Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-11-12
2001-01-09
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S492000, C524S493000, C152S151000
Reexamination Certificate
active
06172138
ABSTRACT:
FIELD
This invention relates to preparation of an elastomer which contains a dispersion of filler reinforcement by forming a filler reinforcement in-situ within the elastomer host, the resulting elastomer/filler composite and tire having component which contains such reinforced elastomer.
This invention further relates to a rubber composition of at least two elastomers wherein one of said elastomers is a pre-formed composite of elastomer and in-situ formed filler reinforcement. The invention also relates to a tire having a component of such rubber composition. It particularly relates to a tire with a tread of such composition.
BACKGROUND
Elastomers are conventionally reinforced with particulate reinforcing fillers such as, for example, carbon black and sometimes precipitated silica.
It is sometimes difficult to obtain an adequate, homogeneous dispersion of the reinforcing filler, particularly silica, in the rubber composition, by conventionally blending the rubber and filler under high shear conditions.
Accordingly, however, an adequate, homogeneous, dispersion of the reinforcing filler particles within the rubber composition is sometimes desired.
In one aspect, it has heretofore been proposed to create a dispersion of silica in polysiloxane polymers such as poly(dimethylsiloxane), or (PDMS), elastomer(s) by in-situ formation of silica from a base-catalyzed sol-gel conversion of tetraethoxysilane (TEOS). For example see “Precipitation of Silica-Titania Mixed-Oxide Fillers Into Poly(dimethylsiloxane) Networks” by J. Wen and J. Mark;
Rubber Chem and Tech,
(1994), volume 67, No.5, (pages 806-819).
A process of preparing rubber products has been suggested by mixing the TEOS with a solution of unvulcanized rubber in an organic solvent and subjecting it to a sol-gel condensation reaction to provide a finely powdered silica. For example, see Japanese patent application publication 93/02152.
Further, a composition has been suggested as comprising a base rubber and globular silica made by a sol-gel method and having an average particle diameter of 10-30 microns and specific surface area of 400-700 square meters per gram. The composition is suggested for use in a flap of a tire. For example, see Japanese patent application publication 6145429.
Also, a tread rubber composition has been proposed as a composition of a base rubber and spherical silica prepared by a sol-gel transformation. For example, see Japanese patent application publication 6116440 and corresponding Japanese patent publication 2591569.
Further, an in-situ formation of silica from a sol gel reaction of TEOS in an organic solution of styrene/butadiene rubber, onto which a bis(3-triethoxysilylpropyl) tetrasulfide has been previously grafted to form triethoxysilyl groups, has been reported. (“The Effect of Bis(3-triethoxysilylpropyl) Tetrasulfide on Silica Reinforcement of Styrene-Butadiene Rubber” by Hashim, et al, in
Rubber Chem
&
Tech,
1998, Volume 71, pages 289-299).
In the description of this invention, the term “phr” where 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 “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 such terms are well known to those having skill in the rubber mixing or rubber compounding art.
SUMMARY AND PRACTICE OF THE INVENTION
In accordance with this invention, a method is provided of preparing an elastomer/filler composite as a dispersion of a filler formed in-situ within an elastomer host which comprises:
A) blending a filler precursor, condensation reaction promoter and elastomer host selected from elastomer host (A) and elastomer host (B), in a medium of (1) an organic solvent solution of said elastomer host or (2) an aqueous latex of said elastomer host, preferably in an organic solvent solution, to initiate a condensation reaction of said filler precursor and, for elastomer host (A), and optionally for elastomer host (B), subsequently adding and reacting an organosilane material with said filler/filler precursor prior to the completion of said condensation reaction; followed by recovering the resulting elastomer/filler composite; or
B) blending, in an internal rubber mixer, a filler precursor, condensation reaction promoter and elastomer host selected from elastomer host (A) and elastomer host (B), to initiate a condensation reaction of said filler precursor and, for elastomer host (A), and optionally for elastomer host (B), subsequently adding and reacting, in an internal rubber mixer, an organosilane material with said filler/filler precursor prior to the completion of said condensation reaction; followed by recovering the resulting elastomer/filler composite; or
C) immersing an elastomer host selected from elastomer host (A) and elastomer host (B) in a liquid filler precursor, and allowing said filler precursor to imbibe into said elastomer host to cause the elastomer host to swell, applying a condensation reaction promoter to said swelled elastomer host to initiate a condensation reaction of said filler precursor and, for elastomer host (A), and optionally for elastomer host (B), subsequently adding and reacting an organosilane material with said filler/filler precursor prior to the completion of said condensation reaction; followed by recovering the resulting elastomer/filler composite; wherein said elastomer host (A) is selected from at least one of homopolymers of conjugated dienes, copolymers of conjugated dienes, copolymers of conjugated diene with a vinyl aromatic compound, preferably selected from styrene and alpha-methylstyrene and more preferably styrene; wherein said elastomer host (B) is selected from at least one alkoxy metal end functionalized diene-based elastomer having, for example, a general formula (I):
elastomer-X-(OR)
n
(I)
wherein X is selected from silicon, titanium, aluminum and boron, preferably silicon, R is selected from alkyl radicals having from 1 to 4 carbon atoms, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl and isobutyl radicals, more preferably ethyl radicals, and n is 3 for silicon and titanium and is 2 for aluminum and boron, and wherein said elastomer is selected from at least one of homopolymers of conjugated dienes, copolymers of conjugated dienes, copolymers of conjugated diene with a vinyl aromatic compound, preferably selected from styrene and alpha-methylstyrene, and more preferably styrene; and
wherein said filler precursor is at least one material selected from the formulas (IIA), (IIB) and (IIC):
M(OR)
x
(R′)
y
(IIA)
(RO)
x
(R′)
y
M—O—M′(R′)
z
(RO)
w
(IIB)
(RO)
x
(R′)
y
M—(CH
2
)
r
—M′(R′)
z
(RO)
w
(IIC)
wherein M and M′ are the same or different and are selected from silicon, titanium, zirconium, boron and aluminum, preferably silicon, where R and R′ are individually selected from alkyl radicals having from 1 to 4 carbon atoms, preferably from methyl, ethyl, n-propyl, isopropyl, n-butyl and isobutyl radicals, wherein R is preferably an ethyl radical and R′ is preferably a methyl radical, and wherein the sum of each of x+y and w+z integers is equal to 3 or 4 depending upon the valence of the associated M or M′, as the case may be and is, therefore, 4 except when its associated M or M′ is boron or aluminum for which it is 3, and wherein r is from 1 to 15, preferably from 1 to 6;
wherein said organosilane is at least one material selected from formula (III), (IV) and (V), namely:
an organosilane polysulfide of formula (III) as:
Z—R
1
—S
m
—R
1
—Z (III)
wherein m is a number in a range of from 2 to about 8 and the average for m is in a range of (a) about 2 to about 2.6 or (b) about
Agostini Giorgio
Materne Thierry Florent Edm{acute over (e)}
Thielen Georges Marcel Victor
Cain Edward J.
The Goodyear Tire & Rubber Company
Wyrozebski Katarzyna
Young, Jr. Henry C.
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