WO2020035787A1

WO2020035787A1 - Method for fabricating recycled plastic composite material

Info

Publication number: WO2020035787A1
Application number: PCT/IB2019/056863
Authority: WO
Inventors: Jules Dierickx Visschers; Rudy GALLE
Original assignee: Dierickx Visschers Nv; Recencere Bvba
Priority date: 2018-08-13
Filing date: 2019-08-13
Publication date: 2020-02-20
Also published as: BE1026532B1; BE1026532A1

Abstract

The present invention describes, in a first aspect, a method for the fabrication of a plastic composite material comprising the following steps: (a) providing a woven or non-woven structure; (b) equally spreading one or more granular components over the surface of the structure resulting in a layered structure, which granular components comprise one or more thermoplastic polymer components with a glass transition temperature and a melting temperature; (c) optionally, providing a second structure over the granular components; (d) optionally, repeating steps b and c; and (e) heating the layered structure, in which the layered structure is heated to a temperature which is higher than the average glass transition temperature of the thermoplastic components, at which a bond between the granular components and the structure is obtained. A second, third and fourth aspect comprise a non-woven composite material, a composed composite material and a carrier fabricated from this composite material, respectively.

Description

METHOD FOR FABRICATING RECYCLED PLASTIC COMPOSITE MATERIAL

TECHNICAL DOMAIN

The present invention relates in general to methods for fabricating a plastic composite. More in particular, the present invention relates to methods for fabricating a plastic composite comprising a structure bound in a thermoplastic matrix.

STATE OF THE ART

Plastic has become the most commonly used material in the whole industry for forming a variety of products for both household and commercial purposes. Accordingly, there has been a significant increase in plastic production throughout the years and this has significantly contributed to the increased burden of solid waste. Because of their characteristics, plastics are a particularly difficult kind of waste as they do not quickly perish.

For reducing the costs associated with obtaining raw materials, wasting natural sources for the fabrication of disposable products and minimizing possible negative effects on the environment, continuous efforts have been done for developing methods for recycling used thermoplastic materials, that would otherwise be burnt or dumped onto a dumping site. Such methods comprise injection moulding, rotational moulding, calendaring and different kinds of extrusion techniques.

In such an application of recycled thermoplastic materials, a variety of thermoplastic composite plates and/or panels has been developed. Such thermoplastic composites, in general fabricated by means of non-woven methods, comprise fibre materials that are reinforced in the recycled thermoplastic materials. These thermoplastic composites offer a number of advantages, for example, they can be moulded and shaped into a variety of appropriate products, both structurally and non-structurally, such as, amongst other things, parking boards, advertising boards, car panels, carriers (crates, boxes, pallets, etc.) and many others.

However, the use of recycled materials for the fabrication of thermoplastic composites has also a number of disadvantages. The recycling of different lightweight thermoplastic products, e.g. disposable gloves, aprons, air filters, protected covers, plastic covers, polythene, etc. is for example generally not preferred because their use often results in products with physical characteristics that are generally less acceptable than products made of strong thermoplastic materials. Consequently, these types of products remain 'waste', and thus keep on being dumped on dumping sites or burnt, and thus, they have detrimental consequences for the environment.

In some recent efforts, such shortcoming with the lightweight thermoplastic material is solved by using a method in which lightweight plastic materials such as polypropylene (PP) or polyethylene bags, films, cloths or similar are first washed in a centrifugal process, are then torn up and subsequently are molten and are again processed into a rough pellet shape. Although this process is generally effective for providing desired characteristics to the output products, it requires that the separate melting processes form pellets, which inevitably adds costs to the process and thus, to the final recycled product.

Consequently, there is a need in the technique for a time-efficient as well as cost- efficient method for forming thermoplastic composites that are fabricated from recycled materials, with characteristics of impact strength, fragility, swelling, heat resistance, heat delay, dimensional stability, abrasive resistance that are at least similar to products that are fabricated with new materials.

Moreover, considering a continuously increasing complexity of packaging materials, in particular multi-layered bags, e.g. shrink bags and hybrid bags and foils, and consequently increasing difficulties for recycling these materials, the purpose of the present invention is to provide a method allowing an efficient recycling thereof.

The present invention aims to find at least a solution for some of the above- mentioned problems or disadvantages.

SUMMARY OF THE INVENTION

Thereto, a first aspect of the present invention provides a method for the fabrication of a plastic composite material of claim 1. The method comprises the steps of (a) providing a woven or non-woven structure; (b) equally spreading one or more granular components over the surface of the structure resulting in a layered structure, which granular components comprise one or more thermoplastic polymer components with a glass transition temperature and a melting temperature; (c) optionally, providing a second structure over the granular components; (d) optionally, repeating steps b and c; and (e) heating the layered structure. The layered structure is heated to a temperature which is higher than the average glass transition temperature of the thermoplastic components, at which a bond between the granular components and the structure is obtained.

A particular advantage of this method is that it offers a very efficient process enabling the recycling of normally difficult to not to recycle composite materials, including the recycling of increasingly complex packaging material, particularly multi-layered bags (e.g. shrink bags) and hybrid bags and foils. Therefore, an additional step is normally required, namely the melting and shaping into granulates or pellets.

Preferred embodiments of the method are illustrated in claims 2 to 22.

A specific embodiment relates to the method of claim 2, in which the layered structure is heated to a temperature which is below the average melting temperature of the thermoplastic components. The heating between the average glass transition temperature and the average melting temperature of the thermoplastic components offers a flexible composite material, in which the thermoplastic polymer components adhere to each other. Such a flexible composite material can easily be folded and transported, and is a valuable semi-finished product that can be distributed for the subsequent thermomoulding thereof.

A further or other embodiment relates to the method of claim 5, in which the granular components comprise regrind, flakes, granulate and/or agglomerate with a diameter between 3 and 25 mm. The adhesion between the thermoplastic components is optimal within this diameter range and a large diversity of thermoplastic components is possible. The spreading of the granular components over the tissue is hereby very uniform.

An embodiment according to claim 6 relates to the method, in which the granular components comprise a micronisate, with a diameter between 0.1 and 300 pm.

A second aspect of the present invention relates to a non-woven composite material according to claim 23, in which a non-woven or woven structure is comprised in a thermoplastic matrix, which binds the structure. The composite material comprises a layered structure, which comprises between 5.0 and 50.0 m% per layer of structure, and between 50.0 and 95.0 m% per layer of thermoplastic matrix. Preferred embodiments of the composite material are described in the claims 24 to 33.

In a third and fourth aspect, the present invention describes a composed composite material according to claim 34 and a carrier according to claim 37, respectively. Preferred embodiments of the composed composite material and the carrier are shown in claims 35-36 and 38-41, respectively.

DETAILED DESCRIPTION

In a first aspect, the present disclosure relates to a method for forming a plastic composite from recycled thermoplastic materials by means of a simple, cost-efficient method. The method uses a lightweight plastic material including, but not limited to, plastic films, foils, plastic bags, etc. for forming a plastic composite with appropriate mechanic characteristics, high heat resistance, high impact strength, load resistance, and a very good dimensional stability. The constructed plastic composite is useful for forming varieties of panel plates, such as a construction fence panel, advertising boards, plastic steel planking, carriers such as boxes, crates, pallets or similar. It will be clear that, although the present description only refers to lightweight recycled thermoplastic materials such as foils, bags, films, etc., the present method can also be used generally for all kinds of thermoplastic materials.

Unless otherwise specified, all terms used in the description of the invention, including technical and scientific terms, shall have the meaning as they are generally understood by the worker in the technical field of the invention. For a better understanding of the description of the invention, the following terms are explained specifically.

"A", "an" and "the" refer in the document to both the singular and the plural form unless clearly understood differently in the context. "A segment" means for example one or more than one segment.

When "approximately" or "about" are used in the document together with a measurable quantity, a parameter, a period or moment, etc., variations of +/-20% or less, preferably +/-10% or less, more preferably +/-5% or less, still more preferably +/-1% or less, and even still more preferably +/-0.1% or less than and of the cited value are meant, as far as such variations apply to the invention that is described. It will however be clearly understood that the value of the quantity at which the term "approximately" or "about" is used, is itself specified.

The terms "include", "including", "consist", "consisting", "provide with", "contain", "containing", "comprise", "comprising" are synonyms and are inclusive or open terms that indicate the presence of what follows, and that do not exclude or prevent the presence of other components, characteristics, elements, members, steps, known from or described in the state of the art.

The citation of numeric intervals by means of end points includes all integers, fractions and/or real numbers between the end points, including these end points. The term "granular components" refers to a wide range of products occurring as a group of loose pieces or parts. Depending on the size of these parts and/or the shape in which they occur, different terms are used. "Regrind" refers to parts that are obtained after e.g. grinding. According to an approximately decreasing particle size, the terms "flakes", "granulate", "powder" and "micronisate" are used here. Flakes have a rather irregular shape and can amongst other things be obtained after a breaking or tearing process, while a granulate is mainly composed of parts with an essentially spherical shape. As soon as the dimensions of the granulate or powder are within the micrometre range, this granulate is also called "micronisate". By extension, several adhered or bound parts are called an "agglomerate". Consequently, agglomerates have a rather irregular shape.

The term "melting temperature" means the temperature that is minimally necessary for making a substance melt, or for making it pass from a solid to a liquid state. For some materials, especially for polymers and in particular for thermoplastic polymers, the transition between solid and liquid state is a gradual transition. The term "glass transition temperature" refers in such cases to the temperature at which this substance becomes weak, or otherwise, when the temperature exceeds the "processing temperature", at which the substances softens. Between the glass transition temperature and the melting temperature, a polymer is still solid, but not liquid, however rather soft and sticky.

The term "natural fibres", as used here, refers to any continuous filament that has been derived from natural, renewable sources such as plants or animals. The terms 'fibres' and 'filaments' are used interchangeably. Natural fibres can comprise, but are not limited to, seed fibres such as cotton and kapok; leaf fibres such as sisal and agave; bast fibres or skin fibres such as flax, jute, kenaf, hemp, ramie, rattan, soy fibres , vine fibres, and banana fibres ; fruit fibres such as coconut fibres ; stem fibres such as wheat straw, rice, barley, bamboo, grass and tree wood; animal hair fibres such as sheep's wool, goat's wool (cashmere, mohair), alpaca's wool, horsehair; silk fibres; bird fibres such as feathers.

A first aspect of the present invention provides a method for the fabrication of a plastic composite material comprising the following steps: (a) providing a woven or non-woven structure; (b) equally spreading one or more granular components over the surface of the structure resulting in a layered structure, which granular components comprise one or more thermoplastic polymer components with a glass transition temperature and a melting temperature; (c) optionally, providing a second structure over the granular components; (d) optionally, repeating steps b and c; and (e) heating the layered structure. The layered structure is heated to a temperature which is higher than the average glass transition temperature of the thermoplastic components, at which a bond between the granular components and the structure is obtained. The bound granular components are further also called "thermoplastic matrix".

The term "average glass transition temperature" or shortly "glass transition temperature" of one or more components in a thermoplastic matrix should be interpreted in the context of the present invention as the temperature and/or the temperature range at which adhesion of the thermoplastic matrix takes place in which the rubber reaches a rubbery state, and in which polymer chains are free to move but, however, still remain intertwined. The polymer does not yet "flow" in this state, but can already adhere to the woven or non-woven structure. The skilled worker who knows the characteristics of the incoming waste flow to recycle, can determine and/or estimate this glass transition temperature and/or this range based on the composition of the incoming waste flow and can, if necessary, realize the method of the present invention successfully.

According to an embodiment, the average glass transition temperature of a waste flow is chosen as the temperature at which at least 50 m% of the thermoplastic components become rubbery, as a result of which a good adhesion is obtained. Preferably, the average glass transition temperature is chosen as the temperature at which at least 60 m% of the thermoplastic components become rubbery, more preferably at least 70 m%, still more preferably at least 80 m%. In the following, the average glass transition temperature of a mixture is shortly referred to as the glass transition temperature.

According to some embodiments, the layered structure is heated to a temperature which is higher than the average softening temperature. The "average softening temperature" of shortly "softening temperature" of one or more components in the thermoplastic matrix, should be interpreted in the context of the present invention as the temperature and/or the temperature range at which adhesion substantially continues in the thermoplastic matrix. The polymer reaches a more fluid state, in which polymer chains are no longer intertwined, but move as a whole with respect to each other. The skilled worker who knows the characteristics of the incoming waste flow to recycle, can determine and/or estimate this softening temperature and/or this range based on the composition of the incoming waste flow and can, if necessary, realize the method of the present invention successfully.

According to an embodiment, the average softening temperature of a waste flow is chosen as the temperature at which at least 50 m% of the thermoplastic components soften, as a result of which a good adhesion is obtained. Preferably, the average glass transition temperature is chosen as the temperature at which at least 60 m% of the thermoplastic components soften, more preferably at least 70 m%, still more preferably at least 80 m%. In the following, the average softening temperature of a mixture is shortly referred to as the softening temperature.

The method is generally a simple, cost-efficient, time-saving method for forming a high-quality thermoplastic composite by using generally unused lightweight plastic waste such as, amongst other things, plastic foils, plastic bags, gloves or similar, and/or combinations thereof. Usually, for the use of such lightweight plastic materials, an additional step is required of melting and shaping it into granulates or pellets before they are applicable for being used in the fabrication of thermoplastic composites. However, by using the method in accordance to the present invention, the recycling process can be shortened considerably and significantly. While recycling by melting plastics leads to a recycled product with an inferior quality and reduced strength, the method of the present invention provides a high-quality product. The product can hereby be adjusted to the aimed field of application and can, if necessary, be fabricated both flexible and hard and/or rigid. Moreover, the product can be re- recycled several times, in which the product becomes ever stronger. The granular component can, moreover, also comprise thermosetting polymers, as a result of which the present method also offers a solution for the recycling of normally difficult to not to recycle components.

The determination of the strength, namely the impact and tensile strength, can be determined by means of techniques as known from the state of the art, for example the standard ISO 9073-3: 1989, ISO 9073-4: 1997 or ISO 9073-5:2008.

According to an embodiment, the layered structure is heated to maximum 10°C above the average melting temperature of the thermoplastic components. More preferably, it is heated maximum 5°C above the average melting temperature. The term "average melting temperature" of shortly "melting temperature" of one or more components in the thermoplastic matrix, should be interpreted in the context of the present invention as the temperature and/or the temperature range at which substantial melting takes place in the thermoplastic matrix. The skilled worker who knows the characteristics of the incoming waste flow to recycle, can determine this melting temperature and/or this range based on the composition of the incoming waste flow.

According to an embodiment, the average melting temperature of a waste flow will be chosen as the temperature at which at least 50 m% of the thermoplastic components melts. Preferably, the average glass transition temperature is chosen as the temperature at which at least 60 m% of the thermoplastic components melts, more preferably at least 70 m%, still more preferably at least 80 m%. In the following, the average melting temperature of a mixture is shortly referred to as the melting temperature.

According to still another embodiment, the melting temperature of the woven or non- woven structure is higher than the glass transition temperature of the thermoplastic matrix. The melting temperature of the woven or non-woven structure is preferably 1°C, more preferably 5°C, still more preferably 10°C, still more preferably 25°C higher than the glass transition temperature of the thermoplastic matrix.

According to another embodiment, the melting temperature of the woven or non- woven structure is higher than the softening temperature of the thermoplastic matrix. The melting temperature of the woven or non-woven structure is preferably 1°C, more preferably 5°C, still more preferably 10°C, still more preferably 25°C higher than the softening temperature of the thermoplastic matrix.

According to a further or another embodiment, the melting temperature of the woven or non-woven structure is higher than the melting temperature of the thermoplastic matrix. Hereby, the woven or non-woven structure remains essentially intact, and the structure is optimally bound in the thermoplastic matrix. The melting temperature of the woven or non-woven structure is preferably 1°C, more preferably 5°C, still more preferably 10°C, still more preferably 25°C higher than the melting temperature of the thermoplastic matrix. In a preferred embodiment, steps b and c can be repeated up to 7, 10 or 20 times before the structure is reinforced by heat.

The granular components generally comprise lightweight thermoplastic (generally with a lower relative density or lower bulk density than water) such as plastic foils, plastic bags, plastic gloves, foils, other polymer materials comprising polypropylene (PP), polystyrene (PS), polyamid (PA), polycarbonate (PC), polymethyl-methacrylate (PMMA) or similar. Preferably, its melting temperature is lower than 200°C or more preferably lower than 190°C.

According to a further or another embodiment, the layered structure is heated to a temperature that is lower than the average melting temperature of the thermoplastic components. Whereas in conventional recycling processes of thermoplastic materials, one always tries to obtain a heating temperature that is higher than the average melting temperature, for forming pellets, the temperatures that are used in the present method, are significantly lower. According to this method, the melting of the thermoplastic components is not aimed for, but however its adhesion. This offers a flexible composite material. Such a flexible composite material can easily be folded, rolled and transported, and is a valuable semi-finished product that can be distributed for the subsequent thermomoulding thereof. The use of this temperature does not only allow the processing of a variety of thermoplastic components at the same time, but the method is moreover realized in an extremely cost-efficient way. Contrary to recycling processes at higher temperatures, where the melting of polymers is aimed for, in the method of the present invention, the structure and the quality of the plastic material is maintained and moreover, the quality of the end product is even improved at repeated recycling thereof. Moreover, potential dangers, such as the release of chlorine in the processing of PVC, is minimized at these low temperatures.

According to an embodiment, the melting temperature of the thermoplastic components is at least 10°C higher than their glass transition temperature. A difference in temperature of at least 10°C allows to efficiently realize the method. The higher this temperature difference, the less stringent the requirements of the heating temperature are, and the more possibilities there are as to the diversity of the used thermoplastic components. Preferably, the melting temperature of the thermoplastic components is at least 20°C higher than their glass transition temperature, more preferably at least 30°C higher, still more preferably at least 40°C, most preferably at least 50°C higher. According to a further or another embodiment, the layered structure is heated to a temperature that is comprised between 90 and 140°C for 1 to 15 minutes. Preferably, the temperature is comprised between 100 and 130°.

In an embodiment of the present invention, a plastic panel can be made of a thermoplastic composite in accordance to one aspect of the present invention. The thermoplastic composite is, at least partially, made of used, recyclable thermoplastic material. The thermoplastic material generally comprises granular components comprising one or more lightweight (i.e. with a relative density and/or bulk density lower than water), thermoplastic materials in the shape of regrind, pellets, agglomerate and/or granulate. According to an embodiment, the diameter of the granular components is comprised between 3 mm and 25 mm, which range offers optimal characteristics to the composite material. The adhesion of the thermoplastic components is optimal within this diameter range and the use of a large diversity of thermoplastic components is possible. The spreading of the granular components over the structure is hereby very uniform. Within this range, characteristics such as impact strength, swelling, heat resistance, heat delay, dimensional stability and abrasive resistance of the resulting composite material are moreover obtained, that are at least comparable with commonly used composite materials. Preferably, the diameter is between 3 mm and 15 mm, most preferably between 5 mm and 10 mm.

The diameter of granular components, comprising flakes with a rather irregular shape, as well as granulate with an essentially spherical shape, can be determined by means of several techniques as has been described in the state of the art. According to some embodiments, the diameter, or equivalent diameter, of the granular components is determined by means of one or several sieves and/or grids with a specific hole diameter. This method is quick, efficient and moreover very accurate and independent of the type of material. Since the granular components are particularly composed of different materials, material independence is an advantage in this context.

According to an embodiment of the method, the granular components comprise a micronisate with a diameter between 0.1 and 300 pm. The use of a micronisate allows to apply the method at lower temperatures and shorter heating times as a result of which the thermoplastic matrix optimally keeps its structure and only minimally loses its strength. Hereto, the diameter of the micronisate is preferably comprised between 30 and 300 pm. Granular components with a smaller diameter usually lead to a final composite material with a larger strength. Alternatively, in particular for forming very thin and strong composite materials, the diameter of the micronisate is preferably comprised between 0.1 and 1.5 pm.

An embodiment relates to the method in which the granular components are present in the layered structure in a density between 100 and 500 g/m² per layer. A higher density leads to a composite material in which more recycled material has been integrated. This composite material is usually slightly heavier and stiffer and has better sound-isolating characteristics. A lower density offers a composite material that is lighter and more open in structure, with a better heat isolation as a result. This material is often much more flexible than material in which a high density of granular components has been processed. Preferably, the density of the granular components in the layered structure is comprised between 200 and 400 g/m² per layer, most preferably between 250 and 350 g/m² per layer. At a density within this range, an optimal equilibrium between the amount of recycled material and the desired characteristics of the flexible composite material is obtained.

The density is determined by the skilled worker by means of techniques that are known in the state of the art, such as the standard ISO 9073-1 : 1989.

Another or a further embodiment describes the spreading of the granular components over the surface of the structure by means of a spreader and/or vibrating table, which ensures a homogeneous spreading of granular components and can be applied in a round-the-clock production process.

According to an embodiment, the structures comprises natural fibres and/or synthetic fibres with a glass transition temperature and a melting temperature. Preferably, the glass transition temperature of the fibres is higher than the glass transition temperature of the thermoplastic components and the melting temperature of the fibres is higher than their glass transition temperature. As a result, it is possible to fabricate a hard composite material by means of the melting of the thermoplastic components, in which the fibres are only adhered, without melting. As a result, the strength of the composite material is significantly increased.

According to an embodiment, the structure can be fabricated by means of the provision of carded, natural fibres and/or synthetic fibres that are oriented arbitrarily. This orientation is obtained by means of a tissue process, preferably a card or needle punch process for forming a homogeneous mixed tissue structure. Weaving or associated textile production processes, or ultrasonic welding can also be applied. Also, a structure can be provided by means of the purchase of a woven or non-woven cloth.

The card process can, for example, be realized on a Rando machine or Laroche machine, or any other machine, as is known in the state of the art. Alternatively, the fabric is realized using any known mechanism such as a card process, or similar. "Carding" is a mechanical process in which fibres are disentwined and mixed for forming a continuous tissue that is appropriate for later processing. By using a card process, a structure with a very thin predetermined thickness can be produced (up to 16 g/m²).

"Ultrasonic welding" relates to a technique for fabricating a tissue, in which no weaving process is necessary. This technique can have the advantage that the distance between fibres can be chosen, so that flakes at both sides of the tissue structure come into contact with each other, which results in improved characteristics of the recycled plastic composite.

When the structure is formed, the method continues to a next step in which the lightweight thermoplastic matrix is spread uniformly, i.e. it is distributed equally by spreading it uniformly, onto the structure. After the spreading of the thermoplastic matrix, a second structure can be positioned onto the thermoplastic matrix, as such with the lightweight thermoplastic matrix between two tissues. The latter two steps can be repeated a number of times, resulting in layers of spread lightweight thermoplastic matrix between structures of fibres, which results in very high volumes of thermoplastic matrix that are enclosed in the resulting plastic composite. Subsequently, the layered structure is heated by means of known mechanisms such as a thermomoulding process. The used thermomoulding process preferably comprises a thermobinding process in which the structure that is obtained from the preceding step is heated by realizing heated calendar rolling, or by means of other pressing techniques.

According to an embodiment, the structure has a density between 20 and 150 g/m² per layer. A density of the structure within this range offers improved characteristics to the composite material, this mainly with respect to strength. More preferably, the density is comprised between 50 and 100 g/m² per layer, still more preferably between 60 and 80 g/m² per layer. Most preferably, the structure has a density of 1 g/m² per layer.

According to an embodiment, the granular components are obtained by means of the provision of one or more polymer materials, and the tearing up, grinding, reducing, micronizing and/or crushing thereof. This has the advantage that the structural or dimensional requirements of the polymer material to recycle are very low. Mixtures of polymers can be used, in which the shape in which they occur, is not important. However, the average glass transition and melting temperature van these materials are important. A method of the present invention can comprise a number of steps for obtaining granular components of the thermoplastic material to recycle, however, the order of the describes steps of the method is illustrative for the understanding of the invention by the skilled worker.

In general, the collection of thermoplastic granular components to mix for forming the thermoplastic matrix can be obtained in a configuration that is ready for use from different sources (e.g. external suppliers) offering the recycled thermoplastic granular components. However, in some embodiments of the present invention, the collection of the thermoplastic granular components is obtained from a collection of thermoplastic material to recycle.

The collection of thermoplastic material generally comprises a thermoplastic material with a low relative density and/or low bulk density that is mixed with thermoplastic materials with a high relative density and/or a high bulk density. The collection of received thermoplastic material is sorted based on different factors such as type of material, colour of material, or similar, and is subsequently crushed for forming regrind comprising flakes and grains. Standard reduction of plastic to regrind is mostly realized by shredders and pelleting machines. These machines have industrial knifes realizing rotational cutting for grinding the plastic, which is led through a sieve and subsequently is led to the next phase in the process. In embodiments of the present invention, the sieve of the pelleting machine can have a hole diameter that preferably varies between 3 mm and 25 mm, or more preferably between 3 mm and 15 mm, and most preferably between 5 mm and 10 mm. Reduction of plastics alternatively occurs by means of micronization thereof to a particle diameter between 0.1 and 300 pm. Subsequently, regrind with a higher relative density and/or a higher bulk density are separated from regrind with a lower relative density and/or a lower bulk density; preferably by means of a centrifugal process, or by means of a flotation technique such as separation in water, as a result of which the thermoplastic flakes with a density and/or bulk density lower than water are separated from the flakes with a density and/or bulk density higher than water.

In a next step, the regrind with a lower relative density and/or a lower bulk density are processed to separate flakes from grains, for example by wind shifting.

According to an embodiment, the regrind comes from amongst other things plastic foils, plastic bags, plastic gloves, and all kids of plastic foil or multi-layered plate material with a relative density and/or bulk density lower than water. The size of these particles is determined by passing through the sieve of a pelleting machine with a hole diameter that preferably varies between 3 mm and 25 mm, or more preferably between 3 mm and 15 mm, and most preferably between 5 mm and 10 mm. Alternatively, a micronized product is aimed for with a particle diameter between 0.1 and 300 pm. The thermoplastic composite further comprises a core of fibres, generally intertwined and bound into a three-dimensional structure with the thermoplastic matrix.

The thermoplastic materials that are appropriate for being used in this invention are generally composed of different kinds of lightweight plastic components that are derived from the recycled objects such as flexible films and/or plates obtained based on commercial labels, and/or bags, and/or containers, and/or envelopes, preferably for use in the food and/or agricultural sector, preferably made of at least one material from polyethylene (PE), polyethylene terephthalate (PET) polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), that normally cannot be re-used and that are usually dumped on a dumping site or that are burnt because of cost, melting/adhesion, or pollution problems.

Some other non-limiting examples of appropriate thermoplastic materials comprise a product chosen from the following group of resins: acryl nitrile-butadiene-styrene (ABS), acrylic, high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP) and polystyrene (PS). Present recycled plastics that can easily be obtained, are products made of PET and HDPE and comprise plastic bottles, containers and packaging, plastic timber, etc. that are all identified with one of the acceptable recycling symbols, such as: 'high-density white plastics' means containers and packaging made of white and transparent plastics such as containers for white washing powders, containers for wiper fluid, etc.

Other examples of thermoplastic materials comprise the commercial plastic labels that are applied onto containers, boxes, cans, bottles containing food, etc.; transparent, semi-transparent and non-transparent bags, containing fresh food and/or long-life food; bags for agricultural products, such as fertilizers, compost, seeds, etc.; transparent, semi-transparent and non-transparent impenetrable canvasses; bags for waste, food, products and goods, etc.; thermoplastic packaging for mono- and multi-product packagings, etc. and/or any appropriate combination thereof.

Optionally, the regrind of plastic materials with a higher density and/or a higher bulk density than water (e.g. acrylonitrile-butadiene-styrene (ABS), polystyrene (PS), polyvinyl chloride (PVC)) are moreover spread uniformly over the structure(s) or they can be part of the thermoplastic matrix to spread. This can result in a plastic composite with a lower fragility. This type of regrind can make up between 5 and 20 percent by weight, or between 10 and 20 percent by weight, of the total amount of regrind including granular components in the plastic composite.

An embodiment of the present method comprises a structure that comprises fibres chosen from the group of glass fibres, polyester fibres, acrylonitrile-butadiene- styrene fibres (ABS), polystyrene fibres (PS), nylon fibres, polyamid fibres (PA), natural fibres, metal fibres or combinations thereof.

Preferably, the natural fibres that are used in the present invention, have at least moderate strength and stiffness and a good deformability. Fibres with large diameters are also preferred because they offer larger fibre stiffness. Further, optionally, glass fibres or natural fibres can also be spread uniformly over the structure. This can result in a higher stiffness and/or a larger thermal expansion.

In an embodiment of the present invention, the natural fibres comprise natural rough fibres such as jute, hemp, coconut, flax, sisal, etc. In an embodiment of the present invention that is more preferred, jute fibres are used as natural fibres. The jute fibres have characteristics such as a low density, low abrasive characteristics, a high strength and, as a result, a good dimensional stability.

The fibres with a melting temperature that is higher than the melting point of the thermoplastic matrix for use in the fabrication of the plastic composite can comprise thermoplastic fibres and/or glass fibres and/or metal fibres and/or a matrix of natural fibres, preferably unravelled, obtained by processing intertwined natural rough fibres by using conventionally available tools such as a bast fibre opening machine or a tearing machine, or similar.

An embodiment comprises the method in which the structure and the granular components are present in a ratio smaller than 50: 50 on a weight base. Smaller ratios offer structurally better composite materials. Preferably, this ratio is less than 40:60 on a weight base, and most preferred the ratio is 30:70.

According to an embodiment, fibres have a length between 50 and 400 mm. Within this range, the method can be realized efficiently and the addition of the fibres means a plus-value for the strength and other structural characteristics of the composite material. Preferably, their length is comprised between 150 and 350 mm.

An embodiment of the present method comprises the heating of the layered structure by means of steam-heating, steam-injection-heating, microwave heating, vacuum heating, or combinations thereof.

A further or another embodiment comprises the thermal moulding of one or more composite materials by pressing, vacuum moulding, gluing and/or welding, or combinations thereof. Two or more thermoplastic composites are adhered to each other in this way into a layered structure for forming a multi-layered thermoplastic composite. Furthermore, each layer of the multi-layered thermoplastic composite can be moulded into a similar or different thermoplastic material according to the desired application and characteristics of the thermoplastic composite to fabricate.

According to an embodiment, the one or more composite materials are moulded at a temperature that is higher than the melting temperature of the thermoplastic components. Hereby, a hard composite plate material is obtained. The temperature of thermal moulding is possibly situated between the glass transition temperature of the fibres and their melting temperature, so that the thermoplastic matrix melts at least partially, and preferably essentially completely, and so that the fibres do not melt at a second melting temperature. The obtained composite material is hard and is moreover reinforced by the presence of the still intact, however adhered, fibre structure.

Alternatively, reinforcement can be realized in a two-step thermomoulding process. In a first step, thermomoulding is realized at a temperature that is lower than the melting temperature of the thermoplastic components (e.g. between 90 and 120°C), but higher than their glass transition temperature, so that the thermoplastic matrix absorbs sufficient heat energy for weakening and sufficiently adhering or sticking for binding the fibres and thermoplastic matrix, which partially results in a flexible semi- finished product, e.g. a flexible mat. In the second step, thermomoulding is realized at a temperature between the melting temperature of the thermoplastic components and the glass transition temperature of the fibres for further reinforcing and moulding the finished plastic composite. Optionally, a number of flexible mats can be assembled for being exposed to the second thermomoulding step, which results in a stiff composite panel, a stiff composite plate, or a stiff composite plank with higher thickness.

The melting temperature of the fibres can be at least 10°C higher than the melting temperature of the thermoplastic components, or preferably at least 20°C higher, more preferably at least 30°C higher, and most preferably at least 50°C. In some embodiments, the melting temperature of the fibres can be at least 210°C, preferably at least 220°C, more preferably at least 240°C, and most preferably at least 260°C.

In some embodiments, the processing temperature for thermomoulding can be between 190°C and 250°C, preferably between 190°C and 230°C, more preferably between 190°C and 210°C, most preferably approximately 200°C. The resulting plastic composite is a stiff composite panel, a stiff composite plate or a stiff composite plank.

The processing temperature for thermomoulding is hereby between the melting temperature of the thermoplastic components and the melting temperature of the fibres, so that the thermoplastic matrix melts at least partially, and preferably essentially completely, and so that the fibres do not melt. In some embodiments, the processing temperature for thermomoulding can be between 190°C and 250°C, preferably between 190°C and 230°C, more preferably between 190°C and 210°C, most preferably approximately 200°C.

According to a further or another embodiment, the method comprises the treatment of the plastic composite with a finishing material and/or the post-treatment for offering selected characteristics to the composite. One or more surfaces of the thermoplastic composite can for example be treated with an antimicrobial product, an anti-fungal product or similar. Alternatively and/or additionally, the thermoplastic composite can be treated with finishing materials such as wax, paint or similar.

An embodiment comprises the method in which the resulting plastic composite material is re-used as a raw material for a next realization of the method. The recycling process hereby forms, as it were, an infinite loop in which the composite material does not lose quality when realizing the method several times, but hereby rather becomes stronger. In this way, the present method allows to recycle and re- use polymer materials a large number of times. Possible residual materials when realizing the method can also be re-used in a next cycle, as a result of which the method almost does not generate any waste.

A second aspect of the present invention relates to a non-woven composite material in which a woven or non-woven structure is comprised in a thermoplastic matrix, which binds the structure. The composite material comprises a layered structure, which comprises between 5.0 and 50.0 m% per layer of structure, and between 50.0 and 95.0 m% per layer of thermoplastic matrix. The thermoplastic matrix hereby ensures a good adhesion in the composite material, while it improves the structural characteristics that are present. Desired characteristics are a good impact strength, a low fragility, a low swelling, heat resistance, heat delay, dimensional stability, abrasive resistance, at least comparable with products that are fabricated with new materials. Preferably, the layered structure comprises between 10 and 40 m% per layer of structure and respectively between 60 and 90 m% per layer of thermoplastic matrix. More preferably, these concentrations are situated between 20 and 40 m% per layer, respectively 60 and 80 m% per layer. Most preferably, they are situated between 25 and 35 m% per layer, respectively between 65 and 75 m% per layer.

In the context of the layered structure, the term "layer" indicates any sequence of a woven or non-woven structure with homogeneous granular components distributed thereover. A further or another embodiment describes the composite material in which the structure comprises fibres chosen from the group of glass fibres, polyester fibres, acrylonitrile-butadiene-styrene fibres (ABS), polystyrene fibres (PS), nylon fibres, polyamid fibres (PA), natural fibres, metal fibres or combinations thereof. Fibres contribute to the strength of the composite material. According to an embodiment, the thermoplastic matrix comprises polymers chosen from the group of acryl nitrile- butadiene-styrene (ABS), acrylic, high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP) and polystyrene (PS) or combinations thereof. The thermoplastic matrix adheres the different components in the composite material into a strong, coherent assembly.

Still a further embodiment comprises the composite material, in which the woven or non-woven structure is higher than the glass transition temperature of the thermoplastic matrix. The melting temperature of the woven or non-woven structure is preferably 1°C, more preferably 5°C, still more preferably 10°C, still more preferably 25°C higher than the glass transition temperature of the thermoplastic matrix.

A further embodiment comprises the composite material, in which the melting temperature of the woven or non-woven structure is higher than the softening temperature of the thermoplastic matrix. The melting temperature of the woven or non-woven structure is preferably 1°C, more preferably 5°C, still more preferably 10°C, still more preferably 25°C higher than the softening temperature of the thermoplastic matrix.

A further or another embodiment comprises the composite material, in which the melting temperature of the woven or non-woven structure is higher than the melting temperature of the thermoplastic matrix. The melting temperature of the woven or non-woven structure is preferably 1°C, more preferably 5°C, still more preferably 10°C, still more preferably 25°C higher than the melting temperature of the thermoplastic matrix.

An embodiment comprises the composite material with a thickness situated between 2 and 15 mm. Within this range, the composite material can be used in a large application domain. A thickness to 15 mm moreover remains deformable via a thermomoulding process. Preferably, the thickness of the composite material is situated between 3 and 12 mm, most preferably between 4 and 10 mm.

In the context of the present invention, the "thickness" of both flexible and solid composite materials is determined by means of appropriate techniques as known in the state of the art, such as for example described in the standard ISO 9073-2: 1995.

A further or another embodiment comprises the composite material comprising 70 to 90 m% polymers in the form of flakes and/or micronisate chosen from the group of polypropylene (PP), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyvinyl chloride (PVC), polystyrene (PS), or combinations thereof. The particle size of the micronized polymers is preferably situated between 0.1 and 1.5 micron. This composite material can be fabricated extremely thin, namely from minimally 4 mm thick.

In an embodiment, the composite material of the present invention comprises 10.0 to 30.0 m% of polyester fibres. Polyester fibres are easily available and have an ideal melting and glass transition temperature for use in the present invention. In this context, polyester fibres belong to the group of the woven or non-woven structure, as they appear in fibre form and are not granular. They offer an improved strength and rigidity to the composite material.

An embodiment comprises a composite material that can be deformed by means of a thermomoulding process and/or a vacuum process. Deformability is an important aspect as the formation of a non-planar structure broadens the application domain of this composite material.

In an embodiment of the present invention, a composite plate can be made of a multi-layered thermoplastic composite. The multi-layered composite comprises a first layer of thermoplastic composite attached and/or adhered to an adjoining second layer of thermoplastic composite. In some examples, the layers can be equally thick. In some other embodiments, the layers can have a different thickness. In some examples, the first layer and the second layer have both been made of the same thermoplastic materials in the same composition. In some other examples, the first layer and the second layer can be composed using different types of thermoplastic materials, offering different characteristics to each thereof. Correspondingly, by enclosing alternate layers of different materials, the multi-layered composite can show the desired characteristics, such as a high chemical, thermal and mechanical resistance, high strength or similar.

The thermoplastic composite can furthermore comprise one or more layers of finishing materials that are applied to an upper and/or lower surface of one or more separate layers of the thermoplastic composite. In an embodiment of the present invention, the finishing material comprises one or more antibacterial coatings of material such as an antibacterial agent, anti-fungal agent or similar. In another embodiment, the finishing material can comprise a washing solution, paint or similar.

The present invention can mainly be used for different applications such as traffic management products such as advertising boards, parking boards, steel planking, other structural components, made of thermoplastic materials and requires desired characteristics such as impact strength, swelling, heat resistance, heat delay, dimensional stability, abrasive resistance, etc. at least similar to convention plastic plates, mat or panels. Moreover, by spreading recycled thermoplastic matrices over thin fibre tissues, very large volumes of recycled thermoplastic matrices can be enclosed in the resulting plastic composite.

According to an embodiment, the composite material is at least partially composed into a three-dimensional structure. Preferably, this three-dimensional structure comprises a honeycomb structure.

Previous embodiments of the composite material are preferably fabricated by means of a method according to the first aspect of the present invention.

A third aspect of the present invention comprises a composed composite material, made of at least two mutually attached composite materials according to the previous aspect. Preferably, the composed material comprises a central composite material, assembled into a three-dimensional structure, which central composite material is enclosed by two planar composite plates, that are adhered at both sides of the central composite material. More preferably, the three-dimensional structure of the central material comprises a honeycomb structure.

A last aspect of the present invention comprises a carrier made of a composite material according to one of the above-mentioned embodiments. The carrier shows a good strength, at least comparable to commonly used carriers, and is a good alternative for existing carriers in the context of the recuperation of polymer waste materials.

Preferably, the composite material is at least partially composed into a three- dimensional structure. The three-dimensional structure offers improved structural characteristics to the composite material, such as an improved strength, and an increased resistance to bending and breaking, while the carrier remains extremely light. Because of the three-dimensional structure, the necessary amount of composite material per carrier is rather limited. The three-dimensional structures possibly provide points of application for forklift trucks and/or carts, facilitating its use. Preferably, this three-dimensional structure is a honeycomb structure.

According to an embodiment, the carrier comprises several mutually attached composite materials. This allows to combine different material characteristics in the carrier and also allows to fabricate more complex shapes.

Preferably, the carrier comprises a central composite material, which material is assembled into a three-dimensional structure, and which material is enclosed by two planar composite plates, that are adhered at both sides of the central composite material. The three-dimensional structures that is anchored between two planar composite plates is particularly rigid, light and extremely appropriate as a carrier. The planar plates at both sides allow easy stacking of goods on the carrier, as well as the positioning of the carrier onto a surface or into a cart. Carriers that have been assembled in this way comprise, however are not limited to, pallets and platforms.

In a preferred embodiment, the three-dimensional structure comprises a honeycomb structure, offering optimal structural characteristics to the carrier and simplifying the adhesion of surrounding composite plates.

In the following, the invention will be described by means of non-limiting examples or figures illustrating the invention, and not meant to be interpreted as limiting the scope of the invention. EXAMPLES

Example fabrication of a pallet 85 percent in weight of recycled LDPE flakes from foils and bags which have been shredded with a shredder with a sieve with a hole diameter of 8 mm was mixed with 15 percent in weight of a mixture of ABS, PS and PVC grains with approximately the same size. Approximately 300 g/m² of the above-mentioned mixture was spread equally onto a carded tissue structure of 70 g/m² of recycled PET fibres. This process was repeated twice, and a finished tissue structure was placed on top of it, and ended in a sandwich structure of 4 carded fabrics with the mixture of flakes and grains spread equally between them. As such, the total weight of the structure is approximately 1180 g/m².

This structure is thermomoulded under pressure into an intermediate composite material with a thickness of 1 cm. The intermediary product is a flexible mat and can be rolled into a roll of for example approximately 200 kg. 3 pieces of these flexible mats were place onto each other and pressed at 200°C to a total thickness of 9 mm, as a result of which a pallet was formed.

Claims

1. A method for the fabrication of a plastic composite material comprising the steps:

a. the provision of a woven or non-woven structure;

b. the equal spreading of one or more granular components, over the surface of the structure resulting in a layered structure, which granular components comprise one or more thermoplastic polymer components with a glass transition temperature and a melting temperature;

c. optionally, the provision of a second structure over the granular components;

d. optionally, repeating steps b and c; and

e. heating the layered structure;

characterized in that, the layered structure is heated to a temperature which is higher than the average glass transition temperature of the thermoplastic components, wherein a bond between the granular components and the structure is obtained.

2. The method according to claim 1, characterized in that, the layered structure is heated to a temperature which is lower than the average melting temperature of the thermoplastic components.

3. The method according to claim 1 or 2, characterized in that, the melting temperature of the thermoplastic components is at least 10°C higher than the glass transition temperature thereof.

4. The method according to any one of the preceding claims 1-3, characterized in that, the layered structure is heated to a temperature which is comprised between 90 and 140°C for 1 to 15 minutes.

5. The method according to any one of the preceding claims 1-4, characterized in that, the granular components comprise regrind, flakes, granulate and / or agglomerate with a diameter between 3 and 25 mm.

6. The method according to any one of the preceding claims 1-4, characterized in that, the granular components comprise micronisate with a diameter between 0.1 and 300 pm.

7. The method according to any one of the preceding claims 1-6, characterized in that, the granular components are present in the layered structure in a density between 100 and 500 g/m² per layer.

8. The method according to any one of the preceding claims 1-7, characterized in that, the granular components are spread equally over the surface of the structure by means of a spreader and / or vibrating table.

9. The method according to any one of the preceding claims 1-8, characterized in that, the structure comprises natural fibres and / or synthetic fibres with a glass transition temperature and a melting temperature.

10. The method according to any one of the preceding claims 1-9, characterized in that, the structure is fabricated by means of providing carded, natural fibres and / or synthetic fibres that are oriented randomly.

11. The method according to any one of the preceding claims 1-10, characterized in that, the structure has a density situated between 20 and 150 g/m² per layer.

12. The method according to any one of the preceding claims 1-11, characterized in that, the granular components are obtained by means of providing one or more polymeric materials, and the tearing up, grinding, reducing, micronizing and / or crushing thereof.

13. The method according to any one of the preceding claims 1-12, characterized in that, the granular components are coming from materials chosen from the group of plastic foils, plastic bags, single- or multi-layered plastic plate materials, or combinations thereof.

14. The method according to any one of the preceding claims 1-13, characterized in that, the structure comprises fibres chosen from the group of glass fibres, polyester fibres, ABS fibres, polystyrene fibres, nylon fibres, PA fibres, natural fibres, metal fibres, or combinations thereof.

15. The method according to any one of the preceding claims 1-14, characterized in that, the structure and the granular components are present in a ratio smaller than 50: 50 on a weight base.

16. The method according to any one of the preceding claims 9-15, characterized in that, the fibres have a length between 50 and 400 mm.

17. The method according to any one of the preceding claims 1-16, characterized in that, the heating of the layered structure takes place by means of steam heating, steam injection heating, microwave heating, vacuum heating, or combinations thereof.

18. The method according to any one of the preceding claims 1-17, characterized in that one or more composite materials are subsequently moulded thermally by pressing, vacuum moulding, gluing and / or welding, with the formation of a composite plate.

19. The method according to any one of the preceding claims 3-18, characterized in that, the composite materials are moulded thermally at a temperature which is higher than the melting temperature of the thermoplastic components.

20. The method according to any one of the preceding claims 3-19, characterized in that, the composite materials are moulded thermally at a temperature which is higher than the glass transition temperature of the fibres and lower than the melting temperature thereof.

21. The method according to any one of the preceding claims 18-20, characterized in that, the composite plate is subsequently provided with one or more finishing layers.

22. The method according to any one of the preceding claims 1-21, characterized in that, the resulting plastic composite material is re-used as a raw material for the subsequent execution of the method.

23. A non-woven composite material wherein a non-woven or woven structure is comprised in a thermoplastic matrix, which binds the structure, characterized in that, the composite material comprises a layered structure, which comprises between 5.0 and 50.0 wt.% per layer of structure, and between 50.0 and 95.0 wt.% per layer of thermoplastic matrix.

24. The composite material according to claim 23, characterized in that, the structure comprises fibres chosen from the group of glass fibres, polyester fibres, acrylonitrile-butadiene-styrene fibres (ABS), polystyrene fibres (PS), nylon fibres, polyamid fibres (PA), natural fibres, metal fibres or combinations thereof.

25. The composite material according to claim 23 or 24, characterized in that, the thermoplastic matrix comprises polymers chosen from the group of ABS, acryl, high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP) and polystyrene (PS) or combinations thereof.

26. The composite material according to any one of the preceding claims 23-25, characterized in that, the composite material has a thickness between 2 and 15 mm.

27. The composite material according to any one of the preceding claims 23-26, characterized in that, the composite material comprises 70 to 90 wt.% polymers in the form of flakes and / or micronisate chosen from the group of polypropylene (PP), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyvinyl chloride (PVC), polystyrene (PS), or combinations thereof.

28. The composite material according to claim 27, characterized in that, the micronisate has a particle size between 0.1 and 1.5 pm.

29. The composite material according to any one of the preceding claims 23-28, characterised in that, the composite material comprises 10.0 to 30.0 m% of polyester fibres.

30. The composite material according to any one of the preceding claims 23-29, characterized in that, the composite material is deformable by means of a thermomoulding process and / or a vacuum process.

31. The composite material according to any one of the preceeding claims 23-30, characterised in that, the composite material is at least partially formed into a three-dimensional structure.

32. The composite material according to the claim 31, characterised in that, the three-dimensional structure comprises a honeycomb structure.

33. The composite material according to claim 23-32, fabricated by means of a method according to any one of the claims 1-22.

34. An assembled composite material, comprising at least two mutually adhered composite materials according to any one of the preceding claims 23-33.

35. The assembled composite material according to claim 34, characterized in that, the assembled composite material comprises a central composite material, formed into a three-dimensional structure, which material is enclosed by two planar composite plates, which are adhered at both sides of the central composite material.

36. The assembled composite material according to claim 35, characterised in that, the three-dimensional structure comprises a honeycomb structure.

37. A carrier fabricated from a composite material according to any one of the claims 23-33.

38. The carrier according to claim 37, characterised in that, the composite material is at least partially formed into a three-dimensional structure.

39. The carrier according to claim 37 or 38, characterized in that, the carrier comprises several mutually attached composite materials.

40. The carrier according to any one of the preceding claims 37-39, characterized in that, the carrier comprises a central composite material, which material is formed into a three-dimensional structure, and which material is enclosed by two planar composite plates, which are adhered at both sides of the central composite material.

41. The carrier according to the claim 40, characterised in that, the three- dimensional structure comprises a honeycomb structure.