FR2752187A1 - Production of wood and plastic composite profiles from waste material - Google Patents

Abstract

A device for producing composite products made of wood and plastic materials by mixing and extrusion comprises a mixer (1) having two vats and two screws, a filling screw (2), a force fed hopper (3), a twin screw extruder (4), a single screw extruder (6), a die (11), a take-up (13) and a cutting device (14). Also claimed is the process of mixing humid waste wood with waste plastic, transporting this with the filling screw, pressing and reducing the apparent density in filling the hopper, laminating the mixture in the twin screw extruder and evacuating the water formed, transporting, heating and removing volatiles in the single screw extruder, extruding through a die, stretching and cutting.

Description

DEVICE FOR PRODUCING COMPOSITE PRODUCTS
FOR THE PRODUCTION OF WOOD AND POLYMER PROFILES
AND THE PROFILES SO OBTAINED
The present invention relates to the field of mechanics and more particularly to the manufacture of profiles formed from wood and polymers.

More specifically, it relates to a shaping device comprising two extruders allowing the manufacture of composite products based on wood waste. These products find applications in the manufacture of pallet dice, carpentry moldings, window frames, and more generally of all products based on wood waste.

The two extruders according to the invention can also be used to prepare plastic wood pellets, from 2 mm to 10 mm in diameter. These granules, intended for injection, can be molded like a plastic material, hence the advantage of being able to produce all kinds of parts at a competitive price.

French patent (FAYE Richard) no. 2,679,482 already describes a process for manufacturing composite products based on a mixture of wood waste and recycled thermoplastics in which the components are intimately mixed. Wood waste is in firstly mixed and compacted with a binding agent formed from recycled polyolefins previously disaggregated and presented in the form of flakes which are heated before introduction to the fluidization temperature then the mixture is subjected to cooling which allows a diffusion and distribution of polyolefins throughout the volume defined by the product The composite products are subsequently shaped by compression or by extrusion.

French patent (Company GREPP) n "2,564,374, also describes a production process by extrusion of massive profiles with low humidity recovery and variable density based on a mixture of wood shavings and recycled thermoplastics, in which a degassing single screw extruder is supplied, provided at its end with a profile die, firstly in its entry area by the wood chips and then made of recycled plastic melted from an auxiliary external source at a point located before the degassing zone.

European patent (MASTER Srl) n "401.885, describes a process for the re-use of solid waste like wood, paper, natural or synthetic rubber ..., and / or thermoplastic resins, in which one begins to grind the material to reuse (wood, paper ...), then add to the ground material, polyethylene, or another suitable thermoplastic resin, in a percentage varying from 20 to 60%, to add additives such as stabilizers, coloring agents or lubricants ..., to mix everything, to melt the mixture in an extruder or by the means of another system, to then form the finished or semi-finished products by extrusion or, by molding, by compression ... These products finished are used for various uses (construction, agriculture ...).

These references highlight the need to use materials with a low moisture content.

The device according to the invention makes it possible to extrude wood and plastic materials in order to obtain a homogeneous mass.

The device, in addition allows to extrude wet wood containing up to 70% humidity, and therefore to be able to use wood waste of all kinds, still wet, coming directly from the sawmill and therefore unusable without drying for everything use.

The device according to the invention therefore aims to no longer use a wood dryer which results in a long and extremely expensive drying.

Waste plastics include polyvinyl chloride, polyethylene, polypropylene, vinyl acetate.

The device according to the invention consists of a mixing installation, of a filling screw ensuring the transport of the wood / polymer mixture until its introduction into a forced hopper at the end of which is an extruder with two screw ensuring the exit of the wringed composite before its introduction into another single screw extruder.

The forced hopper is therefore extended by a twin screw extruder ensuring the spinning and rolling of the wood, then a mono bis extruder recovering the wrung material. Degassing wells allow volatile products formed during the distillation of the wood to escape, a vacuum pump makes it possible to extract the steam remaining in the wood, and a condenser makes it possible to transform the trapped steam into water.

There is also a die through which the hot material passes free of any vapor and volatile products, a cooling tank through which the composite material passes, a caterpillar used to pull the product, and finally, a cutter which ensures the section of the tube. , from a single screw extruder, in calibrated segments.

The invention also relates to a process for producing composite materials using the device according to the invention.

The process for preparing composite products and in particular profiles formed from wood and polymers consists in firstly mixing and metering the base materials, in particular wet wood waste such as chips and / or sawdust, with plastic waste, in that the wood / polymer mixture is transported using the filling screw, in that it is pressed and the apparent density of the waste mixture is reduced of wood and plastic material by the introduction of this mixture into a forced hopper, in that it is wrung and the wood is laminated by the introduction of the wood / polymer mixture in a twin screw extruder, in that the the water formed during the spinning of the wood is discharged using orifices located on the twin-screw extruder, in that the composite material thus wrung is introduced into a single-screw extruder, in that this material is heated in said extruder, in that transports this material into different compression and decompression zones of said extruder, in that the volatile products formed during the distillation of the wood are extracted using degassing wells, in that the composite material thus obtained.

Then, the process according to the invention consists in passing the material thus obtained through a die, in that the composite product thus cooled is cooled and that this product is stretched before cut it out.

Figure 1 illustrates an overview of the device according to a preferred embodiment.

The mixer (1) is made up of a tank of 900 mm in diameter for chips and sawdust, and of a tank of 500 mm in diameter for plastic material which is in the form of flakes.

To avoid the arch effect, two mixing arms are placed inside the two tanks so that the plastic and the sawdust are always in motion.

This same mixer is equipped with two spring screws, with a diameter of 60 mm, actuated by variable speed motors, for the volumetric dosing of sawdust and plastic. This dosage of sawdust and plastic material can make it possible to vary from 0 to 100% of sawdust, and from 0 to 100% of plastic material in the mixture.

The material thus dosed and mixed, is transported by the screw (2) with a diameter of 80 mm, introduced into the forced hopper (3) which, for its part, is equipped with a speed variator motor, a screw without end of a pitch ranging from 80 to 120 mm and in particular 100 mm, which allows pressing and reducing the apparent density of sawdust and plastic, in order to feed the twin screw extruder as much as possible (4) , if necessary by applying pressure.

The twin screw extruder (4) is 2 times 120 mm in diameter. It includes a screw with a variable pitch of 80 mm under the hopper, from 60 mm in the first zone to reach 100 mm in the last extrusion zone.

This extruder (4) allows the wringing and rolling of the wood. At the rear of the twin screw extruder, two half-moon-shaped orifices evacuate the water separated by the spinning of the wood. Indeed, the wood contains an amount of humidity which ranges from 40 to 70%.

The extruder (4) is driven by an 80 horsepower variator motor, the screws of this machine are cooled by a circulation of water. The sheath of this one is heated by 6 heating collars, with a power of 2000 Watts each, and cooled by collars with water circulation.

Such an assembly is necessary to control the temperature to the nearest degree, so that the water extracted from the wood by wringing is in no case transformed into steam in the first stage.

The material thus wrung, is maintained at a temperature of 80 degrees, and is pushed towards a filling orifice (not shown) with a diameter ranging from 80 to 120 mm and in particular of 100 mm, which is located on the single screw extruder (6). The latter, with a screw diameter of 150 mm and a power of 120 hp, takes up the material, reheating it to around 170 degrees in the first zone known as the cylinder head.

The material is transported by the screw in the zone n "1 called compression, which has the effect of compressing the material. The zone n" 2 known as decompression has a heating power of 2000 Watts, a temperature of 185 degrees, and , at this location a degassing well (7), of diameter 125, is connected to a vacuum pump (9) with liquid rings, with a power of 10 hp located 85 cm from the cylinder head which also allows extract the vapor remaining in the wood.

This captured vapor passes inside a condenser (10) which transforms the vapor into water.

This machine also includes a degassing well (5).

The same material then passes into zone n "3 called compression, with a heating power of 4000 Watts, at a temperature of 190 degrees to mix the material well. Then the material passes into zone n" 4 known as decompression, with a heating power of 6000 Watts, where a new degassing well (8) makes it possible to completely extract the remaining vapor which is released from the wood. The next zone called metrous zone n "5, with a heating power of 6000 Watts, a temperature of 210 degrees, aims to homogenize the material using pins and mixers located on the screw. 400 mm from the end of the extruder.

Thus the hot mixed material, free of any vapor, passes through a die (11) where all the profiles that one can imagine are achievable (round, square, triangular, flat, etc.).

This system is heated to 220 degrees, by two zones of 1000 Watts each.

The product thus obtained is cooled, guided in a cooling tank (12) with water spray, a length of 5 m. At the outlet of the cooling tank, a pulling device formed by a track (13), of a width ranging from 100 to 150 mm and in particular of 120 mm, and of a length ranging from 1200 to 2000 mm and in particular 1400 mm, is fitted with a drive motor with torque limiter.

This device is used to stretch the product regularly, and therefore, to calculate the cutting lengths recorded previously, which makes it possible to give the order to cut the cutter (14).

The two extruders as well as the forced hopper are controlled at speed, temperature and cooling levels by three programmable controllers.

 It is also possible to install molds on a barrel. This barrel is then placed in front of the die, for filling the mold. This operation finished, the triggering of the barrel is controlled by the pressure of the material in the die. Another mold is positioned opposite the die, etc.

Such a system has the advantage of using hot material directly at the extruder outlet and, while one mold is being filled, the other cools.

Claims (20)

1. A device for the production of composite products made of wood and  plastics by mixing and extruding the mass, characterized in  that it consists of a mixer (1) comprising two tanks and two screws, of a  filling screw (2), a forced hopper (3), a twin screw extruder (4),  a single screw extruder (6), a die (11), a track (13) and a  cutting device (14). 2. A device according to claim 1 in which the twin screw extruder (4) is  provided with two discharge orifices. 3. A device according to claim 1 or claim 2, wherein  the bis screw extruder (4) has a screw with a variable pitch of 80 mm under the  hopper, 60 mm in the first zone and 100 mm in the last zone  extrusion. 4. A device according to one of claims 1 to 3, in which the extruder bis  screw (4) is cooled by water circulation. 5. A device according to claim 1, in which the single screw extruder (6)  has a filling opening with a diameter ranging from 80 to 120 mm. 6. A device according to claims 1 and 5, in which the single screw extruder  (6) has degassing wells for volatile products. 7. A device according to claims 1, 5 and 6, in which the mono extruder  screw (6) has a liquid ring vacuum pump (9). 8. A device according to claims 1, 5, 6 and 7, in which the mono extruder  screw (6) includes a condensing device (10). 9. A device according to claim 1, in which the mixer (1) is formed  a tank for wood and a tank for plastic. 10. A device according to claim 1 or claim 9, wherein the  mixer (1) has two arms arranged inside the tanks and two screws  springs actuated by variable speed motors. 11. A device according to claim 1, in which the forced hopper (3)  includes a variable speed motor and a worm. 12. A device according to claim 11, in which the worm of the hopper  forcing force is 80 to 120 mm. 13. A device according to claim 1, in which the die (11) is extended  a cooling tank (12) with water spray. 14. A device according to claim 1, in which the track (13) is equipped  of a variable speed motor with torque limiter. 15. A device according to claim 1 and claim 14, in which the  track (13) is between 100 and 150 mm wide and has a length  between 1200 and 2000 mm. 16. A process for the preparation of composite products formed from wood and  plastics according to claim 1 characterized in that one mixes  and dose the wet wood waste with plastic waste, we  transports the wood / polymer mixture using a filling screw,  press and decrease the bulk density of the composite material mixture  by introducing it into a forced hopper, the wood is wrung and laminated by  the introduction of the wood / polymer mixture into a twin screw extruder, we  evacuates the water formed during the spinning of the wood, the material is introduced  wrung in a single screw extruder, this material is heated in said  extruder, we transport this material in different areas of the extruder,  the volatile products formed are extracted using degassing wells,  homogenizes the composite material, then we pass this material through a  die, said composite material is cooled, it is stretched and cut. 17. Use of the device according to one of claims 1 to 15, with a view to  the use of wood waste containing up to 70% humidity. 18. Use of the device according to one of claims 1 to 15, with a view to  the use of plastic waste. 19. Composite products based on wood waste and material waste  plastic, obtained according to the process of claim 16. 20. Composite products and in particular pallet dice, moldings  carpentry, window frames obtained by the process of  claim 16.