Cross-linkable foaming composition, foams obtained using the same, foaming composition and use thereof

Abstract

The present application provides a cross-linkable foaming composition, comprising a hydrogenated styrene diblock copolymer, a free radical initiator and a foaming agent, wherein the hydrogenated styrene diblock copolymer comprises a first block comprising an isoprene unit and a second block comprising a styrene unit, wherein the hydrogenated styrene diblock copolymer comprises 10 to 60 wt% of the styrene unit, 50 mol% or more of the isoprene unit is hydrogenated, and the weight average molecular weight of the hydrogenated styrene diblock copolymer is between 30,000 and 200,000. Furthermore, the present application also provides a foam obtained by cross-linking and foaming the aforementioned cross-linkable foaming composition, a foaming composition and uses thereof.

Description

TECHNICAL FIELD

[0001] The present invention relates to a cross-linkable foaming composition and a foam obtained by cross-linking foaming the aforementioned cross-linkable foaming composition, a foaming composition and use thereof. BACKGROUND

[0002] There are a wide variety of materials used to make shoe soles, among which rubber is the most popular. Rubber-soled shoes have unparalleled wear resistance and exhibit great elongation and contraction in all seasons, such as walking on wet sidewalks or snow-covered streets. Thermoplastic materials are also used for shoe outsoles. For example, outsoles made of PVC are flexible and inexpensive, but can be slippery. Thermoplastic elastomer (TPE) materials, which behave like vulcanized rubber at room temperature but can be melt-processed at high temperatures. The most commonly used TPE material in shoe sole production is styrene block copolymer (SBC), such as styrene-butadiene-styrene (SBS) triblock copolymer and thermoplastic polyurethane (TPU).

[0003] In order to obtain lightweight foams, foams of ethylene-vinyl acetate (EVA), for example, are also used as shoe outsoles. EVA is widely used to manufacture foamed products, mainly as midsole parts in footwear applications. However, for the use of outsoles, EVA foams have some limitations, such as poor slip resistance, which hinders the widespread use of EVA foams as footwear outsoles. Mixtures of various materials are often used to prepare foams with improved slip resistance. For example, CN104693564B discloses an expandable composition comprising brominated butyl rubber (BIIR), EVA and low-density polyethylene (LDPE) for manufacturing shoe sole foams with high damping and slip resistance.

[0004] Among TPE materials, SBCs such as SBS and SEBS (hydrogenated SBS) are the only ones that can be made into lightweight foams in a traditional footwear foam manufacturing process, which first adds a peroxide initiator and a chemical foaming agent at a temperature below about 120°C, then molds the foaming composition to cross-link the foaming composition in a mold, and then foams at a temperature of about 140°C to 190°C. Since SBC materials generally have good wear resistance and slip resistance, foams with SBC as the main component are being developed as shoe sole foams. For example, CN106349633B discloses an expandable composition mainly comprising SEBS, as well as a small amount of LDPE, olefin block copolymer (OBC) and styrene-butadiene rubber (SBR), for manufacturing foams with good dry and wet slip resistance. For another example, CN102888067B discloses an elastic and slip-resistant elastic foam material mainly comprising an SEBS composition, and including PP (polypropylene), EVA, inorganic fillers and a small amount of filling oil.

[0005] In view of the trend toward the use of light-weight foams as outsoles for contact with the ground, there remains a need to develop new types of foaming resins to produce foams having enhanced slip-resistance properties and overall balanced mechanical properties suitable for use on footwear outsoles. Moreover, in view of the dominance of EVA foams for footwear applications, there remains a need to modify EVA foams to improve slip-resistance properties. SUMMARY

[0006] The present invention has two objectives. The first objective is to develop a styrene block copolymer resin whose foams have balanced mechanical properties, especially excellent slip-resistance properties important for footwear outsoles, wherein the foaming process steps of the foams are the introduction of a free radical initiator and a blowing agent into a cross-linkable foaming composition at a temperature of about 120°C or below, followed by injection molding of the cross-linkable foaming composition in an injection mold for peroxide cross-linking and blowing agent decomposition at a temperature of about 150°C to 200°C.

[0007] The second objective is to develop a styrene block copolymer resin that can be blended with an ethylene copolymer, such as EVA, to make foams that have the advantages of both materials, especially excellent slip-resistance properties important for footwear outsole applications.

[0008] Although not limited by theory, the present invention is based on the discovery that hydrogenated styrene-isoprene diblock copolymers are best suited to achieve the objectives of the present invention as described above. Foams comprising hydrogenated styrene-isoprene diblock copolymers have desirable slip-resistance properties suitable for use as shoe outsoles.

[0009] Moreover, the present invention is based on the discovery that the polymer structure of hydrogenated styrene-isoprene diblock copolymers is best suited for the foaming mixing and injection process of adding a peroxide initiator and a blowing agent at a temperature of about 120°C or below, followed by peroxide cross-linking of the mixture in a mold at a temperature of about 150°C to 200°C.

[0010] The following will be further described in detail.

[0011] In general practice, SBCs are first prepared as diblock copolymers of a styrene hard block and a soft block such as butadiene or isoprene by anionic polymerization, followed by coupling or sequential polymerization to form linear A-B-A type or star-shaped multiblock copolymers. Hydrogenated SBCs, such as SEBS, further improve mechanical properties and weather resistance. SBC block copolymers, as a class of TPEs, are widely used in many applications including footwear foams. Hydrogenated SBCs, such as hydrogenated SEBS, are preferred for footwear foam applications. Partially hydrogenated SEBS is best suited for footwear foams because the residual unsaturation in the soft block aids peroxide cross-linking.

[0012] In the case of the A-B type styrene diblock copolymer, the styrene hard block does not bundle to form physical crosslinking as in the case of the multi-block copolymer. It does not have the characteristics of a thermoplastic elastomer, such as elasticity. In short, the styrene diblock copolymer is not considered a thermoplastic elastomer, and its commercial use is limited. For example, there are very few commercial products of styrene diblock copolymers available from global SBC manufacturers. Styrene diblock copolymers are most commonly used in adhesives, coatings, or modifiers, where mechanical strength and elasticity are not the most important. Unexpectedly and surprisingly, the A-B type hydrogenated styrene-isoprene diblock copolymer can be well mixed and foamed into a foam having excellent slip resistance properties.

[0013] In addition, the difference in structure between the triblock copolymer and the diblock copolymer is beneficial in terms of the effect of peroxide curing, which is a key process for increasing the strength of the foamed melt. In the case of the triblock SEBS, chemical crosslinking by peroxide crosslinking is introduced into the pre-existing physical crosslinking of the SEBS in the melting stage. On the other hand, the styrene diblock copolymer does not have a pre-existing physical crosslinking network. In peroxide crosslinking, new crosslinks are formed by peroxide crosslinking, and all loose styrene blocks are bound in the crosslinks. In short, the crosslinking results show that the peroxide crosslinking of the styrene diblock copolymer not only serves to provide chemical crosslinking by peroxide crosslinking, but also forms a physical crosslinking network. Surprisingly, peroxide crosslinking converts the styrene-isoprene diblock copolymer into a suitable foaming resin for obtaining excellent slip resistance properties.

[0014] In addition, the styrene-isoprene diblock copolymer has good compatibility with other ethylene copolymers, such as EVA, which is important for producing a foam containing different polymers. It is known that A-B type diblock copolymers have better self-assembly ability, which is derived from the thermodynamic incompatibility between the A-B two blocks of the copolymer. This is also the reason why A-B diblock copolymers are often used as compatibilizers for two different polymers.

[0015] According to the purpose of the present application, the present application provides a crosslinkable foaming composition, a foam obtained by crosslinking and foaming the same, and a method for preparing the same, as described below.

[0016] The present application provides a cross-linkable foaming composition including a hydrogenated styrene diblock copolymer, a radical initiator, and a blowing agent. The hydrogenated styrene diblock copolymer includes a first block including an isoprene unit and a second block including a styrene unit. The hydrogenated styrene diblock copolymer includes 10 to 60 wt% of the styrene unit, 50 mol% or more of the isoprene unit is hydrogenated, and the weight average molecular weight of the hydrogenated styrene diblock copolymer is between 30,000 and 200,000. The present application also provides a foamed body or a shoe part cross-linked and foamed from the aforementioned cross-linkable foaming composition. Thus, the resulting foamed body or shoe part includes the hydrogenated styrene diblock copolymer and has the characteristics of the aforementioned hydrogenated styrene diblock copolymer.

[0017] The present application also provides another cross-linkable foaming composition including a hydrogenated styrene diblock copolymer, an ethylene copolymer, a radical initiator, and a blowing agent. The hydrogenated styrene diblock copolymer has the characteristics as described above. In addition, the weight ratio of the ethylene copolymer to the hydrogenated styrene diblock copolymer is between 50 / 50 and 95 / 5. The present application also provides a foamed body or a shoe part cross-linked and foamed from the aforementioned cross-linkable foaming composition. Thus, the resulting foamed body or shoe part includes the hydrogenated styrene diblock copolymer and the ethylene copolymer and has the characteristics of the aforementioned hydrogenated styrene diblock copolymer and the weight ratio of the ethylene copolymer to the hydrogenated styrene diblock copolymer.

[0018] The present application also provides a foaming composition including a hydrogenated styrene diblock copolymer. The hydrogenated styrene diblock copolymer has the characteristics as described above. In addition, the present application also provides the use of the aforementioned composition for preparing a foamed body.

[0019] The details of one or more embodiments of the application are set forth in the description below. Other features, objects, and advantages of the application will be apparent from the description and from the claims. DETAILED DESCRIPTION

[0020] Different embodiments of the present application are provided below. These embodiments are used to illustrate the technical content of the present application, but are not used to limit the scope of rights of the present application. A feature of an embodiment can be applied to other embodiments by suitable modification, substitution, combination, or separation.

[0021] It should be noted that, in this document, unless specifically indicated otherwise, having "a" component does not limit to having a single component, but can have one or more components.

[0022] In this document, the terms "comprises", "comprising", "includes", "including", "has", "having" or "contains", "containing" or "consists of" means "including but not limited to", unless otherwise specified.

[0023] As used herein and unless otherwise indicated, the term "about" or "approximately" means an acceptable limit of error for a particular value as determined by one of ordinary skill in the art which depends in part on how the value is measured or determined. In certain embodiments, the term "about" or "approximately" means within 1, 2, 3, or 4 standard deviations. In certain embodiments, the terms "about" and "approximately" mean within ±20%, within ±15%, within ±10%, within ±9%, within ±8%, within ±7%, within ±6%, within ±5%, within ±4%, within ±3%, within ±2%, within ±1%, within ±0.5%, within ±0.05%, or lower of a given value or range. Where a given number is an approximate number, the meaning of "about" or "approximately" is also implied where not specifically stated. Furthermore, the phrases "ranging / ranges between" a first and a second value of an included range are intended to include the first and second values, and that any intervening sub-ranges. It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

[0024] Furthermore, features of different embodiments of the present application can be combined to form another embodiment.

[0025] In some embodiments, the cross-linkable foaming composition can include a hydrogenated styrene diblock copolymer, a free radical initiator, and a foaming agent. The hydrogenated styrene diblock copolymer can include a first block including isoprene units and a second block including styrene units. The hydrogenated styrene diblock copolymer can include 10 to 60 wt% of styrene units, 50 mol% or more of isoprene units can be hydrogenated, and the weight average molecular weight of the hydrogenated styrene diblock copolymer can be between 30,000 and 200,000.

[0026] In some embodiments, the cross-linkable foaming composition can include a hydrogenated styrene diblock copolymer, an ethylene copolymer, a free radical initiator, and a foaming agent. The hydrogenated styrene diblock copolymer can be as described above. In addition, the weight ratio of the ethylene copolymer to the hydrogenated styrene diblock copolymer can be between 50 / 50 and 95 / 5.

[0027] In some embodiments, a foamed body cross-linked and foamed from any of the aforementioned cross-linkable foaming compositions is provided.

[0028] In some embodiments, a shoe component crosslinked and foamed from any of the aforementioned crosslinkable foaming compositions is provided.

[0029] In some embodiments, the foaming composition can include a hydrogenated styrene diblock copolymer. The hydrogenated styrene diblock copolymer is characterized as described above and will not be repeated.

[0030] In some embodiments, the aforementioned foaming composition is used to prepare a foam.

[0031] Next, the components of the aforementioned crosslinkable foaming composition, the foam or shoe component crosslinked and foamed from the aforementioned crosslinkable foaming composition, and the method of preparing the same will be described in detail. In addition, the components of the aforementioned foaming composition will also be described in detail.

[0032] Hydrogenated styrene diblock copolymer

[0033] The hydrogenated styrene diblock copolymer of the present application is a diblock copolymer including a first block including isoprene units and a second block including styrene units.

[0034] In some embodiments, the hydrogenated styrene diblock copolymer can include about 10 to 60 wt% of styrene units, based on the total weight of the hydrogenated styrene diblock copolymer. When a crosslinked foam is prepared using a crosslinkable foaming composition having less than 10 wt% of styrene units, the resulting crosslinked foam has poor mechanical properties (e.g., delamination tear strength). When a crosslinked foam is prepared using a crosslinkable foaming composition having more than 60 wt% of styrene units, the resulting crosslinked foam has poor compression set or impact resilience.

[0035] In some embodiments, in order to obtain a crosslinked foam having balanced mechanical properties, the hydrogenated styrene diblock copolymer can include about 10 to 50 wt% of styrene units, based on the total weight of the hydrogenated styrene diblock copolymer, and the remaining portion of the hydrogenated styrene diblock copolymer is conjugated diene monomer units. Within this range, the crosslinked foam is expected to have balanced mechanical properties and excellent slip resistance properties. In some embodiments, the hydrogenated styrene diblock copolymer can include about, for example, 10 to 55 wt%, 15 to 55 wt%, 15 to 50 wt%, 18 to 50 wt%, 18 to 45 wt%, 18 to 40 wt%, 18 to 35 wt%, or 18 to 33 wt% of styrene units, and the remaining portion of the hydrogenated styrene diblock copolymer is conjugated diene monomer units.

[0036] In some embodiments, about 50 mol% or more of the isoprene units in the hydrogenated styrene diblock copolymer are hydrogenated after hydrogenation. In some embodiments, about 50 to 100 mol% of the isoprene units are hydrogenated after hydrogenation. In some embodiments, for example, about 55 to 100 mol%, 60 to 100 mol%, 65 to 100 mol%, 70 to 100 mol%, 75 to 100 mol%, or 75 to 99 mol% of the isoprene units are hydrogenated after hydrogenation. If the degree of hydrogenation is less than 50 mol%, it is difficult to manufacture due to too strong adhesion to the metal surface.

[0037] In some embodiments, the weight average molecular weight of the hydrogenated styrene diblock copolymer can be about 30,000 to 200,000. If the weight average molecular weight of the hydrogenated styrene diblock copolymer is less than 30,000, the hydrogenated styrene diblock copolymer can result in a foam having poor mechanical properties. If the weight average molecular weight of the hydrogenated styrene diblock copolymer exceeds 200,000, it is difficult to process the hydrogenated styrene diblock copolymer.

[0038] In some embodiments, the weight average molecular weight of the hydrogenated styrene diblock copolymer can be about, for example, 40,000 to 200,000, 50,000 to 200,000, 60,000 to 200,000, 70,000 to 200,000, 70,000 to 190,000, 70,000 to 180,000, 70,000 to 170,000, 70,000 to 160,000, 70,000 to 150,000, 70,000 to 140,000, 80,000 to 140,000, 80,000 to 130,000, 90,000 to 130,000, or 100,000 to 130,000.

[0039] In some embodiments, the first block can be a polymer block of isoprene units. In some embodiments, the first block can be a polymer block of isoprene units and butadiene units, wherein the content of butadiene units is less than or equal to 15 mol% of the total weight of the first block

[0040] In some embodiments, the second block can be a polymer block of styrene units. In some embodiments, the second block can be a polymer block of styrene units and conjugated diene monomer units, where the content of the conjugated diene monomer units can be less than or equal to 15 wt% of the total weight of the second block. In some embodiments, the content of the conjugated diene monomer units can be in a range from about 0.5 to 15 wt%, 0.5 to 14 wt%, 0.5 to 13 wt%, 0.5 to 12 wt%, 0.5 to 11 wt%, or 0.5 to 10 wt% of the total weight of the second block. The conjugated diene monomer units can be butadiene units, isoprene units, or mixtures thereof. In some embodiments, the second block can be a polymer block of styrene units and butadiene units, where the content of the butadiene units can be less than or equal to 10 wt% of the total weight of the second block. When the second block is a polymer block containing a small amount (less than or equal to 15 wt%) of conjugated diene monomer units, the flowability of the hydrogenated styrene diblock copolymer can be improved.

[0041] In some embodiments, the first block can be a polymer block of isoprene units, and the second block can be a polymer block of styrene units.

[0042] In some embodiments, the first block can be a polymer block of isoprene units and butadiene units, where the content of the butadiene units can be less than or equal to 15 mol% of the total weight of the first block, and the second block can be a polymer block of styrene units.

[0043] In some embodiments, the first block can be a polymer block of isoprene units, and the second block can be a polymer block of styrene units and conjugated diene monomer units, where the conjugated diene monomer units can be butadiene units, isoprene units, or mixtures thereof, and the content of the conjugated diene monomer units can be less than or equal to 15 wt% of the total weight of the second block.

[0044] In some embodiments, the first block can be a polymer block of isoprene units and butadiene units, where the content of the butadiene units can be less than or equal to 15 mol% of the total weight of the first block, and the second block can be a polymer block of styrene units and conjugated diene monomer units, where the conjugated diene monomer units can be butadiene units, isoprene units, or mixtures thereof, and the content of the conjugated diene monomer units can be less than or equal to 15 wt% of the total weight of the second block.

[0045] In some embodiments, for example, when the first block and / or the second block include isoprene units, the content of 3,4-vinyl bonds of the isoprene units can be between about 5 and 40 mol% prior to hydrogenation. In some embodiments, the content of 3,4-vinyl bonds of the isoprene units can be between about, for example, 5 and 35 mol%, 5 and 30 mol%, 5 and 25 mol%, 5 and 20 mol%, or 5 and 15 mol% prior to hydrogenation.

[0046] In some embodiments, for example, when the first block and / or the second block include butadiene units, the content of 1,2-vinyl bonds of the conjugated diene monomer units (i.e., butadiene) can be between 5 and 40 mol% prior to hydrogenation.

[0047] In this context, the term "vinyl bond" is used to describe the polymer product when 1,3-butadiene is polymerized by the 1,2-addition mechanism and isoprene is polymerized by the 3,4-addition mechanism. The result is a monosubstituted olefinic group pendant to the polymer backbone, i.e., a vinyl group. In the case of anionic polymerization of isoprene, insertion of isoprene by the 3,4-addition mechanism provides a structure with a dialkyl C=C group pendant to the polymer backbone. The 3,4-addition polymerization of isoprene has a similar effect on the final properties of the block copolymer as the 1,2-addition of butadiene.

[0048] The method for preparing the styrene diblock copolymer prior to hydrogenation is not particularly limited and any known method can be used. In the polymerization method, living anionic polymerization can be used, which is carried out in a hydrocarbon solvent and initiated by an organic alkali metal compound. For example, the above polymerization step is specifically described in U.S. Patent No. 3823203. The hydrocarbon solvent is not particularly limited and any known solvent can be used. For example, the hydrocarbon solvent can include aliphatic hydrocarbons such as n-hexane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as xylene. The above hydrocarbon solvents can be used alone or in combination of two or more.

[0049] The initiator is not particularly limited and any known initiator having anionic polymerization activity for a vinyl aromatic monomer (e.g., styrene) and a conjugated diene monomer (e.g., isoprene) can be used, for example, aliphatic alkali metal compounds, aromatic alkali metal compounds, and organic amino alkali metal compounds. The alkali metal used as the initiator can include lithium, sodium, and potassium. In some embodiments, the initiator can be an aliphatic alkali metal, for example, n-butyllithium.

[0050] The polymerization process for preparing the styrene diblock copolymer can be carried out similarly to those used for anionic polymerization. The polymerization reaction can be carried out at a temperature of about 0°C to about 180°C, more preferably about 30°C to about 150°C, most preferably about 30°C to about 90°C. The polymerization reaction is carried out in an inert atmosphere, preferably in nitrogen, and can also be carried out at a pressure ranging from about 0.5 to about 10 bar. The polymerization process generally requires less than 12 hours, depending on the temperature, concentration of monomer composition, polymer molecular weight, etc.

[0051] The hydrogenation of the styrene diblock copolymer can be carried out using known hydrogenation methods. For example, it can be accomplished using methods as described in U.S. Patent Nos. 3,595,942 and 3,700,633. These hydrogenation methods use a suitable catalyst. The catalysts mentioned can comprise a metal of Group VIII of the Periodic Table of the Elements (e.g., nickel or cobalt) and are used in conjunction with a suitable reducing agent, such as an alkyl aluminum or a hydride of a metal selected from Groups I-A, II-A, and III-B of the Periodic Table of the Elements, particularly lithium, magnesium, or aluminum.

[0052] The hydrogenation process is not particularly limited, and is generally carried out at a temperature of 0°C to 180°C, more preferably 30°C to 150°C. The hydrogen pressure used in the process is not particularly limited, and is generally 0.1 to 20 MPa, 0.2 to 15 MPa, or 0.3 to 5 MPa. The reaction time is generally 1 minute to 10 hours or 10 minutes to 5 hours.

[0053] The hydrogenation process can be carried out by a batch process, a continuous process, or a combination thereof. If necessary, the catalyst residue can be removed. The hydrogenated polymer can be separated by pouring into hot water while stirring, and the organic solvent can be removed by stripping.

[0054] The basic synthesis method for preparing the hydrogenated styrene-isoprene diblock copolymer is briefly described herein. First, cyclohexane as a solvent and n-butyllithium as a starter are introduced into a reactor equipped with a heater and a stirrer. Second, isoprene is added to the solvent to perform anionic polymerization. In the third step, styrene is added to the reactor, and the reaction mixture is further polymerized to form a styrene isoprene diblock copolymer structure. The block copolymer is then hydrogenated using a nickel 2-ethylhexanoate / TEAL catalyst and hydrogen gas in a pressure vessel. The hydrogenation reaction is terminated after about 50 mol% or more of the isoprene units are hydrogenated. The resulting styrene-isoprene diblock copolymer is washed with hot acidic water to remove the residual catalyst.

[0055] In some embodiments, the microstructure of the isoprene segments of the hydrogenated styrene di-block copolymer, such as the vinyl bond content and styrene content before hydrogenation and the hydrogenation degree after hydrogenation, can be measured using proton nuclear magnetic resonance (1H-NMR). In addition, the weight average molecular weight can be determined using gel permeation chromatography (GPC).

[0056] In addition, for the purpose of improving the properties of the foam, the hydrogenated styrene-isoprene di-block copolymer of the present application can contain up to 20 wt% of a hydrogenated styrene multi-block copolymer, such as SEPS tri-block, of similar composition. The styrene-isoprene multi-block copolymer can have a styrene content of 10 to 40 wt%, a weight average molecular weight of about 30,000 to 80,000, a 3,4-vinyl bond content of the isoprene units of 10 to 30 mol% before hydrogenation, and a hydrogenation degree of the isoprene units of 60 to 95 mol%. The weight ratio of the hydrogenated styrene multi-block copolymer to the hydrogenated styrene di-block copolymer is related to the foaming properties required by the foaming process and the final application.

[0057] Ethylene copolymer

[0058] In some embodiments of the present application, the cross-linkable foaming composition can contain the aforementioned hydrogenated styrene di-block copolymer and ethylene copolymer.

[0059] In some embodiments, the weight ratio of the ethylene copolymer to the hydrogenated styrene di-block copolymer can be between 50 / 50 and 95 / 5. In some embodiments, the weight ratio of the ethylene copolymer to the hydrogenated styrene di-block copolymer can be between, for example, 50 / 50 and 90 / 10, 60 / 40 and 90 / 10, 65 / 35 and 90 / 10, or 70 / 30 and 90 / 10.

[0060] In the present application, the ethylene copolymer is not particularly limited and known ethylene copolymers can be used. For example, suitable ethylene copolymers can include polyethylene (PE), ethylene-vinyl acetate copolymer (EVA) obtainable by copolymerization of ethylene and vinyl acetate, ethylene-α-olefin copolymer obtainable by random or block copolymerization of ethylene and C3-10 α-olefin, or a combination thereof.

[0061] In some embodiments, the ethylene copolymer can be polyethylene, which can be high density polyethylene, low density polyethylene, or a combination thereof.

[0062] In some embodiments, the ethylene copolymer can be ethylene-vinyl acetate copolymer, and the content of vinyl acetate can be about 15 to 40 wt% based on the total weight of the ethylene copolymer. In some embodiments, the content of vinyl acetate can be about 15 to 35 wt%, 15 to 30 wt%, 18 to 30 wt%, or 20 to 30 wt% based on the total weight of the ethylene copolymer.

[0063] In some embodiments, the ethylene copolymer can be an ethylene-a-olefin copolymer, where the a-olefin can include 1-butene, 1-pentene, 1-hexene, 1-octene, the like, or a combination thereof.

[0064] Radical initiator

[0065] In some embodiments of the present application, the cross-linkable foamable composition can further include a radical initiator. There is no particular limitation on the radical initiator used to cross-link the cross-linkable foamable composition, and any known radical initiator can be used.

[0066] In some embodiments, the radical initiator can be an organic peroxide.

[0067] In some embodiments, the organic peroxide can be selected from the group consisting of dicumyl peroxide, 2,5-dimethyl-2,5-di-(t-butyl peroxy)hexane, bis(1-(tert-butylperoxy)-1-methylethyl)-benzene, and a combination thereof. In some embodiments, the organic peroxide can be bis(1-(tert-butylperoxy)-1-methylethyl)-benzene. However, the present application is not limited thereto.

[0068] There is no particular limitation on the amount of the radical initiator used. In some embodiments, the amount of the radical initiator used can be about 0.01 to 10 wt%, 0.01 to 9 wt%, 0.01 to 8 wt%, 0.01 to 7 wt%, 0.01 to 6 wt%, 0.01 to 5 wt%, 0.01 to 4 wt%, 0.05 to 4 wt%, 0.05 to 3 wt%, 0.1 to 3 wt%, 0.1 to 2.5 wt%, 0.1 to 2 wt%, 0.1 to 1.5 wt%, or 0.1 to 1 wt%, based on the total weight of the cross-linkable foamable composition.

[0069] Blowing agent

[0070] In some embodiments of the present application, the cross-linkable foamable composition can further include a blowing agent. There is no particular limitation on the blowing agent, and any known blowing agent can be used. For example, the blowing agent can be a chemical blowing agent, a physical blowing agent, or a combination thereof.

[0071] In some embodiments, the blowing agent is a chemical blowing agent.

[0072] In some embodiments, the blowing agent can include an organic blowing agent, such as azodicarbonamide (ADCA), bis(l-(tert-butylperoxy)-l-methylethyl)-benzene, 4,4'-oxybis(benzenesulfonylhydrazide), p-toluenesulfonylsemicarbazide, N,N'-dinitrosopentamethylenetetramine, diphenylsulfone-3,3'-disulfonyl hydrazide (DPSDSH), trihydrazotriazine, or a combination thereof; or an inorganic thermally decomposable blowing agent, such as sodium bicarbonate, ammonium bicarbonate, sodium carbonate, ammonium carbonate, or a combination thereof. In some embodiments, the organic blowing agent and the inorganic thermally decomposable blowing agent can be used alone or in combination. In some embodiments, the blowing agent can be azodicarbonamide. However, the present application is not limited thereto.

[0073] The amount of the blowing agent is not particularly limited. In some embodiments, the amount of the blowing agent can be about 0.5 to 10 wt%, 0.5 to 9 wt%, 0.5 to 8 wt%, 0.5 to 7 wt%, 0.5 to 6 wt%, 0.5 to 5 wt%, or 1 to 5 wt%, based on the total weight of the cross-linkable foaming composition.

[0074] In some embodiments, the blowing agent can be a physical blowing agent, such as nitrogen, carbon dioxide, alkanes, cycloalkanes, dialkyl ethers, cycloalkyl ethers, fluoroalkanes, hydrofluoroolefins, hydrochlorofluoroolefins, or a combination thereof.

[0075] Other additives

[0076] In some embodiments of the present application, if desired, the cross-linkable foaming composition can further optionally include other additives, such as a cross-linking co-agent, an organometallic compound, a filler, a heat stabilizer, a weathering stabilizer, a pigment, and the like, in addition to the aforementioned components. However, the present application is not limited thereto.

[0077] In some embodiments of the present application, to accelerate the rate of crosslinking reaction, the crosslinkable foaming composition can further comprise a crosslinking co-agent. For example, the crosslinking co-agent can include, but is not limited to, triallylisocyanurate, triallyl cyanurate, ethylene glycol dimethacrylate, vinyl butyrate, and the like.

[0078] In some embodiments of the present application, to make the crosslinked foam cell more fine or more uniform, the crosslinkable foaming composition can further comprise an organometallic compound. For example, the organometallic compound can include, but is not limited to, zinc diacrylate or zinc dimethacrylate, which can also serve as a crosslinking co-agent.

[0079] In some embodiments of the present application, to save cost, adjust hardness, modulus, or nucleation, the crosslinkable foaming composition can further comprise a filler. For example, the filler can include, but is not limited to, clay, silica, talc, titanium dioxide, zinc oxide, calcium carbonate, and the like.

[0080] In some embodiments of the present application, to increase the durability of the foamed product, the crosslinkable foaming composition can further comprise a heat stabilizer, a weather stabilizer, or a combination thereof. For example, the heat stabilizer can include, but is not limited to, phosphorus-based heat stabilizers such as Irgafos 168. For example, the weather stabilizer can include, but is not limited to, hindered phenol-based weather stabilizers such as pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate].

[0081] In some embodiments of the present application, the crosslinkable foaming composition can further comprise a pigment. For example, the pigment can include, but is not limited to, azo-based pigments, phthalocyanine-based pigments, oxide-based pigments, chromate-based pigments, molybdate-based pigments, inorganic pigments, or carbon black.

[0082] Preparation of the crosslinkable foaming composition

[0083] The cross-linkable foaming composition of the present application can be prepared by melt blending the aforementioned hydrogenated styrene diblock copolymer, ethylene copolymer or combination thereof using a kneader, followed by addition of a radical initiator and a blowing agent, and other additives (e.g. a filler) can be added. The operation is conducted at a temperature below 120°C before the addition of the radical initiator and the blowing agent to avoid premature decomposition of the radical initiator or the blowing agent.

[0084] The method of melt blending is not particularly limited and known methods can be used. For example, extrusion devices such as single screw extruders, twin screw extruders, multi screw extruders, Henschel mixers, Banbury mixers, roll mills and kneaders can be used in the present application. In some embodiments, the melt blending is performed using a kneader.

[0085] The shape of the cross-linkable foaming composition of the present application is not particularly limited after the step of melt blending. For example, it can be shaped into a granular form, a sheet form, a strip form, a disc form, etc. For example, the components can be mixed and formed into granules by a granulator or similar machine. For example, after kneading the components of the composition, a roll mill can be used to form a sheet. In this way, an uncross-linked and unfoamed expandable sheet can be produced, wherein the expandable sheet comprises any of the aforementioned cross-linkable foaming compositions.

[0086] Preparation of cross-linked foams

[0087] The cross-linkable foaming composition provided by the present application can be cross-linked and foamed to obtain the foams of the present application.

[0088] The method of cross-linking and foaming is not particularly limited and can be any known method. Here, an example of cross-linking and foaming the cross-linkable foaming composition of the present application by pressing the composition into a sheet form is provided. The cross-linking and foaming sheet is cut to a size of 1.0 to 1.2 times the volume of the mold and placed in the mold. In a typical foaming molding operation, the mold is maintained at about 150 to 200°C, the mold clamping pressure is 30 to 300 kgf / cm 2 , and the holding time is 3 to 50 minutes. In the mold, the cross-linking reaction proceeds while the blowing agent is decomposed. After the holding time, the mold is opened and the cross-linkable foaming composition is formed into a cross-linked foam. In the industrial production of the foam, an injection molding process in which the cross-linkable foaming composition is melt injected into a mold to cross-link and foam can be used.

[0089] The specific gravity (which can also be referred to as the density) of the cross-linked foam obtained from the cross-linkable foaming composition can be about 0.05 to 0.5 g / cm 3 , for example, 0.1 to 0.5 g / cm 3 , 0.1 to 0.45 g / cm m3, 0.1 to 0.4 g / cm 3 , 0.1 to 0.35 g / cm 3 , 0.1 to 0.3 g / cm 3 , or 0.1 to 0.25 g / cm 3 However, the present application is not limited thereto, and the specific gravity of the foamed body can be adjusted by changing the components of the cross-linkable foaming composition.

[0090] The hardness (Asker C) of the cross-linked foamed body obtained from the cross-linkable foaming composition can be about 20 to 80. In some embodiments, when the foamed body is formed from the cross-linkable foaming composition including the hydrogenated styrene diblock copolymer, the hardness (Asker C) of the foamed body can be about, for example, 30 to 75, 30 to 70, 30 to 65, 30 to 60, 35 to 60, 35 to 55, or 40 to 55. In some embodiments, when the foamed body is formed from the cross-linkable foaming composition including the hydrogenated styrene diblock copolymer and the ethylene copolymer, the hardness (Asker C) of the foamed body can be about, for example, 30 to 75, 30 to 70, 30 to 65, 30 to 60, 35 to 60, 35 to 55, or 40 to 55. However, the present application is not limited thereto, and the hardness (Asker C) of the foamed body can be adjusted by changing the components of the cross-linkable foaming composition.

[0091] The dry static coefficient of friction of the cross-linked foamed body obtained from the cross-linkable foaming composition is about 0.5 to 1.8, which can be determined according to ASTM D1894. In some embodiments, when the foamed body is formed from the cross-linkable foaming composition including the hydrogenated styrene diblock copolymer, the dry static coefficient of friction of the foamed body is about, for example, 0.6 to 1.8, 0.6 to 1.7, 0.6 to 1.6, 0.6 to 1.5, 0.6 to 1.4, 0.7 to 1.4, 0.7 to 1.3, 0.8 to 1.3, or 0.8 to 1.0. In some embodiments, when the foamed body is formed from the cross-linkable foaming composition including the hydrogenated styrene diblock copolymer and the ethylene copolymer, the dry static coefficient of friction of the foamed body is about, for example, 0.5 to 1.5, 0.5 to 1.4, 0.5 to 1.3, 0.5 to 1.2, 0.5 to 1.1, 0.5 to 1.0, or 0.5 to 0.9. However, the present application is not limited thereto, and the dry static coefficient of friction of the foamed body can be adjusted by changing the components of the cross-linkable foaming composition.

[0092] The crosslinked foamed body obtained from the crosslinkable foaming composition has a wet static coefficient of friction of about 0.5 to 1.5, which can be determined according to ASTM D1894. In some embodiments, when the foamed body is formed from the crosslinkable foaming composition including the hydrogenated styrene diblock copolymer, the foamed body has a wet static coefficient of friction of about, for example, 0.5 to 1.4, 0.5 to 1.3, 0.5 to 1.2, 0.6 to 1.2, 0.6 to 1.1, 0.7 to 1.1, 0.7 to 1.0, 0.8 to 1.0, or 0.8 to 0.9. In some embodiments, when the foamed body is formed from the crosslinkable foaming composition including the hydrogenated styrene diblock copolymer and the ethylene copolymer, the foamed body has a wet static coefficient of friction of about, for example, 0.5 to 1.4, 0.5 to 1.3, 0.5 to 1.2, 0.5 to 1.1, 0.5 to 1.0, 0.5 to 0.9, 0.5 to 0.8, or 0.5 to 0.7. However, the present application is not limited thereto, and the wet static coefficient of friction of the foamed body can be adjusted by changing the components of the crosslinkable foaming composition.

[0093] The foamed body obtained from the crosslinkable foaming composition of the present application has excellent balanced mechanical properties, at least in impact resilience, light weight, compression set, and tear properties. Thus, the foamed body obtained from the crosslinkable foaming composition of the present application can be used as a light weight and flexible material, and can be widely used in automobiles, construction, daily necessities, and sports goods.

[0094] In some embodiments, the crosslinked foamed body obtained from the crosslinkable foaming composition of the present application can be used as a shoe component, for example, an outsole.

[0095] In particular, when the foaming specific gravity is reduced, the mechanical properties tend to decrease; however, in the present application, it is possible to produce a light weight crosslinked foamed body having balanced mechanical properties, which can be particularly suitable for use in an outsole or a sports foaming pad.

[0096] Thus, in some embodiments, the foamed body obtained by crosslinking foaming the crosslinkable foaming composition of the present application can be used as a shoe component, for example, an outsole or a sports foaming pad, but the present application is not limited thereto.

[0097] Examples

[0098] The present application will be described in detail below with reference to examples. However, the present application is not limited to these examples. In the examples and comparative examples, the preparation and identification of the components used in the examples and comparative examples and the evaluation of the mechanical properties of the crosslinked foamed body can be performed by the following methods.

[0099] The polymer structure of the hydrogenated styrene diblock copolymer was identified as follows.

[0100] Molecular weight and molecular weight distribution

[0101] The weight average molecular weight (Mw) and number average molecular weight (Mn) are both tested and determined using a gel permeation chromatography (GPC) instrument. The molecular weight values of the peaks in the chromatogram are calculated by a calibration curve of commercially available standard polystyrene. The molecular weight distribution (Mw / Mn) is determined based on the weight average molecular weight (Mw) and the number average molecular weight (Mn). More detailed information about the test procedure and instrument information is described below. The instrument is a commercial GPC system provided by Waters Corporation, including PDI and refractive index detectors. Tetrahydrofuran (THF) is generally 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.

[0102] Styrene content and vinyl bond content

[0103] The measurement of the styrene content and the vinyl bond content of the hydrogenated styrene diblock copolymer before hydrogenation can use a1H-NMR spectrometer, VARIAN 400, provided by Agilent Technologies, Inc. Generally, deuterated chloroform is selected as the solvent.

[0104] Degree of hydrogenation

[0105] The degree of hydrogenation can be calculated from the reduction rate of the signal of the unsaturated bond in the1H-NMR spectrum, as follows.

[0106] Degree of hydrogenation (mol%) = B / (A+B) x 100%

[0107] A: the number of moles of unhydrogenated conjugated diene monomer units

[0108] B: the number of moles of hydrogenated conjugated diene monomer units

[0109] Melt flow index

[0110] The melt flow index (MFI) can be measured according to ASTM-D1238.

[0111] The novel state of the styrene diblock copolymer is evaluated as follows.

[0112] Compounding capability

[0113] The mixing ability of the styrene diblock and triblock samples of the examples and comparative examples was evaluated using an open roll mixer (HT-8807) supplied by Hoshizaki Engineering Co., Ltd. at a temperature of not more than 120°C. This was to simulate the shoe material mixing process, the steps of which include the addition of a free radical initiator and a chemical blowing agent, and then injection of the mixture into a press mold for foaming at a temperature that does not cause premature decomposition of the free radical initiator and the blowing agent. The temperature that does not cause decomposition of the free radical initiator and the blowing agent is 100 to 120°C.

[0114] The roll was heated to 120°C before the mixing process. Then, the sample was placed between the two rolls of the roll mixer. The material was ground into small pieces and gradually melted to form a band. After the material changed from a solid state to a molten state, the molten polymer formed a uniform band adhering to the rotating rolls. At this time, the degree of difficulty of mixing and the quality of the band could be observed and determined. If the sample did not melt well under the temperature conditions, the surface of the melt would be uneven. At the same time, small holes of irregular size could be observed. On the other hand, if the sample could melt well under the temperature conditions, the surface of the melt would be smooth and uniform.

[0115] The level of band formation on the roll surface was rated from 1 to 5, with a rating of 5 indicating the formation of a perfect melt film, and a rating of 1 indicating the formation of a poor film.

[0116] The mechanical properties of the crosslinked foam were evaluated in the following manner.

[0117] Specific gravity

[0118] The once-crosslinked foam was punched into a circle having a diameter of 2.54 cm and a thickness of 1 cm, and the specific gravity was measured by an electronic specific gravity meter (MS-204S, manufactured by Mettler Toledo Co., Ltd.).

[0119] Hardness

[0120] The hardness (Asker C) of the once-crosslinked foam was measured according to ASTM D2240 using an Asker hardness C durometer (Type C, manufactured by Polymer Co., Ltd.), and the value was read within 1 second. In addition, the average value (arithmetic mean) of 5 points was taken as the hardness.

[0121] Split tear strength

[0122] The split tear strength of the once-crosslinked foam was determined according to ASTM D3574 F.

[0123] Tensile strength

[0124] The tensile strength at break of the once-crosslinked foam was determined according to ASTM D412.

[0125] Elongation at break

[0126] Elongation at break of the once-crosslinked foams was determined according to ASTM D412.

[0127] Compression set

[0128] The once-crosslinked foams were punched into a circular shape with a diameter of 2.54 cm, used as test pieces, and compressed to a thickness of 50%. After being kept at 50°C for 6 hours, the pressure was released, and the thickness after 1 hour was measured. The size of the residual deformation was evaluated.

[0129] Impact resilience

[0130] The impact resilience of the crosslinked foams was determined in a vertical resiliometer according to ASTM-D2632. Impact resilience refers to the ratio of the rebound height of a metal plunger of specified mass and shape to the drop height, which falls on a foamed sample.

[0131] Static coefficient of friction

[0132] The static coefficient of friction of the once-crosslinked foams was determined according to ASTM D1894.

[0133] The resin compositions of the examples and comparative examples are described below.

[0134] Styrene block copolymer

[0135] SEP-1: hydrogenated styrene-isoprene diblock copolymer

[0136] SEP-1 is a hydrogenated styrene-isoprene diblock copolymer, the preparation and determination of which are described in detail below. First, 4800 g of cyclohexane, 7.06 mmol of n-butyllithium, and 2.66 mmol of tetrahydrofuran (THF) were added to a 10 liter-sized reactor equipped with a heater and a stirrer. Second, 534 g of isoprene was added to the reactor to initiate anionic polymerization at a temperature of about 45°C. Third, 313 g of styrene was added to the reactor, and the reaction mixture was further polymerized to produce a styrene-isoprene diblock copolymer. The content of 3,4-vinyl bond in the isoprene block was about 9.1 mol%.

[0137] The styrene-isoprene diblock copolymer obtained in the above step is then hydrogenated in a pressure vessel using a nickel 2-ethylhexanoate / TEAL catalyst and hydrogen gas. The temperature of the hydrogenation process is controlled at about 40°C to 100°C. After about 80 mol% of the isoprene block is hydrogenated, the hydrogenation reaction is terminated. The obtained sample is then washed with hot acidic water to remove the residual catalyst. Finally, the block copolymer is isolated by coagulation in hot water and then dried. The yield of the hydrogenated styrene diblock copolymer is about 80%.

[0138] After analysis, the obtained hydrogenated styrene-isoprene diblock copolymer has a styrene content of 37 wt%, a hydrogenation degree of 80 mol%, a weight average molecular weight of about 121,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and a MFI of 4 measured at 230°C / 5 kgf.

[0139] SEP-2: hydrogenated styrene-isoprene diblock copolymer

[0140] SEP-2 is prepared in the same manner as SEP-1, which is a fully hydrogenated styrene-isoprene diblock copolymer having a styrene content of 37 wt%, a content of 3,4-vinyl bonds in the isoprene block before hydrogenation of about 9 mol%, and a hydrogenation degree of the isoprene block of 99 mol%. The diblock copolymer has a weight average molecular weight of about 121,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and a MFI of 1.5 measured at 230°C / 5 kgf.

[0141] SEP-3: hydrogenated styrene-isoprene diblock copolymer

[0142] SEP-3 is prepared in the same manner as SEP-1, which is a hydrogenated styrene-isoprene diblock copolymer having a styrene content of 25 wt%, a content of 3,4-vinyl bonds in the isoprene block before hydrogenation of about 9 mol%, and a hydrogenation degree of the isoprene block of 84 mol%. The diblock copolymer has a weight average molecular weight of about 118,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and a MFI of 2.2 measured at 230°C / 5 kgf.

[0143] SEP-4: hydrogenated styrene-isoprene diblock copolymer

[0144] SEP-4, which is a fully hydrogenated styrene-isoprene diblock copolymer, was prepared in the same manner as SEP-1, having a styrene content of 25 wt%, a 3,4-vinyl bond content of about 9 mol% in the isoprene block before hydrogenation, and a hydrogenation degree of 98 mol% in the isoprene block. The diblock copolymer had a weight average molecular weight of about 119,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and an MFI of 0.7 measured at 230°C / 5 kgf.

[0145] SEPS-1: hydrogenated styrene-isoprene-styrene triblock copolymer

[0146] SEPS-1 is a hydrogenated styrene-isoprene-styrene triblock copolymer, which was prepared as follows.

[0147] First, 4800 g of cyclohexane, 10.2 mmol of n-butyllithium, and 2.66 mmol of tetrahydrofuran (THF) were added to a 10 liter-sized reactor equipped with a heater and a stirrer. Second, 120 g of styrene was added to the solvent, and anionic polymerization was performed at a temperature of about 45°C. Third, 560 g of isoprene was added to the reactor until the isoprene reaction was completed. Fourth, 120 g of styrene was added to the reactor, and after the styrene polymerization was completed, methanol was added to terminate the polymerization, forming a styrene-isoprene-styrene triblock copolymer structure. The 3,4-vinyl bond content of the isoprene block of the styrene-isoprene-styrene triblock copolymer was about 10 mol%.

[0148] Hydrogenation was performed in the same manner as in the preparation of SEP-1. According to the analysis results, the hydrogenated styrene-isoprene-styrene triblock copolymer obtained had a hydrogenation degree of 78.8 mol%, a styrene content of 28.8 wt%, a weight average molecular weight of about 95,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and an MFI of 0.23 measured at 230°C / 5 kgf.

[0149] SEPS-2: hydrogenated styrene-isoprene-styrene triblock copolymer

[0150] SEPS-2, which is a fully hydrogenated styrene-isoprene-styrene triblock copolymer, was prepared in the same manner as SEPS-1, having a styrene content of 28.4 wt%, a 3,4-vinyl bond content of about 10 mol% in the isoprene block, and a hydrogenation degree of 98.2 mol%. The triblock copolymer had a weight average molecular weight of about 95,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.03, and an MFI of 0.04 measured at 230°C / 5 kgf.

[0151] EEPS-1: hydrogenated (butadiene / isoprene)-styrene diblock copolymer

[0152] EPS-1 is a hydrogenated (butadiene / isoprene)-styrene diblock copolymer, the preparation and measurement of which are described in detail below. First, 4800 g of cyclohexane, 7.89 mmol of n-butyllithium, and 2.66 mmol of tetrahydrofuran (THF) were added to a 10 liter-sized reactor equipped with a heater and a stirrer. Second, 295 g of isoprene and 197 g of butadiene were simultaneously added to the reactor (I / B molar ratio controlled at 1.25), and anionic polymerization was initiated at a temperature of about 50°C until the isoprene and butadiene reactions were completed. Third, 289 g of styrene was added to the reactor, and after the styrene polymerization was completed, methanol was added to terminate the polymerization, forming a (isoprene / butadiene)-styrene diblock copolymer. The content of 3,4-vinyl bonds in the isoprene block was about 13 mol%, and the content of 1,2-vinyl bonds in the butadiene block was about 16 mol%.

[0153] Then, the (butadiene / isoprene)-styrene diblock copolymer obtained by the above steps was hydrogenated in a pressure vessel using a nickel 2-ethylhexanoate / TEAL catalyst and hydrogen gas. The temperature of the hydrogenation process was controlled at about 50°C to 90°C. Once the cumulative amount of hydrogen gas absorbed reached an amount corresponding to the target hydrogenation degree, the hydrogenation reaction was terminated. Then, the obtained sample was washed with hot acidic water to remove the residual catalyst. Finally, the block copolymer was separated by coagulation in hot water and then dried. The hydrogenated styrene diblock copolymer had a hydrogenation degree of 78.1 mol%, a styrene content of 37.1 wt%, a weight average molecular weight of about 128,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.06, and an MFI of 0.63 measured at 230°C / 5 kgf.

[0154] EEPS-2: hydrogenated (butadiene / isoprene)-styrene diblock copolymer

[0155] EEPS-2 was prepared and identified in the same manner as EEPS-1, which is a fully hydrogenated (butadiene / isoprene)-styrene diblock copolymer, having a styrene content of 37.1 wt%, a hydrogenation degree of 99.1 mol%, a weight average molecular weight of about 128,000, a molecular weight distribution (weight average molecular weight / number average molecular weight) of 1.06, and an MFI of less than 0.1 measured at 230°C / 5 kgf.

[0156] Ethylene copolymer

[0157] EVA-1: ethylene-vinyl acetate copolymer

[0158] EVA-1 is an ethylene-vinyl acetate copolymer having a vinyl acetate content of 25 wt%, a MFI of 3 g / 10 min measured at 190°C / 2.16 kgf, which is manufactured by USI Corporation under the trade name "UE659".

[0159] Organic Peroxide

[0160] Bis(1-(tert-butylperoxy)-1-methyl ethyl)-benzene (BIPB) manufactured by Arkema Group was used.

[0161] Chemical Foaming Agent

[0162] Azodicarbonamide (AC) manufactured by Kumyang Corporation was used.

[0163] Other Additives

[0164] Calcium carbonate (manufactured by Yuncheng Chemical Industry Co., Ltd.), ZnO (zinc oxide, manufactured by Diamonchem International Co., Ltd.), and stearic acid (manufactured by Vulchem Inc.) were used.

[0165] Results

[0166] Table 1 below lists the polymer structure information, melt flow index, and mixing ability grade of diblock SEP-1, diblock EEPS-1, and triblock SEPS-1, and the measurement of the mixing ability grade is described above in the Mixing Ability section.

[0167] Table 1

[0168]

[0169]

[0170] As shown in the results of Table 1, in the mixing ability evaluation in the roll mill, it can be clearly seen that both diblock samples (SEP-1 and EEPS-1) are well mixed and form a smooth transparent band on the rotating roller. Both SEP-1 and EEPS-1, which have a high molecular weight and a high melt viscosity as shown in the MFI values measured at 230°C / 5 kg, can be well mixed, which is a very unexpected result. For example, the diblock SEP-1 has a Mw of 121,000. In contrast, the triblock SEPS-1 having a weight average molecular weight Mw of 95,000 is difficult to mix in the roll mill and forms an opaque band on the rotating roller.

[0171] In the following examples (abbreviated as Ex) and comparative examples (abbreviated as Comp Ex), a styrene block copolymer was mixed with an organic peroxide and a foaming agent to prepare a crosslinked foam.

[0172] In Example 1, a foaming composition including 100 parts by weight of SEP-1 (partially hydrogenated styrene-isoprene diblock copolymer), 0.4 parts by weight of bis(1-(tert-butylperoxy)-1-methylethyl)-benzene (BIPB) based on the total weight of the resin component (here, SEP-1), 3.0 parts by weight of azodicarbonamide (AC) based on the total weight of the resin component, 1 part by weight of zinc oxide based on the total weight of the resin component, 1 part by weight of stearic acid based on the total weight of the resin component, and 10 parts by weight of calcium carbonate based on the total weight of the resin component, was mixed and kneaded in a roll mill with the roll surface temperature set to 120°C for 10 minutes. Although the weight average molecular weight of SEP-1 was about 121,000, it was mixed well with the other ingredients of the foaming formulation.

[0173] Next, the mixed composition was pressurized and heated in a press mold at 175°C and a pressure of 100 kgf / cm 2 for 10 minutes to obtain a crosslinked foam. Subsequently, the properties of the foam were measured according to the above-described method. The results are shown in Table 2 below.

[0174] Examples 2 to 6 were prepared and tested according to the same method as Example 1, except that different polymer components and different peroxide contents were used as listed in Table 2. Examples 4 to 6 were mixtures of EVA and different styrene-isoprene diblock copolymer resins.

[0175] In Comparative Example 1, an EVA foam was prepared and tested according to the same method as Example 1.

[0176] Comparative Examples 2 to 5 were prepared according to the same method as Example 1, except that different polymer components and different peroxide contents were used as listed in Table 3 below. Comparative Examples 2 and 3 were mixtures of EVA-1 with partially hydrogenated SEPS-1 triblock and fully hydrogenated SEPS-2 triblock, respectively. Comparative Examples 4 and 5 were mixtures of EVA-1 with partially hydrogenated EEPS-1 diblock and fully hydrogenated EEPS-2 diblock, respectively.

[0177] The results of Examples 1 to 6 and Comparative Example 1 are shown in Table 2, and the results of Comparative Examples 2 to 5 are shown in Table 3.

[0178] Table 2

[0179]

[0180] Table 3

[0181]

[0182]

[0183] Comparative Example 1 was compared to Examples 1-6, which included styrene-isoprene diblock copolymers, for slip resistance properties. As shown in Table 2, all of the foams of Examples 1-6 showed superior slip resistance properties to the EVA-1 foams of Comparative Example 1. In addition, all of the foams of Comparative Examples 2-5 showed inferior slip resistance properties to the foams of Examples 3-6. These results show that foams prepared from compositions including styrene-isoprene diblock copolymers have improved slip resistance properties.

[0184] In summary, the present application provides a crosslinked foamed composition including the hydrogenated styrene-isoprene diblock copolymer of the present application, or a blend of the hydrogenated styrene-isoprene diblock copolymer of the present application and an ethylene copolymer. The crosslinked foams of the present application have superior slip resistance properties and excellent balanced mechanical properties (at least in impact resilience, light weight, compression set, and delamination tear strength). In addition, the crosslinked foams can be suitable for use in a variety of molded articles, such as shoe midsoles and outsoles, automotive parts, civil engineering and construction applications, home appliance parts, sports goods, and a wide range of other fields. In particular, the crosslinked foams have superior slip resistance properties, which is an important feature for shoe outsole applications.

[0185] While the application has been provided with respect to particular embodiments, it will be understood that numerous other modifications and changes can be made without departing from the spirit and scope of the disclosure claimed below.

Claims

1. A crosslinkable foaming composition comprising a hydrogenated styrene diblock copolymer, a free radical initiator, and a blowing agent, characterized in that, The hydrogenated styrene diblock copolymer comprises: a first block being a polymer block of isoprene units; and a second block being a polymer block of styrene units; wherein the hydrogenated styrene diblock copolymer comprises 10 to 60 wt% of the styrene units, 50 mol% or more of the isoprene units are hydrogenated, and the weight average molecular weight of the hydrogenated styrene diblock copolymer is between 30,000 to 200,000. Before hydrogenation, the content of 3,4-vinyl bond in the isoprene units is between 5 to 15 mol%.

2. A crosslinkable foamable composition comprising a hydrogenated styrene di-block copolymer, a free radical initiator, and a blowing agent, characterized in that, The hydrogenated styrene diblock copolymer comprises: a first block being a polymer block of isoprene units and butadiene units, wherein the content of the butadiene units is less than or equal to 15 mol% of the total weight of the first block, and a second block being a polymer block of styrene units; wherein the hydrogenated styrene diblock copolymer comprises 10 to 60 wt% of the styrene units, 50 mol% or more of the isoprene units are hydrogenated, and the weight average molecular weight of the hydrogenated styrene diblock copolymer is between 30,000 to 200,000.

3. A crosslinkable foamable composition comprising a hydrogenated styrene diblock copolymer, a free radical initiator, and a blowing agent, characterized in that, The hydrogenated styrene diblock copolymer comprises: a first block being a polymer block of isoprene units; and a second block being a polymer block of styrene units and conjugated diene monomer units, wherein the conjugated diene monomer units are butadiene units, isoprene units, or a mixture thereof, and the content of the conjugated diene monomer units is less than or equal to 15 wt% of the total weight of the second block; wherein the hydrogenated styrene diblock copolymer comprises 10 to 60 wt% of the styrene units, 50 mol% or more of the isoprene units are hydrogenated, and the weight average molecular weight of the hydrogenated styrene diblock copolymer is between 30,000 to 200,000. Before hydrogenation, the content of 3,4-vinyl bond in the isoprene units is between 5 to 15 mol%.

4. A crosslinkable foamable composition comprising a hydrogenated styrene diblock copolymer, a free radical initiator, and a blowing agent, characterized in that, The hydrogenated styrene diblock copolymer comprises: a first block being a polymer block of isoprene units and butadiene units, wherein the content of the butadiene units is less than or equal to 15 mol% of the total weight of the first block; and a second block being a polymer block of styrene units and conjugated diene monomer units, wherein the conjugated diene monomer units are butadiene units, isoprene units, or a mixture thereof, and the content of the conjugated diene monomer units is less than or equal to 15 wt% of the total weight of the second block; wherein the hydrogenated styrene diblock copolymer comprises 10 to 60 wt% of the styrene units, 50 mol% or more of the isoprene units are hydrogenated, and the weight average molecular weight of the hydrogenated styrene diblock copolymer is between 30,000 to 200,000.

5. The cross-linkable foamable composition of claim 2 or 4, wherein Before hydrogenation, the content of 3,4-vinyl bond in the isoprene units is between 5 to 40 mol%.

6. The cross-linkable foaming composition of any one of claims 1-4, wherein, After hydrogenation, 60 to 100 mol% of the isoprene units are hydrogenated.

7. The cross-linkable foaming composition of any one of claims 1-4, wherein the cross-linkable foaming composition is a polyurethane foam composition. The free radical initiator is an organic peroxide selected from the group consisting of dicumyl peroxide, bis(1-(tert-butylperoxy)-1-methylethyl)-benzene, and mixtures thereof.

8. The cross-linkable foaming composition of any one of claims 1-4, wherein, The blowing agent is a chemical blowing agent, which is azodicarbonamide.

9. The cross-linkable foamable composition of any one of claims 1-4, further comprising a cross-linking co-agent.

10. The cross-linkable foaming composition of any one of claims 1-4, wherein, further comprising an ethylene copolymer, wherein a weight ratio of the ethylene copolymer to the hydrogenated styrene diblock copolymer is between 50 / 50 and 95 / 5.

11. The cross-linkable foaming composition of claim 10, wherein The ethylene copolymer comprises an ethylene-vinyl acetate copolymer, an ethylene-a-olefin copolymer, or a combination thereof.

12. The cross-linkable foaming composition of claim 10, wherein The ethylene copolymer is an ethylene-vinyl acetate copolymer, and a content of the vinyl acetate is 15 to 40 wt% of a total weight of the ethylene copolymer.

13. The cross-linkable foaming composition of claim 10, wherein characterized in that, further comprising a cross-linking co-agent.

14. A foam characterized by, obtained by cross-linking foaming the cross-linkable foamable composition according to any one of claims 1-4.

15. The foam of claim 14, wherein, The specific gravity of the foam is 0.1 to 0.5 g / cm 3 a dry static coefficient of friction of 0.6 to 1.8, a wet static coefficient of friction of 0.5 to 1.5, and a hardness of 30 to 80, wherein the dry static coefficient of friction and the wet static coefficient of friction are determined in accordance with ASTM D1894, and the hardness is measured in accordance with ASTM D2240.

16. The foam of claim 14, wherein It is a footwear component.

17. The foam of claim 16, wherein, It is an outsole.

18. A foam, characterized by, obtained by cross-linking foaming the cross-linkable foamable composition according to claim 10.

19. The foam of claim 18, wherein, The specific gravity of the foam is 0.1 to 0.5 g / cm 3 a dry static coefficient of friction of 0.6 to 1.5, a wet static coefficient of friction of 0.5 to 1.2, and a hardness of 30 to 80, wherein the dry static coefficient of friction and the wet static coefficient of friction are determined in accordance with ASTM D1894, and the hardness is measured in accordance with ASTM D2240.

20. The foam of claim 18, wherein It is a footwear component.

21. The foam of claim 20, wherein, It is an outsole.

22. A foaming composition comprising a hydrogenated styrene diblock copolymer, characterized in that, The hydrogenated styrene diblock copolymer comprises: a first block, which is a polymer block of isoprene units; and a second block, which is a polymer block of styrene units; wherein the hydrogenated styrene diblock copolymer comprises 10 to 60 wt% of the styrene units, 50 mol% or more of the isoprene units are hydrogenated, and a weight average molecular weight of the hydrogenated styrene diblock copolymer is between 30,000 and 200,000; wherein, before hydrogenation, a content of 3,4-vinyl bonds in the isoprene units is between 5 and 15 mol%.

23. A foaming composition comprising a hydrogenated styrene diblock copolymer, characterized in that, The hydrogenated styrene diblock copolymer comprises: a first block, which is a polymer block of isoprene units and a polymer block of butadiene units, wherein a content of the butadiene units is less than or equal to 15 mol% of a total weight of the first block; and a second block, which is a polymer block of styrene units; wherein the hydrogenated styrene diblock copolymer comprises 10 to 60 wt% of the styrene units, 50 mol% or more of the isoprene units are hydrogenated, and a weight average molecular weight of the hydrogenated styrene diblock copolymer is between 30,000 and 200,000.

24. A foaming composition comprising a hydrogenated styrene diblock copolymer, characterized in that, The hydrogenated styrene diblock copolymer comprises: a first block, which is a polymer block of isoprene units; and a second block, which is a polymer block of styrene units and a polymer block of conjugated diene monomer units, wherein the conjugated diene monomer units are butadiene units, isoprene units, or a mixture thereof, and a content of the conjugated diene monomer units is less than or equal to 15 wt% of a total weight of the second block; wherein the hydrogenated styrene diblock copolymer comprises 10 to 60 wt% of the styrene units, 50 mol% or more of the isoprene units are hydrogenated, and a weight average molecular weight of the hydrogenated styrene diblock copolymer is between 30,000 and 200,000. wherein the content of 3,4-vinyl bonds in the isoprene units is between 5 and 15 mol% prior to hydrogenation.

25. A foaming composition comprising a hydrogenated styrene diblock copolymer, characterized in that, The hydrogenated styrene diblock copolymer comprises: a first block being a polymer block of isoprene units and butadiene units, wherein the content of butadiene units is less than or equal to 15 mol% of the total weight of the first block; and a second block being a polymer block of styrene units and conjugated diene monomer units, wherein the conjugated diene monomer units are butadiene units, isoprene units, or a mixture thereof, and the content of conjugated diene monomer units is less than or equal to 15 wt% of the total weight of the second block; wherein the hydrogenated styrene diblock copolymer comprises 10 to 60 wt% of the styrene units, 50 mol% or more of the isoprene units are hydrogenated, and the weight average molecular weight of the hydrogenated styrene diblock copolymer is between 30,000 and 200,000.

26. The composition of any one of claims 22-25, wherein, an ethylene copolymer is also included.

27. Use of the composition of any one of claims 22-25, wherein for making a foam. for making a foam.

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