Method for recycling waste plastics containing polybrominated diphenyls and polybrominated diphenyl ethers

Abstract

The invention discloses a method for recycling waste plastics containing polybrominated diphenyls and polybrominated diphenyl ethers, which comprises the following steps: adding waste electronic plastics into a solvent A, dissolving the waste electronic plastics at normal temperature, screening the dissolved plastic solution by using a separating screen, centrifugalizing the screened plastic solution, complementally adding the solvent A into the centrifugalized plastic solution, applying ultrasonic waves onto the solution, adding the obtained plastic solution into a solvent B, and stirring for 30-90 minutes at the rotation speed of 1000-2000 revolutions / minute under the action of ultrasonic waves of which the frequency is 20-50 kHz and the power is 0.5-1.5 W / cm<2>; and sending the plastic precipitate into a twin screw extruder, and removing the residual solvent in the precipitate at 180-220 DEG C, thereby obtaining the recycled plastic product. The mass percent of polybrominated diphenyls and polybrominated diphenyl ethers in the plastics treated by using the method provided by the invention is reduced to lower than 0.1% without great loss of physical and mechanical properties.

Description

technical field [0001] The invention relates to a regeneration method of waste plastics, in particular to the recycling of polybrominated diphenyl ether and polybrominated biphenyl flame-retardant waste plastics, and the method is suitable for the regeneration of flame-retardant waste electronic plastics. Background technique [0002] The dismantling and recycling process of waste electronic and electrical equipment produces a large amount of plastic waste. These plastics are generally added with 5-20% brominated flame retardants. Among them, polybrominated biphenyls and polybrominated diphenyl ethers have been proven to be harmful to the environment, organisms and human beings. Persistent organic pollutants that are harmful to health, so the European Union clearly stipulates in the "Directive on the Restriction of the Use of Certain Hazardous Components in Electrical and Electronic Equipment" (RoHS Directive) that all products sold in the EU market will be effective from Jul...

AI Technical Summary

Problems solved by technology

However, there are the following problems in adopting this patented method to reclaim polybrominated diphenyl ether flame-retardant plastics: (1) decabromodiphenyl ether theoretically still has a solubility of 0.1 to 0.2 wt% in these solvents at room temperature, and the polybrominated diphenyl ethers below nona bromine The solubility is greater, due to the high boiling point and low volatility, most of the dissolved polybrominated diphenyl ethers cannot be removed with the solvent in the subsequent vacuum evaporation process

(2) The particle size of decabromodiphenyl ether raw materials is generally 1 to 5 microns. Experiments have found that the decabromodiphenyl ether particles in waste plastics will also partially dissolve when the plastic dissolves, resulting in a smaller particle size. Therefore There are a large number of decabromodiphenyl ether particles with a particle size of less than 1 micron in the plastic solution. These small particles cannot be separated even by high-speed centrifugation. As a result, the concentration of decabromodiphenyl ether in the plastic solution after centrifugation Significantly higher than its theoretical solubility in solvents

However, the supercritical extraction process has problems such as high equipment requirements, harsh separation conditions, and unsuitability for large-scale production.

[0007] It can be seen that the existing technology cannot better solve the regeneration problem of plastic wastes containing polybrominated biphenyls and polybrominated diphenyl ethers.