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
2001-08-31
2002-11-05
Niland, Patrick D. (Department: 1714)
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...
C152S151000, C152S450000, C152S905000, C264S501000, C523S200000, C523S215000, C523S216000, C524S493000, C524S495000, C524S496000, C524S499000, C524S186000, C524S236000, C524S247000, C524S262000, C524S093000
Reexamination Certificate
active
06476115
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a conjugated diene-based rubber composition reinforced with silica-based reinforcement together with a non-silane coupling agent as N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide and/or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide for endeavoring to both couple synthetic aggregates of precipitated silica to elastomers and enhancing electrical conductivity of such rubber compositions which contain less than 25 parts by weight carbon black per 100 parts by weight elastomer.
Said coupling agent materials may be provided for mixing with said diene-based rubber(s), for example, as individual materials, as at least one of said materials being supported on a carbon black carrier or as being pre-reacted, or otherwise pre-treated, with synthetic silica aggregates. The invention includes an article of manufacture, including a tire, having at least one component comprised of such rubber composition.
BACKGROUND FOR THE INVENTION
For various applications utilizing rubber compositions, carbon black and/or synthetic amorphous silica-based materials are conventionally used as particulate reinforcing fillers for the elastomer(s) of the rubber composition(s).
Sometimes, such silica reinforced rubber compositions contain only a minimal amount of carbon black reinforcement, such as for example, 25 parts by weight or less based upon 100 parts by weight of the elastomer, and often 10 parts by weight or even less. For rubber compositions with such a small amount of carbon black contend, the rubber composition typically has a very high electrical resistivity which is sometimes undesirable.
Also, often a coupling agent is used together with the silica in order to couple, or otherwise enhance, its elastomer reinforcement effect for the elastomer(s) and such use of a coupling agent is well known to those having skill in such art.
Historically, such coupling agents may be, for example, silane-based compounds which have one moiety (a silane-based moiety such as, for example, an alkoxysilane moiety) which is reactive with hydroxyl groups (e.g. silanol groups) on the surface of a synthetic amorphous silica and having another moiety (e.g. a polysulfide bridge) which becomes interactive with a conjugated diene-based elastomer.
For example, bis-(3-trialkoxysilylpropyl)polysulfides having an average of from 2 to 4 connecting sulfur atoms in their polysulfidic bridge are often used as a coupling agent (or adhesive) to enhance coupling of synthetic amorphous silicas, such as aggregates of precipitated silica, to various conjugated diene-based elastomers. Use of such coupling agents is well known to those having skill in such art.
However, use of such silane/polysulfide coupling agents do not serve to reduce inherent high electrical resistivity of silica reinforced rubber compositions which contain only a minimal amount of carbon black, if any.
In the description of this invention, the term “phr” is used to designate parts by weight of a material per 100 parts by weight of elastomer. In the further description, the terms “rubber” and “elastomer” may be used interchangeably unless otherwise mentioned. The terms “vulcanized” and “cured” may be used interchangeably, as well as “unvulcanized” or “uncured”, unless otherwise indicated.
SUMMARY AND PRACTICE OF THE INVENTION
In accordance with one aspect of this invention, a rubber composition is provided which comprises, based upon parts by weight per 100 parts by weight rubber (phr):
(A) 100 parts by weight of at least one diene hydrocarbon based elastomer,
(B) about 25 to about 90, optionally about 35 to about 90, phr of particulate reinforcing filler comprised of about 10 to about 70, phr of synthetic amorphous silica aggregates and, correspondingly, from zero to about 25, alternately about 5 to about 20, phr of at least one of carbon black and silica treated carbon black having domains of silica on its surface, wherein said silica aggregates and said silica domains on the surface of said treated carbon black contain hydroxyl groups (e.g. silanol groups) on their surface; and
(C) about 0.5 to about 10, preferably about 1 to about 7, phr of a coupling agent selected from one of N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide, or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide;
wherein said coupling agent is provided and mixed with said elastomer(s), according to one or more of the following:
(1) mixing said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide with said elastomer(s) and said particulate reinforcement, preferably in an internal rubber mixer.
(2) pre-reacting said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide with
(a) precipitated silica aggregates, or
(b) an aqueous dispersion of colloidal silica particles from which precipitated silica aggregates are recovered to form a silica composite thereof,
(3) mixing said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide with said elastomer(s) and said particulate reinforcement, preferably in an internal rubber mixer, according to any of said steps (1) or (2) wherein said particulate reinforcement includes at least one of said synthetic precipitated silica aggregates which has been pre-hydrophobated prior to mixing with said elastomers by reaction with an alkylsilane of the general formula (I):
X
n
—Si—R
4−n
(I)
wherein X is a radical selected from alkoxy radicals having from 1 through 3 carbon atoms, preferably selected from methoxy and ethoxy radicals, and from halogen radicals selected from at least one of chlorine and bromine radicals, preferably a chlorine radical R is an alkyl radical having from 1 to 18 carbon atoms, preferably from 1 through 4 carbon atoms and more preferably selected from methyl and ethyl groups and n is an integer of 1 through 3,
(4) mixing said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide with said elastomer(s) and particulate reinforcement and an alkylsilane of the said formula (I), preferably in an internal rubber mixer, and
(5) mixing said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide and said alkylsilane of formula (I) with said elastomer(s) and said particulate reinforcement, preferably in an internal rubber mixer, wherein said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide and said alkylsilane of formula (I) have all been pre-reacted with
(a) synthetic precipitated silica aggregates, or
(b) an aqueous dispersion of colloidal silica particles from which precipitated silica aggregates are recovered to form a silica composite thereof.
In further accordance with this invention, an article of manufacture is provided a which contains at least one component comprised of the rubber composition of this invention.
If desired, an additional coupling agent in a form of a bis-(3-trialkoxyalkylsilane) polysulfide may be used having from 2 to 8, with an average of from 2 to 2.6 or from 3.5 to 4, sulfur atoms in its polysulfidic bridge may be used.
Such additional coupling agent may be, for example, bis-(3-triethoxysilylpropyl) polysulfide having from 2 to 8, with an average of from 2 to 2.6 or from 3.5 to 4, sulfur atoms in its polysulfidic bridge.
A significant aspect of the invention is the use of the N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide to enhance electrical conductivity of the rubber composition. It is envisioned herein that such phenomenon is accomplished by attachment of the diol (dihydroxy) portion of the bromide salt to the silica surface with water elimination and attachment of the oleyl or mercapto moiety to the diene polymer, giving a non-silane charged nitrogen salt bridge between th
Wideman Lawson Gibson
Zanzig David John
Niland Patrick D.
The Goodyear Tire & Rubber Company
Young, Jr. Henry C.
LandOfFree
SILICA REINFORCED RUBBER COMPOSITION WHICH CONTAINS... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with SILICA REINFORCED RUBBER COMPOSITION WHICH CONTAINS..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and SILICA REINFORCED RUBBER COMPOSITION WHICH CONTAINS... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2929077