JP2018104481A - Structure and composite article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-weight and high-rigidity structure capable of used also as a single material.SOLUTION: A structure is formed of reinforced fibers and a resin, where the reinforced fibers have a mass average fiber length of 1 mm or more and 15 mm or less and are bonded to each other through a resin to form a void, an existence interval of a composite body formed of the reinforced fibers and the resin in an arbitrary cross section of the structure is in a range of the interval of 10-100 μm, and the maximum length of the void is 5 μm or more and 200 μm or less.SELECTED DRAWING: None

Description

  The present invention relates to a structure composed of a resin, reinforcing fibers and voids, and a composite article thereof.

  In recent years, lightweight and highly functional materials are required for industrial products such as automobiles, aircraft, sports products, and building materials. In order to meet such demands, fiber reinforced resins that are excellent in lightness, rigidity, and strength are used in various industrial applications. For example, as a fiber reinforced resin material excellent in lightness, a porous fiber reinforced resin material composed of a reinforced fiber and a foamable resin has been studied (Patent Document 1). Since these materials have vacancies as fragile portions, the rigidity and strength are greatly inferior as a single material. For this reason, when these materials are used, they are often used as a core material having a sandwich structure by bonding with a highly rigid skin material (Patent Document 2). However, when used in combination with a high-density skin material, weight reduction due to the porous structure is greatly limited. In addition, the porous material has the characteristics that it is excellent in impact resistance, acoustic properties, thermal properties, and workability, and the properties peculiar to the porous structure are impaired by being bonded to the skin material. From the above, there is an urgent need to provide a structure capable of sufficiently expressing mechanical characteristics and various characteristics not only as a core material but also as a single material.

Japanese Patent Laid-Open No. 10-296772 International Publication No. 2014/162873

  This invention is made | formed in view of the said subject, The objective is to provide the lightweight and highly rigid structure which can be used also as a single material.

  The structure according to the present invention is a structure composed of reinforcing fibers and a resin, and the reinforcing fibers have a mass average fiber length of 1 mm or more and 15 mm or less, and form voids by bonding through a resin. The composite existing interval between the reinforcing fiber and the resin in an arbitrary cross section of the structure is within a range of 10 to 100 μm, and the maximum length of the void is 5 μm or more and 200 μm or less. It is characterized by.

  According to the present invention, a lightweight and highly rigid structure can be provided.

FIG. 1 is a schematic diagram showing a cross-sectional structure of a structure according to the present invention. FIG. 2 is a schematic view showing an example of a dispersion state of reinforcing fibers in the reinforcing fiber mat used in the present invention. FIG. 3 is a schematic diagram showing an example of a cross-sectional structure in the surface direction and thickness direction of the structure according to the present invention.

  The structure and composite article according to the present invention will be described.

  FIG. 1 is a schematic diagram showing a cross-sectional structure of a structure according to the present invention. As shown in FIG. 1, the structure 1 according to the present invention includes a resin 2, reinforcing fibers 3, and voids 4.

  Here, the mass average fiber length of the reinforcing fibers 3 is in the range of 1 mm or more and 15 mm or less. Thereby, the reinforcement efficiency of the reinforced fiber 3 can be improved, and the mechanical characteristic excellent in the structure 1 is given. When the mass average fiber length of the reinforcing fibers 3 is less than 1 mm, the voids 4 in the structure 1 cannot be efficiently formed, and thus the density may increase. In other words, the thickness of the reinforcing fiber 3 is the same as that of the desired thickness. Since it becomes difficult to obtain the structure 1, it is not desirable. On the other hand, when the mass average fiber length of the reinforcing fiber 3 is longer than 15 mm, the reinforcing fiber 3 in the structure 1 is easily bent by its own weight, which is an undesirable factor for inhibiting the expression of mechanical properties. The mass average fiber length is obtained by removing the resin component of the structure 1 by a method such as burning or elution, randomly selecting 400 from the remaining reinforcing fibers 3, measuring the length to the unit of 10 μm, and averaging them It can be calculated as a length.

  The reinforcing fibers 3 are bonded via the resin 2 to form the voids 4. For example, when the structure precursor is obtained by heating the structure precursor in which the reinforcing fiber 3 is pre-impregnated with the resin 2, the void 4 is formed by raising the reinforcing fiber 3 by melting or softening of the resin 2 accompanying the heating. The This is based on the property that in the structure precursor, the internal reinforcing fiber 3 that has been compressed by pressurization is raised by the raising force derived from its elastic modulus. By setting the resin 2, the reinforcing fiber 3, and the void 4 as described above, the structure 1 forms a strong network of the reinforcing fibers 3 while being porous, and becomes a lightweight and highly rigid structure. .

  The reinforcing fiber 3 forms the resin 2 and the composite 5 in the structure 1, and the composite 5 existence interval in the section of the structure 1 is within a range of 10 to 100 μm. By setting the existence interval of the composite 5 within the above-described range, the resin 2 and the reinforcing fiber 3 in the structure 1 can be arranged uniformly, sufficiently exhibiting mechanical characteristics, and also have functionality such as workability. improves.

  Although there is no restriction | limiting in particular as a method of measuring the space | interval of the composite_body | complex 5, For example, the method of measuring the space | interval of the composite_body | complex 5 from the surface of the structure 1 can be illustrated. In this case, it becomes easier to observe the composite 5 by polishing the surface of the structure 1 to expose the resin 2 and the reinforcing fibers 3. In an arbitrary observation cross section of the structure 1, 50 locations where the reinforcing fibers 3 and the resin 2 form the composite 5 are selected at random, and the shortest distance to another arbitrary composite 5 existing therearound is selected. The existence interval can be measured by measuring the distance.

  The maximum length of the gap 4 is not less than 5 μm and not more than 200 μm. By setting it as said range, the structure 1 can acquire the lightening effect by a space | gap to the maximum. When the maximum length of the void is less than 5 μm, it means that the volume content of the void in the case of the structure 1 is reduced, and the weight of the structure 1 is increased, which is not preferable. On the other hand, when the maximum length of the gap is longer than 200 μm, when a load is applied to the structure 1, stress is easily concentrated on the portion, which causes a decrease in strength, which is not preferable. From the viewpoint of achieving both lightness and strength, the maximum length of the void is more preferably 5 μm or more and 100 μm or less.

  Although there is no restriction | limiting in particular as a method of measuring the maximum length of the space | gap 4, For example, the method of measuring the maximum length of the space | gap 4 from the surface of the structure 1 can be illustrated. In this case, it becomes easier to observe the voids 4 by polishing the surface of the structure 1 to expose the resin 2 and the reinforcing fibers 3. It can be measured by arbitrarily selecting 50 voids 4 in an arbitrary observation cross section of the structure 1 and measuring the maximum length of the voids.

When the bending elastic modulus of the structure 1 is Ec and the density of the structure 1 is ρ, the specific bending rigidity of the structure 1 expressed as Ec ^1/3 · ρ ⁻¹ is in the range of 3 or more and 20 or less. Preferably there is. By setting it as said range, the structure 1 can acquire the sufficient weight reduction effect.

  Here, examples of the resin 2 include a thermoplastic resin and a thermosetting resin. In the present invention, a thermosetting resin and a thermoplastic resin may be blended.

  In one embodiment of the present invention, the resin 2 preferably includes at least one kind of thermoplastic resin. Thermoplastic resins include “polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polyesters such as liquid crystal polyester, polyethylene (PE), polypropylene (PP) , Polyolefins such as polybutylene, polyarylene sulfides such as polyoxymethylene (POM), polyamide (PA), polyphenylene sulfide (PPS), polyketone (PK), polyetherketone (PEK), polyetheretherketone (PEEK), poly Crystalline resins such as fluorinated resins such as ether ketone ketone (PEKK), polyether nitrile (PEN), polytetrafluoroethylene, and liquid crystal polymer (LCP); , Polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyphenylene ether (PPE), polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polysulfone (PSU), poly Amorphous resins such as ether sulfone and polyarylate (PAR), phenolic resins, phenoxy resins, polystyrenes, polyolefins, polyurethanes, polyesters, polyamides, polybutadienes, polyisoprenes, fluorine Examples thereof include thermoplastic resins such as acryl-based resins and acrylonitrile-based thermoplastic elastomers, and copolymers and modified products thereof.

  In one embodiment of the present invention, the resin 2 preferably includes at least one kind of thermosetting resin. Thermosetting resins include unsaturated polyesters, vinyl esters, epoxy resins, phenol resins, urea resins, melamine resins, thermosetting polyimides, copolymers thereof, modified products, and resins obtained by blending at least two of these. Can be illustrated. Moreover, in the range which does not impair the objective of this invention, resin of the structure which concerns on this invention may contain impact resistance improvers, such as an elastomer or a rubber component, and another filler and additive. Examples of fillers and additives include inorganic fillers, flame retardants, conductivity imparting agents, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorants, and coloring inhibitors. , Heat stabilizers, mold release agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, antifoaming agents, or coupling agents.

  According to the present invention, the volume content of the reinforcing fiber is 0.5 volume% or more and 55 volume% or less, the volume content of the resin is 2.5 volume% or more and 85 volume% or less, and the void volume is 100 volume% of the structure. The content is preferably 10% by volume or more and 97% by volume or less. That is, the volume content of the resin 2 in 100% by volume of the structure is preferably 2.5% by volume or more and 85% by volume or less. The volume content of the resin 2 is preferably in the range of 2.5% by volume to 85% by volume. By setting it as said range, the resin 2 can fully fulfill | perform the role of the coupling | bonding of the reinforced fiber 3, and can improve the mechanical characteristic and the lightweight property of the structure 1. FIG.

  As the reinforcing fiber 3, metal fibers such as aluminum, brass, and stainless steel, PAN-based, rayon-based, lignin-based, pitch-based carbon fibers, graphite fibers, insulating fibers such as glass, aramid, PBO, polyphenylene sulfide, polyester, Examples thereof include organic fibers such as acrylic, nylon, and polyethylene, and inorganic fibers such as silicon carbide and silicon nitride. Moreover, the surface treatment may be given to these fibers. Examples of the surface treatment include a treatment with a coupling agent, a treatment with a sizing agent, a treatment with a bundling agent, and an adhesion treatment of an additive in addition to a treatment for depositing a metal as a conductor. Moreover, these fibers may be used individually by 1 type, and may use 2 or more types together.

  The reinforcing fibers 3 in the structure are preferably discontinuous, are approximately monofilament-like, and are randomly dispersed. By making the reinforcing fiber 3 into such an embodiment, when a precursor or structure of a sheet-like structure is formed by applying an external force, it becomes easy to mold into a complicated shape. Moreover, since the void formed by the reinforcing fiber 3 is densified and the weak part at the fiber bundle end of the reinforcing fiber 3 in the structure 1 can be minimized by adopting the reinforcing fiber 3 as such an aspect, excellent reinforcing efficiency In addition to reliability, isotropic properties are also imparted. Here, the substantially monofilament means that the reinforcing fiber single yarn is present in less than 500 fineness strands. More preferably, it is dispersed in a monofilament form.

  Here, the term “dispersed in a substantially monofilament shape or monofilament shape” means a ratio of single fibers having a two-dimensional contact angle of 1 ° or more with respect to the reinforcing fibers 3 arbitrarily selected in the structure 1 ( Hereinafter, it refers to that the fiber dispersion ratio is 80% or more, in other words, in the structure 1, two or more of the single fibers are in contact with each other and the bundle in parallel is less than 20%. Therefore, it is particularly preferable that the mass fraction of the fiber bundle having at least 100 filaments in the reinforcing fiber 3 corresponds to 100%.

  In the case of discontinuous reinforcing fibers, the two-dimensional contact angle is an angle formed by a single fiber and a single fiber that comes into contact with the single fiber. It is defined as the angle on the acute angle side within the range of from 0 ° to 90 °. This two-dimensional contact angle will be further described with reference to the drawings. FIG. 2 is a schematic diagram illustrating an example of a dispersion state of reinforcing fibers in the reinforcing fiber mat when observed from the surface direction (FIG. 2A) and the thickness direction (FIG. 2B). When the single fiber 11a is used as a reference, the single fiber 5 is observed to cross the single fibers 6 to 10 in FIG. 2A, but the single fiber 5 is in contact with the single fibers 9 and 10 in FIG. Not. In this case, with respect to the reference single fiber 11a, the evaluation targets of the two-dimensional contact angle are the single fibers 6 to 8, and of the two angles formed by the two single fibers in contact, 0 ° or more and 90 ° It is an acute angle A within the following range.

  Although there is no restriction | limiting in particular as a method of measuring a two-dimensional contact angle, For example, the method of observing the orientation of the reinforced fiber 3 from the surface of the structure 1 can be illustrated. In this case, it becomes easier to observe the reinforcing fiber 3 by polishing the surface of the structure 1 to expose the reinforcing fiber 3. Moreover, the method of photographing the orientation image of the reinforcing fiber 3 by performing X-ray CT transmission observation can also be exemplified. In the case of the reinforcing fiber 3 having a high X-ray permeability, the reinforcing fiber 3 is observed by mixing the reinforcing fiber 3 with a tracer fiber or by applying a tracer chemical to the reinforcing fiber 3. It is preferable because it is easy to do. In addition, when the measurement by the above method is difficult, after the resin component is burned off at a high temperature by a heating furnace or the like, the reinforcing fiber 3 is extracted from the reinforcing fiber 3 taken out using an optical microscope or an electron microscope. A method for observing the orientation can be exemplified.

  Based on the observation method described above, the fiber dispersion rate is measured by the following procedure. That is, the two-dimensional contact angle with all the single fibers (single fibers 6 to 8 in FIG. 2) in contact with the randomly selected single fibers (single fibers 5 in FIG. 2) is measured. This is performed for 100 single fibers, and the ratio is calculated from the ratio between the total number of all single fibers whose two-dimensional contact angle is measured and the number of single fibers having a two-dimensional contact angle of 1 ° or more.

  Furthermore, it is particularly preferable that the reinforcing fibers 3 are dispersed randomly. Here, that the reinforcing fibers 3 are randomly dispersed means that the arithmetic average value of the two-dimensional orientation angle of the arbitrarily selected reinforcing fibers 3 in the structure 1 is within a range of 30 ° or more and 60 ° or less. Say. Such a two-dimensional orientation angle is an angle formed by a single fiber of the reinforcing fiber 3 and a single fiber intersecting with this single fiber, and among the angles formed by the intersecting single fibers, 0 ° or more, It is defined as the angle on the acute angle side within the range of 90 ° or less.

  This two-dimensional orientation angle will be further described with reference to the drawings. 2A and 2B, when the single fiber 5 is used as a reference, the single fiber 5 intersects with the other single fibers 6 to 10. Here, the intersection means a state in which a single fiber as a reference is observed crossing another single fiber in a two-dimensional plane to be observed, and the single fiber 5 and the single fibers 6 to 10 are not necessarily in contact with each other. There is no need to do so, and there is no exception to the state observed when they are projected. That is, when it sees about the single fiber 5 used as a reference | standard, all the single fibers 6-10 are evaluation objects of a two-dimensional orientation angle, and the two single fibers which a two-dimensional orientation angle crosses in FIG. Among the two angles to be formed, the angle A is an acute angle within a range of 0 ° to 90 °.

  The method for measuring the two-dimensional orientation angle is not particularly limited. For example, a method for observing the orientation of the reinforcing fiber 3 from the surface of the component can be exemplified, and the same means as the method for measuring the two-dimensional contact angle described above. Can be taken. The average value of the two-dimensional orientation angle is measured by the following procedure. That is, the average value of the two-dimensional orientation angle with all the single fibers (single fibers 6 to 10 in FIG. 2) intersecting with the randomly selected single fibers (single fibers 5 in FIG. 2) is measured. . For example, when there are many other single fibers that cross a certain single fiber, an arithmetic average value obtained by randomly selecting and measuring 20 other single fibers that intersect may be substituted. This measurement is repeated a total of 5 times with another single fiber as a reference, and the arithmetic average value is calculated as the arithmetic average value of the two-dimensional orientation angle.

  Since the reinforcing fibers 3 are dispersed in a substantially monofilament shape and randomly, the performance imparted by the reinforcing fibers 3 dispersed in the above-described substantially monofilament shape can be maximized. In addition, the structure 1 can impart isotropy to the mechanical characteristics. From such a viewpoint, the fiber dispersion rate of the reinforcing fibers 3 is desirably 90% or more, and is more preferable as it approaches 100%. The arithmetic average value of the two-dimensional orientation angle of the reinforcing fibers 3 is desirably in the range of 40 ° or more and 50 ° or less, and is more preferable as it approaches the ideal angle of 45 °.

  The form of the reinforcing fiber 3 may be either a continuous reinforcing fiber having the same length as that of the structure 1 or a discontinuous reinforcing fiber having a finite length cut to a predetermined length. From the viewpoint of easily impregnating and adjusting the amount thereof, discontinuous reinforcing fibers are preferable.

  As described above, the volume content of the reinforcing fibers 3 in 100 volume% of the structure is preferably in the range of 0.5 volume% or more and 55 volume% or less. When the volume content of the reinforcing fiber is in the above range, the reinforcing effect of the reinforcing fiber 3 is sufficiently exhibited, and the mechanical properties of the structure 1, particularly the bending properties are satisfied.

  It is preferable that the content rate of the space | gap 4 in 100 volume% of structures in this invention exists in the range of 10 volume% or more and 99 volume% or less. The presence of the air gap 4 in the above range makes the structure 1 have a structure with improved lightness and excellent specific rigidity and specific strength. In the present invention, the volume content is defined as 100% by volume of the total volume content of the resin 2, the reinforcing fiber 3, and the void 4 constituting the structure 1.

When the length of the reinforcing fiber 3 is Lf and the orientation angle of the reinforcing fiber 3 in the cross-sectional direction of the structure 1 is θf, the thickness St of the structure 1 is a conditional expression: St ≧ Lf ² · (1-cos (θf) ) Is preferably satisfied. By satisfying the above conditional expression, the reinforcing fiber 3 has straightness or the balance between the structure 1 having a desired thickness and the fiber length is excellent. These features are fully demonstrated and the freedom of thickness design is improved. In the above conditional expression, it is possible to obtain a balance between the bending elastic modulus and the specific bending rigidity, which are characteristics of the structure 1 formed by the length of the reinforcing fiber 3 and the orientation angle thereof, and the fiber length in the structure 1 Depending on the orientation angle, it is easy to be deformed in the state before solidification or curing in the molding process, and it is easy to mold the desired structure 1, so that the thickness St of the structure 1 is 2% or more and 20% or less. A value within the range is preferable, and a value within a range between 5% and 18% is particularly preferable. The units used in the conditional expression are St [mm], Lf [mm], and θf [°].

  Here, the length Lf of the reinforcing fiber 3 is obtained by removing the resin component of the structure 1 by a method such as burning or elution, and randomly selecting 400 from the remaining reinforcing fibers 3 and reducing the length to a unit of 10 μm. It can be calculated and calculated as a mass average fiber length calculated from their lengths. In addition, the orientation angle θf of the reinforcing fiber 3 in the cross-sectional direction of the structure 1 is the degree of inclination with respect to the cross-sectional direction of the structure 1, in other words, the degree of inclination of the reinforcing fiber 3 with respect to the thickness direction. A larger value indicates that the film is inclined in the thickness direction, and is given in a range of 0 ° to 90 °. That is, by setting the orientation angle θf of the reinforcing fibers 3 within such a range, the reinforcing function in the structure 1 can be expressed more effectively. Although there is no restriction | limiting in particular in the upper limit of orientation angle (theta) f of the reinforced fiber 3, In view of the expression of the bending elastic modulus at the time of setting it as the structure 1, it is desirable that it is 60 degrees or less, Furthermore, it is 45 degrees or less. It is more preferable. When the orientation angle θf of the reinforcing fibers 3 is less than 3 °, the reinforcing fibers 3 in the structure 1 are planar, in other words, two-dimensionally oriented. It is undesirable because it decreases and the lightness cannot be satisfied. Therefore, the orientation angle θf of the reinforcing fiber 3 is preferably 3 ° or more.

  The orientation angle θf of the reinforcing fiber 3 can be measured based on observation of a vertical cross section with respect to the surface direction of the structure 1. FIG. 3 is a schematic diagram showing an example of a cross-sectional structure in the surface direction (FIG. 3A) and the thickness direction (FIG. 3B) of the structure according to the present invention. In FIG. 3A, the cross-sections of the reinforcing fibers 3a and 3b are approximated to an elliptical shape for easy measurement. Here, the cross section of the reinforcing fiber 3a has a small elliptical aspect ratio (= ellipse long axis / short elliptical axis), whereas the cross section of the reinforcing fiber 3b has a large elliptical aspect ratio. On the other hand, according to FIG. 3B, the reinforcing fiber 3a has a substantially parallel inclination with respect to the thickness direction Y, and the reinforcing fiber 3b has a certain amount of inclination with respect to the thickness direction Y. In this case, for the reinforcing fiber 3b, the angle θx formed by the surface direction X of the structure 1 and the fiber main axis (long axis direction in the ellipse) α is substantially equal to the out-of-plane angle θf of the reinforcing fiber 3b. On the other hand, with respect to the reinforcing fiber 3a, there is a large difference between the angle θx and the angle indicated by the orientation angle θf, and it cannot be said that the angle θx reflects the orientation angle θf. Therefore, when the orientation angle θf is read from a vertical cross section with respect to the surface direction of the structure 1, the detection accuracy of the orientation angle θf can be improved by extracting a fiber cross section whose elliptical aspect ratio is a certain value or more.

  As an index of the elliptical aspect ratio to be extracted, when the cross-sectional shape of the single fiber is close to a perfect circle, that is, when the fiber aspect ratio in the cross section perpendicular to the longitudinal direction of the reinforcing fiber 3 is 1.1 or less, the elliptical aspect ratio For the reinforcing fiber 3 having a ratio of 20 or more, a method of measuring an angle θx formed by the plane direction X and the fiber principal axis α and adopting this as the orientation angle θf can be used. On the other hand, when the cross-sectional shape of the single fiber is an ellipse or a saddle shape, and the fiber aspect ratio is larger than 1.1, paying attention to the reinforcing fiber 3 having a larger elliptical aspect ratio, the orientation angle θf was measured. If the fiber aspect ratio is 1.1 or more and less than 1.8, the elliptical aspect ratio is 30 or more. If the fiber aspect ratio is 1.8 or more and less than 2.5, the elliptical aspect ratio is 40. As described above, when the fiber aspect ratio is 2.5 or more, it is preferable to select the reinforcing fiber 3 having an elliptical aspect ratio of 50 or more and measure the orientation angle θf.

The density ρ of the structure 1 is preferably 0.9 g / cm ³ or less from the viewpoint of lightness. In the structure according to the present invention, even when the structure is used alone or in combination with other members, the density of the structure itself varies depending on the reinforcing fiber or resin used. From the viewpoint of maintaining the mechanical properties of the structure, it is more preferably 0.03 g / cm ³ or more.

  The structure 1 according to the present invention can be used as a first member to form a composite article together with the second member. By using a composite article, it is possible to produce a product having a complicated shape, which exhibits mechanical characteristics, thermal characteristics, electrical characteristics, etc. that cannot be expressed only by the structure 1. As one form of the composite article, there is a composite article in which the second member is integrated with the outer surface of the first member by mechanical fastening, adhesive bonding, or heat fusion.

  When mechanical fastening is selected as the integration method, it is exemplified that a hole is formed in the first member and integrated with the second member using a bolt or nut. At this time, the resin 2 in the first member is a resin having a high strength or / and a high fatigue characteristic, the reinforcing fiber 3 is “a high strength fiber, and a non-conductive fiber that is not easily corroded by bolts and nuts is used. Alternatively, it is preferable to reduce the volume content of the void 4 because the strength of the structure around the hole is improved and the bonding strength is improved.

  When adhesive bonding is selected, a method of applying an adhesive to the first member and / or the second member and integrating them is exemplified. At this time, the resin 2 in the first member is subjected to a chemical treatment such as a plasma treatment or an etching treatment by applying a coupling agent or a primer for improving the adhesion to the surface of the first member, and a highly adhesive resin. It is preferable to increase the adhesion surface area by exposing the reinforcing fibers 3 to the adhesion interface or by disposing the voids 4 on the surface of the first member because the adhesion is more firmly achieved.

  In the case of selecting heat fusion, a method of melting and fusing part of the first member and / or the second member with heat is exemplified. In this case, “the reinforcing fiber 3 in the first member is welded and fused as a meltable fiber such as a metal fiber or a resin fiber”, “secondary processing is performed by melting and cooling the resin 2 as a thermoplastic resin”, “ The resin 2 is made into an uncured thermosetting resin and is integrated with the second member while being cured by heat, or “the melted first or / and second member flows into the concave portion of the other member, By solidifying ”, it is firmly heat-sealed.

  Another form of the composite article is a composite article in which the first member or the second member is included or embedded in the other member. By adopting the above-mentioned form, a composite article can be obtained without a joining step such as mechanical fastening or adhesive joining, which is preferable.

  As said 2nd member, a metal member, a decorating member, and a surface protection member are used preferably. Use of a metal member is preferable because it can impart metal characteristics to a composite article including the first member composed of reinforcing fibers, resin, and voids. Moreover, when using a decorating member, since the surface quality of a 1st member can be improved, it is preferable. Moreover, when using a surface protection member, since durability of a 1st member improves, it is preferable.

  The structure 1 is, for example, “a personal computer, a display, an OA device, a mobile phone, a portable information terminal, a PDA (a portable information terminal such as an electronic notebook), a video camera, an acoustic device, an optical device, an audio, an air conditioner, a lighting device, an amusement Electrical, electronic equipment parts such as “cases, trays, chassis, interior members, or cases thereof”, “members, toys, other home appliances”, “various members, various frames, various hinges, various arms, various axles, various wheels” Bearings, various beams "," hood, roof, door, fender, trunk lid, side panel, rear end panel, front body, underbody, various pillars, various members, various frames, various beams, various supports, various rails, various Outer plate or body parts such as hinges "," bumper, bumper beam, molding, unloading -Exterior parts such as covers, engine covers, current plates, spoilers, cowl louvers, aero parts "," interior parts such as instrument panels, seat frames, door trims, pillar trims, handles, various modules "or" motor parts, CNG Tanks, gasoline tanks "and other automobile and motorcycle structural parts," battery trays, headlamp supports, pedal housings, protectors, lamp reflectors, lamp housings, noise shields, spare tire covers "and other automobiles and motorcycle parts," sound insulation walls " Building materials such as interior materials such as walls and soundproof walls, backing plates, heat insulating materials, water retention materials, cushions, various panels, various mats, etc., `` Landing gear pods, winglets, spoilers, edges, ladders, elevators, failings, ribs , Parts for aircraft such as `` toe '', marine and ship parts such as `` floor materials, wall materials, propellers, piping, buoyancy materials, various fitting parts '', `` vehicle bodies, seat cushions, floor panels, pantographs, various interior parts '', etc. Railway parts, furniture such as "sofa, desk, chair", "bridge frame and core material, windmill blade, pole, pillar, cable, cushioning material, curing mat, filter, signboard, waterstop, transport box, shelter ”Industrial materials such as“, body for small unmanned aerial vehicles ”,“ fishing rods, bicycle frames, golf putters, surfboards, various rackets, bats, various balls, poles and posts ”structural materials for sports equipment,“ artificial bones, shoes , Bags, prosthetic limbs, protectors, supporters, medical equipment, impact absorbing members, etc.

  When the structure 1 is required to be flame retardant in addition to light weight and high rigidity, any of PVC, PA, PBT, PC, PEI, PPS, PEEK, and PAI is selected as the resin 2, and the reinforcing fiber 3 is selected. By selecting and combining pitch-based carbon fibers or aramid fibers, it is preferably used for automobiles, motorcycle parts, aircraft parts, railway parts, ship parts, building materials, and the like. When the structure 1 is also required to be electromagnetic wave transmissive, it is preferably used for electrical / electronic device parts, building materials, medical parts, etc. by selecting glass fibers as the reinforcing fibers 3. When high specific rigidity is required for the structure 1, “PP 2 is selected from the viewpoint of light weight as the resin 2 and PA, PPS, PEI, and PEEK are selected from the viewpoint of strength, and the PAN-based, pitch is used as the reinforcing fiber 3. Or a carbon fiber such as a rayon-based carbon fiber is selected and combined, or “a sheet-like intermediate base material in which the structural body 1 or structural body precursor is used for the core layer and the continuous reinforcing fiber 3 is impregnated with a resin. The sandwich structure used for the skin layer is preferably used for main structural parts such as automobiles, motorcycle parts, aircraft parts, railway parts, ship parts, building materials, sporting goods, and medical equipment. When the structure 1 is required to be flexible, the resin 2 is preferably used as a rubber component or an elastomer component for medical parts, electrical parts, electronic equipment parts, building materials, automobile interior parts, aircraft interior parts, etc. Used. When the structure 1 is also required to have high water absorption, the gaps 4 are connected to each other and are preferably used for building materials, industrial materials, furniture, etc. by taking the form of open cells. When economic efficiency is required for the structure 1, by selecting PP as the resin 2 and / or glass fiber as the reinforcing fiber 3, electrical / electronic equipment parts, automobile parts, railway parts, building materials, industrial materials, sports It is preferably used for articles. When the structure 1 is required to have conductivity, the structure 1 is made to contain conductive particles and / or by selecting carbon fiber or metal fiber as the reinforcing fiber 3, for electric / electronic device parts, automobiles, and motorcycles. It is preferably used for parts, aircraft parts, railway parts, ship parts, building materials and the like.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(1) Density of reinforcing fiber ρf
The density ρf of the reinforcing fiber was measured by a JIS R7603 (1999) A method liquid replacement method.

(2) Resin sheet density ρr
The density ρr of the resin sheet was measured by the JIS K7112 (1999) A method underwater substitution method.

(3) Volume content Vf of reinforcing fiber in the structure
After measuring the mass Ws of the structure, the structure was heated in air at 500 ° C. for 30 minutes to burn off the resin component, and the mass Wf of the remaining reinforcing fibers was measured and calculated by the following formula.
Vf (volume%) = (Wf / ρf) / {Wf / ρf + (Ws−Wf) / ρr} × 100
ρf: density of reinforcing fiber (g / cm ³ )
ρr: Density of resin sheet (g / cm ³ )
(4) Bending test of structure The test piece was cut out from the structure, and the bending elastic modulus was measured according to ISO178 method (1993). Test pieces were prepared by cutting out test pieces in four directions of + 45 °, −45 °, and 90 ° directions when an arbitrary direction was set to 0 ° direction, and the number of measurements was set to n = 5 in each direction, and the arithmetic average The value was defined as the flexural modulus Ec. As the measuring apparatus, “Instron (registered trademark)” 5565 type universal material testing machine (manufactured by Instron Japan Co., Ltd.) was used. From the obtained results, the specific bending rigidity of the structure was calculated by the following equation.
Specific bending stiffness = Ec ^1/3 / ρ
(5) Reinforcing fiber orientation angle θf in the structure
A small piece having a width of 25 mm was cut out from the structure, embedded in an epoxy resin, and then polished so that a vertical section in the sheet thickness direction was an observation surface to prepare a sample. The sample was magnified 400 times with a laser microscope (manufactured by Keyence Corporation, VK-9510), and the fiber cross-sectional shape was observed. Develop the observation image on general-purpose image analysis software, extract the individual fiber cross sections visible in the observation image using a program embedded in the software, provide an ellipse inscribed in the fiber cross section, and approximate the shape of the fiber cross section (Hereinafter referred to as fiber ellipse). Further, for the fiber ellipse having an aspect ratio of 20 or more represented by the major axis length α / minor axis length β of the fiber ellipse, the angle formed by the plane direction X and the major axis direction of the fiber ellipse was determined. By repeating the above operation for the observation samples extracted from different parts of the structure, the orientation angle was measured for a total of 600 reinforcing fibers, and the arithmetic average value was obtained as the orientation angle θf of the reinforcing fibers.

(6) Structure density ρ
A test piece was cut out from the structure, and the apparent density of the structure was measured with reference to JIS K7222 (2005). The dimensions of the test piece were 100 mm long and 100 mm wide. The length, width, and thickness of the test piece were measured with a micrometer, and the volume V of the test piece was calculated from the obtained values. Moreover, the mass M of the cut-out test piece was measured with the electronic balance. The density ρ of the structure was calculated by substituting the obtained mass M and volume V into the following equation.
ρ [g / cm ³ ] = 10 ³ × M [g] / V [mm ³ ]
(7) Volume content of voids in the structure The test piece was cut out from the structure to a length of 10 mm and a width of 10 mm, and the cross section was observed with a scanning electron microscope (SEM) (S-4800, manufactured by Hitachi High-Technologies Corporation). From the surface of the structure, 10 locations were photographed at 1000 × magnification at equal intervals. For each image to determine the area A _a void in the image. Moreover, to calculate the porosity by dividing the area A _a void in the area of the entire image. The volume content of voids in the structure was determined by arithmetic average from 50 voids in total, each of which was photographed at 10 points with 5 test pieces.

(8) Volume content of resin of structure The value obtained by subtracting the volume content of reinforcing fibers and voids obtained as described above from 100% by volume was determined as the volume content of resin.

(9)
[Carbon fiber 1]
Spinning, firing treatment, and surface oxidation treatment were carried out from a copolymer containing polyacrylonitrile as a main component to obtain continuous carbon fibers having a total number of 12,000 single yarns. The characteristics of this continuous carbon fiber were as follows.
Single fiber diameter: 7μm
Density: 1.8 g / cm ³
Tensile strength: 4600 MPa
Tensile modulus: 220 GPa
[PP resin]
100 g of basis weight comprising 80% by mass of unmodified polypropylene resin (“Prime Polypro” (registered trademark) J105G manufactured by Prime Polymer Co., Ltd.) and 20% by mass of acid-modified polypropylene resin (“Admer” QB510 manufactured by Mitsui Chemicals, Inc.) A resin sheet of / m ² was produced. The density of the obtained PP resin sheet was 0.92 g / cm ³ .

[Reinforcing fiber mat 1]
Carbon fiber 1 was cut into a length of 6 mm to obtain chopped carbon fiber. Chopped carbon fiber was put into a cotton opening machine to obtain a cotton-like reinforcing fiber assembly in which almost no reinforcing fiber bundle of the original thickness was present. This reinforcing fiber assembly was put into a carding apparatus having a cylinder roll having a diameter of 600 mm to form a sheet-like web made of reinforcing fibers. The rotation speed of the cylinder roll at this time was 320 rpm, and the speed of the doffer was 13 m / min. This web was laminated to obtain a reinforcing fiber mat 1. In the obtained reinforcing fiber mat 1, the reinforcing fibers were dispersed in substantially monofilaments. The mass average fiber length Lf of the reinforcing fiber mat 1 was 6 mm, and the basis weight was 50 g / m ² .

Example 1
Reinforcing fiber mat 3 as the reinforcing fiber mat, PP resin as the resin sheet, [Resin sheet / Reinforcing fiber mat / Resin sheet / Reinforcing fiber mat / Resin sheet / Reinforcing fiber mat / Resin sheet / Reinforcing fiber mat / Reinforcing fiber mat / Resin Three laminates arranged in the order of “sheet / reinforced fiber mat / resin sheet / reinforced fiber mat / resin sheet / reinforced fiber mat / resin sheet” were stacked to prepare a laminate. Subsequently, the structure was obtained through the following steps (I) to (V). In the obtained structure, voids with reinforcing fibers as columnar supports were confirmed from cross-sectional observation. Table 1 shows the characteristics of the obtained structure.

Subsequently, an instantaneous adhesive (manufactured by Toagosei Co., Ltd., Aron Alpha EXTRA fast-acting versatile) is applied to the surface of the above structure, and an M4 hexagon nut 1 type (manufactured by TRUSCO, SUS304) is adhesively bonded. Obtained. In the obtained composite article, the nut was firmly bonded to the structure 1.
(I) The laminate is placed in a press molding die cavity preheated to 230 ° C., and the die is closed.
(II) Next, after holding for 120 seconds, a pressure of 3 MPa is applied and the pressure is further held for 60 seconds.
(III) After step (II), the mold cavity is opened, a metal spacer is inserted into the end thereof, and the thickness when the structure is obtained is adjusted to 10.2 mm.
(IV) Thereafter, the mold cavity is fastened again, and the cavity temperature is cooled to 50 ° C. while maintaining the pressure.
(V) Open the mold and take out the structure.

(Example 2)
A hole having a diameter of 6 mm and a depth of 8 mm was formed in the structure 1 obtained in the same manner as in Example 1 with a drilling machine. M4 enZate (manufactured by KKV, SUS22L) was inserted into the obtained hole. In the obtained composite article, the ether was firmly embedded without breaking the structure 1 around the hole. Table 1 shows the characteristics of the obtained structure.

(Comparative Example 1)
Reinforcing fiber mat 3 as the reinforcing fiber mat, PP resin as the resin sheet, [Resin sheet / Reinforcing fiber mat / Resin sheet / Reinforcing fiber mat / Resin sheet / Reinforcing fiber mat / Resin sheet / Reinforcing fiber mat / Reinforcing fiber mat / Resin 9 sheets of laminates arranged in the order of “sheet / reinforcing fiber mat / resin sheet / reinforcing fiber mat / resin sheet / reinforcing fiber mat / resin sheet”, and then undergo the following steps (I) to (IV). A structure was obtained.
An attempt was made to adhesively bond the same nut as in Example 1 using the same instantaneous adhesive as in Example 1 on the surface of the obtained structure 1, but sufficient joint strength could not be obtained, and the nut was immediately It has come off. Table 1 shows the characteristics of the obtained structure.
(I) The laminate is placed in a press molding die cavity preheated to 230 ° C., and the die is closed.
(II) Next, after holding for 120 seconds, a pressure of 3 MPa is applied and the pressure is further held for 60 seconds.
(III) Thereafter, the cavity temperature is cooled to 50 ° C. while maintaining the pressure.
(IV) Open the mold and take out the structure.

(Comparative Example 2)
A hole having a diameter of 6 mm and a depth of 8 mm was processed with a drilling machine in order to insert an ether into the structure obtained in the same manner as in Comparative Example 1. However, the amount of burrs generated during machining was large, the drill shaft was shaken, and a smooth hole could not be obtained. Next, an enzant was inserted, but there was a gap between the hole and the enzant. Table 1 shows the characteristics of the obtained structure.

(Comparative Example 3)
A hole with a diameter of 6 mm and a depth of 8 mm was formed with a drilling machine, using Furukawa Electric's low-foam polypropylene sheet “Efcell” as a structure. The same insert as in Example 2 was inserted into the obtained hole, but the structure around the hole was partially broken during the insertion, and the insert could not be inserted without loosening. Table 1 shows the characteristics of the obtained structure.

〔Consideration〕
In this example, the mass average fiber length of the reinforcing fibers in the structure is 1 mm or more and 15 mm or less, and the existence interval of the composite composed of the reinforcing fibers and the resin is in the range of 10 to 100 μm, and the gap It is clear that a light-weight and high-rigidity structure is obtained when the maximum length satisfies 5 μm or more and 200 μm or less. Furthermore, in Example 1, a composite article in which metal parts were bonded and integrated to the structure could be formed. This is presumably because the adhesive strength was improved because a part of the adhesive flowed into the voids existing in the surface layer due to the ubiquitous voids in the structure. Also in Example 2, it was shown that the structure 1 was excellent in strength and workability. On the other hand, in Comparative Example 1, when the existing interval of the composite composed of the reinforcing fiber and the resin and the maximum length of the void are not satisfied, the specific bending rigidity is inferior and the composite article is obtained from the poor adhesiveness of the matrix resin. I couldn't. In Comparative Example 2, the workability of the structure is degraded because the balance of void content is poor, and in Comparative Example 3, the strength of the structure is not present because no reinforcing fiber is present. As a result, it was shown that the workability was also lowered.

  ADVANTAGE OF THE INVENTION According to this invention, the structure excellent in lightweight property and high rigidity can be provided.

DESCRIPTION OF SYMBOLS 1 Structure 2 Resin 3 Reinforcing fiber 4 Void 5-10 Single fiber 3a, 3b Single fiber

Claims (9)

A structure composed of reinforcing fibers and resin,
The reinforcing fibers have a mass average fiber length of 1 mm or more and 15 mm or less, and form voids by bonding through a resin.
A structure in which a composite existence interval composed of reinforcing fibers and a resin in an arbitrary cross section of the structure is in a range of 10 to 100 μm, and a maximum length of the void is 5 μm or more and 200 μm or less.   The structure according to claim 1, wherein the reinforcing fibers have a substantially monofilament shape and are randomly dispersed in the structure. The specific bending rigidity represented by Ec ^1/3 · ρ ⁻¹ is in the range of 3 or more and 20 or less when the bending elastic modulus of the structure is Ec and the density is ρ. A structure according to any one of the above. The structure according to claim 1, wherein the structure satisfies the following content.
(1) The volume content of the resin is 2.5% by volume to 85% by volume.
(2) The volume content of the reinforcing fiber is 0.5 volume% or more and 55 volume% or less.
(3) The volume content of the voids is 10% by volume to 97% by volume. When the length of the reinforcing fiber is Lf and the orientation angle of the reinforcing fiber in the cross-sectional direction of the structure is θf, the thickness St of the structure is a conditional expression: St ≧ Lf ² · (1-cos (θf) The structure according to any one of claims 1 to 4, wherein The structure according to any one of claims 1 to 5, wherein the density ρ of the structure is 0.9 g / cm ³ or less.   A composite comprising the structure according to any one of claims 1 to 6 as a first member, wherein the second member is integrated with the outer surface of the first member by mechanical fastening, adhesive bonding, and heat fusion. Goods. A composite article comprising the structure according to any one of claims 1 to 6 as a first member, the first member and a second member,
A composite article in which a first member or a second member is included or embedded in the other member.   The composite article according to claim 7 or 8, wherein the second member is a metal member, a decorative member, or a surface protection member.