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AssigneeSumitomo Chemical Company, Limited
InventorsNaoki Inui, Hironobu Iyama, Kyoko Tsuta, Hideo Nagasaki
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The present invention relates to a method for producing a vulcanized rubber by compounding in a kneading step at a relatively high temperature, a rubber and a flavan compound of the formula (I) ##STR1## wherein R.sup.1, R.sup.2, R.sup.4 and R.sup.5 independently of one another represent a hydrogen or an aliphatic group having 1-6 6 carbon atoms, or R.sup.1 and R.sup.2 together with the carbon atoms to which they are attached and/or R.sup.4 and R.sup.5 together with the carbon atom to which they are attached form an alicyclic ring having 4-10 carbon atoms, R.sup.3 is a hydrogen or an aliphatic group having 1-6 carbon atoms, and X and Y independently of one another are hydrogen, hydroxy or an aliphatic group having 1-8 carbon atoms; also, a rubber composition containing a flavan compound according to the above formula together with a cobalt-containing compound and a methylene donor; the vulcanized rubber produced through the method or from the rubber composition exhibits excellent rubber properties such as, for example, increased hardness and processability essentially free from fuming problems.
A method for producing a vulcanized rubber comprising compounding:
A method for increasing hardness and dynamic modulus of elasticity of a vulcanized rubber comprising compounding:
Dependencies are inferred from the claim text.