A rubber composition obtained by dry-mixing a rubber wet masterbatch A containing a carbon black A having a nitrogen adsorption specific: surface area (N.sub.2SA) of NA (m.sup.2/g) with a rubber wet masterbatch B containing a carbon black B having a nitrogen adsorption specific surface area (N.sub.2SA) of NB (m.sup.2/g), wherein the content ratio of the rubber wet masterbatch A to the rubber wet masterbatch B is from 5/95 to 40/60, and when the content proportion of the carbon black A in the rubber wet masterbatch A is represented by LA, and that of the carbon black B in the rubber wet masterbatch B is represented by LB, the specific expressions are satisfied.

A problem which is addressed is the provision of a method for manufacturing a wet rubber masterbatch that will serve as raw material for vulcanized rubber which excels in fatigue resistance, ability to achieve reduced heat generation, and tensile characteristics.

A wet rubber masterbatch is manufactured by means of a method comprising an operation in which a latex that has magnesium present therein in an amount which is not greater than 150 ppm is prepared; an operation in which a liquid mixture is made; and an operation in which the liquid mixture is coagulated to obtain a coagulum. The latex comprises rubber particles for which the 90 vol % particle diameter is not greater than 2 m. The operation in which the liquid mixture is made comprises a step in which the latex and a dispersion solvent are mixed together. The operation in which the liquid mixture is made further comprises a step in which a slurry that contains filler and a latex solution obtained as a result of the step in which the latex and the dispersion solvent were mixed are mixed together. The operation in which the coagulum is obtained comprises a step in which the coagulum is separated from waste liquid. The method for manufacturing the wet rubber masterbatch satisfies Formula I, below.

a/b65 (Formula I)

(At Formula I, a indicates COD (mg/L) of waste liquid, and b indicates amount (mass %) of rubber present in the liquid mixture.)

A problem which is addressed is the provision of a method for manufacturing a wet rubber masterbatch and so forth permitting improvement in fatigue resistance without causing worsening in ability to achieve reduced heat generation. Wet rubber masterbatch and so forth are manufactured by means of a method comprising an operation in which a latex that comprises rubber particles for which 90 vol % particle diameter is not greater than 2 m and that has magnesium present therein in an amount which is not greater than 150 ppm is prepared.

Methods to make a silica elastomer composite with a destabilized dispersion of silica are described, along with silica elastomer composites made from the methods. The advantages achieved with the methods are further described.

Article comprising a polymeric substrate having a first major surface comprising a plurality of particles (e.g., clay particles, graphite particles, boron nitride particles, carbon particles, molybdenum disulfide particles, bismuth oxychloride particles, and combinations thereof) attached thereto. Articles described herein are useful, for example, for a tamper evident surface.

Acido-basic properties of a system containing a polymer obtained by decomposing by oxidative cleavage of a carbon-carbon double bond, and a trifunctional molecule having an alkoxysilyl group in the structure as represented by the formula (A) are changed such that the system is changed into a basic system when the system is acidic and the system is changed into an acidic system when the system is basic to combine the decomposed polymer and the trifunctional molecule, thereby introducing the alkoxysilyl group into the main chain. Furthermore, acido-basic properties of a system containing a polymer obtained by decomposing by oxidative cleavage of a carbon-carbon double bond to decrease the molecular weight, and a functional molecule having an alkoxysilyl group as represented by the formula (a) are changed in the same manner as above to combine the decomposed polymer and the functional molecule, thereby introducing the alkoxysilyl group in a molecular terminal. ##STR00001##

The present invention provides a method for producing a masterbatch and related products which enhance the dispersibility of fillers in rubber to improve the balance of tensile strength, rigidity, and fuel economy. Provided is a method for producing a masterbatch, including a step of mixing a rubber latex having a zeta potential of 100 to 20 mV with a filler dispersion having a zeta potential of 10 to 90 mV, and preparing a latex compound having a zeta potential of 20 to 0 mV.

The present invention provides a method for producing a masterbatch and related products which enhance the dispersibility of fillers in rubber to improve rubber physical properties such as tensile strength, rigidity, and fuel economy. Provided is a method for producing a masterbatch, including: step (1) of mixing a rubber latex having a zeta potential of 100 to 20 mV with a filler dispersion having a zeta potential of 90 to 10 mV to prepare a latex compound; and step (2) of adjusting a zeta potential of the latex compound prepared in step (1) to 30 to 0 mV.

A first tire member manufacturing method includes an operation in which a pre-coagulation rubber latex containing carbon black, for which a ratio of specific surface area as determined by nitrogen adsorption N.sub.2SA (in units of m.sup.2/g) to an amount of iodine absorption IA (in units of mg/g) is not less than 1.00, is coagulated to obtain a coagulum; an operation in which a compound according to Formula (I), below, is added to the water-containing coagulum; and an operation in which the compound according to Formula (I), below, is dispersed within the coagulum.

##STR00001##

In Formula (I), R.sup.1 and R.sup.2 each indicates a hydrogen atom, an alkyl group having 1 to 20 carbons, an alkenyl group having 1 to 20 carbons, or an alkynyl group having 1 to 20 carbons, R.sup.1 and R.sup.2 may be the same or different, and M.sup.+ indicates sodium ion, potassium ion, or lithium ion.

A method for producing a wet rubber comprises a step (I) of dispersing the filler into the dispersing solvent, and adding, at the time of the dispersing, at least one portion of the rubber latex solution to the dispersing solvent to produce a slurry solution containing the filler to which particles of the rubber latex adhere, a step (II) of mixing the slurry solution containing the filler, to which the rubber latex particles adhere, with the rest of the rubber latex solution to produce a rubber latex solution containing the filler, to which the rubber latex particles adhere, and a step (III) of solidifying and drying the rubber latex solution containing the filler. About the filler, the ratio of the nitrogen adsorption specific surface area (N.sub.2SA) thereof to the iodine adsorption amount (IA) thereof ((N.sub.2SA)/(IA)) is 1.00 or more.