Solvent free liquid moisture curable polyurethane compositions with long open times and fast cure rates
Disclosed is a liquid, solvent free, moisture curable polyurethane adhesive composition comprising the reaction products of at least one polyoxypropylene polyol having a hydroxyl functionality of at least three and ethylene oxide end-capping with one or more polyisocyanates having a weight average isocyanate functionality of greater than 2.3. The adhesive composition has a long open time and rapid cure time compared to currently available adhesives. The polyoxypropylene polyol preferably has a number average molecular weight of from 3,000 to 8,000. The composition finds special use in panel lamination applications.
1. A liquid, solvent free, moisture curable polyurethane adhesive composition comprising:
an acid selected from phosphoric acid, trifluoromethane sulfonic acid, methane sulfonic acid and ethane sulfonic acid; and
the reaction products of:
a polyol component comprising at least one polyoxypropylene polyol having a hydroxyl functionality of from 3.0 to about 4.5 and ethylene oxide end-capping, wherein the polyol component is free of filler;
optionally one or more polyols selected from the group consisting of a non-polyoxypropylene polyol or a polyoxypropylene polyol that is not ethylene oxide end-capped or a polyoxypropylene polyol having a hydroxyl functionality outside the range of 3.0 to about 4.5; and
a polyisocyanate component comprising one or more polyisocyanates, wherein the one or more polyisocyanates have a weight average isocyanate functionality of from 2.3 to about 3.3.
2. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said one or more polyisocyanates having a weight average isocyanate functionality of at least 2.4 to about 3.3.
3. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said one or more polyisocyanates having a weight average isocyanate functionality of at least 2.5 to about 3.3.
4. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said at least one polyoxypropylene polyol is present in an amount of from 20 to 80% by weight based on the total weight of said composition.
5. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said at least one polyoxypropylene polyol is present in an amount of from 30 to 60% by weight based on the total weight of said composition.
6. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said one or more polyisocyanates is present in an amount of from 20 to 80% by weight based on the total weight of said composition.
7. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said one or more polyisocyanates is present in an amount of from 30 to 60% by weight based on the total weight of said composition.
8. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said at least one polyoxypropylene polyol has a number average molecular weight of from 3,000 to 8,000.
9. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said at least one polyoxypropylene polyol has a number average molecular weight of from 3,500 to 6,500.
10. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 , further comprising liquid mineral oil, liquid aromatic oil, and combinations thereof.
11. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 , comprising from 0.005 to 0.8 weight % based on the total composition weight of the acid.
12. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said one or more polyisocyanates comprises polymeric MDI or a mixture of polymeric MDI and MDI.
13. An assembly comprising the adhesive composition of claim 1 .
14. An assembly comprising cured reaction products of the adhesive composition of claim 1 .
15. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said composition is a two-component composition and wherein the two components are stored separately and combined immediately prior to use.
16. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 wherein said composition is a two-component composition and wherein the two components cannot be mixed and stored.
17. A liquid, solvent free, moisture curable polyurethane adhesive composition comprising the reaction products of:
one or more polyisocyanates, wherein the one or more polyisocyanates have a weight average isocyanate functionality of from 2.3 to about 3.3; and
at least one polyol, wherein all of the polyols in the reaction product are selected from the group consisting of polyoxypropylene polyol having a hydroxyl functionality of from 3.0 to about 4.5 and ethylene oxide end-capping; a non-polyoxypropylene polyol; a polyoxypropylene polyol that is not ethylene oxide endcapped; a polyoxypropylene polyol that is not ethylene oxide endcapped having a hydroxyl functionality outside the range of 3.0 to about 4.5; and combinations thereof;
wherein the adhesive composition is free of filler.
18. The liquid, solvent free, moisture curable polyurethane adhesive composition of claim 1 being free of filler.