Polymer compositions for shaped articles

Abstract

The polyethylene composition comprises a) at least 89.0 wt.% of a multimodal polyethylene polymer, b) optionally 0.01 to 10.0 wt.% of a colorant or a color concentrate containing a colorant; c) 0.01 to 1.0 wt.% of a nucleating agent of formula (I), wherein A = a monocyclic or bicyclic aromatic group; each X is independently a -CO-NH-group or a -NH-CO-group; R1 to R3 are each independently a C1-C20 alkyl group optionally substituted with one or more hydroxyl groups; a C2-C20 alkenyl group optionally substituted with one or more hydroxyl groups; a C2-C20 alkyl group interrupted by oxygen or sulfur; a C3-C12 cycloalkyl group optionally substituted with one or more C1-C20 alkyl groups; or a C3-C12 cycloalkyl-C1-6-alkenyl group, wherein the C3-12 cycloalkyl group is optionally substituted with one or more C1-C20 alkenyl groups. #imgabs0#R1-X-A-X-R2 (II).

Description

Technical Field

[0001] The present invention relates to a polyethylene composition comprising a multimodal polyethylene polymer, an optional colorant, and a nucleating agent. The present invention also relates to injection-molded and compression-molded articles comprising the composition, to the use of a nucleating composition comprising a nucleating agent and a colorant to normalize or reduce shrinkage anisotropy or warpage of injection-molded or compression-molded articles, and to the use of a nucleating composition to reduce angel hair, high points, and increase cycle time in cap manufacturing. Background Art

[0002] Many HDPE (high-density polyethylene) polymers are used to make caps or closures for containers such as bottles. These caps are made by injection molding or compression molding.

[0003] Many caps are colored for aesthetic reasons or perhaps to designate the nature of the product being packaged. For example, color-coded caps are often used to indicate the type of fresh milk in the container.

[0004] One issue with cap production is color dimensional stability. This problem can manifest itself simply when using colorants or when switching from one masterbatch to another. The present inventors have discovered that the presence of colorants can cause shrinkage issues in the resulting molded article. Specifically, the presence of colorants can increase shrinkage or exacerbate shrinkage anisotropy, meaning different shrinkage in the transverse and machine directions.

[0005] The inventors have discovered that the solution to this problem lies in the nature of the nucleating agent introduced into the resin.

[0006] The use of multimodal HDPE in the preparation of shaped articles is not new. EP-A-2052026 describes multimodal HDPE for use in shaped articles. EP-A-3283566 describes HDPE compositions for use in the manufacture of caps or closures comprising HDPE and a nucleating agent which is an alkali metal salt or a carboxylate.

[0007] EP-A-3515953 describes nucleated polyethylene blends and their use in shaped articles. The blends claimed contain a mixture of monomodal and bimodal HDPE and are nucleated with, for example, dimethylene sorbitol esters.

[0008] However, the present invention requires the use of a specific class of nucleating agents, described further below. These nucleating agents are typically N,N′-disubstituted arylene dicarboxamides. This class of nucleating agents is not new and is described in EP-A-3037466, where the nucleating agents improve the optical properties of polymer compositions to which they are added. However, the polymer combined with the nucleating agent in EP-A-3037466 is not a multimodal polymer.

[0009] JPH 06234890 describes a polyethylene resin composition comprising a polyethylene resin, a specific polycarboxylic acid amide compound, and a polyamine amide compound or a polyamino acid amide compound.

[0010] In EP-A-1 592 738, triamide-substituted compounds are compounded with any polymer, such as polyethylene. These compounds act as mist reducers.

[0011] However, the issue of color dimensional stability (CDS) has not been considered before. In a first embodiment, the present invention is directed to reducing or regulating the effect of colorants or color masterbatches on the shrinkage of molded articles. The inventors have discovered that the addition of certain nucleating agents can reduce or regulate shrinkage.

[0012] After a molded article is produced, as the polymer melt cools, it will shrink to some extent. The industry determines shrinkage in both the machine and transverse directions. While minimizing shrinkage is generally a preferred goal, ensuring uniform shrinkage in both directions is also important. Skilled artisans dislike articles that shrink significantly in one direction and not at all in the other. Such articles will distort. Therefore, skilled artisans seek uniformity in shrinkage, ideally low levels of shrinkage.

[0013] The present inventors have discovered that when a colorant or a masterbatch containing the colorant is combined with a base polymer (here a multimodal polyethylene polymer), the final molded article exhibits significant shrinkage anisotropy, i.e., the molded article shrinks more in one direction than in another.

[0014] The present inventors sought a solution to the problem of shrinkage anisotropy. Ideally, they also desired to minimize the shrinkage of molded articles. They discovered that the use of nucleating agents based on certain aromatic di- or triamides can regulate anisotropy and, depending on the properties of the colorant, reduce overall shrinkage.

[0015] Furthermore, the inventors have discovered that the combination of a base polymer (here, a multimodal polyethylene polymer) and certain nucleating agents based on aromatic di- or triamides (optionally in combination with a colorant) can reduce angel hair and / or peaking on caps and reduce cap cycle time. This means that more caps can be produced in a fixed amount of time. Therefore, the present invention further relates to the combination of a multimodal polyethylene polymer and a nucleating agent in the absence of a colorant. Summary of the Invention

[0016] Summary of the Invention

[0017] From one aspect, the present invention provides a polyethylene composition comprising

[0018] a) at least 89.0 wt.% multimodal polyethylene polymer;

[0019] b) 0.01 to 10.0 wt.-% of a colorant or a masterbatch containing a colorant;

[0020] c) 0.01 to 1.0 wt.-% of a nucleating agent of formula (I)

[0021]

[0022] in

[0023] A = monocyclic or bicyclic aryl;

[0024] Each X is independently a -CO-NH- group or a -NH-CO- group;

[0025] R1 to R3 are each independently C1-C20 alkyl optionally substituted with one or more hydroxyl groups; C2-C20 alkenyl optionally substituted with one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl groups; or C3-C12 cycloalkyl-C1-6-alkenyl, wherein the C3-C12 cycloalkyl is optionally substituted with one or more C1-C20 alkyl groups.

[0026] From another aspect, the present invention provides a polyethylene composition comprising

[0027] a) at least 89.0 wt.% multimodal polyethylene polymer;

[0028] b) optionally 0.01 to 10.0 wt.-% of a colorant or a masterbatch containing a colorant;

[0029] c) 0.01 to 1.0 wt.-% of a nucleating agent of formula (I)

[0030]

[0031] in

[0032] A = monocyclic or bicyclic aryl;

[0033] Each X is independently a -CO-NH- group or a -NH-CO- group;

[0034] R1 to R3 are each independently C1-C20 alkyl optionally substituted with one or more hydroxyl groups; C2-C20 alkenyl optionally substituted with one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl groups; or C3-C12 cycloalkyl-C1-6-alkenyl, wherein the C3-C12 cycloalkyl is optionally substituted with one or more C1-C20 alkyl groups.

[0035] From another aspect, the present invention provides a polyethylene composition comprising

[0036] a) at least 89.0 wt.% multimodal polyethylene polymer;

[0037] b) 0.01 to 10.0 wt.-% of a colorant or a masterbatch containing a colorant;

[0038] c) 0.01 to 1.0 wt.-% of a nucleating agent of formula (II)

[0039] R1-XAX-R2 (II)

[0040] in

[0041] A = monocyclic or bicyclic aryl;

[0042] Each X is independently a -CO-NH- group or a -NH-CO- group;

[0043] R1 to R2 are each independently a C1-C20 alkyl group optionally substituted by one or more hydroxy groups; a C2-C20 alkenyl group optionally substituted by one or more hydroxy groups; a C2-C20 alkyl group interrupted by oxygen or sulfur; a C3-C12 cycloalkyl group optionally substituted by one or more C1-C20 alkyl groups; a C3-C12 cycloalkyl-C1-6 alkenyl group, wherein the C3-12 cycloalkyl group is optionally substituted by one or more C1-C20 alkyl groups.

[0044] From another aspect, the present invention provides a polyethylene composition comprising

[0045] a) at least 89.0 wt.% multimodal polyethylene polymer;

[0046] b) optionally 0.01 to 10.0 wt.-% of a colorant or a masterbatch containing a colorant;

[0047] c) 0.01 to 1.0 wt.-% of a nucleating agent of formula (II)

[0048] R1-XAX-R2 (II)

[0049] in

[0050] A = monocyclic or bicyclic aryl;

[0051] Each X is independently a -CO-NH- group or a -NH-CO- group;

[0052] R1 to R2 are each independently a C1-C20 alkyl group optionally substituted by one or more hydroxy groups; a C2-C20 alkenyl group optionally substituted by one or more hydroxy groups; a C2-C20 alkyl group interrupted by oxygen or sulfur; a C3-C12 cycloalkyl group optionally substituted by one or more C1-C20 alkyl groups; a C3-C12 cycloalkyl-C1-6 alkenyl group, wherein the C3-12 cycloalkyl group is optionally substituted by one or more C1-C20 alkyl groups.

[0053] Viewed from another aspect, the present invention provides the use of a nucleating agent of formula (I) or (II) as described herein for reducing shrinkage anisotropy and / or warpage of an injection or compression molded article.

[0054] Viewed from another aspect, the invention provides an article, preferably an injection or compression molded article, more preferably a cap or closure, comprising the polyethylene composition described herein.

[0055] From another aspect, the present invention provides a nucleating composition comprising

[0056] (I) 50.0-99.0 wt.-% of a color masterbatch containing a macrocyclic organic pigment; and

[0057] (II) 1.0-50.0 wt.-% nucleating agent of formula (I)

[0058]

[0059] or 1.0-50.0 wt.-% of a nucleating agent of formula (II)

[0060] R1-XAX-R2 (II)

[0061] in

[0062] A = monocyclic or bicyclic aryl;

[0063] Each X is independently a -CO-NH- group or -NH-CO-;

[0064] R1 to R3 are each independently a C1-C20 alkyl group optionally substituted with one or more hydroxy groups; a C2-C20 alkenyl group optionally substituted with one or more hydroxy groups; a C2-C20 alkyl group interrupted by oxygen or sulfur; a C3-C12 cycloalkyl group optionally substituted with one or more C1-C20 alkyl groups; or a C3-C12 cycloalkyl-C1-6 alkenyl group, wherein the C3-12 cycloalkyl group is optionally substituted with one or more C1-C20 alkyl groups.

[0065] Viewed from another aspect the invention provides the use of a nucleating composition as hereinbefore described for reducing shrinkage anisotropy and / or warpage in an injection or compression moulded article.

[0066] Viewed from another aspect the invention provides the use of a nucleating agent of formula (I) or (II) as hereinbefore described for reducing spiky and / or angel hair in injection or compression moulded caps.

[0067] Viewed from another aspect, the present invention provides the use of a nucleating agent of formula (I) or (II) as hereinbefore described for reducing the cycle time in the manufacture of an injection or compression molded cap. DETAILED DESCRIPTION

[0068] Detailed Description of the Invention

[0069] The present invention relates to a composition for preparing shaped articles such as caps and closures. In particular, the present invention relates to a polyethylene composition comprising

[0070] a) at least 89.0 wt.% multimodal polyethylene polymer;

[0071] b) optionally 0.01 to 10.0 wt.-% of a colorant or a masterbatch containing a colorant;

[0072] c) 0.01 to 1.0 wt.-% of a nucleating agent of formula (I)

[0073]

[0074] or 0.01 to 1.0 wt.-% of a nucleating agent of formula (II)

[0075] R1-XAX-R2 (II)

[0076] in

[0077] A = monocyclic or bicyclic aryl.

[0078] Each X is independently a -CO-NH- group or a -NH-CO- group.

[0079] R1 to R3 are each independently C1-C20 alkyl optionally substituted with one or more hydroxyl groups; C2-C20 alkenyl optionally substituted with one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl groups; or C3-C12 cycloalkyl-C1-6-alkenyl, wherein the C3-C12 cycloalkyl is optionally substituted with one or more C1-C20 alkyl groups.

[0080] Multimodal polyethylene polymers

[0081] The polyethylene composition comprises a multimodal polyethylene polymer, preferably HDPE (high density polyethylene), particularly a high density polyethylene copolymer. Therefore, the multimodal high density ethylene copolymer preferably contains comonomers. However, on a molar basis, the majority of the monomer residues present are derived from ethylene monomer units.

[0082] Any multimodal polyethylene polymer preferably comprises:

[0083] (I) a lower molecular weight ethylene homopolymer or copolymer component; and

[0084] (II) A high molecular weight (HMW) ethylene copolymer component composed of ethylene and at least one C3-12 alpha olefin comonomer.

[0085] The comonomer content in the HMW component is preferably no more than 10% by mole, more preferably no more than 5% by mole. However, it is desirable to have very low levels of comonomer content in any copolymer component, such as 0.1 to 3.0 mol%, e.g., 0.5 to 2.0 mol%.

[0086] The total comonomer content of the multimodal polyethylene copolymer as a whole may be from 0.05 to 3.0 mol%, such as from 0.1 to 2.0 mol%, preferably from 0.2 to 1.0 mol%.

[0087] Copolymerizable monomers or monomers present in any copolymer component are C3-12 alpha olefin monomers, in particular monoolefinic or polyolefinically unsaturated monomers, especially C4-12 alpha olefins, such as propylene, 1-butene, 1-hexene, 1-octene and 4-methylpentene. The use of 1-hexene and 1-butene is particularly preferred. Ideally, only one monomer is present, but it is also possible to have two or more monomers present to form a terpolymer.

[0088] When one comonomer is present, the comonomer is preferably 1-butene. If two or more comonomers are present, they are preferably 1-butene and 1-hexene.

[0089] Multimodal polyethylene polymers are multimodal and therefore comprise at least two components. Generally, it is preferred if the Mw of the high molecular weight (HMW) component is at least 5,000 greater than the Mw of the low molecular weight (LMW) component, for example at least 10,000 greater. Another way of looking at this is that the MFR2 of the HMW component is lower than the MFR2 of the LMW component, for example at least 2 g / 10 min.

[0090] Multimodal polyethylene polymers are multimodal. Typically, polyethylene compositions containing at least two polyethylene components are referred to as "multimodal," where these components are produced under different polymerization conditions, resulting in different (weight-average) molecular weights and molecular weight distributions. Thus, in this sense, the compositions of the present invention are multimodal polyethylenes. The prefix "multi" indicates that the composition is composed of multiple different polymer components. Thus, for example, a composition consisting of only two components is referred to as "bimodal."

[0091] The form of the molecular weight distribution curve of such a multimodal polyethylene, ie a plot of the polymer weight fraction as a function of its molecular weight, will show two or more maxima, or at least be significantly broadened compared to the curve for a single fraction.

[0092] For example, if a polymer is produced in a continuous, multi-stage process, utilizing reactors in series and using different conditions in each reactor, the polymer fractions produced in the different reactors will have their own molecular weight distributions and weight average molecular weights. When a molecular weight distribution curve for such a polymer is recorded, the individual curves for these fractions are superimposed on the molecular weight distribution curve for the total polymer product produced, typically producing a curve with two or more distinct maxima.

[0093] It is further preferred if the multimodal polyethylene polymer is bimodal.

[0094] The MFR2 of the multimodal polyethylene polymer is preferably from 0.5 to 20 g / 10 min, preferably from 2.0 to 10.0 g / 10 min, and preferably from 2.0 to 5.0 g / 10 min. The MFR2 of the polymer is preferably from 2.0 to 4.9 g / 10 min. Most preferably, the MFR2 may be from 2.5 to 4.9 g / 10 min, and preferably from 3.0 to 4.9 g / 10 min. In some embodiments, the MFR2 may be from 0.1 to 10.0 g / 10 min, and preferably from 0.5 to 4.9 g / 10 min.

[0095] The MFR5 of the multimodal polyethylene polymer is preferably from 11.0 to 18.0 g / 10 min, preferably 12-16 g / 10 min.

[0096] The density of the multimodal polyethylene polymer is preferably at least 0.940 g / cm 3 , for example 0.940-0.980 g / cm 3 , preferably 0.945-0.970 g / cm 3 in the range of 0.950-0.960 g / cm 3 range.

[0097] The molecular weight distribution Mw / Mn of the multimodal polyethylene polymer, ie the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, is preferably 5-50, preferably between 10-30, more preferably 10.5 to 18.0.

[0098] The Mw / Mn of the multimodal polyethylene polymer is preferably 30.0 or less, more preferably 25.0 or less, even more preferably 20.0 or less.

[0099] The weight average molecular weight Mw of the multimodal polyethylene polymer is preferably at least 50,000, more preferably at least 70,000. Furthermore, the Mw of the composition is preferably at most 200,000, more preferably at most 150,000.

[0100] As mentioned above, the multimodal polyethylene polymer preferably comprises a low molecular weight component (I) and a high molecular weight component (II). The weight ratio of the LMW component (I) to the HMW component (II) in the multimodal polyethylene polymer is preferably between 35:65 and 55:45, more preferably between 40:60 and 55:45, and most preferably between 48:52 and 52:48. Thus, it has been found that the best results are achieved when the HMW component is present in approximately the same proportion as the LMW component or even predominates, for example 48 to 52 wt% of the HMW component (II) and 52 to 48 wt% of the component (I).

[0101] Therefore, the ideal polymer is a lower molecular weight homopolymer component (I) and a higher molecular weight component (II), which is an ethylene, 1-butene component.

[0102] The low molecular weight component (I) preferably has an MFR2 of 200 to 400 g / 10min. The preferred range is 250 to 350 g / 10min. This high MFR2 of the LMW component ensures a large Mw difference between the LMW and HMW components, which is important for imparting good rheological properties and ideal flowability as well as good ESCR to the multimodal polyethylene polymer.

[0103] Component (I) is preferably an ethylene homopolymer, preferably with a density of 965 to 975 kg / m 3 , preferably 968 to 972 kg / m 3 .

[0104] The HMW component is preferably an ethylene copolymer. Its properties are selected to achieve the desired final density and MFR. It has a lower MFR2 than the LMW component and a lower density. Ideally, it is a copolymer of ethylene and 1-butene.

[0105] The multimodal (e.g., bimodal) polyethylene polymers described herein can be produced by mechanically mixing two or more polyethylenes (e.g., unimodal polyethylenes) having different central maxima in their molecular weight distributions. The unimodal polyethylenes required for the blending can be purchased commercially or prepared using any conventional process known to those skilled in the art. Each polyethylene used in the blend and / or final polymer composition can have the characteristics of the low molecular weight component and the high molecular weight component of the composition described herein, respectively.

[0106] However, it is preferred if the multimodal polyethylene polymer is formed in a multistage process. The process of the present invention preferably involves polymerising ethylene to form the low molecular weight homopolymer component (I) as described herein;

[0107] In the presence of component (I), ethylene and at least one C3-12 alpha olefin comonomer are polymerized to form a higher molecular weight component (II), thereby forming the multimodal polyethylene copolymer desired in the present invention.

[0108] Any catalyst can be used to prepare the multimodal polyethylene polymers of the present invention, including single-site (e.g., metallocene) catalysts and Ziegler-Natta catalysts. It is preferred if the same Ziegler-Natta catalyst is used in both stages of the process and is transferred from step (I) to step (II) along with component (I).

[0109] It is preferred if at least one of the components is produced in a gas phase reaction.

[0110] It is further preferred that one of components (I) and (II), preferably component (I), of the multimodal polyethylene polymer is produced in a slurry reaction, preferably in a circulation reactor, and one of components (I) and (II), preferably component (II) is produced in a gas phase reaction.

[0111] Preferably, the multimodal polyethylene polymer can be produced by polymerization using a Ziegler Natta catalyst system using conditions that produce a multimodal (e.g., bimodal) polymer product, which uses a two or more stage (i.e., multi-stage) polymerization process with different process conditions (e.g., different temperatures, pressures, polymerization media, hydrogen partial pressures, etc.) in different stages or zones.

[0112] Polymer compositions produced in a multi-stage process are also designated as "in situ" mixtures.

[0113] Preferably, the main polymerization stage of the multi-stage process for producing the composition according to the invention is as described in EP 517 868, i.e. the production of components (I) and (II) is carried out as a combination of slurry polymerization of component (I) / gas phase polymerization of component (II). The slurry polymerization is preferably carried out in a so-called loop reactor. Further preferably, the slurry polymerization stage precedes the gas phase stage.

[0114] Optionally and advantageously, the main polymerization stage can be preceded by a prepolymerization, in which case up to 10%, preferably 1-5%, and more preferably 1-3% by weight of the total composition can be produced. The prepolymer is preferably an ethylene homopolymer (high-density polyethylene). During the prepolymerization, preferably all the catalyst is charged into a loop reactor and the prepolymerization is carried out as a slurry polymerization. Such a prepolymerization results in fewer fine particles in the subsequent reactor and a more uniform product at the end. Any prepolymer is considered to be part of the LMW component.

[0115] The polymerization catalyst is preferably a Ziegler-Natta (ZN) catalyst. The catalyst may be supported, for example, on a conventional support, including a magnesium dichloride-based support or silica. Preferably, the catalyst is a ZN catalyst, more preferably, the catalyst is a silica-supported ZN catalyst.

[0116] Generally, the multimodal polyethylene polymer used herein is a commercial product that can be purchased from suppliers such as Borealis.

[0117] Pigments

[0118] The polyethylene composition of the present invention preferably also includes a colorant, which can be included in a masterbatch. The term masterbatch describes a coloring composition comprising a carrier and one or more colorants. The properties of these masterbatches are generally proprietary, but it is believed that the colorant content in such masterbatches is between 10 and 50 wt%, for example 10 to 30 wt%.

[0119] The nature of the carrier present in the masterbatch is not critical and will generally be a polymer such as a polyolefin.

[0120] Therefore, the character and quantity of colorant change according to the difference of colorant.In one embodiment, colorant is organic, particularly organic macrocyclic compound.In another embodiment, colorant is inorganic.Also can use the mixture of colorant, for example, inorganic pigment and macrocyclic organic pigment.

[0121] Organic coloring pigments are usually macrocyclic, such as phthalocyanine. The use of copper phthalocyanine or its derivatives is a preferred option. This produces blue products.

[0122] Inorganic colorants of interest include ultramarine blue (eg, CAS No. 57455-37-5) or titanium dioxide.

[0123] It is particularly advantageous if the composition of the present invention includes a macrocyclic organic pigment, especially a macrocyclic organic pigment and an inorganic pigment. When one or both of these pigments are present, the nucleating agents described herein reduce shrinkage anisotropy.

[0124] The color imparted to the article may vary. It is preferred that the color is not white or black.

[0125] Nucleating agent

[0126] The nucleating agent is of formula (I) or (II).

[0127] or R1-XAX-R2 (II)

[0128] in

[0129] A = monocyclic or bicyclic aryl;

[0130] Each X is independently a -CO-NH- group or a -NH-CO- group;

[0131] R1 to R3 are each independently C1-C20 alkyl optionally substituted with one or more hydroxyl groups; C2-C20 alkenyl optionally substituted with one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl groups; or C3-C12 cycloalkyl-C1-6-alkenyl, wherein the C3-C12 cycloalkyl is optionally substituted with one or more C1-C20 alkyl groups.

[0132] In any of the nucleating compounds of the present invention it is preferred if A is naphthyl or phenyl, especially phenyl. The groups are preferably attached via the 1,4 positions on the phenyl ring.

[0133] It is preferred if X is -NH-CO-, so that the carbonyl group is adjacent to Ring A. It is preferred that all X groups are identical. It is preferred that all X groups are attached to Ring A via the carbonyl group.

[0134] R1 to R3 are preferably the same.

[0135] R1 to R3 are preferably independently C1-C10 alkyl; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl; or C3-C12 cycloalkyl-C1-6-alkylene, wherein the C3-12 cycloalkyl is optionally substituted with one or more C1-C20 alkyl. In a C3-C12 cycloalkyl-C1-6-alkylene group, the cycloalkyl ring is connected to X through an alkylene group, for example, cyclohexyl-CH2-X.

[0136] R1 to R3 are preferably independently C1-C6 alkyl; C5-C6 cycloalkyl optionally substituted with one or more C1-C6 alkyl; or C5-C6 cycloalkyl-C1-6-alkenyl. More preferably, R1 to R3 are preferably independently C1-C6 alkyl; C5-C6 cycloalkyl; or C5-C6 cycloalkyl-C1-6-alkylene.

[0137] More preferably, the nucleating agent is of formula (III)

[0138] R1-NH-CO-A-CO-NH-R2 (III)

[0139] in

[0140] A = monocyclic or bicyclic aromatic group, such as phenyl;

[0141] R1 and R2 are each independently C1-C20 alkyl optionally substituted with one or more hydroxyl groups; C2-C20 alkenyl optionally substituted with one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl groups; or C3-C12 cycloalkyl-C1-6-alkenyl, wherein the C3-12 cycloalkyl is optionally substituted with one or more C1-C20 alkenyl groups.

[0142] Even more preferably, the nucleating agent is of Formula IV, wherein the nucleating agent comprises a structure of Formula (IV):

[0143]

[0144] Wherein R1 and R2 include the same or different groups selected from C3-C12 cycloalkyl; C1-C20 alkyl; or C3-C12 cycloalkyl-C1-6-alkenyl.

[0145] Even more preferably, the nucleating agent is of Formula V, wherein the nucleating agent comprises a structure of Formula (V):

[0146]

[0147] wherein R1 and R2 comprise the same group selected from C5-C8 cycloalkyl; C1-C6 alkyl; or C5-C8-cycloalkyl-C1-6-alkenyl.

[0148] It is most preferred if R1 to R3 or R1 to R2 are cyclohexyl.

[0149] Highly preferred nucleating agents are N,N'-dicyclohexyl-2,6-naphthalenedicarboxylic acid amide and N,N'-dicyclohexyl-1,4-phenylenedicarboxylic acid amide.

[0150] Dosage

[0151] The multimodal polyethylene polymer preferably forms at least 90.0 wt % of the composition, such as at least 92.0 wt % of the composition. Most preferably, it forms at least 94.0 wt % of the composition, such as 94.0 to 99.5 wt %. Once all other components are taken into account, the multimodal polyethylene polymer can generally form the balance of the composition.

[0152] The colorant or the color concentrate comprising the colorant preferably forms 0.05 to 5.0 wt.-%, for example 0.1 to 3.0 wt.-% of the composition.

[0153] In one embodiment, the composition comprises 0.1 to 5.0 wt.-% of a colorant or a color concentrate comprising a colorant, such as 0.1 to 4.0 wt.-% of a colorant or a color concentrate comprising a colorant.

[0154] The nucleating agent preferably forms 0.01 to 1.0 wt.%, preferably 0.05 to 0.5 wt.%, in particular 0.05 to 0.25 wt.% of the composition.

[0155] Therefore, in another aspect, the present invention relates to a polyethylene composition comprising

[0156] a) at least 89.0 wt.% multimodal polyethylene polymer;

[0157] b) optionally 0.01 to 10.0 wt.-% of a masterbatch containing a colorant, preferably 0.5 to 5.0 wt. %;

[0158] c) 0.01 to 1.0 wt.-% of a nucleating agent of formula (I)

[0159]

[0160] or 0.01 to 1.0 wt.-% of a nucleating agent of formula (II)

[0161] R1-XAX-R2 (II)

[0162] in

[0163] A = monocyclic or bicyclic aryl;

[0164] Each X is independently a -CO-NH- group or a -NH-CO- group;

[0165] R1 to R3 are each independently C1-C20 alkyl optionally substituted with one or more hydroxyl groups; C2-C20 alkenyl optionally substituted with one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl groups; or C3-C12 cycloalkyl-C1-6-alkenyl, wherein the C3-C12 cycloalkyl is optionally substituted with one or more C1-C20 alkyl groups.

[0166] The polyethylene composition of the present invention may include

[0167] a) at least 94.0 wt.% multimodal polyethylene polymer;

[0168] b) 0.05 to 5.0 wt.-% of a colorant or a masterbatch containing a colorant;

[0169] c) 0.01 to 1.0 wt.-% of said nucleating agent of formula (I) or (II).

[0170] The polyethylene composition of the present invention may include

[0171] a) at least 98.0 wt.%, e.g., 99 wt.% or more, of a multimodal polyethylene polymer;

[0172] b) 0.01 to 1.0 wt.% of the nucleating agent of formula (I) or (II).

[0173] Any composition of the present invention may be composed of the listed components.

[0174] In another aspect of the present invention, it is directed to a nucleating composition suitable for combination with the multimodal polyethylene polymer described herein, the nucleating composition comprising:

[0175] (I) 5.0-50.0 wt.-% of macrocyclic organic pigments; and

[0176] (II) 1.0-50.0 wt.-% of a nucleating agent comprising a compound of formula (I) or (II)

[0177] or R1-XAX-R2 (TI)

[0178] in

[0179] A = monocyclic or bicyclic aryl;

[0180] Each X is independently a -CO-NH- group or -NH-CO-;

[0181] R1 to R3 are each independently C1-C20 alkyl optionally substituted with one or more hydroxyl groups; C2-C20 alkenyl optionally substituted with one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl groups; or C3-C12 cycloalkyl-C1-6-alkenyl, wherein the C3-C12 cycloalkyl is optionally substituted with one or more C1-C20 alkyl groups.

[0182] From another aspect, the present invention provides a composition comprising

[0183] (I) 50.0-99.0 wt.-% of a color masterbatch containing a macrocyclic organic pigment; and

[0184] (II) 1.0-50 wt.-% of a nucleating agent comprising a compound of formula (I) or (II)

[0185] or R1-XAX-R2 (II)

[0186] in

[0187] A = monocyclic or bicyclic aryl;

[0188] Each X is independently a -CO-NH- group or -NH-CO-;

[0189] R1 to R3 are each independently C1-C20 alkyl optionally substituted by one or more hydroxyl groups; C2-C20 alkenyl optionally substituted by one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted by one or more C1-C20 alkyl groups; C3-C12 cycloalkyl-C1-6-alkenyl.

[0190] In a preferred embodiment, the composition comprises

[0191] (I) 85.0-99.0 wt.-% of a color masterbatch containing a macrocyclic organic pigment; and

[0192] (II) 1.0-15.0 wt.-% of a nucleating agent.

[0193] When producing the composition of the invention, preferably a compounding step is applied, wherein the composition of the invention is extruded in an extruder and then pelletized into polymer particles in a manner known in the art.

[0194] The polyethylene composition, for example in granular form, may also contain small amounts of other additives such as antistatic agents, fillers, antioxidants, etc., typically in an amount of up to 5% by weight.

[0195] Optionally, additives or other polymer components may be added to the composition in the compounding step in the amounts described above. Preferably, the composition of the present invention obtained from the reactor is compounded together with the additives in an extruder in a manner known in the art.

[0196] The multimodal polyethylene polymers may also be combined with other polymer components such as other HDPE or with other polymers such as LLDPE or LDPE.

[0197] However, articles of the present invention, such as caps and closures, are preferably at least 89.0 wt% multimodal polyethylene polymer.

[0198] application

[0199] Still further, the present invention relates to an injection- or compression-molded article, preferably a cap or closure, comprising the polyethylene composition, and to the use of the polyethylene composition in producing an injection- or compression-molded article, preferably a cap or closure. Preferably, the injection-molded article is prepared. The present invention is well suited for producing caps for containers, such as bottles.

[0200] Therefore, the cap of the present invention is very suitable for bottles containing carbonated or non-carbonated beverages.

[0201] Injection molding of the composition described above can be carried out using any conventional injection molding equipment. A typical injection molding process can be carried out at a temperature of 190 to 275°C.

[0202] Furthermore, the present invention relates to a compression-molded article, preferably a cap or closure article, comprising the above-mentioned polyethylene polymer, and the use of the polyethylene polymer in producing a compression-molded article, preferably a cap or closure.

[0203] Preferably, the composition of the invention is used for producing caps or closures.

[0204] The caps or closures of the present invention are of conventional size and are therefore designed for bottles and the like. They have an outer diameter of approximately 2 to 8 cm (measured across the solid top of the cap), depending on the bottle, and are fitted with a screw. The height of the cap may be 0.8 to 3 cm.

[0205] The lid or closure may be provided with a tear strip from which the lid can be separated when first opened, as is well known in the art. The lid may also be provided with a liner.

[0206] It will be understood that any of the parameters mentioned above are measured according to the detailed tests given below. In any parameter for which narrower and broader embodiments are disclosed, these embodiments are disclosed together with the narrower and broader embodiments of the other parameters.

[0207] The invention will now be described with reference to the following non-limiting examples and figures. BRIEF DESCRIPTION OF THE DRAWINGS

[0208] Figure 1 A cap without the apex is shown (IE3). Figure 2 Shows the presence of a high cusp (CE5).

[0209] Test method:

[0210] Melt flow rate

[0211] Melt flow rate (MFR) is determined according to ISO 1133 and is expressed in g / 10 min. MFR is an indicator of the viscosity of a polymer melt. MFR is measured at 190°C. The load under which the melt flow rate is measured is usually indicated by a subscript, e.g. MFR2 is measured under a load of 2.16 kg (Condition D), MFR5 is measured under a load of 5 kg (Condition T), and MFR 21 It was measured under a load of 21.6 kg (condition G).

[0212] The quantity FRR (Flow Rate Ratio) is an indicator of molecular weight distribution and represents the flow rate ratio under different loads. 21 / 2 Indicates MFR 21 / MFR2 value.

[0213] density

[0214] The density of the polymer is measured according to ISO 1183 / 1872-2B.

[0215] For the purposes of this invention, the density of a mixture can be calculated from the densities of the individual components.

[0216]

[0217] where ρ b is the density of the mixture,

[0218] w i is the weight fraction of ingredient "i" in the mixture, and

[0219] p i is the density of component “i”.

[0220] Molecular weight

[0221] Molecular weight average, molecular weight distribution (Mn, Mw, Mz, MWD)

[0222] The molecular weight averages (Mz, Mw and Mn), molecular weight distribution (MWD) and their breadth are determined by gel permeation chromatography (GPC) according to ISO 16014-1:2003, ISO 16014-2:2003, ISO 16014-4:2003 and ASTM D 6474-12 and are described as Mw / Mn (where Mn is the number average molecular weight and Mw is the weight average molecular weight) using the following formula:

[0223]

[0224]

[0225]

[0226] for a constant elution volume interval ΔVi, where Ai and Mi are the chromatographic peak slice area associated with the elution volume Vi and the polyolefin molecular weight (MW), respectively, and where N equals the number of data points between the integration limits obtained from the chromatogram.

[0227] A high-temperature GPC instrument was used, equipped with an infrared (IR) detector (IR4 or IR5 from PolymerChar (Valencia, Spain)) or an Agilent Technologies differential refractometer (RI), equipped with three Agilent-PLgel Olexis and one Agilent-PLgel Olexis Guard columns. 1,2,4-Trichlorobenzene (TCB) stabilized with 250 mg / L of 2,6-di-tert-butyl-4-methylphenol was used as the solvent and mobile phase. The chromatographic system was operated at 160°C and a constant flow rate of 1 mL / min. 200 μL of sample solution was injected for each analysis. Data were collected using Agilent Cirrus version 3.3 software or PolymerChar GPC-IR control software.

[0228] The column set was calibrated using universal calibration (according to ISO 16014-2:2003) with 19 narrow molecular weight polystyrene (PS) standards ranging from 0.5 kg / mol to 11,500 kg / mol. The PS standards were dissolved at room temperature for several hours. The conversion of polystyrene peak molecular weight to polyolefin molecular weight was accomplished using the Mark Houwink equation and the following Mark Houwink constant:

[0229] K PS =19x10 -3 mL / g, α PS =0.655

[0230] K PE =39x10-3 mL / g, α PE =0.725

[0231] K PP =19x10 -3 mL / g, α PP =0.725

[0232] A third-order polynomial fit was used to fit the calibration data.

[0233] All samples were prepared in the concentration range of 0,5-1 mg / ml and incubated at 160°C with continuous gentle shaking for 2.5 hours to dissolve PP or 3 hours to dissolve PE.

[0234] Quantification of microstructure by NMR spectroscopy

[0235] Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers.

[0236] The molten state was analyzed using a Brucker Advance III 500 NMR spectrometer. 1 H and 13 C were operated at 500.13 and 125.76 MHz, respectively, and quantitative 13 C{ 1 H}NMR spectra. All spectra were taken at 150℃ 13C was recorded using an optimized 7 mm magic angle spinning (MAS) probe head, with nitrogen used for all pneumatics. Approximately 200 mg of material was loaded into a 7 mm outer diameter zirconia MAS rotor, which was spun at 4 kHz. Standard single-pulse excitation was used with transient NOEs with a short recycle delay of 3 s (see Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, H.W., Wilhelm, M., Macromol. Chem. Phys. 2006; 207: 382., and Pollard, M., Klimke, K., Graf, R., Spiess, H.W., Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37: 813), and the RS-HEPT decoupling scheme (see Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239 and Griffin, J. M., Tripon, C., Samoson, A., Filip, C., and Brown, SP, Mag. Res. in Chem. 200745, S1, S198).

[0237] A total of 1024 (1k) transients were acquired for each spectrum. This setting was chosen due to its high sensitivity to low comonomer contents.

[0238] Quantitative 13 C{ 1 H} NMR spectra were processed, integrated, and quantitative attributes determined using a custom spectral analysis automation program. All chemical shifts were internally referenced to the bulk methylene signal (δ+) at 30.00 ppm (see J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.)

[0239] A characteristic signal corresponding to the incorporation of 1-butene was observed (randal 1189) and all contents were calculated relative to all other monomers present in the polymer.

[0240] A characteristic signal is observed for the incorporation of isolated 1-butene, the EEBEE comonomer sequence. The incorporation of isolated 1-butene is quantified using the integral of the signal at 39.84 ppm assigned to the *B2 site, combined with the reported number of sites for each comonomer:

[0241] B=I *B2

[0242] In the absence of other signals indicating other comonomer sequences, i.e., continuous comonomer addition, the total 1-butene monomer content is calculated based solely on the amount of isolated 1-butene sequences:

[0243] B total = B

[0244] The relative amount of ethylene was quantified by integrating the bulk methylene (δ+) signal at 30.00 ppm:

[0245] E=(1 / 2)*I δ+

[0246] The total ethylene monomer content is calculated based on the abundance of methylene signals combined with the presence of ethylene units in other observed comonomer sequences or terminal groups:

[0247] E 总 =E+(5 / 2)*B

[0248] The total mole fraction of 1-butene in the polymer was then calculated as:

[0249] fB=(B 总 / (E 总 +B 总 )

[0250] The total comonomer incorporation of 1-butene in mole percent was calculated from the mole fractions in the usual manner.

[0251] B [mol%] = 100 * fB

[0252] The total monomer charge of 1-butene in weight percent was calculated from the mole fractions in the standard manner:

[0253] B[wt%]=100*(fB*56.11) / ((fB*56.11)+(fH*84.16)+((1-(fB+fH)))*28.05))

[0254] Example 1

[0255] Injection molding experiments The process was carried out at the Institute for Polymer Processing in Leoben using an all-electric Arburg Allrounder 470A 1000-400 with a screw diameter of 25 mm and a maximum clamping force of 1000 kN. To achieve similar molding conditions to the cap, a component with a similar wall thickness and simple geometry was required to facilitate dimensional measurement. For this purpose, an existing mold from the Institute for Polymer Processing was used. It was a flat plate with dimensions of 75 × 25 × 1.1 mm. 3(length × width × thickness). The following materials were used:

[0256] MB7541 is a multimodal HDPE with a density of 954 kg / m 3 , MFR2 is 4g / 10min.

[0257] MB5568 is a multimodal HDPE with a density of 956 kg / m 3 , MFR2 is 0.8g / 10min.

[0258] FLYADD-B1 (CAS 15088-29-6), also known as TMB-5, is a soluble nucleating agent. It is N,N'-dicyclohexyl-1,4-phenylenedicarboxamide.

[0259] CMB1 (Remafin Blue PE53421301ZN) is a blue masterbatch. The blue pigment in this masterbatch is identified as Ultramarine Blue (PB29).

[0260] CMB2 (Remafin Blue PL14502310916) is a blue masterbatch. The blue pigments in this masterbatch are identified as Ultramarine Blue (PB29) and Phthalocyanine Blue (PB15).

[0261] unit CE1 CE2 CE3 IE1 IE2 MB7541 w％ 100 98 98.5 97.9 98.4 CMB1 w％ 2 2 CMB2 w％ 1.5 1.5 FLYADD-B1 w％ 0.1 0.1 Shrinkage MD ％ 2.40 2.07 2.41 2.87 2.67 std.dev.MD ％ 0.01 0.02 0.02 0.02 0.02 Shrinkage TD ％ 1.27 1.23 0.56 0.77 0.74 std.dev.TD ％ 0.01 0.05 0.03 0.02 0.02 Anisotropy coefficient 1.89 1.68 4.30 3.73 3.61

[0262] The shrinkage of the injection molded plaque specimens was measured in the flow (MD=machine direction) and cross-flow direction (TD=transverse direction), and the anisotropy coefficient was calculated (anisotropy coefficient=shrinkage MD / shrinkage TD).

[0263] Multimodal polyethylene polymer alone exhibits low shrinkage anisotropy (CE1). However, when CMBs are added, a different effect occurs. The presence of CMB1, which contains only inorganic pigments, shows slight anisotropy, while the presence of CMB2, which contains both inorganic and organic pigments, significantly increases anisotropy.

[0264] When FLYADD-B1 is added, the resulting anisotropy is normalized to a consistent value. Whether using CMB1 or CMB2, the resulting anisotropy is predictable. Having predictable, and therefore normalized, shrinkage is valuable to those working in this field. Furthermore, the presence of the nucleating agent appears to reduce anisotropy in compositions containing organic pigments.

[0265] Example 2

[0266] Cycle time reduction for injection molding caps with blue MB5568 in the presence of FLYADD-B1

[0267] equipment

[0268] The tests were carried out on an "Engel Speed ​​180 / 45" injection moulding machine with a 12-cavity lid mould (28 mm PCO1881, carbonated soft drinks, for HDPE).

[0269] Material

[0270] MB5568 was used as the base resin. The blue color masterbatch (CMB) was CMB2. A compound of MB5568 and FLYADD-B1 was prepared using a twin-screw extruder. The blue compound was prepared by dry-blending the base resin and the blue CMB prior to injection molding.

[0271] result

[0272] unit CE4 IE3 CE5 IE4 MB5568 w％ 100 99.9 98.5 98.4 CMB2 w％ 1.5 1.5 FLYADD-B1 w％ 0.1 0.1 Cycle @ 200℃ S 3.7 3.59 nd nd Cycle @ 220℃ S 3.86 3.56 4.44 3.93 Cycle @ 240℃ S 3.65 3.43 4.51 4.12

[0273] In the presence of FLYADD-B1, the periodicity of the natural blue compound can be significantly reduced at different melting temperatures (200, 220, 240°C). No increase in the number of defects (high peaks and angel hairs) was observed in the nucleated compound compared to the nucleated material. Figure 1 A cap without the apex (IE3) is shown. Figure 2 The presence of a high cusp is shown (CE5).

Claims

1. The polyethylene composition comprises a) at least 89.0 wt.% multimodal polyethylene polymer; b) 0.01 to 10.0 wt.% of a colorant or a masterbatch containing a colorant; c) 0.01 to 1.0 wt.-% of a nucleating agent of formula (I) or 0.01 to 1.0 wt.% of a nucleating agent of formula (II) R1-XAX-R2(II) in A = monocyclic or bicyclic aryl; Each X is independently a -CO-NH- group or a -NH-CO- group; R1 to R3 are each independently C1-C20 alkyl optionally substituted with one or more hydroxyl groups; C2-C20 alkenyl optionally substituted with one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl groups; or C3-C12 cycloalkyl-C1-6-alkenyl, wherein the C3-C12 cycloalkyl is optionally substituted with one or more C1-C20 alkyl groups.

2. The polyethylene composition according to claim 1, wherein The nucleating agent is of formula (III) R1-NH-CO-A-CO-NH-R2(III) in A = monocyclic or bicyclic aryl; R1 and R2 are each independently C1-C20 alkyl optionally substituted with one or more hydroxyl groups; C2-C20 alkenyl optionally substituted with one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl groups; or C3-C12 cycloalkyl-C1-6-alkenyl, wherein the C3-12 cycloalkyl group is optionally substituted with one or more C1-C20 alkyl groups.

3. The polyethylene composition according to claim 2, wherein The nucleating agent is of formula (IV) Wherein R1 and R2 include the same or different groups selected from C3-C12 cycloalkyl; C1-C20 alkyl; or C3-C12 cycloalkyl-C1-6-alkenyl.

4. The polyethylene composition according to claim 1, wherein R1 to R3 or R1 and R2 are all cyclohexyl groups.

5. The polyethylene composition according to claim 1, wherein The multimodal polyethylene polymer has a density according to ISO 1183 of 0.940-0.980 g / cm 3 within the range.

6. The polyethylene composition according to claim 1, wherein The multimodal polyethylene polymer has a density according to ISO 1183 of 0.945-0.970 g / cm 3 within the range.

7. The polyethylene composition according to claim 1, wherein The multimodal polyethylene polymer has a density according to ISO 1183 of 0.950-0.960 g / cm 3 within the range.

8. The polyethylene composition according to claim 1, wherein MFR of the multimodal polyethylene polymer according to ISO 1133 190 / 2.16 In the range of 0.05 to 20 g / 10 min.

9. The polyethylene composition according to claim 1, wherein The colorant includes a macrocyclic organic pigment or one or more inorganic pigments or a mixture thereof.

10. The polyethylene composition according to claim 1, wherein The pigments include a mixture of ultramarine blue and phthalocyanine.

11. The polyethylene composition according to claim 9, wherein The macrocyclic organic pigment includes phthalocyanine or its derivatives.

12. The polyethylene composition according to claim 9, wherein The macrocyclic organic pigment includes copper phthalocyanine and / or its derivatives.

13. The polyethylene composition according to claim 9, wherein The inorganic pigment is selected from ultramarine blue or titanium dioxide or a combination thereof.

14. The polyethylene composition according to claim 1, wherein The polyethylene polymer is bimodal and / or wherein the polyethylene polymer has a molecular weight distribution Mw / Mn in the range of 5-50 as measured by GPC.

15. The polyethylene composition according to claim 1, wherein The polyethylene polymer is bimodal and / or wherein the polyethylene polymer has a molecular weight distribution Mw / Mn in the range of 10-30 as measured by GPC.

16. The polyethylene composition according to claim 1, comprising d) at least 94.0 wt.% multimodal polyethylene polymer; e) 0.05 to 5.0 wt.% of a colorant or a masterbatch containing a colorant; f) 0.01 to 1.0 wt.% of the nucleating agent.

17. A nucleating composition comprising 50.0-99.0wt.% of a masterbatch containing a macrocyclic organic pigment and 1.0-50.0 wt.% of a nucleating agent of formula (I) or 1.0-50.0wt.% of a nucleating agent of formula (II) R1-XAX-R2(II) in A = monocyclic or bicyclic aryl; Each X is independently a -CO-NH- group or -NH-CO-; R1 to R3 are each independently C1-C20 alkyl optionally substituted with one or more hydroxyl groups; C2-C20 alkenyl optionally substituted with one or more hydroxyl groups; C2-C20 alkyl interrupted by oxygen or sulfur; C3-C12 cycloalkyl optionally substituted with one or more C1-C20 alkyl groups; or C3-C12 cycloalkyl-C1-6-alkenyl, wherein the C3-C12 cycloalkyl is optionally substituted with one or more C1-C20 alkyl groups.

18. Use of a nucleating composition according to claim 17 for reducing shrinkage anisotropy and / or warpage in injection or compression moulded articles.

19. Use of the composition according to claim 1 for reducing shrinkage anisotropy and / or warpage in injection or compression molded articles.

20. An article comprising the polyethylene composition of claim 1.

21. The article according to claim 20, wherein the article is an injection molded or compression molded article.

22. The article of claim 20, wherein the article is a cap or a closure.

23. Use of the composition according to claim 1 for reducing spiky and / or angel hair in injection or compression moulded caps.

24. Use of the composition according to claim 1 for reducing cycle time in the manufacture of injection or compression moulded caps.

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