CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. national phase application under 35 U.S.C. § 371 of PCT/EP2018/060316, filed on Apr. 23, 2018, which claims the benefit of priority to FI Application No. 20175561, filed on Jun. 15, 2017, the entire contents of each of which are incorporated by reference herein for all purposes.

BACKGROUND OF THE INVENTION

The invention concerns a cellulose based composition for manufacturing a film or foil, use thereof, as well as a packaging film manufactured thereof, and a method for manufacturing a film or foil. Especially, the invention concerns a composition for manufacturing a film or foil, which composition comprises at least one polymer selected from the group consisting of cellulose acetate butyrate, cellulose acetate propionate and ethyl cellulose, and in addition tall oil fatty acid (TOFA) ester, wherein the molar mass of at least one of the polymers selected from the group consisting of cellulose acetate butyrate, cellulose acetate propionate and ethyl cellulose is above 20,000 Da.

BACKGROUND OF THE INVENTION

To ensure an environmentally sustainable development, plastic materials made from fossil raw materials, such as petroleum or natural gas, need to be replaced with new environmentally friendly materials. These new materials are often called bioplastics.

Several new synthetic bioplastic materials have been developed. These synthetic materials are not necessarily based on renewable resources, but have been made biodegradable in an artificial way. Bioplastics are thus commonly divided into two separate groups: natural and synthetic polymers. Natural polymers are based on biopolymers, for example proteins or polysaccharides (i.e. starch and cellulose). Synthetic biopolymers are for example aliphatic polyesters, polyanhydrides, polyortoesters, water soluble polyvinyl alcohols and certain polyurethanes. Biodegradable materials are typically defined as a mass that degrades in a reasonable time, either by bacterial enzyme activity or by hydrolytic degradation.

One large field, where raw materials from fossil sources are still used, is packing and wrapping materials such as plastic materials (polyethylene, polypropylene etc.). Plastic wrappings, such as films or foils, are one example of materials which typically are derived from petroleum based products or natural gas. Most household plastic wraps are made from polyethylene (PE), polyvinyl chloride (PVC), or polyvinylidene chloride (PVDC) derived from hydrocarbons. Films and foils made from plastic are used for a wide range of purposes. Some examples are cling films or other plastic wraps for packing food, plastic films for wrapping bales of hay etc. Such wrapping or packing materials need to be replaced with environmentally friendly alternatives.

Cellulose is a natural polymer and is considered a renewable resource. Known cellulose based materials are for example Cellophane, Celluloid, Transparit, Cellidor, and Cellblend. Cellulose based materials are typically biodegradable. However, many of these materials have not been considered economically feasible compared to petroleum based products. Thereto, they have had other disadvantages relating to processability etc. Cellulose acetate, cellulose acetobutyrate, benzyl cellulose, and ethyl cellulose, for example, need high DS to obtain melt processability. Thermoplasticity and biodegradability are not always compatible.

Although some new bioplastics have been developed to replace petroleum based plastic materials, there is still a constant need for finding new sustainable solutions to ensure a sustainable development and to alleviate waste problems related to packaging materials and plastics. Especially, there is a need to develop materials with clingy properties to replace traditional cling films, such as LDPE cling films.

SUMMARY OF THE INVENTION

The objective of the invention is to achieve a solution to the above-mentioned problems. Especially, the objective of the invention is to bring forth a cellulose based composition, which can be used to manufacture films or foils. The new cellulose based composition could replace films or foils based on fossil raw materials, and which are used as packing or wrapping materials. Thus, the cellulose based composition and films or foils manufactured therefrom provide a more sustainable packing material option for grocers and consumers.

The objectives of the invention are accomplished with a composition having the characteristics as mentioned in the independent claims. The preferred embodiments of the invention are presented in the independent claims. One objective of the invention is thus to provide a cellulose based composition for manufacturing a film or foil. The cellulose based composition according to the invention comprises at least one of the cellulose based polymers selected from the group consisting of: cellulose acetate butyrate, cellulose acetate propionate and ethyl cellulose, and in addition tall oil fatty acid ester, wherein the molar mass of at least one of the polymers selected from the group consisting of cellulose acetate butyrate, cellulose acetate propionate and ethyl cellulose is above 20,000 Da. The present invention also concerns a packaging film, which comprises the cellulose based composition according to the invention.

In addition to the new composition and packaging film, the present invention concerns a method for manufacturing a film or foil. The method according to the invention comprises the following steps:melt mixing a composition comprising at least one of the polymers selected from the group consisting of cellulose acetate butyrate, cellulose acetate propionate and ethyl cellulose, and tall oil fatty acid ester, to obtain a homogenous mixture, ester, to obtain a homogenous mixture, wherein optionally, tall oil fatty acid ester is added to the polymer(s) in at least two steps,granulating the homogenous mixture to obtain a granulated raw material, andproducing a film or foil material from said granulated raw material.

The present invention concerns also use of the cellulose based composition according to the invention for the manufacture of a packaging film. Also the invention concerns use of the cellulose based composition according to the invention in a film blowing process.

The invention is based on the surprising finding that an environmentally friendly composition for manufacturing a film or foil can be prepared from a mixture comprising at least one of the cellulose based polymers selected from the group consisting of cellulose acetate butyrate, cellulose acetate propionate and ethyl cellulose, together with tall oil fatty acid ester. The obtained composition can be formed into a packaging film or foil with clingy properties.

One advantage with the composition according to the invention is that it can be processed in conventional machines, which are now used to manufacture and process plastic films. Thus, no expensive apparatus investments need to be made.

SHORT DESCRIPTION OF THE FIGURES

In the following, the invention is illustrated more closely by FIGURE referring to the enclosedFIG. 1, which shows an example of a film manufactured from the composition according to the invention.

Definitions

In the present application and claims the following terms and expressions have the meanings as defined below.

“Cellulose based” is defined as comprising polymers obtained from fibers derived from cellulose containing material. The polymers obtained from fibers derived from cellulose containing material are thus biopolymers. The cellulose based polymers are typically derivatives, such as ethers or esters of cellulose. The cellulose containing material can be obtained from various raw materials, for example wood, bark or leaves of plants, or from a plant-based material.

“Cellulose acetate butyrate” (CAB) polymer and “cellulose acetate propionate” (CAP) polymer are cellulose derivatives. They are produced by esterification of some hydroxyl groups in the cellulose polymer chain on the repeating glucose units. Cellulose acetate butyrate/propionate are used as binders and additives in coatings applications for a variety of substrates. These products offer a wide range of properties based on their butyryl/propyl, acetyl and hydroxy contents.

“Ethyl cellulose” (EC) polymer is another derivative of cellulose. Some of the hydroxyl groups in the cellulose polymer chain on the repeating glucose units have been converted into ethyl ether groups. Ethyl cellulose is mainly used in industrial applications such as in thin-film, but some grades can also be used in regulated markets such as food and pharmaceuticals. The number of ethyl groups may vary depending on the manufacturing process and give various properties to the material.

“Tall oil fatty acid ester” or TOFA ester is an ester of tall oil fatty acids. Typically, tall oil fatty acid methyl ester is used.

“Packaging film” may be for example cling film, shrink film, stretch film, bag film or container liners, films meant for consumer packaging (e.g. packaging film for frozen products, shrink film for transport packaging, food wrap film, packaging bags, or form, fill and seal packaging film), laminating film (e.g. laminating of aluminum or paper used for packaging for example milk or coffee), barrier film (e.g. film acting as an aroma or oxygen barrier used for packaging food, e.g. cold meats and cheese), films for the packaging of medical products, agricultural film (e.g. greenhouse film, crop forcing film, silage film, silage stretch film) or for applications in packaging cosmetics.

“Blow film process” or “film blowing process” or “blow film extrusion” is one of the most common methods of film manufacture. The blown film process is also sometimes referred to as the tubular film extrusion. The process involves extrusion of a plastic through a circular die, followed by “bubble-like” expansion.

