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
2002-12-11
2004-08-24
Peng, Kuo-Liang (Department: 1712)
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...
C528S284000, C525S342000, C525S343000, C524S492000, C152S209100
Reexamination Certificate
active
06780925
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the preparation of a silica reinforced rubber composition where alkoxysilane and/or sulfur cure reactions within the elastomer host are controlled by the use of a selected amino acid, or amino acid-containing protein based, activator. The invention also relates to such composite and to a tire having at least one component of such composite.
Such amino acid-containing proteins are defined as proteins which contain one or more of such selected amino acids to enhance the formation of the alkoxysilane condensation reaction product within an elastomer host, to enhance the silane/elastomer interactions as well as to provide some unique synergism with the sulfur cure system for the elastomer composition Such amino acid-containing proteins are referred to herein as “derived protein(s)” as being the condensation product of amino acids of which at least one of such amino acids is a selected amino acid as defined and required by this invention.
The invention also relates to such composite and to a tire having at least one component comprised of such composite
BACKGROUND OF THE INVENTION
Elastomer compositions typically contain particulate filler reinforcement such as, for example, carbon black and/or silica.
Silica reinforcement for an elastomer composition may be provided by adding particulate silica such as, for example, precipitated silica, to a rubber composition.
In practice, particularly where a particulate silica-based filler is added to an elastomer composition as an elastomer reinforcement such as, for example, an aluminosilicate or silica-modified carbon black, a coupling agent is often used to aid in coupling the filler to one or more diene-based elastomers. The use of various coupling agents for such purpose is well known to those having skill in such art.
Such coupling agents may be, for example, an alkoxyorganosilane polysulfide which has a constituent component, or moiety, (the alkoxysilane portion) capable of reacting with, for example, silanol groups, on the silica surface of the silica-containing filler and, also, a constituent component, or moiety, (the polysulfide portion) usually capable of interacting with the rubber, particularly a diene-based, sulfur vulcanizable rubber which contains carbon-to-carbon double bonds, or unsaturation. In this manner, then, the coupler may act as a connecting bridge between the silica-containing filler and the rubber and, thereby, enhance its reinforcing effect for the rubber composition.
In particular, it is envisioned that the silane moiety of the coupler, particularly a trialkoxysilane moiety, is available for reacting with virtually any reactive hydroxyl groups it may encounter and particularly with silanol groups (—Si—OH) on the surface of the silica-based filler and also with alkoxy groups on the coupler itself to form siloxane units (—Si—O—Si—).
In practice, alkoxyorganosilane polysulfides sometimes used are bis-(3-trialkoxysilylalkyl)polysulfides which contain from about 2 to 8, with an average of from about 3.5 to 4.5, sulfur atoms in its polysulfidic bridge.
During a typical mixing (processing) of the elastomer composition in an internal rubber mixer under high shear conditions to temperatures in a range of 150° C. to 175° C., the silane portion reacts with the surface of a silica-based filler (e.g.: which may be hydroxyl groups on the surface of the silica which may be in a form of silanol groups).
A portion of the polysulfidic bridge of such organosilane polysulfide typically breaks during such mixing operation, resulting in an exposed sulfur on the coupling agent which is available to apparently interact with one or more of the elastomer(s) in the elastomer composition.
However, it is to be appreciated that such interaction of the sulfur with the elastomer(s) is typically accompanied by an increase in the viscosity (e g. Mooney viscosity) of the rubber composition itself as the sulfur interacts with the elastomer(s). Too high of an elastomer viscosity under such conditions makes the rubber composition more difficult to process, or mix, in a typical internal rubber mixer.
Therefore, a degree of adjustment of various formulation ingredients (formulation tuning) and enhancement of various physical properties is limited because of such typical higher viscosity related processing limitations imposed via use of such coupling agent.
Uniquely, however, organosilane polysulfide compounds in a form of organosilane disulfide compounds with predominately contained only about two sulfur atoms in the polysulfidic bridge (e.g. and an average of about 2 to about 2.6 sulfur atoms) do not ordinarily cause such excessive viscosity build-up of the rubber composition during its internal mixing operation.
Such phenomenon in the use of the organosilane disulfide compounds is apparently due to stronger sulfur-to-sulfur bonds for the polysulfidic bridge of the disulfide and their inherent resistance to breaking upon high shear mixing at the aforesaid elevated temperatures, thus, enabling only a very limited amount of sulfur atoms available to interact with diene-based elastomer(s) in the rubber composition during the mixing operation. This phenomenon is well known to those having skill in such art.
Accordingly, it is desired to more effectively utilize the aforesaid rubber processing advantages afforded via use of such organosilane disulfide compound, including a bis-(trialkoxyorganosilane)disulfide, compound as a coupling agent.
It is a purpose of this invention to enhance the formation of the alkoxysilane condensation reaction product within an elastomer host, to enhance the silane/elastomer interactions as well as to provide some unique synergism with the sulfur cure system for the elastomer composition
While it is known from said EP Publication No. 1 061 097 that silica reinforcement may be improved by a condensation reaction of an alkoxysilane, particularly an alkoxysilane polysulfide promoted or retarded by the presence of acidic or base materials, the use of a specific type of amino acid, or proteins containing such amino acid, as described herein and required for this invention is believed to be novel and inventive.
The term “phr” as used herein, and according to conventional practice, refers to “parts of a respective material per 100 parts by weight of rubber, or elastomer”.
In the description of this invention, the terms “rubber” and “elastomer” if used herein, may be used interchangeably, unless otherwise prescribed. The terms such as “rubber composition”, “compounded rubber” and “rubber compound”, if used herein, are used interchangeably to refer to “rubber which has been blended or mixed with various ingredients and materials” and “rubber compounding” or “compounding” may be used to refer to “the mixing of such materials”. Such terms are well known to those having skill in the rubber mixing or rubber compounding art.
The term “derived protein(s)” as used herein is intended to mean amino acid-containing protein(s) which contains one or more amino acids specified herein available to interact with organosilanes and/or sulfur cure systems as discussed herein unless otherwise indicated.
SUMMARY AND PRACTICE OF THE INVENTION
In accordance with this invention, a process of preparing a composite of an elastomer composition which contains a silica-based reinforcement therein comprises the sequential steps of:
(A) thermomechanically mixing in at least one preparatory mixing step to a temperature of about 140° C. to about 190° C., alternatively to a temperature of about 150° C. to about 185° C.,
(1) 100 parts by weight of at least one sulfur vulcanizable elastomer selected from homopolymers and copolymers of conjugated diene hydrocarbons copolymers of at least one conjugated diene hydrocarbon and vinyl aromatic compound,
(2) about 15 to about 100, alternatively about 30 to about 90, phr of particulate filler comprised of at least one silica-based filler which contains reactive hydroxyl groups on the surface thereof (e.g.: silanol groups),
(3) about 0.05 to about 20 parts by weight per part by wei
Edme Materne Thierry Florent
Kayser Francois
Mallamaci Michael Paul
Wilk Harlan Roy
The Goodyear Tire & Rubber Company
Young, Jr. Henry C.
LandOfFree
Rubber composition with silica reinforcement obtained with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rubber composition with silica reinforcement obtained with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rubber composition with silica reinforcement obtained with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3318987