Foam and article using the same

Abstract

To provide a foam which is especially suitable for shoe midsoles, other types of sport foam pads, or daily necessities.SOLUTION: A foam is obtained by foaming a resin composition, which comprises a hydroxyl-terminated hydrogenated styrenic block copolymer of (A-B)n-OH, (B-A)n-OH, A(B-A)n-OH, or B(A-B)n-OH having a hydroxyl group at the terminal; where the A block comprises a styrene monomer unit and the B block comprises a conjugated diene monomer unit. The hydroxyl-terminated hydrogenated styrenic block copolymer comprises 10-60 wt.% of the styrene monomer unit; and 40 mol% or more of the conjugated diene monomer unit is hydrogenated. The hydrogenated styrenic block copolymer has a weight average molecular weight of about 30000 to about 200000. The 1,2-vinyl bond content in the conjugated diene monomer unit of the hydroxyl-terminated hydrogenated styrenic block copolymer is in the range of 5 to 60 mol% prior to the hydrogenation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119(e)(1) of the filing date of U.S. Provisional Patent Application No. 63 / 596395, filed November 6, 2023, and U.S. Provisional Patent Application No. 63 / 596400, filed November 6, 2023.

[0002] The present invention provides a foam that is particularly suitable for shoe midsoles, other types of sports foam padding, or everyday items. [Background technology]

[0003] Ethylene copolymers, such as ethylene vinyl acetate (EVA), are widely used to make foam products for footwear applications in a process that involves first incorporating a peroxide initiator and a chemical blowing agent at a temperature of about 120°C or less, then molding the resin composition in a mold to crosslink it, and then foaming it at a temperature of about 140°C to 190°C. Ethylene-α-olefin copolymers are also used in footwear foam applications. For example, U.S. Patent No. 5,407,965 disclosed a crosslinked, substantially linear ethylene copolymer composition for foam applications. U.S. Patent No. 7,666,918 disclosed a foamable composition, the foam comprising an ethylene / α-olefin copolymer having multiple blocks of soft and hard blocks. Blends of ethylene copolymers are also used to make lightweight foams to balance foam properties.

[0004] Thermoplastic elastomers (TPEs), such as thermoplastic polyurethanes (TPUs), thermoplastic polyetherester elastomers (TPEEs), and polyether block amides (PEBAs), are another category of materials suitable for producing lightweight foams, such as footwear foam. TPEs behave like thermoset rubbers but are melt-processable like thermoplastics. They consist of two phases: a soft phase that provides elastic properties and a hard phase that cohere to form a physical crosslinked network. Selected compositions of TPEs can have the inherent melt strength to expand without crosslinking, and the resulting foams have desirable foam properties. Generally, current foaming processes for producing EVA foam cannot produce foams from TPE materials, such as thermoplastic polyurethanes. For example, European Patent No. 3259306 discloses a process for producing expanded thermoplastic polyurethane particles containing an impregnated physical blowing agent, such as nitrogen, that expand into bead foam.

[0005] Styrenic block copolymers (SBCs) are a category of TPE suitable for producing lightweight foams in conventional footwear foam processes. To produce SBC-based foams, peroxide crosslinking is required to obtain the melt strength required for foaming. SBCs with glass transition temperatures of approximately 100°C can be processed at temperatures below 120°C to incorporate peroxides and chemical blowing agents, and the soft blocks, i.e., butadiene and / or isoprene chemical structures and their hydrides, can be crosslinked with peroxide initiators. For optimal crosslinking with peroxides, partially hydrogenated forms are preferred. Therefore, partially hydrogenated styrene block copolymers, such as SEBS, have been used in footwear foams, particularly to modify ethylene copolymers to achieve improved properties such as rebound resilience.

[0006] Despite advances in the application of SBCs for foam applications, there remains a need to explore new SBC compositions to further enhance their broad suitability for foam applications, particularly footwear foam applications. For example, U.S. Patent Application Publication No. 2022 / 0380566 discloses foams based on hydrogenated styrene diblock copolymers that exhibit improved processability and high resilience. Foams based on hydrogenated SBCs are non-polar polymers primarily containing hydrogenated butadiene blocks, which can reduce their ability to bond with other footwear components that use environmental primers and adhesives in shoe manufacturing. It is also worth exploring novel blend compositions containing SBCs that provide differentiated foaming performance and meet diverse needs for footwear foam applications. Summary of the Invention

[0007] An object of the present invention is to provide a hydroxyl-terminated hydrogenated styrene block copolymer that is suitable for use in footwear foam applications, as seen in the following aspects:

[0008] The first aspect is that hydroxyl-terminated hydrogenated block copolymers in foam form have excellent bonding capabilities with other footwear components. Because the durability of a shoe directly depends on the quality of the bonding process for those components, careful attention must be paid to the adhesion of foam components to other parts of the shoe. Soft styrene block copolymers, such as SEBS, suitable for footwear foam applications have a high content of non-polar ethylene-butylene units. The adhesive capabilities of styrene block copolymer-based foams can be a concern that limits their use. Hydroxyl-terminated hydrogenated block copolymers achieve excellent adhesive capabilities without compromising the foam.

[0009] The second aspect is that the hydroxyl-terminated hydrogenated styrene block copolymers act as blending partners with other widely used foaming resins, such as ethylene-based copolymers and polar thermoplastic elastomers. To meet the ever-expanding performance requirements of footwear foams, blending different foaming resins with different chemistries is primarily used to achieve key properties. The hydroxyl-terminated hydrogenated styrene block copolymers provide additional synergistic effects when blended with other foaming resins.

[0010] A third aspect is that the hydroxyl-terminated hydrogenated styrene block copolymer can achieve improved compatibility with other polar polymers in the resin composition by reacting its terminal hydroxyl groups with at least one functional group selected from the group consisting of anhydride, epoxy, and isocyanate. This interaction also enhances the dispersion of additives such as fillers, crosslinking coagents, or functional chain extenders.

[0011] Without being bound by theory, the present invention is based on the discovery that a hydroxyl-terminated hydrogenated styrene block copolymer is optimal for achieving the above-mentioned objectives of the present invention.

[0012] According to the object of the present invention, the present invention discloses a hydroxyl-terminated hydrogenated styrene block copolymer, a foam containing the hydroxyl-terminated hydrogenated styrene block copolymer, a resin composition containing the hydroxyl-terminated hydrogenated block copolymer and an ethylene-based copolymer, a foam using the same, and a preparation thereof, as well as a resin composition containing the hydroxyl-terminated hydrogenated block copolymer and a polar thermoplastic elastomer, a foam using the same, and a preparation thereof.

[0013] (1) A foam obtained by foaming a resin composition, the foam comprising a hydroxyl-terminated hydrogenated styrene block copolymer, the hydroxyl-terminated hydrogenated styrene block copolymer having the formula: (AB)n-OH, (BA)n-OH, A(BA)n-OH, or B(AB)n-OH is a linear block copolymer of n is 1 to 4, the block has a terminal hydroxyl group, the A block before hydrogenation comprises a styrene monomer unit, and the B block before hydrogenation comprises a conjugated diene monomer unit; A foam, comprising a hydroxyl-terminated hydrogenated styrene block copolymer having 10 to 60 weight % of an A block, a 1,2-vinyl bond content in the conjugated diene monomer units of the hydroxyl-terminated hydrogenated styrene block copolymer being in the range of 5 to 60 mol % before hydrogenation, and 40 mol % or more of the conjugated diene monomer units being hydrogenated after hydrogenation, and the hydroxyl-terminated hydrogenated styrene block copolymer having a weight average molecular weight of 30,000 to 200,000.

[0014] (2) The foam is obtained by foaming a resin composition containing (a) the above-mentioned hydroxyl-terminated hydrogenated styrene block copolymer and (b) an ethylene-based copolymer, and the weight ratio (a / b) of component (a) to component (b) is 90 / 10 to 10 / 90.

[0015] (3) The foam is obtained by foaming a resin composition containing (a) the above-mentioned hydroxyl-terminated hydrogenated styrene block copolymer and (b) a polar thermoplastic elastomer, and the weight ratio (a / b) of component (a) to component (b) is 90 / 10 to 5 / 95.

[0016] (4) An article made from the foam is a component of footwear. In some embodiments, the component of footwear is a midsole.

[0017] (5) A resin composition comprising a hydroxyl-terminated hydrogenated styrene block copolymer, the hydroxyl-terminated hydrogenated styrene block copolymer having the formula: (AB)n-OH, (BA)n-OH, A(BA)n-OH, or B(AB)n-OH is a linear block copolymer of n is 1 to 4, the block has a terminal hydroxyl group, the A block before hydrogenation comprises a styrene monomer unit, and the B block before hydrogenation comprises a conjugated diene monomer unit; A resin composition comprising a hydroxyl-terminated hydrogenated styrene block copolymer having 10 to 60 weight % of an A block, a 1,2-vinyl bond content in the conjugated diene monomer units of the hydroxyl-terminated hydrogenated styrene block copolymer being in the range of 5 to 60 mol % before hydrogenation, and 40 mol % or more of the conjugated diene monomer units being hydrogenated after hydrogenation, and a weight average molecular weight of 30,000 to 200,000.

[0018] (6) Use of the resin composition for preparing a foam.

[0019] It is noted that in this specification, when a component / ingredient is described as having an element, it means that the component / ingredient may have one or more of that element, and does not mean that the component / ingredient has only one of that element, unless otherwise specified.

[0020] In this specification, unless otherwise specified, feature A "or" feature B means the presence of feature A or the presence of feature B. feature A "and / or" feature B means the presence of feature A, the presence of feature B, or the presence of both features A and B. feature A "and" feature B means the presence of both features A and B. The terms "comprise," "comprising," "including," "including," "having," "has," and "having" mean "including, but not limited to."

[0021] In this disclosure, unless otherwise specified, the terms "almost," "about," and "approximately" refer to an acceptable error in a particular value, typically as determined by one of ordinary skill in the art, depending on how the value is measured or determined. In some embodiments, the terms "almost," "about," and "approximately" refer to within 1, 2, 3, or 4 standard deviations. In some embodiments, the terms "almost," "about," and "approximately" refer to within ±20%, ±15%, ±10%, ±9%, ±8%, ±7%, ±6%, ±5%, ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.05%, or less of a given value or range. The quantities given herein are approximate quantities, i.e., "almost," "about," and "approximately" can be implied without specifying them. Furthermore, the phrases "in the range of a first value to a second value," "from a first value to a second value," etc., mean that the range includes the first value, the second value, and other values ​​between the first and second values.

[0022] Other novel features of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0023] [Figure 1] Figure 1 shows an image of the peeled foam sample after the peel adhesion test. DETAILED DESCRIPTION OF THE INVENTION

[0024] Preferred embodiments of the present invention are described in more detail below. The present invention provides a foam obtained by crosslinking and foaming a resin composition comprising a hydroxyl-terminated hydrogenated styrene block copolymer. The present invention also provides a foam obtained by crosslinking and foaming a resin composition containing the above-mentioned hydroxyl-terminated hydrogenated styrene block copolymer and an ethylene-based copolymer. Still further, the present invention provides a foam obtained by foaming a resin composition containing the above-mentioned hydroxyl-terminated hydrogenated styrene block copolymer and a polar thermoplastic elastomer. The main components used to produce the foam of the present invention are described in detail below.

[0025] (A) Hydroxyl-terminated hydrogenated styrene block copolymer The hydroxyl-terminated hydrogenated styrene block copolymer of the present disclosure has a general formula of (AB)n-OH, (BA)n-OH, A(BA)n-OH, or B(AB)n-OH, and is terminated with a hydroxyl group, wherein the A block comprises vinyl aromatic units and the B block comprises conjugated diene monomer units, the hydroxyl-terminated hydrogenated styrene block copolymer comprises 10 to 60 weight % of the A block, the 1,2-vinyl bond content of the conjugated diene monomer units is in the range of 5 to 60 mol % before hydrogenation, and after hydrogenation, 40 mol % or more of the conjugated diene monomer units are hydrogenated, and the hydroxyl-terminated hydrogenated styrene block copolymer has a weight average molecular weight of 30,000 to 200,000.

[0026] Hydroxyl-terminated hydrogenated styrene block copolymers are prepared by sequential polymerization of A and B blocks in an anionic polymerization process containing terminal hydroxyl groups, the hydroxyl groups being located either at the end of the A block or at the end of the B block.

[0027] In terms of producing footwear foam, the hydroxyl-terminated hydrogenated styrene block copolymer of the present disclosure is preferably an AB-OH or BA-OH linear diblock copolymer. The hydroxyl-terminated hydrogenated styrene diblock copolymer significantly improves processability in a foam production process that involves incorporating a free radical initiator and a blowing agent into a foam composition at a temperature of about 120°C or less, followed by injection molding the composition containing the free radical initiator and the blowing agent in a mold. Crosslinking and production of the blowing agent in the mold occurs at a temperature of about 150°C to 180°C. A foam is formed after the mold is opened.

[0028] In the hydroxyl-terminated hydrogenated styrene block copolymer of the present invention, the A block before hydrogenation is a polymer block of styrene units, and the B block before hydrogenation is a polymer block of conjugated diene monomer units selected from the group consisting of butadiene units, isoprene units, and mixtures thereof.

[0029] Optionally, the A block of the hydroxyl-terminated hydrogenated styrene block copolymer of the present invention before hydrogenation is a polymer block of styrene monomer units and conjugated diene monomer units. The conjugated diene monomer units are butadiene units, isoprene units, or a mixture thereof, and the content of the conjugated diene monomer units in the A block is in the range of 0% by weight to 15% by weight, based on the total weight of the A block. Optionally, the A block is a styrene monomer unit, and the B block is a butadiene monomer unit. Optionally, the B block before hydrogenation is a polymer block of conjugated diene monomer units and styrene monomer units. The conjugated diene monomer units are butadiene units, isoprene units, or a mixture thereof, and the content of the styrene monomer units is in the range of 0% by weight to 20% by weight, based on the total weight of the B block.

[0030] In some embodiments, the 1,2-vinyl bond content in the butadiene units may be in the range of 5 to 60 mol % before hydrogenation. In one embodiment, the B block is a polymer block of butadiene, and the 1,2-vinyl bond content in the butadiene units may be in the range of 5 to 60 mol % before hydrogenation. In one embodiment, the A block is a polymer block of styrene units and butadiene units, and the 1,2-vinyl bond content in the butadiene units may be in the range of 5 to 60 mol % before hydrogenation. In some embodiments, the B block is a polymer block of butadiene units and styrene units, and the 1,2-vinyl bond content in the butadiene units may be in the range of 5 to 60 mol % before hydrogenation.

[0031] In some embodiments, the 3,4-vinyl bond content in the isoprene units may be in the range of 5 to 60 mol % before hydrogenation. In one embodiment, the B block is a polymer block of isoprene, and the 3,4-vinyl bond content in the isoprene units is in the range of 5 to 60 mol % before hydrogenation. In one embodiment, the A block is a polymer block of styrene units and isoprene units, and the 3,4-vinyl bond content in the isoprene units is in the range of 5 to 60 mol % before hydrogenation.

[0032] In some embodiments, 60 to 95 mole percent of the conjugated diene monomer units are hydrogenated after hydrogenation.

[0033] In some embodiments, the A block is a polymer block of styrene units and conjugated diene monomer units. Specifically, the content of conjugated diene monomer units in the A block can be in the range of greater than about 0 wt % to less than about 15 wt %, such as 3 wt %, 6 wt %, 9 wt %, 12 wt %, and 15 wt %.

[0034] In some embodiments, the B block is a polymer block of butadiene units and styrene units. Specifically, the content of styrene monomer units in the B block can range from greater than about 0 wt% to less than about 20 wt%, such as 5 wt%, 10 wt%, and 15 wt%.

[0035] In some embodiments, the hydroxyl-terminated styrenic block copolymer has a number average functionality (f(n)) ranging from 0.9 to 1.0. In some embodiments, the hydroxyl-terminated styrenic block copolymer has a molecular weight distribution ranging from 1.0 to 1.05.

[0036] The method for producing the hydroxyl-terminated styrene block copolymer before hydrogenation is not particularly limited, and any well-known method can be used. Among the polymerization methods, living anionic polymerization carried out in a hydrocarbon solvent and initiated by an organic alkali metal compound can be used. For example, the above polymer synthesis step is clearly described in U.S. Pat. No. 3,823,203. The hydrocarbon solvent is not particularly limited, and any well-known solvent can be used. For example, the hydrocarbon solvent can include aliphatic hydrocarbons such as n-hexane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as xylene. The above hydrocarbon solvents can be used alone or in combination of two or more.

[0037] The initiator is not particularly limited, and initiators such as aliphatic hydrocarbon alkali metal compounds, aromatic hydrocarbon alkali metal compounds, and organic amino alkali metal compounds, which are known to have anionic polymerization activity with vinyl aromatic monomers such as styrene and conjugated diene monomers such as butadiene, can be used. The alkali metals used as initiators can include lithium, sodium, and potassium. In some embodiments, the initiator can be an aliphatic hydrocarbon alkali metal such as n-butyllithium.

[0038] The polymerization process for preparing hydroxyl-terminated styrene block copolymers can be carried out similarly to that used for anionic polymerization. Polymerization can be carried out at temperatures ranging from about 0°C to about 180°C, more preferably from about 30°C to about 150°C, and most preferably from about 30°C to about 90°C. It can be carried out in an inert atmosphere, preferably nitrogen, and can also be achieved under pressures ranging from about 0.5 to about 10 bar. The polymerization process generally requires less than 12 hours, depending on the temperature, concentration of the monomer components, and molecular weight of the polymer.

[0039] The above-mentioned method for chain end functionalization is clearly described in U.S. Pat. No. 5,693,711. For example, a hydroxyl-terminated styrene triblock copolymer can be prepared as follows: First, styrene is introduced to generate a styrene block, followed by the introduction of butadiene to form a midblock. Next, styrene is again introduced to form end blocks. Third, an alkylene oxide, such as ethylene oxide or propylene oxide, is introduced as a capping agent to form hydroxyl groups at the ends. This is followed by the addition of a compound with active hydrogen, such as an alcohol, a carboxylic acid, or water, to terminate the polymerization process. In some embodiments, the alkylene oxide is selected from one or more of ethylene oxide, propylene oxide, 1,2-butylene oxide, and 1,2-pentane oxide. Ethylene oxide is suitable as a capping agent to form hydroxyl groups.

[0040] Hydrogenation of hydroxyl-terminated styrene block copolymers having hydroxyl groups at the ends can be carried out in a process similar to that of known hydrogenation processes. For example, such hydrogenation has been achieved using methods such as those reported in U.S. Patents 3,595,942 and 3,700,633. These hydrogenation methods employ a suitable catalyst. The catalyst may include an aluminum alkyl or a metal selected from Groups IA, II-A, and III-A of the Periodic Table of Elements, particularly a Group VIII metal such as nickel or cobalt, combined with a suitable reducing agent such as hydroxides of lithium, magnesium, or aluminum.

[0041] The hydrogenation process is not particularly limited, but hydrogenation is usually carried out at 0°C to 180°C, more preferably 30°C to 150°C. The hydrogen pressure used in this process is not particularly limited, but is usually 0.1 to 20 MPa, 0.2 to 15 MPa, or 0.3 to 5 MPa. The reaction time is usually 1 minute to 10 hours, or 10 minutes to 5 hours.

[0042] The hydrogenation process can be carried out by a batch process, a continuous process, or a combination thereof. If necessary, catalyst residues can be removed. The hydrogenated polymer can be isolated by injecting hot water with stirring, and the organic solvent can be removed by steam stripping.

[0043] In some embodiments, the microstructure of the conjugated diene segments of the hydrogenated styrene copolymer, such as the vinyl bond content and styrene content before hydrogenation, and the degree of hydrogenation after hydrogenation can be determined by proton nuclear magnetic resonance ( 1 The weight average molecular weight can be determined using H-NMR. Furthermore, the weight average molecular weight can be determined by gel permeation chromatography (GPC).

[0044] (B) Ethylene-based copolymer In some embodiments of the present disclosure, the foamed resin composition may include the above-described hydroxyl-terminated hydrogenated styrene block copolymer and the ethylene-based copolymer, and in some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the ethylene-based copolymer is 90 / 10 to 10 / 90.

[0045] In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the ethylene-based copolymer can be 50 / 50 to 10 / 90. In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the ethylene-based copolymer can be, for example, 50 / 50 to 10 / 90, 40 / 60 to 10 / 90, 35 / 65 to 10 / 90, or 30 / 70 to 10 / 90.

[0046] In the present disclosure, the ethylene-based copolymer is not particularly limited, and known ethylene-based copolymers can be used. For example, suitable ethylene-based copolymers may be ethylene-vinyl acetate copolymer (EVA) obtained by copolymerization of ethylene and vinyl acetate, ethylene-α-olefin random copolymers, olefin block copolymers having ethylene polymer blocks and C4-C8-α-olefin polymer blocks, polyethylene, or combinations thereof. In some embodiments, the polyethylene is linear low-density polyethylene.

[0047] In some embodiments, the ethylene-based copolymer may be an ethylene-vinyl acetate copolymer, wherein the vinyl acetate content is in the range of about 15 to 40 wt %, based on the total weight of the ethylene-vinyl acetate copolymer. In some embodiments, the ethylene-based copolymer may be an ethylene-α-olefin random copolymer, wherein the α-olefin may include 1-butene, 1-pentene, 1-hexene, 1-octene, or a combination thereof, such as TAFMER® olefin copolymers manufactured by Mitsui Chemicals, Inc. and ENGAGE® manufactured by Dow Chemical Company. In some embodiments, the ethylene-based copolymer is an ethylene-α-olefin random copolymer consisting of ethylene units and octene units.

[0048] In some embodiments, the ethylene-based copolymer can be an olefin block copolymer such as INFUSE® olefin block copolymers manufactured by Dow Chemical Company. In one embodiment, the ethylene-based copolymer is an olefin block copolymer comprising polymer blocks of ethylene units. In some embodiments, the ethylene-based copolymer is an olefin block copolymer comprising polymer blocks of ethylene units and polymer blocks of octene units. Suitable olefin block copolymers exhibit a melting point in the range of 115°C to 130°C and a density in the range of 0.875 g / cc to 0.945 g / cc.

[0049] In some embodiments, the ethylene-based interpolymer may further comprise high density polyethylene and low density polyethylene for property tailoring.

[0050] (C) Polar thermoplastic elastomer In some embodiments of the present disclosure, a resin composition for preparing a foam may include the above-described hydroxyl-terminated hydrogenated styrene block copolymer and TPU (thermoplastic polyurethane). In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the TPU is 90 / 10 to 10 / 90.

[0051] In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the TPU can be 50 / 50 to 10 / 90. In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the TPU can be, for example, 50 / 50 to 10 / 90, 40 / 60 to 10 / 90, 35 / 65 to 10 / 90, or 30 / 70 to 10 / 90.

[0052] In this disclosure, the structure of the TPU is not particularly limited, and well-known copolymers prepared from diisocyanates, chain extenders or short-chain diols, and polyols or long-chain diols can be used. It is a segmented block copolymer consisting of soft and hard segments. The hard segments are isocyanates and can be classified as either aliphatic or aromatic depending on the type of isocyanate. The soft segments are composed of polyols or long-chain diols. Additionally, short-chain diols may also act as chain extenders in the TPU structure.

[0053] In some embodiments of the present disclosure, the foamed resin composition may include the above-described hydroxyl-terminated hydrogenated styrene block copolymer and TPEE (thermoplastic polyester elastomer, also known as thermoplastic copolyester). One of the most well-known trade names is Hytrel® manufactured by DuPont®. In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the TPEE is 90 / 10 to 10 / 90.

[0054] In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the TPEE can be 50 / 50 to 5 / 95. In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the TPEE can be, for example, 50 / 50 to 10 / 90, 40 / 60 to 10 / 90, 35 / 65 to 10 / 90, or 30 / 70 to 10 / 90.

[0055] In this disclosure, the structure of TPEE is not particularly limited and is a well-known copolymer containing alternating hard and soft block segments. The hard segments are usually composed of polyesters with aromatic rings, which give TPEE its strength and heat resistance. The soft segments are usually composed of polyethers or polyesters with aliphatic chains, which give the material flexibility and resilience. In some embodiments, TPEE is a type of linear segmented copolymer containing PBT (polybutylene terephthalate) polyester hard segments (crystalline phase) and aliphatic polyester or polyether (amorphous phase) soft segments.

[0056] In some embodiments of the present disclosure, the foamed resin composition may include the above-mentioned hydroxyl-terminated hydrogenated styrene block copolymer and PEBA (polyether block amide). One of the most well-known trade names is Pebax® manufactured by Arkema. In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to PEBA is 90 / 10 to 10 / 90.

[0057] In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the PEBA can be 50 / 50 to 5 / 95. In some embodiments, the weight ratio of the hydroxyl-terminated hydrogenated styrene block copolymer to the PEBA can be, for example, 50 / 50 to 10 / 90, 40 / 60 to 10 / 90, 35 / 65 to 10 / 90, or 30 / 70 to 10 / 90.

[0058] In the present disclosure, the structure of PEBA is not particularly limited, and it is a well-known copolymer containing alternating hard and soft block segments. The hard segments, usually polyamide (PA), provide PEBA with its strength and heat resistance. The soft segments, usually polyether, provide flexibility and resilience.

[0059] In the present disclosure, the foam can be obtained by a process including injection molding a resin composition in an injection mold, crosslinking the resin composition using an organic peroxide initiator, and foaming the resin composition using a chemical foaming agent, wherein the crosslinking temperature in the injection mold is about 150°C to about 200°C.

[0060] (D)Organic peroxide In the present invention, the organic peroxide used to crosslink the foamed resin composition is not particularly limited, and any well-known organic peroxide can be used. For example, dicumyl peroxide (DCP), 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, bis(1-(tert-butylperoxy)-1-methylethyl)-benzene (BIPB), and di-t-butylperoxide are suitable and widely used in the preparation of foams. The amount of the organic peroxide is not particularly limited, but is preferably 0.01 to 10 parts, more preferably 0.1 to 3 parts, per 100 parts by weight of the total amount of the resin composition.

[0061] (E) Chemical foaming agent The blowing agent of the present invention is not particularly limited, and any well-known blowing agent can be used. In some embodiments, the blowing agent can be an organic type blowing agent or an inorganic type thermally decomposable blowing agent. Among these blowing agents, the most well-known organic type blowing agents can include azodicarbonamide (AC), 4,4'-oxybis(benzenesulfonylhydrazide), p-toluenesulfonyl semicarbazide, N,N'-dinitrosopentamethylenetetramine, diphenylsulfone-3,3'-disulfonyl hydrazide (DPSDSH), or trihydraznotriazine. Specific examples of inorganic thermally decomposable foaming agents include sodium bicarbonate, ammonium bicarbonate, sodium carbonate, or ammonium carbonate. Among the above foaming agent types, azodicarbonamide (AC) is most suitable and is used in the present invention. The amount of foaming agent used is not particularly limited, but is preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the total amount of the resin composition.

[0062] (F) Other additives Although not particularly limited, the resin composition for the foam of the present invention may further contain, in addition to the above components, a crosslinking coagent, a functional chain extender, an organometallic compound, a filler, a heat and weather stabilizer, a pigment, etc. A functional chain extender having at least one functional group selected from the group consisting of anhydride, epoxy, and isocyanate that can react with the terminal hydroxyl group of the hydroxyl-terminated hydrogenated styrene block copolymer may be used to crosslink the resin composition.

[0063] A crosslinking coagent can be used in the present invention to accelerate the crosslinking reaction. For example, the crosslinking coagent can include triallyl isocyanurate, triallyl cyanurate, ethylene glycol dimethacrylate, or vinyl butyrate. To make the pores of the foam finer or more uniform, organometallic compounds can be added during foaming. For example, suitable organometallic compounds can include zinc diacrylate and zinc dimethacrylate, which can also function as crosslinking coagents. Fillers are often included in resin compositions for cost savings, hardness or modulus adjustment, and nucleation purposes. Examples of fillers can include clay, silicon dioxide, talc, titanium dioxide, zinc oxide, or calcium carbonate.

[0064] To improve the durability of foam products, one of the most common methods is to add heat and weather stabilizers to the resin composition. Heat stabilizers can include phosphorus-based stabilizers such as Irgafos 168. Weather stabilizers can include hindered phenol-based stabilizers such as pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate]. Meanwhile, examples of pigments can include azo-based, phthalocyanine-based, oxide-based, chromate-based, molybdate-based, inorganic, and carbon black.

[0065] Preparation of resin compositions for foaming The resin composition of this embodiment can be produced by first melting and mixing the above components, hydroxyl-terminated hydrogenated styrene block copolymer and ethylene-based copolymer, or optionally a polar thermoplastic elastomer, in a kneader, and then mixing in the organic peroxide and blowing agent, including other additives such as fillers. The process is carried out at 120°C or below to avoid premature decomposition of the peroxide and blowing agent.

[0066] The melt-mixing and mixing method is not particularly limited, and well-known methods can be used. For example, extruders such as a single-screw extruder, a twin-screw extruder, a multi-screw extruder, a Henschel mixer, a Banbury mixer, a roll mill, and a kneader can be used in the present invention. In this embodiment, a melt-mixing method using a kneader is preferred.

[0067] After the melt-mixing process, the shape of the resin composition of the present embodiment is not particularly limited. For example, it can be formed into pellets, flakes, strands, chips, or the like. For example, the components can be mixed using a granulator or the like to form pellets. For example, after kneading the components of the resin composition, a roll mill can be used to form a sheet ready for foaming.

[0068] The polymer structure identity of the hydroxyl-terminated hydrogenated styrene block copolymer is determined as follows.

[0069] Molecular weight and molecular weight distribution Both the weight average molecular weight (Mw) and number average molecular weight (Mn) were tested and determined by gel permeation chromatography (GPC) equipment. The molecular weight values ​​of the peaks in the chromatogram were calculated using a calibration curve of commercially available standard polystyrene. The molecular weight distribution (Mw / Mn) was determined based on the weight average molecular weight (Mw) and number average molecular weight (Mn). Further details about the test procedure and instrument information are described below. The equipment is a commercially available GPC system including a parallax refractive index detector provided by PDI and Waters Corporation. Generally, tetrahydrofuran (THF) is selected as the solvent. The measurement temperature is maintained at 40°C. The flow rate is 1 ml / min, and the injection volume is 100 μl. The ratio of hydrogenated block copolymer / THF is 3 mg / 15 cc.

[0070] Styrene content and vinyl bond content The styrene content and vinyl bond content of the hydrogenated styrene diblock copolymer before hydrogenation were measured using VARIAN400 provided by Agilent Technologies, Inc. 1 The NMR spectrum is measured by H-NMR. Generally, deuterated chloroform is the solvent of choice.

[0071] Hydrogenation degree The degree of hydrogenation is 1 It can be calculated from the rate of decrease of the unsaturated bond signal in the H-NMR spectrum. The calculation is described as follows: Hydrogenation degree (mol%) = B / (A+B) × 100% A: Number of moles of unhydrogenated conjugated diene monomer units B: Number of moles of hydrogenated conjugated diene monomer units

[0072] Number Average Functionality (f(n)) The number average functionality of the hydroxyl-terminated hydrogenated styrene block copolymer is 1 It can be calculated from H-NMR spectrum and GPC.

number

[0073] Melt flow index MFI (Melt Flow Index) is measured according to ASTM-D1238.

[0074] In some embodiments of the present invention, the resulting foam has the following properties: 0.1 to 0.5 g / cm 3 range, impact resilience within the range of 50% to 80%, and hardness (Asker C) within the range of 20 to 70.

[0075] The mechanical properties of the crosslinked foams were evaluated as follows.

[0076] specific gravity Once crosslinked, the foam was punched into a circle with a diameter of 2.54 cm and a thickness of 1 cm, and the density was measured by an electronic hydrometer (MS-204S manufactured by Mettler Toledo Co., Ltd.).

[0077] hardness The hardness (Asker C) of the crosslinked foam was measured using an Asker C hardness tester (Type C manufactured by Polymer Co., Ltd.) according to ASTM D2240, and the value was read within 1 second. The average value (arithmetic mean) of five points was used as the hardness.

[0078] split tear strength The splitting strength of the foam once crosslinked is determined according to ASTM D3574F.

[0079] tensile strength The tensile strength at break of the foam once crosslinked is determined according to ASTM D412.

[0080] elongation The elongation at break of the foam once crosslinked is determined according to ASTM D412.

[0081] Compression set The crosslinked foam was punched into a circular shape with a diameter of 2.54 cm and used as a test specimen. It was compressed to 50% of its thickness. After holding at 50°C for 6 hours, the pressure was released and the thickness was measured after 1 hour. The magnitude of the residual deformation was evaluated.

[0082] Impact resilience The rebound resilience of crosslinked foams is determined in a vertical rebound apparatus according to ASTM-D2632. Rebound resilience is determined as the ratio of the rebound height to the drop height of a metal plunger of defined mass and shape dropped onto a foam sample.

[0083] Shrinkage The shrinkage of foams is determined according to ASTM-D1917. The sample is chopped into square specimens 5 cm long and 1 cm thick. The initial length of the specimen is first recorded, and the specimen is placed in an oven at 70°C for 40 minutes. After heating, the specimen is removed from the oven and allowed to cool at room temperature. After cooling, the length is measured again, and the change in length is recorded as shrinkage.

[0084] Adhesion evaluation of foams containing hydroxyl-terminated hydrogenated block copolymers. Foam adhesion evaluation was performed by peel testing of laminated foam and vulcanized samples after treatment with primer and PU adhesive. The components employed in the bonded samples in the test are listed below. 1) Foam samples with a thickness of 10 mm for both the comparative example without a hydroxy-terminated block copolymer and the example containing a hydroxy-terminated block copolymer are listed in Table 2. 2) It was bonded to the foam sample using a vulcanized rubber flat sheet with a thickness of 2 mm provided by Yong-Shan Enterprise Co., Ltd. (Taiwan). 3) <Primer System> The primers used were Greco001A and 001B obtained from Great Eastern Resins Industrial Co., Ltd. (Taiwan). 4) <PU Adhesive System> The PU-based adhesive is Greco6608, and the curing agent is Greco368. The PU-based adhesive and the curing agent are obtained from Great Eastern Resins Industrial Co., Ltd. (Taiwan).

[0085] The preparation of the bonded sample of the foam sample and the vulcanized rubber flat sheet by co-bonding using the primer and the PU adhesive was carried out as follows. 1) The foam sample sheet and the vulcanized rubber flat sheet were treated by a polishing and washing process. The polishing process was carried out by a polishing machine to achieve the desired roughness and smoothness on the sample surface. The washing process was carried out with ethanol. After the polishing and washing treatments, the sample sheet was dried in an oven at 70 °C for 20 minutes. 2) The aqueous primers Greco001A and 001B were thoroughly mixed at a weight ratio of 100 / 2, and the primer solution was brush-coated onto the polished surfaces of the foam sample and the vulcanized rubber sheet. Then, these sample sheets were placed in an oven at 70 °C for 4 minutes to evaporate the solvent. 3) The trade name of the PU adhesive is 6608, and the trade name of the curing agent is 368. These two materials should be mixed in a 100 / 5 weight ratio before the adhesive is brushed onto the sample. After the adhesive and curing agent are thoroughly mixed, the mixture is brushed onto the surface of the primer-treated sponge and vulcanized rubber sheet. The sample sheets are then placed in a 70°C oven for 4 minutes to evaporate the solvent. 4) The treated foam sheet surface was attached to the treated surface of the vulcanized rubber sheet, and the attached sheet sample was pressed with a fixed press for a few seconds to bond the foam sample to the vulcanized rubber sheet. The bonded sheet sample was left at room temperature for more than 24 hours, and finally the sheet sample was cut into test specimens 15 cm long and 25 mm wide.

[0086] Referring to ASTM D1876, the T-peel test method is applied to evaluate the bond strength between foam / vulcanized rubber sheets. A tensile machine (Instron 3365) is used to measure the bond strength in kgf / cm.

[0087] Materials for Examples and Comparative Examples Ethylene copolymer EVA659 is an ethylene vinyl acetate copolymer manufactured by USI Corporation under the trade name "UE659" with a vinyl acetate content of 25% by weight and a melt flow index of 3 g / 10 min when measured at 190°C / 2.16 kgf.

[0088] OBC9530 is an olefin block copolymer. Specifically, OBC9530 is manufactured by Dow Chemical Company under the trade name "Infuse9530" and has a melt flow index of 5.0 g / 10 min when measured at 190°C / 2.16 kgf, a viscosity of 0.887 g / cm 3 and a melting point of 119°C.

[0089] POE8450 is manufactured by Dow Chemical Company under the trade name "Engage8450" and has a melt flow index of 3.0 g / 10 min when measured at 190°C / 2.16 kgf, and a melt flow index of 0.902 g / cm 3 It is an ethylene / 1-octene random copolymer with a density of 1.

[0090] organic peroxide Bis(1-(tert-butylperoxy)-1-methylethyl)-benzene (BIPB) is manufactured by Arkema Group.

[0091] Chemical Foaming Agents Azodicarbonamide (AC) is manufactured by Kumyang Corporation.

[0092] Other additives Calcium carbonate is manufactured by Yuncheng Chemical Industrial CO., LTD. ZnO (zinc oxide) is manufactured by Diamonchem International Co., Ltd. Stearic acid is manufactured by Vulchem ​​Inc.

[0093] In some embodiments of the present invention, the resulting foam can be used as a component of footwear, such as a midsole.

[0094] Various embodiments of the present disclosure are provided in the following description. These embodiments are intended to explain the technical concepts of the present disclosure and do not limit the scope of the present disclosure. The features described in the embodiments can be applied to other embodiments by appropriate modification, substitution, combination, or separation.

[0095] The present disclosure will be described in more detail through embodiments, but these embodiments do not limit the scope of the present disclosure. Unless otherwise specified, in the following preparation examples, examples, and comparative examples, temperatures are in degrees Celsius, and numerical parts or percentages are by weight. The relationship between parts by weight (or parts by mass) and parts by volume is similar to the relationship between kilograms and liters.

[0096] A sample of hydroxy-terminated hydrogenated block copolymer was prepared as follows.

[0097] SEB-OH-A SEB-OH-A, i.e., a hydroxyl-terminated hydrogenated styrene-butadiene-styrene diblock copolymer, was prepared and characterized as follows. First, 4800 g of cyclohexane, 15.7 mmol of n-butyllithium, and 166 mmol of tetrahydrofuran (THF) were charged into a 10-liter reactor equipped with a heater and a stirrer. Second, 160 g of styrene was added to the solvent to conduct anionic polymerization at a temperature of approximately 50 °C. Third, 640 g of butadiene was added to the reactor. After the butadiene reaction was complete, 1.2 g of propylene oxide was added to form a hydroxyl-terminated styrene-butadiene diblock copolymer. Methanol was then added to terminate the polymerization. The SB-OH copolymer had a styrene content of 20 wt %, and the 1,2-vinyl bond content in the butadiene block was approximately 38 mol %.

[0098] The SB-OH copolymer obtained by the above process was then hydrogenated in a pressure vessel using a nickel-2-ethylhexanoic acid / TEAL catalyst and hydrogen gas. The temperature for the hydrogenation process was controlled between approximately 40°C and 100°C. After approximately 80 mol% of the butadiene block was hydrogenated, the hydrogenation reaction was terminated. The resulting sample was then washed with hot acidic water to remove the residual catalyst. Finally, the block copolymer was isolated by coagulation in boiling water and then dried. The yield of hydroxyl-terminated hydrogenated styrene-butadiene diblock copolymer (SEB-OH) was approximately 80%.

[0099] Analysis showed that the resulting SEB-OH-A copolymer had a degree of hydrogenation of 79 mol%, a weight average molecular weight of about 75,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and an MFI measured at 190°C / 5 kgf of 0.4.

[0100] SEBS-OH-A SEBS-OH-A is a hydroxyl-terminated hydrogenated styrene-butadiene-styrene triblock copolymer, and its preparation and detailed characterization are described. First, 4800 g of cyclohexane, 16.8 mmol of n-butyllithium, and 166 mmol of tetrahydrofuran (THF) were charged into a 10-liter reactor equipped with a heater and a stirrer. Second, 80 g of styrene was added to the solvent and anionic polymerization was carried out at a temperature of approximately 50 °C. Third, 640 g of butadiene was added to the reactor until the butadiene reaction was complete. Fourth, 80 g of styrene was added to the reactor. After the styrene polymerization was complete, 1.6 g of propylene oxide was added to form a hydroxyl-terminated styrene-butadiene-styrene triblock copolymer structure. Methanol was then added to terminate the polymerization. The SBS-OH copolymer had a styrene content of 20% by weight, and the 1,2-vinyl bond content in the butadiene block was about 40% by mole.

[0101] The SBS-OH copolymer obtained by the above process was then hydrogenated in a pressure vessel using a nickel-2-ethylhexanoic acid / TEAL catalyst and hydrogen gas. The temperature for the hydrogenation process was controlled between approximately 40°C and 100°C. After approximately 80 mol% of the butadiene block was hydrogenated, the hydrogenation reaction was terminated. The resulting sample was then washed with hot acidic water to remove the residual catalyst. Finally, the block copolymer was isolated by coagulation in boiling water and then dried. The yield of the SBS-OH copolymer was approximately 80%.

[0102] Analysis showed that the resulting SEBS-OH-A copolymer had a degree of hydrogenation of 82 mol%, a weight average molecular weight of about 53,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and an MFI of 18 measured at 190°C / 5 kgf.

[0103] SEB-OH-B SEB-OH-B, a hydroxyl-terminated hydrogenated styrene-butadiene diblock copolymer, was prepared and characterized as follows:

[0104] First, 4800 g of cyclohexane, 12.6 mmol of n-butyllithium, and 166 mmol of tetrahydrofuran (THF) were charged into a 10-liter reactor equipped with a heater and a stirrer. Second, 160 g of styrene was added to the solvent to conduct anionic polymerization at a temperature of approximately 50 °C. Third, 640 g of butadiene was added to the reactor until the reaction of butadiene was complete, and 1 g of ethylene oxide was added to form a hydroxyl-terminated styrene-butadiene diblock copolymer structure. Methanol was then added to terminate the polymerization. The SB-OH copolymer had a styrene content of 20 wt % and a 1,2-vinyl bond content in the butadiene block of approximately 40 mol %.

[0105] The SB-OH copolymer obtained by the above process was then hydrogenated in a pressure vessel using nickel-2-ethylhexanoic acid / TEAL catalyst and hydrogen gas. The temperature for the hydrogenation process was controlled between approximately 40°C and 100°C. After approximately 80 mol% of the butadiene block was hydrogenated, the hydrogenation reaction was terminated. The obtained sample was then washed with hot acidic water to remove the residual catalyst. Finally, the block copolymer was isolated by coagulation in boiling water and then dried. The yield of the SEB-OH copolymer was approximately 80%.

[0106] Analysis showed that the resulting SEB-OH-B copolymer had a degree of hydrogenation of 85 mol%, a weight average molecular weight of about 64,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and an f(n) value of about 0.95.

[0107] SEB-OH-C SEB-OH-C, i.e., a hydroxyl-terminated hydrogenated styrene-butadiene diblock copolymer, was prepared in a similar manner to that used to prepare SEB-OH-B. This hydroxyl-terminated hydrogenated styrene-butadiene diblock copolymer was formed by reacting with ethylene oxide and had a styrene content of 34% by weight, a 1,2-vinyl bond content in the butadiene block of about 41 mol%, and a hydrogenation degree of 82 mol%. It had a weight-average molecular weight of about 55,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and an f(n) value of about 0.95.

[0108] SEBS-OH-B SEBS-OH-B, a hydroxyl-terminated hydrogenated styrene-butadiene-styrene triblock copolymer, was prepared and characterized as follows.

[0109] First, 4800 g of cyclohexane, 16.8 mmol of n-butyllithium, and 166 mmol of tetrahydrofuran (THF) were charged into a 10-liter reactor equipped with a heater and a stirrer. Second, 120 g of styrene was added to the solvent to allow anionic polymerization at a temperature of approximately 50 °C. Third, 560 g of butadiene was added to the reactor until the butadiene reaction was complete. Fourth, 120 g of styrene was added to the reactor, and upon completion of the styrene polymerization, 1.56 g of ethylene oxide was added to form a hydroxyl-terminated styrene-butadiene di-styrene triblock copolymer structure. Methanol was then added to terminate the polymerization. The SBS-OH copolymer had a styrene content of 30 wt % and a 1,2-vinyl bond content in the butadiene block of approximately 40.1 mol %.

[0110] The SBS-OH copolymer obtained by the above process was then hydrogenated in a pressure vessel using a nickel-2-ethylhexanoic acid / TEAL catalyst and hydrogen gas. The temperature for the hydrogenation process was controlled between approximately 40°C and 100°C. After approximately 80 mol% of the butadiene block was hydrogenated, the hydrogenation reaction was terminated. The resulting sample was then washed with hot acidic water to remove the residual catalyst. Finally, the block copolymer was isolated by coagulation in boiling water and then dried. The yield of the SBS-OH copolymer was approximately 80%.

[0111] Analysis showed that the resulting SEBS-OH-B had a degree of hydrogenation of 85.3 mol%, a weight average molecular weight of about 45,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and an f(n) value of about 0.95.

[0112] SEBS-OH-C SEBS-OH-C is a hydroxyl-terminated hydrogenated styrene-butadiene-styrene triblock copolymer. It was prepared in a manner similar to that used to prepare hydroxyl-terminated SEBS-OH-B. It was formed by reacting with ethylene oxide and had a styrene content of 20% by weight. The 1,2-vinyl bond content in the butadiene block was approximately 40 mol %. The degree of hydrogenation was 82 mol %. It had a weight average molecular weight of approximately 53,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and an f(n) value of approximately 0.95.

[0113] SEBS-OH-A and SEB-OH-A were prepared into foams as follows. SEBS-OH-A foam 100 parts of SEBS-OH-A hydroxyl-terminated hydrogenated styrene block copolymer, 0.6 phr of bis(1-(tert-butylperoxy)-1-methylethyl)-benzene (BIPB) as an organic peroxide, 3.0 phr of azodicarbonamide (AC) as a foaming agent, 10 phr of calcium carbonate, 1 phr of zinc oxide, and 1 phr of stearic acid were mixed and kneaded for 10 minutes on a roll mill having a roll face temperature of 120°C, and then the mixture was formed into a sheet shape. The amounts of BIPB, AC, calcium carbonate, zinc oxide, and stearic acid added were based on the total weight of the resin components.

[0114] The obtained sheet was filled into a press mold and then subjected to a pressure of 100 kgf / cm 2 The mixture was pressed and heated at a pressure of 175°C for about 10 minutes to obtain a foam. The size of the press mold was 10 mm thick, 150 mm long, and 150 mm wide. The foam properties were then determined according to the methods described above. The results are shown in Table 1 below.

[0115] SEB-OH-A foam 100 parts of SEB-OH-A, 0.35 parts per hundred (phr) of bis(1-(tert-butylperoxy)-1-methylethyl)-benzene (BIPB) as an organic peroxide, 3.0 phr of azodicarbonamide (AC) as a blowing agent, 10 phr of calcium carbonate, 1 phr of zinc oxide, and 1 phr of stearic acid were mixed and kneaded for 10 minutes on a roll mill having a roll surface temperature of 120°C, and then the mixture was formed into a sheet shape. The amounts of BIPB, AC, calcium carbonate, zinc oxide, and stearic acid added were based on the total weight of the resin components.

[0116] The obtained sheet was filled into a press mold and then subjected to a pressure of 100 kgf / cm 2The mixture was pressurized and heated at 175°C for about 10 minutes at a pressure of 1000 kJ / min to obtain a crosslinked foam with an expansion ratio of 160%. The size of the press mold was 10 mm thick, 150 mm long, and 150 mm wide. The foam properties were then determined according to the methods described. The results are shown in Table 1 below.

[0117] SEB-OH-A foam Foams were prepared and tested in the same manner as SEBS-OH-A, except that 100 parts SEB-OH-A, 0.35 phr BIPB, and 3.0 phr AC were used. The results are shown in Table 1 below. Both the foams of the hydroxyl-terminated hydrogenated triblock copolymer SEBS-OH-A and the foams of the hydroxyl-terminated hydrogenated diblock copolymer SEB-OH-A exhibit excellent foam properties. [Table 1]

[0118] The Examples and Comparative Examples listed in Table 3 are foam samples for evaluating the adhesion between the foam sample and a vulcanized rubber sheet. The adhesion test employed the method described above for evaluating the adhesion of foams containing hydroxyl-terminated hydrogenated block copolymers. The foam samples were prepared in a similar manner to SEBS-OH-A, except for different polymer compositions and varying BIPB and AC contents. The resin compositions and BIPB and AC contents used in the foam formulation of the foam samples are listed in Table 2. For example, Example 1 is a foam prepared by foaming a formulation containing 60 parts OBC-9530, 40 parts SEB-OH-B, 0.5 phr of BIPB, and 2.0 phr of AC.

[0119] Comparative Example 1 in Table 3 is a foam of EVA659, a resin widely used in footwear foam applications. The adhesion value is considered a benchmark for evaluating the adhesive capabilities of foam resins used in footwear foam applications.

[0120] As shown in Table 3, unlike the polar EVA659 foam, both the POE-8450 and OBC-9530 foams exhibit very low adhesion. OBC-9530, an olefin block copolymer of ethylene and 1-octene, exhibits even lower adhesion compared to POE-8450, a random copolymer of ethylene and 1-octene. As the EVA659 content increases, the adhesion of the foams of POE-8450 and its blend with OBC-9530 increases, respectively. For foams containing 40 wt% EVA, the peel adhesion values ​​of Comparative Examples 4 and 7 are still below 2 kgf / cm. Because the EVA in Comparative Example 7 is multiphase, the foam exhibits good adhesion. In Comparative Example 6, the presence of 40 wt% OBC-9530 in the blend significantly reduced adhesion.

[0121] The adhesion of foams containing hydroxyl-terminated hydrogenated diblock SEB-OH or triblock SEBS-OH all showed excellent adhesion. It was highly unexpected that foam samples containing 40 wt. % SEB-OH-B, SEB-OH-C, or SEBS-OH-B as the minority phase still achieved high adhesion. Peel adhesion testing of Example 9, which contained only SEBS-OH-C, resulted in the foam tearing due to the strong adhesive forces at the interface.

[0122] Figure 1 shows images of peeled foam samples after peel adhesion testing. It can be seen that the bonds of Comparative Examples 4 and 7 failed in an adhesive failure mode, while the bonds of Examples 5 and 8 failed in a cohesive failure mode. Specifically, the failure site for the foam containing the hydroxyl-terminated hydrogenated styrene block copolymer was within the foam itself, rather than at the adhesive interface. It is clear that the foam containing the hydroxyl-terminated hydrogenated styrene block copolymer disclosed herein, which leaves foam residue on both sides, exhibits higher bonding capacity. [Table 2] [Table 3]

[0123] Although the present disclosure has been described with reference to embodiments thereof, it should be understood that many other possible variations and modifications can be made without departing from the spirit and scope of the present disclosure as hereinafter claimed.

Claims

1. A foam obtained by foaming a resin composition, 1. The hydroxyl-terminated hydrogenated styrenic block copolymer, the hydroxyl-terminated hydrogenated styrenic block copolymer having the formula: (A-B)n-OH, (B-A)n-OH, A(B-A)n-OH, or B(A-B)n-OH is a linear block copolymer of n is 1 to 4, the A block is terminated with a hydroxyl group, the B block before hydrogenation comprises styrene monomer units, and the B block before hydrogenation comprises conjugated diene monomer units; the hydroxyl-terminated hydrogenated styrene block copolymer comprises 10 to 60 weight % of the A block, the 1,2-vinyl bond content in the conjugated diene monomer units of the hydroxyl-terminated hydrogenated styrene block copolymer is in the range of 5 to 60 mol % before hydrogenation, and after hydrogenation, 40 mol % or more of the conjugated diene monomer units are hydrogenated, and the hydroxyl-terminated hydrogenated styrene block copolymer has a weight average molecular weight of 30,000 to 200,000.

2. 2. The foam of claim 1, wherein the hydroxyl-terminated hydrogenated styrenic block copolymer is an A-B-OH or B-A-OH linear diblock copolymer.

3. 2. The foam of claim 1, wherein the hydroxyl-terminated hydrogenated styrenic block copolymer is prepared by sequential polymerization of the A block and the B block in an anionic polymerization process containing terminal hydroxyl groups, the hydroxyl groups being located either at the ends of the A block or at the ends of the B block.

4. 2. The foam of claim 1, wherein the A block is a polymer block of styrene monomer units and the B block is a polymer block of conjugated diene monomer units selected from the group consisting of butadiene units, isoprene units, and mixtures thereof.

5. 2. The foam according to claim 1, wherein the A block is a polymer block of styrene units and conjugated diene monomer units, the conjugated diene monomer units being butadiene units, isoprene units or a mixture thereof, and the content of the conjugated diene monomer units in the A block is 15% by weight or less based on the total weight of the A block.

6. 2. The foam of claim 1, wherein the A block is a polymer block of styrene units and the B block is a polymer block of butadiene units.

7. 2. The foam of claim 1, wherein the B block is a polymer block of butadiene and styrene units, the styrene units being 20% ​​or less by weight based on the total weight of the B block.

8. The foam according to claim 4, wherein the 1,2-vinyl bond content in the butadiene units is in the range of 5 to 60 mol % before hydrogenation.

9. The foam according to claim 5, wherein the 1,2-vinyl bond content in the butadiene units is in the range of 5 to 60 mol % before hydrogenation.

10. The foam according to claim 6, wherein the 1,2-vinyl bond content in the butadiene units is in the range of 5 to 60 mol % before hydrogenation.

11. The foam according to claim 7, wherein the 1,2-vinyl bond content in the butadiene units is in the range of 5 to 60 mol % before hydrogenation.

12. The foam according to claim 4, wherein the 3,4-vinyl bond content of the isoprene units is in the range of 5 to 60 mol % before hydrogenation.

13. The foam according to claim 5, wherein the 3,4-vinyl bond content of the isoprene units is in the range of 5 to 60 mol % before hydrogenation.

14. 10. The foam of claim 1, wherein from 60 to 95 mole percent of the conjugated diene monomer units are hydrogenated after hydrogenation.

15. A foam obtained by foaming a resin composition, (a) a hydroxyl-terminated hydrogenated styrene block copolymer having the formula: (A-B)n-OH, (B-A)n-OH, A(B-A)n-OH, or B(A-B)n-OH is a linear block copolymer of n is 1 to 4, the A block is terminated with a hydroxyl group, the B block before hydrogenation comprises styrene monomer units, and the B block before hydrogenation comprises conjugated diene monomer units; the hydroxyl-terminated hydrogenated styrene block copolymer comprises 10 to 60 weight % of the A block, the 1,2-vinyl bond content in the conjugated diene monomer units of the hydroxyl-terminated hydrogenated styrene block copolymer is in the range of 5 to 60 mol % before hydrogenation, and after hydrogenation, 40 mol % or more of the conjugated diene monomer units are hydrogenated, and the hydroxyl-terminated hydrogenated styrene block copolymer has a weight average molecular weight of 30,000 to 200,000; (b) an ethylene-based copolymer; wherein the weight ratio of said hydroxyl-terminated hydrogenated styrene block copolymer to said ethylene-based copolymer is from 90 / 10 to 10 / 90.

16. The foam according to claim 15, wherein the ethylene-based copolymer is an ethylene-vinyl acetate copolymer, an olefin block copolymer having a polymer block of ethylene units, an ethylene-α-olefin random copolymer, polyethylene, or a combination thereof.

17. 16. The foam of claim 15, wherein the ethylene-based copolymer is an ethylene-vinyl acetate copolymer, and the vinyl acetate content of the ethylene-vinyl acetate copolymer is in the range of 15 to 40 wt%, based on the total weight of the ethylene-vinyl acetate copolymer.

18. The foam according to claim 15, wherein the ethylene-based copolymer is an ethylene-α-olefin-based random copolymer comprising ethylene units and octene units.

19. 16. The foam of claim 15, wherein the ethylene-based copolymer is an olefin block copolymer comprising polymer blocks of octene units.

20. 16. The foam of claim 15, wherein the ethylene-based copolymer is an olefin block copolymer having a melt temperature in the range of 110°C to 130°C and a density in the range of 0.875 g / cc to 0.945 g / cc.

21. A foam obtained by foaming a resin composition, (a) a hydroxyl-terminated hydrogenated styrene block copolymer having the formula: (A-B)n-OH, (B-A)n-OH, A(B-A)n-OH, or B(A-B)n-OH is a linear block copolymer of n is 1 to 4, the A block is terminated with a hydroxyl group, the B block before hydrogenation comprises styrene monomer units, and the B block before hydrogenation comprises conjugated diene monomer units; the hydroxyl-terminated hydrogenated styrene block copolymer comprises 10 to 60 weight % of the A block, the 1,2-vinyl bond content in the conjugated diene monomer units of the hydroxyl-terminated hydrogenated styrene block copolymer is in the range of 5 to 60 mol % before hydrogenation, and after hydrogenation, 40 mol % or more of the conjugated diene monomer units are hydrogenated, and the hydroxyl-terminated hydrogenated styrene block copolymer has a weight average molecular weight of 30,000 to 200,000; (b) a polar thermoplastic elastomer; and wherein the weight ratio of said hydroxyl terminated hydrogenated styrenic block copolymer to said polar thermoplastic elastomer is from 90 / 10 to 10 / 90.

22. 22. The foam of claim 21, wherein the polar thermoplastic elastomer is a thermoplastic polyurethane (TPU), a thermoplastic polyester elastomer (TPEE), a polyether block amide (PEBA), or a combination thereof, the polar thermoplastic elastomer having a hardness measured on Shore A ranging from 60A to 90A and a melting temperature ranging from 140°C to 200°C.

23. 2. The foam according to claim 1, obtained by a process comprising injection molding the resin composition in an injection mold, the process comprising: Crosslinking the resin composition using an organic peroxide initiator and foaming the resin composition using a chemical foaming agent. Including, The crosslinking temperature in the injection mold is about 150°C to about 200°C.

24. 24. The foam of claim 23, wherein the organic peroxide initiator is bis(1-(tert-butylperoxy)-1-methylethyl)-benzene.

25. 24. The foam of claim 23, wherein the chemical blowing agent is azodicarbonamide.

26. 24. The foam of claim 23, wherein a crosslinking coagent or functional chain extender is further used in crosslinking the resin composition, the functional chain extender having at least one functional group selected from the group consisting of anhydride, epoxy, and isocyanate to react with the terminal hydroxyl groups of the hydroxyl-terminated hydrogenated styrenic block copolymer.

27. 0.1~0.5g / cm ３ 24. The foam of claim 23, having a foam density in the range of 100%, a rebound resilience in the range of 50% to 80%, and a hardness (Asker C) in the range of 20 to 70.

28. 13. An article made from the foam of claim 1 which is a component of footwear.

29. 30. The article of claim 28, wherein the footwear component is a midsole.

30. A resin composition comprising:

1. The hydroxyl-terminated hydrogenated styrenic block copolymer, the hydroxyl-terminated hydrogenated styrenic block copolymer having the formula: (A-B)n-OH, (B-A)n-OH, A(B-A)n-OH, or B(A-B)n-OH is a linear block copolymer of n is 1 to 4, the A block is terminated with a hydroxyl group, the B block before hydrogenation comprises styrene monomer units, and the B block before hydrogenation comprises conjugated diene monomer units; the hydroxyl-terminated hydrogenated styrene block copolymer comprises 10 to 60 weight % of the A block, the 1,2-vinyl bond content in the conjugated diene monomer units of the hydroxyl-terminated hydrogenated styrene block copolymer is in the range of 5 to 60 mol % before hydrogenation, and after hydrogenation, 40 mol % or more of the conjugated diene monomer units are hydrogenated, and the hydroxyl-terminated hydrogenated styrene block copolymer has a weight average molecular weight of 30,000 to 200,000.

31. The resin composition according to claim 30, further comprising an ethylene-based copolymer.

32. 31. Use of the resin composition according to claim 30 for preparing a foam.

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