LOW TEMPERATURE HOT MELT ADHESIVES FOR DISPOSABLE ARTICLES WITH HIGH CREEP RESISTANCE

• US 20130202787A1
• Filed: 03/15/2013
• Published: 08/08/2013
• Est. Priority Date: 02/18/2011
• Status: Active Grant

• Current Assignee: Henkel AG & Co KGaA
• Original Assignee: Henkel Corporation (Henkel AG & Co KGaA)
• Inventors: Hu, Yuhong, Xenidou, Maria
• Granted Patent: US 8,987,372 B2
• Time in Patent Office: Days
• US Class Current: 427/208.2
• CPC Class Codes: C08L 53/02 of vinyl-aromatic monomers and conjugated dienes
• CPC Class Codes: C08L 91/00 Compositions of oils, fats or waxes; Compositions of derivatives thereof
• CPC Class Codes: C08L 91/06 Waxes
• CPC Class Codes: C08L 91/08 Mineral waxes
• CPC Class Codes: C09J 153/02 Vinyl aromatic monomers and conjugated dienes
• CPC Class Codes: C09J 191/06 Waxes
• CPC Class Codes: C09J 191/08 Mineral waxes
• CPC Class Codes: C09J 5/06 involving heating of the applied adhesive

Abstract

The present invention is directed to adhesives suitable for application using a hot melt process at a relatively low temperature in the range of about 110° C. to about 130° C. Such adhesives exhibit desirable viscoelastic properties and are suitable for bonding an elastic attachment in the manufacture of disposable articles, such as disposable diapers.

Claims

1. A low application temperature hot melt adhesive comprising:

(a) at least one styrenic block copolymer which has a melt flow index greater than 33, measured in accordance with ASTM D 1238, and a styrene content greater than 40%, and

(b) a wax,

wherein the adhesive has a viscosity less than about 8,500 centipoises at 120°

C.

2. The low application temperature hot melt adhesive of claim 1 comprising:

(a) 5 to 20 wt % of the styrenic block copolymer;

(b) 0.5 to 5% wt % of the wax;

(c) 30-70 wt % of a tackifier; and

(d) 0.1-2 wt % of an antioxidant.

3. The low application temperature hot melt adhesive of claim 2 wherein the tackifier has a ring and ball softening point less than about 105°

C.

4. The low application temperature hot melt adhesive of claim 3 wherein the tackifier is selected from the group consisting of aliphatic C5 resins, aliphatic resins, dicyclopentadiene resins, C5/C9 blended resins and mixtures thereof.

5. The low application temperature hot melt adhesive of claim 2 further comprising 0 to 30 wt % of an oil.

6. The low application temperature hot melt adhesive of claim 1 wherein the adhesive has a crossover temperature greater than 60°

C.

7. The low application temperature hot melt adhesive of claim 6 wherein the crossover temperature, measured as the point where tan d=1, is greater than 65°

C.

8. The low application temperature hot melt adhesive of claim 1 wherein the adhesive has a yield stress of greater than 50 psi.

9. The low application temperature hot melt adhesive of claim 8 wherein the yield stress is greater than 75 psi.

10. The low application temperature hot melt adhesive of claim 1 wherein the styrenic block copolymer is a styrene-isoprene-styrene, styrene-butadiene-styrene or mixtures thereof.

11. The low application temperature hot melt adhesive of claim 1 wherein the wax is selected from the group consisting of paraffin waxes, microcrystalline waxes, polyethylene waxes, polypropylene waxes, by-product polyethylene waxes, Fischer-Tropsch waxes, oxidized Fischer-Tropsch waxes, functionalized waxes, and mixtures thereof.

12. An article comprising the low application temperature hot melt adhesive of claim 1.

13. The article of claim 12 which is a disposable article.

14. The article of claim 13 which is an elastic attachment.

15. A method of forming an article comprising:

(a) applying the low application temperature hot melt adhesive of claim 1 onto a substrate at a temperature in the range of from about 110°

C. to about 130°

C. at an add-on-level of about 20 to about 100 mg/m/strand;

(b) cooling the adhesive to room temperature;

wherein the cooled adhesive has a creep performance of less than about 15% after 300% strain is applied on the cooled adhesive at 38°

C. for four hours

16. The method of claim 15 wherein the adhesive is applied by strand coating.

17. A method of forming an article comprising:

(a) applying the low application temperature hot melt adhesive of claim 1 onto a substrate at a temperature in the range of from about 110°

C. to about 130°

C. at an add-on-level of about 3 to about 30 mg/in; and

(b) cooling the adhesive to room temperature;

wherein the cooled adhesive has a creep performance of less than about 25% after 300% strain is applied on the cooled adhesive at 38°

C. for four hours.

18. The method of claim 17 wherein the adhesive is applied by spiral coating.