Resin composition and use thereof

Abstract

To provide a resin composition suitable for use in footwear parts including soles, enabling production of a foam having an excellent balance of rebound elasticity and durability without performing crosslinking, and also to provide a foam containing the resin composition, and a laminate, footwear, and footwear parts employing the foam.SOLUTION: A resin composition comprises a polyether block amide (A) and an acid-modified ethylene-based polymer (B).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel resin composition suitable for producing foams, blow-molded articles, and the like, and to a foam, laminate, footwear, and footwear part containing the resin composition. [Background technology]

[0002] Footwear and footwear components, specifically the soles (mainly midsoles) of sports shoes and other such products, are required to be lightweight, resist deformation over long periods of use, and have the mechanical strength and resilience to withstand harsh conditions of use. For these reasons, cross-linked resin foams are used.

[0003] Traditionally, cross-linked foams made by peroxide cross-linking ethylene-vinyl acetate copolymer (EVA), a copolymer of ethylene and a polar monomer, have been widely used for shoe soles. Cross-linked foams made using this ethylene-vinyl acetate copolymer have a relatively high specific gravity and large compression set. Therefore, when used for shoe soles, for example, they are heavy, and over time, the sole becomes compressed, causing a loss of mechanical strength, such as rebound resilience. Therefore, in order to further improve the compression set and mechanical strength of ethylene-vinyl acetate copolymer-based foams, attempts have been made to blend them with polyolefin rubbers, such as ethylene-1-butene rubber (EBR) and ethylene-octene rubber (EOR), which have better cross-linking efficiency than ethylene-vinyl acetate copolymer.

[0004] Furthermore, since it is known that materials with lower crystallinity have better impact resilience, when particularly high impact resilience is required, blends of ethylene-vinyl acetate copolymer (EVA) and ethylene-propylene-diene copolymer (EPDM) have been attempted. However, this has problems with insufficient heat shrinkability and mechanical strength, and it has sometimes been necessary to supplement the mechanical strength by adding a highly crystalline polyolefin rubber.

[0005] On the other hand, block copolymers, such as polyether block amide (PEBA), which has both polyamide and polyether blocks in its molecule, are sometimes used in shoe sole foams. Conventional ethylene-vinyl acetate copolymers and polyolefin rubbers require peroxide crosslinking due to their large compression set, but the polyether block amide foams are flexible yet have a high melting point, allowing them to be used in shoe soles without crosslinking with peroxides. Patent Document 1 describes a non-crosslinkable foamable composition using a polyether block amide. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2020-506275 Summary of the Invention [Problem to be solved by the invention]

[0007] However, even in the non-crosslinked foamable composition containing PEBA described in Patent Document 1 and the like, further durability may be required. An object of the present invention is to provide a resin composition that is suitable for use in footwear parts such as soles and that can be used to produce a foam that has a good balance of excellent impact resilience and durability even without crosslinking; a foam containing the resin composition; and a laminate, footwear, and footwear part that use the foam. [Means for solving the problem]

[0008] The present invention relates to, for example, the following. [1] a polyether block amide (A); Acid-modified ethylene polymer (B) A resin composition comprising:

[0009] [2] The resin composition according to [1], wherein the acid-modified ethylene polymer (B) satisfies all of the following requirements (b-1), (b-2), and (b-3): (b-1) The degree of acid modification is in the range of 0.5 to 3.0% by mass. (b-2) The melt flow rate (MFR) measured in accordance with ASTM D1238 at 190°C under a load of 2.16 kg is in the range of 0.05 to 100 g / 10 min. (b-3) Density (ASTM D1505) 850 to 975 kg / m 3 is in the range. [3] per 100 parts by mass of the total of the polyether block amide (A) and the acid-modified ethylene polymer (B), the content of the polyether block amide (A) is 50 to 99 parts by mass, the content of the acid-modified ethylene polymer (B) is 1 to 50 parts by mass, The resin composition according to [1] or [2],

[0010] [4] A foam comprising the resin composition according to any one of [1] to [3]. [5] The foam according to [4], wherein the specific gravity of the foam is 0.3 or less.

[0011] [6] A layer made of the foam according to [4] or [5]; a layer made of at least one material selected from the group consisting of polyolefin, polyurethane, rubber, leather, and artificial leather; A laminate having:

[0012] [7] Footwear comprising the resin composition according to any one of [1] to [3] or the foam according to [4] or [5]. [8] A footwear part comprising the resin composition according to any one of [1] to [3] or the foam according to [4] or [5]. [9] The footwear component according to [8], which is a midsole, insole or sole.

Advantages of the Invention

[0013] According to the present invention, there can be provided a resin composition capable of producing a foam that is suitable for use in footwear components such as soles and is excellent in balance between resilience and durability even without crosslinking, a foam containing the resin composition, a laminate using the foam, footwear, and footwear components.

Embodiments for Carrying out the Invention

[0014] Hereinafter, the present invention will be specifically described. Here, in this specification, "~" indicating a numerical range means "not less than M and not more than N" when expressed as, for example, "M~N" (where M and N are numerical values satisfying M < N), unless otherwise specified. Also, in this specification, when an olefin constituting a certain polymer is denoted as M, the expression "structural unit derived from M" may be used, which means "structural unit corresponding to M", that is, a structural unit having a pair of bonds formed by opening the π bond constituting the double bond of M. For example, "structural unit derived from ethylene" means a structural unit represented by -CH2-CH2-, and "structural unit derived from α-olefin" specifically means a structural unit represented by -CH2-CRR'- (where R and R' are each independently a hydrogen atom or an alkyl group). In this specification, "~" indicating a numerical range means that the unit described on either side thereof indicates the same unit unless otherwise specified. In this specification, when referring to the amount of each component in a composition, in the case where there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the plurality of substances present in the composition.

[0015] ≪Resin Composition≫ The resin composition of the present invention contains a polyether block amide (A) and an acid-modified ethylene-based polymer (B).

[0016] <Polyether block amide (A)> The polyether block amide (A) (hereinafter also referred to simply as "component (A)") contained in the resin composition of the present invention is not particularly limited, and various known polyether block amide resins can be used without limitation as long as the effects of the present invention are not impaired. For example, a polyether block amide resin obtained by a polycondensation reaction between a polyamide block having a dicarboxylic acid chain terminal and a polyoxyalkylene block having a diamine chain terminal can be used.

[0017] The polyamide block is preferably an aliphatic polyamide, more preferably polyamide 6, polyamide 66, polyamide 69, polyamide 610, polyamide 612, polyamide 11, or polyamide 12, and the polyoxyalkylene block is preferably polyethylene glycol, polypropylene glycol, or polytetramethylene glycol, more preferably polyethylene glycol or polytetramethylene glycol.

[0018] The Shore D hardness (measured in accordance with ASTM D2240) of the component (A) contained in the resin composition of the present invention is preferably 60 or less from the viewpoint of flexibility of the foam, and more preferably in the range of 20 to 50 from the viewpoint of the balance between flexibility and mechanical strength of the foam. The component (A) used in the resin composition of the present invention may be one type or two or more types. The polyamide block and polyoxyalkylene block constituting component (A), or their monomers, can be derived from either fossil fuels or biomass. Also, fossil fuels and biomass-derived raw materials can be used in combination.

[0019] The content of component (A) in the resin composition of the present invention is preferably 50 to 99 parts by mass, more preferably 60 to 95 parts by mass, and even more preferably 65 to 90 parts by mass, per 100 parts by mass of the total of the polyether block amide (A) and the acid-modified ethylene polymer (B). As the polyether block amide (A) of component (A), a commercially available product may be used, and examples of commercially available products include Pebax (registered trademark) manufactured by Arkema, VESTAMID (registered trademark) manufactured by Polypla-Evonik, and UBESTA XPA manufactured by UBE.

[0020] <Acid-modified ethylene polymer (B)> The resin composition of the present invention contains an acid-modified ethylene polymer (B) (hereinafter also referred to simply as "component (B)"). A foam obtained from a resin composition containing component (B) has a good balance of excellent impact resilience and durability.

[0021] The component (B) used in the present invention is obtained by acid-modifying an ethylene-based polymer. The ethylene-based polymer before acid-modification is a polymer or copolymer mainly containing structural units derived from ethylene, such as an ethylene homopolymer or a copolymer of ethylene and an α-olefin (ethylene-α-olefin copolymer).

[0022] Specific examples of α-olefins include propylene, 1-butene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, trimethyl-1-butene, ethyl-1-pentene, 1-octene, methyl-1-pentene, and dimethyl-1-hexene. Examples of α-olefins include α-olefins having 3 to 20 carbon atoms, such as propylene, trimethyl-1-pentene, ethyl-1-hexene, methylethyl-1-pentene, diethyl-1-butene, propyl-1-pentene, 1-decene, methyl-1-nonene, dimethyl-1-octene, trimethyl-1-heptene, ethyl-1-octene, methylethyl-1-heptene, diethyl-1-hexene, 1-dodecene, 1-hexadecene, and 1-octadecene. Two or more of these α-olefins may be used in combination. Among the above α-olefins, α-olefins having 3 to 10 carbon atoms are preferred, with propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene being more preferred, and 1-butene being even more preferred.

[0023] Furthermore, when the ethylene-based polymer is an ethylene-α-olefin copolymer, the ethylene-α-olefin copolymer contains structural units derived from ethylene in an amount of usually 70 to 95 mol %, preferably 75 to 95 mol %, and structural units derived from an α-olefin having 3 to 20 carbon atoms in an amount of usually 5 to 30 mol %, preferably 5 to 25 mol %. The total of the structural units derived from ethylene and the structural units derived from the α-olefin is 100 mol %. The content of the structural units derived from ethylene and the content of the structural units derived from the α-olefin are 13 It can be calculated by analyzing the spectrum obtained by C-NMR measurement.

[0024] Ethylene and α-olefin, which are monomers constituting the ethylene-based polymer before acid modification, may be fossil fuel-derived monomers, biomass-derived monomers, or a combination of fossil fuel-derived monomers and biomass-derived monomers.

[0025] The component (B) according to the present invention can be obtained, for example, by graft polymerizing an acid component (e.g., maleic acid or its anhydride) onto the ethylene polymer before acid modification in the presence of a radical initiator. At this time, additives described below may be added as needed. The ethylene polymer may be granulated in advance by a melt-kneading method. Alternatively, the acid component may be graft polymerized onto the ethylene polymer in the presence of a radical initiator using an extruder without a solvent. The graft polymerization reaction is preferably carried out for 0.5 to 10 minutes at a temperature equal to or higher than the melting point of the ethylene polymer. The acid component (for example, maleic acid or its anhydride) may be a fossil fuel-derived monomer, a biomass-derived monomer, or a combination of a fossil fuel-derived monomer and a biomass-derived monomer.

[0026] The amount of the acid component is usually 0.01 to 15 parts by mass, preferably 0.01 to 5 parts by mass, based on 100 parts by mass of the ethylene polymer before acid modification. The amount of the radical initiator used is usually 0.001 to 1 part by mass, preferably 0.001 to 0.3 part by mass, based on 100 parts by mass of the ethylene polymer before acid modification.

[0027] Examples of the radical initiator that can be used include organic peroxides, azo compounds, and metal hydrides. The radical initiator may be used by directly mixing with the acid component and the polyethylene before acid modification, or may be used by dissolving in a small amount of an organic solvent.

[0028] The acid-modified ethylene polymer (B) of the component (B) preferably satisfies one or more of the following requirements (b-1) to (b-3), and more preferably satisfies all of the following requirements (b-1) to (b-3).

[0029] Requirement (b-1): The acid-modified ethylene polymer (B) has an acid modification degree (amount of acid component grafted) of 0.5 to 3.0 mass %, preferably 0.5 to 2.8 mass %, more preferably 0.7 to 2.8 mass %, and even more preferably 0.7 to 2.6 mass %. The degree of acid modification is the acid content in the acid-modified ethylene polymer (B). For example, when the acid-modified ethylene polymer (B) is a polymer obtained by graft-modifying an ethylene polymer before acid modification with maleic anhydride, the degree of acid modification means the proportion expressed as the amount of maleic anhydride grafted, and is expressed as the wave number of 1780 cm assigned to the carbonyl group in FT-IR. -1 It is calculated from a calibration curve prepared based on peak intensity.

[0030] When the acid-modification degree is equal to or greater than the lower limit of the above range, foams or molded articles obtained from resin compositions containing the same tend to have excellent tensile strength, tensile elongation, etc., which is preferable. On the other hand, when the acid-modification degree exceeds the upper limit of the above range, reactions with components other than component (B) proceed, which may reduce the fluidity of the resin composition, resulting in reduced foamability and moldability, or may cause gel formation, impairing the appearance of foams or molded articles. When the acid-modification degree of the acid-modified ethylene polymer (B) satisfies the above range, resin compositions containing the same will have excellent foamability, moldability, and the appearance of foams or molded articles.

[0031] Requirement (b-2): The acid-modified ethylene polymer (B) preferably has a melt flow rate (MFR) of 0.05 to 100 g / 10 min, as measured in accordance with ASTM D1238 at 190°C under a load of 2.16 kg. This MFR is preferably 0.05 to 50 g / 10 min, and more preferably 0.05 to 20 g / 10 min. If the MFR of component (B) falls within the above range, it is preferred because the resin composition containing it will have appropriate foamability and moldability.

[0032] Requirement (b-3): The density of the acid-modified ethylene polymer (B), measured in accordance with ASTM D1505, is 850 to 975 kg / m 3 and preferably 860 to 970 kg / m 3 is. For example, when the resin composition is used to produce a foam that requires flexibility and impact resilience, the density of component (B) is 850 kg / m 3 More than 900kg / m 3 It is preferably in the range of less than 860 to 880 kg / m 3 Furthermore, for example, when the resin composition is used to produce a foam or molded article that requires mechanical properties, the density of component (B) is 900 kg / m 3 More than 975kg / m 3 It is preferably in the range of less than 910 to 970 kg / m 3 is.

[0033] The content of component (B) in the resin composition of the present invention is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, and even more preferably 10 to 35 parts by mass, per 100 parts by mass of the total of the polyether block amide (A) and the acid-modified ethylene polymer (B). In this specification, the polyether block amide (A) and the acid-modified ethylene polymer (B) may be collectively referred to as the "polymer component."

[0034] <Optional ingredients> The resin composition of the present invention may contain optional components other than the aforementioned components (A) and (B) as needed, provided that the object of the present invention is not impaired, such as a foaming agent, a foaming aid, a crosslinking agent, a crosslinking aid, a filler, a heat stabilizer, a weather stabilizer, a flame retardant, a hydrochloric acid absorber, a pigment, a polymer other than the aforementioned components (A) and (B), etc. Optional components include known additives that can be added to olefin resins. When optional components are used, the resin composition of the present invention may contain one or more types of each optional component.

[0035] <Production of Resin Composition> The resin composition of the present invention can be prepared by mixing the above-mentioned components sequentially or simultaneously by a known method. The resin composition of the present invention is also preferably in the form of pellets, sheets, or the like.

[0036] Pellets of the resin composition of the present invention can be produced by mixing the above-mentioned components (A), (B), and optional components used as needed in the aforementioned ratios using a Henschel mixer or the like, melt-plasticizing the mixture at an appropriate temperature using a kneader such as a Banbury mixer, roll, or extruder, uniformly mixing and dispersing the mixture, and then granulating the mixture using a granulator. When the resin composition of the present invention contains a chemical foaming agent as a foaming agent, it is desirable to melt-plasticize the mixture at a temperature at which the chemical foaming agent does not decompose.

[0037] The sheet of the resin composition of the present invention can be produced, for example, by molding the pellets obtained as described above into a sheet using an extruder or a calendar molding machine. Alternatively, the resin composition sheet can be produced by kneading the components constituting the resin composition of the present invention with a Brabender or the like and then molding them into a sheet using a calendar roll, forming them into a sheet using a press molding machine, or kneading them using an extruder and then passing them through a T-die or annular die or the like to form a sheet. When the resin composition of the present invention contains a chemical foaming agent as a foaming agent, the sheet is preferably formed at a temperature equal to or lower than the decomposition temperature of the chemical foaming agent. Specifically, the sheet is preferably formed under temperature conditions that allow the resin component to be in a molten state.

[0038] The resin composition of the present invention can be used in various molding applications such as injection molding and foam molding, and can also be suitably used for producing foams.

[0039] <Foam> The foam according to the present invention is a foam obtained by foaming the resin composition of the present invention, and can be produced by foaming the resin composition of the present invention, typically polymer components such as the polyether block amide (A) and the acid-modified ethylene polymer (B). This foaming is typically carried out using a foaming agent. The foam may be a non-crosslinked foam or a crosslinked foam, but the foam of the present invention is suitable for producing a non-crosslinked foam.

[0040] The foam containing the resin composition of the present invention is produced by expanding the resin composition of the present invention with a gas. Representative methods for expanding the resin composition of the present invention include physical foaming and chemical foaming.

[0041] Physical foaming is a method for foaming a resin material by dissolving a gas or supercritical fluid in a resin material such as the resin composition of the present invention under high pressure, and then reducing the pressure or heating to reduce the solubility of the gas or the like, thereby generating bubbles. Here, the gas or supercritical fluid used in physical foaming is called a physical foaming agent (D).

[0042] On the other hand, chemical foaming is a method of foaming a resin material by compounding a chemical substance that generates gas through a chemical reaction with a resin material such as the resin composition of the present invention, and generating bubbles with the gas generated by the chemical reaction of the chemical substance. Here, the chemical substance used in chemical foaming is called a chemical foaming agent (D'). Examples of chemical foaming agents (D') include organic chemical foaming agents such as azodicarbonamide (ADCA) and inorganic chemical foaming agents such as baking soda.

[0043] While the molding temperature for chemical foaming is limited by the reaction temperature of the chemical foaming agent used, physical foaming does not require reactive additives, allowing for molding at higher temperatures than chemical foaming. This makes it possible to foam-mold high-melting-point materials that are difficult to apply chemical foaming to. Therefore, it is suitable for foaming materials containing thermoplastic polyurethane (TPU), PEBA, etc. PEBA in particular has excellent rebound resilience, and materials containing PEBA are increasingly being used as foams for footwear. For these reasons, it is preferable to include a physical foaming agent (D) as a foaming agent when producing a foam containing the resin composition of the present invention.

[0044] <Physical foaming agent (D)> The physical foaming agent (D) is a substance that generates bubbles in a polymer component, such as the polyether block amide (A) and the acid-modified ethylene polymer (B), by utilizing the temperature- and / or pressure-dependent change in solubility in the polymer component, and does not necessarily involve a chemical reaction during foaming.

[0045] Examples of the physical blowing agent (D) include organic physical blowing agents such as various aliphatic hydrocarbons such as methanol, ethanol, propane, butane, pentane, and hexane; various chlorinated hydrocarbons such as dichloroethane, dichloromethane, and carbon tetrachloride; and various fluorochlorohydrocarbons such as chlorofluorocarbons, as well as inorganic physical blowing agents such as air, carbon dioxide, nitrogen, argon, and water. Among these, carbon dioxide, nitrogen, and argon are excellent because they do not need to be converted into steam, are inexpensive, and have extremely low environmental pollution and ignition potential, and of these, carbon dioxide and nitrogen are particularly excellent.

[0046] The physical blowing agent (D) can often be used in the form of a gas. The physical blowing agent (D) may also be used in the form of a supercritical fluid to ensure sufficient solubility in polymer components such as the polyether block amide (A) and the acid-modified ethylene polymer (B). Carbon dioxide has a critical pressure of 7.38 MPa and a critical temperature of 31.1°C, while nitrogen has a critical pressure of 3.40 MPa and a critical temperature of -147.1°C, making it relatively easy to convert it into a supercritical fluid.

[0047] When a physical foaming agent (D) is used as the foaming agent in producing the foam of the present invention, the resulting foam contains no decomposition residue of the foaming agent. This prevents mold contamination during foaming of the resin composition. Moreover, since the physical foaming agent is not powdery, it has excellent kneadability. Furthermore, the use of this physical foaming agent prevents the resulting foam from having an unpleasant odor (such as the ammonia odor produced during the decomposition of azodicarbonamide (ADCA)).

[0048] As a method of storing the physical blowing agent (D), in the case of small-scale production, carbon dioxide, nitrogen, etc. can be used in a cylinder and supplied to an injection molding machine, an extrusion molding machine, etc. through a pressure reducing valve, or the pressure can be increased by a pump or the like and supplied to an injection molding machine, an extrusion molding machine, etc.

[0049] In addition, in facilities for manufacturing foamed products on a large scale, storage tanks for liquefied carbon dioxide, liquefied nitrogen, etc. are installed, and the liquefied carbon dioxide, liquefied nitrogen, etc. are vaporized through a heat exchanger, and then supplied to injection molding machines, extrusion molding machines, etc. through piping and pressure reducing valves.

[0050] When a liquid physical blowing agent is used as the physical blowing agent (D), the storage pressure is preferably in the range of 0.13 to 100 MPa. When a physical foaming agent (D) is used, the amount of the physical foaming agent (D) added is determined appropriately depending on the desired expansion ratio, but is usually 0.1 to 15 parts by mass, and preferably 0.5 to 10 parts by mass, per 100 parts by mass of the total of the polyether block amide (A) and the acid-modified ethylene polymer (B).

[0051] The chemical foaming agent (D') is a chemical substance that generates gas by thermal decomposition or other chemical reaction. Examples of the chemical foaming agent (D') include: azo compounds such as azodicarbonamide (ADCA), 1,1'-azobis(1-acetoxy-1-phenylethane), dimethyl-2,2'-azobisbutyrate, dimethyl-2,2'-azobisisobutyrate, 2,2'-azobis(2,4,4-trimethylpentane), 1,1'-azobis(cyclohexane-1-carbonitrile), and 2,2'-azobis[N-(2-carboxyethyl)-2-methyl-propionamidine]; Nitroso compounds such as N,N'-dinitrosopentamethylenetetramine (DPT); hydrazine derivatives such as 4,4'-oxybis(benzenesulfonylhydrazide) and diphenylsulfone-3,3'-disulfonylhydrazide; Semicarbazide compounds such as p-toluenesulfonylsemicarbazide; organic thermal decomposition type blowing agents such as trihydrazinotriazine; Examples of inorganic thermal decomposition type foaming agents include bicarbonates such as sodium hydrogen carbonate and ammonium hydrogen carbonate, carbonates such as sodium carbonate and ammonium carbonate, nitrites such as ammonium nitrite, and hydrogen compounds. Among these, azodicarbonamide (ADCA) tends to be widely used as the chemical foaming agent (D') because it generates a large amount of gas during thermal decomposition.

[0052] When a chemical foaming agent (D') is used as the foaming agent, a foaming assistant may be used in combination with the chemical foaming agent (D'). The foaming assistant acts to lower the decomposition temperature of the chemical foaming agent (D'), promote decomposition, and homogenize the bubbles. Examples of such foaming assistants include zinc oxide (ZnO), zinc stearate, organic acids such as salicylic acid, phthalic acid, stearic acid, and oxalic acid, and urea or its derivatives.

[0053] However, when a foam is produced using azodicarbonamide (ADCA) or the like as a blowing agent, the resulting foam may emit an odor (off-odor) derived from the blowing agent, such as the ammonia odor generated upon decomposition of ADCA. The presence of such an odor (off-odor) is undesirable for use in footwear and footwear components. Furthermore, when ADCA or the like is used as a blowing agent, problems such as discoloration may occur in the resulting foam, which is undesirable from the viewpoint of aesthetics, etc. Therefore, in the present invention, a chemical blowing agent (D') is not typically used.

[0054] <Optional ingredients> The foam of the present invention may contain optional components other than the above-mentioned components as needed, provided that the object of the present invention is not impaired, such as various additives such as a crosslinking agent, a crosslinking aid, a filler, a heat stabilizer, a weather stabilizer, a flame retardant, a hydrochloric acid absorbent, a pigment, etc. Examples of optional components include known additives that can be added to olefin resins. When optional components are used, the foam of the present invention may contain one or more optional components.

[0055] <Foam manufacturing> The foam of the present invention is not particularly limited, and can be produced, for example, by the following method using the resin composition obtained by the present invention, the above-mentioned foaming agent, and, if necessary, optional components.

[0056] The resin composition of the present invention can be obtained by a production method including a step of physically foaming the resin composition. The physically foaming step may be carried out by first impregnating the resin composition of the present invention in a gaseous physical foaming agent under pressure, and then releasing the pressure. Alternatively, the physically foaming step may be carried out by impregnating the resin composition of the present invention in a supercritical fluid.

[0057] When a supercritical fluid is used as the physical foaming agent (D), the physical foaming step includes, for example, a step (SC1) of impregnating the resin composition of the present invention with a supercritical fluid, and a step (SC2) of injecting the mixture obtained in the step (SC1) into a mold, depressurizing the mixture to foam it, and cooling and solidifying it in the mold. The temperature and pressure for carrying out step (SC1) are not particularly limited as long as the physical foaming agent (D) is in a supercritical fluid state, but may be, for example, 100 to 300°C and 100 to 300 bar (i.e., 10 to 30 MPa). On the other hand, the temperature and pressure for carrying out step (SC2) are set to be lower than the pressure for carrying out step (SC1), for example, 1 to 50 bar (i.e., 0.1 to 5.0 MPa). The mold temperature for carrying out step (SC2) is, for example, 5 to 60°C.

[0058] The foam obtained as described above may be used as a primary foam as it is, or the foam may be subjected to compression molding to give a predetermined shape to produce a secondary foam, for example, under compression molding conditions of a mold temperature of 130 to 200°C and a mold clamping pressure of 30 to 300 kgf / cm. 2 The compression time is 5 to 60 minutes, and the compression ratio is in the range of 1.1 to 3.0. Among the above-mentioned production methods, it is preferable to obtain a foam by heat treating the resin composition of the present invention.

[0059] Examples of the foam product shape include a sheet, a thick board, a net, and a molded product. The foam of the present invention preferably has a specific gravity of 0.3 or less, more preferably 0.03 to 0.30. Foams with such specific gravities are preferably used for laminates, footwear, or footwear components, which will be described later.

[0060] <Laminate> The laminate of the present invention is a laminate having a layer made of the foam, and preferably a laminate having a layer made of the foam and a layer made of at least one material selected from the group consisting of polyolefin, polyurethane, rubber, leather, and artificial leather.

[0061] The polyolefin, polyurethane, rubber, leather, and artificial leather are not particularly limited, and conventionally known polyolefins, polyurethanes, rubbers, leathers, and artificial leathers can be used. Such laminates are particularly suitable for use in footwear and footwear parts.

[0062] <Molded body> The molded article obtained from the resin composition of the present invention is a molded article of the resin composition of the present invention described above, and may be the foamed article described above or a non-foamed molded article. Examples of non-foamed molded articles include molded articles obtained by molding the resin composition of the present invention described above by known molding methods such as injection molding, extrusion molding, inflation molding, blow molding, extrusion blow molding, injection blow molding, press molding, vacuum molding, and calendar molding. Among these, blow molding, extrusion blow molding, and injection blow molding are preferred, and examples of preferred molded articles include blow molded articles of various shapes and bottles.

[0063] <Applications of resin compositions, foams, and laminates> The resin composition of the present invention is suitable for producing various molded articles and foamed articles, and is particularly suitable for producing non-crosslinked molded articles and non-crosslinked foamed articles, and can be used for any of the conventionally known applications without any restrictions. Specific examples of uses of the resin composition of the present invention and molded articles, foamed articles, and laminated articles made from the resin composition include automobile interior and exterior parts such as automobile interior skin materials, weatherstrip sponges, body panels, steering wheels, and side shields; civil engineering and building material parts such as ground improvement sheets, water supply boards, and noise prevention walls; industrial parts; footwear parts such as shoe soles and sandals; electric and electronic parts such as wire coating materials, connectors, and cap plugs; sports and leisure goods such as golf club grips, baseball bat grips, swimming fins, and diving goggles; and miscellaneous goods such as gaskets, waterproof cloths, garden hoses, belts, draining sheets, and cosmetic puffs. In particular, the resin composition can be suitably used as footwear parts such as shoe soles, shoe insoles, half insoles, midsoles, inner soles, and outsoles.

[0064] <Footwear and footwear parts> The footwear and footwear components according to the present invention include the foam or laminate described above. Because the footwear and footwear components include the foam or laminate described above, they are lightweight and can be prevented from deforming over long periods of use.

[0065] Examples of the footwear include shoes and sandals. Suitable examples of the footwear include sports shoes. Examples of sports shoes include shoes for track and field, marathon shoes, basketball shoes, tennis shoes, golf shoes, walking shoes, marine shoes, trekking shoes, and running shoes. Of these, running shoes are preferred.

[0066] Examples of the footwear parts include shoe soles, shoe insoles, half insoles, midsoles, innersoles, and outsoles. Suitable examples of the footwear parts include the aforementioned sports shoe parts, and more preferred are insoles, half insoles, midsoles, inner soles and outsoles for running shoes. [Example]

[0067] The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples.

[0068] [Raw materials used] The materials used in the examples and comparative examples are as follows. <Polyether block amide (A)> Polyether block amide (A-1): Polyamide 12-polytetramethylene glycol (Arkema, Pebax® 3533 SP 01) <Acid-modified ethylene polymer (B)> Acid-modified ethylene polymer (B-1): Ethylene-1-butene random copolymer modified with maleic anhydride, MFR (190°C, 2.16 kg, ASTM D1238) 2.4 g / 10 min, density (ASTM D1505) 885 kg / m 3 , the content of structural units derived from ethylene is 89 mol %, and the amount of maleic anhydride grafted is 0.5 mass % Acid-modified ethylene polymer (B-2): Ethylene-1-butene random copolymer modified with maleic anhydride, MFR (190°C, 2.16 kg, ASTM D1238) 0.6 g / 10 min, density (ASTM D1505) 866 kg / m 3 , the content of structural units derived from ethylene is 80 mol %, and the amount of maleic anhydride grafted is 1.0 mass %

[0069] [Example 1] (Preparation of Resin Composition) A dry blend was prepared by mixing 80 mass % of polyether block amide (A-1) as the polyether block amide (A) and 20 mass % of acid-modified ethylene polymer (B-1) as the acid-modified ethylene polymer (B) using a Henschel mixer. Next, this dry blend was fed into the main inlet of a twin-screw extruder (L / D=40, 30 mmφ) set at 285°C, and extruded at a screw rotation speed of 180 rpm and a discharge rate of 15 kg / hr to prepare pellets of the resin composition.

[0070] (Preparation of foam) The pellets were dried overnight at 100°C, and 100 g of the pellets were then placed in an injection molding machine equipped with a Trexel Inc. supercritical fluid (SCF) metering and supply system, "MuCell T-200." After heating and plasticizing in the cylinder, the pellets were impregnated with 1.08 g of supercritical nitrogen and injected at a speed of 66 mm / s into a mold (counter pressure 15 bar) measuring 200 mm in length, 10 mm in width, and 20 mm in thickness. The mixture was then cooled for 10 minutes to obtain a foam. The cylinder and mold temperatures during foam injection molding were as shown in Table 1.

[0071] (Measurement of foam properties) ·specific gravity The specific gravity of the foam was measured in accordance with JIS K 7222:2005. The samples used for measuring the specific gravity were taken from a location 20 mm or more inward from each of the four sides of the foam with the largest area and 2.5 mm or more inward from the surface of the foam. Samples were prepared from five locations on the foam, and the specific gravity was measured and the average was used. Asker C hardness The Asker C hardness was measured in a 23°C environment according to the "Spring Hardness Test Type C Test Method" described in Appendix 2 of JIS K 7312:1996. Compression set (CS) Compression set (CS) was measured in accordance with JIS K 6262. The foam was cut into a cylindrical shape with a diameter of 30 mm to use as a sample. A cylindrical dumbbell cutter can be used to cut foam into cylindrical shapes and to cut foam from parallel plane surfaces. The sample was compressed to 50% and left at 50°C for 6 hours, and then measured 30 minutes after release from compression. The compression set (CS) (%) was calculated using the following formula: CS=(t0-t1) / (t0-t2)×100 t0: sample thickness (mm) t1: Thickness (mm) 30 minutes after removing the sample from the compression device t2: Spacer thickness (mm) Rebound elasticity The rebound resilience was measured in accordance with JIS K 6255: 2013. The samples used were prepared in the same manner as the samples used for the compression set (CS) below, and the measurement was carried out in an atmosphere at 23°C.

[0072] [Example 2] A foam was produced and its physical properties were measured in the same manner as in Example 1, except that the content of polyether block amide (A-1) was changed to 90% by mass, and the content of acid-modified ethylene-based polymer (B-1) was changed to acid-modified ethylene-based polymer (B-2), and its content was changed to 10% by mass.

[0073] [Comparative Example 1] A foam was produced and its physical properties were measured in the same manner as in Example 1, except that the acid-modified ethylene polymer (B) was not used and the polyether block amide (A-1) was used in an amount of 100% by mass.

[0074] [Table 1]

[0075] The above examples and comparative examples demonstrate that when the resin composition of the present invention containing the polyether block amide (A) and the acid-modified ethylene polymer (B) is used, the compression set, which is an index of durability, tends to be superior without sacrificing rebound resilience and flexibility, compared to Comparative Example 1, which consists of only the polyether block amide (A). [Industrial Applicability]

[0076] The resin composition of the present invention is suitable for producing various molded articles, particularly foamed articles, and can be used for any of the conventionally known applications without any restrictions. Specific examples of uses of the resin composition of the present invention, and molded articles, foams, and laminates using the composition, include automotive interior and exterior parts such as automotive interior skin materials, weatherstrip sponges, body panels, steering wheels, and side shields; civil engineering and building material parts such as ground improvement sheets, water supply boards, and noise prevention walls; industrial parts; footwear parts such as shoe soles and sandals; electric and electronic parts such as wire coating materials, connectors, and cap plugs; sports and leisure goods such as golf club grips, baseball bat grips, swimming fins, and diving goggles; and miscellaneous goods such as gaskets, waterproof cloths, garden hoses, belts, draining sheets, and cosmetic puffs. In particular, the composition can be suitably used as footwear parts such as shoe soles, shoe insoles, half insoles, midsoles, inner soles, and outsoles.

Claims

1. a polyether block amide (A); an acid-modified ethylene polymer (B); A resin composition comprising:

2. The resin composition according to claim 1, wherein the acid-modified ethylene polymer (B) satisfies all of the following requirements (b-1), (b-2) and (b-3): (b-1) The degree of acid modification is in the range of 0.5 to 3.0% by mass. (b-2) The melt flow rate (MFR) measured in accordance with ASTM D1238 at 190°C under a load of 2.16 kg is in the range of 0.05 to 100 g / 10 min. (b-3) Density (ASTM D1505) 850 to 975 kg / m 3 is in the range.

3. per 100 parts by mass of the total of the polyether block amide (A) and the acid-modified ethylene polymer (B), the content of the polyether block amide (A) is 50 to 99 parts by mass, the content of the acid-modified ethylene polymer (B) is 1 to 50 parts by mass, The resin composition according to claim 1,

4. A foam comprising the resin composition according to any one of claims 1 to 3.

5. 5. The foam according to claim 4, wherein the specific gravity of the foam is 0.3 or less.

6. A layer made of the foam according to claim 4; a layer made of at least one material selected from the group consisting of polyolefin, polyurethane, rubber, leather, and artificial leather; A laminate having:

7. Footwear comprising the foam of claim 4.

8. A footwear component comprising the foam of claim 4.

9. The footwear part according to claim 8, which is a midsole, an innersole, or a sole.

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