GB2519249A

GB2519249A - Process and apparatus for manufacturing a multilayer article

Info

Publication number: GB2519249A
Application number: GB1500203.3A
Authority: GB
Inventors: Omer Kutluoglu; Tural Taskent
Original assignee: ENVIRONMENTAL TECHNOLOGY EVOLUTION Ltd
Current assignee: ENVIRONMENTAL TECHNOLOGY EVOLUTION Ltd
Priority date: 2014-01-07
Filing date: 2015-01-07
Publication date: 2015-04-15
Also published as: GB201400232D0; GB201712960D0; WO2015104541A1; GB2550770A; GB2550770B

Abstract

A process for manufacturing a multilayer article comprising recycled plastics including the steps of subjecting material including a foaming agent to a foaming step with the application of heat in a first extrusion unit prior to discharge of a core material from the first extrusion unit; discharging first and second layer material from extrusion units to form first and second layers on first and second faces of the core material respectively; and cutting to form a multilayer article. The process is particularly for manufacturing boards for use in construction or agriculture. The recycled plastics may include co-mingled, mixed or contaminated recycled plastic input materials. A blending and homogenisation step may be included and high shear or aggressive mixing may be applied in an extrusion unit to break polymer chains. The process may include forming further multiple layers (e.g. third and fourth) and including reinforcement elements including continuous fibre mats within the multilayer article. A manufacturing apparatus and computer program operable to control the process are further disclosed. A crack resistant multilayer article including recycled plastics and comprising a foamed core and first and second layers is also provided.

Description

PROCESS AND APPARATUS FOR MANUFACTURING A MULTILAYER

ARTICLE

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the Invention relates to processes for manufacturing a rnultilayer article, to apparatus for manufacturing a multilayer article, tei computer program products for controlling such manufacturing processes, and tc multi-layered articles (eg. planks or boards).

2. Technical Background

Plastic board articles comprising a skin and a core are known. However, the methods of manufacturing such articles have tended to be somewhat time consuming. Such nethods have also tended to require significant energy.

3. Discussion of Related Art Reference may he had to W02002/062530, GB2460838A and W02013038177A1 regarding related methods for manufacturing plastic articles.

Tn W02002/062550A1, processes for forming plastic are described. Prior art Figure 10 of W02002/062550A1 shows a side elevational view of apparatus for utilizing an open mould. Tn Figure 10 there is shown an illustration of an article and the respective process for nianufacturing the article, generally denoted by the numeral 110. Mould 112 is shown as being formed to make a plate article with raised edges. Mould 112 is heated to an elevated temperature of greater than the melting point of the plastic particulates 116 held within container 114. It is disclosed in W02002/O62550Ai that if heating and cooling lines are used in carrier 118 or in mould 112 itself, then cooling fluids could be run through the lines, which would automatically contract the mould as it got cooler, pulling mould 112 away from a formed article. Figure 10 shows an illustration of an article and the respective, process for manufacturing the article, generally denoted by the numeral 110, according to prior art reference W02002/062550A1.

Figure 11 shows a perspective view in the open position of a plastic moulding machine for use in a method according to prior art reference GB2460838 A. Tn Figure 11, machine comprises upper and lower mould halves 12, 14. The mould halves 12, 14 are joined by hinges 16 so that the mould halves can he moved between the open position seen in Figure 11 and a closed position. Each mould half 12, 14 comprises a mould 18, 20 defining a mould cavity 22, 24 for fonning a plastic article. Insulating jackets 30, 32 are shown in Figure 11. Figure 11 shows a perspective view in the open position of a plastic moulding machine for use in a method according to prior art reference GB2460838A.

In W02002/062550A1, Claim 12 therein discloses plastic particulate material being melted to fort-i a skin on male and female complementary moulds, after which the two complementary male and female moulds are spaced apart from one another at a predetermined distance such that the plastic filler material may be sandwiched between the male and female moulds to form a double skinned composite with a plastic filler material in the middle of the two skins.

In GB2460838A, Claim 7 therein discloses that plastic particulate material is melted to form a skin on the moulds. after which expandable filler material is placed on the plastic skin formed in one mould.

Methods disclosed in W02002/062550A1 and in GB2460838\ have the disadvantage that skins must be formed or partially formed first before filler material is added to the mould.

in addition, it is desirable for some applications to provide a skin srtucture which does not consist of a single skin with a unifonn composition. A more complex skin sucture, such as consisting of two or more layers, can provide''advattages. For example, an outer skin can be provided which provides one or more of added su-ength, selected colour, odour. deodour, fire resistance, LIV stahilisation, ready-releasable properties (eg. for formworking applications), or a smooth surface finish (eg fewer or no surface pits due to contmtnants in recycled plastics of an inner skin), anti-microbial properties. An inner skin can be provided which does not possess these properties, but which has a lower cost per unit volume than the outer skin, for exanaple because it is derived from lower-grade recycled materials. Therefore a two layer skin can have the advantage of the outer skin property, and the advantage of a lo\ver overall cost due to a loxver cost per unit volume of the inner skin tnaterial than the outer skin material, where the outer skin tnaterial may he more expensive due to the property it provides, in addition, the inner skin may bind better to a core material than the binding which would be obtained between the outer skin and the core material, which reduces the risk of post-tnatucftire delamination between layers in a layered article.

in W02002/062550A1, page 12 lines 2 to 3 therein disclose "Generally, the expandable foam is activated by the residual heat from the molds." The use of residual heat is also referred to on pages 18, 20 and 27 therein. The use of residual heat leads to a relatively slow manufacturing process when compared to active heating and cooling. Tn W02002/062550A1 Fig. 10 and related disclosures on pages 19 and 20 therein disclose a process for manufacturing an article using plastic particulate material in a pair of moulds.

however, the process of Fig. 10 therein is disclosed to require 60 tninutes, and the mould parts are disclosed to he apart for the first 2$ minutes of the process. The extended process while the mould parts are apart leads to heat loss from the mould, which reduces energy efficiency and increases manufacturing time because heating is slowed down due to heat loss. Furthermore in W02002/062550A1 Fig. 10 the mould parts are cooled while together which keeps the cooling rate of the mould and its contents low, which also increases naanufacturing time.

in GT32460838B, Claim I therein discloses that moulds are first heated while open, then a material to form a skin is added, then one waits for a skin to form, then filler material is added, and then the n ould is closed. The extended process while the mould is open leads to heat loss from the mould, which reduces energy efficiency and increases manufacturing time because heating is slowed down due to heat loss. Furthermore the moulds are cooled while completely closed which keeps the cooling rate of the moulds and its conten low, which also increases manufacturing time.

Methods disclosed in W02002/062350A1 and in GB2460838B have the disadvantages of providing a relatively lengthy manufacturing cycle and of providing a relatively lo\v energy efficiency. Although W02013038177A1 overcomes these disadvantage.s to a significant extent, further improvement is desirable.

SUMMARY OF TIlE INVENTION

According to a first aspect of the invention, there is provided a process for manufacturing a multilayer article, including the steps of: (i) discharging core material from a first extrusion unit in a first discharge, to form an attic] e core portion; (ii) discharging first]ayer material from a second extrusion unit in a second discharge, to form a hrst layer on a first face of the article core portion; (iii) discharging second layer material from a third extrusion unit in a third discharge, to form a second layer on a second face of the article core portion. and (iv) cutting to form a multilayer article.

The article core portion may include plastic. The first layer may include plastic. The second layer may include plastic. The multilayer article may include plastic.

Benefits of the process include: increased tolerance to acceptable raw material input (e.g. more contaminations, greater variety of polymer types and properties, greater mix of polymer types); increased energy efficiency as there arc no hot moulds that are being heated up and cooled down each time a product is made, and enhanced strength properties of the finished product, which may arise due to the pressure and homogenisation inherent to an extrusion process.

The process may he one wherein the second extrusion unit and the third extrusion unit are the same extrusion unit. dvantages are that one less extrusion unit is required, and that the same output material may he used to form the first layer and the second layer, which provides uniformity of the first and second layers.

The process may be one including a step of subjecting material including a foaming agent in the first extrusion unit to a foaming step including an application of heat prior to discharging core material from the first extrusion unit. Advantages are that the core material is fRamed, which increases the strength and rigidity of the finished article, and reduces the density of the article, which makes it easier to handle manually. for example.

The process may be one including a step of providing heat-activated expandable foam plastic material as input material to the first extrusion unit for the core material. An advantage is that plastic material is relatively cheap and relatively light in weight.

The process may he one wherein the heat-activated expandable foam plastic material includes a foaming agent. An advantage is that the heat-activated expandable foam plastic material may be foamed based on the properties of the foaming agent.

The process may be one wherein the process is a manufacturing process tolerant tel the compositions of the first layer materials and the second layer materials and the core material. An advantage is that the composition of the input materials does not have to be tightly controlled.

The process 1-nay he one \vherein the process includes a step of providing co-mingled or mixed recycled plastic input materials. An advantage is that low cost materials may he used. An advantage is that materials that tnight otherwise be sent to landfill or for incineration may be re-used.

The process may be one wherein the co-mingled or mixed recycled plastic input materials are co-mingled or mixed, contaminated recycled plastic input materials. An advantage is that particularly low cost materials may he used. An advantage is that materials that naight othenvise he sent to landfill or for incineration may he re-used.

The process may be one wherein the multilayer article comprises plastics. An advantage is that the article is relatively cheap to manufacture, and is lightweight.

Ihe process may be one wherein the multilayer article comprises recycled plastics. An advantage is that low cost materials may be used. An advantage is that materials that might otherwise be sent to landfill or for incineration may be re-used.

The process may be one wherein the recycled plastics comprise single polymer recycled materials. An advantage is that low cost materials may he used. An advantage is that materials that might othenvise he sent to landfill or for incineration may he re-used.

The process may be one wherein the recycled plastics comprise multiple polymer recycled materials. An advantage is that particularly low cost materials may be used. An advantage is that materials that might otherwise he sent to landfill or for incineration may he re-used.

The process may be one wherein the multilayer article comprises some non-polymer contaminations. An advantage is that particularly low cost materials may be used. An advantage is that materials that might othenvise lie sent to landfill or for incineration may be re-used.

The process may be one wherein the multilayer article includes minerals. An advantage is increased article strength.

The process may he one wherein a multilayer article core comprises relatively hard plastics and a multilayer article first layer and second layer comprise relatively soft plastics. An advantage is a strong article with a low skin abrasion when handled by a human.

The process may be one wherein the multilayer article has consistent properties without detrimental or un-controlled localised concentrations of any one material type or contamination occurring.

The process may he one wherein the multilayer article includes one or more layers comprising mixed plastics which are unstable (e.g. immiscible) in a liquid phase in the absence of shear. An advantage is increased range of input materials.

Ihe process may be one including a blending step of blending different materials which occurs prior to materials entering an extrusion unit. An advantage is improved article uniformity.

Ihe process may be one including a blending step of blending different materials within at least one extrusion unit. An advantage is improved article unibrmity.

The process may be. one in which for an input stream comprising mixed plastic types or containing contamination or other additives, the input steam is homogenised prior to a pre-extrusion blending step or prior to an extrusion step. An advantage is improved article uniformity.

The process may be one including a blending step in which an even dispersal throughout an input stream of all its various constituent elements is performed such that loca]ised concentrations of any one matcnal within the extrusion units are avoided. An advantage is improved attic] e uniformity.

The process may be one such that a faniily of polymers is dominant within a molten polymer such that it creates a matrix in which non-dominant particles and / or contaminants can reside.

The process may he one in which high shear in an extrusion unit containing non-dominant polymer chains is such that the non-dominant polymer chains are broken down into shorter chains allowing better dispersion within a dominant polymer matrix.

The process may be one including a step in an extrusion unit containing polymers, of melting the polymers and mixing the polyners aggressively to break polymer chains, which allows new polymer bonds to form subsequently. An advantage is improved article strength.

The process may be one including a step of using compatihilisers.An advantage is an increased range of input materials.

The process may be one in which homogenisation and blending of input materials occurs within one or more extuders.

Ihe process may be one in which materials in the extrusion units are at temperatures in the range 100°C to 300°C.

The process may he one in which materials in the extrusion units are at temperatures in the range 120°C to 260°C.

The process may be one in \vhich materials in the extrusion units experience pressures in the range of 0.2 MPa to 70 MPa. Advantages are improved article strength and uniformity.

The process may be one in which materials in the extrusion units experience pressures in the range of 10 \fPa to 50 MPa. Advantages are improved at-tide strength and uniformity.

The process may be one in which materials in an extrusion unit experience shear in the range of 0.01 MPa to 10 MPa. Advantages are improved article strength and uniformity.

The process may he one in \vhich materials in an extrusion unit experience shear in the range of 0.1 MPa to 5 MPa. Advantages are improved article strength and uniformity.

The process may be one in which an extrusion unit includes twin-screw extruders, a single screw extruder, a planetary extruder or more than two screws in a screw extruder.

An advantage is improved mixing of materials.

The process may be one including a degassing step to remove volatile gases from molten materials. An advantage is a reduced risk of voids in a manufactured article, or to remove detrimental gases from the molten materials.

The process i-nay he one including a step of Forming a third layer on the first layer or on the second layer, by discharging third layer material from a fourth extrusion unit in a fourth discharge.

The process may be one including a step of forming a fourth layer on the opposite face to the third layer, by discharging fourth layer material from a fifth extrusion unit in a fifth discharge. An advantage is an outer skin is produced, which may have different properties to an inner skin.

The process may he one xvherein the fourth extrusion unit and the fifth extrusion unit are the sanae extrusion unit. Advantiges are that one less extrusion unit is required, and that the same output material may be used to form the third layer and the fourth layer, which provides uniformity of the third and fourth layers.

The process may he one wherein multiple further Liyers are discharged or placed onto previously discharged layers, from extrusion units, or from elsewhere.

The process may he one in which shear, heat and pressure arc applied to materials in the extrusion units.

The process may be one including a step of including one or more reinforcing elements in the multilayer article. An advantage is a stronger article, but which is produced with only a small change to the process.

The process i-nay he one in which a reinforcing element is a continuous fibre material, such as a fibre mat or mesh, and snch mats or meshes are made ont of woven or uni-directional fibre materials, made from one or more of glass, aratnid, nylon or other polymer types, hemp, carbon, metal, or organic materials.

The process may be one iti which reinforcing elements are sheets, plates, rods, bars or wires.

The process may he one including the step of short reinforcing elements being fed into a paste within an extrusion unit such that the short reinforcing elenients are blended into the paste at the extrusion stage. advantage is a stronger article, hut which is produced with only a small change to the process.

The process nay be one in which short reinforcing elements are one or tnore of short fibres made from glass, araniid, nylon or other polymer types, hemp, carbon, metal, or organic materials.

Ihe process may be one in which a paste in an extrusion unit includes a material (eg.

maleic acid or maleic anhydride) to enhance a bond between the reinforcing elements and plastics.

The proce.ss may be. one including use of a die system which integrates all inpu as article, layering within the die system and forms the finished article. An advantage is a compact process which may he used to produce a relatively complex article.

The process may be one induding one or more high pressure devices to feed materia's into the die system. An advantage is that mixing and high pressure extruding may be performed in separate steps, which may produce better contrcil over the manufacturing process.

The process n-lay be one in which reinforcing dements are fed into an artick being formed at the die system. An advantige is a stronger article, but \vhich is produced with a simple change to the process.

The process i-nay he one in which output From the die system is drawn away and cooled down to Form a product in a continuous process.

The process may be one in which steel bands on rollers are used to draw away output From the die system.

The process may be one in which feedback from sensors is used by a computer to ensure a stabilization of parameters of a manufactured article. ad\Ta1tage is improved contnti of the manufacturing process.

The process 1-nay he one in which the process is a continuous process. An advantage is improved efficiency over hatch processes.

The process may be one in which the process uses input granules including granules in the range of 5 mm to 35 mm in characteristic size. An advantage is that relatively coarse input materials may be used.

Ihe process may be one in which the process includes iow melt flow polymers as input materials. An advantage is that naaterials difficult to recycle naay he used.

The process may be one in which the article is a plank or a board. An advantage is ready use in construction or in agriculture, the process may be one in which the article is barge covering or container flooring.

The process may be one in which the artide is between 1/2 feet (15.24 cm) and 15 feet (457.2 cm) wide.

The process may be one in which the artide is between 4 mm and 80 mm thick.

The process may be one in which the at-tide is between 10 mm and 50 mm thick.

According to a second aspect of the invention, there is provided a manufacturing apparatus for manufactunng a multilayer article, the apparatus including a first extrusion unit, a second extrusion unit, a third extrusion unit, and a cutter, the first extrusion unit, the second extrusion unit, and the third extrusion unit arranged such that: (i) core material is dischargeable from the first extrusion unit in a first discharge, to form an article core portion; (ii) first layer material is dischargeable from the second extrusion unit in a second discharge, to form a first layer on a first face of the article core portion; (iii) second layer material is dischargeable from the third extrusion unit in a third discharge, to form a second layer on a second face of the article core portion, and the cutter is arranged to cut to form a multilayer article.

Benefits of the apparatus include: increased tolerance to acceptable raw material input (e.g. more contaminations, greater variety of polymer types and properties, greater mix of polymer types); increased energy efficiency as there are no hot moulds that are being heated up and cooled down each time a product is made, and enhanced strength properties of the fitushed product, which may arise due to the pressure inherent to an extrusion process.

the manufacturing apparatus nmay be one in which the second extrusion unit is die same extrusion unit as the third extrusion unit. Advantages are that one less extruston unit is required, and that the same output material may he used to form the first layer and the second layer, which provides uniformity of the first and second layers.

The manufacturing apparatus may be arranged to perform a process of any aspect according to the first aspect of the invention.

According to a third aspect of the invention, there is proved a computer program product for running on a computer, wherein the computer program product when running on a computer is operable to control a process of any aspect according to the first aspect of the invention An advantage is improved control and ease of alteration of manufacturing processes.

According to a fourth aspect of the invention, there is provided a crack resistant multilayer article comprising a foamed core, a first layer on a first face of the article core, and a second layer on a second face of the article core, wherein the article includes recycled plastics, wherein the article has a ilexnral modnlns in a range of 1500 MPa to 4000 MPa, and wherein the article is, for example, a plank or a hoard, or barge covering or container flooring. Crack resistance may be manifested for example by the article not cracking when a nail is hanunered into it, or by the article not cracking when a screw is screwed into it. Advantages are that the device is relatively stiff bnt crack resistant. The crack resistant multilayer article may be shatter resistant. the article may be made using processes according to a first aspect of the invention.

The crack resistant multilayer article may include a further layer or a further plurality of layers.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the invention will now he described, by way of example only, with reference to the following Figures, in which: Figure 1 shows an exaniple of a process used in preparing materials for rnanutacturing plastic articles using recycled plastic comprising multiple polymer types as well as some contaminations as the input materials, for use in a plastic extrusion rnanufhcturing process.

Figure 2 shows three examples of processes used in homogenising and blending materials for manufacturing plastic article.s using recycled plastic comprising multiple polymer rpes as well as some contaminations as the input materials, for use in a plastic extrusion manufacturing process.

Figure 3 shows an example die configuration For board manufacturing, in which the two skins of the board are each created within their own die and these dies are in parallel, and then the two skins are integrated with the core layer in a second stage die in series.

Figure 4 shows an example of reinforcing sheets being incorporated in an article during an extrusion manuacturing process.

Figure 5 shows an example method of drawing the product away from the die whilst cooling it and maintaining the form within required dimensional tolerances by using steel bands moving on rollers, with such bands at the top and hottona faces of the product, for example if making hoards.

Figure 6 shows an example of an upper skin, a core and a lower skin materials once well homogenised being brought together in a die.

Figure 7 shows an example of upper skins, a core and lower skins materials once well homogenised being brought together in a die or dies.

Figure 8 shows an example of a cross section of a product which may be manufactured by an extrusion process.

Figure 9 shows an example of a cross section of a product which may be manufactured by an extrusion process.

Figure 10 shows an illustration of an article and the respective process for manufacturing the article, generally denoted by the numeral 110, according to prior art reference W02002/062530A1.

Figure 11 shows a perspective view in the. open position of a plastic moulding machine for use in a method according to prior art reference GB2460838A.

DETAILED DESCRIPTION

There are provided processes for manufacturing plastic articles. There are provided processes using treatment techniques for handling, cleaning, sorting and size-reduction of plastics, honiogenisation techniques, blending techniques, extrusion techniques and forming techniques. There is provided a plastic article manufactured using combinations of these techniques in processes. There are provided methods within the rnanufhcturing processes for strengthening the finished articles.

There are provided methods of manufacturing plastic articles which are well-suited to the use of recycled plastics in the manufacturing method, but which are not necessarily limited to the use of recycled plastics. there are provided methods of manufacturing plastic articles which are well-suited to the use of input materials for the manufacturing method which contain multiple types of plastics. and which materials may contain some non-polymer contaminations. Such methods are highly applicable in the use of recycled materials.

In an example, the processes for manufacturing plastic articles are used to make a hoard for use in construction or agriculture. In this example such boards would be used in a variety of applications in place of plywood produc or other plastic or wood panel products. An example of an application in construction would he as a shuttering panel in forinwork 2u1d fialsework, where properties such as high strength. stiffness, good surface finish, good surface release properties, a relatively low weight and safety in handling are all features that this process for manufacturing plastic articles can accommodate.

In an example, different plastics are used in the present manufacturing methods. One example is styrenic polymers. Examples include polystyrene (PS), acrylonitrile butadiene styrene (ABS), and high-impact polystyrene (I liPS). Other examples of different plastics include poly-olefins, eg. polyethylene (PE) and polypropylene (PP). Different pFastics may be either homogenised or blended or both, with such blending occurring either prior to extrusion or during extrusion or both prior to and during extrusion.

In an example recycling process, plastics to he recycled are sorted into relatively hard plastics and relatively soft plastics. Plastics in each class then undergo cleaning to excess dirt, food waste., sticky labels, and the like. Plastics in each class are shredded into piece.s with a characteristic size of less than about 100 mm, then dc-dusted, cleaned again, then shredded, granulated or agglomerated into pieces with a characteristic size of about 35mm to 2mm. Pieces may he turned into finer grains (eg. characteristic size less than 2 mm) for use in a manufacturing process.

Tn an example recycling process, plastic pieces of a wide range of sizes may be seated by polymer type, colour, density, size, hardness, electrical conductivity, by additives, or by any combination of these criteria, and such sorting may occur at any stage within the process. Such sorting may also include sorting large or particular non-polymer contiirrinants, such as metal pieces, to remove them from the polymer materials. this stage may be called a "Primary Sorting" and / or "Screening".

in an example recycling process, materials cleaned and sorted in the "Primary Sorting" and "Screening" may then he size-reduced and further cleaned and screened. Size-reduction can occur via shredding, granulation, agglomeration or densification processes, or any con bination of these processes. Additionally, materials can be cleaned using vet and / or dry cleaning systems, metal separation systems, air, density or size classification systems. Additionally, tnaterials can be further purified using more advanced techniques such as with classification assemblies using near infra-red (NIR) screening, X-ray screening, laser screening, optical colour screening. The sequencing of particular processes may vary.

Figure 1 shows an example of a process used in preparing materials for manufacturing plastic articles using recycled plastic comprising multiple polymer types as well as some contaminations as the input materials, for use in a plastic extrusion manufacturing process.

in an example recycling process, a mix of relatively clean plastic pieces of size 2nun to 50mm comprising differing types of polymer may be homogenised prior to blending or prior to extrusion. these particles may be homogenised through a homogenisation process. Examples of such a honiogenisation process could he hulk homogenisation through a system such asa large-scale mixing during storage or through blending within a blending silo, fountain blender or honaogenisation silo. Other particle homogenisation techniques can also be. used. in this step it is intended to ensure an even dispersal throughout the input stream of all its various constituent elernen such that localised concentrations of any one type of material or contarninafion within the extruders are avoided. In this way it is intended to achieve consistent properties of the finished articles being manufactured without detrimenta' or un-controlled]ocahsed concentrations of any one material type or contamination occurring within the finished article.

Tn an example, the re]ativdy soft pastcs may be used to form a skin of an artide manufactured using the manufacturing methods disclosed, vhde the rdativdy hard plastics may be used to form a core of an article manufctured using the manufcturing methods disclosed. However, such an arrangement may lead to an article, surface which is softer than desired (e.g. more prone to scratches or te.aring. and to a core which is more brittle than desired eg. too likely to crack under mechanical shock. Consequently, in the manufacturing methods disclosed, the skin may be formed using a blend oF the relatively soft and relatively hard plastic materials, and the core may also he formed using a blend of the relailvely soft and relatively hard plasfic materials, but where the surface comprises relatively nore soft plasfic materials than the core. Other materials may be added to a blend of relatively soft plastics materials and relatively hard plastics materials: an example is that rubber types may be added for impact resistance. Blending can occur before materials are fed into rn exuder. Blending crn occur within an extruder.

Different input streams of input materials may lie used, such as from different suppliers of recycled plastic input materials. for example. Each input stream may contain many different types of po'ymer as wefl as contaminations. Different input streams may he used in paralld in the same manufacturing process. for exampk. Other input streams are possiHe, such as more contaminated materials, or non-poh'mer additives or po'ymer addffives or any combinadon of these. For example minerals such as talc, calc, or other types of fillers Imay be added. Other types of addffive may be used, such addffives impardng particular properfics or benefits to the finished arficles. One example of such an addiñve could be so-called compaflbilisers. Virgin materials or single-polymer recycled materials may also be used.

The materials used to form a skin of an artick m,uufactured using the manufacturing methods disclosed may comprise plastic granules, pellets, flakes, agglomerate, or powder material, these materials can be thermo-set plastics or therrno-plastics, or therrno-plastic rubber or rubber. these materials may contain additives. these materials may contain contaminants. These materials may contain some or all of the above at the same time.

The input materials used to form a core of an article manufactured using the manufacturing methods disclosed may comprise heat-activated expandable foamed plastic granulated material. These materials can be varied fonns of polymer, elastomer or rubber, such as thenno-set plastics or thermo-plastics or thermo-plastic rubbers or rubbers. T Teat-activated expandable foam plastic material may include or comprise heat-activated expandable foamable plastic material. Such heat-activated expandable foam plastic material will typically include a foaming agent. Known foaming agents include blowing agents and surfactants. there are rtvo main types of blowing agents: those which are gases at the temperature at which the foam is formed and those that generate gases by a chemical reaction. Carbon dioxide, pentane. steam and chlorofluorocarhons are examples of the former. Blowing agents that produce gas via chemical reactions include baking powder, sodium bicarbonate, azodicarbonamide, hydroxypropane tricarboxylic acid and titanium hydride. Blowing agents may be dosed into the core layer paste within the core layer extruder, or may he blended into the core layer materials prior to the core layer materials entering the extruder. the materials used to fonn the skin and/or core may comprise any of powder, pellets, shavings, Bakes, chunks, granules, agglomerate or the like.

\Vhere any input stream comprises mixed plastic types or contains contanunation or other additives, the input stream should preferably he homogenised prior to blending or prior to extrusion. The best homogenisation is achieved at the stage where particle sizes are in the range of 50mm or less. The input stream is to he homogenised through a homogenisation process. Examples of such a homogenisation process could be bulk homogenisation through a system such as a large-scale mixing during storage or through bulk-blending within a blending silo or honogenisation silo. Other particle homogenisation techniques can also be used. in this step it is intended to ensure an even dispersal throughout the input stream of all its various constituent elements such that localised concentrations of any one material within the extruders are avoided. In this way it is intended to achieve consistent properties of the finished articles being manufactured without detrimental or un-controlled localised concentrations of any one naaterial type or contrnnination occurring within the finished articles.

Additionally, there may he several different input streams and some or all of these may be homogenised together. If post-homogenisafion more than one input stream is to he used, then Nending of these streams may be required. Bknding can occur prior to material entering the extruder or can occur through controlled feeding into different input ports in the extruder, but in both cases the rebtive quantities of the different input streams are controlled such that a targeted bknd within the extruder barrel is u]ttrnatdy achieved.

The further homogenisation and bknding of the input materia's then occurs within the extruder or e.xtruders. The. material is subjected to pressure., heat and shear. in an example., the temperature within an extruder or extruders may be in the range of 100°C to 300°C. In a preFerred exampk, the temperature within an extruder or extruders may be in the range of 120°C to 260°C. In an example, a pressure within an extruder or extruders may he in the range of 0.2 MPa to 70 MPa. Tn a preferred example, a pressure within an ocftuder or extruders may be in the range of 10 MPa to 50 MPa. In an example, a shear within »=rn exftuder or exu-uders may be in the range of 0.01 MPa to 10 MPa. In a preferred exarnpe, a shear within an extruder or extruders may he in the range oF 0.! MPa to 5 MPa. the p1asc particles may be melted within the exkudcr through a combina6on of heat and pressure, but it is typically mostly with the shearing ac6on within the extnider that further homogenisation and blending is achieved. In an exaniple, to achieve a high level of shear and consecuent material blending. co-rotating flvin-screw extruders are used. In another exampk a single screw extruder is used. In another examp'e a ccpanetafl? extruder is used.

The bornogenisation. blending and extrusion processes may thereFore be used together to produce a relatively homogeneous and well blended paste coming out of the exüuder, having started from relafively inhomogeneous input materials, such as co-mingled or mixed, contaminated recycled plastic materials for example. A melt filter may also be.

incorporated within the extrusion system to further aid the removal of non-n olten contmination particles from the melt. A degassing process nay also be incorporated within the extrusion system to further aid the removil of volatile gases from the melt. A relatively hn)geneous material may therefore be developed from a process combining some or all of the Primary Sorting techniques such as sorting, screening, size-reducing.

cleaning and classifying, and then homoge.nising, blending and extruding or alternatively then hornogenising extruding and blending within the extruder. the materials are thus well homogenised to achieve consistency, and blended to achieve further consistency and to achieve defined characteristics within the finished articles, and these materials thus exit the extruder as a blended and consistent hot paste. An example of the importance of careful blending would be to ensure that one family of polymers can be dominant within the melted polymer such that it can create a matrix in which non-dominant particles and / or contaminants can reside. An example of the importance of using the right type of extrusion technique is the generation of high shear within the melt mixture, such that the non-dominant polymer chains are broken down into shorter chains allowing better dispersion within the dominant polymer matrix. Melting the polymers and mixing them aggressively may serve to break the polymer chains. By breaking polymer bonds when breaking the polymer chains, and allowing new polymer bonds to form subsequently.

product stiffness may be increased.

Figuf e 2 shows three examples of processes used in homogenising and blending materials for manufacturing plastic articles using recycled plastic comprising multiple polymer types as \vell as some contaminations as the input materials, for use in a plastic exkusion manufacturing process. in example 1, homogenised material 1, homogenised material 2, and optionally homogenised material 3, are added to additive 1 and optionally additive 2 is added, and the materials are blended together at a blending stige. The blended material is then provided to an extrusion stage. In exaniple 2, homogenised material 1, homogenised material 2, and optionally additive 2, are blended at the blending stage. Following blending, additive I and optionally homogenised material 3 are added to the blended material and the extrusion stage. Tn example 3, homogenised material 1, homogenised material 2, additive 1, and optionally homogenised marerial 3, and optionally additive 2, are brought together in an extrusion stage.

it may be necessary to blend materials into the material paste or pastes within the extruder or extruders to enhance characteristics of the finished article. For example compatibilisers are such materials that may act to enhance the bonds between different types of plastics and thereby make the finished article stronger. Examples of compatil)ihsers are block co-polymers such as SEBS (styrene-ethylene / buiylene-styrene) or SE.PS (styrene-ethylene / propylene-styrene. For example mineral fillers or extenders such as calcium carbonate (chalk) or magnesium silicate (talc) may be added to stiffen the finished articles. Other examples of properties that may be enhanced by including addifives into the paste at this stage are fire retardation, thermal conductivity (heat dissipation), cosmetic colouring, anti-microbial, anti-graffiti, anti-slip, anti-oxidant.

fragrance, impact modification, and UV stability. P]astici2ers may be used to soften the product if it \voud be too stiff otherwise.

This paste may be formed in a die. The finished artide may comprise many layers. These distinct layers and their arrangement within the finished article may impart pat-flcuar properties to the finished artide. An extruder may be used for each byer Ot ayer type.

That is to say if tvo or more identically composed layers are used within the. finished article, structure then it may be preferential to create more than one layer from the. same.

extruder by dividing the extruder output beFore feeding into a die or dies. Multiple extruders may he used to make multiple different layers. One extruder may be used to make the paste for the core layer. If the core is comprised of more than one layer then more than one core extruder nay be required. Each extruder produces its own pre-determined paste. These pastes may all need to be formed and brought together in a die.

lo make a product with multiple layers, there may he many difFerent extruders For the multiple layers of skins and core, with each extruder producing i own pre-determined paste. these pastes may all need to be formed and brought together in a die or within a series of dies.

Surface layer thickness may he at least 0.01 mm. Surbnce layer thickness may lie less than 3.0 cm. SurFace layer thickness may be tess than 1.0 cm. Surface layer thickness may he tess than 1.0 mm.

A purpose of the die or dies is to give and maintain a desired shape. or form and can also be to combine more than one input together. the die or dies is / are. designed to be fed with multiple inpu and to force the integration of these different streams into a single.

cohesive output and to form this output. lnpu to the die. can be one or more exftude.r outputs, reinforcing elements, or any combination of these. The. process nay use a single.

die, or several dies. If fed with multiple inputs, the die or dies integrate all inputs as article layering within the die or dies and form the finished article. The process may use more than one die, in series and / or in parallel, each die with single or multiple inputs to forms individual layers or combinations of layers, and then a later die or later dies to integrate and form these layers or layer combinations into the article. If more than one die is used it will he preferable for the dies to he in close proximity to each other to maintain pressure within the system. In an example die configuration for board manufacturing, the two skins of the board are each created within their own die and these dies are in parallel, and then the two skins are integrated with the core layer in a second stage die in series.

An example is shown in Figure 3. Multiple die stages may be integrated into a single die or single die block.

To bring these materials together in the die and maintain good properties for the finished articles, the materials may need to be fed into the die under high pressure. A high shear extruder may not provide adequate high pressure, therefore it may be necessary to add a device between each extnider and the die. Examples of such a device could he a melt-pump attached to the end of an extmder for example, or the inclusion of a second extruder between the First extnider and the die.

It may be desirable to add reinforcement to the finished articles. An example could be the case where the Finished article is a panel ro he used in the construction industry for forinworks and high flexural strength is required. in such cases where it is desirable to sftengthen the finished article, reinforcement elentents may be fed into the article being formed at the die or dies. Examples of such elements could be continuous fibre materials.

eg. fibre mat or ntesh, and such mats or nteshes could he ntade out of woven or uni-directional fibre materials. niade from glass, araniid, nylon or other polymer types, hemp.

carbon, metal, or organic materials. Other reinforcement elements could he any of sheets, plates, rods, bars or wires which could also he fed into the article being formed at the die or dies. An example could he to include aluminium sheet material between two separate skin layers, on each side of the finished article. Figure 4 shows an example of a plastic exusion process wherein fibre sheets reinforcing elements are inftoduced into the process at the die or dies.

if reinforcing elements are fed into the article being formed at the die or dies, it may be necessary to blend certain materials into the material paste or pastes xvithin the extnider or extruders for a layer or layers of the finished article conung in to contact tvith the reinforcing element. Such materials act to enhance the bond between the reinforcing element and the plastics within the paste. Lxarnples of such materials could be organic compounds such as rnaleic anhydride.

In such cases where it is desirable to strengthen the finished article, reinforcing elements may be fed into the paste within the extruders such that the reinforcing elements are blended into the paste at the extrusion stage. Examples of such elements could be short fibres made from glass, aramid, nylon or other polymer types, hemp, carbon, metal, or organic materials. Short fibres are non-continuous fibres of short length, generally in the range of 4mm to I Onun long.

Where short fibres are fed into the paste within the extruders such that the. short fibres are blended into the paste at the extrusion stige, it may be necessary to blend certain materials into the material paste or pastes within the extruder or extruders. Such materials act to enhance the bond between the reinforcing element and the plastics within the paste. Examples of such materials could he organic compounds such as maleic anhydride acting to enhance the bond between plastics and other materials such as short fibres (e.g. short glass fibres), glass fibres, and metals.

The output from the die is drawn away and cooled down to form a product in a continuous process. Maintenance of the form of the output may be required as the output is drawn away and cooled. Additional fornting of the output may he required as the output is drawn away and cooled.

An example method of drawing the product away from the die whilst cooling it and maintaining the form within required dimensional tolerances could he to use steel bands moving on rollers, with such bands at the top and bottom faces of the product, for example if making boards. in this example the steel bands are cooling the product while maintaining the form and drawing the product away from the die. Figure 5 shows a possible example of the configuration of this part of the manufacturing process.

in an example method of drawing the product away from the die whilst cooling it and maintaining the form within required dimensional tolerances using steel hands moving on rollers such that there are bands at the top and lxttom faces of the product, the distance be.tveen the. top and bottom stee.l bands may be. varied for varying thickness requirements of the finished articles, for example if making boards of 9mm, 12mm or 18mm thick.

After cooling, the output may he cut into the final required sizes. An example of this would he to cut the output into rectangles of 8 feet by 4 feet, being a common size for sh uttering panels.

The product produced may be cut to form boards. A board may incorporate reinforcing materials. A skin or any layer of an article may include short fibres or a fibre sheet or mat which strengthens the product. A skin or any layer of an article may include other types of reinforcing elements which strengthen the article. Reinforcing sheet or sheets may be incorporated in an article during an extrusion manufacturing process, either in single or multiple layers. An example is shown in Figure 4. Short fibres may he incorporated into an article during an extrusion manufacturing process.

Materials for a core or any skin layer may first need to be size-reduced to a particle size appropriate for input into the extrusion process. An example would be to shred, granulate or agglomerate plastic into particles of approximately 2mm to 35mm diameter. Particles can be in many forms such as flakes, granules, powder or film fragments, providing that they may be free-flowing enough to be homogenised and can be fed into the extruders.

These particles may then he homogenised through a h mogenisation process. Examples of a particle homogenisation process could he bulk homogenisation through a system such as a large-scale mixing during storage or blending within a blending silo or homogenisation silo. Alternatively another example of homogenisation could he continuous blending of particles continuously dosed from different sources of material, so rather than bulk blending a large single volume of material one can continuously blend small quantities of material taken continuously from several volutnes.

Materials for a core may be extruded from an extruder, the materials being subject to shear, heat and pressure in the extruder. Materials for an upper skin may be extruded from an extruder. the materi2ds being subject to shear, heat and pressure in the extruder.

Materials for a lower skin may he extruded from an extruder, the materials being subject to shear, heat and pressure in the extmder. }-ionaogenisation and blending of the plastic materials are occurring within the extruders and the pressure, heat and shearing action within the extruders is achieving this frirther honaogenisation and blending. bor example, co-rotating twin screw extruders may he used here to achieve a high level of shear.

The upper skin or skins, core and tower skin or skins matenas once well homogenised will need to be brought together in a die or dies. Examp'e process configurations are shown in Figures 6 and 7.

To bring these materials together in the die or dies and maintain good propernes for the finished artides, the materials need to be fed into the die under high pressure. A high shear extruder may not provide adequate high pressure, therefore it may be necessary to add a device between each extruder and the die. Examples of such a device could be a melt-pump attached to the end of an extruder or the inclusion of another extruder between the extruder and the die.

The outputs from the die or dies are then drawn away and cooled down to form a product in a continuous process. Additional forming of the output may be required as the output is drawn away and cooled. Hxampes are shown in Figures 4, 5, 6 and 7.

Materials for a core may be extruded from an exu-uder, the materials being subject to heat, shear and pressure in the extruder. Materials fbr an upper outer skin may he extruded from an extruder, the materials being subject to heat, shear and pressure in the extruder. Materials for an upper inner skin may he extruded from an extruder, the materials being subject to heat, shear and pressure in the extruder. Materials for a o\ver inner skin may he extruded from an extruder, the materials being subject to heat, shear and pressure in the extruder. i\'laterias for a tower outer skin may he extmded from an extruder, the materials being subject to heat, shear and pressure in the extruder.

The further homogenisation and blending of the plastic materials occurs within these extruders and the shearing action withul the extruders is achieving this further homogenisation and blending. Co-rotating twin screw extruders may be used to achieve a high level of shear -for example.

Once the upper outer skin material, upper inner skin material, core material, lower outer skin material and lower inner skin material are all well homogenised, they may need to be brought together in a die or dies. Examples re shown in Figures 3, 4, 5 and 7.

To bring these materia's together in the die and maintain good properties for the hnished artides, the materials may need to he Lcd into the die under high pressure. As high shear extruders may not provide adequately high pressure, it may therefore be necessary to add a device or devices between each extruder and the die. Exarnpes of such devices cou'd he rneft-purnps attached to the end of each extruder, or the inchision of another extruder between each extruder and the die.

The outputs from the die are then drawn away and cooled down to form a product in a continuous process. Additional forming of the output may he required as the output is drawn away and cooled.

Examples arc shown in Figures 4, 5, 6 and 7.

A product produced in a plastic extrusion process may include multiple layers, each layer being exudcd from a respecve exuder. For example, an upper skin of a manufactured ar6cle may include an upper outer skin and an upper inner skin, each skin being cxfiuded from a respective extruder. Examples are shown in Figures 4, 5 and 7.

In an extrusion manufacturing process, the manufacturing line may include a hot zone with hotter temperatures near to exits From extruders, and a cold zone with colder temperatures ffirther down the production line, away from extruders. This arrangement provides a large increase in viscosity oF the extruded materia's as the extruded materials travel away from the e.xtruders and coo1 down, which enables the formation of a rigid product.

When a fibre sheet is provide.d for an ardcle to be manufactured using an exftusion process, it is desirable for extruded polymers to flow into the fibre sheet and to grip the.

hhre sheet, so as to reduce the scope for delamination after manufacture. A bonding agent may he used to improve bonding heiween extruded polymers and a fihre sheet. An example of a bonding agent is maleic acid or maleic anhydride. Maleic acid or maleic anhydride. may be used as a bonding agent at a weight concentration in a skin layer of 01% to 15%. For example, maleic acid or maleic-anhydride may be used as a bonding agent at aweight concentration in a skin layer of 1.0% to 1.5%.

Tn an extrusion process, pressure is used to extrude polymer material from a respective extruder. Pressure, heat and shear may be used to overcome a lack of homogeneity in a mixture of polymers. Pressure may be adjusted according to different polyner composition mixtures and resulting viscosity. Rollers may be used to move manufactured materials along a production line. Tn a manufacturing process, feedback from sensors may be used to control the manufacturing process. For example, if a manufactured article is too thin, as sensed by a thickness sensor, the pressure in one or more extruders may be increased to provide more material, or the speed of the advance along the production line may he reduced, to allow more extruded material to accumulate and to thicken the product, or the die gap can he varied.

A manufacturing process may be fully automated so that feedback from sensors is used to ensure a stabilization of parameters of a manufactured product. For example, thickness unitormity. surface roughness and weight may he measured. Weight measurement may he used to check for density. An unexpectedly low density may be an indication of voids in the product, for example.

An extrusion unit (e.g. for extruding a skin or layer, or fbr extruding a core) may include a hack pressure release system, which prevents the pressure within the extrusion unit from exceeding a threshold. Such a back pressure release system may he provided for safety reasons, and/or to help to control pressure in the extrusion system during a manufacturing process. Such an extrusion unit may he used For producing a foamed material in a controlled way.

Tn a continuous manufacturing process, such as shown for example in Figures 4, 5, 6 and 7, the product may be provided with improved strength. A continuous manufacturing process provides efficiency improvements over single item manufacture or batch processes, such as are described for example in W02002/062550. GB2460838A and \V02013038177A1, because in a continuous manufacturing process the apparatus does not need to undergo relatively large cycles of heating and cooling, which use energy.

instead, in a continuous manufacturing process, different parts of the continuous manufacturing line are maintained at relatively constant temperatures, which means that relatively large cycles of healing and cooling are not required, and energy efficiency is therefore improved.

Because input materials are mixed in an extruder apparatus, to produce a relatively homogeneous mixture of input materials (eg. a paste), in contrast to processes in which extruder apparatus is not used, and in which therefore inhomogeneities may lead to product defects, an extrusion manufacturing process produces an enhanced tolerance to varIations within the input materials used.

Because input materials are mixed in an extruder apparatus. relatively large granules of input materials, such as 8 mm to 10 mm in characteristic size, or 5 mm to 35 mm in characteristic size in another example, may he used. This is an advantage over manufacturing processes in which powders must he prepared For manufacturing, because for example more grinding of input materials is required to produce materials with smaller characteristic sizes, such as for powders. Examples of processes which use powders are disclosed in W02002/062550, G132460838A and \X102013038177A1, for example. there is a further advantage over manufacturing processes in which powders must be prepared for manufacturing, because more tolerance exists towards impurities.

For exaniple. s2uld particles may damage po\vder producing apparatus, such as by damaging milling blades, for example.

An advantage of an extrusion process is that pressure may be varied so as to improve the flow of low melt flow polymers. For example, plastic bags may include low melt flow polymers. These low melt flow polymer materials are better suited to use in extrusion manufacturing processes than to use in manufacturing processes which use low pressure, such as are disclosed in W02002/062550, GB2460838A and W02013038177A1, for example. therefore an extrusion process is better suited for recycling plastic bag materials than a plastic particulate moulding process.

An advantage of a shear-based extrusion process is that a relatively stable phase of mixed plastics may he achieved. \vhereas the mixed plastics may he unstable (eg. immiscible) in the liquid phase in the absence of shear. A layer in a multilayer product (eg. a board) made using an extrusion process may include at least one layer including a mixture of plastics that is unstable (e.g. immiscible in the liquid phase in the absence of shear.

An advantage of an extrusion process is thai the pressure inherent in such a process may lead to a stronger product (eg. a board) when compared to prior art processes such as those disclosed in W02002/062550, GB2460838A and W02013038l77A1, for example, in which the pressures inherent such processes may be lower.

Figure 8 and Figure 9 show examples of products which may be manufactured by an extrusion proce. Material produced using the processes shown in, or disclosed with reference to, Figures 1 to 7, may be cut into boards, such as are shown for example in Figure 8 in cross section, or in Figure 9 in cross section.

The process may he one in which the article (eg. hoard) core is made from heat-activated expandable Foam plastic material. The process may he one wherein the heat-activated expandable foam plastic material includes heat-activated expandable foatnable plastic material. The process may be one wherein the process is a manufacturing process tolerant to the compositions of the outer layer materials and the heat-activated expandable foam plastic material.

The process may he one in which the article (eg. hoard) includes recycled plastic. The recycled plastic may he comingled contaminated recycled plastic. The process may he one in which the article (eg. hoard) includes non-recycled plastic. The process may he one in which the article (eg. board) includes elastomeric material. The process may he one in which the article (eg. board) includes rubber. The process may he one in which the article (eg. board) includes a blend of plastics. The process may he one wherein the board is no less than 1/2 feet x 2 feet. (1/2 feet x 2 feet = 15.24 cmx 60.96 cm. 1ie process may be one wherein the board is no bigger than 100 feet x 15 feet. (100 feet x 15 feet = 3048 cmx 457.2 cm). The process may be one wherein the article (eg. board) is no thicker than 200 mm. the process may be one wherein the article (eg. board) is no thicker than 80 mm. the process may be one wherein the article (eg. board) is no thinner than 4 mna. The process may he one wherein the article (eg. hoard) thickness is in the range of 10 mm to 50 mm. Note

It is to he understood that the above-referenced arrangements are only illustrafive of the application for the principles of the present invenfion. Numerous modificaflons and alternative arrangements can he devised without departing from the spirit and scope of the present invention. While the present invention has been shown in the drawings and fully described above with particularity and detail in connection with what is presettly deemed to be the most practical and prefcrred example(s) of the invention, it will he apparent to those of ordinary skill in the art that numerous modifications can be made without departing from the ciples and concepts of the invention as set forth herein.

Claims

CLMMS1. A process for manufacturing a mulfilayer article, including the steps of: (i) discharging core material from a first extrusion unit in a first discharge, to form an attic] e core portion; (ii) discharging first]ayer material from a second extrusion unit in a second discharge, to form a first layer on a first tace of the article core poon; (iii) discharging second layer material from a third extrusion unit in a third discharge, to form a second layer on a second face of the article core pothotb and (iv) cutting to form a multilayer article.

2. Process of Claim 1, wherein the second extrusion unit and the third extrusion unit are the same extrusion unit.

3. Process of any previous Claim, including a step of subjecting material including a foaming agent in the first extrusion unit to a foaming step including an application of heat prior to discharging core material from the first extrusion unit.

4. Process of any previous Claim, including a step of providing heat-activated expandable foam plastic material as input material to the first extrusion unit fbr the core material.

3. Process of Claim 4, wherein the heat-activated expandable Foam plastic material includes a foaming agent.

6. Process of any previous Claim, wherein the process is a manufacturing process tolerant to the compositions of the first layer materials and the second layer materials and the core material.

7. Process of any previous Claim, wherein the process includes a step of providing co-mingled or mixed recycled plastic input materials.

8. Process of Claim 7, wherein the co-mingled or mixed recycled plastic input materials are co-mingled or mixed, contaminated recycled plastic input materials.

9. Process of any previous Claim, wherein the multilayer article comprises plastics.

10. Process of Dairn 9, wherein the muRdayer artide comprises rccyckd p'astics.

11. Process of Cairn 10, wherein the recyded pbstics cotnptisc singk poymcr recyded rnaterias.

12. Process of Claim [0. wherein the recycled plastics comprise multiple. polymer recycled materials.

13. Process of any of Claims 9 to 12, wherein the multilayer article comprises some non-polymer contaminations.

14. Process of any of Claims 9 to 13, wherein the mulfilayer article includes ninerals.

15. Process of any of Claims 9 to 14, wherein a multilayer article core comprises relatively hard plashcs and a mullayer article first layer and second layer comprise relatively soft plastics.

16. Process of ally previous Claim. wherein the multilayer article has consistent properties without detrimenta' or un-controlled ocalised concentrations of any one rnateria type or contamination occurring.

17. Process of any previous Claim, wherein the multilayer arñcle includes otic or more layers comprising mixed plasflcs which arc unstable (e.g. immiscible) in a liquid phase in the absence of shear.

18. Process of any previous Claim, including a blending step of blending different materials which occurs prior to truterials entering an extrusion unit.

19. Process of any previous Claim, including a blending step of blending different materials within at least one extrusion unit.

20. Process of any previous Claim, in which for an input stream comprising mixed plastic types or containing contamination or other additives, the input stream is homogenised pnor to a pre-extrusion blending step or prior to an extrusion step.

21. Process of any previous Claim, including a blending step in which an even dispersal throughout an input stream of all its various constituent elements is performed such that]ocalised concentrations of any one material within the extrusion units are avoided.

22. Process of any previous Claim, such that a family of polymers is dominant within a molten polymer such that it creates a matrix in \vhich non-dominant particles and / or contaminants can reside.

23. Process of any previous Claim, in which high shear in an extrusion unit containing non-dominant polymer chains is such that the non-dominant polymer chains arc broken down into shorter chains allowing better dispersion within a dominant polymer matrix.

24. Process of any previous Claim, including a step in an extrusion unit containing polymers. of melting the polymers and mixing the polymers aggressively to break polymer chains, which allows new polymer bonds to form subsequently.

25. Process of any previous Claim, including a step of using compatihilisers.

26. Process of any previous Claim, in which homogenisation and blending of input materials occurs within one or more extruders.

27. Process of any previous Claim, in which materials in the extrusion units are at temperatures in the range 100°C to 300°C.

28. Process of Claim 27, in which materials in the extrusion units are at temperatures in the range 120°C to 260°C.

29. Process of any previous Claim, in which materials in the extrusion units experience pressures in the range of 0.2 MPa to 70 MPa.

30. Process of Claim 29, in which materials in the extrusion units experience pressures in the range of 10 MPa te 50 MPa.

31. Process of any previous Claim, in which materials in an extrusion unit experience shear in the range of 0.01 MPa to 10 MPa.

32. Process of Claim 31, in which materials in an extrusion unit experience shear in the range of 0.1 MPa to 5 MPa.

33. Process of any previous Claim, in which an extrusion unit includes twin-screw exuders, a single screw extruder, a planery extruder or more than two screws in a screw extruder.

34. Process of any previous Claim, including a degassing step to remove volaaile gases from molten materials.

33. Process of any previous Claim, including a step of forming a third layer on the first layer or on the second layer, by discharging third layer material from a fourth extrusion unit in a fourth discharge.

36. Process of Claim 35, including a step of forming a fourth layer on the opposite face to the third layer, by discharging fourth layer material from a fifth extrusion unit in a fifth discharge.

37. Process of Claim 36, wherein the fourth extrusion unit and the fifth extrusion unit are the same extrusion unit.

38. Process of any of Claims 35 to 37, wherein multiple. furthe.r layers are discharged or placed onto previously discharged layers, from extrusion units, or from elsewhere.

39. Process of any previous Claim, in which shear, heat and pressure are applied to materials in the extrusion units.

4(1. Process of any previous Claim, including a step of including One or more reinforcing elements in the nm]tilayer article.

0 41. Process of Claim 41, in which a reinforcing element is a continuous fibre material, such as a fibre mat or mesh, and such mats or meshes are made out of woven or uni-directional fibre materials, made from one or more of glass, aramid. nylon or other polymer types. hemp, carbon, metal, or organic materials.

42. Process of any of Claims 40 or 41, in which reinforcing elements are sheets, plates, rods, bars or wires.

43. Process of any of Claims 40 to 42, including the step of short reinforcing elements being fed into a paste within an extrusion unit such that the short reinforcing elements are blended into the paste at the extrusion stage.

44. Process of any of Clainas 40 to 4?, in which short reinforcing elements are one or more of short fibres naade from glass. araniid. nylon or other polymer types, henap, carbon, metal, or organic materials.

45. Process of any of Claims 40 to 44. in which a paste in an extrusion unit includes a material (eg. maleic acid or maleic anhydride) to enhance a bond between the reinforcing elements and plastics.

46. Process of any previous Claim, including use of a die system which integrates all inputs as article layering within the die system and fonns the finished article.

47. Process of Claim 42, including one or more high pressure devices to feed materials into the die system.

48. Process of Claims 46 or 47, in which reinforcing elements are fed into an article being formed at the die system.

49. Process of any of Cairns 46 to 48, in which output from the die system is drawn away and coefled down to form a product in a continuous process.

50. Process of Claim 49, in which steel hands on rollers arc used to draw away output from the die system.

Si. Process of any previous Claim, in which feedback from sensors is used by a computer to ensure a stabilization of parameters of a manufactured article.

52. Process of any previous Claim, in which the process is a continuous process.

53. Process of any previous Claim, in which the process uses input granules including granules in the range of 5 mm to 35 mm in characteristic size.54. Process of any previous Claim, in which the process includes low melt flow polymers as input materials.53. Process of any previous Claim, in which the article is a plank, a hoard, barge covering or container flooring.36. Process of any previous Claim, in which the process is one in which the article is between 1/2 feet (13.24 cm) and 15 feet (437.2 cm) wide.37. Process of any previous Claim, in which the process is one in which the article is between 4 mm and 80 mm thick.38. Process of Claim 57, in which the process is one in which the article is between mm and 30 mm thick.59. Manufacturing apparatus for manufacturing a rnultilaye.r article, the apparatus including a first extrusion unit, a second extrusion unit, a third extrusion unit, and a cutter, the first extrusion unit, the second extrusion unit, and the third extrusion unit arranged such that: (i) core material is dischargeable from the first extrusion unit in a first discharge, to form an article core portion; (ii) first layer material is dischargeable from the second extrusion unit in a seconid discharge, to form a hrst layer on a first face of the article core portion; (iii) second layer material is dischargeable frotn the third extrusion unit in a third discharge, to form a second layer on a second face of the article core portion, and the cutter is arrimged to cut to form a multilayer article.60. Manufacturing apparatus of Claim 59, in which the second extrusion unit is the same extrusion unit as the third extrusion unit.61. Manufacturing apparatus of Claims 59 or 60, arranged to perform a process of any of Claims 1 to 58.62. Computer program product for running on a computer, wherein the computer program product when running on a computer is operable to control a process of any of Claims 1 to 58.63. Crack resistant multilayer article comprising a foanied core, a first layer on a first face of the article core, and a second layer on a second face of the article core, wherein the article includes recycled plastics, wherein the article has a tiexural modulus in a range of 1500 \fPa to 4000 \[Pa, and wherein the article is, For example, a plank or a hoard, or barge covering or container flooring.64. Crack resistant Inulfilayer article of Claim 63, the article including a further layer or a further plurality of layers.65. Multilayer article manufactured using a process of any of Claims 1 to 58.Amendments to the Claims have been filed as follows:-CLAIMS1. A process for manufacturing a multilaye.r article comprising recycled plastics, including the steps of: (i) discharging core material from a first extrusion unit in a first discharge, to form an arficle core portion; (ii) discharging first layer material from a second extrusion unit in a second discharge, to form a first layer on a first face of the arficle core portion; (iii) discharging second layer material from a third extrusion unit in a third discharge, to form a second layer on a second face of the article core portion, and (iv) cutting to form a multilayer article comprising recycled plastics, wherein the process includes a step of subjecting material including a foaming agent in the first extrusion unit to a foaming step including an application of heat prior to discharging core 13 material from the first extrusion unit.2. Process of Claim 1, wherein the second extrusion unit and the third extrusion unit are the same extrusion unit.3. Process of any previous Claim, including a step of providing heat-activated expandable foam plastic material as input material to the first extrusion unit for the core material.23 4. Process of Claim 3, wherein the heat-activated expandable foani plastic material includes a fiaming agent.3. Process of any previous Claim, wherein the process is a manufacturing process tolerant to the compositions of the first layer materials and the second layer materials and the core material.6. Process of any previous Claim, wherein the process includes a step of providing co-mingled or mixed recycled plastic input materials.7. Process of Claim 6, wherein the co-mingled or mixed recycled plastic input materials are co-mingled or mixed, contaminated recycled plastic input materials.8. Process of any previous Claim, wherein the recycled plastics comprise single polymer recycled materials.9. Process of any previous Claim, wherein the recycled plastics comprise multiple polymer recycled materials.10. Process of-any previous Claim, wherein the multilayer article comprises some non-polymer contanilnatlons.13 11. Process of any previous Claim, wherein the multilayer article includes nainerals.12. Process of any previous Claim, wherein a multilayer article core comprises relatively hard plastics nd a multilayer article first layer and second layer comprise relatively soft plastics.13. Process of any previous Claim, wherein the multilayer article has consistent properues without detrimentil or un-conu-olled localised concenu-ations of any one material type or contamination occurring.23 14. Process of any previous Claim, wherein the multilayer article includes one or more layers comprising mixed plastics which are unstable (e.g. imniiscible in a liquid phase in the absence of shear.13. Process of any previous Claim, including a blending step of blending different materials which occurs prior to materials entering an extrusion unit.16. Process of any previous Claim, including a blending step of blending different materials within at least one exftusion utut.17. Process of any previous Claim, in which for an input stream comprising mixed plastic types or containing contamination or other additives, the input stream is homogenised prior to a pre.-extrusion blending step or prior to an extrusion step.3 18. Process of any previous Claim, including a blending step in which an even dispersal throughout an input stream of all its various constituent elements is performed such that localised concentrations of any one material \vithin the extrusion units are avoided.19. Process of any previous Claim, such that a family of polymers is dominant within a molten polymer such that it creates'a matrix in which non-dominant particles and / or contaminants can reside.20. Process of any previous Claina. in which high shear in an extrusion unit 13 containing non-dominant polymer chains is such that the non-dominant polymer chains are broken down into shorter chains allowing better dispersion within a dominant polymer matrix.21. Process of any previous Claim, including a step in an extrusion unit containing polymers. of melting the polymers and mixing the polymers aggressively to break polymer chains, which allows new polymer bonds to form subsequently.22. Process of any previous Claim, including a step of using compaflbilisers.23 23. Process of any previous Claim, in which homogenisation and blending of input materials occurs within one or more extruders.24. Process of any previous Claim, in which materials in the extrusion units are at temperatures in the range 100°C to 300°C.23. Process of Claim 24, in which materials in the extrusion units are at temperatures in the range 120°C to 260°C.26. Process of any previous Claim, in which materials in the extrusion units experience pressures in the range of 0.2 \fPa to 70 MPa.27. Process of Claim 26, in which materials in the. extrusion units experience.3 pressures in the range of 10 MPa to 30 MPa.28. Process of any previous Claim, in which materials in an extrusion unit experience shear in the range of 0.01 MPa to 10 MPa.29. Process of Claim 28, in which materials in an extrusion unit experience shear in the range of 0.! MPa to 5 MPa.30. Process of any previous Claim, in which an extrusion unit includes iwin-screw extruders, a single screw extruder, a planetary extruder or more than Iwo screws in a 13 screw extmder.31. Process of any previous Claim, including a degassing step to remove volatile gases frona nx)lten materials.32. Process of any previous Claim, including a step of forming a third layer on the first layer or on the second layer, by discharging third layer material from a fourth extrusion unit in a fourth discharge.33. Process of Claim 32, including a step of forming a fourth layer on the opposite face to the third layer, by discharging fburth layer material from a fifth extrusion unit in a fifth discharge.34. Process of Claim 33, wherein the fourth extrusion unit and the Fifth extrusion unit are the same extrusion unit.33. Process of any of Claims 32 to 34, wherein multiple Harther layers are discharged or placed onto previously discharged layers, from extrusion unr, or from elsewhere.36. Process of any previous Claim, in which shear, heat and pressure are applied to materials in the extrusion units.37. Process of any previous Claim, including a step of including one or more.3 reinforcing elements in the multilayer article.38. Process of Claim 37. in which a reinforcing element is a continuous fibre material, such as a fibre mat or mesh, and such mats or meshes are made out of woven or uni-directional fibre materials, made from one or more of glass,a.raiid, nylon or other polymer types, hemp, carbon, metal, or organic materials.39. Process of any of Claims 37 or 38, in which reinforcing elements are. sheets, plates, rods, bars or wires.13 40. Process of any of Claims 37 to 39, including the step of short reinforcing elements being fed into a paste within an extrusion unit such that the short reinforcing elements are blended into the paste at the extrusion stage.41. Process of any of Claims 37 to 40, in which short reinforcing elements are one or more of short Fibres made from glass, aramid, nylon or other polymer types, hemp, carbon, metal, or organic materials.42. Process of any of Claims 37 to 41, in which a paste in an exfiusion unit includes a material (eg. maleic acid or maleic anhydride to enhance a bond beiween the reinforcing 23 elements and plastics.43. Process of any previous Claim, including use of a die system which integrates all inputs as article layering within the die system and forms the finished article.44. Process of Claim 39, including one or more high pressure devices to feed materials into the die system.43. Process of Claims 43 or 44, in which reinforcing elements are fed into an article being formed at the die system.46. Process of any of Claims 43 to 45, in which output from the die system is drawn away and cooled down to form a product in a continuous process.3 47. Process of Claim 46. in which steel bands on rollers are used to draw away output from the die system.48. Process of any previous Claim, in which feedback from sensors is used by a computer to ensure a stabilization of parameters of a manufactured article.49. Process of any previous Claim, in which the process is a continuous process.50. Process of any previous Claim, in which the process uses input granules including granules in the range of 5 mm to 35 mm in characteristic size.31. Process of any previous Claim, in which the process includes low melt flow polymers as input materials.52. Process of any previous Claim, in which the article is a plank, a hoard, barge covering or container flooring.53. Process of any previous Claim, in which the process is one in which the article is between 1/2 feet (15.24 cm) and 15 feet (457.2 cm) wide.54. Process of any previous Claim, in which the process is one in which the article is between 4 mm and 80 mm thick.53. Process of Claim 54, in which the process is one in which the article is between mm and 30 mm thick.56. Manufacturing apparatus for manufacturing a recycled plastic multilayer article, the apparatus including a first extrusion unit, a second extrusion unit, a third exftusion unit, and a cutter, the first exftusion unit, the second exUusion unit, and the third exfiusion unit arranged such that: (i) heat can be applied to material in the first extrusion utut, suitable to activate a foaming agent in the rnatcnal to induce foaming, and core material is dischargeable from the first extrusion unit in a first discharge. to form an article core portion; (ii) first layer material is dischargeable from the second extrusion unit in a second S discharge, to form a first layer on a first face of the article core portion; (iii) second layer material is dischargeable from the third extrusion unit in a third discharge, to form a second layer on a second face of the article core portion, and the cutter is arranged to cut to form a recycled plastic multilayer article.57. Manufacturing apparatus of Claim 56, in which the second extrusion unit is the same extrusion unit as the third extrusion unit.58. Manufacturing apparatus of Claims 56 or 57. arranged to perform a process of any of CLums 1 to 55.59. Computer program product for mnning on a computer, wherein the computer program product when running on a computer is operable to control a process of any of Claims I to 55.60. Crack resistant multilayer article comprising a foamed core, a First layer on a First face of the article core, and a second layer on a second face of the article core, wherein the article includes recycled plastics, wherein the article has a flexural modulus in a range of 1500 MPa to 4000 MPa, and wherein the article is, for example, a pLank or a board, or barge covering or container flooring.61. Crack resistant multilayer article of Claim 60, the article including a further layer or a further plurality of layers.62. Multilayer article manufactured using a process of any of Claims I to 53.