Laminate and method for manufacturing the same

Abstract

To provide a laminate which can be improved in joining strength between a metal body and a resin body.SOLUTION: In a laminate 1, a metal body 2 and a resin body 3 are joined together. The laminate 1 is provided with an adhesive layer 4 containing a thermoplastic resin or a thermoplastic elastomer between the metal body 2 and the resin body 3. A molding shrinkage rate of the adhesive layer 4 is 1.5% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a laminate and a method for manufacturing the same.

Background Art

[0002] Conventionally, laminates in which a metal body and a resin body are joined have been used for various applications. In recent years, such laminates have been used in the development of airless tires.

[0003] The following Patent Document 1 describes an airless tire. This airless tire includes a cylindrical tread ring having a ground contact surface, a hub disposed radially inside the tread ring and fixed to an axle, and spokes connecting the tread ring and the hub.

[0004] The hub is formed of a metal body. On the other hand, the spokes are formed of a resin body. Therefore, the composite body composed of the hub and the spokes corresponds to the above-described laminate. These hub and spokes are joined via an adhesive.

Prior Art Documents

Patent Documents

[0005] <000002​​​​​​​​​​​​​​​​This disclosure was devised in view of the above-described circumstances, and its primary purpose is to provide a laminate capable of improving the bonding strength between a metal body and a resin body. [Means for solving the problem]

[0008] This disclosure relates to a laminate in which a metal body and a resin body are joined together, wherein an adhesive layer containing a thermoplastic resin or thermoplastic elastomer is provided between the metal body and the resin body, and the molding shrinkage rate of the adhesive layer is 1.5% or less. [Effects of the Invention]

[0009] By adopting the above configuration, the joint of the present disclosure makes it possible to improve the bonding strength between the metal body and the resin body. [Brief explanation of the drawing]

[0010] [Figure 1] This is a partial cross-sectional view of the laminate according to this embodiment. [Figure 2] (a) to (c) are cross-sectional views illustrating the manufacturing method of the laminate according to this embodiment. [Figure 3] This is a partial front view of the airless tire of this embodiment, as seen from the axle direction. [Modes for carrying out the invention]

[0011] Embodiments of this disclosure will be described below with reference to the drawings. It should be understood that the drawings contain exaggerations and representations that differ from the actual structural proportions in order to aid in understanding the content of the disclosure. Furthermore, the same or common elements are denoted by the same reference numerals throughout each embodiment, and redundant explanations are omitted. Moreover, the specific configurations shown in the embodiments and drawings are for the purpose of understanding the content of this disclosure, and this disclosure is not limited to the specific configurations shown.

[0012] [Laminate (First Embodiment)] [Overall structure of the laminate] Figure 1 shows a partial cross-sectional view of the laminate 1 of this embodiment. As shown in Figure 1, the laminate 1 of this embodiment is made up of a metal body 2 and a resin body 3 joined together. An adhesive layer 4 is provided between the metal body 2 and the resin body 3.

[0013] [Metal body] As shown in Figure 1, the metal body 2 is not particularly limited as long as it can be bonded to the resin body 3 via the adhesive layer 4. For example, the metal body 2 in this embodiment may be made of iron-based metals, aluminum-based metals, magnesium-based metals, copper-based metals, and titanium-based metals.

[0014] Examples of iron-based metals include iron, steel, and stainless steel. Examples of aluminum-based metals include aluminum and aluminum alloys. Examples of magnesium-based metals include magnesium alloys. Examples of copper-based metals include copper and copper alloys. Examples of titanium-based metals include titanium and titanium alloys.

[0015] In this embodiment, the metal body 2 is made of an aluminum-based metal from among the above-mentioned metals. Compared to other metals, such aluminum-based metals are lightweight and have high workability.

[0016] [Resin body] The resin body 3 is not particularly limited as long as it can be bonded to the metal body 2 via the adhesive layer 4. In this embodiment, the resin body 3 is made of a polymer material. The polymer material is not particularly limited, but it is preferable that it is a resin or elastomer that can be molded by injection molding or casting.

[0017] Examples of resins or elastomers include polyolefins, polyvinyl chlorides, polystyrenes, methacrylic resins, polycarbonates, polyamides, polyimides, polyacetals, fluororesins, urea resins, phenolic resins, polyesters, polyurethanes, epoxy resins, melamine resins, and silicone resins.

[0018] In the present embodiment, among the above-mentioned polymer materials (resins or elastomers), from the viewpoints of molding / processing properties and the degree of freedom in material design, it is preferable to adopt a thermoplastic elastomer. The thermoplastic elastomer is not particularly limited, but a thermoplastic polyester elastomer, a thermoplastic polyamide elastomer, or a thermoplastic polyurethane elastomer is preferable. Among these thermoplastic elastomers, from the viewpoint of improving durability, a thermoplastic polyester elastomer resin can be preferably adopted.

[0019] Incidentally, in a conventional laminate as described in Patent Document 1 above, the metal body 2 and the resin body 3 are joined via an adhesive. Generally, since the resin body 3 has a different coefficient of thermal expansion from that of the metal body 2, when thermal shrinkage or the like occurs in the metal body 2 and the resin body 3, stress acts on the cured product of the adhesive between them. Such stress is absorbed by the adhesive. Thereby, the bonding strength between the metal body 2 and the resin body 3 is maintained. However, from the viewpoint of improving the durability of the laminate, further improvement in the bonding strength between the metal body 2 and the resin body 3 is desired.

[0020] As a result of intensive studies, the inventors have found that a thermoplastic resin and a thermoplastic elastomer can effectively absorb stress due to thermal shrinkage or the like acting between the metal body 2 and the resin body 3 having different coefficients of thermal expansion, and improve the adhesive strength between the metal body 2 and the resin body 3. Based on such findings, in the laminate 1 of the present embodiment, an adhesive layer 4 containing a thermoplastic resin or a thermoplastic elastomer is provided between the metal body 2 and the resin body 3.

[0021] [Adhesive layer] The adhesive layer 4 of the present embodiment contains a thermoplastic resin or a thermoplastic elastomer. Thereby, the laminate 1 of the present embodiment can effectively absorb the stress acting due to thermal shrinkage or the like of the metal body 2 and the resin body 3, so that the bonding strength between the metal body 2 and the resin body 3 is improved. Therefore, the durability of the laminate 1 is improved.

[0022] The adhesive layer 4 is not particularly limited as long as it contains a thermoplastic resin or thermoplastic elastomer. Preferably, the thermoplastic resin and thermoplastic elastomer can be molded by injection molding or casting. The adhesive layer 4 in this embodiment is composed solely of a thermoplastic resin or thermoplastic elastomer, but is not particularly limited.

[0023] Examples of thermoplastic resins or thermoplastic elastomers include thermoplastic polyolefins, polyvinyl chloride, polystyrene, methacrylic resins, polycarbonates, polyamides, polyimides, polyacetals, fluororesins, urea resins, phenolic resins, polyesters, polyurethanes, epoxy resins, melamine resins, and silicone resins.

[0024] In this embodiment, among the above-mentioned thermoplastic resins or thermoplastic elastomers, thermoplastic polyester elastomers, thermoplastic polyamide elastomers, and thermoplastic polyurethane elastomers are preferred from the viewpoint of moldability, processability, and freedom of material design. Among these thermoplastic elastomers, thermoplastic polyester elastomer resin can be suitably used from the viewpoint of improving the adhesive strength between the metal body 2 and the resin body 3.

[0025] Furthermore, the molding shrinkage rate of the adhesive layer 4 in this embodiment is limited to 1.5% or less. This molding shrinkage rate indicates the extent to which the adhesive layer (thermoplastic resin or thermoplastic elastomer) 4 shrinks when solidifying in relation to the mold 11 (shown in Figure 2(c)) for forming the laminate 1. The smaller this molding shrinkage rate, the smaller the shrinkage associated with the solidification of the adhesive layer 4, making it possible to effectively absorb stress due to thermal shrinkage, etc., acting between the metal body 2 and the resin body 3. Therefore, the bonding strength between the metal body 2 and the resin body 3 is improved. In order to effectively exert this effect, the molding shrinkage rate is preferably 1.1% or less. On the other hand, if the molding shrinkage rate is too small, demolding from the mold 11 becomes difficult, so it is preferable to set it to 0.3% or more. The molding shrinkage rate is measured in accordance with JIS K7152-4 (2005).

[0026] The thickness W1 of the adhesive layer 4 is preferably set to 20 to 200 μm. Setting the thickness W1 to 20 μm or more effectively absorbs stress due to thermal shrinkage acting between the metal body 2 and the resin body 3, thereby improving the bonding strength between the metal body 2 and the resin body 3. Furthermore, the molding of the adhesive layer 4 becomes easier, and variations in the thickness W1 are suppressed (for example, ±2.5 μm). On the other hand, setting the thickness W1 to 200 μm or less suppresses the decrease in cohesive force of the adhesive layer 4 caused by the increased thickness, and maintains the bonding strength. From this viewpoint, the thickness W1 is preferably 60 μm or more, and preferably 160 μm or less.

[0027] The spring constant of the adhesive layer 4 is preferably set to 3.0 to 20.0 N / mm. Setting the spring constant to 20.0 N / mm or less effectively absorbs stress due to thermal contraction and other factors acting between the metal body 2 and the resin body 3. On the other hand, setting the spring constant to 3.0 N / mm or more suppresses the decrease in cohesive force and maintains the bonding strength. From this viewpoint, the spring constant is preferably 16.0 N / mm or less, and more preferably 7.0 N / mm or more.

[0028] To measure the spring constant of adhesive layer 4, first, a No. 7 dumbbell-shaped test specimen (hereinafter sometimes simply referred to as "test specimen") formed from adhesive layer 4 is prepared. Next, a tensile test of the test specimen is performed at a temperature of 23°C in accordance with JIS K6251:2010 "Vulcanized rubber and thermoplastic rubber - Method for determining tensile properties". Then, the elongation at break (EB(23°C)) at 23°C is measured, and the spring constant of adhesive layer 4 is measured (calculated) based on the elongation-displacement curve at that time. Furthermore, the spring constant can be appropriately set by adjusting the hardness of adhesive layer 4 (i.e., by adjusting the composition and molecular weight of the thermoplastic resin or thermoplastic elastomer constituting adhesive layer 4).

[0029] The tensile shear strength of the adhesive layer 4 at 80°C is preferably set to 1.0 MPa or higher. Setting the tensile shear strength at 80°C to 1.0 MPa or higher suppresses cohesive failure of the adhesive layer 4 in high-temperature environments in which the laminate 1 is used (for example, when an airless tire containing the laminate 1 is in operation). From this viewpoint, it is desirable to set the tensile shear strength at 80°C to 3.0 MPa or higher. The tensile shear strength is measured in accordance with JIS K6850 "Test Method for Tensile Shear Adhesion Strength of Rigid Adhered Materials," by shifting the position of the metal body 2 and the resin body 3 along the adhesive surface and measuring the fracture stress at which the adhesive layer 4 breaks due to the tensile shear stress acting on the adhesive layer 4. Furthermore, the tensile shear strength can be appropriately set by adjusting the hardness and thickness W1 of the adhesive layer 4.

[0030] The complex modulus of elasticity E* of the adhesive layer 4 at 70°C is preferably set to 30 to 150 MPa. Setting the complex modulus of elasticity E* at 70°C to 30 MPa or higher maintains the rigidity of the adhesive layer 4 under the operating environment of the laminate 1 (for example, when an airless tire containing the laminate 1 is driven), thereby improving the bonding strength between the metal body 2 and the resin body 3. On the other hand, setting the complex modulus of elasticity E* at 70°C to 150 MPa or lower ensures the flexibility of the adhesive layer 4, suppressing delamination of the adhesive layer 4 between the metal body 2 and the resin body 3. From this viewpoint, the complex modulus of elasticity E* at 70°C is preferably 40 MPa or higher, and also preferably 120 MPa or lower.

[0031] The complex modulus of elasticity E* is measured in accordance with the provisions of JIS K6394, using a dynamic viscoelasticity measuring device (Iplexer series) manufactured by GABO, under the following measurement conditions. Frequency: 10Hz Initial strain: 5% Dynamic distortion: ±1% Temperature: 70℃ Deformation mode: Tension

[0032] [Uneven portion] To increase the adhesive strength with the adhesive layer 4, it is preferable that the first surface S of the metal body 2, which is intended to come into contact with the adhesive layer 4, has an uneven surface (not shown). Such an uneven surface provides an anchoring effect with the adhesive layer 4, thereby increasing the adhesive strength between the metal body 2 and the adhesive layer 4.

[0033] The uneven surfaces (not shown) can be formed, for example, by known surface treatments such as laser processing or shot blasting. In this embodiment, laser processing is employed, which can form uneven surfaces of any desired roughness with high precision.

[0034] [Layer of adhesive] A layer of adhesive (cured product), not shown, may be interposed between the adhesive layer 4 and the metal body 2. Such an adhesive layer can further increase the bonding strength between the metal body 2 and the adhesive layer 4.

[0035] The adhesive is not particularly limited as long as it can improve the bonding strength between the metal body 2 and the adhesive layer 4. In this embodiment, for example, the adhesives "Chemlock 218E," "Chemlock 210," and "Chemlock IMB1040" manufactured by Rhode Japan Co., Ltd. are preferably used ("Chemlock" is a registered trademark). Other adhesives include, for example, "Metalock C-12" and "Metalock UA" manufactured by Toyo Chemical Research Institute Co., Ltd. ("Metalock" is a registered trademark).

[0036] The thickness of the adhesive layer (not shown) is preferably set to 10 to 50 μm. Setting the thickness to 10 μm or more increases the bonding strength between the metal body 2 and the adhesive layer 4. On the other hand, setting the thickness to 50 μm or less prevents the adhesive layer from becoming unnecessarily thick. This prevents the adhesive layer from being damaged by the strain acting between the metal body 2 and the resin body 3. From this viewpoint, the thickness is preferably 15 μm, and more preferably 35 μm.

[0037] [Method for manufacturing laminates] Next, the manufacturing method of the laminate 1 of this embodiment (hereinafter sometimes simply referred to as the "manufacturing method") will be described. Figures 2(a) to (c) are cross-sectional views illustrating the manufacturing method of the laminate of this embodiment.

[0038] [Melting thermoplastic resin or thermoplastic elastomer] In the manufacturing method of this embodiment, first, a thermoplastic resin or thermoplastic elastomer (in this example, thermoplastic elastomer 4A) for forming the adhesive layer 4 is melted. For melting, for example, a known injection molding machine (not shown) is used. In this embodiment, the thermoplastic elastomer 4A is temperature-controlled (for example, 200 to 300°C) inside the cylinder (not shown) of the injection molding machine. As a result, the thermoplastic elastomer 4A is melted into a liquid state.

[0039] [Molten thermoplastic resin or thermoplastic elastomer is brought into contact with a metal body.] Next, in the manufacturing method of this embodiment, a step is performed in which the molten thermoplastic resin or thermoplastic elastomer (in this example, thermoplastic elastomer 4A) is brought into contact with the metal body 2.

[0040] In this process, first, as shown in Figure 2(a), the metal body 2 is set in, for example, the cavity 12 of the mold 11. At this time, an empty space 13 is left in the cavity 12 so that the adhesive layer 4 and the resin body 3 (shown in Figure 2(c)) can be supplied. Also, the first surface S of the metal body 2 is positioned to face the empty space 13 of the cavity 12.

[0041] Next, in the process of this embodiment, as shown in Figure 2(b), liquid thermoplastic elastomer 4A is supplied (injected) from the cylinder (not shown) of an injection molding machine to the first surface S of the metal body 2 which is intended to come into contact with the adhesive layer 4. This allows the molten thermoplastic elastomer 4A to come into contact with the first surface S of the metal body 2. In this embodiment, the thermoplastic elastomer 4A is formed in a sheet-like shape on the first surface S.

[0042] Furthermore, if an uneven surface (not shown) is formed on the first surface S of the metal body 2, it is preferable that the step of forming the uneven surface on the first surface S is performed prior to the step of bringing the thermoplastic elastomer 4A into contact with the metal body 2. The formation of the uneven surface is carried out using the procedure described above.

[0043] Furthermore, when an adhesive layer (cured product) not shown is interposed between the adhesive layer 4 and the metal body 2, it is preferable that the adhesive be applied to the first surface S of the metal body 2 prior to the step of bringing the thermoplastic elastomer 4A into contact with the metal body 2. In order to improve the adhesive strength of the adhesive, a step of preheating the adhesive applied to the first surface S may be performed. For preheating the adhesive, it is preferable to use a heating device (not shown) provided separately from the mold 11 shown in Figure 2(b). The temperature of the adhesive is preferably set to, for example, 30 to 100°C. The preheating time is preferably set to, for example, 10 to 30 minutes.

[0044] [Melting the resin] Next, in the manufacturing method of this embodiment, a step is performed to melt the resin 3A (shown in Figure 2(c)) for forming the resin body 3. In this embodiment, for example, a known injection molding machine (not shown) is used. In this embodiment, the resin 3A is temperature-controlled (for example, 200 to 300°C) inside the cylinder (not shown) of the injection molding machine. As a result, the resin 3A is melted into a liquid state.

[0045] [Liquid resin is brought into contact with thermoplastic resin or thermoplastic elastomer] Next, in the manufacturing method of this embodiment, a step is performed in which liquid resin 3A is brought into contact with a thermoplastic resin or thermoplastic elastomer (in this example, thermoplastic elastomer 4A) that is in contact with the metal body 2. In the step of this embodiment, as shown in Figure 2(c), liquid resin 3A is supplied (injected) into the empty space 13 of the cavity 12 from the cylinder of the injection molding machine (not shown). In this embodiment, the liquid resin 3A can be brought into contact with the thermoplastic elastomer 4A.

[0046] [Joining metal and resin bodies] Next, in the manufacturing method of this embodiment, a thermoplastic resin or thermoplastic elastomer (in this example, thermoplastic elastomer 4A) and resin 3A are cured to join the metal body 2 and the resin body 3 via an adhesive layer 4. In this embodiment, the thermoplastic elastomer 4A and resin 3A (thermoplastic resin) are cooled and cured in the cavity 12. As a result, a laminate 1 (shown in Figure 1) is obtained in which the metal body 2 and the resin body 3 are joined (integrally molded) via the adhesive layer 4.

[0047] In the manufacturing method of this embodiment, an adhesive layer 4 containing a thermoplastic resin or thermoplastic elastomer is provided between the metal body 2 and the resin body 3, so that stress acting due to thermal shrinkage of the metal body 2 and the resin body 3 can be effectively absorbed. Furthermore, since the molding shrinkage rate of the adhesive layer (thermoplastic resin or thermoplastic elastomer) 4 is limited to 1.5% or less, shrinkage associated with the solidification of the adhesive layer 4 can be reduced. As a result, stress due to thermal shrinkage acting between the metal body 2 and the resin body 3 can be absorbed more effectively. Therefore, in the manufacturing method of this embodiment, it is possible to manufacture a laminate 1 with improved bonding strength between the metal body 2 and the resin body 3.

[0048] Furthermore, if an uneven surface (not shown) is formed on the first surface S (shown in Figure 2(b)) of the metal body 2 that is in contact with the adhesive layer 4, an anchoring effect with the adhesive layer 4 can be achieved, thereby enabling the manufacture of a laminate 1 with further improved adhesive strength between the metal body 2 and the adhesive layer 4. Moreover, if a layer of adhesive (cured product) not shown is interposed between the adhesive layer 4 and the metal body 2, a laminate 1 with further improved adhesive strength between the metal body 2 and the adhesive layer 4 can be manufactured.

[0049] [Airless tires] Next, an airless tire including laminate 1 will be described. Figure 3 is a partial front view of the airless tire of this embodiment as seen from the axle direction. As shown in Figure 3, the airless tire 16 is composed of a hub portion 17 fixed to the axle, an annular tread ring 18 for contacting the ground, and spoke portions 19 connecting the hub portion 17 and the tread ring 18.

[0050] The hub portion 17 is formed of, for example, a metal material.

[0051] The tread ring 18 is made of vulcanized rubber. To increase its circumferential rigidity, the tread ring 18 may, for example, be provided with a reinforcing cord layer 25 (shown by a dashed line) inside.

[0052] The spoke portion 19 of this embodiment integrally includes, for example, an outer portion 21 on the radially outer side of the tire, an inner portion 22 on the radially inner side of the tire, and a plurality of spoke elements 23.

[0053] The outer portion 21 is an annular body joined to the inner circumferential surface of the tread ring 18. The inner portion 22 is an annular body joined to the outer circumferential surface of the hub portion 17. Each spoke element 23 extends in the tire radial direction between the outer portion 21 and the inner portion 22, connecting them to one another.

[0054] In this embodiment, the metal body 2 (shown in Figure 1) of the laminate 1 forms the hub portion 17, and the resin body 3 (shown in Figure 1) of the laminate 1 forms the spoke portion 19 (inner portion 22). An adhesive layer 4 containing a thermoplastic resin or thermoplastic elastomer is provided between the hub portion 17 and the spoke portion 19. Therefore, the airless tire 16 of this embodiment utilizes the laminate 1.

[0055] The laminate 1 can improve the bonding between the metal body 2 (hub portion 17) and the resin body 3 (spoke portion 19) through an adhesive layer 4 containing a thermoplastic resin or thermoplastic elastomer. Furthermore, since the molding shrinkage rate of the adhesive layer 4 is limited to 1.5% or less, the bonding between the metal body 2 (hub portion 17) and the resin body 3 (spoke portion 19) can be further improved. As a result, the airless tire 16 of this embodiment can increase the bonding strength between the hub portion 17 and the spoke portion 19 (inner portion 22), thereby improving durability (high-speed durability).

[0056] [How to manufacture airless tires] Next, the manufacturing method of the airless tire 16 of this embodiment (hereinafter sometimes simply referred to as the "manufacturing method") will be described. The manufacturing method of this embodiment uses known procedures described in, for example, patent documents (Japanese Patent Publication No. 2015-217717). The following description will focus on procedures that are not publicly known, and publicly known procedures may be omitted.

[0057] [Prepare the hub] In the manufacturing method of this embodiment, first, a step is performed to prepare the hub portion 17 (metal body 2). If an uneven surface (not shown) is formed on the first surface S of the hub portion 17, which is intended to come into contact with the adhesive layer 4, it is preferable to perform a step of forming the uneven surface on the first surface S prior to the step of bringing the thermoplastic elastomer 4A into contact with the hub portion 17. The formation of the uneven surface is performed according to the procedure described above.

[0058] [Vulcanization molding of the tread rings] Next, in the manufacturing method of this embodiment, a step is performed to vulcanize the annular tread ring 18. In this step, a surface treatment layer (not shown) is formed on the inner circumferential surface of the tread ring 18. The surface treatment layer is formed, for example, by chlorination treatment.

[0059] [Set the hub and tread ring into the mold] Next, in the manufacturing method of this embodiment, the hub portion 17 and the tread ring 18 are set in the cavity of the mold (neither of which is shown). After these components are set, empty spaces (not shown) are formed in the cavity of the mold for molding the adhesive layer 4 and the spoke portion 19.

[0060] [Melting thermoplastic resin or thermoplastic elastomer] Next, in the manufacturing method of this embodiment, a step is performed to melt a thermoplastic resin or thermoplastic elastomer (in this example, thermoplastic elastomer 4A) for forming the adhesive layer 4. The thermoplastic elastomer 4A is melted into a liquid state in the cylinder of an injection molding machine (not shown), similar to the manufacturing method of the laminate 1 shown in Figure 2.

[0061] [Molten thermoplastic resin or thermoplastic elastomer is brought into contact with the hub.] Next, in the manufacturing method of this embodiment, a step is performed in which the molten thermoplastic resin or thermoplastic elastomer (in this example, thermoplastic elastomer 4A) is brought into contact with the hub portion 17 made of a metal body 2.

[0062] In this process, similar to the manufacturing method of the laminate 1 shown in Figure 2, liquid thermoplastic elastomer 4A is supplied (injected) from the cylinder (not shown) of an injection molding machine to the first surface S of the hub portion 17 (metal body 2) which is intended to come into contact with the adhesive layer 4. This allows the molten thermoplastic elastomer 4A to come into contact with the first surface S of the hub portion 17. In this embodiment, the thermoplastic elastomer 4A is formed in a sheet-like shape on the first surface S.

[0063] When an adhesive layer (cured product) not shown is interposed between the adhesive layer 4 and the hub portion 17, it is preferable that the adhesive be applied to the first surface S of the hub portion 17 prior to the step of bringing the thermoplastic elastomer 4A into contact with the hub portion 17. In order to improve the adhesive strength of the adhesive, the adhesive applied to the first surface S may be preheated as described above.

[0064] [Melting the resin] Next, in the manufacturing method of this embodiment, a step is performed to melt the resin 3A for forming the spoke portion 19 (resin body 3). The melting of the resin 3A is performed according to the same procedure as the manufacturing method of the laminate 1 shown in Figure 2.

[0065] [Liquid resin is brought into contact with thermoplastic resin or thermoplastic elastomer] Next, in the manufacturing method of this embodiment, a step is performed in which the liquid resin 3A is brought into contact with the thermoplastic resin or thermoplastic elastomer (in this example, thermoplastic elastomer 4A) that is in contact with the hub portion 17.

[0066] In this process, liquid resin 3A is supplied from the cylinder of the injection molding machine (not shown) into the empty space in the mold cavity (not shown). This allows the liquid resin 3A to come into contact with the thermoplastic elastomer 4A in this process.

[0067] [Joining the hub and spokes] Next, in the manufacturing method of this embodiment, a step is performed to bond the hub portion 17 and the spoke portion 19 by curing the thermoplastic resin or thermoplastic elastomer (thermoplastic elastomer 4A in this example) and the resin 3A. In this embodiment, the thermoplastic elastomer 4A and the resin 3A (thermoplastic resin) are cooled and cured in the mold cavity (neither of which is shown). As a result, an airless tire 16 (shown in Figure 3) is obtained in which the laminate 1, in which the hub portion 17 and the spoke portion 19 are joined (integrally molded) via the adhesive layer 4, and the tread ring 18 are integrated.

[0068] In the manufacturing method of this embodiment, an adhesive layer 4 containing a thermoplastic resin or thermoplastic elastomer is provided between the hub portion 17 and the spoke portion 19, so that stress acting due to thermal shrinkage of the hub portion 17 and the spoke portion 19 can be effectively absorbed. Furthermore, since the molding shrinkage rate of the adhesive layer (thermoplastic resin or thermoplastic elastomer) 4 is limited to 1.5% or less, shrinkage associated with the solidification of the adhesive layer 4 can be reduced. As a result, stress due to thermal shrinkage acting between the hub portion 17 and the spoke portion 19 can be absorbed more effectively. Therefore, the manufacturing method of this embodiment makes it possible to manufacture an airless tire 16 with improved bonding strength between the hub portion 17 and the spoke portion 19.

[0069] Furthermore, if an uneven surface (not shown) is formed on the first surface S of the hub portion 17, an anchoring effect with the adhesive layer 4 can be achieved, thereby enabling the manufacture of an airless tire 16 with improved bonding strength between the hub portion 17 and the spoke portion 19. Moreover, if a layer of adhesive (cured product) not shown is interposed between the adhesive layer 4 and the hub portion 17, an airless tire 16 with even greater bonding strength between the hub portion 17 and the adhesive layer 4 can be manufactured. Thus, the manufacturing method of this embodiment enables the manufacture of an airless tire with improved durability (high-speed durability).

[0070] Although particularly preferred embodiments of this disclosure have been described in detail above, this disclosure is not limited to the illustrated embodiments and can be modified and implemented in various ways. [Examples]

[0071] [Example A] More specific and non-limiting embodiments of this disclosure are described below. A sample of a metal body with an uneven surface formed on the first surface was prepared. Next, the metal body sample was placed into the cavity of the mold, and then a thermoplastic elastomer for forming an adhesive layer and a resin for forming a resin body were supplied to the empty space in the cavity. By curing the thermoplastic elastomer and the resin, a laminate was formed in which the metal body and the resin body were joined via the adhesive layer. The molding shrinkage rate of the adhesive layer in Examples 1 to 4 was set to 1.5% in all cases. On the other hand, the molding shrinkage rate in the comparative example was set to 2.0%. The thickness W1 of the adhesive layer in Examples 1 to 4 and the comparative example was adjusted according to Table 1. Meanwhile, the thickness of the resin layer was adjusted to 2.0 mm.

[0072] From these laminates, strip-shaped samples measuring 25 mm in width and 12 mm in length were cut out as laminate samples. The common specifications for the examples are as follows: Metal body: Aluminum alloy Ten-point average roughness Rz of uneven surface: 614 μm Resin body (resin): Thermoplastic polyester elastomer Adhesive layer: Thermoplastic polyamide elastomer Spring constant of the adhesive layer: 4.8 N / mm Complex modulus of elasticity E* of the adhesive layer at 70°C: 100 MPa

[0073] Furthermore, to evaluate the bonding strength between the metal and resin bodies in the laminate, a shear force test (T-shaped peel test) was conducted. The shear force test was performed in accordance with JIS K 6854, under room temperature conditions of 23°C and 55% humidity, and under high-temperature conditions (80°C). The test results are shown in Table 1.

[0074] [Table 1]

[0075] The test results showed that in Examples 1-4, where the molding shrinkage rate of the adhesive layer was set to 1.5% or less, material fracture occurred in the resin body during the shear force test (80°C), but no delamination occurred at the interface between the metal body and the adhesive layer, or between the adhesive layer and the resin body. On the other hand, in the comparative example where the molding shrinkage rate was set to 2.0%, interfacial delamination occurred between the metal body and the adhesive layer, or between the adhesive layer and the resin body, when the shear force (N / mm²) was measured during the shear force test (80°C). 2 ) is shown.

[0076] Examples 1-4 showed improved bonding strength between the metal body and the resin body compared to the comparative example where material fracture occurred and interfacial isolation occurred. Furthermore, since the thickness W1 of the adhesive layer in Examples 1-4 was set within a favorable range, the bonding strength between the metal body and the resin body was further improved.

[0077] Next, based on the laminates shown in Table 1, airless tires were prototyped, and their high-speed durability was evaluated. In the high-speed durability evaluation, a drum testing machine was used to load the airless tires with a load of 2.6 kN. Rolling was started at an initial speed of 100 km / h, and the speed was increased by 10 km / h every 10 minutes. The speed at which damage occurred in the airless tire (one step lower, or 10 km / h lower) is expressed as an index with Example 2 set to 100. A higher value indicates better high-speed durability.

[0078] The test results showed that Examples 1-4 were able to improve the bonding between the metal body and the resin body, and exhibited the high-speed durability (index of 100 or higher) required for airless tires compared to the comparative example. Furthermore, since the thickness W1 of the adhesive layer in Examples 1-4 was set within a favorable range, high-speed durability was further improved.

[0079] [Example B] Laminates were created based on the adhesive layer thickness W1 and spring constant of the adhesive layer shown in Table 2 (Examples 5-9). The molding shrinkage rate of these adhesive layers was set to 1.0%. Then, to evaluate the bonding between the metal and resin bodies in these laminates, shear force tests were performed in the same manner as in Example A. The common specifications of the laminates are the same as in Example A, except for the thickness W1 and spring constant shown in Table 2.

[0080] Furthermore, airless tires were prototyped using the laminates shown in Table 2, and their high-speed durability was evaluated. The shear force test and high-speed durability evaluation were performed using the same procedure as in Example A. The test results are shown in Table 2.

[0081] [Table 2]

[0082] The test results showed that Examples 5-9 had a shear force of 1.0 N / mm². 2 The shear force exceeded the required level for the laminate, or material failure occurred, improving the bonding strength between the metal and resin bodies and enhancing the high-speed durability of the airless tire. Furthermore, in Examples 6 to 9, where the spring constant of the adhesive layer was set within a preferred range, the shear force was greater or material failure occurred compared to Example 5, where the spring constant was outside the preferred range, resulting in improved high-speed durability. In addition, in Example 9, the thickness of the adhesive layer was set larger than in Example 6, which allowed for material failure in the resin body during the shear force test and improved high-speed durability.

[0083] [Example C] Laminates were fabricated based on the complex modulus E* of the adhesive layer at 70°C shown in Table 3 (Examples 10-15). Shear force tests were then performed in the same manner as in Example A to evaluate the bonding properties between the metal and resin bodies in these laminates. The common specifications of the laminates were the same as in Example A, except for the complex modulus E* shown in Table 3. The molding shrinkage rate of the adhesive layer was set to 1.0%. The thickness W1 of the adhesive layer was set to 50 μm.

[0084] Furthermore, airless tires were prototyped using the laminates shown in Table 3, and their high-speed durability was evaluated. The shear force test and high-speed durability evaluation were carried out using the same procedure as in Example A. The test results are shown in Table 3.

[0085] [Table 3]

[0086] The test results showed that in Examples 10-15, the shear force was above the specified range or material fracture occurred, demonstrating improved bonding strength between the metal and resin bodies and improved high-speed durability of the airless tires. Furthermore, in Examples 11-14, where the complex modulus E* was set within the preferred range, the shear force was greater or material fracture occurred compared to Examples 10 and 15, where the complex modulus E* was set outside the preferred range, resulting in improved high-speed durability.

[0087] [Note] This disclosure includes the following aspects.

[0088] [Disclosure 1] A laminate in which a metal body and a resin body are joined together, An adhesive layer containing a thermoplastic resin or thermoplastic elastomer is provided between the metal body and the resin body. The molding shrinkage rate of the adhesive layer is 1.5% or less. Laminated structure. [Disclosure 2] The laminate according to Disclosure 1, wherein the thickness of the adhesive layer is 20 to 200 μm. [Disclosure 3] The laminate according to disclosure 1 or 2, wherein the spring constant of the adhesive layer is 3.0 to 20.0 N / mm. [Disclosure 4] The laminate according to any one of disclosures 1 to 3, wherein the tensile shear strength of the adhesive layer at 80°C is 1.0 MPa or more. [Disclosure 5] The laminate according to any one of disclosures 1 to 4, wherein the complex modulus E* of the adhesive layer at 70°C is 30 to 150 MPa. [Disclosure 6] The laminate according to any one of disclosures 1 to 5, wherein the thermoplastic elastomer is a thermoplastic polyamide elastomer. [Disclosure 7] The laminate according to any one of disclosures 1 to 6, wherein the resin body is a thermoplastic polyester elastomer, a thermoplastic polyamide elastomer, or a thermoplastic polyurethane elastomer. [Disclosure 8] The laminate according to any one of disclosures 1 to 7, wherein the metal body has an uneven surface on the first surface that contacts the adhesive layer. [Disclosure 9] An airless tire comprising a laminate as described in any of items 1 to 8 of this disclosure. [Disclosure 10] The hub portion is fixed to the axle, A ring-shaped tread ring for contact with the ground, It includes a spoke portion that connects the hub portion and the tread ring, The metal body forms the hub portion, The resin body forms the spoke portion of the airless tire according to disclosure 9. [Disclosure 11] A method for manufacturing a laminate according to any one of disclosures 1 to 8, A step of melting the thermoplastic resin or thermoplastic elastomer for forming the adhesive layer, A step of bringing the molten thermoplastic resin or thermoplastic elastomer into contact with the metal body, A step of melting the resin for forming the aforementioned resin body, A step of bringing a liquid resin into contact with the thermoplastic resin or thermoplastic elastomer that is in contact with the metal body, The process includes curing the thermoplastic resin or thermoplastic elastomer and the resin to bond the metal body and the resin body via the adhesive layer, A method for manufacturing laminates. [Disclosure 12] A method for manufacturing a laminate according to the present disclosure 11, further comprising the step of forming an uneven surface on the first surface that is to be in contact with the adhesive layer, prior to the contact step. [Disclosure 13] A method for manufacturing an airless tire as described in Disclosure 10, A step of melting the thermoplastic resin or thermoplastic elastomer for forming the adhesive layer, A step of bringing the molten thermoplastic resin or thermoplastic elastomer into contact with the hub portion made of the metal body, A step of melting the resin for forming the spoke portion, A step of bringing a liquid resin into contact with the thermoplastic resin or thermoplastic elastomer that is in contact with the hub portion, The process includes curing the thermoplastic resin or thermoplastic elastomer and the resin to join the hub portion and the spoke portion. A method for manufacturing airless tires. [Disclosure 14] A method for manufacturing an airless tire according to the disclosure 13, further comprising the step of forming an uneven surface on the first surface of the hub portion that is intended to come into contact with the adhesive layer, prior to the aforementioned contact step. [Explanation of symbols]

[0089] 1. Laminate 2 Metal body 3 Resin body 4 Adhesive layer

Claims

1. A laminate in which a metal body and a resin body are joined together, An adhesive layer containing a thermoplastic resin or thermoplastic elastomer is provided between the metal body and the resin body. The molding shrinkage rate of the adhesive layer is 1.5% or less. The spring constant of the adhesive layer is 3.0 to 20.0 N / mm. Laminated structure.

2. A laminate in which a metal body and a resin body are joined together, An adhesive layer containing a thermoplastic resin or thermoplastic elastomer is provided between the metal body and the resin body. The molding shrinkage rate of the adhesive layer is 1.5% or less. The tensile shear strength of the adhesive layer at 80°C is 1.0 MPa or more. Laminated structure.

3. A laminate in which a metal body and a resin body are joined together, An adhesive layer containing a thermoplastic resin or thermoplastic elastomer is provided between the metal body and the resin body. The molding shrinkage rate of the adhesive layer is 1.5% or less. The complex modulus E* of the adhesive layer at 70°C is 30 to 150 MPa. Laminated structure.

4. The laminate according to any one of claims 1 to 3, wherein the thickness of the adhesive layer is 20 to 200 μm.

5. The laminate according to any one of claims 1 to 4, wherein the thermoplastic elastomer is a thermoplastic polyamide elastomer.

6. The laminate according to any one of claims 1 to 5, wherein the resin body is a thermoplastic polyester elastomer, a thermoplastic polyamide elastomer, or a thermoplastic polyurethane elastomer.

7. The laminate according to any one of claims 1 to 6, wherein the metal body has an uneven surface on the first surface that contacts the adhesive layer.

8. An airless tire comprising a laminate in which a metal body and a resin body are joined, The laminated body is An adhesive layer containing a thermoplastic resin or thermoplastic elastomer is provided between the metal body and the resin body. The molding shrinkage rate of the adhesive layer is 1.5% or less. Airless tires.

9. A hub portion fixed to the axle, A ring-shaped tread ring for contact with the ground, It includes a spoke portion that connects the hub portion and the tread ring, The metal body forms the hub portion, The resin body forms the spoke portion, as described in claim 8 of the airless tire.

10. A method for manufacturing a laminate according to any one of claims 1 to 7, A step of melting the thermoplastic resin or thermoplastic elastomer for forming the adhesive layer, A step of bringing the molten thermoplastic resin or thermoplastic elastomer into contact with the metal body, A step of melting the resin for forming the aforementioned resin body, A step of bringing a liquid resin into contact with the thermoplastic resin or thermoplastic elastomer that is in contact with the metal body, The process includes curing the thermoplastic resin or thermoplastic elastomer and the resin to bond the metal body and the resin body via the adhesive layer, A method for manufacturing laminates.

11. The method for manufacturing a laminate according to claim 10, further comprising the step of forming an uneven surface on the first surface which is intended to come into contact with the adhesive layer, prior to the step of bringing it into contact.

12. A method for manufacturing an airless tire according to claim 9, A step of melting the thermoplastic resin or thermoplastic elastomer for forming the adhesive layer, A step of bringing the molten thermoplastic resin or thermoplastic elastomer into contact with the hub portion made of the metal body, A step of melting the resin for forming the spoke portion, A step of bringing a liquid resin into contact with the thermoplastic resin or thermoplastic elastomer that is in contact with the hub portion, The process includes curing the thermoplastic resin or thermoplastic elastomer and the resin to join the hub portion and the spoke portion. A method for manufacturing airless tires.

13. The method for manufacturing an airless tire according to claim 12, further comprising the step of forming an uneven surface on the first surface of the hub portion that is intended to come into contact with the adhesive layer, prior to the step of making contact.

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