PURPOSE: To obtain rubber containing continuous micro-air bubble on efficient industrial basis by adding foaming agent and water-soluble extracted material to rubber raw material, mixing and kneading, and foaming, vulcanizing while extracting the extracted material with water.
CONSTITUTION: (B) Powdered foaming agent (e.g. NaHCO3, N-diazocarbonylamide, etc.) and (C) powdered water-soluble extract (e.g. urea, KNO3, etc.) are added to (A) rubber raw material obtained by adding vulcanizing agent, etc. to polymers such as NBR, SBR rubber or the like, and mixed, preferably employing an open mixing mill, thereby rubber material is prepared. This blended and kneaded rubber material is vulcanized in a prearranged metal mold, etc., and then an extracted material is extracted by compressing and expanding the foamed product in water to obtain sponge rubber required. For addition ratio, it is recommended that component B 5W20 parts (inorganic matter) or 1W5 parts (organic matter) and component C 200W700 parts will be against 100pts.wt. of component A.
FUJISAKI MITSUO
IWASAKI HIROYUKI
