Waterproof breathable polyurethane membranes and porous substrates protected therewith

• US 5,238,732 A
• Filed: 01/11/1993
• Issued: 08/24/1993
• Est. Priority Date: 07/16/1992
• Status: Expired due to Fees

• Current Assignee: BayBank Co.
• Original Assignee: Surface Coatings, Inc.
• Inventors: Krishnan, Sundaram
• Primary Examiner(s): Foelak, Morton
• Application Number:
  US08/002,640
• Time in Patent Office: 225 Days
• Field of Search: 428/260, 428/267, 428/423.5, 428/913, 521/137, 525/457, 528/28, 528/76
• US Class Current: 442/76
• CPC Class Codes: B32B 27/40 comprising polyurethanes
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: C08G 18/0852 the solvents being organic
• CPC Class Codes: C08G 18/4804 Two or more polyethers of different physical or chemical nature
• CPC Class Codes: C08G 18/61 Polysiloxanes
• CPC Class Codes: D06M 15/564 Polyureas, polyurethanes or other polymers having ureide or urethane links; Precondensation products forming them
• CPC Class Codes: D06M 15/568 Reaction products of isocyanates with polyethers
• CPC Class Codes: D06M 15/643 containing silicon in the main chain
• CPC Class Codes: D06M 17/10 Polyurethanes polyurea
• CPC Class Codes: D06N 3/14 with polyurethanes
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/31562 Next to polyamide [nylon, etc.]
• CPC Class Codes: Y10T 442/2139 Coating or impregnation specified as porous or permeable to a specific substance [e.g., water vapor, air, etc.]
• CPC Class Codes: Y10T 442/2246 Nitrogen containing

Abstract

Disclosed herein are polyurethane compositions specifically adapted to produce non-porous membranes exhibiting waterproof and water vapor transmissible characteristics. The membranes can be produced as free standing products or can be produced as coatings on porous substrates to confer similar properties to such substrates. Also disclosed are coated fabrics and fabric laminates utilizing the membranous coatings of the invention and exhibiting waterproof and water vapor transmissible characteristics. Such coated fabrics and fabric laminates find utility in the fabrication of tenting, rainwear and other garments where waterproofness, coupled with breathability, are important features.

Claims

1. A method for rendering a porous substrate waterproof and water vapor transmissible which comprises disposing over the surface of said substrate a waterproof, water vapor transmissible non-porous polyurethane membrane prepared as a reaction product of:

(a) an organic polyisocyanate;

(b) a polyalkylene ether glycol wherein the number of carbon atoms of the alkylene radical thereof is 2;

(c) at least one polyalkylene ether glycol wherein the number of carbon atoms of the alkylene radical thereof is at least 3; and

(d) an isocyanate reactive hydroxyl group-containing polydimethylsiloxane having a functionality of at least 2;

the mole ratio of the polyalkylene ether glycol of (a) to the at least one polyalkylene ether glycol of (b) being within the range of from 1.5;

0.5 to 0.5;

1.5 and the mole ratio of said isocyanate reactive polydimethylsiloxane to the total of said polyalkylene ether glycols of (b) and (c) being within the range of from 0.1;

1 to 0.3;

1.

2. The method of claim 1 wherein said membrane is continuously bonded to said substrate.

3. The method of claim 2 wherein said membrane is produced by coating of said substrate with a solution of the uncured polyurethane composition dissolved in a fugitive compatible solvent, driving off the solvent of said coating, thereby to produce an uncured non-porous membrane disposed over and bonded to said substrate, and curing the membrane

4. The method of claim 3 wherein said substrate is a fabric.

5. The method of claim 1 wherein said membrane is continuously adhered to said substrate by means of a water vapor transmissible polyurethane adhesive.

6. The method of claim 5 wherein said substrate is a fabric.

7. The method of claim 1 wherein said substrate is a fabric.