of the plant fibers remain.

3. 3. A method for manufacturing a plant fiber-containing resin board according to claim 1 or claim 2, wherein in the fiber-containing resin sheet forming process, the thermoplastic resin in film form is heated while superimposed on the plant fibers, thereby impregnating the plant fibers with the thermoplastic resin.

4. In the cutting step, the fiber-containing resin sheet is cut along the orientation direction of the plant fibers and in a direction intersecting the orientation direction of the plant fibers, A method for manufacturing a plant fiber-containing resin board as described in claim 1 or claim 2, wherein in the laminate formation process, multiple fiber-containing resin pieces are randomly arranged and stacked so that the orientation directions of the plant fibers contained in the fiber-containing resin pieces arranged adjacent to each other are different.

5. In the cutting step, the fiber-containing resin sheet is cut along the orientation direction of the plant fibers, 3. The method for manufacturing a plant fiber-containing resin board according to claim 1, wherein in the laminate forming step, the plurality of fiber-containing resin pieces are arranged and stacked so that the orientation directions of the plant fibers are in the same direction.

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