Claims
- 1. A biaxially oriented, heat set linear polyester film with high water vapor permeability, wherein the polyester is comprised of a reaction product of (1) a glycol diester of a dicarboxylic acid, (2) a high molecular weight polyethylene glycol, and (3) an alkali metal salt of a sulfonic acid-substituted dicarboxylic acid ester.
- 2. The polyester film of claim 1 wherein said glycol diester (1) is bis-2-hydroxyethyl terephthalate.
- 3. The polyester film of claim 1 wherein said polyethylene glycol (2) has a molecular weight of 600 to 20,000.
- 4. The polyester film of claim 1 wherein said polyethylene glycol (2) has a molecular weight of 2000 to 8000.
- 5. The polyester film of claim 1 wherein said alkali metal salt of a sulfonic acid-substituted dicarboxylic acid ester (3) is selected from the group consisting of an alkali-3,5-dicarbomethoxy benzene sulfonic acid, an alkali-1,2-dicarbomethoxy-4-benzene sulfonic acid, and an alkali-3,7-dicarbomethoxy naphthalene-1-sulfonic acid.
- 6. The polyester film of claim 1 wherein said polyethylene glycol (2) is used in an amount of 2-12%, and said alkali metal salt of a sulfonic acid-substituted dicarboxylic acid ester (3) is used in an amount of 2-8%, the percentages being in % by weight of the reaction product.
- 7. The polyester film of claim 2 wherein said polyethylene glycol (2) has a molecular weight of about 3500 and is used in an amount of about 4-10%, and said alkali metal salt of a sulfonic acid-substituted dicarboxylic acid ester is sodium-3,5-dicarbomethoxy benzene sulfonate and is used in an amount of about 3-6%, the percentage being in % by weight of the reaction product.
- 8. A process for preparing a polyester film which comprises synthesizing a polyester of (1) a glycol diester of a dicarboxylic acid, (2) a high molecular weight polyethylene glycol, and (3) an alkali metal salt of a sulfonic acid-substituted dicarboxylic acid ester, casting the polyester into film, and biaxially stretching and heat setting said film to achieve dimensional stability and a permeability to water vapor of about 160-1100 IPV/mil as measured by ASTM Standard Procedure No. F-372-73.
- 9. The process of claim 8 wherein (1) is bis-2-hydroxyethyl terephthalate, (2) is polyethylene glycol with a molecular weight of about 3500, and (3) is sodium-3,5-dicarbomethoxy benzene sulfonate.
- 10. The process of either claim 8 or 9 comprising the further step of coating the biaxially stretched and heat set film with at least one photographic silver halide emulsion.
- 11. The process of either claim 8, 9 or 10 wherein the polyester film contains carbon black.
CROSS-REFERENCE TO RELATED APPLICATION
This is a continuation-in-part of application Ser. No. 788,780, filed Apr. 19, 1977 now abandoned.
US Referenced Citations (8)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
788780 |
Apr 1977 |
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