Polypropylene composition

Abstract

The present invention relates to a polypropylene composition, a method for preparing the same, and an article comprising such a polypropylene composition. The polypropylene composition, relative to the total weight thereof, comprises (A) 30 to 60 wt% of a propylene-based polymer, which is a propylene homopolymer or a propylene copolymer with at most 10 wt% of comonomer units, (B) 30 to 60 wt% of a heterophasic polypropylene, (C) 7 to 11 wt% of a talc, and (D) 0.01 to 1 wt% of a nucleating agent.

Description

[0001] POLYPROPYLENE COMPOSITION

[0002] The present invention relates to a polypropylene composition, a method for preparing the same, and an article comprising such a polypropylene composition.

[0003] In cosmetic applications, the most widely used material is acrylonitrile-butadiene- styrene block copolymer (ABS) due to its high gloss, modulus, and hardness, also the good electroplating performance, good coloring performance and processing convenience. However, ABS is nowadays regarded as a non-sustainable material due to the presence of the styrene blocks. There exists an urgent need in the field to find an alternative material of ABS while having comparable performances.

[0004] PP (polypropylene), PET (polyethylene terephthalate) and PBT (polybutylene terephthalate) are potential alternatives of ABS.

[0005] PP is widely used in various applications including packaging due to its balance of impact and stiffness, heat and chemical resistance, and close dimensional tolerance, also due to its advantages in low weight & cost. However, PP material shows shortage in aspects relating to aesthetic, like modulus, gloss, and electroplating. Adding mineral fillers or additives can improve the modulus but the concern is that mineral fillers or additives can cause the increase of overall density of the compound, and also decrease of gloss. Normally it is required not to exceed 0.975 g / cm3for PP based material with an acceptable recyclability.

[0006] Many attempts have been made in the PP filed generally to improve various properties of a PP composition, but a PP composition meeting the requirements for cosmetic applications has not been disclosed. Such earlier publications on PP compositions include:

[0007] WO2017 / 144475A1 discloses a composition comprising a heterophasic propylene copolymer, a slip agent (erucamide) and a nucleating agent HPN-20E and talc.

[0008] W02020169402A1 discloses a composition comprising a heterophasic propylene copolymer, a polyethylene elastomer, a cyclic dicarboxylate salt compound as a first nucleating agent, and less than 5 wt% of talc as a second nucleating agent.

[0009] WO2014191211A1 discloses a composition comprising 20-60 wt% of a heterophasic propylene copolymer, 5-70 wt% of a polypropylene homopolymer, and 20-40 wt% of a mineral filler. The purpose of the present invention is therefore to provide a PP composition with potential application in the cosmetic filed, preferably with a good tactile sensation. The present invention is realized by compounding two PP components, one being a PP based polymer, such as a homo PP, and the other being a heterophasic PP, with a suitable amount of talc. The thus formulated composition is found to show high modulus, moderate gloss, and low shrinkage, meeting the requirements for cosmetic applications.

[0010] In a preferred embodiment, the composition of the present invention also shows good electroplating performance which is very important for cosmetic applications. In addition, the composition of the present invention can be potentially used for food contact applications and easily recycled after usage.

[0011] In one aspect, the present invention provides a polypropylene composition comprising:

[0012] (A) 30 to 60 wt% of a propylene-based polymer, which is a propylene homopolymer or a propylene copolymer with at most 10 wt% of comonomer units,

[0013] (B) 30 to 60 wt% of a heterophasic polypropylene,

[0014] (C) 7 to 11 wt% of a talc, and

[0015] (D) 0.01 to 1 wt% of a nucleating agent which comprises a bicyclic dicarboxylate metal salt of formula I:

[0016] Formula I in which, Mi and M2are independently, or combined as one cation, selected from metal cations of sodium, calcium, strontium, lithium, zinc, magnesium, and monobasic aluminum; and

[0017] Ri, R2, R3, R4, R5, Re, R7, Rs, R9, and R10 are independently selected from the group consisting of hydrogen and C1-C9 alkyls.

[0018] In another aspect, the present invention provides a process for the preparation of the composition of the present invention, comprising: melt mixing the components (A), (B), (C), (D) and optional (E), to produce the composition, preferably followed by pelletizing the composition.

[0019] In a further aspect, the present invention provides an article comprising the composition of the present invention.

[0020] The composition according to the invention comprises a propylene-based polymer (A).

[0021] The propylene-based polymer may be a propylene homopolymer or a propylene copolymer with at most 10 wt% of comonomer units, such as 8 wt%, 6 wt%, 5wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, or 0.1 wt%. The comonomer units may be ethylene monomer units and / or an a-olefin monomer units having 4 to 10 carbon atoms.

[0022] In an embodiment, the propylene-based polymer (A) is a random propylene-ethylene copolymer consisting of 90 to 99 wt% of propylene monomer units and 1 to 10 wt% of ethylene monomer units. Preferably, the propylene-based polymer (A) is a random propylene-ethylene copolymer consisting of 96 to 99 wt% of propylene monomer units and 1 to 4 wt% of ethylene monomer units. A random copolymer with a low comonomer content retains a good stiffness and leads to a good mechanical property balance.

[0023] In one embodiment, the propylene-based polymer (A) has a density of 0.870-0.950 g / cm3, for example 0.900-0.910 g / cm3, measured in accordance with ISO 1183.

[0024] In one embodiment, the propylene-based polymer (A) has a melt flow rate of 1 to 69 dg / min, preferably 5 to 60 dg / min, more preferably 10 to 50 dg / min, even more preferably 20 to 40 dg / min, such as about 30 dg / min, measured in accordance with ISO 1133 using a 2.16 kg weight and at a temperature of 230 °C.

[0025] In one embodiment, the amount of the propylene-based polymer (A) in the composition is 30 to 60 wt%, for example 35 to 50 wt% or about 40 wt%, with respect to the total composition.

[0026] It will be appreciated that the propylene-based polymer (A), which is a propylene homopolymer or a random propylene copolymer with at most 10 wt% of comonomer units, is not a heterophasic propylene copolymer In the context of the present invention, the polypropylene composition may also comprise two or more polypropylenes (A), each of which and / or a combination of which meets the definitions above.

[0027] The composition according to the invention comprises a heterophasic polypropylene

[0028] (B).

[0029] Heterophasic polypropylenes, or 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 an ethylene-a-olefin mixture. The resulting polymeric materials are heterophasic, but the specific morphology usually depends on the preparation method and monomer ratios used.

[0030] The heterophasic propylene copolymers employed in the 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

[0031] W006 / 010414; Polypropylene and other Polyolefins, by Ser van der en, Studies in

[0032] Polymer Science 7, Elsevier 1990; W006 / 010414; US4399054 and US4472524.

[0033] Preferably, the heterophasic propylene copolymer is made using Ziegler-Natta catalyst.

[0034] The heterophasic propylene copolymer may be prepared by a process comprising

[0035] - polymerizing propylene and optionally ethylene and / or a-olefin in the presence of a catalyst system to obtain the propylene-based matrix and

[0036] - 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.

[0037] 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.

[0038] The heterophasic propylene copolymer of the composition of the invention comprises a propylene-based matrix and a dispersed ethylene-a-olefin 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 by13C-NMR, as well known in the art. The propylene-based matrix consists of a propylene homopolymer and / or a propylene copolymer consisting of at least 90 wt% of propylene monomer units and at most 10 wt% of comonomer units selected from ethylene monomer units and a-olefin monomer units having 4 to 10 carbon atoms, for example consisting of at least 95 wt% of propylene monomer units and at most 5 wt% of the comonomer units, based on the total weight of the propylene-based matrix.

[0039] Preferably, the comonomer in the propylene copolymer of the propylene-based matrix is selected from the group of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1- hexene, 1 -heptene and 1 -octene, and is preferably ethylene.

[0040] Preferably, the propylene-based matrix consists of a propylene homopolymer. The fact that the propylene-based matrix consists of a propylene homopolymer is advantageous in that a higher stiffness is obtained compared to the case where the propylene-based matrix is a propylene-a-olefin copolymer.

[0041] The melt flow index (MFI) of the propylene-based matrix (before the heterophasic propylene copolymer 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, and / or for example 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, measured according to IS01133-1 :2011 (2.16 kg / 230°C).

[0042] Preferably, the propylene-based matrix is present in an amount of 60 to 98 wt%, for example at most 97 wt%, at most 96 wt%, at most 95 wt%, at most 93 wt% or at most 91 wt%, based on the total heterophasic propylene copolymer. Preferably, the propylene-based matrix is present in an amount of at least 70 wt%, more preferably at least 75 wt%, for example at least 80 wt%, at least 85 wt%, at least 87 wt% or at least 90 wt%, based on the total heterophasic propylene copolymer.

[0043] 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 ISO11357-1 and ISO11357- 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.

[0044] Preferably, the amount of ethylene monomer units in the ethylene-a-olefin copolymer is 10 to 60 wt%, preferably 20 to 40 wt%, more preferably 25 to 35 wt% or about 30 wt%. The amount of ethylene monomer units in the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer may herein be sometimes referred as RCC2.

[0045] 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 -hexene, 1 -heptene and 1 -octene. More 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 mixture thereof. More preferably, the a-olefin is propylene, in which case the ethylene-a-olefin copolymer is ethylene-propylene copolymer.

[0046] The MFI of the dispersed ethylene a-olefin copolymer (before the heterophasic propylene copolymer is mixed into the composition of the invention), MFIrUbber, may be for example at least 0.001 dg / min, at least 0.03 dg / min or at least 0.05 dg / min, and / or for example at most 0.1 dg / min or 0.01 dg / min. MFI rubber is calculated according to the following formula: wherein M FIheterophasic is the MFI (dg / min) of the heterophasic propylene copolymer measured according to ISO1133-1 :2011 (2.16kg / 230°C), MFImatrix is the MFI (dg / min) of the propylene-based matrix measured according to ISO1133-1 :2011 (2.16kg / 230°C), matrix content is the fraction of the propylene-based matrix in the heterophasic propylene copolymer, rubber content is the fraction of the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer. The sum of the matrix content and the rubber content is 1 . For the avoidance of any doubt, Log in the formula means log-io. Preferably, the dispersed ethylene-a-olefin copolymer is present in an amount of 2.0 to 40 wt%, for example at least 3.0 wt%, at least 4.0 wt%, at least 5.0 wt%, at least 7.0 wt% or at least 9.0 wt%, based on the total heterophasic propylene copolymer. Preferably, the dispersed ethylene-a-olefin copolymer is present in an amount of at most 20 wt%, more preferably at most 15 wt%, for example at most 13 wt%, at most 11 wt%, or at most 10 wt%, based on the total heterophasic propylene copolymer. This leads to good mechanical properties of the composition according to the invention such as impact strength.

[0047] 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-a-olefin copolymer may be at least 95 wt%, at least 97 wt%, at least 99 wt% or 100 wt% of the heterophasic propylene copolymer.

[0048] Preferably, the heterophasic propylene copolymer has a fraction soluble in p-xylene at 25°C (CXS) measured according to ISO 16152:2005 of 2.0 to 40 wt%, for example 9.0 to 25 wt%.

[0049] Preferably, the amount of ethylene monomer units in the heterophasic propylene copolymer (sometimes referred as TC2) is in the range of 1.0 to 20 wt%, for example 5.0 to 15 wt%, based on the heterophasic propylene copolymer.

[0050] Preferably, the MFI of the heterophasic propylene copolymer is 10 to 60 dg / min, preferably 20 to 50 dg / min, more preferably 25 to 40 dg / min, such as about 30 dg / min, measured in accordance with ISO 1133 using a 2.16 kg weight and at a temperature of 230 °C

[0051] In one embodiment, the amount of the heterophasic polypropylene (B) in the composition is 30 to 60 wt%, for example 35 to 50 wt% or about 40 wt%, with respect to the total composition.

[0052] In the context of the present invention, the polypropylene composition may also comprise two or more heterophasic polypropylenes (B), each of which and / or a combination of which meets the definitions above.

[0053] In one embodiment, the weight ratio between the propylene-based polymer (A) and the heterophasic polypropylene (B) is from 1 :2 to 2:1 , for example 0.6:1 , 0.7:1 , 0.8:1 , 0.9:1 , 1 :1 , 1.1 :1 , 1.2:1 , 1.3:1 , 1.4:1 , 1.5:1 , 1.6:1 , 1.7:1 , 1.8:1 , or 1.9:1.

[0054] In one embodiment, a sum of the propylene-based polymer (A) and the heterophasic polypropylene (B) is at least 70 wt%, with respect to the total composition, preferably at least 80 wt%, more preferably at least 85 wt%, even more preferably at least 90 wt%. (C) Talc

[0055] The composition according to the invention comprises a filler, which is a talc.

[0056] Other than the talc (C), the composition does not comprise other fillers selected from the group consisting of chalk, clay, mica, montmorillonite, silica, glass fibers and carbon fibers.

[0057] In one embodiment, the talc (C) has a median diameter D50 of at most 9pm, preferably between 0.1 to 6 pm, such as 1 to 3 pm. D50 is the mean (or median) particle size, i.e. the particle diameter where 50% of the particles are larger and 50% are smaller. This value can be measured according to sedimentation analysis, Stockes’ law in accordance with ISO 13317-3:2001.

[0058] In one embodiment, the amount of the talc (C) in the composition is 7-11 wt%, for example 8 wt%, 9 wt%, or 10wt%, based on the total composition.

[0059] In one embodiment, the Talc (C) is in compliance to the Swiss Ordinance of the FDHA of “materials and articles intended to come into contact with food-stuffs” (817.023.21 and SR 817.02). Based on the standard testing methods, the talc products are below the detectable limits for asbestos. A fully equipped laboratory determines the absence of detectable asbestos according to ISO 14966-2002. Instrumentation used for analysis includes:

[0060] - X-ray diffractometer for powders (LoD = 1000 ppm)

[0061] - Scanning electron microscopy and Energy dispersive spectrometry (LoD = 100 ppm)

[0062] (D) nucleating agent

[0063] The composition according to the invention further comprises a nucleating agent.

[0064] The 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).

[0065] In one embodiment, the amount of the nucleating agent (D) in the composition is 0.01 to 1 wt%, preferably 0.05 to 0.5 wt%, such as WOOppm, 1500ppm, 2000ppm, 2500 ppm, 3000ppm, 3500ppm, 4000ppm, or 4500ppm. For clarity, 0.5wt% equals to 5000ppm. Suitable examples of the nucleating agent include 2,6-naphthalene dicarboxamides, aliphatic mono- and di- carboxylate salts such as calcium pimelate and calcium suberate; and polyvinylcyclohexane.

[0066] 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- 11 (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 4,463,113.

[0067] 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:

[0068] Formula I wherein Mi and M2are independently selected from the group consisting of metal cations of sodium, calcium, strontium, lithium, zinc, magnesium, and monobasic aluminum; or Mi and M2are combined as one cation selected from the group consisting of metal cations of sodium, calcium, strontium, lithium, zinc, magnesium, and monobasic aluminum; wherein Ri, R2, R3, R4, R5, Re, R7, Rs, R9, and R10 are independently selected from the group consisting of: hydrogen and C1-C9 alkyls, preferably C1-C4 alkyls, more preferably C1-C3 alkyls; and further wherein any two adjacently positioned R3-R10 alkyl groups optionally may be combined to form a carbocyclic ring.

[0069] For the purpose of the present invention, the nucleating agent comprises the bicyclic dicarboxylate metal salt of formula I as defined above.

[0070] 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 particular example may be 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:

[0071] Metal salts of hexahydrophthalic acid (HHPA) are known to the person skilled in the art.

[0072] Such compounds may be as shown:

[0073] Formula II wherein Mi and M2are independently selected from the group consisting of metal cations of calcium, strontium, lithium, and monobasic aluminum; or Mi and M2are combined as one cation selected from the group consisting of metal cations of calcium, strontium, lithium, and monobasic aluminum; and wherein Ri, R2, R3, R4, R5, Re, R7, Rs, R9, and R10 are either the same or different and are individually selected from the group consisting of hydrogen, Ci- C9alkyl, hydroxy, C1-C9 alkoxy, C1-C9 alkyleneoxy, amine, and C1-C9 alkylamine, halogens, and phenyl.

[0074] In one preferred embodiment, the Mi and M2are combined as a calcium ion.

[0075] One particular example may be HYPERFORM(R) HPN-20E from Milliken & Company of Spartanburg, South Carolina. HPN-20E is commercially sold, and comprises calcium cis-hexahydrophthalate, as shown below:

[0076] Di-acetal derivatives, which may be used as a nucleating agent include, but are not limited to, alditol acetals, such as the sorbitol di-acetals described in U.S. Patent No.

[0077] 5,049,605. Suitable di-acetal derivatives preferably conform to the formula below:

[0078] Formula III

[0079] In this formula, 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, Rs, 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 R1, R2, R3, R4, Re, Re, R7, Rs, 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.

[0080] 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. In particular, the composition according to the invention may comprise a nucleating composition comprising a first nucleating agent, which comprises disodium bicyclo [2.2.1] heptane-2,3- dicarboxylate; and a second nucleating agent, which comprises calcium cis-hexahydrophthalate. In a specific embodiment, the nucleating composition comprises HPN-68L and HPN-20E.

[0081] In one embodiment, the amount of the first and the second nucleating agent respectively is in the range of 500 to 2500 ppm, preferably WOOppm to 2000ppm, such as 1500ppm.

[0082] In one embodiment, the ratio between the amount of the first nucleating agent and that of the second nucleating agent is in the range of 1 :5 to 5: 1 , preferably 1 :4 to 4: 1 , for example, 1:3 to 3:1, 1 :2 to 2:1 , or about 1 :1.

[0083] In one embodiment, a sum of the propylene-based polymer (A), the heterophasic polypropylene (B), the talc (C) and the nucleating agent (D) is at least 90 wt%, preferably at least 95 wt%, more preferably at least 99 wt%, even more preferably at least 99.5 wt%.

[0084] (E) Additives

[0085] The composition according to the invention may optionally comprise further additives which are different from the components (A)-(D). The additives may include stabilizers, e.g. heat stabilizers, 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; blowing agents and components that enhance interfacial bonding between polymer and filler.

[0086] 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 5 wt%. The amount of the additives may e.g. be from about 0.01 to about 3 wt%; from about 0.1 to about 2 wt% or from 0.3 to about 1 wt% based on the total composition.

[0087] The sum of all components added in the process of the invention to form the composition comprising (A), (B), (C), (D) and (E) should add up to 100% by weight.

[0088] The composition of the invention does not comprise an ethylene copolymer of ethylene and an a-olefin comonomer having 4 to 10 carbon atoms, which is also termed as an ethylene elastomer. The ethylene elastomer is different from the dispersed phase, i.e., the dispersed ethylene-a-olefin copolymer, in the heterophasic polypropylene (B).

[0089] The a-olefin comonomer in the ethylene copolymer preferably has 4 to 8 carbon atoms and is preferably an acyclic monoolefin such as 1-butene, 1-pentene, 1-hexene, 1- octene, or 4-methyl-1-pentene.

[0090] The ethylene copolymer is preferably selected from the group consisting of ethylene-1- butene copolymer, ethylene- 1-hexene copolymer, ethylene- 1 -octene copolymer and mixtures thereof. Most preferably, the ethylene copolymer is an ethylene- 1 -octene copolymer.

[0091] The ethylene copolymers are commercially available for example under the trademark ENGAGE™ 8402, ENGAGE™ 8407 and SABIC ® FORTIFY™ C30070D.

[0092] The MFI of the composition according to the invention may be for example at least 8 dg / min, at least 10 dg / min, at least 15 dg / min, at least 20 dg / min, or at least 25 dg / min and / or for example at most 100 dg / min, at most 50 dg / min, or at most 40 dg / min, measured according to ISO1133-1 :2011 (2.16 kg / 230°C). Such a range of MFI is suitable for injection moulding.

[0093] The composition according to the invention has a density less than 0.975 g / cm3, for example, in the range of 0.960 to 0.970 g / cm3, as measured in accordance with ISO 1183.

[0094] The composition according to the invention has a tensile modulus obtained via a tensile test carried out at room temperature (23 °C) according to ISO 527 / 1A using specimen with size 80*10*4*170mm of at least 2000MPa, preferably at least 2100 MPa, more preferably at least 2200 MPa.

[0095] The composition according to the invention has a tensile strength obtained via a tensile test carried out at room temperature (23 °C) according to ISO 527 / 1A using specimen with size 80*10*4*170mm of at least 26MPa, preferably at least 27 MPa, more preferably at least 28 MPa.

[0096] The composition according to the invention has an Elongation at break obtained via a tensile test carried out at room temperature (23 °C) according to ISO 527 / 1 A using specimen with size 80*10*4*170mm of at least 10%, preferably at least 15%, more preferably at least 20%. The composition according to the invention has an acceptable gloss. Gloss is the amount of light reflected in a certain direction by a surface of a sample made from the composition. The measurement scale of gloss, Gloss Units (GU), of a glossmeter (BYK Gardner micro-TRI-gloss) is a scaling based on a highly polished reference black glass standard with a defined refractive index having a specular reflectance of 100GU at the specified angle. This standard is used to establish an upper point calibration of 100 with the lower end point established at 0 on a perfectly matte surface. The samples used for this test may be obtained by injection moulding ISO 37 / 2 on the machine Arburg 60T, mould: 1-1-1-108, with geometry 65*65*3.2mm. Preferably, the composition according to the invention has a gloss as determined according to ISO 2813 and DIN67530 at a measurement angle of 20° of at least 18 GU; at a measurement angle of 60° of at least 35 GU; and at a measurement angle of 80° of at least 89 GU.

[0097] The composition according to the invention has a Charpy impact strength tested at room temperature (23 °C) according to ISO 179 / 1eA using specimen with size 80*10*4mm of at least 2.5 kJ / m2, preferably at least 3.0 kJ / m2.

[0098] The composition according to the invention has a flexural modulus at 23 °C according to ISO178 / 1A using specimen with size 80*10*4mm of at least 2000 MPa, preferably at least 2050 MPa, more preferably at least 2100 MPa.

[0099] The composition according to the invention has a shrinkage at the parallel direction or the perpendicular direction tested at room temperature (23 °C) using specimen with size 65*65*3.2 mm of between 1-1 .4 respectively.

[0100] Process

[0101] The composition of the invention may be obtained by a process comprising melt-mixing all the necessary components (A), (B), (C) and (D), as well as the optional component (E) 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 components (A) to (D) and optional (E).

[0102] The melt-mixing of the components may be done in any order. For example, (A) and (C), (D) and / or (E) may be melt-mixed before melt-mixing with (B). A composition of (A) and (C), (D) and / or (E) for example in the form of a pellet may first be obtained and then be melt-mixed with (B). Alternatively, components (A) and (B) are melt-mixed followed by the addition of (C), (D) and optional (E), or components (A) and (B) and (C), (D) and optional (E) are melt-mixed at the same time. 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 copolymer and a masterbatch of additives. 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.

[0103] With melt-mixing is meant that (A) and (B) are melt-mixed with other components at a temperature that exceeds the melting points of (A) and (B). 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 of 200 to 260°C.

[0104] 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.

[0105] Further aspects

[0106] The composition according to the invention may then 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, injection stretch blow moulding, compression moulding, extrusion and extrusion compression moulding, sheet extrusion, thermoforming or thin-walled injection moulding.

[0107] The invention further relates to an article comprising the composition according to the invention. In particular, the invention relates to an article comprising the composition according to the invention, wherein the article is made by one of the processing techniques mentioned above.

[0108] Preferably, the article according to the invention is used in cosmetic applications, for example in contact with cosmetics or used as cosmetic containers, or is used in food contact applications, for example in contact with food or used as food containers.

[0109] In one embodiment, the article is an automotive part, in particular an automotive interior part such as instrument panels, cap and closure. Alternatively, the article according to the invention is a home appliance.

[0110] 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.

[0111] 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.

[0112] When values are mentioned for a lower limit and an upper limit for a parameter, ranges made by the combinations of the values of the lower limit and the values of the upper limit are also understood to be disclosed.

[0113] The invention is now elucidated by way of the following examples, without however being limited thereto.

[0114] Experiments

[0115] Components used in the experiments are summarized in Table 1.

[0116] Table 1. Components

[0117] Polypropylene compositions were obtained by compounding in a twin-screw extruder. The polymers, and additives were premixed together and then dosed into the twin- screw extruder through main feeder. The talc fillers were dosed into the twin-screw extruder through the side feeder at zone5. The twin-screw extruder used was ZSK26mc with L / D 40 and screw diameter 26mm. Melting temperature was 220°C. Screw speed was 350rpm and output was 20kg / hr. The extruded strips were water cooled and then chopped into pellets.

[0118] The properties of the compositions were measured as summarized in Table 2. In all tables, “%” means “wt%”, unless indicated otherwise.

[0119] MFR was measured according to ISO 1133-1 :2011 using a 2.16 kg weight and at a temperature of 230 °C.

[0120] For other tests, the pellets were dried at 80°C for 2hrs and then injection moulded into required bars or plaques.

[0121] Density was obtained via part density test according to ISO 1183 using specimen with size 80*10*4mm.

[0122] Flexural modulus and flexural strength at yield were obtained via 3-point flexural test carried out at room temperature according to ISO178 / 1A using specimen with size 80*10*4mm.

[0123] Impact resistance was obtained in Charpy impact test performed at room temperature (23 °C) according to ISO 179 / 1eA using specimen with size 80*10*4mm.

[0124] Thermal distortion temperature (HDT) at 0.45 MPa was carried out according to ISO75 using specimen with size 80*10*4mm.

[0125] Tensile modulus, tensile strength at yield and elongation at break were obtained via tensile test carried out at room temperature (23 °C) according to ISO 527 / 1 A using specimen with size 80*10*4*170mm.

[0126] Gloss was tested according to ASTM D2457 with measurement angle 20°, 60° and 80° using plaque sample with size 60*60*2mm.

[0127] Electroplating was conducted on the plaque samples and then adhesion tests (including cross-cut, environmental and boiling tests) were conducted.

[0128] For the cross-cut test, 1*1 mm grids on the electroplating surface of the sample were drawn, and a 3M616 adhesive paper was used to scratch the grids and quickly pulled up at 45 to 90 degrees. If the coating did not fall off, the sample was considered passing the test.

[0129] For the environmental test, samples were conditioned at 0°C for 8 hours and then at 54°C for 8 hours, with a 95% humidity, for 2 cycles. If after the test, the sample remained its normal function and there was no damage, whitening, crack, foaming and other adverse phenomena seen, it was considered passing the test.

[0130] For the boiling test, the electroplated samples were immersed into water at 80°C for 30 minutes. If after the test, the sample remained its normal function and there was no coloring, whitening, foaming, spot and other adverse phenomena seen, it was considered passing the test.

[0131] Shrinkage 3-D was tested on injection moulded plaque samples with the size of 65*65*3.2mm. Both shrinkage rates on parallel direction and on perpendicular direction were calculated after conditioning the samples at 23°C for 24 hrs. 5 samples for each composition were used to obtain average shrinkage values.

[0132] Table 2. Compositions and properties.

[0133] As can be seen from the examples, a PP composition meeting the needs for cosmetic applications, in particular with regard to a density below 0.975 g / cm3, a tensile modulus above 2000 MPa, a flexural modulus above 2000 MPa and passing the tests after electroplating, can be obtained on basis of a mixture of a PP homopolymer and a PP impact copolymer with a suitable weight ratio and in combination with a suitable amount of talc.

[0134] In particular, when the talc content reached 14wt% in comparative example 10, the density of the composition was close to 1g / cm3, which was not acceptable for cosmetic applications. In comparative example 9, when the talc content was reduced to 6.5wt%, although the density was low enough to be acceptable, the modulus was not good enough as desired.

[0135] The performance of the composition is highly influenced by the proportion of the PP homopolymer and the PP impact copolymer. When the base polymer was PP homopolymer alone, although the modulus, strength and gloss were comparable to ABS, the electroplating performance as evidenced by the environmental, cross-cut and boiling tests were poor with weak adhesion strength, which strongly affected the applications since most cosmetic parts needed electroplating.

[0136] With the incorporation of the PP impact copolymer, the electroplating performance was unexpectedly improved. Without being bound by theory, the inventors believe that it is because of the dispersed phase in the impact copolymer, which is basically an internal rubber phase and is easier to be etched thus creating anchor holes or easier to be polarized during flame treatment. What’s more, the shrinkage of material was also decreased with the addition of the impact copolymer. However, it was discovered that, when the impact copolymer exceeded 60%, the produced cosmetic parts were too soft and lost its tactile sensation, therefore, for the purpose of the present invention, both the contents of the PP homopolymer and the PP impact copolymer are within the range of 30% to 60%.

[0137] A unique combination of two nucleators, HPN-20E and HPN-68L, was also discovered to bring about an unexpected effect of enhancing stiffness of the composition, which is very important to produce cosmetic parts with higher tactile sensation. In comparative example 6, when no nucleator was used, the modulus was too low and the shrinkage was undesirably high. In comparative example 7, when only 0.15% HPN-20E was used, the modulus was increased but the shrinkage was above threshold, and too high a shrinkage may influence the cross-cut test performance. In example 8, when only 0.15% HPN-68L was used, the shrinkage was acceptable but the modulus was obviously inferior in comparison with the inventive example 3 which has the same base polymer composition, however, both the tensile modulus and the flexural modulus are still above the threshold of 2000 Mpa, meeting the needs for objective cosmetic applications.

Claims

CLAIMS1 . A polypropylene composition, relative to the total weight thereof, comprising:(A) 30 to 60 wt% of a propylene-based polymer, which is a propylene homopolymer or a propylene copolymer with at most 10 wt% of comonomer units,(B) 30 to 60 wt% of a heterophasic polypropylene,(C) 7 to 11 wt% of a talc, and(D) 0.01 to 1 wt% of a nucleating agent which comprises a bicyclic dicarboxylate metal salt of formula I:Formula I in which, Mi and M2are independently, or combined as one cation, selected from metal cations of sodium, calcium, strontium, lithium, zinc, magnesium, and monobasic aluminum; andRi, R2, R3, R4, R5, Re, R7, Rs, R9, and R10 are independently selected from the group consisting of hydrogen and C1-C9 alkyls.

2. The composition according to claim 1 , wherein the weight ratio between the propylene-based polymer (A) and the heterophasic polypropylene (B) is from 1 :2 to 2:1 .

3. The composition according to any of the preceding claims, wherein a sum of the propylene-based polymer (A) and the heterophasic polypropylene (B) is at least 70 wt%, preferably at least 80 wt%, more preferably at least 85 wt%, even more preferably at least 90 wt%.

4. The composition according to any of the preceding claims, wherein the propylene-based polymer (A) has a melt flow rate of 1 to 69 dg / min, preferably 5 to 60 dg / min, more preferably 10 to 50 dg / min, even more preferably 20 to 40 dg / min, measured in accordance with ISO 1133 using a 2.16 kg weight and at a temperature of 230 °C.

5. The composition according to any of the preceding claims, wherein the heterophasic polypropylene (B) has a melt flow rate of 10 to 60 dg / min, preferably 20 to 50 dg / min, more preferably 25 to 40 dg / min, measured in accordance with ISO 1133 using a 2.16 kg weight and at a temperature of 230 °C.

6. The composition according to any of the preceding claims, wherein the talc (C) has a median diameter D50 of at most 9pm, preferably between 0.1 to 6 pm, as measured according to sedimentation analysis, Stockes’ law in accordance with ISO 13317-3:2001.

7. The composition according to any of the preceding claims, wherein the nucleating agent (D) further comprises a hexahydro phthalic acid metal salt of formula II:Formula II in which, Mi and M2are independently, or combined as one cation, selected from metal cations of calcium, strontium, lithium, and monobasic aluminum; andRi, R2, R3, R4, R5, Re, R7, Rs, R9, and R10 are individually selected from the group consisting of hydrogen, C1-C9 alkyl, hydroxy, C1-C9 alkoxy, C1-C9 alkyleneoxy, amine, C1-C9 alkylamine, halogens, and phenyl.

8. The composition according to any of the preceding claims, wherein the composition, other than the dispersed ethylene-a-olefin copolymer, does not comprise an ethylene elastomer, which is an ethylene copolymer of ethylene and an alpha-olefin comonomer units having 4 to 10 carbon atoms, preferably, the ethylene elastomer is selected from the group consisting of ethylene- 1 -butene copolymer, ethylene- 1 -hexene copolymer, ethylene- 1 -octene copolymer and mixtures thereof.

9. The composition according to any of the preceding claims, wherein the composition, other than the talc (C), does not comprise fillers selected from the group consisting of chalk, clay, mica, glass fibers and carbon fibers.

10. The composition according to any of the preceding claims, further comprising(E) 0.01 to 5 wt% of additives selected from the group consisting of heat stabilizers, antioxidants, UV stabilizers, colorants, clarifiers, surface tension modifiers, lubricants, flame-retardants, mold-release agents, flow improving agents, plasticizers, anti-staticagents, blowing agents, and components that enhance interfacial bonding between polymer and filler.

11. The composition according to any of the preceding claims, wherein a sum of the propylene-based polymer (A), the heterophasic polypropylene (B), the talc (C) and the nucleating agent (D) is at least 90 wt%, preferably at least 95 wt%, more preferably at least 99 wt%, even more preferably at least 99.5 wt%.

12. The composition according to any of the preceding claims, wherein the composition meets at least one of the following:• the density of the composition is less than 0.975 g / cm3,• the flexural modulus of the composition is more than 2000 MPa, measured in accordance with ISO178 / 1A, and• the tensile modulus of the composition is more than 2000 MPa, measured in accordance with ISO527 / 1A.

13. A process for the preparation of the composition according to any of the preceding claims, comprising melt mixing the components (A), (B), (C), (D) and optional (E), to produce the composition, preferably followed by pelletizing the composition.

14. An article comprising the composition according to any of the preceding claims 1-12.

15. The article according to claim 14, which is used in cosmetic or food contact applications, preferably being a cosmetic container or a food container.

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