LOW DENSITY POLYOLEFIN RESINS WITH HIGH DIMENSIONAL STABILITY

• US 20180016428A1
• Filed: 07/13/2017
• Published: 01/18/2018
• Est. Priority Date: 07/18/2016
• Status: Active Grant

• Current Assignee: Equistar Chemicals LP (Lyondellbasell Industries NV)
• Original Assignee: Equistar Chemicals LP (Lyondellbasell Industries NV)
• Inventors: GLENISTER, PETER J., DAMMANN, MICHAEL J., YANG, CHANGLAI
• Granted Patent: US 9,902,846 B2
• Time in Patent Office: Days
• CPC Class Codes: C08K 3/00 Use of inorganic substances as compounding ingredients
• CPC Class Codes: C08L 2205/025 containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
• CPC Class Codes: C08L 23/12 Polypropene
• CPC Class Codes: C08L 23/16 Elastomeric ethene-propene or ethene-propene-diene copolymers, e.g. EPR and EPDM rubbers
• CPC Class Codes: C08L 53/02 of vinyl-aromatic monomers and conjugated dienes

Abstract

The present disclosure generally relates to low density compositions useful for making automotive components, such as molded parts, as well as other articles of manufacture; such compositions comprise (a) a polyolefin comprising polypropylene, a propylene-ethylene block copolymer, or combinations thereof, wherein the polyolefin blend is present in an amount ranging from about 53 wt. % to about 65 wt. %, based on a total weight of the composition; (b) a first elastomer, a second elastomer, and an impact-modifying compatibilizer, wherein the combined weight percent of components (b) ranges from about 27 wt. % to about 32 wt. %, based on the total weight of the composition; (c) a filler present in an amount ranging from about 5 wt. % to about 12 wt. %, based on the total weight of the composition; and (d) an additive package present in an amount ranging from about 0.5 wt. % to about 5 wt. %.

Claims

1. A composition comprising:

(a) a polyolefin comprising polypropylene, a propylene-ethylene block copolymer, or combinations thereof, wherein the polyolefin is present in an amount ranging from about 53 wt. % to about 65 wt. %, based on a total weight of the composition;

(b) a first elastomer, a second elastomer, and an impact-modifying compatibilizer, wherein the combined weight percent of the first elastomer, the second elastomer, and the impact-modifying compatibilizer ranges from about 25 wt. % to about 34 wt. %, based on the total weight of the composition;

(c) a filler present in an amount ranging from about 5 wt. % to about 12 wt. %, based on the total weight of the composition; and

(d) an additive package present in an amount ranging from about 0.5 wt. % to about 5 wt. %, based on the total weight of the composition;

wherein the composition has a density ranging from about 0.90 to about 1.00 g/cm³, an after-bake-mold-shrinkage (0.5 hours, 120°

C.) ranging from about 0.5 percent to about 0.9 percent, a coefficient of linear thermal expansion ranging from about 1 to about 8 (10E-5 mm/mm/°

C.), and a flexural modulus between about 1,200 MPa and about 2,500 MPa.

2. The composition of claim 1, wherein:

(i) the first elastomer comprises an ethylene-based copolymer having a density from about 0.87 g/cm³ to about 0.90 g/cm³, wherein the first elastomer is present in an amount ranging from about 10 wt. % to about 22 wt. %, based on the total weight of the composition;

(ii) the second elastomer comprises an ethylene-based copolymer having a density from about 0.85 g/cm³ to about 0.87 g/cm³, wherein the second elastomer is present in an amount ranging from about 4 wt. % to about 15 wt. %, based on the total weight of the composition; and

(iii) the impact-modifying compatibilizer is present in an amount ranging from about 0.5 wt. % to about 8 wt. %, based on the total weight of the composition,

wherein the combined weight percent of the first elastomer, the second elastomer, and the impact-modifying compatibilizer ranges from about 25 wt. % to about 34 wt. %, based on the total weight of the composition.

3. The composition of claim 2, wherein the ethylene-based copolymer of the first elastomer has a melt flow rate (MFR, ASTM D1238, 190°

C., 2.16 kg) from about 0.4 g/10 min to about 1.1 g/10 min.

4. The composition of claim 3, wherein the ethylene-based copolymer of the first elastomer is selected from an ethylene-butene copolymer, ethylene-hexene copolymer, and an ethylene-octene copolymer.

5. The composition of claim 4, wherein the ethylene-based copolymer of the first elastomer is an ethylene-butene copolymer.

6. The composition of claim 2, wherein the ethylene-based copolymer of the second elastomer has a melt flow rate (MFR, ASTM D1238, 190°

C., 2.16 kg) from about 1 g/10 min to about 1.5 g/10 min.

7. The composition of claim 2, wherein the ethylene-based copolymer of the second elastomer has a melt flow rate (MFR, ASTM D1238, 190°

C., 2.16 kg) from about 5 g/10 min to about 50 g/10 min.

8. The composition of claim 2, wherein the impact-modifying compatibilizer is a styrene-ethylene-butylene-styrene (SEBS) rubber having a melt flow rate (MFR, ASTM D1238, 230°

C., 5 kg) from about 15 g/10 min to about 30 g/10 min.

9. The composition of claim 2, wherein the impact-modifying compatibilizer is a C₂/C₃ rubber having a melt flow rate (MFR, ASTM D1238, 230°

C., 2.16 kg) from about 0.1 g/10 min to about 1.5 g/10 min.

10. The composition of claim 1, wherein the additive package comprises one or more of the following:

an antioxidant;

a mold release;

a scratch reduction additive;

a nucleating agent;

a neutralizer/acid scavenger selected from the group consisting of magnesium aluminum hydroxycarbonate and hydrates thereof; and

stearic acid or a stearate salt.

11. The composition of claim 10, wherein the additive package comprises a nucleating agent, wherein the nucleating agent is hexahydrophthalic acid, a salt thereof, or an anhydride thereof.

12. The composition of claim 1, wherein the composition has a melt flow rate (MFR, ASTM D1238, 230°

C., 2.16 kg) from about 15 g/10 min to about 50 g/10 min.

13. The composition of claim 1, wherein the composition has a density from about 0.90 g/cm³ to about 0.97 g/cm³.

14. The composition of claim 1, wherein the composition has a coefficient of linear thermal expansion (CLTE) from about 5 (10⁻

5 mm/mm/°

C.) to about 8 (10<sup>−

5</sup> mm/mm/°

C.).

15. The composition of claim 1, wherein the composition has a flex modulus greater than about 1,650 MPa and less than about 2,100 MPa.

16. The composition of claim 1, wherein the as-molded shrinkage percentage of the composition is from about 0.4 percent to about 0.8 percent.

17. The composition of claim 16, wherein the as-molded shrinkage percentage of the composition is about 0.6 percent.

18. The composition of claim 1, wherein the after-bake shrinkage percentage of the composition is from about 0.6% to about 1.0%.

19. An article formed from the composition of claim 1.

20. The article of claim 19, wherein the article is a part of an automobile.