Shock absorbing material and its manufacturing method

Abstract

The present invention provides a shock-absorbing material with which progressive crushing can be realized with a simple structure, and which absorbs a large amount of energy. The shock-absorbing material has a cylindrical body and a plate-form member attached to an end surface of the cylindrical body. The cylindrical body contains a laminate of fiber-reinforced resin layers including a plurality of reinforcing fibers aligned in one direction and a resin impregnated in the plurality of reinforcing fibers, the cylindrical body has a buckling-minimizing layer and a fragile layer, and the plate-form member is attached to the cylindrical body via an adhesive layer.

Description

[Technical field]

[0001] The present invention relates to an impact absorbing material and a method for manufacturing the same. [Background technology]

[0002] 2. Description of the Related Art In recent years, the use of lightweight, high-strength fiber-reinforced resins as shock absorbing materials for use in automobiles and other vehicles to absorb external shocks has been considered.

[0003] For example, Patent Document 1 describes an impact absorbing device having an energy absorbing member (impact absorbing material) that is cylindrical and made of multiple layers in the radial direction, which is made of a composite material such as fiber-reinforced plastic. This impact absorbing device has a plate-shaped pressing part (the side to which the impact is applied) and a support part (the opposite side) at the front and rear of the cylindrical energy absorbing member, and the pressing part and the support part are held above and below the energy absorbing member by the tension of a clamping member made of a wire or the like. Patent Document 1 describes that the energy absorbing member of the above shape can induce progressive crushing, which absorbs a large amount of energy, by making the pressing part a tapered shape with a small diameter. It also describes that the clamping member bends when impact occurs, so that progressive crushing is not hindered.

[0004] Patent Document 2 describes an impact absorbing device having a crash box (shock absorbing material) made of fiber-reinforced plastic that absorbs impact energy by crushing in a predetermined crushing direction. This impact absorbing device has a pressing member and a support member, both of which are plate-shaped and arranged in front and behind the crash box. Patent Document 2 also describes that by providing a protrusion at the position where the pressing member abuts against the crash box, it is possible to stably progress the crushing from the initial stage of crushing of the crash box to the stage where progressive crushing progresses. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-67006 A [Patent Document 2] JP 2015-55295 A Summary of the Invention [Problem to be solved by the invention]

[0006] It is well known that when an impact absorbing material absorbs an impact, it is destroyed continuously (progressively) in the direction of the impact, which is called progressive crushing, and this increases the amount of energy absorbed during the impact. As described in Patent Document 1 and Patent Document 2, various methods for stably progressing progressive crushing have been studied.

[0007] However, the impact absorbing material having a tapered shape as described in Patent Document 1 has problems such as difficulty in performing high-precision post-processing and difficulty in clamping with the pressing part and the support part. In addition, in the configuration in which a protrusion is provided on the pressing member as described in Patent Document 2, precise alignment between the pressing member and the impact absorbing material is required, making it difficult to assemble the impact absorbing device. In addition, in the configuration in which the collapse is started and progressed by the protrusion, the amount of energy absorbed by the impact absorbing material during collapse is also reduced.

[0008] Furthermore, according to the findings of the present inventors, even in the configurations described in Patent Documents 1 and 2, depending on the type of impact absorbing material, progressive crushing may not be induced and the impact absorbing material may buckle.

[0009] In view of these problems, the present invention aims to provide an impact absorbing material that can achieve progressive crushing with a simple configuration and has a large energy absorption capacity, and a manufacturing method thereof. [Means for solving the problem]

[0010] One aspect of the present invention for solving the above problems relates to the following impact absorbing materials [1] to [8]. [1] An impact absorbing material having a cylindrical body and a plate-like member bonded to an end surface of the cylindrical body, The cylindrical body includes a laminate of fiber-reinforced resin layers including a plurality of reinforcing fibers oriented in one direction and a resin impregnated into the plurality of reinforcing fibers, The cylindrical body has a buckling suppression layer and a fragile layer, The plate-like member is bonded to the cylindrical body via an adhesive layer. Shock absorbing material. [2] The impact absorbing material described in [1], wherein the adhesive layer contains an acrylic adhesive or a cured product thereof. [3] The impact absorbing material described in [1] or [2], wherein the buckling suppression layer has an angle between the longitudinal direction of the cylindrical body and the direction in which the reinforcing fibers are oriented, which is 60° or more and 80° or less. [4] The impact absorbing material according to any one of [1] to [3], wherein the easily destructible layer has an angle between the longitudinal direction of the cylindrical body and the direction in which the reinforcing fibers are oriented, which is 5° or more and less than 30°. [5] The impact absorbing material described in any one of [1] to [4], wherein the laminate has a layer structure in which the buckling suppression layer, the fragile layer and the buckling suppression layer are stacked in this order from the inside to the outside of the cylindrical body. [6] The impact absorbing material according to any one of [1] to [5], wherein the plate-like member contains a thermoplastic resin. [7] The impact absorbing material according to any one of [1] to [6], wherein the fiber-reinforced resin layer includes the plurality of reinforcing fibers and a thermoplastic resin impregnated into the plurality of reinforcing fibers. [8] The impact absorbing material according to any one of [1] to [7], comprising a plurality of the cylindrical bodies, the plurality of cylindrical bodies being bonded to the same plate-like member.

[0011] Another aspect of the present invention for solving the above problems relates to a method for producing an impact absorbing material as described below in [9]. [9] A step of preparing a cylindrical body including a laminate of fiber-reinforced resin layers including a plurality of reinforcing fibers oriented in one direction and a resin impregnated into the plurality of reinforcing fibers, the cylindrical body having a buckling suppression layer and a fragile layer; and bonding a plate-like member to the end surface of the cylindrical body by an adhesive. A manufacturing method for shock absorbing material. Effect of the Invention

[0012] According to the present invention, there is provided an impact absorbing material that can achieve progressive crushing with a simple configuration and has a large energy absorption capacity, and a manufacturing method thereof. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an impact absorbing material according to one embodiment of the present invention. [Diagram 2] FIG. 2A is a schematic diagram showing the configuration of the cylindrical body, and FIGS. 2B, 2C, 2D, and 2E are schematic cross-sectional views of a partial region of the cylindrical body. [Diagram 3] 3A to 3G are schematic cross-sectional views of a partial region of the cylindrical body. [Figure 4] FIG. 4 is a flow chart showing an example of a method for manufacturing an impact absorbing material. [Diagram 5] FIG. 5 is a schematic diagram showing a typical configuration of an apparatus for producing a cylindrical body containing a thermoplastic resin. [Figure 6] FIG. 6 shows load-displacement curves in Example 2 and Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 1. Shock absorbing material An embodiment of the present invention relates to an impact absorbing material having a cylindrical body and a pair of plate-like members arranged on both ends of the cylindrical body.

[0015] In this impact absorbing material, the cylindrical body includes a laminate of fiber-reinforced resin layers including a plurality of reinforcing fibers aligned in one direction and a resin impregnated into the plurality of reinforcing fibers. Progressive crushing is realized by the orientation angle of the reinforcing fibers in each layer of the laminate. Furthermore, the energy absorption amount is increased by a simple configuration in which the plate-like member is attached to the cylindrical member via an adhesive layer.

[0016] 1 is a schematic diagram showing the configuration of an impact absorbing material according to one embodiment of the present invention. The impact absorbing material 100 has a cylindrical body 110 and two plate-like members 120 and 130 bonded to both end faces of the cylindrical body 110. The plate-like members 120 and 130 are bonded to the cylindrical body 110 via adhesive layers 140 and 150, respectively.

[0017] The size of the impact absorbing material is not particularly limited, but for example, the outer diameter of the cylindrical body 110 is 12 mm or more and 110 mm or less, the inner diameter of the cylindrical body 110 is 10 mm or more and 100 mm or less, the height of the cylindrical body 110 (the distance between the two plate-like members 120 and the plate-like member 130) is 20 mm or more and 1000 mm or less, and the surface area of ​​each of the plate-like members 120 and the plate-like member 130 is 34.5 mm 2 Over 1648.5mm 2 It can be the following, etc.

[0018] 1-1.Cylindrical body The cylindrical body 110 includes a laminate formed by stacking multiple fiber-reinforced resin layers containing a plurality of reinforcing fibers oriented and arranged in one direction and a resin composition (matrix resin) impregnated into the reinforcing fibers.

[0019] 1-1-1. Structure of the cylindrical body Fig. 2A is a schematic diagram showing the configuration of cylindrical body 110, and Fig. 2B, Fig. 2C, Fig. 2D, and Fig. 2E are schematic cross-sectional views of a partial region 112 of cylindrical body 110. Fig. 2B is a cross-sectional view in the thickness direction (Y direction in Fig. 2A), and Fig. 2C, Fig. 2D, and Fig. 2E are schematic cross-sectional views in a planar direction (XZ direction in Fig. 2A) along the surface of cylindrical body 110 at different depths in the thickness direction.

[0020] As shown in FIG. 2B, the cylindrical body 110 is a laminated body in which a plurality of fiber reinforced resin layers 114 are laminated. In this embodiment, the cylindrical body 110 has 16 fiber reinforced resin layers 114. FIG. 2C shows the configuration of one fiber reinforced resin layer 114a arranged near the inner surface of the cylindrical body 110, FIG. 2D shows the configuration of one fiber reinforced resin layer 114b arranged at an intermediate depth in the cylindrical body 110, and FIG. 2E shows the configuration of one fiber reinforced resin layer 114c arranged near the outer surface of the cylindrical body 110. As shown in FIG. 2C, FIG. 2D, and FIG. 2E, each fiber reinforced resin layer 114 includes a plurality of reinforcing fibers 210 arranged in one direction and a resin 220 impregnated into the plurality of reinforcing fibers.

[0021] As shown in Figs. 2C, 2D, and 2E, the cylindrical body 110 includes a plurality of types of fiber-reinforced resin layers 114 having different angles (hereinafter, simply referred to as "orientation angles") formed by the orientation direction of the reinforcing fibers 210 with respect to the length direction of the cylindrical body (Z direction in Figs. 2A to 2E). In this embodiment, buckling suppression layers with large orientation angles are arranged near the inner surface and the outer surface of the cylindrical body 110 (Figs. 2C and 2E), and a fragile layer with a small orientation angle is arranged at an intermediate depth of the cylindrical body 110 (Fig. 2D). In this embodiment, of the plurality of fiber-reinforced resin layers 114, the two layers closest to the inner surface of the cylindrical body 110 and the two layers closest to the outer surface of the cylindrical body 110 are the buckling suppression layers 116a and 116c, respectively, and the remaining 12 layers arranged at intermediate depths are the fragile layers 118b.

[0022] The buckling suppression layer 116a and the buckling suppression layer 116c are layers for suppressing buckling of the cylindrical body 110 upon impact. The smaller the orientation angle of the reinforcing fibers 210 (the closer the orientation direction of the reinforcing fibers 210 is to the longitudinal direction of the cylindrical body 110), the easier it is for the cylindrical body 110 to absorb energy. On the other hand, the smaller the orientation angle of the reinforcing fibers 210, the easier it is for the reinforcing fibers 210 to break upon impact, and the easier it is for the cylindrical body 110 to buckle. In contrast, by providing the buckling suppression layer 116a and the buckling suppression layer 116c in which the orientation angle of the reinforcing fibers 210 is larger (the orientation direction of the reinforcing fibers 210 is farther away from the longitudinal direction of the cylindrical body 110), it is possible to make it difficult for the cylindrical body 110 to buckle upon impact, and to facilitate the progress of progressive crushing.

[0023] From the viewpoint of more effectively suppressing buckling, it is preferable that the orientation angle of the reinforcing fibers 210 in the buckling suppression layer is larger. On the other hand, by not making the orientation angle of the reinforcing fibers 210 in the buckling suppression layer too large, the amount of energy absorbed by the buckling suppression layer can be increased, and the amount of energy absorbed by the cylindrical body 110 can also be increased. From the viewpoint of achieving a balance between these, the orientation angle of the reinforcing fibers 210 in the buckling suppression layer is preferably 50° or more and less than 90°, more preferably 55° or more and 85° or less, and even more preferably 60° or more and 80° or less.

[0024] The fragile layer 118b is a layer for increasing the energy absorption amount of the cylindrical body 110 during impact and inducing and advancing progressive crushing. It is known that for a cylindrical body including a laminate of fiber-reinforced resin layers, the smaller the orientation direction of the reinforcing fibers, the greater the amount of energy required for destruction and the greater the amount of energy absorption.

[0025] From the viewpoint of increasing the amount of energy absorption of the cylindrical body 110, it is preferable that the orientation angle of the reinforcing fibers 210 in the fragile layer is smaller. On the other hand, by giving the reinforcing fibers 210 in the fragile layer a certain degree of orientation angle, it is possible to make the cylindrical body 110 less likely to buckle upon impact. From the viewpoint of balancing these, it is preferable that the orientation angle of the reinforcing fibers 210 in the fragile layer is greater than 0° and less than 30°, more preferably 5° or more and less than 30°, and even more preferably 5° or more and less than 15°.

[0026] In order to reduce the deviation of the physical properties of the entire cylindrical body 110, the buckling prevention layer is preferably formed by continuously arranging two layers in which the reinforcing fibers 210 are oriented in opposite directions relative to the length direction of the cylindrical body. Similarly, the fragile layer is preferably formed by continuously arranging two layers in which the reinforcing fibers 210 are oriented in opposite directions relative to the length direction of the cylindrical body.

[0027] FIG. 3A is a cross-sectional view in the thickness direction of cylindrical body 110 similar to FIG. 2B, and FIGS. 3B, 3C, and 3D are schematic cross-sectional views similar to FIGS. 2C, 2D, and 2E, respectively, showing the configurations of fiber reinforced resin layer 114a (buckling suppression layer 116a), fiber reinforced resin layer 114b (destructible layer 118b), and fiber reinforced resin layer 114c (buckling suppression layer 116c). FIG. 3E is a schematic diagram showing the configuration of fiber reinforced resin layer 114aa as buckling suppression layer 116aa arranged continuously with fiber reinforced resin layer 114a shown in FIG. 3B. FIG. 3F is a schematic diagram showing the configuration of fiber reinforced resin layer 114bb as fragile layer 118bb arranged continuously with fiber reinforced resin layer 114b shown in FIG. 3C. FIG. 3G is a schematic diagram showing the configuration of fiber reinforced resin layer 114cc as buckling suppression layer 116cc arranged continuously with fiber reinforced resin layer 114c shown in FIG. 3C. As shown in Figures 3B and 3E, 3C and 3F, and 3D and 3G, in this embodiment, in each of the buckling suppression layer and the fragile layer, a fiber reinforced resin layer in which the reinforcing fiber 210 is oriented in the longitudinal direction of the cylindrical body is on the right side in the figure, and a fiber reinforced resin layer in which the reinforcing fiber 210 is oriented in the longitudinal direction of the cylindrical body is on the opposite side in the figure is continuously arranged. In this specification, for such fiber reinforced resin layers in which the reinforcing fiber 210 is oriented in the opposite direction, the orientation angle of the reinforcing fiber 210 in one fiber reinforced resin layer may be expressed as a + angle, and the orientation angle of the reinforcing fiber 210 in the other fiber reinforced resin layer may be expressed as a - angle. At this time, the above-mentioned preferred orientation angle is the absolute value of the orientation angle displayed with a + or - sign.

[0028] The arrangement of the buckling suppression layer and the fragile layer in the laminate is not particularly limited, and these layers can be arranged at any position. From the viewpoint of more effectively suppressing the buckling of the cylindrical body 110, the buckling suppression layer is preferably arranged on the outer surface or inner surface of the cylindrical body 110, and more preferably arranged on both the outer surface and the inner surface. In addition, from the viewpoint of increasing the amount of energy absorption by the cylindrical body 110 at the time of impact, it is preferable that the fragile layer is arranged in a continuous manner in multiple layers. From the viewpoint of achieving both of these, it is preferable that the laminate has a layer structure in which one or more layers of buckling suppression layers, one or more layers of fragile layers, and one or more layers of buckling suppression layers are laminated in this order from the inside to the outside of the cylindrical body 110.

[0029] The number of layers of the buckling suppression layer is not particularly limited, and can be set according to the balance between buckling suppression and the amount of energy absorption during impact. For example, the number of layers of the buckling suppression layer is preferably 2 to 12 layers, more preferably 2 to 10 layers, and more preferably 2 to 8 layers. When the laminate has buckling suppression layers in two or more places, such as the buckling suppression layer 116a and the buckling suppression layer 116c in this embodiment, the number of layers of the buckling suppression layer is the number of layers of the buckling suppression layer at each position.

[0030] The number of the fragile layers is not particularly limited, and can be set according to the balance between buckling suppression and the amount of energy absorption during impact. For example, the number of the buckling suppression layers is preferably 2 to 36, more preferably 4 to 24, and even more preferably 6 to 16. The number of the fragile layers is the total number of all the fragile layers included in the laminate.

[0031] According to the findings of the present inventors, a sufficient buckling suppression effect can be exhibited even with a smaller number of buckling suppression layers, while the amount of energy absorbed during impact increases as the number of fragile layers increases. Therefore, it is preferable that the laminate has a greater number of fragile layers than the buckling suppression layers.

[0032] 1-1-2. Materials for the cylindrical body 1-1-2-1. Reinforced fiber The material of the reinforcing fiber is not particularly limited. For example, carbon fiber, glass fiber, aramid fiber, alumina fiber, silicon carbide fiber, boron fiber, metal fiber, etc. can be used as the reinforcing fiber. Among these, carbon fiber is preferred because it has excellent mechanical properties and can reduce the weight of the molded product. Examples of the carbon fiber include PAN-based carbon fiber, pitch-based carbon fiber, and rayon-based carbon fiber. Among these, PAN-based carbon long fiber is preferred because it has an excellent balance between strength and elastic modulus.

[0033] The carbon fiber has a surface oxygen concentration ratio [O / C], which is the ratio of the number of oxygen (O) and carbon (C) atoms on the surface of the carbon fiber measured by X-ray photoelectron spectroscopy, of preferably 0.05 to 0.5, more preferably 0.08 to 0.4, and even more preferably 0.1 to 0.3. When the surface oxygen concentration ratio is 0.05 or more, a sufficient amount of functional groups can be secured on the carbon fiber surface, and the adhesion to the matrix resin can be further improved. When the surface oxygen concentration ratio is 0.5 or less, the carbon fiber has excellent handleability and productivity. The surface oxygen concentration ratio [O / C] can be measured by the method described in International Publication No. 2017 / 183672. The surface oxygen concentration ratio [O / C] can be controlled by known methods including electrolytic oxidation treatment, chemical oxidation treatment, and gas phase oxidation treatment, but control by electrolytic oxidation treatment is preferred.

[0034] From the viewpoint of sufficiently enhancing the effect of improving strength by the reinforcing fibers, the average diameter of the reinforcing fibers is preferably 1 μm or more and 20 μm or less, more preferably 3 μm or more and 15 μm or less, and even more preferably 4 μm or more and 10 μm or less.

[0035] The length of the reinforcing fibers is usually 15 mm or more. The lower limit of the length of the reinforcing fibers is preferably 20 mm or more, more preferably 100 mm or more, and even more preferably 500 mm or more. The maximum upper limit of the length of the reinforcing fibers is preferably the same as the maximum length of the UD sheet, for example, 50 m. Usually, the UD sheet used in the resin molded product described below is a UD sheet that is cut to a desired length after production. Therefore, the length of the reinforcing fibers contained in the UD sheet contained in the resin molded product may be smaller than the minimum length value described above.

[0036] The reinforcing fibers are preferably those obtained by opening fiber bundles bundled with a bundling agent (sizing agent). The number of single yarns in the fiber bundle is not particularly limited, but is usually 100 to 350,000, preferably 1,000 to 250,000, and more preferably 5,000 to 220,000.

[0037] The sizing agent may be any known sizing agent including olefin-based emulsion, urethane-based emulsion, epoxy-based emulsion, nylon-based emulsion, etc., among which olefin-based emulsion is preferred, and ethylene-based emulsion or propylene-based emulsion is more preferred. Examples of the ethylene-based polymer contained in the ethylene-based emulsion include ethylene homopolymer and copolymer of ethylene and α-olefin having 3 to 10 carbon atoms. Examples of the propylene-based polymer contained in the propylene-based emulsion include propylene homopolymer and copolymer of propylene and ethylene or α-olefin having 4 to 10 carbon atoms.

[0038] In particular, from the viewpoint of further enhancing the adhesiveness between the reinforcing fiber bundle and the matrix resin, it is preferable that the sizing agent contains an unmodified polyolefin and a modified polyolefin. The unmodified polyolefin is preferably a homopolypropylene, a homopolyethylene, an ethylene-propylene copolymer, a propylene-1-butene copolymer, or an ethylene-propylene-1-butene copolymer. The modified polyolefin may be, for example, one obtained by graft-introducing a carboxylic acid group, a carboxylic anhydride group, or a carboxylic acid ester group into the polymer chain of the unmodified polyolefin and forming a salt between the functional group and a metal cation. Among these, a modified polyolefin containing a metal carboxylate is more preferable.

[0039] 1-1-2-2. Matrix Resin The matrix resin is a resin composition containing a thermoplastic resin or a thermosetting resin. The matrix resin may contain components other than the filler and other resin components.

[0040] Examples of the thermoplastic resin include polycarbonate resin, styrene resin, polyamide resin, polyester resin, polyphenylene sulfide resin (PPS resin), modified polyphenylene ether resin (modified PPE resin), polyacetal resin (POM resin), liquid crystal polyester, polyarylate, acrylic resin including polymethyl methacrylate resin (PMMA) and the like, vinyl chloride, polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polysulfone, polyethersulfone, polyketone, polyetherketone, polyetheretherketone (PEEK), polyethylene, polypropylene, polybutene, poly4-methyl-1-pentene and the like, polyolefins including modified polyolefins thereof, and phenoxy resin. The polyolefin may be a copolymer including ethylene / propylene copolymers, ethylene / 1-butene copolymers, ethylene / propylene / diene copolymers, ethylene / carbon monoxide / diene copolymers, ethylene / ethyl (meth)acrylate copolymers, ethylene / glycidyl (meth)acrylate, and ethylene / vinyl acetate / glycidyl (meth)acrylate copolymers.

[0041] Examples of the thermosetting resin include epoxy resin, phenol resin, melamine resin, urea resin, diallyl phthalate resin, silicone resin, urethane resin, furan resin, ketone resin, xylene resin, thermosetting polyimide resin, unsaturated polyester resin, and diallyl terephthalate resin.

[0042] Among these, from the viewpoint of further improving the energy absorption amount at the time of impact, thermoplastic resins are preferred, polyamide resins and polyester resins are preferred as resins with higher polarity, and polyolefin resins are preferred as resins with lower polarity. In addition, polypropylene resins and polyamide resins are preferred from the viewpoint of making progressive crushing more likely to occur, reducing costs, and reducing the weight of molded products. In addition, from the viewpoint of increasing the affinity with the reinforcing fibers bundled by the bundling agent, the matrix resin may contain the above-mentioned modified polyolefin.

[0043] The type of the polypropylene resin is not particularly limited, and may be a propylene homopolymer, a propylene copolymer, or a mixture thereof. The stereoregularity of the polypropylene resin is also not particularly limited, and may be isotactic, syndiotactic, or atactic. The stereoregularity is preferably isotactic or syndiotactic.

[0044] The polypropylene resin may be an unmodified polypropylene resin (P1), a modified polypropylene resin (P2) containing a carboxylate or the like bonded to a polymer chain, or a mixture of these, but is preferably a mixture of these. In the mixture, the mass ratio of the unmodified polypropylene resin (P1) to the total mass of the unmodified polypropylene resin (P1) and the modified polypropylene resin (P2) [(P1) / (P1+P2)] is preferably 80% by mass or more and 99% by mass or less, more preferably 85% by mass or more and 98% by mass or less, and even more preferably 90% by mass or more and 97% by mass or less.

[0045] The type of the polyamide resin is not particularly limited, and may be any known polyamide resin. Examples of the polyamide resin include polyamide 6, polyamide 12, polyamide 66, polyamide 11, and aromatic polyamides. Among these, polyamide 6 and polyamide 12 are preferred.

[0046] The melt flow rate (MFR) of the polyamide resin, measured at 230°C under a load of 2.16 kg in accordance with ASTM D1238 after drying at 80°C for 5 hours, is preferably 40 g / 10 min or more, more preferably 40 g / 10 min or more and 400 g / 10 min or less. When the MFR is within this range, the matrix resin can be easily impregnated into the reinforcing fibers sufficiently.

[0047] The weight average molecular weight (Mw) of the polyamide resin is preferably 5,000 or more and 50,000 or less, and more preferably 5,000 or more and 30,000 or less.

[0048] The matrix resin may contain other components such as resins other than those mentioned above and short fibers having a length shorter than that of the reinforcing fibers.

[0049] 1-2. Plate-shaped members The plate-like member 120 and the plate-like member 130 are plate-like members arranged on one end surface and the other end surface of the cylindrical body 110, respectively. One plate-like member 120 is arranged on the side of the impact absorbing material 100 that receives an impact, and can be a pressing member that presses the cylindrical body upon impact to cause and advance progressive crushing. The other plate-like member 130 can be a support member that supports the cylindrical body 110 upon impact. The plate-like member 120 and the plate-like member 130 can also be an assembly part for assembling the impact absorbing material 100 to another member.

[0050] The shape and size of the plate-like member 120 and the plate-like member 130 are not particularly limited and can be set appropriately depending on the application of the impact absorbing material 100. The shape of the surface of the plate-like member that contacts the end face of the cylindrical body 110 is preferably flat. By making it flat, it becomes easier to efficiently generate progressive crushing as a pressing member, and it is possible to increase the support efficiency of the cylindrical member 130 as a supporting member.

[0051] The material of the plate-like members 120 and 130 is not particularly limited, and known metals, resins, etc. can be used.

[0052] Examples of the metals include iron, copper, nickel, gold, silver, platinum, cobalt, zinc, lead, tin, titanium, chromium, aluminum, magnesium, manganese, or alloys thereof (e.g., stainless steel, aluminum alloys, brass, phosphor bronze, etc.) Among these, aluminum-based metals and iron are preferred because of their high strength and versatility, and aluminum and aluminum-based metals are more preferred because of their light weight.

[0053] The resin may be a thermoplastic resin or a thermosetting resin.

[0054] Examples of the thermoplastic resin include polycarbonate resin, styrene resin, polyamide resin, polyester resin, polyphenylene sulfide resin (PPS resin), modified polyphenylene ether resin (modified PPE resin), polyacetal resin (POM resin), liquid crystal polyester, polyarylate, acrylic resin including polymethyl methacrylate resin (PMMA) and the like, vinyl chloride, polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polysulfone, polyethersulfone, polyketone, polyetherketone, polyetheretherketone (PEEK), polyethylene, polypropylene, polybutene, poly4-methyl-1-pentene and the like, polyolefins including modified polyolefins thereof, and phenoxy resin. The polyolefin may be a copolymer including ethylene / propylene copolymers, ethylene / 1-butene copolymers, ethylene / propylene / diene copolymers, ethylene / carbon monoxide / diene copolymers, ethylene / ethyl (meth)acrylate copolymers, ethylene / glycidyl (meth)acrylate, and ethylene / vinyl acetate / glycidyl (meth)acrylate copolymers.

[0055] Examples of the thermosetting resin include epoxy resin, phenol resin, melamine resin, urea resin, diallyl phthalate resin, silicone resin, urethane resin, furan resin, ketone resin, xylene resin, thermosetting polyimide resin, unsaturated polyester resin, and diallyl terephthalate resin.

[0056] Among these, thermoplastic resins are preferred from the viewpoint of further improving the amount of energy absorbed during impact. Among thermoplastic resins, polyamide resins and polyolefin resins are preferred from the viewpoint of further improving the amount of energy absorbed during impact, polyolefin resins are more preferred, and polypropylene is even more preferred from the viewpoint of making progressive crushing more likely to occur.

[0057] Moreover, from the viewpoint of increasing the strength of the plate-shaped member 120 and the plate-shaped member 130, the material of these plate-shaped members is preferably a fiber-reinforced resin. The type of the reinforcing fiber is not particularly limited, and may be glass fiber, aramid fiber, alumina fiber, silicon carbide fiber, boron fiber, metal fiber, or the like. The form of the reinforcing fiber is also not particularly limited, and short fibers may be arranged randomly, or long fibers oriented in one direction may be arranged. From the viewpoint of increasing the strength of the plate-shaped member 120 and the plate-shaped member 130, it is preferable that long fibers oriented in one direction are arranged, and it is more preferable that the long fibers are impregnated with a thermoplastic resin (preferably a polyamide resin and a polyolefin resin, more preferably a polyolefin resin, and even more preferably polypropylene). When the long fibers are arranged, the long fibers may be woven, or a plurality of layers containing the long fibers oriented in one direction and having different orientation directions of the long fibers may be laminated.

[0058] The resin contained in the cylindrical body 110 and the resin contained in the plate-like member 120 or the plate-like member 130 may be the same or different. However, when both of these resins are thermoplastic resins, it is preferable that both resins are compatible. Note that "compatible" means that a single phase is formed when both resins are heated and mixed at or above their melting points and cooled to 25°C. Furthermore, it is more preferable that both resins are the same. "Identical" means that the monomer composition, weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of both resins are the same within the range of measurement error. If both resins are compatible and even the same, it becomes easier to select an adhesive that has high adhesion to both the cylindrical body and the plate-like member as the material for the adhesive layer, and it becomes possible to further increase the adhesive strength between them.

[0059] 1-3.Adhesive layer The plate-like member 120 and the plate-like member 130 are bonded to the cylindrical body 110 via an adhesive layer 140 and an adhesive layer 150, respectively. It is sufficient that at least one of the plate-like member 120 and the plate-like member 130 is bonded to the cylindrical body 110 via an adhesive layer, but from the viewpoint of further increasing the amount of energy absorption during impact, it is preferable that both of them are bonded to the cylindrical body 110 via an adhesive layer.

[0060] The adhesive layer 140 and the adhesive layer 150 are layers made of an adhesive or a solidified product thereof, and are layers for joining the above-mentioned resin member and metal member. The adhesive layer 140 and the adhesive layer 150 may contain an inorganic substance such as talc or glass beads, or may be a double-sided tape with an adhesive applied to both sides of the tape.

[0061] According to the findings of the present inventors, by bonding the plate-like members 120 and 130 to the cylindrical body 110 via an adhesive layer, it is possible to increase the amount of energy absorbed during impact, compared to when they are simply assembled using a jig or the like as described in Patent Documents 1 and 2. Although the reason for this is unclear, the present inventors speculate that it is because the relatively soft adhesive layers 140 and 150 are disposed between the plate-like members 120 and 130, both of which are hard, and the cylindrical body 110, making it easier to release impact to the outside via the adhesive layers.

[0062] In this specification, the term "adhesion" includes both adhesion and sticking, and there is no distinction between adhesion and sticking. In other words, in this specification, the adhesive layer 140 and the adhesive layer 150 may bond the plate-like member 120 and the plate-like member 130 to the cylindrical body 110 by either adhesion or sticking, and the adhesive includes both a pressure-sensitive adhesive and an adhesive.

[0063] In addition, the formulation of the adhesive in this specification is not particularly limited, and adhesives of known formulations such as liquid type and tape type can be used. Among them, liquid type is preferable from the viewpoint of further increasing the adhesive strength. In addition, as the liquid type, either one-component curing type or two-component curing type can be used.

[0064] The thickness of the adhesive layer 140 and the adhesive layer 150 is appropriately selected depending on the type of adhesive, etc., but is preferably 10 μm or more and 3000 μm or less, more preferably 30 μm or more and 2000 μm or less, and even more preferably 50 μm or more and 1000 μm or less. When the adhesive layer is 10 μm or more thick, the cylindrical body 110 and the plate-like member 120 and the plate-like member 130 can be firmly bonded to each other. When the adhesive layer is 500 μm or less thick, the strength of the impact absorbing material 100 can be increased.

[0065] The type of adhesive constituting the adhesive layer 140 and the adhesive layer 150 is not particularly limited and is appropriately selected according to the type and shape, etc. of the cylindrical body 110, the plate-like member 120, and the plate-like member 130. Examples of the adhesive for forming the adhesive layer 140 and the adhesive layer 150 include an acrylic adhesive, an epoxy adhesive, a urethane adhesive, and a cyanoacrylate adhesive.

[0066] The acrylic adhesive can be used without any particular limitation as long as it is a known (meth)acrylic adhesive. The (meth)acrylic adhesive may be a one-liquid type or a two-liquid type. In this specification, (meth)acrylic means at least one of acrylic and methacrylic, and (meth)acrylate means at least one of acrylate and methacrylate. Acrylic means at least one of acrylic and methacrylic.

[0067] Examples of one-component (meth)acrylic adhesives include heat-curable or light-curable adhesives containing a (meth)acrylic acid ester and / or a (meth)acrylic acid ester polymer, and a polymerization initiator and / or a crosslinking agent.

[0068] Examples of two-liquid acrylic adhesives include those having a first liquid containing a (meth)acrylic acid ester monomer and an organic peroxide, and a second liquid containing a (meth)acrylic acid ester monomer and a reducing agent. Examples of two-liquid acrylic adhesives also include those having a first liquid containing a (meth)acrylic polymer containing a crosslinkable functional group, and a second liquid containing a crosslinking agent. Examples of two-liquid acrylic adhesives also include those having a first liquid containing a (meth)acrylic acid ester monomer and a second liquid containing a (meth)acrylic acid ester monomer and / or a polymerization initiator. These are merely examples and do not limit the acrylic adhesives.

[0069] Examples of (meth)acrylic acid ester monomers contained in the first and / or second liquid of the two-component acrylic adhesive include methyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, glycidyl (meth)acrylate, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and the like.

[0070] The organic peroxide contained in the first liquid of the two-liquid acrylic adhesive may be any compound capable of generating radicals to vinyl polymerize (meth)acrylic acid ester monomers. Examples of organic peroxides include hydroperoxides, alkyl peroxides, diacyl peroxides, ketone peroxides, and the like. Examples of polymerization initiators contained in the two-liquid acrylic adhesive include the above-mentioned organic peroxides and azo compounds. Examples of azo compounds include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (ABVN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), and 2,2'-azobis(isobutyrate) dimethyl.

[0071] Examples of the reducing agent contained in the second liquid of the two-liquid acrylic adhesive include thiourea compounds, metal chelate compounds, metal soaps, tertiary amines, polyamines, mercaptans, and the like.

[0072] Examples of the (meth)acrylic polymer containing a crosslinkable functional group contained in the first liquid of the two-liquid acrylic adhesive include the above-mentioned polymer containing a (meth)acrylic acid ester monomer, etc. Examples of the crosslinking agent contained in the second liquid include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a carbodiimide-based crosslinking agent, a polyfunctional (meth)acrylate, etc.

[0073] The epoxy adhesive may be a one-liquid type or a two-liquid type. Examples of one-liquid type epoxy adhesives include room temperature curing or heat curing compositions containing a latent curing agent such as ketimine, oxazolidine, or aldimine-based compound and a liquid epoxy resin.

[0074] Examples of two-liquid epoxy adhesives include those having a first liquid containing an epoxy resin and a second liquid containing a curing agent. Examples of epoxy resins contained in the first liquid include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, novolac type epoxy resins, etc. On the other hand, examples of curing agents contained in the second liquid include amine-based curing agents such as chain aliphatic amines, cyclic aliphatic amines, aromatic amines, nitrogen-containing aromatics such as imidazole compounds, etc., amidoamine curing agents, ketimines, etc.

[0075] The urethane adhesive may be a one-component type or a two-component type. Examples of one-component urethane adhesives include moisture-curing adhesives that contain a urethane prepolymer having an isocyanate group.

[0076] Examples of two-liquid urethane adhesives include those having a first liquid containing an isocyanate and a second liquid containing a component capable of reacting with the isocyanate. Examples of urethane prepolymers contained in the first liquid include isocyanates such as methylene bis(p-phenylene diisocyanate), tolylene diisocyanate, hexamethylene diisocyanate, 1-chlorophenyl diisocyanate, 1,5-naphthylene diisocyanate, thiodipropyl diisocyanate, ethylbenzene-α-2-diisocyanate, 4,4,4-triphenylmethane triisocyanate, pentamethylene diisocyanate, bis(isocyanatomethyl)cyclohexane, and m-xylylene diisocyanate.

[0077] Examples of components contained in the second liquid that can react with isocyanates include ethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, glycerol, hexanetriol, xylylenediol, monoglyceride laurate, monoglyceride stearate, monoglyceride oleate, polyethylene glycol, polypropylene glycol, polyester polyol, polyamine (and polyamide), and the like.

[0078] Examples of cyanoacrylate adhesives include those containing methyl cyanoacrylate, ethyl cyanoacrylate, methoxyethyl cyanoacrylate, butyl cyanoacrylate, octyl cyanoacrylate, and the like.

[0079] From the viewpoint of further increasing the amount of energy absorption during impact, it is preferable that the adhesive layer 140 and the adhesive layer 150 contain an acrylic adhesive or a cured product thereof. Although the reason why the amount of energy absorption increases by using an acrylic adhesive is unclear, it is considered that this is because there is no clear yield point in the load-displacement curve, so progressive crushing is efficiently exerted and the impact absorbing material 100 can more easily absorb energy.

[0080] 1-4. Manufacturing method of shock absorbing material FIG. 4 is a flow chart showing an example of a method for manufacturing the above-mentioned impact absorbing material.

[0081] The above-mentioned impact absorbing material can be produced by a method including a step of preparing a cylindrical body including a laminate of fiber-reinforced resin layers including a plurality of reinforcing fibers arranged in one direction and a resin impregnated into the plurality of reinforcing fibers (step S410), and a step of bonding a plate-shaped member to an end face of the cylindrical body with an adhesive (step S420).

[0082] 1-4-1. Step S410: Preparation of cylindrical body In this step, the cylindrical body is prepared.

[0083] The method of producing the cylindrical body is not particularly limited. For example, when a thermoplastic resin is used as the resin of the cylindrical body, a tape-shaped unidirectional reinforced fiber resin sheet (hereinafter, also simply referred to as "Uni-Directional (UD) tape") made by impregnating a plurality of reinforcing fibers oriented and arranged in one direction with a thermoplastic resin can be produced by wrapping it around a mandrel and fusing it. When a thermosetting resin is used as the resin of the cylindrical body, a tape-shaped unidirectional reinforced fiber resin prepreg made by impregnating a plurality of reinforcing fibers oriented and arranged in one direction with an uncured thermosetting resin can be produced by wrapping it around a mandrel and curing the resin. Also, a previously produced cylindrical body may be prepared by purchasing, etc.

[0084] FIG. 5 is a schematic diagram showing a typical configuration of an apparatus 500 for producing a cylindrical body containing a thermoplastic resin as the resin.

[0085] The apparatus 500 has a rotating mandrel 510 and a fusion unit 520 that produces a cylindrical body by fusing the UD tape 530 to the surface of the mandrel 510. In the apparatus 500, a control unit (not shown) rotates the mandrel 510 and causes each component of the fusion unit 520 to perform the following operations.

[0086] In this specification, the surface of the mandrel 510 means either the surface of the mandrel 510 that comes into contact with the UD tape 530, or the surface of the UD tape 530 that has already been wound around the mandrel 510 and fused to the mandrel 510.

[0087] Mandrel 510 is supported at both ends by rotational supports 504a and 504b which are held by supports 502a and 502b, respectively, and is rotated by the rotation of rotational supports 504a and 504b.

[0088] The fusion unit 520 has a storage section 521 that stores the UD tape 530 wound in a roll shape so that it can be unwound, a guide roller 522 that supports the UD tape 530 unwound from the storage section 521 and guides it to the mandrel 510, a laser irradiation section 524 which is an objective lens unit that irradiates the UD tape 530 supplied to the mandrel 510 with a laser emitted from a laser oscillation source 524a, and a pressing roller 525 that presses the UD tape 530 supplied to the mandrel 510 toward the surface of the mandrel 510.

[0089] The storage section 521 stores the UD tape 530 wound in a roll shape, and pays out the UD tape 530 when the cylindrical body is produced. The guide roller 522 is disposed in contact with the moving path of the UD tape 530 connecting the storage section 521 and the mandrel 510, and guides the UD tape 530 moving along the moving path to the surface of the mandrel 510 while supporting it under tension. The laser irradiation section 524 is optically connected to a laser oscillation source 524a disposed outside the fusion unit 520 by an optical fiber or the like, and emits a laser oscillated by the laser oscillation source 524a while converging it with an objective lens. Specifically, the laser irradiation section 524 emits the laser so that the laser is irradiated to at least one of the surfaces of the UD tape 530 and the mandrel 510 immediately before or when the moving UD tape 530 and the surface of the mandrel 510 come into contact with each other. The pressing roller 525 presses the UD tape 530 supplied to the mandrel 510 down toward the surface of the mandrel 510. In a state in which at least one of the UD tape 530 supplied to the mandrel 510 and the UD tapes 530 already wound around the mandrel 510 and fused to each other is melted by laser irradiation, the supplied UD tape 530 is pressed down toward the surface of the mandrel 510, whereby the supplied UD tapes 530 are fused to each other and formed into the shape of the cylindrical body.

[0090] The fusion unit 520 houses the above-mentioned components inside a robot arm. The fusion unit 520 fuses the UD tape 530 while moving back and forth along the axial direction of the rotating mandrel 510 while moving parallel to the guide part 526. The fusion unit 520 is also configured to be capable of vertical and rotational movement. By changing the angle at which the UD tape 530 contacts the surface of the mandrel 510 through rotational movement, the above-mentioned cylindrical body having multiple layers in which the reinforcing fibers are oriented in different directions can be produced.

[0091] The angle at which the UD tape 530 contacts the surface of the mandrel 510 may be determined according to the orientation angle of the reinforcing fibers in each fiber reinforced resin layer included in the cylindrical body. In this embodiment, a buckling suppression layer with a large orientation angle is formed by increasing the angle at which the UD tape 530 contacts the surface of the mandrel 510, and a buckling suppression layer with a large orientation angle is formed by decreasing the angle at which the UD tape 530 contacts the surface of the mandrel 510.

[0092] The cylindrical body thus produced and pulled out from the mandrel 510 is a long cylindrical body, and includes a laminate of fiber-reinforced resin layers in which a plurality of reinforcing fibers aligned in one direction are impregnated with resin. The laminate has one or more buckling-suppressing layers and one or more fragile layers, in which the orientation angles of the reinforcing fibers in the fiber-reinforced resin layers are different. The cylindrical body may then be subjected to a surface treatment or the like. The cylindrical body is cut to a desired size for use.

[0093] 1-4-2. Step S420: Bonding plate-like members Next, a plate-like member is attached to the end face of the prepared cylindrical body using an adhesive.

[0094] Specifically, first, a plate-like member is prepared.

[0095] The plate-like member can be molded by a known molding method. For example, a plate-like member in which long fibers are arranged in one direction can be produced by stacking a plurality of the unidirectional reinforced fiber resin sheets and press molding them. In this case, it is also possible to obtain a plate-like member in which a plurality of layers having different long fiber orientation directions are laminated by changing the orientation direction of the reinforcing fibers in each of the stacked unidirectional reinforced fiber resin sheets.

[0096] This plate-like member may be formed with fastening holes or the like for assembling the impact absorbing material to another member.

[0097] Next, the adhesive is applied to at least one of the end face of the prepared cylindrical body and the surface of the plate-like member, and preferably to both. When applying the adhesive to the surface of the plate-like member, the adhesive may be applied to the surface where the end face of the cylindrical body is bonded.

[0098] In order to enhance the adhesive strength of the adhesive, the end faces of the cylindrical body and the surface of the plate-like member may be pretreated before the adhesive is applied. Examples of the pretreatment include degreasing, and primer treatment and plasma treatment according to the type of adhesive. For example, when a cyanoacrylate adhesive is used, it is preferable to perform a primer treatment on the end faces and surfaces. Furthermore, when a urethane adhesive or an epoxy adhesive is used, it is preferable to perform a plasma treatment on the end faces and surfaces.

[0099] Then, by pressing and leaving the adhesive to stand, or by heating as necessary, the adhesive can be hardened to obtain an impact absorbing material in which the plate-like member is attached to the cylindrical body via an adhesive layer.

[0100] 2.Applications The application of the impact absorbing material is not limited, but it can be used as an impact absorbing member in automobile parts, motorbikes, bicycles, snowmobiles, and other transport equipment, etc. In particular, it can be preferably used as an impact absorbing member in automobiles, such as door reinforcements, impact beams, bumper beam extensions, and crash boxes.

[0101] 3. Other embodiments The configuration of the impact absorbing material is not limited to the above-mentioned configuration. For example, Fig. 1 shows an impact absorbing material having only one cylindrical body. However, the impact absorbing material may have two, three, or more cylindrical bodies, and all of these cylindrical bodies may be bonded to the same plate-like member.

[0102] Furthermore, the configuration of the buckling suppression layer and the fragile layer is not limited to the above-mentioned fiber reinforced resin layers stacked together, but may be a combination of layers with different interlayer peel strengths and intralayer buckling strengths, such as a combination of a stampable sheet and a UD sheet, or a combination of a short fiber reinforced resin sheet and a UD sheet. EXAMPLES

[0103] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to the descriptions in the examples.

[0104] 1. Preparation of UD sheet 1-1. Preparation of sizing agent A mixture obtained by mixing 100 parts by mass of propylene-based resin A, 10 parts by mass of propylene-based resin B, and 3 parts by mass of a surfactant was fed from the hopper of a twin-screw extruder (manufactured by Ikegai Iron Works Co., Ltd., PCM-30, L / D=40) at a rate of 3000 g / hour. Furthermore, a 20% aqueous potassium hydroxide solution was continuously fed at a rate of 90 g / hour from a feed port provided in the vent of the extruder, and the mixture was continuously extruded at a heating temperature of 210°C. The extruded resin mixture was cooled to 110°C with a jacketed static mixer installed at the extrusion port, and further poured into warm water at 80°C to obtain an emulsion with a solid content concentration of 45%.

[0105] Propylene-based resin A was a propylene-butene-ethylene copolymer. Propylene-based resin A had a weight average molecular weight of 120,000 as measured by GPC and did not have a melting point.

[0106] Propylene-based resin B is a modified resin obtained by mixing 96 parts by mass of propylene-butene copolymer, 4 parts by mass of maleic anhydride, and 0.4 parts by mass of a polymerization initiator (manufactured by NOF Corporation, trade name Perhexy 25B), and modifying the mixture at a heating temperature of 160°C for 2 hours.

[0107] The surfactant is also potassium oleate.

[0108] 1-2.Carbon fiber A carbon fiber bundle (manufactured by Mitsubishi Rayon Co., Ltd., product name Pyrofil TR50S12L, number of filaments 24,000, strand strength 5,000 MPa, strand modulus 242 GPa) was immersed in acetone and subjected to ultrasonic waves for 10 minutes, after which the carbon fiber bundle was pulled out and washed with acetone three times, and then dried at room temperature for 8 hours to remove the sizing agent that had adhered to the carbon fiber bundle.

[0109] 1-3. Sizing process The emulsion was applied to the carbon fiber by roller impregnation. After that, the carbon fiber was dried online at 130°C for 2 minutes to remove low boiling point components, and a sheet-like reinforcing fiber bundle was obtained. The amount of emulsion applied to the reinforcing fiber bundle was 0.87% by mass.

[0110] 1-4. Resin impregnation 57 parts by mass of the sized reinforcing fibers were impregnated with 43 parts by mass of a resin composition containing a masterbatch containing a commercially available unmodified propylene resin, modified polypropylene, and carbon black, and processed into a sheet. The sheet was then cut into a tape shape with a width of 12.5 mm using a slitter to obtain a UD sheet with an average thickness of 150 μm.

[0111] The unmodified propylene resin is manufactured by Prime Polymer Co., Ltd. and has the trade name Prime Polypro J106MG (melting point 160° C.).

[0112] The modified polypropylene is a modified polypropylene grafted with 0.5% by mass of maleic anhydride (melt flow rate measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238: 9.1 g / 10 min, melting point: 155° C.).

[0113] The masterbatch containing carbon black is PEONY (registered trademark) BLACK BMB-16117 (carbon black content: 40%) manufactured by DIC Corporation.

[0114] The resin composition was obtained by mixing 85 parts by mass of the unmodified propylene resin, 15 parts by mass of the modified polypropylene, and the master batch in an amount such that the carbon black content was 1 mass% relative to the total mass of the resin composition.

[0115] 2. Preparation of the cylindrical body A cylindrical body was produced by spirally fusing a tape-like UD sheet onto the surface of a mandrel with an outer diameter of Φ30 mm using an apparatus configured as shown in Figure 5. At this time, the winding angle of the UD sheet relative to the axial direction of the mandrel was set to the angles listed in Table 1, starting from the mandrel side. Cylinder 1 and cylinder 2, both of which had a 16-layer structure, were produced.

[0116] The above device is a robot equipped with a STWH INB type winding head manufactured by AFPT Co., Ltd. The head is configured to perform closed-loop control of a diode laser with an output of 3 kW and a wavelength of 960 to 1070 nm.

[0117] [Table 1]

[0118] Both cylindrical body 1 and cylindrical body 2 had an inner diameter of 30.0 mm, an outer diameter of 35.0 mm, and a length in the longitudinal direction of 55.0 m.

[0119] 3. Preparation of plate-shaped components 3-1. Preparation of plate-like member 1 An aluminum frame cut into 60 mm squares was placed on a brass plate, and a release film, the UD sheet cut into 55 mm x 55 mm size, and a release film were placed on top of that in that order, and a brass plate was placed on top of that to form a substrate. Eight of the UD sheets were stacked so that the carbon fiber orientation angles of the UD sheets from bottom to top were 0°, 90°, 0°, 90°, 90°, 0°, 90°, 0°, when the carbon fiber orientation angle of the bottommost UD sheet was set to 0°, and these were placed inside the cut-out part of the aluminum frame.

[0120] The above-mentioned base material was placed inside the mold of a press machine whose inside was heated to 180°C, and preheated for 4 minutes without pressure. After that, the above-mentioned base material was transferred to a press machine whose inside temperature was set to 15°C, and immediately pressed at 2 MPa and held for 3 minutes. After that, it was cooled at room temperature and the layer of the above-mentioned UD sheet was taken out. This is called the plate-like member 1.

[0121] 3-2. Preparation of plate-like member 2 Plate-like member 2 was obtained in the same manner as plate-like member 1, except that an aluminum frame cut out to 155 mm x 55 mm was used and the above UD sheet cut to a size of 150 mm x 50 mm was used.

[0122] 3-3. Preparation of plate-like member 3 A plate-like member 3 was obtained in the same manner as in the production of the plate-like member 1, except that 8 g of long carbon fiber reinforced polypropylene pellets (manufactured by Polyplastics Co., Ltd., product name Plastron PP-CF-40-11) was used instead of the UD sheet.

[0123] 3-4. Preparation of plate-like member 4 Plate-like member 4 was obtained in the same manner as plate-like member 1, except that 6 g of polypropylene pellets not containing reinforcing fibers (Prime Polypro J106G, manufactured by Prime Polymer Co., Ltd.) was used instead of the UD sheet.

[0124] 4.Preparing the adhesive The following adhesives were prepared: Adhesive 1: Acrylic adhesive (3M, product name DP-8010 Blue, two-component type) Adhesive 2: Acrylic adhesive (Permabond, product name TA4611, two-part type) Adhesive 3: Cyanoacrylate adhesive (manufactured by ThreeBond, product name TB7737, one-liquid type) Adhesive 4: Cyanoacrylate adhesive (LOCTITE, product name 401, one-part type) Adhesive 5: Epoxy adhesive (3M, product name Automix Panel Bond 8115, two-part type) Adhesive 6: Epoxy adhesive (manufactured by Mitsui Chemicals, Inc., product name Structbond EW-D241, two-component type) Adhesive 7: Urethane adhesive (manufactured by E-Tech, product name MIGHTYGRIP MG-5000 (main agent: MIGHTYGRIP MG5000, hardener: MIGHTYGRIP MG5030), two-component type) Adhesive 8: Acrylic double-sided tape (manufactured by Teraoka Manufacturing Co., Ltd., product name Tape No. 773)

[0125] 5. Preparation of shock absorbing material

[0126] 5-1. Preparation of Impact Absorbing Material 1 (Example 1) A cylindrical body 1 and two plate-like members 1 were prepared. Both end faces of the cylindrical body 1 and the surfaces of the plate-like members 1 were degreased with acetone, and then adhesive 1 was applied to both end faces of the cylindrical body 1 and pressed against the degreased surfaces of the plate-like members 1. After applying adhesive to both end faces and pressing them against the surfaces of the plate-like members 1, a 1 kg weight was placed on them and they were left to stand for 24 hours to completely harden the adhesive, thereby producing an impact absorbing material 1 having one cylindrical body 1 to which two plate-like members 1 were attached.

[0127] 5-2. Preparation of Impact Absorbing Material 2 (Example 2) Impact absorbing material 2 having one cylindrical body 1 with two plate-like members 1 attached thereto was manufactured in the same manner as impact absorbing material 1, except that adhesive 2 was used instead of adhesive 1.

[0128] 5-3. Preparation of Impact Absorbing Material 3 (Example 3) Impact absorbing material 3, having one cylindrical body 1 to which two plate-like members 1 were attached, was manufactured in the same manner as impact absorbing material 1, except that adhesive 3 was used instead of adhesive 1, and both end faces of cylindrical body 1 after degreasing and the surfaces of each plate-like member 1 were treated with a primer agent (manufactured by ThreeBond, product name TB7797).

[0129] 5-4. Preparation of Impact Absorbing Material 4 (Example 4) Impact absorbing material 4 having one cylindrical body 1 with two plate-like members 1 attached thereto was manufactured in the same manner as impact absorbing material 3, except that adhesive 4 was used instead of adhesive 3 and SF770 manufactured by Loctite was used as the primer.

[0130] 5-5. Preparation of Impact Absorbing Material 5 (Example 5) Impact absorbing material 5, having one cylindrical body 1 to which two plate-like members 1 were attached, was manufactured in the same manner as impact absorbing material 1, except that adhesive 5 was used instead of adhesive 1 and plasma treatment was performed using an atmospheric pressure plasma device on both end faces of the cylindrical body 1 after degreasing treatment and on the surface of each plate-like member 1.

[0131] 5-6. Preparation of Impact Absorbing Material 6 (Example 6) Impact absorbing material 5 having one cylindrical body 1 with two plate-like members 1 attached thereto was manufactured in the same manner as impact absorbing material 5 except that adhesive 6 was used instead of adhesive 5.

[0132] 5-7. Preparation of Impact Absorbing Material 7 (Example 7) Impact absorbing material 7 having one cylindrical body 1 with two plate-like members 1 attached thereto was manufactured in the same manner as impact absorbing material 5, except that adhesive 7 was used instead of adhesive 5.

[0133] 5-8. Preparation of Impact Absorbing Material 8 (Example 8) Impact absorbing material 8 was manufactured in the same manner as impact absorbing material 1, except that adhesive 8 was applied instead of applying adhesive 1, and the impact absorbing material 8 had one cylindrical body 1 to which two plate-like members 1 were attached.

[0134] 5-9. Preparation of Impact Absorber 9 (Example 9) Impact absorbing material 9 was manufactured in the same manner as impact absorbing material 2, except that plate-like member 3 was used instead of plate-like member 1, and had one cylindrical body 1 to which two plate-like members 1 were attached.

[0135] 5-10. Preparation of impact absorbing material 10 (Example 10) An impact absorbing material 10 having one cylindrical body 1 to which two plate-like members 1 were attached was manufactured in the same manner as the production of the impact absorbing material 2, except that plate-like member 4 was used instead of plate-like member 1.

[0136] 5-11. Preparation of impact absorbing material 11 (Example 11) Two cylindrical bodies 1 and two plate-like members 2 were prepared. After both end faces of each cylindrical body 1 and the surface of each plate-like member 1 were degreased with acetone, adhesive 1 was applied to both end faces of each cylindrical body 1, and both were pressed against the degreased surface of the plate-like member 1. After applying adhesive to both end faces and pressing them against the surface of the plate-like member 1, a 1 kg weight was placed on each end and the material was left to stand for 24 hours to completely harden the adhesive, thereby producing an impact absorbing material 11 having two cylindrical bodies 1 with two plate-like members 1 attached to each end. The distance between the two cylindrical bodies 1 was set to 25 mm, and they were placed in the center of the plate-like member 2.

[0137] 5-12. Preparation of shock absorbing material 12 (Example 12) Three cylindrical bodies 1 and two plate-like members 2 were prepared. After both end faces of each cylindrical body 1 and the surface of each plate-like member 1 were degreased with acetone, adhesive 1 was applied to both end faces of each cylindrical body 1, and both were pressed against the degreased surface of the plate-like member 1. After applying adhesive to both end faces and pressing them against the surface of the plate-like member 1, a 1 kg weight was placed on each end and the material was left to stand for 24 hours to completely harden the adhesive, thereby producing an impact absorbing material 13 having three cylindrical bodies 1 with two plate-like members 1 attached to each end. The three cylindrical bodies 1 were arranged linearly in the center along the longitudinal direction of the plate-like member 2, with a distance of 10 mm between each end.

[0138] 5-13. Preparation of impact absorbing material 13 (Comparative Example 1) One cylindrical body 1 and two plate-like members 1 were prepared. Both end faces of the cylindrical body 1 were pressed against the surfaces of the plate-like members 1, respectively, to produce an impact absorbing material 13 having one cylindrical body 1 with two plate-like members 1 attached thereto.

[0139] 5-14. Preparation of impact absorbing material 14 (Comparative Example 2) An impact absorbing material 14 having one cylindrical body 2 with two plate-like members 1 attached thereto was manufactured in the same manner as in the manufacture of impact absorbing material 2, except that cylindrical body 2 was used instead of cylindrical body 1.

[0140] 6. Evaluation 6-1.Amount of energy absorption (EA) Using a universal testing machine (Shimadzu Corporation, Universal Testing Machine AG-100kNX-Plus), each impact absorbing material was compressed in the axial longitudinal direction at a speed of 3 mm / min with an indenter diameter of Φ200 mm until the crosshead traveled 30 mm, and the load [N] and crosshead travel [mm] were measured.

[0141] The movement of the crosshead was taken as the displacement of the impact absorbing material, and the integral value from 0 mm to 30 mm of displacement in the load-displacement curve obtained in the above test was taken as the energy absorption (EA) amount [J].

[0142] 6-2. Energy absorption per unit area (EA) The unit area of ​​each impact absorbing material was calculated by (outer diameter of cylindrical body ÷ 2) × (outer diameter of cylindrical body ÷ 2) × π - (inner diameter of cylindrical body ÷ 2) × (inner diameter of cylindrical body ÷ 2) × π, and the EA amount per unit area was calculated by EA amount ÷ unit area.

[0143] 6-3. Destruction form The shape of each impact absorbing material after the compression test was visually checked, and when it was confirmed that the cylindrical body was cracking on the outside and inside and curling up as the destruction progressed, it was evaluated as having progressive crushing (PC).When the cylindrical body broke, it was evaluated as having buckling.

[0144] 7.Results The manufacturing conditions and evaluation results of the obtained impact absorbing materials 1 to 14 are shown in Tables 2 to 4. Moreover, the load-displacement curves in Example 2 and Comparative Example 1 are shown in FIG.

[0145] [Table 2]

[0146] [Table 3]

[0147] [Table 4]

[0148] As is clear from Tables 2 to 4, the impact absorbing material having a cylindrical body having a buckling suppression layer and a fragile layer, and a plate-like member bonded to the cylindrical body via an adhesive layer, was destroyed by progressive crushing and had a large energy absorption capacity. Also, as is clear from Figure 6, in Example 2 using an acrylic adhesive, no clear yield point occurred, and even if the displacement became large, a certain amount of load could be absorbed, but in Comparative Example 1, yield occurred, and when the displacement was increased beyond the yield point, the amount of load absorption was extremely reduced.

[0149] This application claims priority from Japanese Patent Application No. 2022-048571, filed March 24, 2022. The matter described in the specification, claims and drawings of that application as originally filed is hereby incorporated by reference into this application. [Industrial Applicability]

[0150] The impact absorbing material of the present invention can be suitably used as an impact absorbing material to be placed in an automobile. [Explanation of symbols]

[0151] 100 Shock Absorbing Material 110 Cylindrical body 112 areas 114, 114a, 114b, 114c, fiber reinforced resin layer 116a, 116c, 116aa, 116cc buckling suppression layer 118b, 118bb Destructible layer 120, 130 Plate-shaped member 140, 150 adhesive layer 210 Reinforced Fiber 220 Resin 500 devices 502a, 502b support 504a, 504b Rotation support part 510 Mandrel 520 Fusion Unit 521 Storage Unit 522 Guide roller 524 Laser irradiation unit 524a Laser Source 525 Pressure Roller 530 UD Tape

Claims

1. An impact absorbing material having a cylindrical body and a plate-like member bonded to an end surface of the cylindrical body, The cylindrical body includes a laminate of fiber-reinforced resin layers including a plurality of reinforcing fibers oriented in one direction and a resin impregnated into the plurality of reinforcing fibers, The cylindrical body has a buckling suppression layer and a fragile layer, The laminate has a layer configuration in which the buckling suppression layer, the fragile layer, and the buckling suppression layer are laminated in this order from the inside to the outside of the cylindrical body, The plate-like member is bonded to the cylindrical body via an adhesive layer. Shock absorbing material.

2. The impact absorbing material according to claim 1 , wherein the adhesive layer comprises an acrylic adhesive or a cured product thereof.

3. The impact absorbing material according to claim 1 , wherein the buckling suppression layer has an angle of 60° or more and 80° or less between the longitudinal direction of the cylindrical body and the direction in which the reinforcing fibers are oriented.

4. The impact absorbing material according to claim 1 , wherein the easily destructible layer has an angle of 5° or more and less than 30° between the longitudinal direction of the cylindrical body and the direction in which the reinforcing fibers are oriented.

5. The buckling suppression layer is disposed on both the outer surface and the inner surface of the cylindrical body. The impact absorbing material according to claim 1.

6. The impact absorbing material according to claim 1 , wherein the plate-shaped member includes a thermoplastic resin.

7. The impact absorbing material according to claim 1 , wherein the fiber reinforced resin layer includes the plurality of reinforcing fibers and a thermoplastic resin impregnated into the plurality of reinforcing fibers.

8. The impact absorbing material according to claim 1 , comprising a plurality of said cylindrical bodies, said plurality of cylindrical bodies being attached to the same said plate-like member.

9. A step of preparing a cylindrical body including a laminate of fiber-reinforced resin layers including a plurality of reinforcing fibers oriented in one direction and a resin impregnated into the plurality of reinforcing fibers, the cylindrical body having a buckling suppression layer and a fragile layer; and bonding a plate-like member to the end surface of the cylindrical body by an adhesive. A manufacturing method for shock absorbing material.

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