Waterproof breathable polyurethane membranes and porous substrates protected therewith

• US 5,239,037 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:
  US08/002,747
• Time in Patent Office: 225 Days
• Field of Search: 525/457, 528/28, 528/76, 521/137, 521/154
• US Class Current: 528/28
• 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

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 coating system for laminating fabrics and for rendering the resulting laminate waterproof and water vapor transmissible, which system comprises:

(1) a basecoat chain extended polyurethane prepolymer solute composition dissolved in a fugitive compatible solvent therefor, said solute being a block copolymer reaction product of;

(a) a polyisocyanate;

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

(c) an isocyanate reactive hydroxyl group-containing polydimethylsiloxane having a functionality of at least 2, said basecoat composition being adapted to be coated onto the surface of a fabric layer; and

(2) an adhesive chain extended polyurethane prepolymer solute composition dissolved in a fugitive compatible solvent therefor, said solute being the reaction product of (a) a polyisocyanate and (b) a polyalkylene ether glycol wherein the number of carbon atoms of the alkylene radical thereof is at least 3, said adhesive composition being adapted to be coated onto the surface of said basecoat composition coated onto the surface of said fabric layer and to adhesively receive thereon a second fabric layer applied thereto under sufficient pressure as to effectuate at least partial intermingling of said basecoat and adhesive coatings, the concentrations of said polyalkylene ether glycol of (1)(b) and (2)(b) of said basecoat and adhesive compositions being sufficient to provide an intermingled chain extended prepolymer matrix between said fabric layers wherein the mole ratio of (1)(b) to (2)(b) is within the range of from 1.5;

0.5 and 0.5;

1.5 and the concentration of said polydimethylsiloxane of (1)(c) of said basecoat composition being sufficient to provide within said matrix a mole ratio of said polydimethylsiloxane to the total of said polyalkylene ether glycols of (1)(b) and (2)(b) of from 0.1;

1 to 0.3;

1.

2. The system of claim 1 wherein each of said polyalkylene ether glycols of (1)(b) and (2)(b) has an average molecular weight of between about 450 and about 2000.

3. The system of claim 1 wherein said polydimethylsiloxane of (1)(c) has an average molecular weight of between about 800 and about 3500.

4. The system of claim 1 wherein said polyalkylene ether glycol of (1)(b) is poly(oxyethylene) glycol.

5. The system of claim 1 wherein each of said polyalkylene ether glycols of (1)(b) and (2)(b) has a functionality of 2.