| 摘要 |
PURPOSE: To keep good water retaining capacity even at the time of compression or deformation generated at the time of the passage through the joint part or bent part of piping, in a pig composed of sponge like porous foam subjected to the extrusion of the residue in the piping, by wholly compounding a water retaining agent with the pig in a dispersed state. CONSTITUTION: A pig 1 is produced by forming sponge like soft porous foam such as polyurethane foam and wholly compounding a water retaining agent with the compsn. of the foam or the contour part thereof in a dispersed state. That is, in the case of polyurethane foam, the water retaining agent 2 is premixed with polyol being a raw material and isocyanate is mixed with the resulting premix under stirring to form water retaining agent dispersed foam. Or, a conventional pig is used as a core material and the same material is arranged to the periphery of the core material to form the pig 1 having the water retaining agent 2 dispersed in the contour part thereof. |
