Composite material and molded product

Abstract

To provide a composite material and a molded product having high mechanical strength and at least one of high electrical conductivity and high thermal conductivity.SOLUTION: A composite material includes: a resin matrix; and a plurality of metal fibers dispersed in the matrix. Each of the plurality of metal fibers includes: a steel core wire; and a coating layer covering the core wire and made of at least one material selected from the group consisting of copper, aluminum, and a copper-zinc alloy.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to composites and compacts. [Background technology]

[0002] A composite material containing a resin matrix and metal fibers is known (see, for example, Patent Document 1). In the composite material described in Patent Document 1, metal fibers are dispersed in the matrix. The metal fibers are made of stainless steel. The mechanical strength (tensile strength and Young's modulus) of stainless steel is higher than the mechanical strength of resin. Therefore, the mechanical strength of the composite material is also higher than the mechanical strength of resin. The composite material is molded into a molded body. This molded body also has excellent mechanical strength. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-13693 Summary of the Invention [Problem to be solved by the invention]

[0004] Depending on the application and purpose of the composite material and molded article, at least one of high electrical conductivity and high thermal conductivity is required in addition to improved mechanical strength. Here, mechanical strength refers to tensile strength, yield strength, stiffness (Young's modulus), etc.

[0005] An object of the present disclosure is to provide a composite material and a molded article that have high mechanical strength and at least one of high electrical conductivity and high thermal conductivity. [Means for solving the problem]

[0006] A composite material according to the present disclosure includes a resin matrix and a plurality of metal fibers dispersed in the matrix, each of which includes a steel core wire and a coating layer covering the core wire and made of at least one material selected from the group consisting of copper, aluminum, and a copper-zinc alloy. [Effects of the Invention]

[0007] The composites and compacts according to the present disclosure have high mechanical strength, while also having at least one of high electrical conductivity and high thermal conductivity. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of the composite material and the molded body according to the first embodiment. [Figure 2] FIG. 2 is a schematic diagram of metal fibers contained in the composite material shown in FIG. [Figure 3] FIG. 3 is a schematic diagram of the metal fiber in the second embodiment. [Figure 4] FIG. 4 is a schematic diagram of metal fibers in a modified example of the second embodiment. [Figure 5] FIG. 5 is a schematic diagram of metal fibers in another modified example of the second embodiment. [Figure 6] FIG. 6 is a schematic diagram of the metal fiber in the third embodiment. [Figure 7] FIG. 7 is a schematic diagram of metal fibers in a modified example of the third embodiment. [Figure 8] FIG. 8 is a schematic diagram of the metal fiber according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and explained. (1) A composite material includes a resin matrix and a plurality of metal fibers dispersed in the matrix, each of which includes a steel core wire and a coating layer covering the core wire and made of at least one material selected from the group consisting of copper, aluminum, and a copper-zinc alloy.

[0010] In the composite material of the present disclosure, the core wire of the metal fiber is made of steel, and the coating layer is made of at least one selected from the group consisting of copper, aluminum, and a copper-zinc alloy. Steel has relatively high rigidity. The electrical conductivity of at least one selected from the group consisting of copper, aluminum, and a copper-zinc alloy is higher than that of steel. The thermal conductivity of at least one selected from the group consisting of copper, aluminum, and a copper-zinc alloy is higher than that of steel. Therefore, the composite material and the molded product have high mechanical strength and at least one of high electrical conductivity and high thermal conductivity.

[0011] The specific gravity of steel differs from the specific gravity of at least one metal selected from the group consisting of copper, aluminum, and copper-zinc alloys. Therefore, if steel fibers and fibers made of one of these materials are dispersed separately in a resin, the fibers with a larger specific gravity will settle due to the difference in specific gravity. As a result, composites containing steel fibers, the above-mentioned fibers, and a resin can have heterogeneous mechanical strength and electrical conductivity, heterogeneous mechanical strength and thermal conductivity, or heterogeneous mechanical strength, electrical conductivity, and thermal conductivity. However, in the composite material disclosed herein, each of the multiple metal fibers includes a steel core and a coating layer made of at least one material selected from the group consisting of copper, aluminum, and copper-zinc alloys. This ensures that the specific gravity of the metal fibers is uniform, suppresses sedimentation, and allows the metal fibers to be uniformly dispersed in the resin. This results in homogeneous mechanical strength and electrical conductivity, or homogeneous mechanical strength and thermal conductivity. Furthermore, the heterogeneous mechanical strength, electrical conductivity, and thermal conductivity result in stable quality.

[0012] Since the covering layer covers the core wire, the contact area of ​​the covering layer with the matrix is ​​larger than the contact area of ​​the metal fibers made of copper, aluminum, and copper-zinc alloy with the matrix when the weights of the copper, aluminum, and copper-zinc alloy are the same, so the covering layer has at least one of high electrical conductivity and high thermal conductivity.

[0013] (2) In the above (1), the metal fibers may include straight portions. When this configuration is adopted, the composite material has high rigidity.

[0014] (3) In the above (1) or (2), the metal fibers may include bent portions. When this configuration is adopted, it is possible to suppress delamination or slippage at the interface between the metal fibers and the matrix. In other words, the grip of the metal fibers on the matrix is ​​strong. Therefore, the composite has high mechanical strength.

[0015] The molded body of the present disclosure is (4) The composite material is made of the composite material according to any one of (1) to (3) above. Therefore, the composite material has high mechanical strength and at least one of high electrical conductivity and high thermal conductivity.

[0016] [Details of the embodiments of the present disclosure] Embodiments of a composite material and a molded body of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram of a composite material and a molded body of this embodiment 1. Fig. 2 is a schematic diagram of metal fibers contained in the composite material shown in Fig. 1. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and their description will not be repeated.

[0017] (Embodiment 1) The composite material 1 in the present embodiment 1 includes a resin matrix 2 and a plurality of metal fibers 3. The composite material 1 can also be called a metal fiber-resin composition.

[0018] [Matrix 2] The matrix 2 is the base material of the composite material 1. The matrix 2 is made of a resin. The type of resin is appropriately selected depending on the application and purpose of the composite material 1. Examples of the resin include thermoplastic resins and thermosetting resins. A preferable example of the resin is a thermoplastic resin from the viewpoint of improving moldability. Examples of the thermoplastic resin include engineering plastics (abbreviated as "En-Pura"). Examples of the engineering plastic include polyamide (PA), polycarbonate (PC), polyoxymethylene (POM or polyacetal), modified polyphenylene ether (m-PPE or modified polyphenylene oxide), polybutylene terephthalate (PBT or poly(oxytetramethyleneoxyterephthaloyl)), polysulfone, polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). The resins can be used alone or in combination. The compounding ratio of the matrix 2 in the composite material 1 is, for example, 50% by volume or more and 99.95% by volume or less. A known additive may be added to the matrix 2 in an appropriate ratio.

[0019] [Metal Fiber 3] As shown in FIG. 1 , in the composite material 1, a plurality of metal fibers 3 are dispersed in a matrix 2. Specifically, the plurality of metal fibers 3 are present in a dispersed state in the matrix 2. The plurality of metal fibers 3 include metal fibers 3A and 3B separated by the matrix 2. Although not shown, the plurality of metal fibers 3 may include metal fibers 3 that are in contact with each other. Each of the plurality of metal fibers 3 includes a straight portion 33. In the present disclosure, the metal fiber 3 is composed of the straight portion 33. The straight portion 33 has a cylindrical shape. The straight portion 33 may have an elliptical cylindrical shape or a rectangular cylindrical shape. Preferably, the straight portion 33 has a cylindrical shape. The length of the metal fiber 3 is 0.5 mm or more and 50 mm or less. The length of the metal fiber 3 is sometimes referred to as the fiber length. The length of the metal fiber 3 is the length of the metal fiber 3 in the direction in which the straight portion 33 extends. The diameter of the metal fiber 3 is 0.05 mm or more and 5 mm or less.

[0020] As shown in FIG. 2, the metal fiber 3A includes a core wire 31 and a coating layer 32. In the present disclosure, the metal fiber 3 includes only the core wire 31 and the coating layer 32. The core wire 31 is sometimes referred to as a core or a core. The core wire 31 has a cylindrical shape. The core wire 31 may also have an elliptical cylindrical shape or a rectangular cylindrical shape. The core wire 31 is made of steel. Examples of steel include stainless steel, carbon steel, alloy steel, and spring steel.

[0021] The coating layer 32 coats the core wire 31. Specifically, the coating layer 32 coats the circumferential surface of the core wire 31. The coating layer 32 contacts the circumferential surface of the core wire 31. The coating layer 32 does not contact both end faces of the core wire 31 in the direction in which the straight portions 33 extend. Alternatively, although not shown, the coating layer 32 may contact both end faces of the core wire 31 in the direction in which the straight portions 33 extend. In other words, the coating layer 32 may coat both end faces of the core wire 31 in the direction in which the straight portions 33 extend. In the present disclosure, the coating layer 32 has a cylindrical shape. The coating layer 32 may have an elliptical cylindrical shape or a rectangular cylindrical shape. The coating layer 32 is sometimes referred to as a cover layer or clad. The circumferential surface of the coating layer 32 is exposed to the outside. The end faces of the coating layer 32 in the direction in which the straight portions 33 extend are flush with the end faces of the straight portions 33 in the direction in which the straight portions 33 extend. Examples of materials for the coating layer 32 include copper, aluminum, and copper-zinc alloys. These can be used alone or in combination. In other words, the coating layer 32 is composed of at least one material selected from the group consisting of copper, aluminum, and copper-zinc alloys. The copper-zinc alloy includes brass. The zinc content in the copper-zinc alloy is 20% by mass or more and 45% by mass or less. The thickness of the coating layer 32 is 0.1% by mass or more and 33.3% by mass or less of the wire diameter of the metal fiber 3. The thickness of the coating layer 32 is the distance from the circumferential surface of the core wire 31 to the circumferential surface of the coating layer 32 in the radial direction. Conceptually, the thickness of the coating layer 32 is the value obtained by subtracting the diameter of the core wire 31 from the wire diameter (diameter) of the metal fiber 3 and dividing the value by 2. The length of the coating layer 32 in the direction in which the straight portions 33 extend is the same as the length of the straight portions 33 in the direction in which the straight portions 33 extend.

[0022] The volume ratio of the core wire 31 in the metal fiber 3 is 11 volume % or more and 99.6 volume % or less. The volume ratio of the coating layer 32 in the metal fiber 3 is 0.4 volume % or more and 89 volume % or less. The volume ratio of the metal fiber 3 to 100 volume parts of the matrix 2 is 0.5 volume parts or more and 100 volume parts or less.

[0023] To manufacture the composite material 1, first, a resin and a plurality of metal fibers 3 are prepared. A long metal fiber 30 (see imaginary line) is prepared. The metal fiber 30 is cut so as to be divided in the longitudinal direction. In this way, a plurality of metal fibers 3 are prepared.

[0024] Thereafter, a plurality of metal fibers 3 are blended with the resin 2. If necessary, a plurality of metal fibers 3 and an additive are blended with the resin 2. At this time, the metal fibers 3 (and the additive) are blended with the resin 2 while the resin 2 is heated to a temperature equal to or higher than its softening point, and the resin 2 and the metal fibers 3 are kneaded together. The kneaded product is obtained as the composite material 1 of the present disclosure.

[0025] [Molded body 5] Thereafter, although not shown, the kneaded mixture is poured into a mold having a cavity of a predetermined shape. This results in a molded body 5 made of the composite material 1. In FIG. 1, the molded body 5 has a block shape (lump shape). Although not shown, the molded body 5 may have a sheet shape. The sheet shape includes a film shape or a tape shape.

[0026] (Embodiment 2) FIG. 3 is a schematic diagram of a metal fiber according to the second embodiment. FIG. 4 is a schematic diagram of a metal fiber according to a modification of the second embodiment. FIG. 5 is a schematic diagram of a metal fiber according to another modification of the second embodiment. As shown in FIG. 3, in the second embodiment, the metal fiber 3 has a curved portion 34 in addition to a straight portion 33. Specifically, the metal fiber 3 has an L-shape. The metal fiber 3 includes a plurality of straight portions 33A, 33B and the curved portion 34. The straight portion 33A is along a first straight line L1. The straight portion 33B is along a second straight line L2. The first straight line L1 and the second straight line L2 intersect. The straight portion 33A and the straight portion 33B each extend in a different direction from the curved portion 34. In the present disclosure, the curved portion 34 is a bending point in the metal fiber 3.

[0027] (Modification of the second embodiment) As shown in FIGS. 4 and 5, the metal fiber 3 of the modified example includes a plurality of consecutive metal fibers 3 of the second embodiment. The metal fiber 3 of the modified example of the second embodiment includes a plurality of curved portions 34A, 34B, 34C, 34D, and 34E. The straight portion 33 includes a plurality of straight portions 33A, 33B, 33C, 33D, 33E, and 34F. In the direction along which the metal fiber 3 extends, the straight portion 33A, the curved portion 34A, the straight portion 33B, the curved portion 34B, the straight portion 33C, the curved portion 34C, the straight portion 33D, the curved portion 34D, the straight portion 33E, the curved portion 34E, and the straight portion 33F are arranged in this order. In the modified example of FIG. 5, the angle between the straight portions 33A and 33B at the curved portion 34A is a right angle. The angle between the straight portions 33B and 33C at the curved portion 34B is a right angle. That is, the angle formed by the two straight portions 33 extending from the bent portion 34 is a right angle. In the modification of Fig. 5, the metal fiber 3 has a zigzag shape.

[0028] (Embodiment 3) Fig. 6 is a schematic diagram of a metal fiber in the present embodiment 3. As shown in Fig. 6, the metal fiber 3 does not include a straight portion 33, but includes a curved portion 34. In other words, the metal fiber 3 includes only the curved portion 34. In the embodiment 3, the metal fiber 3 has an arc shape.

[0029] (Modification of the third embodiment) Fig. 7 is a schematic diagram of a metal fiber according to a modification of the third embodiment. As shown in Fig. 7, the metal fiber 3 according to the modification includes a plurality of metal fibers 3 according to the third embodiment in succession. That is, the metal fiber 3 has a plurality of mutually different curved portions 34A, 34B. A line segment LL connecting the center A1 of the arc of the curved portion 34A and the center B1 of the arc of the curved portion 34B crosses the metal fiber 3. The metal fiber 3 has an inflection point 34X located at the boundary between the two curved portions 34A and 34B.

[0030] (Fourth embodiment) FIG. 8 is a schematic diagram of a metal fiber in the fourth embodiment. As shown in FIG. 8, the bent portion 34 of the metal fiber 3 has a spiral shape. The metal fiber 3 has a twisted shape. The metal fiber 3 in the fourth embodiment is produced by winding the long metal fiber 30 (virtual wire) in the first embodiment around another wire (not shown) and then dividing it in the longitudinal direction. Alternatively, the metal fiber 3 in the fourth embodiment is produced by bundling and twisting a plurality of the long metal fibers 3 (virtual wires) in the first embodiment, and then dividing the metal fibers 3 in the longitudinal direction and separating the bundled metal fibers 3.

[0031] It should be understood that the embodiments and examples disclosed herein are illustrative in all respects and are not limiting in any respect. The scope of the present invention is defined not by the above description but by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0032] 1 Composite material 2. Matrix 3,3A,3B,30 Metal fiber 31 Core Wire 32 Covering layer 33,33A,33B,33C,33D,33E,33F Straight section 34,34A,34B,34D,34E,34F curved part 34X Inflection Point 5 Molded body A1,B1 center L1 1st straight line L2 2nd straight line LL line segment

Claims

1. A resin matrix, a plurality of metal fibers dispersed in the matrix; Each of the plurality of metal fibers is A steel core wire, a coating layer covering the core wire and made of at least one material selected from the group consisting of copper, aluminum, and a copper-zinc alloy; Composite material.

2. The composite of claim 1 , wherein the metal fibers have straight portions.

3. 3. The composite material of claim 1 or claim 2, wherein the metal fibers include bends.

4. A molded article made from the composite material of claim 1.

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