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EP0107055A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Artificial organs or membranes for medical use
Assignee: Eneos Corp
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Filing: 1983-09-23
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Granted: —
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Expires: 2003-09-23
Abstract
Abstract @ A process for increasing the mechanical strength of a hydrogel is provided. An aqueous solution containing 6 wt% or more of polyvinyl alcohol having a degree of hydrolysis of not less than 95 mol% and an average polymerization degree of not less than 700 is subjected to a freezing step followed by a thawing step. Then, the mass thus obtained is further subjected to at least one additional cyclic processing step including the freezing and thawing steps. The product hydrogel is hard or not too soft and not swollen in water.
Inventors
- 👤 Masao Nambu
- 👤 Tatsuo Kinoshita
- 👤 Mineo Watase
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 13:59
CPC Classifications
C; C08; C08L; C08L29/00; C08L29/02; C08L29/04; A; A61; A61K; A61K47/00; A61K47/30; A61K47/32; A61L; A61L27/00; A61L27/14; A61L27/16; A61L33/00; A61L33/0005; A61L33/0011; B; B01; B01J; B01J13/00; B01J13/0052; B01J13/0065; Y; Y10; Y10S; Y10S264/00; Y10S264/60; Y10S516/00; Y10S516/924; Y10S516/926; Y10S623/00; Y10S623/901; Y10S623/92
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
107 words
A process for increasing the mechanical strength of a hydrogel wherein an aqueous solution of polyvinyl alcohol is frozen followed by thawing, characterized by a freezing step in which an aqueous solution containing 6 wt% or more of a polyvinyl alcohol having a degree of hydrolysis of not less than 95 mol% and an average polymerization degree of not less than 700 is frozen at a temperature of higher than -3°C to obtain a frozen mass, a thawing step in which said frozen mass is thawed at a temperature not higher than 55°C, and at least one additional cyclic processing step including said freezing and thawing steps.
Claim 2
Dependent Claim
107 words
A process for increasing the mechanical strength of a hydrogel wherein an aqueous solution of polyvinyl alcohol is frozen followed by thawing, characterized by a freezing step in which an aqueous solution containing 6 wt% or more of a polyvinyl alcohol having a degree of hydrolysis of not less than 95 mol% and an average polymerization degree of not less than 700 is frozen at a temperature of higher than -3°C to obtain a frozen mass, a thawing step in which said frozen mass is thawed at a temperature not higher than 55°C, and at least one additional cyclic processing step including said freezing and thawing steps.
Claim 3
Dependent Claim
42 words
The process according to claim 1, further comprising a step of pouring said aqueous solution of said polyvinyl. alcohol into a container or mold and sealingly closing said container or mold prior to subjecting it to said freezing and said thawing steps.
Claim 4
Dependent Claim
32 words
The process according to either of the claims 1 or 2, wherein said aqueous solution of said polyvinyl alcohol is subjected to said additional cyclic processing step for 1 to 9 times.
Claim 5
Dependent Claim
31 words
The process according to any of the claims 1 to 3, wherein the cooling rate in said freezing step is controlled to be in the range of from 0.1°C/min. to 7°C/min.
Claim 6
Dependent Claim
30 words
The process according to any of the claims 1 to 3, wherein the cooling rate at said freezing step is controlled to be in the range of from 7°C/min.to 50°C/min.
Claim 7
Dependent Claim
32 words
The process according to any of the claims 1 to 5, wherein the rate of thawing at said thawing step is controlled to be in the range of from 1°C/min. to 3°C/min.
Claim 8
Dependent Claim
32 words
The process according to any of the claims 1 to 5, wherein the rate of thawing at said thawing step is controlled to be in the range of from 3°C/min. to 5O°C/min.
Claim 9
Dependent Claim
63 words
The process according to any of the claims 1 to 7, wherein said aqueous solution of said polyvinyl alcohol contains an inorganic substance and/or an organic substance which does not hinder gelation of said polyvinyl alcohol, preferably one or more selected from the group consisting of activated char, zeolite, heparin, alcohols, enzymes, microorganisms, saccharose, polysaccharides, proteins, medicines, agricultural chemicals, fertilizers and mixtures thereof.
Claim 10
Dependent Claim
16 words
The process according to claim 8, wherein said aqueous solution of said polyvinyl alcohol contains heparin.
Claim 11
Dependent Claim
33 words
The process according to any of the claims 1 to 9, further comprising a step of dipping said hydrogel into a polyhydric alcohol after it is subjected to said additional cyclic processing step.
Claim 12
Dependent Claim
26 words
The use of a hydrogel according to any of the claims 1 to 11 as an artificial organ preferably in the form of generally hollow pipe.
References Cited (Backward Citations)
No citation records indexed.
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