Hot melt adhesive containing a hydrogenated styrenic block copolymer and an ethylene vinyl acetate copolymer exhibiting low blocking force

Patent metadata

Field	Value
Publication number	US-11912906-B2
Application number	US-201414329058-A
Country	US
Kind code	B2
Filing date	Jul 11, 2014
Priority date	Jul 11, 2013
Publication date	Feb 27, 2024
Grant date	Feb 27, 2024

Abstract

A hot melt adhesive composed of an ethylene vinyl acetate copolymer, a hydrogenated styrenic block copolymer, a tackifying resin, and a liquid plasticizer. The preferred ethylene vinyl acetate copolymer has a vinyl acetate content between 8 and 28 percent by weight, and the preferred hydrogenated styrenic block copolymer is a styrene-ethylene-butylene-styrene having about 30% styrene content and essentially no diblock. The hot melt gives excellent peel strength when used as a construction adhesive for disposable nonwoven articles. It can also be formulated to exhibit very low bleed through and blocking characteristics when used on low basis weight nonwoven fabrics.

First claim

The invention claimed is:

1. A hot melt adhesive composition, consisting of:
about 5% to about 40% by weight of an ethylene vinyl acetate copolymer having a melt index greater than about 2 g/10 minutes;
about 30% to about 70% by weight of a tackifying resin;
about 7% to about 17.4% by weight of a hydrogenated styrenic block copolymer comprising a styrene-ethylene-butylene-styrene polymer and having a diblock content of less than about 30% by weight relative to the weight of the hydrogenated styrenic block copolymer;
about 14% to about 40% by weight of a liquid plasticizer selected from the group consisting of mineral oil, polybutene, or mixtures thereof; and
about 0% to about 5% by weight of a stabilizer;
wherein the viscosity of the composition is equal to or less than about 20,000 centipoise at 325° F.

2. The composition of claim 1 wherein the composition has a storage modulus at 25° C. that is greater than about 1×10 6 dynes/cm 2 .

3. The composition of claim 1 comprising about 10% to about 28% by weight of said ethylene vinyl acetate copolymer.

4. The composition of claim 1 comprising about 14% to about 30% by weight of said liquid plasticizer.

5. The composition of claim 1 wherein said composition has a viscosity equal to or less than 15,000 centipoise at 325° F.

6. The composition of claim 1 wherein said composition has a viscosity equal to or less than 10,000 centipoise at 325° F.

7. The composition of claim 1 wherein said hydrogenated styrenic block copolymer has a styrene content of about 25% to about 35% by weight.

8. The composition of claim 1 wherein said hydrogenated styrenic block copolymer has no diblock content.

9. The composition of claim 1 wherein the tackifying resin has a softening point equal to or greater than about 90° C.

10. The composition of claim 1 wherein the tackifying resin has a softening point of from about 95° C. to about 140° C.

11. The composition of claim 1 wherein the tackifying resin has a softening point of from about 95° C. to about 130° C.

12. The composition of claim 1 having about 40% to about 65% by weight of said tackifying resin.

13. The composition of claim 1 having about 45% to about 60% by weight of said tackifying resin.

14. The composition of claim 1 wherein the vinyl acetate content of said ethylene vinyl acetate copolymer is about 8% to about 28% by weight based on the ethylene vinyl acetate copolymer.

15. The composition of claim 1 wherein the vinyl acetate content of said ethylene vinyl acetate copolymer is about 8% to about 18% by weight based on the ethylene vinyl acetate copolymer.

16. A laminate comprising a first layer of nonwoven material and a second layer of nonwoven material, bonded together with the adhesive composition of claim 1 .

17. A laminate comprising a first layer of nonwoven material and a second layer of film material, bonded together with the adhesive composition of claim 1 .

18. The laminate of claim 17 wherein said film comprises a polyethylene film, a polypropylene film, an ethylene-propylene copolymer film or a cloth-like coated film material.

19. An article comprising the adhesive composition of claim 1 .

20. The article of claim 19 comprising a disposable diaper, a sanitary napkin, a bed pad, a bandage, a surgical drape, a tape, a label, a plastic sheet, a nonwoven sheet, a paper sheet, a cardboard, a book, a filter, or a package.

21. The composition of claim 1 , wherein said hydrogenated styrenic block copolymer consists of the styrene-ethylene-butylene-styrene polymer.

22. The composition of claim 1 , wherein the ethylene vinyl acetate copolymer has a melt index greater than about 5 g/10 minutes.

23. The composition of claim 1 , wherein the ethylene vinyl acetate copolymer has a melt index no more than about 500 g/10 minutes.

Assignees

• Bostik Inc

Inventors

• Stafeil Kevin
• Farris Kathleen M

Classifications

• C09J157/02 Primary

  Copolymers of mineral oil hydrocarbons · CPC title

• A61L15/24

  Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof {(A61L15/225 takes precedence)} · CPC title

• A61L15/585

  Mixtures of macromolecular compounds · CPC title

• B32B5/022

  Non-woven fabric · CPC title

• B32B5/26

  another layer {next to it} also being fibrous or filamentary {(relative arrangement of fibres or filaments of different layers B32B5/12)} · CPC title