WO2017009193A1

WO2017009193A1 - Composition comprising heterophasic propylene copolymer

Info

Publication number: WO2017009193A1
Application number: PCT/EP2016/066192
Authority: WO
Inventors: Said Fellahi; Azzedine KIOUL; Syed Mehmood Ahmed; Abdullah Shamroukh AL-OTAIBI
Original assignee: Sabic Global Technologies B.V.
Priority date: 2015-07-13
Filing date: 2016-07-07
Publication date: 2017-01-19

Abstract

The invention relates to a composition comprising (a) a heterophasic propylene copolymer consisting of 5 (i) a propylene-based matrix, wherein the propylene-based matrix consists of a propylene homopolymer and/or a propylene- α-olefin copolymer consisting of at least 70 wt% of propylene and at most 30 wt% of α-olefin, based on the total weight of the propylene-based matrix and wherein the propylene-based matrix is present in an amount of 60 to 95 wt% based on the total heterophasic propylene copolymer and (ii) a dispersed ethylene-α-olefin copolymer, wherein the dispersed ethylene-α-olefin copolymer is present in an amount of 40 to 5 wt% based on the total heterophasic propylene copolymer and wherein the sum of the total amount of propylene-based matrix and total amount of the dispersed ethylene-α-olefin copolymer in the heterophasic propylene copolymer is 100 wt% and (b) a polymer preferably chosen from the group consisting of polyoxymethylene, polyamide and mixtures thereof, wherein the amount of component (b) is from 0.005 to 5 wt% based on the total weight of the components (a) and (b) and wherein the heterophasic propylene copolymer (a) has a melt temperature TmPP and a crystallization temperature TcPP, the polymer (b) has a melt temperature TmP and a crystallization temperature TcP, wherein the TcP is 5-40 ºC higher than TcPP, wherein the T_m and T_c are determined using Differential Scanning Calorimetry according to ASTM D 3418-08 using a scan rate of 10°C/min on a sample of 10mg and using the second heating cycle.

Description

COMPOSITION COMPRISING HETEROPHASIC PROPYLENE COPOLYMER

The invention relates to a composition comprising a heterophasic propylene copolymer, to a process for obtaining such composition and to the use of such composition.

Heterophasic propylene copolymers, also known as impact propylene copolymers or propylene block copolymers, are an important class of polymers due to their attractive combination of mechanical properties, such as impact strength over a wide temperature range and their low cost. These copolymers find a wide range of applications ranging from the consumer industry (for example packaging and housewares), the automotive industry to electrical applications.

Nucleating agents are chemical compounds or compositions that enable faster nucleation or a higher crystallization temperature of thermoplastic polymers, resulting in productivity gains during their processing and in improved mechanical and physical properties of articles made from such thermoplastics. These compounds provide nucleation sites for crystal growth during cooling of a thermoplastic molten composition. In polypropylenes, for example, a higher degree of crystallinity and more uniform crystalline structure is obtained by adding a nucleating agent such as talc and carboxylate salts, e.g. sodium benzoate. An overview of nucleating agents used in polypropylene-based compositions is given for example in Polym. Adv. Technol. 2007, 18, 685-695. However, it is commonly recognized that the use of nucleating agents is a highly unpredictable technology area. Small changes in a molecular structure of the nucleator can drastically alter the ability of a nucleating agent to nucleate effectively a polymer composition. There are still many unknowns regarding the effect of a nucleating agent on polymer morphology during (re-)crystallization of thermoplastics.

WO2014202603 discloses a thermoplastic composition comprising a heterophasic propylene copolymer and a nucleating composition comprising a cyclic dicarboxylate salt compound and talc. The composition of WO2014202603 has good mechanical properties such as flexural modulus and impact strength.

Although the composition of WO2014202603 is satisfactory for some cases, there is a demand in the industry for a composition which is more cost efficient. It is an object of the invention to provide a composition in which above-mentioned and/or other problems are solved.

This object is achieved by a composition comprising

(a) a heterophasic propylene copolymer consisting of

(i) a propylene-based matrix,

wherein the propylene-based matrix consists of a propylene homopolymer and/or a propylene- a-olefin copolymer consisting of at least 70 wt% of propylene and at most 30 wt% of a-olefin, based on the total weight of the propylene-based matrix and

wherein the propylene-based matrix is present in an amount of 60 to 95 wt% based on the total heterophasic propylene copolymer and

(ii) a dispersed ethylene-a-olefin copolymer,

wherein the dispersed ethylene-a-olefin copolymer is present in an amount of 40 to 5 wt% based on the total heterophasic propylene copolymer and

wherein the sum of the total amount of propylene-based matrix and total amount of the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer is 100 wt%and

(b) a polymer preferably chosen from the group consisting of polyoxymethylene, polyamide and mixtures thereof,

wherein the amount of component (b) is from 0.005 to 5 wt% based on the total weight of the components (a) and (b) and

wherein

the heterophasic polypropylene copolymer (a) has a melt temperature TmPP and a crystallization temperature TcPP,

the polymer (b) has a melt temperature TmP and a crystallization temperature TcP, wherein the TcP is 5-40 °C higher than TcPP,

wherein the T_m (melt temperature) and T_c (crystallization temperature) are determined using Differential Scanning Calorimetry according to ASTM D 3418-08 using a scan rate of 10°C/min on a sample of 10mg and using the second heating cycle.

Preferably, the polymer having TcP which is 5-40 °C higher than TcPP is selected from polyoxymethylene, polyamide and mixtures thereof. The polyoxymethylene has a melt temperature TmPOM and a crystallization temperature TcPOM. The polyamide has a melt temperature TmPA and a crystallization temperature TcPA. TmPOM is higher than TmPP. TmPA is higher than TmPP. TcPOM is 5-40 °C higher than TcPP. TcPA is 5-40 °C higher than TcPP. It has surprisingly been found that the use of a polymer having TcP which is 5-40 °C higher than TcPP (preferably polyoxymethylene and/or polyamide) in a polypropylene composition comprising a heterophasic propylene copolymer provides an increase in heat distortion temperature, mechanical properties such as stress at yield, stress at break, elastic modulus, flexural strength and flexural modulus, as well as an increase in the degree of crystallinity and the crystallization temperature. The impact strength is maintained at an acceptable level or may even be increased. Strain at yield and strain at break are lowered.

A higher crystallization temperature means that the composition will crystallize with less cooling, as compared to a composition with a lower crystallization temperature. This is advantageous in many applications, such as for example injection molding. In a composition with a higher crystallization temperature, the cooling will go faster hence release from the mold can also be done faster. Hence, shorter cycle times for the preparation of articles can be achieved.

It is surprising that such polymer having TcP which is 5-40 °C higher than TcPP

(preferably polyoxymethylene and/or polyamide) has a similar effect to a polypropylene composition as a nucleating agent. It is hence possible to partly or completely replace the nucleating agent by less expensive polymer (preferably polyoxymethylene and/or polyamide) in accordance with the invention.

Compared to TcPP, TcP is at least 5 °C higher, for example at least 10 °C higher or at least 20 °C higher, and/or at most 40 °C higher, for example at most 30 °C higher.

Compared to TmPP, TmP is higher than TmPP, for example at least 1 °C higher, and/or for example at most 20 °C higher, at most 10 °C higher or at most 5 °C higher.

Preferably, compared to TmPP, TmPOM is at least 1 °C higher, and/or for example at most 20 °C higher, at most 10 °C higher or at most 5 °C higher.

Preferably, compared to TcPP, TcPOM is at least 5 °C higher, for example at least 10 °C higher or at least 20 °C higher, and/or at most 40 °C higher, for example at most 30 °C higher. Preferably, compared to TmPP, TmPA is at least 1 °C higher, and/or for example at most 20 °C higher, at most 10 °C higher or at most 5 °C higher. Preferably, compared to TcPP, TcPA is at least 5 °C higher, for example at least 10 °C higher or at least 25 °C higher, and/or at most 40 °C higher.

Preferably, TmPP is from about 140 to 180 °C, for example from about 145 to about 175°C, for example from about 150 to about 170°C, for example from about 155 to about 165°C.

Preferably, TcPP is from about 100°C to about 130°C, for example from about 1 10 to about 125°C, for example from about 1 15 to about 120°C. Preferably, TmPOM is from about 155 to about 175°C, for example from about 160 to 170 °C.

Preferably, TcPOM is from about 120 to about 155°C, for example from about 135 to about 150 °C. Preferably, TmPA is from about 175 to about 225°C, for example from about 180 to 200 °C.

Preferably, TcPA is from about 135 to about 170°C, for example from about 140 to about 160 °C. Preferably, the MVR (melt volume-flow rate) of the polyoxymethylene as measured in accordance with ISO 1 133 using a 2.16 kg weight and at a temperature of 190 °C is in the range from at least 1 cm³/10min, for example at least 2 cm³/10min, and/or at most 10 cm³/10min, for example at most 9 cm³/10min. This results in a good balance of mechanical properties. Particularly preferably, the MVR of the polyoxymethylene as measured in accordance with ISO 1133 using a 2.16 kg weight and at a temperature of 190 °C is from 3 to 9 cm³/10min, for example from 5 to 9 cm³/10min. This results in particularly good mechanical properties including an increased impact strength as well as particularly high flexural modulus. Preferably, the MFI of the polyamide as measured in accordance with ISO 1 133 using a 5 kg weight and at a temperature of 275 °C is in the range from 30 to 100 g/10min.

It has been found that by using a polymer with TcP 5-40 °C higher than TcPP (preferably polyoxymethylene and/or polyamide), it is no longer necessary to incorporate nucleating agent into a polypropylene composition for good mechanical properties. Without wishing to be bound by theory, it may be that the polymer with TcP 5-40 °C higher than TcPP (preferably polyoxymethylene and/or polyamide) acts as a nucleating agent even without the presence of a further nucleating agent. The polymer having a higher crystallization temperature than polypropylene crystallizes first upon cooling of the melted composition, after which the polypropylene crystallizes around the crystallized polymer. Alternatively, the polymer having TcP 5-40 °C higher than TcPP improves the mechanical properties of the polypropylene composition through a different mechanism. For example, the polymer having TcP 5-40 °C higher than TcPP may hinder crystallization (decrease crystallization rate) of the polypropylene matrix, unlike a nucleating agent, but still improves improves the mechanical properties.

In some embodiments, the composition may further comprise a nucleating agent, for example in an amount of about 0.1 parts per million (ppm) or more, of about 1 ppm or more, about 5 ppm or more, or about 10 ppm or more, based on the weight of the total weight of the polymer composition. In such embodiments, the nucleating agent typically is present in the polymer composition in an amount of about 10,000 ppm or less, about 5,000 ppm or less, or about 2,000 ppm or less.

Preferably, the composition comprises little or no further nucleating agent. For example, the composition comprises less than 1500ppm (parts per million as weight based on the total composition), for example less than l OOOppm , more preferably less than l OOOppm, for example less than 500ppm, for example less than 300ppm, for example less than l OOppm, for example less than 10ppm, for example less than 1 ppm, for example less than 0.1 ppm, for example less than 0.05ppm, for example less than 0.01 ppm of a nucleating agent, preferably of nucleating agents chosen from the group of benzoic acid salts, substituted benzoic acid salts, dicarboxylate metal salts,

hexahydrophthalic acid metal salts, phosphate ester salts, glycerolate salts, diamides, triamides, tetramides, pine rosin derivatives, di-acetal derivatives , 2,6-nephthalene dicarboxamides, polyvinylcyclohexanes, and combinations thereof. More preferably the composition does not substantially comprise any nucleating agent selected from the group of benzoic acid salts, substituted benzoic acid salts, dicarboxylate metal salts, hexahydrophthalic acid metal salts, phosphate ester salts, glycerolate salts, diamides, triamides, tetramides, pine rosin derivatives, di-acetal derivatives , 2,6-naphthalene dicarboxamides, polyvinylcyclohexanes and mixtures thereof. Further, in some embodiments, the composition comprises little or no talc or pigments as further nucleating agent. For example, the composition comprises less than 1500ppm (parts per million as weight based on the total composition), for example less than l OOOppm , more preferably less than l OOOppm, for example less than 500ppm, for example less than 300ppm, for example less than l OOppm, for example less than 10ppm, for example less than 1 ppm, for example less than 0.1 ppm, for example less than 0.05ppm, for example less than 0.01 ppm of talc or pigments as further nucleating agent.

Examples of benzoic acid salts suitable for use as the nucleating agent include, but are not limited to sodium benzoate, lithium benzoate, aluminum para-tertiary butyl benzoate, and combinations thereof.

For purpose of the invention with nucleating agent is meant any material that effectively accelerates the phase change from liquid polymer to semi-crystalline polymer (evident via faster crystallization rates measured with a differential scanning calorimeter or small crystallites observed with an optical microscope).

Examples of nucleating agents are 2,6-naphthalene dicarboxamides, aliphatic mono- and di- carboxylate salts such as calcium pimelate and calcium suberate; and polyvinylcyclohexane.

Phosphate esters suitable for use as the nucleating agent include, but are not limited to, sodium 2,2'-methylene-bis-(4,6-di- tert-butylphenyl)phosphate (from Asahi Denka Kogyo K. K., known as "NA- 1 1 (TM)"), aluminum hydroxy bis[2,2'-methylene-bis-(4,6-di-tert- butylphenyl)phosphate] (from Asahi Denka Kogyo K.K., known as "NA-21 (TM)"), and other such phosphate esters as disclosed for example in United States Patent Nos. 5,342,868 and 4,463,1 13.

Bicyclic dicarboxylate metal salts suitable for use as the nucleating agent include, but are not limited to, those salts described in U.S. Pat. Nos. 6,465,551 and 6,534,574. The bicyclic salts having the structure shown below:

wherein Mi and M2 are independently selected from the group consisting of: sodium, calcium, strontium, lithium, zinc, magnesium, and monobasic aluminum; wherein Ri , R2, R3, R4, R5, Re, R7, Re, R9, and R10 are independently selected from the group consisting of: hydrogen and C1-C9 alkyls; and further wherein any two adjacently positioned R3-R10 alkyl groups optionally may be combined to form a carbocyclic ring. In particular, suitable bicyclic dicarboxylate metal salts include disodium bicyclo[2.2.1]heptane-2,3- dicarboxylate, calcium bicyclo[2.2.1]heptane-2,3-dicarboxylate, and combinations thereof. One may employ HYPERFORM(R) HPN-68 or HPN-68L from Milliken & Company of Spartanburg, South Carolina. HPN-68L is commercially sold, and comprises the disodium bicyclo [2.2.1] heptane-2,3- dicarboxylate, as shown below:

Metal salts of hexahydrophthalic acid (HHPA) are known to the person skilled in the art. Such compounds may be as shown:

wherein Mi and M2 are the same or different, and may be combined into one cation, and are selected from at least one metal cation of calcium, strontium, lithium, and monobasic aluminum; and wherein Ri , R2, R3, R4, R5, Re, R7, Re, R9, and R10 are either the same or different and are individually selected from the group consisting of hydrogen, Ci- Cg alkyl, hydroxy, C1-C9 alkoxy, C1-C9 alkyleneoxy, amine, and C1-C9 alkylamine, halogens, and phenyl. In one preferred embodiment, the Mi and M2 are combined as a calcium ion. Ca HHPA as referred to herein refers to the following compound:

Ca HHPA

Di-acetal derivatives, which may be used as nucleating agent include, but are not limited to, alditol acetals, such as the sorbitol di-acetals described in U.S. Patent No. 5,049,605. Suitable di-acetal derivatives preferably conform to the formula

In formula (I), n typically is a value selected from 0, 1 , or 2. R typically is selected from the group consisting of hydrogen, alkenyl (such as allyl), alkyl, alkoxy, hydroxylalkyl, alkyl-halide, aromatic and substituted aromatic groups. Ri , R2, R3, R4, R5, Re, R7, Re, R9, and R10 typically are independently selected from the group consisting of hydrogen, fluorocarbons, alkenyl, alkyl, alkynyl, alkoxy, carboxy, halides, amino, thioether and aromatic groups. In certain embodiments, any two adjacent groups selected from Ri , R2, R3, R4, R5, Re, R7, Re, R9, and R10 may be combined to form a cyclic group selected from the group consisting of methylenedioxy, cyclopentyl, cyclohexyl, or other similar cyclic groups. In certain embodiments, the nucleating agent preferably is 1 ,3:2,4-bis(3,4- dimethylbenzylidene) sorbitol (hereinafter DMDBS), available from Miliiken Chemical under the trade name Millad(R) 3988.

Di-, tri-, and tetra-amides suitable for use as the nucleating agent include, but are not limited to: di- and tri-amides containing amide cores comprised of either single and fused 4,5,6,7-membered aromatic or cycloaliphatic rings; di- and tri-amides containing amide cores comprised of di and tri aliphatic carboxylic acids or di and tri aliphatic amines; and tri- and tetra- amides containing amide cores comprised of aliphatic tri- and tetracarboxylic acids and aliphatic or cycloaliphatic amines. These compounds are exemplified in patent publications, including WO 2004072168, EP 0940431 and WO 200506387. ln some embodiments, the composition according to the invention comprises a nucleating agent in an amount of 10-2000 ppm, preferably 100-1500 ppm, and the nucleating agent is sodium benzoate. Heterophasic propylene copolymer

Heterophasic propylene copolymers are generally prepared in one or more reactors, by polymerization of propylene in the presence of a catalyst and subsequent polymerization of a propylene-oolefin mixture. The resulting polymeric materials are heterophasic, but the specific morphology usually depends on the preparation method and monomer ratios used.

The heterophasic propylene copolymers employed in the process according to present invention can be produced using any conventional technique known to the skilled person, for example multistage process polymerization, such as bulk polymerization, gas phase polymerization, slurry polymerization, solution polymerization or any combinations thereof. Any conventional catalyst systems, for example, Ziegler-Natta or metallocene may be used. Such techniques and catalysts are described, for example, in WO06/010414; Polypropylene and other Polyolefins, by Ser van der Ven, Studies in Polymer Science 7, Elsevier 1990; WO06/010414, US4399054 and US4472524.

Preferably, the heterophasic propylene copolymer is made using Ziegler-Natta catalyst.

The heterophasic propylene copolymer may be prepared by the process comprising - polymerizing propylene and optionally a-olefin in the presence of a catalyst system to obtain the propylene-based matrix and

- subsequently polymerizing ethylene and a-olefin in the propylene-based matrix in the presence of a catalyst system to obtain the dispersed ethylene-a olefin copolymer. These steps are preferably performed in different reactors. The catalyst systems for the first step and for the second step may be different or same. The heterophasic propylene copolymer of the composition of the invention consists of a propylene-based matrix and a dispersed ethylene-oolefin copolymer. The propylene- based matrix typically forms the continuous phase in the heterophasic propylene copolymer. The amounts of the propylene-based matrix and the dispersed ethylene-a- olefin copolymer may be determined by ¹³C-NMR, as well known in the art.

The heterophasic propylene copolymer consists of (i) a propylene-based matrix,

wherein the propylene-based matrix consists of a propylene homopolymer and/or a propylene-oolefin copolymer consisting of at least 70 wt% of propylene and at most 30 wt% of a-olefin, based on the total weight of the propylene-based matrix and

(ii) a dispersed ethylene-oolefin copolymer,

wherein the sum of the total amount of propylene-based matrix and total amount of the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer is 100 wt%.

The propylene-based matrix consists of a propylene homopolymer and/or a propylene- a-olefin copolymer consisting of at least 70 wt% of propylene and up to 30 wt% of a- olefin, for example ethylene, for example consisting of at least 80 wt% of propylene and up to 20 wt% of a-olefin, for example consisting of at least 90 wt% of propylene and up to 10 wt% of a-olefin, based on the total weight of the propylene-based matrix. Preferably, the α-olefin in the propylene- a-olefin copolymer is selected from the group of a-olefins having 2 or 4-10 carbon atoms, for example ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexen, 1-heptene or 1-octene, and is preferably ethylene.

Preferably, the propylene-based matrix consists of a propylene homopolymer.

The melt flow index (MFI) of the propylene-based matrix (before it is mixed into the composition of the invention), (MFIPP) may be for example at least 0.1 dg/min, at least 0.2 dg/min, at least 0.3 dg/min, at least 0.5 dg/min, at least 1 dg/min, at least 1.5 dg/min, and/or for example at most 50 dg/min, at most 40 dg/min, at most 30 dg/min, at most 25 dg/min, at most 20 dg/min, measured according to ASTM D 1238 (2.16 kg/230°C).

Preferably, the MFIPP is 10-40 dg/min, for example 30-40 dg/min, measured according to ASTM D 1238 (2.16 kg/230°C), for preparing a heterophasic propylene copolymer suitable for injection molding.

The propylene-based matrix is present in an amount of 60 to 95wt%, for example 65 to 85 wt%, for example 70 to 85wt%, for example 70 to 80wt%, for example 65 to 75wt% or 75 to 85wt% based on the total heterophasic propylene copolymer.

The propylene-based matrix is preferably semi-crystalline, that is it is not 100% amorphous, nor is it 100% crystalline. For example, the propylene-based matrix is at least 40% crystalline, for example at least 50%, for example at least 60% crystalline and/or for example at most 80% crystalline, for example at most 70% crystalline. For example, the propylene-based matrix has a crystallinity of 60 to 70%. For purpose of the invention, the degree of crystallinity of the propylene-based matrix is measured using differential scanning calorimetry (DSC) according to IS01 1357-1 and IS01 1357-3 of 1997, using a scan rate of 10°C/min, a sample of 5mg and the second heating curve using as a theoretical standard for a 100% crystalline material 207.1 J/g.

Besides the propylene-based matrix, the heterophasic propylene copolymer also comprises a dispersed ethylene-oolefin copolymer. The dispersed ethylene-oolefin copolymer is also referred to herein as the 'dispersed phase'. The dispersed phase is embedded in the heterophasic propylene copolymer in a discontinuous form. The particle size of the dispersed phase is typically in the range of 0.05 to 2.0 microns, as may be determined by transmission electron microscopy (TEM). The MFI of the dispersed ethylene a-olefin copolymer (before it is mixed with other components of the composition of the invention) (MFIEPR) may be for example at least 0.001 dg/min, at least 0.01 dg/min, at least 0.1 dg/min, at least 0.3 dg/min, at least 0.7 dg/min, at least 0.8 dg/min or at least 1 dg/min, and/or for example at most 30 dg/min, at most 20 dg/min, at most 15 dg/min at most 10 dg/min, at most 5 dg/min or at most 1 dg/min. The MFI of the dispersed ethylene a-olefin copolymer (MFIEPR) is calculated taking into account the MFI of the propylene-based matrix (MFIPP), the MFI of the heterophasic propylene copolymer (MFIheterophasic) and rubber content (RC) according to the following formula: if FISPB 1§_&ζ^^β^ MFlfntArapkasie— matt* ffseiefit * isg M PP

In some embodiments, MFIEPR is 0.1-5 dg/min, 0.5-3 dg/min or 0.8-1 dg/min. This is particularly preferred for preparing a heterophasic propylene copolymer suitable for injection molding. The dispersed ethylene-a-olefin copolymer is present in an amount of 40 to 5 wt%, for example in an amount of at least 8 wt% or at least 10 wt%, and/or at most 35 wt%, at most 30 wt%, at most 25 wt% or at most 20 wt%, based on the total heterophasic propylene copolymer.

In the heterophasic polypropylene in the composition of the invention, the sum of the total weight of the propylene-based matrix and the total weight of the dispersed ethylene-a-olefin copolymer is 100 wt%. The amount of ethylene in the ethylene-a-olefin copolymer is preferably in the range of 15-65 wt% based on the ethylene-a-olefin copolymer. More preferably, the amount of ethylene in the ethylene-a-olefin copolymer is 30-62 wt%, more preferably 40-60 wt%.

The a-olefin in the ethylene-a-olefin copolymer is preferably chosen from the group of a- olefins having 3 to 8 carbon atoms and any mixtures thereof, preferably the a-olefin in the ethylene-a-olefin copolymer is chosen from the group of a-olefins having 3 to 4 carbon atoms and any mixtures thereof, more preferably the α-olefin is propylene, in which case the ethylene-a-olefin copolymer is ethylene-propylene copolymer. Examples of suitable a-olefins having 3 to 8 carbon atoms, which may be employed as ethylene comonomers to form the ethylene α-olefin copolymer include but are not limited to propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexen, 1-heptene and 1-octene.

The MFI of the heterophasic propylene copolymer (MFIheterophasic) may be for example at least 0.1 dg/min, at least 0.2 dg/min, at least 0.3 dg/min, at least 0.5 dg/min, at least 1 dg/min, at least 1.5 dg/min, at least 3 dg/min, at least 5 dg/min or at least 10 dg/min, and/or for example at most 120 dg/min, at most 100 dg/min, at most 80 dg/min, at most 60 dg/min, at most 50 dg/min, at most 40 dg/min, at most 30 dg/min, at most 25 dg/min, at most 20 dg/min, at most 15 dg/min or at most 10 dg/min, measured according to ASTM D 1238 (2.16 kg/230°C). Preferably, the MFIheterophasic is 5-120 dg/min measured according to ASTM D 1238 (2.16 kg/230°C), for suitable use for injection molding.

The values of the MFI of the propylene-based matrix (MFIPP) and the MFI of the dispersed ethylene-a-olefin elastomer (MFIEPR) mentioned herein are understood as the values before the heterophasic propylene copolymer is mixed with component (B) and optional component (C) to obtain the composition according to the invention. The value of the MFI of the heterophasic propylene copolymer (MFI heterophasic) refers to the final MFI of the heterophasic propylene copolymer. To exemplify this:

In case the heterophasic propylene copolymer is not subjected to vis-breaking or shifting by melt-mixing with a peroxide, the MFIheterophasic is the original MFI value of the heterophasic propylene copolymer. In case the heterophasic propylene copolymer is subjected to vis-breaking or shifting by melt-mixing with a peroxide, the MFIheterophasic is the value of the heterophasic propylene copolymer after such vis-breaking or shifting.

Preferably, the amount of the heterophasic propylene copolymer in the composition of the invention is at least 80wt%, for example at least 85wt%, for example at least 90wt%, for example at least 95wt%, for example at least 97wt%, for example at least 98wt% based on the total composition.

POM

Polyoxymethylene (POM) is also known as polyacetal and may be one or more homopolymers, copolymers, or a mixture of these. The polyoxymethylene (or polyacetal) polymers described herein can be branched or linear and generally have a number average molecular weight of at least 10,000, preferably 20,000 to 90,000. The molecular weight may be measured: 1 ) by gel permeation chromatography in m-cresol at 160 degrees centigrade using a DuPont PSM bimodal column kit with nominal pore size of 60 and 1000 angstrom; or 2) by determining the melt flow using ASTM D1238 or ISO 1 133.

Polyacetal homopolymers are prepared by polymerizing formaldehyde or formaldehyde equivalents, such as cyclic oligomers of formaldehyde. Preferred are homopolymers having terminal hydroxyl groups that are-capped by a chemical reaction to form ester or other groups. Preferred end groups for homopolymers are acetate and methoxy.

Polyacetal copolymers can contain one or more typical co-monomers, which include acetals and cyclic ethers that lead to the incorporation into the polymer chain of ether units with 2 to 12 sequential carbon atoms. When these compositions include such a copolymer, the quantity of co-monomer will not be more than 20 weight percent, preferably not more than 15 weight percent, and most preferably about two weight percent. Preferable co-monomers include ethylene oxide, butylene oxide and, more preferably1 ,3-dioxolane. In general, preferable polyoxymethylene copolymers are those for which the quantity of co-monomer is about 2 weight percent and are not completely end-capped, but have some free hydroxy ends from the co-monomer unit or are terminated with ether groups. Preferred end groups for copolymers are hydroxy and methoxy.

Polyamide

The polyamide may be homopolymer, copolymer, terpolymer or higher order polymer. Blends of two or more polyamides may be used. Suitable polyamides can be condensation products of dicarboxylic acids or their derivatives and diamines, and/or aminocarboxylic acids, and/or ring-opening polymerization products of lactams.

Suitable dicarboxylic acids include, adipic acid, azelaic acid, sebacic acid,

dodecanedioic acid, isophthalic acid and terephthalic acid. Suitable diamines include tetramethylenediamine, hexamethylenediamine, octamethylenediamine,

nonamethylenediamine, dodecamethylenediamine, 2- methylpentamethylenediamine, 2- methyloctamethylenediamine, trimethylhexamethylenediamine, bis(p- aminocyclohexyl)methane, m- xylylenediamine, and p-xylylenediamine. A suitable aminocarboxylic acid is 1 1-aminododecanoic acid. Suitable lactams include caprolactam and laurolactam.

Preferred aliphatic polyamides include polyamide 6; polyamide 66; polyamide 46;

polyamide 69; polyamide 610; polyamide 612; polyamide 1010; polyamide 1 1 ;

polyamide 12; semi-aromatic polyamides such as poly(m-xylylene adipamide)

(polyamide MXD6), poly(dodecamethylene terephthalamide) (polyamide 12T), poly(decamethylene terephthalamide) (polyamide 10T), poly(nonamethylene terephthalamide) (polyamide 9T), the polyamide of hexamethylene terephthalamide and hexamethylene adipamide (polyamide 6T/66); the polyamide of

hexamethyleneterephthalamide and 2- methylpentamethyleneterephthalamide

(polyamide 6T/DT); the polyamide of hexamethylene isophthalamide and

hexamethylene adipamide (polyamide 61/66); the polyamide of hexamethylene terephthalamide, hexamethylene isophthalamide, and hexamethylene adipamide (polyamide 6T/6I/66) and copolymers and mixtures of these polymers. Examples of suitable aliphatic polyamides include polyamide 66/6 copolymer; polyamide 66/68 copolymer; polyamide 66/610 copolymer; polyamide 66/612 copolymer; polyamide 66/10 copolymer; polyamide 66/12 copolymer; polyamide 6/68 copolymer; polyamide 6/610 copolymer; polyamide 6/612 copolymer; polyamide 6/10 copolymer; polyamide 6/12 copolymer; polyamide 6/66/610 terpolymer; polyamide 6/66/69 terpolymer;

polyamide 6/66/1 1 terpolymer; polyamide 6/66/12 terpolymer; polyamide

6/610/1 1 terpolymer; polyamide 6/610/12 terpolymer; and polyamide 6/66/PACM (bis-p- {aminocyclohexyl} methane) terpolymer.

Preferred examples of the polyamide include polyamide 6 and polyamide 66.

The polyamide may be a glass fiber reinforced polyamide. The glass fibers may be any glass fibers available for the reinforcement of plastic materials. The amount of the glass fiber may e.g. be 1-50 wt%, 5-45 wt%, 10-40 wt% or 30-35 wt% of the total of the glass fiber and the polyamide. The glass fibers include, but are not limited to, chopped strand E-glass fibers.

Non-glass fiber reinforced polyamides and glass fiber reinforced polyamides are commercially available e.g. from DuPont under the brand name Zytel ®.

Amount of the polymer having TcP which is 5-40 °C higher than TcPP

In the composition of the invention, the amount of the polymer having TcP which is 5-40 °C higher than TcPP is from 0.005 to 5 wt% based on the total weight of the

heterophasic propylene copolymer and said polymer in the composition.

In the composition of the invention, when present, the total amount of POM and polyamide is from 0.005 to 5 wt% based on the total weight of the the heterophasic propylene copolymer, the POM and the polyamide in the composition.

The composition of the invention may comprise either one or both of POM and polyamide.

In the cases where the composition of the invention comprises POM but not polyamide, the amount of POM in the composition is preferably at least 0.01 , for example at least 0.02, for example at least 0.03, for example at least 0.04, for example at least 0.05, for example at least 0.1 , for example at least 0.2, for example at least 0.3, for example at least 0.4, for example at least 0.5, for example at least 0.7, for example at least 1 , for example at least 2 and/or for example at most 3, for example at most 1.5, for example at most 1wt% based on the total weight of components a) and b) in the composition.

Preferably, the amount of POM in the composition is from about 0.01 to about 5 wt% based on the total weight of components a) and b) in the composition. The composition comprising no polyamide is herein understood to mean that the composition comprises less than 1500ppm (parts per million as weight based on components a) and b) of the composition) of polyamide, for example less than l OOOppm , more preferably less than l OOOppm, for example less than 500ppm, for example less than 300ppm, for example less than l OOppm, for example less than 10ppm, for example less than 1 ppm, for example less than 0.1 ppm, for example less than 0.05ppm, for example less than 0.01 ppm based on components a) and b) of the composition. In the cases where the composition of the invention comprises polyamide but not POM, the amount of polyamide in the composition is preferably at least 0.01 , for example at least 0.02, for example at least 0.03, for example at least 0.04, for example at least 0.05, for example at least 0.1 , for example at least 0.2, for example at least 0.3, for example at least 0.4, for example at least 0.5, for example at least 0.7, for example at least 1 , for example at least 2 and/or for example at most 3, for example at most 1.5, for example at most 1wt% based on the total weight of the polypropylene and the polyamide in the composition. Preferably, the amount of polyamide in the composition is from about 0.01 to about 5 wt% based on the total weight of components a) and b) in the composition. The composition comprising no POM is herein understood to mean that the composition comprises less than 1500ppm (parts per million as weight based on components a) and b) of the composition) of POM, for example less than l OOOppm , more preferably less than l OOOppm, for example less than 500ppm, for example less than 300ppm, for example less than l OOppm, for example less than 10ppm, for example less than 1 ppm, for example less than 0.1 ppm, for example less than 0.05ppm, for example less than 0.01 ppm based on components a) and b) of the composition.

In the cases where the composition of the invention comprises POM and polyamide, the amount of the total of POM and polyamide in the composition is preferably at least 0.01 , for example at least 0.02, for example at least 0.03, for example at least 0.04, for example at least 0.05, for example at least 0.1 , for example at least 0.2, for example at least 0.3, for example at least 0.4, for example at least 0.5, for example at least 0.7, for example at least 1 , for example at least 2 and/or for example at most 3, for example at most 1.5, for example at most 1wt% based on the total weight of components a) and b) in the composition. Preferably, the amount of the total of POM and polyamide in the composition is from about 0.01 to about 5 wt% based on the total weight of components a) and b) in the composition. The weight ratio between POM to polyamide may be chosen at any value. The weight ratio between POM to polyamide may e.g. be at least 1 :1000, at least 1 :100, at least 1 :50, at least 1 :20, at least 1 :10, at least 1 :5, at least 1 :3, at least 1 :2; at least 1 : 1 , at least 2: 1 , at least 3: 1 , at least 5: 1 , at least 10: 1 , at least 20: 1 , at least 50: 1 , at least 100: 1 or at least 1000: 1. The weight ratio between POM to polyamide may e.g. be at most 1 :1000, at most 1 :100, at most 1 :50, at most 1 :20, at most 1 : 10, at most 1 :5, at most 1 :3, at most 1 :2; at most 1 : 1 , at most 2: 1 , at most 3: 1 , at most 5: 1 , at most 10: 1 , at most 20: 1 , at most 50: 1 , at most 100: 1 or at most 1000: 1.

Additives

Optionally, additives may be present in the composition of the present invention. The additives may for example be added prior to or during the melt-mixing of the polymer having TcP which is 5-40 °C higher than TcPP (preferably the POM and/or PA ) with the heterophasic polypropylene copolymer. Examples of suitable additives include but are not limited to the additives usually used for heterophasic polypropylene copolymer, for example antioxidants, acid scavengers, processing aids, lubricants, surfactants, blowing agents, ultraviolet light absorbers, quenchers, antistatic agents, slip agents, antiblocking agents, antifogging agents, pigments, dyes and fillers such as talc. The additives may be present in the typically effective amounts well known in the art, such as 0.001 weight % to 10 weight % based on the total composition. Typically, the amount of talc as filler is at least 5 weight %.

Therefore, the invention also relates to a composition of the invention further comprising additives. In some embodiments, the composition according to the invention can be obtained by melt-mixing a peroxide with the heterophasic propylene copolymer (a) and polymer (b). The composition obtained by the addition of a peroxide has a different (higher) MFI from the MFI of the heterophasic propylene copolymer used in preparing the composition. This step is also known in the art as vis-breaking or shifting. The term "visbreaking" is well known in the field of the invention. For example methods of visbreaking

polypropylene have been disclosed in US 4,282,076 and EP 0063654. It is also possible to first melt-mix a peroxide with the heterophasic propylene copolymer, which changes the melt flow index of the heterophasic propylene copolymer, and then mix with polymer (b). Examples of organic peroxides are well known and include dialkyl peroxides, e.g. dicumyl peroxides, peroxyketals, peroxycarbonates, diacyl peroxides, peroxyesters and peroxydicarbonates. Specific examples of these include benzoyl peroxide,

dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5- di(peroxybenzoato)-3-hexene, 1 ,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butyl peracetate, a,a'-bis(tert-butylperoxy)diisopropylbenzene (Luperco® 802), 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexene, 2,5-dimethyl-2,5-di(tert- butylperoxy)-hexane, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl per- sec-octoate, tert-butyl perpivalate, cumyl perpivalate.

It can easily be determined by the person skilled in the art through routine

experimentation how much peroxide should be used to obtain a composition having the desired melt flow index. This also depends on the half-life of the peroxide and on the conditions used for the melt-mixing, which in turn depend on the exact composition of the heterophasic propylene copolymer.

When a peroxide is used, the amount of peroxide will typically lie in the range of 0.02 to 0.5 wt% based on the heterophasic propylene copolymer. In some embodiments, the composition according to the invention is prepared without using a peroxide.

The composition of the invention may be prepared by melt-mixing the polymer having TcP which is 5-40 °C higher than TcPP (preferably the POM and/or PA) with the heterophasic propylene copolymer.

Therefore, in another aspect, the invention also relates to a process for the preparation of the composition of the invention comprising the step of

- melt-mixing the polymer having TcP which is 5-40 °C higher than TcPP (preferably POM and/or the PA) with the heterophasic propylene copolymer and the optional additives.

Before melt-mixing, the polymer having TcP which is 5-40 °C higher than TcPP (preferably the POM and/or the PA) and the heterophasic propylene copolymer and the optional additives may be pre-mixed in a mixer, for example a dry blender (as may be purchased from Henschell). The polymer having TcP which is 5-40 °C higher than TcPP (preferably the POM and/or the PA) and the heterophasic propylene copolymer are preferably pre-mixed or melt-mixed in the form of a powder or granules but, although less preferred may also be melt-mixed in the form of pellets.

After the melt-mixing, the composition obtained in the melt-mixing may be pelletized.

With melt-mixing is meant that the polymer having TcP which is 5-40 °C higher than TcPP (preferably the POM and/or the PA) and the heterophasic polypropylene copolymer are mixed at a temperature that exceedsTmP and TcP. Melt-mixing may be done using techniques known to the skilled person, for example in an extruder, for example a single screw or twin screw extruder, preferably a twin screw extruder.

Suitable conditions for melt-mixing, such as temperature, pressure, amount of shear, screw speed and screw design when an extruder is used are known to the skilled person.

When using an extruder, a conventional extruder such as a twin-screw extruder may be used. The temperature can vary through the different zones of the extruder as required. For example, the temperature may vary from 150°C in the feed zone to 300°C at the die. Preferably, the temperature in the extruder varies from 165 to 250°C; likewise, the screw speed of the extruder may be varied as needed. Typical screw speeds are in the range from about l OOrpm to about 400rpm.

It has been found that the heat distortion temperature, flexural modulus, elastic modulus and crystallization temperature are improved according to the invention as compared to a polypropylene composition not containing the polymer having Tc which is 5-40 °C higher than Pc such as POM and/or PA.

One application of thin wall injection molding is thin wall packaging. Thin wall packaging produced via thin wall injection molding provides an answer to the desire for a more sustainable way of packaging, since less material and energy are needed for the injection molding. Consequently, thin wall packaging produced via thin wall injection molding reduces the carbon footprint of the packaging.

In another aspect, therefore, the invention relates to the use of the composition of the invention in injection molding, in particular to thin wall injection molding. The most optimal conditions for (thin wall) injection molding depend on the exact composition used. In general, the temperature for injection molding will be around the T_m or Tc of the component (b) in the composition of the invention, for example in the range from about 150 to about 200°C, for example in the range from about 150 to about 170°C, for example from about 155 to about 165°C. The optimal filling speed (generally less than 0.5 seconds for thin wall injection molding) and pressure with which the composition is injected into the mold, the time needed for cooling etc. can easily be determined by the person skilled in the art. For short cycle times, it is desired to keep the time that the composition is in the mold as short as possible.

The definition of thin wall is dynamic, since it depends upon the application for which it is used. Within the framework of this invention with 'thin wall' is meant a wall thickness in the range from 0.5 to 3.5, preferably 0.5 to 2 mm. Examples of thin wall packaging items include but are not limited to: food packaging items, such as tubs, trays, jars, containers, lids, plates and cups

Since the compositions of the invention may have a high heat distortion temperature as well as a low brittleness around freezing temperature, articles produced from said composition can be used at high as well as at lower temperatures.

Application areas where use at both higher and lower temperatures are desired are for example food applications, for example microwaveable, freezer-safe and ovenable containers and medical applications, where sterilization is needed prior to the filling of a container, but the medication inside the container needs to be stored at a low temperature (e.g. from 4 to 7°C).

In another aspect, the invention relates to articles comprising the composition of the invention, wherein the article is prepared by injection molding, preferably thin wall injection molding.

In yet another aspect, the invention relates to a process comprising the step of injecting the composition of the invention in a mold, preferably a thin wall mold, wherein a thin wall mold is a mold providing a space having a wall thickness in the range from 0.5 to 2 mm. The invention further relates to use of a polymer (b) preferably chosen from the group consisting of polyoxymethylene, polyamide and mixtures thereof for increasing heat distortion temperature, stress at yield, stress at break, elastic modulus, flexural strength, flexural modulus, degree of crystallinity, crystallization temperature and/or impact strength of a composition comprising

(a) a heterophasic propylene copolymer consisting of

(i) a propylene-based matrix,

wherein the propylene-based matrix consists of a propylene homopolymer and/or a propylene- a-olefin copolymer consisting of at least 70 wt% of propylene and at most 30 wt% of a-olefin, based on the total weight of the propylene-based matrix and wherein the propylene-based matrix is present in an amount of 60 to 95 wt% based on the total heterophasic propylene copolymer and

(ii) a dispersed ethylene-a-olefin copolymer,

wherein the sum of the total amount of propylene-based matrix and total amount of the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer is 100 wt%

wherein the heterophasic propylene copolymer (a) has a melt temperature TmPP and a crystallization temperature TcPP,

wherein the polymer (b) has a melt temperature TmP and a crystallization temperature TcP,

wherein the TcP is 5-40 °C higher than TcPP,

wherein the T_m and T_c and the degree of crystallinity are determined using Differential Scanning Calorimetry according to ASTM D 3418-08 using a scan rate of 10°C/min on a sample of 10mg and using the second heating cycle,

wherein the heat distortion temperature is measured according to ASTM D-648, the stress at yield is measured according to ASTM D-638,

the stress at break is measured according to ASTM D-638,

the elastic modulus is measured according to ASTM D-638,

the flexural strength is measured according to ASTM D-790A,

the flexural modulus is measured according to ASTM D-790A and

the impact strength is measured according to ASTM D-256 at 23 °C. In particular, the invention relates to the use of the polymer (b) for increasing heat distortion temperature, elastic modulus, flexural strength, flexural modulus, degree of crystallinity and crystallization temperature in the composition comprising the heterophasic propylene copolymer.

Although the invention has been described in detail for purposes of illustration, it is understood that such detail is solely for that purpose and variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the claims.

It is further noted that the invention relates to all possible combinations of features described herein, preferred in particular are those combinations of features that are present in the claims. It will therefore be appreciated that all combinations of features relating to the composition according to the invention; all combinations of features relating to the process according to the invention and all combinations of features relating to the composition according to the invention and features relating to the process according to the invention are described herein.

It is further noted that the term 'comprising' does not exclude the presence of other elements. However, it is also to be understood that a description on a

product/composition comprising certain components also discloses a

product/composition consisting of these components. The product/composition consisting of these components may be advantageous in that it offers a simpler, more economical process for the preparation of the product/composition. Similarly, it is also to be understood that a description on a process comprising certain steps also discloses a process consisting of these steps. The process consisting of these steps may be advantageous in that it offers a simpler, more economical process.

The invention is now elucidated by way of the following examples, without however being limited thereto.

Experiments

In experiments 1-4, compositions were injection molded in the Battenfeld Injection molding machine using 2 mm thick plaque mold according the following operating conditions. The heterophasic propylene copolymer composition and polyoxymethylene were cryogenically grinded in powder form prior to injection molding. Table 1

The composition used for injection molding comprises a heterophasic propylene copolymer composition and various nucleating agents indicated in Table 2. Various properties were measured according to methods indicated in Table 2 and results are also in Table 2. heterophasic propylene copolymer composition

The heterophasic propylene copolymer composition is a composition comprising a heterophasic propylene copolymer which has a matrix of propylene homopolymer and a dispersed phase of ethylene-propylene copolymer, as well as a nucleating agent and an antistatic agent.

The heterophasic propylene copolymer composition has an MFI of 21 g/10min

(measured in accordance with ASTM D1238 using a 2.16 kg weight and at a temperature of 230 °C) and a density of 0.905 g/cm3.

In the heterophasic propylene copolymer, the amount of the dispersed phase with respect to the heterophasic propylene copolymer (RC) is 14.5 wt%. The amount of ethylene in the dispersed phase (RCC2) is 49.1 wt% with respect to the dispersed phase. The amount of ethylene in the heterophasic propylene copolymer is 7.1 wt%.

The type of the nucleating agent in the heterophasic propylene copolymer composition is sodium benzoate and its amount is 900 ppm. The type of the antistatic agent in the heterophasic propylene copolymer composition is glycerol monostearate (GMS 90) and its amount is 3000 ppm.

HPN-20E

66 wt% of Ca hexahydrophthalic acid (nucleating agent) and 34 wt% of zinc stearate (acid scavenger)

POM1

Hostaform C2521 from Ticona (Celanese). Tm: 166 °C and Tc:129 °C. Melt volume flow rate (MVR): 2.5 cm³/10min

POM2

Hostaform C9021 from Ticona (Celanese). Tm: 168.5 °C and Tc:146 °C. Melt volume flow rate (MVR): 8.0 cm³/10min Tm and T_c of POM were determined using Differential Scanning Calorimetry according to ASTM D 3418-08 using a scan rate of 10°C/min on a sample of 10mg and using the second heating cycle. MVR was determined by ISO 1 133 using a 2.16 kg weight and at a temperature of 190 °C.

Table 2 Compositions and their properties

1 2 3 4

Various properties were measured by the following method:

The heat distortion temperature (HDT) was determined using ASTM D648-07 at 0.455 MPa on a 3.2 mm sample, wherein the temperature is increased at 2 degrees centigrade /min until the sample deflects 0.25 mm.

The Vicat softening point was as determined using ASTM D 1525-09 using a 1 mm² needle having a circular cross-section and a load of 10N wherein the temperature is increased at 2 degrees centigrade/min until the needle penetration reaches 1 mm. The melt temperature (T_m) and the crystallization temperature (T_c) of the heterophasic propylene copolymer compositions were determined using Differential Scanning Calorimetry according to ASTM D 3418-08 using a scan rate of 10°C/min on a sample of 10mg and using the second heating cycle.

The degree of crystallinity (Xc) was measured using Differential Scanning Calorimetry according to ASTM D 3418-08 using a scan rate of 10 degrees centigrade /min on a sample of 10 mg and using the second heating cycle.

The obtained compositions were injection molded at a temperature of around 160 degrees centigrade to obtain dog bones, flexural, Izod bars and rectangular plaques of 3.2 mm thickness.

The impact strength was measured according to ASTM D-256 (measured at 23 °C). The stress at yield, strain at yield and the elastic modulus were measured according to D-638.

The flexural strength and the flexural modulus were measured according to D-790A.

It is found that the addition of POM to a heterophasic propylene copolymer leads to an Increase in HDT, stiffness, Toughness and crystallization and crystallization

temperature. Since the compositions according to the invention have a higher crystallization temperature, the composition will crystallize at a higher temperature and articles can be released from a mould faster. Hence, shorter cycle times for the preparation of articles can be achieved.

Further, in comparison with the addition of a known nucleating agent HPN-20E, the impact strength is higher in the compositions according to the invention. It is particularly notable that the addition of POM-2 led to an increase in the impact strength compared to when POM was not added.

Claims

1. A composition comprising

(a) a heterophasic propylene copolymer consisting of

(i) a propylene-based matrix,

(ii) a dispersed ethylene-a-olefin copolymer,

and

wherein

the heterophasic propylene copolymer (a) has a melt temperature TmPP and a crystallization temperature TcPP,

wherein the T_m and T_c are determined using Differential Scanning Calorimetry according to ASTM D 3418-08 using a scan rate of 10°C/min on a sample of 10mg and using the second heating cycle.

2. Composition according to claim 1 , wherein the composition comprises the polyoxymethylene, the polyoxymethylene has a melt temperature TmPOM and a crystallization temperature TcPOM and TmPOM is 1-20 °C higher than TmPP and TcPOM is 5-40 °C higher than TcPP.

3. Composition according to claim 1 or 2, wherein the composition comprises the polyamide, the polyamide has a melt temperature TmPA and a crystallization temperature TcPA and TmPA is 1-20 °C higher than TmPP and TcPA is 5-40 °C higher than TcPP.

4. Composition according to any one of claims 1-3, wherein the melt flow index of the heterophasic propylene copolymer as measured in accordance with ASTM D 1238 using a 2.16 kg weight and at a temperature of 230 °C in the range from 10 to 40 g/10min.

5. Composition according to any one of claims 1-4, wherein the composition comprises less than 1500ppm of nucleating agents selected from the group of benzoic acid salts, substituted benzoic acid salts, dicarboxylate metal salts, hexahydrophthalic acid metal salts, phosphate ester salts, glycerolate salts, diamides, triamides, tetramides, pine rosin derivatives, di-acetal derivatives, 2,6-naphthalene dicarboxamides,

polyvinylcyclohexanes and combinations thereof.

6. Composition according to any one of claims 1-5, wherein the composition of the invention comprises polyoxymethylene but no polyamide and the amount of

polyoxymethylene is from about 0.01 to 5wt% based on the total weight of the total of components a) and b).

7. Composition according to any one of claims 1-5, wherein the composition of the invention comprises polyamide but no polyoxymethylene and the amount of polyamide is from about 0.01 to 5wt% based on the total weight of the total of components a) and b).

8. Composition according to any one of claims 1-7, wherein the crystallization temperature of the composition is at least 120 °C.

9. Use of the composition of any one of claims 1-8 in injection molding, preferably in thin wall injection molding.

10. Article comprising the composition of any one of claims 1-8, wherein the article is prepared by injection molding, preferably by thin wall injection molding.

1 1. Process comprising the step of injecting the composition of any one of claims 1-8 in a mold.

12. Process comprising the step of injecting the composition of any one of claims 1-8 in a thin wall mold, wherein a thin wall mold is a mold providing a space having a wall thickness in the range from 0.5 to 2 mm.

13. Process for the preparation of the composition of any one of claims 1-8 comprising the step of

- melt-mixing the the polymer having TcP which is 5-40 °C higher than TcPP_with the heterophasic propylene copolymer and optional additives.

14. Use of a polymer (b) preferably chosen from the group consisting of

polyoxymethylene, polyamide and mixtures thereof for increasing heat distortion temperature, stress at yield, stress at break, elastic modulus, flexural strength, flexural modulus, degree of crystallinity, crystallization temperature and/or impact strength of a composition comprising

(a) a heterophasic propylene copolymer consisting of

(i) a propylene-based matrix,

(ii) a dispersed ethylene-a-olefin copolymer,

wherein the heterophasic polypropylene copolymer (a) has a melt temperature TmPP and a crystallization temperature TcPP,

wherein the T_m and T_c and the degree of crystallinity are determined using Differential Scanning Calorimetry according to ASTM D 3418-08 using a scan rate of 10°C/min on a sample of 10mg and using the second heating cycle, wherein the heat distortion temperature is measured according to ASTM D-648, the stress at yield is measured according to ASTM D-638,

the stress at break is measured according to ASTM D-638,

the elastic modulus is measured according to ASTM D-638,

the flexural strength is measured according to ASTM D-790A,

the flexural modulus is measured according to ASTM D-790A and

the impact strength is measured according to ASTM D-256 at 23 °C.