| 摘要 |
PURPOSE:To produce the titled gel which is rich in elasticity and flexibility and is not deformed, by placing an aq. soln. contg. polyvinyl alcohol and a water- soluble org. compd. in a mold for helmet molding repeating a freeze-thaw operation and drying the aq. soln. CONSTITUTION:An aq. soln. (or aq. suspension) contg. 10-25wt% polyvinyl alcohol (having a degree of saponification of 98mol% or above and an average degree of polymn. of 700-1,100) and 5-40wt% water-soluble org. compd. (an antifreezing agent such as propylene glycol or D-sorbitol) is placed in a mold for helmet molding (having a form capable of enclosing the whole area including the hair, eyebrows, etc.), while keeping the temp. of the aq. soln. at 40 deg.C or above. The aq. soln. is cooled to -10 deg.C or lower to freeze it and the temp. is then elevated to thaw it. This freeze-thaw operation is repeated at least twice. The aq. soln. is then air-dried or dried by heating at 60 deg.C or below to dehydrate it at a dehydration rate of 8% or above, thus obtaining a heat insulating gel for the head. |
