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
2003-03-05
2004-04-13
Wu, David W. (Department: 1713)
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...
C524S084000, C524S099000, C524S257000, C524S424000, C152S450000
Reexamination Certificate
active
06720378
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rubber composition, more specifically, it relates to a rubber composition containing a rubber and compounding agents easy to produce and having an excellent wet skid resistance and low rolling resistance.
2. Description of the Related Art
Along with the improvement in performance and improvement in functions of automobiles, demands for the high performance of tires have been increased from year to year. As one of these, there is a strong demand for development of a tire having a strong grip on wet roads, that is, a good wet skid resistance, and providing also a low fuel consumption property. To obtain a low fuel consumption tire, it is necessary to make the tire small in hysteresis loss. However, if the hysteresis loss is reduced, the rolling resistance becomes smaller and the grip is reduced, and therefor, problems arise in driving safety. On the other hand, if the wet skid resistance is improved in order to increase the grip, the rolling resistance, that is, the hysteresis loss, becomes larger and the tire is made poor in fuel consumption property.
Due to this antimonic relationship between the wet skid resistance and the rolling resistance, active researches have been made to satisfy both demands for tire use rubber compositions Various compounding agents for rubber compositions have been reported for rubber compositions providing a large wet skid resistance in spite of a low rolling resistance.
As such compounding agents for improving the dynamic behavior, nitroso-based compounds have been reported. However, nitrosoamine compounds suffer from the problem of a deleterious effect on the human body. At present, the commercial, production thereof has been stopped. (See Kenneth W. Doak et al.,
Rubber Chem. Technol
., 28, 895 (1995), Payne, A. R. et al.;
J. Rubber Res. Inst. Malaya
, 22, 275 (1969), Walker, L. A. et al.,
Rubber Age
90, 925 (1962), Patts, K. T. et al.,
Rubber Chem. Technol
., 47, 289 (1974), Daniel F. Graves,
Rubber Chem. Technol
., 66, 61 (1993).)
Further, dinitroamine-based compounds have been reported as another compounding agents. However, it is reported that, while the improvement in the dynamic behavior as mentioned above is recognized for polyisoprene-based rubber, it is not recognized for butadiene-based rubber such as SBR. (See Yamaguchi, T. et al.;
Kautsch. Gummi. Kunstst
., 42, 403 (1989).)
As compounding agents exhibiting the above effect on polyisoprene-based rubber and butadiene-based rubber, dialkylamino group-containing sulfur compounds (see Japanese Unexamined Patent Publication (Kokai) No. 9-278942) and aminobenzenesulfonylazide (see Gonzalez, L. et al.;
Rubber Chem. Technol
., 69, 266 (1996)) have been reported. However, these compounds have defects such as the many production steps and the complicated production process and, in the case of the latter azide compounds, the use, as a synthesis starting material of sodium azide, which has explosiveness and requires caution in handling.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a rubber composition containing a rubber and easy-to-produce compounding agents to provide an excellent wet skid resistance and a low rolling resistance.
In accordance with the present invention, there is provided a rubber composition comprising (i) 100 parts by weight of a rubber and (ii) 10 to 180 parts by weight of a composite composed of an oxidative condensate obtained by oxidative condensation of a &pgr;-electron aromatic compound and carbon black.
PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION
It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.
According to the present invention, by compounding a composite (hereinafter sometimes referred to as the “composite” according to the present invention) composed of (i) an oxidative condensate obtained by oxidative condensation of a &pgr;-electron aromatic compound (hereinafter sometimes referred to as the “oxidative condensate” according to the present invention) and (ii) carbon black to a rubber, a good wet skid resistance and low rolling resistance can be obtained. Further, the composite of the present invention is a compounding agent having an extremely high industrial applicability, since it is easy to produce.
The &pgr;-electron aromatic compound useable in the present invention is not particularly limited so long as it can form the oxidative condensate of the present invention with an oxidizing agent. The preferable compounds are, for example, aniline, naphthylamine, phenylenediamine, naphthylenediamine, triaminobenzene, triaminonaphthalene, pyrrole, indole, carbazole, thiophene, selenophene, imidazole, furan, benzene, azulene, pyrene, triphenylene, fluorene, benzenedithiol, diphenyldisulfide, phenol, diethynylbenzene, and their derivatives. As the derivatives, for example, compounds having at least one substituent group such as a C
1
to C
30
alkyl group, C
1
to C
30
alkoxy group, C
2
to C
30
alkylenoxide group, sulfonic acid group, C
2
to C
30
alkylene sulfonic acid group, hydroxyl group, nitro group, amino group, cyano group (di)alkylamino group (i.e., C
1
to C
30
alkyl group), which are introduced into their aromatic rings may be mentioned. Further, the above compounds may be used alone or in any mixture thereof.
The oxidizing agent usable in the present invention is not particularly limited so long as it can oxidatively condense the &pgr;-electron aromatic compound and form the oxidative condensate of the present invention. The preferable oxidizing agents are, for example, persulfates such as ammonium persulfate and potassium persulfate; trivalent ferric salts such as iron (III) chloride, iron (III) sulfate, and iron (III) nitrate; bivalent copper salts such as copper (II) chloride; permanganates such as sodium permanganate and potassium permanganate; bichromates such as potassium bichromate and sodium bichromate; peroxides such as hydrogen peroxide and peracetic acid; oxygen; ozone; oxidizing enzymes (for example, those illustrated in Liu, W. et al.;
J. Am. Chem. Soc
. 1999, 121, 71). Further, redox-based initiators such as those composed of divalent ferrous salts and hydrogen peroxide or Lewis acids (e.g., aluminum trichloride, iron trichloride, etc.) and oxidizing agents (e.g., copper salts such as cuprous chloride, cupric chloride, etc.), air (oxygen), etc.) in combination may also be used (for example, those illustrated in Toshima, N. et al.;
Chem. Lett
. 2000, 1428 or Toshima, N.; Makromol. Chem.,
Macromol. Symp
. 1992, 59, 123). The above oxidizing agents may be used alone or in any mixture thereof. The addition amount of the oxidizing agent is preferably 0.005 to 20, more preferably 0.01 to 10, in terms of molar ratio with respect to the &pgr;-electron aromatic compound (oxidizing agent/&pgr;-electron aromatic compound).
As the oxidative condensate of the present invention, it is possible to use those previously obtained by oxidative condensation of the &pgr;-electron aromatic compound or to perform oxidative condensation after bonding the &pgr;-electron aromatic compound to the carbon black, or to be bonded to the carbon black simultaneously with the oxidative condensation. The oxidative condensate is not particularly limited so long as oxidative condensation of the above &pgr;-electron aromatic compound can be obtained. Preferably, those obtained by oxidative condensates of aniline, pyrrole, thiophene and the derivatives thereof are exemplified.
The &pgr;-conjugated polymer was mentioned as an example of the oxidative condensate of the present invention. This is a polymer having a &pgr;-conjugated system along the polymer chain and is known to exhibit electroconductivity upon doping. Examples of such &pgr;-conjugated polymers are polyaniline, polythiophene, polypyrrole, poly(p-phenylene), poly(p-phenylenevinylene), and derivatives thereof. Among these, those having
Ishikawa Kazunori
Kirino Yoshiaki
Maruyama Tsukasa
Arent & Fox PLLC
Hu Henry S
Wu David W.
Yokohama Rubber Co., Ltd
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