WO2025098864A1 - Method for subsequently reducing the content of free bisphenol-a of polycarbonate and/or polyester carbonate moulding compounds - Google Patents

Abstract

The present invention relates to a method for reducing the content of free BPA of a moulding compound, comprising the steps of a) providing a moulding compound containing A) at least one polycarbonate and/or polyester carbonate each containing structure units derived from bisphenol-A, wherein the moulding compound is free of vinyl polymers and olefin polymers, which are each functionalised with OH-reactive groups and wherein the moulding compound contains either as component C at least one inorganic filler and/or at least one base organic colourant according to component D or wherein the polycarbonate and/or polyester carbonate according to component A is a recycled material b) melting and mixing the moulding compound at a temperature of 200 °C to 350 °C with a polymer B selected from the group consisting of vinyl polymers and olefin polymers, which are each functionalised with OH-reactive groups, c) solidifying the melt by way of cooling, wherein at the start of method step a) the moulding compound has a content of free bisphenol-A of at least 20 ppm. The invention also relates to a moulding compound which can be obtained by the method, and to a moulded body containing a moulding compound which can be obtained by the method.

Description

Process for the subsequent reduction of the content of free bisphenol A in

Polycarbonate and/or polyester carbonate molding compounds

The present invention relates to a process for reducing free bisphenol A from polycarbonate and/or polyester carbonate molding compounds, as well as a molding compound obtained by the process and a molded article containing such a molding compound.

Moulding compounds containing polycarbonate and/or polyester carbonate have been used for many years for numerous applications such as in the automotive industry, the electronics sector and the construction sector.

A molding compound is a polymer resin obtained, for example, by melt compounding (melt processing) polycarbonate with polymer blend partners and/or other components such as fillers and reinforcing materials, colorants, and stabilizers. These molding compounds are typically sold commercially in the form of granules and processed into molded articles, for example, by injection molding. By selecting the type and quantity of components, the overall property profile can be varied widely and adapted to specific requirements.

For many years, bisphenol A (BPA) has been by far the most widely used monomer building block in polycarbonates.

However, the European Union is striving to reduce the release of BPA into the environment. This applies to molding compounds (polymer granules) containing polycarbonate, as well as semi-finished products, i.e., molded articles containing polycarbonate and finished products. The proposed limit values for chemically unbound bisphenol A (free bisphenol A) in the molding compounds and semi-finished products are in the range of 10 to 150 ppm as a prerequisite for future marketing. For the purposes of the present invention, a proportion in ppm is understood to mean a weight proportion (mg/kg). In addition to reducing the content of free BPA in polycarbonate, alternative migration scenarios can be developed, although this would require extensive research.

Approaches to stabilization through optimized compositions of the molding compounds with reduced free BPA content are known from the state of the art.

WO 2018/122138 A1, for example, relates to a composition for producing a thermoplastic molding compound, wherein the composition contains or consists of the following components: A) 30 to 90 wt.% of at least one polymer selected from the group consisting of aromatic polycarbonate, aromatic polyester carbonate and aromatic polyester, B) 5 to 65 wt.% of rubber-modified vinyl (co)polymer produced in Bulk polymerization process which is free of epoxy groups, C) 0.5 to 10 wt.% of a block or graft polymer comprising structural elements derived from styrene and at least one vinyl monomer containing epoxy groups, D) 0 to 20 wt.% of one or more further additives, wherein component C has a weight ratio s of structural elements derived from styrene to vinyl monomer containing epoxy groups of 100:1 to 1:1. The composition has a low content of free bisphenol A.

However, free BPA can be formed in the molding compounds and molded articles due to degradation of the polymer chains during melt compounding and/or thermal shaping into molded articles, for example, in the injection molding process. During melt compounding, polycarbonate is melted and mixed with other components mentioned above in the melt. It has been shown that some components, such as inorganic fillers or inorganic pigments, contribute particularly to polymer chain degradation with BPA release. However, since these components otherwise impart beneficial properties to the molding compound, omitting these components or replacing them with other components is not desirable in most cases.

Furthermore, molding compounds without components critical for polymer chain degradation can also have a high content of free bisphenol, for example if they are a recycled material. Recycled material can be obtained, for example, when moldings are mechanically crushed and the fragments are melted back into granules. This is the case with post-consumer recycled material. Likewise, material that did not meet the required specifications directly after the production process can be remelted. This is referred to as post-industrial recycled material. For the purposes of the present invention, post-consumer recycled material and post-industrial recycled material are both generally referred to as recycled material.

Such a material was not only exposed to thermal stress during its life cycle during melt compounding to form the original molding compound and subsequent molding, but the recycling process represents a further step in which thermally induced BPA release can occur.

EP 0531008 A1 discloses the production of recycled compositions, wherein plastic scrap is made from a composition containing at least one polycarbonate, at least one polyester and at least one impact modifier, with an epoxy-functionalized copolymer consisting of at least one unsaturated epoxy compound and at least one The olefin is melted. This process eliminates the need for sorting the plastic scrap. However, there is no disclosure of any reduction in the proportion of free bisphenol A.

As explained, the release of bisphenol A cannot be avoided in all cases, so that molding compounds are available that contain an undesirably high proportion of BPA.

In order to enable the marketing of these products even in view of the expected regulatory restrictions, it was desirable to provide a process with which the proportion of free bisphenol A already present in such polycarbonate molding compounds can be reduced.

The aim is to provide a process for improving molding compounds with unacceptable BPA content, which can also be described as a repair process. The repair process is intended to be used for the subsequent reactive reduction of free BPA in polycarbonate molding compounds in order to achieve regulatory BPA limits.

It has surprisingly been found that a process for reducing the content of free BPA in a molding compound comprising the steps a) providing a molding compound containing

A) at least one polycarbonate and/or polyester carbonate each containing structural units derived from bisphenol-A, wherein the molding compound is free of vinyl polymers and olefin polymers which are each functionalized with OH-reactive groups b) melting and mixing the molding compound at a temperature of 200 °C to 350 °C with a polymer B selected from the group consisting of vinyl polymers and olefin polymers which are each functionalized with OH-reactive groups, c) solidifying the melt by cooling, wherein the molding compound has a free bisphenol-A content of at least 20 ppm at the beginning of process step a), achieves the stated object.

A method for reducing the content of free BPA in a molding compound is preferred, comprising the steps a) Providing a molding compound containing

A) at least one polycarbonate and/or polyester carbonate each containing structural units derived from bisphenol A, wherein the molding compound is free of vinyl polymers and olefin polymers which are each functionalized with OH-reactive groups and wherein the molding compound contains either as component C at least one inorganic filler and/or at least one basic organic colorant according to component D or wherein the polycarbonate and/or polyester carbonate according to component A is a recycled material b) melting and mixing the molding compound at a temperature of 200 °C to 350 °C with a polymer B selected from the group consisting of vinyl polymers and olefin polymers which are each functionalized with OH-reactive groups, c) solidifying the melt by cooling, wherein the molding compound has a free bisphenol A content of at least 20 ppm at the start of process step a).

For the present invention, it is therefore not important why the molding compound provided in step a) has an excessively high content of free BPA, i.e. whether the cause lies in ingredients that promote BPA release or in the thermal stress that a recycled material has experienced.

The molding compositions to which the process is to be applied have a free BPA content of preferably 20 ppm to 2000 ppm, more preferably 50 ppm to 1000 ppm, particularly preferably 100 to 1000 ppm, most preferably 200 to 1000 ppm.

Component A can be a recycled material or a mixture of different recycled materials. It is also possible that it is a mixture of one or more recycled materials and one or more non-recycled materials (virgin material).

The respective recycled material can come from post-industrial or post-consumer waste. Preferably, in step a) 0.2 to 10 parts by weight, more preferably 0.5-5 parts by weight of component B are used, based on 100 parts by weight of the molding composition.

In a further preferred embodiment, the molding compositions contain at least one inorganic filler as component C and/or at least one basic organic colorant as component D.

Preferably, the process should lead to a significant reduction in the content of free bisphenol A even with short reaction times, i.e., with a short residence time in the melt. The reduction of the bisphenol A content in the melt should work regardless of the processing method used.

It has been shown that the presence of a catalyst during step a) can significantly improve the reduction of free bisphenol A under otherwise identical process conditions. Alternatively, the catalyst can reduce the temperature and/or the residence time, both of which mean a reduced thermal stress on the polymer. Therefore, the presence of a catalyst is a preferred embodiment of the present invention. The process according to the invention thus again produces a molding compound, the molding compound produced having a lower content of free bisphenol A than the molding compound used.

However, the catalyst remains in the molding compositions obtained in this process after step b) and can therefore, in unfavorable cases, lead to undesirable side reactions, for example, if the resulting molding composition is remelted and processed into molded articles. Therefore, it was particularly desirable that the catalyst exert a minimal influence on the thermal stability of the molding compositions obtained in this process.

Even more preferably, the presence of the catalyst should have as little influence as possible on the hydrolysis resistance of the molding compound obtained in this process, i.e. the change in molecular weight when stored under warm and humid conditions.

Therefore, in a particularly preferred embodiment, the catalyst is selected from the group consisting of nitrogen-containing catalysts.

Also preferred are catalysts that react acidically or exhibit a moderate basicity. This corresponds to a pKa value range of -5.5 to <9.6. In a further preferred embodiment, in step a) 0.0005 to 0.07 parts by weight, particularly preferably 0.0015 to 0.05 parts by weight of the catalyst are used, based on 100 parts by weight of the molding composition.

Component A

Polycarbonates and/or polyestercarbonates according to component A which are suitable according to the invention are known from the literature or can be prepared by processes known from the literature (for the preparation of 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 polyester carbonates, e.g. DE-A

3 007 934).

Polycarbonates suitable according to the invention as component A are produced, for example, by reacting bisphenol A and optionally other dihydroxyaryl compounds (also referred to as aromatic diols, diphenols or bisphenols) and/or aliphatic diols with carbonic acid halides, preferably phosgene and/or with aromatic dicarboxylic acid dihalides, preferably benzenedicarboxylic acid dihalides, by the interfacial process, optionally using chain terminators, for example monophenols, and optionally using trifunctional or more than trifunctional branching agents, for example trihydroxyaryl or tetrahydroxyaryl compounds. Production via a melt polymerization process is also possible by reacting bisphenol A and optionally other dihydroxyaryl compounds and/or aliphatic diols with carbonic acid esters, for example diphenyl carbonate.

In addition to bisphenol A, dihydroxyaryl compounds suitable for the preparation of the polycarbonates suitable as component A according to the invention and/or for the preparation of the polyestercarbonates suitable as component A according to the invention are preferably those of the formula (2)

(2), where

A is a single bond, C1 to C5 alkylene, C2 to C5 alkylidene, C5 to C5 cycloalkylidene, -O-, -SO-, -CO-, -S-, -SO2-, C5 to Cn arylene, to which further aromatic rings, optionally containing heteroatoms, may be condensed, or a radical of formula (3) or (4)

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

R ⁵ and R ⁶ can be individually selected for each X ¹ , independently of each other hydrogen or Ci to Ce-

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 at least one atom X ¹ , R ⁵ and R ⁶ are simultaneously alkyl.

Preferred dihydroxyaryl compounds used in addition to bisphenol A are hydroquinone, resorcinol, dihydroxydiphenyls, bis-(hydroxyphenyl)-alkanes, bis-(hydroxyphenyl)-cycloalkanes, bis-(hydroxyphenyl)-sulfides, bis-(hydroxyphenyl)-ethers, bis-(hydroxyphenyl)-ketones, bis-(hydroxyphenyl)-sulfones, bis-(hydroxyphenyl)-sulfoxides, a-a'-bis-(hydroxyphenyl)-diisopropylbenzenes, phthalimidines derived from isatin or phenolphthalein derivatives, as well as their core-alkylated, core-arylated and core-halogenated compounds.

Further preferred dihydroxyaryl compounds used in addition to bisphenol A are 4,4'-dihydroxydiphenyl, 2,4-bis-(4-hydroxyphenyl)-2-methylbutane, 1, l-bis-(4-hydroxyphenyl)-p-diisopropylbenzene, 2,2-bis-(3-methyl-4-hydroxyphenyl)-propane, dimethylbisphenol A, 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, 1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-p-diisopropylbenzene and 1, l-bis-(4-hydroxyphenyl)-3,3,5- trimethylcyclohexane, as well as dihydroxyaryl compounds (I) to (III)

These and other suitable dihydroxyaryl compounds are described, for example, in US 3 028 635 A, 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, in DE 1 570 703 A, DE 2063 050 A, DE 2 036 052 A, DE 2 211 956 A and DE 3 832 396 A, in FR 1 561 518 A, in the monograph "H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964" and in JP 62039/1986 A, JP 62040/1986 A and JP 105550/1986 A.

These dihydroxyaryl compounds can be used individually or as any mixture. The dihydroxyaryl compounds are known from the literature or are available by known methods.

The polycarbonates used according to the invention preferably contain at least 20% by weight, more preferably at least 50% by weight, particularly preferably at least 80% by weight, most preferably 100% by weight, in each case based on the sum of all structural units derived from dihydroxyaryl compounds, of structural units derived from bisphenol A.

Suitable aliphatic diols used in addition to bisphenol A are selected from the group consisting of 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2-bis(4-hydroxycyclohexyl)propane, tetrahydro-2,5-furandimethanol, 2-butyl-2-ethyl-1,3-propanediol, 2-(2-hydroxyethoxy)ethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,2-dimethylpropane-1,3-diol, cyclobutane-1,1-diyldimethanol, 8-(Hydroxymethyl)-3-tricyclo[5.2.1.02,6]decanyl]methanol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, isosorbide and any mixtures thereof.

The polycarbonates used according to the invention preferably contain at least 20 wt.%, more preferably at least 50 wt.%, particularly preferably at least 80 wt.%, most preferably 100 wt.%, in each case based on the sum of all Structural units derived from dihydroxyaryl compounds and aliphatic diols, such structural units derived from bisphenol A.

Chain terminators suitable for the production of 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-butylphenol, p-iso-octylphenol, p-tert-octylphenol, p-dodecylphenol 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 mol% and 10 mol%, based on the molar sum of the dihydroxyaryl compounds used.

The thermoplastic, aromatic polycarbonates have average molecular weights (weight average M _w ) of preferably 15,000 to 50,000 g/mol, more preferably 20,000 to 35,000 g/mol, particularly preferably 24,000 to 32,000 g/mol, measured by GPC (gel permeation chromatography) using dichloromethane as the solvent. Calibration with linear polycarbonates (from bisphenol A and phosgene) of known molar mass distribution from PSS Polymer Standards Service GmbH, Germany, calibration according to method 2301-0257502-09D (from 2009 in German) from Currenta GmbH & Co. OHG, Leverkusen. The eluent is dichloromethane. Column combination of cross-linked styrene-divinylbenzene resins. Diameter of the analytical columns: 7.5 mm; length: 300 mm. Particle sizes of the column material: 3 pm to 20 pm. Solution concentration: 0.2 wt.%. Flow rate: 1.0 ml/min. Solution temperature: 30°C. Use of UV and/or RI detection. Due to the preferred molecular facets of component A, a particularly advantageous balance of mechanical and rheological properties is achieved in the compositions according to the invention.

The polycarbonates can be branched in a known manner, preferably by incorporating 0.05 to 2.0 mol%, based on the sum of the dihydroxyaryl compounds used, of trifunctional or more than trifunctional compounds, for example those with three or more phenolic groups. Linear polycarbonates are preferred, and linear polycarbonates based exclusively on bisphenol A are more preferred.

Both homopolycarbonates and copolycarbonates are suitable. For the preparation of copolycarbonates according to the invention according to component A, 1 to 25 wt.%, preferably 2.5 to 25 wt.%, based on the total amount of Dihydroxyaryl compounds, polydiorganosiloxanes with hydroxyaryloxy end groups, can be used. These are known (US Pat. No. 3,419,634) and can be prepared by processes known from the literature. The preparation of the polydiorganosiloxane-containing copolycarbonates obtained in this way is described, for example, in DE-A 3 334 782 and WO2015/052106 A2.

wobei Copolycarbonates prepared using diphenols of the general formula (4a) are also preferred:

where

R ⁵ represents hydrogen or C 1 -C 4 alkyl, C 1 -C 5 alkoxy, preferably hydrogen;

methoxy or methyl,

R ⁶ , R ⁷ , R ⁸ and R ⁹ each independently represent C 1 -C 4 alkyl or C 1 -C 6 aryl, preferably methyl or phenyl,

Y represents a single bond, SO2-, -S-, -CO-, -O-, C1- to C12-alkylene, C2- to C14-alkylidene, C1- to C18-arylene, which may optionally be condensed with further aromatic rings containing heteroatoms or a C1- to C12-cycloalkylidene radical which may be mono- or polysubstituted by C1- to C4-alkyl, preferably a single bond, -O-, isopropylidene or a C1- to C12-cycloalkylidene radical which may be mono- or polysubstituted by C1- to C4-alkyl,

V represents oxygen, C2- to C12-alkylene or C3- to C16-alkylidene, preferably oxygen or C5-alkylene, p, q and r each independently represent 0 or 1 when q = 0, W represents a single bond when q = 1 and r = 0, W represents oxygen, C2- to C12-alkylene or C5- to C16-alkylidene, preferably oxygen or C5-alkylene when q = 1 and r = 1, W and V each independently represent C2- to C12-alkylene or C5- to C16-alkylidene, preferably C5-alkylene, Z represents a C1- to C2-alkylene, preferably C2-alkylene, o represents an average number of repeating units of 10 to 500, preferably 10 to 100, and m represents an average number of repeating units of 1 to 10, preferably 1 to 6, more preferably 1.5 to 5. It is also possible to use diphenols in which two or more siloxane blocks of the general formula (4a) are linked to one another via terephthalic acid and/or isophthalic acid to form ester groups.

wobei RI für Wasserstoff, Ci- bis C4-Alkyl, vorzugsweise für Wasserstoff oder Methyl steht und insbesondere bevorzugt für Wasserstoff, Particularly preferred are (poly)siloxanes of the formulas (5) and (6)

where RI is hydrogen, Ci- to C4-alkyl, preferably hydrogen or methyl and particularly preferably hydrogen,

R2 independently represent aryl or alkyl, preferably methyl,

X represents a single bond, -SO2-, -CO-, -O-, -S-, C1- to C2-alkylene, C2- to C5-alkylidene or C2- to C5-arylene, which may optionally be condensed with further aromatic rings containing heteroatoms,

X preferably represents a single bond, C1- to C5-alkylene, C2- to C5-alkylidene, C5- to C12-cycloalkylidene, -O-, -SO- -CO-, -S-, -SO2-, particularly preferably X represents a single bond, isopropylidene, C5- to C12-cycloalkylidene or oxygen, and very particularly preferably isopropylidene, n represents an average number from 10 to 400, preferably 10 and 100, particularly preferably 15 to 50 and m represents an average number from 1 to 10, preferably from 1 to 6 and particularly preferably from 1.5 to 5.

wobei a in Formel (IV), (V) und (VI) für eine durchschnittliche Zahl von 10 bis 400, bevorzugt 10 bis 100 und besonders bevorzugt für 15 bis 50 steht. Dabei ist es ebenso bevorzugt, dass mindestens zwei gleiche oder verschiedene der Siloxanblöcke der allgemeinen Formeln (IV), (V) oder (VI) über Terephthalsäure und/oder Isophthalsäure miteinander unter Ausbildung von Estergruppen verknüpft sind. Likewise preferably, the siloxane block can be derived from the following structure

where a in formula (IV), (V) and (VI) represents an average number from 10 to 400, preferably 10 to 100 and particularly preferably 15 to 50. It is also preferred that at least two identical or different siloxane blocks of the general formulas (IV), (V) or (VI) are linked to one another via terephthalic acid and/or isophthalic acid to form ester groups.

It is also preferred if in formula (4a) p = 0, V is Cs-alkylene, r = 1, Z is Cs-alkylene, R ⁸ and R ⁹ are methyl, q = 1, W is Cs-alkylene, m = 1, R ⁵ is hydrogen or C1- to C4-alkyl, preferably hydrogen or methyl, R ⁶ and R ⁷ each independently of one another are C1- to C4-alkyl, preferably methyl and o is 10 to 500.

Copolycarbonates with monomer units of formula (4a) and in particular their preparation are described in WO 2015/052106 A2. Copolycarbonates with monomer units of formula (IV) and in particular their preparation are described in WO 2015/052106 A2.

Aromatic dicarboxylic acid dihalides for the preparation of polyester carbonates are preferably the diacid dichlorides of isophthalic acid, terephthalic acid, diphenyl ether-4,4'-dicarboxylic acid, and naphthalene-2,6-dicarboxylic acid. Particularly preferred are mixtures of the diacid dichlorides of isophthalic acid and terephthalic acid in a ratio of between 1:20 and 20:1.

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 production of polyester carbonates are their chlorocarbonic acid esters and the acid chlorides of aromatic monocarboxylic acids, which may optionally be substituted by C1 to C22 alkyl groups or by halogen atoms, as well as aliphatic C2 to C22 monocarboxylic acid chlorides.

The amount of chain terminators is 0.1 to 10 mol% in each case, based on moles of dihydroxyaryl compound in the case of phenolic chain terminators and on moles of dicarboxylic acid dichloride in the case of monocarboxylic acid chloride chain terminators.

In the production of polyester carbonates, one or more aromatic hydroxycarboxylic acids can additionally be used.

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

Branching agents which can be used are, for example, trifunctional or polyfunctional carboxylic acid chlorides, such as trimesic acid trichloride, cyanuric acid trichloride, 3,3'-,4,4'-benzophenonetetracarboxylic acid tetrachloride, 1,4,5,8-naphthalenetetracarboxylic acid tetrachloride or pyromellitic acid tetrachloride, in amounts of 0.01 to 1.0 mol% (based on 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, 1,3,5-tri-(4-hydroxyphenyl)-benzene, 1,1,1-tri-(4-hydroxyphenyl)-ethane, tri-(4-hydroxyphenyl)-phenylmethane, 2,2-bis[4,4-bis(4-hydroxyphenyl)cyclohexyl]propane, 2,4-bis(4-hydroxyphenylisopropyl)phenol, tetra-(4-hydroxyphenyl)methane, 2,6-bis(2-hydroxy-5-methylbenzyl)-4-methylphenol, 2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)propane, tetra-(4-[4-hydroxyphenylisopropyl]phenoxy)methane, 1,4-bis[4,4'-dihydroxytriphenyl)methyl]benzene, in amounts of 0.01 to 1.0 mol% based on the dihydroxyaryl compounds used. Phenolic branching agents can be initially introduced with the dihydroxyaryl compounds; acid chloride branching agents can be introduced together with the acid dichlorides. The proportion of carbonate structural units in the polyester carbonates can vary as desired. The proportion of carbonate groups is preferably up to 90 mol%, in particular up to 80 mol%, and particularly preferably up to 50 mol%, based on the sum of ester groups and carbonate groups. Both the ester and carbonate portions of the polyester carbonates can be present in the form of blocks or randomly distributed in the polycondensate.

The polycarbonates and polyestercarbonates can be used alone or in any mixture.

Polycarbonate based exclusively on bisphenol A is preferably used as component A. Based exclusively on bisphenol A means that no other diol other than bisphenol A is used to produce component A.

Component B

As component B, at least one polymer selected from the group consisting of vinyl polymers and olefin polymers, each containing OH-reactive groups, is used in the process according to the invention. These OH-reactive groups are preferably selected from the group consisting of carboxy, carboxylic anhydride, carbodiimide, and epoxy groups, more preferably from the group consisting of carboxylic anhydride groups and epoxy groups.

Epoxy groups are most preferably used as reactive groups. This allows for a significant reduction in the free bisphenol A content with short residence times of the components in the melt and/or at low temperatures.

Mixtures of different such polymers can also be used. The mixtures can comprise polymers with similar OH-reactive groups or polymers with different OH-reactive groups.

The vinyl polymers according to the invention containing functional groups are preferably (co)polymers of at least one monomer from the group of (meth)acrylic acid (C 1 to C 8) alkyl esters (such as methyl methacrylate, n-butyl acrylate, tert-butyl acrylate), vinyl aromatics (such as styrene, a-methylstyrene) and vinyl cyanides (unsaturated nitriles such as acrylonitrile and methacrylonitrile) with a further vinyl monomer containing OH-reactive groups.

Depending on the additional property requirements in the respective applications, different contents of OH-reactive groups are used. The molecular weight range of the suitable polymeric OH-reactive products also varies. Products with Molecular weights (Mw) between 1,500 and 150,000. The molecular weights refer to information provided by the manufacturers in their product data sheets based on their analytical methods

Epoxy groups are introduced, for example, by copolymerizing glycidyl methacrylate as an additional monomer together with the other monomers.

However, it is also possible to use vinyl homopolymers if the corresponding monomer has OH-reactive groups.

Such polymers are known and can be produced by radical polymerization, in particular by emulsion, suspension, solution or bulk polymerization.

Component B is also preferably a polyolefin containing OH-reactive groups.

Polyolefins are produced by chain polymerization, for example, by radical polymerization. Alkenes are used as monomers. An alternative name for alkenes is olefins. The monomers can be polymerized individually or as a mixture of different monomers.

Preferred monomers are ethylene, propylene, 1-butene, isobutene, 1-pentene, 1-heptene, 1-octene and 4-methyl-1-pentene.

The polyolefins can be semi-crystalline or amorphous, and linear or branched. The production of polyolefins has long been known to those skilled in the art.

The polymerization can be carried out, for example, at pressures of 1 to 3000 bar and temperatures between 20°C and 300°C, optionally using a catalyst system. Suitable catalysts include mixtures of titanium and aluminum compounds, as well as metallocenes.

By changing the polymerization conditions and the catalyst system, the number of branches, crystallinity, and density of the polyolefins can be varied within a wide range. These measures are also familiar to those skilled in the art.

OH-reactive groups are introduced into the polyolefins by copolymerizing vinyl monomers containing the OH-reactive group with the olefin, as described above, preferably by radical polymerization. A suitable vinyl monomer is, for example, glycidyl methacrylate. An alternative production option is the radical grafting of vinyl monomers containing OH-reactive groups starting from a polyolefin.

In both production processes, in addition to the vinyl monomers containing OH-reactive groups, additional vinyl monomers without functional groups, such as styrene, can also be used.

The polymers according to component B have average molecular weights (weight average M _w , measured by GPC (gel permeation chromatography) at room temperature against polystyrene as standard) of preferably at least 3000 g/mol, more preferably from 5000 to 200000 g/mol, particularly preferably 6000 to 150000 g/mol.

The solvent for the GPC measurement is selected so that component B dissolves well. A suitable solvent for vinyl copolymers such as polymethyl methacrylate is tetrahydrofuran.

If component B contains such a proportion of an olefinic monomer that the solubility at room temperature is no longer sufficient, the measurements are carried out as high-temperature GPC with ortho-dichlorobenzene as solvent and still against polystyrene as standard.

Particularly suitable vinyl polymers or olefin polymers according to component B are glycidyl methacrylate functionalized (co)polymers of the brand Joncryl™ (for example Joncryl™ 4468 and Joncryl™ 4400), maleic anhydride or glycidyl methacrylate functionalized (co)polymers of the brand XiBond™ (for example XiBond™ 160, 280, 370, 920) and the brand Lotader™ (for example Lotader™ AX 8900) as well as glycidyl methacrylate functionalized (co)polymers of the brand Igetabond™ (Igetabond 2C, 7L, 7M).

Component C

The molding compound used in the process according to the invention optionally contains at least one inorganic filler as component C. In the context of the present invention, the term "inorganic filler" is understood to mean any type of inorganic material, regardless of its chemical nature and origin, for example with regard to natural or synthetic origin, particle size and particle geometry, and in particular also regardless of its function in the molding compound used in the process according to the invention. Thus, "inorganic fillers" according to component C do not exclusively mean those inorganic materials that merely serve to fill the polymer for the purpose of cost dilution. Rather, the term "inorganic filler" includes in particular, inorganic functional fillers used as functional additives, such as reinforcing materials, pigments, flame retardants, etc.

Preferably, at least one inorganic filler selected from the group consisting of silica compounds, talc, wollastonite, kaolin, CaCO3, marble powder, titanium dioxide, and other inorganic pigments (inorganic colorants), Al(OH)3, AlO(OH), Mg(OH)2, BaSO4, micas, effect pigments based on metal oxide-coated micas or glass fibers, carbon black, expanded conductive graphite, glass fibers, hollow glass spheres, and solid glass spheres is used as component C in the molding compositions used in the process according to the invention. Preferred molding compositions contain titanium dioxide as a constituent of component C. In particularly preferred molding compositions, effect pigments based on metal oxide-coated micas are used as component C.

"Preferred" means, in the case of the fillers contained in the molding compound, that these fillers react particularly critically with polycarbonate and lead to a rather strong formation of free bisphenol A. The use of the process according to the invention is therefore particularly worthwhile for molding compounds containing such fillers.

The inorganic fillers according to component C can be fully or partially surface-modified with a sizing agent containing at least one or a combination of several organic substances, some of which may be chemically bound to the inorganic filler (for example, when acting as an adhesion promoter), while others may be free, i.e., physically wetting the inorganic filler. The free portion of this sizing agent, i.e., not chemically bound to the inorganic filler, can be separated by extraction, for example and preferably in dichloromethane, and subjected to analysis.

Suitable glass fibers according to component C are preferably made from E, A, or C glass. The average diameter of the glass fiber is preferably 5 to 25 μm, particularly preferably 6 to 20 μm, most preferably 7 to 15 μm. Chopped glass fibers have an average cut length of preferably 1 to 10 mm, preferably 2.0 to 7.5 mm, and particularly preferably 2.5 to 5.0 mm.

Particularly preferably, glass fibers with an aspect ratio, i.e. a quotient of average fiber length to average fiber diameter, of at least 100, particularly preferably of at least 200, especially preferably of at least 300 are used.

The previously mentioned geometric characteristics of the glass fibers (length, diameter and aspect ratio) are determined on the component C used (i.e. before the production of the inventive method of the molding composition used and in particular before carrying out the method according to the invention). Naturally, during the production of the molding compositions and molded articles by physical mixing processes, compounding or thermal shaping, a reduction in this aspect ratio due, for example, to shearing cannot be ruled out, so that the glass fibers of the molding compositions used in the method according to the invention and in the molded articles produced generally have a lower aspect ratio than originally determined for component C used.

Suitable quartz compounds include, for example, and preferably, those that contain more than 97% silicon dioxide (quartz) by weight. The grain shape is spherical and/or nearly spherical.

The quartz compounds are preferably finely divided (amorphous) quartz powders, which are produced by iron-free grinding followed by air separation from electrically melted silicon dioxide. It is also possible to use quartz powders made from processed quartz sand.

Commercially available fused silica flours include Amosil™ FW200 or Amosil™ FW600 from Quarzwerke GmbH (Germany). Commercially available quartz flours include Sikron™ SF300, Sikron™ SF600, Sikron™ SF800, Silbond™ SF600 EST from Quarzwerke GmbH (Germany), and Mikro-Dorsilit™ 120 from QUARZSANDE GmbH (Austria).

For the purposes of the invention, talc includes all talc-based fillers that a person skilled in the art associates with talc or talcum. In particular, all commercially available fillers whose product descriptions include the terms talc or talcum as characterizing features are suitable.

Mixtures of different mineral fillers based on talc can also be used.

According to the invention, mineral fillers are preferred which have a talc content according to DIN 55920 (version of 2006) of greater than 80% by weight, preferably greater than 95% by weight and particularly preferably greater than 98% by weight, based on the total mass of filler.

Talc is a naturally occurring or synthetically produced talc.

Pure talc has the chemical composition 3MgO 4SiO2 H2O and thus an MgO content of 31.9 wt.%, an SiO2 content of 63.4 wt.%, and a chemically bound water content of 4.8 wt.%. It is a silicate with a layered structure.

Naturally occurring talc materials generally do not have the ideal composition listed above, as they are partially replaced by other elements, are contaminated by partial replacement of silicon by, for example, aluminum and/or by intergrowths with other minerals such as dolomite, magnesite and chlorite.

The talc types used as component C are preferably characterized by particularly high purity, characterized by an MgO content of 28 to 35 wt.%, preferably 30 to 33 wt.%, particularly preferably 30.5 to 32 wt.%, and an SiCE content of 55 to 65 wt.%, preferably 58 to 64 wt.%, particularly preferably 60 to 62.5 wt.%. The particularly preferred talc types are further characterized by an AEOs content of less than 5 wt.%, particularly preferably less than 1 wt.%, in particular less than 0.7 wt.%.

Particularly advantageous and therefore preferred is the use of the talc according to the invention in the form of finely ground grades with an average particle size d50 of <10 pm, preferably <5 pm, more preferably <4 pm, and particularly preferably <3 pm. Larger average particle sizes have a detrimental effect on the mechanical properties of the molding compositions according to the invention and molded parts produced therefrom.

Furthermore, it is advantageous and preferred to use talc with an average particle size d50 of >0.2 pm, preferably >0.5 pm, more preferably >1 pm, and particularly preferably >2 pm. Smaller average particle sizes have a detrimental effect on the content of free bisphenol A in the molding compositions according to the invention and moldings produced therefrom.

In this respect, it is particularly advantageous to use talc with an average particle size d50 of 0.2 to 10 pm, preferably 0.5 to 5 pm, more preferably 1 to 4 pm, and particularly preferably 2 to 3 pm. Talc with these geometric particle dimensions can be produced, for example, and preferably, by wet grinding with the addition of, for example, and preferably, water. The average particle size d50 is the diameter, measured by sedimentation analysis according to ISO 13317-3 (version 2001-03), above and below which 50% by weight of the particles lie. Mixtures of talc types that differ in their average particle size d50 can also be used.

The talc types to be used according to the invention preferably have an upper particle or grain size d^, also measured by sedimentation analysis according to ISO 13317-3 (version 2001-03), of less than 30 pm, preferably less than 20 pm, particularly preferably less than 10 pm and especially preferably less than 8 pm.

With regard to the processing and production of molding compounds, the use of compacted talc is also advantageous. Compacted talc can be produced, for example, and preferably, by mixing the ground talc with water and optionally other processing aids, followed by compression under increased pressure. Due to the processing into the molding compound or molded articles, the talc used may have a smaller d ? or d 50 value in the molding compound or molded article than in the originally used form.

Kaolin, preferably calcined kaolin, can also be used as component C.

The main component of naturally occurring kaolin is kaolinite (AE OHfil&Os). Minor components are feldspars, mica, and quartz. In addition to this composition, kaolins can also be used that contain nacrite, dickite, halloysite, and hydrated halloysite instead of or in addition to kaolinite.

The calcined kaolin according to the invention is obtained by heat treating a kaolin at at least 500°C, preferably from 850°C to 1100°C. The hydroxyl groups that form part of the crystal structure of the kaolin are lost during this heat treatment, and the kaolin is transformed into calcined kaolin.

Furthermore, organically surface-modified wollastonites can also be used as inorganic fillers according to the invention, optionally. Organically surface-modified wollastonites preferably have a carbon content based on the wollastonite of greater than 0.1 wt. %, preferably 0.2 to 2 wt. %, more preferably 0.3 to 1 wt. %, most preferably 0.3 to 0.6 wt. %, determined by elemental analysis. Such wollastonites are commercially available, for example under the trade name Nyglos™ from NY CO Minerals Inc., Willsboro, NY, USA, and the type designations Nyglos™ 4 or Nyglos™ 5, or—in the case of surface-modified wollastonites—under the type designations Nyglos™ 4-10992 or Nyglos™ 5-10992.

Preferred wollastonites have an average aspect ratio, i.e. a ratio of the average length of the fiber to the average diameter, of >6, in particular >7 and an average fiber diameter of 1 to 15 pm, preferably 2 to 10 pm, in particular 4 to 8 pm.

Another suitable inorganic filler is calcium carbonate (CaCO3). Calcium carbonate occurs naturally in the form of minerals such as calcite, aragonite, and vaterite, and is a major component of limestone, chalk, and marble. Calcium carbonate can also be produced synthetically, which can be advantageous due to its higher purity. Calcium carbonate with an average particle diameter d50 of 0.1 to 5 pm is preferred.

Another suitable inorganic filler is aluminum hydroxide A1(OH)3. Aluminum hydroxide occurs naturally in the form of minerals such as gibbsite, bayerite, and nordstandite. Aluminum hydroxide can also be produced synthetically, which is due to the higher purity can be advantageous. Calcium carbonate with an average particle diameter d50 of 1 to 5 pm is preferred.

Another suitable inorganic filler is mica or metal oxide-coated mica. The mica can be naturally occurring or synthetically produced mica, the latter being preferred due to its typically higher purity. Mica obtained from nature is usually accompanied by other minerals. "Mica" in the case of naturally obtained inorganic filler also includes corresponding impurities in the stated amount. The mica is preferably muscovite-based, i.e., it preferably comprises at least 60 wt.%, more preferably at least 70 wt.%, even more preferably at least 85 wt.%, particularly preferably at least 90 wt.% muscovite, based on the total weight of the mica content.

In metal oxide-coated micas, the metal oxide coating preferably comprises one or more coating layers containing titanium dioxide, tin oxide, aluminum oxide, and/or iron oxide, with the metal oxide more preferably being iron(III) oxide (Fe2O3), iron(II,III) oxide (Fe3O4, a mixture of Fe2O3 and FeO), and/or titanium dioxide, particularly preferably titanium dioxide. Such metal oxide-coated micas are typically used as effect pigments.

The average particle size (d50) of the optionally metal oxide-coated mica, determined by means of laser diffractometry on an aqueous slurry of the pigment, is preferably 1 to 100 pm, for synthetic mica more preferably 5 to 80 pm and for natural mica more preferably 3 to 30 pm, generally for mica more preferably 3.5 to 15 pm, very particularly preferably 4.0 to 10 pm, extremely preferably 4.5 to 8.0 pm.

Commercially available suitable micas include products from the Tremica™ product group from HPF Minerals (Quarzwerke Group, Germany).

One or more pigments (inorganic colorants) can also preferably be used as component C or as part of component C.

A pigment is understood to be a coloring substance. Examples of such pigments are titanium dioxide, carbon black, bismuth pigments, metal oxides, metal hydroxides, metal sulfides, ultramarine, aquamarine, cadmium pigments, chrome pigments, sulfur-containing pigments such as cadmium red and cadmium yellow, iron cyanide-based pigments such as Prussian blue, oxide pigments such as zinc oxide, red iron oxide, black iron oxide, chromium oxide, titanium yellow, zinc-iron based brown, titanium-cobalt based green, cobalt blue, copper-chromium based black and copper-iron based black or chromium-based pigments such as chrome yellow and zinc oxide. Various titanates such as - TI - e.g., nickel-antimony titanate and chromium-antimony titanate in yellow pigments or spinel-type aluminates in green or blue pigments can also be used. These include, for example, cobalt-titanium spinels or cobalt-chromium spinels.

These are naturally occurring, synthetically produced or modified naturally occurring pigments or mixtures thereof.

The titanium dioxide pigments preferably have one of the crystal structure modifications rutile, anatase, or brookite. The preferred modification is rutile.

Titanium dioxide pigments according to the invention have a density (according to DIN EN ISO 787-10) of 3.6 to 4.4 g/cm ³ , preferably of 3.8 to 4.3 g/cm ³ , particularly preferably of 4.0 to 4.2 g/cm ³ .

The titanium dioxide pigments can be obtained in a known manner using the sulfate process or the chloride process from natural raw materials such as ilmenite, rutile ore, or TiO2 slag. The pigments can have an inorganic surface modification, preferably based on aluminum compounds. The proportion of titanium dioxide (according to DIN EN ISO 591) is preferably > 90 wt.%, particularly preferably > 92 wt.%, further preferably > 95 wt.%.

In a preferred embodiment, the pigments have an oil absorption (according to ISO787-5) of 5 to 50 g / 100 g pigment, more preferably of 10 to 25 g / 100 g pigment and particularly preferably of 12 to 18 g / 100 g pigment.

Component D

The molding compound used in the process according to the invention optionally contains at least one basic organic colorant as component D. Such colorants (or dyes) include, for example, phthalocyanine-derived dyes such as copper phthalocyanine blue and copper phthalocyanine green; condensed polycyclic dyes and pigments such as azo-based (e.g., nickel azo yellow), sulfur indigo dyes; perynone-based, perylene-based, quinacridone-derived, dioxazine-based, isoindolinone-based, and quinophthalone-derived derivatives; anthraquinone-based, heterocyclic systems, etc. Of these, cyanine derivatives, quinoline derivatives, anthraquinone derivatives, and phthalocyanine derivatives are preferred. Concrete examples of commercial products would be MACROLEX Blue RR®, MACROLEX Violet 3R®, MACROLEX Violet B® (Lanxess AG, Germany), Sumiplast Violet RR, Sumiplast Violet B, Sumiplast Blue OR, (Sumitomo Chemical Co., Ltd.), Diaresin Violet D, Diaresin Blue G, Diaresin Blue N (Mitsubishi Chemical Corporation), Heliogen Blue or Heliogen Green (BASF AG, Germany).

Component E

In a preferred embodiment, step a) of the process according to the invention is carried out in the presence of a catalyst. This allows the process to be carried out at moderate Temperatures and/or with short residence times of the molding compound and component B in the melt. Both are beneficial in reducing the risk of thermal damage to the molding compound.

In principle, various types of catalysts are suitable for catalyzing the reaction of OH groups with OH-reactive substances. These include acidic, nucleophilic, and basic catalysts. Suitable catalysts are preferably selected from the group of catalysts with the lowest possible interaction with the polycarbonate polymer chain.

The catalyst is preferably selected from the group consisting of tin compounds, boron compounds, phosphorus compounds, silicon compounds, germanium compounds, transition metal compounds (such as titanium compounds, manganese compounds, zirconium compounds and zinc compounds), antimony compounds, nitrogen compounds, sulfur compounds, alkali metal compounds, alkaline earth metal compounds and mixtures thereof, more preferably selected from the group consisting of phosphorus compounds, antimony compounds, transition metal compounds, nitrogen compounds and sulfur compounds and mixtures thereof.

In a further preferred embodiment, the catalyst does not contain aluminum oxide hydroxide. In a preferred embodiment, the catalyst is based on at least one transition metal cation

The phosphorus compounds are preferably phosphines, phosphates, and phosphonium compounds, more preferably tetraphenylphosphonium. The sulfur compounds are preferably sulfonates, more preferably triflate compounds.

In a preferred embodiment, the catalyst is a compound containing nitrogen, more preferably selected from the group of oxadiazoles, imidazolines, pyridines, ammonium phosphates,

More preferably, it is an acidic catalyst or nucleophilic catalyst.

Particularly preferred catalysts are those containing nitrogen groups; more preferably, the catalyst is based on an ammonium compound. Likewise, the catalyst preferably contains a conjugated -electron system and nitrogen.

Also preferred are catalysts that react acidically or exhibit a moderate basicity. This corresponds to a pKa value range of -5.5 to <9.6. Catalysts that have too high a basicity also catalyze undesirable degradation reactions such as hydrolysis or thermal oxidation.

In a further preferred embodiment, the process is based on an organic acid with free carboxyl groups.

Component F

As component F, one or more polymer additives and/or processing aids and/or further polymeric components can be present in the molding compound, preferably selected from the group consisting of flame retardants, anti-drip 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 as well as transesterification inhibitors), flow promoters, phase compatibilizers, polymeric blend partners other than components A and C, such as rubber-modified graft polymers or rubber-free vinyl (co)polymers, and organic dyes and pigments.

In a preferred embodiment, fatty acid esters, particularly preferably fatty acid esters of pentaerythritol or glycerol, are used as lubricants and mold release agents.

In a preferred embodiment, at least one member selected from the group consisting of sterically hindered phenols, organic phosphites and sulfur-based co-stabilizers is used as the stabilizer.

In a particularly preferred embodiment, at least one representative selected from the group consisting of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and tris(2,4-di-tert-butylphenyl)phosphite is used as stabilizer.

It is also possible for components according to component E to be added in step a) in the process according to the invention, for example to improve the stability of the process product, which is again a molding compound.

In such a preferred embodiment, a thermal stabilizer is added in step a), preferably a phosphorus-containing stabilizer, more preferably selected from the group consisting of organic phosphites, phosphonates or phosphates or mixtures thereof, particularly preferably selected from the group consisting of triisoctyl phosphate, triphenylphosphine, or organic phosphites such as tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl)(1,1'biphenyl)-4-4'-(diylphosphonite) and further reaction products of phosphorus trichloride with 1,1-biphenyl and 2,4-bis(1,1-dimethylethyl)phenol. The stabilizer is preferably added in an amount of 0.01 to 0.3 parts by weight based on 100 parts by weight of the molding compound used in step a).

Implementation of the method according to the invention

A molding compound is a product obtained by melt compounding and melt extruding a composition containing component A and optionally further components C, D, and F. An alternative term is compound.

A molding compound having a free BPA content of at least 20 ppm is used in step a) of the process according to the invention. The process according to the invention can subsequently be carried out with any molding compound having an increased free BPA content and with any thermal processing of the molding compound, for example, in a first alternative as melt compounding and in a second alternative during injection molding. The only essential requirement is that a molding compound containing at least one polycarbonate and/or polyester carbonate, each containing structural units derived from bisphenol A, wherein the molding compound has a free bisphenol A content of at least 20 ppm, is brought into contact with the polymer B in the melt, and mixing takes place.

In step a) of the process according to the invention, the molding compound is melted and mixed at a temperature of 200 °C to 350 °C with a polymer B as described above.

This step can be performed in conventional units such as single-screw extruders, co-rotating or counter-rotating twin-screw extruders, planetary roller extruders, internal kneaders, or co-kneaders, but also directly in the thermal processing step, such as injection molding. A twin-screw extruder or co-kneader is preferred.

Optionally, in step a), a catalyst according to component E can be added in addition to component B. This can further reduce the proportion of free BPA.

It is also possible that in step a) further components according to component F are added.

The temperatures are preferably between 220°C and 330°C, most preferably between 260°C and 320°C.

The residence time of the components in the melt is 10 seconds to 5 minutes, preferably 15 seconds to 3 minutes.

Step a) can be carried out under vacuum or at atmospheric pressure.

After step a), the melt is solidified by cooling in step b). This can be done, for example, in a water bath connected to the end of the extruder and through which the polymer melt is passed. Thus, the process according to the invention a molding compound is obtained which has a reduced content of free bisphenol A compared to the molding compound used in step a).

Likewise, at the end of the injection molding process, the resulting component can cool and harden in the injection molding tool.

After step b), the molding compound can also be mixed with other components in an additional thermal processing step, such as melt compounding, to obtain a molding compound that differs from the molding compound used in step a) not only in its free BPA content but also in its composition. Alternatively, the other components can also be added in step a).

The molding compound obtained in the first alternative of the process according to the invention, including all optional steps, is obtained, for example, in the form of granules. These granules can be converted into the final product (i.e., a molded body) using thermal processes in a subsequent step. This conversion can be carried out, for example, by injection molding, extrusion, and blow molding. Another form of processing is the production of molded bodies by deep drawing from previously produced sheets or films.

Irrespective of this, the reduction of free BPA is also achieved by the direct thermal conversion of a premix of granules of the molding compound and component B and optionally a catalyst (such as in the injection molding process) according to the second alternative of the process according to the invention.

Examples of molded articles are (extruded) films, profiles, housing parts of all kinds, e.g. for household appliances such as juicers, coffee machines, blenders; for office machines such as monitors, flat screens, notebooks, printers, copiers; panels, pipes, electrical installation ducts, windows, doors and other profiles for the construction sector (interior and exterior applications) as well as electrical and electronic parts such as switches, plugs and sockets and components for commercial vehicles, in particular for the automotive sector, interior fittings for rail vehicles, ships, aircraft, buses and other motor vehicles, body parts for motor vehicles, housings of electrical devices containing small transformers, housings for information processing and transmission equipment, housings and cladding for medical devices, massage devices and housings therefor, toy vehicles for children, flat wall elements, housings for safety devices, heat-insulated transport containers, molded parts for sanitary and bathroom equipment, cover grilles for fan openings and housings for gardening equipment.

Further embodiments of the present invention are listed below.

1. Process for reducing the content of free BPA in a molding compound comprising the steps a) providing a molding compound containing

A) at least one polycarbonate and/or polyester carbonate each containing structural units derived from bisphenol A, wherein the molding compound is free of vinyl polymers and olefin polymers which are each functionalized with OH-reactive groups b) melting and mixing the molding compound at a temperature of 200 °C to 350 °C with a polymer B selected from the group consisting of vinyl polymers and olefin polymers which are each functionalized with OH-reactive groups, c) solidifying the melt by cooling, wherein the molding compound has a free bisphenol A content of at least 20 ppm at the start of process step a).

2. Process according to embodiment 1, wherein the molding compound contains either as component C at least one inorganic filler and/or at least one basic organic colorant according to component D or wherein the polycarbonate and/or polyester carbonate according to component A is a recycled material

3. The method according to embodiment 2, wherein the recycled material is a post-consumer recycled material.

4. The method according to embodiment 2, wherein the recycled material is a post-industrial recycled material.

5. The process according to embodiment 1, wherein component A is polycarbonate based exclusively on bisphenol A.

6. Process according to one of the preceding embodiments, wherein in step a) 0.2-10 parts by weight, preferably 0.5 to 5 parts by weight of component B are used, based on 100 parts by weight of the molding composition. 7. Process according to one of the preceding embodiments, wherein component B has an average molecular weight Mw measured by gel permeation chromatography at room temperature against polystyrene as standard of at least 3000 g/mol.

8. Process according to one of the preceding embodiments, wherein component B has an average molecular weight Mw measured by gel permeation chromatography at room temperature against polystyrene as standard of 5000 g/mol to 200000 g/mol.

9. Process according to one of the preceding embodiments, wherein component B has an average molecular weight Mw measured by gel permeation chromatography at room temperature against polystyrene as standard of 6000 g/mol to 150000 g/mol.

10. Process according to one of the preceding embodiments, wherein the polymer B used in step a) contains OH-reactive groups selected from the group consisting of carboxylic anhydride groups and epoxy groups.

11. Process according to one of the preceding embodiments, wherein the polymer B used in step a) contains OH-reactive groups selected from the group consisting of maleic anhydride groups or glycidyl methacrylate.

12. Process according to one of the preceding embodiments, wherein the molding composition contains as component C at least one inorganic filler and/or at least one basic organic colorant according to component D.

13. Process according to one of the preceding embodiments, wherein the molding compound contains as component C at least one inorganic filler selected from the group consisting of titanium dioxide, talc, silica compounds and effect pigments based on metal oxide-coated micas or glass fibers.

14. Process according to one of the preceding embodiments, wherein the molding compound has a free bisphenol A content of 20 to 2000 ppm.

15. Process according to one of the preceding embodiments, wherein the molding compound has a free bisphenol A content of 50-1000 ppm.

16. Process according to any one of the preceding embodiments, wherein step a) is carried out in the presence of a catalyst. Process according to embodiment 16, wherein the catalyst is selected from the group consisting of phosphorus compounds, antimony compounds, transition metal compounds, nitrogen compounds, and sulfur compounds, and mixtures thereof. Process according to embodiment 16 or 17, wherein the catalyst has an acidic, basic, or nucleophilic catalytic effect. Process according to any one of embodiments 16 to 18, wherein the catalyst has a pKa value in the range from -5.5 to <9.6. Process according to embodiments 16 to 19, wherein the catalyst contains nitrogen. Process according to embodiments 16 to 20, wherein the catalyst is based on an ammonium compound. Process according to embodiments 16 to 21, wherein the catalyst contains a conjugated n-electron system and nitrogen. Process according to embodiments 16 to 19, wherein the catalyst is based on a tetraphenylphosphonium compound. Process according to embodiments 16 to 19, wherein the catalyst is based on at least one transition metal cation. Process according to embodiments 16 to 19, wherein the catalyst is based on a so-called triflate compound. Process according to embodiments 16 to 19, wherein the catalyst is based on an organic acid having free carboxyl groups. Process according to any of the preceding embodiments 16 to 26, wherein in step a) 0.0005 to 0.07 part by weight of the catalyst, based on 100 parts by weight of the molding composition, are used. 28. Process according to one of the preceding embodiments 16 to 26, wherein in step a) 0.0015 to 0.05 parts by weight of the catalyst are used, based on 100 parts by weight of the molding composition.

29. Process according to one of the preceding embodiments, wherein step a) is carried out in the presence of a stabilizer, preferably triisooctyl phosphate.

30. Process according to one of the preceding embodiments, wherein step a) is carried out in the presence of a phosphorus-containing stabilizer, preferably selected from the group consisting of organic phosphites, phosphonates or phosphates or mixtures thereof.

31. Process according to one of the preceding embodiments, wherein the process is carried out in a process unit selected from the group consisting of twin-screw extruders, planetary roller extruders, internal kneaders and film extruders.

32. Process according to one of the preceding embodiments, wherein the process is carried out in a process unit selected from the group consisting of twin-screw extruders and co-kneaders.

33. The method according to any one of the preceding embodiments, wherein the residence time in step a) is 10 seconds to 5 minutes.

34. The process according to any one of the preceding embodiments, wherein the residence time in step a) is 15 seconds to 3 minutes.

35. Molding compound obtainable by a process according to one of the preceding embodiments.

36. Shaped body comprising a molding composition obtained by a process according to any one of embodiments 1 to 34.

37. Extruded film comprising a molding compound obtained by a process according to any one of embodiments 1 to 34. Examples

Composition of the molding compound used M

Component A:

Linear polycarbonate based on bisphenol A, produced by the interfacial polymerization process, with a weight-average molecular weight _Mw of 28,000 g/mol (determined at room temperature by GPC in methylene chloride against a BPA-PC standard). Component A has a free bisphenol A content of 6 ppm, measured according to the method described below.

Components C and D:

In addition to component A, the molding compound contained inorganic pigments as component C and basic organic colorants as component D in a total proportion of 1 wt.%, based on the molding compound.

The molding compound M was produced by melt compounding of components A, C and D on a twin-screw extruder ZSK 40 MC at a temperature of 310°C.

Molding compound M had a free bisphenol A content of 418 ppm. This value is entered in all example tables from VI. VI means that no further thermal processing took place after the production of molding compound M.

In all further comparative experiments (V except VI) and examples according to the invention, either only the molding compound M or the molding compound M together with the components described below was subjected to melt compounding.

Further components used in the process according to the invention

Component B-l:

Joncryl™ 4468 (BASF, Germany): Modified styrene-acrylate copolymer with a weight fraction of glycidyl methacrylate (GMA) of 44%

Component B-2:

Joncryl™ 4400 (BASF, Germany):

Modified styrene-acrylate copolymer with a weight fraction of glycidyl methacrylate (GMA) of 29%-wt. Component B-3:

XiBond™ 920 (Polyscope, Netherlands):

Modified styrene-acrylate copolymer with a weight fraction of glycidyl methacrylate (GMA) of 20%

Component B-4:

XiBond™ 160 (Polyscope, Netherlands)::

Styrene-maleic anhydride copolymer. The maleic anhydride content corresponds to an acid number of 250 (mg KOH/g). Converted to content, the content (% wt.) MAH = 21.8

Component E

Catalysts of component E used in the process according to the invention

Component E-l: (4-(Dimethylamino)pyridine purity 99%) (Sigma-Aldrich, USA)

Component E-2 (1-phenylpyrrole purity 99%) (Sigma Aldrich, USA)

Component E-3 (2-(4-Biphenylyl)-5-Phenyl-1, 3, 4-Oxadiazole, purity 99%) (Sigma Aldrich, USA)

Component E-4 (2-amino-5-phenyl-,l,3,4-oxadiazole, purity 97%) (Sigma Aldrich, USA)

Component E-5 (2-phenyl-2-imidazoline, purity 96%) (Sigma Aldrich, USA)

Component E-6 (4-phenylpyridine, purity 99%) (Thermo Fisher Scientific, USA)

Component E-7 (4-Dimethylaminontipyridine, purity 98%) (Sigma Aldrich, USA)

Component E-8 (2-phenylimidazole, purity 98%) (Sigma Aldrich, USA)

Component E-9 (ammonium bisphosphate, purity 98%) (Sigma Aldrich, USA)

Component E-10 (Aluminum Trifluoromethanesulfonate, purity 99.9%) (Sigma Alrich, USA)

Component E-l l (Tetraphenylphosphonium bromide, purity 97%) (Sigma Aldrich, USA)

Component E-12 (2-methylimidazole, purity 99%) (Sigma Adrich, USA)

Component E-13 (Glutaric acid, purity 99%) (Sigma Aldrich, USA)

Component E-14 (zirconium acetylacetonate, purity 97%) (Sigma Aldrich, USA)

Component F

Component F-l: Triisooctyl phosphate, purity >98.5%) (Lanxess, Germany

Implementation of the method according to the invention

The molding compound M and the other components B, E, and F were processed on various units in a melt compounding process according to the weight proportions shown in Tables 1 to 7. The units used were both continuous and discontinuous process units. In the case of processing on For continuous processing, a ZSK26 MC 18 twin-screw extruder (Coperion GmbH, Stuttgart, Germany) (examples in Table 1) and a Rheomex PTWI 16 OS twin-screw extruder (Thermo Fisher Scientific Inc. Waltham, MA, USA) (examples in Table 2) were used. In the examples in Tables 1 and 2, temperatures of 300°C were used. In the case of discontinuous processing (Tables 3-7), a Xplore MC 15 HT mini-extruder (Xplore Instruments BV, Sittard, Netherlands) was used. In the examples in Tables 3-7, a melt temperature of 300°C was used. In order to also evaluate the influence of various process parameters on reactive extrusion, different screw geometries were used for compounding on the twin-screw extruders (Tables 1 and 2). For this reason, the corresponding references (comparative tests V2, V3, and V4) are always listed in Tables 1-7. In all cases, components M and B were pre-dried before being used in melt processing. The residence time in the melt ranged from 20 seconds (Tables 1 and 2) to 2 minutes (Tables 3-7).

The components were melted using thermal and mechanical energy, dispersed into each other, cooled at the extruder outlet and then granulated.

Test

To determine the content of free bisphenol A (abbreviated as [BPA]), samples of the molding compound used and the granules produced by the process according to the invention were dissolved in dichloromethane and reprecipitated with acetone. The precipitated polymer fraction was filtered off, and the filtrate was analyzed by high-pressure liquid chromatography with a UV detector (HPLC-UV) with an external standard. A C18 phase was used as the column material, and water and methanol in a gradient were used as the eluent.

The results are summarized in the following tables. The first column shows the proportion of free bisphenol A in the molding compound M used. The second column shows a value for the molding compound used. In this case, the molding compound was subjected to melt compounding under the same conditions regarding equipment, temperature, and residence time as in the tests shown in the next columns, but without the addition of components B, E, and F. Table 1:

Compositions used in the process according to the invention

Example VI is the starting granulate (molding compound M) used for the experiments relevant to the invention. The material exhibits a free BPA content of 418 ppm in the granulate. The other examples and comparative examples were subjected to an additional thermal processing step to demonstrate the inventive effect of subsequent reduction of high free BPA contents. In principle, each additional processing step increases the free BPA content through thermal degradation. The more critical the formulation composition, the more pronounced this degradation tendency and thus the increase in the free BPA content during thermal processing steps.

For both the examples and the comparative examples, a molding compound with a critical BPA content was used. This compound contained a mixture of components C and D, which resulted in a high initial level of free BPA in the molding compound.

The data in Table 1 show that melt processing of critical product formulations leads to an increase in the free BPA content. The use of copolymers according to component B, which contain OH-reactive groups (such as epoxides), leads to a significant reduction in the free bisphenol A content in the process according to the invention compared to the molding compound M (VI). This is the case even though melt compounding entails additional thermal stress, which, without the addition of component B, leads to a further increase in the free bisphenol A content (V2). Table 2:

Compositions used in the process according to the invention

The data in Table 2 again demonstrate that the addition of copolymers containing epoxy-functionalized groups as OH-reactive component B leads to a reduction in free BPA, despite additional thermal stress. In Comparative Example C3 without component B, the melt compounding step leads to an increase in the BPA content. The addition of a suitable catalyst significantly improves the effectiveness and further reduces the free BPA content (Examples 14-17).

Table 3:

Compositions used in the process according to the invention

The data in Table 3 show that the addition of copolymers containing epoxy-functionalized groups as OH-reactive component B and suitable catalysts results in a significant reduction in free BPA compared to the unadditized variant, even in a batch process. Especially with longer residence times in the melt, as in this case when using the batch process unit, an advantage from using a catalyst is not necessarily to be expected, since a catalyst could also accelerate undesirable chemical side reactions. The use of additional stabilizers according to component F further increases the effectiveness of the catalysts. Table 4:

Compositions used in the process according to the invention

Tabelle 6: Table 5: Compositions used in the process according to the invention

Table 6:

Compositions used in the process according to the invention

The data in Tables 4, 5, and 6 show various catalysts which, together with component B, further reduce the proportion of free bisphenol. Various types of catalysts are suitable for catalysis. The catalysts listed in Tables 4-6 can be classified into the categories of acidic, basic, and nucleophilic based on their mode of action. The suitability of a suitable catalyst cannot be limited solely to the lowest possible residual BPA content in the molding compound. Other influencing factors that determine the suitability of the respective catalysts must be considered. Further aspects for the potential suitability of suitable catalysts include the undesirable catalysis of chemical reactions (e.g., aging mechanisms in the respective applications of the molding compound), availability and cost of the catalysts, as well as product safety and regulatory aspects.

Table 7:

Die Daten in Tabelle 7 zeigen den Einfluss geeigneter Katalysatoren und Stabilisatoren auf dieCompositions used in the process according to the invention

The data in Table 7 show the influence of suitable catalysts and stabilizers on the

Reactivity of anhydride-functionalized copolymers according to component B for the reduction of free BPA

In general, epoxy-containing copolymers are more effective than anhydride-functionalized copolymers when the process residence times are short.

Claims

Patent claims 1. A method for reducing the content of free BPA in a molding compound comprising the steps of a) providing a molding compound containing A) at least one polycarbonate and/or polyester carbonate each containing structural units derived from bisphenol A, wherein the molding compound is free of vinyl polymers and olefin polymers which are each functionalized with OH-reactive groups and wherein the molding compound contains either as component C at least one inorganic filler and/or at least one basic organic colorant according to component D or wherein the polycarbonate and/or polyester carbonate according to component A is a recycled material b) melting and mixing the molding compound at a temperature of 200 °C to 350 °C with a polymer B selected from the group consisting of vinyl polymers and olefin polymers which are each functionalized with OH-reactive groups, c) solidifying the melt by cooling, wherein the molding compound has a free bisphenol A content of at least 20 ppm at the start of process step a). 2. Process according to claim 1, wherein component A is polycarbonate based exclusively on bisphenol A. 3. Process according to claim 1 or 2, wherein in step a) 0.2-10 parts by weight of component B are used relative to 100 parts by weight of the molding composition. 4. Process according to one of the preceding claims, wherein component B has an average molecular weight Mw measured by gel permeation chromatography at room temperature against polystyrene as standard of at least 3000 g/mol. 5. Process according to one of the preceding claims, wherein the polymer B used in step a) contains OH-reactive groups selected from the group consisting of carboxylic anhydride groups and epoxy groups. 6. A process according to any one of the preceding claims, wherein the molding compound as component C contains at least one inorganic filler and/or at least one basic organic colorant according to component D. 7. A process according to any one of the preceding claims, wherein the molding compound has a free bisphenol A content of 20 to 2000 ppm. 8. A process according to any one of the preceding claims, wherein step a) is carried out in the presence of a catalyst. 9. The process according to claim 8, wherein the catalyst is selected from the group consisting of phosphorus compounds, antimony compounds, transition metal compounds, nitrogen compounds and sulfur compounds and mixtures thereof. 10. Process according to one of the preceding claims 8 or 9, wherein in step a) 0.0005 to 0.07 parts by weight of the catalyst are used, based on 100 parts by weight of the molding composition. 11. Process according to one of the preceding claims, wherein step a) is carried out in the presence of a stabilizer, preferably triisooctyl phosphate. 12. The process according to any one of the preceding claims, wherein the process is carried out in a process unit selected from the group consisting of twin-screw extruders, planetary roller extruders, internal kneaders and film extruders. 13. A process according to any one of the preceding claims, wherein the residence time in step a) is 10 seconds to 5 minutes. 14. Molding composition obtainable by a process according to any one of the preceding claims. 15. A molded body containing a molding compound obtained by a process according to any one of claims 1 to 13.