NL2013695C2 - Fibre reinforced composite materials. - Google Patents

Description

Fibre Reinforced Composite Materials

The present invention relates to fibre reinforced composite materials prepared from fibrous shredder residue materials obtained from recycling streams, and their use for the preparation of composite materials. The present invention further relates to a method for the preparation of the composites and shaped articles therefrom, and to its various uses.

Background of the Invention

Many furniture and building materials, for instance those used for kitchen or bathroom materials, require a high durability, and resistance to humidity and exposure to chemicals (micro)biological growth.

Composite materials fare typically based on wood chips or paper residue, and typically are processed using binder materials such as melamines or phenolic resins.

Examples for the use of paper or wood residues are US-A-6,044,604, which for instance discloses a composite roofing board having a paper layer made of recycled paper fibres.

Typically, thermosetting binders are used in such materials, requiring a suitable curing process, resulting in a rather narrow production window both in time due to the reactivity of the binder system, and also typically limiting the maximum thickness of the composite materials if heat is to be applied for curing.

Furthermore, these materials only show a low mechanical strength, and need large amounts of resin or binder addition to achieve suitable physical properties and chemical resistance.

In view of the foregoing, it should be apparent that there exists a need for a low-cost and highly stable composite building material that can be formed into building structural panels using a relatively simple and inexpensive manufacturing process, such that the panels have adequate dimensional stability, durability and flexibility.

Applicants have now surprisingly found that composite materials can be prepared from a fibrous shredder residue comprising thermoplastic waste and fibres, essentially without addition of separate binder materials. It was found that the material was particularly resistant to humidity. Furthermore, the materials can advantageously be sourced from recycling materials that otherwise has little other uses than fuel or landscape filling purposes.

Accordingly, the present invention relates to a process for the preparation of a fibre reinforced composite material from a fibrous shredder residue comprising at least one thermoplastic polymer and having a density of from 150 to 650 kg/m3, comprising the steps of: (a) subjecting the fibrous shredder material to shear rate sufficient and for a time sufficient to reduce the average particle size to at least half of the original average particle size, and (b) compacting the material through a die, to form a fibre reinforced composite material.

The present invention further provides a composite material obtainable by the process that comprises primarily a fibrous shredder residue, essentially without addition, of additional binder material. More particularly, the composite material preferably comprises recycled fibrous material, optionally with additives and fillers.

It is still another object of the present invention to provide a composite material that may include various amounts of other natural or synthetic recycled or virgin substances in proportions that will contribute to the structural integrity or other features of the material, such as preferably recycled ground hard polyurethane foam particles that will increase mechanical strength as well as improve the insulation properties; fibrous or otherwise sheet materials, barrier layers and other enforcements or claddings. The composite materials were found to inherently have a high resistance to water and/or deterioration.

The fibrous shredder residue preferably comprises at least 5% by weight of thermoplastic polymeric material. Typical particulate thermoplastic materials according to the present invention comprise at least two polymeric materials chosen among functionalized polyethylenes, functionalized polypropylenes, ethylene acid copolymers, ionomers, functionalized ethylene vinyl acetate (EVA) copolymers, functionalized ethylene alkyl (meth)acrylate copolymers, polyethylene terephthalate (PET), poly-ethylene-furanoate (PEF); engineering polymers such as nylon and related polycondensation polymers; polyvinyl chloride (PVC) , ABS, elastomers and mixtures thereof; and copolymers of any kind employed in these materials; as well as bituminous materials used e.g. as sound proofing materials.

Preferably, the thermoplastic material comprises one or more polyolefins, such as polypropylene, further preferably comprising one or more functionalized polyolefins, preferably ethylene copolymers and/or ionomers for improved adhesion. The thermoplastic binder polymer preferably has a melt flow index less than 500 g/10 min according to ASTM Method No. D1238 at 190°C and a load of 2160 g.

More preferably, the thermoplastic materials comprise those disclosed in US-A-6191228, including at least two of HDPE, PET, PEF, polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), EPDM; ABS; TPE; TPU; PC/ABS; PMMA and/or mixtures thereof.

The materials to be employed in the present process include those obtained from recycling automobiles, generally vehicles, but may also include materials obtained from recycling and shredding white goods, furniture, electronics waste, or any waste that may suitably comprise fractions comprising thermoplastic polymers, and fibre fractions. In this respect, the term “car body” may also be understood as referring to white goods, furniture, electronics waste.

The fibrous shredder residue is preferably at least in part obtained comprising the steps of i) removal of the accumulator, all removable liquids, and tyres and wheels, engine drive train, glass and drivetrain; ii) shredding of the remaining car body to obtain shredded particles; iii) removing at least part of the ferrous and/or non-ferrous metals from the shredded particles; iii) separating shredded particles into at least four fractions comprising a mineral fraction; the fibrous shredder residue; a plastic fraction; and a metal fraction.

Preferably, suitable fibrous shredder residue materials according to the invention are at least in part the light fractions SLF (Shredder-Leichtfraktion); Rohflusen and/or Leichtflusen LF1, LF2, and /or LF1-LG disclosed in WO-A-2009/124651, and/or Shredderflusen as disclosed in DE-A-19755629. These materials are fibrous fractions obtained from recycling automobiles after removal of metals and most thermoplastics.

This process may comprise the following steps, not all of which need to be performed at the same location,: I) A first step in the recovery cycle is removal of all suitable parts that may be refurbished or recycled selectively, such as e.g. the accumulator, tyres; catalytic converters and panes of glass where applicable, and optionally, thermoplastic and/or thermoset polymeric parts; II) a step for the removal of the automotive operating fluids, such as fuel; engine, gear, power steering and shock absorber oil; air conditioning refrigerants as well as brake and coolant fluids; III) crushing the remaining bodywork and subjecting it to a grinding operation, preferably in a so-called shredder. This suitably grinds the remaining bodywork into pieces of just a few centimetres in size. At this stage, in a further step ferrous and non-ferrous metal parts are removed, as for instance disclosed in WO-A-2005/050823. In these first steps I to III, up to 80 % wt. of the scrap vehicle has been removed for recycling purposes, to obtain a fraction further referred to as shredder residue, which represents 20 %wt of the recycled car.

This shredder residue is then subjected to a so-called the "VW-SiCon Process", wherein several fractions are gained from the shredder residue, also referred to as the so-called “PST process” applied at the Auto Recycling Nederland (ARN) facility in the Netherlands.

The process thus further comprises subjecting the shredder residue is subjected to at least one further grinding step (IV), and to at least one separation step (V). The latter may advantageously be performed using one or more cyclones that separate material according to density, as for instance disclosed in US-A-6,460,788. Similar processes are also disclosed in EP-A-0918606 A US-A-6,460.788 ; WO-A-2004/004997; DE-A-10053487, DE-A-10053488, DE-A-10053491; DE-A-1005349; EP-A-0912310; WO-A-03/090941, WO-A-2004/041452; EP-A-1090727 and BE-A-1,014797. These and the above processes result in one or more fibrous fractions, all of which may be suitable as starting material according to the subject process.

Preferably, the density of the fibrous shredder residue is of from 200 to 450 kg/m3. The density of the fibrous material is measured prior to incorporation into the composite. Preferably, the fibrous material comprises recycled car interior material.

Most preferably, the fibrous material is produced at least in part in a process comprising the steps of (i) shredding a car body, and (ii) removing ferrous and/or non-ferrous metal, and (iii) separating the fibrous material from a heavier, thermoplastic fraction, and a lighter particulate fraction. Step (i) may be executed in any suitable manner.

In step (ii), at least a part, and preferably the majority of the ferrous and/or non-ferrous metal particles are removed. This may conveniently be done by magnetic separation for metals that respond to a magnetic field, and/or through e.g. density based separation methods, such as floating and/or centrifugation, or sifting and screening.

Applicants found that smaller ferrous or non-ferrous metal pieces that may have not been removed from the thermoplastic or the fibrous fraction, such as e.g. copper wires, are advantageous in heat dissipation throughout the composite material, while larger pieces may disturb the blending process due the difficulty to transport them in the blending device, and due to the fact that they may cause defects in the composite upon shaping. Accordingly such remnants are preferably removed prior to step (a) of the subject process.

Preferably, the fibrous shredder residue material has a carbon content of above 45% wt., and a hydrogen content of above 5 %wt.

The fibrous shredder residue may also comprise other materials that are subjected to this process; provided that there a sufficient fibres and thermoplastic residue present to allow performing the subject process.

Step (a) may be performed by any suitable method, including mechanical methods, and/or advantageously the use of cyclone technology, which may equally allow to pre-heat the fibrous material, as may be required for a continuous production. In such a line-up, the material, together with any additive or other material as required may be advantageously be blended and premixed from a silo, and then intensively while already pre-heating to allow for an improved flow if a homogenous composite is desired.

The above-discussed processing steps are well known in the plastics and composites field. Applicants however found that this may also suitably be applied to fibrous shredder material. Suitable techniques and machinery may be employed, or readily adapted, for the purposes of the present invention. The operating parameters, in particular the temperature, pressure and processing time, will depend in any given case upon the nature of the starting material and the desired characteristics of the end product; however, determination of such parameters should be well within the grasp of the skilled person.

Alternatively, the process may be performed batch-wise. The benefit of such a batch production is the relative ease of heating and shaping, but equally also the fact that a less homogenous material may be obtained, which can be advantageous if porous matrix materials are present as well, whereby a full saturation of cavities in the matrix may be avoided, thereby maintaining high insulation values and low density.

Step (a) is preferably executed in a high shear mixing apparatus, such as an extruder or geared pump. More preferably, the blending is done by extrusion, yet more preferably in an extruder line-up comprising more than one blending element.

In a particularly preferred embodiment, step (a) is performed in a high shear blending device; and may further comprise heating and cooling the mixture to different temperatures. Preferably, the temperature in step (a) is in the range of from 90°C to 300°C, more preferably of from 100 to 240, yet more preferably of from 110 to 190 °C.

In step (a), the fibrous shredder residue is preferably subjected to a shear rate in the range of from 100 to 550 s"1 , and at a temperature of at least the glass transition temperature (Tg) of the at least one thermoplastic polymer exhibiting the lowest Tg.

Advantageously, step (a) involves heating the fibrous shredder residue to different temperature zones, e.g. to allow material to cool down after blending to avoid gassing out due to phase transition, retropolymerisation or oxidation reactions. The apparatus for step (a) preferably can be heated and cooled to allow heating the material during blending to a specified temperature, or to several temperatures if the blending is performed in various different blending zones.

The apparatus in step (a) device should preferably agitate the thermoplastic melt to promote good mixing and to eliminate dead regions or stagnation during the process, to avoid hot spots and issue associated therewith, such as depolymerisation, oxidation and/or gassing out, and related issues with e.g. the smell of the obtained materials,

Suitable extruders include single, twin screw extruders, and extruders with higher number of screws or otherwise suitable means including gears, balls, spindles or rollers in addition to a centrally rotating drive shaft or screw, to provide shear. Preferably, the extruder is an intermeshing, co-rotating extruder. The one or more elements or screws may preferably comprise one or more of suitable types of conveying, blending, kneading and mixing elements, all being able to convey the material either forward, or forward and backward, for enhanced blending.

The mixing elements in the device may include gears, balls, spindles or rollers in addition to a centrally rotating core in order to improve mixing conditions, providing for intensive mixing with reduced shear and stagnation.

Preferably the devices may also allow introducing a protecting gas atmosphere, e.g. nitrogen or argon to avoid oxidation, and hence comprises means to add these agents, and/or to remove any gases formed during the process.

Further suitable devices may include a plasticizer screw for advancing molten plastic to an injection mold with a circulating row of balls behind the flights of the screw for agitating the melt to promote better mixing, as disclosed in US-A-3,944,192. A further device for blending is disclosed in US-A-3,530,534, wherein an extruder includes a screw having a thread structure interrupted with a recess which includes two rows or rings of spherical balls. Yet a further device is disclosed in US-A-4,416,543, including a toothed central spindle and toothed planetary spindles disposed symmetrically around the central spindle such that the planetary spindles rotate and orbit the central spindle. This system has the benefit of allowing simultaneous blending, and heating and cooling to desired temperature profiles. A further suitable apparatus is disclosed in US-A-3,443,798, wherein a the processing device includes a rotor centrally mounted in a cylindrical shell and a plurality of sets of axially staggered orbital rollers located in the annulus between the rotor and the inner wall of the shell. The document also suggests the use of gear teeth on a rotor, shell and staggered orbital rollers.

Further suitable devices include gears, balls, spindles or rollers in addition to a centrally rotating core that provide for intensive mixing with low stagnation, as well as the capability of heating to a desired temperature while avoiding hot spots.

In an alternative embodiment, step (a) may be done by a dynamic mixing system located downstream of a screen changer and gear pump so as to deliver thoroughly mixed and cooled extrudate to the extrusion die from which it is emitted in the form of a shaped blended material, which may advantageously be shaped to a composite article of desired form.

Different extrusion devices were found particularly suitable for use in the present invention. These may comprise a single or multiple extruders, preferably with various access points at which controlled amounts of thermoplastic, fibres, additional agents and/or additives may advantageously be added to the molten thermoplastic mass being produced by the extrusion system upstream of the extruding die. In a preferred line-up, step (a) is executed in a series of extruders, allowing a high shear to be applied to the first stage, wherein the materials are blended and heated to the desired first temperature range, and then on to the second stage, where due to the intimate blending that had already occurred, a lower shear rate can be applied. A particularly effective combination was found in the use of either a planetary extruder or a single screw extruder, and then moulding of the obtained materials at a temperature at or below the Tg of the major thermoplastic component.

Additionally to the fibrous shredder residue, one or more additional virgin or recycled thermosetting or thermoplastic binders may be employed, depending on the desired strength and density of the composite materials; however good material properties could be achieved without such addition.

After step (b), the heat supply may be removed, and the material formed may be cooled.

The composites may be formed by either a batch process or a continuous process. In a batch process, the components in the form are suitably blended together dry in the desired weight percentages.

The composite material further preferably may comprise a porous polymeric matrix layer, for increased thermal insulation. Preferably, when shaped into panels, the edges of the composite panel comprise a higher amount of the composite material to increase mechanic strength. The shaping process may advantageously be performed in a heated and/or cooled belt press.

Preferably, the process further comprises adding one or more woven or non-woven sheet material to at least one side of the composite blend prior to or during step (c).

This may be for simply decorative purposes, as well as UV filtration by using a pigmented or printed foil, or functional such as the use of glass or carbon fibre mats for increased strength.

The composite material preferably further comprises at least one woven or non-woven sheet layer, to improve the mechanical properties such as tensile strength and surface resilience. The composite material may further comprise a cover sheet material to create an exterior expression, such as coloured films, preferably also comprising a UV filter, printed films, printed paper or carton box, woven or non-woven fabrics.

Preferably, the temperature in steps (a) , (b) and onwards refers to a temperature in the range of from 90 to 350°C, preferably 100 to 240°C, yet more preferably 110 to 190°C.

The obtained composite materials have a density of typically in between 450 and 1600 kg/m3, preferably of from 1150 to 1500 kg/m3, and yet more preferably of from 1300 to 1400 kg/m3, such as 1350 kg/m3. The composite material may further comprise further components, such as glass fibres, e.g. of 3 to 5 cm length. The composite material may also comprise additives, such as pigments, fillers, flow improvers, catalysts, wetting agents and other usually applied additives. These are suitably added in or before step (a).

The shaped articles may further be subjected to a compression moulding step.

The pressure in this step may be any pressure that is suitably applied, and may range from ambient pressure or slightly above that, such as the pressure exerted by a vacuum bag, to a pressure of several tons per square meter, as suitably applied by e.g. a hydraulic press in the mould. Preferably the pressure ranges of from 0.1 MPa to 10 MPa, preferably from 1 to 7 MPa, again more preferably from 2 to 6.5 MPa, calculated as unit pressure applied to the composite material in a mould. The area is calculated from the projected area taken at right angles to the direction of applied force and includes all areas under pressure during the complete closing of the mould. The unit pressure, expressed in kg per square centimetre, is calculated by dividing the total force applied by this projected area. This is particularly suitable as a high-volume, high-pressure method suitable for a semi-continuous or continuous mode of operation. The time required to achieve a suitable strength and appearance depends largely on the kind of particulate binder used, but may range from several seconds, e. g. at high pressure and temperature, to several hours. Preferably, the time wherein the increased temperature and pressure are applied ranges of from 1 s to 10 hours, more preferably from 5 s to 5 h, yet more preferably from 30 s to 3 h, again more preferably from 1 min to 1 h. Furthermore, the material may be pre-heated, and/or postcured or cooled down as required.

Preferably the process further may comprise adding at least one porous polymeric matrix layer, preferably a rigid urethane foam layer, and applying the blended material to at least one side of the foamed polymeric matrix layer, prior to step (c). This will result in less dense composites with high insulation values.

The present invention further relates to the use of the optionally shaped composite article as building or sheet material, as decorative and/or functional panelling, e.g. as noise suppression walls, furniture, or as a basis for flooring, e. g. as panels for laminate floors, or for furniture, e.g. kitchen table tops or strips as used in kitchen building.

The composite material preferably has a flame spread index of B-S3 or better according to EN 13501-1:2007.

The composite material was found to be resistant to attack by microbes and insects and thus does not require expensive chemical treatments. Also, the material is resistant to degradation from exposure to ultraviolet light as well as damp, freezing conditions.

The present invention further preferably relates to a shaped article comprising the composite material according to the invention, such as advantageously in the form of a flat, square-shaped panel module for use in assembling building structures. Such panels may also advantageously be employed as replacement for fibre enforced concrete panels in structural or other outdoor applications, such as sound proofing, as at the side of highly frequented roads, or as cladding for e.g. dykes.

The following examples are provided to exemplify the invention.

Example 1 A fibrous shredder residue obtained from Auto Recycling Nederland, was subjected to single screw extrusion at a temperature in the range of from 110 to 190°C. The fibrous material was obtained according to a process as disclosed in WO-A-2009/124651, specifically fraction LF1, i.e. the light fraction after removal of metals and thermoplastics.

The fibrous material had the following properties (table 1): Table 1: Compositional data of the fibrous material (AAS)

Table 1 (continued): Compositional data of the fibrous material (AAS)

Table 2: Physical measurements of the fibrous shredder residue

All ratios or measures herein, if not otherwise indicated, are by weight.

The obtained composite material was then shaped through a die into a continuous rectangular profile strip having dimensions of 40x25 mm. The thus prepared strips were found suitable for use in kitchen decorative surfaces, where they would be covered by a foil for various optical impressions.

Example 2: Preparation of pellets

Example 1 was repeated, however extruding the formed composite material through a die with several openings, and cutting the thus formed strands into pellets through a rotating knife. The thus obtained pellets were allowed to cool and then subjected to examination for particle size and fibre length. The average particle size of the original shredder residue, was found to be reduced by about 15 times; thereby rendering the the thus prepared pellets suitable for shaping at normal operations such as extrusion or compression moulding off site.

The examples above clearly illustrate the advantages of the process and materials of the present invention. Although several specific embodiments of the present invention have been described in the detailed description above, this description is not intended to limit the invention to the particular form or embodiments disclosed herein since they are to be recognised as illustrative rather than restrictive, and it will be obvious to those skilled in the art that the invention is not limited to the examples.

Claims (17)

A method for the preparation of a fiber-reinforced composite material from a fibrous shredder residue comprising at least one thermoplastic polymer, and with a density of 150 to 650 kg / m, comprising the steps of: (a) subjecting the fibrous shredder residue to a shear rate with sufficient shear and for a time sufficient to reduce the average particle size to at least half the original average particle size, and (b) compacting the material through a mold to form a fiber-reinforced composite material; and wherein the average particle size is reduced at least 10 times. The method of claim 1, wherein step (a) comprises extrusion into one or more extruders. The method of claim 1, wherein the fibrous shredder residue is subjected to a shear rate in the range of 100 to 550 s and at a temperature of at least the glass transition temperature (Tg) of the at least one thermoplastic polymer that exhibits the lowest Tg. The method of claim 3, wherein the temperature in step (a) and / or (b) is in the range of 90 ° C to 300 ° C. The method of claim 1 or 2, wherein the weight average particle size is in the range of 5-45 mm prior to step (a). The method of any one of claims 1 to 5, wherein the average particle size is reduced at least 15 times. The method of any one of claims 1 to 6, wherein the density of the * fibrous shredder residue is in the range of 200 to 450 kg / m, and wherein it comprises at least 5% by weight of at least two thermoplastic polymers. The method of any one of claims 1 to 7, further comprising (c) forming the fiber-reinforced material obtained in (b) to obtain a shaped article. The method of claim 8, wherein the fiber-reinforced composite material is formed in step (b) to a profile, strip or plate-shaped material. Method according to claim 8 or 9, comprising reducing the material that passes through the mold into granulates, pellets or particles formed in any other way, and optionally comprising cooling the obtained granules, pellets or particles and further processing the reduced material separately. A method according to claim 8 or 9, comprising a further step of pressing the molded article to obtain a press-shaped article. The method of any one of claims 1 to 11, wherein the fibrous shredder residue is at least partially obtained by the steps of: i) removing the accumulator, all removable liquids, and tires and wheels, motor drive, glass and drive line; ii) shredding the remaining bodywork to obtain shredded particles; iii) removing at least a portion of the ferrous and / or non-ferrous metals from the shredded particles; iii) separating the shredded particles into at least four fractions comprising a mineral fraction; the fibrous shredder residue; a plastic fraction; and a metal fraction. A method according to any one of the preceding claims, wherein steps (a) and / or (b) comprise heating and cooling the mixture to different temperatures. The method of claim 8, 9 or 11, further comprising adding a woven or non-woven sheet material to at least one side of a shaped article to form a decorative and / or functional surface layer. Use of the molded composite article according to any one of the preceding claims as building material, structural or decorative sheet material, furniture material, waterproof covering and reinforcement material; concrete covering material and / or sound-damping material. A composite material comprising the processed fibrous shredder residue obtainable according to any of claims 1 to 14. A shaped article comprising the composite material according to claim 16.