EA039749B1 - Polypropylene composition with excellent surface appearance - Google Patents

Abstract

The invention is directed to a heterophasic polypropylene composition (HC) comprising a modified polypropylene composition (mPP), a process for preparing said heterophasic polypropylene composition (HC) and an article comprising said heterophasic polypropylene composition (HC). The invention is further directed to the use of a composition comprising a peroxide (PO) and a crosslinking agent (CA) to reduce tigerskin of a polypropylene composition (PP).

Description

The present invention is directed to a heterophasic polypropylene composition (HC) containing a modified polypropylene composition (mPP), a process for producing said heterophasic polypropylene composition, and an article containing said heterophasic polypropylene composition. The present invention is further directed to the use of a composition containing a peroxide (PO) and a cross-linking agent (CA) to reduce striation (tigerskin) of a polypropylene composition (PP).

Good surface appearance of injection molded parts is a basic prerequisite for many visible and unpainted automotive applications. In this regard, in many cases, the formation of flow marks especially impairs the visual perception of such details, and many efforts have been made to avoid the appearance of flow marks during processing.

One approach to reducing flow marks in automotive exterior compositions is based on the use of peroxides during melt blending and results in excellent surface appearance even under very severe processing conditions. However, this improved surface appearance is often accompanied by reduced tensile properties and reduced impact strength. In particular, the latter is a disadvantage, since a good impact performance is essential for many critical applications in the automotive field.

Accordingly, there is a need in the art for a polypropylene composition useful for making injection molded parts without flow marks while maintaining a high level of impact performance.

Therefore, it is an object of the present invention to provide a polypropylene composition having reduced flow marks and high impact strength after injection molding.

The discovery of the present invention is that a heterophasic system treated with a peroxide and a crosslinker has excellent appearance and impact performance after injection molding.

Accordingly, the present invention provides a heterophasic polypropylene composition (HC) containing a modified polypropylene composition (mPP), wherein said modified polypropylene composition is obtained by treating a polypropylene composition (PP) with a peroxide (PO) and a crosslinking agent (CA), wherein said polypropylene composition contains :

i) a propylene polymer (PP1); and ii) a plastomer (PL) which is a copolymer of ethylene and at least one C ₄ -C ₂₀ α-olefin, wherein said heterophasic polypropylene composition (HC) has an XCS/XHU ratio ranging from 0, 6 to 2.6, where XCS is the content (wt %) of the cold xylene soluble fraction of the heterophasic polypropylene composition (HC) and XHU is the content (wt %) of the hot xylene insoluble fraction of the heterophasic polypropylene composition (HC), and where the mass ratio of propylene polymer (PP1) and plastomer (PL) [w(PP1)/w(PL)] in the modified polypropylene composition (mPP) is greater than 1.0, where w(PP1) is the total amount (in wt.% ) of the propylene polymer (PP1) in the modified polypropylene composition (mPP) and w(PL) is the total amount (wt %) of the plastomer (PL) in the modified polypropylene composition (mPP).

According to one embodiment of the present invention, the heterophasic polypropylene composition (HC) has a hot xylene insoluble fraction (XHU) content in the range of 11.0 to 25.0 wt%.

According to another embodiment of the present invention, the heterophasic polypropylene composition (HC) has a cold xylene soluble fraction (XCS) content, determined according to ISO 16152, equal to or less than 29.0 wt.%.

It is particularly preferred that the heterophasic polypropylene composition (HC) has a melt flow rate MFR2 (230° C., 2.16 kg), determined according to ISO 1133, of at least 10.0 g/10 min.

According to one embodiment of the present invention, the weight ratio of propylene polymer (PP1) and plastomer (PL) [w(PP1)/w(PL)] in the modified polypropylene composition (mPP) is greater than 1.0, more preferably greater than 1.0 to 3 0, even more preferably 1.1 to 1.8, even more preferably 1.1 to 1.4, for example 1.1 to 1.2.

According to one embodiment of the present invention, the polypropylene composition (PP) contains:

i) at least 10.0 wt%, more preferably 20.0 to 80.0 wt%, even more preferably 30.0 to 70.0 wt%, even more preferably 45.0 to 65 .0 wt.%, for example, from 55.0 to 62.0 wt.% of propylene polymer (PP1) and ii) at least 5.0 wt.%, more preferably from 10.0 to 70.0 wt.% , even more preferable

- 1 039749 specifically from 20.0 to 60.0 wt.%, even more preferably from 35.0 to 55.0 wt.%, for example, from 38.0 to

42.0 wt.% plastomer (PL) in relation to the total amount of polypropylene composition (PP).

According to another embodiment of the present invention, the propylene polymer (PP1):

i) is a propylene homopolymer (n-PPI) and/or ii) has an MFR ₂ melt flow index (230° C., 2.16 kg) determined according to ISO 1133 equal to or less than 35.0 g/10 min.

It is particularly preferred that the propylene polymer (PP1) contains:

i) a first polypropylene cut (PP1a) having a melt flow index MFR2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 5.0 to 20.0 g/10 min; and ii) a second polypropylene cut (PP1b) having a melt flow index MFR2 (230° C., 2.16 kg) determined according to ISO 1133 between 30.0 and 65.0 g/10 min.

According to another embodiment of the present invention, the plastomer (PL) is a copolymer of ethylene and 1-butene or 1-octene.

It is particularly preferred that the plastomer (PL) has:

(a) melt flow rate MFR (190° C., 2.16 kg), determined according to ISO 1133, below 30 g/10 min;

(b) a comonomer content relative to the total plastomer weight (PL) in the range of 8.0 to 35.0 mole %; and (c) a density below 0.880 g/cm ³ .

According to one embodiment of the present invention, the peroxide (PO) is an alkyl peroxide or an aryl peroxide, preferably 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.

According to another embodiment of the present invention, the crosslinking agent is a compound of formula (I)

(I) in which M ²⁺ is a divalent metal ion and R ¹ is hydrogen or methyl.

The present invention also provides an article, preferably a molded article, containing the heterophasic polypropylene composition (HC) described above.

The present invention also provides the use of a composition containing a peroxide (PO) and a cross-linking agent (CA) to reduce banding of a polypropylene composition (PP), whereby the heterophasic polypropylene composition (HC) described above is obtained.

Preferably, the banding reduction is performed under the condition that the MSE (Mean Square Error) values are equal to or less than 10.

The present invention also provides a process for the production of a heterophasic composition (HC) as described above, in which a polypropylene composition (PP) containing a propylene polymer (PP1), a plastomer (PL) and optionally a propylene homopolymer (H-PP) is extruded in an extruder in the presence of peroxide (PO) and a cross-linking agent (CA).

Hereinafter, the present invention is described in more detail.

Heterophasic polypropylene composition (HC).

The heterophasic polypropylene composition of the present invention contains a modified polypropylene composition (mPP). Said modified polypropylene composition is obtained by treating a polypropylene composition (PP) with a peroxide (PO) and a crosslinking agent (CA).

Said polypropylene composition (PP) contains a propylene polymer (PP1) and a plastomer (PL).

The heterophasic polypropylene composition (HC) of the present invention should contain a modified polypropylene composition (mPP). In addition, the composition may contain alpha-nucleating agents (NU), inorganic fillers (F) and additives (AD). Accordingly, it is preferred that the modified polypropylene composition (mPP) is at least 80% by weight, more preferably at least 85% by weight, even more preferably at least 90% by weight, for example at least 95% by weight. from a heterophasic polypropylene composition (HC). In one particular embodiment, the heterophasic polypropylene composition (HC) consists of a modified polypropylene composition (mPP) and optional alpha nucleating agents (NU), inorganic fillers (F) and/or additives (AD).

As mentioned above, a modified polypropylene composition (mPP) is obtained by treating a polypropylene composition (PP) with a peroxide (PO) and a crosslinking agent (CA). Preferred peroxides (PO) and crosslinkers (CA) are listed below in the Modified polypropylene composition (mPP) section.

The peroxide (PO) is preferably introduced in the form of a masterbatch. That is, the peroxide (PO) is premixed with the polymeric carrier material. Said polymeric carrier material does not contribute to the improved properties of the heterophasic polypropylene composition (HC). Preferably the polymeric carrier material is polyethylene or polypropylene, the latter being preferred. Typically, the polymeric carrier material is different from propylene polymer (PP1) and plastomer (PL). Preferably, the polymeric carrier material is a propylene homopolymer having a lower melt flow index than propylene polymer (PP1). The amount of said polymeric carrier material is preferably in the range of 1 to 15% by weight, more preferably in the range of 2 to 12% by weight, based on the total weight of the heterophasic polypropylene composition (HC).

Thus, the heterophasic polypropylene composition (HC) preferably contains:

(a) 85 to 99 wt%, more preferably 90 to 98 wt%, even more preferably 95 to 97 wt%, for example 48 to 61 wt%, based on the total weight of the heterophasic polypropylene composition ( HC), modified polypropylene composition (mPP) and (b) from 1 to 15 wt.%, more preferably in the range from 2 to 12 wt.%, even more preferably in the range from 3 to 10 wt.%, for example, in the range from 5 to 9 wt.% in relation to the total weight of the heterophasic polypropylene composition (HC), peroxide (PO) polymer carrier material.

The cross-linking agent (CA) is preferably also introduced in the form of a masterbatch. That is, the crosslinking agent is premixed with the polymeric carrier material. Said polymeric carrier material does not contribute to the improved properties of the heterophasic polypropylene composition (HC). Preferably the polymeric carrier material is polyethylene or polypropylene, the latter being preferred. Typically, the polymeric carrier material is different from propylene polymer (PP1) and plastomer (PL). Preferably, the polymeric carrier material is a propylene homopolymer having a lower melt flow index than propylene polymer (PP1). The amount of said polymeric carrier material is preferably in the range of 1 to 15% by weight, more preferably in the range of 2 to 12% by weight, based on the total weight of the heterophasic polypropylene composition (HC).

Accordingly, the heterophasic polypropylene composition (HC) preferably contains:

(a) 85 to 99 wt%, more preferably 90 to 98 wt%, even more preferably 95 to 97 wt%, for example 48 to 61 wt%, based on the total weight of the heterophasic polypropylene composition ( HC), modified polypropylene composition (mPP);

(b) from 1 to 15 wt.%, more preferably in the range from 2 to 12 wt.%, even more preferably in the range from 3 to 10 wt.%, for example, in the range from 5 to 9 wt.% in relation to the total weight of the heterophasic polypropylene composition (HC), polymeric peroxide carrier material (PO);

(c) from 1 to 15 wt.%, more preferably in the range from 2 to 12 wt.%, even more preferably in the range from 3 to 10 wt.%, for example, in the range from 5 to 9 wt.% in relation to the total weight of the heterophasic polypropylene composition (HC), the polymeric carrier material of the cross-linking agent (CA).

As mentioned above, in addition, the heterophasic polypropylene composition (HC) may contain alpha-nucleating agents (NU), inorganic fillers (F) and/or additives (AD). According to this invention, neither the nucleating agent (NU) nor the filler (F) is an additive (AD). Further, according to the invention, the filler (F) is not an alpha nucleating agent (NU). Accordingly, it is preferable that the heterophasic polypropylene composition (HC) contains up to 5.0 wt.%, preferably from 1.0x10'5 to 4.0 wt.%, more preferably from 2.0x10'5 to 2.0 wt.% in relation to the total weight of the heterophasic polypropylene composition (NS), alpha-nucleating agents (NU), up to 30.0 wt.%, more preferably up to 20.0 wt.%, even more preferably up to 15 wt.% in relation to the total weight of heterophasic polypropylene composition (HC), inorganic fillers (F) and/or up to 8.0 wt.%, preferably from 0.1 to 6.0 wt.%, more preferably from 0.5 to 4.0 wt.% in relation to the total weight of the heterophasic polypropylene composition (HC), additives (AD). Alphanucleating agents (NU), inorganic fillers (F) and additives (AD) are described in more detail below.

Accordingly, the heterophasic polypropylene composition (HC) preferably contains:

(a) 85 to 99 wt%, more preferably 90 to 98 wt%, even more preferably 95 to 97 wt%, for example 48 to 61 wt%, based on the total weight of the heterophasic polypropylene composition ( HC), modified polypropylene composition (mPP);

(b) from 1 to 15 wt.%, more preferably in the range from 2 to 12 wt.%, even more preferably in the range from 3 to 10 wt.%, for example, in the range from 5 to 9 wt.% in relation to the total weight of the heterophasic polypropylene composition (HC), polymeric peroxide carrier material (PO);

(c) from 1 to 15 wt.%, more preferably in the range from 2 to 12 wt.%, even more preferably in the range from 3 to 10 wt.%, for example, in the range from 5 to 9 wt.% in relation to the total weight of the heterophasic polypropylene composition (HC), the polymeric carrier material of the cross-linking agent (CA);

- 3 039749 (d) up to 5.0 wt.%, preferably from 1.0x10-5 to 4.0 wt.%, more preferably from 2.0x10-5 to

2.0 wt.% in relation to the total weight of the heterophasic polypropylene composition (HC), alpha nucleating agents (NU);

(e) up to 30.0 wt.%, more preferably up to 20.0 wt.%, even more preferably up to 15 wt.% in relation to the total weight of the heterophasic polypropylene composition (HC), inorganic fillers (F) and (f) up to 8.0 wt.%, preferably from 0.1 to 6.0 wt.%, more preferably from 0.5 to 4.0 wt.% in relation to the total weight of the heterophasic polypropylene composition (HC), additives (AD) .

Preferably, the heterophasic polypropylene composition (HC) of the present invention has a melt flow rate MFR (230° C., 2.16 kg) determined according to ISO 1133 of at least 10.0 g/10 min, more preferably in the range of 10 0 to 30.0 g/10 min, even more preferably in the range of 10.0 to 20.0 g/10 min, for example in the range of 10.0 to 15.0 g/10 min.

The heterophasic polypropylene composition (HC) has an XCS/XHU ratio in the range of 0.6 to 2.6, more preferably in the range of 0.8 to 1.8, even more preferably in the range of 0.9 to 1.7, e.g. , in the range from 1.0 to 1.5, where XCS is the content (in wt.%) of the cold xylene-soluble fraction of the heterophasic polypropylene composition (HC) and XHU is the content (in wt.%) of the hot xylene-insoluble fraction of the heterophasic polypropylene composition compositions.

Preferably, the heterophasic polypropylene composition (HC) has a hot xylene insoluble fraction (XHU) content in the range of 11.0 to 25.0 wt.%, more preferably in the range of 12.0 to 22.0 wt.%, even more preferably in the range from 15.0 to 20.0 wt.%, for example, in the range from 17.0 to 20.0 wt.%.

Additionally or alternatively to the preceding paragraph, it is preferred that the heterophasic polypropylene composition (HC) has a cold xylene soluble fraction (XCS) content, as determined according to ISO 16152, equal to or less than 29.0% by weight, more preferably in the range of 15.0 to 28.0 wt.%, even more preferably in the range from 18.0 to 25.0 wt.%, for example, in the range from 19.0 to 23.0 wt.%.

It is particularly preferred that the heterophasic polypropylene composition (HC) has an IV(XCS)/IV(XCI) ratio of at least 1.63, more preferably at least 1.70, even more preferably at least 1.85, for example in the range from 1.85 to 2.5, where IV(XCS) is the intrinsic viscosity of IV, determined according to DIN ISO 1628/1 (in decalin at 135°C), xylene-soluble fraction XCS, and IV(XCI) is the intrinsic viscosity of IV , determined according to DIN ISO 1628/1 (in decalin at 135°C), xylene-insoluble fraction XCI.

Further, it is preferred that the intrinsic viscosity IV, determined according to DIN ISO 1628/1 (in decalin at 135° C.), of the cold xylene-soluble XCS fraction of the heterophasic polypropylene composition (HC) is below 2.0 dl/g, more preferably below 1 .7 dl/g, even more preferably below 1.5 dl/g.

In addition, it is preferable that the intrinsic viscosity IV, determined according to DIN ISO 1628/1 (in decalin at 135° C.), of the xylene-insoluble fraction XCI of the heterophasic polypropylene composition (HC) is below 1.5 dl/g, more preferably below 1 .0 dl/g, even more preferably below 0.8 dl/g.

Preferably, the heterophasic polypropylene composition (HC) according to the invention is characterized by a rather high impact resistance. Accordingly, it is preferred that the heterophasic polypropylene composition (HC) has a notched Charpy impact strength, determined according to ISO 179/1eA at 23° C., of at least 20.0 kJ/m ² , more preferably at least 30.0 kJ /m ² , even more preferably at least 50.0 kJ/m ² , for example in the range from 50.0 to 100.0 kJ/m ² .

Additionally or alternatively to the preceding paragraph, it is preferred that the heterophasic polypropylene composition (HC) has a flexural modulus, determined according to ISO 178, of greater than 500 MPa, more preferably in the range of 500 to 1000 MPa, even more preferably in the range of 600 to 800 MPa .

Modified polypropylene composition (mPP).

As stated above, the heterophasic propylene composition (HC) contains a modified polypropylene composition (mPP) obtained by treating a polypropylene composition (PP) with a peroxide (PO) and a crosslinking agent (CA).

Said modified polypropylene composition (mPP) must contain a propylene polymer (PP1) and a plastomer (PL). In a preferred embodiment, the propylene polymer (PP1) and the plastomer (PL) together comprise at least 80 wt.%, more preferably at least 85 wt.%, even more preferably at least 90 wt.%, for example at least 95 wt.% modified polypropylene composition (mPP). In one specific embodiment, the modified polypropylene composition (mPP) consists of a propylene polymer (PP1) and a plastomer (PL).

Peroxide (PO) polymer carrier material, crosslinker polymer carrier material

- 4 039749 agents, alpha-nucleating agents (NU) and additives (AD) are not considered part of the modified polypropylene composition (mPP), but are considered part of the final heterophasic polypropylene composition (HC).

The mass ratio of propylene polymer (PP1) and plastomer (PL) [w(PP1)/w(PL)] in the modified polypropylene composition (mPP) is above 1.0, more preferably is more than 1.0 to 3.0, still more preferably 1.1 to 1.8, even more preferably 1.1 to 1.4, e.g. 1.1 to 1.2, where w(PP1) is the total amount (in wt%) of propylene polymer (PP1) in the modified polypropylene composition (mPP), and w(PL) is the total amount (wt%) of the plastomer (PL) in the modified polypropylene composition (mPP).

Additionally or alternatively to the preceding paragraph, it is preferred that the modified polypropylene composition (mPP) contains at least 10.0 wt.%, more preferably from 20.0 to 80.0 wt.%, even more preferably from 30.0 to 70, 0 wt.%, even more preferably from 45.0 to 65.0 wt.%, for example, from 55.0 to 62.0 wt.% of propylene polymer (PP1) and at least 5.0 wt.%, more preferably from 10.0 to 70.0 wt.%, even more preferably from 20.0 to 60.0 wt.%, even more preferably from 35.0 to 55.0 wt.%, for example, from 38.0 to 42.0 wt.% plastomer (PL) in relation to the total weight of the modified polypropylene composition (mPP).

As can be understood from the wording, the modified polypropylene composition (mPP) is a composition, i.e. a polypropylene composition (PP) that has been chemically treated with a peroxide (PO) and a crosslinker (CA). In this case, a modified polypropylene composition (mPP) is a polypropylene composition (PP) that has been chemically modified by either partial cross-linking of individual polymer chains, branching of individual chains, or development of a preferred dispersed phase morphology by changing the ratio of viscosities of the dispersed phase and the matrix of the polymer composition. A decrease in the content of the cold xylene soluble fraction (XCS), accompanied by an increase in the content of the hot xylene insoluble fraction (HESH), caused by the addition of peroxide and a crosslinking agent, can serve as evidence of a change in the macromolecular level of the system.

As stated above, in order to obtain a modified polypropylene composition (mPP), the polypropylene composition (PP) must be treated with a peroxide (PO) and a cross-linking agent (CA).

Like the modified polypropylene composition (mPP), the polypropylene composition (PP) must also contain a propylene polymer (PP1) and a plastomer (PL). In a preferred embodiment, the propylene polymer (PP1) and the plastomer (PL) together comprise at least 80 wt.%, more preferably at least 85 wt.%, even more preferably at least 90 wt.%, for example at least 95 wt.% of the polypropylene composition (PP). In one specific embodiment, the polypropylene composition (PP) consists of a propylene polymer (PP1) and a plastomer (PL).

Preferably, the polypropylene composition (PP) contains at least 10.0 wt.%, more preferably from 20.0 to 80.0 wt.%, even more preferably from 30.0 to 70.0 wt.%, even more preferably from 45.0 to 65.0 wt.%, for example, from 55.0 to 62.0 wt.% of propylene polymer (PP1) and at least 5.0 wt.%, more preferably from 10.0 to 70.0 wt.%, even more preferably from 20.0 to 60.0 wt.%, even more preferably from 35.0 to 55.0 wt.%, for example, from 38.0 to 42.0 wt.% of the plastomer (PL ) in relation to the total amount of polypropylene composition (PP).

Preferably, the polypropylene composition (PP) is a heterophasic system containing a crystalline matrix, which is a propylene polymer (PP1), and a dispersed phase, which is a plastomer (PL). Accordingly, the propylene polymer (PP1) is preferably a (semi)crystalline propylene polymer (PP1), and the plastomer (PL) is an elastomeric polymer, and the plastomer (PL) is (finely) dispersed in the (semi)crystalline propylene polymer (PP1). In other words, the (semi)crystalline propylene polymer (PP1) constitutes the matrix in which the plastomer (PL) forms inclusions in the matrix, i.e. in (semi)crystalline propylene polymer (PP1). Thus, the matrix contains (finely) dispersed inclusions that are not part of the matrix, and these inclusions contain a plastomer (PL). The term inclusion according to this invention should preferably indicate that the matrix and the inclusion form different phases in the polypropylene composition (PP), said inclusions being visible, for example, using high resolution microscopy such as electron microscopy or atomic force spectroscopy, or using dynamic-mechanical thermal analysis (DMTA). Specifically, in DMTA, the presence of a multiphase structure can be determined by the presence of at least two different glass transition temperatures.

Preferably, the modified polypropylene composition (mPP) has a melt flow rate MFR (230° C., 2.16 kg), determined according to ISO 1133, greater than 9.0 g/10 min, more preferably in the range of 9.0 to 30 g /10 min, even more preferably in the range from 10.0 to 25.0 g/10 min, for example, in the range from 10.0 to 15.0 g/10 min.

- 5 039749

Further, it is preferable that the intrinsic viscosity IV, determined according to DIN ISO

1628/1 (in decalin at 135° C.), the cold xylene soluble fraction XCS of the modified polypropylene composition (mPP) was below 2.0 dl/g, more preferably below 1.7 dl/g, even more preferably below 1.5 dl/g.

In addition, it is preferred that the intrinsic viscosity IV, determined according to DIN ISO 1628/1 (in decalin at 135° C.), of the xylene-insoluble fraction XCI of the modified polypropylene composition (mPP) is below 1.5 dl/g, more preferably below 1 .0 dl/g, even more preferably below 0.8 dl/g.

It is particularly preferred that the ratio IV(XCS)/IV(XCI) of the modified polypropylene composition (mPP) is at least 1.63, more preferably at least 1.70, even more preferably at least 1.90, where IV( XCS) is the intrinsic viscosity IV determined according to DIN ISO 1628/1 (in decalin at 135°C), xylene-soluble fraction XCS and IV(XCI) is the intrinsic viscosity IV determined according to DIN ISO 1628/1 (in decalin at 135 °C), xylene-insoluble fraction XCI.

The individual properties of the propylene polymer (PP1) and plastomer (PL) in the polypropylene composition (PP) can be obtained from the information below.

The peroxide (PO) for modifying the polypropylene composition (PP) is preferably thermally degradable free radical generating substances. More preferably peroxide (PO), ie. the thermally decomposable free radical generating agent is selected from the group consisting of acyl peroxide, alkyl peroxide, hydroperoxide, perester and peroxycarbonate.

The peroxides listed below are particularly preferred.

Acyl peroxides: benzoyl peroxide, 4-chlorobenzoyl peroxide, 3-methoxybenzoyl peroxide and/or methylbenzoyl peroxide.

Alkyl peroxides: allyl tert-butyl peroxide, 2,2-bis-(tert-butylperoxybutane), 2,5-dimethyl-2,5di-(tert-butylperoxy)hexane, 1,1-bis-(tert-butylperoxy)-3 ,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, diisopropylaminomethyl-tert-amyl peroxide, dimethylaminomethyl-tertamyl peroxide, diethylaminomethyl-tert-butyl peroxide, dimethylaminomethyl-tert-butyl peroxide, 1,1-di (tertamylperoxy)cyclohexane, t-amyl peroxide, t-butylcumyl peroxide, t-butyl peroxide and/or 1-hydroxybutyl-n-butyl peroxide.

Perethers and peroxycarbonates: butyl peracetate, cumyl peracetate, cumyl perpropionate, cyclohexyl peracetate, di-tert-butylperadipate, di-tert-butylperacelate, di-tert-butylperglutarate, di-tert-butylperphthalate, di-tert-butylpersebacate, 4-nitrocumylperpropionate, 1-phenylethylperbenzoate, phenylethylnitroperbenzoate , tert-butylcyclo-(2,2,1)heptanepercarboxylate, tert-butyl-4-carbomethoxyperbutyrate, tert-butylcyclobutanepercarboxylate, tert-butylcyclohexylperoxycarboxylate, tert-butylcyclopentylpercarboxylate, tert-butylcyclopropanepercarboxylate, tert-butyldimethylpercinnamate, tert-butyl-2-(2,2 -diphenylvinyl)perbenzoate, tert-butyl-4-methoxyperbenzoate, tert-butylperbenzoate, tert-butylcarboxycyclohexane, tert-butylpernaphthoate, tert-butylperoxyisopropyl carbonate, tert-butylpertoluate, tert-butyl-1-phenylcyclopropylpercarboxylate, tert-butyl-2-propylperpetene-2 -oate, tert-butyl-1-methylcyclopropylpercarboxylate, tert-butyl-4-nitrophenylperacetate, tert-butylnitrophenylperoxycarbamate, tert-butyl-N-succimidoper carboxylate, tert-butylpercrotonate, tert-butylpermaleic acid, tert-butylpermethacrylate, tert-butylperoctoate, tert-butylperoxyisopropylcarbonate, tert-butylperisobutyrate, tert-butylperacrylate and/or tert-butylperpropionate or mixtures of these free radical generating substances.

In a preferred embodiment, the peroxide (PO) is an alkyl peroxide. It is particularly preferred if the peroxide is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

The crosslinking agent (CA) for modifying the polypropylene composition (PP) is preferably a compound containing at least two groups suitable for crosslinking. Accordingly, the crosslinker is preferably a compound containing at least two ethylenically unsaturated functional groups. Non-limiting examples of suitable crosslinking agents are Ν,N'-methylenebisacrylamide, Ν,N'-methylenebismethacrylamide, ethylene glycol divinyl ether, triethylene glycol divinyl ether, cyclohexanediol divinyl ether, triallylamine and/or tetraallyl ammonium salts, tetraallyloxyethane, pentaerythritoltriallyl ether, triethylene glycol divinyl benzene, , diethylenetriamine, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, ethoxylated bis-phenol-A-diacrylate, ethoxylated bis-phenol-A-dimethacrylate , 1,6-hexanediol diacrylate 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, triethylene glycol diacrylate, tetraethylene glycol dimethacrylate, dipentaerythritol pentaacrylate, pentaerythritoltetraacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropantrime taacrylate, cyclopentadiene diacrylate, tris-(2-hydroxyethyl)isocyanurate triacrylate and/or tris-(2-hydroxyethyl)isocyanurate trimethacrylate, triallyl terephthalate, diallyl maleate,

- 6 039749 diallyl fumarate, trivinyl trimellitate, divinyl adipate, diallyl succinate.

Particularly preferably, the cross-linking agent (CA) is a compound of formula (I)

₊ ⁽¹⁾ in which M ²⁺ is a divalent metal ion and R ¹ is hydrogen or methyl.

Preferably, M ²⁺ is selected from the group consisting of Zn ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Ni ²⁺ , Co ²⁺ and Hg ²⁺ . It is particularly preferred that M ^{2+ is} Zn ²⁺ .

Further, it is preferred that R ¹ is hydrogen.

Accordingly, the cross-linking agent (CA) is particularly preferably zinc diacrylate.

In a first embodiment of the method according to the invention, a modified polypropylene composition (mPP) is obtained by extruding a polypropylene composition (PP) containing a propylene polymer (PP1) and a plastomer (PL) in an extruder in the presence of a peroxide (PO) and a crosslinking agent (CA).

If necessary, said modified polypropylene composition (mPP) is then blended (in the melt) with an inorganic filler (F) to form a heterophasic polypropylene composition (HC).

In the second embodiment of the method according to the invention, a polypropylene composition (PP) containing a propylene polymer (PP1) and a plastomer (PL) and optionally an inorganic filler (F) is extruded in an extruder in the presence of a peroxide (PO) and a crosslinking agent (CA) to obtain heterophasic polypropylene composition (HC).

The modification can in particular be carried out by dosing the polypropylene composition (PP) or a mixture of the polypropylene composition and optionally the inorganic filler (F) into a twin screw extruder such as a Prism TSE24 40D, preferably with a temperature profile of 80/200/210/220/ 220/230/230/220/225/220°C and screw speed 300 rpm. A masterbatch in powder form consisting of a peroxide (PO) such as 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, a cross-linking agent (CA) such as zinc diacrylate, and polypropylene is added directly to the extruder, reaching concentrations from 0.001 to 1.0 wt.% peroxide and from 0.05 to 3.0 wt.% cross-linking agent in relation to the mixture. The polymer melt mixture passes through an extruder, then it is discharged and granulated for intensive removal of volatile substances, thus obtaining a modified polypropylene composition (mPP) or a final heterophasic polypropylene composition (HC).

The properties of the propylene polymer (PP1) and plastomer (PL) can be changed by the use of peroxide (PO) and crosslinker (CA). This applies in particular to the intrinsic viscosity and melt flow index of propylene polymer (PP1) and plastomer (PL). In some cases, the melt flow rate MFR (230° C., 2.16 kg) of propylene polymer (PP1) can be increased by using peroxide (PO).

Next, the propylene polymer (PP1) and the plastomer (PL) are described in more detail.

Propylene polymer (PP1).

The propylene polymer may be a propylene copolymer or a propylene homopolymer, the latter being preferred.

In case the propylene polymer is a propylene copolymer, the propylene polymer (PP1) contains monomers copolymerizable with propylene, for example comonomers such as ethylene and/or C ₄ -C ₈ α-olefins, in particular ethylene and/or C ₄ - C ₆ α-olefins, for example 1-butene and/or 1-hexene. Preferably, the propylene polymer (PP1) according to this invention contains, in particular consists of monomers copolymerizable with propylene, from the group consisting of ethylene, 1-butene and 1-hexene. More specifically, the polypropylene polymer (PP1) of this invention contains, in addition to propylene, units derived from ethylene and/or 1-butene. In a preferred embodiment, the propylene polymer (PP1) contains units derived from ethylene and propylene only.

The comonomer content of the propylene polymer (PP1) is in the range of 0.0 to 5.0 mol%, more preferably in the range of 0.0 to 3.0 mol%, even more preferably in the range of 0.0 to 1 .0 mol.%.

It is particularly preferred that the propylene polymer (PP1) is a propylene homopolymer (n-PPI).

In the present invention, the expression propylene homopolymer refers to polypropylene, which is basically, i. at least 99.0 wt.%, more preferably at least 99.5 wt.%, even more preferably at least 99.8 wt.%, for example, at least 99.9 wt.% , consists of propylene units. In another embodiment, only propylene units are detected, ie. only propylene was polymerized.

- 7 039749

Preferably, the propylene polymer (PP1) has a moderate melt flow index. Accordingly, it is preferred that the propylene polymer (PP1) have a melt flow index MFR2 (230° C., 2.16 kg) determined according to ISO 1133 equal to or lower than

35.0 g/10 min, more preferably in the range of 5.0 to 30.0 g/10 min, even more preferably in the range of 15.0 to 25.0 g/10 min, e.g. in the range of 18, 0 to 23.0 g/10 min.

Preferably the propylene polymer (PP1) is isotactic. Accordingly, it is preferable that the propylene polymer (PP1) has a fairly high pentad concentration (mmmm%), i. e. more than 94.1%, more preferably more than 94.4%, for example, from more than 94.4 to 98.5%, even more preferably at least 94.7%, for example, in the range of 94.7-97.5% .

An additional characteristic of the propylene polymer (PP1) is the low amount of propylene misintroductions in the polymer chain, which indicates that the propylene polymer (PP1) is produced in the presence of a Ziegler-Natta catalyst. Accordingly, the propylene polymer (PP1) preferably has a low amount of 2,1-erythroregio defects, i. e. less than or equal to 0.4 mol.%, more preferably less than or equal to 0.2 mol.%, for example, not more than 0.1 mol.%, determined using ¹³ WITH NMR spectroscopy. In a particularly preferred embodiment, no 2,1-erythroregio defects are detected.

Preferably, the propylene polymer (PP1) has a fairly low xylene cold soluble (XCS) content, i. e. the content of cold-soluble xylene (XCS) fraction below 3.1 wt.%. Accordingly, the propylene polymer (PP1) preferably has a cold xylene soluble (XCS) content in the range of 1.0 to 3.0 wt.%, more preferably in the range of 2.0 to 2.8 wt.%, even more preferably in the range from 2.2 to 2.6 wt.%.

Further, the propylene polymer (PP1) is preferably a crystalline propylene homopolymer. The term crystalline indicates that the propylene polymer (PP1) has a fairly high melting point. Accordingly, throughout the invention, the propylene polymer (PP1) is considered to be crystalline unless otherwise indicated. Therefore, the propylene polymer (PP1) preferably has a melting point T _m measured by differential scanning calorimetry (DSC) of at least 160° C., more preferably at least 161° C., even more preferably at least 163° C., for example , in the range from 163 to 167°C.

It is also preferred that the propylene polymer (PP1) has a crystallization temperature T _c measured by differential scanning calorimetry (DSC) equal to or greater than 110°C, more preferably in the range of 110 to 132°C, more preferably in the range of 114 to 130°C.

The propylene polymer (PP1) is preferably characterized by high rigidity. Accordingly, the propylene polymer (PP1) preferably has a rather high flexural modulus. Accordingly, it is preferable that the propylene polymer (PP1) has a flexural modulus according to ISO 178 of at least 1500 MPa, more preferably in the range of 1800 to 3000 MPa, even more preferably in the range of 2000 to 2500 MPa.

Preferably, the propylene polymer (PP1) is obtained by polymerization of propylene in the presence of a Ziegler-Natta catalyst, as described below. More preferably, the propylene polymer (PP1) of this invention is produced by the method detailed below using a Ziegler-Natta catalyst.

The propylene polymer (PP1) may contain two fractions, more preferably two fractions, namely a first polypropylene fraction (PP1a) and a second polypropylene fraction (PP1b). Preferably, the weight ratio between the first polypropylene fraction (PP1a) and the second polypropylene fraction (PP1b) [(PP1a):(PP1b)] is 70:30 to 40:60, more preferably 65:35 to 45:55.

The first polypropylene fraction (PP1a) and the second polypropylene fraction (PP1b) may differ in melt flow rate. In particular, it is preferred that the melt flow rate MFR (230° C., 2.16 kg) of the first polypropylene fraction (PP1a) is lower than the melt flow rate MFR (230° C., 2.16 kg) of the second polypropylene fraction (PP1b).

Preferably the first polypropylene fraction (PP1a) has a melt flow index MFR (230° C., 2.16 kg), determined according to ISO 1133, in the range from 5.0 to 20.0 g/10 min, more preferably in the range from 7, 0 to 15.0 g/10 min, even more preferably in the range of 8.0 to 12.0 g/10 min.

Further preferably, the second polypropylene fraction (PP1b) has an MFR (230° C., 2.16 kg) melt flow rate, determined according to ISO 1133, in the range of 30.0 to 65.0 g/10 min, more preferably in in the range of 40.0 to 60.0 g/10 min, even more preferably in the range of 45.0 to 55.0 g/10 min.

The propylene polymer (PP1) of the present invention may contain additional components. Preferably, however, the propylene polymer (PP1) of the invention contains only the propylene polymer (PP1) as defined in the present invention as polymer components. Accordingly, the amount of propylene polymer (PP1) may not be 100.0 mass% based on the total mass of propylene polymer (PP1). Thus, the remaining part up to 100.0 wt.% can be additional additives known in the prior art. However, this remaining part should be no more than 5.0 wt.%, for example, no more than 3.0 wt.%, in the entire propylene polymer (PP1). For example, the propylene polymer (PP1) of the invention may further contain a small amount of additives selected from the group consisting of antioxidants, stabilizers, inorganic fillers, dyes, nucleating agents, and antistatic additives. In general, they are introduced during the granulation of the powder product obtained by polymerization.

Accordingly, the propylene polymer (PP1) is at least 95.0 wt.%, more preferably at least 97.0 wt.% in the entire propylene polymer (PP1).

In case the propylene polymer (PP1) contains α-nucleating agents, it is preferred that it does not contain β-nucleating agents. These α-nucleating agents are preferably selected from the group consisting of:

(i) salts of monocarboxylic acids and polycarboxylic acids, for example sodium benzoate or aluminum t-butyl benzoate;

(ii) dibenzylidene sorbitol (eg 1,3:2,4-dibenzylidene sorbitol) and C ₁ -C ₈ -alkyl substituted dibenzylidene sorbitol derivatives such as methyldibenzylidene sorbitol, ethyldibenzylidene sorbitol or dimethyldibenzylidene sorbitol (eg 1,3:2,4-di(methylbenzylidene )sorbitol), or nonitol-substituted derivatives such as 1,2,3-trideoxy-4,6:5,7-bis-O-[(4propylphenyl)methylene]nonitol;

(iii) salts of diesters of phosphoric acid, for example sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl)phosphate or aluminum hydroxybis[2,2'-methylene-bis-(4,6- di-tert-butylphenyl)phosphate];

(iv) a vinyl cycloalkane polymer and a vinyl alkane polymer (as discussed in more detail below); and (v) mixtures thereof.

Such additives are commonly commercially available and are described, for example, in the Plastic Additives Handbook, p. ^871-873 , 5th edition, 2001 of Hans Zweifel.

Preferably, the propylene polymer (PP1) contains up to 5.0 wt.% α-nucleating agent. In a preferred embodiment, the propylene homopolymer contains at most 500 ppm, more preferably 0.025 to 200 ppm, more preferably 0.1 to 200 ppm, even more preferably 0.3 to 200 ppm ppm, most preferably 0.3 to 100 ppm α-nucleating agent, particularly selected from the group consisting of dibenzylidene sorbitol (e.g. ,3:2,4-di(methylbenzylidene)sorbitol), or substituted nonitol derivatives such as 1,2,3-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]nonitol , sodium-2,2'-methylenebis-(4,6-ditert-butylphenyl)phosphate, vinylcycloalkane polymer, vinylalkanopolymer and mixtures thereof.

The propylene polymer (PP1) of this invention is preferably produced in the presence of:

(a) a Ziegler-Natta catalyst containing IUPAC Groups 4-6 transition metal compounds (TC), a Group 2 metal compound (MC), and an internal donor (ID), (b) optionally, a co-catalyst (Co), and (c) when need, an external donor (ED).

Preferably, the propylene polymer (PP1) is produced in a sequential polymerization process, further described below, comprising at least two reactors (R1) and (R2), where in the first reactor (R1) the first polypropylene fraction (PP1a) is produced and then transferred to the second reactor (R2) and in the second reactor (R2) the second polypropylene fraction (PP1b) is obtained in the presence of the first polypropylene fraction (PP1a).

The process for producing propylene homopolymer as well as the Ziegler-Natta catalyst are further detailed below.

As already mentioned above, the propylene polymer (PP1) is preferably obtained in a sequential polymerization process.

The term sequential polymerization system indicates that the propylene polymer (PP) is produced in at least two reactors connected in series. Accordingly, this polymerization system comprises at least a first polymerization reactor (R1), a second polymerization reactor (R2), and optionally a third polymerization reactor (R3). The term polymerization reactor indicates that the main polymerization is taking place. Thus, if the process includes two polymerization reactors, this definition does not exclude the possibility that the entire system contains, for example, a prepolymerization stage in the prepolymerization reactor. The term consists of is a closed formulation only in terms of main polymerization reactors.

Preferably, at least one of the two polymerization reactors (R1) and (R2) is a gas phase reactor (GPR). Even more preferably, the second polymerization reactor (R2) and optional third polymerization reactor (R3) are gas phase reactors (GPRs), i. the first gas phase reactor (GPR1) and the second gas phase reactor (GPR2). The gas phase reactor (GPR) of this invention is preferably a fluidized bed reactor, a fast fluidized bed reactor, or a packed bed reactor, or any combination thereof.

Accordingly, the first polymerization reactor (R1) is preferably a slurry reactor (SR), which can be any continuous or metered-stirred batch or loop reactor operating in bulk or in slurry. By weight means polymerization in a reaction medium which contains at least 60% by weight of monomer. According to the present invention, the slurry reactor (SR) is preferably a (bulk) loop reactor (LR). Accordingly, the average concentration of the first fraction (1F) of the propylene polymer (PP1), i.e. the first polypropylene fraction (PP1a) in the polymer slurry inside the loop reactor (LR) is typically 15 to 55 wt. % relative to the total weight of the polymer slurry inside the loop reactor (LR). In one preferred embodiment of the present invention, the average concentration of the first polypropylene fraction (PP1a) in the polymer slurry inside the loop reactor (LR) is from 20 to 55 wt.% and more preferably from 25 to 52 wt.% in relation to the total weight of the polymer suspension inside the loop reactor (LR).

Preferably the propylene homopolymer of the first polymerization reactor (R1), i. e. the first polypropylene fraction (PP1a), more preferably the loop reactor (LR) polymer slurry containing the first polypropylene fraction (PP1a), is directly fed into the second polymerization reactor (R2), i. in the (first) gas phase reactor (GPR1), with no flashing step in between. This type of direct feeding is described in EP 887379 A, EP 887380 A, EP 887381 A and EP 991684 A. By direct feeding is meant a process in which the contents of the first polymerization reactor (R1), i.e. loop reactor (LR), the polymer slurry containing the first polypropylene fraction (PP1a) is sent directly to the gas phase reactor of the next stage.

Alternatively, the propylene homopolymer from the first polymerization reactor (R1), i. e. the first polypropylene fraction (PP1a), more preferably the polymer slurry from the loop reactor (LR) containing the first polypropylene fraction (PP1a), can also be sent to the flash stage or through a pre-concentration step to the second polymerization reactor (R2), i.e. e. into a gas phase reactor (GPR). Accordingly, this indirect feed refers to a process in which the contents of the first polymerization reactor (R1) of the loop reactor (LR), i. the polymer slurry is fed into the second polymerization reactor (R2), into the (first) gas phase reactor (GPR1), through the reaction medium separation unit and with the reaction medium as a gas from the separation unit.

More specifically, the second polymerization reactor (R2) and any subsequent reactor, such as the third polymerization reactor (R3), are preferably gas phase reactors (GPRs). Such gas phase reactors (GPRs) may be any mechanically stirred or fluidized bed reactors. Preferably gas phase reactors (GPRs) comprise a mechanically agitated fluidized bed reactor with gas velocities of at least 0.2 m/s. Thus, it should be understood that the gas phase reactor is a fluidized bed reactor, preferably with a mechanical stirrer.

Thus, in a preferred embodiment, the first polymerization reactor (R1) is a slurry reactor (SR), such as a loop reactor (LR), while the second polymerization reactor (R2) and any possible downstream reactor, such as a third reactor (R3) polymerization are gas phase reactors (GPR). Accordingly, at least two, preferably two polymerization reactors (R1) and (R2) or three polymerization reactors (R1), (R2) and (R3) are used for this process, namely a slurry reactor (SR), such as a loop reactor (LR), and a (first) gas phase reactor (GPR1) and possibly a second gas phase reactor (GPR2) connected in series. If required, a pre-polymerization reactor is located upstream of the slurry reactor (SR).

The Ziegler-Natta catalyst is fed into the first polymerization reactor (R1) and transferred with the polymer (polymer slurry) produced in the first polymerization reactor (R1) to subsequent reactors. If the process also includes a prepolymerization step, it is preferred that all of the Ziegler-Natta catalyst is fed to the prepolymerization reactor. The prepolymerization product containing the Ziegler-Natta catalyst is then transferred to the first polymerization reactor (R1).

The preferred multi-stage process is a loop-gas phase process such as that developed by Borealis A/S, Denmark (known as BORSTAR® technology) described in patent literature such as EP 0887379, WO 92/12182, WO 2004/000899, WO 2004/111095, WO 99/24478, WO 99/24479 or WO 00/68315.

Another suitable slurry gas phase process is the Spheripol® process from Basell.

- 10 039749

Particularly good results are achieved when the temperature in the reactors is carefully chosen.

Accordingly, it is preferable that the operating temperature in the first polymerization reactor (R1) is in the range of 62 to 85°C, more preferably in the range of 65 to 82°C, even more preferably in the range of 67 to 80°C.

Alternatively or additionally to the preceding paragraph, it is preferred that the operating temperature in the second polymerization reactor (R2) and optionally in the third polymerization reactor (R3) is in the range of 62 to 95°C, more preferably in the range of 67 to 92°C.

Preferably, the operating temperature in the second polymerization reactor (R2) is higher than or equal to the operating temperature in the first polymerization reactor (R1). Accordingly, it is preferable that the operating temperature:

(a) in the first reactor (R1) polymerization was in the range from 62 to 85°C, more preferably in the range from 65 to 82°C, even more preferably in the range from 67 to 80°C, for example, from 70 to 80° WITH;

(b) in the second reactor (R2) polymerization was in the range from 75 to 95°C, more preferably in the range from 78 to 92°C, even more preferably in the range from 78 to 88°C, provided that the operating temperature in the second reactor (R2) polymerization is higher than or equal to the operating temperature in the first reactor (R1) polymerization.

Typically, the pressure in the first polymerization reactor (R1), preferably in the loop reactor (LR), is in the range of 2 to 8 MPa (20 to 80 bar), preferably 3 to 7 MPa (30 to 70 bar), for example, 3.5 to 6.5 MPa (35 to 65 bar), while the pressure in the second polymerization reactor (R2), i. in the (first) gas phase reactor (GPR1) and optionally in a subsequent reactor such as the third polymerization reactor (R3), for example in the second gas phase reactor (GPR2), is in the range of 500 kPa to 5 MPa (5 to 50 bar ), preferably 1.5 to 4 MPa (15 to 40 bar).

Preferably, hydrogen is added to each polymerization reactor in order to control the molecular weight, i. melt flow index MFR ₂ .

Preferably, the average residence time in the polymerization reactors (R1) and (R2) is fairly long. In general, the mean residence time (τ) is defined as the ratio of the reaction volume (VR) to the reactor outflow space velocity (Qo) (i.e. VR/Q _o ), i.e. τ = VR/Q _o . In the case of a loop reactor, the reaction volume (VR) is equal to the volume of the reactor.

As mentioned above, the production of propylene homopolymer may include, in addition to the (main) polymerization of propylene homopolymer in at least two polymerization reactors (R1, R2 and possibly R3), before it, prepolymerization in the upstream prepolymerization reactor (PR) from the first polymerization reactor (R1).

Polypropylene (Pre-PP) is produced in the prepolymerization reactor (PR). The prepolymerization is carried out in the presence of a Ziegler-Natta catalyst. According to this embodiment, the Ziegler-Natta catalyst, co-catalyst (Co) and external donor (ED) are introduced at the prepolymerization stage. However, this should not rule out the possibility that, at a later stage, an additional co-catalyst (Co) and/or an external donor (ED) is added to the polymerization process, for example, in the first reactor (R1). In one embodiment, only the Ziegler-Natta catalyst, cocatalyst (Co), and external donor (ED) are added to the prepolymerization reactor (PR) if prepolymerization is used.

The prepolymerization reaction is usually carried out at a temperature of 0 to 60°C, preferably 15 to 50°C, even more preferably 20 to 35°C.

In a preferred embodiment, the prepolymerization is carried out as a bulk slurry polymerization in liquid propylene, i. the liquid phase mainly contains propylene, possibly with inert components dissolved in it. Moreover, according to the present invention, as mentioned above, an ethylene feed is used during the prepolymerization.

Other components can also be added at the prepolymerization stage. Thus, hydrogen can be added in the pre-polymerization step to control the molecular weight of the polypropylene (Pre-PP), as is known in the art. In addition, antistatic additives can be used to prevent the particles from sticking to each other or to the walls of the reactor.

Precise control of prepolymerization conditions and reaction parameters is within the skill of the art.

By virtue of the process conditions defined above, the prepolymerization preferably produces a mixture (M1) of Ziegler-Natta catalyst and polypropylene (Pre-PP) obtained in the prepolymerization reactor (PR). Preferably the Ziegler-Natta catalyst is (finely) dispersed in polypropylene (Pre-PP). In other words, the Ziegler-Natta catalyst particles introduced into the pre-polymerization reactor (PR) break down into smaller fragments that are evenly distributed in the growing polypropylene (Pre-PP). The sizes of the introduced particles of the Ziegler-Natta catalyst, as well as the obtained fragments, are not significant for this

- 11 039749 inventions and are within the competence of experts.

In the case where prepolymerization is not used, propylene and other ingredients such as a Ziegler-Natta catalyst are directly introduced into the first polymerization reactor (R1).

Accordingly, the propylene homopolymer is preferably obtained in a process comprising the following steps, under the above conditions:

(a) in the first polymerization reactor (R1), i. e. in a loop reactor (LR), propylene is polymerized to obtain a first polypropylene fraction (PP1a) of propylene polymer (PP1);

(b) transferring said first polypropylene fraction (PP1a) to a second polymerization reactor (R2);

(c) in the second polymerization reactor (R2), propylene is polymerized in the presence of a first polypropylene fraction (PP1a) to obtain a second polypropylene fraction (PP1b) of a propylene homopolymer, wherein said first polypropylene fraction (PP1a) and said second polypropylene fraction (PP1b) form a propylene polymer (PP1).

The prepolymerization described above can be carried out up to step (a).

According to the invention, the propylene polymer (PP1) is obtained by the above-described multi-stage polymerization process in the presence of a catalyst system containing as component (i) a Ziegler-Natta procatalyst, which contains the transesterification product of a lower alcohol and a phthalic acid ester.

The procatalyst used according to the invention for the production of propylene polymer (PP1) is obtained by:

a) reaction of spray-crystallized or emulsion-cured adduct of MgCl ₂ and C ₁ -C ₂ alcohol with TiCl ₄ ;

b) reaction of the product of step a) with a dialkyl phthalate of formula (I) o

o in which R ¹ and R ² are independently at least C ₅ - alkyl under conditions when transesterification between the specified C ₁ -C ₂ -alcohol and the specified dialkyl phthalate of formula (I) occurs with the formation of an internal donor;

c) washing the product of step b) or

d) optionally reacting the product of step c) with additional TiCl ₄ .

The procatalyst is prepared as defined in patent applications WO 87/07620, WO 92/19653, WO 92/19658 and EP 0491566. The content of these documents is incorporated herein by reference.

First, an adduct of MgCl ₂ and a C1-C ₂ -alcohol of the formula MgCl ₂ -nROH is formed, in which R is methyl or ethyl and n is from 1 to 6. Ethanol is preferably used as the alcohol.

This adduct, which is first melted and then spray crystallized or emulsified, is used as a catalyst support.

In the next step, the spray-crystallized or emulsion-cured adduct of the formula MgCl ₂ -nROH, in which R is methyl or ethyl, preferably ethyl, and n is from 1 to 6, is brought into contact with TiCl 4 to form a titanated carrier, followed by the addition steps into the specified titanized carrier:

(i) a dialkyl phthalate of formula (I) with R ¹ and R ² independently being at least C ₅ alkyl, eg at least C ₈ alkyl; or preferably (ii) a dialkyl phthalate of formula (I) with R ¹ and R ² being the same and being at least C ₅ alkyl, eg at least C ₈ alkyl; or more preferably (iii) a dialkyl phthalate of formula (I) selected from the group consisting of propylhexyl phthalate (PrHP), dioctyl phthalate (DOP), diisodecyl phthalate (DIDP) and ditridecyl phthalate (DTDP), even more preferably the dialkyl phthalate of formula (I) is dioctyl phthalate ( DOP), such as diisooctyl phthalate or diethylhexyl phthalate, in particular diethylhexyl phthalate, to form a first product, by subjecting said first product to suitable transesterification conditions, i.e. temperatures above 110°C, preferably from 100 to 150°C, more preferably from 130 to 150°C, so that the specified methanol or ethanol has undergone transesterification with the specified ester groups of the specified dialkyl phthalate of formula (I) with the formation of preferably at least 80 mol. %, more preferably 90 mol.%, most preferably 95 mol.% dialkyl phthalate of formula (II) about

about

- 12 039749 with R ¹ and R ² being methyl or ethyl, preferably ethyl, the dialkyl phthalate of formula (II) being the internal donor, and recovering said transesterification product as a procatalyst composition (component (i)).

The adduct of the formula MgCl ₂ -nROH, in which R is methyl or ethyl and n is from 1 to 6, is melted in a preferred embodiment and the melt is then preferably introduced by gas into a cooled solvent or cooled gas, whereby the adduct crystallizes in a morphologically advantageous form, such as, for example, described in WO 87/07620.

This crystallized adduct is preferably used as a catalyst support and is reacted with a procatalyst useful in the present invention as described in WO 92/19658 and WO 92/19653.

When the catalyst residue is removed by extraction, an adduct is obtained from the titanated support and the internal donor, in which the group derived from the ester alcohol is changed.

When enough titanium remains on the support, it acts as the active element of the pronatalistic agent.

Otherwise, the titanation is repeated after the above treatment in order to ensure sufficient titanium concentration and thus activity.

Preferably, the procatalyst used according to the invention contains at most 2.5% by weight of titanium, preferably at most 2.2% by weight, and more preferably at most 2.0% by weight. Its donor content is preferably 4 to 12% by weight, and more preferably 6 to 10% by weight.

More preferably, the procatalyst used according to the invention is obtained by using ethanol as the alcohol and dioctyl phthalate (DOP) as the dialkyl phthalate of formula (I) to give diethyl phthalate (DEP) as the internal donor compound.

Even more preferably, the procatalyst used according to the invention is the catalyst described in the examples section, especially using dioctyl phthalate as the dialkyl phthalate of formula (I).

For the production of the propylene polymer (PP1) according to the invention, the catalyst system used preferably contains, in addition to the special Ziegler-Natta procatalyst, an organometallic cocatalyst as component (ii).

Accordingly, it is preferable to select a cocatalyst from the group consisting of trialkylaluminum such as triethylaluminum (TEA), dialkylaluminum chloride and alkylaluminum sesquichloride.

Component (iii) of the catalytic system used is an external donor represented by formulas (IIIa) or (IIIb). Formula (IIIa) is

Si(OCH ₃ ) ₂ R ₂ ⁵ (Sha) in which R ⁵ is a branched alkyl group containing 3 to 12 carbon atoms, preferably a branched alkyl group containing 3 to 6 carbon atoms, or a cycloalkyl group containing 4 up to 12 carbon atoms, preferably a cycloalkyl group containing 5 to 8 carbon atoms.

It is particularly preferred that R ⁵ is selected from the group consisting of isopropyl, isobutyl, isopentyl, t-butyl, t-amyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

Formula (IIIb) is

Si(OCH ₂ CH ₃ ) ₃ (NR ^x R ^y ) (IIIb) in which R ^x and R ^y may be the same or different and represent a hydrocarbon group containing from 1 to 12 carbon atoms.

R ^x and R ^y are independently selected from the group consisting of a linear aliphatic hydrocarbon group containing 1 to 12 carbon atoms, a branched aliphatic hydrocarbon group containing 1 to 12 carbon atoms, and a cyclic aliphatic hydrocarbon group containing 1 to 12 carbon atoms. carbon. It is particularly preferred that R ^x and R ^y are independently selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decanyl, isopropyl, isobutyl, isopentyl, t-butyl, t-amyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

More preferably R ^x and R ^y are the same, even more preferably R ^x and R ^y are an ethyl group.

More preferably, the external donor is a donor of formula (IIIa), such as dicyclopentyldimethoxysilane [Si(OCH ₃ ) ₂ (cyclopentyl) ₂ ], diisopropyldimethoxysilane [Si(OCH ₃ ) ₂ (CH(CH ₃ ) ₂ ) ₂ ].

Most preferably, the external donor is dicyclopentyldimethoxysilane [Si(OCH ₃ ) ₂ (cyclopentyl) ₂ ] (donor D).

In another embodiment, the Ziegler-Natta procatalyst can be modified by polymerizing a vinyl compound in the presence of a catalyst system containing a special Ziegler-Natta procatalyst (component (i)), an external donor (component (iii)) and, optionally, a co-catalyst ( component (ii)), and the vinyl compound has the formula ch ₂ =ch-chr ³ r ⁴ in which R ³ and R ⁴ together form a saturated, unsaturated or aromatic ring with 5 or 6 members, or independently represent an alkyl group containing from 1 up to 4 carbon atoms, and the modified catalyst is used to produce the propylene polymer (PP1) of the invention.

The polymerized vinyl compound can act as an α-nucleating agent.

In connection with the modification of the catalyst, reference is made to international applications WO 99/24478, WO 99/24479 and in particular WO 00/68315, incorporated herein by reference with regard to the reaction conditions associated with the modification of the catalyst, as well as regarding the polymerization reaction.

Plastomer (PL).

The plastomer may be any elastomeric polyolefin, provided that it is chemically different from the elastomeric copolymer (EPR) of ethylene and propylene as defined herein. More preferably the plastomer (PL) is a very low density polyolefin, more preferably a very low density polyolefin polymerized using a single site catalyst, preferably a metallocene catalyst. Typically, the plastomer (PL) is an ethylene copolymer.

As mentioned above, the properties of the plastomer (PL) are changed due to the use of a peroxide (PO) and a crosslinker (CA). That is, the properties defined in this section may differ after a plastomer (PL) has been treated with a peroxide (PO). In particular, the density changes as well as the melt flow index MFR2 (190° C., 2.16 kg). However, the comonomer content does not change.

In a preferred embodiment, the plastomer (PL) has a density below 0.880 g/cm ³ . More preferably, the plastomer density (PL) is equal to or less than 0.870 g/cm ³ , even more preferably in the range of 0.845 to 0.865 g/cm ³ , for example in the range of 0.855 to 0.862 g/cm ³ .

Preferably, the plastomer (PL) has a melt flow index MFR2 (190° C., 2.16 kg), defined according to ISO 1133, below 30 g/10 min, more preferably from 0.1 to 15 g/10 min, even more preferably from 0.1 to 10 g/10 min, for example in the range of 0.1 to 5.0 g/10 min.

Preferably the plastomer (PL) contains units derived from ethylene and C ₄ -C ₂₀ α-olefin.

The plastomer (PL) contains units, preferably consists of units derived from (i) ethylene and (ii) at least another C ₄ -C ₂₀ α-olefin, such as a C ₄ -C _1o α-olefin, more preferably from units derived from (i) ethylene and (ii) at least another α-olefin selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene. It is particularly preferred that the plastomer (PL) contains at least units derived from (i) ethylene and (ii) 1-butene or 1-octene.

In a particularly preferred embodiment, the plastomer (PL) consists of units derived from (i) ethylene and (ii) 1-butene or 1-octene.

The content of the comonomer, for example the content of C ₄ -C ₂₀ α-olefin in the plastomer (PL), is in the range from 8 to 30 mol.%, more preferably in the range from 10 to 25 mol.%, even more preferably in the range from 11 to 23 mol.%, for example, in the range from 12 to 20 mol.%.

In one preferred embodiment, the elastomer (E) is produced with at least one metallocene catalyst. The elastomer (E) can also be made with more than one metallocene catalyst, or it may be a mixture of multiple elastomers made with different metallocene catalysts. In some embodiments, the elastomer (E) is essentially a linear ethylene polymer (substantially linear ethylene polymer, SLEP). SLEP and other metallocene-catalyzed elastomers (E) are known in the art, such as US 5,272,236. These polymers are also commercially available, such as Queo™ plastomers available from Borealis, ENGAGE™ plastomers available from Dow Chemical Co., or EXACT™ polymers from Exxon, or TAFMER™ polymers from Mitsui.

Inorganic filler (F).

An additional possible requirement for the composition of this invention is the presence of an inorganic filler (F).

Preferably the inorganic filler (F) is a mineral filler. It is advantageous if the inorganic filler (F) is sheet silicate, mica or wollastonite. Even more preferably, the inorganic filler (F) is selected from the group consisting of mica, wollastonite, kaolinite, clay minerals, montmorillonite and talc. The most preferred inorganic filler (F) is talc.

It should be understood that the filler (F) has a median particle size (D ₅₀ ) in the range of 0.8 to 20 μm and an upper cut-off point of particle size (D95) in the range of 10 to 20 μm, preferably a median particle size (D ₅₀ ) in the range of 5.0 to 8.0 µm and the upper particle size cutoff (D95) in the range of 12 to 17 µm, more preferably the median particle size (D ₅₀ ) in the range of 5.5 to 7.8 µm and the upper cutoff point size (D ₉₅ ) particles from 13 to 16.5 microns.

- 14 039749

According to this invention, the filler (F) does not belong to the class of alpha nucleating agents (NU) and additives (AD).

The filler (F) is known in the art and is a commercially available product.

Additives (AD).

In addition to the modified polypropylene composition (mPP) and optional inorganic filler (F), the heterophasic polypropylene composition (HC) of the invention may contain additives (AD). Common additives are acid scavengers, antioxidants, colorants, light stabilizers, plasticizers, slip agents, anti-scratch agents, dispersants, processing aids, lubricants, pigments, and the like. As stated above, the inorganic filler (F) is not considered an additive (AD).

Such additives are commercially available and are described in, for example, Plastic Additives Handbook, 6th ^edition 2009 of Hans Zweifel (pages 1141 to 1190).

Moreover, the term additives (AD) of the present invention also includes carrier materials, in particular polymeric carrier materials.

Polymer carrier material.

Preferably, the heterophasic polypropylene composition (HC) of the invention does not contain additional polymer(s) other than the modified polypropylene composition (mPP), i. other than propylene polymer (PP1) and plastomer (PL) in an amount exceeding 15 wt.%, preferably in an amount exceeding 10 wt.%, more preferably in an amount exceeding 9 wt.%, relative to the weight of the heterophasic polypropylene composition (NS). If an additional polymer is present, that polymer is typically a polymeric carrier material for peroxide (PO), crosslinker (CA), and additives (AD). Any additive carrier material (AD) is not counted in the amount of polymeric compounds referred to in the present invention, but is counted in the amount of the respective additive. Accordingly, the present invention distinguishes between a polymeric carrier material for peroxide (PO) and additives (AD). As mentioned above, polymeric peroxide (PO) and crosslinker (CA) carrier materials are counted separately, while additive carrier polymeric material (AD) is considered part of said additives (AD).

The polymeric additive carrier material (AD) is the carrier polymer for uniform distribution in the heterophasic polypropylene composition (HC) of the invention. The polymeric carrier material is not limited to a specific polymer. The polymeric carrier material may be an ethylene homopolymer, an ethylene copolymer derived from ethylene and an α-olefin comonomer such as a C^-Qs α-olefin comonomer, a propylene homopolymer and/or a propylene copolymer derived from propylene and an α-olefin comonomer such as as ethylene and/or C ₄ -C ₈ α-olefin comonomer.

Product.

The heterophasic polypropylene composition (HC) of the present invention is preferably used to produce articles, more preferably molded articles, even more preferably injection molded articles. Even more preferred is the use for washing or dishwasher parts, as well as automotive products, especially automotive interior and exterior trim parts, such as bumpers, side trim, running boards, body panels, spoilers, dashboards, interior trim, etc. .P.

The present invention also provides articles, more preferably molded articles such as injection molded articles containing, preferably containing at least 60 wt.%, more preferably at least 80 wt.%, even more preferably at least 95 wt. .%, for example, consisting of a heterophasic polypropylene composition (HC) according to the invention. Accordingly, the present invention is particularly directed to parts of washing machines or dishwashers, as well as automotive products, especially parts of the interior and exterior trim of cars, such as bumpers, side trim, running boards, body panels, spoilers, instrument panels, interior trim and etc., containing, preferably containing at least 60 wt.%, more preferably at least 80 wt.%, even more preferably at least 95 wt.%, for example, consisting of a heterophasic polypropylene composition (NS) according to the invention .

Application.

The present invention is also directed to the use of a composition containing a peroxide (PO) and a crosslinking agent (CA) to reduce banding of a polypropylene composition (PP), where a heterophasic polypropylene composition (HC) is obtained, said heterophasic polypropylene composition comprising a modified polypropylene composition (mPP) . With regard to the definition of heterophasic polypropylene composition, modified polypropylene composition (mPP) and polypropylene composition, they are described in the above information.

Banding reduction preferably occurs when MSE (Mean Square Error) values are equal to or less than 10, more preferably in the range of 1 to 10, still

- 15 039749 more preferably in the range from 1 to 5 for a heterophasic polypropylene composition (HC).

The present invention is now described in more detail with the help of the following examples.

Examples

1. Definitions/Measurements.

The following definitions of terms and methods of definition apply to the above general description of the invention, as well as to the examples below, unless otherwise specified.

Quantitative determination of polymer microstructure using NMR spectroscopy.

Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the content of comonomers in polymers. Quantitative NMR spectra of ^13C {1H} were recorded in solution using a Bruker Advance III 400 NMR spectrometer operating at 400.15 and ^100.62 MHz for 1H and 13C, respectively. All spectra were recorded using a ¹³ ° C. optimized 10 mm long temperature sensor head at 125° C. using nitrogen gas for all pneumatic equipment. Approximately 200 mg of the material was dissolved in 3 ml of 1,2-tetrachloroethane-d ₂ (TCE-62) together with chromium(III) acetylacetonate (Cr(acac) ₃ ) to give a 65 mM solution of the relaxing agent in a solvent (Singh, G., Kothari, A., Gupta, V., Polymer Testing 28, 5 (2009), 475). To ensure a homogeneous solution, after preparing the initial sample in the heating block, the NMR tube was additionally heated in a rotary oven for at least 1 hour. After being placed in a magnet, the tube was rotated at a frequency of 10 Hz. This mode was chosen primarily for the high resolution and quantitation required for accurate determination of ethylene content. Standard single-pulse excitation was used without the nuclear Overhauser effect, using an optimized tilt angle, recovery latency of 1 s, and a WALTZ16 two-level decoupling system (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson 187 (2007), 225 Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J ., Talarico, G., Macromol RapidCommun. 2007, 28, 1128). Received a total number of transitions 6144 (6k) per spectrum.

Quantitative ¹³ C{1H} NMR spectra were processed, integrated and the corresponding quantitative properties were determined from the integrals using proprietary computer programs. All chemical shifts were indirectly assigned to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. This approach allowed for a comparable comparison even when this structural link was not present. Observed characteristic signals corresponding to the introduction of ethylene (Cheng, HN, Macromolecules, 17 (1984), 1950).

With observed characteristic signals corresponding to 2,1-erythroregiodefects (described in L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev. 2000, 100 (4), 1253, in Cheng, H. N., Macromolecules, 1984, 17, 1950 and in W.-J. Wang and S. Zhu, Macromolecules, 2000, 33 1157), a correction was required for the influence of regio-defects on the determined properties. No characteristic signals corresponding to other types of regiodefects were observed.

Quantification of the comonomer fraction was carried out using the method of Wang et. al. (Wang, W.-J., Zhu, S., Macromolecules, 33 (2000), 1157) by integrating multiple signals over the entire spectral region in ¹³ C{1H} spectra. This method was chosen for its inherent reliability and the ability to take into account the presence of regiodefects when required. The integrable regions were slightly adjusted to increase applicability across the range of comonomer contents encountered.

For systems where only isolated ethylene was observed in the PPEPP sequences, the method of Wang et. al. has been modified to reduce the effect of non-zero center integrals known not to be present. This approach reduces the overestimation of ethylene content for such systems, and has been done by reducing the number of centers used to determine the absolute ethylene content to:

E = 0.5(8ββ + 8βγ + 8βδ + 0.5(8αβ + Say))

Through the use of this set of centers, the corresponding integral equation becomes:

E = 0.5(1 _n + I _G + 0.5(I _c + b)) using the same notation as in Wang et. al. (Wang, W.-J., Zhu, S., Macromolecules, 33 (2000), 1157). The equations used for the absolute content of propylene were not modified.

The molar percentage of the introduced comonomer was calculated from the mole fraction:

E [mol.%] = 100 * fraction of E.

The mass percentage of the introduced comonomer was calculated from the mole fraction:

E [wt%] = 100 * (E fraction * 28.06) / ((E fraction * 28.06) + ((1-E fraction) * 42.08))

The distribution of comonomeric sequences at the triad level was determined using the analysis method of Kakugo et al. (Kakugo, M., Naito, Y., Mizunuma, K., Miyatake, T. Macromolecules, 15 (1982), 1150). This method was chosen for its inherent reliability, and the integration domains were slightly adjusted

- 16 039749 to improve applicability to a wider range of comonomer contents.

Calculation of the melt flow index MFR2 (230°C) of the second polypropylene fraction (PP1b), i.e. polymer fraction obtained in the second reactor (R2), propylene polymer (PP1):

riog(MFP(PPi))-w(PPia) x log(MFP(PPia))

MFR(PPlb) = 1θί where w(PP1a) is the mass fraction [in wt.%] of the first propylene polymer fraction, i.e. the polymer obtained in the first reactor (R1);

w(PP1b) is the mass fraction [in wt.%] of the second propylene polymer fraction, i.e. the polymer obtained in the second reactor (R2);

MFR(PP1a) is the melt flow index MFR2 (230°C) [in g/10 min] of the first propylene polymer fraction, i.e. the polymer obtained in the first reactor (R1);

MFR(PP1) is the melt flow index MFR2 (230°C) [in g/10 min] of the first and second propylene fractions, i.e. polymer obtained in the first and second reactors (R1+R2);

MFR(PP1b) is the calculated melt flow rate MFR2 (230° C.) [in g/10 min] of the second propylene polymer fraction, i.e. polymer obtained in the second reactor (R2).

Quantitative determination of the comonomer content in the plastomer using NMR spectroscopy.

Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the content of comonomers in polymers. Quantitative NMR spectra of ^13C {1H} were recorded in the molten state using a Bruker Advance III 500 NMR spectrometer operating at 500.13 and ^125.76 MHz for 1H and 13C, respectively. All spectra were recorded using a ¹³ C 7 mm optimized rotating magic angle (MAS) measuring head at 150° C. using nitrogen gas for all pneumatic equipment. Approximately 200 mg of material was packed into a zirconium MAS rotor with an outer diameter of 7 mm and rotated at 4 kHz. This mode was chosen mainly for the high sensitivity required for rapid identification and accurate quantification (Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382; Parkinson, M., Klimke, K., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2007; 208:2128.; Castignolles, P., Graf, R ., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer, 50 (2009), 2373). A standard single-pulse excitation was applied using the Overhauser transient nuclear effect with short recovery latency times of 3 s (Pollard, M., Klimke, K., Graf, R., Spiess, HW, Wilhelm, M., Sperber, O., Piel , C., Kaminsky, W., Macromolecules, 2004;3 7:813.; Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382), and the RS-HEPT steaming system (Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239.; Griffin, JM, Tripon, C., Samoson, A., Filip, C., and Brown, SP, Mag. Res. in Chem. 2007, 45, S1, S198). Received a total number of transitions 1024 (1k) per spectrum. This mode was chosen because of its high sensitivity to low comonomer levels. Quantitative ¹³ C{1H} NMR spectra were processed, integrated, and quantitated using custom-made spectral analysis automation software. All chemical shifts were internally assigned to the bulk methylene (δ+) signal at 30.00 ppm. (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201).

Characteristic signals corresponding to comonomer incorporation were observed (J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201) and all contents were calculated relative to all other monomers present in the polymer.

For further information, see Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007), 225 and Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Community. 2007, 28, 1128.

The comonomer content of the plastomer (PL) was measured in a known manner based on Fourier transform infrared spectroscopy (FTIR) calibrated with ¹³ C NMR using a Nicolet Magna 550 IR spectrometer together with Nicolet Omnic FTIR software. Films having a thickness of about 250 µm were obtained by direct pressing from the samples. Similar films were made from calibration samples having a known comonomer content. The content of the comonomer was determined from the spectrum in the range of wave numbers from 1430 to 1100 cm ^-1 . The absorbance was measured as the height of the peak by choosing the so-called short or long baseline or both. A short baseline is drawn from about 1410 to 1320 cm ^-1 through the minimum points, and a long baseline from about 1410 to 1220 cm ^-1 . Calibrations must be performed specifically for each type of baseline. In addition, the comonomer content of the unknown sample must be within the comonomer content range of the calibration samples.

MFR2 (230°C) was measured according to ISO 1133 (230°C, load 2.16 kg).

MFR2 (190°C) was measured according to ISO 1133 (190°C, load 2.16 kg).

Cold Xylene Soluble Fraction (XCS, wt %): The cold xylene soluble fraction (XCS) was determined at 25° C. according to ISO 16152, first edition, 2005-07-01. The part that remains undissolved is the cold xylene insoluble fraction (XCI).

Hot xylene insoluble fraction (XHU, wt.%): The content of the gel is assumed to be identical with the hot xylene insoluble fraction (XHU), which is determined by extracting 1 g of a finely cut polymer sample in 350 ml of xylene in a Soxhlet extractor for 5 hours at a temperature boiling. The remaining amount of solid is dried at 90°C and weighed to determine the amount of insoluble matter.

Intrinsic viscosity is measured according to DIN ISO 1628/1, October 1999 (in decalin at 135°C).

Density is measured according to ISO 1183-187. Samples are obtained by direct pressing according to ISO 1872-2:2007.

Flexural test: Flexural modulus and flexural strength were determined under three-point bending according to ISO 178 on 80x10x4 mm injection molded specimens made according to ISO 294-1:1996.

The notched Charpy impact strength is determined according to ISO 179/1A at 23° C. using injection molded prototypes as described in EN ISO 1873-2 (80x10x4 mm).

Shrinkage: Shrinkage is measured on injection-molded center entry round discs (180 mm diameter, 3 mm thick, 355° flow angle and 5° cut-off). Two samples are formed using two different exposure times under external pressure (10 and 20 s, respectively). The temperature of the melt at the inlet is 260° C. and the average velocity of the flow front in the mold is 100 mm/s. Instrument temperature 40°C, back pressure 60 MPa (600 bar). After keeping the sample at room temperature for 96 hours, both disks are measured for dimensional changes, radial and tangential to the flow direction. Average corresponding values for both disks are presented as final results.

Stream traces.

The propensity to show traces of flows was examined using the method described below. This method is described in detail in WO 2010/149529, which is incorporated herein in its entirety.

The optical measurement system described by Sybille Frank et al. in PPS 25 Intern. Conf. Polym. Proc. soc. 2009 or Proceedings of the SPIE, Volume 6831, p. 68130T-68130T-8 (2008) was used to determine the surface quality.

The method consists of two aspects.

1. Image recording.

The basic principle of the measuring system is to illuminate the plates with a given light source (LED) in a closed environment and to record the image using a charge-coupled camera system. The schematic setup is shown in Fig. one.

2. Image analysis.

The sample is illuminated from one side and the part of the light reflected upwards is deflected by means of two mirrors into a charge-coupled sensor. Such a created image, with gray saturation, is analyzed in a stream. From the recorded gray saturation deviations, the mean square deviation (MSE) is calculated, which provides a quantitative estimate of the surface quality, i.e. the larger the MSE value, the more pronounced the surface defect.

In general, for the same material, the tendency for flow marks increases as the casting speed is increased.

For this evaluation, 440x148x2.8mm VW K50 grit plates and 1.4mm film gate were used and were produced with different fill times of 1, 5, 3, and 6 seconds, respectively.

Additional terms:

Melt temperature 240°C.

The mold temperature is 30°C.

Dynamic pressure 1 MPa abs. (10 bar absolute).

The smaller the MSE value at a given filling time, the less prone to flow trails.

The glass transition temperature Tg and the storage modulus G'(23° C.) are determined by dynamic mechanical analysis according to ISO 6721-7. The measurements are performed in the torsional vibration mode on samples obtained by direct pressing (40x10x1 mm ³ ) from -100 to 150°C with a heating rate of 2°C/min and a frequency of 1 Hz.

2. Examples.

Getting PP1.

Obtaining a catalyst.

First, 0.1 mol of MgCl ₂ -3EtOH was suspended under inert conditions in 250 ml of decane in a reactor at atmospheric pressure. The solution was cooled to a temperature of -15°C and added 300 ml of cold TiCl ₄ while maintaining the temperature at the specified level. Then the temperature of the suspension is slowly

- 18 039749 increased to 20°C. At this temperature, 0.02 mol of dioctyl phthalate (DOP) was added to the suspension. After adding the phthalate, the temperature was raised to 135° C. over 90 minutes and the suspension was left for 60 minutes. Then another 300 ml of TiCl ₄ was added and the temperature was maintained at 135° C. for 120 minutes. After that, the catalyst was filtered from the liquid and washed six times with 300 ml of heptane at 80°C. The solid catalyst component was then filtered and dried. The catalyst and the concept of its preparation are described in general, for example, in patent publications EP 491566, EP 591224 and EP 586390.

The catalyst was further modified (VCH catalyst modification).

ml of mineral oil (Paraffinum Liquidum PL68) was added to a 125 ml stainless steel reactor, then 0.82 g of triethylaluminum (TEAL) and 0.33 g of dicyclopentyldimethoxysilane (donor D) were added under inert conditions at room temperature. After 10 minutes, 5.0 g of the catalyst obtained above (Ti content 1.4 wt%) was added and after another 20 minutes, 5.0 g of vinylcyclohexane (VCH) was added. The temperature was raised to 60°C over 30 minutes and maintained for 20 hours. Finally, the temperature was lowered to 20°C and the concentration of unreacted VCH in the oil/catalyst mixture was analyzed and found to be 200 ppm.

Table 1

Polymerization PP1

PP1 Prepolymerization Time of stay [h] 0.38 Temperature [°C] thirty Co/ED ratio [mol/mol] And Co/TC ratio [mol/mol] 180 Loop reactor (R1) Time of stay [h] 0.35 Temperature [°C] 80 Ratio H ₂ /Cz [mol/kmol] 5 Split [%] 60 MFR [g/10 min] ten XCS [wt%] 1.0 1st gas phase reactor (R2) Time of stay [H] 1.5 Temperature [°C] 80 Pressure [bar] 24 Ratio H ₂ /Cz [mol/kmol] 140 Split [%] 40 MFR [g/10 min] 20 XCS [wt%] 2.0

The PP1 powder was stabilized in a twin screw extruder with a standard additive package containing 0.4 wt% talc (Talc HM 2 from IMI), 0.1 wt% Irganox B 215 FF and 0.07 wt% calcium stearate supplied by Croda.

Obtaining a modified polypropylene composition (mPP).

Example CE1 (comparative).

60.0 wt% PP1 and 40.0 wt% Engage HM 7487 ethylene-butene copolymer from Dow were melt blended in a co-rotating twin screw extruder. The polymer melt mixture was discharged and granulated.

Example CE2 (comparative).

To a mixture of 58.0 wt.% PP1 and 40.0 wt.% Engage HM 7487 ethylene-butene copolymer from Dow was added 2.0 wt. (tert-butylperoxy)hexane with polypropylene in the main feed hopper of a ZSK 18 twin screw extruder (extruder length 40 D) with a temperature profile of 20/190/220/225/230/230/210/200°C and a screw speed of 300 rpm. The polymer melt mixture was discharged and granulated.

Example CE3 (comparative).

To a mixture of 57.0 wt% PP1 and 40.0 wt% Engage HM 7487 ethylene-butene copolymer from Dow was added a 3.0 wt% masterbatch of 5 wt% 2,5-dimethyl-2 ,5-di(tert-butylperoxy)hexane with propylene in the main feed hopper of a twin-screw extruder ZSK 18 (extruder length 40 D) with a temperature profile of 20/190/220/225/230/230/210/200°C and a screw speed of 300 rpm The polymer melt mixture was discharged and granulated.

Example CE4 (comparative).

To a mixture of 56.0 wt.% PP1 and 40.0 wt.% Engage HM 7487 ethylene-butene copolymer from Dow was added 4.0 wt. (tert-butylperoxy)hexane with propylene in the main feed hopper of a ZSK 18 twin screw extruder (extruder length 40 D) with a temperature profile of 20/190/220/225/230/230/210/200°C and a screw speed of 300 rpm. The polymer melt mixture was discharged and granulated.

Example IE4 (according to the invention).

To a mixture of 48.0 wt.% PP1 and 40.0 wt.% Engage HM 7487 ethylene-butene copolymer from Dow was added 2.0 wt. (tert-butylperoxy)hexane with propylene, 2.0 wt.% zinc diacrylate (Dymalink 633 from Total Cray Valley) and 8.0 wt.% propylene homopolymer (HC001) in the main feed hopper of a ZSK 18 twin screw extruder (extruder length 40 D ) with a temperature profile of 20/190/220/225/230/230/210/200°C and a screw speed of 300 rpm. The polymer melt mixture was discharged and granulated.

table 2

Compositions and Properties of Comparative Examples and Inventive Example of _____Modified Polypropylene Composition (mPP)_____

CE1 CE2 SEZ CE4 IE1 PPI [wt%] 60 58 57 56 48 PP2 [wt%] 0 0 0 0 eight PL [wt%] 40 40 40 40 40 POX PP [wt%] 0 2 3 4 2 CA [wt%] 0 0 0 0 2 MFR [g/10 min] 7.0 28.9 34.5 38.5 10.4 Modulus of elasticity in bending [MPa] 1016 759 730 686 631 Bending strength [MPa] 21.8 16.9 16.4 15.3 13.9 Notched Charpy impact strength (+23°C) [kJ / m ² ] 64.8 8.7 10.2 8.6 62.9 Notched Charpy impact strength (-20°C) [kJ / m ² ] 12.4 6.6 8.2 7.4 nd Average mold shrinkage [%] 1D5 1.76 1.81 1.83 nd MSE [-] 225 6.0 2.4 6.5 3.2 XCS [wt%] 41.1 40.4 40.2 40.1 21.7 XHU [wt%] 0.01 0.04 0.04 0.05 18.01 IV(XCS) [dl/g] 2.03 1.74 1.76 1.77 1.45 IV(XCI) [dl/g] 1.70 1.07 0.91 0.93 0.76 IV(XCS)/IV(XCI) [-] 1.19 1.62 1.93 1.90 1.90 DMTA tan5 [°C] -58.1 -56.0 -56.0 -56.0 -56.1 G'(23°C) DMTA [MPa] 419 322 314 288 245

PP2 is a general purpose injection molded polypropylene homopolymer free of anti-skid and anti-block additives and calcium stearate containing 500 ppm precipitated calcium carbonate (Socal U1S1 supplied by Solvay Chemicals) as a particulate acid scavenger, with MFR( 230°C/2.16 kg) 2.0 g/10 min and a density of 905 kg/m ³ .

PL is a commercially available ethylene-butene copolymer Engage HM 7487 from Dow having a density of 0.860 g/cm ³ , an MFR2 (190° C., 2.16 kg) melt flow rate of 2.0 g/10 min and a 1-butene content of 19 .1 mol.%.

POX PP is a masterbatch of 5 wt% 2,5-dimethyl-2,5-di(t-butylperoxy)hexane with propylene.

CA is Dymalink 633 zinc diacrylate from Total Cray Valley.

- 20 039749

CLAIM

Claims (16)

CLAIM 1. A heterophasic polypropylene composition (HC) containing a modified polypropylene composition (mPP) wherein said modified polypropylene composition (mPP) is obtained by chemical treatment of a polypropylene composition (PP) with peroxide (PO) and a crosslinking agent (CA), wherein said polypropylene composition (PP) contains: i) a propylene polymer (PP1); and ii) a plastomer (PL) which is a copolymer of ethylene and at least one C ₄ -C ₂₀ α-olefin, wherein said heterophasic polypropylene composition (HC) has an XCS/XHU ratio ranging from 0, 6 to 2.6, where XCS is the content (wt %) of the cold xylene soluble fraction of the heterophasic polypropylene composition (HC) and XHU is the content (wt %) of the hot xylene insoluble fraction of the heterophasic polypropylene composition (HC); and where the weight ratio of propylene polymer (PP1) and plastomer (PL) [w(PP1)/w(PL)] in the modified polypropylene composition (mPP) is from more than 1.0 to 3.0, where w(PP1) is the total amount (in wt%) of the propylene polymer (PP1) in the modified polypropylene composition (mPP) and w(PL) is the total amount (in wt%) of the plastomer (PL) in the modified polypropylene composition (mPP); where the crosslinking agent is a compound of formula (I) (I) in which M ²⁺ is a divalent metal ion and R ¹ is hydrogen or methyl. 2. Heterophasic polypropylene composition (HC) according to claim 1, having a content of hot xylene insoluble fraction (XHU) in the range from 11.0 to 25.0 wt.%. 3. A heterophasic polypropylene composition (HC) according to claim 1 or 2, having a cold xylene soluble fraction (XCS) content, determined according to ISO 16152, equal to or less than 29.0 wt.%. 4. A heterophasic polypropylene composition (HC) according to any one of the preceding claims, having a melt flow index MFR2 (230° C., 2.16 kg) determined according to ISO 1133 of at least 10.0 g/10 min. 5. The heterophasic polypropylene composition (HC) according to any one of the preceding claims, wherein the weight ratio of propylene polymer (PP1) and plastomer (PL) [w(PP1)/w(PL)] in the modified polypropylene composition (mPP) is between 1, 1 to 1.8, preferably 1.1 to 1.4, for example 1.1 to 1.2. 6. The heterophasic polypropylene composition (HC) according to any one of the preceding claims, wherein the polypropylene composition (PP) comprises: i) from 45.0 to 65.0 wt.% of the propylene polymer (PP1); and ii) from 35.0 to 55.0 wt.% of the plastomer (PL) in relation to the total amount of the polypropylene composition (PP). 7. The heterophasic polypropylene composition (HC) according to any one of the preceding claims, wherein the propylene polymer (PP1) is a propylene homopolymer (n-PPI). 8. The heterophasic polypropylene composition (HC) according to any one of the preceding claims, wherein the propylene polymer (PP1) has a melt flow index MFR ₂ (230° C., 2.16 kg) determined according to ISO 1133 equal to or less than 35.0 g /10 minutes. 9. The heterophasic polypropylene composition (HC) according to any one of the preceding claims, wherein the propylene polymer (PP1) contains: i) a first polypropylene cut (PP1a) having a melt flow index MFR2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 5.0 to 20.0 g/10 min; and ii) a second polypropylene cut (PP1b) having a melt flow index MFR2 (230° C., 2.16 kg) determined according to ISO 1133 between 30.0 and 65.0 g/10 min. 10. The heterophasic polypropylene composition (HC) according to any one of the preceding claims, wherein the plastomer (PL) is a copolymer of ethylene and 1-butene or 1-octene. 11. The heterophasic polypropylene composition (HC) according to any one of the preceding claims, wherein the plastomer (PL) has: (a) melt flow rate MFR2 (190° C., 2.16 kg), determined according to ISO 1133, below 30 g/10 min; (b) a comonomer content relative to the total plastomer weight (PL) in the range of 8.0 to 35.0 mole %; and (c) a density below 0.880 g/cm ³ . 12. The heterophasic polypropylene composition (HC) according to any one of the preceding claims, wherein the peroxide (PO) is an alkyl peroxide. - 21 039749 13. An article intended for washing machines, dishwashers or automotive products, containing a heterophasic polypropylene composition (HC) according to any one of claims 1-12. 14. The use of a composition containing a peroxide (PO) and a crosslinking agent (CA) to reduce the banding of a polypropylene composition (PP), where the banding is the appearance of traces of flows, in which a heterophasic polypropylene composition (HC) is obtained, as defined in any of the preceding paragraphs .1-12. 15. The use of claim 14, wherein the banding reduction is performed under the condition that mean square error (MSE) values are equal to or less than 10. 16. A method for producing a heterophasic propylene composition (HC) according to any one of claims 1 to 12, in which a polypropylene composition (PP) containing a propylene polymer (PP1) and a plastomer (PL) is extruded in an extruder in the presence of a peroxide (PO) and a crosslinking agent. agent (CA).