Accelerate cure of moisture curable polyurethane adhesive compositions useful for bonding glass
The adhesive system of the invention is especially useful in bonding replacement windows into vehicles. They allow for sufficient working time while still realizing a fast drive away time. The adhesive system is comprised of a moisture curable adhesive and a cure accelerator that may be applied using a simple single caulk gun and may be applied at ambient temperatures such as −10° C. and about 45° C. The cure accelerator is comprised of a polyol having a backbone that has at least one amine in the backbone. The moisture curable adhesive typically is comprised of an isocyanate terminated prepolymer.
1. An adhesive system comprised of a moisture curable adhesive comprised of an isocyanate terminated prepolymer made using a diol and a triol, and a plasticizer, and a separate cure accelerator comprised of a first polyol having a backbone comprised of at least one amino group characterized by an apparent pH of at least 10 when measured in a solution of 10 g of the first polyol in 60 ml of a 10 wt % water solution in isopropyl alcohol, and an average OH functionality of at least 2 to 4.5 and present in an amount of 5% to 50% by weight of the cure accelerator; wherein the cure accelerator includes 20% to 80% by weight of the cure accelerator of a polyol not having an amino group, and the amount of any water in the cure accelerator is less than 1 weight percent, based on the total weight of the cure accelerator and the moisture curable adhesive:
wherein the adhesive system, upon curing, is substantially free of bubbles and has a Shore A hardness of at least 60, when measured according to ASTM D 2240-05;
wherein a volume ratio of the moisture curable adhesive to the cure accelerator is 5 to 200.
2. The adhesive system of claim 1 , wherein the prepolymer is comprised of an isocyanate terminated polyether prepolymer, and the cure accelerator includes from 0 to 500 ppm water, based on the total weight of the cure accelerator and the moisture curable adhesive.
3. The adhesive system of claim 2 , wherein the isocyanate terminated polyether prepolymer is comprised of a polyether backbone comprised of an ethylene oxide, a propylene oxide, or combination of these.
4. The adhesive system of claim 1 , wherein the first polyol having an amino group has an OH # of at least about 250.
5. The adhesive system of claim 1 , wherein said first polyol has an OH # of at least 550.
6. The adhesive system of claim 1 , wherein the moisture curable adhesive is further comprised of at least one of the following a filler and a catalyst.
7. The adhesive system of claim 6 , wherein the plasticizer is linear, branched or combination thereof.
8. The adhesive system of claim 1 , wherein the first polyol has an average OH functionality of at least 3.5 to 4.2.
9. The adhesive system of claim 1 , wherein the amino groups are all tertiary amines.
10. The adhesive system of claim 4 , wherein the cure accelerator includes 10 to 35 percent of one or more fillers based on the weight of the cure accelerator.
11. The adhesive system of claim 10 , wherein the cure accelerator includes from 0 to 500 ppm water, based on the total weight of the cure accelerator and the moisture curable adhesive.
12. The adhesive system of claim 11 , wherein the cure accelerator includes 0.01% to 2% catalyst, based on the total weight of the cure accelerator.
13. An adhesive system comprised of a moisture curable adhesive comprised of an isocyanate terminated prepolymer made using a diol and a triol, and a plasticizer, and a separate cure accelerator comprised of a polyol having a backbone comprised of about 3.0 to about 6 amino groups and an average OH functionality of at least 2 to 4.5;
wherein the polyol having an amino group has an apparent pH of at least 10 when measured in a solution of 10 g of the first polyol in 60 ml of a 10 wt % water solution in isopropyl alcohol; wherein the cure accelerator includes 20% to 80% by weight of the cure accelerator of a polyol not having an amino group, and the amount of any water in the cure accelerator is sufficiently low so that bubbling is avoided upon curing the adhesive system;
wherein the adhesive system, upon curing, is substantially free of bubbles and has a Shore A hardness of at least 60, when measured according to ASTM D 2240-05.
14. The adhesive system of claim 13 , wherein the moisture curable adhesive and cure accelerator are provided in a volumetric ratio of moisture curable adhesive/cure accelerator of 5 to 200.
15. The adhesive system of claim 14 , wherein said volumetric ratio is 5 to 20.
16. The adhesive system of claim 13 , wherein the apparent pH is at least 11.