Impact-absorbing laminated structure

Abstract

To provide an impact-absorbing laminated structure for absorbing shock received from outside of an article and protecting a part, a member or the like installed inside the article from the shock.SOLUTION: There is provided an impact-absorbing laminated structure, comprising: a first plate member; an impact-absorbing member; and a second plate member, which are laminated in this order, wherein a ratio (t / X) between an average thickness t of the impact-absorbing member, and an average distance X of a portion of a space between the first plate member and the second plate member where the impact-absorbing member is present, is t / X≥0.3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an impact absorbing laminate structure. [Background technology]

[0002] An undercover is attached to the underside of the vehicle body (Patent Documents 1 to 3). In response to the recent trend toward electric vehicles (EVs), a design in which a storage battery such as a lithium-ion secondary battery is mounted on a plate-shaped member attached to the upper side of the undercover is being considered. Patent Document 4 describes a battery pack that can also be used for in-vehicle use.

[0003] On the other hand, while the vehicle is traveling, it is possible that the undercover may be impacted by pebbles or other objects bouncing off the undercover or by contacting the undercover with protrusions in the road surface, and in such cases it was necessary to suppress the impact on the storage battery mounted on the upper side of the undercover via a plate-shaped member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-188569 A [Patent Document 2] JP 2021-133623 A [Patent Document 3] JP 2014-159219 A [Patent Document 4] JP 2021-118051 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide an impact-absorbing laminated structure for absorbing impact received from outside an article and protecting parts or members, etc. installed inside the article from the impact. [Means for solving the problem]

[0006] As a result of intensive research into solving the above-mentioned problems, the inventors have discovered that a laminate structure comprising a first plate member, an impact absorbing material, and a second plate member stacked in this order, in which the ratio of the average thickness of the impact absorbing material when arranged in the impact absorbing laminate structure to the average distance of the portion of the space between the first plate member and the second plate member in which the impact absorbing material is present is a predetermined value or greater, can absorb impacts received from outside the article and protect parts or members installed inside the article from impacts, and have completed the present invention.

[0007] That is, the present invention is as follows. [1] A first plate member; Impact absorbing members, and Second Plate Member A shock absorbing laminated structure comprising the following laminated in this order: The average thickness t of the impact absorbing member; The ratio (t / X) of the average distance X of the portion of the space between the first plate member and the second plate member where the shock absorbing member is present is t / X≧0.3; Shock absorbing laminated structure. [2] The shock absorbing laminated structure according to [1], wherein at least a portion of the surface of the shock absorbing member has an uneven shape. [3] The shock absorbing laminated structure according to [1] or [2], wherein at least a portion of the shock absorbing member is attached to either one or both of the first plate member and the second plate member. [4] The impact absorbing laminate structure according to any one of [1] to [3], wherein the impact absorbing member has a compressive modulus of elasticity of 30 MPa or more and a 50% compressive stress of 1 MPa or more and 10 MPa or less. [5] The impact absorbing laminated structure according to any one of [1] to [4], wherein the temperature-dependent change rate (P(60°C) / P(-40°C)) of the compressive elastic modulus P of the impact absorbing member from -40°C to 60°C is 0.5 or more. [6] The impact absorbing laminate structure according to any one of [1] to [5], wherein the impact absorbing member includes a bead foam molding. [7] The first plate member is a panel attached to a lower portion of an automobile, The second plate member is a base plate of a battery mounted in a vehicle or a plate member for a vehicle attached to the base plate, The shock-absorbing laminated structure is used to protect a battery mounted in a vehicle from shock. The impact absorbing laminated structure according to any one of [1] to [6]. Effect of the Invention

[0008] According to the present invention, it is possible to provide an impact absorbing laminated structure for absorbing an impact from the outside of an article and protecting parts or members installed inside the article from the impact, and it can be particularly suitably used as an undercover that is attached to the bottom of an automobile and protects a battery loaded in the automobile from impact. Furthermore, in the case of impact absorption using only the first plate member, it is necessary to increase the thickness of the first plate, which increases the weight, and when the first plate comes into contact with the second plate due to deformation caused by the load, the load rises suddenly, leading to damage to the second plate. If an impact absorbing member is disposed between the first plate member and the second plate member with an appropriate thickness, it is also possible to shorten the distance between the first plate and the second plate, and it is possible to absorb the same amount of energy in a smaller space than in the conventional design. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing an example of the impact absorbing laminated structure of the present invention. [Diagram 2]1 is a schematic diagram showing an example of the impact absorbing laminated structure of the present invention. [Diagram 3] 1 is a schematic diagram showing an example of the impact absorbing laminated structure of the present invention. [Figure 4] 1 is a schematic diagram showing an example of the impact absorbing laminated structure of the present invention. [Diagram 5] FIG. 2 is a schematic diagram (a: top view, b: side view) showing an evaluation method in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (shock absorbing laminated structure) The shock absorbing laminated structure (1) of the present invention includes a first plate member (2), a shock absorbing member (3), and a second plate member (4) laminated in this order, wherein the ratio (t / X) of the average thickness t of the shock absorbing member (3) to the average distance X of the portion of the space between the first plate member (2) and the second plate member (4) where the shock absorbing member (3) is present is t / X≧0.3. Some examples of the shock absorbing laminated structure (1) of the present invention are shown in Figures 1 to 4.

[0011] <First and second plate members> In the shock absorbing laminated structure (1) of the present invention, the first plate member (2) and the second plate member (4) are plate-like members arranged on parallel planes, and form the exterior of the shock absorbing laminated structure (1). The terms "first plate member" and "second plate member" are merely convenient names for distinguishing between the two plate members included in the shock absorbing laminated structure (1). In particular, the "first plate member" may refer to the plate member on the side that may receive a shock (e.g., a panel attached to the lower part of an automobile), and the "second plate member" may refer to the plate member on the side where a part or member to be protected from a shock (e.g., a battery (11) mounted on an automobile) may be installed (e.g., a base plate or plate member).

[0012] <<Plate member shape, dimensions and arrangement>> The first plate member (2) and the second plate member (4) (hereinafter collectively referred to as "plate members") have a plate-like shape. The plate members may have holes. The plate members may have projections and recesses. The first plate member (2) and the second plate member (4) may have portions that come into contact with each other and are joined together (e.g., bolt fixing portions (5, 6) etc.). The thickness of the plate members is not particularly limited, but from the viewpoint of strength and rigidity, it is preferably 1.0 mm or more, and more preferably 1.5 mm or more, for example, and from the viewpoint of weight reduction, it is preferably 3.0 mm or less, and more preferably 2.5 mm or less.

[0013] The average distance X of the portion of the space between the first plate member (2) and the second plate member (4) where the shock absorbing member (3) is present is not particularly limited, but from the viewpoint of load distribution and energy absorption (EA), it is preferably 3 mm or more, and more preferably 5 mm or more, and from the viewpoint of space and weight reduction, it is preferably 30 mm or less, and more preferably 25 mm or less.

[0014] <<Plate material>> The plate member is preferably made of a rigid material, more preferably a rigid metal or a rigid resin. The rigid metal is not particularly limited, but may be, for example, a material containing aluminum, stainless steel, iron, copper, etc. The rigid resin may be, for example, a reinforced fiber material using carbon fiber or glass fiber.

[0015] <<Physical properties of plate components>> The flexural modulus of the plate member is not particularly limited, but is preferably 30 GPa or more, more preferably 50 GPa or more, and is preferably 500 GPa or less, and more preferably 400 GPa or less. The surface density of the plate member is not particularly limited, but is, for example, 1.0 kg / m 2 More than 1.5kg / m is preferable. 2 More preferably, 15.0 kg / m 2 Less than 10.0 kg / m is preferable. 2 The following is more preferred:

[0016] <Shock absorbing materials> The shock absorbing member (3) used in the shock absorbing laminated structure (1) of the present invention is located between the first plate member (2) and the second plate member (4) and has the role of protecting parts or members attached to the second plate member (4) from shock by absorbing the shock received from the first plate member (2) and dispersing the shock load to the second plate member (4).

[0017] <<Shape, dimensions and arrangement of impact absorbing components>> The shock absorbing member 3 has a plate-like shape. The shock absorbing member 3 may have a concave shape and / or a convex shape, for example, at least a part of the surface of the shock absorbing member 3 may have a concave shape.

[0018] The shock absorbing member (3) may have a uniform thickness (e.g., Figs. 1 and 2) or may have a different thickness (e.g., Figs. 3 and 4). Examples of shapes with different thickness include a shape with a stepwise difference in thickness (e.g., Fig. 3) and a shape with a gradient in thickness (e.g., Fig. 4). When the shock absorbing laminated structure (1) has joints (e.g., bolt fixing parts (5 and 6), etc.) between the first plate member (2) and the second plate member (4) at both ends, the shock absorbing capacity decreases as it moves away from the joints and closer to the center, so it is preferable that the shock absorbing member (3) has a shape with an increased thickness closer to the center (e.g., Figs. 3 and 4). In addition, when the first plate or the second plate has an uneven structure, the amount of compressive deformation of the shock absorbing member (3) changes, so it is preferable to make the shape take into account the compressive deformation (e.g., when the plate is convex, the shock absorbing member (3) is made concave to suppress partial concentration of stress).

[0019] The shock absorbing member (3) may be bonded to the first plate member (2) or the second plate member (4), or may not be bonded to either the first plate member (2) or the second plate member (4). When the shock absorbing laminated structure (1) is subjected to an impact, the shock absorbing member (3) may fall off or break, or the first plate member (2) may be deformed or break, and the first plate member (2) may need to be replaced, whereas the second plate member (4) may not be damaged by the impact, and replacement of the second plate member (4) may not be necessary. Therefore, in such a case, when replacing the first plate member (2) or the shock absorbing member (3), it is preferable that the shock absorbing member (3) is not joined to the second plate member (4) but is joined to the first plate member (2) so that it is possible to deal with the problem by removing and replacing only the first plate member (2) and the shock absorbing member (3) rather than repairing and replacing the first plate member (2) and the shock absorbing member (3) together with the second plate member (4).

[0020] The ratio (t / X) of the average thickness t of the shock absorbing member (3) to the average distance X of the portion of the space between the first plate member (2) and the second plate member (4) where the shock absorbing member (3) is present is t / X≧0.3, preferably t / X≧0.4, and more preferably t / X≧0.5. The upper limit of the t / X ratio is t / X≦1. The above range of the t / X ratio is sufficient if it is satisfied at one cross section of the shock absorbing laminated structure (1), and it is preferable that the above range is satisfied at any number of cross sections of the shock absorbing laminated structure (1). By having the t / X ratio in the above range, the shock absorbing member (3) can absorb the shock received by the first plate member (2) and protect parts or members attached to the second plate member (4) from the shock.

[0021] The average thickness t of the impact absorbing member (3) is not particularly limited, but for example, it is preferable that the impact absorbing member (3) has a sufficient thickness to be able to absorb the impact received by the first plate member (2) and protect the parts or members attached to the second plate member (4) from the impact, and from the viewpoint of ensuring such a thickness, it is preferably 3 mm or more, and more preferably 5 mm or more, and from the viewpoint of reducing the space occupied by the impact absorbing member (3) and the weight of the impact absorbing member (3), it is preferably 30 mm or less, and more preferably 25 mm or less. <<Various physical properties of impact absorbing materials>>

[0022] From the viewpoint of improving the impact absorption efficiency, the impact absorbing member (3) has a compressive elastic modulus of preferably 30 MPa or more, more preferably 40 MPa or more, and preferably 300 MPa or less, and more preferably 200 MPa or less. From the viewpoint of improving the impact absorption efficiency, the impact absorbing member (3) has a 50% compressive stress of preferably 1 MPa or more, and preferably 3 MPa or more, and from the viewpoint of protecting the second plate, it is preferably 10 MPa or less, and preferably 8 MPa or less.

[0023] The temperature-dependent change rate (P(60°C) / P(-40°C)) of the compressive elastic modulus P of the shock absorbing member (3) from -40°C to 60°C is preferably 0.5 or more, more preferably 0.6 or more, and preferably 1.0 or less, and more preferably 0.95 or less, from the viewpoint of improving shock absorbing efficiency. The closer the ratio of the compressive elastic modulus at high temperature to the compressive elastic modulus at low temperature is to 1, the more the unevenness of the energy absorption efficiency due to temperature change can be reduced.

[0024] <<Shock absorbing material>> The material of the shock absorbing part is usually an elastic material, and is preferably an elastic material having the above-mentioned physical properties. The material of the shock absorbing part preferably includes a bead foam. The bead foam may be made of resin. The resin used as the raw material of the bead foam is preferably a thermoplastic resin. Examples of the thermoplastic resin include modified polyphenylene ether (m-PPE), polyamide, polypropylene, polystyrene, high impact polystyrene, ABS resin, polyethylene (high density, low density), polymethyl methacrylate, polyvinylidene chloride copolymer resin, polyethylene terephthalate, polycarbonate, and mixtures thereof.

[0025] (Use of impact absorbing laminated structures) The shock absorbing laminate structure (1) of the present invention is, for example, a member for absorbing a shock received from the outside of an article and protecting a part or member installed inside the article from the shock. The shock absorbing laminate structure (1) of the present invention is particularly suitable for use as an undercover that is attached to the lower part of an automobile to protect a battery (11) installed in the automobile from shock.

[0026] When used as an undercover for protecting a battery (11) mounted on an automobile from impact, the impact absorbing laminated structure (1) of the present invention can be configured so that the first plate member (2) is used as a panel attached to the lower part of the automobile, and the second plate member (4) is used as a base plate for the battery (11) mounted on the automobile or an automobile plate member attached to the base plate. EXAMPLES

[0027] The present invention will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples. The measurement and evaluation methods applied in the examples and comparative examples are shown below.

[0028] *1 The resin types are as follows: PPE-based: Asahi Kasei Corporation's "Sunforce (registered trademark) BE", PE-based: Asahi Kasei Corporation's "Mef (registered trademark)", PP-based: JSP Corporation's "Miradren (registered trademark)", PUR-based: Inoac Corporation's "Calmflex (registered trademark) F140" The PPE-based and PE-based beads were molded to have the densities shown in Tables 1 and 2, and foamed molded articles of the specified sizes were produced.

[0029] *2, *3 Thickness (mm), density (g / cm 3 ), areal density (kg / m 2 ) was calculated as follows: After measuring the mass W (g) of the shock absorbing material, the area S (m 2 ), volume V(cm 3 ) and W / S (kg / m 2 ) is the surface density of the impact absorbing material, and W / V (g / cm 3 ) was defined as the density of the impact absorbing material.

[0030] *4 The closed cell ratio of the impact absorbing material was measured by cutting out a rectangular parallelepiped sample of impact absorbing material measuring 20 mm in length, 20 mm in width, and the thickness (mm) shown in Table 1 from the impact absorbing material. S(%)={(Vx-W / ρ) / (Va-W / ρ)}×100 ···(1) In formula (1), Vx is the true volume of the foam (cm 3 ) and Va is the apparent volume of the foam (cm 3 ), W is the weight of the foam (g), and ρ is the density of the base resin of the foam (g / cm 3 The true volume of the foam is calculated using a pycnometer.

[0031] *5 The compressive modulus and 50% compressive stress of the impact absorbing material were measured in accordance with JIS K 7220 (2006). The compressive modulus at the specified temperature was measured by storing the material at the specified temperature for more than 3 hours and then measuring it under the specified temperature conditions in the same manner as at room temperature.

[0032] *6 The surface density of the composite is calculated by measuring the mass W (g) and then measuring the area S (m 2 ) and W / S (kg / m 2 ) was defined as the areal density of the composite.

[0033] *7 The distance between the first and second plates was designed using the specified value for the jig distance shown in Figure 5.

[0034] *8 t / X is calculated by measuring the thickness t of the impact absorbing material with a vernier caliper and dividing it by the distance between the plates X.

[0035] <Evaluation of load, energy absorption (EA), and displacement> As shown in Fig. 5, a base plate (corresponding to the second plate member (4)) was used as a foundation, and an impact absorbing material was placed on the base plate. A panel (corresponding to the first plate member (2)) was placed over the impact absorbing material and fixed to the base plate to create a test sample (21). A load was applied from above the panel of the test sample (21) using a measuring tool (indenter) (31) of a measuring device, and each evaluation value was measured. A UH-500kNIR manufactured by Shimadzu Corporation was used.

[0036] The EA at 50% displacement per weight was calculated by calculating the obtained EA at 50% displacement from the area of ​​the load-displacement curve and dividing the calculated value by the areal density of the composite.

[0037] (Examples 1 to 15, Comparative Examples 1 to 5) Test samples were prepared using the impact absorbing material and panel (corresponding to the first plate member) shown in Table 1, and each evaluation value was measured. The results are shown in Table 1.

[0038] [Table 1-1]

[0039] [Table 1-2] [Industrial Applicability]

[0040] According to the present invention, it is possible to provide an impact absorbing laminated structure for absorbing an impact received from the outside of an article and protecting parts or members etc. installed inside the article from the impact, and in particular, it can be suitably used as an undercover attached to the bottom of an automobile for protecting a battery loaded in the automobile from impact. [Explanation of symbols]

[0041] 1. Impact absorbing laminated structure 2. First plate member 3. Shock absorbing materials 4 Second plate member 5 Bolt fixing portion (in the first plate member) 6 Bolt fixing part (in the second plate member) 11. Battery 12 Volts 13 Bolt fixing member 21 Test Samples 31 Measuring tool (indenter)

Claims

1. A first plate member; Impact absorbing members, and Second Plate Member A shock absorbing laminated structure comprising the following laminated in this order: The average thickness t of the impact absorbing member; The ratio (t / X) of the average distance X of the portion of the space between the first plate member and the second plate member where the shock absorbing member is present is t / X≧0.3; Shock absorbing laminated structure.

2. The shock absorbing laminated structure according to claim 1 , wherein at least a part of the surface of the shock absorbing member has an uneven shape.

3. 2. The impact absorbing laminate structure according to claim 1, wherein at least a portion of the impact absorbing member is attached to either one or both of the first plate member and the second plate member.

4. 2. The impact absorbing laminate structure according to claim 1, wherein the impact absorbing member has a compressive elastic modulus of 30 MPa or more and a 50% compressive stress of 1 MPa or more and 10 MPa or less.

5. 2. The impact absorbing laminated structure according to claim 1, wherein the impact absorbing member has a compressive elastic modulus P whose temperature dependence change rate from -40°C to 60°C (P(60°C) / P(-40°C)) is 0.5 or more.

6. The impact absorbing laminate structure of claim 1 , wherein the impact absorbing member comprises a bead foam molding.

7. The first plate member is a panel attached to a lower portion of an automobile, The second plate member is a base plate of a battery mounted in a vehicle or a plate member for a vehicle attached to the base plate, The shock-absorbing laminated structure is used to protect a battery mounted in a vehicle from shock. The impact absorbing laminated structure according to any one of claims 1 to 6.

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