Low application temperature hot melt adhesive
View Patent ↗A low application temperature rubber-based hot melt adhesive having properties particularly well suited for use in the construction of disposable articles has been invented. The adhesive comprises a styrene block copolymer and a type of wax in an amount effective to produce a viscosity at 120° C. of below about 10,000 centipoises, a cube flow at 130° F. (54° C.) of less than about 300%, a DSC crystallization temperature of less than about 75° C. and a storage modulus of less than about 1.0×10 7 dynes/cm 2 at 10 rads/sec (25° C.).
1. A hot melt adhesive formulated for application at a temperature of less than about 120° C., said adhesive comprising a styrene block copolymer and a type and amount of wax effective to produce an adhesive having a viscosity at 120° C. of below about 10,000 centipoises, a cube flow at 54° C. of less than about 300%, a DSC crystallization temperature of less than about 75° C., and a storage modulus of less than about 1.0×10 7 dynes/cm 2 at 10 rads/sec (25° C.), wherein the styrene block copolymer is present in amounts of from about 10 to about 25 wt % and wherein said effective amount of wax is less than 10 wt %.
2. The adhesive of claim 1 wherein said wax has a melting point of greater than about 74° C.
3. The adhesive of claim 2 wherein the wax comprises a mixture of waxes.
4. The adhesive of claim 1 comprising a SBS polymer, a SIS polymer, a SEBS polymer and/or a SEPS polymer.
5. The adhesive of claim 1 wherein the styrene block copolymer is a blend of SBS and SIS.
6. The adhesive of claim 1 further comprising a tackifier, a plasticizer and/or an antioxidant.
7. The adhesive of claim 6 comprising at least about 1 wt % of said wax.
8. The adhesive of claim 7 comprising from about 40 to about 70 wt % of a tackifier, from about 15 to about 30 wt % of a plasticizer, and up to about 2 wt % of an antioxidant.
9. The adhesive of claim 6 wherein the tackifier has a softening point of greater than about 80° C.
10. The adhesive of claim 1 wherein said wax has a melting point of greater than about 165° F.
11. The adhesive of claim 10 wherein said wax is a crystalline wax.
12. The adhesive of claim 1 comprising about 14 wt % of said styrene block copolymer and about 5 wt % of said wax.
13. The adhesive of claim 1 where in the styrene block copolymer is SBS.
14. The adhesive of claim 10 wherein said wax has a melting point of greater than about 165° F.
15. A hot melt adhesive formulated for application at a temperature of less than about 120° C., said adhesive comprising
a styrene block copolymer,
a type and amount of wax effective to produce an adhesive having a viscosity at 120° C. of below about 10,000 centipoises, a cube flow at 54° C. of less than about 300%, a DSC crystallization temperature of less than about 75° C., and a storage modulus of less than about 1.0×10 7 dynes/cm 2 at 10 rads/sec (25° C.),
a tackifier, and
a plasticizing oil,
wherein said styrene block copolymer is present in amounts of from about 10 to about 25 wt %, said effective amount of wax is less than 10 wt %, said tackifier is present in amounts of from about 40 to about 70 wt %, and said plasticizing oil is present in amounts of from about 15 to about 30 wt %.
16. The adhesive of claim 14 , further comprising up to about 2 wt % of an antioxidant.
17. The adhesive of claim 14 wherein said wax is a microcrystalline wax having a melting point of greater than about 165° F.
18. The adhesive of claim 15 comprising about 14 wt % of said styrene block copolymer and about 5 wt % of said wax.