Process for preparing polyester carbonate

Abstract

The invention relates to a process for preparing polyester carbonates in a melt transesterification process starting from polycarbonates or polycarbonate oligomers. The process relates in particular to preparing polyester carbonates in a reactive extrusion process. The process is characterized in that the polyester carbonates prepared have a balanced property distribution with respect to molecular weight, glass transition temperature and residual phenolic OH content. The use also relates to the use of the polyester carbonates prepared according to the invention.

Description

[0001] The invention relates to a process for preparing polyester carbonates in a melt transesterification process starting from polycarbonates or polycarbonate oligomers. The process relates in particular to preparing polyester carbonates in a reactive extrusion process. The process is characterized in that the polyester carbonates prepared have a balanced property distribution with respect to molecular weight, glass transition temperature and residual phenolic OH content. The use also relates to the use of the polyester carbonates prepared according to the invention.

[0002] Polyesters, polycarbonates and polyester carbonates are known to have good properties in terms of mechanical, heat deformation resistance and weathering resistance. Depending on the monomers used, each polymer class has certain key features that characterize this type of material. For example, polycarbonates have particularly good mechanical properties, while polyesters generally show good chemical resistance. Depending on the monomers selected, polyester carbonates show a distribution of properties from the two classes.

[0003] Polyester carbonates made from aromatic diols and linear diacids generally have improved flowability compared to aromatic polycarbonates. In addition, they exhibit better levels of mechanical properties at lower temperatures.

[0004] Polyester carbonates made from aromatic diols and aliphatic diacids are now produced industrially by the interfacial process. Despite publications on the melt transesterification process, this method has not yet established itself. One disadvantage of the interfacial process is the usually necessary discontinuous operation of these specialty products. Since, for example, interfacial plants designed for the production of aromatic polycarbonates usually have large capacities, such specialty products can only be produced with great expenditure and usually at low economic efficiency. In addition, the risk of impurities, for example, being introduced into other products (for example, respective standard products, for example, polycarbonates based on BPA), is very high.

[0005] Therefore, the aim is to develop a method that is flexible and can be implemented cost-effectively on small equipment. In addition, the aim is to proceed from the available raw materials. In addition, the aim is to achieve the shortest possible residence time on the corresponding production unit.

[0006] Surprisingly, this object can be achieved by a melt transesterification process preferably carried out in an extruder, a polymer kneader or other reactor. For this purpose, starting from an aromatic polycarbonate or a corresponding oligomer, the corresponding polyester carbonate is prepared by adding aliphatic and / or aromatic dicarboxylic acids and diaryl carbonates.

[0007] EP1230288 describes a transesterification process of aromatic carbonate oligomers and linear fatty acids. However, the process time is very long, so this is not a promising process for reactive extrusion. The longer the residence time in a continuously operated extruder or polymer kneader, the more uneconomical the method is. For reactive extrusion, the target is a residence time of 30 minutes or less. On the contrary, the process time described in EP1230288 is several hours.

[0008] EP1307421 describes a process for preparing diphenyl esters of dicarboxylic acids. These can react with aromatic diols or even with oligomers. However, this two-stage process cannot be implemented in a continuous reactive extrusion process, or can only be implemented with great difficulty. Similarly, EP1242498 describes a multistage process for preparing polyester carbonates, which is not suitable for reactive extrusion processes.

[0009] EP 1 307 421 and EP 1 230 288 describe ratios between dicarboxylic acids and diaryl carbonates which surprisingly prove to be extremely disadvantageous for reactive extrusion processes.

[0010] The object of the present invention is therefore to develop a method for preparing polyester carbonate from aromatic carbonate oligomers and aliphatic and / or aromatic diacids, which method improves the shortcomings of the above-mentioned prior art. In particular, the object of the present invention is to provide a method that does not need to use phosgene. In addition, a method that can be carried out in a solvent-free manner should be provided. In addition, the method should also be applicable in principle to reactive extrusion processes or melt transesterification processes, that is, the novel method should be characterized by a short process time, i.e. a process time of less than 1 hour. In addition, the polymer should have a high molecular weight (significantly increased compared to the raw materials) and a relatively low OH end group content.

[0011] At least one, preferably all of the above objects are achieved by the present invention. It has been surprisingly found that the direct reaction of aromatic oligomeric carbonates or polycarbonates with at least one aliphatic and / or aromatic diacid and at least one aromatic carbonate in the presence of a basic catalyst produces the desired product. It has also been shown that only the specific ratio of oligomer, diacid and carbonate diester obtains the desired product properties. This has neither been described nor suggested in the prior art.

[0012] Thus, a process for preparing polyester carbonates containing aliphatic and / or aromatic diacids has been found which does not require the use of phosgene and therefore does not involve corresponding safety precautions. In addition, the process can be carried out in a solvent-free manner. This makes the process according to the invention environmentally friendly. In addition, the process can be carried out in short process times. This means that the desired properties, such as molecular weight and OH end group content, can be set in short process times.

[0013] According to the invention, there is therefore provided a process for preparing polyester carbonates by transesterification, preferably by melt transesterification, in which the following components are reacted

[0014] (A) at least one aromatic polycarbonate or oligomeric polycarbonate comprising structural units of the formula

[0015]

[0016] in

[0017] Z is a single bond, -SO2-, -CO-, -O-, -S-, C1- to C6-alkylene, C2- to C5-alkylidene, or C5- to C 12 -cycloalkylidene, and C6- to C6- optionally fused to other aromatic rings containing heteroatoms 12 -arylene group,

[0018] R1 and R2 are independently H, C1- to C 18 -alkyl, C1- to C 18 -alkoxy, halogen such as Cl or Br or C6 to C 18 -Aryl or C7 to C 18 -aralkyl, preferably H or C1- to C 12 -alkyl, particularly preferably H or C1- to C8-alkyl, especially preferably H or methyl, and

[0019] n and n1 are independently an integer from 1 to 5, and if n is a number from 2 to 5, the various radicals R1 may be identical or different, and if n1 is a number from 2 to 5, the various radicals R2 may be identical or different,

[0020] (B) at least one aliphatic and / or aromatic dicarboxylic acid of the formula

[0021]

[0022] in

[0023] R3 is a C1- to C1- 44 -alkylene, C5- to C 44 -cycloalkylene, C7- to C 44 -aralkylene or C6- to C 24 - arylene, diarylene or polyarylene, preferably C6 to C 16 - alkylene,

[0024] and

[0025] (C) at least one diaryl carbonate of the formula

[0026]

[0027] in

[0028] R4 and R5 are independently H, C1-C 34 -alkyl, C7-C 34 -Arylalkyl, C6-C 34 -aryl or -COO-R', where R' corresponds to C1-C 34 -alkyl, C7-C 34 -Arylalkyl, C6-C 34 - aryl,

[0029] m and m1 are independently an integer from 1 to 5, and if m is a number from 2 to 5, the various radicals R4 may be the same or different, and if m1 is a number from 2 to 5, the various radicals R5 may be the same or different,

[0030] The molar ratio of the dicarboxylic acid of formula II to the diaryl carbonate of formula III is 1: 1.01 to 1: 1.9.

[0031] The terms "melt transesterification", "melt transesterification process" or "melt transesterification process" used synonymously according to the invention are known to the person skilled in the art. The melt transesterification process is described, for example, in WO 2001 / 05866 A1, WO 2000 / 105867, US Pat. No. 5,340,905 A, US Pat. No. 5,097,002 A or US Pat. No. 5,717,057 A. In the preparation of polycarbonates, copolycarbonates or copolyestercarbonates by means of melt transesterification, the components required for the reaction, in particular the components (A), (B) and (C) according to the invention and optionally further components, react with one another in the melt. In the case of melt transesterification, the entire reaction mixture remains in the melt during the entire reaction time. The oligomeric structures initially formed generally have a lower melting point or softening point than the final target product of the copolyestercarbonate. However, the temperature in the melt transesterification is selected such that the copolyestercarbonate to be obtained is also present in the melt. Only when the target product, in particular the desired molecular weight or the desired viscosity, is the temperature adjusted so that the target product is now obtained as a solid in the work-up. However, the person skilled in the art understands that melt transesterification is a process in which the entire reaction, in particular the reaction of components (A), (B) and (C) and optionally further components, is carried out in the melt.

[0032] It is also obvious to the person skilled in the art that in the case of melt transesterification, an intimate mixing of the components and later also of the products takes place. Corresponding intimate mixing is known to the person skilled in the art and can be carried out, for example, by means of suitable stirrers, shafts, etc. Furthermore, in the case of melt transesterification—in comparison with, for example, solid phase polymerization—a high level of surface renewal is ensured.

[0033] Here, it is also known to the person skilled in the art that during the melt transesterification, negative pressure must usually be applied in order to shift the equilibrium towards the target product. Only in this way can it be ensured that a sufficiently high molecular weight is established. In the case of melt transesterification, the reaction conditions are therefore selected so that the condensation product(s) are sufficiently removed. The optionally applied vacuum and surface renewal must therefore be sufficient to discharge these condensation products. In particular, pressures of 0.1 to 100 mbar, preferably 0.2 to 1 mbar, are used in the melt transesterification process. It is therefore also preferred according to the invention to use a pressure of 0.1 to 100 mbar, preferably 0.2 to 1 mbar, in the process according to the invention. Here, it is known to the person skilled in the art that such a pressure does not have to be present over the entire reaction time. Such a pressure is preferably used for the preferred process steps ii or ii' according to the invention (described later). Here, it is known to the person skilled in the art that a higher pressure is used at an early reaction time in order to prevent low molecular weight reaction products / reactants from being removed under vacuum. At a later reaction time, a lower pressure is generally used in order to be able to sufficiently remove the condensation products as described above; it should be noted here that the viscosity increases as the reaction proceeds, so that it is more difficult to remove the low molecular weight condensation product / s. Therefore, good mixing and low pressure are usually necessary. The resulting copolyestercarbonate comprises structural units of the following formulae IV and V

[0034]

[0035] or

[0036]

[0037] Here, R1, R2, R3, Z, n and n1 correspond to the above description of formulae I and II, and z and y correspond to natural numbers ≥ 1.

[0038] Z is preferably a single bond, C1- to C5-alkylene, C2- to C5-alkylidene, C5- to C6-cycloalkylidene, -O-, -SO-, -CO-, -S-, -SO2- or a group of formula (VI)

[0039] .

[0040] The preparation of the polycarbonates and oligocarbonates used in the process according to the invention is known to the person skilled in the art and is carried out from diphenols, carbonic acid derivatives, for example phosgene or diaryl carbonates, optionally chain terminators and optionally branching agents.

[0041] According to the present invention, the term "one / multiple oligocarbonates" is understood to mean oligocarbonates having a molecular weight of ≤ 1.210 relThe term "polycarbonate" or "polyester carbonate" refers to a polymer or polymer mixture having a solution viscosity of > 1.210 η rel To 1.38, preferably those with a solution viscosity of 1.23 to 1.36, in each case in dichloromethane at a concentration of 5 g / l at 25 ° C using an Ubbelohde viscometer. It is known to those skilled in the art to determine the relative solution viscosity by means of an Ubbelohde viscometer. According to the invention, this is preferably carried out according to DIN 51562-3; 1985-05. Here, the flow-through time of the measured polyester carbonate is measured by an Ubbelohde viscometer in order to subsequently determine the viscosity difference between the polymer solution and its solvent. For this purpose, the Ubbelohde viscometer is first calibrated by measuring the pure solvents dichloromethane, trichloroethylene and tetrachloroethylene (here always at least 3 measurements, a maximum of 9 measurements). Thereafter, the actual calibration is carried out with the solvent dichloromethane. Then weigh out the polymer sample, dissolve it in dichloromethane, and then measure the flow-through time of this solution three times. The average value of the flow-through time is corrected by the Hagenbach correction method and the relative solution viscosity is calculated.

[0042] Examples of diphenols for the production of the polycarbonates and oligocarbonates to be used according to the invention are: dihydroxybiphenyls, bis(hydroxyphenyl)alkanes, bis(hydroxyphenyl)cycloalkanes, bis(hydroxyphenyl)arenes, bis(hydroxyphenyl)ethers, bis(hydroxyphenyl)ketones, bis(hydroxyphenyl)sulfides, bis(hydroxyphenyl)sulfones, bis(hydroxyphenyl)sulfoxides, 1,1′-bis(hydroxyphenyl)diisopropylbenzene and ring-alkylated and ring-halogenated compounds thereof.

[0043] The divalent group -Ar(R1)n-Z-Ar(R2)n1- in formula I can be obtained by removing two hydroxyl groups from these diphenols.

[0044] Particularly preferred diphenols on which the polycarbonates and oligocarbonates used in the process according to the invention are based are 4,4′-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)-1-phenylpropane, 1,1-bis(4-hydroxyphenyl)phenylethane, 2,2-bis(4-hydroxyphenyl)propane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene (bisphenol M), 2,2-bis(3-methyl-4- 2-(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane, 1,3-bis[2-(3,5-dimethyl-4-hydroxyphenyl)-2-propyl]benzene and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (bisphenol TMC).

[0045] Very particularly preferred diphenols are 4,4′-dihydroxybiphenyl, 1,1-bis(4-hydroxyphenyl)phenylethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (bisphenol TMC).

[0046] Most preferred is 2,2-bis(4-hydroxyphenyl)propane (bisphenol A).

[0047] For example, in US 2 999 835 A, US 3 148 172 A, US 2 991 273 A, US 3 271 367 A, US 4 982 014 A and US 2 999 846 A, German Offenlegungsschrifts 1 570 703 A, 2 063 050 A, 2 036 052 A, 2 211 956 A and 3 832 396 A, French Patent Specification 1 561 518 A1, the monograph “H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964, pages 28 et seq. and 102 et seq.” and “DG Legrand, JT Bendler, Handbook of Polycarbonate Science and Technology, Marcel Dekker New York 2000, These and other suitable diphenols are described on pages 72 et seq.

[0048] In the case of homopolycarbonates or homooligopolycarbonates, only one diphenol is used, in the case of copolycarbonates or co-oligopolycarbonates, two or more diphenols are used. The diphenols used and all other chemicals and adjuvants added to the synthesis may be contaminated by impurities from their own synthesis, handling and storage. However, it is desirable to use raw materials that are as pure as possible.

[0049] The monofunctional chain terminators required for molecular weight regulation, for example phenols or alkylphenols, in particular phenol, p-tert-butylphenol, isooctylphenol, cumylphenol, their chloroformates or acid chlorides of monocarboxylic acids or mixtures of these chain terminators, are supplied to the reaction together with the one or more bisphenol salts or are added at any time in the synthesis, as long as phosgene or chloroformic acid end groups are still present in the reaction mixture or, in the case of acid chlorides and chloroformates as chain terminators, as long as sufficient phenolic end groups are available for the polymer formed. However, it is preferred to add the one or more chain terminators after phosgenation at a point or time at which phosgene is no longer present but the catalyst has not yet been metered in, or to meter them in before, together with or in parallel with the catalyst.

[0050] The branching agents or mixtures of branching agents which may be used are added to the synthesis in the same way, but usually before the chain terminators. Usually triphenols, tetraphenols or acid chlorides of tri- or tetracarboxylic acids or mixtures of polyphenols or mixtures of acid chlorides are used.

[0051] Examples of some compounds that can be used as branching agents and have three or more phenolic hydroxyl groups are phloroglucinol, 4,6-dimethyl-2,4,6-tri(4-hydroxyphenyl)hept-2-ene, 4,6-dimethyl-2,4,6-tri(4-hydroxyphenyl)heptane, 1,3,5-tri(4-hydroxyphenyl)benzene, 1,1,1-tri(4-hydroxyphenyl)ethane, tris(4-hydroxyphenyl)phenylmethane, 2,2-bis[4,4-bis(4-hydroxyphenyl)cyclohexyl]propane, 2,4-bis(4-hydroxyphenylisopropyl)phenol, tetrakis(4-hydroxyphenyl)methane.

[0052] Some other trifunctional compounds are 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride, and 3,3-bis(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole.

[0053] Preferred branching agents are 3,3-bis(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole and 1,1,1-tris(4-hydroxyphenyl)ethane.

[0054] The amount of branching agents optionally used is from 0.05 mol % to 2 mol %, again based on the moles of diphenol used in each case.

[0055] The branching agent can be precharged together with the diphenol and the chain terminator in the alkaline aqueous phase or added before the phosgenation in the form of a solution in an organic solvent.

[0056] All these measures for producing polycarbonates are familiar to the person skilled in the art.

[0057] According to a preferred embodiment, a polycarbonate having an OH end group content of <0.1% by weight, preferably <0.08% by weight, determined by infrared spectroscopy, is used in the method according to the invention. The determination can be carried out as follows: the polycarbonate dissolved in dichloromethane is analyzed in an FT infrared spectrometer Nicolet iS10 from Thermo Fisher Scientific (2 g / 50 ml; 1 mm quartz cuvette). The phenolic OH end group content is determined by evaluating the band at a wave number of 3583 cm-1.

[0058] Aliphatic and / or aromatic dicarboxylic acids can be used as dicarboxylic acids of the formula II. Aliphatic dicarboxylic acids are linear aliphatic and cycloaliphatic dicarboxylic acids.

[0059] Examples which may be mentioned are: phthalic acid, terephthalic acid, isophthalic acid, tert-butylisophthalic acid, 3,3′-diphenyldicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-benzophenonedicarboxylic acid, 3,4′-benzophenonedicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid, 2,2-bis(4-carboxyphenyl)propane, trimethyl-3-phenylindan-4,5′-dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, tetradihydro-2,5-furandicarboxylic acid, tetradihydro-2,5-dimethylfurandicarboxylic acid, decahydro-2,4-naphthalene dicarboxylic acid, decahydro-2,5-naphthalene dicarboxylic acid, decahydro-2,6-naphthalene dicarboxylic acid, decahydro-2,7-naphthalene dicarboxylic acid, dodecanedicarboxylic acid, sebacic acid, adipic acid, octadecanedicarboxylic acid, octadecane-9-enedicarboxylic acid, 9-carboxyoctadecanoic acid and 10-carboxyoctadecanoic acid and dimer fatty acids.

[0060] Dimer fatty acids (also called dimer fatty acids or dimer acids) represent mixtures made by oligomerization of unsaturated fatty acids. 12 - to C 22 -Fatty acids, such as C 18 - fatty acids such as linolenic acid, linoleic acid and / or oleic acid can be used as raw materials. 12 - to C 22 - the number and position of the double bonds of the fatty acids, the carboxyl groups of the dimer fatty acids being linked to one another via hydrocarbon radicals having predominantly 24 to 44 carbon atoms. These hydrocarbon radicals are usually branched and may have double bonds, C6-alicyclic hydrocarbon radicals or C6-aromatic hydrocarbon radicals; cycloaliphatic and / or aromatic radicals may also be present in condensed form. The radicals linking the carboxyl groups of the dimer fatty acids preferably contain no aromatic hydrocarbon radicals, very particularly preferably contain no unsaturated bonds and contain no aromatic hydrocarbon radicals.

[0061] Preferred diacids of the formula II are terephthalic acid, isophthalic acid, 3,3'-diphenyldicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, tetradihydro-2,5-furandicarboxylic acid, dodecanedioic acid, adipic acid, octadecanedioic acid and sebacic acid.

[0062] Particularly preferred diacids are dodecanedioic acid, adipic acid, octadecanedioic acid and sebacic acid.

[0063] Diaryl carbonates corresponding to formula III are described, for example, in EP-A 1 609 818. Preferred are diphenyl carbonate, 4-tert-butylphenyl carbonate-phenyl ester, di(4-tert-butylphenyl) carbonate, biphenyl-4-yl carbonate-phenyl ester, di(biphenyl-4-yl) carbonate, 4-(1-methyl-1-phenylethyl) phenyl carbonate-phenyl ester and di[4-(1-methyl-1-phenylethyl) phenyl] carbonate. Very particularly preferably, substituted or unsubstituted, preferably unsubstituted diphenyl carbonate is used as the carbonate in the process according to the invention.

[0064] Also can use the described carbonate with the residual content of the monohydroxyaryl compound for the preparation of described carbonate.The residual content of described monohydroxyaryl compound can be maximum 20%, preferably 10%, particularly preferably maximum 5%, very particularly preferably maximum 2%.This means that in the method according to the present invention, also can use the carbonate that need not pass through complicated purification after their preparation method.Because in the method according to the present invention, the monohydroxyaryl compound for obtaining carbonate reappears and is preferably removed as condensation product Ar-OH, these impurities can not interfere with reaction.By this advantageous carbonate made, the method according to the present invention can be configured as also more economical and advantageous on the whole.

[0065] In another aspect, it is also possible to prepare the at least one carbonate without using phosgene. This enables the entire process for preparing polyester carbonates to be carried out in a phosgene-free manner.

[0066] The process according to the invention for preparing polyester carbonates by melt transesterification comprises the following process steps:

[0067] i) reacting a dicarboxylic acid component B and a diaryl carbonate component C to produce a diaryl ester D,

[0068] ii) further condensing the diaryl ester D obtained in process step i with the polycarbonate / oligocarbonate component A.

[0069] In this case, process steps i) and ii) are carried out in the melt.

[0070] These reactions are shown, for example, in the figure below (Figure 1)

[0071] Step i :

[0072]

[0073] Step ii :

[0074]

[0075] It is obvious to the person skilled in the art that the reaction schemes for method steps (i) and (ii) shown above are to be understood only as examples and not as limiting. In particular, according to the invention it cannot be excluded that further reactions also occur, in particular in method step (i). For example, it is very likely that macromolecules (molecules in which the individual monomers have been partially condensed) have already been formed in method step (i). However, further side reactions and / or intermediate stages may also occur. Likewise, the reaction in method step (i) does not have to be complete, but may also only occur partially in method step (ii). However, in method step (i), the reaction is substantially complete. However, preferably, according to the invention, method step (i) is carried out until a significant reduction in gas formation can be observed, and only then is method step (ii) initiated, for example by applying a vacuum to remove the compounds eliminated in the condensation. However, as described above, it is optionally not possible according to the invention to achieve a clear separation between method steps (i) and (ii).

[0076] Alternatively, the method can also be carried out as follows

[0077] In the first process step i, only a portion of the total amount of the diaryl carbonate component C to be used in the process is used,

[0078] Before or during the second process step ii, the remainder of the diaryl carbonate component C is added to the reaction mixture from process step i to form further diaryl esters in the second process step, while the above-described condensation takes place in parallel thereto (process step ii').

[0079] Here, process steps i) and ii′) are also carried out in the melt.

[0080] According to the invention, it is preferred that process steps i) and ii) or ii') directly follow one another. This means, for example, that there are no steps of recrystallization, precipitation, addition of solvent, etc.

[0081] In process step ii, no further condensation of the reaction mixture obtained from process step i takes place. In the context of the present invention, the expression "further" condensation is understood to mean that condensation has already taken place in process step i. This is preferably a reaction of the dicarboxylic acid B with the diaryl carbonate C with elimination of the aromatic alcohol.

[0082] The term "condensation" is known to those skilled in the art. This is preferably understood to mean a reaction in which two molecules (same substance or different substances) merge to form a larger molecule and in which molecules of a chemically simple substance are eliminated. Preferably, this compound eliminated during the condensation is removed by applying a vacuum in method step ii or ii'. Preferably, the pressure is gradually reduced at this point. In a first embodiment, method step i preferably further comprises one of the following two steps ia): melting a mixture of components A, B and C, or pre-loading a molten component A and mixing components B and C in liquid form separately. In an alternative embodiment, in method step i, only a portion of component C is melted with components A and B, or is metered into the pre-loaded molten component A in liquid form, and then the remaining component C is added in liquid form before or during method step ii'.

[0083] For this purpose, an extruder is preferably used, for example a twin-screw extruder, in which the polycarbonate / oligocarbonate and the other reactants are mixed and plasticized. Alternatively, the oligocarbonate or polycarbonate is pre-charged in molten form and the diacid and diaryl carbonate are metered in as liquids via the extruder dome. However, the mixing can also be carried out with the aid of a dynamic or static mixer.

[0084] The reaction in process step i is preferably carried out at a temperature of from 280 to 320° C. and a pressure of from 20 to 800 mbar, preferably from 100 to 600 mbar, for a duration of up to 20 minutes, preferably from 1 to 15 minutes.

[0085] Process step i can be carried out, for example, on a twin-screw extruder; furthermore, kneaders, cage or disk reactors and falling-film evaporators are also possible.

[0086] Process step ii or ii' is preferably carried out at a pressure of 0.1 to 100 mbar, preferably 0.2 to 1 mbar. Such a pressure ensures that the desired viscosity or the desired target molecular weight of the copolyestercarbonate according to the invention is obtained. By the Le Chatelier principle, the reaction equilibrium is thus shifted. It is also preferred that process step ii or ii' is carried out at a temperature of 300 to 350° C. These temperatures ensure that the components and also in particular the target product are present in the melt.

[0087] Method step ii or ii' is particularly preferably carried out at a pressure of 0.1 to 100 mbar, preferably 0.2 to 1 mbar, and a temperature of 300 to 350° C. These conditions ensure that a good balance between energy input, reaction time and yield is achieved. According to the invention, short reaction times are feasible. These will not expose the copolyestercarbonate to be obtained to thermal stress for too long, so that the resulting product is of excellent quality. It is therefore preferred to use a reaction time of 10 to 60 minutes, particularly preferably 15 to 45 minutes, in method step ii or ii'. These reaction times also make it possible, in particular, for the entire method according to the invention to be carried out continuously.

[0088] Process step ii or ii' can likewise be carried out on extruders, grid or disk reactors, planetary roller extruders, high-viscosity reactors, falling-film evaporators or similar apparatuses.

[0089] The process according to the invention can be carried out continuously or discontinuously. However, it is preferably carried out continuously.

[0090] According to the invention, the molar ratio of the dicarboxylic acid of formula II to the diaryl carbonate of formula III is 1:1.01 to 1:1.9, preferably 1:1.05 to 1:1.5, particularly preferably 1:1.35. The dicarboxylic acid component B is used in an amount of 2 to 20% by weight, preferably 3 to 15% by weight, particularly preferably 4 to 10% by weight, based on the total weight of the polycarbonate / oligocarbonate component A. The ratio of the raw materials is crucial to the subsequent quality of the polyester carbonate.

[0091] According to one embodiment, only a portion of the diaryl carbonate component C is initially used in process step i. The remainder can be added to the melt mixture in a subsequent stage of the reaction (process step ii'). No changes to the above ratios are permitted.

[0092] In the process according to the invention, other components, such as catalysts, may be added in addition to the components mentioned above.

[0093] The process is preferably carried out in the presence of a catalyst, particularly preferably in the presence of a basic catalyst. The catalyst may be used in step i and / or ii or ii'.

[0094] Catalysts which come into consideration include all inorganic or organic basic compounds, for example hydroxides, carbonates, halides, phenolates, diphenolates, fluorides, acetates, phosphates, hydrogenphosphates and borates of lithium, sodium, potassium, cesium, calcium, barium and magnesium, nitrogen bases and phosphorus bases, for example tetramethylammonium hydroxide, tetramethylammonium acetate, tetramethylammonium fluoride, tetramethylammonium tetraphenylborate, tetraphenylphosphonium fluoride, tetraphenylphosphonium tetraphenylborate, dimethyldiphenylammonium hydroxide, tetraethylammonium hydroxide, hexadecyltrimethylammonium tetraphenylborate, hexadecyltrimethylammonium phenolate, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3 .0]non-5-ene (DBN) or a guanidine system, such as 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-phenyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7,7'-hexylidenedi-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7,7'-decylidenedi-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7,7'-dodecylidenedi-1,5,7-triazabicyclo[4.4.0]dec-5-ene, or a phosphazene, such as the phosphazene base P1-t-Oct = tert-Octyliminotris(dimethylamino)phosphane, Phosphazene Base P1-tert-Butyl = tert-Butyliminotris(dimethylamino)phosphane, BEMP = 2-tert-Butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diaza-2-phosphane.

[0095] Especially suitable are phosphonium catalysts of formula (VII):

[0096]

[0097] wherein Ra, Rb, Rc and Rd can be identical or different C1-C10-alkyl, C6-C14-aryl, C7-C15-arylalkyl or C5-C6-cycloalkyl, preferably methyl or C6-C14-aryl, particularly preferably methyl or phenyl, and X- can be an anion, such as hydroxide, sulfate, hydrogensulfate, bicarbonate, carbonate or halide, preferably chloride, or an alkylate or arylate of the formula -OR, wherein R can be C6-C14-aryl, C7-C15-arylalkyl or C5-C6-cycloalkyl, preferably phenyl.

[0098] Particularly preferred catalysts are tetraphenylphosphonium chloride, tetraphenylphosphonium hydroxide and tetraphenylphosphonium phenolate, tetraphenylphosphonium phenolate being very particularly preferred.

[0099] These catalysts are preferably present in an amount of 10 based on 1 mol of dicarboxylic acid component B. -2 Up to 10 -8The amount of the basic salt used as promoter may be 1 to 500 ppb, preferably 5 to 300 ppb, particularly preferably 5 to 200 ppb.

[0100] In one aspect of the invention, one or more stabilizers may be added to the melt. This may be a known antioxidant, such as a phosphorus-based antioxidant or a phenolic antioxidant. It is also preferred that the entire reaction be carried out in an oxygen-free manner as much as possible. Oxygen inevitably leads to the formation of oxidation products. In order to minimize this formation, stabilizers and / or antioxidants may also be used.

[0101] These stabilizers are preferably selected from phosphorus-containing stabilizers and / or phenolic free radical scavengers. Phosphites and phosphonites and phosphines are preferably suitable. Examples include triphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris(nonylphenyl) phosphites, trilauryl phosphites, tri(octadecyl) phosphites, distearyl pentaerythritol diphosphites, tris(2,4-di-tert-butylphenyl) phosphites, diisodecyl pentaerythritol diphosphites, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphites, bis(2,4-dicumylphenyl) pentaerythritol diphosphites, bis(2,6 ... -tert-butyl-4-methylphenyl) pentaerythritol ester, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite, bis(2,4,6-tri(tert-butylphenyl) pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis(2,4-di-tert-butylphenyl) 4,4'-biphenylene diphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenzo[d,g]-1 ,3,2-dioxaphospholine, bis(2,4-di-tert-butyl-6-methylphenyl)methyl phosphite, bis(2,4-di-tert-butyl-6-methylphenyl)ethyl phosphite, 6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyldibenzo[d,g]-1,3,2-dioxaphospholine, 2,2',2"-nitrilo[triethyl tris(3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl)phosphite], 2-Ethylhexyl 3,3',5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl phosphite, 5-butyl-5-ethyl-2-(2,4,6-tri-tert-butylphenoxy)-1,3,2-dioxaphosphirane, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, triphenylphosphine (TPP), trialkylphenylphosphine, bisdiphenylphosphinoethane or trinaphthylphosphine. Particular preference is given to using triphenylphosphine (TPP), Irgafos® 168 (tris(2,4-di-tert-butylphenyl) phosphite) and tris(nonylphenyl) phosphite or mixtures thereof.

[0102] It is also possible to use phenolic free radical scavengers such as alkylated monophenols, alkylated sulfoalkylphenols, hydroquinones and alkylated hydroquinones. Particular preference is given to using Irganox® 1010 (pentaerythritol 3-(4-hydroxy-3,5-di-tert-butylphenyl) propionate; CAS: 6683-19-8) and Irganox 1076® (2,6-di-tert-butyl-4-(octadecyloxycarbonylethyl)phenol).

[0103] According to the invention, both process steps (i) and (ii) or (ii') are preferably carried out in the absence of an additional organic solvent. The process according to the invention can therefore preferably be carried out without a solvent. This does not exclude, according to the invention, that both the used diaryl carbonate and the condensation product formed in the reaction may be present as solvent in these reaction steps (if possible). This is particularly true if the carbonate is used in a stoichiometric excess relative to the dicarboxylic acid. This preferred process variant is particularly gentle. However, it is preferred according to the invention that no additional organic solvent is added to the process. Due to the absence of an additional organic solvent, the process can be carried out smoothly and in an environmentally friendly manner.

[0104] The process according to the invention ensures that the ratio of OH end groups to acid end groups is extremely low. The low concentration of residual OH groups and in particular free acid end groups can be further reduced at the end of the reaction by epoxy-containing additives and / or by carbodiimide-containing additives.

[0105] Useful oligomeric and / or polymeric carbodiimides are all known carbodiimides of the formula

[0106]

[0107] in

[0108] R"' is an aromatic and / or aromatic aliphatic radical, and if m ≥ 1, R"' is identical or different within the molecule, and each of the above radicals can be combined arbitrarily with one another in various combinations,

[0109] R'" in the case of an aromatic or aromatic aliphatic radical may carry no substituents or, in at least one ortho position to the aromatic carbon atom carrying the carbodiimide group, may carry an aliphatic and / or cycloaliphatic substituent having at least 2 carbon atoms, preferably a branched or cyclic aliphatic radical having at least 3 carbon atoms, in particular an isopropyl radical, which may also carry heteroatoms such as N, S and / or O or an imidazolyl radical,

[0110] R' = C1-C18-alkyl, C5-C18-cycloalkyl-, aryl, C7-C18-aralkyl, -R-NHCOS-R1, -R-COOR1, -RO R1, -RN(R1)2, -R-SR1, -R-OH, -R-NH2, -R-NHR1, -R-epoxy, -R-NCO, -R-NHCONHR1, -R-NHCONR1R2 or -R-NHCOOR3, wherein R = aromatic, aliphatic, cycloaliphatic and / or araliphatic radical,

[0111] R"= H, -N=C=N-aryl, -N=C=N-alkyl, -N=C=N-cycloalkyl, -N=C=N-aralkyl, -NCO, -NHCONHR1, -NHCONR1R2, -NHCOOR3, -NHCOS- R1, -COO R1, -O R1, -N (R1)2, -SR1, -OH, -NH2, -NH R1,

[0112] wherein in R' and R", independently of one another, R1 and R2 are identical or different and are C1-C20-alkyl-, C3-C20-cycloalkyl-, -aryl, C7-C18-aralkyl, oligo- / polyethylene glycol and / or oligo- / polypropylene glycol, and R3 has one of the definitions of R1 or is a polyester or polyamide radical, and m corresponds to an integer from 1 to 5000, and in the case of oligocarbodiimides, m corresponds to an integer from 1 to 5, and in the case of polymeric carbodiimides, m corresponds to an integer > 5,

[0113] and / or carbodiimide of formula (IX)

[0114]

[0115] in

[0116] Y = arylene, C7-C18-aralkylene

[0117] p = an integer from 1 to 500, preferably from 1 to 100,

[0118] B = -NH-CO-NH-Z-, -NH-COO-Z-, -NH-COS-Z-,

[0119] q = an integer from 1 to 500, preferably from 1 to 100,

[0120] o = an integer from 1 to 500, preferably from 1 to 100,

[0121] X = H, -OH, -SH, -NH2, -OR1, -N(R1)2, -SR1, -NHR1, NR1R2, -OCO-NH- R', NHCO-, -NH-R', -S-CO-NH- R' R' = C1-C18-alkyl, C5-C18-cycloalkyl, aryl, C7-C18-aralkyl, -R"'-NH-COS-R1, R"'-COOR1, -R'''-OR1 -R"'-N(R1)2, - R'''-SR1, -R'"-OH, -R'''-NH2, -R'''-NHR1, -R"'-epoxy, - R'''-NCO, -R'''-NHCONHR1, -R"'-NHCONR1R2 or - R"'-NH-COOR3, wherein R1 and R2 are identical or different and are C1-C20-alkyl, C3-C20-cycloalkyl, aryl, C7-C18-aralkyl, oligo- / polyethylene glycol and / or oligo- / polypropylene glycol, and R3 has one of the definitions of R1 or is a polyester or polyamide radical,

[0122] Z = Y, polyester, polyether, polyamide, and R''' describes an aromatic and / or araliphatic group.

[0123] Particular preference is given here to aromatic oligomeric and / or polymeric carbodiimides of the abovementioned formula (VIII) in which m≧2.

[0124] It is also preferred that the polymeric and / or oligomeric carbodiimide is a compound of the formula (IX) in which R''' corresponds to 1,3-substituted 2,4,6-triisopropylphenyl and / or 1,3-bis(1-methyl-1-isocyanatoethyl)benzene and / or a tetramethylbenzylene derivative and / or a 2,4-substituted tolylene and / or a 2,6-substituted tolylene and / or a mixture of 2,4- or 2,6-substituted tolylene.

[0125] The above-mentioned carbodiimides are commercially available compounds, which are available, for example, under the trade names Stabaxol® P (NCN content: 12.5-13.5%), Stabaxol® P 100 (NCN content: 12.5 - 13.5%) and Stabaxol® P 400 (NCN content: 12.5 - 13.5%) from Rhein Chemie Rheinau GmbH.

[0126] Epoxy-containing additives useful for blocking carboxylic acid functionality are, for example, compounds of bisphenol A and epichlorohydrin according to the following formula X, wherein n is about 0 (i.e., only one BPA unit is present), such as those sold under the trade names "Epikote 828" and "Araldite GY-260";

[0127]

[0128] Compounds wherein n is about 1, such as those sold under the trade names "Epikote 834" and "Araldite GY-280"; compounds wherein n is about 2, such as those sold under the trade names "Epikote 1001" and "Araldite 6071"; compounds wherein n is about 3, such as those sold under the trade names "Epikote 1002" and "Araldite 7072"; and compounds wherein n is about 4, such as "Epikote 1004" and "Araldite 6084" (Note: "Epikote" and "Araldite" are trademarks of Hexion and Huntsman Advanced Materials, respectively; n is an average value for the polymerization, which is why one can say, for example, "n is about 0").

[0129] Among these epoxy compounds, diglycidyl ether bisphenol-A in which n = 0 is particularly effective in preventing hydrolysis. This is because this compound in which n = 0 is liquid and can be easily mixed with polyester carbonate, thereby simplifying the preparation.

[0130] In addition to the above-mentioned bisphenol A epoxy compounds, alicyclic epoxy compounds may also be mentioned as useful additives, for example, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate.

[0131] The epichlorohydrin bisphenol A epoxy compound may be used in an amount of up to 0.01 to 5% by weight, preferably 0.1 to 1% by weight, based on the weight of the polyester carbonate to be prepared.

[0132] The present invention further provides polyester carbonates obtainable by the process according to the invention described above.

[0133] They preferably have a content of phenolic OH end groups determined by means of infrared spectroscopy of less than 0.13% by weight, particularly preferably less than 0.12% by weight, very particularly preferably less than 0.11% by weight. The determination can be carried out as follows: The polyester polycarbonate (2 g / 50 ml; 1 mm quartz cuvette) dissolved in dichloromethane is analyzed in an FT infrared spectrometer Nicolet iS10 from ThermoFisher Scientific. The phenolic OH end group content is determined by evaluating the band at a wave number of 3583 cm-1.

[0134] Example :

[0135] Materials used:

[0136] Diphenyl carbonate: Diphenyl carbonate, 99.5%, CAS 102-09-0; Acros Organics, Geel, Belgium

[0137] Sodium phenolate: Sodium phenolate trihydrate, 98%, CAS 652-67-5; Merck, Darmstadt, Germany

[0138] Tetraphenylphosphonium phenolate: Tetraphenylphosphonium phenolate, 66.5%, CAS 15464-47-8; Rheinchemie

[0139] Irganox B900 (Manufacturer: BASF)

[0140] Polycarbonate 1:

[0141] The linear bisphenol A polycarbonate used had phenol-based end groups with a carbonyl group density of 59-62 cm 2 at 300° C. under a load of 1.2 kg. 3 / 10 min melt volume index (according to ISO 1033) and a solution viscosity of about 1.21. This polycarbonate does not contain additives such as UV stabilizers, release agents or heat stabilizers in a proportion of more than 10 ppm. The polycarbonate has a phenol content of 108 ppm, a bisphenol A content of 29 ppm, a diphenyl carbonate content of 500 ppm (each determined by reverse phase chromatography as described below), and a phenolic end group content of about 700 ppm (determined by infrared spectroscopy as described below).

[0142] Oligocarbonate 1:

[0143] A linear bisphenol A oligocarbonate with phenolic end groups having a solution viscosity of 1.17. This oligocarbonate does not contain additives such as UV stabilizers, mold release agents or heat stabilizers in a proportion of more than 10 ppm. The oligocarbonate has a phenol content of 275 ppm, a bisphenol A content of 124 ppm and a diphenyl carbonate content of 533 ppm (determined by reverse phase chromatography as described below). The phenolic OH end group content is about 0.16% by weight (determined by infrared spectroscopy as described below).

[0144] Analytical methods:

[0145] Determination of the phenol content, bisphenol A content and diphenyl carbonate content of the polycarbonate or oligocarbonate 1 used:

[0146] To determine the residual monomers, the sample was dissolved in dichloromethane and then precipitated with acetone / methanol. After separation of the precipitated polymer, the filtrate was concentrated. The residual monomers were quantified by reverse phase chromatography in acetonitrile. Detection was performed using a UV detector.

[0147] Determination of the content of phenolic OH end groups :

[0148] Polycarbonates or oligocarbonates or polyester carbonates dissolved in dichloromethane (2 g / 50 ml; 1 mm quartz cuvette) were analyzed in an FT infrared spectrometer Nicolet iS10 from Thermo Fisher Scientific. The phenolic OH end group content was determined by evaluating the band at a wave number of 3583 cm-1.

[0149] Determination of glass transition temperature :

[0150] The glass transition temperature was determined by dynamic differential scanning calorimetry (DSC) under nitrogen at a heating rate of 10 K / min in accordance with DIN EN ISO 11357-1:2009-10 and ISO 11357-2:2013-05, wherein the glass transition temperature (Tg) was determined as the inflection point in the second heating run.

[0151] Chemical characterization :

[0152] 1 H NMR: 600 MHz; Bruker AV III HD 600 spectrometer; solvent: CDCl3.

[0153] Solution viscosity

[0154] The relative solution viscosity (ηrel; also known as eta rel) is determined using an Ubbelohde viscometer in dichloromethane at a concentration of 5 g / l at 25°C. The determination is carried out in accordance with DIN 51562-3; 1985-05. Here, the flow-through time of the measured polyester carbonate is measured by means of an Ubbelohde viscometer in order to subsequently determine the viscosity difference between the polymer solution and its solvent. For this purpose, the Ubbelohde viscometer is first calibrated by measuring the pure solvents dichloromethane, trichloroethylene and tetrachloroethylene (here always at least 3 measurements and a maximum of 9 measurements). Thereafter, the actual calibration is carried out with the solvent dichloromethane. A sample of the polymer is then weighed out, dissolved in dichloromethane and the flow-through time of this solution is then determined three times. The mean value of the flow-through time is corrected by means of the Hagenbach correction and the relative solution viscosity is calculated. The glass transition temperature is determined.

[0155] Example using oligocarbonate

[0156] Example 1 (Comparative example; no DPC added)

[0157] 47.0 g of oligocarbonate 1 and 3 g (6 wt%) of sebacic acid were pre-loaded in a flask with a short-path separator together with 12.5 mg of TPP-P. The mixture was deoxygenated by evacuating and purging with nitrogen four times. The mixture was melted and heated to 280° C. while stirring. The pressure was reduced to 500 mbar and maintained at this pressure and a temperature of 280-290° C. for 15 minutes. (Step 1). Thereafter, the temperature was increased to 320° C. within about 30 minutes and the pressure was gradually reduced to 0.8 mbar. Only a small amount of distillate was separated here. (Step 2).

[0158] Example 2 (Comparative example; ratio of diacid to DPC 1:1)

[0159] 47.0 g of oligocarbonate 1, 3 g (6 wt%) of sebacic acid (0.015 mol) and 3.18 g of diphenyl carbonate (0.015 mol) were pre-charged in a flask with a short-path separator together with 12.5 mg of TPP-P. The mixture was freed of oxygen by evacuation and purging four times with nitrogen. The mixture was melted and heated to 280° C. while stirring. The pressure was reduced to 500 mbar; the temperature was increased to 300° C. within 20 minutes. (Step 1)

[0160] Thereafter, the temperature is increased to 320° C. over the course of about 30 minutes and the pressure is reduced stepwise to 1.0 mbar. In this process, phenol is separated off. (Step 2).

[0161] Example 3 (Comparative example; ratio of diacid to DPC 1:1.5)

[0162] 43.82 g of oligocarbonate 1, 3.0 g (6 wt%) of sebacic acid (0.015 mol) and 4.77 g of diphenyl carbonate (0.022 mol) were pre-loaded together in a flask with a short path separator. The mixture was deoxygenated by evacuating and purging with nitrogen four times. The mixture was melted and heated to 280° C. while stirring. The pressure was reduced to 500 mbar and allowed to stir for 10 minutes. It was then purged with nitrogen and 12.5 mg of TPP-P was added. (Step 1).

[0163] The temperature was increased to 320° C. within 15 minutes and the pressure was reduced to 0.7 mbar. Phenol was removed continuously during this process.

[0164] Example 4 (Comparative example; ratio of diacid to DPC 1:2)

[0165] 40.64 g of oligocarbonate 1, 3.0 g (6 wt%) of sebacic acid (0.015 mol) and 6.35 g of diphenyl carbonate (0.030 mol) were pre-charged together in a flask with a short-path separator. The operation was continued as in Example 3.

[0166] Example 5 (The present invention; the ratio of diacid to DPC is 1:1.25)

[0167] The experiment was carried out as described in Example 3. 43.01 g of oligocarbonate 1, 3.0 g (6 wt%) of sebacic acid (0.015 mol) and 3.98 g of diphenyl carbonate (0.019 mol) were used.

[0168] A) Example using polycarbonate

[0169] Example 6 (Comparative example; ratio of diacid to DPC 1:0)

[0170] 47.0 g of polycarbonate 1, 3.0 g (6 wt%) and 3.0 g of sebacic acid (0.015 mol) were pre-loaded together in a flask with a short path separator. The mixture was deoxygenated by evacuating and purging with nitrogen four times. The mixture was melted and heated to 280° C. while stirring. The pressure was reduced to 500 mbar and allowed to stir for 10 minutes. It was then purged with nitrogen and 12.5 mg of TPP-P was added. (Step 1).

[0171] The temperature was increased to 320°C and the pressure was reduced stepwise to 1 mbar over 25 minutes (step 2).

[0172] Example 7 (Comparative example; ratio of diacid to DPC 1:1)

[0173] 43.82 g of polycarbonate 1, 3.0 g (6 wt%) of sebacic acid (0.015 mol) and 3.18 g of diphenyl carbonate (0.015 mol) were pre-loaded together in a flask with a short path separator. The mixture was deoxygenated by evacuating and purging with nitrogen four times. The mixture was melted and heated to 280° C. while stirring. The pressure was reduced to 500 mbar and allowed to stir for 10 minutes. It was then purged with nitrogen and 12.5 mg of TPP-P was added. (Step 1).

[0174] The temperature was increased to 320° C. over the course of 25 minutes and the pressure was reduced stepwise to 1 mbar. Phenol was removed continuously during this process. (Step 2).

[0175] Example 8 (Present invention; ratio of diacid to DPC 1:1.15)

[0176] The experiment was performed as in Example 7.

[0177] Example 9 (Present invention; ratio of diacid to DPC 1:1.2)

[0178] The experiment was performed as in Example 7.

[0179] Example 10 (The present invention; the ratio of diacid to DPC is 1:1.25)

[0180] The experiment was performed as in Example 7.

[0181] Example 11 (Comparative example, similar to Example 1 of WO01 / 48050A1)

[0182] 45.47 g of bisphenol-based polycarbonate oligomer (η rel About 1.17) and 2.387 g (0.0118 mol) of sebacic acid and 2.956 g (0.0138 mol) of diphenyl carbonate were pre-loaded in a three-necked flask (the flask was previously washed with 3M hydrochloric acid, rinsed with water, and then dried). Then 5.91 microliters of 1 mmol / L sodium hydroxide solution and 168.48 microliters of 0.22 mmol / L tetramethylammonium hydroxide solution were added. The contents of the flask were deoxygenated by evacuating and inerting with nitrogen three times. The reactants were melted at 240°C in a metal bath. After the reactants were melted, they were stirred at 60 rpm at 240°C and ambient pressure for 2 hours.

[0183] The pressure was then reduced to about 250 mbar. Stirring was carried out for 3.5 hours. After pouring out the melt, a brittle solidified frit of low viscosity was obtained.

[0184]

[0185] Vergl. = comparative example; erf. = example according to the invention.

[0186] Low η in Example 1 rel The values ​​show that if no diaryl carbonate is added to the reaction, the diacid is not incorporated into the polycarbonate oligomers or is incorporated only to a very insufficient extent. Despite the high reactivity of the polycarbonate oligomers and despite the high OH end group content, no increase in molecular weight can be achieved. The experiments with polycarbonate (Example 6) show the same results.

[0187] Examples 2 and 7 surprisingly show that a molar deficiency of diaryl carbonate relative to the acid group equivalents leads to oligomeric polycarbonates or polyester carbonates with high molecular weights. This is surprising since, according to EP 1 230 288 (Examples 3 and 4), at least an equimolar ratio of diaryl carbonate relative to the carboxylic acid equivalents is required to form the corresponding diaryl esters.

[0188] However, the oligo- or polyester carbonates of Examples 2 and 7 show a content of phenolic OH groups above 1300 ppm. A high OH end group content can have a negative effect on the properties of the poly(ester) carbonates. For example, discoloration can occur, for example, through oxidation processes during processing. The presence of acidic OH groups can increase the ease with which the polymers are hydrolyzed. Polyester carbonates therefore preferably have as low an OH end group content as possible; an OH end group content is preferably <0.13% by weight.

[0189] As is clear from the examples in Table 1, only when the diacid and diaryl carbonate are used in a molar ratio of > 1:1 and < 1:2, good to excellent molecular weight growth occurs, while the product has a low OH end group content. The table also shows that the polycarbonate-based products produced within this ratio have an excellent glass transition temperature. Products based on oligocarbonates show an excellent glass transition temperature as long as the molar ratio is below 1:1.5 (<1:1.5).

[0190] Comparative Example 11 shows that if the conditions known to those skilled in the art for melt transesterification are not chosen (such as sufficient removal of condensation products to shift the equilibrium, e.g. by applying low pressure), no sufficient molecular weight increase is observed - in fact there is even a decrease in molecular weight.

Claims

1. A process for preparing polyester carbonates having an OH end group content of <0.13% by weight by melt transesterification, wherein the following components are reacted (A) at least one aromatic polycarbonate or oligocarbonate comprising structural units of the formula in Z is a single bond, -SO2-, -CO-, -O-, -S-, C1- to C6-alkylene, C2- to C5-alkylidene, or C5- to C 12 -cycloalkylidene, and optionally C6- to C6- 12 -arylene group, R1 and R2 are independently H, C1- to C 18 -alkyl, C1- to C 18 -alkoxy, halogen or C6 to C 18 -Aryl or C7 to C 18 -aralkyl, and n and n1 are independently of one another an integer from 1 to 5, and if n is a number from 2 to 5, the radicals R1 are identical or different, and if n1 is a number from 2 to 5, the radicals R2 are identical or different, (B) at least one aliphatic and / or aromatic dicarboxylic acid of the formula in R3 is a C1- to C1- 44 -alkylene, C5- to C 44 -cycloalkylene, C7- to C 44 -aralkylene or C6- to C 24 - arylene, diarylene or polyarylene, and (C) at least one diaryl carbonate of the formula in R4 and R5 are independently H, C1-C 34 -alkyl, C7-C 34 -Arylalkyl, C6-C 34 -aryl or -COO-R', where R' corresponds to C1-C 34 -alkyl, C7-C 34 -Arylalkyl, C6-C 34 - aryl, m and m1 are independently an integer from 1 to 5, and if m is a number from 2 to 5, the radicals R4 are identical or different, and if m1 is a number from 2 to 5, the radicals R5 are identical or different, The molar ratio of the dicarboxylic acid of formula II to the diaryl carbonate of formula III is 1:1.01 to 1:1.9, The dicarboxylic acid component B is used in an amount of 2 to 20% by weight, based on the total weight of the polycarbonate / oligocarbonate component A.

2. A process for preparing polyester carbonates by melt transesterification as claimed in claim 1, wherein the molar ratio of the dicarboxylic acid of formula II to the diaryl carbonate of formula III is from 1:1.05 to 1:1.

5.

3. A process for preparing polyester carbonate by melt transesterification as claimed in claim 1 or 2, wherein Z in component (A) is a single bond, a C1- to C5-alkylene group, a C2- to C5-alkylidene group, a C5- to C6-cycloalkylidene group, -O-, -SO-, -CO-, -S-, -SO2- or a group of formula (VI) 4. A process for preparing polyester carbonates by melt transesterification as claimed in claim 3, wherein the group -Ar(R1)n-Z-Ar(R2)n1- in formula I corresponds to a divalent group obtained by removing two hydroxyl groups from the following diphenols: 4,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)-1-phenylpropane, 1,1-bis(4-hydroxyphenyl)phenylethane, 2,2-bis(4-hydroxyphenyl)propane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 1,3-bis[2-(4-hydroxyphenyl)- 2-propyl]benzene (bisphenol M), 2,2-bis(3-methyl-4-hydroxyphenyl)propane, bis(3,5-dimethyl-4-hydroxyphenyl)methane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, bis(3,5-dimethyl-4-hydroxyphenyl)sulfone, 2,4-bis(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane, 1,3-bis[2-(3,5-dimethyl-4-hydroxyphenyl)-2-propyl]benzene and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (bisphenol TMC).

5. A process for preparing polyester carbonate by melt transesterification as claimed in claim 1 or 2, wherein the dicarboxylic acid of formula II is selected from the group consisting of phthalic acid, terephthalic acid, isophthalic acid, tert-butylisophthalic acid, 3,3'-diphenyldicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4-benzophenonedicarboxylic acid, 3,4'-benzophenonedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 2,2-bis(4-carboxyphenyl)propane, trimethyl-3-phenylindan-4, 5'-dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, tetradihydro-2,5-furandicarboxylic acid, tetradihydro-2,5-dimethylfurandicarboxylic acid, decahydro-2,4-naphthalene dicarboxylic acid, decahydro-2,5-naphthalene dicarboxylic acid, decahydro-2,6-naphthalene dicarboxylic acid, decahydro-2,7-naphthalene dicarboxylic acid, dodecanedicarboxylic acid, sebacic acid, adipic acid, octadecanedicarboxylic acid, octadecane-9-enedicarboxylic acid, 9-carboxyoctadecanoic acid and 10-carboxyoctadecanoic acid and dimer fatty acids.

6. A process for preparing polyester carbonates by melt transesterification as claimed in claim 1 or 2, wherein the diaryl carbonate of formula III is selected from the group consisting of diphenyl carbonate, 4-tert-butylphenyl-phenyl carbonate, di(4-tert-butylphenyl) carbonate, biphenyl-4-yl-phenyl carbonate, di(biphenyl-4-yl) carbonate, 4-(1-methyl-1-phenylethyl)phenyl-phenyl carbonate and di[4-(1-methyl-1-phenylethyl)phenyl] carbonate.

7. A method for preparing polyester carbonate by melt transesterification as claimed in claim 1, comprising the steps of i) reacting a dicarboxylic acid component B and a diaryl carbonate component C to produce a diaryl ester D, ii) further condensing the diaryl ester D obtained in process step i with the polycarbonate / oligocarbonate component A.

8. A process for preparing polyester carbonates by melt transesterification as claimed in claim 1, comprising the steps i) reacting a part of the total amount of dicarboxylic acid component B to be reacted in the process with a part of the total amount of diaryl carbonate component C to be reacted in the process to produce diaryl ester D, ii') reacting the remainder of the total amount of dicarboxylic acid component B to be reacted in the process with the remainder of the total amount of diaryl carbonate component C to be reacted in the process to form further diaryl ester D and, in parallel, further condensing diaryl ester D with polycarbonate / oligocarbonate component A.

9. A process for preparing polyester carbonates by melt transesterification as claimed in claim 7 or 8, wherein, in addition to components B and C, component A is also present during process step i.

10. A process for preparing polyester carbonates by melt transesterification as claimed in claim 7 or 8, wherein the reaction in process step i is carried out at a temperature of 280 to 320°C.

11. A process for preparing polyester carbonates by melt transesterification as claimed in claim 7 or 8, wherein process step ii or ii' is carried out at a temperature of 300 to 350°C.

12. A process for preparing polyester carbonates by melt transesterification as claimed in claim 7, wherein in process step ii or ii' the compounds eliminated in the condensation are removed by means of a vacuum.

13. A process for preparing polyester carbonates by melt transesterification as claimed in claim 1 or 2, wherein the polycarbonate used as component A has an OH end group content of <0.1% by weight.

14. A process for preparing polyester carbonate by melt transesterification as claimed in claim 1, wherein in formula I, R1 and R2 are independently H or C1- to C 12 -alkyl, and / or In formula II R3 is C6 to C 16 -alkylene.

15. A process for preparing polyester carbonates by melt transesterification as claimed in claim 1, wherein in formula I, R1 and R2 are independently H or C1- to C8-alkyl.

16. A process for preparing polyester carbonates by melt transesterification as claimed in claim 1, wherein in formula I, R1 and R2 are independently H or methyl.

17. A process for preparing polyester carbonates by melt transesterification as claimed in claim 1, wherein in formula I, R1 and R2 are independently Cl or Br, and / or In formula II R3 is a C1- to C1- 44 -alkylene, C5- to C 44 -cycloalkylene, C7- to C 44 -aralkylene or C6- to C 24 - arylene, diarylene or polyarylene.

18. The process for preparing polyester carbonate by melt transesterification as claimed in claim 1, wherein the molar ratio of the dicarboxylic acid of formula II to the diaryl carbonate of formula III is 1:1.05 to 1:1.

35.

19. Polyester carbonate having an OH end group content of <0.13% by weight, obtainable by the process as claimed in any one of claims 1 to 18.

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