Azodicarbonamide treatment for carbon black and rubber compounds
View Patent ↗A process for producing cured rubber is disclosed wherein the process comprises: A) mixing rubber, carbon black, and azodicarbonamide without other curative ingredients; B) adding the remaining curative ingredients in one or more subsequent mixing steps; and then C) curing the rubber; whereby a cured rubber having improved hysteresis is obtained. The cured rubber thus obtained is particularly useful in tires and tire treads.
1. A process for producing cured rubber comprising:
A) mixing rubber, carbon black, and azodicarbonamide without curative ingredients;
B) adding curative ingredients in one or more subsequent mixing steps; and then
C) curing the rubber;
whereby a cured rubber having improved hysteresis is obtained.
2. The process of claim 1 wherein the rubber, carbon black, and azodicarbonamide are mixed for an extended time at a temperature above about 160° C. for a time sufficient to achieve maximum interaction of filler and polymer.
3. The process of claim 2 wherein the mixing time is at least three minutes.
4. The process of claim 1 wherein the rubber and carbon black are mixed in a first mixing step and then the azodicarbonamide is added in a second mixing step.
5. The process of claim 1 wherein the rubber, carbon black, and azodicarbonamide are mixed simultaneously in a single step.
6. The process of claim 1 wherein the azodicarbonamide is present at a concentration of from about 0.1 to about 20 phr in the rubber polymer.
7. The process of claim 1 wherein the rubber is selected from the group consisting of solution polymerized styrene-butadiene rubber, emulsion polymerized styrene-butadiene rubber, natural rubber, polybutadiene rubber, polyisoprene rubber, polyisobutylene rubber, ethylene-propylene-diene terpolymer rubber, and blends of two or more of the foregoing.
8. The process of claim 1 in which the carbon black is used at a level of 30–150 parts per hundred of rubber.
9. An article of manufacture comprising a cured rubber produced by a process comprising:
A) mixing rubber, carbon black, and azodicarbonamide without curative ingredients;
B) adding curative ingredients in one or more subsequent mixing steps; and then
C) curing the rubber.
10. The article of manufacture of claim 9 wherein the article is a tire tread.
11. The article of manufacture of claim 10 wherein the azodicarbonamide is present at a concentration of 0.1 to 20 phr in the tread compound.
12. The article of manufacture of claim 9 wherein the article is a tire.