Abstract: The present invention provides a natural rubber masterbatch effective in achieving a tread rubber composition which is suitable for heavy-duty tires for rough roads and which is effective in greatly enhancing the abrasion resistance of the tires without impairing the low heat build-up of the tires, a method of producing the natural rubber masterbatch, a rubber composition prepared using the natural rubber masterbatch, and a tire. In a mixing step of mixing a natural rubber latex with a slurry containing water and a carbon black dispersed therein, 10 to 100 weight parts of the carbon black is mixed with 100 weight parts of a natural rubber component in the natural rubber latex. The carbon black satisfies the following conditions: (1) N2SA is 120 to 180 m2/g; (2) the relationship between 24M4DBP and N2SA is represented by the inequality 15?24M4DBP?0.

Abstract: A natural rubber wet masterbatch rubber composition comprising a mixture of a natural rubber latex with a slurry solution containing a carbon black dispersed therein, which satisfies the followings: (1) a CATB specific surface area (m2/g) in the range of 60<CTAB<110, (2) a 24M4DBP (m3/100 g) in the range of 55<24M4DBP<75, (3) a CATB specific surface area and a tint strength (TINT) having the relationship of TINT>0.41×CTAB+81, and (4) a compounding amount of 10 to 100 parts by mass relative to 100 parts by mass of natural rubber. The natural rubber wet masterbatch rubber composition can be suitably used for improving the resistance to fracture and to crack propagation of a tire, a steel coating rubber for a rubber product for industrial use, and the like.

Abstract: A surface machining method to be adopted when machining a valve mechanism component member is provided so as to manufacture a product assuring a specific pulsation-reducing effect over an extended period of time with a high level of reliability. A plurality of recesses 60 are formed through laser machining over an area (seat surface 51) at a valve plate 2 around an suction port 24, which comes into contact with an suction valve 30, or an area of the suction valve 30 that comes into contact with the valve plate 2. Projections 61 may also be formed through laser machining around the recesses 60. Such projections 61 should be formed so as to assure hardness greater than the hardness of the other areas through radiation of laser light.

Abstract: A natural rubber wet masterbatch rubber composition comprising a mixture of a natural rubber latex with a slurry solution containing a carbon black dispersed therein, which satisfies the followings: (1) a CATB specific surface area (m2/g) in the range of 60<CTAB<110, (2) a 24M4DBP (m3/100 g) in the range of 55<24M4DBP<75, (3) a CATB specific surface area and a tint strength (TINT) having the relationship of TINT>0.41×CTAB+81, and (4) a compounding amount of 10 to 100 parts by mass relative to 100 parts by mass of natural rubber. The natural rubber wet masterbatch rubber composition can be suitably used for improving the resistance to fracture and to crack propagation of a tire, a steel coating rubber for a rubber product for industrial use, and the like.

Abstract: A method for producing a rubber-filler master batch which comprises mixing a rubber solution obtained by dissolving a diene-based rubber in an organic solvent into a slurry obtained by dispersing in water, in advance, carbon black, silica and/or at least one inorganic filler represented by the following general formula (I): nM1.xSiOy.zH2O??(I) [wherein M1 represents at least one selected from the group consisting of metals which are aluminum, magnesium, titanium, calcium and zirconium, oxides and hydroxides of the metals, hydrates thereof and carbonates of the metals, and n, x, y and z respectively represent an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5 and an integer of 0 to 10.

Abstract: The present invention provides a natural rubber masterbatch effective in achieving a tread rubber composition which is suitable for heavy-duty tires for rough roads and which is effective in greatly enhancing the abrasion resistance of the tires without impairing the low heat build-up of the tires, a method of producing the natural rubber masterbatch, a rubber composition prepared using the natural rubber masterbatch, and a tire. In a mixing step of mixing a natural rubber latex with a slurry containing water and a carbon black dispersed therein, 10 to 100 weight parts of the carbon black is mixed with 100 weight parts of a natural rubber component in the natural rubber latex. The carbon black satisfies the following conditions: (1) N2SA is 120 to 180 m2/g; (2) the relationship between 24M4DBP and N2SA is represented by the inequality 15?24M4DBP?0.

Abstract: This invention relates to a method for producing a rubber master batch capable of producing a rubber master batch having an excellent homogeneity without a special equipment, and more particularly to a method for producing a rubber master batch comprising a step of mixing a rubber solution with a slurry solution of a filler previously dispersed into a liquid, characterized in that a static mixer or a high shear mixer comprising a rotor and a stator portion is used in the mixing of the rubber solution and the slurry solution.

Abstract: The natural rubber master batch of the present invention is prepared by mixing a natural rubber latex having its amide linkages cleaved and an aqueous slurry having a filler dispersed in water. Alternatively, the natural rubber master batch is prepared by a method including a step for mixing a natural rubber latex and an aqueous slurry containing dispersed fillers having a specific particle size distribution and a limited range of 24M4DBP absorption. The natural rubber composition of the present invention is prepared by compounding natural rubber, which contains non-rubber components prepared by cleaving amide linkages of natural rubber latex, with silica and/or a particular inorganic filler.

Abstract: A rubber composition is produced by mixing a curing agent with a curable rubber composition having a particular composition in a continuous mixing machine.

Abstract: Provided is a natural rubber obtained by drying a gathered natural rubber latex without coagulating, wherein a drum dryer and/or a conveyor type dryer are used for drying.

Abstract: A rubber composition comprises a polar group-containing diene polymer synthesized through an emulsion polymerization as a rubber component, and an inorganic filler represented by a formula of mM.xSiOy.zH2O wherein M is a metal selected from the group consisting of aluminum, magnesium, titanium and calcium, an oxide or a hydroxide of such a metal or an hydrate thereof, m is an integer of 1 to 5, x is an integer of 0 to 10, y is an integer of 2 to 5 and z is an integer of 0 to 10.

Abstract: The invention provides a diene-based rubber-inorganic compound composite material comprising a diene-based rubber and at least one inorganic compound selected from silica and a compound represented by the following formula (I):

Abstract: The natural rubber master batch of the present invention is prepared by mixing a natural rubber latex having its amide linkages cleaved and an aqueous slurry having a filler dispersed in water. Alternatively, the natural rubber master batch is prepared by a method including a step for mixing a natural rubber latex and an aqueous slurry containing dispersed fillers having a specific particle size distribution and a limited range of 24M4DBP absorption. The natural rubber composition of the present invention is prepared by compounding natural rubber, which contains non-rubber components prepared by cleaving amide linkages of natural rubber latex, with silica and/or a particular inorganic filler.

Abstract: A rubber composition comprises a polar group-containing diene polymer synthesized through an emulsion polymerization as a rubber component, and an inorganic filler represented by a formula of mM.xSiOy.zH2O wherein M is a metal selected from the group consisting of aluminum, magnesium, titanium and calcium, an oxide or a hydroxide of such a metal or an hydrate thereof, m is an integer of 1 to 5, x is an integer of 0 to 10, y is an integer of 2 to 5 and z is an integer of 0 to 10.

Abstract: A rubber composition comprising (A) at least one natural or synthetic diene rubber, (B) an inorganic filler comprising at least one of silica and silicates as the main component and (C) an addition salt of an amine represented by general formula (I): wherein R1 represents a C8 to C24 alkyl group, an aryl group or an aralkyl group, R2 and R3 represent a hydrogen atom, a C1 to C12 alkyl group, an aryl group, an aralkyl group or a hydroxyalkyl group and R4 represents a C6 to C24 alkyl or alkenyl group, an aryl group or an aralkyl group; and a pneumatic tire produced by using the rubber composition.

Abstract: The present invention provides a rubber composition and a pneumatic tire using the rubber composition. A rubber composition which comprises: a blend rubber of a copolymer and other diene base rubbers, the copolymer being obtained by copolymerization of 1,3-butadiene and an aromatic vinylmonomer using an organic lithium compound as an initiator, the glass transition point of the copolymer being −50° C. or more, and the blend rubber comprising the copolymer in an amount of 20 parts by weight or more and the other diene base rubbers in an amount of 80 parts by weight or less per 100 parts by weight of the blend rubber; silica filler in an amount of 10 to 80 parts by weight per 100 parts by weight of the blend rubber; carbon black in an amount of 20 to 80 parts by weight per 100 parts by weight of the blend rubber; and a specific silane coupling agent, i.e.

Abstract: The rubber composition of the present invention comprises a rubber component which is a blend rubber of a copolymer rubber and other diene based rubbers or the copolymer rubber alone, the copolymer rubber having a glass transition temperature of −60° C.

Abstract: A rubber composition prepared by blending 15 to 85 parts by weight of silica per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber and 1 to 15% by weight of a dispersion-improving agent based on the amount of the silica described above. Further, a rubber composition prepared by blending 20 to 60 parts by weight of silica and 30 to 80 parts by weight of carbon black having a cetyl trimethylammonium bromide-adsorbing amount (CTAB) of 120 m2/g or more and a dibutyl phthalate-absorbing amount (DBP) of 120 ml/100 g or more per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber, and 3 to 15% by weight of a dispersion-improving agent based on the amount of the silica described above, wherein the total amount of silica and carbon black is 50 to 120 parts by weight. A specific nitrogen-containing carbonyl compound or silicone oil is used as a dispersion-improving agent.

Abstract: The present invention provides a rubber composition and a pneumatic tire using the rubber composition. A rubber composition comprises silica in an amount of 10 to 85 parts by weight per 100 parts by weight of natural rubber and/or diene synthetic rubbers. A polysulfide silane coupling agent having a specific distribution of sulfur reacts with a trivalent phosphorus compound such that a content of high polysulfide in the polysulfide silane coupling agent is reduced. The rubber composition further comprises 1 to 20% by weight, based on an amount of the silica, of the polysulfide silane coupling agent having a specific distribution of sulfur such that a content of high polysulfide component is small. The pneumatic tire has an excellent low heat buildup property.

Abstract: The present invention provides a rubber composition and a pneumatic tire using the rubber composition. The rubber composition which comprises: a rubber component comprising a styrene-butadiene copolymer rubber or a blend of the styrene-butadiene copolymer rubber and another conjugated diene base rubber with the styrene-butadiene copolymer rubber being 70% by weight or more of the entire blend, and the entire content of styrene is 30 to 40% by weight of the entire rubber component; silica in an amount of 10 to 60 parts by weight per 100 parts by weight of the rubber component; a specific silane coupling agent, i.e., a bis (alkoxysilylalkyl)polysulfide having a polysulfide chain in which the distribution of sulfur is specified, in an amount of 1 to 20% by weight of the amount of silica; and carbon black, the sum of the amount of silica and carbon black being 60 to 130 parts by weight per 100 parts by weight of the rubber component.