| 摘要 |
PROBLEM TO BE SOLVED: To perform a clear stamping without generating warping on a stamping face even when both a top layer and a base layer are made of silicone rubber foams. SOLUTION: A stamp material for a permeating seal has a double layer structure in which the base layer for occluding ink comprising a porous silicone rubber is integrally laminated on the back face of the top layer comprising a porous silicone rubber with ultrafine air bubbles. In the top layer, among main ultrafine air bubbles exceeding 50 vol.% of the whole ultrafine air bubbles and having the air bubble diameter of at most 20μm, sub-ultrafine air bubbles with the air bubble diameter being larger than the largest main ultrafine air bubble but at most 40μm are mixed. On the other hand, the base layer has the fine air bubbles with the air bubble diameter of 150-300μm and has a lower hardness than that of the top layer. COPYRIGHT: (C)2008,JPO&INPIT
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