[0001] The present invention relates to an article, preferably a bottle, comprising recycled and renewable polyethylene. The invention also relates to an extrusion blow-moulding process for the production of such articles.

[0002] For a great variety of applications, including for example as containers for liquid household goods, articles, such as hollow body containers, a particular example of which being bottles of various shapes, are ubiquitously utilised. Examples of household goods that commonly are contained in the articles that are subject of the present invention are liquid foodstuffs, detergents, liquid soap, to name some.

[0003] To qualify for such use, the containers need to comply with a range of specifications. It is for example a requirement that they provide an adequate barrier between the contents of the article and the environment so that degradation of the contents caused by the environment it is subject to is minimised. Furthermore, the container needs to be sufficiently inert to the material contained therein to avoid degradation of the container wall material, as well as contamination of the contents of the container. More requirements apply, including the need that the container needs to be sufficiently shape-stable, and it needs to be able to be produced at attractive process economies.

[0004] Presently, additional properties are being requested of the containers. In view of an ever increasing desire to stimulate circularity, in particular in packaging materials, it is desired that packaging solutions, including hollow body containers, are increasingly light in weight, thereby reducing the amount of material used, they should be suitable for being recycled, and to the extent possible they should be produced using materials that are themselves recycled. At the same time, the further properties as referred to above should not be compromised, as the article still needs to fulfil its purpose as a package.

[0005] In view of the desire for a package to be suitable for being recycled, a particular way to achieve this is via ensuring that the package is essentially made out of material that belongs to a single material family. In the art, many packaging solutions exist where one part of the object is made out of material belonging to a first family of materials, and other parts out of material from a second family. Since it is undesirable at least but often also impossible at most to recycle materials belonging to different families of materials in a single recycling process, one will understand that there is a strive to manufacture objects that are to be suitable for recycling from materials belonging to a single family to the largest degree possible.

[0006] In packaging, in particular in single-use packaging, this is even more relevant, due to the short service life of the article. Furthermore, in packaging solutions, barrier elements that serve to contain a product quite often are manufactured in the form of multi-layer wall or film solutions; and in such solutions, it is quite common that the different layers of such object wall contain very different types of materials, that are unsuitable for joint recycling. For example, thermoplastic multilayer barrier walls may comprise layers comprising polyolefin materials, layers comprising polyamide materials, and/or layers comprising polyester materials, to name just a few, combined together; wherein each layer serves its own purpose to achieve the ultimate properties that are required for the particular application.

[0007] One will understand that it is impossible to tear apart such layers when preparing materials for recycling. Accordingly, it is desired that the various layers of such application, while together still of such constitution that the required properties of the article are achieved, are of materials belonging to a single family of materials. By so, recycling of the article is greatly facilitated.

[0008] A particular family of materials that one would seek to employ in such solutions are polyethylenes. Polyethylenes are the most ubiquitously used thermoplastic polymer family, due to their vast potential of applications. Mixed plastics recycle streams typically contain a majority portion of polyethylenes. Recycling of polyethylenes can be achieved via a range of recycling technologies, including mechanical recycling and chemical recycling, which is facilitated by the fact that polyethylenes consist essentially of carbon and hydrogen atoms; this contributes to the reduction of the presence of undesirable atoms such as certain heteroatoms and metals in recycling processes such as chemical recycling. For these reasons, it is desirable that articles that need to be suitable for recycling contain a maximised quantity of polyethylene as constituents of their material formulation.

[0009] Accordingly, the development of such mono-material solutions for articles is subject of many investigations. In addition, it needs to be established that the article properties including material strength and durability are not compromised. In the present application, such solution is provided by an article for containing liquids, comprising an outer wall, wherein the outer wall is a multi-layer system comprising at least three layers A, B and C in this order, wherein the layer A is suitable for contacting a liquid material that may be contained within the article and forms the inner layer of the multi-layer system, the layer B forms the intermediate layer, and the layer C forms the outer layer of the multi-layer system; wherein:

• the layer A comprises a polyethylene A having a density of > 0.940 and < 0.970 g/cm ³ ;

• the layer B is a foamed layer comprising a polyethylene composition B having a density of > 0.940 and < 0.970 g/cm ³ ; and

• the layer C comprises a polyethylene composition C having a density of > 0.940 and < 0.970 g/cm ³ .

[0010] Such article may be produced using a mono-material solution of polyethylene, thereby contributing to the recyclability of the article, whilst providing desirable strength, durability and inertness.

[0011] Preferably, the article is a hollow body container, more preferably a bottle. The article may for example have an inner volume of > 0.05 and < 5.0 I, preferably of > 0.05 and < 2.0 I.

[0012] The polyethylene A may for example be a homopolymer of ethylene, or a copolymer of ethylene and an a-olefin selected from 1-butene, 1-hexene, 4-methyl-1 -pentene, and 1-octene. For example, the polyethylene A may be a polymer comprising moieties of ethylene and < 5.0 wt % of moieties derived from 1-butene, 1-hexene, 4-methyl-1 -pentene, and 1-octene, with regard to the total weight of the polymer.

[0013] The polyethylene composition B may for example comprise a homopolymer of ethylene, or a copolymer of ethylene and an a-olefin selected from 1-butene, 1-hexene, 4-methyl-1- pentene, and 1-octene. For example, the polyethylene composition B may comprise a polymer comprising moieties of ethylene and < 5.0 wt % of moieties derived from 1-butene, 1-hexene, 4- methyl-1 -pentene, and 1-octene, with regard to the total weight of the polymer. For example, the polyethylene composition B may comprise, with regard to the total weight of the polyethylene composition B, > 30.0 wt% and < 70.0 wt% of a polymer comprising moieties of ethylene and < 5.0 wt % of moieties derived from 1-butene, 1-hexene, 4-methyl-1 -pentene, and 1-octene, with regard to the total weight of the polymer. [0014] For example, the polyethylene composition B may comprise > 80.0 wt% of polyethylenes, preferably > 90.0 wt%, with regard to the total weight of the polyethylene composition B.

[0015] The polyethylene composition B may for example comprise < 5.0 wt% of polypropylene, preferably > 0.1 and < 5.0 wt%, more preferably > 0.1 and < 3.0 wt%, with regard to the total weight of the polyethylene composition B.

[0016] The layer B may for example have a foam density of > 0.20 and < 0.80 g/cm ³ , preferably > 0.40 and < 0.75 g/cm ³ , more preferably > 0.50 and < 0.75 g/cm ³ , even more preferably of > 0.60 and < 0.75 g/cm ³ , yet even more preferably of > 0.65 and < 0.75 g/cm ³ , as determined in accordance with the method of ISO 845 (2006). It is preferred that the layer B comprises < 10.0 wt% of talc, more preferably > 0.1 and < 5.0 wt%, even more preferably > 0.5 and < 5.0 wt%, with regard to the total weight of the layer B.

[0017] The polyethylene composition C may for example comprise a homopolymer of ethylene, or a copolymer of ethylene and an a-olefin selected from 1-butene, 1-hexene, 4-methyl-1- pentene, and 1-octene. For example, the polyethylene composition C may comprise a polymer comprising moieties of ethylene and < 5.0 wt % of moieties derived from 1-butene, 1-hexene, 4- methyl-1 -pentene, and 1-octene, with regard to the total weight of the polymer. For example, the polyethylene composition C may comprise, with regard to the total weight of the polyethylene composition B, > 30.0 wt% and < 70.0 wt% of a polymer comprising moieties of ethylene and < 5.0 wt % of moieties derived from 1-butene, 1-hexene, 4-methyl-1 -pentene, and 1-octene, with regard to the total weight of the polymer.

[0018] For example, the polyethylene composition C may comprise > 80.0 wt% of polyethylenes, preferably > 90.0 wt%, with regard to the total weight of the polyethylene composition C.

[0019] The polyethylene A may for example be a homopolymer of ethylene, or a copolymer of ethylene and an a-olefin selected from 1-butene, 1-hexene, 4-methyl-1 -pentene, and 1-octene. For example, the polyethylene A may be a polymer comprising moieties of ethylene and < 5.0 wt % of moieties derived from 1-butene, 1-hexene, 4-methyl-1 -pentene, and 1-octene, with regard to the total weight of the polymer. [0020] The polyethylene composition C may for example comprise < 5.0 wt% of polypropylene, preferably > 0.1 and < 5.0 wt%, more preferably > 0.1 and < 3.0 wt%, with regard to the total weight of the polyethylene composition C.

[0021] For example, the polyethylene composition B may have a melt mass-flow rate as determined in accordance with ISO 1133-1 (2011) at 190°C and 21.6 kg load of > 10.0 and < 70.0 g/10 min, preferably of > 20.0 and < 60.0 g/10 min, more preferably of > 20.0 and < 50.0 g/10 min.

[0022] For example, the polyethylene composition B may have a melt mass-flow rate as determined in accordance with ISO 1133-1 (2011) at 190°C and 5.0 kg load of > 0.5 and < 5.0 g/10 min, preferably of > 0.5 and < 3.0 g/10 min, more preferably of > 0.5 and < 2.0 g/10 min.

[0023] For example, the polyethylene composition B may have a density of > 960 and < 970 kg/m ³ . For example, the polyethylene composition C may have a density of > 960 and < 970 kg/m ³ . Density of the polyethylenes or polyethylene compositions may be determined in accordance with ISO 1183-1 (2019).

[0024] For example, the polyethylene composition B may have a melt mass-flow rate as determined in accordance with ISO 1133-1 (2011) at 190°C and 2.1 kg load of > 0.15 and < 0.5 g/10 min, preferably of > 0.15 and < 0.4 g/10 min, more preferably of > 0.15 and < 0.3 g/10 min.

[0025] For example, the polyethylene composition C may have a melt mass-flow rate as determined in accordance with ISO 1133-1 (2011) at 190°C and 21.6 kg load of > 10.0 and < 70.0 g/10 min, preferably of > 20.0 and < 60.0 g/10 min, more preferably of > 20.0 and < 50.0 g/10 min.

[0026] For example, the polyethylene composition C may have a melt mass-flow rate as determined in accordance with ISO 1133-1 (2011) at 190°C and 5.0 kg load of > 0.5 and < 5.0 g/10 min, preferably of > 0.5 and < 3.0 g/10 min, more preferably of > 0.5 and < 2.0 g/10 min. [0027] For example, the polyethylene composition C may have a melt mass-flow rate as determined in accordance with ISO 1133-1 (2011) at 190°C and 2.1 kg load of > 0.15 and < 0.5 g/10 min, preferably of > 0.15 and < 0.4 g/10 min, more preferably of > 0.15 and < 0.3 g/10 min.

[0028] For example, the polyethylene A may have a melt mass-flow rate as determined in accordance with ISO 1133-1 (2011) at 190°C and 21.6 kg load of > 10.0 and < 70.0 g/10 min, preferably of > 20.0 and < 60.0 g/10 min, more preferably of > 20.0 and < 50.0 g/10 min.

[0029] For example, the polyethylene A may have a melt mass-flow rate as determined in accordance with ISO 1133-1 (2011) at 190°C and 5.0 kg load of > 0.5 and < 5.0 g/10 min, preferably of > 0.5 and < 3.0 g/10 min, more preferably of > 0.5 and < 2.0 g/10 min.

[0030] For example, the polyethylene A may have a melt mass-flow rate as determined in accordance with ISO 1133-1 (2011) at 190°C and 2.1 kg load of > 0.15 and < 0.5 g/10 min, preferably of > 0.15 and < 0.4 g/10 min, more preferably of > 0.15 and < 0.3 g/10 min.

[0031] The polyethylene composition B may for example be a composition comprising postconsumer mechanically recycled polyethylene, preferably comprising > 30.0 and < 60.0 wt% of post-consumer mechanically recycled polyethylene.

[0032] The polyethylene composition C may for example be a composition comprising postconsumer mechanically recycled polyethylene, preferably comprising > 30.0 and < 60.0 wt% of post-consumer mechanically recycled polyethylene.

[0033] The polyethylene A may for example be a polyethylene obtained by chemical recycling of polyethylene, or by a synthesis process using a biorenewable hydrocarbon feedstock.

[0034] In the article, the multi-layer system may for example have a thickness of > 0.5 and < 2.5 mm, preferably of > 0.7 and < 2.0, more preferably of > 0.7 and < 1.5 mm, even more preferably of > 0.9 and < 1.5 mm. The layer A may for example have a thickness of > 0.1 and < 0.3 mm, preferably of > 0.15 and < 0.25 mm. The layer B may for example have a thickness of > 0.3 and < 1.0 mm, preferably of > 0.4 and < 1.0 mm, more preferably of > 0.4 and < 0.8 mm, even more preferably of > 0.5 and < 0.7 mm. The layer C may for example have a thickness of > 0.1 and< 0.3 mm, preferably of > 0.15 and < 0.25 mm. [0035] For example, the multi-layer system may have a thickness of > 0.7 and < 1.5 mm, preferably of > 0.9 and < 1.5 mm, wherein the layer A has a thickness of > 0.15 and < 0.25 mm, the layer B has a thickness of > 0.4 and < 1.0 mm, preferably of > 0.5 and < 0.7 mm, and the layer C has a thickness of > 0.15 and < 0.25 mm.

[0036] The article may for example be produced by an extrusion blow-moulding process.

[0037] In an embodiment, the present invention also relates to a process for production of an article according to the invention, wherein the process involves the steps of:

(i) producing a tubular shaped object comprising the layers A, B and C via extrusion, preferably via co-extrusion, more preferably continuous co-extrusion;

(ii) enclosing the tubular shaped object with a mould having the exterior form of the article;

(iii) supplying a pressurised gas to the inner volume of the tubular shaped object so that the tubular shape expands to fill the mould to the form of the article;

(iv) cooling the mould to solidify the outer wall; and

(v) removing the article from the mould.

[0038] The tubular shaped object may herein also be referred to as a parison.

[0039] In step (i) the co-extrusion of the tubular shaped object may for example involve supplying the materials that are to constitute the layers A, B and C in molten state via an extrusion head comprising split annular flow channels for each of the layers A, B and C, wherein the annular flows of extruded material are contacted upon exiting the extrusion head to form the tubular shaped object comprising the layers A, B and C.

[0040] In step (i), a foaming agent may be supplied to the material that forms layer B, wherein the material that forms layer B is in a molten state at the time of supply of the foaming agent, preferably wherein the foaming agent in nitrogen.

[0041] An exemplary embodiment of the article is presented in Fig. 1. Therein, a cross-section of an article according to the invention (1) is shown. The article of Fig. 1 comprises an outside wall (2), an outer layer (3) corresponding to layer C of the article of the invention, a foamed layer (4) corresponding to the intermediate layer B of the article of the invention, an inner layer (5) corresponding to layer A of the article of the invention, and an inside wall (6).

[0042] In a certain embodiment, the invention also relates to the use of a multi-layer system comprising at least three layers A, B and C in this order, wherein the layer A is suitable for contacting a liquid material that may be contained within the article and forms the inner layer of the multi-layer system, the layer B forms the intermediate layer, and the layer C forms the outer layer of the multi-layer system; wherein:

• the layer A comprises a polyethylene A having a density of > 0.940 and < 0.970 g/cm ³ ;

• the layer B is a foamed layer, having a foam density of > 0.65 and < 0.75 g/cm ³ , as determined in accordance with the method of ISO 845 (2006), comprising a polyethylene composition B having a density of > 0.940 and < 0.970 g/cm ³ , preferably of > 0.960 and < 0.970 g/cm ³ ; and

• the layer C comprises a polyethylene composition C having a density of > 0.940 and < 0.970 g/cm ³ , preferably of > 0.960 and < 0.970 g/cm ³ ; the density being determined in accordance with ISO 1183-1 (2019); for improvement of the load bearing properties of an extrusion blow-moulded article, preferably a hollow body container.

[0043] The invention will now be illustrated by the following non-limiting examples.

Materials

[0044] Each of T5E01BG, T5E01BN, T5E01BB and T5E01BW contained ca. 1 wt% of polypropylene. [0045] Experiments were conducted by co-extrusion of the above-listed materials on a blowmoulding machine equipped with three extruders in combination with a three-layer extrusion head and a dynamic mixer with gas dosing between the extruder and the extrusion head. The main extruder B for the intermediate layer B was a 60/25D extruder; the extruder A for the inner layer A was a 25/25D extruder; the extruder C for the outer layer C was a 30/25D extruder. Multi-layer bottles having a volume of 70 ml were produced. Nitrogen was used as foaming agent, also referred to as blowing agent, for the layer B. The total throughput of the extruders was 4.2 kg/h; the melt temperature of extruder A was 188°C; the melt temperature of extruder B was 190°C; the melt temperature of extruder C was 187°C. The temperature of the extrusion head was 160°C. A 3-layer parison of diameter 20 mm was formed by extrusion according to the formulations in the table below: Wherein

• MI2 is the melt mass-flow rate determined at 2.16 kg, 190°C, expressed in g/10 min, in accordance with ISO 1133 (2011);

• MI5 is the melt mass-flow rate as determined at 5.0 kg, 190°C, expressed in g/10 min, in accordance with ISO 1133 (2011);

• MI21 is the melt mass-flow rate as determined at 21 .6 kg, 190°C, expressed in g/10 min, in accordance with ISO 1133 (2011);

• density is the density of the polyethylene, as determined in accordance with ISO 1183-1 (2019);

• all the percentage of the composition of the layers B are in wt% with regard to the total weight of the layer B.

[0046] Subsequently, the parison was subjected to blow moulding in a mould at ambient temperature by applying a blowing pressure between 2 and 6 bar for 8 s. By this process, 70 ml bottles were formed having a wall thickness of 1 mm, of which 0.2 mm layer A, 0.6 mm layer B, and 0.2 mm layer C. The foamed layer B has a foam density of 0.70 g/cm ³ . The moulded bottles had an inner wall that is inert to required products that are to be contained in such bottles, such as foodstuffs, detergents, soaps and cosmetic products. The bottles further showed desirable load bearing strengths of over 300 N; the load bearing strength being defined as the load at which the bottle neck collapses as a result of the load exerted onto it.

[0047] For comparative purposes, bottles were prepared according to the extrusion and moulding conditions set out above, with the exception that no blowing agent was added; accordingly, the moulded bottles did not contain a foamed intermediate layer B, but rather a solid layer B. When subjecting these bottles to load testing, it was observed that the bottles did not pass a test at load of 300 N; the bottle necks collapsed under such load. It was determined that to comply with this load bearing requirement, the weight of the layer B had to be increased to such extent that the total weight of the bottle increased by 10%.

[0048] Accordingly, it can be understood that the article according to the invention allows for providing desirable load bearing properties at reduced weight of the article.