Waterproof breathable polyurethane membranes and porous substrates protected therewith

• US 5,208,313 A
• Filed: 07/16/1992
• Issued: 05/04/1993
• 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:
  US07/914,871
• Time in Patent Office: 292 Days
• Field of Search: 528/28, 521/154
• US Class Current: 528/28
• CPC Class Codes: B32B 2250/20 All layers being fibrous or filamentary
• CPC Class Codes: B32B 2255/02 on fibrous or filamentary layer
• CPC Class Codes: B32B 2262/0292 Polyurethane fibres
• CPC Class Codes: B32B 2305/026 Porous
• CPC Class Codes: B32B 2307/724 Permeability to gases, adsorption
• CPC Class Codes: B32B 2307/7265 Non-permeable
• CPC Class Codes: B32B 2375/00 Polyureas; Polyurethanes
• CPC Class Codes: B32B 2437/00 Clothing anti-ballistic clothing B32B2571/02
• 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: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• 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 rendering porous substrates waterproof and water vapor transmissible, which system comprises a basecoat chain extended polyurethane prepolymer solute composition dissolved in a fugitive compatible solvent therefor, said solute being the reaction product of:

(a) a 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 polyaklylene 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 coating system of claim 1 wherein the mole ratio of polyalkylene ether glycol of (a) to the at least one polyalkylene ether glycol of (b) is about 1:

1.

3. The coating system of claim 1 wherein said basecoat solute composition comprises a mixture of chain extended polyurethane prepolymers, one of said chain extended polyurethane prepolymers comprising a block copolymer reaction product of said polyisocyanate of (a), said polyalkylene ether glycol of (b) and said isocyanate reactive polydimethylsiloxane of (d) and the other of said chain extended polyurethane prepolymers comprising the reaction product of said polyisocyanate of (a) and said at least one polyalkylene ether glycol of (c).

4. The coating system of claim 1 including a topcoat chain extended polyurethane prepolymer solute dissolved in a fugitive compatible solvent therefor, said chain extended prepolymer topcoat being adapted to be applied to the surface of said basecoat and to form a water vapor transmissible protective coating thereon upon curing thereof.

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

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

7. The coating system of claim 1 wherein said isocyanate reactive hydroxyl group containing polydimethylsiloxane of (d) has an average molecular weight of between about 800 and about 3500.