Sumitomo Chemical Company, Limited

Kyoko Tsuta

Naoki Inui

Hideo Nagasaki

Hironobu Iyama

Manji Sasaki

Described herein is a process for preparing a hydroxyflavan compound which comprises reacting a polyhydric phenol compound represented by formula(2): ##STR1## wherein at least one of W, X, Y and Z is hydroxy; with a ketone in the presence of (i)an acid catalyst and (ii)water and/or a seed crystal, using an organic solvent which is insoluble in water, procuces the hydroxyflavan compounds in high yield and with high selectivity while maintaining high conversion of the polyhydric phenol.

Process for preparing hydroxyflavan compounds

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.

Rubber composition containing a flavan compound and a method for

A rubber composition (1) which comprises:

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Kawanishi, Japan

Kyoko Tsuta