Patent US3607812A successfully refreshed from Google Patents.
US3607812A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing polyvinyl alcohol films and product
Assignee: Denka Co Ltd
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Filing: 1968-12-17
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Granted: 1971-09-21
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Expires: 1988-12-17
Abstract
Abstract A method of manufacturing a polyvinyl alcohol film insoluble in water at a temperature below 40* C. by adding 13 to 5 parts by weight of a polyhydric alcohol plasticizer to 87 to 95 parts by weight of polyvinyl alcohol resin which has a polymerization degree of from 700 to 1,500 and a hydrolysis degree of at least 97 mol percent and contains less than 0.5 percent by weight of sodium acetate, drying the mixture to reduce the moisture content to less than 2 percent by weight and finally melt extruding the mass into a film with a die heated to temperatures of from 190* to 250* C.
Inventors
- 👤 Bin Takigawa
- 👤 Akio Wakabayashi
- 👤 Tanio Hayashi
- 👤 Masanori Kasagi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:44
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; C08K; C08K5/00; C08K5/04; C08K5/05; C08K5/053; B; B29; B29C; B29C48/00; B29C48/001; B29C48/0018; B29C48/0019; B29C48/022; B29C48/03; B29C48/07; B29C48/08; B29C48/09; B29C48/10; C08J2329/00; C08J2329/02; C08J2329/04
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
22 words
A method according to claim 1 wherein the ratio of the plasticizer to the polyvinyl alcohol resin is from 7:93 to 10:90.
Claim 2
Dependent Claim
21 words
A method according to claim 1 wherein the die temperature is so controlled as to range from 210* to 220* C.
Claim 3
Dependent Claim
19 words
A method according to claim 1 wherein said melt extrusion is carried out in the form of inflation extruding.
Claim 4
Independent Claim
124 words
A method of manufacturing a polyvinyl alcohol film insoluble in water at a temperature below 40* C., which comprises mixing (a) 90 to 93 parts by weight of a polyvinyl alcohol resin having a polymerization degree of from 700 to 1,500 and a hydrolysis degree of at least 97 mol percent and containing less than 0.5 percent by weight of sodium acetate with (b) 7 to 10 parts by weight of plasticizer selected from the group consisting of ethylene glycol, triethylene glycol, polyethylene glycol, glycerine and trimethylol propane, drying the resultant mixture to reduce the moisture content to less than 2 percent by weight, and inflation extruding the dried mixture into a cylindrical film at a die temperature of from 210* to 220* C.
Claim 5
Dependent Claim
26 words
Polyvinyl alcohol film not soluble in water at temperatures below 40* C. and soluble in water at higher temperatures made by the method of claim 1.
Claim 6
Dependent Claim
10 words
A method of claim 2 wherein the plasticizer is glycerine.
Claim 7
Dependent Claim
25 words
A method of claim 1 wherein said plasticizer is selected from the group consisting of ethylene glycol, triethylene glycol, polyethylene glycol, glycerine and trimethylol propane.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |