Hinge component having improved ESCR performance

Abstract

The invention relates to a hinge component comprising at least 90.0 wt.% of a polyethylene composition with regard to the total weight of the hinge component, wherein the polyethylene composition comprises or consists of an ethylene copolymer, and wherein the polyethylene composition has preferably a molecular weight distribution of < 10.0 and wherein the polyethylene composition has: (a) a density of ≥ 940 and ≤ 955 kg / m3; and (b) a melt flow rate (MFR) of ≥ 2.0 and < 10.0 g / 10min; and (c) a weight average molecular weight (Mw) of ≥ 70.0 kg / mol and < 100 kg / mol; The invention further relates to an article comprising such a hinge component.

Description

24POLY0040-WO-ORD1HINGE COMPONENT HAVING IMPROVED ESCR PERFORMANCEFIELD OF INVENTION

[0001] The invention relates to a hinge component comprising a polyethylene composition, and to articles comprising such a hinge component. The invention further relates to a process of producing such a hinge component. In addition, the invention further relates to the use of such a hinge component for improving the Environmental Stress Cracking Resistance (ESCR) of a cap closure for a container.BACKGROUND

[0002] In various consumer products such as bottles and containers, hinges used in caps and closures play an important role in packaging. A living hinge is one such form of a hinge, which is a thin, flexible hinge connecting two relatively rigid parts. Living hinges are usually made from the same material as the rigid parts and is typically used to join rigid parts of a container, allowing them to bend along the line of the hinge.

[0003] A commonly used material for making a hinge is polypropylene. Polypropylene as a material has suitable hinge strength, fatigue performance, good environmental stress crack resistance (ESCR) performance, low cost of manufacturing and excellent processability. However, since bottles or tubes for cosmetic / personal care applications are often made of polyethylene, the difference in material properties between polyethylene and polypropylene polymers, may adversely affect the mechanical performance of the polyethylene recyclates. Therefore, from a sustainability point of view, it is required to have a mono-material packaging where the bottle and tube is of the same material as that of the hinge or the cap for better recyclability.

[0004] In addition, for any viable commercial use of a hinge, the hinge needs to have desirable hinge strength, good environmental stress crack resistance (ESCR) while having the desired processability. In the past several bimodal or trimodal polyethylene compositions have been used for improving both hinge strength and environmental stress crack resistance (ESCR) of a hinge component. However, production of bimodal and trimodal polymer compositions often involve the use of series of reactors, which in certain circumstances add to processing complexity and enhanced capital and operating expenses.

[0005] In addition, attempts have been made to improve such performance. These include the incorporation of C4, Ce, and / or Cs comonomers used during polymerization, which may be24POLYOQ40-WO-ORD2 carried out in the vapor phase or in solution. Fine-tuning the molecular weight distribution (bi- or multi-modal) has also been used, as well as blending the polyethylene with other polymers. Crosslinking of silane grafting of polyethylene has also been used.

[0006] Given the growing trend of down-gauging of the plastic parts (for example, caps and closure, bottles and containers) and the use of plastic containers for storing aggressive chemicals (bleach bottles), an enhanced ESCR performance of plastics becomes more vital. For instance, a weight reduction of bottle caps from 3 g to 1.8-2.0 g, as currently demanded by many brand-owners, while still keeping its ESCR performance, is an emerging challenge.

[0007] While various methods exist to increase ESCR properties of polyethylene, many of these suffer in that they are cost prohibitive or applicable only to the method of making the starting polyethylene materials instead of to existing polyethylene materials.

[0008] In the past published patents such as WO2017 / 221124and W02021 / 250520 describe hinge components and molded articles. Although the solutions described in patents are promising, there remains a need to provide hinge components with further improved hinge strength and environmental stress crack resistance (ESCR) from resins that are easily processible.

[0009] Accordingly, it is an objective of the present invention to provide for a hinge component that has a balance of hinge strength and environmental stress crack resistance (ESCR) while being prepared from a polyethylene composition having desired processability.DESCRIPTION

[0010] Accordingly, one or more objectives of the hinge component comprising at least 90.0 wt.% of a polyethylene composition with regard to the total weight of the hinge component, wherein the polyethylene composition comprises or consists of an ethylene copolymer, and wherein the polyethylene composition has:(a) a density of > 940 and < 955 kg / m3, preferably > 940 and < 950 kg / m3, preferably > 942 and < 950 kg / m3, preferably > 942 and < 949 kg / m3, preferably > 942 and < 948 kg / m3, preferably of > 945 and < 953 kg / m3, preferably of > 945 and < 950 kg / m3, determined in accordance with ISO 1183-1 A; and24POLY0040-WO-ORD3(b) a melt flow rate (MFR) of > 2.0 and < 10.0 g / lOmin, preferably > 4.0 and < 9.5 g / lOmin, preferably > 6.0 and < 9.5 g / lOmin, preferably > 3.0 and < 5.0 g / lOmin, as determined in accordance with ISO 1133 at a load of 2.16 kg and at a temperature of 190 °C; and(c) a weight average molecular weight (Mw) of > 70.0 kg / mol and < 100 kg / mol, preferably > 80 kg / mol and < 100 kg / mol, preferably > 75.0 kg / mol and < 92.0 kg / mol, preferably > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol, determined in accordance with ASTM D 6474-12; and• wherein the polyethylene composition comprises > 95.0 wt.%, preferably > 98.0 wt.%, preferably > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition; and• wherein the polyethylene composition has a unimodal molecular weight distribution; and• wherein the ethylene copolymer comprises or consists of > 95.0 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 5.0 wt.%, preferably > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from alpha olefin comonomer having six to eight carbon atoms, preferably six carbon atoms, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy; and• preferably wherein the polyethylene composition has a molecular weight distribution (MWD) of > 0 and < 10.0, preferably > 1.0 and < 10.0, preferably > 3.0 and < 7.0, preferably > 4.0 and < 7.0, preferably > 4.0 and < 6.0, wherein molecular weight distribution is defined as the ratio of the weight average molecular weight to number average molecular weight, determined in accordance with ASTM D 6474-12.

[0011] Preferably, the hinge component comprises at least 90.0 wt.% of a polyethylene composition with regard to the total weight of the hinge component, wherein the polyethylene composition comprises or consists of an ethylene copolymer, and wherein the polyethylene composition has:24POLY0040-WO-ORD4(a) a density of > 942 and < 950 kg / m3, preferably > 942 and < 949 kg / m3, preferably> 942 and < 948 kg / m3, determined in accordance with ISO 1183-1 A; and(b) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, preferably > 3.0 and < 5.0 g / lOmin, as determined in accordance with ISO 1133 at a load of 2.16 kg and at a temperature of 190 °C; and(c) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol, preferably > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol, determined in accordance with ASTM D 6474-12; and• wherein the polyethylene composition comprises > 95.0 wt.%, preferably > 98.0 wt.%, preferably > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition; and• wherein the polyethylene composition has a unimodal molecular weight distribution; and• wherein the ethylene copolymer comprises or consists of > 95.0 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 5.0 wt.%, preferably > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from alpha olefin comonomer having six carbon atoms, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy; and• wherein the polyethylene composition has a molecular weight distribution (MWD) of > 3.0 and < 7.0, preferably > 4.0 and < 7.0, preferably > 4.0 and < 6.0, wherein molecular weight distribution is defined as the ratio of the weight average molecular weight to number average molecular weight, determined in accordance with ASTM D 6474-12.

[0012] Preferably, the hinge component comprises at least 90.0 wt.% of a polyethylene composition with regard to the total weight of the hinge component, wherein the polyethylene composition comprises or consists of an ethylene copolymer, and wherein the polyethylene composition has:(a) a density of > 942 and < 949 kg / m3, preferably > 942 and < 948 kg / m3, determined in accordance with ISO 1183-1 A; and24POLYOQ40-WO-ORD5(b) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, preferably > 3.0 and < 5.0 g / lOmin, as determined in accordance with ISO 1133 at a load of 2.16 kg and at a temperature of 190 °C; and(c) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol, preferably > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol, determined in accordance with ASTM D 6474-12; and• wherein the polyethylene composition comprises > 95.0 wt.%, preferably > 98.0 wt.%, preferably > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition; and• wherein the polyethylene composition has a unimodal molecular weight distribution; and• wherein the ethylene copolymer comprises or consists of > 95.0 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 5.0 wt.%, preferably > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from alpha olefin comonomer having six carbon atoms, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy; and• wherein the polyethylene composition has a molecular weight distribution (MWD) of > 3.0 and < 7.0, preferably > 4.0 and < 7.0, preferably > 4.0 and < 6.0, wherein molecular weight distribution is defined as the ratio of the weight average molecular weight to number average molecular weight, determined in accordance with ASTM D 6474-12.

[0013] Preferably the hinge component has at least 90.0 wt.% of a polyethylene composition with regard to the total weight of the hinge component, wherein the polyethylene composition comprises or consists of an ethylene copolymer, and wherein the polyethylene composition has:(a) a density of > 942 and < 949 kg / m3, preferably > 942 and < 948 kg / m3, determined in accordance with ISO 1183-1 A; and(b) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, as determined in accordance with ISO 1133 at a load of 2.16 kg and at a temperature of 190 °C; and24POLY0040-WO-ORD6(c) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol, preferably > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol, determined in accordance with ASTM D 6474-12; and• wherein the polyethylene composition comprises > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition; and• wherein the polyethylene composition has a unimodal molecular weight distribution; and• wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from alpha olefin comonomer having six carbon atoms, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy; and• wherein the polyethylene composition has a molecular weight distribution (MWD) of > 4.0 and < 7.0, preferably > 4.0 and < 6.0, wherein molecular weight distribution is defined as the ratio of the weight average molecular weight to number average molecular weight, determined in accordance with ASTM D 6474-12.

[0014] Preferably the hinge component has at least 90.0 wt.% of a polyethylene composition with regard to the total weight of the hinge component, wherein the polyethylene composition comprises or consists of an ethylene copolymer, and wherein the polyethylene composition has:(a) a density of > 942 and < 949 kg / m3, preferably > 942 and < 948 kg / m3, determined in accordance with ISO 1183-1 A; and(b) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, as determined in accordance with ISO 1133 at a load of 2.16 kg and at a temperature of 190 °C; and(c) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol, preferably > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol, determined in accordance with ASTM D 6474-12; and• wherein the polyethylene composition comprises > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition; and• wherein the polyethylene composition has a unimodal molecular weight distribution; and24POLY0040-WO-ORD7• wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from alpha olefin comonomer having six carbon atoms, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy; and• wherein the polyethylene composition has a molecular weight distribution (MWD) of > 4.0 and < 7.0, preferably > 4.0 and < 6.0, wherein molecular weight distribution is defined as the ratio of the weight average molecular weight to number average molecular weight, determined in accordance with ASTM D 6474-12.

[0015] Preferably, the polyethylene composition has a Z-average molecular weight (Mz) of > 450 and < 580 kg / mol, preferably > 500 and < 580 kg / mol, as determined in accordance with ASTM D6474-12 using size exclusion chromatography.

[0016] For example, the hinge component has at least 90.0 wt.% of a polyethylene composition with regard to the total weight of the hinge component, wherein the polyethylene composition comprises or consists of an ethylene copolymer, and wherein the polyethylene composition has:(a) a density of > 942 and < 949 kg / m3, preferably > 942 and < 948 kg / m3, determined in accordance with ISO 1183-1 A; and(b) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, as determined in accordance with ISO 1133 at a load of 2.16 kg and at a temperature of 190 °C; and(c) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol, preferably > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol, determined in accordance with ASTM D 6474-12; and(d) a Z-average molecular weight (Mz) of > 450 and < 580 kg / mol, preferably > 500 and < 580 kg / mol, as determined in accordance with ASTM D6474-12 using size exclusion chromatography; and• wherein the polyethylene composition comprises > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition; and24POLY0040-WO-ORD8• wherein the polyethylene composition has a unimodal molecular weight distribution; and• wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from alpha olefin comonomer having six carbon atoms, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy; and• wherein the polyethylene composition has a molecular weight distribution (MWD) of > 4.0 and < 7.0, preferably > 4.0 and < 6.0, wherein molecular weight distribution is defined as the ratio of the weight average molecular weight to number average molecular weight, determined in accordance with ASTM D 6474-12.

[0017] Preferably the hinge component has at least 90.0 wt.% of a polyethylene composition with regard to the total weight of the hinge component, wherein the polyethylene composition comprises or consists of an ethylene copolymer, and wherein the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3, determined in accordance with ISO 1183-1 A;(b) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, as determined in accordance with ISO 1133 at a load of 2.16 kg and at a temperature of 190 °C; and(c) a weight average molecular weight (Mw) of > 87.0 kg / mol and < 95.0 kg / mol, determined in accordance with ASTM D 6474-12; and(d) a Z-average molecular weight (Mz) of > 500 and < 580 kg / mol, as determined in accordance with ASTM D6474-12 using size exclusion chromatography; and• wherein the polyethylene composition comprises > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition; and• wherein the polyethylene composition has a unimodal molecular weight distribution; and• wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from alpha olefin comonomer having six carbon atoms, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy; and24POLY0040-WO-ORD9• wherein the polyethylene composition has a molecular weight distribution (MWD) of > 4.0 and < 7.0, preferably > 4.0 and < 6.0, wherein molecular weight distribution is defined as the ratio of the weight average molecular weight to number average molecular weight, determined in accordance with ASTM D 6474-12.

[0018] It is particularly preferred that the polyethylene composition has a molecular weight distribution (MWD) of > 4.0 and < 7.0, preferably > 4.0 and < 6.0, where molecular weight distribution is defined as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), determined in accordance with ASTM D 6474-12.

[0019] Advantageously, the hinge component of the present invention has excellent environmental stress crack resistance (ESCR) and hinge strength. As a further advantage, the polyethylene composition has a unimodal molecular weight distribution i.e a polyethylene polymer produced without the need of using multiple reactors or by blending of two or more polymers.

[0020] Accordingly, in an aspect of the invention, the invention relates to the use of the hinge component of the present invention, for improving the Environmental Stress Cracking Resistance (ESCR) of a cap closure for a living hinge cap closure. Such a hinge component may be used in an article. For example, such an article comprising the hinge component of the present invention, is a living hinge cap closure. The living hinge cap closure may be part of a container such as a beverage bottle, a pouch and other consumer articles. Further from the present invention a skilled person will be guided to select a polyethylene composition having a suitable combination of density, molecular weight, melt flow rate and molecular weight distribution to achieve the technical effect envisaged to address the objectives of the present invention.

[0021] The term “hinge” means a mechanical bearing that connects two rigid objects, typically allowing only a limited angle of rotation between them. Two rigid objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation, with all other translations or rotations prevented; thus a hinge has one degree of freedom. The term “living hinge” or “integral hinge” is a thin flexible hinge (flexure bearing) made from the same material as the two rigid pieces it connects.

[0022] The hinge component comprises at least or > 90.0 wt.% of a polyethylene composition, preferably > 95.0 wt.% and wt.% and < 100 wt.%, preferably > 98.5 wt.% and < 10024POLY0040-WO-ORD10 wt.% with regard to the total weight of the hinge component; and > 0.0 wt.% and wt.% and < 5.0 wt.%, preferably > 0 and < 1.5 wt.% of stabilizers and additives selected from UV stabilisers, antioxidants and acid scavengers. In some aspects of the present invention, the hinge component has 100.0 wt.% of a polyethylene composition with regard to the total weight of the hinge component.

[0023] Preferably, the polyethylene composition comprises > 95.0 wt.%, preferably > 98.0 wt.%, preferably > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition. Preferably, the polyethylene composition comprises > 0.0 wt.% and < 5.0 wt.%, preferably > 0.0 wt.% and < 2.0 wt.%, preferably > 0.0 wt.% and < 2.0 wt.% of additives, with regard to the total weight of the polyethylene composition.

[0024] Preferably in some embodiments of the invention, the polyethylene composition comprises 100 wt.% of the of the ethylene copolymer with regard to the total weight of the polyethylene composition.

[0025] The term “unimodal molecular weight distribution” as used herein means that the polyethylene composition is not a result of a reactor blend of two different ethylene polymers having different molecular weight. In other words, the polyethylene composition of the present invention is free of blends of two or more ethylene polymers.

[0026] Furthermore, the polyethylene compositions described herein exhibit unimodal molecular weight distribution, meaning that there often is a single distinguishable peak in a molecular weight distribution curve of the composition (as determined using gel permeation chromatography (GPC) or other recognized analytical technique.

[0027] Examples of “unimodal” molecular weight distribution can be seen in U.S. Patent No. 8,691,715, Figure 6 of such patent. This is in contrast with a “multimodal” molecular weight distribution, which means that there often (not always) is at least two distinguishable peaks in a molecular weight distribution curve (again, as determined by GPC or any other recognized analytical technique, with GPC controlling in the event of any conflict). Such bimodal or multimodal polyethylene compositions made from Ziegler Natta catalyst may have a molecular weight distribution (MWD) of greater than or equal to 10.0.24POLY0040-WO-ORD11Catalyst

[0028] The ethylene copolymer may be prepared by any known catalyst such as a Ziegler Natta catalyst or a Metallocene catalyst or a chromium / chromium oxide-based catalyst. It is particularly preferred that the ethylene copolymer is prepared using a Ziegler natter catalyst.

[0029] Preferably, the polyethylene composition (ethylene copolymer) is prepared in the presence of Ziegler Natta or a metallocene catalyst in a gas phase reactor.

[0030] Preferably, the ethylene copolymer is prepared in the presence of Ziegler Natta catalyst in a gas phase reactor. Preferably, the Ziegler Natta catalyst comprises titanium, magnesium, aluminum, chloride moieties and a cocatalyst, wherein the cocatalyst is an alkyl aluminum compound, such as tri-ethyl-aluminium (TEAL) or tri-isobutyl-aluminium (TIBA).Comonomer content

[0031] The polyethylene composition comprises ethylene copolymer comprising polymeric units derived from ethylene and an alpha olefin comonomer. For example, the ethylene copolymer comprises or consists of > 95.0 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene and > 0.5 wt.% and < 5.0 wt.%, preferably > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from alpha olefin comonomer having six to eight carbon atoms, preferably six carbon atoms, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0032] The inventors surprisingly found that only alpha olefin comonomer having six to eight carbon atoms were suitable to address the objectives of the present invention in contrast to four carbon atom monomers such as 1 -butene.

[0033] Preferably, the alpha olefin comonomer is selected from 4-methyl-l -pentene, 1- hexene and 1 -octene. Preferably wherein the alpha olefin comonomer is 1 -hexene.Combination of (MWD), (Mw), (Mz), Density, Comonomer content

[0034] Preferably, the polyethylene composition:(a) has a molecular weight distribution (MWD) of > 3.0 and < 7.0; and(b) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol; and24POLY0040-WO-ORD12 wherein the ethylene copolymer consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1-hexene, with regard to the total weight of the ethylene copolymer, as determined using13C NMR spectroscopy.

[0035] Preferably, the polyethylene composition has:(a) a density of > 942 and < 950 kg / m3; and(b) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, preferably > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 3.0 and < 7.0; and wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0036] Preferably, the polyethylene composition has:(a) a density of > 942 and < 950 kg / m3; and(b) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, preferably > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 3.0 and < 7.0; and(e) Z-average molecular weight (Mz) of > 500 and < 580 kg / mol; and wherein the ethylene copolymer consists of > 96.5 wt.% and < 99.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1-hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0037] Preferably, the polyethylene composition has:(a) a density of > 942 and < 949 kg / m3; and24POLY0040-WO-ORD13(b) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, preferably > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 3.0 and < 7.0; and wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0038] Preferably, the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3; and(b) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol, preferably > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 7.0, preferably > 4.0 and < 6.0; and wherein the ethylene copolymer consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, as determined using13C NMR spectroscopy.

[0039] Preferably, the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3; and(b) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 7.0; and wherein the ethylene copolymer consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1-hexene,24POLY0040-WO-ORD14 with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0040] Preferably, the polyethylene composition has:(a) a density of > 942 and < 950 kg / m3; and(b) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and wherein the ethylene copolymer consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1-hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0041] Preferably, the polyethylene composition has:(a) a density of > 942 and < 950 kg / m3; and(b) a weight average molecular weight (Mw) of > 80.0 kg / mol and < 100.0 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and wherein the ethylene copolymer consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1-hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0042] Preferably, the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3; and(b) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and24POLY0040-WO-ORD15 wherein the ethylene copolymer consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1-hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0043] Preferably, the polyethylene composition has > 2.0 and < 4.0, of short chain branches per carbon atoms (SCB) / 1000, determined by Fourier Transform Infrared Spectroscopy (FTIR) in accordance with ASTM D6645-01 method and preferably wherein the amount of short chain branching in the polyethylene composition is inversely proportional to the weight average molecular weight of the polyethylene composition.

[0044] Preferably, the polyethylene composition has > 3.0 and < 7.0, preferably > 3.0 and < 5.7 of butyl branches / 1000 carbon atoms, when determined using13C NMR spectroscopy.

[0045] The content of short chain branching and butyl branching is sufficient to impart the desired balance of processability and ESCR properties to the hinge component of the present invention.

[0046] Preferably the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3determined in accordance with ISO 1183-1 A;(b) a melt flow rate (MFR) of > 3.0 and < 5.0 g / lOmin, as determined in accordance with ISO 1133 at a load of 2.16 kg and at a temperature of 190 °C; and(c) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and(e) Z-average molecular weight (Mz) of > 500 and < 580 kg / mol; and• wherein the polyethylene composition comprises > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition; and• wherein the polyethylene composition has a unimodal molecular weight distribution; and• wherein the ethylene copolymer consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived24POLY0040-WO-ORD16 from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using 13C NMR spectroscopy; and• wherein the polyethylene composition has > 3.0 and < 7.0 of butyl branches / 1000 carbon atoms, when determined using13C NMR spectroscopy; and• wherein the polyethylene composition has > 2.0 and < 4.0, of short chain branches (SCB) / 1000 carbon atoms, determined by Fourier Transform Infrared Spectroscopy (FTIR) in accordance with ASTM D6645-01 method; and preferably wherein the amount of short chain branching in the polyethylene composition is inversely proportional to the weight average molecular weight of the polyethylene composition.Rheology and Viscosity properties

[0047] Yet another suitable indicator for assessing the processability of polymers in the course of manufacturing the hinge component is by assessing the intrinsic viscosity. The polyethylene composition has sufficient viscosity for imparting the necessary processability while also imparting the desired ESCR and hinge strength properties to the hinge component. For example, the polyethylene composition has an intrinsic viscosity of > 0.8 and < 2.0 dl / g, preferably > 0.9 and < 1.5 dl / g, preferably > 1.2 and < 1.5 dl / g, determined in accordance with ISO1628- 1 :2021.

[0048] Preferably the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3; and(b) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and(e) Z-average molecular weight (Mz) of > 500 and < 580 kg / mol; and(f) a short chain branches (SCB) / 1000 carbon atoms of > 2.0 and < 4.0; and(g) a butyl branches / 1000 carbon atoms of > 3.0 and < 7.0; and(h) an intrinsic viscosity of > 1.2 and < 1.5 dl / g; and wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived24POLY0040-WO-ORD17 from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0049] Preferably the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3; and(b) a weight average molecular weight (Mw) of > 87.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and(e) Z-average molecular weight (Mz) of > 500 and < 580 kg / mol; and(f) a short chain branches (SCB) / 1000 carbon atoms of > 2.0 and < 4.0; and(g) a butyl branches / 1000 carbon atoms of > 3.0 and < 7.0; and(h) an intrinsic viscosity of > 1.2 and < 1.5 dl / g; and wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0050] Preferably the polyethylene composition has:(a) a density of > 945 and < 948 kg / m3; and(b) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and(e) Z-average molecular weight (Mz) of > 500 and < 580 kg / mol; and(f) a short chain branches (SCB) / 1000 carbon atoms of > 2.0 and < 4.0; and(g) a butyl branches / 1000 carbon atoms of > 3.0 and < 7.0; and(h) an intrinsic viscosity of > 1.2 and < 1.5 dl / g; and wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.24POLY0040-WO-ORD18

[0051] Preferably the polyethylene composition has:(a) a density of > 942 and < 950 kg / m3; and(b) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and(e) Z-average molecular weight (Mz) of > 500 and < 580 kg / mol; and(f) a short chain branches (SCB) / 1000 carbon atoms of > 2.0 and < 4.0; and(g) a butyl branches / 1000 carbon atoms of > 3.0 and < 7.0; and(h) an intrinsic viscosity of > 1.2 and < 1.5 dl / g; and wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

[0052] Preferably the polyethylene composition has:(a) a density of > 945 and < 948 kg / m3; and(b) a weight average molecular weight (Mw) of > 87.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and(e) Z-average molecular weight (Mz) of > 500 and < 580 kg / mol; and(f) a short chain branches (SCB) / 1000 carbon atoms of > 2.0 and < 4.0; and(g) a butyl branches / 1000 carbon atoms of > 3.0 and < 7.0; and(h) an intrinsic viscosity of > 1.2 and < 1.5 dl / g; and wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.24POLY0040-WO-ORD19

[0053] The polyethylene composition constituting the hinge component has suitable rheology in particularly suitable shear thinning Preferably, the polyethylene composition has a ratio of G’ IOOOO / G’ IOOO > 30.0 and < 40.0, where G’ IOOOO is the storage modulus measured at a loss modulus of 10000 Pa and G’iooo is the storage modulus measured at a loss modulus of 1000 Pa, where storage and loss modulus is measured using Dynamic Mechanical Analysis (DMA) using a 25 mm diameter parallel plate geometry at 190° C. under nitrogen atmosphere in accordance with ISO 6721-10.

[0054] Preferably, the polyethylene composition has:(a) Yield Stress (MPa) of > 20.0 and < 25.0, determined in accordance with ISO 527-1 :2019;(b) Tensile Modulus (MPa) of > 920.0 and < 1080.0, determined in accordance with ISO 527- 1 :2019; and(c) Environmental Stress Crack Resistance (ESCR), F50 of > 20.0 hours, preferably > 23.0 hours, when measured in accordance with ASTM DI 693 Condition B, 10% Igepal.

[0055] In an aspect of the invention, the invention relates to the process of preparing the hinge component, wherein the process comprises the step of injection molding the polyethylene composition to obtain the hinge component.

[0056] For example, the hinge component may be prepared by a process involving injection molding that comprises the steps of:(a) providing the unimodal polyethylene composition; and(b) subjecting the polyethylene composition to an injection molding process under injection molding conditions sufficient to obtain the article; preferably wherein the injection molding conditions comprises:(i) processing temperature of > 200 °C and < 250 °C, preferably > 215 °C and < 230 °C;(ii) a suitable inj ection speed depending on the part geometry, the number of cavities for example present in the molding equipment and the injection molding machine used; and(iii) at a suitable mold temperature of > 10 °C and < 40 °C.

[0057] During injection molding, the injection speed can be made for example at > 30 cm3 / s and < 50 cm3 / s, preferably > 20 cm3 / s and < 60 cm3 / s while the injection pressure can be24POLY0040-WO-ORD20 made for example at a maximum injection pressure of > 100 MPa and < 200 MPa; preferably > 120 MPa and < 180 MPa.

[0058] The present invention will now be further elucidated based on the following nonlimiting examples.

[0059] Purpose - Evaluate the following hinge components prepared from the unimodal polyethylene compositions for their ESCR, hinge strength and processability.

[0060] Material: The following compositions were considered: IE1 and IE2 were unimodal polyethylene samples used for making inventive hinge components while CE1-CE3 were comparative samples.

[0061] The samples IE1, IE2 and CE1 are non-commercial grades of SABIC having the properties as listed in the table below. CE2 was obtained from SABIC and is the grade SABIC® HOPE Ml 053. CE3 obtained from SABIC is SABIC® HOPE CC860V.

[0062] The inventive resins IE1 and IE2 were prepared using a catalyst system comprising a procatalyst UCAT-J-25 (commercially available from Univation Technologies) and a co-catalyst Tri-ethyl-aluminium (TEAL). The polyethylene resins were produced via fluidized bed gas phase polymerization of ethylene. Gas phase processes for the co-polymerization of olefins are well established in the field. These processes typically involve introducing the monomer and comonomer continuously into a gas-fluidized bed, which contains polyolefin particles.

[0063] The reactor was operated at 91-94 °C and 23 bar total pressure. The recycle gas typically contains ethylene as the monomer at a partial pressure as provided below, a comonomer such as 1 -butene (comparative) or 1 -hexene at a Ce / C2-ratio or C4 / C2-ratio as given below and may also include inert components like nitrogen or a chain transfer agent such as hydrogen at a H2 / C2- ratio of 0.340-0.380. The gas concentrations in the recycling loop were kept constant. Monomer losses due to the polymerization reaction were compensated by feeding make-up gas or liquid into the polymerization zone or the recycling loop.

[0064] Catalyst was introduced into the reactor at the rate required to keep the rate of conversion within the operating window of the reactor. The polymer was discharged discontinuously from the reactor through an outlet positioned near the bottom of the reactor, close to the fluidization grid to maintain a constant reactor inventory.24POLY0040-WO-ORD21

[0065] IE1 , IE2 and CE1 were produced using gas phase fluidized bed using the conditions as provided in the table below. The amount of catalyst used was about 35 ppm by weight.Table 1Table 224POLY0040-WO-ORD2224POLY0040-WO-ORD23

[0066] Test Standards and Parameters

[0067] Melt Flow Rate (MFR) - All samples were procured from SABIC. MFR was measured according to ISO 1133 at 190 °C and a load of 2.16 kg.

[0068] Density- Density was measured according to ISO 1183. Specimens were prepared according to ISO17855-2, at a compression molding temperature: 180°C, and at a compression molding cooling rate: 15°C / min.

[0069] Comonomer content - The type and amount of comonomer was measured by 13C NMR on a Bruker Avance 500 spectrometer equipped with a cryogenically cooled probe head operating at 125°C, whereby the samples were dissolved at 130°C in C2D2C14 containing DBPC as stabilizer.

[0070] Molecular Wei ht - Mw (weight average molecular weight), Mn (number average molecular weight) and Mz (z-average molecular weight) were measured in accordance with ASTM D6474-12. Mn, Mw, and Mz(g / mol) were determined by high temperature Gel Permeation Chromatography (GPC) with differential refractive index (DRI) detection using universal calibration. GPC data was obtained using an instrument sold under the trade name “Waters 150c”, with 1 ,2,4- trichlorobenzene as the mobile phase at 140°C. The samples were prepared by dissolving the polymer in this solvent and were run without filtration. Molecular weights were expressed as polyethylene equivalents with a relative standard deviation of 2.9% for the number average molecular weight (“Mn”) and 5.0% for the weight average molecular weight (“Mw”). The molecular weight distribution (MWD) is the weight average molecular weight divided by the number average molecular weight, Mw / Mn. The z-average molecular weight distribution is Mz / Mn. Polymer sample solutions (1 to 2 mg / mL) were prepared by heating the polymer in 1,2,4- trichlorobenzene (TCB) and rotating on a wheel for 4 hours at 150°C in an oven. The antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT) was added to the mixture in order to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. Sample solutions were24POLY0040-WO-ORD24 chromatographed at 140°C on a PL 220 high-temperature chromatography unit equipped with four Shodex columns (HT803, HT804, HT805 and HT806) using TCB as the mobile phase with a flow rate of 1.0 mL / minute, with a differential refractive index (DRI) as the concentration detector. BHT was added to the mobile phase at a concentration of 250 ppm to protect the columns from oxidative degradation. The sample injection volume was 200 mL. The raw data were processed with CIRRUS® GPC software. The columns were calibrated with narrow distribution polystyrene standards. The polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink equation, as described in the ASTM standard test method D6474.

[0071] Intrinsic Viscosity - The method of measuring the intrinsic viscosity was made in accordance with ISO1628-l :2021.

[0072] Storage Modulus experiment - The storage modulus (G*) was determined by oscillatory rheometer according to ISO 6721-10 and operated between 0.01 and 100 rad / s at 190 °C with parallel plates having 25 mm diameter and 1.2 mm gap between the plates. In particular, Anton Paar MCR 502 rotational rheometer was used in our measurement. The specimen was subjected to a sinusoidal angular displacement of constant angular frequency - “controlled-strain” test, the resultant torque and the phase shift between the displacement and torque was measured. The complex shear modulus G*, shear storage modulus G’, shear loss modulus G”, phase angle 5, and the corresponding shear viscosity terms were determined from the measured torque and displacement and of the specimen dimensions. The oscillatory shear experiments were done within the linear viscoelastic range of strain (10% strain) at frequencies from 0.01 to 100 rad / s. The values of storage modulus (G’), loss modulus (G”), complex modulus (G*) and complex viscosity (h*) were obtained as a function of frequency. In deriving these values, it was assumed that the specimen exhibited a linear-viscoelastic response.

[0073] Yield Stress - Yield stress was measured following ISO527-1 at 1 mm / min for modulus and at 50 mm / min for the tensile test, on bars of type IB at 23 °C.

[0074] Tensile Modulus - Tensile stress was measured following ISO527-1. In particular, as a measure for stiffness, the tensile modulus (E-modulus) of the compositions was measured at 23 °C on compression molded specimens according to ISO 527-2: 1993. The specimens (IB type) were milled from plaques of 4 mm thickness prepared by compression molding according to ISO24POLY0040-WO-ORD25293:2004 using the conditions defined in chapter 3.3 of ISO 1872-2:2007. The modulus was measured at a speed of 1 mm / min.

[0075] Short Chain branching and butyl branching: The short chain branch frequency (SCB per 1000 carbon atoms) of copolymer samples was determined by Fourier Transform Infrared Spectroscopy (FTIR) as per the ASTM D6645-01 method. The molecular structure parameters were calculated by SEC universal based on IR5. Method: IAV Molecular Characterisation, Code: SEC-HT-2 (universal calculation) Chromatography: Polymer Laboratories PL-GPC220 (System ID: C7). Detection: Polymer Laboratories PL BV-400 viscometer; Refractive index detector. Column set: three Polymer Laboratories 13 pm PLgel Olexis, 300 x 7.5 mm. PE molar mass calibration: performed with linear PE standards.

[0076] Injection molding to prepare hinge components: A Husky injection machine H120-RS35 / 28 with a 4-cavity hinge cap mold was used. The machine had a clamping force of 120 tons and was equipped with a standard 3-zone screw of 28 mm & L / D 25.1. The hinge cap tool had a typical butterfly hinge design, which worked with all types of PE materials. There was an in-mold-closing unit integrated in the tool, which enabled the caps to be closed in the tool before the caps were ejected. Hinged caps (components) of the materials on Table 1 were produced in a Husky injection machine H120-RS35 / 28 with a 4-cavity hinge cap mold. The machine had a clamping force of 120 tons and is equipped with a standard 3-zone screw of 28mm diameter at a L / D of 25.1.

[0077] The hinge cap was designed based on a PCO-1881 screw cap with a diameter of 28mm but incorporating a typical bi-stable flip-top hinge with middle living hinge of 0.3mm thick and side hinge of 0.4mm thick. There was an in-mold-closing unit integrated in the tool, which enabled to close the caps in the tool before the caps was ejected.

[0078] The injection molding parameters used for preparing the hinges are provided below:Table 324POLY0040-WO-ORD26

[0079] The hinge samples once obtained were evaluated for the ESCR and torque strength properties as shown below.

[0080] ESCR test for the hinge - The F50 was measured according to ASTM D1693-15 B, condition B, 10% Igepal CO-630, 50 °C.Specimen: compression molded specimen prepared according to ISO 17855-2, specimen thickness: 1.84-1.97 mm, notch depth: 0.3-0.4mm.- F50 determination: Ten specimens are used, and a 50% failure point (F50) was determined by the graphical method in ANNEX Al of DI 693.

[0081] The ESCR performance of the hinge samples were evaluated in the following way: the samples were immersed in an aqueous solution of 10% Igepal; and thereafter conditioning the samples in an oven at 50°C for 3 days. Thereafter, evaluating the performance of the samples by taking the samples out of the Igepal solution and opening and closing the caps manually until failure or up to 120 cycles. The Table below shows the ESCR test results, with the reported average number of bending cycles until hinge failure or up to 120 cycles.

[0082] Strength of hinge - A further test of twist break resistance was carried out: The twist break torque of the hinge samples were evaluated by twisting the hinge using a torque tester. The base part of the cap was clamped by the fixture of the torque tester and the flip-top part was open 180°. The flip-top part of the cap was twisted by hand to break the hinge in around 2 second. The maximum torque was measured to indicate the hinge twist break torque. 5 specimens were tested for each material and average values were measured.Table 424POLYOQ40-WO-ORD27

[0083] From Table 4, it is clear that the inventive samples (IE1 and IE2) show improved ESCR test performance evidenced from the Bell Test. Further the hinge samples from IE1 and IE2 demonstrated excellent performance as shown by open / close cycles without failure even after 3 days conditioning @ 50 °C in 10% Igepal solution. Clearly with 120 cycles, IE1 and IE2 exceeded the performance of the other samples.

[0084] In particular, from the above table, for samples IE1 and IE2, Yield Stress, Tensile Modulus, ESCR, Hinge Twist and open / close cycles all demonstrated excellent performance without compromising on any one property. For example, although CE3 demonstrated desired yield stress and tensile modulus property with better properties than IE1 and IE2, however the ESCR property and the failure cycle test were not satisfactory.

[0085] Therefore, as seen from the examples, the invention now enables a skilled person to develop hinge components having the balance of desirable ESCR performance and hinge24POLY0040-WO-ORD28 strength while retaining the desired processability. It is also seen that copolymers obtained by the use of Ce carbon atoms (1-hexene) as opposed to C4 carbon atoms (1-butene) in combination with other suitable properties such as density, molecular weight based properties (Mw and Mz, MWD), comonomer content as contemplated in the present invention, imparts the desired properties. Further, the hinge components of the present invention allow mono-material packaging and thereby aiding in plastic recycling.

Claims

24POLY0040-WO-ORD29CLAIMS1. A hinge component comprising at least 90.0 wt.% of a polyethylene composition with regard to the total weight of the hinge component, wherein the polyethylene composition comprises or consists of an ethylene copolymer, and wherein the polyethylene composition has:(a) a density of > 940 and < 955 kg / m3, preferably > 940 and < 950 kg / m3, preferably > 942 and < 950 kg / m3, preferably > 942 and < 949 kg / m3, preferably > 942 and < 948 kg / m3, preferably of > 945 and < 953 kg / m3, preferably of > 945 and < 950 kg / m3, determined in accordance with ISO 1183-1 A; and(b) a melt flow rate (MFR) of > 2.0 and < 10.0 g / lOmin, preferably > 4.0 and < 9.5 g / lOmin, preferably > 6.0 and < 9.5 g / lOmin, preferably > 3.0 and < 5.0 g / lOmin, as determined in accordance with ISO 1133 at a load of 2.16 kg and at a temperature of 190 °C; and(c) a weight average molecular weight (Mw) of > 70.0 kg / mol and < 100 kg / mol, preferably > 80 kg / mol and < 100 kg / mol, preferably > 75.0 kg / mol and < 92.0 kg / mol, preferably > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol, determined in accordance with ASTM D 6474-12; and• wherein the polyethylene composition comprises > 95.0 wt.%, preferably > 98.0 wt.%, preferably > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition; and• wherein the polyethylene composition has a unimodal molecular weight distribution; and• wherein the ethylene copolymer comprises or consists of > 95.0 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 5.0 wt.%, preferably > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from alpha olefin comonomer having six to eight carbon atoms, preferably six carbon atoms, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy; and• preferably wherein the polyethylene composition has a molecular weight distribution (MWD) of > 0 and < 10.0, preferably > 1.0 and < 10.0, preferably > 3.0 and < 7.0,24POLY0040-WO-ORD30 preferably > 4.0 and < 7.0, preferably > 4.0 and < 6.0, wherein molecular weight distribution is defined as the ratio of the weight average molecular weight to number average molecular weight, determined in accordance with ASTM D 6474-12.

2. The hinge component according to claim 1, wherein the alpha olefin comonomer is selected from 4-m ethyl- 1 -pentene, 1 -hexene and 1 -octene, preferably wherein the alpha olefin comonomer is 1-hexene.

3. The hinge component according to any one of claims 1-2, wherein the polyethylene composition:(a) has a molecular weight distribution (MWD) of > 3.0 and < 7.0; and(b) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol; and wherein the ethylene copolymer consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1- hexene, with regard to the total weight of the ethylene copolymer, as determined using13C NMR spectroscopy.

4. The hinge component according to any one of claims 1-3, wherein the polyethylene composition:(a) has a molecular weight distribution (MWD) of > 3.0 and < 7.0; and(b) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, preferably > 3.0 and < 5.0 g / lOmin; and wherein the ethylene copolymer consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, as determined using13C NMR spectroscopy.24POLY0040-WO-ORD315. The hinge component according to any one of claims 1-4, wherein the polyethylene composition has:(a) a density of > 942 and < 949 kg / m3; and(b) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin, preferably > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 3.0 and < 7.0; and wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

6. The hinge component according to any one of claims 1-5, wherein the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3; and(b) a weight average molecular weight (Mw) of > 80 kg / mol and < 100 kg / mol, preferably > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 7.0, preferably > 4.0 and < 6.0; and wherein the ethylene copolymer consists of > 96.5 wt.% and < 99.5 wt.%, preferably > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 0.5 wt.% and < 3.5 wt.%, preferably > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, as determined using13C NMR spectroscopy.

7. The hinge component according to any one of claims 1-6, wherein the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3; and24POLY0040-WO-ORD32(b) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 4.0 and < 9.5 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 7.0; and wherein the ethylene copolymer consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1-hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

8. The hinge component according to any one of claims 1-7, wherein the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3; and(b) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and wherein the ethylene copolymer consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1-hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

9. The hinge component according to any one of claims 1-8, has a Z-average molecular weight (Mz) of > 450 and < 580 kg / mol, preferably > 500 and < 580 kg / mol, as determined in accordance with ASTM D6474-12 using size exclusion chromatography.

10. The hinge component according to any one of claims 1-9, wherein the polyethylene composition has > 3.0 and < 7.0, preferably > 3.0 and < 5.7, of butyl branches / 1000 carbon atoms, when determined using13C NMR spectroscopy; and / or wherein the polyethylene composition has > 2.0 and < 4.0, of short chain branches per carbon atoms (SCB) / 1000, determined by Fourier Transform Infrared Spectroscopy (FTIR) in accordance with ASTMPOLY0040-WO-ORD33D6645-01 method and preferably wherein the amount of short chain branching in the polyethylene composition is inversely proportional to the weight average molecular weight of the polyethylene composition.

11. The hinge component according to any one of claims 1-10, wherein the polyethylene composition has:(a) a density of > 942 and < 948 kg / m3determined in accordance with ISO 1183-1 A;(b) a melt flow rate (MFR) of > 3.0 and < 5.0 g / lOmin, as determined in accordance with ISO 1133 at a load of 2.16 kg and at a temperature of 190 °C; and(c) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol, preferably > 87.0 kg / mol and < 95.0 kg / mol; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and(e) Z-average molecular weight (Mz) of > 500 and < 580 kg / mol; and• wherein the polyethylene composition comprises > 98.0 wt.% and < 100 wt.%, of the ethylene copolymer with regard to the total weight of the polyethylene composition; and• wherein the polyethylene composition has a unimodal molecular weight distribution; and• wherein the ethylene copolymer consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using 13C NMR spectroscopy; and• wherein the polyethylene composition has > 3.0 and < 7.0 of butyl branches / 1000 carbon atoms, when determined using13C NMR spectroscopy; and• wherein the polyethylene composition has > 2.0 and < 4.0, of short chain branches (SCB) / 1000 carbon atoms, determined by Fourier Transform Infrared Spectroscopy (FTIR) in accordance with ASTM D6645-01 method; and preferably wherein the amount of short chain branching in the polyethylene composition is inversely proportional to the weight average molecular weight of the polyethylene composition.24POLYOQ40-WO-ORD3412. The hinge component according to any one of claims 1-11, wherein the polyethylene composition has an intrinsic viscosity of > 0.8 and < 2.0 dl / g, preferably > 0.9 and < 1.5 dl / g, preferably > 1.2 and < 1.5 dl / g, determined in accordance with ISO1628-l :2021.

13. The hinge component according to any one of claims 1-12, wherein the polyethylene composition has:(a) a density of > 945 and < 948 kg / m3; and(b) a weight average molecular weight (Mw) of > 85.0 kg / mol and < 95.0 kg / mol; and(c) a melt flow rate (MFR) of > 3.0 and < 5.0 g / lOmin; and(d) a molecular weight distribution (MWD) of > 4.0 and < 6.0; and(e) Z-average molecular weight (Mz) of > 500 and < 580 kg / mol; and(f) a short chain branches (SCB) / 1000 carbon atoms of > 2.0 and < 4.0; and(g) a butyl branches / 1000 carbon atoms of > 3.0 and < 7.0; and(h) an intrinsic viscosity of > 1.2 and < 1.5 dl / g; and wherein the ethylene copolymer comprises or consists of > 96.5 wt.% and < 98.5 wt.%, of polymeric units derived from ethylene; and > 1.5 wt.% and < 3.5 wt.%, of polymeric units derived from 1 -hexene, with regard to the total weight of the ethylene copolymer, determined using13C NMR spectroscopy.

14. The hinge component according to any one of claims 1-13, wherein the polyethylene composition has a ratio of G’ IOOOO / G’ IOOO > 30.0 and < 40.0, where G’ IOOOO is the storage modulus measured at a loss modulus of 10000 Pa and G’iooo is the storage modulus measured at a loss modulus of 1000 Pa, where storage and loss modulus is measured using Dynamic Mechanical Analysis (DMA) using a 25 mm diameter parallel plate geometry at 190° C. under nitrogen atmosphere in accordance with ISO 6721-10.

15. An article comprising the hinge component as claimed in any one of claims 1-14, preferably wherein the article is a living hinge cap closure.

Images