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
1998-06-23
2001-04-24
Cain, Edward J. (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...
C524S493000, C524S495000, C524S496000, C523S212000, C523S213000, C523S214000, C523S215000, C523S216000, C523S217000
Reexamination Certificate
active
06221950
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an unvulcanized rubber mixture, which contains an unvulcanized rubber, aggregate, and at least one filler.
2. Discussion of Background
In an unvulcanized rubber mixture, the fillers have significant importance. Not only do they contribute to the cost reduction of unvulcanized rubber mixtures, but their specific effects upon the unvulcanized rubber are utilized. In the field of unvulcanized rubber, one differentiates the fillers according to the distinctiveness of their effect (activity). The activity of a filler is dependent upon its particle size, its specific surface, its geometric shape, and its chemical composition. Thus, one characterizes fillers as active (reinforcing fillers), in which a characteristic optimum is noted in relation to its concentration, such that this unvulcanized rubber feature is “actively” influenced. For example, carbon black and silicic acid are included among these fillers. In contrast to the reinforcing fillers, an almost exclusively constant alteration of the feature image can be observed in the inactive fillers (reinforcing only via volume content), with the degree of the filler. For example, chalk may be used as an inactive filler in unvulcanized rubber mixtures.
As already mentioned, the activity of a filler is dependent upon the particle size, the specific surface, the geometric form of the particle, and its chemical structure. The reinforcing effect is essentially based upon physical and/or chemical reciprocal actions at the border between the filler and the unvulcanized rubber matrix. The surface characteristics of the fillers especially play a significant role. It is, for example, known to modify the surface of silicic acid with a hydrosilicon, in order to produce a good bond to the unvulcanized rubber matrix and thus to influence positively the characteristics of the vulcanized material. Such measures are known, for example, for the production of treads for vehicle pneumatic tires, which give the vehicle pneumatic tires a low rolling friction and a good wet skidding performance. However, such interactions between filler and unvulcanized rubber matrix are based upon a one-time, irreversible coupling process during the manufacture of the vulcanized material. If, however, the atmospheric temperature or the load condition of the vulcanized material changes, for example, a filler which is bound in the conventional way to the matrix is no longer in a position to react to these influences, in order to ensure sufficient dynamic-mechanical characteristics, for example, when the vulcanized material is being used.
SUMMARY OF THE INVENTION
The present invention involves manufacturing an optimal bond, at least between filler and unvulcanized rubber matrix, such that it is possible to adapt the characteristics of the vulcanized material to conditions, e.g., changing atmospheric conditions.
This task is solved in accordance with the invention because the filler surface is modified with a substance which exhibits stimuli-sensitive characteristics.
In accordance with one aspect, the present invention is directed to an unvulcanized rubber mixture, comprising at least one rubber, aggregate, and at least one filler, wherein a surface of the at least one filler has been modified with a stimuli-sensitive substance.
In accordance with another aspect, the at least one rubber comprises natural rubber.
In accordance with yet another aspect, the stimuli-sensitive substance is heterotelechelous. The stimuli-sensitive substance may comprise polysilamine. The polysilamine may have the following structure:
wherein:
1) R
1
, R
2
, R
3
, R
4
, R
5
, and R
6
are selected from the group consisting of: —H, -Alkyl (branched or unbranched), -Alkenyl (branched or unbranched), -Acyl, -Silyl, —NH
2
, —SH, —OH, —COOH, —COH, —NOH, —CN, and —NC;
2) R
5
≠R
6
;
3) n, m, and i have values of about 0 to 5; and
4) j>2.
In particular, the above-noted polysilamine may involve the following structure:
wherein:
1) R
7
, R
8
, R
9
, and R
10
are selected from the group consisting of: —H, -Alkyl (branched or unbranched), -Alkenyl (branched or unbranched), -Acyl, -Silyl, —NH
2
, —SH, —OH, —COOH, —COH, —NOH, —CN, and —NC; and
2) k, l, p, and q have values of about 0 to 5.
In accordance with another aspect, the at least one filler comprises an active filler, wherein a surface of the active filler is modified with the stimuli-sensitive substance. The active filler may comprise at least one member selected from the group consisting of carbon black, silicic acid, carbon black modified by silicic acid, and polymer microgel.
In accordance with yet another aspect, the at least one filler comprises an inactive filler, wherein a surface of the inactive filler is modified with the stimuli-sensitive substance.
In accordance with still another aspect, the at least one natural rubber comprises at least one member selected from the group consisting of natural rubber, styrene-butadiene-copolymer, acrylonitrile-butadiene-copolymer, isoprene-butadiene-copolymer, polybutadiene, synthetic polyisoprene, isoprene-isobutylene-copolymer, and ethylene-propylene-diene-terpolymer.
In accordance with another aspect, the present invention is directed to a filler for unvulcanized rubber mixtures, wherein a surface of the filler is modified with a stimuli-sensitive substance.
In accordance with another aspect, the present invention is directed to a process for making an unvulcanized rubber mixture comprising at least one rubber, aggregate, and at least one filler, wherein a surface of the at least one filler has been modified with a stimuli-sensitive substance, the process comprising coating a surface of at least one filler with a stimuli-sensitive substance to form at least one coated filler, and mixing the at least one coated filler with unvulcanized rubber and aggregate.
In accordance with another aspect, the present invention is directed to a rubber product formed from an unvulcanized rubber mixture, comprising at least one rubber, aggregate, and at least one filler, wherein a surface of the at least one filler has been modified with a stimuli-sensitive substance.
In accordance with another aspect, the present invention is directed to vulcanized rubber, comprising a rubber matrix comprising aggregate and at least one rubber, and at least one filler, wherein a surface of the at least one filler has been modified so as to form a stimuli-sensitive rubber mixture with the rubber matrix surrounding the at least one filler.
In accordance with another aspect, the at least one rubber comprises at least a first rubber and a second rubber, wherein the surface of the at least one filler is modified such that a stimuli-sensitive rubber mixture forms between the first rubber which is located on the filler surface and the second rubber.
In accordance with yet another aspect, the at least one rubber is selected from the group consisting of natural rubber, styrene-butadiene-copolymer, acrylonitrile-butadiene-copolymer, isoprene-butadiene-copolymer, polybutadiene, synthetic polyisoprene, isoprene-isobutylene-copolymer, and ethylene-propylene-diene-terpolymer. In particular, the at least one rubber may comprise at least polyisoprene and polybutadiene.
In accordance with another aspect, the present invention is directed to a process for making vulcanized rubber comprising a rubber matrix comprising aggregate and at least one rubber, and at least one filler, wherein a surface of the at least one filler has been modified so as to form a stimuli-sensitive rubber mixture with the rubber matrix surrounding the at least one filler, the process comprising coating a surface of at least one filler with unvulcanized rubber to form at least one coated filler, mixing the at least one coated filler with unvulcanized rubber and aggregate to form an unvulcanized rubber mixture, and vulcanizing the unvulcanized rubber mixture.
REFERENCES:
patent: 3994742 (1976-11-01), Russel et al.
patent: 5409969 (1995-04-01), Hamada
patent: 5486560 (1996-01-01), Shiga et al.
pa
Heinrich Gert
Recker Carla
Cain Edward J.
Continental Aktiengesellschaft
Greenblum & Bernstein P.L.C.
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