SI21606A - Mechanical recycling procedure for composite polymeric material - Google Patents

Abstract

A mechanical processing procedure is described for composite material consisting of partly crosslinked polymethylmetacrylate, acrylonitrile-butadiene-styrene copolymer, unsaturated polyester resin and glass fibres by using a pressing out - extrusion method. Material shall be ground and dried prior to processing. The extruder shall operate at a temperature between 180 and 230 degrees Celsius and allow transition of softened and unmelted particles of material. By using the procedure described, homogeneous products of various dimensions can be obtained without application or with minimum application of additives to the output material.

Description

MECHANICAL RECYCLING PROCEDURE FOR COMPOSITE POLYMER MATERIAL

The subject of the invention is a process of mechanical recycling of waste composite polymer material into products of different dimensions. The waste composite polymer recycling material according to the invention consists of 30-40 parts (by weight) of glass fiber-reinforced polyester resin, 30-60 parts of partially cross-linked polymethylmethacrylate and 0-70 parts of acrylonitrile-butadiene-styrene (ABS) copolymer. This type of composite material is used for the production of large-scale load-bearing products such as bathroom fixtures, slides or vessels. The recycling of this composite material is limited by the difficult separation of constituent components and the fact that unsaturated polyester resin and partially cross-linked polymethylmethacrylate are not thermoplastic materials that can be transformed into melt. Waste from such composite materials is therefore mostly disposed of at landfills.

Existing methods of processing waste composite polymeric materials are based on the fact that the majority of the mixture is a thermoplastic material that wraps other parts of the mixture as fillers. The established procedures use abrasion-resistant extruders and the thermoplastic fraction should not be less than 70%, according to the recommendations of the device manufacturers. Such a method could also be applied to said composite polymer material, but in this case, due to the addition of a thermoplastic (to represent about 70% of the final mixture), the total amount of material would be greatly increased. The invention described herein solves the technical problem of recycling mixed polymer waste from cross-linked polymers, without or with minimal thermoplastic additives.

Published inventions in the field of recycling polymer composites from cross-linked polymers are based on depolymerization and reuse methods (WO 03/051956 Al), use of solvents at elevated temperatures (WO 01723463 Al, US 2002/0017162 Al) or pyrolysis process (WO 02 / 088277 Al). The above methods require a large amount of energy and fall into t. im. chemical recycling methods in which the polymer is mainly degraded or chemically treated. Mechanical recycling of composite waste with a predominantly polyester resin described in the invention (EP 1 273 627 Al), but in this case it is a material composition substantially different from the material described in the present invention. The object and object of the invention is a process for recycling a low-thermoplastic composite polymer material that will be technologically simple, energy-efficient and economical.

According to the invention, the problem is solved by a process of mechanical recycling of waste composite polymer material according to an independent claim.

The process according to the invention is based on extrusion of ground mixed waste. Due to the nature of the material, the extruder must have a screw (snail) that permits a smooth flow of non-molten, softened particles of crushed material. The particle size and thus the shape of the snail depend on the pre-preparation of the material during the grinding and / or sieving process. The extruder must have a regulated external heating system that allows temperatures to be reached at which the viscosity (partial melting) of polyester, polymethylmethacrylate and / or ABS is reached. Single or double auger estruder can be used, with or without the possibility of degassing the heated mass. An extruder with a screw diameter of at least 25 mm and temperatures between 180 and 230 ° C was used.

Prior to processing, the material must be ground to a particle size that allows the material to be introduced into the extruder without interruption, depending mainly on the method of material feed, inlet openings and the screw diameter. In order to achieve homogeneity and a relatively smooth surface of the product, the material must be dried to a constant mass before being processed so as not to contain moisture. The proportion of ABS copolymer can be varied arbitrarily, but this affects the processing properties of the material. Without ABS or with a small amount of ABS, it is possible to fill the molds and extrude non-demanding shapes, and by increasing the proportion of ABS it is possible to extrude more complex shapes.

The mixed waste is mixed in the passage through the extruder and softened under the influence of heat. Softened polyester, polymethylmethacrylate and ABS connect non-molten polymer particles and glass fibers to produce a homogeneous mass formed in a continuous profile from the device. The shape of the profile depends on the choice of the outlet nozzle, respectively. destination of the product. The product can also be shaped by introducing a softened mass into metal molds of various dimensions and shapes. Chilled products have strengths that are comparable to the strengths of ive boards. On the surface and after the cross section, larger particles of polymethylmethacrylate, polyester resin and fibers are observed, but they are strongly interconnected. The product does not absorb water or swell in the presence of moisture. During the continuous extrusion process, a layer of polymethylmethacrylate can be applied to the surface of the product by continuous extrusion, which gives the product a flawless appearance.

The invention described herein improves the process of mechanical recycling of a polymer composite based on polymethylmethacrylate, ABS, unsaturated polyester resin and glass fibers. The main advantage of the process described is that it allows for affordable mechanical recycling of large quantities of mixed polymer waste, without or with minimal content of thermoplastics, binders or other additives, which would increase the cost of processing and increase the amount of material recovered.

Example 1

Composite Composition: 50% polymethylmethacrylate, 30% unsaturated polyester resin and 20% glass fibers were ground to a maximum particle size of 11 mm. The resulting mixture was run into a single screw extruder with a screw diameter of 25 mm. The extrusion was carried out at 220 ° C. The resulting full profile was compact, homogeneous and solid after cooling. The inside of the profile was homogeneous and free of air bubbles. No thermal overheating or uncontrolled thermal decay of any mixed material component occurred during processing.

Example 2

Composite Composition: 50% polymethylmethacrylate, 35% unsaturated polyester resin and 15% glass fibers were ground to a maximum particle size of 15 mm. The resulting mixture was run into a single screw extruder with a 60 mm diameter screw. The extrusion was carried out at 190 ° C. The molten mixture was introduced directly into the metal mold until it was full. The induction was then interrupted, the model closed and allowed to cool to a temperature of about 50 ° C. The model was then opened to remove the product from it. The cross-section of the product showed that the interior of the product was homogeneous.

Example 3

Composite composition; 50% polymethylmethacrylate, 10% acrylonitrile butadiene styrene copolymer, 25% unsaturated polyester resin and 15% glass fibers were ground to a maximum particle size of 15 mm. The resulting mixture was run into a single screw extruder with a 60 mm diameter screw. The extrusion was carried out at 190 ° C. The resulting tube, with walls between 5 and 7 mm thick, was compact, homogeneous and solid after cooling, with no air bubbles.

Example 4

Composite Composition: 33% polymethylmethacrylate, 40% acrylonitrile butadiene styrene copolymer, 17% unsaturated polyester resin and 10% glass fibers were ground to a maximum particle size of 15 mm. The resulting mixture was run into a single screw extruder with a 60 mm diameter screw. The extrusion was carried out at 190 ° C. Profile was calibrated. The resulting 35 mm diameter rod was compact, homogeneous and solid after cooling, with no air bubbles.

The process of mechanical recycling of waste composite polymeric material from partially cross-linked polymethylmethacrylate, acrylonitrile-butadiene-styrene copolymer, unsaturated polyester resin and fiberglass into products of different dimensions is characterized in that the material is suitable for grinding to a particle size prior to processing in an extruder, that the process takes place in a extruder - an extruder heated to an operating temperature between 180 and 230 ° C. Material consisting of 30 - 40 parts by weight of unsaturated glass fiber reinforced polyester resin, 30-60 parts of partially crosslinked polymethylmethacrylate and 0 - 70 parts of copolymer of acrylonitrile butadiene styrene (ABS). The extruder permits the passage of loose particles of material. The material does not contain moisture or is dry to constant weight before processing. The mass resulting from the extruder is formed into a continuous profile of different shapes, depending on the outlet nozzle and the intended use of the products. Continuous profiles can be coated with a layer of polymethylmethacrylate using co-extrusion. The mass resulting from the extruder can also be formed by being introduced into molds of various dimensions and shapes.

The process according to the invention is energy and material saving since it does not require a large input of energy or added materials. This makes the invention specific and economically efficient.

The foregoing embodiments of the invention do not limit, but merely explain.

Claims (6)

1. A process for the mechanical recycling of waste composite polymeric material, characterized in that it contains 30 - 40 parts (by weight) of glass fiber-reinforced polyester resin, 30-60 parts of cross-linked polymethylmethacrylate and 0-70 parts of acrylonitrile-butadiene styrene copolymer (ABS) that the material is ground prior to processing to a particle size suitable for dispensing into an extruder and that the process takes place in an extruder extruder which is heated to an operating temperature between 180 and 230 ° C. A method according to claim 1, characterized in that the extruder allows the passage of non-molten particles of material. Process according to claim 1, characterized in that the material is moisture-free or dried to constant weight before processing. Method according to claim 1, characterized in that the mass resulting from the extruder is formed into a continuous profile of different shapes, depending on the outlet nozzle and the intended use of the products. Method according to claim 4, characterized in that the continuous profiles are coated with a layer of polymethylmethacrylate using co-extrusion. A method according to claim 1, characterized in that the mass resulting from the extruder is formed by being introduced into molds of various dimensions and shapes.