FIELD OF THE INVENTION

This invention relates to a grease, oil, alkaline, dry soap, water and water vapour transmission barrier coating composition, with or without an aesthetic pigment, for coating of paper-based products used for the packaging, transport, holding, display or consumption of consumables, and to paper-based products coated with the barrier coating composition of the invention. The invention further relates to a method for manufacturing such a barrier coating composition and a method of producing barrier composition coated paper-based products. In particular the barrier composition coated paper-based products are provided as a replacement for polystyrene, expanded polystyrene or other plastic containers.

BACKGROUND OF THE INVENTION

Expanded polystyrene foam, is a plastic material, that has special/specific properties owing to its structure. The structure which is composed of individual cells of low-density polystyrene is extraordinarily lightweight, approximately 95% air, but can support many times its own weight. Owing to the structure of the individual polystyrene cells, i.e. not being interconnected, neither heat nor cold can travel through the expanded cells easily. Expanded polystyrene functions as an efficient insulator and is therefore used in flotation devices, insulation, egg trays, fast foods trays, vegetable trays, fruit, and meat trays, but are not limited to these areas of application. Polystyrene trays and containers are sometimes also generically referred to as ‘Styrofoam’, although STYROFOAM® in fact refers specifically to a type of hard aesthetic, expanded polystyrene foam, used mainly in boating.

Functionally, expanded polystyrene trays are extremely fit for purpose, however, the concern is that expanded polystyrene effectively never goes away. Expanded polystyrene containers being an inexpensive product occurs more commonly in our environment than all plastics with the exception of polyethylene. Once the packaged product is consumed, the expanded polystyrene container is disposed into waste and owing to its poor degradability, ubiquitously occurs in the environment, and oceans. In landfill, expanded polystyrene containers are covered by earth which deprives the degradation process which typically requires oxygen and water, as necessary components to influence the disposed containers rate of degradation. Furthermore, expanded polystyrene containers are resistant to photolysis, which is the breaking down of materials by photons originating from a light source.

Unfortunately, expanded polystyrene containers disposed in the environment, owing to their extremely lightweight and buoyant properties, also readily travel through gutters and stormwater channels, eventually reaching the ocean. Travelling through the waterways, the expanded polystyrene containers readily break down into smaller, non-biodegradable, non- compostable pieces. Owing to the porous nature of expanded polystyrene, other carcinogenic pollutants in seawater are absorbed and ingested by marine life which either harms or results in their death, through starvation, induced by blockage of stomach and digestive system with consumed expanded polystyrene particles. The finer particles which sink to the ocean beds and are consumed by sea creatures and fish which when consumed by humans can cause harm through bioaccumulation in vital organs. As the result several coastal cities, especially in the US have banned the use of expanded polystyrene containers.

Incineration of these containers releases carbon monoxide and styrene monomers into the environment, which can be a human and animal health respiratory hazard. Also, polystyrene contains toxic substances including benzene, with suspected carcinogens and neurotoxins that are hazardous to human health. Contact of the packaging material with certain foods and heat initiates partial breakdown of the expanded polystyrene foam, causing some toxins to be leached into food which is absorbed into the bloodstream and tissues when food is consumed from these containers. Consumption of food from expanded polystyrene containers are known to cause adverse health effects in humans and animals, styrene is known to exhibit toxicity to humans as a neurotoxin by attacking the central nervous and peripheral nervous system. The accumulation of these highly lipid-soluble materials in the lipid rich tissues of the brain, spinal cord and peripheral nerves is correlated with acute or chronic functional impairment of the nervous system. Furthermore, dioxins that are used in the manufacturing of polystyrene are known to cause immune and hormonal concerns, and repeated exposure can affect foetal development. This is an occupational hazard to workers receiving regular exposure.

According to “Scientific American”, research advises that 28,500 tons of expanded polystyrene was produced in 2014, for single use containers, of which the majority, >90%, continues to reside in our environment. Although the world is aware of the detrimental effects of expanded polystyrene containers on the environment, not everyone is aware that expanded polystyrene waste has become a pollution pandemic which will last forever and that several thousands of years will be necessary for the container to decompose completely.

Expanded polystyrene waste, will not be adequately recovered from the environment and is not classified as degradable, bio-degradable or compostable, cannot be incinerated and only approximately 1% of the 1 1 billion kg disposed each year are recycled into concrete, egg trays, foam insulation, office products and garbage cans.

To fully understand the difference between disintegration, biodegradation and compostability:

Disintegration:- the total wrapper should degrade, per conditions described in EN14045, to less than 10% of the original weight and residues should be approximately 2mm in diameter;

Bio-Degradability: - refers to the biological, aerobic, or anaerobic decomposition of the wrapping material into CO2, water, and minerals. Importantly are the conditions and time, EN14046 describes biodegradability of 90% within 6months, under specific conditions; and

Compostabilitv:- refers, to disintegration and biodegradability as described above and that the wrapping material should have no negative effect on the composting process as described in EN13432 and should not leave harmful residues behind.

Owing to the ubiquitious nature of expanded polystyrene and other plastic waste containers and their resistance to disintegration and biodegradability, the disposed container has essentially become non-destructible waste, which make it no longer just fit for purpose. Strategies to manage disposal or disintegration of food containers, which are disposed globally on a daily basis, in significant volumes and continue to accumulate in the environment have now become crucial and require attention. It would therefore be highly beneficial to develop an environmentally friendly paper-based product that can be used to replace the environmental scourge that is expanded polystyrene, but fulfil the same function effectively. It would be further useful if such a product could be simple and cost effective to produce.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a water-based grease, oil, alkaline, dry soap, water and water vapour transmission barrier coating composition, with or without an aesthetic pigment, for coating one or both surfaces of a paper-based substrate used for the packaging, transport, holding, display or consumption of consumables comprising or consisting of the following ingredients: a) a styrene-acrylic copolymer resin; b) a glycol-ether-free styrene-acrylic copolymer film forming emulsion; c) a high viscosity styrene-acrylic copolymer colloidal emulsion; d) an antifoam; e) alcohol; f) water; and g) optionally one or more water based pigment(s), wherein the barrier coating composition excludes the use of polystyrene or expanded polystyrene, and plastics including, but not limited to, polypropylene, high density polyethylene (HDPE), low density polyethylene (LDPE), polyethylene terephthalate (PET), or polyvinyl chloride (PVC or vinyl).

In one embodiment of the invention the barrier coating composition comprises or consists of the following ranges of ingredients: It is to be appreciated that the quantities set out above may include a variance of between about 4% to 10%, greater or lesser of each of the ingredients.

For example, the the barrier coating composition comprises or consists of the following ranges of ingredients:

It is to be appreciated that the quantities set out above may include a variance of between about 4% to 10%, greater or lesser of each of the ingredients.

Alternatively, the barrier coating composition comprises or consists of the following ranges of ingredients:

It is to be appreciated that the quantities set out above may include a variance of between about 4% to 10%, greater or lesser of each of the ingredients.

The barrier coating composition may be formulated as a clear, gloss, matt or decorative aesthetic pigmented finish. One or more silica compounds may be incorporated to create a matt aesthetic finish. For example the decorative aesthetic pigmented finish may comprise a coloured finish using any desired colour of water-based pigments. For example, the colours may be black, blue, or green, as well as other colours as desired. The paper-based substrate may be paper or paperboard products and may be printed or unprinted, fluted or corrugated.

Consumables to be packaged may be industrial and FMCG goods, including fruit, vegetable, meats, dairy, snack and fast foods.

According to a further aspect of the invention there is provided a paper-based product for the packaging, transport, holding, display or consumption of consumables coated on one or both surfaces with the barrier coating of the invention, wherein the paper-based product excludes the use of polystyrene or expanded polystyrene, and plastics including, but not limited to, polypropylene, high density polyethylene (HDPE), low density polyethylene (LDPE), polyethylene terephthalate (PET), or polyvinyl chloride (PVC or vinyl).

According to a further aspect of the invention there is provided a method for manufacturing a a water-based barrier coating composition of the invention comprising or consisting of the steps of: i. adding the styrene-acrylic copolymer resin to dedicated mixing vessel; ii. blending in water; iii. starting-up and charging the mixing vessel; iv. blending in a glycol-ether-free styrene-acrylic copolymer film forming emulsion; v. blending in a high viscosity styrene-acrylic copolymer colloidal emulsion, optionally comprising one or more water-based pigment(s) dispersed therein; vi. blending in antifoam; and vii. blending in alcohol.

According to a further aspect of the invention there is provided a method for manufacturing a paper-based product coated on one or both surfaces with the barrier coating composition of the invention, comprising or consisting of the steps of:

A. mixing a barrier coating composition of the invention to ensure homogenisation prior to application;

B. application of the barrier coating composition of the invention to a first surface of a paper-based substrate by gravure, flexographic, varnisher, rollercoat, semi- flexographic roll, blade coater, or airknife coaters, preferably by gravure application or flexographic application; C. drying the coated paper-based substrate by gas or electric fired ovens with high velocity air to remove the liquid solvents and ensure a tack free finish on delivery, typically at a temperature of between 60 to 100°C; and

D. optionally application of the barrier coating composition of the invention to a second surface of a paper-based substrate by gravure, flexographic, varnisher, rollercoat, semi- flexographic roll, blade coater, or airknife coaters, preferably by gravure application or flexographic application followed by drying the coated paper-based substrate by gas or electric fired ovens with high velocity air to remove the liquid solvents and ensure a tack free finish on delivery, typically at a temperature of between 60 to 100°C.

In one possible exemplification of the invention, the barrier coating composition may be applied at from 1 .2 to 4.0 g/m ² dry, or from 1 .2 to 2.0 g/m ² dry, depending on the application method and requirements.

The barrier coating composition of the invention may be applied directly to the paper-based substrate, or may be applied over a primer coating.

In particular the barrier coated paper-based products are provided as a replacement for polystyrene, expanded polystyrene or other plastic containers.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to a grease, oil, alkaline, dry soap, water and water vapour transmission barrier coating composition, with or without an aesthetic pigment, for coating of paper-based products used for the packaging, transport, holding, display or consumption of consumables, and to paper-based products coated with the barrier coating composition of the invention. The invention further relates to a method for manufacturing such a barrier coating composition and a method of producing barrier composition coated paper-based products. In particular the barrier composition coated paper-based products are provided as a replacement for polystyrene, expanded polystyrene or other plastic containers.

The basic unit of polystyrene is typically manufactured through a reaction of ethylene and benzene in the presence of a catalyst e.g., aluminium chloride, which is then dehydrogenated at 600/650 °C to form styrene. Polystyrene is formed by suspension polymerisation, which involves suspension of tiny droplets of the styrene monomer in water and a mucilaginous substance, the suspension agent produces droplets of polystyrene. The next process involves incorporating a polymerisation initiator to the droplets, which are suspended by heat radiation at 100 °C, creating free radicals which molecularly bond to form chains of polystyrene. The polymerisation process is stopped at appropriate times through the introduction of terminators to ensure chains tall within required ranges, overly long chains will not melt readily, and shorter chains will exhibit brittle properties. Once polymerisation is completed the polystyrene chains are allowed to cool, washed, dried, and sized through meshes. In order to expand the polystyrene beads, the beads must be first pre-expanded to achieve proper density, this involves heating with steam or heat in a controlled vessel, which incorporates an agitator to prevent the polystyrene beads from fusing together. Since expanded beads are lighter, they are forced to the top of the vessel and discharged. The process lowers the density of the beads to 3% of their original value and yield a smooth skinned, closed cell expanded polystyrene beads which are aired for 24 hours. The ageing process allows air to diffuse into the beads, making them harder.

After ageing, the beads are fed into moulds of the desired container shape, low pressure steam is injected, into and between the beads, expanding them once more causing them to fuse together, once coaled, a container is created. The containers which are now ready to package foods are the perfect material, which are cost effective and functions effectively to protect and hold and store foods, for the intended shelf life of the specific product, in various display environments, including, refrigeration, shelf display and outdoor conditions.

Expanded polystyrene trays are typically available in various colours. As most stores exhibit a variety of merchandise including fruit, vegetable and meats, the use of coloured trays assists with, amongst others: rapid product classification by the retailer; and

- enhancement of the appearance of the product being sold.

While there is no official colour coding system:

- green trays are typically used for fruit or fresh produce of any type; yellow is primarily for chicken; blue is traditionally used for mushrooms;

- black may be used for all types of foods, but is commonly used for meats or to enhance the marketing appeal of brightly coloured fruits e.g., strawberries; and

- white is used for all foods.

The applicant has therefore developed a replacement product that can be used instead of polystyrene, expanded polystyrene or other plastic containers for the packaging, transporting, holding, displaying or consuming of industrial and fast moving consumer goods (FMCG) including foods, fruit, vegetable, meats and fast foods. The invention relates to a barrier coated, fluted cartonboard or paper product, that is available in clear, gloss, matt or decorative aesthetic pigmented finishes.

The product comprises of two similar compositions that may be used in the alternative: a) the first is a functional coating for application to paper-based packaging materials to impart barrier properties, and includes barrier to water, grease, oil, fats alkaline and soap; and b) the second is an aesthetic pigmented version of the first composition, available in any desired colour, such as black, blue, green etc. versions.

The first composition is formulated for application to the paper between 2 to 4 grams per meter square (g/m ² ) dry, although it is to be appreciated that the application grammage can be lowered or increased, depending on the substrate’s smoothness, substrate porosity and level of barrier required. The first composition is formulated to impart an initially breathable layer, on application allowing moisture and heat transpiration through the print stack, which on allowing 24 hour conditioning, exhibits barrier optimisation.

The second composition is merely an aesthetic pigmented version of the first composition.

The application of the first and second compositions involves print conversion to papers, which may also be laminated or fluted with other papers, to form fit for purpose paper food containers for the holding, packaging, transporting, storing, displaying and consumption of food products. These first and second composition-coated paper packaging products, which can be recycled, will disintegrate in the environment, and manage the risks associated chemical migration from expanded polystyrene containers presently affecting human health, provide an environmentally sustainable alternative to the current expanded polystyrene container.

Some advantages to the application of the first and second compositions to fluted containers include imparting a fit for purpose:

- cobb value; moisture vapour transmission rate value;

- effective protection of the product; lightweightedness;

- breathability / moisture release during the packaging of warm products; coefficient of friction value for carton forming, processing; - stacking I structural integrity for packaging, wrapping, storing, displaying, and transporting of food; refrigeration tolerance; and

- scuff and abrasion tolerance, customised for wrapping lines, under packaging, wrapping, storing, displaying, and transporting of food.

Other technical and mechanical benefits include:

- cost effectiveness; resistance to shrinkage;

- cost recovery as wastepaper;

- excellent substrate dead fold;

- suitablility for high speed print conversion; and

- suitablility for application in register

Furthermore, environmental benefits include:

- containers are recyclable; and non-recovered containers will disintegrate in landfill at the rate of the papers’ standard rate of disintegration.

Health Benefits include:

- free of known toxic chemicals and suspected carcinogens and neurotoxins that are hazardous to human health, including through attacking the central nervous and peripheral nervous system; free of known toxic substances which exhibit potential to be leached into food which can be absorbed into the bloodstream and tissues; and free of dioxins which are known to cause immune and hormonal concerns.

The invention will now be described with reference to the following exemplary embodiments which should in no way be considered to be limiting to the scope of the invention. EXAMPLES

1. Composition of ingredients

Figure 1: Composition of the first composition of the invention

Figure 2: Composition of the second composition of the invention

The styrene-acrylic copolymer resin is any OH-functional acrylate binder including a carboxyfunctional styrene-acrylic resin, in particular a styrene-acrylic copolymer emulsified resin.

The glycol-ether-free styrene-acrylic copolymer film forming emulsion is a semi-translucent emulsion formulated for use with water-based inks and overprint varnishes, having ultra-low VOC, excellent resolubility, excellent printability, excellent viscosity stability, and good compatibility.

The high viscosity styrene-acrylic colloidal emulsion is a semi-translucent emulsion formulated for use with inks for pre-print and post-print corrugated board and kraft paper applications, having good transfer and printability, excellent hot mar resistance, and low cost in use. The alcohol is preferably ethanol, more preferably ethyl alcohol of 95 % mass purity.

Any water-based, food-safe pigment that is known to those skilled in the art may be used.

2. Process of manufacture

2. 1. Equipment required

Dedicated mixing vessel

Pre-blending vessel

High Shear blending equipment

Low shear blending equipment

Industrial weighing equipment

Personal protective equipment

2.2. Method of manufacture of the first composition of the invention viii. Add 25 parts styrene-acrylic copolymer resin, to dedicated mixing vessel; ix. Blend in 10 parts water; x. Start-up / charge high shear mixing; xi. Blend in 10 parts glycol-ether-free styrene-acrylic copolymer film forming emulsion; xii. Blend in 40 parts high viscosity styrene-acrylic copolymer colloidal emulsion; xiii. Hand mix 0.5 parts antifoam into 0.5 parts water, add blend to vessel; and xiv. Hand mix 10 parts alcohol into 4 parts water, add blend to vessel.

2.3. Method of manufacture of the second composition of the invention

A. Add 40.8 parts styrene-acrylic copolymer resin, to dedicated mixing vessel;

B. Blend in 2 parts water;

C. Start-up / charge high shear mixing;

D. Blend in 10 parts glycol-ether-free styrene-acrylic copolymer film forming emulsion;

E. Blend in 40 parts high viscosity styrene-acrylic copolymer colloidal emulsion comprising water-based pigment dispersed therein;

F. Hand mix 0.5 parts antifoam into 0.5 parts water, add blend to vessel; and

G. Hand mix 4 parts alcohol onto 2.2 parts water, add blend to vessel. 2.4. Product Description of the first composition of the invention

The first composition of the invention is a water-based barrier coating, specifically formulated to impart water repellence onto papers. The first composition of the invention is customised to impart an initially “breathable” film, which allows moisture and heat transpiration through the print stack, which on 24 hour conditioning allows barrier optimisation.

Product Features

- Good water repellence

- Good cobb value, values will optimise after 24 hour conditioning

- Good flexibility

- Good scuff and abrasion resistance

- Good release in stacks

- Good deep freeze resistance

- Good non-block tolerance

- Imparts a soft bruise resistant effect to the substrate

Typical Product Properties

Solid Content 19 - 22.0%

Package viscosity 20 - 30” Zahn#2 @ 25 °C p.H Value 8.8 - 9.4

Dry Coating Weight 1 .2 - 4.0 g/m ² [depending on application method & requirements] Reducer, STD Water or Water / 95% ethyl alcohol blend [50:50] Wash Up [Wet] Water Wash Up [Dry] Remove by mechanical means

Additional Information

- Mix well before use, settling of the additive components can occur on standing, these can be readily re-homogenised with the use of a clean, handheld mixing paddle

- Apply by gravure, flexo, semi-flexo roll, varnisher or dedicated coating device

- Apply directly to paper or over primer

- Drying, conventional high velocity air [60 °C - 100 °C], or adequate temperature to ensure a tack free finish on delivery

- Seal container after use, store away from sources of frost, direct sunlight or contamination

- Store between +5 °C to <+35 °C - Barrier performance is influenced by substrate pinholes and substrate smoothness

2.5. Product Description of the second composition of the invention

The second composition of the invention is a water-based, barrier coating, specifically formulated to impart water repellence onto papers. The second composition of the invention is an aesthetic pigmented version of the first composition of the invention. The second composition of the invention is customised to impart an initially “breathable” film, which allows moisture and heat transpiration through the print stack, which on 24 hour conditioning allows barrier optimisation.

Product Features

- Good water repellence

- Good cobb value, values will optimise after 24 hour conditioning

- Good flexibility

- Good scuff and abrasion resistance

- Good release in stacks

- Good deep freeze resistance

- Good non-block tolerance

- Imparts a soft bruise resistant effect to the substrate

Typical Product Properties

Solid Content 38.0 - 45.0% [depending on pigment dispersion solids]

Package viscosity 20 - 30” Zahn#2 @ 25 °C p.H Value 8.8 - 9.4

Dry Coating Weight 1 .2 - 4.0 g/m ² [depending on application method & requirements] Reducer, STD Water or Water 1 95% ethyl alcohol blend [50:50] Wash Up [Wet] Water Wash Up [Dry] Remove by mechanical means

Additional Information

- Mix well before use, settling of the additive components can occur on standing, these can be readily re-homogenised with the use of a clean, handheld mixing paddle

- Apply by gravure, flexo, semi-flexo roll, varnisher or dedicated coating device

- Apply directly to paper or over primer - Drying, conventional high velocity air [60 °C - 100 °C], or adequate temperature to ensure a tack free finish on delivery

- Seal container after use, store away from sources of frost, direct sunlight, or contamination

- Store between +5 °C to <+35 °C

- Barrier performance is influenced by substrate pinholes and substrate smoothness.

2.6. Application methodology

The compositions of the invention are recommended for application by gravure or flexographic printing, but application is not limited to these processes and others known to those skilled in the art may be used. For example, the compositions of the invention can also be adapted for application by lithographic printing, through a coating unit, semi-flexographic roll system, Meyer rod or other dedicated coated methods.

The compositions of the invention may be applied to one or both surfaces of a paper-based product, including brown or bleached kraft paper, coated or uncoated paper or paperboard, and fluted paperboard. They may be applied over a primer if desired.

Flexographic Application

Flexographic (or Flexo) printing is a printing process which utilises a flexible relief plate, which is mounted over a roller. The plate is based on a light sensitive polymer. To create a specific image a negative image is placed over the plate, which is subsequently exposed to ultra violet light, the polymer hardens where light passes through the film, the remaining polymer which changes in consistency is washed away, this process can also be done by lazer etching. For full coverage, a standard rubber roller can be used instead of mounting a full plate.

The Flexo process involves a fountain roller which is submerged in the ink pan, this roller transfers the coating from the pan onto an anilox, which is also known as a metering roller. The anilox roller has engraved recessed cells which are pre-determined to carry a specific volume of coating. The doctor blade scrapes the anilox roll to ensure that the predetermined ink quantity delivered is only what is in the engraved cells.

The coatings are transferred onto flexible printing plates or solid rubber roller as an alternative to a plate cylinder. The impression cylinder applies pressure to the plate cylinder, where the image is transferred to the paper substrate the paper is drawn into an enclosed oven with heated air movement and the solvent from the coating is dried. Gravure Application

Direct gravure or rotogravure printing presses involves engraving or chemically etching micronized cells or wells over a chromed copper-based cylinder. These cells are specifically engraved or chemically etched to ensure specific cell dimensions and volumes. The unengraved or unetched areas of the cylinder represent the non-image areas. The cylinder rotates in a bath called an ink pan. As the cylinder turns, the engraved or etched cell volumes are filled with the product of the compositions of the invention, and the excess product is wiped off the cylinder by a flexible steel doctor blade. The remaining product in the recessed cells forms the desired print or image by direct transfer to the paper substrate as the paper passes between the plate cylinder and the impression cylinder.

The coated paper subsequent to the transfer of the coating is drawn through gas or electric fired ovens, these ovens which are enclosed remove the liquid solvents and ensure the coating is dry before it reaches the next gravure station.

The compositions of the invention are inline gravure applied at 1.0 to 2.0 g/m ² dry, although application is not limited to these grammages, over calendared or coated side of specific, qualified paper. It is to be appreciated that the application grammage can be increased, and that this will relatively improve barrier performance.

Application guidelines

Gravure application guidelines

Supply Viscosity - 20 to 30 seconds Zahn#2

Press Mixing - Blend using a hand-held paddle or pneumatic stirrer

Application viscosity - 20 to 30 seconds Zahn#2 @ 25 °C

Reducer - Water or Water / 95% ethyl alcohol blend [ 50:50 ]

Oven temperature - 60 °C to 100 °C, temperature can be adjusted, higher or lower to ensure graduated drying, adequate solvent removal, and a tack free finish, relative to conversion speed Recommended g/m ² - 2.0 to 4.0 g/m ² dry, not limited to recommendation.

Flexo application guidelines

Supply Viscosity - 20 to 30 seconds Zahn#2

Press Mixing - Blend using a hand-held paddle or pneumatic stirrer

Application viscosity - As Supplied

Reducer - Water or Water 1 95% ethyl alcohol blend [ 50:50 ]

Oven temperature - 60 °C to 100 °C, temperature can be adjusted, higher or lower to ensure graduated drying, adequate solvent removal, and a tack free finish, relative to conversion speed

Recommended g/m ² - 1 .2 to 2.0 g/m ² dry, not limited to recommendation.