METHOD FOR PRODUCING RESINS FROM RUBBER CHIPS

Abstract

A method of production of hydrocarbon-containing resins starting from a charge comprising rubber chips comprises at least one pyrolysis step and a resin synthesis step.

Claims

1.-15. (canceled)

16. A method of producing hydrocarbon-containing resins starting from a charge comprising rubber chips, the method comprising: (a) a step of pyrolysis of the rubber chips carried out at a temperature between 300 and 900 C. with an increasing temperature ramp, giving a gaseous effluent, a pyrolysis oil and a solid effluent, the pyrolysis oil comprising at least 1.5 wt % of C.sub.4-C.sub.12 olefinic monomers; (b) a step of separation of the pyrolysis oil into at least one raffinate, an intermediate fraction and an extract, the intermediate fraction comprising at least 20 wt % of C.sub.4-C.sub.12 olefinic monomers and at most 10 wt % of heteroatoms; (c) a resin synthesis step comprising a polymerization section supplied at least with the intermediate fraction resulting from step (b) and with a solvent selected from aliphatic, aromatic and halogenated solvents and mixtures thereof, followed by a finishing section producing a polymerized effluent; and (d) a step of treatment of the polymerized effluent resulting from step (c) comprising a section for separation of an effluent rich in solvent and an effluent rich in resins, and a drying section supplied with the resin-rich effluent in order to produce a stream of hydrocarbon-containing resins.

17. The method according to claim 16, wherein the rubber chips comprise at least 50 phr of diene elastomer.

18. The method according to claim 17, wherein the diene elastomer is selected from the group consisting of natural rubber, synthetic polyisoprenes, polybutadienes, butadiene copolymers, isoprene copolymers and mixtures thereof.

19. The method according to claim 16, wherein the pyrolysis step (a) comprises operating a pyrolysis reactor at a temperature between 350 and 800 C., a pressure below 1 bar, and a ratio of residence time of solid to residence time of gas from 10 to 240.

20. The method according to claim 16, wherein the pyrolysis step (a) is carried out with an increasing temperature ramp between 1 and 10 C./min.

21. The method according to claim 16, wherein the intermediate fraction resulting from step (b) comprises at most 2 wt % of sulfur element.

22. The method according to claim 16, wherein the separation step (b) is carried out by distillation.

23. The method according to claim 22, wherein the separation step (b) is carried out in a column with an internal wall, the intermediate fraction being obtained by side-stream draw-off from the column.

24. The method according to claim 16, wherein the intermediate fraction resulting from step (b) undergoes a purification treatment before supplying step (c).

25. The method according to claim 24, wherein a content of heteroatoms in the intermediate fraction at the end of the purification treatment is below 2 wt %.

26. The method according to claim 16, wherein the solvent selected from aliphatic, aromatic and halogenated solvents and mixtures thereof is selected from C.sub.7-C.sub.10 aromatic solvents, C.sub.6-C.sub.8 aliphatic solvents and C.sub.1-C.sub.2 chlorinated solvents and mixtures thereof.

27. The method according to claim 16, wherein the polymerization section is operated in the presence of an acid catalyst.

28. The method according to claim 16, wherein the finishing section of step (c) is carried out by contacting with a stream comprising a stopper compound selected from water, a C.sub.1-C.sub.3 alcohol and mixtures thereof, at a temperature between 5 and 80 C., followed by separation by phase decanting of the polymerized effluent and an effluent comprising predominantly the stopper compound.

29. A finished or semi-finished rubber article comprising a resin obtained by the method according to claim 16.

30. A pneumatic or non-pneumatic tire comprising a resin obtained by the method according to claim 16.

Description

DESCRIPTION OF THE FIGURES

[0130] FIG. 1 shows a schematic view of the method according to the invention.

[0131] A charge comprising rubber chips (1) is fed to a step (A) of pyrolysis of the rubber chips, giving a gaseous effluent (3), a pyrolysis oil (2) and a solid effluent (4). The pyrolysis oil (2) is fed to a step (B) of separation of the pyrolysis oil (2) into at least one raffinate (7), an intermediate fraction (5) and an extract (6), the intermediate fraction (5) comprising at least 20 wt % of C.sub.4-C.sub.12 olefinic monomers and at most 10 wt % of heteroatoms. The intermediate fraction (5) is then fed to a resin synthesis step (C) comprising a polymerization section supplied at least with the intermediate fraction (5) and with a solvent (8) selected from aliphatic, aromatic and halogenated solvents and mixtures thereof, operated in the presence of an acid catalyst, followed by a finishing section producing a polymerized effluent (9). This polymerized effluent (9) is treated in a treatment step (D) comprising a section for separation of an effluent rich in solvent (11) and a resin-rich effluent, and a drying section supplied with the resin-rich effluent in order to produce a stream of hydrocarbon-containing resins (10).

[0132] FIG. 2 shows a schematic view of the method according to the invention. The common elements with FIG. 1 are numbered identically.

[0133] A charge comprising rubber chips (1) is fed to a step (A) of pyrolysis of the rubber chips, giving a gaseous effluent (3), a pyrolysis oil (2) and a solid effluent (4). The pyrolysis oil (2) is fed to a step (B) of separation of the pyrolysis oil (2) into at least one raffinate (7), an intermediate fraction (5) and an extract (6), the intermediate fraction (5) comprising at least 20 wt % of C.sub.4-C.sub.12 olefinic monomers and at most 10 wt % of heteroatoms. The intermediate fraction (5) is purified in an optional purification step (P1) and is then fed to a resin synthesis step (C) comprising a polymerization section (C.sub.1) supplied at least with the intermediate fraction (5) and with a solvent (8) selected from aliphatic, aromatic and halogenated solvents and mixtures thereof, operated in the presence of an acid catalyst so as to produce a stream from the polymerization section (12), this stream being fed to a finishing section (C.sub.2) producing a polymerized effluent (9). The finishing section (C.sub.2) is also supplied with a stream comprising a stopper compound (13) and produces an effluent comprising predominantly the stopper compound (14). The polymerized effluent (9) is treated in a treatment step (D) in which it is fed to a section for separation (D1) of a solvent-rich effluent (11) and a resin-rich effluent (15), the latter being fed to a drying section (D2) that produces a stream of hydrocarbon-containing resins (10). The solvent-rich effluent (11) may be fed to an optional purification treatment (P2) in order to be reused in the method according to the invention.

Example 1

[0134] An implementation of the method according to the invention is described hereunder.

[0135] Pyrolysis Step

[0136] A step for pyrolysis of rubber chips is supplied with chips having an average diameter of about 1 mm and a density of 504 kg/m.sup.3, resulting from the grinding of tyres of heavy goods vehicles of all dimensions and many brands. These chips have a content of isoprene elastomers of 65 wt %.

[0137] The pyrolysis step is carried out under an inert atmosphere of nitrogen, in a reactor comprising 3 sections heated independently at respective temperatures of 425 C., 550 C. and 775 C., therefore having an increasing temperature profile.

[0138] A gaseous effluent, a pyrolysis oil and a liquid effluent are separated at reactor outlet with the following respective yields (effluent flow rate/feed flow rate): 13.5%, 44.5% and 42%. The pyrolysis oil comprises about 4 wt % of several monomers of interest, including styrene, methylstyrene, indene, beta-pinene and limonene.

[0139] Step of Separation of the Pyrolysis Oil

[0140] The pyrolysis oil is fed to a step of separation by distillation carried out in two sections at atmospheric pressure. In a first section, a light cut is separated, whose initial boiling point is below 160 C., constituting the extract. The heavier fraction is fed to a second section for producing a raffinate whose cut point is 280 C., i.e. whose initial boiling point is 280 C. at atmospheric pressure, and an intermediate cut constituting the intermediate fraction. The content of olefinic monomers in this fraction is about 33 wt %, including 24.3 wt % of limonene, 2.8 wt % of styrene and 3 wt % of indene.

[0141] Resin Synthesis Step

[0142] The intermediate fraction is fed to a resin synthesis step. Aluminium chloride (2 mol % relative to the content of monomers) is introduced into a reactor under an inert atmosphere. The reactor is then kept under inert atmosphere throughout the reaction.

[0143] The intermediate fraction is enriched in limonene by contribution of an external stream of bio-based limonene so as to achieve a content of olefinic monomers of 70 wt %. This mixture is then injected into the reactor in the presence of a toluene solvent. The amount of toluene solvent is adjusted so that the content of monomers is between 50 wt % and 75 wt %, in this instance 58 wt %. The mixture is stirred and operated at a temperature of 25 C. for 2 h. The reaction is then stopped by adding water.

[0144] The reaction mixture, constituting the polymerized effluent, is separated into an effluent rich in solvent and an effluent rich in resins by washing with water and coagulation of the resins with methanol. The resin-rich effluent is then dried in a stove at 175 C. for 24 h. A resin is recovered in the form of a yellow/orange translucent solid.

[0145] This resin has a glass transition temperature Tg=25 C.

Example 2Implementation of a Purification Treatment

[0146] All of the steps described in Example 1 are carried out, with the following modification:

[0147] At the end of the step of separation of the pyrolysis oil, the intermediate fraction is supplied to a treatment for purification by passing over alumina beads. The weight flow rate of intermediate fraction in kg/h to the weight of alumina ratio is equal to 1 h.sup.1. The intermediate fraction at the outlet of the bed of alumina beads then supplies the resin synthesis step as described in Example 1.

[0148] A resin is recovered in the form of a yellow/orange translucent solid having a number-average molecular weight Mn=770 g/mol, a polydispersity index PDI=1.2 and a glass transition temperature Tg=92 C.