JP2017218530A - Fiber-reinforced composite material and method for producing fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the thickness while improving the strength of a material.SOLUTION: A fiber-reinforced composite material has fibers forming fabric, a coating layer formed of a cellulose nanofiber covering the periphery of the respective fibers, and a resin part entering between the fibers covered with the coating layer. The cellulose nanofiber can improve the strength of the fiber-reinforced composite material by forming a coating layer in the periphery of the respective fibers, and can respond to reduction in the thickness. The strength is improved by providing the coating layer to suppress an increase in the basis weight of the fiber, which can suppress shrinkage of the resin and reduce an amount of unevenness of the surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fiber reinforced composite material and a method for producing a fiber reinforced composite material.

  Conventionally, various fiber-reinforced composite materials have been proposed. For example, a carbon fiber reinforced composite material in which a carbon fiber layer or a thermosetting resin layer is laminated is known (see Patent Document 1). Also known is a fiber-reinforced composite material comprising a reinforced fiber base material on which a woven fabric having a thermoplastic resin portion formed by attaching a thermoplastic resin to the surface and a matrix resin made of a thermosetting resin. (See Patent Document 2). Furthermore, a fiber reinforced resin composite is known in which a fiber reinforced resin is reinforced by a reinforcing material that is contained in an epoxy resin in a state where cellulose nanofibers are defibrated (Patent Document 3).

JP 2010-280903 A International Publication WO2012 / 066872 International Publication No. WO2015 / 019679

  By the way, conventionally known fiber reinforced composite materials (FRP: Fiber-Reinforced Plastics) obtained by impregnating a fabric with a resin are used in various applications. However, when such an FRP is used in a housing of a mobile device such as a wearable PC (Personal Computer), a smartphone, or a tablet terminal, the following inconvenience is assumed. Conventional FRP may have a low hardness and strength of the resin portion, and may be difficult to be molded into a thin wall. When used in a housing of a mobile device or the like that is required to be reduced in size and thickness, the problem of insufficient strength due to thinning becomes significant. Further, in order to improve the strength of FRP, it is conceivable to increase the thickness of the fiber bundle impregnated with the resin, but there is a concern that the amount of unevenness on the surface of the FRP increases due to the increase of resin sink as a contradiction. . Increasing the thickness of the fiber bundle and increasing the amount of irregularities on the surface of the FRP also hinders material thickness reduction.

  Patent Documents 1 to 3 do not improve these points, and if Patent Document 2 tries to improve the strength by using a laminated structure, the thickness of the material increases. End up. As described above, any document has room for improvement from the viewpoint of reducing the thickness while improving the strength of the material.

  In one aspect, it is an object of the fiber-reinforced composite material and the method for manufacturing a fiber-reinforced composite material disclosed in this specification to reduce the thickness while improving the strength of the material.

  The fiber-reinforced composite material disclosed in this specification includes a fiber forming a fabric, a coating layer of cellulose nanofibers covering the periphery of each of the fibers, and the fibers covered by the coating layer. And an intruding resin portion.

  The method for producing a fiber-reinforced composite material disclosed in the present specification includes a step of forming a fabric with fibers, and a step of passing a cellulose nanofiber solution through the fabric to form a coating layer of cellulose nanofibers around the fibers. And impregnating the fabric with the covering layer formed around the fibers with a resin.

  According to the fiber-reinforced composite material and the method for producing the fiber-reinforced composite material disclosed in this specification, it is possible to reduce the thickness while improving the strength of the material.

FIG. 1 (A) is an explanatory view schematically showing a schematic configuration of the fiber-reinforced composite material of the first embodiment, and FIG. 1 (B) is an enlarged view of a part of the fiber-reinforced composite material of the first embodiment. It is explanatory drawing shown. 2A-1 is an explanatory diagram schematically illustrating a state in which two pieces of fabric are overlapped, and FIG. 2A-2 is an explanatory diagram illustrating a part of the fabric in an enlarged manner. (B) is explanatory drawing which shows typically a mode that a cellulose nanofiber solution is allowed to pass (impregnation) in a fabric. Fig. 3 (A-1) is an explanatory view schematically showing a state in which a coating layer is formed around the fibers forming the fabric, and Fig. 3 (A-2) is an enlarged view showing a part of the fabric. FIG. 3 (B) is an explanatory diagram schematically showing how a fabric is impregnated with resin. FIG. 4 (A) is an explanatory view schematically showing a state in which a fabric is placed on a filter paper laid on a porous plate, and FIG. 4 (B) is an illustration showing a state in which a cellulose nanofiber solution is poured onto the fabric. FIG. 4 (C) is an explanatory view schematically showing a state of sucking the cellulose nanofiber solution. FIG. 5 is an explanatory view schematically showing how the fabric is impregnated with resin. FIG. 6 is an explanatory view schematically showing a schematic configuration of the fiber-reinforced composite material of the second embodiment. FIG. 7 (A) is an explanatory view schematically showing a state in which the fabric is placed on a filter paper laid on a porous plate, and FIG. 7 (B) is an illustration showing a state in which the cellulose nanofiber solution is poured onto the fabric. FIG. 7C is an explanatory view schematically showing a state in which the cellulose nanofiber solution is sucked.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the dimensions, ratios, and the like of each part may not be shown so as to completely match the actual ones. Further, depending on the drawings, components that are actually present may be omitted for convenience of explanation, or dimensions may be exaggerated from the actual drawing.

(First embodiment)
First, a schematic configuration of the fiber-reinforced composite material 1 according to the first embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 (A) is an explanatory view schematically showing a schematic configuration of the fiber-reinforced composite material of the first embodiment, and FIG. 1 (B) is an enlarged view of a part of the fiber-reinforced composite material of the first embodiment. It is explanatory drawing shown. 2A-1 is an explanatory diagram schematically illustrating a state in which two pieces of fabric are overlapped, and FIG. 2A-2 is an explanatory diagram illustrating a part of the fabric in an enlarged manner. (B) is explanatory drawing which shows typically a mode that a cellulose nanofiber solution is allowed to pass (impregnation) in a fabric. Fig. 3 (A-1) is an explanatory view schematically showing a state in which a coating layer is formed around the fibers forming the fabric, and Fig. 3 (A-2) is an enlarged view showing a part of the fabric. FIG. 3 (B) is an explanatory diagram schematically showing how a fabric is impregnated with resin. FIG. 4 (A) is an explanatory view schematically showing a state in which a fabric is placed on a filter paper laid on a porous plate, and FIG. 4 (B) is an illustration showing a state in which a cellulose nanofiber solution is poured onto the fabric. FIG. 4 (C) is an explanatory view schematically showing a state of sucking the cellulose nanofiber solution. FIG. 5 is an explanatory view schematically showing how the fabric is impregnated with resin. In addition, it is assumed that the fiber reinforced composite material 1 of this embodiment is used as a material for a housing of a mobile device, and is formed into a plate shape.

  Referring to FIG. 1 (A), the fiber reinforced composite material 1 includes a fabric 201. The fabric 201 in the present embodiment is a woven fabric formed by weaving the fibers 2. More specifically, the fabric 201 is formed by weaving a fiber bundle 21 in which a plurality of fibers 2 are bundled as warp and weft. As a method for forming the fabric 201, various conventionally known methods can be employed. Moreover, in this embodiment, although carbon fiber is employ | adopted as the fiber 2, conventionally well-known inorganic fiber, such as glass fiber, and organic fiber can also be employ | adopted. Moreover, you may employ | adopt metal wires, such as gold | metal | money, copper, and nickel. Furthermore, these may be used in combination as appropriate. In addition, in this embodiment, although the fabric 201 is used as two sheets piled up, the number of sheets to pile up can be suitably selected according to a use.

  Referring to FIG. 1B, a coating layer 3 is provided around each of the fibers 2. The coating layer 3 is formed of cellulose nanofibers (hereinafter referred to as CNF). The covering layer 3 covers the periphery of the individual fibers 2. In this way, each individual fiber 2 is coated with CNF, whereby each individual fiber 2 is reinforced, and thereby the strength of the fabric 201 is improved. As a result, the strength of the fiber reinforced composite material 1 is improved. If the strength of the fiber reinforced composite material 1 itself is improved, the required strength can be secured even when the fiber reinforced composite material 1 is molded into a thin wall.

  Referring to FIGS. 1A and 1B, the fiber reinforced composite material 1 includes a resin portion 4 entering between the fibers 2. The resin portion 4 forms the surface of the fiber reinforced composite material 1. That is, the resin part 4 is formed in a layer shape and has a smooth surface 1 a exposed on one surface side of the fabric 201. The resin portion 4 may be exposed to at least one surface side of the fabric 201 to form a smooth surface. In the present embodiment, as shown in FIG. It has a smooth surface 1b exposed on the surface side. The resin part 4 prevents the cloth 201 from being exposed by forming the smooth surfaces 1a and 1b outside the cloth 201.

  The resin portion 4 enters the fiber bundle 21 and fills not only between the fibers 2 but also between the fiber bundles 21. Thereby, it is avoided that a cavity is formed inside the fiber reinforced composite material 1, and the strength is increased.

  Although the resin part 4 forms the smooth surfaces 1a and 1b which become the surface of the fiber reinforced composite material 1, the resin part 4 of this embodiment can suppress the occurrence of sink marks, and the fiber reinforced composite material 1 The amount of surface irregularities can be reduced. This is because the fiber 2 itself is reinforced, so that it is not necessary to increase the basis weight for securing the strength. If the basis weight is increased and the fiber amount is increased in order to improve the strength of the material, the fiber bundle becomes thicker. When the thickness of the fiber bundle is increased, irregularities are likely to appear on the surface of the material. In the fiber reinforced composite material 1 of the present embodiment, since the strength can be improved without increasing the basis weight, the occurrence of unevenness on the material surface can be suppressed. In addition, if the weight per unit area is increased and the thickness of the fiber bundle is increased, the thickness of the resin portion covering this is also increased, which hinders thinning, but in this embodiment, there is no such inconvenience, Thinning can be achieved.

  Below, the manufacturing method of the fiber reinforced composite material 1 is demonstrated. First, as shown in FIG. 2 (A-1), two pieces of fabric 200, which is a woven fabric obtained by weaving the fiber bundle 20 in which the fibers 2 are bundled as warp and weft, are stacked. At the stage shown in FIG. 2 (A-1), the fiber 2 is not covered with the coating layer 3 as shown in an enlarged view in FIG. 2 (A-2). For this reason, different reference numbers are used to distinguish uncovered fiber bundles and fabrics from fiber bundles 21 and fabrics 201 formed by the fibers 2 coated with the coating layer 3. That is, reference numerals 20 and 200 are assigned to fiber bundles and fabrics that do not include the coating layer 3, respectively.

  Referring to FIG. 2 (B), as indicated by arrow 7, the CNF solution 8 is supplied to the fabric 200 and allowed to pass therethrough. As a result, the fabric 200 is impregnated with CNF, and the coating layer 3 of CNF is formed around the fibers 2. Here, the formation of the coating layer 3 will be specifically described with reference to FIGS. Referring to FIG. 4A, a filter paper is laid on a porous plate 10 having a smooth upper surface, and a two-ply fabric 200 is placed thereon. Here, the porous plate 10 is used for sucking the CNF solution 8 from the lower side. In addition, as long as the CNF solution 8 can be sucked from the lower side, a plate material made of another material may be used. For example, a punching metal provided with a plurality of fine holes may be used.

  After the fabric 200 is placed on the filter paper as shown in FIG. 4A, the CNF solution 8 is supplied from above the fabric 200 as shown by an arrow 7 in FIG. Since the CNF solution 8 is stored on the filter paper 9, the fabric 200 is impregnated with the CNF solution 8. As indicated by an arrow 11 in FIG. 4C, suction is performed from below the porous plate 10, and the CNF solution 8 is extracted so as to pass through the gap 6 in the fabric 200. In the present embodiment, a CNF 1% aqueous solution was used as the CNF solution 8, and after impregnation, the process of drying at 120 ° C. for 1 hour was repeated five times. Alternatively, the CNF solution 8 may be applied on the filter paper 9, the fabric 200 may be immersed therein, and then sucked.

  By passing through such a process, as shown in FIG. 3 (A-1) and FIG. 3 (A-2), the coating layer 3 by CNF is formed around the fiber 2. As a result, the fiber bundle 20 and the fabric 200 in which the coating layer 3 is not formed become the fiber bundle 21 and the fabric 201 in which the coating layer 3 is formed, respectively. Note that the CNF solution 8 is allowed to pass through the fabric 200 because the coating layer 3 is formed by the CNF solution 8 and the coating layer 3 is formed as shown in FIGS. 3A-1 and 3A-2. This is because the gap 6 a is formed between the formed fibers 2 and between the fiber bundles 21. After the coating layer 3 is formed around the fibers 2, the fabric 201 is impregnated with resin as shown in FIG. The resin part 4 enters the gap 6a. Here, the formation of the resin portion 4 will be described with reference to FIG.

  In this embodiment, the resin part 4 is formed by pressing the TPU (thermoplastic polyurethane) resin sheet 12 against the fabric 201 using the upper mold 13a and the lower mold 13b, and at the same time, a prepreg plate is obtained. That is, the TPU resin sheet 12 is installed on the lower mold 13b, and the fabric 201 is placed thereon. Then, using the upper mold 13a and the lower mold 13b, the impregnation of the resin and the molding of the prepreg plate are simultaneously performed under the conditions of a press temperature of 180 ° C., a pressure of 5 MPa, and a holding time of 5 minutes. As a result, a fiber-reinforced composite material 1 having a thickness of 0.5 mm, a surface unevenness of 3 μm, and a flexural modulus of 43 GPa could be obtained. In addition, when a TPU resin sheet is pressed under the same pressure condition on a fabric 200 not provided with the coating layer 3 to form a resin part and a 0.5 mm thick plate is obtained, the surface unevenness amount is 60 μm, bending A fiber-reinforced composite material having an elastic modulus of 38 GPa was obtained (comparative example). According to this embodiment, the fiber reinforced composite material 1 having higher strength and less surface unevenness than the comparative example could be obtained.

  In this embodiment, the sheet-like resin, that is, the TPU resin sheet 12 is used, but the molding method of the resin portion 4 is not limited to this, and other conventionally known methods may be adopted. For example, you may apply | coat resin and may transfer to a press process after that.

  According to the fiber-reinforced composite material 1 of the present embodiment, it is possible to reduce the thickness while improving the strength of the material. For this reason, even if it is a case where the housing | casing reduced in size and thickness, such as a mobile apparatus, was created using the fiber reinforced composite material 1 of this embodiment, intensity | strength is securable. In addition, since the strength can be ensured without increasing the amount of the fiber bundle 21, the fiber bundle 21 can be formed thinly. As a result, the amount of unevenness on the surface can be reduced, and the thickness can be easily reduced. Can be

(Second Embodiment)
Next, the second embodiment will be described with reference to FIGS. 6 to 7C. FIG. 6 is an explanatory view schematically showing a schematic configuration of the fiber-reinforced composite material of the second embodiment. FIG. 7 (A) is an explanatory view schematically showing a state in which the fabric is placed on a filter paper laid on a porous plate, and FIG. 7 (B) is an illustration showing a state in which the cellulose nanofiber solution is poured onto the fabric. FIG. 7C is an explanatory view schematically showing a state in which the cellulose nanofiber solution is sucked.

  The fiber-reinforced composite material 14 according to the second embodiment includes a cellulose nanofiber (CNF) portion 15 formed in a layer shape. The CNF portion 15 has a smooth surface 15b exposed on at least one surface side of the fabric 201. That is, the smooth surface 1b in the first embodiment is formed by exposing the resin portion 4, but the smooth surface 15b of the present embodiment is formed by exposing the CNF portion 15.

  The smooth surface 15b has a smaller surface irregularity and a high hardness. This is because the smooth surface 15 b is formed by the CNF portion 15. CNF is less prone to unevenness than resin. This is because the CNF itself is a fiber, and so to speak, because the CNF portion 15 is formed by laminating the fibers, so that unevenness is not easily generated. Further, since the dried CNF has a higher hardness than the resin, the smooth surface 15b has a high hardness. Due to such properties, the fiber reinforced composite material 14 is easily thinned.

  Further, since the smooth surface 15b has high hardness, it can be used as it is as an outer peripheral wall surface of the housing without undergoing a process such as painting. In this case, since CNF has high translucency and can observe the cloth 201 existing inside, the eyes of the cloth 201 inside can be used as a design of the casing without applying the coating to the smooth surface 15b.

  Such a CNF portion 15 can be formed through the steps shown in FIGS. 7A to 7C. The steps shown in FIGS. 7A and 7B are the same as in the first embodiment, and the fabric 200 is immersed in the CNF solution 8. Then, as shown in FIG. 7C, the CNF solution is sucked from the lower side and extracted. At this time, the extraction amount of the CNF solution is adjusted so that CNF remains on the filter paper 9. The remaining CNF forms the CNF portion 15 as an anchor adhesion layer. Since the shape of the CNF portion 15 follows the smooth porous plate 10 and the filter paper 9, a smooth surface 15b is formed. Thereafter, the resin portion 4 is formed as in the first embodiment, but the resin is supplied from above. For example, the resin part 4 can be formed by arranging the TPU resin sheet 12 above the fabric 201 and performing press working. Thereby, the smooth surface 15a is formed in the back surface side of the smooth surface 15b.

  Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications, within the scope of the gist of the present invention described in the claims, It can be changed.

DESCRIPTION OF SYMBOLS 1,14 Fiber reinforced composite material 2 Fiber 20, 21 Fiber bundle 3 Coating layer 4 Resin part 6, 6a Cavity 8 CNF solution 9 Filter paper 10 Porous board 12 TPU resin sheet 15 CNF part 200 Fabric

Claims (5)

The fibers forming the fabric,
A coating layer of cellulose nanofibers covering the periphery of each of the fibers;
A resin portion entering between the fibers covered by the coating layer;
A fiber reinforced composite material.   The fiber-reinforced composite material according to claim 1, wherein the resin portion is formed in a layer shape and has a smooth surface exposed at least on one surface side of the fabric.   The fiber-reinforced composite material according to claim 1, comprising a cellulose nanofiber portion formed in a layered manner.   The fiber-reinforced composite material according to claim 3, wherein the cellulose nanofiber portion has a smooth surface exposed at least on one surface side of the fabric. Forming a fabric with fibers;
Passing a cellulose nanofiber solution through the fabric to form a coating layer of cellulose nanofibers around the fibers;
Impregnating the fabric with the covering layer formed around the fibers with a resin;
A method for producing a fiber-reinforced composite material.

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