Method for manufacturing resin board containing vegetable fiber

Abstract

To provide a method for manufacturing a resin board containing vegetable fibres that is resistant to whitening.SOLUTION: In a method for manufacturing a resin board 20 containing vegetable fibers, the resin board 20 comprising a base material 21 containing vegetable fibers and a thermoplastic resin, and a waterproof film 25 having waterproof properties covering at least one surface of the base material 21, the method includes: a pre-board forming step of heating and pressing a fiber mat 21M containing vegetable fibers and thermoplastic resin fibers to form a pre-board 21P having, on at least one surface, a plurality of grooves 22 extending to its outer edge; a waterproof film adhering step of adhering a waterproof film 25 to the surface of the pre-board 21P having the plurality of grooves 22 to form a film-attached pre-board 21F in which the plurality of grooves 22 are sealed by the waterproof film 25; and a heating and press-forming step of heating the film-attached pre-board 21F and pressing it so that the plurality of grooves 22 are crushed, these steps being performed in sequence.SELECTED DRAWING: Figure 10

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, for example, plant fibers, the method described in Patent Document 1 is known. Patent Document 1 describes a method for manufacturing a base material for vehicle interiors by forming a fiberboard for thermoforming, which is a mixture of plant fibers and resin fibers, into a mat shape, heating and cooling it to produce a pre-board, reheating the pre-board to a temperature at which the resin melts, and then press-forming it using an upper and lower mold for cold press forming.

[0003] Further, Patent Document 2 describes a wooden board having one or both sides covered with a moisture-proof sheet. Since wooden boards may have a reduced strength or generate an odor due to being wetted with water or the like, a configuration is adopted in which such a waterproof layer is provided on the surface in order to achieve waterproofing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in recent years, there are cases where the texture and feel of the board member itself made of plant-based materials are used as a design, and in such cases, a transparent layer is used as a layer for covering the board member.

[0006] However, when the surface of the board member is coated with a transparent layer having waterproof properties, there is a problem that when the board member is heat-molded, gases such as water vapor generated from the plant-based material enter between the board member and the transparent waterproof layer, causing whitening to occur on the completed board member. That is, the appearance deteriorates, making it difficult to use as a product.

[0007] The technology disclosed in this specification has been completed based on the above circumstances, and an object thereof is to provide a method for manufacturing a plant fiber-containing resin board that is less likely to turn white.

Means for Solving the Problems

[0008] The technology disclosed in this specification, which has been completed to solve the above problems, is a method for manufacturing a plant fiber-containing resin board including a base material containing plant fibers and a thermoplastic resin, and a waterproof film having waterproof properties that covers at least one surface of the base material. The method sequentially performs a pre-board forming step of heating and pressing a fiber mat containing the plant fibers and thermoplastic resin fibers to form a pre-board having a plurality of groove portions extending to the outer edge portion on at least one surface, a waterproof film attaching step of attaching the waterproof film to the surface of the pre-board where the plurality of groove portions are formed to form a pre-board with a film in a state where the plurality of groove portions are blocked by the waterproof film, and a heat press forming step of heating the pre-board with a film and press-forming it so that the plurality of groove portions are crushed.

[0009] According to the above manufacturing method, even when manufacturing a plant fiber-containing resin board including a hot press forming step (including the step of reheating a pre-board with a film), during heating in the hot press forming step, when heating up to the temperature at which the resin in the pre-board melts, gas such as water vapor generated from the pre-board is discharged to the outside from the outer periphery of the pre-board with a waterproof film through a tubular portion formed between a plurality of groove portions of the pre-board and the waterproof film. Therefore, when the pre-board with a waterproof film is heated up to the temperature at which the resin melts and press-formed so that the plurality of groove portions collapse, almost no gas remains between the pre-board and the waterproof film, and thus it is possible to suppress the accumulation of gas between the base material and the waterproof film after press-forming and the occurrence of whitening in the plant fiber-containing resin board.

[0010] In the pre-board forming step, the plurality of groove portions may be formed by transferring a transfer portion arranged between a press mold for forming the pre-board and the fiber mat. According to such a configuration, one embodiment for forming the groove portions can be realized.

[0011] Also, in the pre-board forming step, the fiber mat may be hot press-formed by passing between two conveyor belts arranged to face each other, and the plurality of groove portions may be formed by transferring a transfer portion arranged between the conveyor belt and the fiber mat. According to such a configuration, another embodiment for forming the groove portions can be realized.

[0012] The plurality of groove portions may be arranged in a grid pattern. According to such a configuration, the gas generated from the pre-board can be efficiently discharged.

Advantages of the Invention

[0013] According to the technology disclosed in this specification, it is possible to provide a method for manufacturing a plant fiber-containing resin board in which whitening is less likely to occur.

Brief Description of the Drawings

[0014]

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Mode for Carrying Out the Invention

[0015] An embodiment will be described with reference to FIGS. 1 to 17. In this embodiment, a method for manufacturing an ornament board 20 provided in an interior material of a vehicle will be exemplified. The door trim 10 constitutes the interior side portion of the vehicle's side door and is attached to the door inner panel from the interior side of the vehicle. The door trim 10 is mainly composed of a trim board 11 having a generally rectangular shape. In addition to the trim board 11, the door trim 10 includes various functional components such as an inside handle 12, an armrest 13, a door pocket 14, and a speaker grill 15 provided on the trim board 11 (see FIG. 1).

[0016] The trim board 11 is formed by assembling a plurality of board members and is mainly composed of an upper board 17, a lower board 18, an ornament board 20, and an armrest board 19. Among these, the ornament board 20 is a plant fiber-containing board of this embodiment, and the ornament board 20 is disposed above the armrest 13 provided on the trim board 11. The interior surface of the ornament board 20 in the vehicle interior is not covered with a skin material such as synthetic leather, genuine leather, or fabric, but is configured to utilize the texture and feel of the base material 21 described later as a design. Note that the board members other than the ornament board 20 are configured such that the surface of the plate-shaped base material is covered with a skin material.

[0017] The ornament board 20 is a plate-shaped member having a predetermined thickness. As shown in FIG. 2, the ornament board 20 includes a plate-shaped base material 21 and a transparent or translucent waterproof film 25 that covers the interior surface 21A (design surface side) of the base material 21 in the vehicle interior.

[0018] The base material 21 is supposed to contain vegetable fibers and a thermoplastic resin. Examples of the vegetable fibers contained in the base material 21 can include bast plant fibers such as kenaf and vegetable fibers obtained by unraveling fibrous wood and the like. The base material 21 is obtained by heating and press-molding a fiber mat in which vegetable fibers and thermoplastic resin fibers are mixed, and the thermoplastic resin functions as a binder that binds the vegetable fibers. Examples of the thermoplastic resin contained in the base material 21 can include polyolefin resins (such as polypropylene and polyethylene), polyester resins (such as aliphatic polyester resins like polylactic acid and polycaprolactone, and aromatic polyester resins like polyethylene terephthalate), and the like.

[0019] In this embodiment, as the base material 21, one containing vegetable fibers obtained from kenaf and polypropylene is used, but the material of the base material 21 is not limited to these and can be changed as appropriate.

[0020] The transparent or semi-transparent waterproof film 25 has waterproofness and odor-proofness, protects the surface of the base material 21, and has an effect like clear coating, and has a function of enhancing the design property of the base material 21. Examples of the waterproof film 25 can include, for example, a three-layer film of polyethylene-nylon-polyethylene (each layer is not shown).

[0021] Next, an example of the manufacturing method of the ornament board 20 will be described. The manufacturing method of the ornament board 20 of this embodiment sequentially executes a pre-board forming step of forming a pre-board 21P, a waterproof film attaching step of attaching a waterproof film 25 to the surface of the pre-board 21P, and an ornament board forming step (an example of a heating press molding step) of heating and press-molding the pre-board 21P (pre-board 21F with a waterproof film) covered with the waterproof film 25 to produce the ornament board 20. Hereinafter, each step will be specifically described.

[0022] <Pre-board forming step> In the pre-board forming process, as shown in FIGS. 3 and 4, first, a fiber mat 21M composed of vegetable fibers and thermoplastic resin fibers is heated and pressed by a pair of flat press dies 30 composed of an upper die 31 and a lower die 32. Thereby, the fiber mat 21M is compressed, and the thermoplastic resin contained in the fiber mat 21M melts and mixes at the contact surfaces with each other. Then, the thermoplastic resin contained in the fiber mat 21M cools and solidifies, thereby forming the pre-board 21P.

[0023] In the pre-board forming process of the present embodiment, a transfer sheet (an example of a transfer portion) 35 is disposed between the upper die 31 and the fiber mat 21M. The transfer sheet 35 is made of Teflon (registered trademark) and has an uneven shape having a plurality of standing walls 37 standing from a flat sheet-like base portion 36. The plurality of standing walls 37 may be arranged in a stripe shape extending in parallel, for example, in a plan view, or may be arranged in a lattice shape extending in the vertical and horizontal directions, but both ends in the extending direction of each standing wall 37 are set to dimensions extending outside the outer edge portion of the fiber mat 21M. That is, a plurality of groove portions 22 extending to the outer edge portion of the pre-board 21P are formed on the surface of the pre-board 21P formed by heating and pressing the fiber mat 21M through the transfer sheet 35 by a pair of press dies 30 (see FIGS. 6 and 7).

[0024] <Waterproof film attaching process> Next, the pre-board 21P is heated again by a heater (not shown), and after melting at least the thermoplastic resin on its surface, it is disposed between a pair of flat press dies (cooling dies) 40 as shown in FIG. 8. At this time, the pre-board 21P is oriented such that the groove portions 22 are disposed on the upper surface side, and a waterproof film 25 is disposed between the upper surface of the pre-board 21P and the upper die 41.

[0025] Subsequently, the upper mold 41 and the lower mold 42 are brought close to each other, and the press mold 40 is closed (see Fig. 9), thereby laminating the pre-board 21P and the waterproof film 25. When the thermoplastic resin contained in the pre-board 21P cools and solidifies, the waterproof film 25 is adhered to the upper surface of the pre-board 21P by the thermoplastic resin oozing out from the pre-board 21P, thereby obtaining a pre-board 21F with a waterproof film (see Fig. 10).

[0026] At this time, the distance between the press mold 40 (the upper mold 41 and the lower mold 42) is set to a dimension such that the plurality of groove portions 22 of the pre-board 21P are not crushed. That is, the waterproof film 25 is attached to the ridge portion 23 disposed between the adjacent groove portions 22, and is disposed in a state of closing the plurality of groove portions 22 with respect to the pre-board 21P. Thereby, a plurality of tubular spaces S surrounded by the waterproof film 25 and the plurality of groove portions 22 are formed in the pre-board 21F with a waterproof film (see Fig. 10). These plurality of tubular spaces S extend to the outer edge portion of the pre-board 21F with a waterproof film, and both ends thereof are in an open state facing outward.

[0027] <Ornament board forming process (an example of a hot press forming process)> In the ornament board forming process, first, the pre-board 21F with a waterproof film is heated by a heater (not shown). Thereby, the resin in the pre-board 21F with a waterproof film melts and becomes in a softened state. Then, the pre-board 21F with a waterproof film in the softened state is disposed between a pair of molding dies 50 (an upper die 51 and a lower die 52) that can be pressed into a predetermined product shape as shown in Fig. 11. Subsequently, as shown in Fig. 12, the upper die 51 and the lower die 52 are closed, thereby press-forming the pre-board 21F with a waterproof film by the respective molding surfaces of the upper die 51 and the lower die 52. At this time, the dimension between the pair of molding dies 50 is set to a dimension such that the groove portions 22 are crushed. That is, by press-forming, the groove portions 22 are crushed and the entire back surface of the waterproof film 25 is in close contact with the base material 21 (see Figs. 2 and 12).

[0028] Before the groove portion 22 collapses in this way, gases such as water vapor released from the vegetable fibers contained in the pre-board 21P during heating and temperature rise are discharged to the outside from the outer edge portion of the pre-board 21F with a waterproof film through the tubular space S surrounded by the groove portion 22 and the waterproof film 25. After that, the groove portion 22 is crushed by press molding, and the entire back surface of the waterproof film 25 is brought into close contact with the base material 21. As a result, the pre-board 21F with a waterproof film has a shape following the shape of the molding space, and the ornament board 20 is completed.

[0029] In addition, in the pre-board forming process described above, the width of the groove portion 22 formed in the pre-board 21P is preferably in the range of 0.5 mm to 2.0 mm, and the depth of the groove portion 22 is preferably in the range of 0.2 mm to 0.4 mm. If the width of the groove portion 22 becomes too wide, the waterproof film 25 is likely to bend and enter the inside of the groove portion 22 in the waterproof film attaching process, and wrinkles are likely to occur on the surface during the heat press molding process (see FIGS. 13 and 14). Also, if the depth of the groove portion 22 is too deep, it becomes difficult for the groove portion 22 to collapse properly during heat press molding, and the base material 21 is not sufficiently crushed, making it easy for a wrinkle pattern to occur (see FIGS. 15 and 16). Further, when the width of the groove portion 22 is too small or the depth of the groove portion 22 is too shallow, the cross-sectional area of the tubular portion (space S) formed in the pre-board 21F with a waterproof film becomes too small, making it difficult to sufficiently discharge gases such as water vapor released from the pre-board 21P to the outside.

[0030] Next, the functions and effects will be described. This embodiment is a method for manufacturing an ornament board 20 including a base material 21 containing vegetable fibers and a thermoplastic resin, and a waterproof film 25 having waterproof properties that covers one surface (the vehicle interior surface 21A) of the base material 21. The method includes a pre-board forming step of heating and pressing a fiber mat 21M containing vegetable fibers and thermoplastic resin fibers to form a pre-board 21P having a plurality of groove portions 22 extending to the outer edge portion on one surface; a waterproof film attaching step of attaching the waterproof film 25 to the surface of the pre-board 21P where the plurality of groove portions 22 are formed to form a pre-board 21F with a waterproof film in a state where the plurality of groove portions 22 are blocked by the waterproof film 25; and a hot press forming step of heating the pre-board 21F with a waterproof film and press-forming it so that the plurality of groove portions 22 collapse, which are executed in order.

[0031] According to the above manufacturing method, even when the ornament board 20 is manufactured including the hot press forming step (when reheating the pre-board 21F with a waterproof film), during heating in the hot press forming step, when the temperature rises to the temperature at which the resin in the pre-board 21P melts, gas such as water vapor generated from the pre-board 21P (vegetable fibers) is discharged to the outside from the outer edge of the pre-board 21F with a waterproof film through a tubular portion (space S) formed between the plurality of groove portions 22 of the pre-board 21P and the waterproof film 25. Therefore, when the pre-board 21F with a waterproof film is heated to the temperature at which the resin melts and press-formed so that the plurality of groove portions 22 collapse, almost no gas remains between the pre-board 21P and the waterproof film 25, and thus it is possible to suppress the occurrence of whitening on the ornament board 20 due to gas accumulation between the base material 21 and the waterproof film 25 after press forming.

[0032] Also, in the pre-board forming step, the plurality of groove portions 22 are formed by transferring a transfer sheet 35 disposed between a press die 30 for forming the pre-board 21P and the fiber mat 21M. With such a configuration, the groove portions 22 can be formed.

[0033] Further, the plurality of groove portions 22 may be arranged, for example, in a lattice pattern or in a stripe pattern.

[0034] Thus, according to the present embodiment, it is possible to provide a method for manufacturing the ornament board 20 that is less likely to undergo whitening.

Examples

[0035] Hereinafter, based on the examples, the technology disclosed in this specification will be described more specifically. Note that the technology disclosed in this specification is not limited by these examples in any way.

[0036] 〔Example 1〕 In the pre-board forming step described above, as the pre-board 21P, one having a plurality of groove portions 22 arranged in a lattice pattern in the vertical and horizontal directions on one of its surfaces was produced (see FIG. 6). The width L1 of the groove portion 22 of the pre-board 21P of Example 1 was 1.0 mm, the plate thickness L2 of the portion where the groove portion 22 was formed was 2.5 mm, the width L3 of the ridge portion 23 was 5.0 mm, and the plate thickness L4 of the ridge portion 23 was 2.8 mm (see FIG. 10).

[0037] 〔Example 2〕 A pre-board 21P similar to that of Example 1 was produced except that the width of the groove portion 22 was 0.5 mm.

[0038] 〔Example 3〕 A pre-board 21P similar to that of Example 1 was produced except that the width of the groove portion 22 was 2.0 mm.

[0039] 〔Example 4〕 In the pre-board forming step described above, as the pre-board 21P, one having a plurality of groove portions 22 arranged in a stripe pattern on one of its surfaces was produced (see FIG. 7). The width L1 of the groove portion 22 of the pre-board 21P of Example 4 was 2.0 mm, the plate thickness L2 of the portion where the groove portion 22 was formed was 2.5 mm, the width of the ridge portion 23 was 5.0 mm, and the plate thickness of the ridge portion 23 was 2.8 mm.

[0040] 〔Comparative Example 1〕 A pre-board 21P similar to that of Example 1 was produced, except that the plate thickness L4 of the ridge portion 23 was 2.6 mm.

[0041] 〔Comparative Example 2〕 A pre-board 21P similar to that of Example 1 was produced, except that the plate thickness L4 of the ridge portion 23 was 3.0 mm.

[0042] 〔Comparative Example 3〕 A pre-board 21P similar to that of Example 1 was produced, except that the width L1 of the groove portion 22 was 3.0 mm.

[0043] 〔Comparative Example 4〕 A pre-board 21P similar to that of Example 1 was produced, except that the width L1 of the groove portion 22 was 0.5 mm and the width L3 of the ridge portion 23 was 10.0 mm.

[0044] 〔Comparative Example 5〕 A pre-board 21P similar to that of Example 4 was produced, except that the width L1 of the groove portion 22 was 1.0 mm.

[0045] 〔Comparative Example 6〕 A pre-board 21P similar to that of Example 4 was produced, except that the plate thickness L4 of the ridge portion 23 was 3.0 mm.

[0046] 〔Comparative Example 7〕 A pre-board 21P similar to that of Example 4 was produced, except that the width L1 of the groove portion 22 was 3.0 mm.

[0047] From the pre-boards 21P of the above-described Examples 1 to 4 and Comparative Examples 1 to 7, waterproof film-attached pre-boards 21F were produced by the above-described waterproof film attachment process, and then heat press molding was performed as described in the above-described ornament molding process, and in each case, ornament boards 20 having a plate thickness L5 (see Figure 2) of 2.3 mm were produced. The obtained ornament boards 20 were evaluated for the following items.

[0048] <Evaluation 1: Whitening> Each test piece of the pre-board 21F with a waterproof film made at 250×200 mm was heated and pressed in a flat molding die at a temperature of 235 degrees for 90 seconds to raise the internal temperature of the test piece to 170 degrees, and it was visually confirmed whether there was a whitened portion on the surface of each test piece after cooling. · Evaluation criteria for whitening "〇"... Whitening was not confirmed. "×"... Whitening was confirmed.

[0049] <Evaluation 2: Presence or absence of wrinkles> It was visually confirmed whether wrinkles or wrinkle patterns were generated on the surface of the test piece after cooling. · Evaluation criteria for the presence or absence of wrinkles "〇"... Wrinkles were not confirmed. "×"... Wrinkles were confirmed.

[0050] The evaluation results of the above-mentioned Evaluations 1 and 2 are shown in the table of Fig. 17. As shown in the table, when the pattern of the groove portion 22 is in a lattice shape, for the test pieces of Examples 1 to 3 where the width L1 of the groove portion 22 is in the range of 0.5 to 2.0 mm, the plate thickness L2 of the portion where the groove portion 22 is provided is 2.5 mm, and the width L3 of the ridge portion 23 is 5.0 mm and the plate thickness L4 of the portion made into the ridge portion 23 is 2.8 mm, neither whitening nor wrinkles occurred. That is, it is considered that the gas generated from the pre-board 21P is discharged to the outside through the tubular space S during heating, and when the pre-board 21F with a waterproof film is press-molded, the groove portion 22 was neatly crushed (see Fig. 2).

[0051] On the other hand, in Comparative Example 1 where the plate thickness L4 of the ridge portion 23 was as thin as 2.6 mm, Comparative Example 3 where the width L1 of the groove portion 22 was as wide as 3.0 mm, and Comparative Example 4 where the width L3 of the ridge portion 23 was as wide as 10.0 mm, whitening occurred. Also, in Comparative Example 2 where the plate thickness of the ridge portion 23 was as thick as 3.0 mm and Comparative Example 3 where the width L1 of the groove portion 22 was as wide as 3.0 mm, wrinkles or wrinkle patterns occurred.

[0052] In Comparative Example 1, the depth (L4 - L2) of the groove portion 22 was shallow. In Comparative Example 4, the width of the groove portion 22 was too small and the number of the groove portions 22 was also small. Therefore, the total cross-sectional area of the tubular space S became small, and the gas generated from the pre-board 21P could not be sufficiently discharged, which is considered to have caused whitening. Further, in Comparative Example 3, since the groove width L1 was too large, the waterproof film 25 was bent and the cross-sectional area of the tubular space S became small (see FIG. 13), and the gas generated from the pre-board 21P could not be sufficiently discharged, which is considered to have caused whitening. In Comparative Example 2, the depth (L4 - L2) of the groove portion 22 was too deep and the groove portion 22 was not neatly crushed (see FIGS. 15 and 16), so it is considered that a wrinkle pattern occurred. Furthermore, in Comparative Example 3, since the groove width L1 was too large, the waterproof film 25 was bent during heat press forming and could not be neatly formed, and wrinkles are considered to have occurred (FIGS. 13 and 14).

[0053] On the other hand, when the pattern of the groove portion 22 was striped, for the test piece of Example 4 in which the width L1 of the groove portion 22 was 2.0 mm, the plate thickness L2 of the portion where the groove portion 22 was provided was 2.5 mm, and the width L3 of the ridge portion 23 was 5.0 mm and the plate thickness L4 of the portion that was the ridge portion 23 was 2.8 mm, neither whitening nor wrinkles occurred. That is, it is considered that the gas generated from the pre-board 21P was discharged to the outside through the tubular space S during heating, and when the pre-board 21F with the waterproof film was press formed, the groove portion 22 was neatly crushed (see FIG. 2).

[0054] In contrast, whitening occurred in Comparative Example 5 in which the width L1 of the groove portion 22 was as small as 1.0 mm and Comparative Example 7 in which the width L1 of the groove portion 22 was as large as 3.0 mm. Further, in Comparative Example 6 in which the plate thickness of the ridge portion 23 was as thick as 3.0 mm and Comparative Example 7 in which the width L1 of the groove portion 22 was as wide as 3.0 mm, wrinkles or a wrinkle pattern occurred. In Comparative Example 6, the depth (L4 - L2) of the groove portion 22 was too deep and the groove portion 22 was not neatly crushed (FIGS. 15 and 16), so it is considered that a wrinkle pattern occurred. In Comparative Example 7, since the width L1 of the groove portion 22 was too large and the waterproof film 25 was bent and the groove portion 22 was not neatly crushed (see FIGS. 13 and 14), it is considered that wrinkles occurred.

[0055] <Other Embodiments> The technology disclosed in this specification is not limited to the embodiments described by the above description and drawings. For example, the following embodiments are also included in the technical scope.

[0056] (1) In the above embodiment, the groove portions 22 formed in the pre-board are shown in a lattice form and a stripe form. However, the groove portions may be in any form. The key is that at least one end of the groove portion extends to the outer edge of the pre-board.

[0057] (2) The above embodiment shows a form in which a plurality of groove portions 22 are formed in the pre-board 21P by transferring a transfer sheet 35 in a form in which a plurality of standing walls 37 rise from a base portion 36. However, for example, a large number of groove portions can also be formed in the pre-board by using a transfer portion made of a PET film subjected to embossing or a mesh-type Teflon (registered trademark) sheet.

[0058] (3) In the above embodiment, in the pre-board forming step, the pre-board 21P having a plurality of groove portions 22 is formed by pressing a fiber mat 21M with a pair of press dies 30 (an upper die 31 and a lower die 32) via a transfer sheet 35. However, the pre-board can also be formed by passing it through while being pressed between two conveyor belts 60 (see FIG. 18). In such a case, a transfer portion 61 can be provided on the conveyor belt 60, or a separate transfer portion can be provided between the fiber mat 21M and the conveyor belt 60 to produce a pre-board 21P having a plurality of groove portions 22.

[0059] (4) In the above embodiment, a pre-board 21F with a waterproof film is produced by directly laminating a waterproof film 25 on the surface of a base material 21. However, for example, a form in which a colored spunbond is interposed between the base material and the waterproof film is also included in the technical scope.

[0060] (5) In the above embodiment, the waterproof film 25 is shown in a three-layer structure, but the waterproof film is not limited to the above embodiment, and a single-layer, two-layer, four-layer or more layer film may be used.

[0061] (6) In the above embodiment, the ornament board 20 covered with the waterproof film 25 only on one side of the base material 21 is shown, but depending on the application, a vegetable fiber-containing resin board in which both the front and back surfaces of the base material are covered with a waterproof film can also be used.

[0062] (7) In the above embodiment, the ornament board 20 of the door trim 10 for a vehicle is exemplified as the vegetable fiber-containing resin board, but the technology disclosed in this specification is not limited to the ornament board 20 of the vehicle, and other vehicle interior materials such as pillar garnishes, ceiling materials, console boxes, dashboards, various instrument panels, deck trims, etc. In addition to vehicle interior materials, it can be variously modified and applied in vehicle interior materials for railways, airplanes, ships, etc., and applications other than vehicle interior materials.

Explanation of reference numerals

[0063] 10: Door trim 11: Trim board 20: Ornament board 21: Base material 21F: Pre-board with waterproof film 21M: Fiber mat 21P: Pre-board 22: Groove portion 23: Ridge portion 25: Waterproof film 30, 40: Press mold 35: Transfer sheet (transfer portion) 36: Base portion 37: Upright wall 50: Molding die 60: Conveyor belt 61: Transfer portion

Claims

1. A method for manufacturing a plant fiber-containing resin board, comprising a base material containing plant fibers and a thermoplastic resin, and a waterproof film having waterproof properties covering at least one surface of the base material, wherein: a pre-board forming step of heating and pressing a fiber mat containing the plant fibers and thermoplastic resin fibers to form a pre-board having a plurality of groove portions extending to the outer edge portion on at least one surface; a waterproof film attaching step of attaching the waterproof film to the surface of the pre-board on which the plurality of groove portions are formed to form a pre-board with a film in a state where the plurality of groove portions are blocked by the waterproof film; a heating press forming step of heating the pre-board with a film and press-forming it so that the plurality of groove portions are crushed, and sequentially executing the steps. A method for manufacturing a plant fiber-containing resin board.

2. The method for manufacturing a plant fiber-containing resin board according to claim 1, wherein in the pre-board forming step, the plurality of groove portions are formed by transferring a transfer portion disposed between a press mold for forming the pre-board and the fiber mat.

3. In the pre-board forming step, the fiber mat is heated and pressed by passing between two conveyor belts arranged to face each other, The method for manufacturing a plant fiber-containing resin board according to claim 1, wherein the plurality of groove portions are formed by transferring a transfer portion disposed between the conveyor belt and the fiber mat.

4. The method for manufacturing a plant fiber-containing resin board according to any one of claims 1 to 3, wherein the plurality of groove portions are arranged in a lattice pattern.

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