Method and apparatus for separating polymer from a plastic, and the resulting separated polymer
OwnerPeter H. Farmer, John M. Mosesinventors
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Abstract
A method and apparatus for continuously separating polymer from a plastic, and the resulting separated polymer. The plastic is made flowable into a stream through melting or solubilizing. A critical fluid, such as supercritical carbon dioxide, is added to the plastic stream to promote mechanical or thermodynamic separation of the polymer from contaminants and other components of the plastic.
Claims15
A method of purifying a polymer component of a thermoplastic which includes at least a second component other than the polymer, using a fluid which is a gas at room temperature, and which is a solvent for the second component, the method including the steps of:
- mixing the thermoplastic with a cosolvent which at least partially dissolves the polymer, and that is miscible in said fluid, to decrease the viscosity of the thermoplastic;
- introducing into the thermoplastic-cosolvent mixture, said fluid in the liquid, critical fluid, or supercritical fluid state, to solubilize and thus to separate the second component from the polymer, and in which said introduced fluid precipitates some of the dissolved polymer from the cosolvent;
- and
- separating the precipitated polymer from the mixture, to recover purified polymer from the thermoplastic.
The method of 6 in which said fluid is carbon dioxide.
A method of purifying a polymer component of a thermoplastic which includes at least a second component other than the polymer, using a fluid which is a gas at room temperature, and which is a solvent for the second component, the method including the steps of:
- mixing the thermoplastic with a cosolvent which at least partially dissolves the polymer, and that is miscible in said fluid, to decrease the viscosity of the thermoplastic;
- introducing into the thermoplastic-cosolvent mixture, said fluid in the liquid, critical fluid, or supercritical fluid state, to solubilize and thus to separate the second component from the polymer, and in which said introduced fluid precipitates some of the dissolved polymer from the cosolvent;
- filtering the thermoplastic-cosolvent mixture, either before or after the introduction of said fluid, to remove particulate contaminants;
- mixing the thermoplastic-cosolvent-fluid mixture with additional said fluid in the liquid state, to precipitate dissolved polymer from the cosolvent;
- and
- separating the precipitated polymer from the mixture, to recover purified polymer from the thermoplastic.
Dependencies are inferred from the claim text.