# US 10,479,875 B2 · Process for the treatment of a composition comprising thermoplastics

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- Number: US 10,479,875 B2
- Document ID: US10479875B2
- Status: Granted
- Kind: B2
- Application number: 15/743,048
- Filed: 2016-07-13
- Published: 2019-03-21
- Granted: 2019-11-19
- Earliest claimed: 2015-07-14
- Assignees: Solvay SA
- Applicants: Solvay SA
- Inventors: Stéphane Streiff; Dominique Balthasart; Armin T. Liebens; Gérard Antonini
- Web page: https://patentgrep.com/patent/US10479875B2

## CPC

- C08J 11/12: by dry-heat treatment only
- C07C 4/22: by depolymerisation to the original monomer, e.g. dicyclopentadiene to cyclopentadiene
- C08J 11/08: using selective solvents for polymer components
- C08J 2323/02: not modified by chemical after treatment
- C08J 2323/06: Polyethene
- C08J 2323/12: Polypropene
- C08J 2325/06: Polystyrene
- Y02W 30/62: Plastics recycling; Rubber recycling
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

The present invention relates to a process for the treatment of a composition comprising thermoplastics comprising introducing the composition into a reactor under reduction of oxygen content of the atmosphere, heating the composition in the presence of a solvent to liquefy the thermoplastics, separating insoluble fractions and recovering the liquefied thermoplastics which process is conducted in one reactor.

## Claims

### Claim 1

Process for the treatment of a composition comprising thermoplastics, the process comprising the steps of
a) introducing the composition comprising thermoplastics into a reactor under reduction of oxygen content of the atmosphere, wherein the oxygen content is reduced to below 10 vol % of gas phase,
b) heating the composition to a temperature in the range of 150° C. to 450° C. in the presence of a solvent, wherein the solvent has a boiling point of between 50° C. and 150° C. and wherein the amount of solvent is 0.1 kg to 10 kg per kg of thermoplastics, to obtain a drop in viscosity below 104 mPas of at least 50% by weight of the thermoplastics, based on the total content of the thermoplastics,
c) separating solid and/or gaseous fractions of the composition at the surface of the mixture and/or the bottom of the reactor, and
d) recovering liquefied thermoplastics from the reactor,
wherein the process steps a) to c) are conducted in one reactor.

### Claim 2 (depends on 1)

Process according to claim 1, wherein the process steps a) to c) are conducted continuously.

### Claim 3 (depends on 1)

Process according to claim 1, wherein the solvent used in step b) is an aliphatic hydrocarbon.

### Claim 4 (depends on 1)

Process according to claim 1, wherein the solvent used in step b) is a C6 to C8 alkane or a mixture of C6 to C8 alkanes.

### Claim 5 (depends on 1)

Process according to claim 1, wherein the solvent forms an azeotropic mixture with water.

### Claim 6 (depends on 1)

Process according to claim 1, wherein in step b) the composition is heated in the presence of the solvent to a temperature in the range of above 250° C. to 400° C.

### Claim 7 (depends on 1)

Process according to claim 1, wherein the composition comprises at least 80% polyethylene, polypropylene and polystyrene as thermoplastics.

### Claim 8 (depends on 1)

Process according to claim 1, wherein steps a) to d) are followed by a step e) of cracking the liquefied thermoplastics.

### Claim 9 (depends on 8)

Process according to claim 8, wherein the cracking is thermal or catalytic cracking.

### Claim 10 (depends on 1)

Process according to claim 1, wherein the composition comprises waste plastic.

### Claim 11 (depends on 1)

Process according to claim 1, wherein steps a) to d) are preceded by a step of reduction of the particle size of the thermoplastics.

### Claim 12 (depends on 2)

Process according to claim 2, wherein the process steps a) to c) are conducted simultaneously in the reactor.