Technical field of the invention

The present invention relates to the field of pelleted materials for injection moulding.

Background of the invention

In Europe, 52 billion disposable cups are sold annually, either produced in plastic or surface-treated with plastic. This makes the cups difficult to degrade both in industry and nature (up to 80 years even for the surface treated cups). After use, the disposable cups are mostly burned. Even the surface-treated cups are burned as the separation of cardboard and plastic is an expensive process that requires special machinery.

Many of the disposable cups end up in the nature. It is estimated that up to 20 tonnes of coffee cups are thrown from the cars on Danish highways every year and 900,000 cups end up in the Danish marine environment every year. This number is increasing. The plastic from the disposable cups results in micro- and nanoplastics. The over-consumption of materials and inappropriate disposal of waste, such as disposable cups, is not sustainable. Already now we can see a shortage of cups worldwide due to a growing consumption as well as fewer resources. This has resulted in disposable cups that are halved in thickness resulting in a weaker cup. In Denmark alone, more than 143 million disposable coffee cups are yearly sold in cafes (35% of the total disposable cup consumption) and the market has grown by 2% annually in recent years. Hence, there is a great need for sustainable initiatives and better utilization of natural resources in the coffee industry.

Description of the invention

Millions of tons of coffee grounds are used to make coffee worldwide each day, creating huge amounts of waste material. The present invention may advantageously reduce this waste by providing a second use for otherwise worthless used coffee grounds once they have fulfilled their primary purpose by being used to make coffee. The present invention may advantageously reduce the quantity of plastics used in article manufacture, e.g., cup manufacture, by replacing the plastic material with used coffee grounds and by substituting oil derived plastics with biodegradable thermoplastic polymer. The inventors of the present invention have surprisingly found that no adhesive is needed to bind the biodegradable thermoplastic polymer together with the used coffee grounds when the used coffee grounds have a maximal water content of at most 10% w/w, preferably of at most 5% w/w, and most preferably at most 2% w/w. When used as a pelleted material for injection moulding, the inventors have surprisingly found that the used coffee grounds must have a maximal water content of at most 2% w/w as the composition otherwise breaks the mould during the moulding process.

The inventors have found that a maximal water content of at most 2% w/w is only obtainable if the majority of the oil present in the used coffee grounds is removed first. Normally the water content in used coffee grounds is up to about 70% w/w. It may be oven dried to about 5-10% w/w. The oven dried used coffee grounds have an oil content of about 10-20% w/w. The oil mainly consists of fatty acids, with most of the fatty acids being in the form of glycerides, mainly triglycerides. Depending on the extraction process, the triglycerides are degraded into diglycerides, or monoglycerides. Hexane as an extraction solvent has shown to be particularly gentle, resulting in very little degradation of the triglycerides and in a better removal of the oil component. Ethanol is also suitable, but the oil yield is lower than for hexane, and the ethanol performs best when anhydrous. The extraction may e.g., be performed at 20-30 degrees Celsius for 20-60 minutes. The use of supercritical carbon dioxide has also shown promising results, e.g., with hexane, acetone and/or ethanol as co-solvents. Both types of extraction processes are well-known within the art of extraction.

A first aspect relates to a method for the production of a pelleted material for injection moulding comprising the steps of: a) Providing a composition consisting of:

- 20-80% w/w of a biodegradable thermoplastic polymer;

- 20-80% w/w of used coffee grounds;

- 0-10% w/w inorganic fillers and/or dyes; b) Processing the mixed material to form a pelleted material. Preferably, the used coffee grounds have been pre-processed by oil extraction, and a subsequent dehydration step.

A second aspect relates to a disposable beverage container, preferably a drinking container, with a base and side wall each having an inner surface and an outer surface, said base and side wall made from a composition comprising:

- 20-80% w/w of a biodegradable thermoplastic polymer;

- 20-80% w/w of used coffee grounds; and

- 0-10% w/w inorganic fillers and/or dyes.

A third aspect relates to a pelleted material for injection moulding produced by the method according to the present invention.

A fourth aspect relates to a pelleted material for injection moulding consisting of:

- 20-80% w/w of a biodegradable thermoplastic polymer;

- 20-80% w/w of used coffee grounds;

- 0-10% w/w inorganic fillers and/or dyes; wherein the used coffee grounds have been pre-processed by oil extraction, and a subsequent dehydration step.

A fifth aspect relates to a method for the production of a disposable beverage container comprising the steps of: a) Providing a pelleted material according to the present invention; and b) Filling said composition into a mould to form a shaped disposable beverage container.

The term "used coffee grounds" refers to ground coffee beans once they have been used to make coffee. Used coffee grounds may alternatively be termed "recycled coffee grounds" or "waste coffee grounds". The term “thermoplastic polymer” is used to refer to a polymeric material, which will melt upon exposure to sufficient heat to form a flowable liquid and will return to a solidified state upon sufficient cooling.

The term “biodegradable polymer” refers to a polymer, which will be broken down into organic substances by living organisms, for example, microorganisms.

Preferred biodegradable thermoplastic polymers are e.g., polyhydroxyalkanoates (PHAs), such as PHBV (Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly-3- hydroxy butyrate (PHB), polyhydroxyvalerate (PHV), and polyhydroxyhexanoate (PHH), polylactic acid (PLA), and biodegradable starch blends, such as starch/polylactic acid, starch/polycaprolactone, and starch/polybutylene-adipate-co- terephthalate. The most preferred biodegradable thermoplastic polymer is poly(3- hydroxybutyrate-co-3-hydroxyvalerate.

In one or more embodiments, the used coffee grounds have a maximal water content of at most 2% w/w, preferably of at most 1 % w/w.

In one or more embodiments, the oil extraction is performed with supercritical carbon dioxide, preferably together with a co-solvent, such as hexane, isopropanol, or ethanol.

In one or more embodiments, the oil extraction is performed with anhydrous ethanol, isopropanol, or hexane, preferably at atmospheric pressure.

Both extraction methods may preferably be performed at 20-60 degrees Celsius.

In one or more embodiments, the used coffee grounds have an oil content of less than 5% w/w, such as within the range of 0-5% w/w, e.g., within the range of 0.01- 4% w/w, such as within the range of 0.05-3% w/w, e.g., within the range of 0.1-2% w/w, such as within the range of 0.5-1 % w/w, preferably less than 1% w/w. In one or more embodiments, the used coffee grounds have a glyceride content of less than 5% w/w, such as within the range of 0-5% w/w, e.g., within the range of 0.01-4% w/w, such as within the range of 0.05-3% w/w, e.g., within the range of 0.1- 2% w/w, such as within the range of 0.5-1% w/w, preferably less than 1% w/w.

In one or more embodiments, the used coffee grounds have a fatty acid content of less than 5% w/w, such as within the range of 0-5% w/w, e.g., within the range of 0.01-4% w/w, such as within the range of 0.05-3% w/w, e.g., within the range of 0.1- 2% w/w, such as within the range of 0.5-1% w/w, preferably less than 1% w/w.

In one or more embodiments, the base and side wall is made from a composition consisting of:

- 20-80% w/w of a biodegradable thermoplastic polymer;

- 20-80% w/w of used coffee grounds; and

- 0-10% w/w inorganic fillers and/or dyes.

In one or more embodiments, the biodegradable thermoplastic polymer is present in an amount of within the range of 25-75% w/w of the composition, such as within the range of 30-70% w/w of the composition, preferably within the range of 35-65% w/w of the composition, and even more preferably within the range of 40-60% w/w of the composition, such as about 50% w/w of the composition.

In one or more embodiments, the used coffee grounds are present in an amount of within the range of 25-75% w/w of the composition, such as within the range of 30- 70% w/w of the composition, preferably within the range of 35-65% w/w of the composition, and even more preferably within the range of 40-60% w/w of the composition, such as about 50% w/w of the composition.

In one or more embodiments, the biodegradable thermoplastic polymer and the used coffee grounds are in total present in an amount of within the range of 80- 100% w/w of the composition, such as within the range of 85-99% w/w of the composition, e.g., within the range of 90-95% w/w of the composition.

In one or more embodiments, the base and side wall are made from a composition consisting of: - 20-80% w/w of a biodegradable thermoplastic polymer; and

- 20-80% w/w of used coffee grounds.

Used coffee grounds have strong thermal properties that make the cup thermoefficient, even with walls of a relatively thin thicknesses. To obtain such an effect, the used coffee grounds should be present in an amount of at least 20% w/w of the composition, such as within the range of 20-80% w/w of the composition, preferably, in an amount of at least 30% w/w of the composition, such as within the range of 35- 75% w/w of the composition.

The cup may be coated with a layer (relatively thin compared to the wall thickness of the cup, e.g., 5-100 micrometres in thickness) such that the cup can be approved for food contact in some regions or countries.

In one or more embodiments, the inner surface of the beverage container’s base and side wall is coated with a biodegradable thermoplastic polymer, preferably a polyhydroxyalkanoate-type polymer, free from used coffee grounds, more preferably pure poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

In one or more embodiments, the coating has a thickness of within the range of 5- 100 micrometres, such as within the range of 10-90 micrometres, e.g., within the range of 15-80 micrometres, such as within the range of 20-70 micrometres, e.g., within the range of 25-60 micrometres, such as within the range of 30-55 micrometres, e.g., within the range of 35-50 micrometres,

In one or more embodiments, the beverage container’s side wall is of a thickness within the range of 0.5-3 mm, preferably within the range of 0.9-1.5 mm, such as about 1 mm.

In one or more embodiments, the beverage container is adapted for hot drinks, such as coffee, chocolate, or tee.

Another aspect relates to a method for the production of a disposable beverage container comprising the steps of: a) Providing a composition comprising:

- 20-80% w/w of a biodegradable thermoplastic polymer;

- 20-80% w/w of used coffee grounds;

- 0-10% w/w inorganic fillers and/or dyes; and b) Filling said composition into a mould to form a shaped disposable beverage container.

Preferably, step b) includes shaping the disposable beverage container using injection moulding.

In one or more embodiments, the composition is provided in the shape of pellets suitable for injection moulding.

In one or more embodiments, the injection moulding process included cooling with gas, such as air, nitrogen, carbon dioxide, or mixtures thereof.

Yet another aspect relates to a method for the production of a pelleted material for injection moulding, the method comprising the steps of: a) providing a composition consisting of:

- 20-80% w/w of a biodegradable thermoplastic polymer;

- 20-80% w/w of used coffee grounds;

- 0-10% w/w inorganic fillers and/or dyes; and b) processing the mixed material to form a pelleted material.

In one or more embodiments, step b) includes cooling with gas, such as air, nitrogen, carbon dioxide, or mixtures thereof.

Still another aspect relates to a pelleted material for injection moulding consisting of:

- 20-80% w/w of a biodegradable thermoplastic polymer;

- 20-80% w/w of used coffee grounds;

- 0-10% w/w inorganic fillers and/or dyes.

As used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and/or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about", it will be understood that the particular value forms another embodiment.

It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

Detailed description of the invention

The following description is to be seen as non-limiting examples of a disposable beverage container according to various embodiments of the present invention.

Examples

EXAMPLE 1 :

Determination of the optimal conditions for producing a disposable drinking cup Materials for the production of a disposable coffee cup were carefully selected according to the properties and effects they add to the cup. The disposable coffee cup was developed with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and used coffee grounds. PHBV is ideal as a virgin plastic substitute due to its short degradability to carbon dioxide and water, as it is produced by plants or bacteria. Studies show that the material nourishes the soil in which it is broken down, as the material fertilizes the same bacteria that are used to produce the PHBV.

The inventors have found that the produced disposable coffee cup can decompose in nature in 3-4 months as compared to pure PHBV that can decompose in nature, in the same thicknesses as the cup, in about 6 months. This result is comparable to an orange peel that decomposes in 4 months.

PHBV is a food contact approved material that makes it possible to create a cup comprising coffee grounds that can be used to hold coffee.

PHBV has a relatively low melting point of about 153 degrees Celsius (compared to traditional plastic, such as polystyrene of about 240 degrees Celsius) and flows easily, making it optimal for mixing with coffee grounds as the coffee grounds would otherwise be burned.

Used coffee grounds were selected for use in the coffee cup due to its many positive properties. Used coffee grounds will be able to add value throughout the full life cycle of a disposable coffee cup. Used coffee grounds are currently thrown away as waste. PHBV is a very flexible material and a cup made only from this material would become too fragile. The used coffee grounds strengthen or stiffen the cup and make it durable for hot drinks. Used coffee grounds have strong thermal properties that make the cup thermo-efficient, even with walls of a relatively thin thicknesses. This makes it possible to create a cup that is competitive on both price, weight, and surpasses the competition in quality. The density of used coffee grounds (when dried) is three times lower than the normally used virgin plastic, which significantly reduces the weight taxes on the cups. Furthermore, used coffee grounds showed to significantly promote the degradation of the PHBV. Finally, used coffee grounds act as a natural fertilizer and are used in many commercial fertilizer products as they contain nitrogen, phosphorus, potassium, and some minerals that all nourish plants.

To produce a disposable coffee cup, the composition must first be processed for use with injection moulding, preferably as a pelleted product. The used coffee grounds are received wet (about 20-50% w/w water) and PHBV is received as raw material in pellet form. In general, it would be expected to use a binder/adhesive to incorporate the used coffee grounds into the thermoplastic polymer as they are not easily miscible as such. However, the inventors of the present invention found that if the used coffee grounds are dried to a water content of at most 10% w/w, the coffee grounds can be equally distributed within the PHBV. Preferably, the used coffee grounds are dried to a water content of at most 5% w/w, and most preferably to a water content of at most 2% w/w, which makes the composition much easier to process into pellets. A further advantage of the drying step is that the coffee grounds are dried to a stage dry enough to stop the degradation processes. This can e.g., be done during drying at room temperature, of the coffee grounds distributed in fine layers. As described above, the step of drying the used coffee grounds to 2% w/w water or below requires that the majority of the oil is removed prior to the last drying step. This may be performed with extraction as described above. Preferably, at most 1-4% w/w is left of the oil in the used coffee grounds after the oil extraction step.

After drying of the used coffee grounds, it is mixed with PHBV to form a composite material. The mixing process is performed by melting PHBV the used coffee grounds are mixed in. The mixture is processed through a screw extruder to finally be cut out into pellet form. During the process, the material is cooled. Air cooling is used, contrary to normal water/liquid cooling, to avoid that the coffee grounds will absorb water/liquid, which would result in a useless composition unsuitable for forming pellets.

Once the pellets are produced, injection moulding is used to shape the cup. Thermoforming was initially tried without success. In the injection moulding process, the material is melted and pressed into a mould with the desired design. Compared to thermoforming, this process induces less pressure on the material, which makes a higher content of coffee grounds possible, i.e., 20-80% w/w. The size of the coffee grounds particles is in general not that important, but for the production of cups with a wall thickness of about 1 mm, the particle size should be less than 0.6 mm.

The cup may be coated with a layer (relatively thin compared to the wall thickness of the cup, e.g., 5-100 micrometres in thickness) such that the cup can be approved for food contact in some regions or countries. This can e.g., be performed as part of the injection moulding process or as a subsequent independent process. For this purpose, the biodegradable thermoplastic polymer, such as e.g., PHBV, may preferably be used in pure form as this or these materials are approved for food contact.

At present, compositions comprising 30-60% w/w coffee grounds have shown to be particularly suitable for producing disposable coffee cups with a wall thickness of about 1 mm.