Method for recycling waste plastic material containing styrene polymer

A method for recovering a thermoplastic polymer from a waste plastic containing the thermoplastic polymer selected from the group consisting of styrene polymers, ABS resin and polypropylene, which comprises:

• dissolving the waste plastic in about 10 wt % to about 50 wt % of a solvent having a boiling point of about 75.degree. C. to about 175.degree. C. and being capable of dissolving the waste plastic to form a solution of the waste plastic at an elevated temperature;
• filtering the solution under pressure to remove foreign debris from the solution;
• depressurizing the filtrate from said filtration;
• heating the filtrate to a temperature of 200.degree.-300.degree. C. under a pressure of 1-75 torrs to remove the solvent by evaporation;
• extruding the resulting plastic melt into pellets, whereby the waste plastic is recovered;
• condensing the solvent separated by the vacuum-evaporation;
• refining said condensed solvent by distillation;
• and
• recycling the solvent for use as a solvent for dissolving the waste polymer.

A method for recovering a thermoplastic polymer from a waste plastic containing the thermoplastic polymer selected from the group consisting of styrene polymers, ABS resin and polypropylene, which comprises:

• dissolving the waste plastic in about 10 wt % to about 50 wt % of a solvent having a boiling point of about 75.degree. C. to about 175.degree. C. and being capable of dissolving the waste plastic to form a solution of the waste plastic at an elevated temperature;
• filtering the solution under pressure to remove foreign debris from the solutions;
• depressurizing the filtrate from said filtration by passing the solution through a needle valve;
• preheating the filtrate using a multi-tube heat exchanger;
• heating the filtrate to a temperature of 200.degree.-300.degree. C. under a pressure of 1-75 torrs to remove the solvent by evaporation;
• extruding the resulting plastic melt into pellets, whereby the waste plastic is recovered;
• condensing the solvent separated by the vacuum-evaporation;
• refining said condensed solvent by distillation;
• and
• recycling the solvent for use as a solvent for dissolving the waste polymer.