Hot melt adhesive
View Patent ↗Hot melt adhesives are provided that have improved heat resistance. The adhesives comprise a metallocene polyolefin, an amorphous α-olefin polymer, a tackifier and a functional polyolefin. The functional polyolefin is used in an amount sufficient to increase the heat resistance. A preferred functional polyolefin is a maleated polyolefin such as maleated polypropylene. A preferred tackifier is a hydrogenated hydrocarbon tackifier.
1. A hot melt adhesive consisting essentially of:
(a) from 20 to 75 wt % of a mixture wherein the mixture comprises (i) from 10 to 50 wt % of a crystalline metallocene polypropylene copolymer component that has a viscosity range of about 60 to about 7000 cP at 170° C. and (ii) from 20 to 50 wt % of an amorphous α-olefin polymer component
(b) from 0.1 to 15 wt % of a functionalized polyolefin;
(c) from 20 to 60 wt % of a tackifier;
(d) from 5 to 40 wt% of a wax that has a melt temperature between 49° C. and 121° C.; and
(e) from 0.1 to 1.5 wt % of a stabilizer or antioxidant
wherein the adhesive has a viscosity range of from about 700 cP to about 10,000 cP at 180° C. and the adhesive has a heat stress cleavage improvement of at least 10° C. over an adhesive without the functionalized polyolefin and wherein the wt % is based on the total weight of the adhesive.
2. The adhesive of claim 1 wherein the functionalized polyolefin is a maleated polypropylene wherein the adhesive has a heat stress cleavage improvement of at least 37° C. over an adhesive without the functionalized polyolefin.
3. An article of manufacture comprising the adhesive of claim 1 .
4. The hot melt adhesive of claim 1 wherein the functionalized polyolefin is present from 0.5 to 10 wt %.
5. The hot melt adhesive of claim 1 wherein the adhesive has a heat stress cleavage improvement of at least 40° C. over an adhesive without the functionalized polyolefin.
6. The article of manufacture comprising the adhesive of claim 2 .
7. The article of claim 6 which is a nonwoven article.
8. The hot melt adhesive of claim 1 wherein the wax has a melt temperature between 82° C. and 104° C.