Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Patent
1997-06-18
2000-02-01
Marcheschi, Michael
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
106475, 524492, 524495, 524424, 523215, 523216, 523210, C08K 902, C08L 2100, C09C 156
Patent
active
06019832&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing surface-treated carbon black for rubber reinforcement (hereinbelow referred to simply as "surface-treated carbon black"). More particularly, it relates to a process for producing surface-treated carbon black for rubber reinforcement having amorphous silica deposited on the surface thereof. The surface-treated carbon black for rubber reinforcement thus obtained provides superior physical properties such as wear resistance, grip performance, and low rolling resistance (i.e., low heat generation), when blended into rubber compositions for tires and various other types of rubber products such as belt conveyors and industrial rollers.
BACKGROUND ART
Reinforcing fillers such as carbon black, silica have long been used for reinforcing rubber or rubber reinforcement. Among these, silica, as compared with carbon black, has a property of a low tan .delta. at high temperatures (around 60.degree. C.) and a high tan .delta. at low temperatures (around 0.degree. C.), and therefore, when used for rubber compositions for tire treads, has the advantage capable of producing a tire having a low rolling resistance and a high gripping power. Silica, however, is inferior to carbon black in wear resistance and has a low electrical conductivity, and therefore, if used for tires, there is the problem that the tire will pick up a charge when driven on and will cause noise in the radio and other electronic equipments in the car and, in some cases, will cause their malfunction.
Covering the surface of the pigment etc. with, for example, silica to improve their dispersibility and to increase the weather resistance has been proposed in, for example, Japanese Examined Patent Publication (Kokoku) No. 50-14254 and Japanese Examined Patent Publication (Kokoku) No. 7-30269, but neither of these makes any reference to covering the surface of the carbon black used for reinforcing the rubber with silica.
SUMMARY OF INVENTION
Accordingly, an object of the present invention is to provide a process for producing surface-treated carbon black for rubber reinforcement, which has a superior tan .delta. temperature dependency of silica, provides excellent wear resistance, and further is free from problems derived from the low electrical conductivity.
In accordance with the present invention, there is provided a process for producing surface-treated carbon black for rubber reinforcement comprising;
a surface treatment reaction step of dispersing carbon black for rubber reinforcement in water followed by reacting a metallic silicate and an acid to thereby deposit amorphous silica on the surface of the carbon black; and
a subsequent aging step of bringing the pH of the dispersion to not more than 7.
DETAILED DESCRIPTION OF THE INVENTION
The present inventors engaged in intensive studies on a process for producing surface-treated carbon black for rubber reinforcement which, as explained above, has the superior tan .delta. temperature dependency of silica, provides excellent wear resistance, and further is free from problems derived from a low electrical conductivity and, as a result, succeeded in achieving the above-mentioned object by depositing silica on the surface of carbon black under the above specified conditions.
As the carbon black for reinforcing rubber usable as the starting material in the present invention, any carbon black which has been generally used in the past as carbon for reinforcement of tires or other rubber products can be used. Preferred types of carbon black are the GPF (General Purpose Furance) to SAF (Super Abrasion Furance) grades. It is possible to variously select these or to blend two or more types, depending on the application of the rubber composition.
According to the present invention, the above-mentioned carbon black for reinforcing rubber is first dispersed in water. To improve the dispersibility of the carbon black, a suitable dispersant (e.g., methanol or various types of surfactants) is added to obtain a homogeneous slurry. Then, a me
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CA 127:35765, Kawamo et al. "Manufacture of surface treated carbon black for reinforcing rubbers with good wear resistance and low electric resistance", corresponds to JP 95-277862, Oct. 1995.
CRC Handbook of Chemistry and Physics, 65th edition, CRC press Inc. Boca Raton, Florida, (no month) 1984.
Kawazoe Masayuki
Kawazura Tetsuji
Takahashi Shuji
Yatsuyanagi Fumito
Marcheschi Michael
The Yokohama Rubber Co. Ltd.
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