GAMMA RAY STERILIZATION PROCESS FOR POLYVINYL ALCOHOL GEL.

摘要

The polyvinyl alcohol hydrogel is obtd. by repeating 2-8 times a cycle of freezing and thawing polyvinyl alcohol aq. soln. or by partially dehydrating in vacuo a frozen polyvinyl alcohol aq. soln. until achieving a wt. redn. of 3% or more. The obtd. polyvinyl alcohol hydrogel is sterilised with a gamma-ray dose specified to be between 3 and 7 Mrad. This dose reduces the formation of soluble decomposition products to 0.0095% or less. A polyvinyl alcohol having a saponification of 95 mol.% or more is used to obtain the hydrogel. The freeze-thaw cycle ic carried out after injecting the polyvinyl alcohol soln. into a moulding shape. Partial dhydration is carried out in a bag which seals out oxygen or in a container evacuated or filled with an inert gas. The hydrated hydrogel is specified to be between 3 and 30% of the total. The moulding hydrogel can be used to wrap or cover medical materials. In this case the remaining water is exchanged with a physiological saline soln.