EA039636B1 - Degradable sheet material - Google Patents

Abstract

The invention provides a sheet material formed of a degradeable composition, the composition comprising: 30 to 80 wt.% calcium carbonate by weight of the composition; an additive; and the balance a polymer selected from polyethylene, polypropylene and copolymers and blends thereof; wherein the additive comprises, by combined weight of the additive and the polymer: (a) two or more transition metal compounds in a total amount of from 0.15 to 0.6 wt.%, wherein the transition metal compounds comprise a stearate moiety; (b) a mono- or poly-unsaturated C14-C24 carboxylic acid in an amount of from 0.04 to 0.08 wt.%; (c) a synthetic rubber in an amount of from 0.04 to 0.2 wt.%; wherein the two or more transition metal compounds are selected from iron, manganese, copper compounds and wherein the transition metals in the two or more transition metal compounds are different; wherein the transition metals in the two or more transition metal compounds comprise: i) iron, manganese and copper; or (ii) manganese and copper; or (iii) iron and manganese. Furthermore, the invention provides packaging, a container and a disposable coffee cup formed of said sheet material and a method of forming a container, a method of initiating the chemical degradation of said packaging, container and disposable coffee cup and the use of an additive to initiate degradation of a sheet material.

Description

The present invention relates to a disposable sheet material suitable for use as a package or to form a container. The sheet material is particularly suitable in cases where a waterproof material is required for a single or temporary application. A preferred use is in a disposable container for holding hot or cold beverages, commonly referred to as a coffee cup. The material described herein has the particular advantage that it is easily degradable and satisfies the slow degradation requirements of standard packaging materials.

Tons of paper packaging materials are thrown away as waste every day. Because it seems obvious that the product is made from paper, end users incorrectly assume that the material will degrade quickly, which may prompt them to discard the material, or they may even assume that the material is recyclable and place it in a container. for recyclable waste. However, when a paper material is rendered waterproof, it is usually done by combining the paper with polyethylene, producing a material that cannot be separated into its original components in a standard waste recycling process and preventing the material being discarded from quickly decomposing.

This problem is particularly relevant for coffee cups used for take-out drinks such as coffee and tea in roadside establishments such as cafes. Typically, said cups are made from cardboard which has been treated to be water resistant and which may be provided with a separate or integrated cuff to seal the contents and protect the user's hands from hot or cold liquid drinks.

In addition, it is known to obtain plastic packaging materials and containers, including plastic coffee cups. The use of such polymeric materials has numerous advantages and can provide chemically and biologically inert durable materials at a relatively low cost. Unfortunately, many of these characteristics make it difficult to dispose of without causing long-term environmental damage. The very short life of plastic containers results in a rapid accumulation of waste that is inert to most of the physical and chemical stresses to which they are subjected during traditional disposal.

As the world's population becomes more aware of the human impact on our climate, our ecosystems and the planet as a whole, there is an increasing need to increase the proportion of waste that can be recycled. Accordingly, the demand for alternatives to traditional polymeric materials is increasing.

A number of degradable polymer compositions have been developed. However, there are significant disadvantages associated with these conventional degradable polymers. Traditional degradable polymers (such as aliphatic polyesters) tend to be stable and difficult to process, resulting in lower productivity. These materials have significantly higher densities and lower strength values than conventional non-degradable commercial polymers.

US 4,016,117 discloses the use of biodegradable filler materials, such as starch, and auto-oxidizing agents, such as fat, which, when exposed to transition metals in soil, form peroxides that break bonds between carbon atoms in the resin.

US 4,931,488 discloses adding a biodegradable substance (starch), an iron compound (FeOH(stearate) ₂ ) and a fatty acid or fatty acid ester (eg soybean oil, which is a mixture of fatty acid esters) to a thermoplastic polymer. The resulting plastic composition decomposes under the action of heat and/or ultraviolet radiation and/or sunlight. These compositions have insufficient rates of abiotic degradation and biodegradation.

The modern consumer is becoming increasingly aware of their social responsibility and their contribution to carbon dioxide emissions. Accordingly, negative public attitudes towards this waste problem are increasing and there is an urgent need to find an environmentally friendly alternative. Therefore, it is desirable to provide a degradable sheet material suitable for use in the preparation of packages or containers, in particular coffee cups, and/or to solve at least some of the problems associated with the prior art, or at least to provide corresponding alternatives suitable for industrial applications. In particular, it is desirable to provide a packaging or wrapping material that is recyclable and also readily degradable, in particular when it is disposed of as waste.

The essence of the invention

According to a first aspect, the present invention provides a sheet material obtained from a degradable composition, wherein the composition contains from 30 to 80% by weight of calcium carbonate relative to the weight of the composition;

additive;

- 1 039636 a polymer comprising the rest of the mass, selected from polyethylene, polypropylene and their copolymers and mixtures, and the additive contains, in relation to the combined mass of the additive and polymer (a), two or more transition metal compounds in a total amount of from 0.15 to 0.6 wt.%, where the transition metal compounds contain a fragment of stearate;

(b) mono - or polyunsaturated C ₁₄ -C ₂₄ -carboxylic acid in an amount of from 0.04 to 0.08 wt.%;

(c) synthetic rubber in an amount of 0.04 to 0.2% by weight;

wherein the two or more transition metal compounds are selected from iron, manganese, copper compounds, and wherein the transition metals in the two or more transition metal compounds are different;

where the transition metals in two or more transition metal compounds contain (i) iron, manganese and copper; or (ii) manganese and copper; or (iii) iron and manganese.

The composition may further comprise (d) dry starch in an amount of up to 20% by weight.

The composition may additionally contain (e) calcium oxide in an amount up to 1 wt.%.

The composition may further comprise (f) a phenolic antioxidant stabilizer in an amount of up to 0.2% by weight.

In one embodiment, the composition contains 60 to 70 wt % calcium carbonate, wherein the calcium carbonate preferably has an average larger particle diameter of 1 to 30 microns.

According to one embodiment, the sheet material has an average thickness of 100 to 500 µm, preferably 200 to 400 µm.

According to another embodiment, the composition has a foam-containing structure.

According to one embodiment, the composition further comprises (g) an oxidizing agent, preferably calcium nitrate.

In one embodiment, the mono- or polyunsaturated C ₁₄ -C ₂₄ carboxylic acid is a linear C ₁₆ -C ₂₀ carboxylic acid, preferably oleic acid.

In one embodiment, the synthetic rubber comprises an unsaturated polymer, preferably styrene-isoprene-styrene, more preferably a mixture of styrene-isoprene-styrene and styrene-isoprene copolymers.

In one embodiment, the polymer is high density polyethylene (HDPE), preferably having a melt flow index of 10 to 20 g/10 min.

In one embodiment, the composition comprises, based on the combined weight of additive and polymer:

(a) two or more transition metal stearates in a total amount of 0.2 to 0.3% by weight; and/or (b) monounsaturated linear C ₁₆ -C ₂₀ -carboxylic acid in an amount of from 0.04 to 0.06 wt.%; and/or (c) synthetic rubber in an amount of 0.08 to 0.12% by weight; and/or (d) dry starch in an amount of 0.1 to 0.4% by weight; and/or (e) calcium oxide in an amount of 0.1 to 0.3% by weight; and/or (f) calcium nitrate in an amount of 0.1 to 1.0% by weight.

According to a second aspect, the present invention provides a package made from the above sheet material.

According to a third aspect, the present invention provides a container made from the above sheet material.

According to a fourth aspect, the present invention provides a disposable coffee cup made from the above sheet material.

According to a fifth aspect, the present invention provides a method for producing a container, the method comprising obtaining a composition containing 30 to 80 wt.% calcium carbonate relative to the weight of the composition, a polymer and an additive, molding the composition to obtain a container, the polymer being selected from polyethylene, polypropylene and their copolymers and mixtures, and the additive contains in relation to the combined weight of the additive and polymer (a) two or more transition metal compounds in a total amount of from 0.15 to 0.6 wt.%, where the transition metal compounds contain a stearate moiety;

(b) mono - or polyunsaturated C ₁₄ -C ₂₄ -carboxylic acid in an amount of from 0.04 to 0.08 wt.%;

(c) synthetic rubber in an amount of 0.04 to 0.2% by weight;

wherein two or more transition metal compounds are selected from iron(III), manganese, copper compounds, and wherein the transition metals in the two or more transition metal compounds are different;

where the transition metals in two or more transition metal compounds contain

- 2 039636 (i) iron, manganese and copper; or (ii) manganese and copper; or (iii) iron and manganese.

According to one embodiment, the step of molding the composition into a container comprises (a) molding the composition into a container configuration, preferably by thermoforming, injection molding, injection blow molding, or compression molding; or (b) obtaining and molding one or more sheets of the composition into a container configuration and optionally fixing the configuration by heat sealing or gluing; or (c) 3D printing.

According to another embodiment, the method is to obtain the above container or the above disposable coffee cup.

According to a sixth aspect, the present invention provides a method for initiating chemical decomposition of the above package, or the above container, or the above disposable coffee cup, the method comprising exposing the sheet material to temperatures in excess of 50° C. by contacting the sheet material with a hot beverage or food product, or by exposing the sheet material to microwave heating.

According to another embodiment, primary degradation occurs within 6 weeks and secondary microbial degradation occurs within 1 year.

According to a sixth aspect, the present invention provides the use of an additive for initiating the decomposition of a sheet material after exposure to temperatures exceeding 50°C, wherein the sheet material is obtained from a composition containing from 30 to 80 wt.% calcium carbonate relative to the mass of the composition;

additive;

the remaining polymer selected from polyethylene, polypropylene and their copolymers and mixtures, and at the same time the additive contains, in relation to the combined mass of the additive and polymer (a), two or more transition metal compounds in a total amount of from 0.15 to 0.6 wt .%, where the transition metal compounds contain a fragment of stearate;

(b) mono - or polyunsaturated C ₁₄ -C ₂₄ -carboxylic acid in an amount of from 0.04 to 0.08 wt.%;

(c) synthetic rubber in an amount of 0.04 to 0.2% by weight;

wherein the two or more transition metal compounds are selected from iron, manganese, copper compounds, and wherein the transition metals in the two or more transition metal compounds are different;

where the transition metals in two or more transition metal compounds contain (i) iron, manganese and copper; or (ii) manganese and copper; or (iii) iron and manganese.

Detailed description of the invention

This document describes a sheet material obtained from a degradable composition, and the composition contains from 30 to 80 wt.% calcium carbonate relative to the weight of the composition;

additive;

the remaining polymer selected from polyethylene, polypropylene and their copolymers and mixtures, and the additive contains, in relation to the combined mass of additive and polymer (a) two or more transition metal compounds in a total amount of from 0.15 to 0.6 wt%;

(b) mono - or polyunsaturated C ₁₄ -C ₂₄ -carboxylic acid or its ester, anhydride or amide in an amount of from 0.04 to 0.08 wt.%;

(c) synthetic rubber in an amount of 0.04 to 0.2% by weight; and optionally (d) dry starch in an amount of 0 to 20% by weight; and/or (e) calcium oxide in an amount of 0 to 1% by weight; and/or (f) a phenolic antioxidant stabilizer in an amount of from 0 to 0.2 wt.%, and two or more compounds of transition metals are selected from compounds of iron, manganese, copper, zinc, titanium, cobalt and cerium, and the transition metals in two or more transition metal compounds are different.

Preferably the sheet material is a disposable coffee cup. While the following description is focused on sheet materials, it applies equally to an embodiment in which the sheet material is in the form of a disposable coffee cup.

Preferably the additive consists essentially of the listed components (a)-(f). Preferably, the composition is mainly additive, calcium carbonate and polymer. That is, the composition preferably contains less than 5 wt%, and more preferably less than 1 wt%, of other ingredients; most preferably it is free of other ingredients.

The following is a description of the present invention. In the following sections, various aspects of the present invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless expressly stated otherwise. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

The present invention provides a sheet material that can be used for packaging or for making a container. One example of a sheet is a traditional patty bun wrapper. This is a thin, waterproof wrapper that is often thrown away by the consumer, wrongly believing that it should degrade easily. Another example is a molded container or a folded and glued container such as a food carton used for takeaway packaging. Other examples are product packaging intended for general retail use. Advantageously, the compositions described herein may be heat sealed to form closed containers or sealed packages.

A disposable coffee cup is a container that is designed to contain one serving of a beverage and from which the consumer can drink the beverage. Typically, such a container has a volume of 30 ml to 1 liter, more specifically 200 to 350 ml. The container is suitable for holding a hot beverage at temperatures up to 100°C, although typically the maximum temperature for its use is only 80 to 95°C. Thus, the container remains watertight for the period of time provided for its use, i.e. within at least one day. The coffee cup is disposable, which means that it is meant to be disposed of after use and not reused for another drink. The container has an opening through which the container can be filled and emptied.

Typical coffee cups are in the form of a hollow truncated cone having a lower closed base with a smaller diameter of, for example, 3 to 8 cm, an upper open base with a larger diameter of, for example, 5 to 10 cm, and a height of, for example , from 5 to 15 cm. The typical weight of a coffee cup is from 5 to 20 g and usually about 10 to 12 g.

The sheet material is obtained from a degradable composition. As used in the following description, the term degradable means synthetic polymeric components that decompose into CO ₂ , H ₂ O, biomass and inorganic salts under conventional composting and other conditions. As can be understood, calcium carbonate does not decompose, but remains as an inert powder component after polymer degradation. Thus, the following discussion refers interchangeably to degradation of the composition and degradation of the polymer that forms the sheet structure. Advantageously, the sheets described herein are suitable for recycling because calcium carbonate and polyethylene masterbatch is often added to recycled materials to improve recycling. Thus, the high content of calcium carbonate does not interfere with processing. Due to the low polymer content, the sheets may even be suitable for composting under certain conditions.

The composition contains from 30 to 80 wt.% calcium carbonate relative to the weight of the composition. Calcium carbonate is a cheap, renewable material found in nature. It is widely used in personal care products, bleached paper, indigestion tablets, etc. When fired, it forms lime (calcium oxide), which is commonly added to drinking water. Calcium carbonate can be obtained from sources such as chalk deposits, sea shells, or eggshells. Preferably the composition contains from 50 to 75 wt.% and most preferably from 60 to 70 wt.% calcium carbonate.

The addition of calcium carbonate provides a stable end material that breaks down easily once decomposition has begun, is low cost, and has little environmental impact. The calcium carbonate has an average larger particle diameter, preferably 1 to 30 µm and more preferably 1 to 20 µm. This is desirable for good distribution throughout the bulk of the polymer and provides ease of processing of the composition, including extrusion.

Calcium carbonate is contained in the bulk of the polymer selected from polyethylene, polypropylene and their copolymers and blends. These polymers preferably comprise from 19 to 69% by weight of the composition, with additives and calcium carbonate making up the remainder. Preferably the polymer is high density polyethylene (HDPE). Preferably, the polymer has a melt flow index of 10 to 20 as this provides good processing of the calcium carbonate containing composition as described herein.

The incorporation of calcium carbonate into the polymer is known. For example, natural mineral paper (NMP) is a composite material that mainly contains up to 80% calcium carbonate (rock mineral) and an organic binder (HDPE).

- 4 039636

This material was invented in the 1970s and found use only in specialty markets such as art gift bags, labels, luggage tags and stationery.

In addition, the incorporation of calcium carbonate into polyolefins is currently popular because it can be used to reduce processing time and reduce costs by increasing the mass/volume of materials to reduce their cost. These materials may also have improved tensile properties and opacity properties. Masterbatches have now been developed that can improve recycling by improving the intercompatibility of different polymers, in particular in the case of three-layer or five-layer films containing a gas barrier layer.

The paper that forms natural mineral paper retains many of the properties of paper, such as crisp wrinkling and good ink retention, and is waterproof, tear-resistant, and much cheaper and cleaner to produce, which uses less energy and water and does not requires bleach. Many of the modern manufacturers claim that it is capable of decomposing under the influence of light, possibly due to impurities of iron (III) oxide that chalk contains, but they do not indicate the decomposition time, as a result of which this property does not expand the scope of possible applications. Modern generation stone paper (NMP) typically contains calcium carbonate and HDPE in a ratio of 80:20 in the case of sheets less than 300 µm thick (for printing paper applications, labels, paper-like bags, etc.). ) and 60:40 in the case of sheets with a thickness of more than 300 microns (for use as cards, glossy boxes, etc.).

The sheet material composition discussed herein may contain other solid particles in addition to calcium carbonate, as well as other ingredients described herein, such as solid particles of other metal carbonates and metal oxides. However, the presence of such additional solids is preferably less than 20% by weight, more preferably less than 5% by weight, and most preferably less than 1% by weight, based on the weight of the composition. According to a preferred embodiment, the composition consists of the ingredients described herein without any additional solid particles.

The polymer additionally contains an additive that is responsible for achieving the degradability of the composition. The amount of additive is described herein in relation to the combined weight of additive and polymer. In the practical preparation of a sheeting composition, the additive may be pre-formed as a masterbatch containing a certain amount of polyethylene, polypropylene and their copolymers and blends prior to mixing with the bulk polymer and calcium carbonate.

The additive contains two or more transition metal compounds in a total amount of 0.15 to 0.6% by weight, preferably 0.2 to 0.3% by weight, based on the combined weight of additive and polymer. As used in the following description, the term transition metal means any of the metal elements of groups IVB-VIII, III, IIB or 4-12 of the Periodic Table of the Elements. Preferred transition metals are iron, manganese, copper, cobalt and cerium; when iron is used, it is preferably present in the +3 oxidation state, and when copper is used, it is preferably present in the +2 oxidation state. These compounds catalyze decomposition. The introduction of large amounts of transition metals increases the cost of the degradable composition and can lead to the accumulation of transition metals in waste disposal sites. In addition, since the transition metal acts as a catalyst in the decomposition process, increasing the content of the transition metal above these values has the effect of reducing the decomposition rate.

The two or more transition metal compounds are selected from iron (preferably iron(III)) compounds, manganese, copper, zinc, titanium, cobalt and cerium, the transition metals in the two or more transition metal compounds being different.

Preferably the transition metal in the two or more transition metal compounds contains (i) iron, manganese and copper; or (ii) manganese and copper; or (iii) iron and manganese.

The temperature of the polymer composition and its exposure to light can also affect its rate of degradation. The present inventors have surprisingly found that the choice of transition metal can be used to further control these effects. In particular, the present inventors have found that iron is a more efficient catalyst in a photodecomposition process, while manganese is a more efficient catalyst in a thermal decomposition process. Thus, the transition metal component can be used to control the rate of decomposition depending on the intended exposure to heat and light for a particular product.

Specific transition metals can affect the properties of the polymer composition. For example, iron compounds can color the polymer composition.

In addition, other metals, such as copper, advantageously increase the degradation rate, but may render the polymer composition unsuitable for certain applications due to their toxicity. The use of iron may be omitted in color sensitive compositions.

The use of copper can be excluded in the food industry.

Preferably, the transition metal compounds contain moieties selected from stearate, carboxylate, acetylacetonate, triazacyclononane, or combinations of two or more of the above moieties. Preferably, the transition metal compounds may be present in a weight ratio of iron stearate and manganese stearate to copper stearate of 4:1 to 8:1. Preferably, the transition metal compounds may be present in a weight ratio of iron(III) stearate and manganese stearate to copper stearate of 4:1 to 8:1.

Alternatively or in addition, certain non-ionic ligands may also be present which play an active role in degradation. When non-ionic ligands are present, they are preferably selected from amines, imines, amides, phosphites, phosphines and carbenes. The present inventors have found that such non-ionic ligands can have an advantageous effect on composition degradation rates while maintaining essential material properties. Non-ionic ligands preferably comprise at least 5% of the ligands, preferably up to 50% of the ligands, and preferably from 10 to 40% of the ligands.

Preferably the transition metal ligands are chosen to make the transition metal physically and chemically compatible with the polymer. Advantageously, the choice of ligand can affect the catalytic activity of the transition metal. Ligands can be selected to make the metal compatible with the particular polyolefin used and to control the degradation rate of the polymer composition.

Preferably the ligands in the metal compounds are inorganic ligands and/or saturated organic ligands. Preferably, the ligands in the metal compounds are not mono- or polyunsaturated C14-C24 carboxylic acids or their esters, anhydrides or amides.

The additive contains a mono- or polyunsaturated C ₁ 4-C ₂ 4-carboxylic acid in an amount of 0.04 to 0.08% by weight, preferably 0.04 to 0.06% by weight, based on the combined weight of additive and polymer. Used in the following description, the term carboxylic acid means a number of compounds, the molecules of which contain a carboxyl group -COOH. The carboxylic acid according to the present invention is mono- or polyunsaturated and has a carbon skeleton containing from 14 to 24 carbon atoms, and at least one double bond is present in the carbon skeleton. The carbon skeleton of a carboxylic acid can be linear, branched, or aromatic. Preferably the mono- or polyunsaturated carboxylic acid is a C ₁₆ -C ₂₀ carboxylic acid. Preferred carboxylic acids are oleic, linoleic and cinnamic acids, the most preferred carboxylic acid is oleic acid.

Alternatively, the additive contains an ester, anhydride or amide of mono- or polyunsaturated C ₁ 4-C ₂ 4-carboxylic acid in an amount of from 0.04 to 0.08 wt.%, preferably from 0.04 to 0.06 wt. % based on the combined weight of additive and polymer.

The carboxylic acid or ester, anhydride or amide components are preferably free or uncoordinated in the sense that they do not form part of the transition metal compound.

When the additive contains an ester of a mono- or polyunsaturated C ₁ 4-C ₂ 4-carboxylic acid, the alcohol component is preferably a C ₁ -C ₃₀ alcohol, preferably a saturated straight chain C ₁ -C ₃₀ alcohol.

When the additive contains an anhydride mono - or polyunsaturated C ₁ 4-C ₂ 4-carboxylic acid, this anhydride may be symmetrical or unsymmetrical. The second carboxylic acid component is preferably a C ₁ -C ₃₀ carboxylic acid, more preferably a saturated straight chain C ₁ -C ₃₀ carboxylic acid.

When the additive contains an amide of a mono- or polyunsaturated C ₁ 4-C ₂ 4-carboxylic acid, this amide may be a primary, secondary or tertiary amide. When a secondary or tertiary amide is present, each of the carbon chains preferably contains from 1 to 30 carbon atoms, more preferably each carbon chain is a C ₁ -C ₃₀ alkyl group.

Unless otherwise specified, when carboxylic acids are discussed as features herein, they are also intended to cover the corresponding esters, anhydrides, or amides.

Without intending to be bound by theory, we believe that the mono- or polyunsaturated C14-C24 carboxylic acid in the polymer composition autoxidizes to form peroxides that can cleave bonds between carbon atoms in the polymer chain, subjecting the polymer to conventional degradation processes. Transition metals present catalyze autoxidation, increasing the rate

- 6 039636 decomposition of the composition.

The content of more than 0.08 wt.% mono - or polyunsaturated Cu-CM-carboxylic acid can make the polymer excessively sensitive to air. Excessive auto-oxidation of the carboxylic acid can create a relatively high concentration of peroxides and lead to rapid degradation of the polymer structure.

This can cause shelf life issues. On the other hand, the content of less than 0.04 wt.% mono - or polyunsaturated Cl ₄ -C ₂₄ -carboxylic acid can lead to a negligible rate of decomposition. The authors of the present invention have found that the content of from 0.04 to 0.08 wt.% mono or polyunsaturated Cl ₄ -C ₂₄ -carboxylic acid allows you to set the rate of decomposition at desired levels for numerous applications.

Surprisingly, the authors of the present invention found that linear monounsaturated acids, including, in particular, oleic acid, have the greatest impact on the rate of decomposition. This could not be assumed from the chemical stability of these compounds in pure form, since, as a rule, an increase in the number of double bonds in a carboxylic acid makes it more susceptible to oxidation.

The additive contains synthetic rubber in an amount of from 0.04 to 0.2 wt.%, preferably from 0.08 to 0.12 wt.%, most preferably about 0.1 wt.% in relation to the combined weight of additive and polymer. Used in the following description, the term rubber means viscous elastic polymers. Rubbers are amorphous polymers that exist at temperatures above their glass transition temperature. Preferably the rubber according to the present invention is an unsaturated rubber, more preferably the rubber according to the present invention is polyisoprene, styrene-isoprene, styrene-isoprene-styrene or a mixture of two or more of these polymers.

The rubber content can advantageously improve the mechanical properties of the resin composition. In addition, rubbers generally have less chemical resistance than bulk polyolefins. Accordingly, the rubber content can improve the degradation rate without adversely affecting the physical properties of the polymer. Thus, it appears to act as a co-catalyst.

Advantageously, the presence of synthetic rubber in the polymeric composition improves resilience. This helps counter the embrittlement of the polymer composition that other additives cause. A content of less than 0.04% synthetic rubber can render the polymer excessively brittle and unusable. Contents of more than 0.12% synthetic rubber may increase the degradation rate and may adversely affect the properties of the polymeric material. In addition, the content of synthetic rubber is believed to increase the rate of decomposition without the need to increase the content of transition metal, starch or carboxylic acid.

The additive optionally contains dry starch in an amount of from 0 to 20 wt.%, preferably from 0 to 10 wt.%, more preferably from 0.1 to 1 wt.% and most preferably from 0.1 to 0.4 wt.% in relation to to the combined weight of additive and polymer. Used in the following description, the term starch means a polysaccharide containing a large number (typically from 500 to 2,000,000 monomer units) of glucose units connected by glycosidic bonds. The starch of the present invention is dry starch. That is, the starch contains less than 5% by weight of water based on the weight of the starch, preferably less than 1% by weight of water, most preferably the starch is substantially free of water.

The content of starch in large quantities can increase the density and reduce the tensile strength of the polymer. In addition, high starch content can cause shelf life problems due to rapid degradation. The high content of starch makes the polymer containing it susceptible to deterioration in cosmetic and physical properties due to the action of water and microorganisms. If the starch content is insufficient, the additive may have little effect on the rate of biodegradation.

The additive optionally contains calcium oxide in an amount of 0 to 1% by weight, preferably 0 to 0.4% by weight, more preferably 0.1 to 0.3% by weight, based on the combined weight of additive and polymer. Used in the following description, the term calcium oxide means a crystalline solid having the chemical formula CaO. Advantageously, the calcium oxide reacts with and immobilizes the water in the composition. This stabilizes the composition during processing and can reduce the occurrence of surface defects and discoloration of the final product. In addition, to their surprise, the authors of the present invention unexpectedly found that increasing the content of calcium oxide in the polymer composition can increase the rate of decomposition. The predominantly contained CaO can be used to improve degradability without the need to increase the transition metal content of the starch. The content of more than 0.4 wt.% CaO leads to embrittlement of the polymer.

The additive optionally contains an oxygen generating additive. The oxygen producing additives may be organic or inorganic. Preferably as an oxygen producing

- 7 039636 additives choose nitrates, peroxides, sulfates and phosphates or combinations of two or more of these compounds. A preferred oxygen producing additive is calcium nitrate. Preferably, the oxygen generating additive is present in an amount of 0.1 to 1.0% by weight based on the combined weight of additive and polymer. It has been found that the oxygen producing additive further increases the rate of oxidation of the polymer.

The additive optionally contains a phenolic antioxidant stabilizer in an amount of 0 to 0.2% by weight, preferably 0.02 to 0.15% by weight. Phenolic antioxidant stabilizers are well known in the art and are, for example, Irganox 1076 and Irganox 1010. It has been found that the phenolic antioxidant stabilizer allows for improved control of polymer degradation time. In particular, the addition of a phenolic antioxidant stabilizer can delay the onset of degradation, increasing the shelf life of the product and the period during which the product can be processed in existing polyolefin processing lines.

Preferably, the additive further comprises a coloring additive such as, but not limited to, carbon black or titanium oxide.

Accordingly, the present invention provides a sheet material obtained from a composition based on a certain combination of ingredients that provide an ideal degradable composition.

The sheet material has an average thickness of preferably 100 to 500 µm and more preferably 200 to 400 µm.

According to one embodiment, the sheet material has a foam-containing structure. That is, sheeting can be obtained with trapped internal cavities that provide an insulation benefit to the consumer. The thickness of the foam may preferably be from 1000 µm to 10 cm.

According to a further aspect, a package or container is provided that is made from the sheet material as described herein.

According to a preferred embodiment of the coffee cup, preferably the cup comprises an additional component selected from the group consisting of a lid, a handle and a collar, said component also consisting of a degradable composition.

The present invention provides a coffee cup made from a composition based on a specific combination of ingredients that allows for an ideal disintegrating composition.

The cup has a wall thickness of 100 to 500 µm and preferably 200 to 400 µm.

According to one embodiment, the composition has a foam-containing structure. That is, a cup wall with entrapped internal cavities can be obtained, which provides the advantage of insulating the cup wall to prevent burns to the hands of the hot beverage consumer. The wall thickness of the foam cup may be 400 to 3000 µm, preferably 1000 to 2000 µm.

According to a further aspect, a method for producing a container is provided, the method comprising preparing a composition containing 30 to 80 wt % calcium carbonate, an additive and a polymer, molding the composition to form a container, wherein the polymer and additive are as described herein.

According to a further aspect, a method is provided for preparing a disposable coffee cup, the method comprising preparing a composition containing 30 to 80 wt % calcium carbonate, an additive and a polymer, molding the composition to form a coffee cup, wherein the polymer and additive are as described in this document.

According to the above embodiments, the preparation step typically comprises mixing the components, optionally with an additive present in the concentrated masterbatch, to form a composition.

Preferably, the step of molding the composition into a container or coffee cup comprises molding the composition into a container configuration or forming and molding one or more sheets of the composition into a container configuration and optionally fixing the configuration by heat sealing or gluing or 3D printing.

Preferably, the preparation is carried out by molding, such as thermoforming, injection molding, injection blow molding or compression molding. Alternatively, the molding may include folding techniques. This may involve heat sealing under pressure. Due to the polymer content, this can advantageously be achieved without the use of a binder.

Preferably, the method is for making a container or coffee cup as detailed above.

According to a further aspect, a method is provided for initiating chemical degradation of a package or container as described herein, the method comprising exposing the sheet material to temperatures in excess of 50°C, preferably by placing a hot beverage or food product in the container, or by exposing the container to microwave heating. . That

- 8 039636 there is a composition described in this document is heat sensitive, and as a result of this, the use of a container, for example to contain a hot drink, initiates decomposition. Degradation is slow and therefore the container or package continues to serve its intended purpose but degrades over the next few weeks after application. Preferably primary degradation occurs substantially within 6 weeks, preferably within 4 weeks, and secondary microbial degradation occurs substantially within 1 year, preferably within 6 months.

The primary degradation/degradation described herein preferably occurs within 2 to 6 weeks and can be demonstrated under fugitive emissions (roadside or wasteland), soil and aerobic composting. Typically, primary decomposition compromises the structural integrity of the container such that it is no longer suitable for its original purpose. Microbial degradation of materials occurs within 6 months to 1 year, provided that the sheet material is in an environment with suitable microorganisms. After decomposition, the materials turn into white chalk powder.

According to a further aspect, a method is provided for initiating chemical decomposition of a disposable coffee cup as described herein, the method comprising exposing the coffee cup to temperatures in excess of 50°C, preferably by placing a hot beverage in the coffee cup. That is, the composition described herein is heat sensitive, and as a result, the use of a cup to contain a hot beverage initiates decomposition. Decomposition is slow and therefore the cup continues to serve its intended purpose, but decomposes over the next few weeks after use. Preferably, primary degradation occurs substantially within 6 weeks, preferably within 4 weeks, and secondary microbial degradation occurs substantially within 1 year, preferably within 6 months.

According to another aspect, the use of an additive for initiating the decomposition of a sheet material (or coffee cup) containing the aforementioned additive after exposure to temperatures in excess of 50°C is provided, wherein the composition of the additive and the sheet material is as described herein. Preferably, exposure to temperatures in excess of 50°C includes contacting the sheet material with a hot beverage or food product, or exposing the sheet material (or coffee cup) to microwave heating.

The sheet material of the present invention is intended to solve the problem of improper disposal of packages and containers such as coffee cups. When containers are considered recyclable by consumers, it is advantageous that the present invention provides a recyclable material that can be incorporated into standard recycling processes because the ingredients are compatible with other recyclable materials. When consumers consider the containers to be made from plain paper and capable of naturally degrading when thrown into a ditch, it is advantageous that the present invention provides a degradable material that will degrade rapidly under such conditions.

Examples of specific applications for the sheet material discussed in this document are paper plates, food/drink cartons, packaging paper, food labels, horticultural/agricultural labels, drink straws, business cards, souvenir boxes and bags, similar to paper. These examples are particularly suitable for cast films. Other uses are disposable cutlery, disposable containers such as flower pots, yoghurt cups, takeaway food containers, and cups with lids for hot/cold drinks, which can be produced by thermoforming techniques. The following uses are degradable shopping bags, trash bags, seed/grain bags, cement bags and silage wraps, as well as food wraps such as burger wraps, all of which can be made from blown films. Foam compositions can be used that provide for single use of insulating beverage/food containers, packaging materials, insulation, temporary plastic seats, bicycle seats, or bicycle helmets. Advantageously, the material can be easily printed.

All percentages used in the present description are weight ratios unless otherwise specified.

For the avoidance of doubt, an example of relative amounts is provided. In a composition containing 50 wt.% calcium carbonate, 1 wt.% additive and polymer constituting the remainder (49 wt.%), the additive component, which is 0.5 wt.% of the combined weight of polymer and additive, is 0.25 wt.% relative to the total weight of the composition.

Hereinafter, the present invention will be described with respect to the following non-limiting figures.

In FIG. 1 shows an exemplary container.

In FIG. 2 shows an exemplary coffee cup and lid.

- 9 039636

Hereinafter, the present invention will be described with respect to the following non-limiting examples.

Examples

An exemplary sheet composition is described below.

Exemplary Composition of NMP Thermoformed Articles

A sheet for molding a container (coffee cup) was obtained from a composition containing a polyolefin that is HDPE or polypropylene (PP), a PE/PP copolymer or blend with a melt flow index of 10 to 30 g/10 min, and calcium carbonate with a particle size of 1 up to 30 microns. To this composition was added a masterbatch composition (0.2-5%), which is a mixture containing metal stearates and other carboxylates, a pro-oxidant such as metal nitrates and phosphates, calcium oxide, metal carbonates, dry starch and unsaturated rubber. For coloring, carbon black or other pigments can be added, the content of which is from 0.1 to 10%.

Exemplary composition for blown film products

The sheet for molding the container was obtained from a polyolefin, which is HDPE, LLDPE or PP, a copolymer or mixture with a melt flow index of 0.2 to 2 g/10 min and containing calcium carbonate with a particle size of 1 to 30 μm and an additive composition constituting from 0.1 to 5% and representing the aforementioned mixture of metal stearates, with the addition of carbon black as a dye.

An exemplary composition for polypropylene foam products

A polypropylene foam resin was obtained containing from 30 to 50% calcium carbonate with an average particle diameter of 0.1 to 5 μm, as well as from 0.1-5% of the additive described in this document and containing dry starch, unsaturated rubber and a mixture of catalysts for metal base. This resin was molded into a coffee cup.

Specific Compositions

The following compositions have been used to produce a plastic suitable for making a coffee cup through the addition of HDPE and calcium carbonate. Calcium carbonate was 50 wt.% of the mixture, and HDPE was 48 wt.% of the mixture. The cups have been tested under harsh atmospheric conditions and show rapid degradation. In addition, the cups produced a good paper feel and suitable strength for the intended application.

Composition 1

Received the composition of the additive, which was

i) dried starch - 10.00% by weight;

ii) manganese stearate - 4.00 wt.%;

iii) iron(III) stearate - 8.00 wt.%;

iv) copper stearate - 1.30% by weight;

v) oleic acid - 2.00% by weight;

vi) styrene-isoprene-styrene (SIS)/styrene-isoprene (SI) copolymer - 4.00% by weight;

vii) calcium oxide - 10% by weight;

viii) linear low density polyethylene (LLDPE) - 60.70 wt.%.

Composition 2

Received the composition of the additive, which was

i) dried starch - 10.00% by weight;

ii) manganese stearate - 2.00% by weight;

iii) iron(III) stearate - 10.00% by weight;

iv) Irganox 1076 - 13.0% by weight;

v) oleic acid - 1.00% by weight;

vi) SIS/SI copolymer - 2.00% by weight;

vii) calcium oxide - 10.00% by weight;

viii) LLDPE - 52.0 wt%.

Composition 3

Received the composition of the additive, which was

i) dried starch - 10.00% by weight;

ii) manganese stearate - 4.00 wt.%;

iii) copper stearate - 8.00% by weight;

iv) oleic acid - 6.00% by weight;

v) SIS/SI copolymer - 2.00% by weight;

vi) LLDPE - 70.00% by weight

Exemplary compositions 1, 2 and 3 were obtained by hot extrusion of components ii)-viii) and subsequent separate addition of starch. By separately adding starch, it can be added after the heating steps, preventing damage to the structure.

Composition 4

Received the composition of the additive, which was

i) manganese stearate - 4.00% by weight;

- 10 039636 ii) iron(III) stearate - 8.00 wt.%;

iii) copper stearate - 1.30% by weight;

iv) oleic acid - 6.00% by weight;

v) SIS/SI copolymer - 1.00% by weight;

vi) calcium oxide - 10.00% by weight;

vii) LLDPE - 69.70% by weight

Composition 5

Received the composition of the additive, which was

i) manganese stearate - 4.00% by weight;

ii) iron(III) stearate - 8.00% by weight;

iii) copper stearate - 1.30% by weight;

iv) oleic acid - 2.00% by weight;

v) SIS/SI copolymer - 1.00% by weight;

vi) calcium oxide - 10.00% by weight;

vii) Irganox 1076 - 10.00% by weight;

viii) LLDPE - 63.70% by weight

Exemplary compositions 4 and 5 were obtained by hot extrusion of the components.

The compositions are summarized below.

one 2 3 4 5 i) Dried starch 10.0 10.0 10.0 i) Manganese stearate 4.0 2.0 4.0 4.0 4.0 iii) Iron(III) stearate 8.0 10.0 8.0 8.0 iv) Copper Stearate 1.3 8.0 1.3 1.3 v) Oleic acid 2.0 ι, ο 6.0 6.0 2.0 vi) SIS/SI copolymer 4.0 2.0 2.0 ι, ο ι, ο vii) Calcium oxide 10.0 10.0 10.0 10.0 viii) LLDPE 60.7 52.0 70.0 69.7 63.7 ix) Irganox 1076 13.0 10.0

Although the present document describes in detail the preferred embodiments of the present invention, those skilled in the art should understand that appropriate changes may be made without departing from the scope of the present invention or the appended claims.

CLAIM

Claims (21)

CLAIM 1. Sheet material obtained from a decomposing composition, and the composition contains from 30 to 80 wt.% calcium carbonate relative to the weight of the composition; additive; the remaining polymer selected from polyethylene, polypropylene and their copolymers and mixtures, and the additive contains in relation to the combined mass of additive and polymer: (a) two or more transition metal compounds in a total amount of from 0.15 to 0.6 wt.%, where the transition metal compounds contain a stearate moiety; (b) mono - or polyunsaturated C ₁₄ -C ₂₄ -carboxylic acid in an amount of from 0.04 to 0.08 wt.%; (c) synthetic rubber in an amount of 0.04 to 0.2% by weight; wherein the two or more transition metal compounds are selected from iron, manganese, copper, and wherein the transition metals in the two or more transition metal compounds are different; where the transition metals in two or more transition metal compounds contain: (i) iron, manganese and copper; or (ii) manganese and copper; or (ii i) iron and manganese. 2. Sheet material according to claim 1, in which the composition further comprises (d) dry starch in an amount of up to 20 wt.%. 3. Sheet material according to claim 1, in which the composition further comprises (e) calcium oxide in an amount of up to 1 wt.%. 4. The sheet material of claim 1, wherein the composition further comprises (f) a phenolic anti- - 11 039636 oxidant stabilizer in an amount up to 0.2 wt.%. 5. Sheet material according to claim 1, in which the composition contains from 60 to 70 wt.% calcium carbonate, and while calcium carbonate preferably has an average larger particle diameter of from 1 to 30 microns. 6. Sheet material according to any of the preceding claims, having an average thickness of 100 to 500 µm, preferably 200 to 400 µm. 7. Sheet material according to any one of claims 1 to 5, wherein the composition has a foam structure. 8. Sheet material according to any one of the preceding claims, wherein the composition further comprises (g) an oxidizing agent, preferably calcium nitrate. 9. Sheet material according to any of the preceding claims, wherein the mono- or polyunsaturated C ₁ 4-C ₂ 4 carboxylic acid is a linear C ₁₆ -C ₂₀ carboxylic acid, preferably oleic acid. 10. Sheet material according to any one of the preceding claims, wherein the synthetic rubber comprises an unsaturated polymer, preferably styrene-isoprene-styrene, more preferably a mixture of styrene-isoprene-styrene and styrene-isoprene copolymers. 11. Sheet material according to any one of the preceding claims, wherein the polymer is high density polyethylene (HDPE), preferably having a melt flow index of 10 to 20 g/10 min. 12. Sheet material according to any one of the preceding claims, wherein the composition comprises, relative to the combined weight of additive and polymer: (a) two or more transition metal stearates in a total amount of 0.2 to 0.3% by weight; and/or (b) monounsaturated linear C ₁₆ -C ₂₀ -carboxylic acid in an amount of from 0.04 to 0.06 wt.%; and/or (c) synthetic rubber in an amount of 0.08 to 0.12% by weight; and/or (d) dry starch in an amount of 0.1 to 0.4% by weight; and/or (e) calcium oxide in an amount of 0.1 to 0.3% by weight; and/or (f) calcium nitrate in an amount of 0.1 to 1.0% by weight. 13. A package obtained from the sheet material according to any one of the preceding claims. 14. A container obtained from the sheet material according to any one of the preceding claims. 15. A disposable coffee cup made from the sheet material of any one of the preceding claims. 16. The method of obtaining a container, and the method includes obtaining a composition containing from 30 to 80 wt.% calcium carbonate in relation to the mass of the composition, a polymer and an additive, molding the composition to obtain a container, the polymer being selected from polyethylene, polypropylene and their copolymers and mixtures , and at the same time the additive contains in relation to the combined mass of additive and polymer: (a) two or more transition metal compounds in a total amount of from 0.15 to 0.6 wt.%, where the transition metal compounds contain a stearate moiety; (b) mono - or polyunsaturated C ₁ 4-C ₂ 4-carboxylic acid in an amount of from 0.04 to 0.08 wt.%; (c) synthetic rubber in an amount of 0.04 to 0.2% by weight; wherein the two or more transition metal compounds are selected from iron(III), manganese, copper compounds, and wherein the transition metals in the two or more transition metal compounds are different; where the transition metals in two or more transition metal compounds contain: (i) iron, manganese and copper; or (ii) manganese and copper; or (iii) iron and manganese. 17. The method of claim 16 wherein the step of molding the composition to form a container comprises: (a) molding the composition into a container configuration, preferably by thermoforming, injection molding, injection blow molding, or compression molding; or (b) obtaining and molding one or more sheets of the composition into a container configuration and optionally fixing the configuration by heat sealing or gluing; or (c) 3D printing. 18. A method according to claim 16 or 17, wherein the method is for producing a container according to claim 14 or a disposable coffee cup according to claim 15. 19. A method for initiating chemical decomposition of a package according to claim 13, or a container according to claim 14, or a disposable coffee cup according to claim 15, the method comprising subjecting the sheet material to temperatures in excess of 50°C by contacting the sheet material with hot beverage or food or by exposing the sheet material to microwave heating. 20. The method of claim 19 wherein primary degradation occurs within 6 weeks and secondary microbial degradation occurs within 1 year. - 12 039636 21. The use of an additive to initiate the decomposition of the sheet material after exposure to temperatures exceeding 50°C, and the sheet material is obtained from a composition containing from 30 to 80 wt.% calcium carbonate relative to the mass of the composition; additive; the remaining polymer selected from polyethylene, polypropylene and their copolymers and mixtures, and the additive contains in relation to the combined mass of additive and polymer: (a) two or more transition metal compounds in a total amount of 0.15 to 0.6 wt.%, where the transition metal compounds contain a stearate moiety; (b) mono- or polyunsaturated C14-C24 carboxylic acid in an amount of from 0.04 to 0.08% by weight; (c) synthetic rubber in an amount of 0.04 to 0.2% by weight; wherein the two or more transition metal compounds are selected from iron, manganese, copper, and wherein the transition metals in the two or more transition metal compounds are different; where the transition metals in two or more transition metal compounds contain: (i) iron, manganese and copper; or (d) manganese and copper; or