Fiber-reinforced resin article and manufacturing method thereof

Abstract

To provide a fiber-reinforced resin article with reduced porosity and excellent impact energy absorption characteristics, and a method for manufacturing the fiber-reinforced resin article.SOLUTION: In a fiber-reinforced resin article having a hollow cylindrical section including at least one fiber-reinforced resin layer, the fiber-reinforced resin layer contains continuous fiber bundles arranged in a spiral and crossed form, and a thickness of the one fiber-reinforced resin layer in a cross section of the hollow cylindrical section cut in a direction perpendicular to an axial direction is 0.4 mm or more and 2 mm or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a fiber-reinforced resin article, and more particularly to a fiber-reinforced resin article having a hollow cylindrical shape, and a method for manufacturing the same.

Background Art

[0002] Since fiber-reinforced resin articles are lightweight and highly rigid, they have been widely studied for use as members in automobiles, aircraft, etc. For example, in addition to automotive drive shafts and propeller shafts, it has been proposed to apply fiber-reinforced resin articles having a hollow cylindrical shape as energy absorption members that absorb impact energy, such as side impact beams and crash boxes (Patent Documents 1 to 5). As fiber-reinforced resin articles having a hollow cylindrical shape, fiber-reinforced resin articles formed by the filament winding method are known (Patent Documents 1 to 5).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in conventional fiber-reinforced resin articles such as those of Patent Documents 1 to 5, voids are likely to occur between the layers laminated in the filament winding method, and it is difficult to achieve excellent impact energy absorption characteristics.

[0005] An object of the present invention is to provide a fiber-reinforced resin article with reduced voids and excellent impact energy absorption characteristics, and a method for manufacturing the fiber-reinforced resin article.

Means for Solving the Problems

[0006] The present invention includes the following aspects. [1] Having a hollow cylindrical portion including at least one layer of fiber-reinforced resin layer, The fiber-reinforced resin layer contains continuous fiber bundles arranged spirally and intersecting, A fiber-reinforced resin article, wherein the thickness of one layer of the fiber-reinforced resin layer is 0.4 mm or more and 2 mm or less. [2] The fiber-reinforced resin article according to [1], wherein the number of laminated layers of the fiber-reinforced resin layer in a cross section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction is 1 to 100. [3] The fiber-reinforced resin article according to [1] or [2], which satisfies the following formula (1). 1.0 ≦ (N C / t) ≦ 2.7 ···(1) (In the formula (1), N C is the number of laminated layers of the fiber-reinforced resin layer in a cross section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction. t is the total thickness (mm) of the hollow cylindrical portion.) [4] The fiber-reinforced resin article according to any one of [1] to [3], wherein the porosity in a cross section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction is 0.01 to 4%. [5] The fiber-reinforced resin article according to any one of [1] to [4], wherein the fiber volume content is 40 to 80% by volume. [6] The fiber-reinforced resin article according to any one of [1] to [5], which satisfies the following formula (2). P × V 1 / 2 ≦ 30 ···(2) (In the formula (2), P is the porosity (%) in a cross section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction. V is the fiber volume content (% by volume).) [7]The fiber-reinforced resin article according to any one of [1] to [6], wherein the maximum load in the following drop weight impact test is 5 kN or more and the average load is 1.0 kN or more. (Drop weight impact test) Cut the fiber-reinforced resin article to a length of 1000 mm to prepare a test piece, and fix it on an impact three-point bending jig with a fulcrum distance of 800 mm. A drop weight of 100 kg is freely dropped from a height of 4.09 m toward the central part in the length direction of the test piece, an impact three-point bending load is applied at an impact speed of 32 km / h, and the impact load (the reaction force of the load cell) is measured by load cells installed at the fulcrums at both ends of the test piece. Further, the displacement of the target marker installed on the drop weight when the impact three-point bending load is applied is measured, a load-displacement curve is drawn from the measured impact load and the displacement, the maximum value of the impact load is defined as the maximum load, and the average value of the impact load when the displacement is from 60 mm to 150 mm is defined as the average load. [8]The number of voids with an area of 2600 μm 2 or more in the cross section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction is 2 or less per unit area (mm 2 ), and the fiber-reinforced resin article according to any one of [1] to [7]. [9]The fiber-reinforced resin article according to any one of [1] to [8], wherein the continuous fiber bundle is a continuous carbon fiber bundle.

[10] The fiber-reinforced resin article according to any one of [1] to [9], wherein the number of the continuous fiber bundles constituting the fiber-reinforced resin layer is 1 to 5.

[11] Including winding a continuous fiber bundle around a mandrel in a helical winding by a filament winding method to form a hollow cylindrical portion including at least one layer of fiber-reinforced resin layer, A method for manufacturing a fiber-reinforced resin article, wherein the thickness of one layer of the fiber-reinforced resin layer is 0.4 mm or more and 2 mm or less.

[12] The method for manufacturing a fiber-reinforced resin article according to

[11] , which satisfies the following formula (3). (B×N F ) / (t 2 ×T×v)×10 4 ≦8 ···(3) (In the above formula (3), N Fis the set number of layers in the filament winding device. B is the number of traverses of winding of the continuous fiber bundle per layer of the set number of layers. t is the total thickness (mm) of the hollow cylindrical portion. T is the total fineness (mg / m) of the continuous fiber bundle. v is the molding speed (m / min).)

[13] The method for manufacturing a fiber-reinforced resin article according to

[11] or

[12] , wherein the total fineness of the continuous fiber bundle is 2000 to 6000 (mg / m).

[14] The method for manufacturing a fiber-reinforced resin article according to any one of

[11] to

[13] , wherein the number of the continuous fiber bundles wound around the mandrel is 1 to 5.

[15] The method for manufacturing a fiber-reinforced resin article according to any one of

[11] to

[14] , wherein the continuous fiber bundle is drawn out from the wound body around which the continuous fiber bundle is wound, resin is applied, and then wound around the mandrel.

[16] The method for manufacturing a fiber-reinforced resin article according to any one of

[11] to

[14] , wherein the continuous fiber bundle impregnated with resin is drawn out from the wound body around which the continuous fiber bundle is wound and wound around the mandrel.

Advantages of the Invention

[0007] An object of the present invention is to provide a fiber-reinforced resin article in which voids are reduced and which has excellent impact energy absorption characteristics, and a method for manufacturing the fiber-reinforced resin article.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be specifically described. However, the present invention is not limited to the following embodiments and can be variously modified and implemented within the scope of the gist thereof. In this specification and the claims, a numerical range represented by "~" means a numerical range including the numerical values before and after "~" as the lower limit value and the upper limit value. For example, A~B is synonymous with A or more and B or less.

[0010] [Fiber Reinforced Resin Article] The fiber reinforced resin article according to the embodiment of the present invention has a hollow cylindrical portion including at least one layer of fiber reinforced resin layer. The fiber reinforced resin layer contains continuous fiber bundles arranged spirally and intersecting, and the thickness of one layer of the fiber reinforced resin layer in a cross section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction is 0.4 mm or more and 2 mm or less. In the fiber reinforced resin article according to the embodiment, the fiber reinforced resin layer is typically formed by winding a continuous fiber bundle provided with a resin around a mandrel by a filament winding method. In the present invention, the "one layer of fiber reinforced resin layer" means a layer observed as one layer in a cross section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction. FIG. 3 is a cross-sectional photograph of the hollow cylindrical portion of the fiber reinforced resin article according to an example of the embodiment obtained by cutting in a direction perpendicular to the axial direction. As in this example, each fiber reinforced resin layer and the layers therebetween can be observed in the cross section.

[0011] The thickness of one layer of the fiber reinforced resin layer is 0.4 mm or more, preferably 0.45 mm or more, and more preferably 0.5 mm or more. If the thickness of one layer of the fiber reinforced resin layer is equal to or greater than the lower limit value, since the thickness of one layer of the fiber reinforced resin layer becomes thick, a fiber reinforced resin article with few voids can be obtained.

[0012] Since the voids are reduced and the impact energy absorption characteristics are improved, the fiber reinforced resin article according to the embodiment preferably satisfies the following formula (1). 1.0≦(N C / t)≦2.7 ···(1) However, in the above formula (1), N C is the number of layers of the fiber-reinforced resin layer (cross-sectional number of layers) in the cross-section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction. t is the total thickness (mm) of the hollow cylindrical portion.

[0013] N C / t is preferably 1.0 or more, more preferably 1.3 or more, and even more preferably 1.8 or more. N C / t is equal to or greater than the above lower limit, and the cross-sectional number of layers N per unit of lamination thickness (total thickness) t c increases, so that a fiber-reinforced resin article with few voids can be obtained. N C / t is preferably 2.7 or less, more preferably 2.6 or less, and even more preferably 2.5 or less. N C / t is equal to or less than the above upper limit, and the cross-sectional number of layers N per unit of lamination thickness (total thickness) t c decreases, so that the molding time becomes longer.

[0014] The number of layers of the fiber-reinforced resin layer (total cross-sectional number) N in the cross-section obtained by cutting the hollow cylindrical portion of the fiber-reinforced resin article in a direction perpendicular to the axial direction C is preferably from 1 to 100, more preferably from 1 to 50, and even more preferably from 1 to 10. The total cross-sectional number N C is equal to or less than the above upper limit, and the effect of reducing voids and improving impact energy absorption characteristics can be easily obtained.

[0015] Since voids are reduced and impact energy absorption characteristics are improved, the fiber-reinforced resin article according to the embodiment preferably satisfies the following formula (2). P × V 1 / 2 ≦ 30 ··· (2) However, in the above formula (2), P is the porosity (%) in the cross-section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction. V is the fiber volume content (volume %) of the fiber-reinforced resin article.

[0016] P × V 1 / 2 The value obtained by is more preferably 25 or less, and even more preferably 20 or less.

[0017] The porosity P is preferably from 0.01 to 4%, more preferably from 0.01 to 3%, and even more preferably from 0.01 to 2%. If the porosity P is below the upper limit value, the impact energy absorption characteristics of the fiber-reinforced resin article are improved. The porosity P can be measured in accordance with JIS K 7075:1991.

[0018] The fiber volume content V of the fiber-reinforced resin article is preferably from 40 to 80% by volume, more preferably from 42 to 65% by volume, and even more preferably from 40 to 57% by volume. If the fiber volume content V is at least the lower limit value, the proportion of the reinforcing fibers bearing the load increases, and the impact energy absorption characteristics of the fiber-reinforced resin article are improved. If the fiber volume content V is at most the upper limit value, the resin (matrix resin) serves as a binder with the reinforcing fibers, and the impact energy absorption characteristics of the fiber-reinforced resin article are improved. The fiber volume content V of the fiber-reinforced resin article can be measured in accordance with JIS K 7075:1991.

[0019] In the cross-section obtained by cutting the hollow cylindrical portion of the fiber-reinforced resin article in a direction perpendicular to the axial direction, the number of voids (large voids) with an area of 2600 μm 2 or more is preferably 2 or less, more preferably 1.5 or less, and even more preferably 1 or less per unit area (mm 2 ). If the number of large voids is at most the upper limit value, the impact energy absorption characteristics of the fiber-reinforced resin article are improved.

[0020] Since it is easy to obtain a fiber-reinforced resin article having excellent impact energy absorption characteristics, the number of continuous fiber bundles constituting the fiber-reinforced resin layer is preferably 1 to 5. For example, it is preferable to install 1 to 5 continuous fiber bundles in a yarn feeding device that supplies and controls the tension of the continuous fiber bundles in a filament winding device to manufacture a fiber-reinforced resin article.

[0021] Examples of the reinforcing fibers constituting the continuous fiber bundle include, for example, glass fibers, carbon fibers, aramid fibers, and alumina fibers. Among them, carbon fibers are preferred because they have excellent mechanical properties and are likely to exhibit characteristics. That is, as the continuous fiber bundle, a continuous carbon fiber bundle is preferred. The reinforcing fibers constituting the continuous fiber bundle may be of one type or two or more types.

[0022] Since it is easy to obtain a fiber-reinforced resin article having excellent impact energy absorption characteristics, the fiber diameter of the reinforcing fibers constituting the continuous fiber bundle is preferably 3 to 25 μm, more preferably 4 to 15 μm, and even more preferably 5 to 10 μm. The fiber diameter of the reinforcing fibers can be measured in accordance with JIS R 3420:2013.

[0023] The total fineness of the continuous fiber bundle is preferably 2000 to 6000 mg / m, more preferably 2500 to 5000 mg / m, and even more preferably 3000 to 4000 mg / m. If the total fineness of the continuous fiber bundle is equal to or greater than the lower limit value, it is easy to obtain a fiber-reinforced resin article having excellent impact energy absorption characteristics. If the total fineness of the continuous fiber bundle is equal to or less than the upper limit value, the length of the continuous fiber bundle wound around the bobbin becomes longer, so that the fiber-reinforced resin article can be efficiently produced. The total fineness of the continuous fiber bundle can be measured in accordance with JIS R 3420:2013.

[0024] The number of filaments in the continuous fiber bundle is preferably 35000 to 100000, more preferably 40000 to 80000, and even more preferably 45000 to 75000. If the number of filaments is equal to or greater than the lower limit value, it is easy to obtain a fiber-reinforced resin article having excellent impact energy absorption characteristics. If the number of filaments is equal to or less than the upper limit value, it is easy to uniformly impregnate the continuous carbon fibers with the resin in the process of manufacturing the fiber-reinforced resin article by the filament winding method.

[0025] Since it is easy to obtain a fiber-reinforced resin article having excellent impact energy absorption characteristics, the crossing angle of the reinforcing fiber bundles crossing in the hollow cylindrical shape portion of the fiber-reinforced resin article is preferably 60 to 160°, more preferably 80 to 130°.

[0026] The resin used for the fiber-reinforced resin layer may be a thermosetting resin or a thermoplastic resin. As the resin, a thermosetting resin is preferable because of excellent molding workability, particularly workability during filament winding molding, and resin impregnation properties.

[0027] Examples of the thermosetting resin include epoxy resin, unsaturated polyester resin, vinyl ester resin, melamine resin, phenol resin, urethane resin, polyisocyanate, polyisocyanurate, polyimide, urea resin, silicone resin, furan resin, benzoguanamine resin, alkyd resin, xylene resin, bismaleimide triazine resin, diallyl phthalate resin, and the like. Among them, epoxy resin is preferable because of excellent impregnation properties, curing rate, demolding properties, and mechanical properties of the molded product. The thermosetting resin may be used alone or in combination of two or more.

[0028] Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, bisphenol S type epoxy resin, tetramethyl bisphenol A type epoxy resin, tetramethyl bisphenol F type epoxy resin, tetramethyl bisphenol AD type epoxy resin, tetramethyl bisphenol S type epoxy resin, tetrabromo bisphenol A type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, and the like.

[0029] Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, styrene / maleic anhydride resin, styrene / maleimide resin, polyacrylonitrile, acrylonitrile / styrene resin, acrylonitrile / butadiene / styrene resin, chlorinated polyethylene / acrylonitrile / styrene resin, acrylonitrile / ethylene / styrene resin, acrylonitrile / styrene / methyl acrylate resin, styrene / acrylonitrile resin, (meth)acrylic resin, polyvinyl chloride, polyvinylidene chloride, polyamide, polyacetal, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polycarbonate, polyarylene sulfide, polyethersulfone, polyphenylsulfone, polyphenylene ether, modified polyphenylene ether, polyaryl ketone, liquid crystal polymer, fluororesin, polyetherimide, polyarylate, polysulfone, polyamideimide, polyaminobismaleimide, thermoplastic polyimide, polyethylene naphthalate, ethylene / vinyl acetate resin, ionomer resin, polybutadiene, styrene / butadiene resin, polybutylene, polymethylpentene, olefin / vinyl alcohol resin, cyclic olefin resin, cellulose resin, polylactic acid, etc. The thermoplastic resin may be used alone or in combination of two or more.

[0030] For the fiber reinforced resin layer, a resin composition in which an additive is blended with the resin may be used. Examples of the additive that the resin composition may contain include a curing agent, a curing accelerator, a flame retardant, an ultraviolet absorber, a heat stabilizer, an antioxidant, an antistatic agent, a fluidity improver, an antiblocking agent, a lubricant, a nucleating agent, an antibacterial agent, a pigment, etc.

[0031] The fiber reinforced resin article according to the embodiment is excellent in impact energy absorption characteristics. Specifically, it is preferable that the maximum load in the falling weight impact test described later is 5 kN or more and the average load is 1.0 kN or more.

[0032] (Falling weight impact test) The fiber-reinforced resin article is cut to a length of 1000 mm to prepare a test piece, which is fixed on an impact three-point bending jig with a span of 800 mm. A drop hammer with a mass of 100 kg is freely dropped from a height of 4.09 m toward the central portion in the length direction of the test piece, and an impact three-point bending load is applied at an impact speed of 32 km / h. The impact load (the reaction force of the load cell) is measured by load cells installed at the fulcrums at both ends of the test piece. Further, the displacement of the target marker installed on the drop hammer when the impact three-point bending load is applied is measured, and a load-displacement curve is drawn from the measured impact load and the displacement. The maximum value of the impact load is defined as the maximum load, and the average value of the impact load when the displacement ranges from 60 mm to 150 mm is defined as the average load.

[0033] More specifically, as shown in FIG. 1, a fiber-reinforced resin article having a hollow cylindrical shape is cut to a length of 1000 mm to prepare a test piece 1, which is fixed on impact three-point bending jigs 2 and 3 with a span of 800 mm using a large-scale drop weight impact testing apparatus. A drop hammer 4 with a mass of 100 kg (the lower surface is a hemispherical surface with a radius of curvature of 150 mm) is freely dropped from a height (the distance from the lower end of the drop hammer 4 to the central axis of the test piece 1) of 4.09 m toward the central portion in the length direction of the test piece 1, and an impact three-point bending load in the thickness direction is applied to the central portion of the test piece 1 at an impact speed of 32 km / h. At this time, the impact load (the reaction force of the load cell) is measured by load cells installed at the fulcrums at both ends of the test piece 1, and the deformation of the central portion of the test piece 1 is photographed with a high-speed camera, and the video is analyzed by displacement analysis software to measure the displacement of the central portion of the test piece 1 (the amount of deformation based on the initial position of the central portion of the test piece 1). Then, a load-displacement curve is drawn using the measured impact load and displacement, the maximum value of the impact load is obtained as the maximum load, and the average value of the impact load when the displacement ranges from 60 mm to 150 mm is obtained as the average load.

[0034] The use of the fiber-reinforced resin article according to the embodiment is not particularly limited, and examples thereof include a shaft material and an energy absorption member. Examples of the shaft material include automobile parts such as a propeller shaft and a drive shaft, and sports goods such as a tennis racket, a fishing rod, and a golf shaft. Examples of the energy absorption member include a crash box, a front side member, a rear side member, a side impact beam, and the like.

[0035] [Method for manufacturing a fiber-reinforced resin article] The method for manufacturing a fiber-reinforced resin article according to the embodiment includes winding a continuous fiber bundle around a mandrel in a helical manner by a filament winding method to form a hollow cylindrical portion including at least one layer of a fiber-reinforced resin layer, and setting the thickness of the one layer of the fiber-reinforced resin layer to 0.4 mm or more and 2 mm or less. Thereby, voids in the hollow cylindrical portion are reduced, and a fiber-reinforced resin article excellent in impact energy absorption characteristics can be obtained.

[0036] The method for manufacturing a fiber-reinforced resin article according to the embodiment may be a wet filament winding method in which a continuous fiber bundle is drawn out from a wound body around which the continuous fiber bundle is wound, resin is applied, and then the continuous fiber bundle is wound around a mandrel, or may be a dry filament winding method in which a continuous fiber bundle is drawn out from a wound body around which a continuous fiber bundle impregnated with resin is wound and wound around a mandrel.

[0037] As an example, a stainless steel mandrel having a predetermined outer diameter is installed in a filament winding apparatus, and, for example, one continuous carbon fiber bundle is installed as a continuous fiber bundle in a yarn feeding apparatus that supplies the continuous fiber bundle and controls the tension. For example, an epoxy resin is introduced into a resin bath as a resin composition. A curing agent and a curing accelerator may be blended into the epoxy resin. Next, using the filament winding apparatus, the continuous fiber bundle is impregnated with the resin composition in the resin bath and wound around the mandrel so as to have a predetermined thickness while applying a predetermined tension. Next, the continuous fiber bundle wound around the mandrel is heated at a predetermined temperature for a predetermined time to cure the resin composition impregnated in the continuous fiber bundle. Then, by removing the cured product formed by curing the resin composition impregnated in the continuous fiber bundle from the mandrel using a core removing machine, a fiber-reinforced resin article having a hollow cylindrical portion can be obtained. As the filament winding apparatus and the core removing machine, known apparatuses can be used.

[0038] In the filament winding method, the thickness of one layer of the fiber-reinforced resin layer can be adjusted by adjusting the total fineness of the continuous fiber bundle used in the filament winding method, the tension applied to the continuous fiber bundle wound around the mandrel (forming tension F), and the like. The total fineness of the continuous fiber bundle used in the filament winding method is preferably 2000 to 6000 mg / m, more preferably 3000 to 5000 mg / m, and even more preferably 3200 to 3800 mg / m. By using a reinforcing fiber bundle (large tow) with a total fineness of 2000 mg / m or more, the thickness of one layer of the fiber-reinforced resin layer can be easily made in the range of 0.4 to 2 mm. By using large tow, the number of layers of the fiber-reinforced resin layer can be reduced compared to molding using regular tow, and since the number of layers between layers decreases, it becomes easier to obtain a fiber-reinforced resin article with a low porosity. Also, by using large tow, the number of traverses and the number of layers can be reduced compared to regular tow CF, so the molding time can be shortened.

[0039] In the filament winding method, the number of continuous fiber bundles wound around the mandrel, that is, the number of continuous fiber bundles installed in the yarn feeding device of the filament winding apparatus, is preferably 1 to 5.

[0040] The winding angle of the continuous fiber bundle wound around the mandrel, that is, the angle formed between the rotation axis (central axis) direction of the mandrel and the continuous fiber bundle wound around the mandrel, is preferably 1 to 60°, and more preferably 10 to 30°.

[0041] Since it is easy to obtain a fiber-reinforced resin article excellent in impact energy absorption characteristics, the method for manufacturing a fiber-reinforced resin article according to the embodiment preferably satisfies the following formula (3). (B × N F ) / (t 2 × T × v) × 10 4 ≦ 8 ··· (3) However, in the above formula (3), N FN is the set number of layers in the filament winding device. B is the number of traverses of winding of the continuous fiber bundle per layer of the set number of layers. t is the total thickness (mm) of the hollow cylindrical portion. T is the total fineness (mg / m) of the continuous fiber bundle. v is the molding speed (m / min).

[0042] (B × N F ) / (t 2 × T × v) × 10 4 The value obtained is more preferably 6 or less, and even more preferably 4 or less.

[0043] Since a fiber-reinforced resin article excellent in impact energy absorption characteristics is easily obtained, the tension (molding tension F) applied to the continuous fiber bundle wound around the mandrel is preferably 10 to 150 N, more preferably 15 to 100 N, and even more preferably 15 to 80 N.

[0044] Since a fiber-reinforced resin article excellent in impact energy absorption characteristics is easily obtained, the lamination thickness (total thickness) t when winding the continuous fiber bundle around the mandrel is preferably 2 to 12 mm, more preferably 3 to 8 mm, and even more preferably 4 to 6 mm.

[0045] The molding speed v, that is, the supply speed of the continuous fiber bundle wound around the mandrel is preferably 1 to 500 m / min, more preferably 1 to 300 m / min, and even more preferably 5 to 150 m / min.

[0046] When heating the continuous fiber bundle wound around the mandrel, the heating temperature is preferably 70 to 90°C, more preferably 75 to 85°C. When heating the continuous fiber bundle wound around the mandrel, the heating time is preferably 3 to 5 hours, more preferably 3.5 to 4.5 hours.

[0047] As described above, in the present invention, in a fiber-reinforced resin article having a hollow cylindrical portion including at least one layer of fiber-reinforced resin layer, the thickness of one layer of fiber-reinforced resin layer is set to be 0.4 mm or more and 2 mm or less. As a result, a fiber-reinforced resin article with reduced voids and excellent impact energy absorption characteristics is obtained. When a fiber-reinforced resin article having a hollow cylindrical portion absorbs impact energy, if buckling occurs before the continuous fiber bundle breaks, the impact energy absorption characteristics deteriorate. Voids are a factor that deteriorates the interlayer adhesiveness and makes the continuous fiber bundle prone to buckling. However, in the fiber-reinforced resin article of the present invention, the interlayer adhesiveness is improved by reducing the porosity. As a result, in the fiber-reinforced resin article of the present invention, it is considered that buckling of the continuous fiber bundle is suppressed when impacted, and excellent impact energy absorption characteristics are exhibited.

Example

[0048] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following description.

[0049] [Materials] (Continuous fiber bundle) Fiber bundle 1: A continuous carbon fiber bundle formed by converging 60,000 carbon fiber filaments, with a total fineness T of 3,200 mg / m. Fiber bundle 2: A continuous carbon fiber bundle formed by converging 50,000 carbon fiber filaments, with a total fineness T of 3,750 mg / m. Fiber bundle 3: A continuous carbon fiber bundle formed by converging 30,000 carbon fiber filaments, with a total fineness T of 1,670 mg / m. (Resin composition) Resin composition 1: An epoxy resin composition obtained by mixing an epoxy resin (manufactured by Nagase ChemteX Corporation, trade name: Epoxy resin XNR6805), a curing agent (manufactured by Nagase ChemteX Corporation, trade name: XNH6805), and a curing accelerator (manufactured by Nagase ChemteX Corporation, trade name: XNA6805) at a mass ratio of 100:100:2.

[0050] [Example 1-1] A fiber-reinforced resin article having a hollow cylindrical portion was manufactured using a continuous fiber bundle 1 and a resin composition 1. After installing a stainless steel mandrel with an outer diameter of 25 mm in a filament winding device, one fiber bundle 1 was installed in a yarn feeding device that supplies and controls the tension of the continuous fiber bundle, and the resin composition 1 was introduced into the resin bath of the filament winding device. As the mandrel, one that had been previously subjected to a mirror finish and a release treatment was used. Using the filament winding device, the fiber bundle 1 was impregnated with the resin composition 1 in the resin bath and wound around the mandrel so that the lamination thickness t became 4.15 mm while applying a tension of 28.7 N (forming tension F). The winding operation of the fiber bundle 1 by the filament winding device was performed with the set number of laminations N F of 4, the traverse number B of winding of the continuous fiber bundle per layer of the set number of laminations N F of 9 times / layer, the forming speed v of 5 m / min, and the winding angle with respect to the rotation axis (central axis) direction of the mandrel being set to ±30° (i.e., the crossing angle being 60°) when the rotation axis direction of the mandrel was set to 0°. Next, the fiber bundle 1 wound around the mandrel was heated at a temperature of 85°C for 4 hours to cure the resin composition 1 impregnated in the fiber bundle 1. Next, the cured product of the fiber bundle 1 impregnated with the resin composition 1 was removed from the mandrel using a core removal machine to obtain a fiber-reinforced resin article having a hollow cylindrical portion with an outer diameter of 33 mm and an inner diameter of 25 mm.

[0051] [Example 1-2] A fiber-reinforced resin article having a hollow cylindrical portion was manufactured in the same manner as in Example 1, except that in the winding of the fiber bundle 1 impregnated with the resin composition 1 around the mandrel by the filament winding device, the forming tension F was changed to 16.6 N and the lamination thickness t was changed to 4.03 mm.

[0052] [Example 1-3] In the winding of the fiber bundle 1 impregnated with the resin composition 1 around the mandrel by the filament winding device, the forming tension F was 47.9 N, the lamination thickness t was 4.07 mm, and the set number of laminations N FA fiber-reinforced resin article having a hollow cylindrical portion was produced in the same manner as in Example 1, except that it was changed to 5.

[0053] [Example 1-4] In winding the fiber bundle 1 impregnated with the resin composition 1 around the mandrel by the filament winding apparatus, the forming tension F was 60.0 N, the lamination thickness t was 4.25 mm, and the set number of laminations N F A fiber-reinforced resin article having a hollow cylindrical portion was produced in the same manner as in Example 1, except that it was changed to 5.

[0054] [Example 2-1] The continuous fiber bundle was changed to fiber bundle 2, and further, in winding the fiber bundle 2 impregnated with the resin composition 1 around the mandrel by the filament winding apparatus, a fiber-reinforced resin article having a hollow cylindrical portion was produced in the same manner as in Example 1, except that the forming tension F was changed to 33.7 N and the lamination thickness t was changed to 4.35 mm.

[0055] [Example 2-2] The continuous fiber bundle was changed to fiber bundle 2, and further, in winding the fiber bundle 2 impregnated with the resin composition 1 around the mandrel by the filament winding apparatus, a fiber-reinforced resin article having a hollow cylindrical portion was produced in the same manner as in Example 1, except that the forming tension F was changed to 56.1 N and the lamination thickness t was changed to 4.03 mm.

[0056] [Comparative Example 1] The continuous fiber bundle was changed to fiber bundle 3, and further, in winding the fiber bundle 3 impregnated with the resin composition 1 around the mandrel by the filament winding apparatus, a fiber-reinforced resin article having a hollow cylindrical portion was produced in the same manner as in Example 1, except that the forming tension F was changed to 15.0 N, the lamination thickness t was changed to 4.21 mm, and the set number of laminations N F was changed to 6 and the number of traverses B was changed to 12 times / layer.

[0057] [Void fraction P] The porosity P of the fiber-reinforced resin articles obtained in each example was measured in accordance with JIS K 7075:1991. The results are shown in Table 1. The values in Table 1 are the average values when measured five times.

[0058] [Fiber volume fraction V] The fiber volume fraction V of the fiber-reinforced resin articles obtained in each example was measured in accordance with JIS K 7075:1991. The results are shown in Table 1. The values in Table 1 are the average values when measured five times.

[0059] [Falling weight impact test] The fiber-reinforced resin articles obtained in each example were cut so that the length became 1000 mm to prepare impact three-point bending test specimens (specimen 1), and a falling weight impact test was conducted using a large falling weight impact test device as shown in Fig. 1. In the falling weight impact test, specimen 1 was placed on an impact three-point bending jig with a support distance of 800 mm and fixed with a cloth fixing band. A 100 kg weight hammer 4 was freely dropped from a height of 4.09 m toward the central part in the length direction of specimen 1, and an impact three-point bending load in the thickness direction was applied to the central part of specimen 1 at an impact speed of 32 km / h. Signals (reaction forces of the load cells) from two load cells (manufactured by Showa Measuring Instruments Co., Ltd., product name: SH-00kN) installed at the supports at both ends of specimen 1 were recorded in a data logger (manufactured by Yokogawa Electric Corporation, product name: ScopeCorder DL950), and the impact load was measured. In addition, the displacement of the target marker installed on the weight hammer 4 when the impact three-point bending load was applied was measured by analyzing a video taken with a high-speed camera (manufactured by Photron Ltd., product name: FASTCAM Mini AX200) using displacement analysis software (manufactured by Photron Ltd., product name: Photron FASTCAM Analysis). Using the measured impact load and displacement, a load-displacement curve was drawn, and the maximum value of the measured impact load (maximum load) and the average value of the impact load when the displacement amount was from 60 mm to 150 mm (average load) were calculated. The results are shown in Table 1. In addition, the total energy absorption amount until the displacement amount in the load-displacement curve reached 150 mm was calculated. The specific energy absorption amount was calculated by dividing the calculated total energy absorption amount by the mass of the portion broken in the drop-weight impact test. The results are shown in Table 1. The values in Table 1 are the maximum values when measured three times. Fig. 2 shows the load-displacement curves obtained in the drop-weight impact test for the fiber-reinforced resin articles of Example 1 and Comparative Example 2.

[0060] [Measurement of large voids] A part of the fiber-reinforced resin article obtained in each example was cut in a direction perpendicular to the longitudinal direction, resin-embedded, and cross-sectionally observed. The cross-sectional observation image was binarized with image processing software HALCON and classified into a void portion and a resin and fiber portion. The area was 2600 μm 2 The number of the above voids (large voids) was measured, and the value obtained by dividing the number by the total area of the analysis range was defined as the large void number (pieces / mm 2 ). The results are shown in Table 1. The values in Table 1 are the results measured on one cross-section of the fiber-reinforced resin article of each example.

[0061]

Table 1

[0062] As shown in Table 1 and Fig. 1, the fiber-reinforced resin articles of Examples 1-1 to 1-4, 2-1, and 2-2, in which the thickness of the single-layer fiber-reinforced resin layer was in an appropriate range, all had a larger maximum load, average load, and specific energy absorption amount in the drop-weight impact test and were excellent in impact energy absorption characteristics compared to the fiber-reinforced resin article of Comparative Example 1 in which the thickness of the single-layer fiber-reinforced resin layer was thin.

Claims

1. It has a hollow cylindrical portion including at least one layer of fiber-reinforced resin layer, The fiber-reinforced resin layer contains continuous fiber bundles arranged spirally and intersecting, A fiber-reinforced resin article, wherein the thickness of one layer of the fiber-reinforced resin layer in a cross-section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction is 0.4 mm or more and 2 mm or less.

2. The fiber-reinforced resin article according to claim 1, wherein the number of laminated layers of the fiber-reinforced resin layer in a cross-section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction is 1 to 100.

3. The fiber-reinforced resin article according to claim 1, which satisfies the following formula (1). 1.0 ≤ (N Ｃ / t) ≤ 2.7...(1) (In the above formula (1), N Ｃ is the number of laminations of the fiber-reinforced resin layer in a cross-section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction. t is the total thickness (mm) of the hollow cylindrical portion.)

4. The fiber-reinforced resin article according to claim 1, wherein the porosity in a cross-section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction is 0.01 to 4%.

5. The fiber-reinforced resin article according to claim 1, wherein the fiber volume content is 40 to 80% by volume.

6. The fiber-reinforced resin article according to claim 1, which satisfies the following formula (2). P × V １／２ ≤ 30 ··· (2) (In the above formula (2), P is the porosity (%) in a cross-section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction. V is the fiber volume content (% by volume).)

7. The fiber-reinforced resin article according to claim 1, wherein the maximum load in the following drop weight impact test is 5 kN or more and the average load is 1.0 kN or more. (Drop weight impact test) The fiber-reinforced resin article is cut so that the length becomes 1000 mm to prepare a test piece, and the test piece is fixed on an impact three-point bending jig with a fulcrum distance of 800 mm. A drop weight of 100 kg is freely dropped from a height of 4.09 m toward the central portion in the length direction of the test piece, an impact three-point bending load is applied at an impact speed of 32 km / h, and the impact load (the reaction force of the load cell) is measured by load cells installed at the fulcrums at both ends of the test piece. Further, the displacement of the target marker installed on the drop weight when the impact three-point bending load is applied is measured, a load-displacement curve is drawn from the measured impact load and the displacement, the maximum value of the impact load is defined as the maximum load, and the average value of the impact load when the displacement is from 60 mm to 150 mm is defined as the average load.

8. The area in the cross-section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction is 2600 μm ２ or more, and the number of voids is 2 or less per unit area (mm ２ ), The fiber-reinforced resin article according to claim 1.

9. The fiber-reinforced resin article according to claim 1, wherein the continuous fiber bundle is a continuous carbon fiber bundle.

10. The fiber-reinforced resin article according to claim 1, wherein the number of the continuous fiber bundles constituting the fiber-reinforced resin layer is 1 to 5.

11. Wrapping a continuous fiber bundle around a mandrel in a helical winding by a filament winding method to form a hollow cylindrical portion including at least one layer of a fiber-reinforced resin layer, A method for manufacturing a fiber-reinforced resin article, wherein the thickness of one layer of the fiber-reinforced resin layer in a cross-section obtained by cutting the hollow cylindrical portion in a direction perpendicular to the axial direction is 0.4 mm or more and 2 mm or less.

12. The method for manufacturing a fiber-reinforced resin article according to claim 11, which satisfies the following formula (3). (B × N Ｆ ) / (t ２ × T × v) × 10 ４ ≤ 8... (3) (In the above formula (3), N Ｆ is the set number of layers in the filament winding apparatus. B is the number of traverses of the winding of the continuous fiber bundle per layer of the set number of layers. t is the total thickness (mm) of the hollow cylindrical portion. T is the total fineness (mg / m) of the continuous fiber bundle. v is the molding speed (m / min).)

13. The method for manufacturing a fiber-reinforced resin article according to claim 11, wherein the total fineness of the continuous fiber bundle is 2000 to 6000 (mg / m).

14. The method for manufacturing a fiber-reinforced resin article according to claim 11, wherein the number of the continuous fiber bundles wound around the mandrel is 1 to 5.

15. The method for manufacturing a fiber-reinforced resin article according to claim 11, wherein the continuous fiber bundle is drawn out from a wound body around which the continuous fiber bundle is wound, resin is applied, and then the continuous fiber bundle is wound around the mandrel.

16. The method for manufacturing a fiber-reinforced resin article according to claim 11, wherein the continuous fiber bundle impregnated with resin is drawn out from a wound body around which the continuous fiber bundle is wound and wound around the mandrel.

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