abstract |
Natural rubber contains a viscosity stabilizer for the natural rubber, and the viscosity stabilizer includes a hydrazide compound of the following general formula, R-CONHNH2 wherein R is an alkyl group having 1 to 5 carbon atoms or a cycloalkyl group having 3 to 5 carbon atoms. As a result, gelation (storage hardening) is suppressed and a decrease in molecular weight is prevented. |