Polypropylene-based adhesive compositions

• US 6,747,114 B2
• Filed: 12/21/2000
• Issued: 06/08/2004
• Est. Priority Date: 12/22/1999
• Status: Expired due to Term

• Current Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Chemical Patents Inc. (Exxon Mobil Corporation)
• Inventors: Harrington, Bruce A., Nelson, Keith A., Tancrede, Jean M., Cozewith, Charles, Lohse, David J., Datta, Sudhin, Karandinos, Anthony G., Lewtas, Kenneth, Georjon, Olivier J. F.
• Primary Examiner(s): RABAGO, ROBERTO
• Application Number:
  US09/745,394
• Publication Number:
  US 20020019507A1
• Time in Patent Office: 1,265 Days
• Field of Search: 525/326.1, 525/240, 525/333.7, 525/333.8, 526/348, 526/348.2, 526/348.5, 526/348.6
• US Class Current: 526/348.2
• CPC Class Codes: C08F 210/06 Propene
• CPC Class Codes: C08F 210/14 Monomers containing five or more carbon atoms
• CPC Class Codes: C08F 210/16 Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• CPC Class Codes: C08F 2500/03 Narrow molecular weight distribution, i.e. Mw/Mn < 3
• CPC Class Codes: C08F 2500/12 Melt flow index or melt flow ratio
• CPC Class Codes: C08F 2500/17 Viscosity
• CPC Class Codes: C08L 2205/02 containing two or more polymers of the same C08L -group
• CPC Class Codes: C08L 23/10 Homopolymers or copolymers of propene
• CPC Class Codes: C08L 2314/06 Metallocene or single site catalysts
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C09J 123/10 Homopolymers or copolymers of propene
• CPC Class Codes: C09J 123/14 Copolymers of propene C09J123/16 takes precedence

Abstract

An adhesive blend is described that can include a semi-crystalline copolymer of propylene and at least one comonomer selected from the group consisting of ethylene and at least one C₄ to C₂₀ α-olefin, the copolymer having a weight average molecular weight (Mw) from about 15,000 to about 200,000; an melt index (MI) from about 7 dg/min to about 3000 dg/min as measured by ASTM D 1238(B), and a (Mw/Mn) of approximately 2. Various production processes are also described. Also described are adhesive compositions and methods for making adhesive compositions having polymers or polymer blends with melt flow rates (MFRs) equal to and above 250° dg/min. at 230° C. Certain specific embodiments of the invention involve the use of a free radical initiator, e.g., a peroxide.

Claims

1. An adhesive composition comprising a semi-crystalline copolymer of propylene and at least one comonomer selected from the group consisting of ethylene and C₄ to C₂₀ α

-olefins, wherein the copolymer has a propylene content of greater than 65 mole percent a weight average molecular weight (Mw) of from about 15,000 to about 200,000, a melt index (MI) of from about 7 dg/min to about 3000 dg/min as measured by ASTM D 1238(B), a weight average molecular weight/number average molecular weight ratio (Mw/Mn) of approximately 2, an MFR of greater than 250 dg/min. and a heat of fusion of from about 30 to about 80 J/g as determined by DSC.

2. The adhesive composition of claim 1, wherein the semi-crystalline copolymer has a propylene content greater than 73 mole percent.

4. The adhesive composition of claim 1, wherein the semi-crystalline copolymer has a random comonomer sequence distribution.

5. The adhesive composition of claim 1, wherein the semi-crystalline copolymer comprises isotactic polypropylene sequences.

6. The adhesive composition of claim 1, wherein the composition is a hot melt adhesive composition.

7. The adhesive composition of claim 1, further comprising a wax.

8. The adhesive composition of claim 1, further comprising at least one additive selected from the group consisting of a tackifier, an antioxidant and combinations thereof.

9. The adhesive composition of claim 1, wherein the semi-crystalline copolymer has a weight average molecular weight (Mw) of from about 50,000 to about 150,000.

10. The adhesive composition of claim 1, wherein the composition has a melt viscosity of less than 10,000 cps measured at 180°

C.

11. An article of manufacture comprising the adhesive composition of claim 1.

12. The article of manufacture of claim 11, wherein the article of manufacture is a sanitary article.

3. The adhesive composition of claim it wherein the melt index of the semi-crystalline copolymer is from about 20 dg/min to about 900 dg/min.

13. An adhesive composition having an MFR greater than about 250 dg/min. at 230°

C., the composition comprising a blend of a crystalline polymer and a random copolymer produced by copolymerizing propylene and at least one of ethylene and alpha-olefins having 20 or fewer carbon atoms, the random copolymer having a crystallinity of at least about 2% and no greater than about 65% derived from stereoregular polypropylene sequences and a melting point of from about 25°

C. to about 105°

C.

14. The adhesive composition of claim 13, wherein the crystalline polymer has a melting point greater than about 110°

C.

15. The adhesive composition of claim 13, Wherein the crystalline polymer comprises polypropylene or a copolymer comprising propylene units and at least one comonomer selected from the group consisting of ethylene and C₄-C₂₀ α

-olefins, the copolymer having a comonomer content of less than about 15 mole percent.

16. The adhesive composition of claim 13, wherein the crystalline polymer comprises isotactic polypropylene.

17. The adhesive composition of claim 13, wherein the crystalline polymer comprises isoractic polypropylene having a melting point greater than 110°

C.