Polyolefins composition with low CLTE and reduced occurrence of flow marks

Patent metadata

Field	Value
Publication number	US-9611382-B2
Application number	US-201214002328-A
Country	US
Kind code	B2
Filing date	Mar 2, 2012
Priority date	Mar 3, 2011
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

The invention relates to a novel polyolefin composition having a low coefficient of thermal expansion (CLTE) and having a reduced occurrence of flow marks. The novel polyolefin compositions comprise a heterophasic polypropylene composition, ethylene/1-butene elastomer and an inorganic filler.

First claim

The invention claimed is:

1. A polyolefin composition comprising:
a. 35-90 wt %, based on the weight of the polyolefin composition, of a heterophasic polypropylene composition having a continuous matrix phase and a discontinuous phase, wherein the continuous matrix phase comprises two propylene homopolymers of different MFR2 and wherein the discontinuous phase comprises two ethylene-propylene rubbers with different molecular weight, and wherein the heterophasic polypropylene composition comprises:
i. 10-50 wt %, based on the weight of the heterophasic polypropylene composition, of a first propylene homopolymer (PPH1) having an MFR 2 measured according to ISO 1133 of from 30-80 g/10 min (230° C., 2.16 kg),
ii. 20-65 wt %, based on the weight of the heterophasic polypropylene composition, of a second propylene homopolymer (PPH2) having an MFR 2 measured according to ISO 1133 of from 100-250 g/10 min (230° C., 2.16 kg),
iii. 5-30 wt %, based on the weight of the heterophasic polypropylene composition, of a first xylene cold soluble fraction (XS1) having an intrinsic viscosity IV XS1 of 2.0-3.0 dl/g,
iv. 5-25 wt %, based on the weight of the heterophasic polypropylene composition, of a second xylene cold soluble (XS2) fraction having an intrinsic viscosity IV XS2 of 1.5-2.8 dl/g,

with the proviso that IV XS1 ≠IV XS2 ,
b. 5-40 wt %, based on the weight of the polyolefin composition, of an inorganic filler, and
c. 5-25 wt %, based on the weight of the polyolefin composition, of an ethylene/1-butene elastomer;
wherein the polyolefin composition has a CLTE −30/+80° C.<49 μm/m·K, a CLTE +23/+80° C.<57 μm/m·K, and a flexural modulus>1700 MPa.

2. The polyolefin composition according to claim 1 , wherein the ethylene/1-butene elastomer has a density of from 850-880 kg/m 3 .

3. The polyolefin composition according to claim 1 , wherein the ethylene/1-butene elastomer has an MFR 2 measured according to ISO 1133 of from 0.5-10 g/10 min (190° C., 2.16 kg).

4. The polyolefin composition according to claim 1 , wherein the inorganic filler is selected from the group consisting of talc and wollastonite.

5. The polyolefin composition according to claim 1 , wherein the MFR 2 measured according to ISO 1133 of the polyolefin composition is from 5.0-50 g/10 min (230° C., 2.16 kg).

6. The polyolefin composition according to claim 1 , further comprising at least one alpha-nucleating agent.

7. The polyolefin composition according to claim 6 , wherein the at least one alpha-nucleating agent is selected from the group consisting of aluminum hydroxy-bis[2,4,8,10-tetrakis(1,1-dimethylethyl)-6-hydroxy-12H-dibenzo-[d,g]-dioxa-phosphocin-6-oxidato] containing nucleating agents, sodium-2,2′-methylene-bis(4,6-di-t-butylphenyl)phosphate, aluminium-hydroxy-bis[2,2′-methylene-bis(4,6-di-t-butyl-phenyl)-phosphate], sorbitol based nucleating agents and polymeric nucleating agents.

8. The polyolefin composition according to claim 7 , wherein the at least one alpha nucleating agent is a polymeric nucleating agent selected from the group consisting of vinylcycloalkane polymers and vinylalkane polymers.

9. A molded article comprising a polyolefin composition according to claim 1 .

10. The molded article according to claim 9 , being an injection moulded article.

Assignees

• Kock Cornelia
• Tranninger Michael
• Borealis Ag

Inventors

• Kock Cornelia
• Tranninger Michael

Classifications

• C08L2207/02

  Heterophasic composition · CPC title

• C08L2205/035

  containing four or more polymers in a blend · CPC title

• C08L23/0815

  with aliphatic 1-olefins containing one carbon-to-carbon double bond · CPC title

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title

• C08L23/12 Primary

  Polypropene · CPC title