Elastic attachment adhesive containing radial block copolymer
View Patent ↗Hot melt adhesive compositions containing radial polystyrene-polyisoprene/polybutadiene block copolymer and use as elastic attachment adhesive in the manufacture of disposable absorbent elastic articles.
1. An elastic attachment hot melt adhesive comprising:
(1) 15 wt % to about 35 wt % of a radial block copolymer component comprising (PS-PI- PB) n X wherein PS is polystyrene, PI is polyisoprene and PB is polybutadiene, X is the residue of a multifunctional coupling agent used in the production of the radial block copolymer, and n is equal to or greater than 3 and represents the number of PS-PI-PB arms appended to X,
said radial block copolymer having a styrene content of from 25 wt % to about 50wt %,
said radial block copolymer has a di-block percentage of less than about 25%, based on the amount of the radial block copolymer, and
the number average molecular weight of each arm of said radial block copolymer is from about 30,000 to about 95,000;
(2) about 1 wt% to about 6 wt% of a linear triblock copolymer selected from the group consisting of styrene-isoprene-styrene, styrene-butadiene-styrene and styrene-isobutylene styrene; and
(3) about 30 wt% to about 70 wt % of a tackifying resin;
wherein the wt% is based on the weight of the adhesive composition.
2. The adhesive of claim 1 wherein the radial block copolymer has a di-block percentage of less than about 20%.
3. The adhesive of claim 1 wherein the n is between about 3 and about 6.
4. The adhesives of claim 1 further comprising a wax, said wax being present in an amount of less than about 5 wt %.
5. The adhesive of claim 1 further comprising a liquid plasticizer, said plasticizer being present in amounts of less than about 20 wt %.
6. An article of manufacture comprising the hot melt adhesive of claim 1 and a substrate, wherein
said substrate comprises an elastomeric fiber.
7. The article of claim 6 which is a disposable elastic article.
8. The article of claim 7 which is a diaper.
9. The elastic attachment hot melt adhesive of claim 1 wherein the tackifying resin consists of about 40 wt% to about 60 wt % of a midblock compatible tackifier and about 1 wt% to about 30 wt % of an endblock compatible tackifier.
10. The elastic attachment hot melt adhesive of claim 9 wherein the midblock compatible tackifier is selected from aliphatic resin, cycloaliphatic resin or mixtures thereof.