Reactive hot melt adhesives with improved adhesion
The present specification relates to moisture reactive hot melt adhesive compositions comprising a silane reactive plasticizer and the reaction product of (i) a semi-crystalline polyol and (ii) a polyisocyanate and (iii) an aminosilane; the production of such adhesives; and the use of such adhesives.
1. A moisture curable composition comprising:
60 to 95 weight percent of a reaction product of (i) a semi-crystalline polyol and (ii) a polyisocyanate and (iii) a primary aminosilane; and
5 to 35 weight percent of a silane reactive plasticizer.
2. The moisture curable composition of claim 1 wherein the equivalent ratio of polyisocyanate (ii) to semi-crystalline polyol (i) is >1.4.
3. The moisture curable composition of claim 1 wherein the ratio of equivalents of primary aminosilane (iii) to [equivalents of polyisocyanate (ii)−equivalents of semi-crystalline polyol (i)] is about 1 or greater.
4. The moisture curable composition of claim 1 being free of water and solvent.
5. The moisture curable composition of claim 1 wherein the equivalent ratio of polyisocyanate (ii) to semi-crystalline polyol (i) is >1.
6. The moisture curable composition of claim 1 further comprising adhesion promoter.
7. The moisture curable composition of claim 1 further comprising an aminosilane adhesion promoter.
8. The moisture curable composition of claim 1 wherein the equivalent ratio of isocyanate to polyol is greater than 1 to 1.
9. The moisture curable composition of claim 1 wherein the equivalent ratio of isocyanate to polyol is greater than 1.6 to 1.
10. The moisture curable composition of claim 1 further comprising one or more of a tackifier; an acrylic polymer; and a catalyst.
11. The moisture curable composition of claim 1 wherein the semi-crystalline polyol is a semi-crystalline polyester polyol and a weight ratio of polyester polyol to silane reactive plasticizer is greater than 1 part polyester polyol to 1 part silane reactive plasticizer.
12. The moisture curable composition of claim 1 wherein the semi-crystalline polyol is a semi-crystalline polyester polyol and a weight ratio of polyester polyol to silane reactive plasticizer is greater than 1.2 parts polyester polyol to 1 part silane reactive plasticizer.
13. The moisture curable composition of claim 1 wherein the silane reactive plasticizer comprises at least one silyl group with a formula of
R-[A-Si(C x H 2x+1 ) n (OH) 3−n ] z
or
R-[A-Si(C x H 2x+1 ) n (OC y H 2y+1 ) 3−n ] z
wherein
R is a polymer backbone;
A is a linkage to the polymer backbone;
x is 1 to 12;
y is 1 to 12; and
n is 0, 1 or 2
z is 1 or 2.
14. The moisture curable composition of claim 13 , wherein polymer backbone R is selected from silicone, polyether, polycarbonate, polyisobutylene, ethylene vinyl acetate and polyacrylate.
15. The moisture curable composition of claim 1 being free of isocyanate monomer.
16. The moisture curable composition of claim 1 comprising about 70 to about 90 weight percent reaction product and about 10 to about 30 weight percent silane reactive plasticizer.
17. A method of applying a moisture curable composition comprising:
providing the moisture curable composition of claim 1 in solid form at room temperature;
heating the moisture curable composition to a molten state at the point of use;
applying the molten moisture curable composition to a first substrate;
bringing a second substrate in contact with the molten moisture curable composition applied to the first substrate;
cooling the applied molten moisture curable composition to a solid state;
subjecting the cooled composition to conditions sufficient to irreversibly cure the cooled composition to form a bond between the first and second substrates.
18. An article of manufacture comprising the moisture curable composition of claim 1 .
19. A moisture curable hot melt adhesive comprising the moisture curable composition of claim 1 .
20. The moisture curable composition of claim 1 in cured form.
21. The moisture curable composition of claim 1 , wherein the silane reactive plasticizer is a liquid at room temperature and polymer backbone R is selected from polyether, polycarbonate, polyisobutylene, and polyacrylate.
22. The moisture curable composition of claim 1 wherein the reaction product comprises a plurality of terminal silyl groups each independently having a formula of:
—Si(C x H 2x+1 ) n (OC y H 2y+1 ) 3−n
wherein
n=0, 1 or 2;
x and y are, independently a number from 1 to 12.