| 摘要 |
A printing material composed of an open-cell sponge rubber capable of including therein a colored ink, which does not necessitate a stamp pad for the stamping operation, is disclosed. This printing material is prepared by adding appropriate amounts of soluble starch and a fine powder of an easily water-soluble salt which does not decompose or gasify at a curing temperature to a mixture of a starting rubber, a curing agent and a filler, kneading and milling the mixture, introducing the mixture into a mold, heating the mixture to effect curing, removing said starch and salt by washing, and drying the resulting product.
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