Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-07-30
2001-03-27
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S346000, C525S387000, C556S413000, C524S492000, C524S495000, C152S450000
Reexamination Certificate
active
06207757
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. § 119 of German Patent Application No. 198 34 804.5, filed on Aug. 1, 1998, the disclosure of which is expressly incorporated by reference herein in its entirety.
Reference is made to U.S. application Ser. No. 09/305,225 filed Jul. 30, 1999, now U.S. Pat. No. 6,133,364, entitled “Rubber Composition, Method of Formulating the Composition and Vehicle Tire Made From the Composition”, which is concurrently filed with the present application.
Reference is also made to U.S. application Ser. No. 09/365,226 filed Jul. 30, 1999, entitled “Rubber Composition, Method of Formulating and Blending the Same and Article and Tires Made Therefrom”,which is concurrently filed with the present application.
1. Field of the Invention
The invention relates to a rubber composition that contains at least one rubber component and at least one initial filler whose surface has nucleophilic groups, more particularly hydroxyl groups, as well as additional customary additives. The composition is particularly useful in tire treads, and the invention relates to tires containing the inventive composition.
2. Discussion of Background Information
Rubber compositions are used for the manufacture of rubber products with an extremely wide variety of applications. Depending on the field of use, different demands are placed on the particular rubber composition. Thus, in addition to the rubber components, the rubber composition contains further constituents such as fillers, anti-aging agents, and vulcanizing agents, which materially affect the properties of the finished rubber product. For this reason, suitable systems of polymer and additional constituents must be prepared to obtain the appropriate properties of the rubber product. Fillers in a rubber composition are accorded great importance. Not only do they contribute to lowering the price of rubber compositions, their specific effects on the rubber are also exploited. For this reason, there has been no lack of experiments, e.g., to mix an extremely wide variety of fillers in the rubber composition. Carbon black and silicic acid, for example, are known as fillers. It has been observed that rubber products containing carbon black as filler, for example, possess adequate mechanical load capacity, but when these compositions are used in tire treads, the tires have the disadvantage that they have a high rolling resistance and poor wet skid behavior. An attempt has been made to solve this problem by mixing silicic acid into the tread composition; this in turn requires a filler activator for binding to the polymer. However, it has been observed that rubber products that contain silicic acid as filler and a conventional organosilane (e.g., bis-3-(triethoxysilylpropyl)tetrasulfide) as filler activator have an inadequate influence on the hysteresis behavior and the reinforcement of the rubber product for modern application areas.
Thus, current rubber compositions for the manufacture of vehicle tires (e.g., tire treads) are required that, in the vulcanized state, lend the tire even lower rolling resistance, resulting in reduced fuel consumption. At the same time, other characteristics, such as durability and wet skid behavior, should not be adversely affected, if possible.
SUMMARY OF THE INVENTION
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure.
The present invention provides for the preparation of rubber compositions that have improved hysteresis behavior in the vulcanized state so that when these rubber compositions are used, e.g., in tires, the rolling resistance is reduced. Also the present invention provides for an elastomer or rubber composition which can be better strengthened through the use of an appropriate filler system.
The invention further provides for a composition for use in tire treads having a rubber mixture that can be vulcanized with sulfur, which includes:
a) at least one rubber component,
b) at least one filler having nucleophilic groups,
c) as an additional filler, gel particles comprising a rubber, having a particle size between about 3×10
−9
and about 1×10
−6
m and a swelling index in toluene of about 1 to about 15 and whose surface has electrophilic centers,
d) a substance acting as a coupling agent between the filler having nucleophilic groups and the additional filler. The substance acting as the coupling agent has the following structure:
X—R
1
—Si—(R
2
)
3
wherein
X is a nucleophilic group,
R
1
is an alkyl group having up to about 6 carbon atoms or a phenyl group, and
R
2
may be the same as or different from each other and from R
1
and is an alkyl or alkoxy group having up to about 6 carbon atoms and at least one of R
2
is an alkoxy group.
X may be NH
2
, SH, or NHR
3
, wherein R
3
may be an alkyl group having up to about 3 carbon atoms or a phenyl group. R
1
and R
2
may be branched, unbranched or cyclic alkyls. The substance acting as a coupling agent may be one or both of aminopropyltriethoxysilane or 3-(2-aminoethylamino)-propyl-trimethoxysilane. The nucleophilic groups of the filler may be silanol groups. The filler with the silanol groups may be silica. The filler may further be carbon black having silanol groups located on its surface. The rubber component may be selected from natural rubber, synthetic polyisoprene, styrene butadiene, polybutadiene, or mixtures thereof. The composition may contain about 10 to about 110 phr gel and about 10 to about 110 phr silicic acid relative to 100 parts of total rubber material. The gel may be selected from the group selected from a polymer of butadiene with p-chloromethyl styrene, a polymer of styrene butadiene rubber modified with p-chloromethyl styrene, and a polymer of butadiene with methacrylic methylester, wherein each polymer has a swelling index in toluene between about 1 and about 15 and a particle size between about 3×10
−9
and about 1×10
−6
m. Preferably, the gel is styrene butadiene rubber modified with p-chloromethyl styrene with a swelling index in toluene between about 1 and about 15 and a particle size between about 3×10
−9
and about 1×10
−6
m.
The invention also provides for a vehicle tire having a tread formed of a composition which includes a rubber mixture that can be vulcanized with sulfur. The composition includes:
a) at least one rubber component,
b) at least one filler having nucleophilic groups,
c) as an additional filler, gel particles comprising a rubber, having a particle size between about 3×10
−9
and about 1×10
−6
m and a swelling index in toluene of about 1 to about 15 and whose surface has electrophilic centers,
d) a substance acting as a coupling agent between the filler having nucleophilic groups and the additional filler. The substance acting as the coupling agent has the following structure:
X—R
1
—Si—(R
2
)
3
wherein
X may be a nucleophilic group,
R
1
may be a branched, unbranched or cyclic alkyl group having up to about 6 carbon atoms or a phenyl group, and
R
2
may be the same as or different from each other and from R
1
and may be a branched, unbranched or cyclic alkyl or alkoxy group having up to about 6 carbon atoms, and at least one of R
2
is an alkoxy group.
X may be NH
2
, SH, or NHR
3
, wherein R
3
may be an alkyl group having up to about 3 carbon atoms or a phenyl group. The substance acting as a coupling agent may be aminopropyltriethoxysilane or 3-(2-aminoethylamino)-propyl-trimethoxysilane. The nucleophilic groups of the filler may be silanol groups. The rubber component may be selected from natural rubber, synthetic polyisoprene, styrene butadiene, polybutadiene, or mixtures thereof and the gel may be selected from the group selected from a polymer of butadiene with p-chloromethyl styrene, a polymer of styrene butadiene rubber modified with p-chloromethyl styrene, and a polymer of butadiene with methacrylic methylester, wherein each polymer has a swelling index in tol
Monroy Victor
Obrecht Werner
Scholl Thomas
Well Michael
Wendling Peter
Continental Aktiengesellschaft
Dawson Robert
Greenblum & Bernstein P.L.C.
Peng Kuo-Liang
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