Transparent polyurethane compositions

• US 6,458,875 B1
• Filed: 06/01/2000
• Issued: 10/01/2002
• Est. Priority Date: 01/30/1998
• Status: Expired due to Term

• Current Assignee: GKN Aerospace Transparency Systems, Inc. (Melrose Industries Plc)
• Original Assignee: Pilkington Aerospace, Inc. (Melrose Industries Plc)
• Inventors: Sandlin, Stephen L., Moncur, Marlowe V., Hoo, Lin Hin
• Primary Examiner(s): NILAND, PATRICK DENNIS
• Application Number:
  US09/585,690
• Time in Patent Office: 852 Days
• Field of Search: 524/589, 524/590, 524/168
• US Class Current: 524/168
• CPC Class Codes: C08G 18/4854 Polyethers containing oxyalkylene groups having four carbon atoms in the alkylene group
• CPC Class Codes: C08G 18/664 with compounds of group C08G18/3203
• CPC Class Codes: C08G 18/758 containing two or more cycloaliphatic rings
• CPC Class Codes: C08J 2475/00 Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
• CPC Class Codes: C08J 7/0423 with at least one layer of inorganic material and at least one layer of a composition containing a polymer binder
• CPC Class Codes: C08J 7/0427 with only one layer of a composition containing a polymer binder with more layers C08J7/042
• CPC Class Codes: C08J 7/043 Improving the adhesiveness of the coatings per se, e.g. forming primers adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50
• CPC Class Codes: C08J 7/044 Forming conductive coatings; Forming coatings having anti-static properties
• CPC Class Codes: C08J 7/046 Forming abrasion-resistant coatings; Forming surface-hardening coatings
• CPC Class Codes: C09D 175/06 from polyesters
• CPC Class Codes: Y10T 428/31507 Of polycarbonate
• CPC Class Codes: Y10T 428/31551 Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]
• CPC Class Codes: Y10T 428/31565 Next to polyester [polyethylene terephthalate, etc.]
• CPC Class Codes: Y10T 428/31573 Next to addition polymer of ethylenically unsaturated monomer
• CPC Class Codes: Y10T 428/31576 Ester monomer type [polyvinylacetate, etc.]
• CPC Class Codes: Y10T 428/31583 Nitrile monomer type [polyacrylonitrile, etc.]
• CPC Class Codes: Y10T 428/31601 Quartz or glass

Abstract

The present invention is embodied in a polyurethane composition suitable for coating, casting or laminating, which incorporates a prescribed additive selected to increase the composition'"'"'s electrical conductivity without adversely affecting the composition'"'"'s transparency and percent haze and without adversely affecting its adhesion to an underlying substrate or its environmental durability, especially with regard to humidity resistance. The prescribed additive is an ionizable metal salt of a perfluoroalkylsulfonimide, in a weight percent of 0.5 to 5.0, with the metal being an alkali metal and the preferred perfluoroalkylsulfonimide being trifluoromethanesulfonimide. The most preferred salt is lithium trifluoromethanesulfonimide. The preferred polyurethanes include both aliphatic polyetherurethanes and aliphatic polyesterurethanes. Use of the additive enhances the composition'"'"'s electrical conductivity by at least about two orders of magnitude, thereby minimizing the risk of a static charge building to a point where a shock hazard is created or the polyurethane coating or laminate is damaged by a rapid discharge of electrical current. The composition is particularly useful in an aircraft window or transparency, where it can be used as a coating or laminated film overlaying a transparent conductive coating.

Claims

1. A transparent polyurethane composition suitable for coating or casting, wherein the composition consists essentially of polyurethane and an ionizable salt of a perfluoroalkysulfonimide, and wherein the ionizable salt of the perfluoroalkysulfonimide is present in an amount 0.5 to 5.0 weight percent of the total amount of polyurethane and ionizable salt of the perfluoroalkysulfonimide in the composition.

2. A transparent polyurethane composition as defined in claim 1, wherein the composition is an aliphatic polyesterurethane.

3. A transparent polyurethane composition as defined in claim 1, wherein the composition is an aliphatic polyetherurethane.

4. A transparent polyurethane composition as defined in claim 1, wherein the metal is an alkali metal and the perfluoroalkylsulfonimide is trifluoromethanesulfonimide.

5. A transparent polyurethane composition as defined in claim 4, wherein the ionizable salt is lithium trifluoromethanesulfonimide.

6. A transparent polyurethane composition as defined in claim 5, wherein the weight percent of lithium trifluoromethanesulfonimide is in the range of 1.0 to 3.0.

7. A transparent polyurethane composition as defined in claim 1, wherein the ionizable salt is incorporated at a concentration effective to reduce the composition'"'"'s volume resistivity, after curing, by more than about two orders of magnitude over what it would be in the absence of the ionizable salt.