WO2017215914A1 - Composition comprising heterophasic propylene copolymer - Google Patents

Abstract

The invention relates to acomposition comprising (A) a heterophasic propylene copolymer and (B) anorganic salt of alkali metal and/or an organic salt of alkaline earth metal, wherein the heterophasic propylene copolymer consists of (a) 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 (b) a dispersed ethylene-α-olefin copolymer, wherein the dispersed ethylene-α-olefin copolymer is present in an amount of 40 to wt% based on the total heterophasic propylene copolymer and 1 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%, wherein the amount of (B) in the composition is 40 to 500 ppm based on the total weight of the composition. 20

Description

COMPOSITION COMPRISING HETEROPHASIC PROPYLENE COPOLYMER

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

Heterophasic propylene copolymer, 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.

In general, the impact strength of the heterophasic propylene composition can be increased by use of a higher amount of the dispersed phase in the heterophasic propylene copolymer. However, an increase of the amount of the dispersed phase may lead to decrease in other properties.

It is an object of the invention to provide a heterophasic polypropylene composition having a high impact strength while maintaining desired levels of other properties.

This object is achieved by a composition comprising (A) a heterophasic propylene copolymer and

(B) an organic salt of alkali metal and/or an organic salt of alkaline earth metal, wherein the heterophasic propylene copolymer consists of

(a) 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 oolefin, 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

(b) 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%, wherein the amount of (B) in the composition is 40 to 500 ppm based on the total weight of the composition.

According to the present invention, it has surprisingly been found that an organic salt of alkali metal or alkaline earth metal in a very low amount significantly increases the impact strength. Properties such as flexural strength, flexural modulus and Young's modulus are substantially maintained. The incorporation of this salt does not require any additional operations as this can be added along with other additives which are typically added such as antioxidants, thermal stabilizers and acid scavengers.

The incorporation of this salt shows a significant increase in the impact strength, surprisingly already at a very low ppm level in the composition. There is a trend towards use of less additives to facilitate recycling and to make it easier to comply with increasingly stringent regulations. Therefore, it is surprising and very advantageous from a sustainability, regulatory as well as from a cost and processing perspective that (B) is effective in very little amounts in increasing impact strength, while other properties such as flexural strength, modulus and Young's modulus are maintained.

It is noted that an organic salt of alkali metal or alkaline earth metal is typically used as an anti-drip agent. For example, EP2789653 discloses a flame retardant polyolefin resin composition comprising polypropylene, flame retardants and a fluorine-containing anti-drip agent. As specific examples of the fluorine-containing anti-drip agents, alkali metal perfluoroalkanesulfonate compounds or alkaline earth metal

perfluoroalkanesulfonate compounds such as sodium perfluoromethanesulfonate, potassium perfluoro-n-butanesulfonate, potassium perfluoro-tert-butanesulfonate, sodium perfluorooctane sulfonate, and calcium perfluoro-2-ethylhexanesulfonate are mentioned. EP2789653 mentions that, if the content of the anti-dripping effect is less than 0.01 % by mass, the anti-dripping effect is not sufficient. KR2013022641 discloses a polyolefin resin composition comprises 0.2-5 parts by weight of a surfactant based on 100.0 parts by weight of a mixed composition. The mixed composition consists of 30-96 weight% of a polyolefin resin, 1 -30 weight% of a rubber, and 3-40 weight% of inorganic fillers. The surfactant may be

perfluorobutanesulfonate. Neither the use of an organic salt of alkali metal or alkaline earth metal in a very low amount in a heterophasic propylene copolymer nor its effect of increasing the impact strength is disclosed in EP2789653 and KR2013022641 . (A) 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 a process comprising - polymerizing propylene and optionally oolefin in the presence of a catalyst system to obtain the propylene-based matrix and

- subsequently polymerizing ethylene and oolefin 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-o olefin copolymer may be determined by¹³C-NMR, as well known in the art.

The propylene-based matrix consists of a propylene homopolymer and/or a propylene- oolefin copolymer consisting of at least 70 wt% of propylene and up to 30 wt% of o 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 to 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. When the propylene-based matrix consists of a propylene homopolymer, a higher stiffness is obtained compared to the case where the propylene-based matrix is a propylene-a- olefin copolymer, which may be advantageous. The melt flow index (MFI) of the propylene-based matrix (before the heterophasic propylene copolymer is mixed into the composition of the invention), MFI_PP, 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 IS01 133 (2.16 kg/230°C). The MFI_PP may be in the range of for example 0.1 to 50 dg/min, for example from 0.2 to 40 dg/min, for example 0.3 to 30 dg/min, for example 0.5 to 25 dg/min, for example from 1 to 20 dg/min, for example from 1.5 to 10 dg/min, measured according to IS01 133 (2.16 kg/230°C). The propylene-based matrix is present in an amount of 60 to 95wt%. Preferably, the propylene-based matrix is present in an amount of 60 to 80wt%, for example at least 65 wt% or at least 70 wt% and/or at most 78 wt%, 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-a-olefin copolymer. The dispersed ethylene-a-olefin 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 amount of the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer may herein be sometimes referred as RC.

The amount of ethylene in the ethylene-a-olefin copolymer is 10 to 25 wt%, for example at least 12 wt% or at least 15 wt%, and/or at most 23 wt% or at most 20 wt%, preferably 15 to 20 wt%. Such amount of ethylene in the ethylene-a-olefin copolymer is preferred because it is easy to produce and a higher ethylene amount leads to a better impact. The amount of ethylene in the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer may herein be sometimes referred as RCC2.

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

The MFI of the dispersed ethylene a-olefin copolymer (before the heterophasic propylene copolymer is mixed into the composition of the invention), MFI_EPR, 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 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 3 dg/min. The MFI_EPR may be in the range for example from 0.001 to 30 dg/min, for example from 0.01 to 20 dg/min, for example 0.1 to 15 dg/min, for example 0.3 to 10 dg/min, for example from 0.7 to 5 dg/min, for example from 1 to 3 dg/min. MFI_EPR is calculated taking into account the MFI of the propylene-based matrix (MFI_PP) measured according to IS01 133 (2.16 kg/230 °C), the MFI of the heterophasic propylene copolymer (MFIheterophasic) measured according to IS01 133 (2.16 kg/230 °C) and the amount of the propylene-based matrix in the heterophasic propylene copolymer (matrix content) and the amount of the dispersed phase in the heterophasic propylene copolymer (rubber content (RC)) according to the following formula:

Loq MFIheterophasic— matrix content * Loq MFIPP

MFIEPR = 10^Λ (— )

rubber content

The dispersed ethylene-oolefin copolymer is present in an amount of 40 to 5 wt%. Preferably, the dispersed ethylene-oolefin copolymer is present in an amount of 40 to 20 wt%, for example in an amount of at least 22 wt% and/or for example in an amount of at most 35 wt% or at most 30 wt% based on the total heterophasic propylene copolymer.

In the heterophasic propylene copolymer 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-oolefin copolymer is 100 wt% of the heterophasic propylene copolymer.

For example, the amount of ethylene in the heterophasic propylene copolymer

(sometimes referred as TC2) is in the range of 5 - 20 wt% based on the heterophasic propylene copolymer.

The MFI of the heterophasic propylene copolymer 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 5 dg/min or at least 10 dg/min, and/or for example at most 100 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 or at most 10 dg/min, measured according to IS01 133 (2.16 kg/230°C). The MFI of the heterophasic propylene copolymer may be in the range of for example 0.1 to 50 dg/min, for example from 0.2 to 40 dg/min, for example 0.3 to 30 dg/min, for example 0.5 to 25 dg/min, for example from 1 to 20 dg/min, for example from 1.5 to 10 dg/min, measured according to IS01 133 (2.16 kg/230°C). In some embodiments, the MFI of the heterophasic propylene copolymer may be in the range of 10-100 dg/min, measured according to IS01 133 (2.16 kg/230°C). Such a range of MFI is suitable for injection moulding.

The values of the MFI of the propylene-based matrix (MFI_PP) and the MFI of the dispersed ethylene-oolefin elastomer (MFI_EPR) mentioned herein are understood as the values before the heterophasic propylene copolymer is mixed with component (B) and optional component(s) 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, in the heterophasic propylene copolymer according to the invention, the α-olefin in the propylene- a-olefin copolymer is selected from the group of a-olefins having 2 or 4 to10 carbon atoms and

the α-olefin in the ethylene-a-olefin copolymer is selected from the group of a-olefins having 3 to 8 carbon atoms.

The composition according to the invention also comprises an organic salt of alkali metal and/or an organic salt of alkaline earth metal. The amount of (B) in the composition is 40 to 500 ppm based on the total weight of the composition.

Preferably, the organic salt of alkali metal and/or an organic salt of alkaline earth metal is selected from alkali and alkaline earth metal salts of organic sulfonic acids.

Preferably, the organic salt of alkali metal and/or an organic salt of alkaline earth metal is selected from alkali and/or alkaline earth metal salts of sulfonic acids having a perfluoroalkane group of 1 to 8 carbon atoms. Examples of the sulfonic acids having a perfluoroalkane group of 1 to 8 carbon atoms include perfluoromethane sulfonic acid, perfluoroethane sulfonic acid, perfluoropropane sulfonic acid, perfluorobutane sulfonic acid.

Most preferably, the organic salt of alkali metal and/or an organic salt of alkaline earth metal is potassium perfluorobutane sulfonic acid (also known as Rimar salt). Preferably, the amount of (B) in the composition is at least 40 ppm, more preferably at least 50 ppm, for example 50 to 400 ppm, 50 to 300 ppm, 50 to 200 ppm or 50 to 100 ppm. (C) Optional components

The composition according to the invention may optionally comprise at least one optional component (C). Examples of optional components (C) are peroxides and other additives. The amount of the optional component (C) is typically 0 to 30 wt% of the total of the composition.

Peroxides

In some embodiments, the composition according to the invention can be obtained by melt-mixing a peroxide with components (A) and (B). The composition obtained by the addition of a peroxide has a different (higher) MFI from the MFI of the heterophasic 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 component (A), which changes the melt flow index of the heterophasic propylene copolymer, and then mix with component (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.

Additives

The composition according to the invention may further comprise additives. The additives may include nucleating agents, stabilisers, e.g. heat stabilisers, anti-oxidants, UV stabilizers; colorants, like pigments and dyes; clarifiers; surface tension modifiers; lubricants; flame-retardants; mould-release agents; flow improving agents; plasticizers; anti-static agents; external elastomeric impact modifiers; blowing agents; inorganic fillers such as talc and reinforcing agents; and/or components that enhance interfacial bonding between polymer and filler, such as a maleated polypropylene.

The skilled person can readily select any suitable combination of additives and additive amounts without undue experimentation. The amount of the additives depends on their type and function and typically is of from 0 to about 30 wt%. The amount of the additives may e.g. be from about 1 to about 20 wt%; from about 2 to about 10 wt% or of from 3 to about 5 wt% based on the total composition.

In some preferred embodiments, when additives are present in the composition in addition to (A) and (B), the amount of the additives is at most 20000 ppm, at most 10000 ppm or at most 5000 ppm of the total composition. composition

The sum of all components added in the process of the invention to form the composition comprising (A) the heterophasic propylene copolymer, (B) the organic salt of alkali metal and/or an organic salt of alkaline earth metal and (C) the optional components should add up to 100% by weight of the total composition.

Preferably, the total of components (A) and (B) is at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, at least 97 wt%, at least 98 wt%, at least 99 wt%, at least 99.5 wt%, at least 99.9 wt% or 100 wt% of the total composition.

In some embodiments, the composition according to the invention comprises a glass material such as glass beads or glass fibers as an additional component to components (A) and (B). The amount of the glass material such as the glass beads or glass fibers may e.g. be 5 to 30 wt%, e.g. 10 to 25 wt%, e.g. 15 to 20 wt%. The invention further relates to a composition comprising no or little amount of glass material such as glass beads or glass fibers as an additional component to

components (A) and (B). The amount of glass materials such as the glass beads or glass fibers may e.g. be at most 5 wt%, at most 4 wt%, at most 3 wt%, at most 1 wt%, at most 0.5 wt%, at most 0.1 wt% or 0 wt%.

Process for making composition

The composition of the invention may be obtained by a process comprising melt-mixing (A) the heterophasic copolymer, (B) the organic salt of alkali metal and/or an organic salt of alkaline earth metal and (C) the optional component by using any suitable means. Accordingly, the invention further relates to a process for the preparation of the composition according to the invention comprising melt mixing (A) and (B) and optionally (C). Preferably, the composition of the invention is made in a form that allows easy processing into a shaped article in a subsequent step, like in pellet or granular form. The composition can be a mixture of different particles or pellets; like a blend of the heterophasic propylene copolymer and a masterbatch of additives (e.g. a pre-mix). Preferably, the composition of the invention is in pellet or granular form as obtained by mixing all components in an apparatus like an extruder; the advantage being a composition with homogeneous and well-defined concentrations of the additives.

With melt-mixing is meant that the components (B) and optionally (C) are mixed with the heterophasic propylene copolymer at a temperature that exceeds the melting point of the heterophasic propylene copolymer. Melt-mixing may be done using techniques known to the skilled person, for example in an extruder. Generally, in the process of the invention, melt-mixing is performed at a temperature in the range from 150-300°C.

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 200 to 265°C;; too high temperatures may induce undesired degradation processes, which may for example result in compositions having poor mechanical properties. Likewise, the screw speed of the extruder may be varied as needed. Typical screw speed is in the range from about 10Orpm to about 400rpm. Properties of composition

The MFI of the composition according to the invention may be for example at least 1.0 dg/min, at least 5.0 dg/min, at least 10.0 dg/min, at least 15.0 dg/min, for example at least 20.0 dg/min and/or for example at most 100 dg/min, at most 70dg/min, at most 50 dg/min, measured according to IS01 133 (2.16 kg/230°C). The MFI of the composition according to the invention may for example be in the range of for example 1 .0 to 100 dg/min, for example from 10 to 100dg/min, measured according to IS01 133 (2.16 kg/230°C). The MFI of the composition according to the invention may be in the range of 10-100 dg/min measured according to IS01 133 (2.16 kg/230°C). Such a range of MFI is suitable for injection moulding.

Preferably, the composition according to the invention has an Izod impact strength at 23°C measured by ASTM D256 (test geometry: 65^*12.7^*3.2 mm, notch 45°, radius 0.25 mm, parallel orientation) of at least 70.0 J/m. Preferably, the composition according to the invention has a Flexural Strength according to ASTM D790 of at least 28 MPa.

Preferably, the composition according to the invention has a Flexural Modulus measured by ASTM D638 of at least 1000 MPa.

Preferably, the composition according to the invention has a Young's Modulus measured by ASTM D790 of at least 1250 MPa.

Further aspects

The composition according to the invention may be processed by any conventional technique known in the art into an article. Suitable examples of processing techniques wherein the composition according to the invention may be used include injection moulding, compression moulding, extrusion, sheet extrusion, film extrusion, cast film extrusion, foam extrusion, thermoforming and thin-walled injection moulding.

The invention further provides an article comprising the composition according to the invention. Suitable examples of the article include a consumer appliance such as housings for household appliances, housings for electrical appliances such as refrigerator interiors, washing machine barrels and housings for garden power tools, e.g. lawn mower. The invention further provides a process for the preparation of the article according to the invention, comprising the steps of

- injecting the composition according to the invention into a mold and

- cooling the composition to obtain a formed composition and removing the formed composition from the mold.

The invention further provides use of the composition according to the invention for injection molding.

The invention also relates to the use of (B) an organic salt of alkali metal or alkaline earth metal as an impact modifier for (A) a heterophasic propylene copolymer consisting of

(a) 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 oolefin, 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

(b) 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%. It is 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. Examples

Materials

The heterophasic propylene copolymer used in the examples comprises a matrix phase of a propylene homopolymer and a dispersed phase of propylene-ethylene copolymer and has the following properties:

Table 1

The heterophasic propylene copolymer was mixed with Rimar salt (potassium perfluorobutane sulfonate) in amounts shown in Table 2 and additives which are typically used in propylene compositions such as thermal stabilizers to prevent thermo- oxidative degradation. The compositions were prepared using a co-rotating twin screw extruder [Krauss Maffei co-rotating twin screw extruder, 25 mm screw dia with L/D of 56] to obtain pellets.

All experiments were performed at 200 RPM and a throughput of 30 kg/hour. The temperature zones 1 to 12 were set on: 35°C, 200°C, 200°C, 200°C, 200°C, 200°C, 200°C, 220°C, 220°C, 220°C, 220°C and 220°C. The adaptor temperature, the die temperature and the water tank temperature was 230°C, 240°C and 40°C respectively.

Impact strength was measured by Izod test (notched Izod Impact) according to ASTM D256-10e1. Samples were obtained by injection molding specimens in 65^*12.7^*2 mm dimension in the parallel orientation of moulding with 45° notch, radius 0.25mm. The test temperature was 23 °C.

Flexural strength (FS) was measured by ASTM D790-15e2.

Flexural Modulus (FM) was measured by ASTM D790-15e2.

Young's Modulus (YM) was measured by ASTM D790-15e2.

The test results are shown in Tables 2.

Table 2

As can be understood from Table 2, the Rimer salt leads to a significant increase in the impact strength, surpisingly already at a very low ppm level in the composition. There is a trend towards use of less additives to facilitate recycling and to make it easier to comply with increasingly stringent regulations. Therefore, it is surprising and very advantageous from a sustainability, regulatory as well as from a cost and processing perspective that Rimar salt is effective in very little amounts in increasing impact strength, while other properties such as flexural strength, modulus and Young's modulus are maintained.

Claims

1 . A composition comprising (A) a heterophasic propylene copolymer and (B) an organic salt of alkali metal and/or an organic salt of alkaline earth metal, wherein the heterophasic propylene copolymer consists of

(a) 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 oolefin, 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

(b) 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%,

wherein the amount of (B) in the composition is 40 to 500 ppm based on the total weight of the composition.

2. The composition according to claim 1 , wherein (B) is selected from alkali and alkaline earth metal salts of organic sulfonic acids.

3. The composition according to any one of the preceding claims, wherein (B) is selected from alkali and/or alkaline earth metal salts of sulfonic acids having a perfluoroalkane group of 1 to 8 carbon atoms, such as perfluoromethanesulfonic acid, perfluoroethanesulfonic acid, perfluoropropanesulfonic acid, perfluorobutanesulfonic acid.

4. The composition according to any one of the preceding claims, the amount of (B) in the composition is 50 to 200 ppm based on the total weight of the composition.

5. The composition according to any one of the preceding claims, wherein the propylene-based matrix consists of a propylene homopolymer.

6. The composition according to any one of the preceding claims, wherein the a-olefin in the ethylene-a-olefin copolymer is chosen from the group of a-olefins having 3 to 8 carbon atoms and any mixtures thereof and is preferably propylene.

7. The composition according to any one of the preceding claims, wherein the composition has a melt flow index as determined according to IS01 133 at 230 °C and 2.16 kg in the range of 10 to 100 dg/min.

8. The composition according to any one of the preceding claims, wherein when additives are present in the composition in addition to (A) and (B), the amount of the additives is at most 20000 ppm, preferably at most 10000 ppm and more preferably at most 5000 ppm of the total composition.

9. The composition according to any one of the preceding claims, wherein the composition has an Izod impact strength at 23°C measured by ASTM D256 of at least 70.0 J/m, with a test geometry of 65^*12.7^*3.2 mm, notch 45°, radius 0.25 mm, parallel orientation.

10. A process for the preparation of the composition according to any one of the preceding claims, comprising melt mixing (A) and (B).

1 1 . An article comprising the composition of any one of claims 1 -8.

12. The article according to claim 10, wherein the article is a consumer appliance such as housings for household appliances, housings for electrical appliances such as refrigerator interiors, washing machine barrels and housings for garden power tools, e.g. lawn mower.

13. A process for the preparation of the article according to claim 1 1 or 12, comprising the steps of

- injecting the composition of any one of claims 1 -9 into a mold and

- cooling the composition to obtain a formed composition and removing the formed composition from the mold.

14. Use of the composition of any one of claims 1 -9 for injection molding.

15. Use of (B) an organic salt of alkali metal or alkaline earth metal as an impact modifier for (A) a heterophasic propylene copolymer consisting of (a) 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 oolefin, 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

(b) 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%.