WO2019056283A1

WO2019056283A1 - Polypropylene composition with good electromagnetic shielding properties

Info

Publication number: WO2019056283A1
Application number: PCT/CN2017/102852
Authority: WO
Inventors: Ben Chen; Henry ZHOU
Original assignee: Borouge Compounding Shanghai Co., Ltd.
Priority date: 2017-09-22
Filing date: 2017-09-22
Publication date: 2019-03-28
Also published as: CN111094431A

Abstract

The present invention relates to a polypropylene composition comprising a) 30 to 54 parts per weight of a propylene polymer (PP) having an MFR2, determined according to ISO1133 at 230℃ and under a load of 2.16 kg of 2.0 to 80 g/10 min； b) 11 to 30 parts per weight of an ethylene copolymer (PE) having an MFR2, determined according to ISO1133 at 190℃ and under a load of 2.16 kg, of 0.5 to 35 g/10 min c) 26 to 50 parts per weight carbon fibers master batch, d) 0.10 to 2.0 parts per weight of a polar modified polypropylene (PMP) wherein the polar modified polypropylene (PMP) comprises groups derived from polar groups in an amount of from 0.5 to 5.0 wt. -％ and an article made therefrom such as a molded or foamed article, preferably an injection molded article, e.g. at least a part of a housing for an electrical apparatus and/or used in automotive applications.

Description

Polypropylene composition with good electromagnetic shielding properties

The present invention relates to a polypropylene composition having good electromagnetic shielding properties an article made therefrom.

Polypropylene compositions having good electromagnetic interference (EMI) shielding are desirable as polypropylene compositions are one of the main materials used for the housings of electrical equipment such as in electrical and electronic applications in general, energy applications and, healthcare, especially automotive applications, e.g. instrument panel carrier.

In order to provide good electromagnetic interference (EMI) shielding the polypropylene composition needs to have a low surface resistivity. Currently carbon black is used whereby a low amount of carbon black does not provide a sufficiently low surface resistivity whereas adding an amount of carbon black sufficient to achieve the desired surface resistivity leads to a deterioration of mechanical properties, e.g. the brittleness is increases as well as the stiffness is reduced.

Hence, a polypropylene composition is required overcoming this conflict of aims.

HLZ：HK

The present invention, thus, provides a polypropylene composition comprising

a) 30 to 54 parts per weight of a propylene polymer (PP) having an MFR₂, determined according to ISO1133 at 230℃ and under a load of 2.16 kg of 2.0 to 80 g/10 min；

b) 11 to 30 parts per weight of an ethylene copolymer (PE) having an MFR₂, determined according to ISO1133 at 190℃ and under a load of 2.16 kg, of 0.5 to 35 g/10 min

c) 26 to 50 parts per weight carbon fiber master batch,

d) 0.1.0 to 2.0 parts per weight of a polar modified polypropylene (PMP) wherein the polar modified polypropylene (PMP) comprises groups derived from polar groups in an amount of from 0.5 to 5.0 wt. -％,

the parts per weight are based on the total parts per weight of components a) , b) , c) and d) .

It has been surprisingly found that the combination of compounds according to the present invention leads to a significantly lower surface resistivity while maintaining or at least not significantly affecting the mechanical properties of the composition. This makes the composition particularly suitable for electrical housings, e.g. in automotive applications.

Propylene polymer (PP)

The propylene polymer (PP) may be a propylene homopolymer, a random propylene copolymer or a heterophasic propylene copolymer.

The propylene polymer (PP) preferably has an MFR₂, determined according to ISO1133 at 230℃ and under a load of 2.16 kg, of 5.0 to 60 g/10 min, more preferably of 5.0 to 40 g/10 min and most preferably of 5.0 to 20 g/10 min.

In case the propylene polymer (PP) is a random copolymer the comonomers are preferably selected from C₂ and/or C₄ to C₂₀ alpha-olefins, more preferably from C₂ and/or C₄ to C₁₀ alpha-olefins and most preferably from C₂, C₄, C₆ and/or C₈ alpha-olefins.

In case the propylene polymer (PP) is a random copolymer the comonomer content is preferably 0.5 to 10 wt. ％based on the total amount of the propylene polymer (PP) , preferably 0.5 o 5.0 wt. ％based on the total amount of the propylene polymer (PP) .

The preparation of propylene homo-and random copolymers is known in the art.

The propylene polymer (PP) is preferably a heterophasic polypropylene (HECO) .

In the following preferred features of the propylene polymer (PP) being a heterophasic polypropylene (HECO) are described unless explicitly mentioned to the contrary.

The heterophasic polypropylene (HECO) is preferably characterized by an MFR₂, determined according to ISO1133 at 230℃ and under a load of 2.16 kg, of 5.0 to 60 g/10 min, more preferably 5.0 to 40 g/10 min and most preferably 5.0 to 20 g/10 min.

Preferably the heterophasic polypropylene (HECO) is characterized by a total comonomer content of 5.0 to 18 wt. ％, more preferably 7.0 to 15 wt. ％and most preferably 10.0 to 15 wt.％.

The heterophasic polypropylene (HECO) is further preferably characterized by a xylene cold solubles (XCS) content of 20 to 36 wt. ％based on the heterophasic polypropylene (HECO) , more preferably 25 to 34 wt. ％and most preferably 28 to 34 wt. ％.

The heterophasic polypropylene (HECO) is preferably characterized by an intrinsic viscosity of the xylene cold solubles (IV) of 2.0 to 4.0 dl/g, preferably 2.3 to 3.5 dl/g and most preferably 2.3 to 2.8 dl/g.

The heterophasic polypropylene (HECO) is preferably characterized by a comonomer content of the xylene cold solubles (XCS) of 30 to 45 wt. ％, more preferably 35 to 40 wt％.

The heterophasic propylene copolymer (HECO) according to this invention preferably comprises

(a) a polypropylene matrix (M) and

(b) an elastomeric copolymer (E) comprising units derived from

- propylene and

- ethylene and/or C₄ to C₂₀ alpha-olefins, more preferably from ethylene and/or C₄ to C₁₀ alpha-olefins and most preferably from ethylene, C₄, C₆ and/or C₈ alpha-olefins, e.g. ethylene and, optionally, units derived from a conjugated diene.

Preferably the propylene content in the heterophasic propylene copolymer (HECO) is 82 to 95 wt.-％, more preferably 85 to 93 wt. -％and most preferably 85 to 90 wt. ％, based on the total heterophasic propylene copolymer (HECO) . The remaining part constitute the comonomers different from propylene (preferably C₂ and/or C₄ to C₂₀ alpha-olefins) , more preferably constitutes ethylene. Thus the heterophasic propylene copolymer (HECO) comprises comonomers, preferably ethylene and/or C₄ to C₁₂ α-olefin, more preferably ethylene, in the range of 5.0 to 18 wt. ％, more preferably 5.0 to 15 wt. ％and most preferably 7.0 to 13 wt. ％.

As defined herein a heterophasic propylene copolymer (HECO) comprises as polymer components only the polypropylene matrix (M) and the elastomeric copolymer (E) .

Throughout the present invention the xylene cold insoluble (XCI) fraction of the heterophasic propylene copolymer (HECO) represents the matrix (M) and optionally the polyethylene whereas the xylene cold soluble (XCS) fraction represents the elastomeric part of the heterophasic propylene copolymer (HECO) , i.e. the elastomeric copolymer (E) .

Accordingly the matrix (M) content, i.e. the xylene cold insoluble (XCI) content, in the heterophasic propylene copolymer (HECO) is preferably in the range of 64 to 88 wt. -％, more preferably in the range of 66 to 75 wt. -％, most preferably 66 to 72 wt. ％.

On the other hand the elastomeric copolymer (E) content, i.e. the xylene cold soluble (XCS) content, in the heterophasic propylene copolymer (HECO) is preferably in the range of 20 to 36 wt. ％, more preferably 25 to 34 wt. ％and most preferably 28 to 34 wt. ％.

The polypropylene matrix (M) is preferably a random propylene copolymer (R) or a propylene homopolymer (H) , the latter especially preferred.

Accordingly the co-monomer content of the polypropylene matrix (M) is equal or below 1.0 wt. -％, yet more preferably not more than 0.8 wt. -％, still more preferably not more than 0.5 wt. -％, like not more than 0.2 wt. -％.

As mentioned above the polypropylene matrix (M) is preferably a propylene homopolymer (H) .

The expression propylene homopolymer used in the instant invention relates to a polypropylene that consists substantially, i.e. of more than 99.7 wt. -％, still more preferably of at least 99.8 wt. -％, of propylene units. In a preferred embodiment only propylene units in the propylene homopolymer are detectable.

In case the polypropylene matrix (M) is a random propylene copolymer (R) it is appreciated that the random propylene copolymer (R) comprises monomers co-polymerizable with propylene, for example co-monomers such as ethylene and/or C₄ to C₂₀ alpha-olefins, in particular ethylene and/or C₄ to C₁₀ alpha-olefins, e.g. ethylene, C₄, C₆ and/or C₈ alpha-olefins. Preferably the random propylene copolymer (R) according to this invention comprises, especially consists of, monomers co-polymerizable with propylene from the group consisting of ethylene, 1-butene and 1-hexene. More specifically the random propylene copolymer (R) of this invention comprises -apart from propylene -units derivable from ethylene and/or 1-butene. In a preferred embodiment the random propylene copolymer (R) comprises units derivable from ethylene and propylene only.

Additionally it is appreciated that the random propylene copolymer (R) has preferably a co-monomer content in the range of more than 0.3 to 1.0 wt. -％, more preferably in the range of more than 0.3 to 0.8 wt. -％, yet more preferably in the range of 0.3 to 0.7 wt. -％.

The term “random” indicates that the co-monomers of the random propylene copolymers (R) and (R) are randomly distributed within the propylene copolymers. The term random is understood according to IUPAC (Glossary of basic terms in polymer science； IUPAC recommendations 1996) .

As will be explained below, the heterophasic propylene copolymer as well as its individual components (matrix and elastomeric copolymer) can be produced by blending different polymer types, e.g. the carrier polymer of the carbon fiber masterbatch. However, it is preferred that the heterophasic propylene copolymer as well as its individual components (matrix and elastomeric copolymer) are produced in a sequential step process, using reactors in serial configuration and operating at different reaction conditions.

Further, it is appreciated that the polypropylene matrix (M) of the heterophasic propylene copolymer (HECO) has a moderate melt flow MFR₂, determined according to ISO1133 under a load of 2.16 kg and at a temperature of 230 ℃. As stated above the melt flow rate MFR₂, determined according to ISO1133 under a load of 2.16 kg and at a temperature of 230 ℃, of the polypropylene matrix (M) equates with the melt flow rate MFR₂ of the xylene cold insoluble (XCI) fraction of the heterophasic propylene copolymer (HECO) . Thus it is preferred that the xylene cold insoluble (XCI) fraction of the heterophasic propylene copolymer (HECO) has a melt flow rate MFR₂ of 20.0 to 150.0 g/10min, more preferably of 25.0 to 110 g/10min, still more preferably of 30.0 to 100 g/10 min, still more preferably of 35.0 to 90 g/10 min.

Preferably, the polypropylene matrix (M) is isotactic. Accordingly it is appreciated that the polypropylene matrix (M) has a rather high pentad concentration, i.e. higher than 80 ％, more preferably higher than 85 ％, yet more preferably higher than 90 ％, still more preferably higher than 92 ％, still yet more preferably higher than 93 ％, like higher than 95 ％.

The second component of the heterophasic propylene copolymer (HECO) is the elastomeric copolymer (E) .

The elastomeric copolymer (E) comprises, preferably consists of, units derivable from (i) propylene and (ii) ethylene and/or C₄ to C₂₀ alpha-olefins, more preferably from ethylene and/or C₄ to C₁₀ alpha-olefins and most preferably from ethylene, C₄, C₆ and/or C₈ alpha-olefins, e.g. ethylene. The elastomeric copolymer (E) may additionally contain units derived from a conjugated diene, like butadiene, or a non-conjugated diene, however it is preferred that the elastomeric copolymer (E) consists of units derivable from (i) propylene and (ii) ethylene and/or C₄ to C₁₂ α-olefins only. Suitable non-conjugated dienes, if used, include straight-chain and branched-chain acyclic dienes, such as 1, 4-hexadiene, 1, 5-hexadiene, 1, 6-octadiene, 5-methyl-1, 4-hexadiene, 3, 7-dimethyl-1, 6-octadiene, 3, 7-dimethyl-1, 7-octadiene, and the mixed isomers of dihydromyrcene and dihydro-ocimene, and single ring alicyclic dienes such as 1, 4-cyclohexadiene, 1, 5-cyclooctadiene, 1, 5-cyclododecadiene, 4-vinyl cyclohexene, 1-allyl-4-isopropylidene cyclohexane, 3-allyl cyclopentene, 4-cyclohexene and 1-isopropenyl-4- (4-butenyl) cyclohexane.

In the present invention the content of units derivable from propylene in the elastomeric copolymer (E) equates with the content of propylene detectable in the xylene cold soluble (XCS) fraction. Accordingly the propylene detectable in the xylene cold soluble (XCS) fraction ranges from 50.0 to 75.0 wt. -％, more preferably from 55.0 to 70.0 wt. -％, and still more preferably from 58.0 to 67.0 wt％. Thus in a specific embodiment the elastomeric copolymer (E) , i.e. the xylene cold soluble (XCS) fraction, comprises from 25.0 to 50.0 wt. -％, more preferably 30.0 to 45.0 wt. -％, and even more preferably 33.0 to 42.0 wt. -％units derivable from ethylene and/or at least another C₄ to C₂₀ α-olefin. Preferably the elastomeric copolymer (E) is an ethylene propylene non-conjugated diene monomer polymer (EPDM) or an ethylene propylene rubber (EPR) , the latter especially preferred, with a propylene and/or ethylene content as defined in this paragraph.

The instant polypropylene composition (PP) contains preferably an alpha-nucleating agent. Even more preferred the present invention is free of beta-nucleating agents. According to the present invention the nucleating agent is understood as a nucleating agent different to the inorganic filler (F) . Accordingly, the nucleating agent is preferably selected from the group consisting of

(i) salts of monocarboxylic acids and polycarboxylic acids, e.g. sodium benzoate or aluminum tert-butylbenzoate, and

(ii) dibenzylidenesorbitol (e.g. 1, 3 : 2, 4 dibenzylidenesorbitol) and C₁-C₈-alkyl-substituted dibenzylidenesorbitol derivatives, such as methyldibenzylidenesorbitol, ethyldibenzylidenesorbitol or dimethyldibenzylidenesorbitol (e.g. 1, 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, and

(iii) salts of diesters of phosphoric acid, e.g. sodium 2, 2'-methylenebis (4, 6, -di-tert-butylphenyl) phosphate or aluminium-hydroxy-bis [2, 2'-methylene-bis (4, 6-di-t-butylphenyl) phosphate] , and

(iv) vinylcycloalkane polymer and vinylalkane polymer , and

(v) mixtures thereof.

Such additives are generally commercially available and are described, for example, in "Plastic Additives Handbook" , 5th edition, 2001 of Hans Zweifel.

Most preferably the alpha-nucleating agent is part of the heterophasic propylene copolymer (HECO) and thus of the polypropylene composition (PP) . Accordingly the alpha-nucleating agent content of the heterophasic propylene copolymer (HECO) is preferably up to 5.0 wt. -％. In a preferred embodiment, the heterophasic propylene copolymer (HECO) contain (s) not more than 3000 ppm, more preferably of 1 to 2000 ppm of a α-nucleating agent, in particular selected from the group consisting of dibenzylidenesorbitol (e.g. 1, 3 : 2, 4 dibenzylidene sorbitol) , dibenzylidenesorbitol derivative, preferably dimethyldibenzylidenesorbitol (e.g. 1, 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, vinylcycloalkane polymer, vinylalkane polymer, and mixtures thereof.

In a preferred embodiment the heterophasic propylene copolymer (HECO) and thus the polypropylene composition (PP) contains a vinylcycloalkane, like vinylcyclohexane (VCH) , polymer and/or vinylalkane polymer, as the α-nucleating agent. Preferably, in this embodiment the heterophasic propylene copolymer (HECO) contains a vinylcycloalkane, like vinylcyclohexane (VCH) , polymer and/or vinylalkane polymer, preferably vinylcyclohexane (VCH) . Preferably the vinylcycloalkane is vinylcyclohexane (VCH) polymer which is introduced into the heterophasic propylene copolymer (HECO) and thus into the polypropylene composition (PP) by the BNT technology. More preferably in this preferred embodiment, the amount of vinylcycloalkane, like vinylcyclohexane (VCH) , polymer and/or vinylalkane polymer, more preferably of vinylcyclohexane (VCH) polymer, in the heterophasic propylene copolymer (HECO) is not more than 500 ppm, more preferably of 1 to 200 ppm, most preferably 5 to 100 ppm, and the amount of vinylcycloalkane, like vinylcyclohexane (VCH) , polymer and/or vinylalkane polymer, more preferably of vinylcyclohexane (VCH) polymer, in the heterophasic propylene copolymer (HECO) is not more than 500 ppm, more preferably of 1 to 200 ppm, most preferably 5 to 100 ppm. Accordingly it is thus preferred that the polypropylene composition (PP) contains not more than 500 ppm, more preferably of 0.1 to 200 ppm, most preferably 0.2 to 100 ppm, of vinylcycloalkane, like vinylcyclohexane (VCH) polymer.

With regard to the BNT-technology reference is made to the international applications WO 99/24478, WO 99/24479 and particularly WO 00/68315. According to this technology a catalyst system, preferably a Ziegler-Natta procatalyst, can be modified by polymerising a vinyl compound in the presence of the catalyst system, comprising in particular the special Ziegler-Natta procatalyst, an external donor and a cocatalyst, which vinyl compound has the formula:

CH₂＝CH-CHR³R⁴

wherein R³ and R⁴ together form a 5-or 6-membered saturated, unsaturated or aromatic ring or independently represent an alkyl group comprising 1 to 4 carbon atoms, and the modified catalyst is used for the preparation of the heterophasic polypropylene according to this invention, i.e. of the heterophasic propylene copolymer (HECO) . The polymerized vinyl compound acts as an α-nucleating agent. The weight ratio of vinyl compound to solid catalyst component in the modification step of the catalyst is preferably of up to 5 (5: 1) , preferably up to 3 (3: 1) most preferably from 0.5 (1: 2) to 2 (2: 1) . The most preferred vinyl compound is vinylcyclohexane (VCH) .

The heterophasic propylene copolymer (HECO) according to this invention is preferably produced in a sequential polymerization process, i.e. in a multistage process known in the art, wherein the corresponding matrix (propylene homopolymer matrix (M) ) is produced at least in one slurry reactor and subsequently the elastomeric copolymer (E) is produced in at least one i.e. one or two, gas phase reactor (s) .

More precisely, the heterophasic propylene copolymer (HECO) is obtained by producing the propylene homopolymer matrix (M) in at least one reactor system, said system comprises at least one reactor, transferring said propylene homopolymer matrix (M) into a subsequent reactor system, said system comprises at least one reactor, where in the presence of the propylene homopolymer matrix (M) the elastomeric propylene copolymer (E) is produced.

Thus, each of the polymerization systems can comprise one or more conventional stirred slurry reactors and/or one or more gas phase reactors. Preferably the reactors used are selected from the group of loop and gas phase reactors and, in particular, the process employs at least one loop reactor and at least one gas phase reactor. It is also possible to use several reactors of each type, e.g. one loop and two or three gas phase reactors, or two loops and one or two gas phase reactors, in series.

Preferably, the process for the preparation of the heterophasic propylene copolymer (HECO) comprises also a prepolymerisation with the chosen catalyst system, as described in detail below, comprising the Ziegler-Natta procatalyst, the external donor and the cocatalyst.

In a preferred embodiment, the prepolymerisation is conducted as bulk slurry polymerization in liquid propylene, i.e. the liquid phase mainly comprises propylene, with minor amount of other reactants and optionally inert components dissolved therein.

The prepolymerisation reaction is typically conducted at a temperature of 0 to 50 ℃, preferably from 10 to 45 ℃, and more preferably from 15 to 40 ℃.

The pressure in the prepolymerisation reactor is not critical but must be sufficiently high to maintain the reaction mixture in liquid phase. Thus, the pressure may be from 20 to 100 bar, for example 30 to 70 bar.

The catalyst components are preferably all introduced to the prepolymerisation step. However, where the solid catalyst component (i) and the cocatalyst (ii) can be fed separately it is possible that only a part of the cocatalyst is introduced into the prepolymerisation stage and the remaining part into subsequent polymerisation stages. Also in such cases it is necessary to introduce so much cocatalyst into the prepolymerisation stage that a sufficient polymerisation reaction is obtained therein.

It is possible to add other components also to the prepolymerisation stage. Thus, hydrogen may be added into the prepolymerisation stage to control the molecular weight of the prepolymer as is known in the art. Further, antistatic additive may be used to prevent the particles from adhering to each other or to the walls of the reactor.

The precise control of the prepolymerisation conditions and reaction parameters is within the skill of the art.

A slurry reactor designates any reactor, such as a continuous or simple batch stirred tank reactor or loop reactor, operating in bulk or slurry and in which the polymer forms in particulate form. "Bulk" means a polymerization in reaction medium that comprises at least 60.0 wt. -％monomer. According to a preferred embodiment the slurry reactor comprises a bulk loop reactor.

"Gas phase reactor" means any mechanically mixed or fluid bed reactor. Preferably the gas phase reactor comprises a mechanically agitated fluid bed reactor with gas velocities of at least 0.2 m/sec.

The particularly preferred embodiment for the preparation of the heterophasic propylene copolymer (HECO) of the invention comprises carrying out the polymerization in a process comprising either a combination of one loop and one or two or three gas phase reactors or a combination of two loops and one or two gas phase reactors.

A preferred multistage process is a slurry-gas phase process, such as developed by Borealis and known as the

technology. In this respect, reference is made to EP 0 887 379 A1, WO 92/12182, WO 2004/000899, WO 2004/111095, WO 99/24478, WO 99/24479 and WO 00/68315. They are incorporated herein by reference.

A further suitable slurry-gas phase process is the

process of Basell.

Preferably, the heterophasic propylene copolymer (HECO) according to this invention are produced by using a special Ziegler-Natta procatalyst in combination with a special external donor, as described below in detail, preferably in the

or in the

-PP process.

One preferred multistage process may therefore comprise the steps of:

- producing a polypropylene matrix in the presence of the chosen catalyst system, as for instance described in detail below, comprising the special Ziegler-Natta procatalyst (i) , an external donor (iii) and the cocatalyst (ii) in a first slurry reactor and optionally in a second slurry reactor, both slurry reactors using the same polymerization conditions,

- transferring the slurry reactor product into at least one first gas phase reactor, like one gas phase reactor or a first and a second gas phase reactor connected in series,

- producing an elastomeric copolymer in the presence of the polypropylene matrix and in the presence of the catalyst system in said at least first gas phase reactor,

- recovering the polymer product for further processing.

With respect to the above-mentioned preferred slurry-gas phase process, the following general information can be provided with respect to the process conditions.

The temperature is preferably from 40 to 110 ℃, preferably between 50 and 100 ℃, in particular between 60 and 90 ℃, with a pressure in the range of from 20 to 80 bar, preferably 30 to 60 bar, with the option of adding hydrogen in order to control the molecular weight in a manner known per se.

The reaction product of the slurry polymerization, which preferably is carried out in a loop reactor, is then transferred to the subsequent gas phase reactor (s) , wherein the temperature preferably is within the range of from 50 to 130 ℃, more preferably 60 to 100 ℃, at a pressure in the range of from 5 to 50 bar, preferably 8 to 35 bar, again with the option of adding hydrogen in order to control the molecular weight in a manner known per se.

The average residence time can vary in the reactor zones identified above. In one embodiment, the average residence time in the slurry reactor, for example a loop reactor, is in the range of from 0.5 to 5 hours, for example 0.5 to 2 hours, while the average residence time in the gas phase reactor generally will be from 1 to 8 hours.

If desired, the polymerization may be effected in a known manner under supercritical conditions in the slurry, preferably loop reactor, and/or as a condensed mode in the gas phase reactor.

According to the invention the heterophasic polypropylene is preferably obtained by a multistage polymerization process, as described above, in the presence of a catalyst system comprising as component (i) a Ziegler-Natta procatalyst which contains a trans-esterification product of a lower alcohol and a phthalic ester.

The procatalyst used according to the invention is prepared by

a) reacting a spray crystallized or emulsion solidified adduct of MgCl₂ and a C₁-C₂ alcohol with TiCl₄

b) reacting the product of stage a) with a dialkylphthalate of formula (I)

wherein R^1’and R^2’are independently at least a C₅ alkyl under conditions where a transesterification between said C₁ to C₂ alcohol and said dialkylphthalate of formula (I) takes place to form the internal donor

c) washing the product of stage b) or

d) optionally reacting the product of step c) with additional TiCl₄.

The procatalyst is produced as defined for example in the patent applications WO 87/07620, WO 92/19653, WO 92/19658 and EP 0 491 566, EP 591224 and EP 586390. The content of these documents is herein included by reference.

First an adduct of MgCl₂ and a C₁-C₂ alcohol of the formula MgCl₂*nROH, wherein R is methyl or ethyl and n is 1 to 6, is formed. Ethanol is preferably used as alcohol.

The adduct, which is first melted and then spray crystallized or emulsion solidified, is used as catalyst carrier.

In the next step the spray crystallized or emulsion solidified adduct of the formula MgCl₂*nROH, wherein R is methyl or ethyl, preferably ethyl and n is 1 to 6, is contacting with TiCl₄ to form a titanised carrier, followed by the steps of

● adding to said titanised carrier

(i) a dialkylphthalate of formula (I) with R^1’and R^2’being independently at least a C₅-alkyl, like at least a C₈-alkyl,

or preferably

(ii) a dialkylphthalate of formula (I) with R^1’and R^2’being the same and being at least a C₅-alkyl, like at least a C₈-alkyl,

or more preferably

(iii) a dialkylphthalate of formula (I) selected from the group consisting of propylhexylphthalate (PrHP) , dioctylphthalate (DOP) , di-iso-decylphthalate (DIDP) , and ditridecylphthalate (DTDP) , yet more preferably the dialkylphthalate of formula (I) is a dioctylphthalate (DOP) , like di-iso-octylphthalate or diethylhexylphthalate, in particular diethylhexylphthalate, to form a first product,

● subjecting said first product to suitable transesterification conditions, i.e. to a temperature above 100 ℃, preferably between 100 to 150 ℃, more preferably between 130 to 150 ℃, such that said methanol or ethanol is transesterified with said ester groups of said dialkylphthalate of formula (I) to form preferably at least 80 mol-％, more preferably 90 mol-％, most preferably 95 mol. -％, of a dialkylphthalate of formula (II)

with R¹ and R² being methyl or ethyl, preferably ethyl,

the dialkylphthalat of formula (II) being the internal donor and

● recovering said transesterification product as the procatalyst composition (component (i) ) .

The adduct of the formula MgCl₂*nROH, wherein R is methyl or ethyl and n is 1 to 6, is in a preferred embodiment melted and then the melt is preferably injected by a gas into a cooled solvent or a cooled gas, whereby the adduct is crystallized into a morphologically advantageous form, as for example described in WO 87/07620.

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

As the catalyst residue is removed by extracting, an adduct of the titanised carrier and the internal donor is obtained, in which the group deriving from the ester alcohol has changed.

In case sufficient titanium remains on the carrier, it will act as an active element of the procatalyst.

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

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

More preferably the procatalyst used according to the invention has been produced by using ethanol as the alcohol and dioctylphthalate (DOP) as dialkylphthalate of formula (I) , yielding diethyl phthalate (DEP) as the internal donor compound.

Still more preferably the catalyst used according to the invention is the catalyst as described in the example section； especially with the use of dioctylphthalate as dialkylphthalate of formula (I) according to WO 92/19658) .

In a further embodiment, as outlined above, the Ziegler-Natta procatalyst can be modified by polymerising a vinyl compound in the presence of the catalyst system, comprising the special Ziegler-Natta procatalyst, an external donor and a cocatalyst, which vinyl compound has the formula:

CH₂＝CH-CHR³R⁴

wherein R³ and R⁴ together form a 5-or 6-membered saturated, unsaturated or aromatic ring or independently represent an alkyl group comprising 1 to 4 carbon atoms, and the modified catalyst is used for the preparation of the heterophasic polypropylene composition according to this invention. The polymerized vinyl compound can act as an α-nucleating agent. This modification is in particular used for the preparation of the heterophasic polypropylene (HECO) .

Concerning the modification of catalyst reference is made to the international applications WO 99/24478, WO 99/24479 and particularly WO 00/68315, incorporated herein by reference with respect to the reaction conditions concerning the modification of the catalyst as well as with respect to the polymerization reaction.

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

Accordingly it is preferred to select the cocatalyst from the group consisting of trialkylaluminium, like triethylaluminium (TEA) , dialkyl aluminium chloride and alkyl aluminium sesquichloride.

Component (iii) of the catalysts system used is an external donor represented by formula (IIIa) or (IIIb) . Formula (IIIa) is defined by

Si(OCH₃) ₂R₂ ⁵ (IIIa)

wherein R⁵ represents a branched-alkyl group having 3 to 12 carbon atoms, preferably a branched-alkyl group having 3 to 6 carbon atoms, or a cyclo-alkyl having 4 to 12 carbon atoms, preferably a cyclo-alkyl having 5 to 8 carbon atoms.

It is in particular preferred that R⁵ is selected from the group consisting of iso-propyl, iso-butyl, iso-pentyl, tert. -butyl, tert. -amyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

Formula (IIIb) is defined by

Si (OCH₂CH₃) ₃ (NR^xR^y) (IIIb)

wherein R^x and R^y can be the same or different, representing a hydrocarbon group having 1 to 12 carbon atoms.

R^x and R^y are independently selected from the group consisting of linear aliphatic hydrocarbon group having 1 to 12 carbon atoms, branched aliphatic hydrocarbon group having 1 to 12 carbon atoms and cyclic aliphatic hydrocarbon group having 1 to 12 carbon atoms. It is in particular preferred that R^x and R^y are independently selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decanyl, iso-propyl, iso-butyl, iso-pentyl, tert. -butyl, tert. -amyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl. More preferably both R^x and R^y are the same, yet more preferably both R^x and R^y are an ethyl group.

More preferably the external donor of formula (IIIb) is diethylaminotriethoxysilane .

Most preferably the external donor is of formula (IIIa) , like dicyclopentyl dimethoxy silane [Si (OCH₃) ₂ (cyclo-pentyl) ₂] or diisopropyl dimethoxy silane [Si (OCH₃) ₂ (CH (CH₃) ₂) ₂] , particularly dicyclopentyl dimethoxy silane [Si (OCH₃) ₂ (cyclo-pentyl) ₂] .

Ethylene copolymer (PE)

A further essential requirement is the present of an ethylene copolymer (PE) . The ethylene copolymer (PE) is (chemically) different to the elastomeric copolymer (E) of the heterophasic polypropylene (HECO) .

Further the ethylene copolymer (PE) , is featured by a specific melt flow rate, namely by a melt flow rate MFR₂, determined according to ISO 1133 under a load of 2.16 kg and at a temperature of 190℃, in the range of 0.1 to 45.0 g/10 min, more preferably in the range of 0.5 to 35 g/10 min., even more preferably in the range of 1 to 20 g/10min.

Preferably the ethylene copolymer (PE) , is a copolymer containing as a major part units derivable from ethylene. Accordingly it is appreciated that the ethylene copolymer (PE) , comprises at least 50.0 wt. -％units derivable from ethylene, more preferably at least 55.0 wt. -％of units derived from ethylene. Thus, it is appreciated that the ethylene copolymer (PE) , comprises 50.0 to 70.0 wt. -％, more preferably 55.0 to 65 wt. -％, units derivable from ethylene. The comonomers present in the ethylene copolymer (PE) , are C₄ to C₂₀ alpha-olefins, like 1-butene, 1-hexene and 1-octene, the latter especially preferred. Accordingly in one specific embodiment the ethylene copolymer (PE) , is an ethylene-1-octene polymer with the amounts given in this paragraph.

Suitable ethylene copolymers (PE) are commercially available, such as an elastomer copolymer of ethylene and octane, “Engage 8200” of Dow Chemical Pacific Ltd. (Hongkong) .

Carbon fiber masterbatch

The carbon fiber masterbatch usually comprises 25-50 wt％carbon fibers, preferably the carbon fiber masterbatch comprises 25-50 wt％carbon fibers and 50-75wt％of a polypropylene, usually a propylene homopolymer as carrier for the carbon fiber, based on 100％total weight of the masterbatch. Preferably, the masterbatch comprises 30-45％carbon fiber and 55-70％of the polyproplyne, preferably propylene homopolymer, carrier.

The carbon fibers have preferably an average length of from 0.5 to 30 mm, more preferably from 1.0 to 20 mm, for example 2.0 to 15 mm.

The carbon fibers preferably have an average diameter of from 1.0 to 30 μm, more preferably from 2.0 to 25 μm and most preferably from 3.0 to 15 μm.

Preferably, carbon fibers have an average length of from 0.5 to 30 mm and an average diameter of from 1.0 to 30 μm, more preferably an average length of from 1.0 to 20 mm and an average diameter of from 2.0 to 25 μm and most preferably an average length of from 2.0 to 15 mm and an average diameter of from 3.0 to 15 μm.

The carbon fibers are preferably free of any metal coatings.

The masterbatch has a MFR_2, measured according to ISO1133 at a temperature of 230℃ and a load of 2.16kg, of 0.5 to 20 g/10min. preferably of 1 to 10 g/10min. more preferably an MFR₂ of 1 to 5 g/10min.

The propylene homopolymer preferably used as the carrier is usually a regular propylene homopolymer.

Polar modified polypropylene (PMP)

In order to achieve an easier and more uniform dispersion of the carbon fibers (CF) the polypropylene composition comprises a specific coupling agent.

The coupling agent according to this invention is a specific polar modified polypropylene (PMP) .

The polar modified polypropylene (PMP) comprises groups derived from polar groups in an amount of from 1 to 5 wt. -％. In the following the polypropylene of the polar modified polypropylene (PMP) will be defined more precisely which is subsequently modified to the polar modified polypropylene (PMP) as explained in detail below.

The polypropylene of the polar modified polypropylene (PMP) is preferably a propylene homopolymer or a random propylene copolymer, like a copolymer of (i) propylene and (ii) ethylene and/or C₄ to C₁₂ alpha-olefins, preferably from (i) propylene and (ii) an alpha-olefin selected from the group consisting of ethylene, 1-butene, 1-hexene, and 1-octene.

Preferably, the comonomer content based on the total amount of the random propylene copolymer is in the range of 1.0 to 7.5 wt. -％, more preferably in the range of 4.0 to 7.0 wt. -％.

In one embodiment, the polar modified polypropylene (PMP) is a modified random propylene copolymer, wherein said random propylene copolymer comprises ethylene as the only comonomer unit.

Additionally, it is appreciated that the random propylene copolymer of the polar modified polypropylene (PMP) has a melting temperature T_m in the range of 125 to 140 ℃, more preferably ranges from 128 to 138 ℃ and most preferably ranges from 131 to 136 ℃. The melting temperature given in this paragraph is the melting temperature of the non-modified random propylene copolymer.

Additionally or alternatively, the random propylene copolymer of the polar modified polypropylene (PMP) , i.e. the non-modified random propylene copolymer, has a melt flow rate MFR₂, determined according to ISO 1133 at 190℃ and under a load of 2.16 kg, in the range from 1 to 500 g/10min, preferably in the range of 20 to 150 g/10min, more preferably in the range of 1 to 100 g/10min.

It is appreciated that the polar modified polypropylene (PMP) comprises groups derived from polar groups. In this context, preference is given to polar modified polypropylene (PMP) comprising groups derived from polar compounds, in particular selected from the group consisting of acid anhydrides, carboxylic acids, carboxylic acid derivatives, primary and secondary amines, hydroxyl compounds, oxazoline and epoxides, and also ionic compounds.

Specific examples of the said polar groups are unsaturated cyclic anhydrides and their aliphatic diesters, and the diacid derivatives. In particular, one can use maleic anhydride and compounds selected from C₁ to C₁₀ linear and branched dialkyl maleates, C₁ to C₁₀ linear and branched dialkyl fumarates, itaconic anhydride, C₁ to C₁₀ linear and branched itaconic acid dialkyl esters, maleic acid, fumaric acid, itaconic acid and mixtures thereof.

In terms of structure, the polar modified polypropylene (PMP) is preferably selected from graft or block copolymers preferably of the above defined polypropylene, like the above defined random propylene copolymer for the polar modified polypropylene (PMP) .

Preferably the polar modified polypropylene (PMP) , i.e. the coupling agent, is a polypropylene, like the random propylene copolymer for the polar modified polypropylene (PMP) as defined above in the section, grafted with such polar group.

Particular preference is given to using a polypropylene, like the random propylene copolymer for the polar modified polypropylene (PMP) as defined above in the section, grafted with maleic anhydride as the polar modified polypropylene (PMP) , i.e. the coupling agent.

In one embodiment, the polar modified polypropylene (PMP) is a random propylene copolymer as defined above grafted with maleic anhydride. Thus in one specific preferred embodiment the polar modified polypropylene (PMP) is a random propylene ethylene copolymer grafted with maleic anhydride, more preferably wherein the ethylene content based on the total amount of the random propylene ethylene copolymer is in the range of 1.0 to 7.5 wt. -％, more preferably in the range of 4.0 to 7.0 wt. -％.

Required amounts of groups deriving from polar groups in the polar modified polypropylene (PMP) are preferably from 0.5 to 5.0 wt. -％, more preferably from 0.8 to 3.0 wt. -％, and most preferably from 1.0 to 1.8 wt. -％, such as from 1.2 to 1.6 wt. -％, based on the total weight of the polar modified polypropylene (PMP) .

Thus in one specific preferred embodiment the polar modified polypropylene (PMP) is a random propylene ethylene copolymer grafted with maleic anhydride, more preferably wherein the ethylene content based on the total amount of the random propylene ethylene copolymer is in the range of 2.0 to 7.5 wt. -％, more preferably in the range of 4.0 to 7.0 wt. -％and/or the amount of groups deriving from the maleic anhydride in the polar modified polypropylene (PMP2) is from 0.5 to 3.0 wt. -％, more preferably from 0.8 to 2.0 wt. -％, and most preferably from 1.0 to 1.8 wt. -％, such as from 1.2 to 1.6 wt. -％, based on the total weight of the polar modified polypropylene (PMP) .

Preferred values of the melt flow rate MFR₂ determined according to ISO 1133 at 190℃ and under a load of 2.16 kg for the polar modified polypropylene (PMP) are from 1.00 to 500 g/10 min, like in the range of 20 to 150 g/10 min.

The polar modified polypropylene (PMP) can be produced in a simple manner by reactive extrusion of the polymer, for example with maleic anhydride in the presence of free radical generators (like organic peroxides) , as disclosed for instance in EP 0 572 028.

The polar modified polypropylene (PMP2) is known in the art and commercially available. A suitable example is SCONA TPPP 8112 FA of BYK.

The polypropylene composition

As outlined above, the polypropylene composition comprises

b) 11 to 30 parts per weight of an ethylene copolymer (PE) having an MFR₂, determined according to ISO1133 at 190℃ and under a load of 2.16 kg, of 0.5 to 35 g/10 min；

c) 26 to 50 parts per weight carbon fiber masterbatch；

d) 0.10 to 2.0 parts per weight of a polar modified polypropylene (PMP) wherein the polar modified polypropylene (PMP) comprises groups derived from polar groups in an amount of from 0.5 to 5.0 wt. -％,

Preferably, the polypropylene composition comprises

a) 35 to 50 parts per weight of the propylene polymer (PP) , more preferably 40 to 50 parts per weight of the propylene polymer (PP) ；

b) 11 to 30 parts per weight of the ethylene copolymer (PE) , more preferably 11 to 25 parts per weight of the ethylene copolymer (PE) and most preferably 11 to 20 parts per weight of the ethylene copolymer (PE) ；

c) 30 to 45 parts per weight carbon fiber masterbatch, more preferably 33 to 40 parts per weight carbon fiber masterbatch；

and/or

d) 0.25 to 1.75 parts per weight of the polar modified polypropylene (PMP) , more preferably 0.5 to 1.5 parts per weight of the polar modified polypropylene (PMP) and most preferably 0.75 to 1.25 parts per weight of the polar modified polypropylene (PMP)

It is particularly preferable that component b) is present in an amount of at least 11 wt. ％based on the entire polypropylene composition.

Preferably, the sum of components a) to d) based on the total amount of the polypropylene composition is at least 85 wt. ％, more preferably at least 90 wt. ％and most preferably at least 95 wt. ％, such as at least 98 wt. ％.

The polypropylene composition is preferably having a surface resistivity of 1.0·10⁶ Ohm/m² or lower, more preferably of 5.0·10⁵ Ohm/m² or lower and most preferably of 1.0·10⁵ Ohm/m² or lower.

The polypropylene composition is preferably having an MFR, determined according to ISO11, at a temperature of 230℃ and under a load of 2.16 kg, of 1.0 to 30 g/10 min, more preferably 3.0 to 25 g/10 min and most preferably 5.0 to 15 g/10 min.

The polypropylene composition is furthermore preferably having a tensile strength, determined according to ISO 527-2, of at least 20 MPa, more preferably at least 30 MPa and most preferably at least 40 MPa. Usually the tensile strength will not be higher than 70 MPa.

Preferably, the flexural modulus, determined according to ISO 178, of the polypropylene composition is at least 3500 MPa, more preferably at least 4000 MPa and most preferably at least 4500 MPa. Usually the flexural modulus will not be higher than 6000 MPa.

The polypropylene composition preferably has a Charpy Notch impact strength, determined according to ISO 179 1eA at 23 ℃, of at least 2.0 kJ/m², more preferably at least 4.0 kJ/m² and most preferably at least 6.0 kJ/m². Usually the Charpy Notch impact strength will not be higher than 10 kJ/m².

The polypropylene composition may comprise compounds different from compounds a) to d) as defined herein whereby the total amount of these compounds different from compounds a) to d) is preferably not more than 15 wt. ％, more preferably not more than 10 wt. ％and most preferably not more than 5 wt. ％such as not more than 2 wt. ％.

The compounds different from compounds a) to d) are preferably selected from usual additives different from carbon fibers, like antioxidants, slip agents, antiblock agents, antifogging agents, pigments, antistatic agents, etc. and carrier polymers. As already outlined above carrier polymers are frequently used to introduce additives into a polymer composition.

The compounds different from compounds a) to d) may comprise carbon black as a pigment. However, in case carbon black is present in the polypropylene composition according to the present invention, it is usually not present in an amount of higher than 5.0 wt. ％, more preferably not more than 2.5 wt. ％and most preferably not more than 1.5 wt. ％such as not more than 1 wt. ％.

In one variant the polypropylene composition comprises

a) 30 to 54 parts per weight, preferably 35 to 50 parts per weight, more preferably 40 to 50 parts per weight of a propylene polymer (PP) having an MFR₂, determined according to ISO1133 at 230℃ and under a load of 2.16 kg of 2.0 to 80 g/10 min；

b) 11 to 30 parts per weight, preferably 11 to 25 parts per weight and most preferably 11 to 20 parts per weight of an ethylene copolymer (PE) having an MFR₂, determined according to ISO1133 at 190℃ and under a load of 2.16 kg, of 0.5 to 35 g/10 min；

c) 26 to 50 parts per weight more preferably 33 to 40 parts per weight carbon fiber masterbatch；

d) 0.10 to 2.0 parts per weight, more preferably 0.5 to 1.5 parts per weight and most preferably 0.75 to 1.25 parts per weight of a polar modified polypropylene (PMP) wherein the polar modified polypropylene (PMP) comprises groups derived from polar groups in an amount of from 0.5 to 5.0 wt. -％,

e) the sum of components a) to d) based on the total amount of the polypropylene composition is at least 85 wt. ％more preferably at least 90 wt. ％and most preferably at least 95 wt. ％, such as at least 98 wt. ％；

the parts per weight are based on the total parts per weight of components a) , b) , c) and d) ,

and

f) the polypropylene composition is having an MFR, determined according to ISO1133, at a temperature of 230℃ and under a load of 2.16 kg, of 1.0 to 30 g/10 min, more preferably 3.0 to 25 g/10 min and most preferably 5.0 to 15 g/10 min

wherein, preferably, the

carbon fibers have an average length of from 0.5 to 30 mm and/or an average diameter of from 1.0 to 30 μm, more preferably an average length of from 1.0 to 20 mm and/or an average diameter of from 2.0 to 25 μm, and most preferably an average length of from 2.0 to 15 mm and/or an average diameter of from 3.0 to 15 μm.

In another variant the polypropylene composition comprises

a) 35 to 50 parts per weight, more preferably 40 to 50 parts per weight of a propylene polymer (PP) having an MFR₂, determined according to ISO1133 at 230℃ and under a load of 2.16 kg of 2.0 to 80 g/10 min；

b) 11 to 25 parts per weight and most preferably 11 to 20 parts per weight of an ethylene copolymer (PE) having an MFR₂, determined according to ISO1133 at 190℃ and under a load of 2.16 kg, of 0.5 to 35 g/10 min；

d) 0.5 to 1.5 parts per weight and most preferably 0.75 to 1.25 parts per weight of a polar modified polypropylene (PMP) wherein the polar modified polypropylene (PMP) comprises groups derived from polar groups in an amount of from 0.5 to 5.0 wt. -％,

the parts per weight are based on the total parts per weight of components a) , b) , c) and d)

e) the sum of components a) to d) based on the total amount of the polypropylene composition is at least 90 wt. ％and most preferably at least 95 wt. ％, such as at least 98 wt. ％； and

f) the polypropylene composition is having an MFR, determined according to ISO1133, at a temperature of 230℃ and under a load of 2.16 kg, of 3.0 to 25 g/10 min and most preferably 5.0 to 15 g/10 min

wherein, preferably, the

In yet another variant the polypropylene composition comprises

wherein the

The article

The present invention is further directed to an article comprising the polypropylene composition according to the present invention, preferably, the article is a molded or foamed article, more preferably an injection molded article.

Molding and foaming processes are generally known in the art.

Preferably, the article according to the present invention is at least a part of a housing for an electrical apparatus and/or used in automotive applications, such as an apparatus for electrical and electronic applications, energy applications and, healthcare, especially automotive applications, e.g. instrument panel carrier.

Usually, the surface resistivity of the polypropylene composition is lowered compared with the same composition containing instead of carbon fibers the same amount of carbon black by a factor of at least 10, more preferably by a factor of at least 100 and most preferably by a factor of at least 1000, such as at least 5000.

Experimental part

Definitions/Measuring Methods

The following definitions of terms and determination methods apply for the above general description of the invention as well as to the below examples unless otherwise defined.

Quantification of microstructure by NMR spectroscopy

Quantitative nuclear-magnetic resonance (NMR) spectroscopy is used to quantify the isotacticity and regio-regularity of the polypropylene homopolymers.

Quantitative ¹³C {¹H} NMR spectra were recorded in the solution-state 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 ¹³C optimised 10 mm extended temperature probehead at 125℃ using nitrogen gas for all pneumatics.

For polypropylene homopolymers approximately 200 mg of material was dissolved in 1, 2-tetrachloroethane-d₂ (TCE-d₂) . To ensure a homogenous solution, after initial sample preparation in a heat block, the NMR tube was further heated in a rotatary oven for at least 1 hour. Upon insertion into the magnet the tube was spun at 10 Hz. This setup was chosen primarily for the high resolution needed for tacticity distribution quantification (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443； Busico, V. ； Cipullo, R., Monaco, G., Vacatello, M., Segre, A.L., Macromolecules 30 (1997) 6251) . Standard single-pulse excitation was employed utilising the NOE and bi-level WALTZ16 decoupling scheme (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. Rapid Commun. 2007, 28, 11289) . A total of 8192 (8k) transients were acquired per spectra.

Quantitative ¹³C {¹H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs.

For polypropylene homopolymers all chemical shifts are internally referenced to the methyl isotactic pentad (mmmm) at 21.85 ppm.

Characteristic signals corresponding to regio defects (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253；； Wang, W-J., Zhu, S., Macromolecules 33 (2000) , 1157； Cheng, H.N., Macromolecules 17 (1984) , 1950) or comonomer were observed. The tacticity distribution was quantified through integration of the methyl region between 23.6-19.7 ppm correcting for any sites not related to the stereo sequences of interest (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443； Busico, V., Cipullo, R., Monaco, G., Vacatello, M., Segre, A.L., Macromolecules 30 (1997) 6251) .

Specifically the influence of regio-defects and comonomer on the quantification of the tacticity distribution was corrected for by subtraction of representative regio-defect and comonomer integrals from the specific integral regions of the stereo sequences.

The isotacticity was determined at the pentad level and reported as the percentage of isotactic pentad (mmmm) sequences with respect to all pentad sequences:

[mmmm] ％＝ 100 * (mmmm /sum of all pentads)

The presence of 2, 1 erythro regio-defects was indicated by the presence of the two methyl sites at 17.7 and 17.2 ppm and confirmed by other characteristic sites. Characteristic signals corresponding to other types of regio-defects were not observed (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253) .

The amount of 2, 1 erythro regio-defects was quantified using the average integral of the two characteristic methyl sites at 17.7 and 17.2 ppm:

P_21e ＝ (I_e6 + I_e8) /2

The amount of 1, 2 primary inserted propene was quantified based on the methyl region with correction undertaken for sites included in this region not related to primary insertion and for primary insertion sites excluded from this region:

P₁₂ ＝ I_CH3 + P_12e

The total amount of propene was quantified as the sum of primary inserted propene and all other present regio-defects:

P_total ＝ P₁₂ + P_21e

The mole percent of 2, 1-erythro regio-defects was quantified with respect to all propene:

[21e] mol. -％＝ 100 * (P_21e /P_total)

Characteristic signals corresponding to the incorporation of ethylene were observed (as described in Cheng, H. N., Macromolecules 1984, 17, 1950) and the comonomer fraction calculated as the fraction of ethylene in the polymer with respect to all monomer in the polymer.

The comonomer fraction was quantified using the method of W-J. Wang and S. Zhu,

Macromolecules 2000, 33 1157, through integration of multiple signals across the whole spectral region in the ¹³C {¹H} spectra. This method was chosen for its robust nature and ability to account for the presence of regio-defects when needed. Integral regions were slightly adjusted to increase applicability across the whole range of encountered comonomer contents.

The mole percent comonomer incorporation was calculated from the mole fraction.

The weight percent comonomer incorporation was calculated from the mole fraction.

Density of the polymer composition is measured according to ISO 1183-187. Sample preparation is done by compression molding in accordance with ISO 1872-2: 2007.

The xylene cold solubles (XCS) are determined at 25 ℃ according ISO 16152； first edition； 2005-07-01.

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

Tensile Modulus； Tensile strength are measured according to ISO 527-2 (cross head speed ＝ 1 mm/min； 23 ℃) using injection molded specimens as described in EN ISO 1873-2 (dog bone shape, 4 mm thickness) .

Flexural modulus is determined in 3-point-bending according to ISO 178 on injection molded specimens of 80 x 10 x 4 mm³ prepared in accordance with EN ISO 1873-2.

Charpy notched impact strength is determined according to ISO 179 1eA at 23 ℃ by using an 80x10x4 mm³ test bars injection molded in line with EN ISO 1873-2.

Average fiber diameter is determined according to ISO 1888: 2006 (E) , Method B, microscope magnification of 1000.

Melt flow rate (MFR) is measured according to ISO 1133 at the temperature and load given. DSC analysis, melting temperature (Tm) and melting enthalpy (Hm) , crystallization temperature (Tc) and crystallization enthalpy (Hc) : measured with a TA Instrument Q200 differential scanning calorimetry (DSC) on 5 to 7 mg samples. DSC is run according to ISO 11357 /part 3 /method C2 in a heat /cool /heat cycle with a scan rate of 10 ℃/min in the temperature range of -30 to +225℃. Crystallization temperature and crystallization enthalpy (Hc) are determined from the cooling step, while melting temperature and melting enthalpy (Hm) are determined from the second heating step.

Surface resistivity: was tested using test Equipment “HS-699” commercially available from Shenzheng Hoslen Electronic Co., Ltd., Guangdong, China.

Sample for test: a plate with a size of 150mm (length) *90mm (width) *3mm (height) is prepared by injection moulding.

Test condition: at a temperature of 23℃ and a relative humidity of 50％.

Production of PP1

Catalyst preparation

First, 0.1 mol of MgCl₂ x 3 EtOH was suspended under inert conditions in 250 ml of decane in a reactor at atmospheric pressure. The solution was cooled to the temperature of –15℃ and 300 ml of cold TiCl₄ was added while maintaining the temperature at said level. Then, the temperature of the slurry was increased slowly to 20℃. At this temperature, 0.02 mol of dioctylphthalate (DOP) was added to the slurry. After the addition of the phthalate, the temperature was raised to 135℃ during 90 minutes and the slurry was allowed to stand for 60 minutes. Then, another 300 ml of TiCl₄ was added and the temperature was kept at 135℃ for 120 minutes. After this, the catalyst was filtered from the liquid and washed six times with 300 ml heptane at 80℃. Then, the solid catalyst component was filtered and dried.

Catalyst and its preparation concept is described in general e.g. in patent publications WO 87/07620, WO 92/19653, WO 92/19658 and EP 0 491 566, EP 591224 and EP 586390.

The catalyst was further modified (VCH modification of the catalyst) .

35 ml of mineral oil (Paraffinum Liquidum PL68) was added to a 125 ml stainless steel reactor followed by 0.82 g of triethyl aluminium (TEAL) and 0.33 g of dicyclopentyl dimethoxy silane (donor D) under inert conditions at room temperature. After 10 minutes 5.0 g of the catalyst prepared above (Ti content 1.4 wt％) was added and after additionally 20 minutes 5.0 g of vinylcyclohexane (VCH) was added. ) . The temperature was increased to 60 ℃ during 30 minutes and was kept there for 20 hours. Finally, the temperature was decreased to 20 ℃ and the concentration of unreacted VCH in the oil/catalyst mixture was analysed and was found to be 200 ppm weight.

As external donor di (cyclopentyl) dimethoxy silane (donor D) was used.

Table 1: Polymerization conditions of PP1

		PP1
Prepolymerisation
Residence time	[h]	0.08
Temperature	[℃]	30
Co/ED ratio	[mol/mol]	7.3
Co/TC ratio	[mol/mol]	220
Loop (R1)
Residence time	[h]	0.6
Temperature	[℃]	75
H₂/C₃ ratio	[mol/kmol]	14.8
MFR₂ (230℃/2.16kg)	[g/10min]	55
XCS	[wt％]	2.0
C2 content	[wt％]	0
split	[wt％]	30
1^st GPR (R2)
Residence time	[h]	0.75
Temperature	[℃]	80
Pressure	[kPa]	2200
H₂/C₃ ratio	[mol/kmol]	149.7
MFR₂ (230℃/2.16kg)	[g/10min]	55
XCS	[wt％]	2.0
C2 content	[wt％]	0
split	[wt％]	35
2^nd GPR (R3)
Residence time	[h]	0.6
Temperature	[℃]	70

Pressure	[kPa]	2190
C₂/C₃ ratio	[mol/kmol]	584.6
H₂/C₂ ratio	[mol/kmol]	116.5
MFR₂ (230℃/2.16kg)	[g/10min]	20
C2 content	[wt％]	8.5
split	[wt％]	20
3^rd GPR (R4)
Residence time	[h]	0.6
Temperature	[℃]	85
Pressure	[kPa]	1320
C₂/C₃ ratio	[mol/kmol]	585.2
H₂/C₂ ratio	[mol/kmol]	92.7
MFR₂ (230℃/2.16kg)	[g/10min]	11
C2 content	[wt％]	13
XCS	[wt％]	32
C2 content of XCS	[wt％]	38
IV of XCS	[dl/g]	2.5
split	[wt％]	15

The properties of the products obtained from the individual reactors naturally are not measured on homogenized material but on reactor samples (spot samples) . The properties of the final resin are measured on homogenized material, the MFR₂ on pellets made thereof in an extrusion mixing process as described below.

PP1 was mixed in a twin-screw extruder with 0.1 wt％of Pentaerythrityl-tetrakis (3- (3’, 5’-di-tert. butyl-4-hydroxyphenyl) -propionate, (CAS-no. 6683-19-8, trade name Irganox 1010) supplied by BASF AG, 0.1 wt％Tris (2, 4-di-t-butylphenyl) phosphate (CAS-no. 31570-04-4, trade 10 name Irgafos 168) supplied by BASF AG, and 0.05 wt％Calcium stearate (CAS-no. 1592-23-0) supplied by Croda Polymer Additives.

Table 2: The recipe for preparing the inventive and reference compositions

“PE1” is the commercial product Engage 8200 of Dow Chemical Pacific Ltd. (Hongkong) , which is an ethylene-1-octene copolymer having a density of 0.870 g/cm³, a melt flow rate MFR₂ (190℃, 2.16kg) of 5.0 g/10min；

“PP-H, GD, 225” propylene homopolymer used as carrier for Irgafos 168 and Irganox 1010, Tm: 160℃；

“Irgafos 168” Tris (2, 4-di-t-butylphenyl) phosphite, CAS-no. 31570-04-4, available from BASF；

“Irganox 1010” Pentaerythrityl-tetrakis (3- (3’, 5’-di-tert. butyl-4-hydroxyphenyl) -propionate, CAS-no. 6683-19-8, available from BASF；

“Carbon fiber master batch” is a mixture of 40 wt. ％carbon fibers and 60 wt. ％of polypropylene homopolymer carrier, having an MFR₂ (ISO1133, 230℃, 2.16 kg load) of 2 g/10 min and a flexural modulus of 18500 MPa；

“TPPP 8112” is the polypropylene (functionalized with maleic anhydride) “TPPP8112 FA” of BYK Co. Ltd, Germany, having a MFR₂ (190 ℃； 2.16 kg) of more than 80 g/10min and a maleic anhydride content of 1.4 wt. -％；

The compositions were prepared by compounding the raw materials in a twin-screw extruder .

All feed materials are heated and mixed homogeneously in the extruder at a temperature of 180-250℃ and the mixture thus formed is extruded from the extruder.

Table 3: The following temperature profile was applied in the compounding process

The properties of the compositions are as follows.

As can be seen from the above the surface resistivity compared with a composition comprising carbon black is reduced by four orders of magnitude while the composition has superior mechanical properties.

Claims

A polypropylene composition comprising

a) 30 to 54 parts per weight of a propylene polymer (PP) having an MFR₂, determined according to ISO1133 at 230℃ and under a load of 2.16 kg, of 2.0 to 80 g/10 min；

b) 11 to 30 parts per weight of an ethylene copolymer (PE) having an MFR₂, determined according to ISO1133 at 190℃ and under a load of 2.16 kg, of 0.5 to 35 g/10 min

c) 26 to 50 parts per weight carbon fibers master batch,

d) 0.10 to 2.0 parts per weight of a polar modified polypropylene (PMP) wherein the polar modified polypropylene (PMP) comprises groups derived from polar groups in an amount of from 0.5 to 5.0 wt.-％

the parts per weight are based on the total parts per weight of components a) , b) , c) and d) .
The polypropylene composition of claim 1, wherein the propylene polymer (PP) is a heterophasic polypropylene (HECO) .
The polypropylene composition according to claim 2, wherein the heterophasic polypropylene (HECO) is characterized by at least one of the following features i) to v)

i) an MFR₂, determined according to ISO1133 at 230℃ and under a load of 2.16 kg, of 5.0 to 60 g/10 min；

ii) a total comonomer content of 5.0 to 18 wt.％；

iii) an xylene cold solubles (XCS) content of 20 to 36 wt.％；

iv) a comonomer content of the xylene cold solubles (XCS) of 30 to 45 wt.％； and

v) an intrinsic viscosity of the xylene cold solubles (IV) of 2.0 to 4.0 dl/g.
The polypropylene composition according to any one of the preceding claims, wherein the ethylene copolymer (PE) is an ethylene copolymer having a comonomer content of not more than 50.0 wt.％.
The polypropylene composition according to any one of the preceding claims, wherein the ethylene copolymer (PE) is a C₂/C₄-C₂₀ alpha-olefin copolymer.
The polypropylene composition according to any one of the preceding claims, wherein the polar modified polypropylene (PMP) comprises groups derived from polar groups selected from the group consisting of acid anhydrides, carboxylic acids, carboxylic acid derivatives, primary and secondary amines, hydroxyl compounds, oxazoline and epoxides, and also ionic compounds, preferably, the polar modified polypropylene (PMP) is a propylene polymer grafted with maleic anhydride.
The polypropylene composition according to any one of the preceding claims, wherein the carbon fiber master batch comprises 25-45 wt％carbon fibers based on the total weight of the carbon fiber master batch.
The polypropylene composition according to any one of the preceding claims, wherein the carbon fibers are free of any metal coatings.
The polypropylene composition according to any one of the preceding claims, wherein the carbon fibers have

i) an average diameter of 1.0 to 30 μm；

ii) an average length of 0.5 to 30 mm； or

iii) both i) and ii) .
The polypropylene composition according to any one of the preceding claims having a surface resistivity of 10⁶ Ohm/m² or lower.
An article comprising the polypropylene composition according to any one of the preceding claims.
The article according to claim 11 being a molded or foamed article, preferably an injection molded article.
The article according to any one of the preceding claims 11 or 12, wherein the article is at least a part of a housing for an electrical apparatus and/or used in automotive applications.