Hot melt adhesive composition based on a random copolymer of isotactic polypropylene

• US 20040081795A1
• Filed: 10/28/2002
• Published: 04/29/2004
• Est. Priority Date: 10/28/2002
• Status: Active Grant

• Current Assignee: Bostik Incorporated (Totalenergies Se)
• Original Assignee: Bostik Incorporated (Totalenergies Se)
• Inventors: Zhang, Chongyao, Svenningsen, Lacretia A., Wang, Baoyu, Kanderski, Monina Dadap, Strelow, Diane M., Gibes, Mark A.
• Granted Patent: US 7,067,585 B2
• Time in Patent Office: Days
• US Class Current: 428/114
• CPC Class Codes: C08L 2205/02 containing two or more polymers of the same C08L -group
• CPC Class Codes: C08L 23/142 at least partially crystalline copolymers of propene with other olefins
• CPC Class Codes: C08L 2666/06 Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof
• CPC Class Codes: C09J 123/142 at least partially crystalline copolymers of propene with other olefins
• CPC Class Codes: Y10T 428/24132 including grain, strips, or filamentary elements in different layers or components parallel
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 442/602 Nonwoven fabric comprises an elastic strand or fiber material
• CPC Class Codes: Y10T 442/643 Including parallel strand or fiber material within the nonwoven fabric
• CPC Class Codes: Y10T 442/659 Including an additional nonwoven fabric
• CPC Class Codes: Y10T 442/674 Nonwoven fabric with a preformed polymeric film or sheet

Abstract

A hot melt adhesive composition is based on an isotactic polypropylene random copolymer (RCP). The composition contains about 4%-50% by weight of the RCP copolymer, about 20%-65% by weight of a compatible tackifier, about 0%-40% by weight of a plasticizer, about 0%-3% by weight of a stabilizer, about 0%-40% by weight of a wax, and optionally about 0%-60% by weight of an atactic poly-α-olefin (APAO). The adhesive composition may be used in a number of applications such as, for example, in disposable nonwoven hygienic articles, paper converting, flexible packaging, wood working, carton and case sealing, labeling and other assembly applications.

Claims

1. A hot melt adhesive composition comprising a blend of the following components:

(a) about 4% to 50% by weight of a random RCP copolymer of propylene and at least one α

-olefin comonomer having the following molecular structure;

R—

CH═

CH₂

where R is hydrogen or a C₂ to C₁₀ alkyl group, and said α

-olefin comprises about 1.5% by weight to about 20% by weight of the said RCP copolymer;

(b) about 20% to 65% by weight of a tackifier;

(c) about 0% to 60% by weight of an atactic poly-α

-olefin (APAO) polymer;

(d) about 0% to 40% by weight of a plasticizer;

(e) about 0% to 40% by weight of a wax;

(f) about 0% to 3% by weight of a stabilizer; and

(g) about 0% to 60% by weight of a filler;

the components totaling 100% by weight of the composition.

2. The composition of claim 1 wherein said RCP copolymer has a density of about 0.88 g/cc to 0.905 g/cc and a melt flow rate of equal to or greater than 5 g/10 min and an a melting point equal to or less than 145°

C.

3. The composition of claim 2 wherein said RCP copolymer is an mRCP copolymer of propylene and at least one α

-olefin prepared by using a metallocene catalyst system.

4. The composition of claim 1 wherein said APAO polymer has a density of about 0.85 g/cc to 0.89 g/cc and a glass transition temperature (Tg) of from about −

5 to −

40°

C. and a weight average molecular weight (Mw) of from about 4,000 g/mol to about 150,000 g/mol.

5. The composition of claim 1 wherein the α

-olefin comonomer is selected from the group consisting of ethylene, butene-1 and hexene-1.

6. The composition of claim 1 wherein the APAO polymer is a homopolymer or a copolymer of propylene and at least one α

-olefin comonomer having the following molecular structure;

R—

CH═

CH₂

where R is hydrogen, or an alkyl or an aryl radical.

7. The composition of claim 6 wherein the α

-olefin comonomer is selected from the group consisting of ethylene, butene-1 and hexene-1.

8. The composition of claim 1 wherein the tackifier is selected from the group consisting of aliphatic and cycloaliphatic hydrocarbon resins and their hydrogenated derivatives, aromatic and hydrogenated aromatic hydrocarbon resins, aromatically modified aliphatic or cycloaliphatic resins and their hydrogenated derivatives, polyterpene and styrenated polyterpene resins.

9. The composition of claim 8 wherein the tackifier has a R&

B softening point equal to or greater than 80°

C.

10. The composition of claim 9 wherein the tackifier is a C-5 aliphatic hydrocarbon resin.

11. The composition of claim 1 wherein the plasticizer is selected from the group consisting of mineral oil and liquid polybutene.

12. The composition of claim 11 wherein the mineral oil has less than 30% aromatic carbon atoms.

13. The composition of claim 1 wherein said wax is selected from the group consisting of petroleum waxes, low molecular weight polyethylene and polypropylene, synthetic waxes and polyolefin waxes.

14. The composition of claim 13 wherein the said wax is a low molecular weight polyethylene having a number average molecular weight of about 400 to about 6,000 g/mol.

15. The composition of claim 1 further including 0.1% to about 30% by weight of a surfactant.

16. The composition of claim 15 wherein the surfactant has an HLB of less than 15.

17. The composition of claim 15 wherein the surfactant is selected from the group consisting of fatty acid esters, nonionic ethoxylates and ethylene oxide/propylene oxide copolymers.

18. The composition of claim 1 wherein said filler is selected from the group consisting of talc, calcium carbonate, clay, silica, mica, wollastonite, feldspar, aluminum silicate, alumina, hydrated alumina, glass microsphere, ceramic microsphere, thermoplastic microsphere, baryte and wood flour.

19. The composition of claim 1 wherein the adhesive composition further includes a colorant.

20. A corrugated box article bonded with the adhesive composition of claim 1.

21. A laminate comprising a first layer of nonwoven material, a second layer of nonwoven material, and a plurality of elastic strands disposed between said first and second nonwoven layers, bonded together with the adhesive composition of claim 1.

22. A laminate comprising a first layer of nonwoven material, a second layer of film material, and a plurality of elastic strands disposed between said first and second layers, bonded together with the adhesive composition of claim 1.

23. The laminate of claim 22 where the said film comprises a polyethylene film, a polypropylene film, an ethylene-propylene copolymer film or a polyolefin coated cloth-like nonwoven material.

24. A laminate comprising a first layer of nonwoven material bonded to a second layer of film material with the adhesive composition of claim 1.

25. The laminate of claim 24 where the said film material comprises a polyethylene film, a polypropylene film, an ethylene-propylene copolymer film or a polyolefin coated cloth-like nonwoven material.