Impact energy absorber

Abstract

To provide an impact energy absorber exhibiting an excellent impact energy absorption amount.SOLUTION: An impact energy absorber includes an aluminum extrusion material and a foam body. The aluminum extrusion material is composed of aluminum and has a shape in which a specifically shaped extrusion material cross section is continuous in an extruding direction which is a direction perpendicular to the extrusion material cross section. At least one cavity is provided in the aluminum extrusion material, the cavity being a space present within the extrusion material cross section, at least partially surrounded by the aluminum material, and being continuous in the extruding direction. The foam body is present in at least one of the cavities, and the extrusion material cross section includes a cavity having an occupancy rate (%) representing the percentage of the area occupied by the foam body relative to 100% of the cavity area in the range of 0.6 F×100 to 1.2 F×100.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present invention relates to an impact energy absorber.

Background Art

[0002] Conventionally, in order to absorb the impact during a vehicle collision and protect the human body, impact absorbing members and buffer members have been used in the vehicle body frame. For example, bumper beams for absorbing the impact energy during a vehicle collision are attached to the front and rear portions of the vehicle body frame. Such bumper beams are generally formed of a metal such as iron or an aluminum alloy, and in order to avoid an increase in weight, their interiors have a hollow structure. There are various evaluation methods according to the vehicle collision form, and there is an evaluation in which the side of the vehicle body collides with an obstacle such as a utility pole.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent studies of electric vehicles (EVs), in order to mount more batteries in electric vehicles, it has been necessary to make the crushable space on the side of the vehicle body narrower than before and increase the installation area of the battery. However, in the impact energy absorber described in Patent Document 1, the stroke required for absorbing a predetermined amount of energy is long, and the amount of impact energy absorbed in a short stroke is insufficient for adoption in the crushable space on the side of the EV vehicle body. In addition, in the impact energy absorber described in Patent Document 2, a technique for increasing the impact energy by combining a metal part and a foam is disclosed. However, there is a problem that the foam remains crushed after compression and the battery is damaged due to a rapid load rise.

[0005] An object of the present invention is to provide an impact energy absorber that exhibits an excellent impact energy absorption amount.

Means for Solving the Problems

[0006] That is, the present invention is as follows. [1] Including an aluminum extruded material and a foam, The aluminum extruded material is made of an aluminum material, and has a shape in which an extruded material cross-section of a specific shape is continuous in an extrusion direction perpendicular to the extruded material cross-section, At least one cavity in which at least a part existing in the extruded material cross-section is surrounded by the aluminum material and is a cavity continuous in the extrusion direction is provided in the aluminum extruded material, The foam exists in at least one of the cavities, When the filling rate of the foam ((foaming ratio of the foam - 1) / foaming ratio of the foam) is F, the occupancy rate (%) which is the ratio of the area occupied by the foam to 100% of the area of the cavity is in the range of 0.6F×100 to 1.2F×100, including an extruded material cross-section including a cavity, Impact energy absorber. [2] The impact energy absorber according to [1], including an extruded material cross-section including a cavity in which the occupancy rate is in the range of 0.6F×100 to 1.2F×100 and an extruded material cross-section including a cavity in which the occupancy rate is less than 0.6F×100. [3] The extrusion material cross-section including the cavity where the occupancy rate is in the range of 0.6F×100 to 1.2F×100 is arranged in the left-right direction perpendicular to the traveling direction of the automobile and is arranged at the position closest to the center of gravity of the automobile, and is used to cover at least a part of the end surface in the left-right direction of the cross-member, the impact energy absorber according to [1] or [2]. [4] There is a location where the foam continuously exists over a length of 90% or more with respect to the total length of the extrusion direction of the aluminum extrusion material, the impact energy absorber according to any one of [1] to [3]. [5] The compression strength of the foam is 0.6 MPa or more and 50 MPa or less, the impact energy absorber according to any one of [1] to [4]. [6] The foam is a bead foam, and the average cell diameter of the foam is 500 μm or less, the impact energy absorber according to any one of [1] to [5]. [7] The average thickness of the aluminum material of the aluminum extrusion material is 0.5 mm or more and 5 mm or less, the impact energy absorber according to any one of [1] to [6]. [8] The compression recovery rate, which is the ratio of the thickness after 100 hours at room temperature excluding the weight to the thickness after 100 hours at room temperature with a 10 kg weight placed on a plate-shaped foam with a width of 5 cm, a height of 5 cm, and a thickness of 5 mm, of the foam is more than 100% and 105% or less, the impact energy absorber according to any one of [1] to [7]. [9] The impact energy absorption amount of the impact energy absorber with respect to the mass of the impact energy absorber is 200 J / Kg or more and 5000 J / Kg or less, the impact energy absorber according to any one of [1] to [8].

[10] The foam is a bead foam, the foam has closed cells, and the closed cell ratio of the foam is 20 to 99%, the impact energy absorber according to any one of [1] to [9].

[11] The shock energy absorber according to any one of [1] to

[10] , wherein the foam is a bead foam, the foam has closed cells, and the average foam particle diameter of the foam is 0.1 to 3.0 mm.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a shock energy absorber that exhibits an excellent shock energy absorption amount.

Brief Description of the Drawings

[0008]

Figure 1A

Figure 1B

Figure 1C

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Figure 2B

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 5A

Figure 5B

Figure 6

Figure 7

Figure 8

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Figure 10

BEST MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited to the following description, and can be variously modified and implemented within the scope of the gist. Also, in the present embodiment, A (numerical value) to B (numerical value) means A or more and B or less.

[0010] [Impact Energy Absorber] The impact energy absorber of this embodiment includes an aluminum extrusion and a foam. The aluminum extrusion is made of an aluminum material, and has a shape in which the cross-section of the extrusion with a specific shape is continuous in the extrusion direction perpendicular to the cross-section of the extrusion. The cavity, which is a shape in which at least a part of the space existing within the cross-section of the extrusion and surrounded by the aluminum material is continuous in the extrusion direction, is provided with at least one in the aluminum extrusion, and the foam exists within at least one of the cavities. Further, in the impact energy absorber of this embodiment, when the filling ratio of the foam ((foaming ratio of the foam - 1) / foaming ratio of the foam) is F, the occupancy rate (%), which is the ratio of the area occupied by the foam to 100% of the area of the cavity, is in the range of 0.6F×100 to 1.2F×100, and it includes an extrusion cross-section including the cavity. The impact energy absorber of this embodiment is lightweight and can exhibit excellent bending strength. Here, it is preferable that the aluminum extrusion and the foam are in a physically contacting state, but it is not necessarily limited to a state where they are adhered with an adhesive or the like.

[0011] Hereinafter, this embodiment will be illustrated and described with reference to the drawings. FIG. 1 shows an example of the impact energy absorber of this embodiment. The impact energy absorber 1 of this embodiment includes an aluminum extrusion 2 and a foam 3. The impact energy absorber 1 of this embodiment can exhibit a higher buckling strength than a single aluminum extrusion. Therefore, it can be suitably used as an impact absorbing member installed on the side surface of a cross member or the side part of a battery back, an automobile component such as a bumper or a pillar of a vehicle.

[0012] <Aluminum extrusion> From the viewpoints of being lightweight and having excellent strength, the aluminum extrusion may be an extrusion molded body made of an aluminum material.

[0013] The aluminum extrusion will be described with reference to FIG. 2. The shape of the aluminum extruded material 2 is a shape in which the cross-section 21 of the extruded material with a specific shape is continuous in the extrusion direction perpendicular to the cross-section 21 of the extruded material (Fig. 2(A)). The cross-section 21 of the extruded material is a shape in which the same cross-sectional shape extends continuously in the extrusion direction, and no matter at which point in the extrusion direction it is cut in the direction perpendicular to the extrusion direction, the shape is the same (Fig. 2(B)). The shape of the aluminum extruded material 2 can be appropriately set according to the intended use. The shape of the cross-section 21 of the extruded material is not limited to that shown in Fig. 2(B), and examples include a rectangle, a V-shape, a C-shape, a U-shape, a square shape, an arc shape, and combinations thereof.

[0014] In the cross-section 21 of the extruded material, there are spaces (22a, 22b) at least partially surrounded by the aluminum material. The spaces extend continuously in the extrusion direction and form cavities within the aluminum extruded material. No matter at which point in the extrusion direction it is cut in the direction perpendicular to the extrusion direction, the above spaces have the same shape (Fig. 2(B)). In this specification, a flat part without anything that is at least partially surrounded by the aluminum material within the cross-section of the extruded aluminum material may be referred to as a "space". Also, a three-dimensional part without anything (i.e., a hollow part) in which the above space extends continuously in the extrusion direction may be referred to as a "cavity". The cavity of the above aluminum extruded material is a cavity.

[0015] The above space is at least partially surrounded by the aluminum material 23. The above space may be entirely surrounded by the aluminum material 23 on the outer periphery (22a), or a part of the outer periphery may be surrounded by the aluminum material 23 (22b).

[0016] The number of the above spaces within the cross-section of the extruded material is one or more, preferably two or more, more preferably three or more, and even more preferably four or more. From the perspective of further increasing the impact energy absorption amount, it is preferable that there are a plurality of the above spaces (preferably, the space 22a whose entire outer periphery is surrounded by the aluminum material 23) in the direction in which the impact energy absorber receives an impact. For example, in Fig. 2(B), when receiving an impact in the left-right direction, there are two spaces 22a whose entire outer peripheries are surrounded by the aluminum material 23 in the direction in which the impact is received.

[0017] The shapes of the respective spaces within the cross-section of the extrusion material may be the same or different. Further, the shape of each space is not particularly limited, and examples include a substantially polygonal shape, a substantially circular shape, a curved shape, and combinations thereof.

[0018] From the perspective of further increasing the impact energy absorption amount, the ratio of the total area occupied by the above spaces to the area of 100% of the cross-section of the extrusion material may be 60% or more and less than 100%, more preferably 70 to 99%, and even more preferably 80 to 95%. Note that the area of the cross-section of the extrusion material may be the area surrounded by the aluminum material 23 (for example, the total area of the aluminum material and the space). Here, in the space 22b (Fig. 2(b)) whose part of the outer periphery is surrounded by the aluminum material 23, the above area may be obtained using the virtual line (the dotted line in Fig. 2(b)) connecting the ends of the aluminum material 23 as the outer periphery.

[0019] Examples of the above aluminum material include aluminum, aluminum alloy, etc. The aluminum alloy may contain iron, steel material, stainless steel, copper, copper alloy, manganese, manganese alloy, magnesium, titanium, titanium alloy, silicon, etc. Among them, it is preferable to contain more than 50% by mass of aluminum with respect to 100% by mass of the aluminum material, and more preferably 70% by mass or more.

[0020] The dimensions of the above aluminum extrusion material are not particularly limited, and the cross-section of the extrusion material may have a width of 10 to 10000 mm and a height of 10 to 10000 mm. Further, the length in the extrusion direction may be 10 to 10000 mm.

[0021] From the viewpoints of weight reduction and rigidity, the average thickness of the aluminum material of the above aluminum extruded material is preferably 0.5 to 5 mm. The above average thickness may be the average value of the thicknesses of the aluminum materials in the cross-section of the extruded material.

[0022] The above aluminum extruded material can be manufactured, for example, by extrusion molding.

[0023] The above aluminum extruded material may be surface-treated as necessary for its surface, particularly the surface in contact with the foam. Examples of such surface treatment include sandblasting, polishing, degreasing, etching, surface treatment by dipping or spraying a rust preventive, chromate conversion treatment, phosphate conversion treatment, sulfide conversion treatment, anodized film formation, or fluororesin coating.

[0024] <foam> In the shock energy absorber of this embodiment, the foam 3 is present in at least one of the above cavities 24.

[0025] The foam in the cavity will be described with reference to FIG. 1. In the shock energy absorber of this embodiment, a cross-section of the extruded material in which the foam 3 is present in at least one space (22a, 22b) exists as a cross-section at any point in the extrusion direction. The foam 3 may be present in the space 22a entirely surrounded by the aluminum material, or may be present in the space 22b partially surrounded by the aluminum material, or may be present in both. The shapes, materials, and characteristics of the foams 3 provided in each cavity may be the same or different.

[0026] The foam 3 may exist in the cavity 24 with the same cross-sectional shape in the extrusion direction, or the cross-sectional shape may change in the extrusion direction, or it may be interrupted midway in the extrusion direction. For example, the extruded material cross-section of FIG. 1(B) may be continuous in the entire extrusion direction. In this case, in the upper left cavity, the foam 3 exists continuously over the entire length in the extrusion direction with an occupancy rate of 100%. Also, in the upper right cavity, the foam 3 exists continuously over the entire length in the extrusion direction at a specific occupancy rate. From the viewpoint of reducing costs and weight by increasing the occupancy rate of the foam in the locations where a high impact energy absorption amount is desired and decreasing the occupancy rate in other locations, it is preferable to vary the occupancy rate of the foam in the extrusion direction. For example, the extruded material cross-sections of FIGS. 1(B) and (C) may exist in the extrusion direction. In this case, in the upper right cavity, the occupancy rate of the foam 3 becomes 100% in a part of the extrusion direction (FIG. 1(C)), and is low in other parts (FIG. 1(B)). Also, in the lower left cavity, a specific occupancy rate is achieved in a part of the extrusion direction (FIG. 1(C)), and no foam exists in other parts (FIG. 1(B)). That is, in the lower left cavity, the foam is not continuous in the entire extrusion direction and is interrupted midway.

[0027] (Occupancy rate) The occupancy rate of the foam will be described. From the viewpoint that the impact energy absorption amount in short-stroke deformation of the impact energy absorber of the present embodiment is further increased, when the filling rate of the above-mentioned foam ((the expansion ratio of the above-mentioned foam (cm 3 / g) - 1) / the expansion ratio of the above-mentioned foam (cm 3 / g)) is defined as F, the extrusion material cross-section includes at least a cavity in which the occupancy rate (%) of the area occupied by the above-mentioned foam with respect to the area of 100% of the cavity area is in the range of 0.6F × 100 to 1.2F × 100. The above-mentioned occupancy rate is preferably 0.65F × 100 to 1.0F × 100, more preferably 0.700F × 100 to 0.940F × 100. The area of the cavity refers to the area of one space of the extruded material cross-section 21. Here, in the space 22b (FIG. 2(B)) where a part of the outer periphery is surrounded by the aluminum material 23, the above-mentioned area may be obtained using the virtual line (dotted line in FIG. 2(B)) connecting the ends of the aluminum material 23 as the outer periphery. Among the plurality of spaces in the cross-section of the extruded material, it is preferable that at least one space satisfies the above occupancy rate, more preferably that two spaces satisfy the above occupancy rate, and even more preferably that all spaces satisfy the above occupancy rate. Note that the occupancy rate has an upper limit of 100%.

[0028] The cross-section of the extruded material including the cavity where the occupancy rate is within the above range preferably exists continuously over the entire length in the extrusion direction, preferably exists continuously over a length of 50% or more with respect to the total length in the extrusion direction, more preferably exists continuously over a length of 80% or more, and even more preferably exists continuously over a length of 90% or more. Note that in the continuous length, the occupancy rate may be the same or different as long as it is within the above range.

[0029] From the viewpoint of cost reduction and weight reduction by increasing the occupancy rate of the foam in the locations where a high impact energy absorption amount is desired and decreasing the occupancy rate in other locations, the impact energy absorber of the present embodiment preferably includes a cross-section of an extruded material including a cavity where the occupancy rate is in the range of 0.6F×100 to 1.2F×100 (preferably 0.65F×100 to 1.0F×100, more preferably 0.700F×100 to 0.940F×100), and a cross-section of an extruded material including a cavity where the occupancy rate is less than 0.6F×100 (preferably more than 0.55F×100 and less than or equal to F×100, more preferably 0.10F×100 to 0.50F×100). For example, there may be a cross-section of an extruded material that simultaneously includes a cavity where the occupancy rate is in the range of 0.6F×100 to 1.2F×100 and a cavity where the occupancy rate is less than 0.6F×100, or a cross-section of an extruded material including a cavity where the occupancy rate is in the range of 0.6F×100 to 1.2F×100 and a cross-section of an extruded material including a cavity where the occupancy rate is less than 0.6F×100 may be separate.

[0030] It is preferable that there is a portion where the foam continuously exists over a length of 90% or more with respect to the total length in the extrusion direction of the aluminum extrusion material. Note that the above-mentioned "portion" may be a point on the cross-section of the extrusion material (for example, a point in the space of the cross-section of the extrusion material) where the foam continuously exists in the extrusion direction.

[0031] When the foam 3 is disposed in the cavity 24, the cavity wall surface and the foam 3 may be in contact with each other, or there may be a gap therebetween. From the viewpoint of reducing the remaining crush, it is preferable that there is a gap between the cavity wall surface and the foam. Further, when the cavity wall surface and the foam are in contact with each other, buckling of the aluminum extrusion material at the time of collision can be suppressed, and a sudden impact on the vehicle body can be suppressed.

[0032] The shape of the above-mentioned foam 3 can be appropriately set according to the purpose of use. For example, polyhedral columnar, semi-elliptical spherical or hemispherical, elliptical or (substantially) cylindrical, cylindrical, polyhedral pyramidal, irregular shape, elliptical or (substantially) conical, etc. can be mentioned. From the viewpoint of suppressing the remaining crush, the above-mentioned foam 3 may have a recess in which a part of the outer edge is recessed in the cross-section of the extrusion material. For example, if the foam has a square cross-section, a part of one side may be recessed inside the square. The above-mentioned recess may be one or a plurality. Further, the above-mentioned recess may be provided over the entire length in the extrusion direction, or may be provided in a part of the extrusion direction.

[0033] (Properties) The properties of the above-mentioned foam will be described.

[0034] The above-mentioned foam 3 may be either a closed-cell foam or an open-cell foam, and a closed-cell foam having closed cells is preferable. The above-mentioned foam 3 may be either an extruded foam or a particle foam (that is, a bead foam) obtained by foaming pre-expanded particles. Among them, a bead foam obtained by foaming pre-expanded particles is preferable. Here, the "foamed particles" in this specification refer to the particles that make up the foam 3, and refer to the expanded particles after the final-stage foaming of the pre-foamed particles. In addition, the pre-foamed particles include, for example, spherical or irregular pre-foamed beads and foaming pellets. Also, the "pre-foamed particles" in this specification refer to foaming particles that have not undergone the final-stage foaming, and include the state before and after the implementation of preliminary foaming that is not the final stage.

[0035] -Closed cell ratio- The closed cell ratio of the above-mentioned foam 3 is not particularly limited, but is preferably 20 to 99%, more preferably 30 to 90%, and even more preferably 40 to 80%. When the closed cell ratio is within the above range, the elastic repulsive force is maintained during compression. When the locker structure of the hollow part is crushed, the followability of the metal to deformation is improved. When the metal undergoes buckling deformation, it does not bend suddenly, the load can be dispersed, and the energy absorption amount increases. Note that the closed cell ratio S (%) is calculated by the formula represented by the following formula (1). S (%) = {(Vx - W / ρ) / (Va - W / ρ)} × 100 ···(1) In the above formula (1), Vx is the true volume (cm 3 ) of the foam 3, Va is the apparent volume (cm 3 ) of the foam 3, W is the weight (g) of the foam 3, and ρ is the resin density (g / cm 3 ) of the foam 3.

[0036] -Expansion ratio- From the perspective of weight reduction, the expansion ratio of the above-mentioned foam 3 is preferably 1.5 cm 3 / g or more, more preferably 3.0 cm 3 / g or more. Also, from the perspective of maintaining the elastic repulsive force during compression, it is preferably less than 20 cm 3 / g, more preferably less than 15 cm 3is less than or equal to / g. Here, the expansion ratio means how much the volume has expanded from the state of the base resin through the inclusion (impregnation) of the blowing agent, pre-foaming, and final-stage foaming. In this specification, the expansion ratio can be calculated as the reciprocal of the above density (g / cm 3 ).

[0037] -Particle diameter of pre-foamed particles- When the above foam 3 is a bead foam, the particle diameter of the pre-foamed particles is preferably 0.1 mm or more and 3.0 mm or less.

[0038] -Average foam particle diameter- The average foam particle diameter of the above foam 3 is preferably 0.1 to 3.0 mm, more preferably 0.3 to 2.5 mm, and even more preferably 0.5 to 2.0 mm. The average foam particle diameter of the foam can be measured by the method described in the examples below.

[0039] -Average bubble diameter- When the above foam 3 is a bead foam, from the viewpoint that the load dispersion is improved when the bubbles are compressed and deformed before buckling, the average bubble diameter of the foam constituting the bead foam is preferably 500 μm or less, more preferably 200 μm or less. Also, from the viewpoint of maintaining the thickness of the resin film separating the bubbles and suppressing bubble breakage, the above average bubble diameter is preferably 10 μm or more, more preferably 20 μm or more. The average bubble diameter of the foam can be measured by the method described in the examples below.

[0040] -Filling ratio F- From the viewpoint that the above foam 3 can have the effect of dispersing the buckling load of the foam and suppressing a sudden increase in load due to remaining crushing, the filling ratio F calculated by the following formula is preferably 0.33 to 0.95, more preferably 0.5 to 0.94, and even more preferably 0.67 to 0.93. Filling ratio F = (expansion ratio (cm 3 / g) - 1) / expansion ratio (cm 3 / g)

[0041] -Compressive strength- From the viewpoint of further increasing the impact energy absorption amount, the compressive strength of the foam 3 is preferably 0.6 to 50 MPa, more preferably 0.7 to 30 MPa, and still more preferably 1.0 to 25 MPa. The above compressive strength can be measured by the method described in the examples below.

[0042] -Compression recovery rate- From the viewpoint of the creep resistance characteristics of the foam without using fixing means such as an adhesive for the energy absorber, the compression recovery rate of the foam 3 is preferably more than 100% and 105% or less, more preferably 100.02 to 104%, and still more preferably 100.04 to 103%. The above compression recovery rate is the ratio of the thickness after 100 hours at room temperature without the weight to the thickness after 100 hours at room temperature with a 10 kg weight placed on a plate-shaped foam with a width of 5 cm, a height of 5 cm, and a thickness of 5 mm (thickness after removing the weight / thickness when the weight is placed × 100), and can be measured by the method described in the examples below.

[0043] (Composition) The composition of the above foam will be described.

[0044] The above foam 3 preferably contains a thermoplastic resin. The above-mentioned thermoplastic resin is not particularly limited. For example, polyacetal, polystyrene, poly-α-methylstyrene, styrene maleic anhydride copolymer, blend or graft polymer of polyphenylene oxide and polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene polymer, styrene-butadiene copolymer, high-impact polystyrene and other styrene polymers; polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, chlorinated polyvinyl chloride, copolymer of ethylene or propylene and vinyl chloride and other vinyl chloride polymers; polyvinylidene chloride copolymer resin; nylon-6, nylon-6,6 and other homopolymer and copolymer polyamide resins; polybutylene terephthalate, polyethylene terephthalate and other homopolymer and copolymer polyester resins; polyether resins such as polyethersulfone, polyetheretherketone; polyphenylene ether resin, modified polyphenylene ether resin (phenylene ether-polystyrene alloy resin); polycarbonate resin; imide resins such as polyamideimide, polyimide, polyetherimide, methacrylimide; polyphenylene sulfide resin; polysulfone resin; polyethersulfone resin; phenol resin; urethane resin; polyolefin resins such as polypropylene or polymethylpentene; polyester resins; fluorine resins such as polyvinylidene fluoride or polytetrafluoroethylene; and the like.

[0045] Examples of the above-mentioned polyolefin resins include polypropylene resins such as polypropylene polymerized using a Ziegler catalyst or a metallocene catalyst, ethylene-propylene random copolymer, propylene-butene random copolymer, ethylene-propylene block copolymer, ethylene-propylene-butene terpolymer, etc., and polyethylene resins such as low-density polyethylene, medium-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ionomer resin, etc.

[0046] The above-mentioned polyphenylene ether-based resin refers to a polymer represented by the following general formula (1). Here, in general formula (1), R1, R2, R3, and R4 are each independently hydrogen, halogen, an alkyl group, an alkoxy group, a phenyl group, or a haloalkyl group or haloalkoxy group having at least two carbon atoms between the halogen and the benzene ring in general formula (1) and not containing a tertiary α-carbon. Also, n is an integer representing the degree of polymerization.

Chemical formula

[0047] The weight average molecular weight of the above-mentioned polyphenylene ether-based resin is preferably 20,000 to 60,000.

[0048] Examples of the polyphenylene ether resin include, but are not limited to, poly(2,6-dimethyl-1,4-phenylene) ether, poly(2,6-diethyl-1,4-phenylene) ether, poly(2-methyl-6-ethyl-1,4-phenylene) ether, poly(2-methyl-6-propyl-1,4-phenylene) ether, poly(2,6-dipropyl-1,4-phenylene) ether, poly(2-ethyl-6-propyl-1,4-phenylene) ether, poly(2,6-dibutyl-1,4-phenylene) ether, poly(2,6-didodecyl-1,4-phenylene) ether, poly(2,6-diphenyl-1,4-diphenylene) ether, poly(2,6-dimethoxy-1,4-phenylene) ether, poly(2,6-diethoxy-1,4-phenylene) ether, poly(2-methoxy-6-ethoxy-1,4-phenylene) ether, poly(2-ethyl-6-stearyloxy-1,4-phenylene) ether, poly(2,6-dichloro-1,4-phenylene) ether, poly(2-methyl-6-phenyl-1,4-phenylene) ether, poly(2,6-dibenzyl-1,4-phenylene) ether, poly(2-ethoxy-1,4-phenylene) ether, poly(2-chloro-1,4-phenylene) ether, poly(2,6-dibromo-1,4-phenylene) ether, etc. Among these, those in which R1 and R2 are alkyl groups having 1 to 4 carbon atoms, and R3 and R4 are hydrogen atoms or alkyl groups having 1 to 4 carbon atoms are particularly preferred. These may be used alone or in combination of two or more kinds.

[0049] Particularly preferred thermoplastic resins include polyphenylene ether resins, polyolefin resins, polyamide resins, polyester resins, polyether resins, methacrylic resins, modified polyether resins (phenylene ether-polystyrene alloy resins), etc. Among them, polyphenylene ether resins are preferred. The above thermoplastic resins may be used alone or in combination. The resin component contained in the foam is preferably only a polyphenylene ether resin. Further, the above thermoplastic resin may be used in an uncrosslinked state, or may be crosslinked by a peroxide, radiation, or the like before use.

[0050] The mass ratio of the above thermoplastic resin to the total amount (100% by mass) of the impact energy absorber is preferably 5 to 50% by mass, more preferably 10 to 40% by mass.

[0051] In addition, in this embodiment, when it is necessary to adjust the average cell diameter of the pre-expanded particles when forming the foam 3, a cell regulator may be contained. Examples of the cell regulator include talc, silica, calcium silicate, calcium carbonate, aluminum oxide, titanium oxide, diatomaceous earth, clay, sodium bicarbonate, alumina, barium sulfate, aluminum oxide, bentonite, etc. The amount used is usually 0.005 to 2 parts by mass with respect to 100 parts by mass of the total amount of the raw materials of the pre-expanded particles.

[0052] The above pre-expanded particles can be obtained by containing (impregnating) a foaming agent in the pelletized thermoplastic resin to cause foaming. This foaming is pre-foaming, not the final-stage foaming. Examples of the foaming agent used in the production of the above pre-expanded particles include volatile foaming agents. Examples of the volatile foaming agents include chain or cyclic lower aliphatic hydrocarbons such as methane, ethane, propane, butane, isobutane, pentane, isopentane, neopentane, hexane, heptane, cyclopentane, cyclohexane, methylcyclopentane; halogenated hydrocarbons such as dichlorodifluoromethane, trichloromonofluoromethane, 1-chloro-1,1-difluoroethane, 1-chloro-2,2,2-trifluoroethane; and inorganic gas-based foaming agents such as nitrogen, air, and carbon dioxide.

[0053] The average particle diameter of the above pre-expanded particles can be measured by a classification method using a standard sieve defined in JIS Z8801-1:2006 for 100 g of the pre-expanded particles. The average particle diameter of the above pre-expanded particles is preferably 1.0 to 4.0 mm, more preferably 1.2 to 3.0 mm.

[0054] As the method for producing the above-mentioned pre-expanded particles, (i) a method utilizing the thermoplasticity of a thermoplastic resin, (ii) a method by post-processing such as cutting a solid-state thermoplastic resin, etc. are possible, and any method that can impart a desired outer shape to the particles can be applied. Among them, as a method excellent in productivity and capable of producing particles with a stable shape, a profile extrusion method using a die provided with an extrusion cross-section can be preferably used. As the profile extrusion method, a method in which a base resin pellet obtained by melting and extruding a thermoplastic resin by an extruder and pelletizing it by an industrially commonly used method such as strand cutting or underwater cutting is foamed to obtain pre-expanded particles; and a method in which a foaming agent is injected into the extruder from the middle of the barrel and foamed simultaneously with extrusion, and after cooling, it is underwater cut or strand cut to directly obtain pre-expanded particles; a method in which a thermoplastic resin is melted in an extruder, extruded from a die having a desired cross-sectional shape, and after cooling, it is cut to a predetermined length by a pelletizer to produce a base resin pellet, and the base resin pellet is impregnated with a foaming agent and heated to foam at a predetermined expansion ratio; etc., can be manufactured by arbitrarily applying conventionally known methods.

[0055] The method of containing (impregnating) a foaming agent in a thermoplastic resin is not particularly limited and may be a generally used method. Although the method is not particularly limited, for example, a method performed using an aqueous medium in a suspension system such as water (suspension impregnation), a method using a thermal decomposition type foaming agent such as sodium bicarbonate (foaming agent decomposition), a method in which a gas is used as an atmosphere at a critical pressure or higher and brought into a liquid phase state and brought into contact with the base resin (liquid phase impregnation), a method in which a gas is used as an atmosphere at a pressure less than the critical pressure and brought into a gas phase state and brought into contact with the base resin (gas phase impregnation), etc. can be mentioned.

[0056] In addition to the above-mentioned thermoplastic resin, the above-mentioned foam 3 may further contain a compounding agent as necessary. Examples of the above compounding agents include metal oxide compounds, antioxidants, light stabilizers, ultraviolet absorbers, flame retardants, bubble regulators, foaming agents, colorants such as dyes or pigments, plasticizers, lubricants, crystallization nucleating agents, and inorganic fillers such as calcium carbonate. The above compounding agents may be used alone or in combination of two or more.

[0057] As shown in FIGS. 3 and 4, the impact energy absorber of the present embodiment can be disposed around the cross members (41, 42) of the automobile 4 and used as an impact absorbing material. A cross member is a member used to improve the rigidity and strength of a vehicle body, and is provided in the left - right direction (lateral direction of the automobile) perpendicular to the traveling direction of the automobile (for example, three cross members are provided in the example of FIG. 3). In this specification, among the plurality of cross members 41, the cross member disposed at the position closest to the center of gravity of the automobile may be referred to as the center - of - gravity cross member 42.

[0058] An example of disposing the impact energy absorber of the present embodiment on the side surface of the automobile 4 (for example, the lower surface of the automobile 4 and the side surfaces of the cross members 41, 42) will be described with reference to FIG. 4. FIG. 4(A) is a schematic view of the lower surface of the automobile 4 of FIG. 3 in which three cross members are provided. The side indicated as "front of the vehicle body" is the front of the automobile, and the opposite side is the rear. Also, the direction from the front side to the rear side is the extrusion direction of the impact energy absorber 1. Hereinafter, the direction from the front to the rear of the automobile may be referred to as the "front - rear direction" or "traveling direction", and the direction perpendicular to the front - rear direction in which the cross members 41, 42 extend may be referred to as the "left - right direction". The impact energy absorber 1 of the present embodiment may be disposed on both side surfaces of the automobile 4 with the cross members 41, 42 interposed therebetween, or may be disposed on one side surface (FIG. 4(A)). It may be disposed over the entire length in the front - rear direction of the automobile 4 (FIG. 4(A)), or may be disposed partially. The impact energy absorber 1 disposed on the side of the vehicle 4 is preferably arranged such that the above occupancy rate changes according to the position of the cross member from the viewpoints of cost and weight reduction. The extruded material cross section including a cavity having an occupancy rate in the range of 0.6F×100 to 1.2F×100 (preferably 0.65F×100 to 1.0F×100, more preferably 0.700F×100 to 0.940F×100) is arranged to cover at least a part of the left and right end faces in the left and right direction perpendicular to the traveling direction of the vehicle, of a cross member (preferably the center of gravity cross member) (Fig. 4(A)). For example, an extruded material cross section with a high occupancy rate may be arranged to cover the entire left and right end faces in the left and right direction of the cross member, and an extruded material cross section with a low occupancy rate (for example, less than 0.6F×100, preferably more than 0.55F×100 and less than or equal to F×100, more preferably 0.10F×100 to 0.50F×100) may be arranged in other parts (Fig. 4(A)(B)(C)). In particular, by arranging the extruded material cross section with a high occupancy rate so as to cover at least a part (preferably the entire end face) of the left and right end faces in the left and right direction of the center of gravity cross member, it is further excellent in terms of low cost and weight reduction. Also, by increasing the energy absorption amount at a short stroke around the cross member, in addition to low cost and weight reduction, the battery is less likely to be damaged. The impact energy absorber of the present embodiment may be arranged in the direction in which the cross member extends (the direction perpendicular to the vehicle body front-rear direction in Fig. 4), and may be arranged in contact with the cross member (Fig. 4(A)) or may be arranged away from the cross member. Here, Fig. 4(B) is a K-K cross section of the impact energy absorber 1 of the present embodiment attached to the side of the vehicle 4, and Fig. 4(C) is an L-L cross section. The impact energy absorber 1 in Figs. 4(B) and (C) is an impact energy absorber having one cavity in which a space surrounded by an aluminum material over the entire outer periphery extends in the extrusion direction.

[0059] <Manufacturing method> The impact energy absorber of this embodiment can be manufactured, for example, by a method of inserting a foam into an aluminum extrusion, a method of foaming pre-expanded particles within an aluminum extrusion, or the like.

[0060] A cavity (22b) in which a part of the outer periphery is surrounded by an aluminum material and extends in the extrusion direction may have a base material attached and covering it. For example, when the foam 3 is disposed in the space 22b and the foam is exposed, the base material is attached to the impact energy absorber so as to cover a part or the entire exposed surface of the foam. The method of attaching the base material is not particularly limited, and known methods can be applied. It is preferable that the base material and the aluminum extrusion are joined or adhered. As the adhesion method, the base material and the aluminum extrusion may be adhered using a known adhesive, or the aluminum extrusion and the metal base material may be adhered by soldering or heat fusion. For example, when the aluminum extrusion is a long, grooved body or a hat-shaped body (a hat-shaped body with a flange) provided with an edge, a joining means is provided that includes a first hole formed at the edge of the aluminum extrusion where the base material and the grooved aluminum extrusion are overlapped with each other, a second hole formed in the base material, and a through-axis means that penetrates the first hole and the second hole to join the aluminum extrusion and the base material. The through-axis means may be configured, for example, to include a bolt as a shaft member (screw) that penetrates the first hole and the second hole formed in the aluminum extrusion and the base material, and a nut as a fastening member that fixes the bolt to the upper aluminum extrusion and the base material to join the aluminum extrusion and the base material. Alternatively, the through-axis means may use a shaft member such as a rivet that penetrates the first hole and the second hole formed in the aluminum extrusion and the base material to join the aluminum extrusion and the base material. The material, shape, and size of the base material are not particularly limited, and various base materials (wooden base materials, plastic base materials, metal base materials) can be mentioned.

[0061] <Characteristics> The characteristics of the impact energy absorber according to this embodiment will be described.

[0062] (Impact energy absorption amount) The impact energy absorption amount of the impact energy absorber according to this embodiment is preferably 5700 J or more, more preferably 6100 J or more, and even more preferably 6200 J or more. The impact energy absorption amount of the impact energy absorber with respect to the mass of the impact energy absorber according to this embodiment (impact energy absorption amount (J) / mass (Kg)) is preferably 200 to 5000 J / Kg, more preferably 300 to 4800 J / Kg, and even more preferably 500 to 4500 J / Kg. By being within the above range, the impact energy absorber is lightweight while sufficiently absorbing impact energy. The above impact energy absorption amount can be measured by the method described in the examples below.

Examples

[0063] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these examples.

[0064] (Example 1) Using an aluminum material (product name A6061), an aluminum extruded material having the shape shown in Fig. 5(A) with a cross-section of the extruded material continuous in the extrusion direction was produced by extrusion molding. The length in the extrusion direction was set to 1000 mm. The average thickness of the aluminum extruded material was 4.3 mm. The polyphenylene ether foam described below was placed in three cavities of the aluminum extruded material in each of the three spaces shown in Fig. 5(A) so that the occupancy rate was 52.2%. The arrangement shape of the foam is shown in Fig. 6, and the occupancy rate and the arrangement shape are the same throughout the entire length in the extrusion direction.

[0065] As the foam, a polyphenylene ether foam (manufactured by Asahi Kasei Corporation, product name "Sunforce BE") with the expansion ratio described in Table 1 was used.

[0066] (Examples 2 to 6) An impact energy absorber was produced in the same manner as in Example 1, except that the arrangement shape of the foam in each of the three spaces in Fig. 5(A) was as shown in Figs. 7 to 10, and the foam was arranged so that the occupancy rate was the value described in Table 1. In Example 5, the foam was arranged in all three cavities with an occupancy rate of 100%.

[0067] (Example 7) An impact energy absorber was produced in the same manner as in Example 2, except that a polyphenylene ether foam (manufactured by Asahi Kasei Corporation, product name "Sunforce BE") with a foaming ratio of 3.5 cm 3 / g was used.

[0068] (Example 8) An impact energy absorber was produced in the same manner as in Example 4, except that a polyphenylene ether foam (manufactured by Asahi Kasei Corporation, product name "Sunforce BE") with a foaming ratio of 3.5 cm 3 / g was used.

[0069] (Example 9) An impact energy absorber was produced in the same manner as in Example 4, except that a polyphenylene ether foam (manufactured by Asahi Kasei Corporation, product name "Sunforce BE") with a foaming ratio of 7 cm 3 / g was used.

[0070] (Example 10) An impact energy absorber was produced in the same manner as in Example 4, except that a polyphenylene ether foam (manufactured by Asahi Kasei Corporation, product name "Sunforce BE") with a foaming ratio of 10 cm 3 / g was used.

[0071] (Example 11) An impact energy absorber was produced in the same manner as in Example 4, except that a polypropylene foam (manufactured by Kaneka, Epelan PP) with a foaming ratio of 5 cm 3 / g was used.

[0072] (Comparative Example 1) The foam was not placed in the cavity, and only the aluminum extruded material was used.

[0073] [Evaluation] The following measurements were performed on the impact energy absorbers obtained in the examples and comparative examples.

[0074] - Compressive strength of the foam - Foam pieces with a size of 20 mm × 20 mm × 20 mm were cut out. Then, for the cut test pieces, in accordance with JIS K7220 under the conditions of 23°C and 50% RH, using an autograph (AG-5000D) type manufactured by Shimadzu Corporation, the compressive strength (MPa) at 5% compressive displacement was measured.

[0075] - Average cell diameter of the foam - The cross-section of the impact energy absorber was photographed with a scanning electron microscope. For calculating the cell area of the closed cells, it was obtained from the SEM image using image software. The image software used was ImageJ1.48v (freeware Version 1.46, developer Wayne Rasband, July 10, 2014). The areas (S) of 30 closed cells were calculated, and when assuming a circular shape, the diameter d = 2(S / 3.14) 1 / 2 was obtained for each closed cell, and the additive average value was taken as the average cell diameter of the foam.

[0076] - Recovery rate after compression of the foam - From the impact energy absorber obtained in the example, a foam (width 50 mm, height 50 mm, thickness 5 mm) was cut out to obtain a plate-shaped foam. On the plane consisting of the width and height of the plate-shaped foam, a weight of 10 kg was placed, and the thickness after 100 hours at room temperature (thickness under load) was measured. Then, after removing the weight, the thickness after 100 hours at room temperature (thickness after recovery) was measured. And the recovery rate after compression was calculated by the following formula. Recovery rate after compression (%) = Thickness after recovery (mm) / Thickness under load (mm) × 100

[0077] - Closed cell ratio of the foam - From the impact energy absorber obtained in the example, a foam (width 20 mm, height 20 mm, thickness 20 mm) was cut out, and the true volume Vx (cm 3 ) of the foam, the apparent volume Va (cm 3 ) of the foam, the weight W (g) of the foam, and the resin density ρ (g / cm 3 ) of the foam were measured. Then, the closed-cell ratio (%) was calculated from the following formula. Closed-cell ratio (%) = {(Vx - W / ρ) / (Va - W / ρ)} × 100 In the formula, Vx is the true volume (cm 3 ) of the foam, Va is the apparent volume (cm 3 ) of the foam, W is the weight (g) of the foam, and ρ is the density (g / cm 3 ) of the foam. The true volume of the foam was calculated by a pycnometer, and the apparent volume of the foam was calculated by multiplying the width 20 mm, height 20 mm, and thickness 20 mm of the cut-out foam.

[0078] -Average foam particle diameter of the foam- From the impact energy absorber obtained in the example, a foam (width 500 mm, thickness 5 mm) was cut out, and the average foam particle diameter (μm) was measured by the following method. The cross-section in the thickness direction of the foam was observed using the length measurement function of the analysis software attached to the microscope VHX-2000. The area (S) of 30 foam particles was calculated, and the diameter d = 2(S / 3.14) when assuming a circular shape 1 / 2 was obtained for each foam particle, and the additive average value was taken as the average foam particle diameter of the foam.

[0079] -Value of impact energy absorption amount with respect to the mass of the impact energy absorber- Using the impact energy absorber obtained in the examples, the impact energy absorption amount (J) was measured by the method shown in Fig. 5(B). As the measuring instrument, the product name "YU-2000-S" manufactured by JT Toshi Co., Ltd. was used. The impact energy absorber 1 was placed on the hard plate 5, and in the direction in which the three spaces of the impact energy absorber were arranged and perpendicular to the extrusion direction (the direction of the arrow in Fig. 5B), a semi-circular impact member 6 with a diameter of 300 mm was pushed in at a speed of 10 mm / min and collided with the impact energy absorber 1. Then, by measuring the load of the load cell provided on the upper part of the impact member and the displacement of the impact member 6 in the direction in which the three spaces of the impact energy absorber were arranged after the collision (the displacement in the direction of the arrow in Fig. 5B), a stress-strain curve with the displacement (mm) on the horizontal axis and the load (N) on the vertical axis was obtained. The impact energy absorption amount (J) was calculated from the integral value of the stress-strain curve from a displacement of 0 mm to the displacement value at a load of 1000 kN. The impact energy absorption amount was evaluated as follows. ◎(Extremely excellent): 6200 J or more 〇(Excellent): 6100 J or more and less than 6200 J △(Good): 5700 J or more and less than 6100 J ×(Inferior): Less than 5700 J Then, from the following formula, the value of the impact energy absorption amount with respect to the mass of the impact energy absorber was calculated. Value of impact energy absorption amount with respect to the mass of impact energy absorber = Impact energy absorption amount (J) / Mass (kg)

[0080] -Remaining crush- When measuring the above-mentioned impact energy absorption amount, the length of the impact energy absorber crushed in the direction in which the three spaces were arranged when the load value of the load cell exceeded 1000 kN (the difference between the length of 131.02 mm before receiving the impact and the length after receiving the impact) was measured.

[0081]

Table 1

Explanation of symbols

[0082] 1 Impact energy absorber 2 Aluminum extrusion 21 Cross-section of the extrusion 22a Space entirely surrounded by aluminum material 22b Space partially surrounded by aluminum material 23 Aluminum material 24 Cavity 3 Foam 4 Automobile 41 Cross member 42 Center-of-gravity cross member 5 Hard plate 6 Impact member

Claims

1. An extrusion-molded aluminum material and a foam are included, The extrusion-molded aluminum material is made of an aluminum material, and has a shape in which an extrusion-molded material cross-section having a specific shape is continuous in an extrusion direction perpendicular to the extrusion-molded material cross-section, At least one cavity is provided in the extrusion-molded aluminum material, the cavity being a cavity in which a space at least partially surrounded by the aluminum material within the extrusion-molded material cross-section is continuous in the extrusion direction, The foam is present in at least one of the cavities, When the filling rate of the foam ((foaming ratio of the foam - 1) / foaming ratio of the foam) is F, the occupancy rate (%) which is the ratio of the area occupied by the foam to the area of 100% of the cavity area is in the range of 0.6F × 100 to 1.2F × 100, including an extrusion-molded material cross-section including the cavity, An impact energy absorber.

2. Including an extrusion-molded material cross-section including a cavity in which the occupancy rate is in the range of 0.6F × 100 to 1.2F × 100, and an extrusion-molded material cross-section including a cavity in which the occupancy rate is less than 0.6F × 100, The impact energy absorber according to Claim 1.

3. The extrusion-molded material cross-section including a cavity in which the occupancy rate is in the range of 0.6F × 100 to 1.2F × 100 is arranged to cover at least a part of the left-right direction end face of a cross member arranged in the left-right direction perpendicular to the traveling direction of the vehicle and arranged at the position closest to the center of gravity of the vehicle, and is used, The impact energy absorber according to Claim 2.

4. There is a portion where the foam continuously exists over a length of 90% or more with respect to the total length of 100% in the extrusion direction of the extrusion-molded aluminum material, The impact energy absorber according to Claim 1 or 2.

5. The compression strength of the foam is 0.6 MPa or more and 50 MPa or less, The impact energy absorber according to claim 1 or 2.

6. The foam is a bead foam, and the average cell diameter of the foam is 500 μm or less. The impact energy absorber according to claim 1 or 2.

7. The average thickness of the aluminum material of the aluminum extruded material is 0.5 mm or more and 5 mm or less. The impact energy absorber according to claim 1 or 2.

8. The compression recovery rate, which is the ratio of the thickness after 100 hours at room temperature with a 10 kg weight placed on a 5 cm wide, 5 cm high, and 5 mm thick plate-shaped foam of the foam to the thickness after 100 hours at room temperature excluding the weight, is more than 100% and 105% or less. The impact energy absorber according to claim 1 or 2

9. The impact energy absorption amount of the impact energy absorber with respect to the mass of the impact energy absorber is 200 J / Kg or more and 5000 J / Kg or less. The impact energy absorber according to claim 1 or 2.

10. The foam is a bead foam, the foam has closed cells, and the closed cell ratio of the foam is 20 to 99%. The impact energy absorber according to claim 1 or 2.

11. The foam is a bead foam, the foam has closed cells, and the average foam particle diameter of the foam is 0.1 to 3.0 mm. The impact energy absorber according to claim 1 or 2.

Images