| 摘要 |
Gel for use as a cooling medium is prepd. by (i) casting into a mould having desired shape and dimensions, an aq. soln. or suspension contg. polyvinyl alcohol (PVA) having a degree of hydrolysis of not less than 95 mole % and a viscosity ave. mol. wt. (Mr) of not less than 1500; (ii) cooling the cast soln. to a temp. of not higher than -6 deg.C; and (iii) dehydrating the cooled mass in vacuo, without thawing, until the dehydration rate reaches not less than 5wt.%. Pref. the aq. suspension also contains a laminate structure clay mineral including a fundamental module of a tri-strata (2:1 type) composite layer, the amt. of clay mineral being not more than 5 times the wt. of PVA. The clay mineral is pref. montmorillonite, vermiculite, illite, pyrophyllite or talc. The obtd. gel is highly elastic, free of unpleasant odour, resistant to disintegration (even in the presence of a freezing point depressing agent such as ethylene glycol), provides a comfortable touch (like human skin), is insoluble in water, and can absorb a high water content. It can be moulded to desired shape, or it can be moulded into a block and then cut to desired shape. |
