| 摘要 |
PURPOSE: To maintain a molding in its set shape without melting if it is kept at a freezing temperature or higher by injecting feedstook slurry into a molding die after adding and blending polyvinyl alcohol or its modified product to the feedstock slurry, and performing a repetitive cycle of cooling and heating. CONSTITUTION: PVA(polyvinyl alcohol) is added to feedstock slurry and this mixture is injected into a molding die of desired form, and then a cycle of cooling and heating(freezing and thawing cycle) is repeated once or more. That is, first the mixture is cooled(frozen) with the molding die, and a heating cycle(thawing) is performed at least, once. The feedstook slurry with added PVA is injected into the interior of the molding die of a desired form. After that, normally the molding die is subjected to external freezing and heating. The cooling is normally performed at 0 deg.C or lower, preferably at a temperature of -5 deg.C or lower. On the other hand, the heating is conducted after the cooling, and is performed normally at 4 to 60 deg.C, preferably at 10 to 30 deg.C. |
