Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-03-20
2003-04-29
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S265000, C524S287000, C524S493000, C523S200000, C523S216000, C523S205000
Reexamination Certificate
active
06555606
ABSTRACT:
FILED OF THE INVENTION
This invention relates to preparation of a rubber composition by pre-mixing at least rubber compounding ingredient with an organic solvent solution of at least one elastomer. The invention also contemplates the use of such rubber composition, or a blend of such rubber composition with additional elastomer(s) and/or rubber compounding ingredients, as a component of an article of manufacture. Such article of manufacture may be, for example, a tire. Such article may also be an industrial product such as, for example, a hose or belt such as a conveyor belt or power transmission belt.
BACKGROUND OF THE INVENTION
Various rubber compounding ingredients, including particulate carbon black reinforcement, is conventionally blended with various elastomers with the aid of various internal mixers, as well as open roll mixers, under high sheer and relative high temperature conditions. Accordingly a considerable amount stress is experienced by the rubber composition as well as expenditure of energy to accomplish the aforesaid mixing.
Alternatively, various rubber compositions have heretofore been prepared by:
(1) first masterbatching various rubber latices with various rubber compounding ingredients which have particularly included rubber reinforcing carbon black under low shear and temperatures followed by
(2) blending the masterbatch with additional elastomer(s) and compounding ingredients under high shear and temperature conditions.
For example, see U.S. Pat. Nos. 3,294,733; 3,298,984; 3,317,458; 3,345,324; 3,491,052; 3,767,605 and 3,923,707.
U.S. Pat. No. 3,317,458, for example, relates to masterbatching a combination of carbon black and silica with a rubber latex.
Various rubber compositions have also heretofore been prepared by mixing an aqueous slurry of carbon black with an organic solvent solution of elastomer(s). For example see U.S. Pat. No. 3,350,342.
U.S. Pat. No. 3,304,281, for example, relates to mixing together a solution of one polymer with a latex of another polymer and then coagulating the rubber crumb from the resulting mixture. the process can be used to incorporate an oil and/or carbon black into the polymer. For example, the oil can be introduced as an aqueous emulsion and the oil emulsion mixed with the latex prior to contact with the solution. Alternatively, all three components can be mixed simultaneously. Alternatively, a carbon black aqueous slurry can be added to the solution-latex mixture or it can be mixed with the latex prior to mixing with the solution.
U.S. Pat. No. 3,491,052 for example, relates to mixing an elastomer in an aqueous latex form with a solution of an elastomer which has been dissolved in a water immiscible organic solvent to form a pseudo-emulsion and recovering the mixed elastomers by adding a latex coagulating agent at a temperature sufficient to vaporize the solvent. Alternatively a rubber pigment (e.g.: carbon black) may be dispersed in the pseudo-emulsion prior to coagulation.
U.S. Pat. No. 3,533,988, for example, relates to blending a hydrocarbon solution of rubber with an aqueous suspension of a rubber reinforcing agent, such as carbon black. In its background discussion, it relates that, theretofore, in order to avoid a disagreeableness of handling dry, dusty carbon black with raw rubber on mixing rolls, a method was developed for producing masterbatch by dispersing carbon black directly into a rubber solution produced by monomer polymerization in the presence of a solvent. It further relates that, theretofore, another method was to disperse carbon black in a hydrocarbon and mix the dispersion with the rubber solution.
In the description of this invention, the term “phr” relates to parts by weight of an ingredient per 100 parts by weight of rubber.
The terms “rubber” and “elastomer” are used interchangeably unless otherwise specified.
The term “Tg” relates to a glass transition temperature of an elastomer, normally determined by a differential scanning (DSC) calorimeter with a temperature rise of 10° C. per minute.
DISCLOSURE AND PRACTICE OF THE INVENTION
In accordance with this invention, a process of preparing a rubber composition is provided which comprises:
(A) blending a particulate elastomer-reinforcing filler with an organic solvent solution of a conjugated diene-based elastomer solution and recovering a composition thereof by removing said solvent therefrom wherein said filler is blended therewith in a form of:
(1) particulate elastomer-reinforcing filler exclusive of aqueous or organic dispersion of said filler; and/or
(2) particulate elastomer-reinforcing filler as a dispersion thereof in an organic solvent, or
(B) spraying an organic solvent solution of a conjugated diene-based elastomer solution onto a particulate elastomer-reinforcing filler and recovering a composition thereof by removing said solvent.
In practice, various rubber compounding ingredients may be included with said filler in either of the above said blending process and/or said spraying process.
In practice, said solvent solution of said elastomer may be a polymerizate.
In further accordance with this invention, said particulate filler is comprised of at least one of carbon black, silica, particularly amorphous silica including precipitated silica and/or fumed silica, carbon black and modified carbon black having silanol groups on the surface thereof.
In additional accordance with this invention, a preferred carbon black and silica have a relatively low apparent density prior to said blending in a range of about 3 to about 300, alternatively about 3 to about 140 g/l. This low density is substantially lower than conventional carbon blacks and silicas which more conventionally have an apparent density in a range of about 500 to about 1000 g/l.
Exemplary of more conventional silicas are precipitated silicas and exemplary of conventional carbon blacks are those in which the carbon black powder has been processed to form very small pellets and which have designations such as, for example, N234, N121, N330, etc which are ASTM designations.
Exemplary of silicas and carbon blacks with the said low apparent densities are, for example, fumed silicas and fine carbon black powers prior to their pelletization to form the said N234, N122 and N330 (for example) designated carbon blacks. Such fine carbon black powders are not normally used for rubber reinforcement purposes, although carbon blacks in the aforesaid pelletized form, with attendant higher apparent densities, are conventionally used for rubber reinforcement purposes.
A significant aspect of using the silica and carbon black powder with very low apparent densities for this invention is to utilize the high absorption capacities of such fillers, particularly where it is desired for the filler to have a greater ability to absorb various ingredients onto its surface and to thereby ultimately provide a resulting free flowing rubber composition.
As previously presented, the process of this invention may involve spraying said organic solvent solution comprised of at least one diene-based elastomer onto said particulate filler.
As a feature of said spraying process, said particulate filler is preferably agitated during said spraying of said solvent solution onto said filler.
As an additional feature of said spraying process, the solvent solution of said elastomer(s) is substantially dried upon said particulate filler as it is being agitated.
In additional accordance with this invention, said suspension, or dispersion, of said filler and said solvent solution of elastomer(s) is heat treated by heating the mixture, while agitating the mixture, to a temperature within a range of about 30° C. to about 150° C., alternatively about 40° C. to about 150° C., for about 2 to about 30, alternatively about 3 to about 20, minutes prior to drying the said composite. It is to be appreciated that the mixture may need to be contained under pressure in a suitable container or under reflux conditions where evaporating solvent is returned to the solution during the heat treatment operation.
In further accordance with
Agostini Giorgio
Zimmer Rene Jean
Harlan R.
The Goodyear Tire & Rubber Company
Wu David W.
Young, Jr. Henry C.
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