Described herein are methods of preparing composites from never-dried natural rubber. Also described are composites made from never-dried natural rubber and filler. A method of preparing a composite in an integrated manufacturing operation is further described which includes producing a never-dried natural rubber from latex recovered from natural latex sources in a latex or rubber manufacturing facility. Products made from the composites disclosed herein are also described.

Disclosed herein are methods of preparing a composite. In one aspect, the method comprises: (a) charging a mixer having one or more rotors with: (i) at least a liquid masterbatch comprising a first filler dispersed in at least one elastomer, and (ii) a wet filler comprising a second filler and a liquid; (b) in one or more mixing steps, mixing the at least the liquid masterbatch and the wet filler to form a mixture; and (c) discharging, from the mixer, the composite comprising the first and second fillers dispersed in the at least one elastomer at a total loading of at least 20 phr, wherein the composite has a liquid content of no more than 10% by weight based on total weight of said composite.

The invention provides a novel hydrophilic polymer and latex polymer blend coating formulation and compositions thereof, and their use on various devices (e.g., prophylactic and medical devices) to form hydrophilic and flexible coatings with durable lubricity.

A first tire member manufacturing method includes an operation in which master batch is made, and an operation in which the master batch and high-cis polybutadiene rubber are mixed. The operation in which the master batch is made includes an operation in which carbon-black-containing pre-coagulation rubber latex is coagulated to obtain a coagulum, an operation in which a compound according to Formula (I) is added to the water-containing coagulum, and an operation in which the compound according to Formula (I) 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, M.sup.+ indicates sodium ion, potassium ion, or lithium ion.

Pore-free rubber articles are prepared by dip-molding in a dipping medium that includes a vulcanizing agent, then partially-cured by immersing the dip former in a heated liquid bath that is chemically inert. A particularly effective liquid bath is a molten, nitrite free inorganic salt. The partially-cured rubber is then maintained at a desired curing temperature in a low/no oxygen heating oven to complete curing. Alternatively, upon removal from the molten salt bath, the latex film is quenched.

A masterbatch manufacturing method in accordance with the present disclosure comprises a first operation in which a pre-coagulation rubber latex comprising carbon black is heated as it is agitated with an agitator provided with agitator vane(s); and a second operation in which coagulant is added to the pre-coagulation rubber latex; wherein the first operation satisfies Formula I and Formula II. The Formula I is bi5.6/100. The Formula II is bt.sub.m/e.sub.h100>10. b indicates agitator vane circumferential speed (m/s). i indicates iodine absorption (g/kg) of carbon black. t.sub.m indicates agitation time (s). e.sub.h is given by Formula III. The Formula III is e.sub.h=(t.sub.e+t.sub.s)t.sub.m/2. t.sub.e indicates the temperature ( C.) of the pre-coagulation rubber latex at the end of the first operation. t.sub.s indicates the temperature ( C.) of the pre-coagulation rubber latex at the start of the first operation.

Disclosed is a method for producing a surface-treated carbon black, including a step (step (i)) of mixing a carbon-black-containing aqueous-slurry-solution in which a carbon black is dispersed in water with a dihydrazide compound, and subsequently removing the water. Disclosed is a method for producing a rubber wet masterbatch, including: a step (I) of mixing a carbon-black-containing aqueous-slurry-solution in which a carbon black is dispersed in water, a rubber latex solution, and a dihydrazide compound with each other to produce a carbon-black-containing aqueous-rubber-latex-solution; a step (II) of solidifying the resultant carbon-black-containing aqueous-rubber-latex-solution to produce a carbon-black-containing rubber solidified product; and a step (III) of dehydrating and drying the resultant carbon-black-containing rubber solidified product to produce the rubber wet masterbatch. These producing methods can give a vulcanized rubber low in exothermicity, and a rubber composition restrained from being lowered in scorch property (or having scorch resistance).

The invention provides a novel hydrophilic polymer and latex polymer blend coating formulation and compositions thereof, and their use on various devices (e.g., prophylactic and medical devices) to form hydrophilic and flexible coatings with durable lubricity.

A method for producing a rubber wet masterbatch is disclosed including mixing a carbon-black-containing aqueous-slurry-solution in which a carbon black is dispersed in water with a rubber latex solution to produce a carbon-black-containing aqueous-rubber-latex-solution, solidifying the resultant carbon-black-containing aqueous-rubber-latex-solution to produce a carbon-black-containing rubber solidified product, and dehydrating and drying the resultant carbon-black-containing rubber solidified product to produce a rubber wet masterbatch. In this method, about the carbon-black-containing aqueous-slurry-solution, in carbon black particles in the slurry-solution, the proportion of carbon black particles having a particle diameter of 60 m or more is 35% or less by volume. The particle diameter is based on a measurement of the carbon black particles in the slurry-solution with an image-analytic particle size distribution meter. The method for producing a rubber wet masterbatch can give a vulcanized rubber having excellent abrasion resistance while the rubber has a low exothermicity.

A process for producing a wet rubber masterbatch comprises a step (I) of dispersing a filler into a dispersing solvent to produce a filler-containing slurry solution, and a step (II) of adding a rubber latex solution to the filler-containing slurry solution to yield a filler-containing rubber latex solution, and stirring the yielded filler-containing rubber latex solution while heating the filler-containing rubber latex solution, thereby solidifying the filler-containing rubber latex solution, and a step (III) of stirring the resultant while adding an acid thereto, thereby solidifying the filler-containing rubber latex solution. In the step (II), the circumferential speed of a stirring impeller which a mixing tank used at the time of the stirring has is less than 10 m/s, and a calorie of 25 to 250 J both inclusive per unit period and unit mass is given to the filler-containing rubber latex solution by the heating.