Anti-nucleating agents for pigmented polypropylene resins

Abstract

The present invention relates to a polypropylene composition comprising an organic pigment and a polymeric dispersing agent consisting of a polymer comprising carboxyl groups, carbamate groups or acrylic groups, an article comprising said polypropylene composition and the use of said polymeric dispersing agent in said polypropylene composition for reducing the crystallization temperature (Tc) of the composition by at least 1°C compared to a composition differing from said composition by being without polymeric dispersing agent.

Description

[0001] Anti-Nucleating Agents for Pigmented Polypropylene Resins

[0002] The present invention relates to a polypropylene composition comprising an organic pigment and a polymeric dispersing agent consisting of a polymer comprising carboxyl groups, carbamate groups or acrylic groups, an article comprising said polypropylene composition and the use of said polymeric dispersing agent in said polypropylene composition for reducing the crystallization temperature Tc of the composition by at least 1°C compared to a composition differing from said composition by being without polymeric dispersing agent.

[0003] Technical background

[0004] The nucleating effect of several widely used commercial organic pigments, like phthalocyanine blue, in polypropylene based resins causes multiple problems, especially in injection moulding applications. Too high crystallization rate, excessive shrinkage and even warpage, but also a lack of toughness, might limit the applicability. At the same time, injection moulded parts having different colours will have different dimensions, i.e . , low colour dimensional stability. So far, the only option was excessive nucleation e.g. by using proprietary Borealis Nucleation Technology (BNT) on top of the pigment. However, the present approach of „nucleation-safe“ polypropylene resins not reacting to the addition of nucleating pigments, in which excessive nucleating agent is added during polymerization or in post-reactor processing, has clearly limitations. The producer has no control over which pigments are added in which amounts and which processing conditions are set by the costumer. Therefore, nucleating agent has to be introduced in excess as a precautious measure in order to allow the customer liberty in additivation and processing conditions.

[0005] Thus, there is a need in the art to reduce the nucleating effect of organic pigments by means of additives, which can be added together and in coordination with the organic pigment so that the nucleating effect of the pigment can be selectively reduced.

[0006] In the present invention it has surprisingly been found that a polymeric dispersing agent consisting of a polymer comprising carboxyl groups, carbamate groups or acrylic groups selectively reduce the nucleating effect of organic pigments. It has been observed that the addition of such polymeric dispersing agent to a polypropylene based composition together with an organic pigment such as phthalocyanine blue results in a decrease of crystallization temperature via DSC of polypropylene, and in a decrease of the overall shrinkage of the resulting injection moulded parts. Without being bound to theory, it is believed that the dispersing agent, suitably because of its preferable amphiphilic molecular structure, is able to produce steric hindrance of the pigment particle and thus reduces the nucleating effect of the organic pigment. The dispersing agent can be added in the same processing step as the pigment and therefore can be adjusted to the amount of pigment and the processing conditions applied by the costumer.

[0007] As a consequence articles, especially injection moulded articles, are obtained which show less nucleating effects caused by the pigment, especially in behalf of crystallization rate, shrinkage, warpage, toughness and dimensional stability.

[0008] Summary of the invention

[0009] In a first aspect, the present invention relates to a composition suitable for injection moulding comprising

[0010] (A) from 80.00 to 99.9994 wt.-%, preferably from 90.00 to 99.9970 wt.-%, more preferably from 95.00 to 99.9940 wt.-% of a propylene-based polymer;

[0011] (B) from 1 to 5000 ppm, preferably from 5 to 2500 ppm, more preferably from 10 to 1500 ppm of an organic pigment; and

[0012] (C) from 5 to 10000 ppm, preferably from 25 to 8500 ppm, more preferably from 50 to 7500 ppm of a polymeric dispersing agent consisting of a polymer comprising carboxyl groups, carbamate groups or acrylic groups, all based on the total weight content of the composition.

[0013] In a further aspect, the present invention relates to an article comprising the composition as described above or below, preferably in an amount of from 90 to 100 wt.-%, more preferably in an amount of from 95 to 100 wt.-%, still more preferably in an amount of from 99 to 100 wt.-%.

[0014] Said article is preferably an injection moulded article.

[0015] In another aspect, the present invention relates to the use of the polymeric dispersing agent (C) in a composition as described above or below for reducing the crystallization temperature Tc of the composition by at least 1 °C compared to a composition differing from said composition by being without polymeric dispersing agent (C).

[0016] Definitions

[0017] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although, any methods and materials similar or equivalent to those described herein can be used in practice for testing of the present invention, the preferred materials and methods are described herein. In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below.

[0018] Unless clearly indicated otherwise, use of the terms “a,” “an,” and the like refers to one or more.

[0019] In the following, amounts are given in % by weight (wt.-%) unless it is stated otherwise.

[0020] A propylene homopolymer is a polymer that essentially consists of propylene monomer units. Due to impurities especially during commercial polymerization processes, a propylene homopolymer can comprise up to 0.1 mol-% comonomer units, preferably up to 0.05 mol-% comonomer units and most preferably up to 0.01 mol-% comonomer units.

[0021] A propylene copolymer is a copolymer of propylene monomer units and comonomer units, preferably ethylene comonomer units.

[0022] A propylene random copolymer is a propylene copolymer wherein the comonomer units are randomly distributed along the polymer chain, whilst a propylene block copolymer comprises blocks of propylene monomer units and blocks of comonomer units. Propylene random copolymers can comprise comonomer units from one or more comonomers different in their amounts of carbon atoms.

[0023] A heterophasic propylene copolymers typically comprise: a) a crystalline propylene homopolymer or copolymer matrix (M); and b) an elastomeric rubber, preferably a propylene-ethylene copolymer (E);

[0024] In case of a random heterophasic propylene copolymer, said crystalline matrix phase is a random copolymer of propylene and at least one alpha-olefin comonomer. The elastomeric phase can be a propylene copolymer with a high amount of comonomer that is not randomly distributed in the polymer chain but is distributed in a comonomerrich block structure and a propylene-rich block structure. A heterophasic polypropylene usually differentiates from a one-phasic propylene copolymer in that it shows two distinct glass transition temperatures Tg which are attributed to the matrix phase and the elastomeric phase.

[0025] The presence of a heterophasic nature can be easily determined by the number of glass transition points, like in dynamic-mechanical analysis (DMA), and / or high resolution microscopy, like scanning electron microscopy (SEM), transmission electron microscopy (TEM) or atomic force microscopy (AFM).

[0026] A polypropylene or a propylene-based polymer means a polymer being composed of units derived from propylene in an amount of more than 50 mol-%.

[0027] An amphipathic molecule contains both polar (water-soluble) and nonpolar (not water- soluble) portions in its structure.

[0028] Detailed description

[0029] In a first aspect, the present invention relates to a composition suitable for injection moulding comprising

[0030] (A) from 80.00 to 99.9994 wt.-%, preferably from 90.00 to 99.9970 wt.-%, more preferably from 95.00 to 99.9940 wt.-% of a propylene-based polymer;

[0031] (B) from 1 to 5000 ppm, preferably from 5 to 2500 ppm, more preferably from 10 to 1500 ppm of an organic pigment; and

[0032] (C) from 5 to 10000 ppm, preferably from 25 to 8500 ppm, more preferably from 50 to 7500 ppm of a polymeric dispersing agent consisting of a polymer comprising carboxyl groups, carbamate groups or acrylic groups, all based on the total weight content of the composition.

[0033] There are no specific restrictions for the selection of the propylene-based polymer (A). Preferably, the propylene-based polymer (A) can be any propylene-based polymer suitable for injection moulding application. Preferably, the propylene-based polymer (A) is a propylene homopolymer or a propylene copolymer.

[0034] The propylene copolymer preferably is a copolymer of propylene and ethylene.

[0035] The copolymer of propylene and ethylene can be a random copolymer of propylene and ethylene or a heterophasic copolymer of propylene and ethylene.

[0036] The propylene-based polymer (A) comprises, preferably consists of a propylene polymer having an ethylene content of from 0 to 20.0 wt.-%, preferably from 0 to 15.0 wt.-%, more preferably from 0 to 5.0 wt.-%, based on the total weight content of the propylene based polymer (A).

[0037] A random copolymer of propylene and ethylene usually has an ethylene content of from 0.1 to 5.0 wt.-%, more preferably from 0.2 to 4.5 wt.-%, still more preferably from 0.5 to 4.0 wt.-%, based on the total weight content of the random copolymer of propylene and ethylene.

[0038] The heterophasic copolymer of propylene and ethylene preferably has a total ethylene content of from more than 5.0 to 20.0 wt.-%, more preferably from 6.0 to 17.5 wt.-%, still more preferably from 7.5 to 15.0 wt.-%, based on the total weight content of the heterophasic copolymer of propylene and ethylene.

[0039] The propylene-based polymer (A) preferably consists of monomer units selected from propylene and optionally ethylene.

[0040] The propylene-based polymer (A) can be a single propylene-based polymer or a blend of two or more, such as two to five, preferably two or three different propylene-based polymers.

[0041] The blend can be a reactor blend in which the two or more different propylene-based polymers are prepared in different reactor stages of a multistage polymerization process.

[0042] The blend can alternatively be a melt blend, in which the two or more different propylene-based polymers are mixed together in form of powder or pellets and melt- blended in a post-polymerization stage. The melt flow rate MFR2 of the propylene-based polymer (A) is not particularly limited. Generally the propylene-based polymer (A) preferably has a melt flow rate MFR2 of from 0.1 to 300 g / 10 min, such as 0.2 to 150 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg.

[0043] In a specific embodiment, the propylene-based polymer (A) preferably has a melt flow rate MFR2 of from 10 to 50 g / 10 min, more preferably 15 to 35 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg.

[0044] Propylene-based polymers within such a melt flow rate range are especially suitable for injection moulding applications.

[0045] The polymerization process and polymerization catalyst for producing the propylene- based polymer (A) are not critical.

[0046] Usually propylene-based polymers are produced in single or multistage polymerization processes using one or more slurry and / or gas phase polymerization reactors. Suitable processes are, amongst others, Borstar® process or Spheripol™ process.

[0047] The polymerization catalyst can be any catalyst suitable for producing propylene-based polymers, such as e.g. Ziegler-Natta catalysts or single-site catalysts, like metallocene catalysts.

[0048] The composition further comprises an organic pigment (B).

[0049] The organic pigment (B) can be any organic pigment, which is known to cause a nucleating effect. The nucleating effect can be determined by measuring the crystallization temperature Tc of the composition. A pigment has a nucleating effect, when the crystallization temperature Tc of the composition including the organic pigment (B) is at least 2°C higher, such as from 2 to 15°C, preferably from 6 to 15°C higher than the crystallization temperature Tc of the composition without the organic pigment (B).

[0050] Preferably the organic pigment (B) is a phthalocyanine or a phthalocyanine derivative, preferably an AI-, Ni-, Co-, Fe-, Zn-, Cu- or Mg-derivative of phthalocyanine, more preferably a Cu-derivative of phthalocyanine. Especially preferred is copper phthalocyanine, also known as Phthalocyanine Blue (CAS No. 147-14-8).

[0051] In one embodiment the organic pigment (B) is phthalocyanine or a phthalocyanine derivative, which comprises halogen atoms, such as chlorine atoms, bromine atoms or mixtures of chlorine atoms and bromine atoms, preferably from 14 to 16 chlorine atoms or from 14 to 16 bromine atoms, preferably a Cu-derivative of phthalocyanine, which comprises from 14 to 16 chlorine atoms or bromine atoms. Suitable examples are polychlorinated copper phthalocyanine, also known as Phthalocyanine Green 7 (CAS No. 1328-53-6) or polybrominate copper phthalocyanine, also known as Phthalocyanine Green 36.

[0052] The organic pigment (B) usually is commercially available and suitable for pigmenting polypropylene compositions.

[0053] The organic pigment (B) can be added to the composition in pure form or in form of a masterbatch. In a masterbatch the organic pigment (B) is compounded into a polymeric matrix optionally together with other additives in concentrated amounts. The matrix polymer preferably is a propylene-based polymer.

[0054] “Pure” means that the organic pigment (B) is in its delivery form, i.e. it is added to the composition according to the supplier’s instructions.

[0055] The lower limit of the weight amount of the organic pigment (B) in the composition is at least 1 ppm, preferably at least 5 ppm, more preferably at least 10 ppm, based on the total weight content of the composition.

[0056] In some embodiments, the lower limit of the weight amount of the organic pigment (B) in the composition is preferably at least 100 ppm, more preferably at least 250 ppm, still more preferably at least 500 ppm, based on the total weight content of the composition.

[0057] The upper limit of the weight amount of the organic pigment (B) in the composition is not more than 5000 ppm, preferably not more than 2500 ppm, more preferably not more than 1500 ppm, based on the total weight content of the composition.

[0058] In some embodiments, the upper limit of the weight amount of the organic pigment (B) in the composition is preferably not more than 1250 ppm, more preferably not more than 1000 ppm, still more preferably not more than 500 ppm, based on the total weight content of the composition.

[0059] When adding the organic pigment (B) in form of a masterbatch, generally lower weight amounts of the organic pigment (B) can be added to the composition due to improved dispersion of the masterbatch comprising the organic pigment (B) in the composition during blending.

[0060] The amount of the organic pigment (B) in the composition when added in form of a masterbatch is preferably from 1 to 1250 ppm, more preferably from 5 to 1000 ppm, still more preferably from 10 to 500 ppm, based on the total weight content of the composition.

[0061] When adding the organic pigment (B) in pure form generally higher weight amounts of the organic pigment (B) are added to the composition due to limited accuracy of dispensing the solid powders of the organic pigment (B) to the polymeric melt of the composition and consequently limited dispersion of the pure organic pigment (B) in the composition during blending.

[0062] The amount of the organic pigment (B) in the composition when added in pure form is preferably from 100 to 5000 ppm, more preferably from 250 to 2500 ppm, still more preferably from 500 to 1500 ppm, based on the total weight content of the composition.

[0063] The claimed weight amounts of the organic pigment (B) in the composition preferably refer to the weight amounts of the pure organic pigment (B) in the composition.

[0064] The weight amounts of further components of the masterbatch, such as the matrix polymer or other additives are preferably calculated separately, when assessing the weight amounts of the composition.

[0065] The composition further comprises a polymeric dispersing agent consisting of a polymer comprising carboxyl groups, carbamate groups or acrylic groups (C), in the following polymeric dispersing agent (C).

[0066] The polymeric dispersing agent (C) preferably consists of a carboxy-functional polymer, a modified polyurethane or an acrylic block copolymer, preferably a carboxy-functional polymer or a modified polyurethane, more preferably a carboxy-functional polymer.

[0067] The polymeric dispersing agent (C) is preferably amphipathic. The polymeric dispersing agent (C) is preferably a block or graft copolymer, more preferably an amphipathic block or graft copolymer with aliphatic chains having anchoring groups like carboxylic, carbamate or ester groups.

[0068] The carboxy-functional polymer is preferably an amphipathic block or graft copolymer with aliphatic chains having carboxylic groups as anchoring groups.

[0069] The carboxy-functional polymer is preferably commercially available under the tradename Efka PA from BASF SE.

[0070] The modified polyurethane is preferably an amphipathic block or graft copolymer with aliphatic chains having carbamate groups as anchoring groups.

[0071] The modified polyurethane is preferably commercially available under the tradename Efka PU from BASF SE.

[0072] The acrylic block copolymer is preferably an amphipathic block copolymer with aliphatic chains having ester groups as anchoring groups. The acrylic block copolymer can be produced via controlled free radical polymerization (CFRP).

[0073] The acrylic block copolymer is preferably commercially available under the tradename Efka PX from BASF SE.

[0074] The polymeric dispersing agent (C) is usually in form of a liquid solution with about 30 to 70 wt.-%, such as 40 to 60 wt.-%, suitably around 50 wt.-% polymeric dispersing agent (C) in a solvent.

[0075] The polymeric dispersing agent (C) can be added to the composition in said liquid solution.

[0076] The weight amount of polymeric dispersing agent (C) in the composition is usually adapted to the weight amount of organic pigment (B), which is added to the composition.

[0077] The lower limit of the weight amount of polymeric dispersing agent (C) in the composition is at least 5 ppm, preferably at least 25 ppm, more preferably at least 50 ppm, based on the total weight content of the composition. In some embodiments the lower limit of the weight amount of polymeric dispersing agent (C) in the composition is at least 500 ppm, preferably at least 1000 ppm, more preferably at least 2500 ppm, based on the total weight content of the composition.

[0078] The upper limit of the weight amount of polymeric dispersing agent (C) in the composition is not more than 10000 ppm, preferably not more than 8500 ppm, more preferably not more than 7500 ppm, based on the total weight content of the composition.

[0079] In some embodiments the upper limit of the weight amount of polymeric dispersing agent (C) in the composition is preferably not more than 6500 ppm, more preferably not more than 5000 ppm, still more preferably not more than 3500 ppm, based on the total weight content of the composition.

[0080] The claimed weight amounts of the polymeric dispersing agent (C) in the composition preferably refer to the weight amounts of the pure polymeric dispersing agent (C) in the composition, i.e. without solvent.

[0081] The weight amounts of further components of the solution, such as the solvent are preferably calculated separately, when assessing the weight amounts of the composition.

[0082] The composition comprises the propylene-based polymer (A), the organic pigment (B) and the polymeric dispersing agent (C) in the claimed amounts.

[0083] The weight ratio of polymeric dispersing agent (C) to organic pigment (B) in the composition is preferably in the range of from 1 : 1 to 20 : 1 , more preferably 2 : 1 to 15 : 1 , still more preferably 4 : 1 to 10 : 1.

[0084] The composition can further comprise other components, such as additional polymers, further additives and solvents.

[0085] The further components of the optional masterbatch of the organic pigment (B) and the further components of the liquid solution of the polymeric dispersing agent (C) are counted to said other components.

[0086] When being a propylene-based polymer the matrix polymer of the optional masterbatch of the organic pigment (B) is counted to the propylene-based polymer (A). The amount of said optional other components in the composition is preferably in the range of from 0 to 19.9899 wt.-%, more preferably from 0 to 9.8995 wt.-%, still more preferably from 0 to 4.799 wt.-%, based on the total weight content of the composition.

[0087] The optional additional polymers can be any polymer, which does not fall under the definition of the propylene-based polymer (A), preferably a polyolefin with the main monomer not being propylene.

[0088] It is preferred that the composition does not comprise additional polymers.

[0089] The further additives are preferably provided in an amount in the range from 0.01 to 5.0 wt.-%. The skilled practitioner would be able to select suitable additives that are well known in the art.

[0090] The further additives are preferably selected from antioxidants, UV-stabilisers, antiscratch agents, mould release agents, acid scavengers, lubricants, anti-static agents, and mixtures thereof.

[0091] The further additives can be added in pure form or in form of a masterbatch. Thereby, the additives can at least partly be added to the masterbatch of the organic pigment (B). When being a propylene-based polymer the matrix polymer of the optional masterbatch of the further additives is counted to the propylene-based polymer (A).

[0092] The propylene-based polymer (A), the organic pigment (B), the polymeric dispersing agent (C) and the optional other components make up 100 wt.-% of the total weight content of the composition.

[0093] The melt flow rate MFR2 of the composition is not particularly limited. Generally the composition preferably has a melt flow rate MFR2 of from 0.1 to 300 g / 10 min, such as 0.2 to 150 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg.

[0094] In a specific embodiment, the composition preferably has a melt flow rate MFR2 of from 10 to 50 g / 10 min, more preferably 15 to 35 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg.

[0095] A composition with a melt flow rate in said range is especially suitable for injection moulding applications. Further, the composition preferably has an anti-nucleation efficiency scale aNE of from 15 to 80 %, preferably from 25 to 70 %, more preferably from 35 to 60 %, wherein aNE is calculated according to the following formula where

[0096] Td is the crystallization temperature Tcof the pure polymer without organic pigment (B) and polymeric dispersing agent (C),

[0097] TC2 is the crystallization temperature Tcof the composition containing the organic pigment (B) but no polymeric dispersing agent (C), and

[0098] Tex is the crystallization temperature Tcof the composition containing both the organic pigment (B) and the polymeric dispersing agent (C).

[0099] The composition preferably has a crystallization temperature Tc, which is at least 1 °C, more preferably at least 2.5°C, still more preferably at least 4.5°C lower compared to a composition differing from said composition by being without polymeric dispersing agent (C).

[0100] The composition preferably has a crystallization temperature Tc, which is not more than 10°C, more preferably not more than 8.5°C lower compared to a composition differing from said composition by being without polymeric dispersing agent (C).

[0101] In a further aspect, the present invention relates to an article comprising the composition as described above or below, preferably in an amount of from 90 to 100 wt.-%, more preferably in an amount of from 95 to 100 wt.-%, still more preferably in an amount of from 99 to 100 wt.-%.

[0102] Said article is preferably an injection moulded article.

[0103] In said aspect it is preferred that all properties and embodiments of the composition also apply to the article.

[0104] The article preferably has a shrinkage in machine direction (MD) of not more than 1.38 % and / or a shrinkage in transverse direction (TD) of not more than 1 .45 %.

[0105] The shrinkage is preferably measured on injection moulding plates with dimension 60x60x2 mm3according to EN ISO 19069-2 after 96 hours. In another aspect, the present invention relates to the use of the polymeric dispersing agent (C) in a composition as described above or below for reducing the crystallization temperature Tc of the composition by at least 1 °C, preferably at least 2.5°C, more preferably at least 4.5°C compared to a composition differing from said composition by being without polymeric dispersing agent (C).

[0106] Preferably the crystallization temperature Tc of the composition is reduced by not more than 10°C, more preferably not more than 8.5°C compared to a composition differing from said composition by being without polymeric dispersing agent (C).

[0107] In said aspect it is preferred that all properties and embodiments of the composition and the article also apply to the use.

[0108] Examples

[0109] 1. Determination methods

[0110] The following definitions of terms and determination methods apply for the above general description of the invention including the claims as well as to the below examples unless otherwise defined.

[0111] Quantification of microstructure by NMR spectroscopy

[0112] Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content and comonomer sequence distribution of the polymers. Quantitative13C{1H} NMR spectra were recorded in the solution-state using a Bruker Advance III 400 NMR spectrometer operating at 400.15 and 100.62 MHz for1H and13C respectively. All spectra were recorded using a13C optimised 10 mm extended temperature probehead at 125°C using nitrogen gas for all pneumatics. Approximately 200 mg of material was dissolved in 3 ml of 7,2-tetrachloroethane-c / 2 (TCE-cfo) along with chromium-(lll)- acetylacetonate (Cr(acac)3) resulting in a 65 mM solution of relaxation agent in solvent (Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure a homogenous solution, after initial sample preparation in a heat block, the NMR tube was further heated in a rotatary oven for at least 1 hour. Upon insertion into the magnet the tube was spun at 10 Hz. This setup was chosen primarily for the high resolution and quantitatively needed for accurate ethylene content quantification. Standard single-pulse excitation was employed without NOE, using an optimised tip angle, 1 s recycle delay and a bi-level WALTZ16 decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128). A total of 6144 (6k) transients were acquired per spectra.

[0113] Quantitative13C{1H} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. This approach allowed comparable referencing even when this structural unit was not present. Characteristic signals corresponding to the incorporation of ethylene were observed Cheng, H. N., Macromolecules 17 (1984), 1950).

[0114] With characteristic signals corresponding to 2,1 erythro regio defects observed (as described in L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev. 2000, 100 (4), 1253, in Cheng, H. N., Macromolecules 1984, 17, 1950, and in W-J. Wang and S. Zhu, Macromolecules 2000, 33 1157) the correction for the influence of the regio defects on determined properties was required. Characteristic signals corresponding to other types of regio defects were not observed.

[0115] The comonomer fraction was quantified using the method of Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157) through integration of multiple signals across the whole spectral region in the13C{1H} spectra. This method was chosen for its robust nature and ability to account for the presence of regio-defects when needed. Integral regions were slightly adjusted to increase applicability across the whole range of encountered comonomer contents.

[0116] For systems where only isolated ethylene in PPEPP sequences was observed the method of Wang et. al. was modified to reduce the influence of non-zero integrals of sites that are known to not be present. This approach reduced the overestimation of ethylene content for such systems and was achieved by reduction of the number of sites used to determine the absolute ethylene content to: E = 0.5(Spp + Spy + Sp6 + 0.5(Sap + Say))

[0117] Through the use of this set of sites the corresponding integral equation becomes: E = 0.5(IH +IG + 0.5(lc + ID)) using the same notation used in the article of Wang et. al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157). Equations used for absolute propylene content were not modified.

[0118] The mole percent comonomer incorporation was calculated from the mole fraction: E [mol%] = 100 * fE

[0119] The weight percent comonomer incorporation was calculated from the mole fraction: E [wt%] = 100 * (fE * 28.06) I ((fE * 28.06) + ((1-fE) * 42.08))

[0120] The comonomer sequence distribution at the triad level was determined using the analysis method of Kakugo et al. (Kakugo, M., Naito, Y., Mizunuma, K., Miyatake, T. Macromolecules 15 (1982) 1150). This method was chosen for its robust nature and integration regions slightly adjusted to increase applicability to a wider range of comonomer contents.

[0121] The relative content of isolated to block ethylene incorporation was calculated from the triad sequence distribution using the following relationship (equation (I)): 100 ( VI) ' wherein

[0122] 1(E) is the relative content of isolated to block ethylene sequences [in %]; fPEP is the mol fraction of propylene / ethylene / propylene sequences (PEP) in the sample; fPEE is the mol fraction of propylene / ethylene / ethylene sequences (PEE) and of ethylene / ethylene / propylene sequences (EEP) in the sample; fEEE is the mol fraction of ethylene / ethylene / ethylene sequences (EEE) in the sample

[0123] Melt Flow Rate

[0124] The melt flow rate (MFR) was determined according to ISO 1133 and is indicated in g / 10 min. The MFR is an indication of the flowability, and hence the processability, of the polymer. The higher the melt flow rate, the lower the viscosity of the polymer. The MFR2 of polypropylene was determined at a temperature of 230°C and a load of 2.16 kg.

[0125] DSC analysis, melting temperature (Tm) and heat of fusion (Hf), crystallization temperature (Tc) and heat of crystallization (He): was measured with a TA Instrument Q200 differential scanning calorimetry (DSC) on 5 to 7 mg samples. DSC was run according to ISO 11357 / part 3 / method C2 in a heat / cool / heat cycle with a scan rate of 10 °C / min in the temperature range of -30 to +225°C. Crystallization temperature (Tc) and crystallization enthalpy (Hc) were determined from the cooling step, while melting temperature (Tm) and melting enthalpy (Hm) were determined from the second heating step.

[0126] Shrinkage

[0127] The shrinkage was measured in machine direction (MD and transverse direction (TD) on a 60x60x2 mm3specimen, injection moulded according to ISO 19069-2. Before measurements, the specimen were conditioned at 23 ±2°C and relative humidity 50% for 96h.

[0128] 2. Examples

[0129] 2.1 Components

[0130] The following components were used for the preparation of the compositions of examples CE1 , CE2, IE1 , IE2 and IE3:

[0131] PP propylene-co-ethylene random copolymer with a melt flow rate MFR2 of 20 g / 10 min and an ethylene content of 3.4 wt.-%

[0132] Pigment Copper-phthalocyanine blue pigment Heliogen Blue K7090, commercially available from BASF SE

[0133] Efka PA 4450 carboxy-fu notion al polymer, polymeric dispersing agent, commercially available from BASF SE

[0134] Efka PU 4046 modified polyurethane, polymeric dispersing agent, commercially available from BASF SE

[0135] Efka PX 4350 acrylic block copolymer, polymeric dispersing agent, commercially available from BASF SE

[0136] AO1 Irganox 1010, commercially available from BASF SE

[0137] AO2 Irgafos 168, commercially available from BASF SE

[0138] 2.2 Preparation of compositions

[0139] The dispersing agents were received in solution with a concentration of circa 50 wt.-% of the solute. In order to obtain a final concentration of dispersing agent in the polymer of about 0.5 wt.-%, 1 wt.-% of the original dispersing agent solution was sprayed onto the PP powder admixed with the AOs. A drying step at 100°C for 16 h was performed in order to eliminate solvent residues. Eventually, the dried mix was compounded with the remaining components.

[0140] In Table 1 the compositions of examples CE1 , CE2. IE1 , IE2 and IE3 are listed.

[0141] Table 1 : Compositions of examples CE1 , CE2. IE1 , IE2 and IE3 n.a. = not applicable

[0142] 2.3 Nucleating behaviour of the examples

[0143] The nucleating behaviour of the examples was determined by measuring the crystallization temperature Tc and the shrinkage of injection moulded test specimens in MD and TD.

[0144] The anti-nucleation efficiency aNE was calculated from the measured Tc’s as follows: with

[0145] Tc1 being the Tc of pure polymer without pigment and dispersing agent (CE1)

[0146] Tc2 being the Tc of the composition comprising the pigment but no dispersing agent

[0147] (CE2)

[0148] Tex being the Tc of the composition comprising the pigment and dispersing agent (IE1- IE3)

[0149] The results are listed in Table 2. Table 2: Results n.m. = not measured

[0150] CE1 has the lowest value of crystallization temperature (To), being this the pure polymer, while CE2 has the highest To, due to the nucleating effect of the pigment. It can be seen that the inventive compounds show a Tc lower than the compound CE2 and higher than CE1. This means that the used dispersing agents reduce the nucleation ability of the pigment. Both the shrinkage in MD and in TD are also lower in the inventive examples, being linked to the decrease in crystallization rate seen via the Tc values. From the anti-nucleation efficiency calculation it can be seen that the scale of efficiency in inhibiting the nucleation effect of the pigment is: Efka PA 4450 > Efka PU 4046 > Efka PX 4350.

Claims

Claims1. A composition suitable for injection moulding comprising(A) from 80.00 to 99.9994 wt.-%, preferably from 90.00 to 99.9970 wt.-%, more preferably from 95.00 to 99.9940 wt.-% of a propylene-based polymer;(B) from 1 to 5000 ppm, preferably from 5 to 2500 ppm, more preferably from 10 to 1500 ppm of an organic pigment; and(C) from 5 to 10000 ppm, preferably from 25 to 8500 ppm, more preferably from 50 to 7500 ppm of a polymeric dispersing agent consisting of a polymer comprising carboxyl groups, carbamate groups or acrylic groups, all based on the total weight content of the composition.

2. The composition according to claim 1 , wherein the propylene-based polymer (A) comprises, preferably consists of a propylene polymer having an ethylene content of from 0 to 20.0 wt.-%, preferably from 0 to 15.0 wt.-%, more preferably from 0 to 5.0 wt.-%, based on the total weight content of the propylene based polymer (A) and determined by quantitative NMR spectroscopy.

3. The composition according to claims 1 or 2, wherein the propylene-based polymer(A) is a propylene homopolymer or a copolymer of propylene and ethylene, preferably a propylene homopolymer or a random copolymer of propylene and ethylene.

4. The composition according to any one of claims 1 to 3, wherein the propylene- based polymer (A) consists of monomer units selected from propylene and optionally ethylene.

5. The composition according to any one of claims 1 to 4, wherein the propylene- based polymer (A) has a melt flow rate MFR2 of from 0.1 to 300 g / 10 min, preferably 0.2 to 150 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg.

6. The composition according to any one of claims 1 to 5, wherein the organic pigment(B) has a nucleating effect.

7. The composition according to any one of claims 1 to 6, wherein the organic pigment (B) is a phthalocyanine or a phthalocyanine derivative, preferably an AI-, Ni-, Co-, Fe-, Zn-, Cu- or Mg-derivative of phthalocyanine, more preferably a Cu-derivative of phthalocyanine.

8. The composition according to claim 7, wherein the organic pigment (B) is phthalocyanine or a phthalocyanine derivative, which comprises halogen atoms, such as chlorine atoms, bromine atoms or mixtures of chlorine atoms and bromine atoms, preferably from 14 to 16 chlorine atoms or from 14 to 16 bromine atoms, preferably a Cu-derivative of phthalocyanine, which comprises from 14 to 16 chlorine atoms or bromine atoms.

9. The composition according to any one of claims 1 to 8, wherein polymeric dispersing agent (C) consists of a carboxy-functional polymer, a modified polyurethane or an acrylic block copolymer, preferably a carboxy-functional polymer or a modified polyurethane, more preferably a carboxy-functional polymer.

10. The composition according to any one of claims 1 to 9 having a melt flow rate MFR2 of from 0.1 to 300 g / 10 min, preferably 0.2 to 150 g / 10 min, determined according to ISO 1133 at 230°C and 2.16 kg.11 . The composition according to any one of claims 1 to 10 having an anti-nucleation efficiency scale aNE of from 15 to 80 %, preferably from 25 to 70 %, more preferably from 35 to 60 %, wherein aNE is calculated according to the following formula aNE = ?£ Z?£ x100% T:2 T:1 whereTd is the crystallization temperature Tcof the pure polymer without organic pigment (B) and polymeric dispersing agent (C),TC2 is the crystallization temperature Tcof the composition containing the organic pigment (B) but no polymeric dispersing agent (C), andTex is the crystallization temperature Tcof the composition containing both the organic pigment (B) and the polymeric dispersing agent (C).

12. An article comprising the composition according to any one of claims 1 to 11 , preferably in an amount of from 90 to 100 wt.-%, more preferably in an amount of from 95 to 100 wt.-%, still more preferably in an amount of from 99 to 100 wt.-%.

13. The article according to claim 12 being an injection moulded article.

14. The article according to claim 12 or 13 having a shrinkage in machine direction(MD) of not more than 1 .38 % and / or a shrinkage in transverse direction (TD) of not more than 1.45%, measured on 60x60x2 mm3specimens, injection moulded according to ISO 19069-2.

15. Use of the polymeric dispersing agent (C) in a composition according to any one of claims 1 to 11 for reducing the crystallization temperature Tc of the composition by at least 1 °C compared to a composition differing from said composition by being without polymeric dispersing agent (C).

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