WO2014017892A1

WO2014017892A1 - Machine and process for producing boards from plastic waste

Info

Publication number: WO2014017892A1
Application number: PCT/MX2012/000073
Authority: WO
Inventors: Carlos RIVERA ULLOA
Original assignee: Rivera Ulloa Carlos
Priority date: 2012-07-27
Filing date: 2012-07-27
Publication date: 2014-01-30

Abstract

The invention relates to a machine and process for producing boards or plates from post-consumer plastic waste, which includes a series of interrelated devices for melting, in a melting chamber, a load of plastic waste contained in a mould; a pressing station for compressing the melted material in the mould; and a set of tracks that define a production circuit for the boards, along which the moulds travel from the start of the process until the end of same.

Description

MACHINE AND PROCESS FOR THE ELABORATION OF BOARDS FROM PLASTIC WASTE

Field of the Invention

The invention consists of a machinery and process for making boards, and more particularly a machinery and a process for manufacturing solid and resistant plates or boards from plastic waste, which can be used in weather, humidity, corrosive environments, and that are also characterized because they have a long service life. Background of the Invention.

There are currently a significant number of proposals in this technological field for the use of plastic waste, recycling them in other useful products, which are intended as an option to avoid excessive use of wood due to the consequences of over-exploitation of our forests.

For all the above, the machinery and process of the present invention adds to the above alternatives with notable advantages that surpass those that are known because they result in a simple and versatile process since it allows using any thermoplastic to convert it into a plate or board . For example, a wide variety of thermoplastics such as high density polyethylene (HDPE), low density polyethylene (LDPE), ultra high molecular weight polyethylene (HW PE), polypropylene (PP), acrylonitrile butadiene styrene ( ABS), ethylene vinyl acetate (EVA), polystyrene (PS), polyethylene terephthalate (PET), among others, which makes the process highly ecological because it recycles all those thermoplastics that normally constitute a serious contamination problem due to the difficulty involved the disposition of those materials.

The resulting plastic board aims to replace wood or other materials, without losing the properties or advantages of products manufactured with these raw materials, so it must be feasible to machine said plastic board, as if it were a wooden product , that is, saw cutting, recesses with router or profiler, holes and nailing. To obtain these characteristics it is important to use olefins, such as polyethylenes and polypropylenes, in a proportion of the order of 75 to 80% by weight of the total composition that It is going to melt. Likewise, it is recommended that when PET is part of the raw material, it does not exceed 15% of the composition.

The new process is static, that is, there is no mixing or homogenization of the plastic; It melts as it is placed in the mold. This feature allows the use of post-consumer raw materials ("plastic waste") even with non-plastic waste, such as soil, paper labels, metal staples, glass, wood chips, etc. Therefore, it is feasible to process plastic waste without the need to separate them by types, or to wash them. This last characteristic makes the new process highly ecological.

It should be mentioned that in the worldwide use of plastics, polyethylenes and polypropylenes predominate by almost 80%. Consequently, an urban plastic waste is a candidate to develop a solid and resistant board.

OBJECTS OF THE INVENTION

It is a main objective of the invention to propose a machinery and process designed for the use of urban, agricultural and industrial post-consumer plastic waste for the development of new products, for example, plastic boards that can be used in different sectors of the industry, thereby promoting the recycling of waste material to produce other useful items. Concurrently, this seeks to raise awareness so that certain products that are commonly made with wood or other materials, such as formwork for the construction industry, walls or fences, pavers, parking stops, containment barriers, roofing sheets, pots , boxes, miscellaneous furniture, etc., are produced with plastic waste material paying a rational exploitation of our forests. Likewise, this collaborates in the care of the environment because plastic waste that today represents a pollution problem is given appropriate use when it is recycled into other very useful products.

The above and other additional objects will be materialized by means of an installation composed of several machines that jointly make it possible, through a specific process, to make boards from plastic waste.

In a preferred embodiment, the machine of the present invention comprises:

- a set of tracks that define a circuit or path through which molds are transported along a panel production circuit;

- one or more molds in which the plastic waste, previously ground, is poured; each mold has support columns at the lower end of which it has bearings that allow it to slide along the production line of the boards; each mold also includes a suspension system to ensure proper board pressing;

- one or more furnaces with a melting chamber of plastic waste in which the molds with the waste to be melted are introduced; each oven includes an entrance door and an exit door for the entrance and exit of the molds to the oven and of this one, and in addition a means of actuation to impel the molds inside and outside of said chamber;

- at least one pressing station, located close to the foundry homo, to which the mold leaving the oven is transferred to compress the molten plastic board; said press consists of hydraulic cylinders and a hydraulic drive means for subjecting the molten material to compression; likewise, said pressing station includes a mold cooling system;

- to | less a car to transport the molds throughout the process stations; Y

- a driving system by means of which the cars and the molds of the machine are driven to move along the production circuit of the panels.

In addition to the previous components, a knife mill is included to crush the plastic waste until a granulated material is obtained in uniform and fine representation, and a scale for dosing the loads of the ground plastic material in the molds.

In addition, a resting press is included to keep the boards under pressure after the melting process. Likewise, other attachments or tools for working the resulting board such as, for example, a circular table saw for framing, sizing and cutting the boards produced are also part of the equipment of the present invention. In one embodiment, the final product obtained with the machine is a board with dimensions of approximately 1,250 mm x 2,500 mm (4 'x 8') with thicknesses ranging from 5 mm to 90 mm. However, it will be understood that the dimensions of the board will be determined by the specific needs that are required and therefore they can be distinguished from those mentioned here by way of example. The board produced is worked with the same equipment used for wood and can be coated with paints.

Based on the nature of the process and the mixing of the raw material ("plastic waste") the board will have an indefinite color finish. However, this does not imply that, if desired or convenient, the board cannot be produced of a certain color simply by adding coloring substances to the mixture. DESCRIPTION OF THE FIGURES OF THE INVENTION

Figure 1 is a perspective view of a first embodiment of the machinery of the present invention in which the main components thereof are shown in the process line.

Figure 2 is a rear perspective view of the melting furnace of the machinery for making plastic boards.

Figure 3 is a perspective view of the press station that is a component of the machinery of the present invention.

Figure 4 is a partial view of the machinery in which the foundry homo, the press station and a mold just removed from it are shown.

Figure 5 is a partial representation of an alternate embodiment of the invention composed of two press stations.

Figure 6 is another view of the press station with the mold subjected to compression.

Figure 7 is an almost frontal view of the foundry homo with the door open to allow observing the interior thereof.

Figure 8 is illustrative of the track change system for moving the molds along the line of the casting process.

Figure 9 is a perspective view of a mold to show the load damping system it incorporates. Figure 10 is a perspective view of an alternate embodiment of the present invention consisting of two line ovens and two press stations with their corresponding control means.

Figures 11, 12 and 13 are representative schematic views of different embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED MODE

OF THE INVENTION

The machinery of the present invention is characterized in that it consists of a set of equipment or components that are operatively interrelated and positioned in such a way that they favor the development of the different stages of the process that are carried out to make the plastic waste boards. Likewise, it relates to a method for making boards from said plastic waste.

The machine consists mainly of the following elements: a) Casting chamber (20) .- Consisting of an insulated electric homo, with controlled temperature up to 300 ° C, sufficient to melt thermoplastics. The casting chamber (20) has a nominal production of 70 kg / hr, which can be increased if two or three additional chambers are available, which would double and triple the production, respectively. It will be understood that the oven heating system may be different, for example from gas, to the one mentioned above without implying that it deviates from the concept of the present invention.

A characteristic of the casting chamber (20) is that it has a double thermal insulation system. In addition, the chamber has two temperature control zones in order to keep the interior of the oven at a uniform temperature for the smelting of plastic waste.

b) Press station (30) .- Component where the board is compressed once the plastic waste has melted. It consists of hydraulic cylinders (32) and a 3 hp power source (hydraulic pump 34). In this same component (30) the plastic is gradually cooled by means of a 5 ton water cooler. Cold water circulates inside the press deck, and inside the counter press or mold holder.

In one embodiment, the machine of a camera (20) has a press station (30), however, as seen in the figures, in other alternatives 2 or more press stations (30) may be installed.

c) Mold (40) .- It consists of a tray p drawer of carbon steel with the appropriate dimensions to obtain boards of 1,250 mm x 2,500 mm., or any other major or minor dimension. Each mold (40) has 4 columns (42) where bearings (44) are fastened, which can be 4 per column. Between the column (42) and the bearings (44) there is a spring suspension (45) that allows the proper pressing. The number of molds (40) varies according to the desired capacity of the machine model. In one embodiment, the machine that has a chamber has 4 molds; with two cameras 5 molds and with three cameras 6 molds.

d) Change of track (70) .- Component that allows the change of the mold (40) between the main track (64) and the return path (66) towards the beginning of the production circuit of the boards. Two of these elements (70) are provided for any machine model.

b) Car (90) .- Component that runs through the change of track (70), taking with it the mold of the main track (64) to the return path (66). There are two cars for any machine model.

c) Return (66) .- Component with rails where the mold (40) runs back to the beginning of the production circuit. There is a return to the machine of a camera; two for the two chamber machine; and three for the three chamber machine.

Some other peripheral accessories that can be used, but which are not necessarily part of the invention, are a mill for crushing plastic waste and obtaining a granulated material in a uniform and fine presentation; and a scale to dose the loads of the material to be melted.

EXAMPLED MODE OF THE MACHINE:

Oe according to a preferred embodiment of the invention, the machine for making boards is characterized in that it comprises:

a) a set of tracks that define a circuit or path through which molds (40) are transported along a panel production circuit; wherein said set of tracks consists of tubular elements (62) configured in such a way that they allow the safe sliding of the cars and molds along them. The track assembly includes a track change element (70) that allows the change of the mold from a main track (64) to a return circuit (66) that leads the mold to the start of the production circuit.

b) at least one mold (40) in which the previously ground plastic waste is poured; said mold has support columns (42) at the lower end of which it has bearings (44) that allow it to slide along the production line of the boards; The mold also includes a suspension system (45) for proper pressing of the board; c) a furnace with a casting chamber (20) of plastic waste in which the molds with the waste to be melted are introduced; said furnace includes an entrance door (22) and an exit door (24) for molds, actuated by means of hydraulic devices (25), for the entrance and exit of the molds to the oven and from it, and also actuation means motor (28) to drive the molds inside and outside said chamber;

d) at least one pressing station (30), located next to the smelting furnace (20), to which the mold (40) that exits the oven is transferred to compress the molten plastic board; said press (30) consists of hydraulic cylinders (32) and a hydraulic drive means (34) for subjecting the molten material to compression; likewise, said pressing station includes a mold cooling system;

e) at least one carriage (90) for transporting the at least one mold along the process stations; Y

a driving system by means of which the carts and the molds of the machine are propelled for their movement along the circuit of production of the boards.

Additionally, the machine includes a centralized control panel (80) through which the different variables and stages involved in the production of the panels are controlled.

PROCESS:

Regarding the stages of the elaboration of the boards, the process is characterized by the following:

1) Casting Stage of the process in which the plastic melts into an open mold (40) inside the electric oven (20). The plastic must be added to said mold in a granular presentation (ground, densified and / or pelletized), where it must have a uniform arrangement by means of a sash to ensure the manufacture of a board of uniform thickness.

It is important to note that the plastic does not need any additive, in this way the foundry is 100% plastic. However, it is necessary to impregnate the interior of the mold with a non-stick agent, such as a siiicone emulsion, to prevent the board from sticking to the mold due to dirt or other debris.

The foundry has no losses, the kilos that are founded will be the kilos that the board weighs. The thickness or thickness of the board is defined by the kilos to be melted, this is based on the specific weight of the plastics. However, it can be estimated that a square meter of 20 mm thick produced board has a weight of approximately 18.5 kg. Thus, for reference the following values can be indicated for the plastic boards produced:

Thickness (mm) Weight Approx. (kg / m ² )

15 13.87

20 18.50

25 23.12

30 27.75

40 37.00

50 46.25

60 55.50

70 64.75

80 74.00

90 83.25

The above values are useful for calculating the weight in kilos of any measure and board thickness, as well as to define the kilos that the mold will carry according to the desired thickness, considering that the mold has an area of approximately 3.25 m ² . For example, a 20 mm thick board needs approximately 60 kg. These quantities may vary slightly according to the type of plastic to use. The time needed for the casting of the plastic, also goes according to the desired thickness and obviously to The kilos to melt. However, it can be determined that a thickness of 20 mm melts in approximately 60 minutes at an approximate temperature of

220 ° C

2) Pressing

After the appropriate time inside the oven, the mold (40) with the molten plastic is removed therefrom by means of a chain transmission (not shown). This places the mold on the car and / or intermediate track change. As the case may be, the mold is placed manually within one of the press stations (30), to proceed with the next stage of the process, which is pressing.

The steel plate of the press is introduced hydraulically into the mold until it makes contact with the plastic. The pressure level is calculated based on the hardness and fluidity of each material. The press plate maintains a temperature between 7 ° C and 18 ° C, which gradually cools the plastic.

The pressing and cooling time must be slightly shorter than the casting time in order to receive the next mold in the pressing station.

The resulting board will be finished according to the plastic waste used, that is, it will be mottled or streaked with the predominant colors of the waste. However, it is feasible to incorporate a dye into the plastic prior to the casting stage if it is desired to obtain a board of a certain color.

The resulting board is a solid product with high resistance to fracture, humidity and weather, and has an infinite number of applications.

Another feature of the board is that it can be machined with all kinds of tools and equipment such as those used for wood and steel. For example, it is easily cut with a circular bench saw, it can be nailed without fractures, and it also supports coatings as well as any type of paint.

Currently there is no glue for polyethylenes, so mechanical joints or failing to weld with the same material and hot air application must be used.

Normally, the final products from the boards are assembled or assembled mechanically with screws and / or nails, being resistant and giving great versatility of applications. An important feature of the method of the present invention is that it does not require water to operate, except in the mold cooling stage. Logically, this translates into an added value because when said liquid is not used, it is not unnecessarily contaminated unlike other processes.

Also, another advantage of the new method of the present invention is that plastics are processed with impurities and without the need to separate them by types or classes of plastics.

SOME SPECIFICATIONS OF THE RESULTING BOARD:

Physical Properties:

Specific gravity: 0.96 gr / cc

The weight of the boards is calculated based on the specific weight.

In general and according to our experience, 0.96 gr / cc is used to calculate the weights, as follows:

thickness (mm) x 0.96 «= Kg / m2

Example:

20 mm x 0.96 = 19.2 Kg / m2 (a square meter with a thickness of 20 mm weighs approximately 19.2 Kg).

Thermal Properties:

Maximum operating temperature: 75 ° C

Softening point: 130 ° C

Maximum low temperature resistance (HMWPE): -75 ° C

Mechanical properties:

Hardness: shore D 63; rockwell 49

Stress Effort: 3,300 psi

Elongation for rupture: 800%

Flexural modulus: 125,000 psi

Izod impact: 8 ft-lb / in

It will be understood that the physical, thermal and mechanical properties specified above may vary according to certain factors, such as the type of polyethylene and their degradation, among others.

On the other hand, a method for making boards or plates from plastic waste is described, which is characterized by the following stages: a) crush the plastic waste until a granulated material is obtained in a uniform and fine presentation;

b) dose the loads of the granulated material to be melted before pouring them into molds;

c) adding said granulated material to the mold (densified and / or pelletized), ensuring that it has a uniform arrangement using for this purpose a slab to ensure the manufacture of a board of uniform thickness;

d) insert the mold with the load of granulated plastic material into a smelting furnace in which it melts at an approximate temperature of 220 ° C;

e) remove the mold with the molten plastic material from the casting homo and pass it to a pressing station;

f) subject the molten plastic material contained in the mold to compression with a press for a time less than that of the casting time of another mold introduced into the smelting furnace; Y

g) cool the molten material in the mold.

Although the invention has been described in the context of the preferred embodiment or embodiment, it will be apparent to those skilled in the art that the scope of the exemplified concept extends beyond that of the machine and method specifically described and illustrated to other possible alternate embodiments of the invention that are feasible or viable. Furthermore, although the invention has been described in detail, any expert in the field to which the invention belongs may deduce that some constituent elements of the system and / or steps of the method may be substituted or others different or modified, incorporated in the light of the above description without essentially modifying the result for which they were designed.

In view of the foregoing, it is intended that the scope of the present invention not be construed as limited by the particularly described embodiment, but rather be determined by a reasonable interpretation of the content of the following claims.

Claims

1. Machine for making boards from plastic waste, of the type that includes plastic casting and pressing equipment, said machine is characterized in that it comprises:

- at least one mold in which the plastic waste, previously ground, is poured; said mold has support columns at the lower end of which it has bearings that allow it to slide along the production line of the boards; The mold also includes a suspension system for proper board pressing;

- an oven with a plastic waste casting chamber in which the molds with the waste to be melted are introduced; said furnace includes an entrance door and an exit door for molds for the entrance and exit of the molds to the homo and of this, and also actuation means for driving the molds into and out of said chamber;

- at least one pressing station, located next to the smelting furnace, to which the mold leaving the furnace is transferred to compress the molten plastic board; said press consists of hydraulic cylinders and a hydraulic drive means for subjecting the molten material to compression; likewise, said pressing station includes a mold cooling system;

- at least one carriage to transport the at least one mold along the process stations;

- a driving system by means of which the carriages and the molds of the machine are driven to move along the production circuit of the panels; Y

- a centralized control panel through which the different variables involved in the production of the boards are controlled.

2. The machine of claim 1, wherein the suspension system comprises spring elements placed each column, between the bearings and the middle section of said column.

3. The machine of claim 1, wherein the entrance and exit doors of the homo are hydraulically operated.

4. The machine of claim 1, wherein said casting chamber has a double thermal insulation system.

5. The machine of claim 1, wherein the casting chamber includes two temperature control zones.

6. The machine of the claim, wherein the cooling system is based on cold water circulating inside the press plate, and inside the counter press or mold support.

7. The machine of claim 1, wherein the set of tracks comprises tubular elements configured in such a way as to allow the safe sliding of the carriages and the molds along them.

8. The machine of claim 1, wherein the set of tracks includes a main track, a return path and a track change element that allows the change of the mold from the main path to the return path leading to the mold at the beginning of the production circuit.

9. The machine of claim 1, which may further include a mill for crushing plastic waste and obtaining a granulated material in a uniform and fine presentation.

10. The machine of claim 1, which may further include a scale for dosing the loads of the material to be melted.

11. The machine of claim 1, wherein the casting chamber operates with electric power or with gas.

12. A method for the elaboration of boards from plastic waste, which is characterized by the following stages: a) crush the plastic waste to obtain a granulated material in a uniform and fine presentation;

c) add said granulated material to

(densified and / or pelletized), ensuring that it has a uniform arrangement using a standard to ensure the manufacture of a board of uniform thickness;

e) remove the mold with the molten plastic material from the smelting furnace and pass it to a pressing station;

f) subjecting the molten plastic material contained in the mold to compression with a press for a time less than that of the casting time of another mold introduced into the smelting furnace; Y

g) cool the molten material in the mold.

13. The method of claim 12, wherein before pouring the granulated material into the mold, the interior thereof is impregnated with a non-stick agent to prevent the board from sticking to the mold due to dirt or other debris.

14. The method of claim 12, wherein the plastics are processed with impurities and without the need to separate them by types or classes of plastics.