cushioning material

Abstract

The present invention provides a cushioning material that maintains high surface pressure over a wide range of displacements, exhibits sufficiently high shock absorption or cushioning properties, and is also less prone to compression set. [Solution] The device comprises an elastic body made of elastomer A with a V-shaped or wavy cross-section, and a leaf spring core material enclosed along the shape of the elastic body, wherein the bending direction during compression is controlled in the leaf spring core material. A cushioning material wherein the coefficient of friction of the elastic body is 0.3 or greater, and / or an adhesive layer is provided on the contact surface of the contact portion of the elastic body.

Description

Technical Field

[0001] The present invention relates to a buffer material.

Background Art

[0002] As buffer materials that absorb external impacts and pressures, buffer materials with various structures and characteristics have been developed so far, and they are widely used for applications such as vibration absorption in buildings and vehicles, and expansion absorption of battery cells. For example, in Patent Document 1, as an impact-absorbing material used for guardrails on roads and housing building materials, etc., there is provided a buffer material comprising a foamed resin body as a base material, a reinforcing fiber layer composed of reinforcing fibers covering the surface of the foamed resin body, and a coating layer composed of a room-temperature curable resin impregnated with the reinforcing fibers, and the foamed resin body, the reinforcing fiber layer, and the coating layer are integrated. Further, in Patent Document 2, there is disclosed an invention of a buffer material for a battery having a configuration in which a plurality of contact portions and a plurality of support portions are alternately connected to form an M-shaped continuous structure. In the buffer material for the battery, two adjacent support portions among the plurality of support portions form a hollow space between the two support portions in a state before receiving a compressive force, and the two support portions are deformed in such a manner that the bent portions of the two support portions bent in an S shape under the compressive force are accommodated in the hollow space, whereby the hollow space is crushed and the thickness of the buffer material for the battery is reduced.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, the shock absorbers and battery cushioning materials described in the above patent documents are all made of rubber or resin. When such cushioning materials are compressed with strong force, the surface pressure (reaction force) is insufficient, and their absorption performance (cushioning performance) against strong impacts is poor. Furthermore, the battery cushioning material described in Patent Document 2 has a structure in which the support parts of the cushioning material can bend in an S-shape when compressed, but if each support part is compressed without exhibiting the same S-shaped curvature, there is a risk that the cushioning performance will decrease, and if it continues to be subjected to strong compression while in this S-shaped curvature state, deformation (compression set) is likely to occur. Once deformation occurs, not only does the surface pressure decrease, but there is also the problem that it cannot fully recover to its pre-compression shape even after being released from the compressive force (a problem in which the absorption performance is significantly reduced against repeated compressive forces). In addition, because the battery cushioning material described in Patent Document 2 has a U-shaped recess on the opposing surface of the contact part, the contact area with the rigid body (compression surface) becomes small when no compressive force is applied. Therefore, for example, if a compressive force is applied to a rigid body from an oblique direction, the compressive force on one side of the cushioning material becomes stronger, causing the contact area to slide in the direction of less compressive force, which may prevent it from properly performing its absorption (cushioning) function.

[0005] The present invention aims to provide a cushioning material that maintains a moderately high surface pressure over a wide range of displacements, exhibits sufficiently high shock absorption or cushioning properties, and is also less prone to compression set. [Means for solving the problem]

[0006] In view of the above problems, the inventors of this invention conducted extensive research and, as a result, designed a cushioning material in which a bent portion is provided in a leaf spring core material, and the outer circumference of the leaf spring core material is covered with an elastic body made of elastomer. They found that by controlling the coefficient of friction of the elastic body to a specific high range, or by providing an adhesive layer on the contact surface of the contact portion of the elastic body, it is possible to maintain a moderately high surface pressure over a wide range of displacements, resulting in a cushioning material that exhibits sufficiently high shock absorption or cushioning properties while also being less susceptible to compression set. The present invention was completed based on these findings.

[0007] In other words, the above problem was solved by the following means. [1] The device comprises an elastic body made of elastomer A with a V-shaped or wavy cross-section, and a leaf spring core material enclosed along the shape of the elastic body, wherein the bending direction of the support column portion during compression is controlled in the leaf spring core material. A cushioning material wherein the coefficient of friction of the elastic body is 0.3 or greater, and / or an adhesive layer is provided on the contact surface of the contact portion of the elastic body. [2] The cushioning material according to [1], wherein the constituent material of the leaf spring core is metal or elastomer B. [3] The cushioning material according to [2] above, wherein the metal is selected from carbon steel, phosphor bronze, copper, titanium alloy, nickel alloy, steel, and stainless steel. [4] The cushioning material according to any one of [1] to [3], wherein the width of the support portion is 0.5 times or less the height of the contact portion. [5] A cushioning material according to any one of [1] to [4], having a flat plate material that contacts the contact portion. [6] A composite cushioning material comprising stacking two or more cushioning materials described in any one of the above [1] to [5] in the height direction of the cushioning material. [Effects of the Invention]

[0008] The cushioning material of the present invention maintains a moderately high surface pressure over a wide range of displacements, exhibiting sufficiently high shock absorption or cushioning properties, while also being less prone to compression set. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1(a) is a schematic diagram showing a longitudinal cross-sectional view of one embodiment of the cushioning material of the present invention. Figure 1(b) is a schematic diagram showing a longitudinal cross-sectional view of another embodiment of the cushioning material of the present invention. [Figure 2]Figure 2(a) is a schematic diagram showing a longitudinal cross-sectional view of a cushioning material comprising another embodiment of the cushioning material of the present invention, wherein the structure shown in Figure 1(a) is connected in parallel. Figure 2(b) is a schematic diagram showing a longitudinal cross-sectional view of a cushioning material comprising yet another embodiment of the cushioning material of the present invention, wherein the structure shown in Figure 1(b) is connected in parallel. [Figure 3] Figure 3 is a perspective view of the cushioning material of the present invention shown in Figure 2(a) from an oblique upward direction. [Figure 4] Figure 4(a) is a graph showing the relationship between the displacement of the cushioning material and the surface pressure when one embodiment of the cushioning material of the present invention is compressed. Figure 4(b) is a schematic longitudinal cross-sectional view showing the compression of the cushioning material at each stage in Figure 4(a). [Figure 5] Figure 5 is a longitudinal cross-sectional view showing one embodiment of the composite cushioning material of the present invention. [Figure 6] Figure 6 is a graph showing the relationship between surface pressure and displacement for each cushioning material in Examples 1 and 2 and Comparative Examples 1 and 2. [Figure 7] Figure 7 is a graph showing the relationship between surface pressure and displacement for each cushioning material in Examples 1, 3, and 4, and Comparative Example 4. [Figure 8] Figure 8 is a graph showing the relationship between surface pressure and displacement for each cushioning material in Examples 5 and 6. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described with reference to the drawings as appropriate. However, the embodiments described below represent preferred embodiments of the present invention, and the present invention is not limited to those described below other than those specified herein.

[0011] [Cushioning material] The buffer material of the present invention includes an elastic body made of an elastomer A having a V-shaped or wave-shaped cross-sectional shape, and a leaf spring core material enclosed along (following) the shape of the elasticity body. In the leaf spring core material, the bending direction of the support column portion during compression is controlled. The elastomer has a friction coefficient of 0.3 or more, and / or an adhesive layer is provided on the contact surface of the contact portion of the elastomer. In the present invention or this specification, the term "V-shaped" includes not only a V-shape but also a substantially V-shape. That is, the "V-shaped" may be a V-shape itself, or a shape close to a V-shape (substantially V-shape, for example, among the contact portions of the elastomer, the shape of the edge (rising portion) of the portion facing the compression surface is angular (linear) or curved (curved outward without an angle), U-shaped, etc.) within a range not impairing the effects of the present invention. Also, in the present invention or this specification, the term "wave-shaped" means an N-shaped (a shape like a V-shaped elastomer and a V-shaped elastomer with the top and bottom reversed partially overlapped), or a shape in which two or more V-shaped structures are connected in the lateral direction. Note that if the cross-sectional shape of the elastomer is V-shaped or wave-shaped, the cross-sectional shape of the buffer material of the present invention is also V-shaped or wave-shaped. Also, in the present invention or this specification, the shape of the "leaf spring core material enclosed along (following) the shape of the elastomer" means a shape passing through the axial portion (or its vicinity) of the shape of the elastomer in a plan view of a longitudinal sectional view.

[0012] In the buffer material of the present invention, by controlling the bending direction (bending state) of the support column portion during compression to be uniform, the impact absorption performance or buffering performance of the buffer material can be improved, and furthermore, a buffer material with less occurrence of compression set can be obtained. Also, by setting the friction coefficient of the elastomer to 0.3 or more, and / or providing an adhesive layer on the contact surface of the contact portion of the elastomer, the contact surface of the contact portion can firmly hold the compression surface during compression, suppressing the sliding of the contact portion (the contact portion sliding in the lateral direction under the compression force), and further improving the impact absorption performance or buffering performance of the buffer material.

[0013] Figure 1 schematically shows the longitudinal cross-sectional views of a preferred embodiment of the cushioning material of the present invention (Figure 1(a), cushioning material 100A) and another preferred embodiment (Figure 1(b), cushioning material 100B). Note that each embodiment shown in Figure 1 shows the state before pressure is applied from the vertical direction. Figure 1(a) shows a longitudinal cross-sectional view of one embodiment of the cushioning material of the present invention (cushioning material 100A), in which the cross-sectional shape of the elastic body 110 is V-shaped, and a V-shaped structure is shown in which a leaf spring core material 120 is enclosed along the shape of the elastic body 110 (in other words, the V-shaped structure is a structure in which the outer circumference of the leaf spring core material 120 is covered with the elastic body 110). The elastic body 110 has contact portions 111 that abut against the upper and lower compression surfaces 300, and support portions 112 that connect the contact portions 111. In the cushioning material 100A of the present invention, the edge shape of the portion of the contact portion 111 that faces the compression surface is square (straight), and it is in contact with the compression surface by the contact surface 113. The leaf spring core material 120 is provided with a curved portion 121 that is curved according to the V-angle θ, and a bent portion 122 at a position that guides the bending of the support portion during compression. The cushioning material 100A of the present invention has a cross-sectional shape that extends in the depth direction, as shown in Figure 1(a). The same applies to other embodiments described later. Figure 1(b) shows a longitudinal cross-sectional view of another embodiment (100B) of the cushioning material of the present invention, which, like the cushioning material 100A shown in Figure 1(a), shows a V-shaped structure in which the cross-sectional shape of the elastic body 110 is V-shaped (approximately V-shaped), and the leaf spring core material 120 is enclosed along the shape of the elastic body 110. Furthermore, the leaf spring core material 120 has a bent portion 122 at a position that guides the bending of the support portion when the cushioning material 100B of the present invention is compressed. As shown in Figure 1(b), the contact portion 111 of the cushioning material 100B of the present invention has a curved shape where the edge of the portion facing the compression surface does not have corners and is curved outward.

[0014] Furthermore, Figure 2 shows the cross-sectional shapes of the cushioning material of the present invention having a shape (wave-like) in which two or more V-shaped structures shown in Figure 1(a) are connected horizontally (Figure 2(a), cushioning material 100C), and the cushioning material of the present invention having a shape (wave-like) in which two or more V-shaped structures shown in Figure 1(b) are connected horizontally (Figure 2(b), cushioning material 100D). The cushioning materials shown in Figures 2(a) and 2(b) have flat plate members 130 (rigid bodies) above and below the V-shaped structure. Figure 3 shows a schematic diagram of the cushioning material 100C of the present invention shown in Figure 2(a) when viewed from an oblique upward direction (however, the upper flat plate member 130 is shown as semi-transparent).

[0015] In the case where the cushioning material of the present invention is a corrugated shape in which two or more V-shaped structures are connected in the lateral direction, the number of connections of the V-shaped structures in the lateral direction is not particularly limited and can be appropriately determined according to the dimensions of the cushioning material and the scope to which it is applied. For example, the number of connections may be two or more, ten or more, or 100 or more. The dimensions of the cushioning material of the present invention are not particularly limited and can be set appropriately according to the purpose, as long as they do not hinder the effects of the present invention. For example, the length (length in the vertical direction of the V-shaped structure) can be 4 to 1000 mm, the width (length in the horizontal direction of the V-shaped structure) can be 10 to 3000 mm, and the depth can be 10 to 3000 mm. In the case where the cushioning material of the present invention is corrugated in which two or more V-shaped structures are connected in the horizontal direction, the preferred horizontal length of the entire cushioning material is determined by the preferred horizontal length of the V-shaped structure and the preferred number of V-shaped structures connected in the horizontal direction.

[0016] Figure 4(a) is a graph showing the relationship between the displacement of the cushioning material and the surface pressure (reaction force on the compression surface) when the cushioning material is compressed vertically, in one example of an embodiment of the cushioning material of the present invention. As shown in Figure 4(a), the surface pressure increases as the displacement of the cushioning material (compressed distance) increases, and the increase in surface pressure becomes gradual within a certain range of displacement. After that, once the displacement exceeds a certain value, the surface pressure rises sharply again. Figures (A) to (C) in Figure 4(b) are schematic diagrams showing the compression process in stages (A) to (C) shown in Figure 4(a) when the cushioning material of the present invention (one embodiment shown in Figure 1(a)) is compressed from the vertical direction. In the state of stage (A) in Figure 4(b), the support column in the cushioning material of the present invention is not bent, and the surface pressure increases according to the amount of displacement. In this state, a sufficient space S is secured between the compression surface and the cushioning material of the present invention. Next, in the state of stage (B) in Figure 4(b), the support column bends due to compression, becoming a curved S-shape and folding into the space S. In the cushioning material of the present invention, the leaf spring core material has a bent portion, so the bending direction of the support column in the state of stage (B) in Figure 4(b) is controlled, and bending occurs at a position where it can be efficiently stored in the space S. In this state, even if the amount of displacement increases, the increase in surface pressure is gradual, and a sudden increase in surface pressure (reaction force) in response to the compression of the cushioning material can be prevented. In the state of stage (C) in Figure 4(b), further compression occurs and the folded support column comes into contact with the compression surface, causing the surface pressure to rise sharply again in proportion to the amount of displacement. In cushioning materials where the bending portion is not controlled (i.e., cushioning materials where the leaf spring core does not have a bending portion), variations occur in the bending position of each support column. As a result, an efficient folding structure in which each support column is controlled within space S is not achieved in the state of stage (B) in Figure 4(b), and it becomes easier to transition to a state in which space S cannot be sufficiently secured, as in the state of stage (C) in Figure 4(b), where the support columns are in contact with the compression surface. Therefore, the range in which the increase in surface pressure is gradual becomes shorter, and a rapid increase in surface pressure in response to the compression of the cushioning material is likely to occur. Furthermore, in the state of stage (C), the support columns are in contact with the compression surface, and in particular, the support columns are folded in a state different from the position in which they should bend. If this state continues for a long period of time, compression set occurs, causing a significant decrease in shock absorption or cushioning performance. Thus, by controlling the bending position of the support columns during compression, it is possible to stabilize the shock absorption or cushioning performance during compression and suppress the occurrence of compression set.

[0017] The cushioning material of the present invention can be used for applications that absorb shock and pressure. For example, it is preferable to use it in buildings and other structures, vehicles such as automobiles and railway cars, and secondary batteries. For example, when the cushioning material of the present invention is applied to a secondary battery, by placing it between battery cells or between battery cells and restraining members, it can absorb the pressure caused by the expansion and contraction of the battery cells.

[0018] The preferred forms of each component of the cushioning material of the present invention will be described below.

[0019] (Elastic body) In the cushioning material of the present invention, the elastic body is an elastomer A having a V-shaped or wavy cross-section. Examples of elastomer A include thermosetting elastomers (rubber) and thermoplastic elastomers. Examples of thermosetting elastomers include natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, ethylene propylene diene rubber, silicone rubber, and urethane rubber. Examples of thermoplastic elastomers include olefin-based elastomers, styrene-based elastomers, and ester-based elastomers. These elastomers are more preferably foamed, having pores inside the elastomer. Having a foamed structure can further improve the shock absorption performance or cushioning performance of the cushioning material of the present invention. The hardness of the elastic material is preferably 50 to 95, and more preferably 65 to 90. By setting the hardness of the elastic material within the above preferred range, the cushioning performance of the cushioning material of the present invention can be further improved. The hardness can be measured, for example, according to JIS K 6253-3:2023. In this invention and specification, in order to distinguish between the elastomer that is a constituent material of an elastic body and the elastomer that is a constituent material of a leaf spring core material described later, the former is referred to as "elastomer A" and the latter as "elastomer B".

[0020] -Contact part- In the elastic body, the contact portion is a structural part having a contact surface that contacts the upper and lower compression surfaces. The shape of the contact portion is not particularly limited, and it is sufficient if it is designed to contact the compression surfaces. The length of the contact surface (in one embodiment of the cushioning material of the present invention shown in Figure 1(a), etc., the length in the lateral direction that contacts the compression surface) is preferably 0.2 to 10 mm, and more preferably 0.4 to 8 mm, from the viewpoint of suppressing slippage of the contact portion during compression. Furthermore, the shape of the contact surface is preferably flat. "Height of the contact portion" refers to the vertical distance (t) of the contact portion at the lateral center position of the contact portion (the vertical length of the valley formed by the two adjacent support portions) at the contact portion connected to two adjacent support portions (the contact portion sandwiched between the two support portions). The height of the contact portion is not particularly limited and can be set appropriately within a range that does not impair the effects of the present invention, depending on the dimensions of the cushioning material of the present invention, the compressive strength, or the application. For example, the height of the contact portion can be set to 0.2 to 500 mm.

[0021] In the cushioning material of the present invention, the coefficient of friction (static friction coefficient μ) of the elastic body is 0.3 or higher, or / or an adhesive layer is provided on the contact surface of the contact portion of the elastic body. In other words, in either case, the slippage of the contact portion is suppressed during compression. If the coefficient of friction is extremely low, slippage occurs at the contact points during compression, causing the V-shape to remain open and crushed. As a result, the V-shaped structure cannot properly absorb the compressive force and cannot maintain high surface pressure. In the cushioning material of the present invention, by setting the coefficient of friction to 0.3 or higher, the opening of the V-shaped structure due to slippage at the contact points during compression can be suppressed, increasing the surface pressure and maintaining excellent shock absorption or cushioning performance. From the viewpoint of further suppressing slippage at the contact points and improving the cushioning effect, the coefficient of friction is preferably 0.3 or higher, and more preferably 0.7 or higher. The coefficient of friction can be measured in accordance with JIS K 7125:1999.

[0022] Furthermore, by providing an adhesive layer on the contact surface of the elastic body's contact portion and bonding the contact surface of the contact portion to the compression surface via the adhesive layer, the opening of the V-shape caused by slippage of the contact portion during compression can be suppressed in the same manner as described above. There are no particular restrictions on such an adhesive layer as long as it can bond the contact surface of the contact portion to the compression surface. Examples of components included in the adhesive layer include components used in bonding methods such as vulcanization bonding and solvent bonding (e.g., epoxy-based, silicone-based, chloroprene rubber-based, etc.).

[0023] -Strut part- In an elastic body, the support portion is a structural part that connects the upper and lower contact portions. That is, for example, if the cross-sectional shape of the cushioning material of the present invention is V-shaped, the cushioning material of the present invention has two adjacent support portions. It is preferable that the support portions are linear in shape before compression. "Width of the support column" refers to the length (w) of the support column in a direction perpendicular to the straight line at a straight section of the support column (for example, at the midpoint of the support column). The width of the support column is not particularly limited and can be set appropriately according to the dimensions of the cushioning material of the present invention, compressive strength, etc., or application. For example, the width of the support column can be 0.1 to 250 mm. In the relationship between the height (t) of the contact portion and the width (w) of the support portion, by making the width (w) of the support portion smaller than the height (t) of the contact portion, the support portion becomes easier to bend during compression, and the elastic bodies are less likely to come into contact with each other, thereby improving the tolerance of displacement due to compression. Specifically, the width (w) of the support portion (w / t) relative to the height (t) of the contact portion can be 1.0 times or less, preferably 0.5 times or less, more preferably 0.4 times or less, and even more preferably 0.3 times or less. Furthermore, it is preferable that the width (w) of the support portion (w) relative to the height (t) of the contact portion is 0.1 times or more.

[0024] The inner angle (V-shape angle) formed on the extension of the straight portion of adjacent support columns is preferably 55 to 75 degrees. By setting it within this range, the V-shape structure can effectively absorb the compressive force during compression and maintain a reaction force against the compressive force (pressure). It can also promote restoration / recovery after the compressive force is released.

[0025] (Leaf spring core material) In the cushioning material of the present invention, the leaf spring core material has spring properties (it deforms when a compressive force is applied and returns to its original shape when the compressive force is removed). The constituent material of the leaf spring core material can preferably be one that has been conventionally used as a spring material, and preferably a metal or elastomer B. The metal can be any metal commonly used for spring materials, more specifically, carbon steel, phosphor bronze, copper, titanium alloy, nickel alloy, steel, stainless steel, etc. Elastomer B can be the thermoplastic elastomer mentioned above in elastomer A. These constituent materials may be commercially available. Note that elastomer A and elastomer B are different materials. The dimensions of the leaf spring core material can be appropriately set according to the dimensions of the cushioning material of the present invention, etc., within the range that achieves the effects of the present invention, and are designed to be enclosed (completely covered) within the elastic body. For example, the thickness of the leaf spring core material can be 0.05 to 10.0 mm, 0.05 to 2.0 mm, or 0.1 to 1.0 mm.

[0026] In order to control the bending direction of the support column portion when the cushioning material of the present invention is compressed, the leaf spring core material has a structure that allows control of the bending direction during compression. For example, in one example of a preferred embodiment of the present invention shown in Figure 1, a bent portion 122 is provided on the leaf spring core material 120 in order to keep the bending position of the leaf spring core material 120 at a constant position. By controlling the bending direction during compression in this way, the shock absorption performance or cushioning performance of the cushioning material of the present invention can be improved, and variations between cushioning materials (variations in bending direction and bending position for each support column portion) can be suppressed, resulting in a stable cushioning material with fewer quality errors. Furthermore, by controlling the bending direction of the support column portion to be uniform during compression, the amount of displacement until transitioning to stage (C) in Figure 4(b) can be widened, and the occurrence of compression set can be suppressed. For example, when the support column of the cushioning material of the present invention is bent in the shape shown in stage (B) of Figure 4(b), it is preferable that the leaf spring core material has two bent sections at positions corresponding to the elastic support column. The number of bent sections can be determined by the desired folding structure, and is preferably one or more, but may be two or more, or three or more. It is preferable that the bent sections are provided at positions that are symmetrical with respect to the center of the V-shaped structure. Furthermore, the shape of the bent sections is not particularly limited as long as it is a structure that can control the bending direction of the support column during compression, and may be an arc shape that protrudes in the opposite direction to the bending direction, as shown in Figure 1. The radius of curvature of the bent sections can be appropriately set depending on the dimensions of the cushioning material and the thickness of the leaf spring core material, and may be, for example, 2.0 to 5.0 mm, or may exceed 5 mm.

[0027] If the constituent material of the leaf spring core is metal, it is preferable that the metal is insulated. By applying insulation, the cushioning material of the present invention can be used in electrical and electronic components such as batteries. Known insulation methods can be applied as insulation methods, such as coating with a highly insulating resin.

[0028] (flat plate material) The cushioning material of the present invention may have flat plates on at least one of the upper and lower and / or left and right sides of the V-shaped structure. That is, the contact surface may be in contact with the inner surface of the flat plate, and the outer surface of the flat plate may be in contact with the compression surface. Furthermore, when the cushioning material of the present invention has flat plates, the contact portion is controlled so as to suppress sliding against the flat plate during compression, and the contact surface of the contact portion may be bonded to the flat plate via an adhesive layer. Note that if the flat plate is a rigid body, the inner surface of the flat plate can also be considered as the compression surface. In the schematic diagram shown in Figure 2, the inner surface of the flat plate 130 is considered as the compression surface 300. When the cushioning material of the present invention includes a flat plate, the constituent material of the flat plate is preferably one that has high hardness and does not deform under compression, and a thermosetting resin, thermoplastic resin, or metal having such properties is more preferable. Furthermore, when the flat plate is made of metal, it is preferable that the flat plate is subjected to the insulating treatment described above.

[0029] [Composite cushioning material] The cushioning material of the present invention can also be stacked in two or more layers in the height direction to form a composite cushioning material. Figure 5 shows a vertical cross-sectional view of a composite cushioning material 200 in which the cushioning material of the present invention is stacked in two layers in the height direction. In the composite cushioning material 200 of Figure 5, a flat plate material 130 is placed between the cushioning material of the present invention, which has a shape (wavy) in which two or more V-shaped structures shown in Figure 1(a) are connected in the horizontal direction. When stacking the cushioning material of the present invention without using the flat plate material 130, it is preferable to stack them so that the contact portions of the cushioning material of the present invention are in contact with each other. When stacking the cushioning materials of the present invention, it is preferable to bond the cushioning materials to each other, or to the cushioning materials and the flat plate material, via an adhesive layer. The bonding method described above is an example of such bonding method.

[0030] (Method of manufacturing cushioning material) The cushioning material of the present invention can be manufactured by the same method as ordinary elastic cushioning materials, except as specified in the present invention. For example, it can be manufactured by placing a leaf spring core material into the raw material of elastomer A in a vulcanizing / heating mold, vulcanizing / heating it, and then cooling it. [Examples]

[0031] The present invention will be described in more detail below based on examples, but the present invention is not limited thereto.

[0032] <Design Example> Each cushioning material was designed for Examples 1-6 and Comparative Examples 1-4, and the relationship between surface pressure and displacement of each cushioning material was evaluated by simulation. The dimensions and constituent materials of each cushioning material used in these examples are as follows. • Dimensions of cushioning material Width of the cushioning material (total width when four V-shaped structures are connected horizontally): 18.0 mm Cushioning material height: 7.6mm Depth of cushioning material: 25.0 mm • Elastic body Material: Ethylene propylene diene rubber (EPDM) Static shear modulus: 6.66 MPa Young's modulus: 20 MPa Poisson's ratio: 0.50 • Leaf spring core Material: Stainless steel (SUS304-CSP) Young's modulus: 193,000 MPa Poisson's ratio: 0.29 Density: 7.93×10 -9 t / mm 3 ·Flat material Material: Rigid body Thickness: 2.0mm

[0033] (Example 1) A 0.20 mm thick stainless steel was designed to have a corrugated cross-sectional shape (a shape in which four V-shaped structures are connected horizontally), and two bent sections with a radius of curvature of 3.0 mm were provided in the region corresponding to the support column of the elastic body, forming a leaf spring core. The periphery of this leaf spring core was covered with ethylene propylene diene rubber, and an elastic body was designed with a rectangular shape at the edge of the part facing the compression surface of the contact section (referred to simply as "shape of the contact section edge" in the table). The V-shape angle θ formed by two adjacent support sections was set to 64 degrees. Furthermore, a 2.0 mm thick flat plate was provided so as to be in contact with the upper and lower contact sections, forming the cushioning material of Example 1 (same shape as Figure 2(a) except for the thickness of the flat plate).

[0034] (Example 2) The cushioning material of Example 2 was constructed in the same manner as in Example 1, except that an adhesive layer was provided on the contact surface of the contact portion, and the contact surface and the flat plate material were bonded (fixed) together.

[0035] (Examples 3 and 4) Except for the hardness and friction coefficient of the elastic material being as shown in Table 1 below, the cushioning materials of Examples 3 and 4 were constructed in the same manner as in Example 1.

[0036] (Examples 5 and 6) The hardness and friction coefficient of the elastic material were set as shown in Table 1 below, and the shape of the edge of the part facing the compression surface of the contact portion was made curved, but otherwise the cushioning material of Examples 5 and 6 was configured the same as in Example 1 (the shape was the same as in Figure 2(b) except for the thickness of the flat plate material).

[0037] (Comparative Example 1) The cushioning material of Comparative Example 1 was constructed in the same manner as in Example 1, except that an adhesive layer was provided on the part corresponding to the contact surface of the leaf spring core material, without using an elastic body, and the flat plate material was bonded (fixed) to it with the adhesive layer.

[0038] (Comparative Example 2) The cushioning material for Comparative Example 2 was constructed in the same manner as in Example 1, except that a leaf spring core material was not used.

[0039] (Comparative Example 3) The cushioning material for Comparative Example 3 was constructed in the same manner as in Example 1, except that a bent portion was not provided in the leaf spring core material.

[0040] (Comparative Example 4) The cushioning material for Comparative Example 4 was constructed in the same manner as in Example 1, except that the coefficient of friction of the elastic material was set to 0.1.

[0041] <Compression Evaluation Method> For each of the above cushioning materials, the surface pressure and change were calculated using static elastic simulation (pressure distance: 3 mm) with Abaqus (https: / / www.cae-sc.com / product / Abaqus). The results are shown in Figures 6-8.

[0042] [Table 1]

[0043] (Comparison with Examples 1 and 2, and Comparative Examples 1-3) Figure 6 shows the relationship between surface pressure and displacement in Examples 1 and 2 and Comparative Examples 1 and 2. In Comparative Example 1, the cushioning material did not use an elastic material, resulting in excessively high surface pressure in the region of stage (B), and it became clear that the shock absorption performance was low (the reaction force was too strong). In Comparative Example 2, the cushioning material did not use a leaf spring core, so it was not possible to maintain high surface pressure in the regions of stages (A) and (B), resulting in low shock absorption performance (the reaction force was too weak). Furthermore, in Comparative Example 3, the cushioning material did not have a bent portion in the leaf spring core, and the results varied so much that reproducible evaluation could not be performed. In contrast, the cushioning materials of Examples 1 and 2, which satisfy the configuration of the present invention, both exhibited a wide stage (B) region ranging from a displacement of approximately 0.3 to 0.5 mm to a displacement of approximately 2.5 mm, showing a moderately high surface pressure, and a gradual increase in surface pressure at this stage, demonstrating excellent shock absorption or cushioning performance. In the cushioning material of Example 1, the coefficient of friction of the elastic body is 0.3, so slippage at the contact point is suppressed during compression, and the compressive force can be absorbed by the V-shaped structure. In the cushioning material of Example 2, the contact surface is bonded (fixed) to the compression surface, so the compressive force can be effectively absorbed by the V-shaped structure.

[0044] (Comparison with Examples 1, 3, 4 and Comparative Example 4) Figure 7 shows the relationship between surface pressure and displacement in Examples 1, 3, and 4, and Comparative Example 4. The cushioning material of Comparative Example 4 showed a low surface pressure relative to the displacement (for example, a surface pressure of approximately 8 MPa when the displacement was 2.5 mm). This was presumed to be because the friction coefficient of the elastic material in the cushioning material of Comparative Example 4 was low at 0.1, causing slippage at the contact points during compression, which widened the V-angle, and preventing the V-structure from properly absorbing the compressive force. In contrast, in the cushioning materials of Examples 1, 3, and 4, where the coefficient of friction of the elastic body was 0.3 or higher, it was shown that slippage at the contact points during compression was suppressed, and that the compressive force could be absorbed by the V-shaped structure. The hardness of the elastic body of the cushioning material in Example 1 was higher than that of the cushioning material in Example 3, and it was found that it exhibited higher surface pressure. Furthermore, in the cushioning material in Example 4, the coefficient of friction of the elastic body was high at 0.7, suggesting that slippage at the contact points was further suppressed, and that the compressive force was absorbed effectively by the V-shaped structure.

[0045] (Comparison with Examples 5 and 6) Figure 8 shows the relationship between surface pressure and displacement in Examples 5 and 6. As shown in Figure 2(b), the cushioning materials of Examples 5 and 6 have a curved edge shape at the part facing the compression surface of the contact area, and the contact area is designed to be thick at 1.0 mm. It was found that the cushioning materials of Examples 5 and 6 exhibit a high cushioning effect in a lower surface pressure range (a surface pressure that is sufficiently high to exhibit shock absorption performance; for example, a surface pressure of 9 MPa or more when the displacement is 2.5 mm) compared to the cushioning materials of Examples 1 to 4.

[0046] From the above, it has become clear that a cushioning material satisfying the configuration of the present invention maintains a moderately high surface pressure over a wide range of displacements, exhibits sufficiently high shock absorption or cushioning properties, and is also less prone to compression set. [Explanation of symbols]

[0047] 100, 100A, 100B, 100C, 100D buffer material 110 Elastic body 111 Contact part 112 Pillar section 113 Contact surface 120 leaf spring core material 121 Curved section 122 Bending section 130 Flat material 200 Composite cushioning material 300 Compression surface t Height of the contact area w width of the support column S space θ V-shaped angle

Claims

1. The device comprises an elastic body made of elastomer A with a V-shaped or wavy cross-section, and a leaf spring core material enclosed along the shape of the elastic body, wherein the bending direction of the support column portion during compression is controlled in the leaf spring core material. A cushioning material wherein the coefficient of friction of the elastic body is 0.3 or more, and / or an adhesive layer is provided on the contact surface of the contact portion of the elastic body.

2. The cushioning material according to claim 1, wherein the constituent material of the leaf spring core is metal or elastomer B.

3. The cushioning material according to claim 2, wherein the metal is selected from carbon steel, phosphor bronze, copper, titanium alloy, nickel alloy, steel, and stainless steel.

4. The cushioning material according to claim 3, wherein the width of the support column portion is 0.5 times or less the height of the contact portion.

5. The cushioning material according to claim 4, further comprising a flat plate material that contacts the aforementioned contact portion.

6. A composite cushioning material comprising two or more layers of the cushioning material described in any one of claims 1 to 5, stacked in the height direction of the cushioning material.

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