Claims
- 1. An improvement in a method for preparing cold water-soluble films wherein a polymeric composition in the form of powder, granules or pellets is melted, extruded through a slit or annulus, quenched by air and then shaped to form a thin film by drawing down, blowing or both, said polymeric composition consisting essentially of (i) a resin mixture of 40 to 55 parts by weight of a low molecular weight polyvinyl alcohol containing acyl groups having 1 to 4 carbon atoms, and having a viscosity in the range between 3 and 10 cps and a degree of hydrolysis in the range between 85 and 90 mol percent; 25 to 60 parts by weight of a medium molecular weight polyvinyl alcohol containing acyl groups having 1 to 4 carbon atoms, and having a viscosity in the range between 10 and 35 cps and a degree of hydrolysis in the range between 85 and 90 mol percent; and 0 to 20 parts by weight of a copolymer made up of 90 to 98 weight percent polymerized vinyl alcohol units and 10 to 2 weight percent of polymerized ester units which in monomeric form have the formula: ##STR5## wherein A is H or --CH.sub.3 ;
- A' is H or --COO Alkyl;
- R is H, --CH.sub.3 or ##STR6## provided that when R is ##STR7## both A and A' are H; R' is H or --CH.sub.3 ; and
- Alkyl contains 1 to 4 carbon;
- which copolymer has a viscosity in the range between 10 and 60 cps and a degree of hydrolysis in the range between 95 and 100 mol percent; and (ii) as a plasticizer, 10 to 30 parts by weight of a polyethylene glycol per 100 parts by weight of said resin mixture, said polyethylene glycol having an average molecular weight in the range between 285 and 420; for each of said polymers, the viscosity being determined by the Hoeppler Falling Ball Method ASTM-D 1343-56, Part 8 and the degree of hydrolysis being determined by saponification.
- 2. The method of claim 1 wherein said resin mixture consists essentially of 40 to 55 parts by weight of said low molecular weight polyvinyl alcohol, 25 to 50 parts by weight of said medium molecular weight polyvinyl alcohol, and 10 to 20 parts by weight of said copolymer.
- 3. The method of claim 2 wherein said plasticizer is present in an amount in the range between 15 and 25 parts by weight thereof per 100 parts by weight of said resin mixture.
- 4. The method of claim 1 wherein said resin mixture consists essentially of 40 to 50 parts by weight of said low molecular weight polyvinyl alcohol, 30 to 45 parts by weight of said medium molecular weight polyvinyl alcohol, and 15 to 20 parts by weight of said copolymer.
- 5. The method of claim 4 wherein said plasticizer is present in an amount in the range between 20 and 25 parts by weight thereof per 100 parts by weight of said resin mixture.
- 6. The method of any one of claims 1 through 5 wherein said polyethylene glycol has an average molecular weight in the range between 380 and 420.
- 7. The method of claim 1 wherein a maximum of 5 parts by weight of an adjuvant per 100 parts by weight of said vinyl alcohol polymer component is added to the polymeric composition; said adjuvant being selected from antioxidants, release agents, antiblock agents, surfactants, dispersants, and slip agents.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a division of U.S. patent application Ser. No. 813,961, filed July 11, 1977, now U.S. Pat. No. 4,119,604, which in turn is a continuation-in-part of U.S. patent application Ser. No. 715,237, filed Aug. 18, 1976, now abandoned.
US Referenced Citations (8)
Foreign Referenced Citations (3)
Number |
Date |
Country |
1201957 |
Jan 1960 |
FRX |
44-28588 |
Nov 1969 |
JPX |
1330745 |
Sep 1973 |
GBX |
Divisions (1)
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Number |
Date |
Country |
Parent |
813961 |
Jul 1977 |
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Continuation in Parts (1)
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Number |
Date |
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Parent |
715237 |
Aug 1976 |
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