WO1997012748A1

WO1997012748A1 - Process for recycling polymer products to produce boards

Info

Publication number: WO1997012748A1
Application number: PCT/US1996/015912
Authority: WO
Inventors: Benjamin Anaya Hernandez
Original assignee: Milet Hernandez, Carlos; Sanchelima & Associates, P.A.
Priority date: 1995-10-03
Filing date: 1996-10-03
Publication date: 1997-04-10
Also published as: AU7255496A; MX9504188A

Abstract

A process for recycling products by homogenizing the monomers of products of different molecular weights. Initially, the products are triturated and milled to relatively small granules. Subsequently they are sprayed with a compound that includes 70-90 % motor oil, 3-10 % agglutinant nopal resin and 5-15 % monobutylic ether of diethylene glycol. The impregnation of this compound homogenizes polymers of different molecular weights by freeing up compatible monomers. Depending on the amount of the compound used, the rigidity of the resulting extruded board is varied. For rigid boards, it has been found that approximately 200 ml/kg of the compound should be used. After being sprayed, the granules are extruded (42) and passed through a temperature gradient filed (60) ranging from 250° to 140 °C. The board is then transported to a cutting stage (90).

Description

I. TITLE: "PROCESS FOR RECYCLING POLYMER PRODUCTS TO

PRODUCE BOARDS"

II. TECHNICAL FIELD

The present invention relates to a process for recycling and recovering polymer products found in industrial and municipal dumps to produce boards, and more particularly to such a process that does not require classification and separation of different types of products.

III. BACKGROUND ART

Most recycling systems today require the separation of different polymer products according to their molecular weight and other characteristics that make them compatible for such a process. This is a time consuming process and the advantage of not having to go through this secondary step is apparent.

IV. SUMMARY OF THE INVENTION

It is one of the main objects of the present invention to provide a process for recovering polymer product from industrial and municipal dumps or cities sites to produce boards by mechanically and chemically homogenizing the different polymers without the need of classifying and separating the raw material by its physical and chemical properties.

It is another object of this invention to provide a process for recovering polymers to produce useful articles of manufacture, such as boards.

It is still another object of the present invention to provide a process for recovering plastic and polymers to produce boards with a superior finished quality and ability to obtain predetermined thickness and length dimensions for the boards. It is yet another object of this invention to provide such a process that is considerably less costly to practice while retaining its effectiveness.

Further objects of the mvention will be brought out in the following part of the specification, wherein detailed description is for the purpose of fully disclosing the invention without placing limitations thereon.

V. BRIEF DESCRIPTION OF THE DRAWINGS

With the above and other related objects in view, the invention consists in the details of construction and combination of parts as will be more fully understood from the following description, when read in conjunction with the accompanying drawings in which:

Figure 1 represents the equipment used for the first phase of the process of recycling and recovering polymers, namely, the preparation of the raw material.

Figure 2 represents the equipment used for the second and third (final) phases of the process, where the raw material is physically and chemically processed until a board is produced.

Figure 3 represents a screening hopper member used in the milling chamber.

Figure 4 illustrates a helicoidal screw extrusion apparatus used in the preferred embodiment to extrude the raw material (mix) to obtain a melted mixture.

Figure 5 is an exploded isometric view of the screw extrusion apparatus and a head /die member. VI. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention discloses a process for recycling and recovering polymers found in industrial and municipal dumps to produce usable products, such as boards. These polymer products may include bottles, toys, containers, accessories, etc. In the process disclosed herein the operators do not have to classify the polymers by their physical and chemical properties, such as molecular weight and chemical composition, to be able to obtain a suitable raw material for further processing in the form of a granulated mixture. Such classification required in conventional recycling systems delay and increase the cost of the production. The present invention overcomes this shortcoming permitting a user to homogenize different polymer products with mixtures having different proportions of polymers with high and low densities.

The process for recycling and recovering polymers to produce boards, subject of the present invention, includes three main phases.

The first phase of this process includes the processing of the raw polymer product found in different industrial and municipal dumps. The equipments used to practice this first phase is shown in figurel. Typically, the polymer waste is grouped in a pile (1) that may be exposed to the elements, recyclable polymer waste products usually have dimensions that do not exceed 1.5 m in length. The waste product is dropped in loading /feeding hopper (10) which in turn feeds crusher or triturator chamber (12). Chamber (12), in the preferred embodiment, has a volumetric capacity of 600 cm? and it is mounted on steel stand (16). Triturator chamber (12) includes a 15 HP motor and horizontally disposed rotatable blades (not shown in the drawings) that crush polymer objects to fragments of less than 25 cm. in length and 10 cm. in width. The triturated fragments are discharged through outlet hopper (14) at a rate of approximately 4.5 Kgs. per minute to transporting band (20), in the preferred embodiment. Transporting band (20) has 10 meters of length running at approximately 30 degrees angle of inclination with respect to the supporting horizontal surface. Transporting band (20) is driven by a 1 HP motor (22) with, electromechanical transmission, outputting 8 R.P.M. The triturated fragments traveling on transporting band (20) are discharged into loading /feeding hopper (30) which in turn feeds them to milling chamber (32) with a volumetric capacity of 600 cm? Milling chamber (32) includes horizontally rotatably fixed and semifixed blades that granulate the incoming triturated fragments. Milling chamber (32) also includes screening hopper member (34) with holes (36) of 6.3 mm of diameter, as it is shown in figure 4. Screening hopper member (34) is designed for the screening of the outcoming granules to a maximum diameter of 6.3 mm. Then, the resulting granules are discharged at the approximate rate of 5 Kgs. per minute through two outlet hoppers (38) and (38') mounted to the bottom of milling chamber (32). The resulting plastic granules are packed in Nylon bags (39) with an average capacity of 35 Kgs., to be transported and used in the second phase of this process as raw material.

The second phase of this process starts with the addition of a chemical substance to the to soften the molecular weight of the polymers with high concentration of monomers or rigid polymers. This chemical compound is a liquid mix and it basically consists of the following compounds:

Compounds Percentage

•motor oil, with international 70-90% specifications API SF/SAE 40

•agglutinant resin of nopal 3-10%

• monobutylic ether of diethylene glycol 5-15%

This chemical compound is added in proportions of approximately 180- 220 milliliters per kilogram of granules, for boards with a rigid consistence. It is added 140-180 milliliters per kilogram of granules, for boards with a semirigid consistence . And, it is added 120 milliliters per kilogram of granules, for boards with a flexible consistence. This chemical compound is added to the granules (poured from bags (39)) in a stirring apparatus (not shown in the drawings) and the process continues until all the granules are impregnated with the chemical compound. This chemical and mechanical process will react to homogenize the heterogenic mix of polymers with different molecular weights and characteristics in the next step ( in the screw extrusion apparatus described below). These impregnated granules are packed again in bags (39') and ready to be poured into loading /feeding hopper (40) of helicoidal screw extrusion apparatus (42), as is illustrated in figure 2. The granules are fed to extrusion apparatus (42) for melting or fusing. Extrusion apparatus (42), in the preferred embodiment, basically includes motor members (43) and (44), helicoidal screw (45) and extrusion die (46). Extrusion die (46) is mounted to the bottom of feeding hopper (40) and extrusion apparatus (42) is removably mounted to extrusion die (46), at one end, as best seen in figure 3. Extrusion die (46), in the preferred embodiment, includes cooling coil (49) with water traveling at a temperature of 5oC. Cooling coil (49) is necessary at this point to avoid an excess of high temperature because of the mechanical parts of the equipment. Also, because the incoming granules can start melting in extrusion die (46) causing the melted mix to obstruct inlet (41') of helicoidal screw (45). Helicoidal screw (45) rotates within a barrel or cylindrical assembly (41) that in turn comprises two main sections: inlet (41') and outlet (41"). Six electrical resistance elements (48) are located along the extension of barrel or cylindrical assembly (41). Electrical resistance elements (48) control the necessary melting range of temperature of the raw material mixture traveling through barrel or cylindrical assembly (41). This range of temperature is important for the chemical reaction of the polymer granules with the chemical compound that was previously added. Electrical resistance elements (48) define six areas where the temperature of the mix varies, as follows: Element 1 Element 2 Element 3 Element 4 Element 5 Element 6 250⁰C 220°C 200°C 180°C 160⁰C 140°C

where, element 1 is located next to inlet (41') and element 6 is located next to outlet (41") of barrel or cylindrical assembly (41). In this manner, the granule mix i s exposed to different temperature gradients as it advances.

The melted mixture that exits outlet (41") is limited by throttle member (47) that acts against the extrusion force. Throttle member (47) guarantees that the necessary pressure for the melted polymer mixture passing through aperture (52) of die member (50) is present. Die member (50), as shown in figure 5, is removably mounted to throttle member (47) and has elongated flat aperture (52) permitting the melted mixture to pass through and obtain a shaped or outlined board. Aperture (52) of die member (50) has 1.20 meters of length, 0.21 cm. of width and 13 cm. of thickness, and is made out of steel. Extension member (54) is removably mounted to the end of die member (50) and over aperture (52). Extension member (54) includes L-shape members (56) and (56') disposed parallel and spaced apart to each other. L-shape members (56) and (56') define slot (58) that forms the resulting board.

In the third phase of this process, as illustrated in figure 2, the shaped or outlined board is cooled by a band (60). This band has two sides and is resistant to relatively high temperature, such as 100 ^C. The band is moved by an electromechanical 1 HP motor . Cold water of about 5^C is sprayed to low the temperature of the board. Then, the board passes to calibrated roller apparatus (70) where it is textured by eliminating irregularities on the surfaces of the resulting board. Calibrated roller apparatus (70) has three lower calibrating rollers and three upper calibrating rollers, in the preferred embodiment. These six calibrating rollers have an internal recycling water flow running at 5^C and drive their power from 3 HP motor. The thickness of the board is calibrated from 5mm to 30 mm depending on the separation of the upper and lower rollers. Finally, the extruded and formed board is transported through transporting band (80) to the cutting stage (90) where the boards are sawed.

The foregoing description conveys the best understanding of the objectives and advantages of the present invention. Different embodiments may be made of the inventive concept of this invention. It is to be understood that all matter disclosed herein is to be interpreted merely as illustrative, and not in a limiting sense.

VII. INDUSTRIAL APPLICABILITY

It is apparent from the previous paragraphs that an improvement of the type for a such process of recycling and recovering polymer products, found in industrial and municipal dumps, is quite desirable to be used for obtaining boards in the industry.

Claims

VIII. CLAIMSWhat is claimed is:

1. A process for recycling polymer products of different molecular weights to obtain a useful board, comprising the steps of:

A) triturating said products to fragments of a maximum predetermined diameters;

B) milling said fragments and reducing same to granules;

O impregnating said granules with a compound that includes a base of motor oil with fifteen percent by volume of agglutinant nopal resin and monobutylic ether of diethylene glycol;

D) extruding said impregnated granules with the application of a plurality of temperature zones as the extruded material advances in the extrusion process and these temperature zones vary from 250°C to 140°C at the end of the extrusion step;

E) shaping said extruded material in a predetermined manner; and

F) cooling down said shaped extruded material.

2. The process set forth in claim 1 wherein said extruding step includes six temperature zones, the first temperature zone being at the beginning of said extrusion step and having a temperature of approximately 250°C, the second through the sixth temperature zones being contiguous and having a temperature of 20°C less for at the end of the extrusion step.

3. The process set forth in claim 2 wherein 140 to 240 millimeters of said compound are used for each kilogram of said granules, depending on the rigidity desired for the resulting board.