Claims
- 1. A water soluble polyvinyl alcohol film formed from a copolymer consisting essentially of vinyl alcohol units, vinyl ester units and copolymerization units containing the 2-pyrrolidone ring, wherein the degree of hydrolysis of said polyvinyl alcohol is 65-98% and the content of said copolymerization units containing the 2-pyrrolidone ring is 1 to 20 mol%.
- 2. The water soluble film of claim 1, wherein the content of copolymerization units containing the 2-pyrrolidone ring is 2 to 12 mol%.
- 3. The water soluble film of claim 2, wherein the content of said copolymerization units containing the 2-pyrrolidone is 2-8 mol%.
- 4. The water soluble film of claim 1, wherein said 2-pyrrolidone ring has a formula I: ##STR2## wherein R.sub.1 to R.sub.6 each represent hydrogen or an alkyl group.
- 5. The water soluble film of claim 4, wherein substituents R.sub.1 -R.sub.6 are each hydrogen.
- 6. The water soluble film of claim 1, wherein the degree of hydrolysis of said polyvinyl alcohol is 65 to 95 mol%.
- 7. The water soluble film of claim 1, wherein the content, X (mol%) of said copolymerization units containing the 2-pyrrolidone ring and the degree of hydrolysis Y (mol%), of said polyvinyl alcohol satisfy the following relationships:
- 2.ltoreq.X.ltoreq.8
- 65.ltoreq.Y.ltoreq.95
- 76-X.ltoreq.Y.ltoreq.80+3.6 X
- 8. A water soluble film comprising the polyvinyl alcohol defined in claim 1 and a sugar alcohol having b 4 to 6 carbon atoms.
- 9. A process for preparing a water soluble film, which comprises:
- melt forming, in the substantial absence of water,
- the polyvinyl alcohol defined in claim 1.
- 10. The process of claim 9, wherein the melt flow index of said polyvinyl alcohol, as determined from the amount melt-extruded through a dye at 190.degree. C. and under a load of 2.16 kg, is 0.1 to 100 g/10 min.
Priority Claims (1)
Number |
Date |
Country |
Kind |
63-189148 |
Jul 1988 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 07/384,794, filed on July 25, 1989, now abandoned.
US Referenced Citations (9)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0020131 |
Jul 1970 |
JPX |
0249633 |
Dec 1969 |
SUX |
Continuations (1)
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Number |
Date |
Country |
Parent |
384794 |
Jul 1989 |
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