Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-04-19
2004-10-26
Mulcahy, Peter D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
Reexamination Certificate
active
06809135
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the preparation of silica reinforced rubber compositions and to articles of manufacture which contain at least one component comprised thereof. Such article of manufacture may be a tire. The silica reinforced rubber composition comprises at least one elastomer, silica, and an organo-metal additive of least one of organo-tin, organo-titanium, and/or organo-zirconium compound, preferably to an exclusion of additional additives to the rubber composition which will readily react with hydroxyl groups (e.g. silanol groups) on the surface of the silica to create an alcohol such as, for example, alkylsilane, alkoxysilane, and bis-(3-alkoxysilylalkyl) polysulfide compounds. Such organo-metal compound may have a valance of four and in the case of the organo-tin compound may have a valance of four or two, preferably four. Such organo-metal compound may be selected from, for example, dibutyltin dilaurate, tin(II) 2-ethylhexanoate, dibutoxytitanium bis-2,4-pentanedionate, and dibutoxyzirconium bis-2,4-pentanedionate.
BACKGROUND OF THE INVENTION
For various applications utilizing rubber which require high strength and abrasion resistance, particularly applications such as tires and various industrial products, sulfur cured rubber is utilized which contains substantial amounts of reinforcing fillers.
Synthetic amorphous silica, such as for example, precipitated silica, and carbon black are commonly used reinforcing fillers for such purpose as is well known to those having skill in such art.
Such silica is often used in conjunction with a coupling agent in order to aid in coupling the silica to one or more elastomers, particularly conjugated diene-based elastomers. Such coupling agent conventionally has a moiety which is reactive with hydroxyl groups on the surface of the silica (e.g. silanol groups) and another moiety interactive with at least one of said diene-based elastomers in the rubber composition to be reinforced.
Conventionally, the moiety of the coupling agent intended to react with the hydroxyl groups on the surface of the silica is a silane-based moiety such as, for example, an alkoxysilane moiety which might be contained, for example in a coupling agent such as a bis (3-ethoxysilylpropyl) polysulfide which contains from 2 to about 6, with an average of about 2 to 2.6 or from 3.5 to 4 connecting sulfur atoms in its polysulfidic bridge.
Inherently, byproducts of an interaction of such coupling agent with hydroxyl groups on the surface of the silica is alcohol (e.g. ethanol) and water.
In the surprising discovery of this invention, a compound has been found which apparently acts to assist the silica in the reinforcement of a diene-based elastomer without having to use a conventional coupling agent for which alcohol is a byproduct.
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” where 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 rubber composition is provided which comprises
(A) 100 parts by weight of at least one diene-based elastomer,
(B) about 10 to about 150, alternately about 10 to about 100, phr of at least one particulate reinforcing filler comprised of about 10 to about 100, alternately about 10 to about 80 of at least one particulate synthetic silica-based material which contains hydroxyl groups (e.g. silanol groups) on the surface thereof and correspondingly, about 0 to about 80, alternately about 5 to about 40 phr of rubber reinforcing carbon black, and
(C) at least one organo-metal additive of at least one of organo-tin, organo-titanium and/or organo-zirconium compound, such organo-metal compound may have a valance of four and in the case of the organo-tin compound may have a valance of four or two, preferably four. Such organo-metal compound may be selected from, for example, dibutyltin dilaurate, tin(II) 2-ethylhexanoate, dibutoxytitanium bis-2,4-pentanedionate, and dibutoxyzirconium bis-2,4-pentanedionate.
In one aspect of this invention the said organo-tin compound having a valence of four may be, for example, dibutyltin dilaurate.
In particular, while dibutyltin dilaurate is the preferred organo-tin compound having a valence of four it is contemplated herein that said organo-tin compounds having a valence of four may be of the following general Formula (I), with corresponding specifications (I-a), (I-b), (I-c), and (I-d):
R
z
2
Sn[Q(C(R
X
))
a
(C(H)
c
H)
b
(C(O))
d
R
y
]
2
(I)
wherein:
(I-a) where Q is oxygen, a and b are zero, d is equal to one, and R
y
is an alkyl radical containing from one to 25, alternatively from 1 to 18, carbon atoms, where R
z
is an alkyl radical containing from one to 25, alternatively from 1 to 10, carbon atoms, or
(I-b) where Q is oxygen, a, b, and d are equal to one, c is zero, R
x
and R
y
are the same or different radicals selected from hydrogen, methyl, CF
3
, propyl, butyl and/or phenyl radicals, preferably from hydrogen and methyl radicals, where R
z
is an alkyl radical containing from one to 25, alternatively from 1 to 10, carbon atoms, or
(I-c) where Q is sulfur, a is zero, b, c, and d are one, and R
y
is an alkyl radical containing from one to 25, alternatively from 1 to 18, carbon atoms, where R
z
is an alkyl radical containing from one to 25, alternatively from 1 to 10, carbon atoms, or
(I-d) where Q is oxygen or sulfur, a, b, and d are zero and R
y
is an alkyl radical containing from one to 25, alternatively from 1 to 18, carbon atoms, where R
z
is an alkyl radical containing from one to 25, alternatively from 1 to 10, carbon atoms;
wherein, optionally, one or more of R
x
, R
y
, and R
z
are alkyl radicals containing heteroatoms, such as, for example Silicon, Nitrogen, Phosphorus, Oxygen, and Sulfur.
Representative examples of alkyl radicals for radicals R
x
and R
y
are, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, septyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl which, were possible, may be saturated or unsaturated, cyclic, or aromatic.
Representative examples of alkyl radicals for radicals R
z
are, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, septyl, octyl, nonyl, decyl which, were possible, may be saturated or unsaturated, cyclic, or aromatic.
Representative examples of heteroatom containing alky radicals for R
x
, R
y
, and R
z
are, for example, bis(trimethylsilyl)phosphate, methylpropanoate, 2-ethylhexylmaleate, 1-thioglycerol, and 1-ethoxyvinyl.
Representative examples of materials of Formula I are of the general Formulas (I-A), (I-B), (I-C), and (I-D):
R
2
Sn(OC(O)R)
2
(I-A)
RO
2
Sn(OC(R)CHC(O)R)
2
(I-B)
R
2
Sn(SCH
2
C(O)R)
2
(I-C)
R
2
Sn(OR)
2
(I-D)
wherein R is an alkyl radical of which representative examples may include methyl, ethyl, propyl, butyl, pentyl, hexyl, septyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, aoctadecyl, bis(trimethylsilyl)phosphate, methylpropanoate, 2-ethylhexylmaleate, 1-thioglycerol, and 1-ethoxyvinyl.
Representative examples of organo-metal compounds, namely organotin compounds, of Formula I are, for example, dibutyltin dilaurate, di-n-butylbis(2-ethylhexanoate)tin, di-n-butylbis(2,4-pentanedionate)tin, di-n-butyldiacetoxytin, di-n-butyldiacrylatetin, di-n-butyldimethacrylatetin, dimethyldineodecanoatetin, dioctyldilauryltin, dioctyldineodecanoatetin.
In one aspect of this invention
Bowen, III Daniel Edward
Castner Eric Sean
Mulcahy Peter D.
The Goodyear Tire & Rubber Company
Young, Jr. Henry C.
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