Polyurethane adhesive film
A thin self-supporting adhesive film is claimed that includes a first polyurethane and a solid surface-deactivated isocyanate.
1. A self-supporting adhesive film comprising:
a solid surface-deactivated isocyanate; and
greater than 70% by weight, based on the weight of the adhesive film, of a isocyanate reactive polyurethane component having a weight average molecular weight (Mw) of no greater than about 90,000 g/mol and an enthalpy of fusion of at least about 25 J/g, the polyurethane component comprising
a first polyurethane having a weight average molecular weight of no greater than about 90,000 g/mol and an enthalpy of fusion of at least about 25 J/g, and
a second polyurethane different from the first polyurethane and having a weight average molecular weight of no greater than about 90,000 g/mol and an enthalpy of fusion of at least about 25 J/g, the second polyurethane differing from the first polyurethane based on a property selected from the group consisting of composition, molecular weight, enthalpy of fusion, melting peak, and combinations thereof.
2. The self-supporting adhesive film of claim 1 , wherein the self-supporting adhesive film is obtained from an aqueous composition.
3. The self-supporting adhesive film of claim 1 , wherein said solid surface-deactivated isocyanate is derived from toluene diisocyanate.
4. The self-supporting adhesive film of claim 1 , wherein a film of said first polyurethane has an enthalpy of fusion of at least about 35 J/g.
5. The self-supporting adhesive film of claim 1 , wherein the first polyurethane is derived from a polyester derived from a polyol selected from the group consisting of 1,4-butane diol and 1,6-hexane diol.
6. The self-supporting adhesive film of claim 1 , wherein the first polyurethane is derived from:
a polyester polyol derived from adipic acid, 1,6-hexane diol, and neopentyl glycol; and
an aliphatic isocyanate.
7. The self-supporting adhesive film of claim 1 , wherein said film exhibits a bond strength of at least about 20 N/2.5 cm when tested according to the Bond Test Method at a Bond Line Temperature of about 64° C.
8. The self-supporting adhesive film of claim 1 , wherein
the first polyurethane has an enthalpy of fusion of at least 35 J/g, and
the second polyurethane has an enthalpy of fusion of at least 35 J/g.
9. The self-supporting adhesive film of claim 1 further comprising an additional polymer, the additional polymer being different from the first polyurethane and the second polyurethane.
10. The self-supporting adhesive film of claim 9 wherein the sum of the percent by weight of the solid surface-deactivated isocyanate, the percent by weight of the polyurethane component, and the percent by weight of the additional polymer amounts to at least about 95% by weight of the self-supporting adhesive film.
11. A composite structure comprising:
a first layer; and
a second layer,
at least one of said first layer and said second layer comprising the self-supporting adhesive film of claim 1 .
12. The composite structure of claim 11 , wherein
the first polyurethane has an enthalpy of fusion of at least 35 J/g, and
the second polyurethane has an enthalpy of fusion of at least 35 J/g.
13. A composite structure comprising:
the self-supporting adhesive film of claim 1 ,
a rigid layer, and
a flexible layer, the rigid layer being bonded to the flexible layer through the self-supporting adhesive film.
14. The composite structure of claim 13 , wherein the rigid layer comprises at least one of metal, metal composite, plastic, plastic composite, wood, and wood-composite.
15. The composite structure of claim 13 , wherein the flexible layer comprises at least one of fabric, foil, film and paper.
16. The composite structure of claim 13 , wherein the rigid layer is nylon and the flexible layer is a soft fabric comprising microfibers.
17. The composite structure of claim 13 , wherein
the first polyurethane has an enthalpy of fusion of at least 35 J/g, and
the second polyurethane has an enthalpy of fusion of at least 35 J/g.
18. A method of making a composite comprising:
contacting a flexible layer with a first major surface of the self-supporting adhesive film of claim 1 ;
applying heat to the film before or after the film is applied to the flexible substrate;
contacting a rigid layer with a second major surface of the self-supporting adhesive film such that the second major surface is in direct contact with the rigid layer to form a composite; and
applying heat and pressure to the composite.
19. A self-supporting adhesive film obtained from an aqueous composition, said aqueous composition comprising:
a solid surface-deactivated isocyanate; and
an isocyanate reactive polyurethane dispersion, the dried film of which has an enthalpy of fusion of at least about 25 J/g, the isocyanate reactive polyurethane dispersion comprising
a first polyurethane having an enthalpy of fusion of at least about 25 J/g, and
a second polyurethane different from the first polyurethane and having an enthalpy of fusion of at least about 25 J/g, the second polyurethane differing from the first polyurethane based on a property selected from the group consisting of composition, molecular weight, enthalpy of fusion, melting peak, and combinations thereof,
the self-supporting adhesive film having a thickness of from about 1 mil to about 8 mils.
20. The self-supporting adhesive film of claim 19 , wherein said film has a thickness of from about 2 mils to about 6 mils.
21. The self-supporting adhesive film of claim 19 wherein the solid surface-deactivated isocyanate is derived from an aromatic isocyanate.
22. The self-supporting adhesive film of claim 19 further comprising an additional polymer, the additional polymer being different from the first polyurethane and the second polyurethane.
23. A composite structure comprising:
the self-supporting adhesive film of claim 2 ,
a first rigid layer, and a
second rigid layer,
the rigid layers being bonded to each other through the self-supporting adhesive film.
24. A composite structure comprising:
the self-supporting adhesive film of claim 2 ,
a rigid layer, and
a flexible layer,
the rigid layer being bonded to the flexible layer through the self-supporting adhesive film.
25. A self-supporting adhesive film comprising:
a solid surface-deactivated isocyanate; and
greater than 70% by weight, based on the weight of the adhesive film, of a isocyanate reactive polyurethane component having a weight average molecular weight (Mw) of no greater than about 90,000 g/mol and an enthalpy of fusion of at least about 25 J/g, the polyurethane component comprising
a first polyurethane derived from a polyester polyol, the first polyurethane having a weight average molecular weight of no greater than about 90,000 g/mol and an enthalpy of fusion of at least about 25 J/g, and
a second polyurethane derived from a polyester polyol, the second polyurethane being different from the first polyester polyurethane and having a weight average molecular weight of no greater than about 90,000 g/mol and an enthalpy of fusion of at least about 25 J/g, the second polyurethane differing from the first polyurethane based on a property selected from the group consisting of composition, molecular weight, enthalpy of fusion, melting peak, and combinations thereof.
26. The self-supporting adhesive film of claim 25 , wherein
the first polyurethane has an enthalpy of fusion of at least 35 J/g, and
the second polyurethane has an enthalpy of fusion of at least 35 J/g.