Bonding method employing thermally stable hot melt moisture-cure polyurethane adhesive composition

• US 4,891,269 A
• Filed: 03/07/1988
• Issued: 01/02/1990
• Est. Priority Date: 01/29/1986
• Status: Expired due to Term

• Current Assignee: H.B. Fuller Licensing & Financing, Inc.
• Original Assignee: HB Fuller Company
• Inventors: Mackey, Sandra J., Bunnelle, William L., Markevka, Virginia C.
• Primary Examiner(s): Gallagher, John J.
• Application Number:
  US07/164,588
• Time in Patent Office: 666 Days
• Field of Search: 156/307.3, 156/331.4, 428/246, 428/423.1, 428/424.4, 525/125, 525/130
• US Class Current: 428/423.1
• CPC Class Codes: C08G 18/10 Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• CPC Class Codes: C08G 18/307 Atmospheric humidity
• CPC Class Codes: C08G 18/381 having bromine atoms
• CPC Class Codes: C08G 18/4841 containing oxyethylene end groups
• CPC Class Codes: C08G 18/797 containing carbodiimide and/or uretone-imine groups
• CPC Class Codes: C08L 23/00 Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C08L 31/00 Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid of hydrolysed polymers C08L29/00; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 33/00 Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 75/04 Polyurethanes
• CPC Class Codes: C09J 131/04 Homopolymers or copolymers of vinyl acetate
• CPC Class Codes: C09J 175/04 Polyurethanes
• CPC Class Codes: Y10T 428/31551 Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]
• CPC Class Codes: Y10T 428/31576 Ester monomer type [polyvinylacetate, etc.]
• CPC Class Codes: Y10T 442/3667 Composite consisting of at least two woven fabrics bonded by an interposed adhesive layer [but not two woven fabrics bonded together by an impregnation which penetrates through the thickness of at least one of the woven fabric layers]
• CPC Class Codes: Y10T 442/659 Including an additional nonwoven fabric

Abstract

A one-package thermally stable hot melt pressure-sensitive moisture-cure polyurethane composition that can be extruded at elevated temperatures to form a hot melt glue line with very high green strength that can moisture-cure to a strong urethane adhesive bond.

Claims

1. A method of joining at least two substrates, which comprises:

(a) forming an assembly comprising at least two substrates having therebetween a sufficient bonding amount of an adhesive having both hot melt and thermosetting urethane properties; and

(b) curing the adhesive;

wherein the adhesive comprises;

(i) an effective film-forming amount of thermoplastic ethylene-vinyl monomer copolymer base wherein the vinyl monomer comprises an acrylate monomer or a vinyl ester of a carboxylic acid compound;

(ii) an effective bonding amount of a liquid polyurethane prepolymer composition having a viscosity of less than 25,000 cP at 25°

C. comprising the reaction product of a polyfunctional hydroxy compound having a number of average molecular weight of at least 1,000 and a polyfunctional isocyanate compound having an isocyanate functionality of about two or more, at a ratio of hydroxyl to isocyanate of 0.1 to 0.7;

1, sufficient to form a rigid moisture cure bond;

(iii) a phenol-free polymeric tackifier composition comprising the polymerization product of aromatic monomers, aliphatic monomers, or mixtures thereof, said aromatic monomers being selected from the group consisting of an indene monomer, a styrene monomer, or a dicyclopentadiene monomer, said aliphatic monomer comprising a C₅ diene; and

(iv) about 0 to 5 wt-% of an antioxidant.

2. The method of claim 1 wherein the ethylene-vinyl monomer copolymer comprises an ethylene vinyl acetate polymer.

3. The method of claim 2 wherein the ethylene-vinyl acetate polymer has about 45 to 60 wt-% vinyl acetate.

4. The method of claim 3 wherein the ethylene-vinyl acetate copolymer has a vinyl acetate concentration of 50 to 60 wt-%, a melt index of about 2 to 90, and is present in the adhesive composition at a concentration of 15 to 35 wt-%.

5. The method of claim 1 wherein the prepolymer is the reaction product of a polyalkylene glycol and a polyfunctional aromatic isocyanate compound having an isocyanate functionality of about two or more.

6. The method of claim 5 wherein the polyalkylene glycol is an ethylene oxide capped polypropylene glycol, the polyfunctional urethane compound having an isocyanate functionality of about two or more is diphenylmethane diisocyanate, the prepolymer is present in the adhesive composition at a concentration of 25 to 50 wt-% and the prepolymer has a viscosity of about 100 to 10,000 cP at 25°

C.

7. The method of claim 1 wherein the prepolymer is present in the adhesive composition at a concentration of 30 to 50 wt-% and has a viscosity of about 2,000-8,000 cP at 25°

C.

8. The method of claim 1 wherein the polymeric tackifier comprises a phenol-free polymer made of monomers comprising a vinyl aromatic compound.

9. The method of claim 8 wherein the vinyl aromatic compound is styrene.

10. The method of claim 8 wherein the vinyl aromatic compound is alphamethyl styrene.

11. The method of claim 1 wherein each substrate is independently textile, metal, plastic, a polyester fiberglass composite, or graphite.

12. The product produced by the method of claim 1.