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1. WO2013010877 - HETEROPHASIC POLYPROPYLENE WITH LOW CLTE AND HIGH STIFFNESS

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[ EN ]

C L A I M S

Polyolefin composition (PO) comprising

(a) a heterophasic propylene copolymer (HECO) comprising

(al) a polypropylene (PP) being the matrix of the heterophasic propylene copolymer (HECO) and

(a2) an elastomeric propylene copolymer (E),

said heterophasic propylene copolymer (HECO) has an intrinsic viscosity ratio of the xylene cold soluble (XCS) fraction and xylene cold insoluble (XCI) fraction [(XCS)/(XCI)] equal or below 1.6 and

(b) more than 150 to equal or below 800 ppm of a nucleating agent (VP)

selected from the group consisting of vinylcycloalkane polymers, vinylalkane polymers and mixtures thereof.

Polyolefin composition (PO) according to claim 1, wherein the polypropylene (PP) has

(a) a melt flow rate MFR2 (230 °C) of 20 to 300 g/1 Omin,

and/or

(b) a melting temperature of at least 135 °C,

and/or

(c) a comonomer content of equal or below 10 wt.-%, the comonomers are ethylene and/or a C4 to C12 a-olefin.

Polyolefin composition (PO) according to one of the preceding claims, wherein polypropylene (PP) is a propylene homopolymer (H-PP).

Polyolefin composition (PO) according to one of the preceding claims, wherein the total polyolefin composition (PO) and/or the heterophasic propylene copolymer (HECO) has/have

(a) a melt flow rate MFR2 (230 °C) of more than 8 to 300 g/1 Omin, and/or

(b) a comonomer content in the range of 6.0 to 20 wt.-%, the comonomers are ethylene and/or a C4 to C12 a-olefin.

Polyolefm composition (PO) according to one of the preceding claims, wherein

(a) the amount of the elastomeric propylene copolymer (E) within the

heterophasic propylene copolymer (HECO) is 20 to 50 wt.-%, and/or

(b) the elastomeric propylene copolymer (E) has a comonomer content of 15 to 50 wt.-%, the comonomers are ethylene and/or a C4 to C12 a-olefin.

Polyolefm composition (PO) according to one of the preceding claims, wherein the elastomeric propylene copolymer (E) has an intrinsic viscosity (IV) of equal or below 2.5 dl/g, measured as the intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction of the heterophasic propylene copolymer (HECO),

Polyolefm composition (PO) according to one of the preceding claims, wherein the polyolefm composition (PO) comprises up to 30 wt.-% of an inorganic filler.

Polyolefm composition (PO) according to one of the preceding claims, wherein the polyolefm composition (PO) without filler (F) has

(a) flexural modulus of at least 1050 MPa,

and/or

(c) a coefficient of linear thermal expansion (CLTE) performed in a temperature range from -30 to +80°C of not more than 100 μηι/mK.

Automotive article comprising a polyolefm composition (PO) according to one of the preceding claims.

Automotive article according to claim 9, wherein the automotive article is an exterior automotive article.

11. Use of equal or more than 150 to equal or below 800 ppm of a nucleating agent (VP) in a heterophasic propylene copolymer (HECO) to reduce the coefficient of linear thermal expansion (CLTE) performed in a temperature range from -30 to +80°C of said heterophasic propylene copolymer (HECO), said reduction is at least 6 μητ/ηιΚ compared to the same heterophasic propylene copolymer (HECO) but without nucleating agent (VP), said nucleating agent (VP) is selected from the group consisting of vinylcycloalkane polymers, vinylalkane polymers and mixtures thereof.

Process for the preparation of the polyolefin composition (PO) according to one of the preceding claims 1 to 8 comprising the step of

(al) mixing at least the heterophasic propylene copolymer (HECO) with 150 to equal or below 800 ppm of vinylcycloalkane polymer and/or vinylalkane polymer obtaining thereby the polyolefin composition (PO)

or

(a2) producing the heterophasic propylene copolymer (HECO) with a modified catalyst system, the modification is obtained by polymerizing a vinyl compound in the presence of the catalyst system obtaining the modified catalyst system.

Process according to claim 12, wherein the vinyl compound has the formula:

CH2=CH-CHR3R4

wherein R3 and R4 together form a 5- or 6-membered saturated, unsaturated or aromatic ring or independently represent an alkyl group comprising 1 to 4 carbon atoms.

Process according to claim 12, wherein the heterophasic propylene copolymer (HECO) is produced in a multistage process, comprising the steps of

(a) polymerizing in at least one reactor propylene and optionally ethylene and/or a C4 to C12 α-olefin in the presence of the modified catalyst system obtaining thereby the polypropylene (PP),

(b) transferring subsequently the polypropylene (PP) in a further reactor,

(c) polymerizing in at least said further reactor and in the presence of said

polypropylene (PP) propylene and at least one ethylene and/or C4 to C12 a- olefin obtaining thereby the elastomeric propylene copolymer (E), the polypropylene (PP) and the elastomeric propylene copolymer (E) form the heterophasic propylene copolymer (HECO).