EP4294892A1

EP4294892A1 - Pyrolysis of polycarbonate-containing material in order to recover raw materials

Info

Publication number: EP4294892A1
Application number: EP21843741.6A
Authority: EP
Inventors: Stefanie Eiden; Rainer Bellinghausen; Aurel Wolf; Erik SLUYTS; Jonas KRAUSE; Andreas Seidel
Original assignee: Covestro Deutschland AG
Current assignee: Covestro Deutschland AG
Priority date: 2021-02-17
Filing date: 2021-12-22
Publication date: 2023-12-27
Also published as: EP4047073A1; WO2022174963A1; CN116848217A; KR20230146533A; JP2024507200A

Abstract

The invention relates to a method for pyrolysis of polycarbonate-containing material in order to recover raw materials. The method comprises at least the following steps: (a) introducing material intended for the pyrolysis, at least comprising material that contains a mixture of a polycarbonate-containing compound and a polystyrene-containing compound, into a reactor; (b) decomposing, at a temperature of 300°C to 700°C, at least the material intended for pyrolysis introduced into the reactor in step (a) and obtaining a product that is present in the gaseous phase as the pyrolysate and of pyrolysis residues that are present in a non-gaseous phase, (i) the amount of oxygen gas in the reactor during decomposition being not more than 2.0 vol.% relative to the entire volume of the gases present in the reactor, and (ii) the pyrolysate being removed from the reactor during decomposition, and (iii) the pyrolysis residues being removed from the reactor; (c) cooling the removed pyrolysate to a temperature of less than 300°C while obtaining a pyrolysis product, selected from pyrolysis condensate, pyrolysis sublimate or a mixture thereof; and (d) optionally processing the pyrolysis product. When carrying out this method in a correspondingly designed device, raw materials for producing polycarbonate-containing composite materials, in particular bisphenol-A and styrene, can be recovered from these composite materials.

Description

"Pyrolysis of polycarbonate-containing material for the recovery of raw materials"

Polycarbonate-containing material - such as polycarbonate blends, e.g. polycarbonate resin or polycarbonate composite resin - is used as a material for consumer goods. Corresponding polycarbonate resins or polycarbonate composite resins are made by blending the polycarbonate with other polymers, such as by blending polycarbonate with acrylonitrile butadiene styrene (ABS). Because these polycarbonate-containing materials have excellent properties such as impact resistance, flowability, toughness, and flame retardancy, they are used in a variety of applications, such as electronic devices and automobiles.

After the above polycarbonate resins and polycarbonate composite resins have been put on the market as a component of many commercial products, they are discarded as valuable materials at the end of the life of the commercial products. Old commercial products are mainly disposed of and exchanged for new commercial products. The total amount of resulting plastic waste is increasing every year. About 60% of the total amount of this waste is disposed of through incineration or landfill.

When the plastic waste is incinerated, CO2 is emitted into the air, which contributes to global warming. Because of its low density, plastic waste in landfills takes up a large volume and from there can also contribute to general pollution in rivers and seas. For this reason it is important to develop efficient recycling methods with which the waste problem can be solved and at the same time fossil resources can be saved.

Since the above-mentioned polycarbonate (composite) resins make up around 8% of the polymer market, the recycling of polycarbonates has not been the focus of developments so far. For the future, however, due to the continuing growth in the plastics market, it is important to develop recycling technologies for all polymer classes in order to both reduce CO2 emissions and save fossil fuels.

The processes for recycling plastic waste can be roughly divided into 3 categories:

(1) Mechanical recycling: Here, the plastic waste is melted down again as it is and can then be reused. This is possible, for example, for very pure PC waste. (2) chemical and thermochemical recycling: Here, the plastic waste is depolymerized into monomers or broken down into smaller molecules to obtain useful chemical raw materials and

(3) thermal recycling, wherein the waste plastics are converted into exhaust gas and heat energy.

The chemical raw materials obtained from thermochemical recycling can be used to synthesize new synthetic resins or other chemical products.

Thermochemical recycling is called pyrolysis. In most cases, pyrolysis is applied to packaging waste and from it a pyrolysis oil is obtained, which is used as a type of recycled naphtha in the well-known refinery processes with crackers as drop in solution. Little is known about the pyrolysis of polycarbonate in this pyrolysis process.

The use of catalysts or additives in the pyrolysis process can lead to lower operating temperature, shorten reaction time, increase degradation efficiency and restrict product distribution, making the process more efficient.

By using metal halide salts as catalysts, especially copper and iron chloride catalysts, it was possible to produce more phenolic compounds during the pyrolysis of polycarbonate at 600° C than without a catalyst (M. Blazsö, J. Anal. Appl. Pyrolysis, 1999, 51, 73-88). Furthermore, the catalytic pyrolysis of polycarbonate was optimized by using various metal chloride compounds with the aim of reducing char residues (J. Chiu et al., Waste Manage., 2006, 26, 252-259). The influence of the catalyst was determined at 400 °C (1 h), since the uncatalyzed pyrolysis proceeds very slowly at this temperature. The choice of metal chloride had a large effect on pyrolysis. NaCl, CrCb, CuCb, and AlCb did not improve pyrolysis rates, while SnCb and ZnCb degraded the polycarbonate with over 80% weight loss.

The product distribution of the pyrolysis of polycarbonate could also be improved by the use of metal salt catalysts. While in the non-catalytic polycarbonate pyrolysis the liquid product contained eleven different products, the mixtures with ZnCb or SnC12 as the catalyst obtained only seven main products, including bisphenol A, phenol and diphenyl ether with smaller amounts of impurities.

Catalysts consisting of metal oxides and zeolites with different porosities and acid/basicity are also known for the pyrolysis of polycarbonate-containing material (E. V. Antonakou et al. polym. degradation Stab., 2014, 110, 482-491. MN Siddiqui et al., Thermochim. Acta, 2019, 675, 69-76).

With the help of basic catalysts such as CaO and MgO, the temperature in the pyrolysis could be significantly reduced to 400-450 ° C, with the simultaneous production of liquid fractions with high proportions of phenolic compounds (DS Achilias et al., J. Appl. Polym. Sci., 2009, 114, 212-221. EC Vouvoudi et al., Front. Environ. Sci. Eng., 2017, 11, 9). A slow release of BPA and CO2 from polycarbonate at 440 ^° C. could be demonstrated from a mixture of polypropylene (PP), acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS) and polycarbonate.

Under the influence of alkaline earth oxides and hydroxides (MgO and Mg(OH)2), better efficiency and higher BPA yield (78%) could be achieved in the steam pyrolysis of pure polycarbonate at 300 ⁰ C, while heating to 500 ⁰ C with A large proportion of phenol (84%) was produced with the aid of MgO (T. Yoshioka et al., Polym. Degrad. Stab., 2009, 94, 1119-1124, T. Yoshioka et al., Ind. Eng. Chem. Res., 2014, 53, 4215-4223).

The publication US 2007/0185309 A1 describes a method for depolymerizing polycarbonates with water in the supercritical or subcritical state. A highly pure dihydroxy component (BPA,) which is a component of polycarbonate could be obtained in high yield by this method. This depolymerization method is environmentally friendly because it does not use organic solvents. It shows a high decomposition rate and few by-products.

None of the pyrolysis methods described in the prior art are suitable for industrial or commercial use, since they are mostly intended as pyrolysis on a microgram scale for analytical purposes. The pyrolyses presented in the prior art are therefore carried out in pyrolysis devices which are not suitable for industrial or commercial use.

In particular for the pyrolysis of larger amounts of polycarbonate-containing materials, which also include other ingredients in addition to polycarbonate, new processes with suitable reactors are required, with the help of which the influence of the other ingredients on the result of the pyrolysis of the polycarbonate can be reduced. Despite the presence of other ingredients, pyrolysis products containing a high content of cleavage products that can be reused for polycarbonate synthesis, in particular aromatic hydroxy compounds such as bisphenol A (BPA) or phenol, are to be obtained from polycarbonate-containing polymer mixtures. It is preferred for energetic reasons, if in high A large amount of aromatic compounds having at least two hydroxyl groups, in particular those of the following general formula (I), are recovered by the pyrolysis, since they can be used directly again for the production of polycarbonates in a polycondensation reaction without further energy-intensive petrochemical conversion steps.

In addition, said new method for pyrolysis should deliver such a pyrolysis product in which, in addition to the cleavage products that can be reused in the polycarbonate synthesis, cleavage products of the other ingredients, e.g. styrene from polystyrene-containing material, are contained in significant quantities and good yields, which suitable for the production of said ingredients in terms of cyclic recycling.

It was therefore the task to provide a method for the commercial execution of pyrolysis and pyrolysis devices usable therein for the pyrolysis of pyrolysis material, at least comprising material containing a mixture of polycarbonate-containing compound and polystyrene-containing compound, with its use even with larger amounts of pyrolysis material an amount of pyrolysis product is obtained, the cleavage products that can be reused for the synthesis of polycarbonate-containing and polystyrene-containing material, preferably in an amount of more than 40% by weight based on the total weight of polycarbonate-containing and polystyrene-containing material used , contains. It was also an object to recover a large amount of aromatic compounds having at least two hydroxyl groups, in particular those of the general formula (I) below, by the pyrolysis of pyrolysis material containing polycarbonate-containing compound. A further object was to recover a large amount of aromatic compounds having at least two hydroxyl groups, in particular those of the general formula (I) below, and styrene by the pyrolysis.

One subject of the present application is therefore a method for pyrolysis, comprising at least the following steps

(a) introducing pyrolysis material, at least comprising material containing a mixture of polycarbonate-containing compound and polystyrene-containing compound, into a reactor;

(b) decomposition of at least the material of the pyrolysis material introduced in step (a) in the reactor at a temperature of 300° C. to 700° C. to obtain product in the gas phase as pyrolysate and non-gas phase pyrolysis residue, wherein (i) during said decomposition the amount of oxygen gas in the reactor is from 0 to 2.0% by volume based on the total volume of gases in the reactor, and

(ii) during said decomposition, said pyrolyzate is discharged from the reactor, and

(iii) said pyrolysis residue is discharged from the reactor;

(c) cooling the discharged pyrolysate to a temperature of less than 300°C to obtain pyrolysis product selected from pyrolysate condensate, pyrolysate resublimate or a mixture thereof;

(d) optional processing of the pyrolysis product.

All of the substances introduced into the reactor for pyrolysis, which are thermally treated there in the absence of oxygen gas or in the presence of a reduced amount of oxygen gas, are referred to as "pyrolysis material". Before being introduced into the reactor, the pyrolysis material is preferably in solid form.

“Pyrolyzate” is understood to mean all those products formed by pyrolysis which are in the gas phase of the reactor under the conditions of step (b) (in particular as a gas and/or as an aerosol).

“Pyrolysis residue” is understood to mean all those substances formed by pyrolysis and the other residues of the pyrolysis material which are not in the gas phase of the reactor under the conditions of step (b). Those embodiments of the process which are characterized in that the pyrolysis residue in the reactor is solid are preferred.

“Pyrolysis product” is understood to mean all those products from the pyrolysate that are obtained in step (c) during the cooling of the pyrolysate by condensation and/or resublimation. Pyrolysis product that is liquid is also known as pyrolysis oil.

Unless explicitly defined otherwise in the context, a substance (e.g. material, pyrolysis product, pyrolysate, pyrolysis product, pyrolysis residue) is “liquid” if it is in the liquid state at 20°C and 1013 mbar. Unless explicitly defined otherwise in the context, a substance (e.g. material, pyrolysis product, pyrolysate, pyrolysis product, pyrolysis residue) is "solid" if it is in the solid state of aggregation at 20°C and 1013 mbar. Unless explicitly defined otherwise in the context, a substance (e.g. material, pyrolysis product, pyrolysate, pyrolysis residue) is "gaseous" if it is present as a gas at 20°C and 1013 mbar im. A substance is "organic" if its chemical structure contains at least one covalent carbon-hydrogen bond.

The mean molar masses specified in this application for polymers or polymeric ingredients are - unless explicitly stated otherwise - always weight-average molar masses Mw, which can be determined in principle by means of gel permeation chromatography using an RI detector, with the measurement being useful against a external standard takes place.

A "polycarbonate-containing compound" is a polymeric compound selected from a homo- or copolymer obtained by polyreaction and wherein at least one repeating unit contains at least one *-0-C-0-* structural unit,

O where * indicates a valency of the polymer backbone.

In the context of the present application, “polystyrene-containing material” or “polystyrene-containing compound” is understood to mean a material or a compound, preferably a polymer, containing structural units derived from styrene or styrene derivatives, in particular from styrene.

A "polystyrene-containing compound" in this sense is a polymeric compound selected from a homo- or copolymer, which is obtained by polymerization reaction and contains as a repeating unit at least one structural unit *-CR ¹ Ph-CH2-*, where * is a valence of the polymer backbone indicates that R ¹ is a hydrogen atom or a methyl group and Ph is a phenyl group which is optionally substituted with at least one group selected from (C1 to C4)-alkyl group, halogen atom (especially chlorine). Said material particularly preferably contains, in addition to at least one polycarbonate-containing compound, at least one polymer as a polystyrene-containing compound which has at least one structural unit according to the above formula derived from styrene (R ¹ = H, Ph = phenyl), a-methylstyrene (R ¹ = methyl , Ph = phenyl), p-methylstyrene (R ¹ = H, Ph = 4-methyl-phenyl), p-chlorostyrene (R ¹ = H, Ph = 4-chlorophenyl) or mixtures thereof. R ¹ = H according to the above formula is more preferred.

A "reactor" is a volume in which a chemical conversion, eg thermal decomposition of material from the pyrolysis material, takes place. For thermal decomposition, for example, this can be the volume of a heated vessel in which the pyrolysis material is located. According to the invention, it is advantageous to introduce the pyrolysis material into a reactor according to the method according to the invention, which is characterized in that it is selected from a continuous stirred tank reactor (CSTR), fixed bed reactor, fluidized bed reactor, screw reactor, screw conveyor reactor, entrained flow reactor, entrainment flow reactor, rotary tube reactor, fluidized bed reactor, paddle reactor. In particular, those reactors are preferably suitable in which the pyrolysis material can be introduced continuously and are selected in particular from rotary tube reactors, continuous stirred tank reactors (CSTR), fixed bed reactors (in particular with continuous bed exchange (shaft reactor) with internal heat exchangers, preferably with internal heat exchanger tubes), screw reactors, screw conveyor reactors , entrained flow reactor, rotary tube reactor or fluidized bed reactor. A very particularly preferred reactor of an embodiment of the process is selected from a screw reactor, a rotary kiln or a fluidized bed. Further reactors preferred for the process according to the invention and their embodiments are described in the context of the embodiments of the device for pyrolysis according to the invention and in the context of an embodiment of the process using a catalyst (many below).

According to the invention, the pyrolysis material introduced into the reactor comprises at least one material containing a mixture of polycarbonate-containing compound and polystyrene-containing compound.

In one embodiment of the method according to the invention, said pyrolysis product contains said material in a total amount of 10.0 to 80.0% by weight, more preferably 30.0 to 70.0% by weight, in each case based on the total weight of the pyrolysis material.

It has proven to be advantageous if said material of the pyrolysis material is preferably introduced into the reactor in the form of solid particles (in particular in the form of a granular mixture). A granular mixture of said material is formed from a multitude of loose, solid particles of said material, which in turn comprise so-called granules. A grain is a designation for the particulate components of powders (grains are the loose, solid particles), dusts (grains are the loose, solid particles), granules (loose, solid particles are agglomerates of several grains) and other granular mixtures. The flowability of a granular mixture relates to its ability to flow freely under its own weight from a flow test funnel with a 16.5 mm diameter outlet. The solid particles, in particular the loose, solid particles of the granular mixture, of said material introduced into the reactor preferably have an average diameter X o (volume average) of 0.01 mm to 5 cm, preferably 0.1 mm to 5 cm. on. The mean particle size diameter X50. is determined by sieving or using a particle size analyzer Camsizer from Retsch.

In general, said material can be, for example, a homopolymer, a copolymer, a comb polymer, a block polymer or mixtures thereof.

Said materials are particularly suitable in which, in addition to said polystyrene-containing compound, at least one compound containing at least ten is contained as the polycarbonate-containing compound

Contains structural units *-O-C-O-*, where * represents a valency of the polymer backbone

0 marks.

Polycarbonate-containing compounds suitable for the process according to the invention for said materials are, for example, aromatic polycarbonates and/or aromatic polyester carbonates. These are known from the literature or can be prepared by processes known from the literature (for the preparation of aromatic polycarbonates see, for example, Schnell, "Chemistry and Physics of Polycarbonates", Interscience Publishers, 1964 and DE-AS 1 495 626, DE-A 2 232 877, DE-A 2 703 376, DE-A 2 714 544, DE-A 3 000 610, DE-A 3 832 396 for the production of aromatic polyester carbonates, e.g. DE-A 3 007 934).

The preparation of the aromatic polycarbonates usable as a polycarbonate-containing compound is carried out e.g. B. by reacting compounds having at least two hydroxyl groups, in particular diphenols, with carbonic acid halides, preferably phosgene and/or with aromatic dicarboxylic acid dihalides, preferably benzenedicarboxylic acid dihalides, by the phase interface process, optionally using chain terminators, for example monophenols and optionally using trifunctional or more as trifunctional branching agents, for example triphenols or tetraphenols. It can also be produced using a melt polymerization process by reacting compounds having at least two hydroxyl groups, in particular diphenols, with diphenyl carbonate, for example. According to the invention, said materials can advantageously be used in which the polycarbonate-containing compound is at least one compound which, by reacting at least the compounds (i) at least one aromatic compound having at least two hydroxyl groups, particularly preferably bisphenol A, and (ii) phosgene or diphenyl carbonate was obtained.

At least one aromatic compound having at least two hydroxyl groups, which is selected from the general formula (I), is preferably used to prepare the polycarbonate-containing compound. wherein

A is a single bond, Ci to Cs-alkylene, C2 to Cs-alkylidene, C5 to C _ö -cycloalkylidene, -O-, -SO-, -CO-, -S-, -SO2-, C o to _Ci2 -arylene, to which other aromatic rings optionally containing heteroatoms can be fused, or a radical of the formula (II) or (III)

B are each Ci to Ci2-alkyl, preferably methyl, halogen, preferably chlorine and/or bromine x are each independently 0, 1 or 2, p are 1 or 0, and

R ⁵ and R ⁶ can be selected individually for each X ¹ , independently of one another hydrogen or C 1 to C 6 _-alkyl , preferably hydrogen, methyl or ethyl,

XI is carbon and m is an integer from 4 to 7, preferably 4 or 5, with the proviso that X ¹ , R ⁵ and R ⁶ are simultaneously alkyl on at least one atom. Preferred aromatic compounds having at least two hydroxyl groups are hydroquinone, resorcinol, dihydroxydiphenols, bis(hydroxyphenyl)-C1-C5-alkanes, bis(hydroxyphenyl)-C5-C6-cycloalkanes, bis(hydroxyphenyl) ether, bis(hydroxyphenyl). )- sulfoxides, bis(hydroxyphenyl) ketones, bis(hydroxyphenyl) sulfones and a,a-bis(hydroxyphenyl)diisopropylbenzenes and their nuclear-brominated and/or nuclear-chlorinated derivatives.

Particularly preferred aromatic compounds having at least two hydroxyl groups are 4,4'-dihydroxydiphenyl, bisphenol A, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis-(4-hydroxyphenyl)-3.3.5-trimethylcyclohexane, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfone and their di- and tetrabrominated or chlorinated derivatives such as 2,2-bis(3 -Chloro-4-hydroxyphenyl)-propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)-propane or 2,2-bis(3,5-dibromo-4-hydroxyphenyl)-pro- pan. 2,2-bis(4-hydroxyphenyl)propane (bisphenol-A) is particularly preferred.

The aromatic compounds having at least two hydroxyl groups can be used individually or as any mixtures. The aromatic compounds having at least two hydroxyl groups are known from the literature or can be obtained by methods known from the literature.

Chain terminators suitable for the production of thermoplastic, aromatic polycarbonates are, for example, phenol, p-chlorophenol, p-tert-butylphenol or 2,4,6-tribromophenol, but also long-chain alkylphenols such as 4-[2-(2,4,4 -Trimethylpentyl)]-phenol, 4-(1,3-tetramethylbutyl)-phenol according to DE-A 2 842 005 or monoalkylphenol or dialkylphenols with a total of 8 to 20 carbon atoms in the alkyl substituents, such as 3,5-di-tert- butyl phenol, p-iso-octyl phenol, p-tert-octyl phenol, p-dodecyl phenol and 2-(3,5-dimethylheptyl) phenol and 4-(3,5-dimethylheptyl) phenol. The amount of chain terminators to be used is generally between 0.5 mole % and 10 mole %, based on the molar sum of the aromatic compounds with at least two hydroxyl groups used in each case.

In a preferred embodiment of the invention, thermoplastic, aromatic polycarbonates that can be used have average molecular weights (weight-average M _w , measured by GPC (gel permeation chromatography) with a polycarbonate standard based on bisphenol A) of preferably 20,000 to 40,000 g/mol, more preferably 24,000 to 32,000 g/mol , particularly preferably 26,000 to 30,000 g/mol. The thermoplastic, aromatic polycarbonates can be branched in a known manner, preferably by incorporating from 0.05 to 2.0 mol%, based on the sum of the aromatic compound used having at least two hydroxyl groups, of trifunctional or more than trifunctional compounds, for example those with three or more phenolic groups.

Linear polycarbonates, more preferably based on bisphenol A, are preferably used.

Both homopolycarbonates and copolycarbonates are suitable. 1 to 25% by weight, preferably 2.5 to 25% by weight, based on the total amount of aromatic compound to be used having at least two hydroxyl groups, of polydiorganosiloxanes with hydroxyaryloxy end groups can also be used to produce copolycarbonates which can be used with preference according to the invention. These are known (US Pat. No. 3,419,634) and can be produced by processes known from the literature. Also suitable are polydiorganosiloxane-containing copolycarbonates; the preparation of the polydiorganosiloxane-containing copolycarbonates is described, for example, in DE-A 3,334,782.

Aromatic dicarboxylic acid dihalides for the production of aromatic polyester carbonates are preferably the dicarboxylic acid dichlorides of isophthalic acid, terephthalic acid, diphenyl ether-4,4'-dicarboxylic acid and naphthalene-2,6-dicarboxylic acid.

Mixtures of the diacid dichlorides of isophthalic acid and terephthalic acid in a ratio of between 1:20 and 20:1 are particularly preferred.

In the production of polyester carbonates, a carbonic acid halide, preferably phosgene, is also used as a bifunctional acid derivative.

In addition to the monophenols already mentioned, suitable chain terminators for the preparation of the aromatic polyester carbonates are their chlorocarbonic acid esters and the acid chlorides of aromatic monocarboxylic acids, which may be substituted by C 1 to C 22 alkyl groups or by halogen atoms, and aliphatic C 2 to C 22 monocarboxylic acid chlorides.

The amount of chain terminators is in each case 0.1 to 10 mol %, based in the case of the phenolic chain terminators on moles of aromatic compound with at least two Hydroxyl groups and, in the case of monocarboxylic acid chloride chain terminators, on moles of dicarboxylic acid dichloride.

In the production of aromatic polyester carbonates, one or more aromatic hydroxy carboxylic acids can also be used.

The aromatic polyester carbonates can be either linear or branched in a known manner (see DE-A 2 940 024 and DE-A 3 007 934), preference being given to linear polyester carbonates.

Examples of branching agents which can be used are trifunctional or polyfunctional carboxylic acid chlorides, such as trimesic acid trichloride, cyanuric acid trichloride, 3,3'-,4,4'-benzophenone tetracarboxylic acid tetrachloride, 1,4,5,8-naphthalenetetracarboxylic acid tetrachloride or

Pyromellitic acid tetrachloride, in amounts of 0.01 to 1.0 mol% (based on the dicarboxylic acid dichlorides used) or trifunctional or polyfunctional phenols such as phloroglucinol, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)- hept-2-ene, 4,6-dimethyl-2,4-6-tri-(4-hydroxyphenyl)-heptane, l,3,5-tri-(4-hydroxyphenyl)-benzene, l,l,l- Tri-(4-hydroxyphenyl)ethane, Tri-(4-hydroxyphenyl)phenylmethane, 2,2-bis[4,4-bis(4-hydroxyphenyl)cyclohexyl]propane, 2,4-bis( 4-hydroxyphenyl-isopropyl)-phenol, tetra-(4-hydroxyphenyl)-methane, 2,6-bis(2-hydroxy-5-methyl-benzyl)-4-methyl-phenol, 2-(4-hydroxyphenyl)- 2-(2,4-dihydroxyphenyl)propane, tetra-(4-[4-hydroxyphenylisopropyl]phenoxy)methane, 1,4-bis[4,4'-dihydroxytriphenyl)methyl]benzene , Are used in amounts of 0.01 to 1.0 mol% based on the diphenols used. Phenolic branching agents can be introduced with the diphenols; Acid chloride branching agents can be charged along with the acid dichlorides.

The proportion of carbonate structural units in the thermoplastic, aromatic polyester carbonates can vary as desired. The proportion of carbonate groups is preferably up to 100 mol %, in particular up to 80 mol %, particularly preferably up to 50 mol %, based on the sum of ester groups and carbonate groups. Both the ester and the carbonate portion of the aromatic polyester carbonates can be in the form of blocks or randomly distributed in the polycondensate.

The aromatic polycarbonates and polyester carbonates can be used alone or in any desired mixture in the said material of the process according to the invention. In addition to at least one polycarbonate-containing compound, said material of the pyrolysis material also contains at least one polystyrene-containing compound.

In the context of the present application, “polystyrene-containing compound” is understood to mean a compound, preferably a polymer, containing structural units derived from styrene or styrene derivatives, in particular from styrene.

According to the invention, “polystyrene-containing compound” is therefore understood to mean a compound which contains a repeating unit derived from styrene which is optionally substituted on the aromatic ring (such as, in particular, styrene, a-methylstyrene, p-methylstyrene, p-chlorostyrene).

In one embodiment of the process according to the invention, such material is advantageously used in the pyrolysis material which, in addition to at least one polycarbonate-containing compound, contains at least one polymer as a polystyrene-containing compound which has at least ten repeating units of the formula

*-CR ¹ Ph-CH ₂ -* contains, in which * denotes a valency of the repeating unit of the polymer backbone, R ¹ represents a hydrogen atom or a methyl group and Ph an optionally with at least one group selected from (Ci to C4)-alkyl group, Halogen atom (particularly chlorine) substituted phenyl group. Said material particularly preferably contains, in addition to at least one polycarbonate-containing compound, at least one polymer as a polystyrene-containing compound which has at least ten repeating units of the above formula derived from styrene (R ¹ = H, Ph = phenyl), a-methylstyrene (R ¹ = methyl, Ph = phenyl), p-methylstyrene (R ¹ = H, Ph = 4-methyl-phenyl), p-chlorostyrene (R ¹ = H, Ph = 4-chlorophenyl) or mixtures thereof.

As a material that can be used with preference according to the invention, in addition to at least one polycarbonate-containing compound, it also contains at least one polymer as a polystyrene-containing compound, selected from rubber-modified graft polymers (Bl) with structural units derived from styrene or styrene derivatives or rubber-free vinyl (co)polymers with styrene or styrene derivatives derived structural units (B2) or a mixture of several such polymers. Such rubber-modified graft polymers (B1) which are preferably used include

B.1.1 5 to 95, preferably 15 to 92, in particular 25 to 60% by weight, based on component B.1, of at least one vinyl aromatic and/or nuclear-substituted vinyl aromatic (such as styrene, a-methylstyrene, p-methylstyrene p-chlorostyrene).

B.1.295 to 5, preferably 85 to 8, in particular 75 to 40% by weight, based on component Bl, of one or more rubbery graft bases, preferably with glass transition temperatures <10° C., more preferably <0° C., particularly preferably 20°C. The glass transition temperature is determined by means of differential scanning calorimetry (DSC) in accordance with the standard DIN EN 61006 at a heating rate of 10 K/min with definition of the T _g as the midpoint temperature (tangent method).

The graft base B.1.2 generally has an average particle size (do value) of 0.05 to 10 μm, preferably 0.1 to 5 μm, particularly preferably 0.2 to 1 μm. The average particle size d o is the diameter above and below which 50% by weight of the particles are in each case. It can be determined by means of an ultracentrifuge measurement (W. Scholtan, H. Lange, Colloid, Z. and Z. Polymere 250 (1972), 7824796).

Monomers B.1.1 are preferably mixtures of

B.l.1.1 50 to 99, preferably 60 to 80, in particular 70 to 80 parts by weight, based on B.1.1, vinyl aromatics and/or nuclear-substituted vinyl aromatics (in particular selected from styrene, a-methylstyrene, p-methylstyrene, p-chlorostyrene or mixtures thereof), and

B.1.1.2 1 to 50, preferably 20 to 40, in particular 20 to 30 parts by weight, based on B.1.1, vinyl cyanides (unsaturated nitriles such as acrylonitrile and methacrylonitrile) and/or (meth)acrylic acid (Ci-Cs )-alkyl esters such as methyl methacrylate, n-butyl acrylate, t-butyl acrylate, and/or derivatives (such as anhydrides and imides) of unsaturated carboxylic acids, for example maleic anhydride and N-phenylmaleimide.

Preferred monomers Bl1.1 are selected from at least one of the monomers styrene and a-methylstyrene, preferred monomers Bl1.2 are selected from at least one of Monomers acrylonitrile, maleic anhydride and methyl methacrylate. Particularly preferred monomers are B.1.1.1 styrene and B.1.1.2 acrylonitrile.

Examples of graft bases B.1.2 suitable for the graft polymers B.1 are diene rubbers, EP(D)M rubbers, ie those based on ethylene/propylene and optionally diene, acrylate, polyurethane, silicone, chloroprene and ethylene/vinyl acetate -Rubber and silicone/acrylic composite rubber.

Preferred graft bases B.1.2 are diene rubbers, for example based on butadiene and isoprene, or mixtures of diene rubbers or copolymers of diene rubbers or mixtures thereof with other copolymerizable monomers (e.g. according to B.1.1.1 and B.1.1.2).

Pure polybutadiene rubber is particularly preferred as the graft base B.1.2.

Particularly preferred polymers B.1 are selected, for example, from copolymers of acrylonitrile-butadiene-styrene (also referred to as ABS polymer) or copolymers of methacrylate-butadiene-styrene (also referred to as MBS polymer), such as those described in DE OS 2 035 390 (=US Pat. No. 3,644,574) or in DE-OS 2,248,242 (=GB-PS 1,409,275) or in Ullmanns, Enzyklopädie der Technischen Chemie, Vol. 19 (1980), p. 280 et seq .

The graft copolymers B.1 are prepared by free-radical polymerization, for example by emulsion, suspension, solution or bulk polymerization, preferably by emulsion or bulk polymerization.

The gel fraction of the graft base B.1.2 is at least 30% by weight, preferably at least 40% by weight, in particular at least 60% by weight, based in each case on B.1.2 and measured as the insoluble fraction in toluene.

The gel content of the graft base B.1.2 is determined at 25° C. in a suitable solvent as the proportion insoluble in these solvents (M. Hoffmann, H. Kromer, R. Kuhn, Polymeranalytik I and II, Georg Thieme-Verlag, Stuttgart 1977).

Also particularly suitable graft rubbers are ABS polymers which are prepared by redox initiation using an initiator system of organic hydroperoxide and ascorbic acid according to US Pat. No. 4,937,285.

Since, as is known, the graft monomers are not necessarily completely grafted onto the graft base in the graft reaction, graft polymers are used according to the invention Bl also understood those products which are obtained by (co)polymerization of the graft monomers in the presence of the graft base and are also obtained during the work-up. Accordingly, these products can also contain free (co)polymer of the graft monomers, ie not chemically bonded to the rubber.

For crosslinking, monomers having more than one polymerizable double bond can be copolymerized. Preferred examples of crosslinking monomers are esters of unsaturated monocarboxylic acids having 3 to 8 carbon atoms and unsaturated monohydric alcohols having 3 to 12 carbon atoms, or saturated polyols having 2 to 4 OH groups and 2 to 20 carbon atoms, such as ethylene glycol dimethacrylate, allyl methacrylate ; polyunsaturated heterocyclic compounds such as trivinyl and triallyl cyanurate; polyfunctional vinyl compounds such as di- and trivinylbenzenes; but also triallyl phosphate and diallyl phthalate. Preferred crosslinking monomers are allyl methacrylate, ethylene glycol dimethacrylate, diallyl phthalate and heterocyclic compounds containing at least three ethylenically unsaturated groups. Particularly preferred crosslinking monomers are the cyclic monomers triallyl cyanurate, triallyl isocyanurate, triacryloylhexahydro-s-triazine, triallylbenzenes. The amount of crosslinked monomers is preferably from 0.02 to 5% by weight, in particular from 0.05 to 2% by weight, based on the graft base B.1.2. In the case of cyclic crosslinking monomers having at least three ethylenically unsaturated groups, it is advantageous to limit the amount to less than 1% by weight of the graft base B.1.2.

Examples of preferred "other" polymerizable, ethylenically unsaturated monomers which, in addition to the acrylic acid esters, can be used to prepare the graft base B.1.2 are acrylonitrile, styrene, α-methylstyrene, acrylamide, vinyl-C 1 -C 6 -alkyl ether, methyl methacrylate, butadiene. Preferred acrylate rubbers as the graft base B.1.2 are emulsion polymers which have a gel content of at least 60% by weight.

Further suitable graft bases according to B.1.2 are silicone rubbers with graft-active sites, as described in DE-OS 3,704,657, DE-OS 3,704,655, DE-OS 3,631,540 and DE-OS 3,631,539.

The rubber-free vinyl (co)polymers according to component B.2 are preferably rubber-free homo- and/or copolymers of at least one monomer from the group consisting of vinyl aromatics, vinyl cyanides (unsaturated nitriles), (meth)- Acrylic acid (Ci to C ₈ ) alkyl esters, unsaturated carboxylic acids and derivatives (such as anhydrides and imides) of unsaturated carboxylic acids.

(Co)polymers from B.2 are particularly suitable

B.2.1 10 to 100% by weight, preferably 50 to 99% by weight, more preferably 60 to 80% by weight, in particular 70 to 80% by weight, based in each case on the total weight of the (co)polymer B .2, at least one monomer selected from the group of vinylaromatics, such as styrene, a-methylstyrene, nuclear-substituted vinylaromatic maten, such as p-methylstyrene, p-chlorostyrene, and

B.2.2 0 to 90% by weight, preferably 1 to 50% by weight, more preferably 20 to 40% by weight, in particular 20 to 30% by weight, based in each case on the total weight of the (co)polymer B .2, at least one monomer selected from the group of vinyl cyanides, such as unsaturated nitriles such as acrylonitrile and methacrylonitrile, (meth)acrylic acid (Ci-Cx) - alkyl esters, such as methyl methacrylate, n-butyl acrylate, tert. -butyl acrylate, unsaturated carboxylic acids and derivatives of unsaturated carboxylic acids, such as maleic anhydride and N-phenylmaleimide.

These (co)polymers B.2 are resinous, thermoplastic and free from rubber. At least the copolymer of B.2.1 styrene and B.2.2 acrylonitrile and/or the homopolymer of B.2.1 styrene is particularly preferably present in said material.

Such (co)polymers B.2 are known and can be prepared by free-radical polymerization, in particular by emulsion, suspension, solution or bulk polymerization. The (co)polymers preferably have average molecular weights M _w (weight average, determined by GPC using polystyrene as the standard) between 15,000 and 250,000 g/mol, preferably in the range from 80,000 to 150,000 g/mol.

In addition to at least one polycarbonate-containing compound and at least one polystyrene-containing compound, said material of the pyrolysis material can also contain at least one polymer additive selected from flame retardants, anti-dripping agents, flame retardant synergists, smoke inhibitors, lubricants and mold release agents, nucleating agents, antistatic agents, conductivity additives, stabilizers (e.g. hydrolysis, Heat aging and UV stabilizers and transesterification inhibitors), flow promoters, phase compatibilizers, other components A and B different polymeric components (e.g. functional blend partners), fillers and reinforcing materials as well as dyes and pigments.

It was also found that an increased content of aromatic compound with at least two hydroxyl groups in the pyrolysis product can be obtained and thus recovered if the pyrolysis material contains a limited small amount of phosphorus-containing organic compounds or is even free of these compounds. A proportion of 0% by weight to at most 0.5% by weight of phosphorus, preferably from 0% by weight to at most, contributed by this total amount and based on the total weight of the pyrolysis material proved to be such a defined total amount of phosphorus-containing organic compound 0.1% by weight phosphorus, more preferably from 0% by weight to at most 0.05% by weight phosphorus, particularly preferably from 0% by weight to at most 0.01% by weight phosphorus. The technical effect resulting from this defined total amount could also be achieved for a pyrolysis material containing at least one polycarbonate-containing compound and a correspondingly limited total amount of phosphorus-containing, organic compound, and optionally also at least one polystyrene-containing compound.

A further embodiment of the method according to the invention is therefore a method which, according to step (a), is characterized in that the pyrolysis material contains at least one polycarbonate-containing compound and a defined total amount of phosphorus-containing, organic compound, so that, based on the total weight of the pyrolysis material, a proportion from 0% by weight to at most 0.5% by weight phosphorus, preferably from 0% by weight to at most 0.1% by weight phosphorus, more preferably from 0% by weight to at most 0.05% by weight. % phosphorus, more preferably from 0% by weight to at most 0.01% by weight phosphorus, is contributed by this total amount of phosphorus-containing organic compound and optionally at least one polystyrene-containing compound. It is further preferred if, for a simultaneous recovery of styrene and its derivatives, the pyrolysis material comprises at least material containing a mixture of polycarbonate-containing compound and polystyrene-containing compound and said total amount of phosphorus-containing, organic compound.

In a further embodiment, it has proven to be preferred according to the invention if the phosphorus-containing organic compound, which is limited in its amount is selected from phosphorus-containing organic compounds whose phosphorus has a formal oxidation state of +5.

It has also proven to be particularly preferred if the pyrolysis material is free from phosphorus-containing organic compounds in which at least one phosphorus atom has a formal oxidation state of +5.

Phosphorus-containing organic compounds of limited quantity are preferably selected from at least one compound from the group consisting of organic phosphoric acid esters, organic phosphonic acid esters, organic phosphazenes and phosphonate amines, in particular organic phosphoric acid esters and organic phosphonic acid esters. Said phosphorus-containing, organic compound is particularly preferably selected from at least one compound from the group consisting of organic phosphoric acid monoesters, organic phosphoric acid diesters, organic phosphoric acid triesters, and oligomeric phosphoric acid esters. Mixtures of several of these compounds can therefore also be used and limited in their amount.

The aforementioned phosphonate amines and phosphazenes, the amount of which is to be limited in the pyrolysis material in the preferred embodiment, can be, for example, those described in WO 00/00541 and WO 01/18105.

For the purposes of this invention, particularly preferred, phosphorus-containing, organic compounds to be limited in terms of their quantitative content are compounds of the general formula (IV) wherein

R ¹ , R ² , R ³ and R ⁴ , each independently optionally halogenated C 1 to C 8 alkyl, each optionally substituted by alkyl, preferably C 1 to C 4 alkyl, and/or halogen, preferably chlorine, bromine, C 5 to C 6 Cycloalkyl, C6 to C20 aryl or C7 to C12 aralkyl, n are independently 0 or 1, q 0 to 30 and

X is a polynuclear aromatic radical having 12 to 30 carbon atoms, or a linear or branched aliphatic radical having 2 to 30 carbon atoms, which can be OH-substituted and contain up to eight ether bonds.

R ¹ , R ² , R ³ and R ⁴ in the formula (IV) are preferably independently CI to Cd-alkyl, phenyl, naphthyl or phenyl-Cl-C4-alkyl. The aromatic groups R ¹ , R ² , R ³ and R ⁴ can in turn be substituted with halogen and/or alkyl groups, preferably chlorine, bromine and/or C1 to C4-alkyl. Particularly preferred aryl radicals are cresyl, phenyl, xylenyl, propylphenyl or butylphenyl and the corresponding brominated and chlorinated derivatives thereof.

X in the formula (IV) is preferably a polynuclear aromatic radical having 12 to 30 carbon atoms. This is preferably derived from aromatic compounds having at least two hydroxyl groups of the general formula (I). n in the formula (IV), independently of one another, can be 0 or 1, preferably n is 1. q is integer values from 0 to 30, preferably 0 to 20, particularly preferably 0 to 10, in the case of mixtures average values from 0.8 to 5.0, preferably from 1.0 to 3.0, more preferably from 1.05 to 2.00, and most preferably from 1.08 to 1.60.

X in formula (IV) particularly preferably represents or their chlorinated or brominated derivatives, in particular X is derived from bisphenol A or diphenylphenol. X is particularly preferably derived from bisphenol A. Phosphorus compounds of the formula (IV) are, in particular, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, diphenyl cresyl phosphate, diphenyloctyl phosphate, diphenyl-2-ethylcresyl phosphate, tri(isopropylphenyl) phosphate, and bisphenol A bridged oligophosphate. The use of oligomeric phosphoric acid esters of the formula (IV) which are derived from bisphenol A is particularly preferred.

Bisphenol-A-based oligophosphate of the formula (IVa) is most preferably used as the phosphorus-containing organic compound with a limited content.

The aforementioned phosphorus-containing organic compounds are known (cf. e.g. EP-A 0 363 608, EP-A 0 640655) or can be prepared in an analogous manner using known methods (e.g. Ullmanns Enzyklopädie der Technischen Chemie, Vol. 18, p. 301 1979; Houben-Weyl, Methods of Organic Chemistry, Vol. 12/1, p. 43; Beilstein, Vol. 6, p. 177).

Mixtures of organic phosphoric acid esters with different chemical structures and/or with the same chemical structure and different molecular weights can also be used, for example, as phosphorus-containing organic compounds suitable according to the invention and to be limited in their quantitative content.

When using oligomeric phosphoric acid esters as the phosphorus-containing organic compound of limited quantity, mixtures with the same structure and different chain lengths are preferably used, the q-value given in the formulas (IV) and (IVa) being the mean q- value trades. The mean q value is determined by determining the composition of the phosphorus compound (molecular weight distribution) using high pressure liquid chromatography (HPLC) at 40° C. in a mixture of acetonitrile and water (50:50) and calculating the mean values for q from this . In a preferred embodiment, the composition contains pentaerythritol tetrastearate as a mold release agent.

The dosing and processability of the pyrolysis material in the pyrolysis of the method according to the invention can be simplified by said pyrolysis material in step (a) additionally containing at least one filler in addition to said material. Said filler preferably does not catalyze the thermal decomposition of polycarbonate as part of pyrolysis. It is in turn particularly preferred if the filler is at least one metal oxide which is not catalytically active in the pyrolysis of the thermal decomposition of polycarbonate, which is preferably selected from SiCk.

The polycarbonate material is preferably mixed with a filler, e.g. sand, which simplifies continuous process management of the method according to the invention. In particular, sticking of said material in the reactor and in the supply of the dosing device to the reactor is avoided. In one embodiment, the filler and said material are added to the pyrolysis material as a mixture in a volume ratio of filler to said material of at least 0.1:1 to 10:1.

Catalysts can be used to make the pyrolysis process more selective and efficient. More effective and more selective decomposition is obtained if, in one embodiment of the method according to the invention, said pyrolysis material introduced in step (a) contains, in addition to said material, at least one catalyst influencing the decomposition reaction of said material. A suitable catalyst can lower the pyrolysis temperature, reduce the product range to the desired products and, if necessary, minimize coking. Inexpensive catalysts are preferred for an efficient process. These can be, for example, naturally occurring materials such as inorganic salts, refractory oxides, minerals and engineered rocks that can optionally be ion exchanged in a simple ion exchange process as they do not require extensive synthesis. They are readily available and are therefore relatively cheap. On the other hand, synthetic catalysts such as zeolites (e.g. of the ZSM-5, A, X,Y, etc. type) are an example of catalysts which, although effective, are not cheap as they have to be specially manufactured.

In addition to the function as a catalyst, catalysts can also simplify the dosing and processability of the pyrolysis material in pyrolysis. If a catalyst is used, the amount of filler used can be reduced in this case. In one embodiment, the total amount of filler and catalyst in the Ratio to the amount of said material in a volume ratio of at least 0.1 to 1 to 10 to 1 fed to the pyrolysis material as a mixture.

In the pyrolysis reaction, preferably at least one catalyst is selected from the group formed by alkaline inorganic materials, more preferably from the group of naturally occurring materials defined above. These inorganic materials can be refractory oxides. Refractory oxides are metal oxides that are stable at high temperatures from 300°C to 700°C. Such catalyst oxides include the oxides of aluminum, magnesium, zirconium, titanium, chromium, zinc, tin and other metals or combinations of alumina with magnesium oxide and/or calcium oxide. Crystalline inorganic materials include aluminosilicates, silicoaluminophosphates, silicalite, spinels and other natural zeolites and clays. At least one compound from the group consisting of inorganic salts, minerals, metal oxides, mixed oxides, clays and zeolites is therefore particularly suitable as said catalyst.

Both homogeneous and heterogeneous catalysts can be used. However, preferred embodiments of the process according to the invention are those in which the catalyst is a heterogeneous catalyst. It has proven to be advantageous if the catalyst is preferably introduced into the reactor in the form of solid particles (in particular in the form of a granular mixture). The heterogeneous catalyst used particularly preferably has an average particle size of its solid particles, in particular its loose, solid particles of the granular mixture, an average diameter X o (volume average) of 0.01 mm to 5 cm, preferably 0.1 mm to 5 cm , on. The mean particle size diameter X o is determined by sieving or by means of a particle size analyzer Camsizer from Retsch.

When using a heterogeneous catalyst, it has proven to be particularly suitable within the scope of a further preferred embodiment if the catalyst particles have a smaller or the same particle size as the particles of said material. It is therefore preferred if the mean particle size of the catalyst present in the pyrolysis material corresponds at most to the mean particle size of the said material present therein.

As a particularly preferably suitable said catalyst, the pyrolysis material can contain at least one basic catalyst. If it is a solid, basic catalyst, the number and strength of the basic centers of the catalyst can be determined using Fourier transform infrared spectroscopy and Temperature Programmed Desorption of CO2 (TPD-C02), or using common titrimetric methods.

If a catalyst is added, it can be admixed with the filler, coated onto the filler, or used as a substitute for the filler.

Since the catalyst used in the process according to the invention tends to form deposits of coke and other carbon residues, when using catalyst it is preferred to use a reactor which allows the catalyst to be discharged and continuously regenerated easily and preferably. Therefore, the use of a continuous stirred tank reactor (CSTR), a moving bed, a screw reactor, a screw conveyor reactor, an entrained flow reactor, a rotating cone reactor, or a fluidized bed reactor is preferred over the use of a fixed bed reactor.

The (e.g. by coking) deactivated catalyst is in the pyrolysis residue and can be fed into a regenerator after the pyrolysis residue has been discharged from the reactor and added to the pyrolysis material of step (b) to be introduced into the pyrolysis reactor after regeneration. Reactors that allow for short contact time, intensive mixing of the components in the feedstream with the catalyst, and continuous recycle of the regenerated catalyst to the pyrolysis zone are most preferred. Since this is the case with a screw reactor, rotary kiln or fluidized bed, these reactors are particularly preferred.

The pyrolysis material introduced into the reactor in step (a) is at least partially decomposed in step (b) with the formation of pyrolysate and pyrolysis residue.

After being introduced into the reactor, the pyrolysis material is heated to a temperature in the range from 300.degree. C. to 700.degree. A particularly successful improvement in the result of the method according to the invention can be achieved if, within the scope of one embodiment, the pyrolysis material introduced is heated to 300° C. to 700° C. and after this target temperature has been reached, the residence time of the correspondingly temperature-controlled pyrolysis material is increased until the resulting pyrolysis residue is discharged 1 second to 2 hours, preferably between 2 minutes and 60 minutes, and during which time the temperature and the content of oxygen gas in the reactor are the values defined in step (b). If the pyrolysis material contains a catalyst in the process according to the invention, this catalyst is in the pyrolysis residue that is discharged. As part of a further embodiment of the method, the discharged pyrolysis residue is therefore fed to a regeneration step of the catalyst contained therein, as described above.

Regardless of this, good results can be achieved if the removal of the pyrolysate from the reactor that takes place in step (b) is ensured by a gas stream conducted through the reactor or by suction and more preferably by allowing the pyrolysate to remain there as a period of time between the point in time at which the said material introduced into the reactor in step (a) and the point in time at which the pyrolysate is discharged is 0.1 seconds to 10 seconds, preferably between 0.5 seconds and 5 seconds, particularly preferably 0.5 seconds to 2 seconds.

If a gas stream is passed through the reactor for this purpose, an inert gas, preferably selected from nitrogen, argon, CO 2 , NO or a mixture thereof, is particularly suitable as the gas for this gas stream.

If a gas stream is used to discharge the pyrolysate, it is preferred according to the invention if the flow velocity of the gas stream in the reactor is in the range from 0.01 m/s to 20 m/s as superficial velocity. If a fixed-bed reactor is chosen as the reactor, it is preferred according to the invention if the flow rate of the gas stream in the reactor is in the range from 0.03 m/s to 1 m/s as the superficial velocity. If a fluidized bed reactor is selected as the reactor, it is preferred according to the invention that the superficial velocity of the gas stream in the reactor is in the range from 0.5 m/s to 2 m/s. If an entrained-flow reactor is selected as the reactor, it is preferred according to the invention that the superficial velocity of the gas stream in the reactor is in the range from 5 m/s to 20 m/s.

As the conditions for the decomposition in the pyrolysis in step (b) according to the invention, the temperature in the reactor is 300 to 700° C. and the amount of oxygen gas in the reactor is from 0 to 2.0% by volume based on the total volume in the reactor gases.

To set the amount of oxygen gas according to the invention, the reactor filled with said material of said pyrolysis material is filled with inert gas, in particular with nitrogen, argon, CO2, NO or a mixture thereof. The inert gas can also of Oxygen gas mixed with various reactive gases, in particular selected from methane, gaseous H2O, hydrogen gas or mixtures thereof.

In order to minimize the introduction of oxygen gas through the introduction of the pyrolysis material into the reactor, the pyrolysis material can be freed from oxygen gas before it is introduced in step (a), e.g. by driving out the oxygen gas by means of stripping with a stripping gas, e.g. in one upstream of the reactor storage container. For example, inert gas, in particular nitrogen, argon, CO2, NO, mixtures thereof, could be used as a stripping gas from above or below in the storage container (preferably from above) via a frit into the container to the pyrolysis material in order to drive out the oxygen gas.

In a preferred embodiment of the method according to the invention, the temperature in step (b) is from 350° C. to 650° C., preferably between 400° C. and 650° C., particularly preferably from 420° C. to 600° C., very particularly preferably from 450ºC to 580ºC.

In a further preferred embodiment of the process according to the invention, the amount of oxygen gas in the reactor in step (b) is at most 0.5% by volume, preferably 0.1% by volume, based in each case on the total volume of the gases in the reactor.

In a very preferred embodiment of the method according to the invention, the temperature in step (b) is firstly from 350° C. to 650° C., preferably between 400° C. and 650° C., particularly preferably from 420° C. to 600° C., very particularly preferably from 450° C. to 580° C., and secondly the amount of oxygen gas in the reactor is at most 0.5% by volume, preferably 0.1% by volume, in each case based on the total volume of the gases present in the reactor.

A preferred embodiment of the method provides a continuous process control. For this, at least steps (a) and (b) run simultaneously within the framework of a continuous process control.

The pyrolysis product obtained in step (c) can be worked up using standard separation methods and thereby (i) at least one aromatic compound having at least two hydroxyl substituents, preferably bisphenol A, and (ii) at least one aromatic compound having at least one vinyl substituent, preferably from styrene. Standard BPA is obtained by crystallization of the BPA/phenol adduct or by precipitation in toluene. Other possibilities are the distillation or extraction of the BPA from the pyrolysis product mixture. Other products like styrene or phenol can be separated by distillation. The method according to the invention can be carried out with the aid of an appropriately configured pyrolysis device. A further object of the invention is therefore a pyrolysis device for producing pyrolysate from pyrolysis material, containing at least one dosing device for feeding in pyrolysis material, at least one heatable reactor for the pyrolysis, and at least one pyrolysate collector, characterized in that said heatable reactor for the Pyrolysis contains at least one heater that can be used to control the temperature of the reactor to a temperature of 300° C. to 700° C., and contains at least one inlet for pyrolysis material and contains at least one outlet for pyrolysate that is different therefrom; and

Metering device and heatable reactor for the pyrolysis are arranged and designed relative to each other in such a way that the metering device is connected via at least one feed line to an inlet for pyrolysis material of said reactor; and the heatable reactor for the pyrolysis and the pyrolysate collector are in fluid communication with one another, so that the preferably gaseous pyrolysate can be discharged from said pyrolysate outlet and the pyrolysate discharged can be introduced into the pyrolysate collector; and at least one pyrolysate collector contains at least one cooling device conditioned to a temperature below 300°C, which is installed in said collector to lower the temperature of the pyrolysate fed out of said reactor to less than 300°C to form a pyrolysis product selected from pyrolysate condensate, pyrolysate resublimate or a mixture thereof, and comprising at least one container for collecting and discharging the product of pyrolysis obtained with cooling; and at least one dosing device for feeding in pyrolysis material, at least one heatable reactor for the pyrolysis, and at least one pyrolysate collector are arranged and configured in relation to one another in such a way that they can be operated simultaneously.

A heating element, e.g. heating coil or heating plates, for example, or a device for heating a gas stream and for introducing the heated gas stream into the reactor can be used to heat the heatable reactor.

In the context of a preferred embodiment, the reactor additionally contains at least one connection to a gas source, with a gas flow via a regulator, for example a valve in the reactor, preferably at a superficial flow rate of between 0.01 m/s to 20 m/s, through the reactor into the pyrolysate collector. If a fixed-bed reactor is chosen as the reactor, it is preferred according to the invention if the flow rate of the gas stream in the reactor is in the range from 0.03 m/s to 1 m/s as the superficial velocity. If a fluidized bed reactor is selected as the reactor, it is preferred according to the invention that the superficial velocity of the gas stream in the reactor is in the range from 0.5 m/s to 2 m/s. If an entrained-flow reactor is selected as the reactor, it is preferred according to the invention that the superficial velocity of the gas stream in the reactor is in the range from 5 m/s to 20 m/s. The gas stream from the gas source can, for example, be heated by the heater before it is introduced into the reactor, as described above.

The pyrolysate collector of the device according to the invention preferably contains a cooling device usable in said collector for lowering the temperature of the pyrolysate fed out of said reactor to less than 50°C (more preferably to less than 30°C) to form pyrolysis product. Cooling units that work according to the heat exchanger principle are particularly suitable for this.

According to the invention, a “fluid connection” is a part of the device that connects parts of the system to one another and through which a substance that can be present in any physical state can be transported from one part of the system to the next, for example a supply line in the form of a pipe.

Another object of the invention is the use of a pyrolysis device of the aforementioned subject of the invention for the recovery of compounds containing in the production of polycarbonate used, organic compound having at least two hydroxyl groups with simultaneous recovery of styrene used in the production of polystyrene-containing compound, by simultaneous pyrolysis of said polycarbonate-containing compound and said polystyrene-containing compound.

In a preferred embodiment of the use, the pyrolysis device is used for the recovery of bisphenol-A used in the production of polycarbonate-containing compound, in addition to said simultaneous styrene recovery.

The method according to the invention and the device according to the invention contribute to the solution of the object set out above and, after step (c) of the method, deliver as a pyrolysis product a composition containing at least one based on the total weight of the composition

(i) between 25 and 80% by weight of a total amount of at least one aromatic compound having at least two hydroxyl groups, preferably according to the general formula (I) above, very particularly preferably bisphenol-A,

(ii) more than 1% by weight of a total amount of at least one aromatic compound with exactly one hydroxyl group, preferably phenol,

(iii) more than 1.5% by weight of a total amount of at least one aromatic compound having at least one vinyl substituent, preferably styrene or a-methyl styrene, the proportions by weight of components (i) to (iii) together with the Add weight proportions of other ingredients of the composition to 100% by weight.

It is preferred if the composition contains a small amount of high-boiling components. A preferred embodiment of the above composition therefore contains between 0.5 and 10.0% by weight of a total amount of at least one organic compound without a hydroxyl group with a boiling point at 1013 mbar of at least 300°C.

As a likewise preferred embodiment, the composition contains between 25 and 80% by weight of a total amount of aromatic compounds having at least two hydroxyl groups selected from 4,4'-dihydroxydiphenyl, bisphenol-A, 2,4-bis(4-hydroxyphenyl) -2-methylbutane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 4,4'-dihydroxydiphenylsulfide, 4,4' -Dihydroxydiphenylsulfone and their di- and tetrabrominated or chlorinated derivatives such as 2,2-bis(3-chloro-4-hydroxyphenyl)propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane or 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, or mixtures thereof.

Furthermore, it is additionally preferred if the aforementioned features of the aforementioned embodiments of components (i) and (ii) of the composition are combined.

In summary but without limitation, the following aspects 1 to 35 of the invention apply as further embodiments:

1. Process for pyrolysis, comprising at least the following steps: (a) introducing pyrolysis material, at least comprising material containing a mixture of polycarbonate-containing compound and polystyrene-containing compound, into a reactor;

(b) decomposition of at least the material of the pyrolysis material introduced in step (a) in the reactor at a temperature of 300° C. to 700° C. to obtain product in the gas phase as pyrolysate and pyrolysis residue not in the gas phase, wherein

(i) during said decomposition, the amount of oxygen gas in the reactor is at most 2.0% by volume based on the total volume of gases in the reactor, and

(ii) during said decomposition, the pyrolyzate is discharged from the reactor, and

(iii) said pyrolysis residue is discharged from the reactor;

(c) cooling the discharged pyrolysate to a temperature of less than 300°C to obtain pyrolysis product selected from pyrolysate condensate, pyrolysate sublimate or a mixture thereof;

(d) optional processing of the pyrolysis product. Process according to aspect 1, characterized in that the reactor is selected from continuous stirred tank reactor (CSTR), fixed bed reactor, fluidized bed reactor, screw reactor, screw conveyor reactor, entrained flow reactor, entrained flow reactor, rotary tube reactor, fluidized bed reactor, blade reactor, in particular is selected from continuous stirred tank reactor (CSTR), fixed bed reactor (in particular with continuous bed exchange (shaft reactor) with internal heat exchanger tubes), a screw reactor, a screw conveyor reactor, an entrained flow reactor, rotary tube reactor or fluidized bed reactor. Process according to one of aspects 1 or 2, characterized in that the temperature in step (b) is from 350°C to 650°C, preferably between 400°C and 650°C, particularly preferably from 420°C to 600°C, most preferably from 450°C to 580°C. Method according to one of the preceding aspects, characterized in that the pyrolysis material introduced is heated to 300°C to 700°C and, after this target temperature has been reached, the residence time of the correspondingly temperature-controlled pyrolysis material up to the time when its resulting pyrolysis residue is discharged is preferably 1 second to 2 hours between 2 minutes and 60 minutes. 5. The method according to any one of the preceding aspects, characterized in that the evacuation of the pyrolysate from the reactor is ensured by a gas stream guided through the reactor or by suction and preferably thereby a residence time of the pyrolysate as a period between the time of introduction of said in the step (a) material introduced into the reactor and the time at which the resulting pyrolysate is discharged is 0.1 seconds to 10 seconds, preferably between 0.5 seconds and 5 seconds, particularly preferably 0.5 seconds to 2 seconds.

6. The method according to any one of the preceding aspects, characterized in that the evacuation of the pyrolysate from the reactor is ensured by a guided through the reactor gas stream, the flow rate in the reactor as superficial velocity in the range of 0.01 m / s to 20 m / s lies.

7. The method according to any one of the preceding aspects, characterized in that the pyrolyzate is present in the reactor in the gas phase.

8. The method according to any one of the preceding aspects, characterized in that the pyrolysis residue is solid in the reactor.

9. The method according to any one of the preceding aspects, characterized in that at least steps (a) and (b) run simultaneously as part of a continuous process control.

10. The method according to any one of the preceding aspects, characterized in that in step (b) the amount of oxygen gas in the reactor is at most 0.5% by volume, preferably 0.1% by volume, based in each case on the total volume of the gases in the reactor amounts to.

11. Method according to one of the preceding aspects, characterized in that the reactor filled with said material is filled with inert gas, in particular with nitrogen, argon, CO2, NO or mixtures thereof.

12. The method according to aspect 11, characterized in that reactive gases different from oxygen gas are added to the inert gas, in particular selected from methane, gaseous H2O, hydrogen gas or mixtures thereof.

13. The method according to any one of the preceding aspects, characterized in that the polycarbonate-containing compound is at least one compound containing at least ten structural units *-O-C-O-*, where * represents a valence of the polymer backbone O marks. A method according to any one of the preceding aspects, characterized in that the polystyrene-containing compound is at least one polymer containing at least ten repeating units of the formula

*-CR ¹ Ph-CH ₂ -* contains, where * denotes a valence of the repeating unit of the polymer backbone, R ¹ represents a hydrogen atom or a methyl group and Ph represents an optionally containing at least one group selected from (C 1 to C 4 )alkyl , Halogen atom (particularly chlorine), substituted phenyl group. Process according to one of the preceding aspects, characterized in that the polycarbonate-containing compound is at least one compound obtained by reacting (i) at least one aromatic compound having at least two hydroxyl groups, preferably bisphenol A, and (ii) phosgene or diphenyl carbonate . Method according to one of the preceding aspects, characterized in that the pyrolysis material, in particular the material, contains a limited total amount of phosphorus-containing, organic compound, so that, based on the total weight of the pyrolysis material, a proportion of 0% by weight to at most 0.5% by weight % phosphorus, preferably from 0% by weight to at most 0.1% by weight phosphorus, more preferably from 0% by weight to at most 0.05% by weight phosphorus, particularly preferably from 0% by weight up to a maximum of 0.01% by weight of phosphorus, is introduced into the pyrolysis material by this total amount of phosphorus-containing organic compound. The method according to aspect 16, characterized in that the phosphorus contained in said phosphorus-containing organic compound has a formal oxidation state of +5. Method according to one of aspects 16 or 17, characterized in that said phosphorus-containing organic compound is selected from at least one compound from the group formed from organic phosphoric acid esters, organic phosphonic acid esters, organic phosphazenes and phosphonate amines, in particular from organic phosphoric acid esters and organic phosphonic acid esters. Process according to one of aspects 16 to 18, characterized in that the phosphorus-containing organic compound is selected from at least one compound of the general formula (IV) wherein

R ¹ , R ² , R ³ and R ⁴ , independently of one another, represent optionally halogenated CI to C8-alkyl, optionally substituted by alkyl, preferably CI to C4-alkyl, and/or halogen, preferably chlorine, bromine, C5 to C6- Cycloalkyl optionally substituted by alkyl, preferably C1 to C4-alkyl, and/or halogen, preferably chlorine, bromine, C6 to C20-aryl or optionally substituted by alkyl, preferably C1 to Cd-alkyl, and/or halogen, preferably chlorine, bromine , substituted C7 to C12 aralkyl, n is independently 0 or 1, preferably 1, q is a number from 0 to 30 and

X is a mono- or polynuclear aromatic radical having 6 to 30 carbon atoms, or a linear or branched aliphatic radical having 2 to 30 carbon atoms, which may be OH-substituted and contain up to 8 ether bonds. Method according to one of aspects 16 to 19, characterized in that the pyrolysis material according to step (a) contains at least one polycarbonate-containing compound and a limited total amount of phosphorus-containing, organic compound, so that, based on the total weight of the pyrolysis material, a proportion of 0 wt % to at most 0.5% by weight phosphorus, preferably from 0% by weight to at most 0.1% by weight phosphorus, more preferably from 0% by weight to at most 0.05% by weight phosphorus , particularly preferably from 0% by weight to at most 0.01% by weight of phosphorus, is introduced by this total amount of phosphorus-containing organic compound and optionally contains at least one polystyrene-containing compound. 21. Method according to one of the preceding aspects, characterized in that said material is introduced into the reactor in the form of solid particles, in particular in the form of a granular mixture.

22. The method according to aspect 21, characterized in that the solid particles, in particular the loose, solid particles of the granular mixture, of said material introduced into the reactor have an average diameter X o (volume average) of 0.01 mm to 5 cm.

23. The method according to any one of the preceding aspects, characterized in that said pyrolysis material in step (a) also contains at least one filler in addition to said material.

24. The method according to aspect 23, characterized in that the filler is at least one metal oxide which is not catalytically active in the pyrolysis of polycarbonate, which is preferably selected from SiCk.

25. The method according to any one of the preceding aspects, characterized in that said pyrolysis material in step (a) contains, in addition to said material, at least one catalyst influencing the decomposition reaction of said material.

26. The method according to aspect 25, characterized in that the catalyst is at least one compound from the group consisting of inorganic salts, minerals, metal oxides, mixed oxides, clays, zeolites.

27. The method according to any one of aspects 25 or 26, characterized in that the catalyst is a basic catalyst.

28. The method according to any one of aspects 25 to 27, characterized in that the catalyst is a heterogeneous catalyst.

29. The method according to any one of aspects 1 to 28, characterized in that said pyrolysis material contains said material in a total amount of 10.0 to 80.0% by weight, more preferably 30.0 to 70.0% by weight, based on its total weight. -%, contains.

30. Pyrolysis device for the production of pyrolysate from pyrolysis material, containing at least one metering device for feeding in pyrolysis material, at least one heatable reactor for the pyrolysis, and at least one pyrolysate collector, characterized in that said heatable reactor for the pyrolysis contains at least one heating element which can be used to control the temperature of the reactor to a temperature of 300°C to 700°C, and contains at least one inlet for pyrolysis material and at least one different outlet for pyrolysate; and

Metering device and heatable reactor for the pyrolysis are arranged and designed relative to each other in such a way that the metering device is connected via at least one feed line to an inlet for pyrolysis material of said reactor; and the heatable reactor for the pyrolysis and the pyrolysate collector are in fluid communication with one another, so that the preferably gaseous pyrolysate can be discharged from said pyrolysate outlet and the pyrolysate discharged can be introduced into the pyrolysate collector; and at least one pyrolysate collector contains at least one cooling device conditioned to a temperature below 300°C, which is installed in said collector to lower the temperature of the pyrolysate led out of said reactor to less than 300°C with the formation of pyrolysis product selected from pyrolysate condensate, pyrolysate sublimate or a mixture thereof, and comprising at least one container for collecting and discharging the product of pyrolysis obtained with cooling; and at least one dosing device for feeding in pyrolysis material, at least one heatable reactor for the pyrolysis, and at least one pyrolysate collector are arranged and configured in relation to one another in such a way that they can be operated simultaneously. Use of a pyrolysis device according to aspect 30 for the recovery of organic compound having at least two hydroxyl groups used in the production of polycarbonate-containing compounds while simultaneously recovering styrene used in the production of polystyrene-containing compound, by simultaneous pyrolysis of said polycarbonate-containing compound and said Polystyrene-containing compound. Use according to aspect 31, characterized in that the pyrolysis device is used for the recovery of bisphenol-A used in the production of polycarbonate-containing compound. 33. Composition containing at least one based on the total weight of the composition

(i) between 25 and 80% by weight of a total amount of at least one aromatic compound having at least two hydroxyl groups, preferably bisphenol-A,

(iii) greater than 1.5% by weight of a total of at least one aromatic compound having at least one vinyl substituent, preferably styrene or α-methylstyrene, the weight parts within the weight part ranges of (i) to (iii) being so selected be such that the sum of the selected proportions by weight from (i) to (iii) together with the proportions by weight of other ingredients of the composition is 100% by weight. 34. The composition according to aspect 33, characterized in that it is the

Composition is a pyrolysis product.

35. A composition according to aspect 34, characterized in that the composition is a pyrolysis product obtained in a process according to any one of aspects 1 to 29.

E x a m p e s

Example 1 (according to the invention):

The pyrolysis of polycarbonate/ AB S-Blend Bayblend ^® FC 85 from Covestro Deutschland AG (Leverkusen, Germany) (hereinafter referred to as PC-Blend) (free of phosphorus-containing, organic compounds) was carried out in a N2-flow fixed-bed reactor at 500 °C carried out. The polycarbonate was introduced into the reactor in 5 Al2O3 crucibles with holders, each containing 2 g. The residence time of the polycarbonate blend was 30 minutes. The flow rate of the gas stream (superficial tube velocity) in the reactor was 0.07 m/s. Two condensers were located behind the reactor in order to separate and collect the liquid components from the resulting pyrolysis product. The resulting coke content of the pyrolysis residue was determined by weighing the crucible after pyrolysis. The gas after the 2 condensers was characterized by GC. The components in the pyrolysis product, which occurs as an oil, were determined using GC-FID. An Agilent 7890A with a Supelco SPB 50 column was used for this. The pyrolysis oil was diluted with acetone 1:50 or 1:100.

Example 2 (not according to the invention):

The pyrolysis of polycarbonate/AB S-Blend ^Bayblend® FC 85 from Covestro Deutschland AG was carried out at 800° C. in a fixed bed reactor through which N2 flowed. The PC was introduced into the reactor in 5 Al2O3 crucibles with holders, each containing 2 g. The residence time of the PC blend was 30 min. The flow rate of the gas stream (superficial velocity) in the reactor was 0.07 m/s. Two condensers were located behind the reactor in order to separate and collect the liquid components from the resulting pyrolysis product. The resulting coke content of the pyrolysis residue was determined by weighing the crucible after pyrolysis. The gas after the 2 condensers was characterized by GC. The components in the pyrolysis product obtained as an oil were determined using GC-FID according to the analytical method described in Example 1. Result as proportions based on parts by weight of PC blend used:

Pyrolysis Gas Coke other Toluene* Ethyl- Styrene* Phenol* 4-tert- Phthal- BPA*

Temperature Components* benzene* butyl acid*

Phenol*

500°C 7.5 10.8 23.3 0.3 0.5 7.8 11.9 0.2 0.3 34.5

(Ex.l)

800°C 9.4 7.9 19.8 0.5 0.8 11.5 20.7 0.3 0.1 18.2

(Ex. 2,

Comparison)

* denotes components of the pyrolysis product

Claims

P atentClaims

A method of pyrolysis comprising at least the following steps

(iii) said pyrolysis residue is discharged from the reactor;

(d) optional processing of the pyrolysis product.

2. The method according to claim 1, characterized in that the temperature in step (b) from 350 ° C to 650 ° C, preferably between 400 ° C and 650 ° C, particularly preferably from 420 ° C to 600 ° C, very particularly preferably from 450°C to 580°C.

3. The method according to any one of the preceding claims, characterized in that the pyrolysis material introduced is temperature-controlled to 300°C to 700°C and after this target temperature has been reached, the dwell time of the correspondingly temperature-controlled pyrolysis material until the point at which its resulting pyrolysis residue is discharged is 1 second to 2 hours , preferably between 2 minutes and 60 minutes.

4. The method according to any one of the preceding claims, characterized in that the evacuation of the pyrolysate from the reactor is ensured by a gas flow guided through the reactor or by suction and preferably thereby a residence time of the pyrolysate as a period between the time of introduction of said in the step (a) the material introduced into the reactor and the time at which it was discharged resulting pyrolysates is 0.1 seconds to 10 seconds, preferably between 0.5 seconds and 5 seconds, particularly preferably 0.5 seconds to 2 seconds.

5. The method according to any one of the preceding claims, characterized in that the evacuation of the pyrolysate from the reactor is ensured by a guided through the reactor gas stream whose flow rate in the reactor as superficial velocity in the range of 0.01 m / s to 20 m / s lies.

6. The method according to any one of the preceding claims, characterized in that at least steps (a) and (b) run simultaneously in a continuous process control.

7. The method according to any one of the preceding claims, characterized in that in step (b) the amount of oxygen gas in the reactor is at most 0.5% by volume, preferably 0.1% by volume, based in each case on the total volume of the gases in the reactor amounts to.

8. The method according to any one of the preceding claims, characterized in that the reactor filled with said material is filled with inert gas, in particular with nitrogen, argon, CO2, NO or mixtures thereof.

9. The method according to any one of the preceding claims, characterized in that the polycarbonate-containing compound is at least one compound containing at least ten structural units *-O-C-O-*, where * represents a valency of the polymer backbone

O marks.

10. The method according to any one of the preceding claims, characterized in that the polystyrene-containing compound is at least one polymer having at least ten repeating units of the formula

*-CR ¹ Ph-CH ₂ -* contains, where * denotes a valence of the repeating unit of the polymer backbone, R ¹ represents a hydrogen atom or a methyl group and Ph represents an optionally containing at least one group selected from (C 1 to C 4 )alkyl , Halogen atom (particularly chlorine), substituted phenyl group.

11. The method according to any one of the preceding claims, characterized in that the polycarbonate-containing compound is at least one compound by Reaction of (i) at least one aromatic compound having at least two hydroxyl groups, preferably bisphenol A, and (ii) phosgene or diphenyl carbonate was obtained.

12. The method according to any one of the preceding claims, characterized in that the pyrolysis material, in particular the material, contains a defined total amount of phosphorus-containing, organic compound, so that, based on the total weight of the pyrolysis material, a proportion of 0 wt .-% to at most 0. 5% by weight phosphorus, preferably from 0% by weight to at most 0.1% by weight phosphorus, more preferably from 0% by weight to at most 0.05% by weight phosphorus, particularly preferably from 0% by weight -% up to a maximum of 0.01% by weight of phosphorus, is introduced into the pyrolysis material by this total amount of phosphorus-containing organic compound.

13. The method according to claim 12, characterized in that the phosphorus contained in said phosphorus-containing organic compound has a formal oxidation state of +5.

14. The method according to any one of claims 12 or 13, characterized in that said phosphorus-containing, organic compound is selected from at least one compound from the group formed from organic phosphoric acid esters, organic phosphonic acid esters, organic phosphazenes and phosphonate amines, in particular from organic phosphoric acid esters and organic phosphonic acid esters.

15. The method according to any one of claims 12 to 14, characterized in that the phosphorus-containing, organic compound is selected from at least one compound of the general formula (IV) wherein

R ¹ , R ² , R ³ and R ⁴ , independently of one another, represent optionally halogenated CI to C8-alkyl, optionally substituted by alkyl, preferably CI to C4-alkyl, and/or halogen, preferably chlorine, bromine, C5 to C6- Cycloalkyl, optionally replaced by alkyl, preferably C1 to C4-alkyl, and/or halogen, preferably chlorine, bromine, C6 to C20 aryl or optionally substituted by alkyl, preferably C1 to Cd-alkyl, and/or halogen, preferably chlorine, bromine, C7 to C12 aralkyl, n is independently 0 or 1, preferably 1, q is a number from 0 to 30 and

X is a mono- or polynuclear aromatic radical having 6 to 30 carbon atoms, or a linear or branched aliphatic radical having 2 to 30 carbon atoms, which may be OH-substituted and contain up to 8 ether bonds.

16. The method according to any one of the preceding claims, characterized in that said material is introduced into the reactor in the form of solid particles, in particular in the form of a granular mixture.

17. The method according to any one of the preceding claims, characterized in that said pyrolysis material in step (a) also contains at least one filler in addition to said material.

18. The method according to any one of claims 1 to 17, characterized in that said pyrolysis material contains said material in a total amount of 10.0 to 80.0% by weight, more preferably 30.0 to 70.0% by weight, based on its total weight. -%, contains.

19. Pyrolysis device for producing pyrolysate from pyrolysis material, containing at least one dosing device for feeding in pyrolysis material, at least one heatable reactor for the pyrolysis, and at least one pyrolysate collector, characterized in that said heatable reactor for the pyrolysis contains at least one heating element, which can be used to control the temperature of the reactor to a temperature of 300° C. to 700° C., and contains at least one inlet for pyrolysis material and contains at least one different outlet for pyrolysate; and the dosing device and the heatable reactor for the pyrolysis are arranged and designed relative to one another in such a way that the dosing device is connected via at least one feed line to an inlet for pyrolysis material of the said reactor; and the heatable reactor for the pyrolysis and the pyrolysate collector are in fluid communication with one another, so that the preferably gaseous pyrolysate can be discharged from said outlet for pyrolysate and the introduction of the extracted pyrolysate into the pyrolysate collector is possible; and at least one pyrolysate collector includes at least one cooling device, controlled to a temperature below 300°C, installed in said collector to lower the temperature of the pyrolysate discharged from said reactor to less than

300°C to form pyrolysis product selected from pyrolysate condensate, pyrolysate sublimate or a mixture thereof, and containing at least one container for collecting and discharging the pyrolysis product obtained with cooling; and at least one dosing device for feeding in pyrolysis material, at least one heatable reactor for the pyrolysis, and at least one pyrolysate collector are arranged and configured in relation to one another in such a way that they can be operated simultaneously.

20. Use of a pyrolysis device according to claim 19 for the recovery of compounds used in the production of polycarbonate-containing, organic

A compound having at least two hydroxyl groups while recovering styrene used in the manufacture of polystyrene-containing compound by simultaneous pyrolysis of said polycarbonate-containing compound and said polystyrene-containing compound.

21 composition containing at least each based on the total weight of

composition

(iii) more than 1.5% by weight of a total amount of at least one aromatic compound having at least one vinyl substituent, preferably styrene or α-methyl styrene, wherein the parts by weight within the parts by weight ranges from (i) to (iii) are selected such that the sum of the selected parts by weight from (i) to (iii) together with the parts by weight of other ingredients results in 100% by weight.