WO2018072049A1

WO2018072049A1 - Polypropylene composition having low fogging

Info

Publication number: WO2018072049A1
Application number: PCT/CN2016/000573
Authority: WO
Inventors: Xin Zhou; Jianglei ZHU; Shih Ping CHEN
Original assignee: Borouge Compounding Shanghai Co., Ltd.
Priority date: 2016-10-17
Filing date: 2016-10-17
Publication date: 2018-04-26
Also published as: CN109843999B; WO2018072666A1; CN109843999A

Abstract

A polypropylene composition (PC) comprising: one or more polypropylenes (P) 0.05 to 5.0 wt.% based on the total weight of the polypropylene composition (PC) of one or more additives (A), whereby each of the additives (A) has a melting temperature determined by DSC of 100℃ or more; and the polypropylene composition (PC) is free from additives having a melting temperature determined by DSC below 100℃, a method for the production thereof, an article made from said composition and the use of additives having a melting temperature determined by DSC of 100℃ or more for reducing the haze of a polypropylene composition (PC) comprising one or more polypropylenes (P).

Description

POLYPROPYLENE COMPOSITION HAVING LOW FOGGING

The present invention relates to a polypropylene composition having low fogging， a method for its manufacture， an article made from the polypropylenc composition and thc usc of specific additives for lowering the fogging of a polypropylene composition.

Polypropylene compositions， have many desirable properties， e.g. lightweight， durability， low costs， etc.， that make them an attractive material for the construction of many interior and exterior automotive parts， e.g. lamp housings， door panels， instrument panels etc. Polypropylene compositions for automotive applications are characterized by a high stiffness and toughness. However， automotive parts are frequently subjected to heat. Lamp housings are exposed to sunlight and to the heat generated by the lamp contained therein which， albeit more and more LED-systems are developed， is predominantly a halogen lamp. The surfaces of car interiors also heat up significantly， e.g. 80℃ or more， in case the car is exposed to sunlight.

Volatile chemicals may evaporate at this high temperature and re-condense e.g. on the transparent front face of a lamp housing or on the car windows， which is called fogging. Presently available compositions for automotive parts usually meet the requirements as to stiffness and toughness， however， they suffer from fogging， and cannot meet the low fogging requirement， which becomes stricter recently in automotive industry.

Thus， a polypropylene composition is required having high stiffness and toughness and simultaneously low fogging.

Therefore， the present invention provides in a first variant a polypropylene composition (PC) comprising

- one or more polypropylenes (P)

- 0.05 to 5.0 wt. ％based on the total weight of the polypropylene composition (PC) of one or more additives (A) ，

whereby

- each of the additives (A) has a melting temperature determined by DSC of 100℃ or more； and

- the polypropylene composition (PC) is free from additives having a melting temperature determined by DSC below 100℃.

In a second variant the present invention provides a polypropylene composition (PC) comprising

- a polypropylene (P)

whereby

the polypropylene composition (PC) has a haze value， determined at 120℃， of 5.0 ％or below.

It has surprisingly been found that using specific additives the fogging of the composition determined as haze as described in the experimental part can be significantly reduced， e.g. by 50 times or more. This is insofar surprising as the melt point of the additives is above the temperature usually present in automobiles etc. Moreover， the stiffness and toughness of the composition is maintained， as no or no significant changes to the polymers as such are required， but at most the processing additives used during manufacturing of the polypropylenes and the additives compounded into the composition in the usual manner need to be replaced whereby usually only minimal or even no adjustments of the process parameters of the polymer are needed.

In the first variant the polypropylene composition (PC) preferably has a haze value， dctermincd at 120℃， of 5.0 ％or below.

In the second variant of the polypropylene composition (PC) preferably

- the polypropylene composition (PC) is free from additivcs having a melting temperature determined by DSC below 100℃.

In the following all variants of the present invention are further described.

The additives (A) may not have a sharp melting point. In this case the lower end of the melting peak is considered the melting temperature according to the present invention. For example， a melting curve may be obtained having a melting peak which starts at 110℃ and ends at 130℃. In this case the melting temperature is 110℃

In the present invention the term “additives” does not encompass pigments and fillers such as mineral fillers.

The expression ″multimodal″ or “bimodal” used throughout the present invention refers to the modality of the polymer， i.e. the form of its molecular weight distribution curve， which is the graph of the molecular weight fraction as a function of its molecular weight.

Preferably， the total amount of polypropylenes (P) is at least 50 wt. ％， more preferably at least 55 wt. ％even more preferably at least 60 wt. ％and most preferably at least 65 wt. ％， based on the total amount of the polypropylene composition (PC) . The polypropylenes (P) usually make up at least 90 wt. ％of the entirety of polymerie compounds present in the polypropylene composition， more preferably make up at least 95 wt. ％of the entirety of polymeric compounds present in the polypropylene composition and most preferably make up at least 98 wt. ％of the entirety of polymeric compounds present in the polypropylene composition. The remaining polymer usually comprises， preferably consists of， polymers used as a carrier for additives. Such carriers comprising additives are frequently denoted masterbatches.

Preferably the melt flow rate (MFR) of the polypropylene composition (PC) ， determined according to ISO 1133 at 230℃ and under a load of 2.16 kg， is from 1 to 50 g/10 min， more preferably from 5 to 40 g/10 min.

The tensile modulus of the polypropylene composition (PC) ， determined according to ISO 527-2， is preferably 3000 MPa or higher， more preferably 3500 MPa or higher and most preferably 3800 MPa or higher. Usually the tensile modulus will not exceed 5000 MPa

The flcxural modulus of the polypropylene composition (PC) ， determined according to ISO 178， is preferably 3000 MPa or higher， more preferably 3400 MPa or higher and most preferably 3700 MPa or higher. Usually the tensile modulus will not exceed 5000 MPa

The tensile strength of the polypropylene composition (PC) ， determined according to ISO 527-2， is preferably 20 MPa or higher， more preferably 25 MPa or higher and most preferably 30 MPa or higher. Usually the tensile modulus will not exceed 40 MPa

The flexural strength of the polypropylene composition (PC) ， determined according to ISO 178， is preferably 35 MPa or higher， more preferably 45 MPa or higher and most preferably 50 MPa or higher. Usually the tensile modulus will not exceed 60 MPa

The haze value of the polypropylene composition (PC) ， determined at 120℃， is preferably 5.0％or lower， more preferably 4.5％or lower， even more preferably 3.0％or lower， even more preferably 1.75％or lower and most preferably 1.0％or lower.

The haze value of the polypropylene composition (PC) ， determined at 130℃， is preferably 10.0％or lower， more preferably 5.0％or lover， even more preferably 3.0％or lower and most preferably 1.5％or lower.

The method for determination of the haze is described in the experimental part.

The Notched IZOD impact strength， determined according to EN ISO 180， of the polypropylene composition (PC) is preferably at least 1.0 J/m²， more preferably at least 2.0 J/m² and most preferably at least 2.4 J/m².

Preferably the polypropylene composition (PC) has a density， measured according to ISO 1138， of at least 890 kg/m³， more preferably at least 900 kg/m³， still more preferably from 900 to 1200 kg/m³.

Preferably the polypropylenes (P) comprise a heterophasic propylene copolymer (HECO) ， and/or a propylene homopolymer (HPP) . A heterophasic propylene copolymer (HECO) comprises a matrix (M) and an elastomeric propylene copolymer (EC) . In an especially preferred variant， both of the heterophasic propylene copolymer (HECO) and a propylene homopolymer (HPP) are present in the polypropylene composition (PC) besides the optional polymers used as earrier for additives as discussed above. In this especially preferred variant the propylene homopolymer (HPP) is different from the matrix of the heterophasic propylene copolymer (HECO) .

A heterophasic propylene copolymer (HECO) comprises a polypropylene as a matrix (M) and dispersed therein an elastomeric propylene copolymer (EC) . Thus the polypropylene matrix (M) contains (finely) dispersed inclusions being not part of the matrix and said inclusions contain the elastomeric propylene copolymer (EC) . The term inclusion indicates that the matrix (M) and the inclusion form different phases within the heterophasic propylene copolymer (HECO) ， said inclusions are for instance visible by high resolution microscopy， like electron microscopy or scanning force microscopy.

The matrix of the heterophasic propylene copolymer (HECO) as well as the rubber phasc of the heterophasic propylene copolymer (HECO) may consist of a single polymer only or may be a mixture of two or more polymers each， preferably consist of a single polymer only

The heterophasic propylene copolymer (HECO) may be produced by melt-blending and/or by reactor blending. In this regard “reactor-blending” denotes that the individual fractions of the polymers are produced in subsequent stages， in the presence of the product of the previous stage. For example， the matrix and the disperse phase of a heterophasic polypropylene may be produced in such subscqucnt stagcs.

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

Furthermore， it is also possible to melt-blend a propylene already comprising two or more fractions， e.g. nelt-blend a heterophasic propylene copolymer (HECO) ， with a further propylene such as a propylene homopolymer (HPP) or random copolymer.

Preferably the melt flow rate (M FR) of the heterophasic propylene copolymer (HECO) ， determined according to ISO 1133 at 230℃ and under a load of 2.16 kg， is from 0.1 to 150 g/10 min， more preferably from 5 to 120 g/10 min and most preferably from 10 to 110 g/10 min.

Preferably the melt flow rate (MFR) of the propylene homopolymer (HPP) determined according to ISO 1133 at 230℃ and under a load of 2.16 kg， is from 0.1 to 65 g/10 min， more preferably from 5 to 60 g/10 min.

The matrix (M) of the heterophasic polypropylene (HECO) ， i.e. the xylene cold insoluble (XCI) content， in the heterophasic polypropylene (HECO) ， preferably has an MFR， determined according to ISO 1133 at 230℃ and under a load of 2.16 kg of 1 to 400 g/10 min， more preferably of 5 to 325 g/10 min and most preferably 10 to 250 g/10 min.

Preferably， the amorphous phase (AM) of the xylene cold soluble fraction (XCS) of the heterophasic propylene copolymer (HECO) has an intrinsic viscosity (IV) measured according to ISO 1628-1 (at 135℃ in decaline) of equal or higher than 1.5 dl/g， more preferably of cqual or higher than 1.7 dl/g and most prefcrably of equal or higher than 1.9 dl/g. Usually the intrinsic viscosity (IV) of the amorphous phase (AM) of the xylene cold soluble fraction (XCS) will not exceed 4.0 dl/g.

Accordingly， the polypropylene matrix (M) content， i.e. the xylene cold insoluble (XCI) content measured according to ISO6427 (23 ℃) ， based on the heterophasic polypropylene (HECO) ， is preferably in the range of 70.0 to 95.0 wt. -％， more preferably in the range of 80.0 to 90.0 wt. -％.

The elastomeric propylene copolymer (EC) content， i.e. the xylene cold soluble (XCS) content measured according to ISO6427 (23 ℃) ， based on the heterophasic polypropylene (HECO) ， is preferably 1.0 to 30.0 wt. ％， more preferably 5.0 to 25.0 wt. ％and most preferably 10.0 to 20.0 wt. ％.

The elastomeric propylene copolymer (EC) content， i.e. the xylene cold soluble (XCS) content measured according to ISO6427 (23 ℃) ， based on the polypropylene composition (PC) is preferably 0.5 to 18 wt. ％， more preferably 1.0 to 13 wt. ％and most preferably 2.0 to 8.0 wt. ％.

The heterophasic propylene copolymer (HECO) comprises apart from propylene also comonomers. Preferably the heterophasic propylene copolymer (HECO) comprises apart from propylene ethylene and/or C₄ to C₁₂ alpha-olefins. Accordingly， the term “propylene copolymer” according to this invention is understood as a polypropylene comprising， preferably consisting of， units derivable from

(a) propylene

and

(b) ethylene and/or C₄ to C₁₂ alpha-olefins.

Thus the propylene copolymers according to this invention， i.e. the heterophasic propylene copolymer (HECO) ， the random propylene copolymer fractions of the matrix， and the elastomeric propylene copolymer (EC) ， comprise monomers copolymerizable with propylene， for example comonomers such as ethylene and/or C₄ to C₁₂ alpha-olefins， in particular ethylene and/or C₄ to C₈ alpha-olefins， e.g. 1-butene and/or 1-hexene. Preferably the propylene copolymers according to this invention comprise， especially consist of， monomers copolymerizable with propylene from the group consisting of ethylene， 1-butene and 1-hexene. More specifically the propylene copolymers of this invention comprise-apart from propylene-units derivable from ethylene and/or 1-butene. In a preferred embodiment the propylene copolymers according to this invention comprise units derivable from ethylene and propylene only. Still more preferably the random propylene copolymer fractions of the matrix -if present-as well as the elastomeric propylene copolymer (EC) contain the same comonomers， like ethylene.

Accordingly， the clastomcric propylcnc copolymcr (EC) is preferably an ethylene propylene rubber (EPR) ， whereas the polypropylene (s) of the matrix (M) is/are either a random propylene copolymer or a propylene homopolymer， the latter being preferred.

Additionally， it is appreciated that the heterophasie propylene eopolymer (HECO) preferably has a comonomer content equal or below 15 wt. -％， more preferably in the range of 0.50 to 12.0 wt. -％， more preferably in the range of 1.0 to 10.0 wt. -％， yet more preferably in the range of 3.0 to 8.0 wt. -％.

Accordingly， the comonomer 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. -％.

The content of units derivable from propylene in the elastomeric propylene copolymer (EC) 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 55.0 to 70.0 wt. -％. Thus in a specific embodiment the elastomeric propylene copolymer (EC) ， i.e. the xylene cold soluble (XCS) fraction， comprises from 25.0 to 50.0 wt. -％， more preferably 30.0 to 45.0 wt. -％， units derivable from ethylene and/or C₄ to C₁₂ alpha-olefins.

The expression propylene homopolymer as used throughout the instant invention relates to a polypropylene that consists substantially， i，e. of equal or more than 99.9 wt. -％， of propylene units. In a preferred embodiment only propylene units in the propylene homopolymer are detectable.

In ease one or more of the polypropylene (s) comprised in the matrix (M) is a random propylene copolymer it is appreciated that the random propylene copolymer (s) comprise (s) monomers copolymerizable with propylene， for example comonomers such as ethylene and/or C₄ to C₁₂ alpha-olefins， in particular ethylene and/or C₄ to C₈ alpha-olefins， e.g. 1-butene and/or 1-hexene. Preferably the random propylene copolymer according to this invention comprises， especially consists of， monomers copolymerizable with propylene from the group consisting of ethylene， 1-butene and 1-hexene. More specifically the random propylene copolymer of this invention comprises -apart from propylene -units derivable from ethylene and/or 1-butene. In a preferred embodiment the random propylene copolymer comprises units derivable from ethylene and propylene only.

Additionally， it is appreciated that the random propylene copolymer has preferably a comonomer content in the range of more than 0.1 to 2.0 wt. -％， more preferably in the range of more than 0.1 to 1.6 wt. -％， yet more preferably in the range of 0.1 to 1.0 wt. -％.

The term “random” indicates that the comonomers of the propylene copolymer 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 outlined above， the heterophasic polypropylene can be prepared by reactor-blending， melt-blending or a mixture thereof. These processes are known in the art.

In a preferred variant the heterophasic polypropylene (HECO) is blended with a propylene homopolymer (HPP) or random copolymer， preferably a propylene homopolymer (HPP) .

The weight ratio between heterophasic polypropylene (HECO) and the propylene homopolymer (HPP) or random copolymer， preferably the preferred propylene homopolymer (HPP) ， is preferably 1∶10 to 10∶1， more preferably 1∶5 to 2∶1 and most preferably 1∶3 to 1∶1.

The heterophasic polypropylene (HECO) according to th is invention is preferably produced in a multistage process known in the art， wherein the matrix is produced at least in one slurry reactor and subsequently the elastomeric copolymer is produced at least in one gas phase reactor.

Thus， the polymerization system 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 comprises also a prepolymerisation with the chosen catalyst system， as dcscribcd in detail below， comprising the Ziegler-Natta procatalyst， the external donor and the cocatalyst.

In a preferred embodiment， the prepolymerisation is conducted as bulk shurry 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 polymerization stages. Also in such cases it is necessary to introduce so much cocatalyst into the prepolymerisation stage that a sufficient polymerization reaction is obtained therein.

It is possible to add other components also to the prepolymerization stage. Thus， hydrogen may be added into the prepolymerization 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 prepolymerization 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 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 polypropylene (HECO) of the invention comprises carrying out the polymerization in a process comprising either a combination of one loop and one or two 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 polypropylene (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 proccssing.

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

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 polypropylenes are 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’a nd R^2’a re 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. 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’a nd 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’ a nd R^2’ being the same and being at least a C₅-alkyl， like at lcast 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 dialky lphthalate of formula (I) is a dioetylphthalate (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.

In a further， preferred， embodiment， 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 alpha-nucleating agent. This modification is in particular used for the preparation of the heterophasic polypropylene (H-PP1) .

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 polypropylenes 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 branehed-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 a represent 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.

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] .

propylene homopolymer (HPP)

The propylene homopolymer (HPP) is preferably having a melt flow ratc MFR₂ (230 ℃， 2.16 kg) measured according to ISO 1133 of not more than 50 g/10 min， preferably in the range of 1 to 30 g/1 0 min， still more preferably in the range of 2 to 20 g/10 min， like in the range of 4 to 15 g/10min.

The melting temperature T_m of the propylene homopolymer (HPP) is preferably in the range of 160 to 170 ℃， like in the range of 164 to 170 ℃.

As outlined above， the expression propylene homopolymer as used throughout the instant invention relates to a polypropylene that consists substantially， i.e. of equal or more than 99.9 wt.-％， of propylene units. In a preferred embodiment only propylene units in the propylene homopolymer are detectable.

The propylene homopolymer (HPP) can be multimodal or bimodal in view of the molecular weight， preferably the propylene homopolymer (HPP) is bimodal.

Preferably the propylene homopolymer (HPP) is isotactic. Accordingly， it is appreciated that the propylene homopolymer (HPP) 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 ％.

Preferably the propylene homopolymer (HPP) has a density， measured according to ISO 1138， of at least 890 kg/m³， more preferably at least 900 kg/m³， still more preferably from 900 to 915 kg/m³.

The propylene homopolymer (HPP) according to this invention can be produced in a slurry reactor and/or a gas phase reactor.

In case the propylene homopolymer (HPP) is multimodal or bimodal， it is preferably produced in a multistage process known in the art， comprising at least one slurry reactor and subsequently at least one gas phase reactor.

As outlined above， the propylene homopolymer (HPP) is preferably bimodal. In this case it is preferably produced in a multistage process， comprising two slurry reactors or one slurry reactor and subsequently one gas phase reactor， more preferably in one slurry reactor and subsequently one gas phase reactor.

The slurry reactor (s) is/are preferably loop reactors.

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

A further suitable slurry-gas phase process is the

process of Basell.

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 catalyst components ate 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 coeatalyst is introduced into the prepolymerisation stage and the remaining part into subsequent polymerization stages. Also in such cases it is necessary to introduce so much cocatalyst into the prepolymerisation stage that a sufficient polymerization reaction is obtained therein.

A slurry reactor designates any reactor， such as a continuous or simple batch stirred tank reactor or loop reactor， operating in bnlk or slurry and in which the polymer forms in particulate form. ″Bulk″ means a polymerization in reaction medium that comprises at least 60 wt. -％monomer. According to a preferred embodiment the slurry reactor comprises a bulk loop reactor.

A suitable catalyst system is described in EP 591 224 which is herewith incorporated by reference.

CH₂-CH-CHR³R⁴

As outlined above， in casc thc polypropylenes (P) comprise a heterophasic propylene copolymer (HECO) and a propylene homopolymer (HPP) ， the propylene homopolymer (HPP) is different from the matrix of the heterophasic propylene copolymer (HECO) . Usually the propylene homopolymer (HPP) at least differs from the matrix of the heterophasic propylene copolymer (HECO) with regard to its melt flow rate (MFR) .

Mineral filler (F)

In addition to thc polymer components the polymer composition (PC) according to the present invention comprises a mineral filler (F) in amounts of up to 45 wt. -％， preferably up to 40 wt. -％， more preferably up to 30 wt. -％， based on the total amount of the polypropylene composition (PC) .

Usually the mineral filler (F) is present in an amount of 1.0 wt. ％or more， more preferable 5.0 wt.％or more and most preferably 10 wt. ％or more based on the total amount of the polypropylene composition (PC) .

Preferably the mineral filler (F) is selected from glass fibers， carbon fibers， phyllosilicate， mica， wollastonite or mixtures thereof. Even more preferably the mineral filler (F) is selected from the group of mica， wollastonite， kaolinite， smectite， montmorillonite and talc. The most preferred mineral filler (F) is talc.

Usually and preferably no additional mineral filler (s) besides the mineral filler (F) defined above is/are present in the polypropylene composition (PC) . Hence， the mineral filler (s) present preferably consist of the mineral filler (F) .

The mineral filler (F) preferably has an average particle size d50 [mass percent] in the range of 1 to 20 μm， more preferably in the range of 1 to 10 μm， still more preferably in the range of 1 to 5 μm.

Typically， the mineral filler (F) has a cutoff particle size d95 [mass percent] of equal or below 20 μm， more preferably in the range of 2.5 to 10 μm.

Typically， the mineral filler (F) has a surface area measured according to the commonly known BET method with N₂ gas as analysis adsorptive of less than 22 m²/g， more preferably of less than 20 m²/g， yet more preferably of less than 18 m²/g.

Typical examples for commercially available talc products are Luzenac A7C， Steamic T1 CA， Jetfine T1 CA and HAR (high aspect ratio) talc.

Pigment

Oplionally the polypropylene composition comprises a pigment. Suitable pigments are known in the art.

Preferably a black pigment is used.

The total amount of pigments present in the polypropylene composition (PC) according to the present invention is preferably 0.10 to 5.0 wt. ％， more preferably 0.25 to 3.5 wt. ％and most preferably 0.25 to 2.5 wt. ％based on the total weight of the polypropylene composition.

Additives (A)

The additives (A) preferably comprise antioxidants， processing aids， acid scavengers， lubricant.

The total amount of additives (A) is preferably within the range of 0.05 to 5.0 wt. ％， more preferably 0.10 to 3.5 wt. ％and most preferably from 0.25 to 2.5 wt. ％.

As outlined above， each of the additives (A) has a melting temperature determined by DSC of 100℃ or more.

Suitable additives are， for example， the following compounds：

Antioxidants

1 ， 3， 5-Tris (3’ ， 5’ -di-tert. butyl-4’ -hydroxybenzyl) -isocyanurate，

CAS-no. 27676-62-6， Tm 218℃；

Tris (2， 4-di-t-butylphenyl) phosphite， CAS-no. 31570-04-4， Tm： 182℃；

Poly ( (6-morpholino-s-triazine-2， 4-diyl) (1， 2， 2， 6， 6-pentamethyl-4-piperidyl) imino) hexamethylene (1， 2， 2， 6， 6-pentamethyl-4-piperidyl) imino) ) ， CAS-no. 193098-40-7 obtainable as Cyasorb UV-3529 from Cytec， Tm： 110℃；

1， 3， 5-tri-methyl-2， 4， 6-tris- (3， 5-di-tert. butyl-4-hydroxyphenyl) benzene， CAS-no. 1709-70-2， Tm： 240 ℃；

Bis- (3， 3-bis- (4-’ -hydroxy-3’ -tert. butylphenyl) butanic acid) -glycolester， CAS-no. 32509-66-3， Tm： 167 ℃；

1， 3， 5-Tris (4-tert. butyl-3-hydroxy-2， 6-dimethylbenzyl) -1， 3， 5-triazine-2， 4， 6- (1 H， 3 H， 5H) -trione， CAS-no. 40601-76-1， Tm： 159℃；

Processing aids：

Talc， Tm： 800℃，

Acid scavengers：

Ca stearate， Tm： 145℃

Process

The present invention is furthermore directed to a process producing the polypropylene composition (PC) according to the present invention， comprising the following steps：

(i) providing one or more polypropylenes (P) ；

(ii) providing one or more additives (A) ， whereby each of the additives (A) has a melting temperature determined by DSC of 100℃ or more；

(iii) melt-mixing the polypropylenes (P) and the additives (A) ；

whereby

no additives having a melting temperature determined by DSC below 100℃ are present in the polypropylenes (P) ； and

no additives having a melting temperature determined by DSC below 100℃ are added during the process.

Melt-mixing of polypropylcncs and additives is known in the art， for example using static mixers or extruders. Preferably， an extruder is used， e.g. a counter-rotating twin-screw extruder.

Further components may be present in step (iii) ， for example a mineral filler (F) and/or a pigment as defined in the present invention.

The additives and the optional pigment (s) and mineral filler (F) ， if present， can be added simultaneously or subsequently. In case the process according to the present invention is carried out in an extruder， the additives and the optional pigment (s) and mineral filler (s) ， if present， are usually added through one or more side-feeders of the extruder.

If prcsent， usually and preferably， thc mineral filler (F) is added prior to the additives (A) and the pigments， if present.

If present， usually and preferably， the pigment (s) is added after the additives (A) and the mineral filler (F) ， if present.

In case the process according to the present invention is carried out in an extruder， usnally and preferably individual side feeders are used for the mineral filler (F) ， if present， the additives (A) and the pigments， if present.

The additives may be premixed with a polypropylene powder (as a carrier for additives) prior to addition to the polypropylenes (P) . Usually and preferably the amount of this polypropylene powder is not more than 2.0 wt. ％based on the total weight of the polypropylene composition (PC) ， more pteferably not more than 1.0 wt. ％based on the total weight of the polypropylene composition (PC) .

The temperature during melt-mixing is preferably within the range of 190 to 260℃.

The present invention is further directed to an article comprising， preferably consisting of， the polypropylene composition (PC) according to the invention.

The article according to the invention is preferably an injection-molded article such as interior and exterior automotive parts.

The present invention is further directed to the use of additives (A) having a melting temperature determined by DSC of 100℃ or more for reducing the haze of a polypropylene composition (PC) comprising one or more polypropylenes (P) .

Preferred embodiments of the polypropylene composition (PC) according to the present invention are also preferred embodiments of the process， article and use according to the present invention and vice versa.

Experimental part

Melt flow rate (MFR) is measured according to ISO 1 133 (230℃， 2.16 kg load) .

Tensile Modulus and Tensile Strength are measured according to ISO 527-2 (cross head specd＝ 50 mm/min； 23 ℃) using injection molded specimens as described in EN ISO 1873-2 (dog bone shape， 4 mm thickness) .

Flexural Modulus and Flexural Strength are determined in 3-point-bending at 23℃according to ISO 178 on 80x10x4 mm³ test bars injection moulded in line with EN ISO 1873-2.

Density was determined according to ISO 1 183.

cutoff particle size d95 and average particle size d50 of the mineral filler were determined by laser mastersizer according to ISO 13320-1.

surface area of the mineral filler was determined according to ISO 9277.

Notched IZOD impact strength (23℃) was determined according to EN ISO 180.

Melting temperature T_m， of the polymers and additives are measured with Mettler TA820 differential scanning calorimetry (DSC) on 5-10 mg samples. Both crystallization and melting curves were obtained during 10 ℃/min cooling and heating scans between 30 ℃ and 225 ℃. Melting temperatures were taken as the peaks of endotherms and exotherms. The melting temperature (T_m) of additives are also available from the literature. However， in the present invention the values as obtained above are used.

Haze

Polymer and composition thereof

Haze of polymer or composition thereof is tested according to the haze test method of Koito Manufacturing Co.， Ltd (JP) ， using the haze equipment “Haze-gard dual 4727” of BYK-Gardner， Germany.

Test steps：

a. a plaque of a polymer sample (diameter 80 mm， thickness 3 mm) was put into a glass vessel for fogging， the opening of the glass vessel was covered with a sealing loop and then a glass plate was affixed on the sealing loop. Finally， a cooling device was fixed on the glass sheet；

b. the glass vessel was placed into a thermotank ( “FT-F1” of Labthink company， Shandong， China) at 120℃ or 130℃ to heat it for 24 hours， the volatile gases generated from the sample go up and condensate on lower surface of the glass sheet cooled down to 25℃ by the cooling device；

c. after heating and condensating for 24 hours， the glass sheet was removed from the vessel， and then the glass sheet was put in a dry utensil at room temperature， until it teaches room temperature. The haze of the glass sheet was determined using the haze machine “Haze-gard dual 4727” .

Haze value is calculated by the following equation：

Haze rate (％) ＝ ( (T4/T2) -T3 (T2/T1) ) *100％

T1： The amount light incident upon the glass plateT2： The total amount of light transmitted through the glass plate

T3： The amount of light scattered by instrument

T4： The amount of light scattered by instrument and test piece

Wherein T1， T2， T3， and T4 are value tested and obtained from haze equipment by the “I laze-gard dual 4727” of BYK-Gardner.

Additive as such

The above described method can also be used to test haze of additives or mixtures thereof. In this case the above described method is repeated whereby the pure additives in powder are used as test sample in the amount corresponding to the amount present in a circular plaque of the polypropylene composition having a diameter of 80 mm and a thickness of 3 mm made from a polypropylene composition comprising these additives instead of the circular plaque.

The xylene solubles (XCS， wt. -％) is determined at 25 ℃ according ISO 16152； first edition； 2005-07-01.

The amorphous content (AM) is measured by separating the above xylene cold soluble fraction (XCS) and precipitating the amorphous part with acetone. The precipitate was filtered and dried in a vacuum oven at 90 ℃.

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

Number average molecular weight (M_n) ， weight average molecular weight (M_w) and molecular weight distribution (MWD) are determined by Gel Permeation Chromatography (GPC) according to the following method：

The weight average molecular weight Mw and the molecular weight distribution (MWD ＝ Mw/Mn wherein Mn is the number average molecular weight and Mw is the weight average molecular weight) is measured by a method based on ISO 16014-1： 2003 and ISO 16014-4： 2003. A Waters Alliance GPCV 2000 instrument， equipped with refractive index detector and online viscosimeter was used with 3 x TSK-gel columns (GMHXL-HT) from TosoHaas and 1， 2， 4-trichlorobenzene (TCB， stabilized with 200 mg/L 2， 6-Di tert butyl-4-methyl-phenol) as solvent at 145 ℃ and at a constant flow rate of 1 mL/min. 216.5 μL of sample solution were injected per analysis. The column set was calibrated using relative calibration with 19 narrow MWD polystyrene (PS) standards in the range of 0.5 kg/mol to 11 500 kg/mol and a set of well characterized broad polypropylene standards. All samples were prepared by dissolving 5 -10 mg of polymer in 10 mL (at 160 ℃) of stabilized TCB (same as mobile phase) and keeping for 3 hours with continuous shaking prior sampling in into the GPC instrument.

Quantification of microstructure by NMR spectroscopy

Quantitative nuclear-magnetic resonance (NMR) spectroscopy was further used to quantify the comonomer content of the polymers. 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 pncumatics.

Approximately 200 mg of material was dissolved in 3 ml of 7， 2-tetrachloroethane-c/2 (TCE-c/₂) along with chromium- (lll) -acetylacetonate (Cr (acac) ₃) resulting in a 65 mM solution of relaxation agent in solvent (Singh， G.， Kothari， A.， Gupta， V.， Polymer Testing 28 5 (2009) ， 475) . To ensure a homogenous solution， after initial sample preparation in a heat block， the NMR tube was further heated in a rotatory 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 and quantitatively needed for accurate ethylene content quantification. Standard single-pulse excitation was employed without NOE， using an optimised tip angle， I s recycle delay and a 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， 1 128) . A total of 6144 (6k) transients were acquired per spectra.

Quantitative ¹³C {¹ H} NMR spectra were processed， integrated and relevant quantitative properties determined from the integrals using proprietary computer programs. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. This approach allowed comparable referencing even when this structural unit was not present. Characteristic signals corresponding to the incorporation of ethylene were observed Cheng， H. N.， Macromolecules 17 (1984) ， 1950) .

The comonomer fraction was quantified using the method of Wang et. al. (Wang， W-J.， Zhu， S.， Maeromolecules 33 (2000) ， 1 157) through integration of multiple signals across the whole spectral region in the ¹³C {¹ H} 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.

For systems where only isolated ethylene in PPEPP sequences was observed the method of Wang et. al. was modified to reduce the influence of non-zero integrals of sites that are known to not be present. This approach reduced the overestimation of ethylene content for such systems and was achieved by reduction of the number of sites used to determine the absolute ethylene content to：

E ＝ 0.5 (Sββ + Sβγ + Sβδ + 0.5 (Sαβ + Sαγ) )

Through the use of this set of sites the corresponding integral equation becomes：

E ＝ 0.5 (I_H +I_G + 0.5 (I_C + I_D) )

using the same notation used in the article of Wang et. al. (Wang， W-J.， Zhu， S.， Macromolecules 33 (2000) ， 1 157) . Equations used for absolute propylene content were not modified.

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

E [mol％] ＝ 100 *fE

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

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

The comonomer sequence distribution at the triad level was determined using the analysis method of Kakugo et al. (Kakugo， M.， Naito， Y.， Mizunuma， K.， Miyatake， T. Macromolcculcs 15 (1982) 1 150) . This method was chosen for its robust nature and integration regions slightly adjusted to increase applicability to a wider range ofcomonomer contents.

Used compounds

Irganox 3114 1， 3， 5-Tris (3’ ， 5’ -di-tert. butyl-4’ -hydroxybenzyl) -isocyanurate， CAS-no. 27676-62-6 obtained from BASF， T_m 218℃；

Irgafos 168 Tris (2， 4-di-t-butylphenyl) phosphite， CAS-no. 31570-04-4， obtained from BASF， T_m 182℃；

Cyasorb UV-3529 Poly ( (6-morpholino-s-triazine-2， 4-diyl) (1， 2， 2， 6， 6-pentamethyl-4-piperidyl) imino) hexamethylene (1， 2， 2， 6， 6-pentamethyl-4-piperidyl) imino) ) ， CAS-no. 193098-40-7 obtained from Cytec， T_m 110℃；

Irganox 1076 Octadecyl 3- (3’ ， 5’ -di-tert. butyl-4-hydroxyphenyl) propionate， CAS-no. 2082-79-3 obtained from BASF， T_m 50℃；

Irganox PS-802 FL Di-stearyl-thio-di-propionate， CAS-no. 211-750-5 obtained from BASF， T_m 64℃；

Cyasorb UV3808 a mixture of

- n-Hexadecyl-3， 5-di-t-butyl-4-hydroxybenzoate， CAS-no. 67845-93-6 and

- a mixture of esters of 2， 2， 6， 6-tetramethyl-4-piperidinol and higher fatty acids (mainly stcaric acid) ， CAS-no. 86403-32-9， obtained from Cytec， T_m 28℃.

Jetfine TTCA talc， obtained from Imerys France， Tm： 800℃.

Yuch black-1906 pigment， available from Cabot (USA) ， Tm： 125℃

PP-H， GD， 225： propylene homopolymer in powder， Tm： 160℃.

Borealis commercial resins comprising glyceryl monostearate (having a T_m of 65℃) ： BD950MO， BD265MO， BE961MO， BF970MO， BH975MO， BJ368MO， HG385MO and HJ311MO.

Borealis commereial resin not comprising glyceryl monostearate (having a T_m of 65℃) nor any other additive having a melting temperature T_m of less than 1 00℃： HJ311A1， HD915CF， BJ356A1.

HD915CF is a propylene homopolymer prepared by the Borealis Borstar nucleation technique (BNT) having an MFR (ISO 1133， 230℃/2.16 kg) of 8 g/10 min whieh does not contain glyceryl monostearate， nor any other additives having a Tm of less than 100℃.

BJ356A1 is a heterophasic polypropylene prepared by the Borealis Borstar nucleation technique (BNT) having an MFR (ISO 1133， 230℃/2.16 kg) of 95 g/1 0 min which does not contain glyceryl monostearate， nor any other additives having a Tm of less than 100℃.

The haze of the base polymers has been determined， the results are given in the following table 1.

TabIe 1	poIypropylene	haze at 120℃ [％]
RE1	BD950MO	13.8
RE2	BD265MO	15.7
RE3	BE961MO	58.5
RE4	BF970MO	12.3
RE5	BH975MO	13
RE6	BJ368MO	6.84
RE7	HG385MO	10.9
RE8	HJ311MO	6.18
IE9	HJ311A1	1.81
IE10	HD915CF	0.12
IE11	BJ356A1	0.06

RE： reference examples

IE： inventive example

Moreover， the haze of the individual additives has been determined as outlined above. The results including the used amounts are given in table 2.

Table 2	additive	T_m [℃]	amount [mg]	haze at 120℃ [％]
RE11	Irganox 1076	50	0.5g	13.6
RE12	Irganox PS-802 FL	64	0.5g	12.6
RE13	Cyasorb UV3808	28	0.5g	24.4
IE14	Irganox 3114	218	0.5g	1.05
IE15	Irgafos 168	182	0.5g	6.57
IE16	Cyasorb UV-3529	110	0.5g	3.39

RE： reference examples

IE： inventive example

Furthermore， the following compositions were prepared using a counter-rotating twin-screw extruder having a main feeder and three side feeds.

The components indicated in the table below are fed via the main feeder， the filler (talc) is fed via the first side feeder， the additives via the second side feeder and the pigment via the third side feeder. The additives were mixed with a polypropylene powder used as a carrier for the additive. The amounts are given in weight percent.

Physical properties of the composition prepared are also shown in table 3 below.

It can be seen clearly from Table 3 that the inventive polypropylene composition， which contains base resins without GMS (i.e. HD915CF and BJ356AI) and additives having a Tm more than 100℃ (i.e. AO 3114， and UV-3529) ， has a much lower haze， reduced by 50 times over the prior material， which contains base resins with GMS (HJ311MO， HG385MO， and BD950MO) and additives having a Tm less than 100℃ (i.e. AO1076， Irganox PS-802 FL， and UV-3808) .

Besides the reduced haze， the inventive composition retains similar mechanical properties to the prior material， which meet requirements of mechanical properties.

Thereby， the inventive compositon has a much lower haze and meet requirements of both haze and mechanical properties.

Claims

A polypropylene composition (PC) comprising

one or more polypropylenes (P)

0.05 to 5.0 wt. ％based on the total weight of the polypropylene composition (PC) of one or more additives (A) ，

whereby

each of the additives (A) has a melting temperature determined by DSC of 100℃ or more； and

-the polypropylene composition (PC) is free from additives having a melting temperature determined by DSC below 100℃.
A polypropylene composition (PC) comprising

a polypropylene (P)

0.05 to 5.0 wt. ％based on the total weight of the polypropylene composition (PC) of one or more additives (A) ，

whereby

the composition has a haze value， determined at 120℃， of 5.0 ％or below.
The polypropylene composition (PC) of claim 1， whereby the composition has a haze value， determined at 120℃， of 5.0 ％or below.
The polypropylene composition (PC) of claim 2， whereby

each of the additives (A) has a melting temperature determined by DSC of 100℃ or more； and

the polypropylene composition (PC) is free from additives having a melting temperature determined by DSC below 100℃.
The polypropylene composition (PC) according to any one of the preceding claims 1 to 4， wherein the total amount of polypropylenes (P) is at least 50 wt. ％based on the total amount of the polypropylene composition (PC) .
The polypropylene composition (PC) according to any one of the preceding claims 1 to 5， wherein the polypropylenes (P) comprises a heterophasic polypropylene (HECO) ， and/or a homopolymer of propylene.
The polypropylene composition (PC) according to any one of the preceding claims 1 to 6， further comprising a mineral filler in an amount of 1 to 45 wt. ％based on the total amount of the polypropylene composition.
The polypropylene composition (PC) according to claim 7， wherein the mineral filler is selected from glass fibers， carbon fibers， phyllosilicate， mica， wollastonite and mixtures thereof.
A method for producing the polypropylene composition (PC) according to any one of the preceding claims 1 to 8， comprising the following steps：

(i) providing one or more polypropylenes (P) ；

(ii) providing one or more additives (A) ， whereby each of the additives (A) has a melting temperature determined by DSC of 100℃ or more；

(iii) melt-mixing the polypropylenes (P) and the additives (A) ；

whereby

-no additives having a melting temperature determined by DSC below 100℃ are present in the polypropylenes (P) ； and

-no additives having a melting temperature determined by DSC below 100℃ are added during the process.
An article comprising the polypropylene composition (PC) according to any one of the preceding claims 1 to 8.
The article according to claim 10 being an injection-molded article such as interior and exterior automotive parts， preferably a lamp housing.
Use of additives having a melting temperature determined by DSC of 100℃ or more for reducing the haze of a polypropylene composition (PC) comprising one or more polypropylenes (P) .