Tackifier-free hot melt adhesive compositions suitable for use in a disposable hygiene article

Patent metadata

Field	Value
Publication number	US-12247142-B2
Application number	US-202017626238-A
Country	US
Kind code	B2
Filing date	Jul 10, 2020
Priority date	Jul 12, 2019
Publication date	Mar 11, 2025
Grant date	Mar 11, 2025

Abstract

A hot melt adhesive composition comprises a polypropylene homopolymer having a DSC melting point of less than 100° C.; a butene-based copolymer; and a plasticizer. The butene-based copolymer may comprise a butene-rich amorphous poly-alpha olefin, such as a butene-propylene copolymer, or a semi-crystalline copolymer, such as a butene-ethylene copolymer. The hot melt adhesive is especially useful for bonding substrates which swell or elongate significantly in use. Such uses include adhering superabsorbent polymers to a substrate or adhering together two substrates at least one of which having superabsorbent polymers, such as the top and bottom layer of an absorbent core of a disposable hygiene article, such as a diaper, feminine sanitary napkin, and adult incontinence pad. The hot melt adhesive composition, which does not contain a tackifier, demonstrates suitable elongation at break and stress at yield, with a sufficiently low viscosity, to stabilize an absorbent core having superabsorbent polymers.

First claim

What is claimed:

1. A hot melt adhesive composition comprising:
(a) a polypropylene homopolymer having a DSC melting point of less than 100° C.;
(b) a 1-butene-based copolymer; and
(c) a plasticizer;
wherein the composition is tackifier-free.

2. The composition of claim 1 , wherein the 1-butene-based copolymer comprises a butene-rich amorphous poly-alpha olefin.

3. The composition of claim 2 , wherein the 1-butene-rich amorphous poly-alpha olefin comprises a butene-propylene copolymer.

4. The composition of claim 1 , wherein the 1-butene-based copolymer comprises a semi-crystalline copolymer.

5. The composition of claim 4 , wherein the semi-crystalline copolymer comprises a butene-ethylene copolymer.

6. The composition of claim 1 , wherein the polypropylene homopolymer is present in an amount of between about 20% and about 75% by weight; the 1-butene-based copolymer is present in an amount of between about 3% and about 50% by weight; and the plasticizer is present in an amount of between about 20% and about 60% by weight.

7. The composition of claim 1 , wherein:
the weight average molecular weight of the polypropylene homopolymer is between about 5,000 and about 150,000 daltons; and
the weight average molecular weight of the 1-butene-based copolymer is between about 15,000 and about 160,000 daltons.

8. The composition of claim 1 , wherein:
the 1-butene-based copolymer comprises a butene-rich amorphous poly-alpha olefin comprising a butene-propylene copolymer;
the weight average molecular weight of the polypropylene homopolymer is between about 5,000 and about 150,000 daltons; and
the weight average molecular weight of the butene-rich amorphous poly-alpha olefin is between about 15,000 and about 85,000 daltons.

9. The composition of claim 1 , wherein the weighted average of the weight average molecular weights of the polypropylene homopolymer and the butene-based copolymer is between about 60,000 and about 80,000 daltons.

10. The composition of claim 1 , wherein the viscosity of the composition is equal to or less than about 30,000 centipoise (cP) at 163° C. (325° F.), preferably equal to or less than about 22,500 centipoise (cP) at 163° C. (325° F.), and most preferably equal to or less than about 15,000 centipoise (cP) at 163° C. (325° F.).

11. The composition of claim 1 , wherein the viscosity of the composition is equal to or less than about 17,500 centipoise (cP) at 177° C. (350° F.).

12. The composition of claim 1 , wherein heat of fusion of the composition obtained by DSC according to ASTM E793-01 of the composition is less than 40 J/g.

13. The composition of claim 1 , wherein the plasticizer is selected from the group consisting of mineral oil, synthetic poly-alphaolefin oils, and polyisobutylene.

14. The composition of claim 1 further comprising an antioxidant.

15. The composition of claim 1 , wherein the composition does not contain a wax.

16. The composition of claim 1 , wherein the composition has an elongation at break of at least about 350%.

17. The composition of claim 1 , wherein the composition has a stress at yield of at least about 0.5 MPa.

18. A method of making a laminate comprising the steps of:
applying the hot melt adhesive composition of claim 1 in a molten state to a primary substrate; and
mating a secondary substrate to the first substrate by contacting the secondary substrate with the adhesive composition.

19. The method of claim 18 , wherein the first substrate comprises a first layer of an absorbent core and the secondary substrate comprises a second layer of the absorbent core, wherein at least one of the first layer or the second layer have superabsorbent polymers associated therewith.

20. An absorbent core comprising a top layer and a bottom layer, wherein at least one of the top layer and the bottom layer comprises superabsorbent polymers, and the top layer and the bottom layer are adhered to each other by a hot melt adhesive composition of claim 1 and the adhesive composition adheres the superabsorbent polymers within the absorbent core.

21. A disposable hygiene article comprising the absorbent core of claim 20 .

Assignees

• Bostik Inc
• Bostik Sa

Inventors

• Secrist Kimberly E
• Gray Steven D
• Hussein Naji

Classifications

• C09J5/06

  involving heating of the applied adhesive · CPC title

• A61F2013/53958

  with separate adhesive layer · CPC title

• A61F13/539 Primary

  characterised by the connection of the absorbent layers with each other or with the outer layers · CPC title

• C09J123/12 Primary

  Polypropene · CPC title

• A61F2013/5395

  with thermoplastic agent, i.e. softened by heat · CPC title