WO2009040462A1

WO2009040462A1 - Making a composite product

Info

Publication number: WO2009040462A1
Application number: PCT/FI2007/050527
Authority: WO
Inventors: Markku Vilkki
Original assignee: Conenor Oy
Priority date: 2007-09-28
Filing date: 2007-09-28
Publication date: 2009-04-02

Abstract

Making a composite product such that first, a fibre material and a plastic material are ground to a smaller piece size and/or to a fibre-like form. The ground materials are melt processed into a composite product containing both the fibre material and the plastic material. At least one of the materials of the composite product is precompacted to a higher specific weight prior to being fed to melt processing. While compacting the material, a substance improving its dimensional stability may be added thereto, if desired. Preferably, the composite product contains aluminium particles.

Description

MAKING ACOMPOsiTE PRODUCT

BACKGROUND OF THE INVENTION

[0001] The invention relates to a method of making a composite product, the method comprising grinding a fibre material and a plastic material to a smaller piece size and/or to a fibre-like form and processing the materials by melt processing into a composite product containing both the fibre material and the plastic material.

[0002] The invention further relates to an apparatus for making a composite product, the apparatus comprising a grinder for grinding a fibre ma- terial, a grinder for grinding a plastic material, and a melt processing device for melt processing the ground materials and for making a composite product containing both the fibre material and the plastic material.

[0003] The invention still further relates to a composite product containing a fibre material and a plastic. [0004] It is known to make a composite product from a fibre material and a plastic material by grinding and mixing the fibre material and the plastic material and by melt processing a product from a mixture thereof. The fibre material may be e.g. a natural fibre or a waste material. When making a composite product, it is quite difficult to obtain a sufficiently high output for a melt processing device, such as an extruder. Typically, to obtain a high output requires a large feed screw for feeding a fibre material to the extruder. Furthermore, dusty fibre materials may prevent sensors being used in an apparatus from operating properly. In addition, the dusty material tends to arch quite easily in a feed hopper. Such impairment of the operation of the sensors and arch- ing of the material both impede the operation of the apparatus considerably.

[0005] When making a composite product, steam being generated inside the mixture tends to produce blisters in the surface of the product and break up the surfaces of the product being made immediately after a nozzle. In order to prevent this problem, often a processing line has to be run at relatively low speeds so as to make the material to cool down sufficiently prior to exiting the nozzle. Further, a typical problem with a composite product is insufficient weather resistance and, in particular, insufficient ultraviolet radiation resistance.

[0006] A quite successful solution for improving the properties of a product is disclosed in document Fl 20055673. The document sets forth that a fibre material and at least one plastic material are extruded so as to produce a composite product. At least one plastic material of the product is crosslinked such that the crosslinking level of at least some surface of a wall of the product is higher than the crosslinking level of an inner part of the wall of the product. In such a case, the strength of the product increases and its thermal resistance improves.

BRIEF DESCRIPTION OF THE INVENTION

[0007] An object of the present invention is to provide a novel method and a novel apparatus for making a composite product, and a novel composite product.

[0008] A method according to the invention is characterized by pre- compacting at least one of the fibre material and the plastic material to a higher specific weight prior to melt processing.

[0009] Furthermore, an apparatus according to the invention is characterized in that the apparatus further comprises a precompacting device for compacting the plastic material and/or the fibre material prior to feeding the material to the melt processing device.

[0010] Still further, a composite product according to the invention is characterized in that the composite product further contains aluminium parti- cles.

[0011] In the solution disclosed in the present description, a fibre material and a plastic material are ground to a smaller piece size and/or a fibre-like form. The ground materials are melt processed into a composite product, which thus contains both the fibre material and the plastic material. At least one of the materials of the composite product is precompacted to a higher specific weight prior to being fed to melt processing. In such a case, a feeder feeding the material to melt processing does not have to be particularly massive and yet still the output of the apparatus is high. While compacting a material, it is also possible to make dusty components to bind to the product, which enables damage caused by dust to the sensors to be prevented. Furthermore, the compacted material does not easily arch in a feed device, so the process can be kept extremely well under control.

[0012] When compacting a material, a substance increasing the dimensional stability of the material may be added thereto, if desired, so that the compacted material retains its shape and dimensions extremely well. This fur- ther ensures that the material can be fed to melt processing in a reliable manner and that the output of the process thus remains good.

[0013] According to another solution disclosed in the present description, an aluminium-containing material is fed to the process so that at least one layer of a final product contains aluminium particles. Owing to their excellent heat transfer capacity, the aluminium particles even out temperature differences occurring in the mass in connection with processing both in melt processing, e.g. inside an extruder, and in the subsequent nozzle, wherein the product is calibrated by cooling. Further, the aluminium particles provide the exterior of plastic with a temperature-independent reinforcement which contributes to preventing the tendency of semi-molten plastic to raise blisters during cooling. Still further, the aluminium particles provide the outer surface of the product with a field of particles, i.e. a "protective screen", which reduces the effect of UV radiation. This solution enables the harmful effects of ultravio- let radiation on the entire product to be reduced considerably.

BRIEF DESCRIPTION OF THE FIGURES

[0014] The invention is described in closer detail in the accompanying figure showing a simplified block diagram of a process for making a composite product.

DETAILED DESCRIPTION OF THE INVENTION

[0015] In the process disclosed in the figure, first, a fibre material is ground. If the fibre material is e.g. waste wood, grinding is carried out in a wood crusher. If, again, the fibre material is paper, board, cardboard or liquid packaging cardboard or some other beverage or food packaging material, the fibre material is ground in a shredder. The fibre material may thus be e.g. wood, such as sawdust, chips or another by-product of mechanical wood processing industry. Furthermore, the fibre material may consist e.g. of flax, sisal, hemp, kenaf, jute, rice hull, straw, such as that of rice, maize, wheat or another cereal plant, or other similar natural fibre materials. Furthermore, the fibre ma- terial may further consist of plastic-coated paper, cardboard or the like, e.g. the material of liquid packages, other industrial packaging material and fibre waste generated in the production thereof.

[0016] After grinding, the ground fibre material is precompacted. In other words, the small-sized material is compacted to a higher specific weight. Prior to precompacting, the ground fibre material may have a specific weight of less than 150 kg/m³. Precompacting may take place e.g. in a pelletizing machine used e.g. in compacting of wood or other natural fibre material. After precompacting, the specific weight of the material is thus higher. Preferably, after precompacting the specific weight of the fibre material is more than 300 kg/m³.

[0017] Organic fibre waste or fibre having a low bulk density or a powdery additional material or another similar material which as such does not have to be ground may be added to the precompacting phase. In a pelletizing machine, for instance, such a powdery or dusty material can be made to attach to pellets produced among the rest of the fibre material by the pelletizing machine, in which case the material is thus bound to the pellets, no longer producing too much dust while being fed to melt processing and processed therein. Furthermore, the powdery additional materials may be such that they increase the hardness and dimensional stability of a pellet. This prevents the pellets, upon leaving the pelletizing machine, from being broken and damaged. It is a very challenging task to compact e.g. liquid packaging cardboard waste into a hard and dimensionally stable pellet. Further, the additional material may be e.g. an additional material improving the fire-retardant properties. Possible additional materials to be fed to a pelletizing machine include lignosulphate, calcium hydroxide, ammonium polyphosphate, lignin, mineral, such as chalk or talc, starch, wood or another natural fibre and dust derived therefrom, or glass fibre dust.

[0018] The process may also be fed with polyurethane waste which, typically, is quite difficult to utilize since a lightweight ground polyurethane in particular is difficult to feed e.g. to an extruder. Polyurethane is ground and fed to a pelletizing device wherein it is combined with a fibre material. Polyurethane is very light, so it contributes to decreasing the specific weight of the final product.

[0019] The plastic material to be fed to the process is also ground first. If the plastic material is rigid and compact, it will suffice that it is crushed into particles of an appropriate size. Lightweight plastic, such as a plastic film or strip, in turn, is preferably also compacted after grinding. The grinding and compacting of lightweight plastic may take place simultaneously e.g. in an agglomeration device. Naturally, plastic may also be ground and shredded prior to being fed to an agglomeration device. The agglomeration device shreds the plastic and heats it to a plasticization temperature. Next, the plastic is cooled down with water, which evaporates and is expelled. The device produces a granular agglomerate and thus compacts the plastic material fed thereto.

[0020] The plastic may be e.g. polyethylene PE, polypropylene PP, polyvinyl chloride PVC, acrylonitrile/butadiene/styrene ABS, polyvinyl acetate PVA, polystyrene PS, polyamide PA or polyethylene terephthalate PET or some other suitable thermoplast or a mixture of some thereof.

[0021] The fibre material and the plastic material processed in the above-described manner are then fed to melt processing. The melt processing may also be fed with more plastic and/or auxiliary substances to alleviate the melt process and/or to improve the properties of the final product. An auxiliary substance to be fed may be a plastic compatible with the plastic in the mixture of materials or a coupling agent, such as maleated anhydride acid compounds, to strengthen the bond between fibre and plastic. Furthermore, the auxiliary substance may be a plastic-crosslinking agent, such as silane or peroxide, or ultraviolet radiation or other weather resistance improving auxiliary substance, such as a HALS compound or a zinc borate compound. Furthermore, the auxiliary substance may be a lubricant, such as aminostearate or polyethylene wax, or the auxiliary substance may be a colourant or some other suitable auxiliary substance. [0022] In the figure, a designation "additional feed" is used for describing that the process may be fed e.g. with wood or other fibre pellets made outside the plant. In such a case, then, as far as the added material is concerned, the grinding and compacting of the fibre material has taken place in a plant different from that at which the melt processing is carried out. [0023] In the process, the melt processing may be e.g. extrusion or injection moulding or rotational moulding. Preferably, the melt processing is carried out by an extruder in which in extrusion the material being processed is further subjected to shearing and rubbing.

[0024] A melt processing line thus produces a composite product. The melt processing line may produce e.g. profiles, such as bars, columns, noise barrier elements, heat-insulated wall elements or other similar profile products. Another melt processing line may be set up for products of another type. The other melt processing line may be arranged to produce e.g. plate products, such as table tops, wall panels, moulds, doors, traffic signs or some other suitable plate-like products. More than two melt processing lines may also be provided. A product to be made may be a single-layer product or a multilayer product.

[0025] Preferably, a composite product is made substantially entirely of waste material. The waste material may be e.g. plastic and natural fi- bre waste produced e.g. in paper industry. Furthermore, the waste may be e.g. aluminium-containing liquid packaging cardboard or aluminium- and plastic- containing beverage or other food packaging material. Furthermore, the waste may contain natural cork. Also, vulcanized recycled rubber or, as reinforcement, organic fibre or inorganic fibre, such as glass or carbon fibre, may be added to the material constituting a composite product.

[0026] Preferably, a composite product is made from a material to provide the product with a large number of aluminium particles. Preferably, the aluminium content in the mixture is 10 to 90 percentage by weight. Aluminium is obtained e.g. from aluminium-containing packaging cardboard or paper or aluminium- and plastic-containing beverage packaging or another food packaging.

[0027] Until now, the aim has been to separate aluminium from a waste material. Surprisingly enough, however, tests have revealed that aluminium-containing waste can be utilized in a process, and aluminium has even been found out to have positive effects on the final result. Owing to their heat transfer capacity, aluminium particles even out temperature differences occurring in the mass in connection with processing both inside an extruder and a subsequent nozzle. Furthermore, the aluminium particles provide the exterior of a product with reinforcement which is independent of the molten tempera- ture of plastic, i.e. 100 to 200 ⁰C, and which contributes to preventing the tendency of semi-molten plastic to raise blisters during cooling. Still further, in the final product the aluminium particles provide the outer surface of the product with a field of particles, i.e. a 'protective screen¹, which reduces the effect of UV radiation. This enables the effects of ultraviolet radiation on the product to be reduced considerably.

[0028] Preferably, if the product to be made is a multilayer product, at least the outer layer is provided with aluminium particles. Further, preferably in a melt processing phase, a crosslinking agent is added to the material, i.e. if the plastic to be fed to the process contains e.g. polyethylene PE, the final product contains crosslinked polyethylene PEX. [0029] Particularly preferably, the process utilizes a waste material or a recycling material which contains two or more starting materials. The material to be fed to the process may be e.g. a composite material of natural fibre and plastic. Further, a composite material of aluminium and plastic, such as low density polyethene LDPE, coated with aluminium may be used. Further, a material containing a plastic, natural fibre and aluminium in combination may be used. Such a material may also contain barrier plastics, such as ethylene vinyl alcohol EVOH. Further, a material may also be used in which instead of aluminium, only a barrier plastic is used as a barrier. The material to be used in the process may thus contain both infusible materials and materials that melt in the process.

[0030] In some cases, the features disclosed in the present application may be used as such, irrespective of other features. On the other hand, the features disclosed in the present application may be combined, when necessary, to provide different combinations.

[0031] The drawing and the related description are only intended to illustrate the idea of the invention. The details of the invention may vary within the scope of the claims.

Claims

1. A method of making a composite product, the method comprising grinding a fibre material and a plastic material to a smaller piece size and/or to a fibre-like form and processing the materials by melt processing into a com- posite product containing both the fibre material and the plastic material, characterized by precompacting at least one of the fibre material and the plastic material to a higher specific weight prior to melt processing.

2. A method as claimed in claim ^characterized by the melt processing method being extrusion.

3. A method as claimed in claim 2, characterized by subjecting, in extrusion, the materials further to shearing and rubbing.

4. A method as claimed in any one of the preceding claims, c h a r- acterized by prior to compacting, the specific weight of the material to be compacted being less than 150 kg/m³, and after compacting more than 300 kg/m³.

5. A method as claimed in any one of the preceding claims, characterized by compacting the fibre material by a pelletizing machine.

6. A method as claimed in any one of the preceding claims, characterized by compacting the plastic material by an agglomeration device.

7. A method as claimed in any one of the preceding claims, char- acterized by adding, in connection with compacting, an auxiliary substance to the material so as to solidify the material and/or to improve properties of a final product.

8. A method as claimed in any one of the preceding claims, char- acterized by feeding the process with an aluminium-containing material and producing a product which contains aluminium particles.

9. A method as claimed in any one of the preceding claims, characterized by making the final product substantially entirely from a waste material or a recycling material.

10. A method as claimed in any one of the preceding claims, characterized by feeding the process with a waste material or a recycling material which contains two or more starting materials.

11. An apparatus for making a composite product, the apparatus comprising a grinder for grinding a fibre material, a grinder for grinding a plastic material, and a melt processing device for melt processing the ground materials and for making a composite product containing both the fibre material and the plastic material, characterized in that the apparatus further comprises a precompacting device for com- pacting the plastic material and/or the fibre material prior to feeding the material to the melt processing device.

12. An apparatus as claimed in claim 11, characterized in that the melt processing device is an extruder.

13. An apparatus as claimed in claim 12, characterized in that the extruder is further arranged to shear and rub the material being processed therein.

14. An apparatus as claimed in any one of claims 11 to 13, char- acterized in that the precompacting device is a pelletizing machine arranged to compact the fibre material.

15. An apparatus as claimed in any one of claims 11 to 14, characterized in that the precompacting device is an agglomeration device arranged to compact the plastic material.

16. A composite product containing a fibre material and a plastic, characterized in that the composite product further contains aluminium particles.

17. A composite product as claimed in claim 16, characterized in that the aluminium particles in the product are obtained from an aluminium-containing recycling material.

18. A composite product as claimed in claim 16 or 17, character i z e d in that the aluminium-containing recycling material is packaging cardboard or paper.

19. A composite product as claimed in claim 16 or 17, character i z e d in that the aluminium-containing recycling material is an aluminium- or plastic-containing beverage or other food package.

20. A composite product as claimed in any one of claims 16 to 19, characterized in that the product is made substantially entirely from a waste material or a recycling material.

21. A composite product as claimed in any one of claims 16 to 20, characterized in that the product contains a waste material or a recycling material consisting of two or more starting materials.