Abstract: A low compression, resilient golf ball having a center including a material formed from the conversion reaction of sufficient amounts of polybutadiene, a free radical source, and a cis-to-trans catalyst to convert a portion of cis-isomer to trans-isomer in the polybutadiene, which reaction occurs at a sufficient temperature to form the material that contains trans-isomer and cis-isomer, wherein said material has an amount of trans-isomer greater than the amount of trans-isomer present before the conversion reaction, at least one intermediate layer disposed about the center and including a resilient polymer component and a reinforcing polymer component present in an amount sufficient to provide an uncrosslinked first mixture having a rigidity as determined by a flexural modulus greater than about 3.5 MPa, wherein the center and each intermediate layer together form the core, and a cover being disposed about the core, wherein the golf ball has a diameter of at least about 1.68 inches.

Abstract: The present invention is directed to a curable, water-based coating composition utilized in waterborne coating systems. The coating composition is the reaction product of a water-based copolymer prepared by free-radical polymerization, and a cross-linking agent. The copolymer is the reaction product of a first block and a second block. The first block is the reaction product of a first ethylenically unsaturated monomer, acrylic acid, and a second ethylenically unsaturated monomer, methyl methacrylate, as wells as the reaction product of a vinylaromatic hydrocarbon monomer, diphenylethylene. The second block is the reaction product of a plurality of ethylenically unsaturated monomers, styrene, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and carbonate-modified glycidyl methacrylate including a carbonate functional group.

Abstract: A bulk polymerized grafted and crosslinkable thermoplastic polyolefin powder composition having elasticity and flexibility properties, which is in the form of a powder intended for the production of flexible coatings by free flow over a hot mold, characterized in that it contains: a) from 100 to 5% by weight and preferably from 80 to 20% by weight of at least one homopolymer of ethylene and/or at least one copolymer containing at least 50 molar % of ethylene; b) from 0 to 95% by weight and preferably from 20 to 80% by weight of at least one thermoplastic elastomer; c) from 0.1 to 15 parts by weight and preferably from 0.5 to 10 parts by weight of a grafting agent, per 100 parts by weight of the accumulated components “a” and “b”. This powder composition is suitable for the production of flexible coatings by its free flow over a hot mold.

Abstract: Random thermoplastic ethylene copolymers can be used to increase the elongation to break and toughness of thermoplastic vulcanizates. Polypropylene is a preferred thermoplastic phase. The rubber can be olefinic rubbers. Random thermoplastic ethylene copolymers are different from Ziegler-Natta ethylene copolymers as the compositional heterogeneity of the copolymer is greater with Ziegler-Natta copolymers. This difference results in substantial differences in properties (elongation to break and toughness) between thermoplastic vulcanizates modified with random thermoplastic ethylene and those modified with Ziegler-Natta ethylene copolymers. An increase in elongation to break results in greater extensibility in the articles made from a thermoplastic vulcanizate.

Abstract: A thermoplastic elastomer composition containing (A), (B-1) and (B-2) described below and having a total content of (B-1) and (B-2) of 10 to 250 parts by weight per 100 parts by weight of the content of (A), a complex dynamic viscosity &eegr;*(1) at 250 ° C. of 1.5×105 poise or less and a Newtonian viscosity index n of 0.67 or less, and pellets obtained by using the thermoplastic elastomer composition, and a molded article thereof: (A): a polyolefin-based resin; (B-1): a conjugated diene-based thermoplastic elastomer or its hydrogenated product providing two tan &dgr; peaks within a temperature range of −70 to 30° C.

Abstract: A bulk polymerized grafted and crosslinkable thermoplastic polyolefin powder composition having elasticity and flexibility properties, which is in the form of a powder intended for the production of flexible coatings by free flow over a hot mold, characterized in that it contains: a) from 100 to 5% by weight and preferably from 80 to 20% by weight of at least one homopolymer of ethylene and/or at least one copolymer containing at least 50 molar % of ethylene; b) from 0 to 95% by weight and preferably from 20 to 80% by weight of at least one thermoplastic elastomer; c) from 0.1 to 15 parts by weight and preferably from 0.5 to 10 parts by weight of a grafting agent, per 100 parts by weight of the accumulated components “a” and “b”. This powder composition is suitable for the production of flexible coatings by its free flow over a hot mold.

Abstract: A thermoplastic elastomeric resin composition for powder molding, comprising a composition prepared by dynamically vulcanizing (a) a block copolymer of a vinyl aromatic compound and a conjugated diene compound, and/or a hydrogenated block copolymer thereof, (b) a non-aromatic softening agent for rubber, (c) a peroxide-decomposing olefinic resin, (d) an unsaturated glycidyl compound, (e) an unsaturated carboxylic acid or a derivative thereof, and (f) a liquid polybutadiene, and (h) at least one material selected from the group consisting of polyester, polyurethane, and polyamide polymers and copolymers; characterized in that (p) a compound represented by the following chemical formula (I) is also comprised: H2C═CH—CH2—O—(CnH2nO)m—X  (I) wherein n is an integer of from 2 to 5, CnH2n may be branched, x represents H or CH═CH2, m is the number of the repeating unit, CnH2nO, and a number average molecular weight of the compound is in a range of from 200 to 6,000.

Abstract: A process is disclosed for the continuous production of an ABS resin. The polymerization step comprises at least two substeps, one being a first-stage substep of forming particles of the rubbery polymer and the other a second-stage substep of adjusting the particle sizes of the particles. The first-stage substep is conducted in a polymerization system making use of a plug flow reactor or a batch polymerization reactor, and conducts polymerization at least until the particles are formed in the polymerization mixture. The second-stage substep increases a converted amount of the monomer component into the polymer compared with that in the particle forming substep and makes the particles smaller. A polycarbonate-ABS resin composition is also disclosed.

Abstract: A rubber composition comprising (A) a rubber ingredient comprised of (a) a nitrile group-containing highly saturated copolymer rubber having an iodine value of not larger than 120, preferably a hydrogenated product of an unsaturated nitrile-conjugated diene copolymer rubber, and (b) an acrylic ester polymer rubber, preferably a copolymer rubber comprising at least 80 mol % of alkyl acrylate or alkoxyalkyl acrylate units, at an (a)/(b) ratio of 40/60 to 90/10 by weight, and (B) an ethylene-&agr;-olefin copolymer, the (A)/(B) ratio being in the range of 30/70 to 70/30 by weight. This rubber composition is useful as a covering material for forming a protective covering layer on electric wires.

Abstract: Disclosed is a method of preparing a blended thermoplastic resin composition that includes combining a ground crosslinked rubber with a thermoplastic material and a compatibilizer, and the products formed thereby. The ground crosslinked rubber has an average particle size of about 80 mesh or smaller. The thermoplastic material can be a polyolefinic resin or a polyolefinic elastomer or olefinic vulcanizate elastomer. The ground crosslinked rubber is included in amounts of up to 70% by weight, based on the total weight of the blended thermoplastic composition.

Abstract: A golf ball core formed from a composition including a (i) cobalt catalyzed polybutadiene and (ii) a blend of lanthanide catalyzed polybutadienes having Mooney viscosities of about 30-70.

Abstract: A polymer composition, a process for its preparation and a molded article formed from the polymer composition are claimed. The polymer composition comprises (a) a base polymer that is a poly(alkyl(meth)acrylate; and (b) a rubber toughening agent selected from the group consisting of (i) copolymers of (alkyl)acrylate rubbers, (ii) copolymers of vinyl aromatic monomers with (alkyl)acrylates, (iii) copolymers of vinyl aromatic monomers with conjugated diolefins; (iv) copolymers of vinyl aromatic monomers with monoethylenically unsaturated monomers, in which the rubber toughening agent is present in the polymer composition as discrete islands substantially surrounded by the base polymer and in which islands are sub-islands of the base polymer.

Abstract: A compatibilized blend of general purpose rubbers (GPR) and benzyl halide polymers are produced through solventless reactions utilizing a multifunctional agent containing a diene reactive group and a benzylic halo reactive group.

Abstract: A fluorine-containing graft copolymer is made from a backbone of an olefin polymer material to which is graft polymerized (a) at least one gaseous fluorinated monomer such as vinylidene fluoride, (b) at least one fluorinated acrylic acid or ester, (c) a mixture of (a) and (b), or (d) a mixture of (a) and/or (b) and a non-fluorinated monomer such as methyl methacrylate. An organic peroxide or a polymeric peroxide is used as the initiator for the graft polymerization process. The graft copolymers have improved surface properties and oxygen barrier properties, and improved thermal stability.

Abstract: Disclosed herein is a game ball and method for making the same. The game ball has an ionomeric cover which includes a combination of ionomeric crosslinks and covalent crosslinks. The game ball cover is superior in at least one of cut resistance and scuff resistance to a conventional cover that does not have covalent crosslinks but is otherwise substantially identical in composition. The game ball cover of the invention is particularly useful for improving the durability of golf balls to be struck with sharp-grooved clubs.

Abstract: A bulk polymerized grafted and crosslinkable thermoplastic polyolefin powder composition having elasticity and flexibility properties, which is in the form of a powder intended for the production of flexible coatings by free flow over a hot mold, characterized in that it contains:

Abstract: There is a need for halogen-free polymeric compositions for utilization in gaskets and seals that offers high tensile strength and high tear strength as well as good resistance to compression set. Seals for automotive body applications, such as, windows, hoods, trunks, and doors, and building applications, such as window glazing gaskets and weather strips, should be dimensionally stable, provide low compression set, and offer outstanding sealing characteristics over a broad temperature range. They must be capable of sealing out noise, wind and water, while providing long-term ultraviolet light resistance.

Abstract: A fluorine-containing graft copolymer is made from a backbone of an olefin polymer material to which is graft polymerized (a) at least one gaseous fluorinated monomer such as vinylidene fluoride, (b) at least one fluorinated acrylic acid or ester, (c) a mixture of (a) and (b), or (d) a mixture of (a) and/or (b) and a non-fluorinated monomer such as methyl methacrylate. An organic peroxide or a polymeric peroxide is used as the initiator for the graft polymerization process. The graft copolymers have improved surface properties and oxygen barrier properties, and improved thermal stability.

Abstract: A thermoplastic elastomer composition powder comprising a thermoplastic elastomer composition represented by the following (A), having a sphere-reduced average diameter of not more than 1.2 mm and a bulk specific gravity of not less than 0.38: (A) a thermoplastic elastomer composition comprising (a) 100 parts by weight of a polyolefin resin; (b) 20 to 250 parts by weight of a conjugated diene polymer of hydrogenated conjugated diene copolymer having a hydrogenation degree of not less than 70%, which is prepared by hydrogenating a conjugated diene-vinyl aromatic compound random copolymer in which the content of a vinyl aromatic compound unit is not more than 25% by weight; and (c) 0 to 500 parts by weight of an ethylene/&agr;-olefin copolymer rubber. This powder can give a molded article having excellent appearance and flexibility, which does not cause whitening easily on bending, according to the powder molding method.

Abstract: The present invention relates to a coextrusion binder comprising:

Abstract: The invention provides a novel chlorine-free modified polyolefin resin composition with excellent adherence to nonpolar substrates, with excellent solubility into solvent and compatibility with other resins, and with no tack after painting and drying.

Abstract: Thermoplastic elastomers of good dyeability and high strength and elasticity, the incorporated elastomeric particles of which have and average particle diameter of 0.05 to 5 &mgr;m. The thermoplastic elastomers are formed according to a method in which mixtures of propylene homopolymers and/or propylene copolymers, elastomeric C4 C12 olefin copolymers and/or terpolymers and C8 to C14 diacrylates, C7 to C16 diallyl compounds, C9 to C15 dimethacrylates, C7 to C10 divinyl compounds, C12 to C17 acrylate esters of polyalcohols, C15 to C21 methacrylate esters of polyalcohols and/or C9 C12 triallyl compounds are added to a melt. The thermoplastic elastomers, as well as mixtures of the thermoplastic elastomers with conventional polyolefins, are suitable for use in the vehicle industry, in the domestic appliances industry, in the construction industry and in medical technology.

Abstract: The present invention is directed to improved polybutadiene compositions suitable for use in molded golf ball core construction. The improved polybutadiene compositions are composed of polypropylene powder resins which have the effect of increasing the hardness of the resulting molded cores without increasing the weight upon curing, thereby allowing for a reduction in the amount of crosslinking agents utilized and increasing the amount of fillers incorporated therein. The addition of the polypropylene powder resins to the core compositions lowers the cost of the molded core, while maintaining the proper weight and compression. The present invention is also directed to golf balls produced utilizing the improved core compositions.

Abstract: A compatibilized blend of general purpose rubbers (GPR) and polymers containing benzylic halide groups are produced through solventless reactions utilizing a multifunctional agent containing a diene reactive group and a benzylic halo reactive group.

Abstract: The invention relates to reactive polysols with a reactive monomer portion which is polymerized during thermal coating. The polysols exhibit good mechanical properties. A monofunctional (meth)acrylate monomer of formula (1) is used as reactive monomer component.

Abstract: A bulk polymerized grafted and crosslinkable thermoplastic polyolefin powder composition having elasticity and flexibility properties, which is in the form of a powder intended for the production of flexible coatings by free flow over a hot mold, characterized in that it contains:

Abstract: A raw material composition for an extrusion moldable polyolefin resin composition including (a) a polypropylene resin, (b) a polyethylene resin, (c) an esterified cellulose material obtained by esterifying a cellulose material with a polybasic acid anhydride and having a content of the polybasic acid anhydride bonded thereto of 0.5-20% based on the weight of the cellulose material, and (d) an organic peroxide compound, wherein the weight ratio of (a) to (b) ranges from 30:70 to 80:20, wherein the weight ratio of a total of (a)+(b) to (c) ranges from 30:70 to 70:30, and wherein (d) is present in an amount of 0.001 to 0.1% based on a total weight of (a)+(b)+(c). By kneading the raw material composition at 150-200° C. for 0.5 to 30 minutes, a polyolefin composition for extrusion molding is obtained.

Abstract: There is a need for halogen-free polymeric compositions that offer high tensile strength and high tear strength as well as increased heat and ultraviolet light resistance. For instance, it is particularly critical for polymers that are utilized in making skin compounds for automotive instrument and door panels to offer high modulus as well as to display excellent heat and ultraviolet light resistance.

Abstract: A tire having improved tear strength including at least one component comprising a vulcanized elastomer from about 5 to about 50 parts by weight polypropylene per one hundred parts by weight elastomer, and from about 0.05 to about 2.0 parts by weight of an anhydride compatibilizing agent per one hundred parts by weight elastomer.

Abstract: A derivatized blend and a process for producing that blend in which a high ethylene content ethylene-propylene polymer and a lower ethylene content ethylene-propylene polymer are subjected to simultaneous blending and shearing to reduce their molecular weights and molecular weight distribution and then reacted with an organic compound to derivatize the blend. The sheared derivatized blend of polymers can function as a shear stable multifunctional viscosity index improver with improved low temperature properties and, in some cases, dispersancy antioxidant and anti-wear properties.

Abstract: Gel-type copolymer beads are described which are useful as ion exchange resins such as those used in the treatment of power plant condensate water. The subject copolymer beads possess an interpenetrating polymer network of at least two polymer components including: (i) a first polymer component derived from a first monomer mixture comprising a first monovinylidene monomer having a styrenic content less than about 50 molar percent and (ii) a second polymer component derived from a second monomer mixture comprising: a second monovinylidene monomer having a styrenic content greater than about 50 molar percent and a second crosslinking agent. The ratio of the molar percent crosslinking agent of the first polymer component to the second polymer component is less than about 0.7. Methods for making the subject beads and methods for their use as ion exchange resins for treating aqueous solutions are also provided.

Abstract: In a process for preparing thermoplastic molding compositions by

Abstract: A polymer composition comprising a blend of (a) a grafted olefin rubber, (b) an ungrafted olefin rubber, (c) a copolymeric matrix and an optional (d) a grafted acrylate rubber is disclosed. The composition which is characterized in having a desirable balance of impact strength and low gloss is useful for molding and extrusion of articles for certain outdoor applications.

Abstract: The present invention is directed to improved polybutadiene compositions suitable for use in molded golf ball core construction. The improved polybutadiene compositions are composed of polypropylene powder resins which have the effect of increasing the hardness of the resulting molded cores without increasing the weight upon curing, thereby allowing for a reduction in the amount of crosslinking agents utilized and increasing the amount of fillers incorporated therein. The addition of the polypropylene powder resins to the core compositions lowers the cost of the molded core, while maintaining the proper weight and compression. The present invention is also directed to golf balls produced utilizing the improved core compositions. Furthermore, the invention is directed to a method for reducing the amount of crosslinking agents utilized to formulate a core composition through the incorporation of polypropylene powder resins.

Abstract: A methacrylic resin composition having excellent transparency, appearance, weatherability, gloss, impact resistance and processability, which comprises a methacrylic resin and a graft copolymer having a multilayer structure prepared by polymerizing a monomer component comprising an alkyl methacrylate such as methyl methacrylate as a main component in the presence of a chain transfer agent to form an innermost layer of a crosslinked methacrylic polymer, polymerizing a monomer component comprising an alkyl acrylate such as butyl acrylate as a main component in the presence of the innermost layer polymer to form an intermediate layer and subsequently polymerizing a monomer component comprising an alkyl methacrylate such as methyl methacrylate as a main component to form an outermost layer on the intermediate layer.

Abstract: This invention relates to polyolefin polymer dispersions having a semicrystalline plastic (SP) component and an amorphous elastomer (AE) component. The polymer dispersions of this invention are characterized by a continuous phase containing a discontinuous phase (dispersed phase) as seen by FIG. 2. Embodiments of this invention include either: 1) a discontinuous phase composed of the SP component dispersed within a continuous phase composed of the amorphous elastomer component and/or, 2) a discontinuous phase composed of the amorphous elastomer dispersed within a continuous phase composed of the SP component.

Abstract: A golf ball includes a solid core which includes a blend of polybutadiene and polyurethane rubber. The rubber component of the core consists of 70 to 95% by weight of a high cis content polybutadiene rubber and 5 to 30% by weight of polyurethane rubber. The core also includes an acrylate of a zinc salt and an organic peroxide initiator.

Abstract: A rubber composition for solid golf balls comprising: (a) 50 to 100 parts by weight of a polybutadiene rubber with a 1,4-cis bond content of 80% or more, a 1,2-vinyl bond content of 2.0% or less, and a ratio (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of 3.5 or less, (b) 0 to 50 parts by weight of a diene-type rubber other than the component(a), provided that the total amount of the component (a) and component (b) is 100 parts by weight, (c) 10 to 50 parts by weight of a cross-linking monomer, (d) 20 to 80 part by weight of inorganic filler, and (e) an effective amount of an organic peroxide. The solid golf balls prepared from the rubber composition provide a good shot feeling, run a long distance, and exhibit superior durability.

Abstract: A method of making polymeric particulates wherein polymeric scrap material, virgin polymeric material and mixtures thereof are supplied to intermeshing extruder screws which are rotated to transport the polymeric material along their length and subject the polymeric material to solid state shear pulverization and in-situ polymer compatibilization, if two or more incompatible polymers are present. Uniform pulverized particulates are produced without addition of a compatibilizing agent. The pulverized particulates are directly melt processable (as powder feedstock) and surprisingly yield a substantially homogeneous light color product.

Abstract: The present invention relates to a high temperature resistant coating composition and a method of using thereof. More particularly, the invention relates to a coating composition comprising a resin containing functional hydroxyl groups (A), a polyfunctional epoxy resin (B), and an anhydride compound.(C).

Abstract: A dual core golf ball and methods for preparing portions thereof including a core having at least one core layer, a mantle having at least one layer including an amount of reinforcing polymer component and a resilient polymer component disposed concentrically adjacent the core, and a cover layer disposed concentrically adjacent the mantle, wherein the at least one mantle layer is sufficiently rigid to inhibit the resilient polymer component from substantially altering shape prior to crosslinking. The invention also includes an elastomeric composition for the mantle that includes a resilient polymer component having a predominantly 1,4-cis content, a free-radical initiator, and a reinforcing polymer component having a sufficiently low viscosity at a mixing temperature to permit substantially uniform dispersion of the polymer component with the resilient polymer component and having a crystalline melting point sufficiently low to permit mixing while avoiding substantial crosslinking.

Abstract: Provided is a method for producing an amphoteric resin which comprises reacting (1) a copolymerizable basic prepolymer A2 which is obtained by reacting a prepolymer A1 being obtained by polymerization of an amino group-containing &agr;, &bgr;-ethylenically polymerizable compound, other &agr;, &bgr;-ethylenically polymerizable compound and a polymerization initiator containing a carboxyl group at an end, with a compound having an epoxy group represented by the following formula (I): (wherein R1 represents H or a methyl group, and R represents a straight or branched chain alkyl group of 1-10 carbon atoms) in an amount of 0.1-1.0 equivalent for the amino group equivalent of the prepolymer A1 and (2) an &agr;, &bgr;-ethylenically polymerizable acidic prepolymer B2 which is obtained by carrying out the reaction in the same manner as above with (3) other &agr;, &bgr;-ethylenically polymerizable compound C.

Abstract: A multi-layer golf ball and methods for preparing a portion thereof including a core having at least one core layer, a mantle having at least one layer including an amount of reinforcing polymer component and a resilient polymer component disposed concentrically adjacent the core, and at least one cover layer disposed concentrically adjacent the mantle, wherein the layer of the mantle is sufficiently rigid to inhibit the resilient polymer component from substantially altering shape prior to crosslinking. The invention also includes an elastomeric composition including a polybutadiene having a high molecular weight average and a predominantly 1,4-cis content, a free-radical initiator, and a reinforcing polymer component having a sufficiently low viscosity at a mixing temperature to permit substantially uniform dispersion of the polymer component with the polybutadiene and having a crystalline melting point sufficiently low to permit mixing while avoiding substantial crosslinking.

Abstract: The invention relates to a highly tear propagation-resistant rubber compound, particularly for sealing and expansion bellows, containing an elastomer, fillers and other auxiliaries. In order to achieve high tear-propagation resistance with high imperviousness, dynamic stress resistance and chemical resistance, a rubber compound is proposed which contains polychloroprene as the elastomer and amorphous silica as the filler, and which is obtained by silanising in the presence of the acid acceptor and the silica, prior to adding other additives.

Abstract: Ethylene vinyl acetate (EVA)/ethylene-styrene interpolymer (ESI) blends are described that are useful in preparing foams which exhibit improved compression set resistance, dimensional stability and rebound resilience at similar foam densities than known foam systems, e.g. EVA. The cross-linked foams of this invention are particularly useful in fabricating footwear and gasket products.

Abstract: A process for making the grafted polyolefin includes the steps of adding a predetermined amount of polyolefin, a predetermined amount of 2-hydroxyethyl methacrylate and a free radical initiator to a reaction vessel. Preferably, the reaction vessel is an extruder. The constituents are then mixed under melt grafting conditions so that at least 5 weight percent of the 2-hydroxyethyl methacrylate is grafted onto the polyolefin to form a copolymer. The grafted polyolefin is then solidified.

Abstract: This invention concerns a composition comprising a blend of polyolefin with the reaction of a functionalized polyolefin and polyetheramine in which the polyetheramine is grafted into the functionalized polyolefin in a customary mixing apparatus. A process for producing the reaction product of functionalized polypropylene and polyetheramine by melting with polypropylene in a customary mixing apparatus is also disclosed. Blends of the present invention are advantageously useful to prepare paintable automotive body parts. This invention further includes dyeable polyolefin compositions containing the reaction product of functionalized polyolefin and polyetheramine. Dyeable polyolefin fibers, including polypropylene fibers, are disclosed, which may be made by melt spinning, and which may be employed to make woven and non-woven fabric. The polyolefin employed in the practice of this invention may be a flexible polyolefin.

Abstract: A thermoplastic resin composition including at least (1) a heat-treated composition obtained by heat-treating dynamically a specific polypropylene and an olefin copolymer rubber in the presence of an organic peroxide and a crosslinking agent and (2) a specified polypropylene. In addition, an inorganic filler can be added to the thermoplastic resin composition. These compositions are superior in mechanical properties such as flexural modulus, thermal rigidity resistance and impact resistance, and can be suitably used as materials for home electric parts and the like.

Abstract: The invention relates to a coextrusion binder obtained by grafting a mixture of a copolymer of ethylene and of an elastomer of EPR type with an unsaturated carboxylic acid anhydride or its derivatives. The grafted mixture is optionally diluted in another copolymer of ethylene. The binder is useful in preparing polyolefin/binder/polyamide or EVOH structures. These structures are useful in preparing rigid hollow bodies.

Abstract: (i) A starting rubber (A) comprising a terminal-modified and/or coupled diene rubber and having an average glass transition temperature TgA (.degree. C.) is mixed with a specific amount of the reinforcing agent are mixed at a temperature of at least 135.degree. C., followed by adding a starting rubber (B) comprising a terminal unmodified diene rubber and having a specific average glass transition temperature TgB (.degree. C.), and the remaining reinforcing agent and a softening agent; (ii) a starting diene rubber (A') having a specific weight average molecular weight Mw(A') and average glass transition temperature TgA' (.degree. C.) is contacted with a reinforcing agent, followed by adding a starting diene rubber (B') having a specific weight average molecular weight Mw(B) and average glass transition temperature TgB' (.degree. C.