Process for preparing cold water-soluble films from PVA by melt extrusion
AssigneeE. I. Du Pont de Nemours and Company
InventorRobert D. Wysong
Life of this patent
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Abstract
Films, 0.5-10 mils thick, which are rapidly and completely soluble in cold water, and which are suitable for use as packaging film in automatic packaging equipment, can be prepared by conventional melt extrusion processes when prepared from a novel composition consisting essentially of 5-20 parts by weight of a polyethylene glycol (having an average molecular weight in the range between 325 and 550) in 100 parts by weight of a partially hydrolyzed low molecular weight polyvinyl alcohol.
Claims13
A process for making a cold water-soluble film 0.5-10 mils thick comprising melt-extruding a composition consisting essentially of 5 to 20 parts by weight of a polyethylene glycol, having an average molecular weight in the range between 325 and 550 (based upon measurement of the hydroxyl content thereof obtained by esterification of said glycol with phthalic anhydride/pyridine), in 100 parts by weight of a low molecular weight polyvinyl alcohol which is about 85 to about 90 mol% hydrolyzed (determined by saponification) and has a viscosity in the range between about 3 and about 10 cps as measured on a 4% aqueous solution at 20.degree. C. (determined by the Hoeppler Falling Ball Method ASTM-D 1343-56, Part 8).
Dependencies are inferred from the claim text.