Thermoplastic vulcanizate comprising interpolymers of ethylene/α-olefins

• US 7,579,408 B2
• Filed: 03/15/2006
• Issued: 08/25/2009
• Est. Priority Date: 03/17/2004
• Status: Active Grant

• Current Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Original Assignee: Dow Global Technologies, Inc. (Dow, Inc.)
• Inventors: Hughes, Morgan M., Cheung, Yunwa W., Walton, Kim L., Rath, Gary L.
• Primary Examiner(s): Nutter; Nathan M
• Application Number:
  US11/377,006
• Publication Number:
  US 20060199910A1
• Time in Patent Office: 1,259 Days
• Field of Search: 525/191, 525/192, 525/210, 525/211, 525/232, 525/239, 525/240, 525/241
• US Class Current: 525/191
• CPC Class Codes: C08L 2205/03 containing three or more polymers in a blend
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 23/0815 Copolymers of ethene with aliphatic 1-olefins
• CPC Class Codes: C08L 23/10 Homopolymers or copolymers of propene
• CPC Class Codes: C08L 23/16 Elastomeric ethene-propene or ethene-propene-diene copolymers, e.g. EPR and EPDM rubbers
• CPC Class Codes: C08L 2312/00 Crosslinking
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials

Abstract

Thermoplastic vulcanizates comprise at least an ethylene/α-olefin interpolymer and at least one thermoplastic polymer, such as polyolefin. The ethylene/α-olefin interpolymer is a block copolymer having at least a hard block and at least a soft block. The soft block comprises a higher amount of comonomers than the hard block. The block interpolymer has a number of unique characteristics disclosed here. The block interpolymer is either used as a compatibilizer between a vulcanizable elastomer and a thermoplastic polymer or as a vulcanizable elastomer when it is in the EPDM form. The thermoplastic vulcanizates can be profiled extruded to make profiles and gaskets.

Claims

1. A thermoplastic vulcanizate comprising or obtained from a reaction mixture comprising:

(i) a vulcanizable elastomer;

(ii) a thermoplastic polyolefin;

(iii) a crosslinking agent; and

(iv) an ethylene/α

-olefin multi-block interpolymer, wherein the ethylene/α

-olefin multi-block interpolymer comprises at least 60 mole percent ethylene and;

(a) has a Mw/Mn from about 1.7 to about 3.5, at least one melting point, Tm, in degrees Celsius, and a density, d, in grams/cubic centimeter, wherein the numerical values of Tm and d correspond to the relationship;

T_m>

−

2002.9+4538.5(d)−

2422.2(d)²;

or

(b) has a Mw/Mn from about 1.7 to about 3.5, and is characterized by a heat of fusion, Δ

H in J/g, and a delta quantity, Δ

T, in degrees Celsius defined as the temperature difference between the tallest DSC peak and the tallest CRYSTAF peak, wherein the numerical values of Δ

T and Δ

H have the following relationships;

Δ

T>

−

0.1299(Δ

H)+62.81 for Δ

H greater than zero and up to 130 J/g,

Δ

T≧

48°

C. for Δ

H greater than 130 J/g,

 

wherein the CRYSTAF peak is determined using at least 5 percent of the cumulative polymer, and if less than 5 percent of the polymer has an identifiable CRYSTAF peak, then the CRYSTAF temperature is 30°

C.;

or

(c) is characterized by an elastic recovery, Re, in percent at 300 percent strain and 1 cycle measured with a compression-molded film of the ethylene/α

-olefin interpolymer, and has a density, d, in grams/cubic centimeter, wherein the numerical values of Re and d satisfy the following relationship when the ethylene/α

-olefin interpolymer is substantially free of a cross-linked phase;

Re>

1481−

1629(d);

or

(d) has a molecular fraction which elutes between 40°

C. and 130°

C. when fractionated using TREF, characterized in that the fraction has a molar comonomer content of at least 5 percent higher than that of a comparable random ethylene interpolymer fraction eluting between the same temperatures, wherein said comparable random ethylene interpolymer has the same comonomer(s) and a melt index, density, and molar comonomer content (based on the whole polymer) within 10 percent of that of the ethylene/α

-olefin interpolymer;

or

(e) is characterized by a storage modulus at 25°

C., G′

(25°

C.), and a storage modulus at 100°

C., G′

(100°

C.), wherein the ratio of G′

(25°

C.) to G′

(100°

C.) is from about 1;

1 to about 10;

1.

5. The thermoplastic vulcanizate of claim 1, wherein the interpolymer has a Mw/Mn from about 1.7 to about 3.5, at least one melting point, Tm, in degrees Celsius, and a density, d, in grams/cubic centimeter, wherein the numerical values of Tm and d correspond to the relationship:

T_m>

−

2002.9+4538.5(d)−

2422.2(d)².

6. The thermoplastic vulcanizate of claim 1, wherein the interpolymer has a Mw/Mn from about 1.7 to about 3.5 and is characterized by a heat of fusion, Δ

H in J/g, and a delta quantity, Δ

T, in degrees Celsius defined as the temperature difference between the tallest DSC peak and the tallest CRYSTAF peak, wherein the numerical values of Δ

T and Δ

H have the following relationships;

Δ

T>

−

0.1299(Δ

H)+62.81 for Δ

H greater than zero and up to 130 J/g,

Δ

T≧

48°

C. for Δ

H greater than 130 J/g,

wherein the CRYSTAF peak is determined using at least 5 percent of the cumulative polymer, and if less than 5 percent of the polymer has an identifiable CRYSTAF peak, then the CRYSTAF temperature is 30°

C.

7. The thermoplastic vulcanizate of claim 1, wherein the interpolymer is characterized by an elastic recovery, Re, in percent at 300 percent strain and 1 cycle measured with a compression-molded film of the interpolymer, and has a density, d, in grams/cubic centimeter, wherein the numerical values of Re and d satisfy the following relationship when the interpolymer is substantially free of a cross-linked phase:

Re>

1481−

1629(d).

8. The thermoplastic vulcanizate of claim 7, wherein the numerical values of Re and d satisfy the following relationship:

Re>

1491−

1629(d).

9. The thermoplastic vulcanizate of claim 7, wherein the numerical values of Re and d satisfy the following relationship:

Re>

1501−

1629(d).

10. The thermoplastic vulcanizate of claim 7, wherein the numerical values of Re and d satisfy the following relationship:

Re>

1511−

1629(d).

11. The thermoplastic vulcanizate of claim 1, wherein the interpolymer comprises at least one molecular fraction having a block index of at least 0.5 and a molecular weight distribution, Mw/Mn, greater than about 1.3.

12. The thermoplastic vulcanizate of claim 1, wherein the interpolymer is characterized by a storage modulus at 25°

C., G′

(25°

C.), and a storage modulus at 100°

C., G′

(100°

C.), wherein the ratio of G′

(25°

C.) to G′

(100°

C.) is from about 1;

1 to about 10;

1.

13. The thermoplastic vulcanizate of claim 1, wherein the α

-olefin is styrene, propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, 1-decene, or a combination thereof.

16. The thermoplastic vulcanizate of claim 1, wherein the interpolymer has a melt index in the range of about 5 to about 500 g/10 minutes measured according to ASTM D-1238, Condition 190°

C./2.16 kg.

17. The thermoplastic vulcanizate of claim 1, wherein the interpolymer is present in the range from about 5% to about 95% by weight of the total composition.

18. The thermoplastic vulcanizate of claim 1, wherein the interpolymer is present in the range from about 5% to about 45% by weight of the total composition.

19. The thermoplastic vulcanizate of claim 1, wherein the polyolefin is a homopolymer.

20. The thermoplastic vulcanizate of claim 1, wherein the polyolefin is a polypropylene.

21. The thermoplastic vulcanizate of claim 1, wherein the polyolefin is a polyethylene.

22. The thermoplastic vulcanizate of claim 1, wherein the vulcanizable elastomer is an ethylene-higher alpha-olefin copolymers or a terpolymer.

23. The thermoplastic vulcanizate of claim 1, wherein the ethylene/α

-olefin multi-block interpolymer;

(a) has a Mw/Mn from about 1.7 to about 2.9, at least one melting point, Tm, in degrees Celsius, and a density, d, in grams/cubic centimeter, wherein the numerical values of Tm and d correspond to the relationship;

T_m>

−

2002.9+4538.5(d)−

2422.2(d)².

2. A thermoplastic vulcanizate comprising or obtained from a reaction mixture comprising:

(i) a vulcanizable elastomer;

(ii) a thermoplastic polyolefin; and

(iii) a crosslinking agent

(iv) an ethylene/α

-olefin multi-block interpolymer, wherein the ethylene/α

-olefin multi-block interpolymer is characterized by (a) having at least one molecular fraction which elutes between 40°

C. and 130°

C. when fractionated using TREF, characterized in that the fraction has a block index of at least 0.5 and up to about 1 and a molecular weight distribution, Mw/Mn, greater than about 1.3;

or (b) an average block index greater than zero and up to about 1.0 and a molecular weight distribution, Mw/Mn, greater than about 1.3.

3. A thermoplastic vulcanizate comprising or obtained from a reaction mixture comprising:

(i) a thermoplastic polyolefin;

(iv) a crosslinking agent; and

(iii) a vulcanizable elastomer which is an ethylene/α

-olefin/diene multi-block interpolymer, wherein the ethylene/α

-olefin/diene multi-block interpolymer is characterized by (a) having at least one molecular fraction which elutes between 40°

C. and 130°

C. when fractionated using TREF, characterized in that the fraction has a block index of at least 0.5 and up to about 1 and a molecular weight distribution, Mw/Mn, greater than about 1.3;

or (b) an average block index greater than zero and up to about 1.0 and a molecular weight distribution, Mw/Mn, greater than about 1.3.

14. The thermoplastic vulcanizate of claim 3, wherein the ethylene/α

-olefin/diene interpolymer an ethylene/propylene/diene (EPDM) copolymer.

15. The thermoplastic vulcanizate of claim 14, wherein the diene is norbornene, 1,5-hexadiene, or a combination thereof.

4. A thermoplastic vulcanizate comprising or obtained from a reaction mixture comprising:

(i) a thermoplastic polyolefin;

(iv) a crosslinking agent; and

(iii) a vulcanizable elastomer which is an ethylene/α

-olefin/diene multi-block interpolymer, wherein the ethylene/α

-olefin/diene multi-block interpolymer;

(a) has a Mw/Mn from about 1.7 to about 3.5, at least one melting point, Tm, in degrees Celsius, and a density, d, in grams/cubic centimeter, wherein the numerical values of Tm and d correspond to the relationship;

T_m>

−

2002.9+4538.5(d)−

2422.2(d)²;

or

(b) has a Mw/Mn from about 1.7 to about 3.5, and is characterized by a heat of fusion, Δ

H in J/g, and a delta quantity, Δ

T, in degrees Celsius defined as the temperature difference between the tallest DSC peak and the tallest CRYSTAF peak, wherein the numerical values of Δ

T and Δ

H have the following relationships;

Δ

T>

−

0.1299(Δ

H)+62.81 for Δ

H greater than zero and up to 130 J/g,

Δ

T≧

48°

C. for Δ

H greater than 130 J/g,

 

wherein the CRYSTAF peak is determined using at least 5 percent of the cumulative polymer, and if less than 5 percent of the polymer has an identifiable CRYSTAF peak, then the CRYSTAF temperature is 30°

C.;

or

(c) is characterized by an elastic recovery, Re, in percent at 300 percent strain and 1 cycle measured with a compression-molded film of the interpolymer, and has a density, d, in grams/cubic centimeter, wherein the numerical values of Re and d satisfy the following relationship when the interpolymer is substantially free of a cross-linked phase;

Re>

1481−

1629(d);

or

(d) has a molecular fraction which elutes between 40°

C. and 130°

C. when fractionated using TREF, characterized in that the fraction has a molar comonomer content of at least 5 percent higher than that of a comparable random interpolymer fraction eluting between the same temperatures, wherein said comparable random interpolymer has the same comonomer(s) and a melt index, density, and molar comonomer content (based on the whole polymer) within 10 percent of that of the interpolymer;

or

(e) is characterized by a storage modulus at 25°

C., G′

(25°

C.), and a storage modulus at 100°

C., G′

(100°

C.), wherein the ratio of G′

(25°

C.) to G′

(100°

C.) is from about 1;

1 to about 10;

1.