Thermally stable hot melt moisture-cure polyurethane adhesive composition

• US 4,775,719 A
• Filed: 01/29/1986
• Issued: 10/04/1988
• 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: Bunnelle, William L., Markevka, Virginia C., Mackey, Sandra J.
• Primary Examiner(s): Bleutge, John C.
• Assistant Examiner(s): Carrillo, A.
• Application Number:
  US06/823,608
• Time in Patent Office: 979 Days
• Field of Search: 525/125, 525/130, 525/131
• US Class Current: 525/125
• 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 hot melt thermosetting urethane adhesive composition having thermal stability that can be extruded as a hot melt adhesive to form an initially high green strength hot melt bond and can moisture cure to a rigid moisture cure polyurethane bond, which comprises:

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

(b) an effective 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 average molecular weight of at least 1,000 and a polyfunctional isocyanate compound having an isocyanate functionality of about 2 or more at a ratio of hydroxyl groups to isocyanate groups of 0.1 to 0.7;

1, sufficient to form a rigid moisture-cure bond;

(c) a phenol-free, aromatic or aliphatic-aromatic polymer tackifier comprising a monomer selected from the group consisting of a C_4-6 diene, a styrenic monomer, an indene monomer, dicyclopentadiene, and mixtures thereof; and

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

2. The composition of claim 1 wherein the ethylene-vinyl monomer copolymer comprises an ethylene vinyl acetate copolymer having an ethylene content of about 10 to 55 wt-%.

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

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

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

6. The composition of claim 5 wherein the polyalkylene glycol is an alkylene oxide capped polypropylene glycol, the aromatic polyfunctional isocyanate compound having an isocyanate functionality of about 2 or more is diphenyl methane diisocyanate, the prepolymers are present in the adhesive composition at a concentration of 25 to 65 wt-% and the prepolymer has a viscosity of about 100 to 10,000 cP at 25°

C.

7. The composition of claim 6 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 composition of claim 1 wherein the tackifier is a styrenic copolymer comprising one or more styrenic monomers selected from the group consisting of styrene, alpha-methylstyrene, vinyl toluene, methoxystyrene, tertiary butyl styrene, and chlorostyrene.

9. The composition of claim 1 wherein the tackifier is a styrene homopolymer, an alpha-methylstyrene homopolymer, or a styrenic copolymer comprising one or more styrenic monomers selected from the group consisting of styrene and alpha-methylstyrene and one or more aliphatic C_4-6 monomers with conjugated diunsaturation.

10. An adhesive having both hot melt and thermosetting urethane adhesive properties which comprises:

(a) about 10 to 50 wt-% of an ethylene vinyl acetate copolymer having a melt index of 2-90 and a vinyl acetate content of greater than 50 wt-%;

(b) about 20 to 60 wt-% of polyurethane prepolymer comprising the reaction product of a polypropylenediol and diphenyl methane diisocyanate at a ratio of hydroxyl groups to isocyanate groups of about 0.2-0.5;

1, having a viscosity of less than 10,000 cP at 25°

C.;

(c) about 10 to 60 wt-% of a polymeric tackifying resin comprising a styrenic polymer compound selected from the group consisting of polystyrene and poly-alpha-methylstyrene; and

(d) about 10 to 60 wt-% of an antioxidant.

11. The adhesive of claim 10 wherein the viscosity of the prepolymer is 2,000-6,000 cP at 25°

C.