Crosslinked thermoplastic elastomers

Abstract

A cross-linkable thermoplastic polymer blend includes a polymer pellet and a crosslinking composition. The polymer pellet includes a thermoplastic elastomer derived at least in part from conjugated diene monomers and / or a thermoplastic elastomer comprising at least one cross-linkable functional group reactive to silane in the presence of peroxide. The crosslinking composition includes a silane crosslinker and an organic peroxide. The cross-linkable thermoplastic polymer blend may further include a moisture cure catalyst. The cross-linkable thermoplastic polymer blend forms a crosslinked thermoplastic elastomer, when extruded or injection molded and optionally moisture cured.

Description

CROSSLINKED THERMOPLASTIC ELASTOMERSCLAIM OF PRIORITY

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 578,546 bearing Attorney Docket Number 1202317 and filed on August 24, 2023, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure generally relates to cross-linkable thermoplastic polymer blends and crosslinked thermoplastic elastomer formed therefrom. More particularly, the present disclosure relates to cross-linkable thermoplastic elastomers manufactured in a one-step process, eliminating the need for a separate silane grafting step.BACKGROUND

[0003] Crosslinked thermoplastic articles may have desirable properties, such as chemical and heat resistance. Conventional processes, such as reaction extrusion, are known for forming crosslinked thermoplastic articles. In reaction extrusion, a thermoplastic polymer is crosslinked by silane grafting in an extruder, and the crosslinked thermoplastic polymer is further formed into articles by conversion processes such as extrusion and / or injection molding. Additional steps, time, and materials may be required to achieve the desirable crosslink density and heat resistance for certain applications in the healthcare, automotive, and electronic fields.SUMMARY

[0004] In light of the disclosure herein, and without limiting the scope of the invention in any way, in a first aspect of the present disclosure, which may be combined with any other aspect listed herein unless specified otherwise, a cross-linkable thermoplastic polymer blend comprises a polymer pellet and a crosslinking composition. The polymer pellet comprises a thermoplasticelastomer derived at least in part from conjugated diene monomers. The crosslinking composition comprises a silane crosslinker and an organic peroxide. The cross-linkable thermoplastic polymer blend forms a crosslinked thermoplastic elastomer, when extruded or injection molded.

[0005] In light of the disclosure herein, and without limiting the scope of the invention in any way, in a second aspect of the present disclosure, which may be combined with any other aspect listed herein unless specified otherwise, a cross-linkable thermoplastic polymer blend comprises a polymer pellet, a crosslinking composition, and a moisture cure catalyst. The polymer pellet comprises a thermoplastic elastomer comprising at least one cross-linkable functional group reactive to silane in the presence of peroxide. The crosslinking composition comprises a silane crosslinker and an organic peroxide. The cross-linkable thermoplastic polymer blend forms a crosslinked thermoplastic elastomer, when extruded or injection molded and moisture cured.

[0006] In any of the aspects of the present disclosure, the crosslinking composition may be present in a dry silane masterbatch comprising a carrier material loaded with the silane crosslinker and the organic peroxide. Alternatively, or in addition to the dry silane masterbatch, the crosslinking composition may be present in a solution, dispersion, or emulsion comprising the silane crosslinker and the organic peroxide.

[0007] In light of the disclosure herein, and without limiting the scope of the invention in any way, in a third aspect of the present disclosure, which may be combined with any other aspect listed herein unless specified otherwise, a process for forming a crosslinked thermoplastic elastomer comprises dry blending one or more polymer pellets and a dry silane masterbatch to form a thermoplastic polymer blend, melting the thermoplastic polymer blend to form a cross-linkable thermoplastic polymer melt, and extruding or injection molding the cross-linkable thermoplastic polymer melt. The polymer pellets comprise a thermoplastic elastomer. The dry silane masterbatch comprises a carrier material loaded with a crosslinking composition comprising a silane crosslinker and an organic peroxide. In accordance with the present disclosure, the dry silane masterbatch may optionally comprise a moisture cure catalyst.

[0008] In light of the disclosure herein, and without limiting the scope of the invention in any way, in a fourth aspect of the present disclosure, which may be combined with any other aspect listedherein unless specified otherwise, a process for forming a crosslinked thermoplastic elastomer comprises melting one or more polymer pellets to form a thermoplastic polymer melt, injecting a solution of a crosslinking composition into the thermoplastic polymer melt to form a cross-linkable thermoplastic polymer melt, and extruding or injection molding the cross-linkable thermoplastic polymer melt. The polymer pellets comprise a thermoplastic elastomer. The crosslinking composition comprises a silane crosslinker and an organic peroxide. In accordance with the present disclosure, the solution of the crosslinking composition may optionally comprise a moisture cure catalyst.

[0009] In accordance with the present disclosure, the process for forming a crosslinked thermoplastic elastomer may further comprise exposing the extruded or injection molded crosslinkable thermoplastic polymer melt to moisture.DETAILED DESCRIPTION

[0010] Disclosed herein are cross-linkable thermoplastic polymer blends. While the present disclosure describes certain embodiments of the cross-linkable thermoplastic blends in detail, the present disclosure is to be considered exemplary and is not intended to be limited to the disclosed embodiments.

[0011] The terminology as set forth herein is for description of the embodiments only and should not be construed as limiting the disclosure as a whole. All references to singular characteristics or limitations of the present disclosure shall include the corresponding plural characteristic or limitation, and vice versa, unless otherwise specified or clearly implied to the contrary by the context in which the reference is made. Unless otherwise specified, “a,” “an,” “the,” and “at least one” are used interchangeably. Furthermore, as used in the description and the appended claims, the singular forms “a,” “an,” and “the” are inclusive of their plural forms, unless the context clearly indicates otherwise.

[0012] To the extent that the term “includes” or “including” is used in the description or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” isemployed (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but not both” will be employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use.

[0013] The cross-linkable thermoplastic polymer blends of the present disclosure can comprise, consist of, or consist essentially of the essential elements of the disclosure as described herein, as well as any additional or optional element described herein, or which is otherwise useful in crosslinked thermoplastic elastomer applications.

[0014] All percentages, parts, and ratios as used herein are by weight of the total blend on an “dry” basis, i.e., without solvents, unless otherwise specified.

[0015] All ranges and parameters, including but not limited to percentages, parts, and ratios, disclosed herein are understood to encompass any and all sub-ranges assumed and subsumed therein, and every number between the endpoints. For example, a stated range of “1 to 10” should be considered to include any and all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less (e.g., 1 to 6.1, or 2.3 to 9.4), and to each integer (1, 2, 3, 4, 5, 6, 7, 8, 9, and 10) contained within the range.

[0016] The present inventive concepts are directed to cross-linkable thermoplastic polymer blends comprising a polymer pellet and a crosslinking composition. The polymer pellet comprises a thermoplastic elastomer derived at least in part from conjugated diene monomers and / or a thermoplastic elastomer comprising at least one cross-linkable functional group reactive to silane in the presence of peroxide. The crosslinking composition comprises a silane crosslinker and an organic peroxide. The cross-linkable thermoplastic polymer blends can be extruded or injection molded, and optionally can further be moisture cured, to form a crosslinked thermoplastic elastomer.

[0017] Conventional processes for forming crosslinked thermoplastic articles include a silane grafting step in which a thermoplastic polymer is crosslinked by a silane crosslinker via reaction extrusion, followed by a conversion step in which the crosslinked thermoplastic polymer is formed into articles by extrusion or injection molding. The silane grafting step adds costs in terms ofspecial equipment and operation for reaction extrusion, different reaction extrusion setups required for thermoplastic polymers having different properties, and the packaging and storage of the crosslinked thermoplastic polymer, which has a certain shelf life until it becomes unsuitable for further extrusion or injection molding. The cross-linkable thermoplastic polymer blends of the present disclosure address these issues in the conventional processes by eliminating the need for a separate silane grafting step. The thermoplastic elastomer of the present disclosure can be blended with a silane crosslinking composition directly in the conventional conversion process, thus eliminating the initial silane grafting step. The crosslinking of the thermoplastic elastomer is performed in a one-step process where a thermoplastic crosslinked article is formed by extrusion or injection molding. As such, the costs and process concerns related to the silane grafting step can be eliminated. In addition, different types of rubbers and polymers can be flexibly included in the cross-linkable thermoplastic polymer blend without restriction from the reaction extrusion process. As result, the cross-linkable thermoplastic polymer blends of the present disclosure significantly reduce manufacturing cost and improves formulation flexibility of crosslinked thermoplastic polymers.Polymer Pellet

[0018] The polymer pellet of the cross-linkable thermoplastic polymer blends comprises a thermoplastic elastomer. In any of the exemplary embodiments, the thermoplastic elastomer may fall within at least one of the following groups: Group A polymers, comprising highly reactive thermoplastic elastomers derived at least in part from conjugated diene monomers; and Group B polymers, comprising at least one cross-linkable functional group reactive to silane in the presence of peroxide.

[0019] Group A polymers may comprise any thermoplastic elastomer derived at least in part from conjugated diene monomers. Particularly, the Group A polymers include elastomers having an unsaturated mer unit derived from the polymerization of a conjugated diene. The Group A polymer may be non-hydrogenated or partially hydrogenated. Examples of suitable conjugated diene monomers include 1,3 -butadiene, 2,3-dimethyl-l,3-butadiene, piperylene, isoprene, and combinations thereof. The thermoplastic elastomer may be derived from conjugated diene monomers in combination with other monomers, such as vinyl aromatic monomers. Examples ofsuitable vinyl aromatic monomers include styrene, a-methyl styrene, p-methylstyrene, o- m ethyl styrene, p-butyl styrene, p-tertbutylstyrene, and combinations thereof.

[0020] In accordance with the present disclosure, the Group A polymer may be selected from the group consisting of styrene-butadiene rubber, styrene-butadiene block copolymers, styrene-isoprene block copolymers (SIS), styrene-butadiene-isoprene rubber, styrene- butadiene / isoprene block copolymers, styrene-butadiene-isoprene block copolymers, nitrilebutadiene rubber, and combinations thereof, which may be non-hydrogenated or partially hydrogenated.

[0021] In accordance with the present disclosure, the Group A polymer may be a block copolymer that includes a block defined by formula (I):wherein the w, x, y, and z units are randomly distributed in block, each Ri is independently a hydrogen atom or a methyl group, and each R2 is independently a hydrogen atom or a methyl group with the proviso that at least one R2 per unit is a hydrogen atom.

[0022] In a polymer block defined by formula (I), the molar percent of the sum of the y and z units out of the total sum of the w, x, y, and z units in the block may be from about 30% to about 90%. The molar percent of the sum of the y and z units out of the total sum of the w, x, y, and z units in the block may be from about 50% to about 70%. The molar percent of the sum of the y and z units out of the total sum of the w, x, y, and z units in the block may be greater than or equal to about 30%, greater than or equal to about 35%, greater than or equal to about 40%, greater than or equal to about 45%, or even greater than or equal to about 50%. The molar percent of the sum of the y and z units out of the total sum of the w, x, y, and z units in the block may be less than or equal to about 90%, less than or equal to about 85%, less than or equal to about 80%, less than orequal to about 75%, or even less than or equal to about 70%. The molar percent of the sum of the y and z units out of the total sum of the w, x, y, and z units in the block may be from about 30% to about 90%, from about 30% to about 85%, from about 30% to about 80%, from about 30% to about 75%, from about 30% to about 70%, from about 35% to about 90%, from about 35% to about 85%, from about 35% to about 80%, from about 35% to about 75%, from about 35% to about 70%, from about 40% to about 90%, from about 40% to about 85%, from about 40% to about 80%, from about 40% to about 75%, from about 40% to about 70%, from about 45% to about 90%, from about 45% to about 85%, from about 45% to about 80%, from about 45% to about 75%, from about 45% to about 70%, from about 50% to about 90%, from about 50% to about 85%, from about 50% to about 80%, from about 50% to about 75%, or from about 50% to about 70%, or any and all subranges formed from any of these endpoints. The molar percent of the sum of the y and z units out of the total sum of the w, x, y, and z units in the block may be less than or equal to about 5%, less than or equal to about 3%, less than or equal to about 2%, less than or equal to about 1%, or even 0%.

[0023] In a polymer block defined by formula (I), the ratio of y units to w units may be greater than the ratio of x units to z units. The ratio of y units to w units may also be less than the ratio of x units to z units.

[0024] In accordance with the present disclosure, the Group A polymer may be a block copolymer that includes a block defined by formula (II):wherein the a, b, c, and d units are randomly distributed in the block.

[0025] In a polymer block defined by formula (II), the molar percent of the sum of the c units and d units out of the total sum of the a, b, c, and d units in the block may be from about 30%to about 90%. The molar percent of the sum of the c units and d units out of the total sum of the a, b, c, and d units in the block may be from about 50% to about 70%. The molar percent of the sum of the c units and d units out of the total sum of the a, b, c, and d units in the block may be greater than or equal to about 30%, greater than or equal to about 35%, greater than or equal to about 40%, greater than or equal to about 45%, or even greater than or equal to about 50%. The molar percent of the sum of the c units and d units out of the total sum of the a, b, c, and d units in the block may be less than or equal to about 90%, less than or equal to about 85%, less than or equal to about 80%, less than or equal to about 75%, or even less than or equal to about 70%. The molar percent of the sum of the c units and d units out of the total sum of the a, b, c, and d units in the block may be from about 30% to about 90%, from about 30% to about 85%, from about 30% to about 80%, from about 30% to about 75%, from about 30% to about 70%, from about 35% to about 90%, from about 35% to about 85%, from about 35% to about 80%, from about 35% to about 75%, from about 35% to about 70%, from about 40% to about 90%, from about 40% to about 85%, from about 40% to about 80%, from about 40% to about 75%, from about 40% to about 70%, from about 45% to about 90%, from about 45% to about 85%, from about 45% to about 80%, from about 45% to about 75%, from about 45% to about 70%, from about 50% to about 90%, from about 50% to about 85%, from about 50% to about 80%, from about 50% to about 75%, or from about 50% to about 70%, or any and all subranges formed from any of these endpoints. The molar percent of the sum of the c units and d units out of the total sum of the a, b, c, and d units in the block may be less than or equal to about 5%, less than or equal to about 3%, less than or equal to about 2%, less than or equal to about 1%, or even 0%.

[0026] In a polymer block defined by formula (II), the ratio of c units to a units may be greater than the ratio of d units to b units. The ratio of c units to a units may also be less than the ratio of d units to b units.

[0027] In accordance with the present disclosure, the thermoplastic elastomer may be a triblock copolymer that includes two polystyrene end blocks. The styrene content of the two polystyrene end blocks in the thermoplastic elastomer may be from about 10 wt.% to about 50 wt.%. The styrene content of the two polystyrene end blocks in the thermoplastic elastomer may be greater than or equal to about 10 wt.%, greater than or equal to about 15 wt.%, greater than orequal to about 20 wt.%, greater than or equal to about 25 wt.%, or even greater than or equal to about 27 wt.%. The styrene content of the two polystyrene end blocks in the thermoplastic elastomer may be less than or equal to about 50 wt.%, less than or equal to about 45 wt.%, less than or equal to about 40 wt.%, less than or equal to about 35 wt.%, or even less than or equal to about 33 wt.%. The styrene content of the two polystyrene end blocks in the thermoplastic elastomer may be from about 10 wt.% to about 50 wt.%, from about 10 wt.% to about 45 wt.%, from about 10 wt.% to about 40 wt.%, from about 10 wt.% to about 35 wt.%, from about 10 wt.% to about 33 wt.%, from about 15 wt.% to about 50 wt.%, from about 15 wt.% to about 45 wt.%, from about 15 wt.% to about 40 wt.%, from about 15 wt.% to about 35 wt.%, from about 15 wt.% to about 33 wt.%, from about 20 wt.% to about 50 wt.%, from about 20 wt.% to about 45 wt.%, from about 20 wt.% to about 40 wt.%, from about 20 wt.% to about 35 wt.%, from about 20 wt.% to about 33 wt.%, from about 25 wt.% to about 50 wt.%, from about 25 wt.% to about 45 wt.%, from about 25 wt.% to about 40 wt.%, from about 25 wt.% to about 35 wt.%, from about 25 wt.% to about 33 wt.%, from about 27 wt.% to about 50 wt.%, from about 27 wt.% to about 45 wt.%, from about 27 wt.% to about 40 wt.%, from about 27 wt.% to about 35 wt.%, or from about 27 wt.% to about 33 wt.%, or any and all subranges formed from any of these endpoints.

[0028] As mentioned above, the thermoplastic elastomer may comprise or consist of Group B polymers, which include polymers comprising at least one cross-linkable functional group reactive to silane in the presence of peroxide. Exemplary Group B polymers include ethylene- propylene-diene rubber (EPDM), pms-SEBS (styrene-ethylene-butylene-styrene), heat cured silicone rubber (HCR), ethylene-propylene rubber (EPR), butyl rubber, halobutyl rubber, halogenated rubbery copolymers of p-alkyl styrene and at least one isomonoolefin having 4 to 7 carbon atoms, nitrile rubber and its copolymers, styrene-acrylate-acrylonitrile rubber (Sunigum®), hydrogenated nitrile rubber, acrylate rubber and its copolymers, ethylene-acrylate-glycidyl methacrylate elastomer, polyamide elastomer, polyester elastomer, natural rubber, and a polyolefin copolymeric elastomer having at least two repeat units that are derived from the group consisting of ethylene, propylene, butene, hexene, and octene. For example, the thermoplastic elastomer can be an EPDM rubber with either norbornene, hexadiene or dicyclopentadiene monomer units.

[0029] In accordance with the present disclosure, the thermoplastic elastomer may have a number average molecular weight from about 30,000 g / mol to about 400,000 g / mol. The thermoplastic elastomer may have a number average molecular weight greater than or equal to 30,000 g / mol, greater than or equal to about 50,000 g / mol, greater than or equal to about 100,000 g / mol, or even greater than or equal to about 150,000 g / mol. The thermoplastic elastomer may have a number average molecular weight less than or equal to about 400,000 g / mol, less than or equal to about 350,000 g / mol, less than or equal to about 300,000 g / mol, or even less than or equal to about 250,000 g / mol. The thermoplastic elastomer may have a number average molecular weight from about 30,000 g / mol to about 400,000 g / mol, from about 30,000 g / mol to about 350,000 g / mol, from about 30,000 g / mol to about 300,000 g / mol, from about 30,000 g / mol to about 250,000 g / mol, from about 50,000 g / mol to about 400,000 g / mol, from about 50,000 g / mol to about 350,000 g / mol, from about 50,000 g / mol to about 300,000 g / mol, from about 50,000 g / mol to about 250,000 g / mol, from about 100,000 g / mol to about 400,000 g / mol, from about 100,000 g / mol to about 350,000 g / mol, from about 100,000 g / mol to about 300,000 g / mol, from about 100,000 g / mol to about 250,000 g / mol, from about 150,000 g / mol to about 400,000 g / mol, from about 150,000 g / mol to about 350,000 g / mol, from about 150,000 g / mol to about 300,000 g / mol, or from about 150,000 g / mol to about 250,000 g / mol, or any and all subranges formed from any of these endpoints.

[0030] In accordance with the present disclosure, when the thermoplastic elastomer has carbon-carbon double bond sites, the carbon-carbon double bond may be partially hydrogenated. Without being bound by theory, it is believed that crosslinking of partially hydrogenated thermoplastic elastomers occurs at least in part at the nonhydrogenated sites (i.e., carbon-carbon double bonds such as those located on the conjugated diene residues) and the amount of reactive sites may be set by tailoring the hydrogenation of the thermoplastic elastomer. By controlling the level of hydrogenation, the amount of crosslinking may also be controlled. Reducing the degree of hydrogenation of the thermoplastic elastomer may improve the crosslink density and heat resistance of the resulting partially crosslinked polymer system. In accordance with the present disclosure, the thermoplastic elastomer may have a degree of hydrogenation greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 85%, greater than or equal to about 90%, oreven greater than or equal to about 95%, based on the molar ratio of the hydrogenated carboncarbon double bonds to the total carbon-carbon double bonds in the pre-partially hydrogenated thermoplastic elastomer. In accordance with the present disclosure, the thermoplastic elastomer may have a degree of hydrogenation in the range of about 30% to about 99%, or about 35% to about 95%, or about 40% to about 90%, or about 45% to about 85%, or about 50% to about 80%, or about 55% to about 75%, based on the unsaturated groups of the conjugated diene monomeric units in the pre-partially hydrogenated thermoplastic elastomer.

[0031] In accordance with the present disclosure, the thermoplastic elastomer may be a block copolymer or a partially hydrogenated block copolymer having a hard phase and a soft phase, the general configuration being:A— B,A — B — A, orA— B— A', where each A and A' blocks is a hard phase comprised of vinyl aromatic monomeric units and each B block is a soft phase comprised of conjugated diene monomeric units. “Hard phase” refers to a portion of the block copolymer having a glass transition temperature from 90 °C to 165 °C. “Soft phase” refers to a portion of the block copolymer having a glass transition less than -20 °C.

[0032] As described above, the polymer pellet comprises a thermoplastic elastomer derived at least in part from conjugated diene monomers and / or a thermoplastic elastomer comprising at least one cross-linkable functional group reactive to silane in the presence of peroxide, and optionally, one or more of a plasticizer, a tackifier, and additive(s). The thermoplastic elastomer may be pelletized into standard sized pellets, or may be otherwise cut to create beads, rods, films, and the like. Those skilled in the art will appreciate that polymer pellets may be prepared using a pelletizer (e.g. underwater pelletizer, water-ring pelletizer, or strand pelletizer). In accordance with the present disclosure, the size of the polymer pellet may be characterized by the number of pellets present per gram. In any of the exemplary embodiments, the polymer pellet may have a size inthe range of 20 to 100 pellets / gram, such as, for example, 40 to 70 pellets / gram, 35 to 65 pellets / gram, and 30 to 60 pellets / gram.Crosslinking Composition

[0033] The crosslinking composition of the cross-linkable thermoplastic polymer blends comprises a silane crosslinker and an organic peroxide. The crosslinking composition causes silane grafting of the thermoplastic elastomer at carbon-carbon double bonds located on the conjugated diene residues and / or other cross-linkable functional groups (such as those in Group B thermoplastic elastomers), such that the thermoplastic elastomer is crosslinked by the silane crosslinker.

[0034] The silane crosslinker of the crosslinking composition may comprise various silanes. Examples of suitable silanes include the silane represented by the following formula:SiRxf x wherein x is 1-4, and each R is individually and independently a monovalent hydrocarbon group or a monovalent alkoxy group.

[0035] In accordance with the present disclosure, the monovalent hydrocarbon group may be a linear, cyclic, or branched group. The monovalent hydrocarbon group may have 1-12 carbon atoms, 2-10 carbon atoms, or 3-8 carbon atoms. The monovalent hydrocarbon group may include one or more carbon-carbon double bonds. The monovalent hydrocarbon group may include one or more aromatic groups.

[0036] In accordance with the present disclosure, the monovalent alkoxy group may be a monovalent hydrocarbon group attached to an oxygen atom. The monovalent hydrocarbon group of the monovalent alkoxy group may be a linear, cyclic, or branched group. The monovalent hydrocarbon group of the monovalent alkoxy group may have 1-12 carbon atoms, 2-10 carbon atoms, or 3-8 carbon atoms. The monovalent hydrocarbon group of the monovalent alkoxy group may include one or more double carbon-carbon bonds. The monovalent hydrocarbon group of the monovalent alkoxy group may include one or more aromatic groups.

[0037] In any of the exemplary embodiments, the silane crosslinker may comprise vinyl trialkoxysilane. For example, the silane crosslinker may comprise vinyl trimethoxysilane, vinyl triethoxysilane, or a combination thereof.

[0038] The silane crosslinker may have a specific gravity greater than or equal to about 0.90 or greater than or equal to about 0.95. The silane may have a specific gravity less than or equal to about 1.05 or less than or equal to about 1. The silane may have a specific gravity from about 0.90 to about 1.05, from about 0.90 to about 1.00, from about 0.95 to about 1.05, or from about 0.95 to about 1.00, or any and all subranges formed from any of these endpoints.

[0039] In any of the aspects disclosed herein, the silane crosslinker may have a boiling point greater than or equal to about 75 °C or greater than or equal to about 100 °C. The silane crosslinker may have a boiling point less than or equal to about 150 °C or less than or equal to about 125 °C. For example, the silane crosslinker may have a boiling point from about 75 °C to about 150 °C, from about 75 °C to about 125 °C, from about 100 °C to about 150 °C, or from about 100 °C to about 125 °C, or any and all subranges formed from any of these endpoints.

[0040] In any of the aspects disclosed herein, the silane crosslinker may have a number average molecular weight greater than or equal to about 50 g / mol, greater than or equal to about 100 g / mol, greater than or equal to 150 g / mol, or greater than or equal to about 200 g / mol. The silane crosslinker may have a number average molecular weight less than or equal to about 500 g / mol, less than or equal to about 400 g / mol, or less than or equal to about 300 g / mol. The silane crosslinker may have a number average molecular weight from about 50 g / mol to about 500 g / mol, from about 50 g / mol to about 400 g / mol, from about 50 g / mol to about 300 g / mol, from about 100 g / mol to about 500 g / mol, from about 100 g / mol to about 400 g / mol, from about 100 g / mol to about 300 g / mol, from about 150 g / mol to about 500 g / mol, from about 150 g / mol to about 400 g / mol, from about 150 g / mol to about 300 g / mol, from about 200 g / mol to about 500 g / mol, from about 200 g / mol to about 400 g / mol, or from about 200 g / mol to about 300 g / mol, or any and all subranges formed from any of these endpoints.

[0041] Examples of suitable silane crosslinkers that are commercially available include grade A-171 vinyltrimethoxy silane under SILQUEST brand from Momentive.

[0042] As mentioned above, the crosslinking composition further includes an organic peroxide. The organic peroxide of the crosslinking composition may comprise various peroxides and is not particularly limited. Examples of suitable peroxides include the peroxide represented by the following formula:R-O-O-R wherein each R is individually and independently a monovalent hydrocarbon group. In accordance with the present disclosure, the monovalent hydrocarbon group of the organic peroxide may be a linear, cyclic, or branched group. The monovalent hydrocarbon group of the organic peroxide may have 1-16 carbon atoms, 3-12 carbon atoms, or 5-10 carbon atoms. The monovalent hydrocarbon group of the organic peroxide may include one or more carbon-carbon double bonds. The monovalent hydrocarbon group of the organic peroxide may include one or more aromatic groups. In accordance with the present disclosure, the organic peroxide may comprise peroxyketal peroxide, di-tert alkyl peroxide, or a combination thereof. For example, the organic peroxide may comprise dicumyl peroxide (a di-tert alkyl peroxide).

[0043] In accordance with the present disclosure, the organic peroxide may have a density greater than or equal to about 1.00 g / cm3or greater than or equal to about 1.05 g / cm3. The organic peroxide may have a density less than or equal to about 1.20 g / cm3or less than or equal to about 1.15 g / cm3. The organic peroxide may have a density from about 1 .00 g / cm3to about 1 .20 g / cm3, from about 1.00 g / cm3to about 1.15 g / cm3, from about 1.05 g / cm3to about 1.20 g / cm3, or from about 1.05 g / cm3to about 1.15 g / cm3, or any and all subranges formed from any of these endpoints.

[0044] Examples of suitable organic peroxide that are commercially available include grade BC-FF dicumyl peroxide under the PERK DOX brand from AkzoNobel.

[0045] In accordance with the present disclosure, the weight ratio based on dry weight of the silane crosslinker and the organic peroxide in the crosslinking composition may be 3 : 1 or more, 4: 1 or more, or 5: 1 or more. The weight ratio based on dry weight of the silane crosslinker and the organic peroxide in the crosslinking composition may be 20: 1 or less, 15: 1 or less, or 10:1 or less. The weight ratio based on dry weight of the silane crosslinker and the organic peroxide inthe crosslinking composition may be from 3:1 to 20: 1, from 3: 1 to 15: 1, from 3:1 to 10: 1, from 4: 1 to 20: 1, from 4: 1 to 15: 1, from 4: 1 to 10: 1, from 5:1 to 20: 1, from 5: 1 to 15: 1, from 5: 1 to 10: 1, or any and all subranges formed from any of these endpoints. The dry weight of the silane crosslinker and the organic peroxide in the crosslinking composition may be from 0.5 to 10% of the mass of the thermoplastic elastomer in the polymer pellet, including from 1% to 8%, from 2 to 7%, and from 3 to 6%.

[0046] In any of the aspects disclosed herein, the crosslinking composition may be present as a dry silane masterbatch comprising a carrier material loaded with the silane crosslinker and organic peroxide. The carrier material may comprise porous pellets, a filler material (e.g., silica, talc, calcium carbonate, microspheres, etc.), or a combination thereof. The porous pellets may comprise high porosity pellets, such as plastics selected from polypropylene, ethylene vinyl acetate, polyethylene, and mixtures thereof. The carrier material may be loaded by soaking the carrier material in a solution containing the silane crosslinker, the organic peroxide, and other components, if present (e.g., moisture cure catalyst and / or additives), and drying the carrier material to remove solvents in the solution. The silane / peroxide loading of the carrier material may be 20% or more, 30% or more, or 40% or more, based on the dry weight ratio of silane / peroxide to carrier. The silane / peroxide loading of the carrier material may be 80% or less, 70% or less, or 60% or less, based on the dry weight ratio of silane / peroxide to carrier. The silane / peroxide loading of the carrier material may be from 20% to 80%, from 20% to 70%, from 20% to 60%, from 30% to 80%, from 30% to 70%, from 30% to 60%, from 40% to 80%, from 40% to 70%, from 40% to 60%, or any and all subranges formed from any of these endpoints, based on the dry weight ratio of silane / peroxide to carrier. The dry silane masterbatch may be dry blended with the polymer pellet and fed to extrusion or injection molding processes for crosslinking the thermoplastic elastomer.

[0047] The crosslinking composition may be present in the form of a solution, dispersion, or emulsion, with the solution, dispersion, or emulsion comprising the silane crosslinker and the organic peroxide. The crosslinking composition may be blended with the porous pellet to form the dry silane masterbatch, which may then be fed to an extrusion or injection molding process for crosslinking the thermoplastic elastomer. Alternatively, or in addition to the dry silane, thesolution, dispersion, or emulsion of the crosslinking composition may be injected directly into the melt polymer pellet during extrusion or injection molding.

[0048] The solution, dispersion, or emulsion of the crosslinking composition may include from about 0.5 wt.% to about 5 wt.% of the silane. In any of the exemplary embodiments, the amount of silane in the solution, dispersion, or emulsion may be greater than or equal to about 0.5 wt.%, including, for example, at least 0.75 wt.%, at least 0.9 wt.%, at least 1 wt.%, at least 1.25 wt.%, at least 1.5 wt.%, at least 1.75 wt.%, or at least 2 wt.%, including all the endpoints and subranges therebetween. In any of the exemplary embodiments, the amount of silane in the solution, dispersion, or emulsion may be less than or equal to about 5 wt.%, including, for example, less than or equal to about 4.75 wt.%, less than or equal to 4.5 wt.%, less than or equal to 4.2 wt.%, less than or equal to 4 wt.%, less than or equal to 3.7 wt.%, less than or equal to 3.5 wt.%, less than or equal to 3.2 wt.%, or less than or equal to about 3 wt. %, including all endpoints and subranges therebetween. The amount of silane in the solution, dispersion, or emulsion may be from 0.5 wt.% to 5 wt.%, including, for example, from 0.5 wt.% to about 4 wt.%, from about 0.5 wt.% to about 3 wt.%, from about 1 wt.% to about 5 wt.%, from about 1 wt.% to about 4 wt.%, or from about 1 wt.% to about 3 wt.%, including any endpoints and subranges therebetween.

[0049] While not wishing to be bound by theory, it is believed that increasing the organic peroxide amount in the crosslinking composition improves the crosslink density and heat resistance of the resulting crosslinked thermoplastic elastomer. In any of the aspects disclosed herein, the solution, dispersion, or emulsion of the crosslinking composition may comprise from about 0.05 wt.% to about 1 wt.% of the organic peroxide. The amount of organic peroxide in the solution, dispersion, or emulsion may be greater than or equal to about 0.05 wt.%, greater than or equal to about 0.1 wt.%, or even greater than or equal to about 0.2 wt.%. The amount of organic peroxide in the solution, dispersion, or emulsion may be less than or equal to about 1 wt.%, less than or equal to about 0.8 wt.%, less than or equal to about 0.6 wt.%, or even less than or equal to about 0.4 wt.%. The amount of organic peroxide in the solution, dispersion, or emulsion may be from about 0.05 wt.% to about 1 wt.%, from about 0.05 wt.% to about 0.8 wt.%, from about 0.05 wt.% to about 0.6 wt.%, from about 0.05 wt.% to about 0.4 wt.%, from about 0.1 wt.% to about 1 wt.%, from about 0.1 wt.% to about 0.8 wt.%, from about 0.1 wt.% to about 0.6 wt.%, from about0.1 wt.% to about 0.4 wt.%, from about 0.2 wt.% to about 1 wt.%, from about 0.2 wt.% to about0.8 wt.%, from about 0.2 wt.% to about 0.6 wt.%, or from about 0.2 wt.% to about 0.4 wt.%, including all endpoints and subranges therebetween.Moisture Cure Catalyst

[0050] As described above, the thermoplastic elastomer in the polymer pellet may comprise Group A polymers, comprising highly reactive thermoplastic elastomers derived at least in part from conjugated diene monomers. The carbon-carbon double bonds on conjugated diene residues in Group A polymers react quickly with the silane crosslinker in the presence of the organic peroxide. Therefore, when the polymer pellet comprises Group A polymers, the cross-linkable thermoplastic polymer blend may not need additional catalyst or further crosslinking steps after the conversion process.

[0051] On the other hand, the thermoplastic elastomer in the polymer pellet may comprise Group B polymers comprising at least one cross-linkable functional group reactive to silane in the presence of peroxide. The cross-linkable functional group may not be as reactive toward the silane crosslinker as the carbon-carbon double bonds in Group A polymers. Therefore, when the polymer pellet comprises Group B polymers, a moisture cure catalyst may be included in the cross-linkable thermoplastic polymer blend in order to increase the reaction rate of crosslinking.

[0052] The moisture cure catalyst, including whether or not to include a moisture cure catalyst in the cross-linkable thermoplastic polymer blend, may be selected depending on the thermoplastic elastomer (e.g., Group A or Group B), the application of the crosslinked thermoplastic elastomer, and / or regulation compliance requirements. For example, since catalysts may affect the shelf life of the crosslinked thermoplastic elastomer, they are avoided in certain applications to extend shelf life, such as hot melt adhesive film where film rolls are extruded and stored for up to several months in warehouse before lamination. In certain applications, in addition to or instead of using moisture cure catalysts, the extruded or injection molded polymer blend is washed with water for post moisture curing. In certain applications such as consumer products and medical uses, tin catalyst is avoided for regulatory reason.

[0053] Accordingly, in accordance with the present disclosure, the cross-linkable thermoplastic polymer blend may further comprise a moisture cure catalyst. Examples of suitable moisture cure catalysts include tin catalyst, such as dibutyltin dilaurate, and non-tin catalyst. The amount of the moisture cure catalyst relative to the thermoplastic elastomer may be from 0.01 wt.% to 1 wt.%, including 0.05 wt.% to 0.8 wt.%, 0.1 wt.% to 0.6 wt.%, and 0.2 wt.% to 0.4 wt.%. Alternatively, the cross-linkable thermoplastic polymer blend may not include any moisture cure catalyst.

[0054] The moisture cure catalyst may be present in the dry silane masterbatch together with the crosslinking composition, or in the solution, dispersion, or emulsion comprising the crosslinking composition. Alternatively, the moisture cure catalyst may be present in a separate component which is blended with the polymer pellet and the crosslinking composition before feeding the cross-linkable thermoplastic polymer blend to extrusion or injection molding processes. For example, the moisture cure catalyst may be present in a dry masterbatch comprising a carrier material (e.g., ENGAGE 8842 polyolefin elastomer by Dow Chemical) loaded with the catalyst in an amount of, for example, from 0.1 wt.% to 5 wt.%, including from 0.5 wt.% to 4 wt.%, from 0.8 wt.% to 3 wt.%, and from 1.0 wt.% to 2 wt.%. Alternatively, the moisture cure catalyst may be present in a solvent comprising the catalyst in an amount of, for example, from 0.1 wt.% to 10 wt.%, including from 0.5 wt.% to 8 wt.%, from 1 wt.% to 6 wt.%, and from 1.5 wt.% to 4 wt.%.Olefin Polymer

[0055] In accordance with the present disclosure, the cross-linkable thermoplastic polymer blend may further comprise an olefin polymer to tailor hardness and mechanical properties and improve flow properties. The olefin polymer may comprise polyolefin, polyolefin elastomer, or a combination thereof. For example, suitable examples of polyolefin include polypropylene, polyethylene, or a combination thereof. The polyolefin may be at least one of high-density polyethylene (e.g., greater than or equal to 0.940 g / cm3) or a crystalline polypropylene with a percent crystallinity of at least about 60%.

[0056] In accordance with the present disclosure, the olefin polymer may comprise polypropylene. The polypropylene may comprise a polypropylene homopolymer (i.e., composed of propylene monomers) or a polypropylene copolymer having greater than 50 wt.% propylene monomer and one or more additional comonomer such as C2 and C4-C12 alpha olefins. The polyethylene may comprise a polyethylene homopolymer (i.e., composed of ethylene monomers) or a polyethylene copolymer having greater than 50 wt.% ethylene monomer and an additional comonomer, such as C3-C12 alpha olefins. The polypropylene may have a melt flow rate (230 °C / 2.16 kg) greater than or equal to about 0.1 g / 10 min, greater than or equal to about 0.5 g / 10 min, greater than or equal to about 1 g / 10 min, or even greater than or equal to about 3 g / 10 min. The polypropylene may have a melt flow rate (230 °C / 2.16 kg) less than or equal to about 10 g / 10 min or even less than or equal to about 5 g / 10 min. The polypropylene may have a melt flow rate (230 °C / 2.16 kg) from about 0.1 g / 10 min to about 10 g / 10 min, from about 0.1 g / 10 min to about 5 g / 10 min, from about 0.5 g / 10 min to about 10 g / 10 min, from about 0.5 g / 10 min to about 5 g / 10 min, from about 1 g / 10 min to about 10 g / 10 min, from about 1 g / 10 min to about 5 g / 10 min, from about 3 g / 10 min to about 10 g / 10 min, or from about 3 g / 10 min to about 5 g / 10 min, or any and all subranges formed from any of these endpoints.

[0057] In accordance with the present disclosure, the polyolefin may have a density greater than or equal to about 0.80 g / cm3or even greater than or equal to about 0.85 g / cm3. The polyolefin may have a density less than or equal to about 1.10 g / cm3or even less than or equal to about 1.00 g / cm3. The polyolefin may comprise a density from about 0.80 g / cm3to about 1.10 g / cm3, from about 0.80 g / cm3to about 1.00 g / cm3, from about 0.85 g / cm3to about 1.10 g / cm3, or from about 0.85 g / cm3to about 1.00 g / cm3, or any and all subranges formed from any of these endpoints.

[0058] In accordance with the present disclosure, the polyolefin may have a melting point greater than or equal to about 100 °C, greater than or equal to about 110 °C, or even greater than or equal to about 120 °C.

[0059] In accordance with the present disclosure, the polyolefin may have a tensile strength at yield greater than or equal to about 25 MPa or even greater than or equal to about 30 MPa. The polyolefin may have a tensile strength at yield less than or equal to about 45 MPa or even less than or equal to about 40 MPa. The polyolefin may have a tensile strength at yield from about 25 MPato about 45 MPa, from about 25 MPa, to about 40 MPa, from about 30 MPa to about 45 MPa, or from about 30 MPa to about 40 MPa, or any and all subranges formed from any of these endpoints.

[0060] In accordance with the present disclosure, the polyolefin may have a tensile elongation at yield greater than or equal to about 3% or even greater than or equal to about 5%. The polyolefin may have a tensile elongation at yield less than or equal to about 20% or even less than or equal to about 15%. The polyolefin may have a tensile elongation at yield from about 3% to about 20%, from about 3% to about 15%, from about 5% to about 20%, or from about 5% to about 15%, or any and all subranges formed from any of these endpoints.

[0061] Examples of suitable polyolefins that are commercially available include polypropylene homopolymer grade 1102KR under the FORMOLENE brand from Formosa Plastics.

[0062] In accordance with the present disclosure, the polyolefin elastomer may comprise polypropylene elastomer. Examples of suitable polyolefin elastomers that are commercially available include polypropylene elastomer grades Vistamaxx 6201 and 6202 under the VISTAMAXX brand from Exxon.

[0063] In accordance with the present disclosure, the polyolefin elastomer may comprise olefin block copolymer, ethylene alpha-olefin copolymer, or a combination thereof. The olefin block copolymer may comprise an ethylene alpha-olefin repeating unit. The ethylene alpha-olefin repeating unit is the polymerized reaction product of ethylene and C3-C12 olefins. For example, the ethylene alpha-olefin repeating unit may comprise ethyl ene-octene copolymer, ethylenehexene copolymer, ethyl ene-butene copolymer, or a combination thereof.

[0064] In accordance with the present disclosure, the olefin block copolymer may have a melt flow rate (190 °C / 2.16 kg) greater than or equal to about 1 g / 10 min or even greater than or equal to about 5 g / 10 min. The olefin block copolymer may have a melt flow rate (190 °C / 2.16 kg) less than or equal to about 25 g / 10 min or even less than or equal to about 20 g / 10 min. The olefin block copolymer may have a melt flow rate (190 °C / 2.16 kg) from about 1 g / 10 min to about 25 g / 10 min, from about 1 g / 10 min to about 20 g / 10 min, from about 5 g / 10 min to about 25 g / 10min, or from about 5 g / 10 min to about 20 g / 10 min, or any and all subranges formed from any of these endpoints.

[0065] In accordance with the present disclosure, the olefin block copolymer may have a density greater than or equal to about 0.80 g / cm3or even greater than or equal to about 0.85 g / cm3. The olefin block copolymer may have a density less than or equal to about 0.95 g / cm3or even less than or equal to about 0.90 g / cm3. The olefin block copolymer may have a density from about 0.80 g / cm3to about 0.95 g / cm3, from about 0.80 g / cm3to about 0.90 g / cm3, from about 0.85 g / cm3to about 0.95 g / cm3, or from about 0.85 g / cm3to about 0.90 g / cm3, or any and all subranges formed from any of these endpoints.

[0066] In accordance with the present disclosure, the olefin block copolymer may have a Shore A hardness greater than or equal to about 50 or even greater than or equal to about 60. The olefin block copolymer may have a Shore A hardness less than or equal to about 85 or even less than or equal to about 75. The olefin block copolymer may have a Shore A hardness from about 50 to about 85, from about 50 to about 75, from about 60 to about 85, or from about 60 to about 75, or any and all subranges formed from any of these endpoints.

[0067] Examples of suitable olefin block copolymers that are commercially available include 9500 and 9817 under the Infuse brand from Dow Chemical Company.

[0068] The ethylene alpha-olefin copolymer is the polymerized reaction product of ethylene and C3-C12 olefins. For example, the ethylene alpha-olefin copolymer may comprise ethyleneoctene copolymer, ethyl ene-hexene copolymer, ethylene-butene copolymer, or a combination thereof.

[0069] In accordance with the present disclosure, the ethylene-alpha olefin copolymer may have a melt flow rate (190 °C / 2.16 kg) greater than or equal to 0.1 g / 10 min or even greater than or equal to 0.25 g / 10 min. The ethylene-alpha olefin copolymer may have a melt flow rate (190 °C / 2.16 kg) less than or equal to 3 g / 10 min or even less than or equal to 1 g / 10 min. The ethylenealpha olefin copolymer may have a melt flow rate (190 °C / 2.16 kg) from 0.1 g / 10 min to 3 g / 10min, from 0.1 g / 10 min to 1 g / 10 min, from 0.25 g / 10 min to 3 g / 10 min, or even from 0.25 g / 10 min to 1 g / 10 min, or any and all subranges formed from any of these endpoints.

[0070] In accordance with the present disclosure, the ethylene-alpha olefin copolymer may have a density greater than or equal to 0.80 g / cm3or even greater than or equal to 0.85 g / cm3. The ethylene-alpha olefin copolymer may have a density less than or equal to 0.95 g / cm3or even less than or equal to 0.90 g / cm3. The ethylene-alpha olefin copolymer may have a density from 0.80 g / cm3to 0.95 g / cm3, from 0.80 g / cm3to 0.90 g / cm3, from 0.85 g / cm3to 0.95 g / cm3, or even from 0.85 g / cm3to 0.90 g / cm3, or any and all subranges formed from any of these endpoints.

[0071] In accordance with the present disclosure, the ethylene-alpha olefin copolymer may have a Mooney viscosity (ML 1+4, 121 °C) greater than or equal to 20, greater than or equal to 30, or even greater than or equal to 40. The ethylene-alpha olefin copolymer may have a Mooney viscosity (ML 1+4, 121 °C) less than or equal to 70, less than or equal to 60, or even less than or equal to 50. The ethylene-alpha olefin copolymer may have a Mooney viscosity (ML 1+4, 121 °C) from 20 to 70, from 20 to 60, from 20 to 50, from 30 to 70, from 30 to 60, from 30 to 50, from 40 to 70, from 40 to 60, or from 40 to 50, or any and all subranges formed from any of these endpoints.

[0072] In accordance with the present disclosure, the ethylene-alpha olefin copolymer may have a Shore A hardness greater than or equal to 40 or even greater than or equal to 45. The ethylene-alpha olefin copolymer may have a Shore A hardness less than or equal to 60 or even less than or equal to 65. The ethylene-alpha olefin copolymer may have a Shore A hardness from 40 to 60, from 40 to 55, from 45 to 60, or from 45 to 55, or any and all subranges formed from any of these endpoints.

[0073] Examples of suitable ethylene-alpha olefin copolymers that are commercially available include XLT 8677 under the Engage brand from Dow Chemical Company.

[0074] In accordance with the present disclosure, the cross-linkable thermoplastic polymer blend may comprise from about 2 wt.% to about 50 wt.% of the olefin polymer, from about 4 wt.% to about 40 wt.% of the olefin polymer, or from about 6 wt.% to about 30 wt.% of the olefinpolymer. The amount of the olefin polymer in the cross-linkable thermoplastic polymer blend may be greater than or equal to about 2 wt.%, greater than or equal to about 4 wt.%, or even greater than or equal to about 6 wt.%. The amount of the olefin polymer in the cross-linkable thermoplastic polymer blend may be less than or equal to about 50 wt.%, less than or equal to about 40 wt.%, less than or equal to about 30 wt.%, less than or equal to about 20 wt.%, less than or equal to about 17 wt.%, less than or equal to about 15 wt.%, less than or equal to about 13 wt.%, or even less than or equal to about 10 wt.%. The amount of olefin polymer in the cross-linkable thermoplastic polymer blend may be from about 2 wt.% to about 50 wt.%, from about 2 wt.% to about 40 wt.%, from about 2 wt.% to about 30 wt.%, from about 2 wt.% to about 20 wt.%, from about 2 wt.% to about 17 wt.%, from about 2 wt.% to about 15 wt.%, from about 2 wt.% to about 13 wt.%, from about 2 wt.% to about 10 wt.%, from about 4 wt.% to about 50 wt.%, from about 4 wt.% to about 40 wt.%, from about 4 wt.% to about 30 wt.%, from about 4 wt.% to about 20 wt.%, from about 4 wt.% to about 17 wt.%, from about 4 wt.% to about 15 wt.%, from about 4 wt.% to about 13 wt.%, from about 4 wt.% to about 10 wt.%, from about 6 wt.% to about 50 wt.%, from about 6 wt.% to about 40 wt.%, from about 6 wt.% to about 30 wt.%, from about 6 wt.% to about 20 wt.%, from about 6 wt.% to about 17 wt.%, from about 6 wt.% to about 15 wt.%, from about 6 wt.% to about 13 wt.%, or from about 6 wt.% to about 10 wt.%, or any and all subranges formed from any of these endpoints.Plasticizer

[0075] In accordance with the present disclosure, the cross-linkable thermoplastic polymer blend composition may further comprise a plasticizer. The plasticizer may be present in the polymer pellet, the crosslinking composition, or both. The plasticizer may help to improve flow in the cross-linkable thermoplastic polymer blend. In accordance with the present disclosure, the plasticizer may comprise non-polar plasticizer (e.g., mineral oil).

[0076] In accordance with the present disclosure, the amount of plasticizer in the crosslinkable thermoplastic polymer blend may be greater than or equal to about 0 wt.%, greater than or equal to about 10 wt.%, greater than or equal to about 20 wt.%, greater than or equal to about 25 wt.%, greater than or equal to about 30 wt.%, or greater than or equal to about 35 wt.%. The amount of plasticizer in the cross-linkable thermoplastic polymer blend may be less than or equalto about 60 wt.%, less than or equal to about 55 wt.%, less than or equal to about 50 wt.%, less than or equal to about 45 wt.%, less than or equal to about 40 wt.%, or less than or equal to about 35 wt.%. The amount of plasticizer in the cross-linkable thermoplastic polymer blend may be from about 0 wt.% to about 60 wt.%, including from about 10 wt.% to 55 wt.%, from about 20 wt.% to 50 wt.%, from about 25 wt.% to 45 wt.%, from about 30 wt.% to 40 wt.%, and any and all subranges formed from any of these endpoints.

[0077] Examples of suitable plasticizers that are commercially available include grade PSO 380 under the PURETOL brand from Petro-Canada.Tackifier

[0078] In accordance with the present disclosure, the cross-linkable thermoplastic polymer blend composition may further comprise a tackifier for adhesive applications (e.g., hot melt adhesive). The tackifier may be present in the polymer pellet, the crosslinking composition, or both.

[0079] In accordance with the present disclosure, the tackifier may comprise hydrocarbon resin. Exemplary hydrocarbon resins may include aliphatic resins (e.g., C5 resins), aromatic resins (e.g., C9 resins), di cyclopentadiene resins, and resins including a combination of two or more of aliphatic monomers, aromatic monomers, and dicyclopentadiene. The hydrocarbon resin may be hydrogenated. In accordance with the present disclosure, the hydrocarbon resin may have a number average molecular weight of less than or equal to about 2,000 g / mol, less than or equal to about 1,500 g / mol, less than or equal to about 1,200 g / mol, less than or equal to about 1, 100 g / mol, less than or equal to about 1,000 g / mol, or less than or equal to about 900 g / mol.

[0080] In accordance with the present disclosure, the cross-linkable thermoplastic polymer blend may comprise from about 15 wt.% to about 50 wt.% of the tackifier, or from about 17 wt.% to about 40 wt.% of the tackifier, or from about 20 wt.% to about 30 wt.% of the tackifier. The amount of tackifier in the cross-linkable thermoplastic polymer blend may be greater than or equal to about 15 wt.%, greater than or equal to about 17 wt.%, or even greater than or equal to about 20 wt.%. The amount of tackifier in the cross-linkable thermoplastic polymer blend may be less thanor equal to about 50 wt.%, less than or equal to about 40 wt.%, less than or equal to about 30 wt.%, less than or equal to about 27 wt.%, or even less than or equal to about 25 wt.%. The amount of tackifier in the cross-linkable thermoplastic polymer blend may be from about 15 wt.% to about 50 wt.%, from about 15 wt.% to about 40 wt.%, from about 15 wt.% to about 30 wt.%, from about 15 wt.% to about 27 wt.%, from about 15 wt.% to about 25 wt.%, from about 17 wt.% to about 50 wt.%, from about 17 wt.% to about 40 wt.%, from about 17 wt.% to about 30 wt.%, from about 17 wt.% to about 27 wt.%, from about 17 wt.% to about 25 wt.%, from about 20 wt.% to about 50 wt.%, from about 20 wt.% to about 40 wt.%, from about 20 wt.% to about 30 wt.%, from about 20 wt.% to about 27 wt.%, or even from about 20 wt.% to about 25 wt.%, or any and all subranges formed from any of these endpoints.

[0081] Examples of suitable tackifiers that are commercially available include grade R1140 under the PLASTOLYN brand from Eastman Chemicals.Co-crosslinkable Polymer

[0082] In accordance with the present disclosure, the cross-linkable thermoplastic polymer blend may further comprise a co-crosslinkable polymer, which may crosslink with the thermoplastic elastomer by the crosslinking composition.

[0083] In accordance with the present disclosure, the co-crosslinkable polymer may comprise ethylene-vinyl acetate. The ethylene-vinyl acetate may have a vinyl acetate content greater than or equal to about 10 wt.%, greater than or equal to about 25 wt.%, greater than or equal to about 40 wt.%, or even greater than or equal to 55 wt.%, based on a total weight of the ethylene-vinyl acetate. The ethylene-vinyl acetate may have a vinyl acetate content less than or equal to about 80 wt.%, less than or equal to about 70 wt.%, or even less than or equal to about 60 wt.%. The ethylene-vinyl acetate may have a vinyl acetate content from about 10 wt.% to about 80 wt.%, from about 10 wt.% to about 70 wt.%, from about 10 wt.% to about 60 wt.%, from about 25 wt.% to about 80 wt.%, from about 25 wt.% to about 70 wt.%, from about 25 wt.% to about 60 wt.%, from about 40 wt.% to about 80 wt.%, from about 40 wt.% to about 70 wt.%, from about 40 wt.% to about 60 wt.%, from about 55 wt.% to about 80 wt.%, from about 55 wt.% to about 70wt.%, or from about 55 wt.% to about 60 wt.%, or any and all sub-ranges formed from any of these endpoints.

[0084] In accordance with the present disclosure, the cross-linkable thermoplastic polymer blend may comprise from about 25 wt.% to about 45 wt.% of the co-crosslinkable polymer, or from about 27 wt.% to about 43 wt.% of the co-crosslinkable polymer, or from about 30 wt.% to about 40 wt.% of the co-crosslinkable polymer. The amount of the co-crosslinkable polymer in the cross-linkable thermoplastic polymer blend may be greater than or equal to about 25 wt.%, greater than or equal to about 27 wt.%, or even greater than or equal to about 30 wt.%. The amount of the co-crosslinkable polymer in the cross-linkable thermoplastic polymer blend may be less than or equal to about 45 wt.%, less than or equal to about 43 wt.%, or even less than or equal to about 40 wt.%. The amount of the co-crosslinkable polymer in the cross-linkable thermoplastic polymer blend may be from about 25 wt.% to about 45 wt.%, from about 25 wt.% to about 43 wt.%, from about 25 wt.% to about 40 wt.%, from about 27 wt.% to about 45 wt.%, from about 27 wt.% to about 43 wt.%, from about 27 wt.% to about 40 wt.%, from about 30 wt.% to about 45 wt.%, from about 30 wt.% to about 43 wt.%, or from about 30 wt.% to about 40 wt.%, or any and all subranges formed from any of these endpoints.

[0085] Examples of suitable co-crosslinkable polymers that are commercially available include grade 265 under the ELVAX brand from Dow Chemical Company.Additives

[0086] In accordance with the present disclosure, the cross-linkable thermoplastic polymer blend may further comprise an additive. The additive may comprise adhesion promoters; biocides; anti-fogging agents; anti-static agents; blowing and foaming agents; bonding agents and bonding polymers; dispersants; flame retardants and smoke suppressants; mineral fillers; initiators; lubricants; micas; pigments, colorants, and dyes; processing aids; release agents; silanes, titanates, and zirconates; slip and anti-blocking agents; stearates; ultraviolet light absorbers; viscosity regulators; waxes; or combinations thereof. Each of the additives may be present in the polymer pellet, the crosslinking composition, or both.Crosslinking of Thermoplastic Elastomer

[0087] In accordance with the present disclosure, the cross-linkable thermoplastic polymer blend, including the polymer pellet, the crosslinking composition, and optional components such as the moisture cure catalyst, can be blended and fed to conventional extrusion or injection molding processes.

[0088] In any of the exemplary embodiments, the cross-linkable thermoplastic polymer blend may include from 90 to 99.9 parts of the polymer pellet and 0.1 to 10 parts crosslinking composition, including, for example 94 to 99.5 parts polymer pellet and 0.5 to 5 parts crosslinking composition, based on dry weight of the crosslinking composition. In any of the exemplary embodiments, the cross-linkable thermoplastic polymer blend may comprise the crosslinking composition in an amount of 0.1% to 10%, including, for example, 0.2% to 6%, 0.3% to 4%, 0.5% to 3%, and 1.0% to 2%, based on dry weight of the crosslinking composition relative to the weight of the thermoplastic elastomer in the polymer pellet, including all endpoints and subranges therebetween.

[0089] Blending (also known as compounding) devices are well known to those skilled in the art and generally include feed means, especially at least one hopper for pulverulent materials and / or at least one injection pump for liquid materials; high-shear blending means, for example a co-rotating or counter-rotating twin-screw extruder, usually comprising a feed screw placed in a heated barrel (or tube); an output head, which gives the extrudate its shape; and means for cooling the extrudate, either by air cooling or by circulation of water. The extrudate is generally in the form of rods continuously exiting the device and able to be cut or formed into granules. However, other forms may be obtained by fitting a die of desired shape on the output die.

[0090] For example, the cross-linkable thermoplastic polymer blend may be fed to an extruder (e.g., 27 MM Leistriz Twin Extruder (L / D 52)) and blended. The blending (e.g., in the barrel of the extruder) may be carried out at a temperature from 240 °F to 500 °F (about 115 °C to about 260 °C). In accordance with the present disclosure, the blending results in carbon-carbon bond crosslinking and grafted silane moieties on the thermoplastic elastomer.

[0091] The extruded or injection molded polymer blend may further be subjected to post moisture curing. When the polymer pellet comprises Group B polymers, post moisture curing may be necessary for the cross-linkable functional groups to fully react with the silane crosslinker to form crosslinks. On the other hand, when the polymer pellet comprises Group A polymers, post moisture curing may not be necessary as the carbon-carbon double bonds on conjugated diene residues in Group A polymers are highly reactive to the silane crosslinker such that crosslinking is complete in the conversion process.

[0092] Post moisture curing can be performed by exposing the extruded or injection molded polymer blend to a moisture environment, such as the ambient moisture in a warehouse or a controlled laboratory environment (e.g., 80 °C and 90% relative humidity). Post moisture curing can also be performed by washing the extruded or injection molded polymer blend with water. The washing temperature and duration are selected depending on the polymer blend and / or the application. For example, hot water washing (e.g., as high as 80 °C) is effective for applications including thin film extrusion applications, such as laminated fabric comprising an extruded film between two layers of fabric.

[0093] After extrusion or injection molding, and the optional post moisture curing, the crosslinkable thermoplastic polymer blend forms a crosslinked thermoplastic elastomer. In accordance with the present disclosure, the crosslinked thermoplastic elastomer may generally be described as a thermoplastic elastomer with silane crosslinks.Properties

[0094] In accordance with the present disclosure, the crosslinked thermoplastic elastomer may have a tensile elongation at break from about 30% to about 725% as measured under ASTM D412. The crosslinked thermoplastic elastomer may have a tensile elongation at break greater than or equal to about 30%, greater than or equal to about 50%, greater than or equal to about 100%, greater than or equal to about 150%, or even greater than or equal to about 200%. The crosslinked thermoplastic elastomer may have a tensile elongation at break less than or equal to about 725%, less than or equal to about 700%, less than or equal to about 650%, less than or equal to about 600%, less than or equal to about 550%, less than or equal to about 500%, or even lessthan or equal to about 450%. The crosslinked thermoplastic elastomer may have a tensile elongation at break from about 30% to about 725%, from about 30% to about 700%, from about 30% to about 650%, from about 30% to about 600%, from about 30% to about 550%, from about30% to about 500%, from about 30% to about 450%, from about 50% to about 725%, from about50% to about 700%, from about 50% to about 650%, from about 50% to about 600%, from about50% to about 550%, from about 50% to about 500%, from about 50% to about 450%, from about100% to about 725%, from about 100% to about 700%, from about 100% to about 650%, from about 100% to about 600%, from about 100% to about 550%, from about 100% to about 500%, from about 100% to about 450%, from about 150% to about 725%, from about 150% to about 700%, from about 150% to about 650%, from about 150% to about 600%, from about 150% to about 550%, from about 150% to about 500%, from about 150% to about 450%, from about 200% to about 725%, from about 200% to about 700%, from about 200% to about 650%, from about 200% to about 600%, from about 200% to about 550%, from about 200% to about 500%, or from about 200% to about 450%, or any and all subranges formed from any of these endpoints.

[0095] In accordance with the present disclosure, the crosslinked thermoplastic elastomer may have a compression set from about 20% to about 90%, as measured at 100 °C. Compression set is measured in accordance with ASTM D395B. The crosslinked thermoplastic elastomer may have a compression set less than or equal to about 90%, including, for example, a compression set less than or equal to about 80%, less than or equal to about 70%, less than or equal to about 60%, less than or equal to about 55%, or less than or equal to about 50%, as measured at 100 °C. The crosslinked thermoplastic elastomer may have a compression set from 0% to about 90%, including for example, from about 10% to about 80%, from about 15% to about 70%, from about 20% to about 65%, from about 25% to about 60%, from about 27% to about 55%, from about 30% to about 50%, from about 35% to about 65%, or from about 40% to about 60%, or any and all subranges formed from any of these endpoints. Low compression set is indicative of high crosslink density, where 100% compression set indicates no crosslinks and 0% compression set indicates fully crosslinked thermoplastic elastomer.

[0096] In accordance with the present disclosure, the crosslinked thermoplastic elastomer may have a Shore A hardness greater than or equal to about 25 as measured under ASTM D2240,including, for example, greater than or equal to about 30, greater than or equal to about 35, greater than or equal to about 40, greater than or equal to about 45, greater than or equal to about 47, greater than or equal to about 50, greater than or equal to about 55, greater than or equal to about 57, or greater than or equal to about 60. The crosslinked thermoplastic elastomer may have a Shore A hardness less than about 95, including, for example, less than or equal to about 90, less than or equal to about 85, less than or equal to about 80, less than or equal to about 75, or even less than or equal to about 70. The crosslinked thermoplastic elastomer may have a Shore A hardness from about 25 to about 95, from about 27 to about 90, from about 30 to about 85, from about 33 to about 80, from about 35 to about 75, from about 30 to about 90, from about 30 to about 85, from about 30 to about 80, from about 30 to about 75, from about 30 to about 70, from about 35 to about 90, from about 35 to about 85, from about 35 to about 80, from about 35 to about 75, from about 35 to about 70, from about 40 to about 90, from about 40 to about 85, from about 40 to about 80, from about 40 to about 75, from about 40 to about 70, from about 45 to about 90, from about 45 to about 85, from about 45 to about 80, from about 45 to about 75, or from about 45 to about 70, or any and all subranges from any of these endpoints.

[0097] In accordance with the present disclosure, the crosslinked thermoplastic elastomer may have a tensile strength at break greater than or equal to about 1.5 MPa as measured under ASTM D412, greater than or equal to about 2.0 MPa, greater than or equal to about 2.5 MPa, or even greater than or equal to about 3.0 MPa. The crosslinked thermoplastic elastomer may have a tensile strength at break less than or equal to about 8.0 MPa, including, for example, less than or equal to about 7.5 MPa, less than or equal to about 7.0 MPa, less than or equal to about 6.5 MPa, or even less than or equal to about 6.0 MPa. The crosslinked thermoplastic elastomer may have a tensile strength at break from about 1.5 MPa to about 8.0 MPa, from about 1.5 MPa to about 7.5 MPa, from about 1.5 MPa to about 7.0 MPa, from about 1.5 MPa to about 6.5 MPa, from about1.5 MPa to about 6.0 MPa, from about 2.0 MPa to about 8.0 MPa, from about 2.0 MPa to about7.5 MPa, from about 2.0 MPa to about 7.0 MPa, from about 2.0 MPa to about 6.5 MPa, from about 2.0 MPa to about 6.0 MPa, from about 2.5 MPa to about 8.0 MPa, from about 2.5 MPa to about7.5 MPa, from about 2.5 MPa to about 7.0 MPa, from about 2.5 MPa to about 6.5 MPa, from about2.5 MPa to about 6.0 MPa, from about 3.0 MPa to about 8.0 MPa, from about 3.0 MPa to about7.5 MPa, from about 3.0 MPa to about 7.0 MPa, from about 3.0 MPa to about 6.5 MPa, or evenfrom about 3.0 MPa to about 6.0 MPa, or any and all subranges formed from any of these endpoints.

[0098] In accordance with the present disclosure, the crosslinked thermoplastic elastomer may have an increase in weight of 170% or less after 903 oil immersion at 125 °C for 3 days, including 160% or less, 150% or less, 140% or less, 130% or less, and 125% or less. Low increase in weight after oil immersion is indicative of high crosslink density, where thermoplastic elastomer with no crosslinks will dissolve when immersed in oil.Methods of Crosslinking Thermoplastic Elastomers

[0099] In accordance with the present disclosure, a method for forming a crosslinked thermoplastic elastomer comprises blending one or more of the polymer pellets and the crosslinking composition to form a thermoplastic polymer blend. As described above, the crosslinking composition may be present in a dry silane masterbatch, and the polymer pellets and the dry silane masterbatch are dry blended. The method further comprises melting the thermoplastic polymer blend to form a cross-linkable thermoplastic polymer melt, and extruding or injection molding the cross-linkable thermoplastic polymer melt to form a crosslinked thermoplastic elastomer. The method includes a one-step conversion process where the thermoplastic elastomer in the polymer pellet is crosslinked, and there is no separate silane grafting processes.

[0100] As described above, instead of the dry silane masterbatch, the crosslinking composition may be present in a solution, dispersion, or emulsion of the crosslinking composition comprising the silane crosslinker and the organic peroxide. Accordingly, instead of dry blending the polymer pellets and the dry silane masterbatch and then melting the thermoplastic polymer blend, the method may comprise blending one or more polymer pellets with the solution, dispersion, or emulsion, and melting the blend to form a cross-linkable thermoplastic polymer melt, which is further extruded or injection molded to form a crosslinked thermoplastic elastomer.

[0101] As described above, a moisture cure catalyst may be present in the dry silane masterbatch together with the crosslinking composition. Alternatively, the moisture cure catalyst may be present in a separate component, such as a solution of the moisture cure catalyst, whichcan be blended with the polymer pellets and the crosslinking composition (present in a dry silane masterbatch or a solution, dispersion, or emulsion) before melting, or injected into the crosslinkable thermoplastic polymer melt during the conversion process.

[0102] The method may further comprise a step of post moisture curing where the extruded or injection molded polymer blend is exposed to a moisture environment. As described above, the extruded or injection molded polymer blend may be exposed to the ambient moisture in a warehouse or a controlled laboratory environment (e.g., 80 °C and 90% relative humidity). Post moisture curing can also be performed by washing the extruded or injection molded polymer blend with water of various temperatures (e.g., 20 °C, 40 °C, or even 80 °C) for various durations (e.g.,2 hours, 10 hours, or 24 hours).EXAMPLES

[0103] Exemplary cross-linkable thermoplastic polymer blends were prepared to demonstrate crosslinking of thermoplastic polymers in a one-step conversion process and the properties of the crosslinked thermoplastic polymers. In Examples 1-6 below, pellets of thermoplastic polymers were dry blended with a solution of silane crosslinker and an organic peroxide. Alternatively, a dry silane masterbatch comprising a carrier material loaded with the silane crosslinker and the organic peroxide may be used, which does not change the mechanism or result of the crosslinking reactions. Optionally, a tin catalyst masterbatch was also dry blended at3 wt.% based on dry weight of the tin catalyst relative to the thermoplastic polymers in Examples using tin catalyst curing. For all Examples, the conversion process was injection molding with an injection molder. Alternatively, the conversion process may be extrusion, which is expected to have more favorable results due to steady state and longer residence time of the polymer melt.Example 1 : Thermoplastic Polymers Comprising SIS

[0104] Cross-linkable thermoplastic polymer blends were prepared with a mixture of SIS (styrene-isoprene block copolymer) and SEBS (styrene-ethylene-butylene-styrene polymer). A polyolefin SEEPS (styrene-ethylene-ethylene-propylene-styrene) was also added to the polymer blend. Crosslinked SIS has good damping properties, and crosslinked SEBS has good temperature resistance, such that they can be used in combination to incorporate these advantages in thecrosslinked thermoplastic polymers. SIS is a Group A polymer having highly reactive carboncarbon double bonds for crosslinking, and SEBS is a Group B polymer having cross-linkable functional groups other than carbon-carbon double bonds on diene residues. As shown in Examples 1 A and IB in Table 1 below, the mixture of SIS and SEBS had low crosslinking rate at conversion without the crosslinking composition, as demonstrated by a high compression set of 95%. However, as shown in Example IB, high crosslinking rate at conversion was achieved with addition of 1.0 wt.% crosslinking composition without the need of additional catalysts, as demonstrated by a low compression set of 50%. The odor was mild during conversion and significantly lower than silane grafting processes for SIS or SEBS.Table 1Example 2: Thermoplastic Polymers Comprising SBS

[0105] Cross-linkable thermoplastic polymer blends were prepared with SBS (styrene- butadiene-styrene) pellets. SBS is a Group A polymer having highly reactive carbon-carbon double bonds for crosslinking. As shown in Example 2A in Table 2 below, crosslinking did not occur at conversion without the crosslinking composition, as demonstrated by 100% compressionset. However, as shown in Example 2B, high crosslinking rate at conversion was achieved with addition of 0.5 wt.% crosslinking composition without the need of additional catalysts, as demonstrated by a low compression set of 52%. The odor was mild during conversion and significantly lower than silane grafting processes for SBS.Table 2Example 3: Thermoplastic Polymers Comprising EPDM and Paramethylstyrene (PMS) Block Copolymer

[0106] Cross-linkable thermoplastic samples were prepared by injection molding with different thermoplastic polymers, i.e., EPDM rubber (EX-3A and EX-3B; EX-3G and EX-3H), paramethylstyrene (PMS) block copolymer (EX-3E and EX-3F), and their 50 / 50 mixture (EX-3C and EX-3D). Moisture curing at 80 °C and 90% relative humidity was performed before testing the properties of the samples. As shown in Tables 3-1 and 3-2, the thermoplastic polymers crosslinked during conversion even without additional catalyst, as indicated by the compression sets from 55% to 67% at 100 °CZ 22h in EX-3A, EX-3C, and EX-3E. However, for each of the thermoplastic polymer formulations, the compression sets significantly decreased with addition of the tin catalyst, indicating a greater degree of crosslinking. In terms of properties of crosslinked thermoplastic polymers, the tensile elongation at yield decreased for each of the formulations withaddition of the tin catalyst. Furthermore, it was shown by EX-3G and EX-3H that the amount of polypropylene relative to EPDM rubber affects the hardness and tensile strength of the crosslinked thermoplastic polymer.Table 3-1Table 3-2Example 4: Thermoplastic Polymers Comprising EPDM / SBS or Paramethylstyrene (PMS) Block Copolymer / SBS

[0107] Cross-linkable thermoplastic samples were prepared by injection molding using different combinations of thermoplastic polymers EPDM rubber, paramethylstyrene (PMS) block copolymer, and SBS. For each of the formulations, two samples were prepared with and without additional catalyst, respectively. Moisture curing at 80 °C and 90% relative humidity was performed before testing the properties of the samples. As shown in Tables 4-1 and 4-2, the thermoplastic polymers crosslinked during conversion even without additional catalyst, as indicated by the compression sets from 42% to 60% (at 100 °C / 22h) and from 47% to 70% (at 125 °C / 22h). However, for each of the thermoplastic polymer formulations, the compression sets significantly decreased with addition of the tin catalyst, indicating a greater degree of crosslinking. In terms of properties of crosslinked thermoplastic polymers, the tensile elongation at yield decreased for each of the formulations with addition of the tin catalyst.Table 4-1Table 4-2Example 5 : Polyamide Overmolding Systems

[0108] Thermoplastic polymer blends were prepared as alternatives for existing nylon overmolding products. Applications of nylon overmolding may require temperature and / or oil resistance.

[0109] Cross-linkable thermoplastic polymer blends were prepared comprising either PMS block copolymer with a molecular weight of 300, 000 (Example 5 A) or PMS block copolymer with a molecular weight of 400,000 (Examples 5B). The exemplary compositions also included comparable concentrations of SEBS with maleic anhydride, vis oil, tackifier, polypropylene, nylon 6, amide wax, and an antioxidant. Example 5B further included talc filler. A tin catalyst masterbatch was optionally dry blended for each of the exemplary cross-linkable thermoplastic polymer blends. The products of conversion were subjected to post moisture curing at 80 °C, 90% relative humidity for 24 hours.

[0110] As shown in Examples 5A and 5B in Table 5 below, higher crosslinking rate at conversion was achieved with the tin catalyst compared to no tin catalyst, but good crosslinking rate, as demonstrated by low compression sets, was achieved even without the tin catalyst. The odor was mild during conversion of the two exemplary polymer blends and significantly lower than silane grafting processes for commercial nylon overmolding products.Table 5Example 6: Thermoplastic Polymers for Seam Tape Application

[0111] Cross-linkable thermoplastic samples were prepared by film extrusion of each of theExamples. A first thermoplastic polymer formulation comprising SEBS and EPDM rubber (EX- 6A, EX-6B, and EX-6C) and a second thermoplastic polymer formulation comprising different ratio of the components (EX-6D, EX-6E, and EX-6F) were prepared. For each formulation, a sample was extruded without addition of silane crosslinking composition, a sample was processed by twin extruder silane grafting followed by extrusion (i.e., the conventional two-step process), and a sample was processed by the one-step conversion process of the present disclosure. Theextruded films were laminated on fabrics at 360 °F. The samples are formed into seam tapes with 0.2 mm thickness. The sample with the one-step conversion was further washed with water at both sides.

[0112] As shown in Tables 6-1 and 6-2 below, the bonding properties of crosslinked thermoplastic polymers improved over the thermoplastic polymer without crosslinking. Furthermore, the crosslinked thermoplastic polymer by the one-step conversion achieved better bonding properties in comparison to the conventional process by twin extruder silane grafting, as demonstrated by better peel resistance before and after water immersion and peel retention. As such, the one-step conversion process significantly lowers manufacturing cost by eliminating the reaction extrusion process while improving the bonding properties of the crosslinked thermoplastic polymer. The one-step conversion process also significantly reduces the odor in comparison to the twin extruder silane grafting process.Table 6-1Table 6-2

[0113] It will be apparent that modifications and variations are possible without departing from the scope of the disclosure defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.

Claims

CLAIMS1. A cross-linkable thermoplastic polymer blend comprising: a polymer pellet comprising a thermoplastic elastomer derived at least in part from conjugated diene monomers; and a crosslinking composition comprising a silane crosslinker and an organic peroxide.

2. A cross-linkable thermoplastic polymer blend comprising: a polymer pellet comprising a thermoplastic elastomer comprising at least one crosslinkable functional group reactive to silane in the presence of peroxide; a crosslinking composition comprising a silane crosslinker and an organic peroxide; and a moisture cure catalyst.

3. The cross-linkable thermoplastic polymer blend of any one of claims 1 or 2, wherein the crosslinking composition is present in a dry silane masterbatch comprising a carrier material loaded with the silane crosslinker and the organic peroxide.

4. The cross-linkable thermoplastic polymer blend of claim 3, wherein the carrier material comprises a high porosity polymer selected from polypropylene, ethylene vinyl acetate, polyethylene, and mixtures thereof.

5. The cross-linkable thermoplastic polymer blend of any one of claims 1 or 2, wherein the crosslinking composition is present in a solution comprising the silane crosslinker and the organic peroxide.

6. The cross-linkable thermoplastic polymer blend of any one of claims 1-5, wherein the cross-linkable thermoplastic polymer blend comprises the crosslinking composition in an amount of 0.1% to 10% based on dry weight of the crosslinking composition relative to the weight of the thermoplastic elastomer in the polymer pellet.

7. The cross-linkable thermoplastic polymer blend of claim 1, wherein the thermoplastic elastomer comprises styrene block copolymers, styrene-butadiene rubber, styrene-butadiene blockcopolymers, styrene-isoprene block copolymers, styrene-butadiene-isoprene rubber, styrene- butadiene / isoprene block copolymers, styrene-butadiene-isoprene block copolymers, partially hydrogenated styrene-butadiene rubber, partially hydrogenated styrene-butadiene block copolymers, partially hydrogenated styrene-isoprene block copolymers, partially hydrogenated styrene-butadiene-isoprene rubber, partially hydrogenated styrene-butadiene / isoprene block copolymers, partially hydrogenated styrene-butadiene-isoprene block copolymers, or combinations thereof.

8. The cross-linkable thermoplastic polymer of claim 7, wherein the hydrogenated styrene block copolymer comprises styrene-ethylene-butylene-styrene copolymer.

9. The cross-linkable thermoplastic polymer blend of claim 2, wherein the thermoplastic elastomer comprises ethylene-propylene-diene rubber (EPDM), pms-SEBS (styrene-ethylene- butylene-styrene), heat cured silicone rubber (HCR), ethylene-propylene rub-ber (EPR), butyl rubber, halobutyl rubber, halogenated rubbery copolymers of p-alkyl styrene and at least one isomonoolefm having 4 to 7 carbon atoms, nitrile rubber and its copolymers, styrene-acrylate- acrylonitrile rubber, hydrogenated nitrile rubber, acrylate rubber and its copolymers, ethylene- acrylate-glycidyl methacrylate elastomer, partially hydrogenated styrene-butadiene rubber, polyamide elastomer, polyester elastomer, natural rubber, and a polyolefin copolymeric elastomer having at least two repeat units that are derived from the group consisting of ethylene, propylene, butene, hexene, and octene.

10. The cross-linkable thermoplastic polymer of any one of claims 1-9, wherein at least one of the polymer pellet and the crosslinking composition further comprises one or more of a plasticizer; a polyolefin; a filler; a hydrocarbon tackifier; and mixtures thereof.

11. The cross-linkable thermoplastic polymer blend of claim 10, wherein the polyolefin comprises polypropylene.

12. The cross-linkable thermoplastic polymer blend of any one of claims 10 or 11, wherein the plasticizer comprises an oil.

13. The cross-linked thermoplastic polymer blend of claim 2, wherein the crosslinking composition is present in a dry silane masterbatch comprising a carrier material loaded with the silane crosslinker and the organic peroxide, wherein the moisture cure catalyst is present in the dry silane masterbatch.

14. The cross-linked thermoplastic polymer blend of claim 2, wherein the moisture cure catalyst is present in a solution of the moisture cure catalyst.

15. The cross-linked thermoplastic polymer blend of claim 2, wherein the moisture cure catalyst is a tin-based catalyst.

16. The cross-linked thermoplastic polymer blend of claim 2, wherein the moisture cure catalyst is a non -tin-based catalyst.

17. The cross-linked thermoplastic polymer blend of any one of claims 1-16, wherein the crosslinked thermoplastic elastomer has a compression set of 70% or less.

18. The cross-linked thermoplastic polymer blend of any one of claims 1-17, wherein the crosslinked thermoplastic elastomer has an increase in weight of 170% or less after 903 oil immersion at 125 °C for 3 days.

19. A process for forming a crosslinked thermoplastic elastomer, the process comprising: dry blending one or more polymer pellets and a dry silane masterbatch to form a thermoplastic polymer blend, the polymer pellets comprising a thermoplastic elastomer, and the dry silane masterbatch comprising a carrier material loaded with a crosslinking composition comprising a silane crosslinker and an organic peroxide; melting the thermoplastic polymer blend to form a cross-linkable thermoplastic polymer melt; extruding or injection molding the cross-linkable thermoplastic polymer melt.

20. The process for forming a crosslinked thermoplastic elastomer according to claim 19, wherein the dry silane masterbatch further comprises a moisture cure catalyst.

21. A process for forming a crosslinked thermoplastic elastomer, the process comprising: melting one or more polymer pellets to form a thermoplastic polymer melt, the polymer pellets comprising a thermoplastic elastomer; injecting a solution of a crosslinking composition into the thermoplastic polymer melt to form a cross-linkable thermoplastic polymer melt, the crosslinking composition comprising a silane crosslinker and an organic peroxide; extruding or injection molding the cross-linkable thermoplastic polymer melt.

22. The process for forming a crosslinked thermoplastic elastomer according to claim 21, wherein the solution of the crosslinking composition further comprises a moisture cure catalyst.

23. The process for forming a crosslinked thermoplastic elastomer of any one of claims 19-22, further comprising exposing the extruded or injection molded cross-linkable thermoplastic polymer melt to moisture.

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