EP1268604A1

EP1268604A1 - Polyester carbonate and a data carrier therefrom

Info

Publication number: EP1268604A1
Application number: EP01913862A
Authority: EP
Inventors: Friedrich-Karl Bruder; Wilfried Haese; Rolf Wehrmann; Peter Fischer; Marco Roelofs; Silke Kratschmer
Original assignee: Bayer AG
Current assignee: Covestro Deutschland AG
Priority date: 2000-03-23
Filing date: 2001-03-12
Publication date: 2003-01-02
Also published as: WO2001070847A1; US20030104234A1; JP2003529637A; AU3929001A; CN1418233A; CN1235936C

Abstract

The invention relates to a machine readable data carrier comprising a substrate consisting of a copolyester carbonate which contains units on the basis of hydrogenated dimer fatty acids. The inventive data carrier offers the possibility to record data when the data density is higher.

Description

PO YESTER CARBONATES AND DATA CARRIERS THEREOF

The invention relates to new polyester carbonates, machine-readable data carriers containing them and further shaped articles containing them.

Polycarbonate is preferably used in machine-readable data carriers such as compact discs. For this application it is important that the materials have high transparency, low affinity for water, good heat resistance and low birefringence. The increase in data density is becoming established and new storage technologies such as CD-ROM (read only), CD-R (recordable), CD-RW

(rewritable), DVD (digital versatile disk) and MO disks (magnetooptical) and also place higher demands on the substrate materials.

With the formats described above, such as the CD-ROM, the information is embossed in the form of so-called pits directly into a transparent thermoplastic material such as bisphenol A (BPA) polycarbonate. The surface is then coated with a reflective metal film and the digital information, which is encoded by the length and position of the pits, is optically read out by a focused laser beam of low power (approx. 0.5mW). The stored information can no longer be changed here (read only format).

The function of a write-once format, such as the CD-R, is to write permanent markings in a thin film on a disc with a focused laser beam (up to 40 mW). The changes in the optical properties (absorption, reflectivity) generated in this way can be detected with a reading laser. Since irreversible processes take place, the information can only be saved once and then not overwritten (WORM principle, write once, read many).

Rewritable are particularly interesting for the computer industry

Media. There are two main principles currently in use: magneto-optical (MO) systems and phase change (PC) systems. In MO storage, a bit is stored as a magnetic domain approximately 1 μm in size, with either up or down magnetization of a vapor-deposited layer (generally made of amorphous alloys of rare earth and transition metals). The magnetization states are obtained by heating above the Curie temperature T _c and then cooling in a variable magnetic field. The information stored in this way is optically read out by the rotation of the plane of polarization of the light in the magnetic thin layer. This so-called magneto-optical Kerr effect typically leads to a rotation of the polarization of less than 0.5 degrees. Birefringent substrate materials also lead to a particularly disruptive one here

Change in polarization of light. That is why substrate materials with low birefringence are particularly important in MO systems.

With phase change materials, the information is stored in areas with different phases - typically amorphous or crystalline. Alloys or compounds of tellurium are usually used as the information layer, in which the glass transition temperature is close to the crystallization temperature. The film can be locally converted from a crystalline to an amorphous state by heating to above the melting point with a short focused laser pulse and rapid cooling. In comparison to the crystalline state, the reflectivity changes, which is optically detected with a laser.

In addition, there are tight tolerances for the geometry of the optical beam path for the writing and reading process. Changes in environmental conditions, such as temperature and humidity, can cause the disc to warp, which has a negative impact on the writing and reading process. The water absorption of the substrate materials leads to swelling and thus to a volume expansion, which manifests itself in a bending of the disk, especially in the case of asymmetrically structured storage formats. Low polymer water absorption is therefore another important property that needs to be realized. In the course of new developments in optical data carriers, the requirements for the carrier material are becoming increasingly demanding and require targeted new material development, for example with the aim of lower birefringence and less water absorption, in particular for the shorter writing and reading wavelengths to be expected in the future, which pose new challenges.

However, low birefringence and low water absorption are not the only important properties for the substrate materials of optical data media, the optimal combination of other properties is required, such as high transparency, heat resistance, flowability, toughness, high purity, low density, low inhomogeneities or particle proportions, and above all low raw material and manufacturing costs.

The materials currently proposed for these applications fail to meet one or more of these requirements and there is therefore a need for new ones

Materials for higher storage densities.

Polyester carbonates from linear or cyclic difunctional aliphatic carboxylic acids, bisphenols and carbonate precursors are described, for example, in EP 433 716 A, US 4 983 706 and US 5 274 068, which describe different processes for their

Describe synthesis. The person skilled in the art is aware that the incorporation of dicarboxylic acids leads to a reduction in the glass transition temperature and to an increase in the flowability. For use as substrate materials, however, the reduction in the glass temperature means that the usability of the discs is restricted, since this reduces their climate resistance. In addition, due to the polar ester groups, these products have a high water absorption, which is unfavorable for use in optical data storage media. As EP 433 716 A teaches, the carboxylic acids known for polyester carbonates can only be incorporated in significant amounts in the phase interface process by means of an elaborate multi-stage procedure. In addition, polyester carbonates, in particular from linear and longer-chain dicarboxylic acids, have an undesirable tendency to crystallize, which has a particularly disruptive effect on the very slow cooling, which can be necessary for molding the finest structures and reducing the process-related birefringence.

Dimer fatty acids as possible acid building blocks in polyester carbonates are listed, for example, in DE 43 06 961 A, US 5 134 220 and EP 443 058 A. There is no precise definition of the acids to be used. However, thermooxidative problems occur with non-hydrogenated dimer fatty acids. In addition, the current commercial products contain more than 3 mol% of three- and polybasic carboxylic acids, which leads to a high zero viscosity, which is undesirable when molding microstructures such as pits or grooves. For this reason, these polyester carbonates have so far generally not been regarded as suitable for substrates for optical data memories.

The object of the invention is to provide machine-readable data carriers for increased data densities which do not have the disadvantages mentioned above, in particular have improved optical properties and can be easily produced.

The object is achieved by data carriers containing a resin made of polyester carbonates with recurring, bifunctional structural units A according to formula (I),

in which

D represents a mixture of divalent hydrocarbon radicals which have 30 to 42 carbon atoms, preferably 32 to 38, particularly preferably 34 carbon atoms atoms. D corresponds substantially to formula la and / or Ib and / or Ic and / or Id and / or Ie.

in which

Ej, E ₂ , E ₃ and E ₄ in formula Ic and Id for each of the substituents - (CH ₂ ), -, - (CH ₂ ), -, - (CH ₂ ) _k CH ₃ and - (CH ₂ ) ιCH ₃ stand and a, b, c, d, e, f, g, h, i, j, k, l, m, n, o and p independently represent an integer between 1 and 10 It was found that substrates made from polyester carbonates according to the invention with recurring, bifunctional structural units, derived from aromatic bisphenols and hydrogenated dimeric fatty acids with a high proportion of difunctional acids, surprisingly have a particularly low water absorption, surprisingly low birefringence, very low tendency to crystallize , low refractive index, good fluidity and low density.

The high glass transition temperature of homopolycarbonates from certain bisphenols such as l, l-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane or 6,6'-dihydroxy-3,3,3 ', 3'-tetramethyl-l, l'-spiro (bis) -indan can be efficiently reduced to an acceptable level for flowability and heat resistance in optical data carriers by cocondensation with very low molar proportions of the acids to be used according to the invention.

The substrates for data carriers made of the new polyester carbonates also have high transparency, good mechanical properties, especially at low temperatures, and high flowability.

Hydrogenated dimeric fatty acids in the context of this invention are acids which can be obtained by dimerizing unsaturated monobasic fatty acids having 16 to 22 carbon atoms and then hydrogenating them. The required acids can be obtained, for example, from plant or animal sources. Synthesis and properties are eg ^th ed Encyclopedia of Chemical Technology, Vol 8, 4, John Wiley & Sons.. 1993, pages 223-237 set.

In addition to the structural elements mentioned in formula I, they can contain small amounts of unsaturated aliphatic groups. Dimer fatty acids with an iodine number of less than about 15 are preferred. It may also contain a small amount of monobasic and polybasic fatty acids. Products with very small proportions of these components, in particular with small proportions of tri- and polybasic acids, are particularly suitable for the production of the polyester carbonates according to the invention. Dimer fatty acids with a proportion of tri- and polybasic acids of less than about 1.5%, as determined by gas chromatography, are therefore preferred. The invention also includes mixtures of dimeric fatty acids with other difunctional carboxylic acids with 4 to 40 carbon atoms such as adipic acid, sebacic acid, α, ω-dodecanedicarboxylic acid, terephthalic acid, ice or trans-9-octadecen-α, ω-dicarboxylic acid or hydroxycarboxylic acids with 4 up to 40 carbon atoms such as salicylic acid or p-

Hydroxybenzoic.

For the purposes of the invention, the dimer fatty alcohols obtained from dimer fatty acids by reduction can also be used and converted to polycarbonates or mixtures or esters of dimer fatty alcohols with dimer fatty acids to polyester carbonates.

At least one of the other bifunctional structural units of the formula (II) different from A is preferably used as the bi-functional structural unit B.

O-R-O-C- (II), II O used,

wherein the radical -ORO- stands for any diphenolate radicals in which -R- is an aromatic radical having 6 to 40 carbon atoms, which can contain one or more aromatic or condensed aromatic nuclei, optionally containing heteroatoms, and optionally with Cι -Cι ₂ alkyl radicals or halogen is substituted and may contain aliphatic radicals, cycloaliphatic radicals, aromatic nuclei or heteroatoms as bridge members. The bifunctional structural units B are particularly preferably derived from diphenol compounds of the formulas (ffia) to (IIIc)

in the

Z _\ and Z ₂ independently of one another each for a divalent radical -C (R ₂ R ₂ ) -, -O-,

-S-, -N (R ₂ ) -, -N - ((R ₂ ) C (= O) -,

R ₂ independently of one another, each for a C 1 to C ₁₂ alkyl radical, preferably C ₁ to C ₃ alkyl radical, particularly preferably methyl, a C ₆ to C ₉ aryl, preferably phenyl radical, a C ₇ to C ₁₂ aralkyl -, preferably phenyl to C alkyl, particularly preferably benzyl, hydrogen, halogen, preferably chlorine or

Bromine, U and V independently of one another for an integer from 0 to 3, preferably and 2,

W and X independently of one another for an integer from 0 to 3, preferably 0, and

Y represents a single bond, a C to C ₆ alkylene, C ₂ to C ₅ alkylidene, C ₅ to C ₆ cycloalkylidene radical which can be substituted by Ci to C ₆ alkyl, preferably methyl or ethyl radicals, a C ₆ to C ₂ arylene residue, which may optionally be condensed with further aromatic rings containing heteroatoms,

stand.

Examples of these diphenols of the formula (purple), (Illb) and (IIIc) are 4,4'-dihydroxydiphenyl, 2,2-bis (4-hydroxyphenyl) propane, 2,4-bis (4- hydroxyphenyl) -2-methylbutane, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, l, l-bis (3-methyl-4-hydroxyphenyl) cyclohexane, 2,2-bis - (3-chloro-4-hydroxyphenyl) propane, bis (3,5-dimethyl-4-hydroxyphenyl) methane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane , 2,4-bis (3,5-dimethyl-4-hydroxyphenyl-2-methylbutane, 2,2, -bis (3,5-dichloro-4-hydroxyphenyl) propane, 2,2-bis - (3,5-dibromo-4-hydroxyphenyl) propane, l, l-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and 1,1-bis (4-hydroxyphenyl) cyclohexane , 6,6 ^, -Dihydroxy-3,3,3 ', 3'-tetramethyl-l, r-spiro (bis) -indan, l- (p-hydroxyphenyl) - l, 3,3-trimethyl-5-indanol and 9,9-bis (4-hydroxyphenyl) fluorene.

Preferred diphenols of the formula (purple), (Illb) and (fflc) are 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) - propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 6,6'-dihydroxy-3,3,3 ', 3'-tetramethyl-l, r-spiro (bis) -indane, 9,9-bis- (4-hydroxyphenyl) fluorene, 1, 1 -B is- (3-methyl-4-hydroxyphenyl) -cyclohexane, 1 - (p-hydroxyphenyl) -

1, 3,3-trimethyl-5-indanol and 4,4 '(m-phenylenediisopropylidene) diphenol. The diphenols can be used individually or as a mixture of several diphenols for the production of the substrates according to the invention.

The carbonate structural units of the formula (II) are particularly preferably derived from

1, 1 -B i s- (4-hydroxypheny l) -3, 3,5 -trimethy lcyclohexane.

In addition, bifunctional monophenols such as resorcinol, hydroquinone or their derivatives substituted one or more times by C ₁ to C ₂ alkyl, C ₆ to C ₉ aryl or C ₇ to C] aralkyl can also be used for the preparation of the substrates according to the invention ,

Preferred polyester carbonates according to the invention are those which have 0.5 to 49 mol%, preferably 2 to 40 mol%, particularly preferably 5 to 20 mol%, based on 100 mol% of the bifunctional structural units A and B, structural units A.

The substrates according to the invention can be produced by the known three methods (cf. H. Schnell "Chemistry and Physics of Polycarbonates", Polymer review, Volume IX, page 27 ff; Interscience Publishers, New York 1964, and DE 1495 626 A, DE 22 32 877 A, DE 27 03 376 A, EP 274 544 A, DE 30 00610 A, DE 38 32 396 A).

1. After the solution process in disperse phase, so-called "two-phase interface process"

The diphenols and bifunctional acids to be used are dissolved in an aqueous alkaline phase. For this purpose, the chain terminators required for the production of the polyester carbonates according to the invention are used in amounts of 1.0 to 20 mol%, based on moles of diphenol plus, according to the invention

Acid, dissolved in an aqueous alkaline phase, preferably sodium hydroxide solution, or to this and an inert organic phase, added in bulk. Then in the presence of an inert, preferably polycarbonate-dissolving, organic phase is reacted with phosgene. The reaction temperature is between 0 ° C and 50 ° C.

The addition of the necessary chain terminators, branching devices and according to the invention

Acids can also occur during the phosgenation or as long as chlorocarbonic acid esters are present in the synthesis mixture, in bulk, as a melt, as a solution in alkali or inert organic solvents.

The reaction can be accelerated by catalysts such as tertiary amines or onium salts. Tributylamine, triethylamine and N-ethylpiperidine and tetrabutylammonium, tetrathylammonium and N-ethylpiperidinium salts are preferred.

In addition to or instead of the diphenols, their chlorocarbonic acid esters and / or bischlorocarbonic acid esters can also be used or added during the synthesis. Instead of dimer fatty acids, their acid chlorides can also be used. Suitable solvents are, for example, methylene chloride, chlorobenzene, toluene and mixtures thereof.

2. According to the solution process in a homogeneous phase, also called "pyridine process"

Here, the diphenols and acids according to the invention are dissolved in organic bases such as pyridine, optionally with the addition of further organic solvents, then, as described under 1., the chain terminators and branching agents required for the preparation of the polyester carbonates according to the invention are optionally added.

Then it is reacted with phosgene. The reaction temperature is between 10 and 50 ° C. Suitable organic bases apart from pyridine are, for example, triethylamine, tributylamine, N-ethylpiperidine and N, N-dialkyl-substituted anilines, such as N, N-di- methylaniline. Suitable solvents are, for example, methylene chloride, chlorobenzene, toluene, tetrahydrofuran, 1,3-dioxolane and mixtures thereof.

In addition to the diphenols, up to 50 mol%, based on the phenols used, of their bischlorocarbonic acid esters can also be used. Some or all of the fatty acids according to the invention can be replaced by their acid chlorides. The necessary chain terminators, branching agents and acids according to the invention can also be added during the phosgenation or as long as chlorocarbonic acid esters are present in the synthesis mixture, in bulk, as a melt or as a solution in inert organic solvents.

Processes 1 and 2 isolate the polyester carbonates according to the invention in a known manner. Suitable work-up methods are, in particular, the precipitation, the spray drying and the evaporation of the solvent in vacuo.

According to the melt transesterification process

In the melt transesterification process, the molecular weight is condensed with the addition of diphenyl carbonate in stoichiometric amounts or in excess of up to 40% to a diphenyl melt / fatty acids with constant removal of phenol and, if appropriate, the excess diphenyl carbonate. This process is carried out using conventional catalysts such as alkali metal ions, e.g. Li, Na, K, transition metal compounds, e.g. those based on Sn, Zn, Ti or nitrogen or phosphorus bases, preferably ammonium and phosphonium salts, preferably phosphonium halides or phenolates, as a one-stage or two-stage process, that is to say with a possible separate condensation of the oligomers and the polymer.

Instead of the acids to be used according to the invention, their aromatic or aliphatic esters, for example methyl, ethyl, isopropyl or phenyl esters, can be used. In a known manner, chain terminators and / or branching agents can also be used for the production of the polyester carbonates according to the invention. The corresponding chain terminators and / or branching devices are known, inter alia, from EP 335 214 A and DE 30 07 934 A and EP 411 433 A, DE 43 35 440 A and

EP 691 361 A is known. In addition, the branching agents and / or chain terminators can be replaced in whole or in part by dimer fatty acids with a higher content of tri- and / or monofunctional carboxylic acids.

Furthermore, the substrates made from the polyester carbonates according to the invention can be mixed with various thermoplastic polymers in a weight ratio of 2:98 to 98: 2 and used as blends.

The polyester carbonates according to the invention have average molecular weights M _w (weight average, determined by gel chromatography after prior calibration

Bisphenol-A-PC) of at least 6,000, preferably between 7,000 and 40,000, particularly preferably between 9,000 and 30,000.

Before, during or after their processing, the substrates for the production of the data carriers according to the invention can contain the additives customary for thermoplastic polycarbonates, such as stabilizers, for example thermal stabilizers, such as organic phosphites, optionally in combination with monomeric or oligomeric epoxides; UV stabilizers, in particular those based on nitrogen-containing heterocycles, such as triazoles; optical brighteners, flame retardants, in particular fluorine-containing, such as perfluorinated salts of organic acid, polyperfluoroethylene, salts of organic sulfonic acids and combinations thereof; mold release agents; Flow aids; Fire retardants; Colorants; pigments; antistatic agents; Fillers and reinforcing materials, divided minerals, fibrous materials, for example alkyl and aryl phosphites, phosphates, phosphines, low molecular weight carboxylic acid esters, halogen compounds, salts, chalk, quartz, inorganic or organic nanoparticles, glass and carbon fibers are added in the usual amounts. The data carriers according to the invention or other molded bodies can be produced in a known manner by injection molding or injection molding on known machines.

Structural units A and B containing polyester carbonates according to the invention which are derived from l, l-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and 0.5 to 49 mol%, preferably 2 to 40 mol%, particularly preferably 10 Up to 25 mol%, based on 100 mol% of the bifunctional structural units A and B, containing bifunctional ester structural units A, are particularly suitable for producing the data carriers according to the invention owing to their low rheo-optical constant C _R , but also their very low yellowness index YI. The yellowness index is measured using a 4 mm thick injection molding plate in accordance with the ASTM E 313/96 standard.

In particular for the production of data carriers according to the invention, the substrates must have a high degree of purity. This is achieved by reducing the residual monomer, solvent, foreign particle (inorganic or organic type, in particular salts and dust) and the chlorine content to the lowest possible values in a known manner when working up and isolating the substrate resin. This is described, for example, in EP 380002 A or EP 691 361 A, to the disclosure of which reference is made in this regard.

The data carriers according to the invention can be designed in various forms. Known shapes such as optical cards or cylindrical perforated disks such as compact disks (CD), CD recordables (CD-R), digital versatile disks (DVD) or mini disks (MD) are particularly preferred.

Information storage layers (for example phase change layers, magneto-optical layers, dyes, fluorescent dyes, photopolymers), dielectric (for example Si / N), reflective (for example silver, gold or aluminum) can be applied to the substrate. semi-reflective (eg Si, Ge), protective layers (eg acrylic lacquers) and other functional layers. Different sequences of such layers are possible.

Several layers of the substrate or layers with other substrates can be laminated on top of one another. The stored information can be embossed in the substrate (e.g. as a pit structure) or stored in separate information layers. The information can be read out through the transparent substrate or from the information side.

Optical information storage media in which the substrate material according to the invention in the form of foils, e.g. to cover the information layer in DVR (Direct Video Recording) or as a substrate of multilayer systems (possibly with imprinted information) are also part of the invention.

The invention further relates to the described polyester carbonates and other shaped articles containing them, such as optical lenses, plates and foils, which contain the polyester carbonates according to the invention and the use of these polyester carbonates for the production of such shaped articles. The excellent properties of these polyester carbonates are particularly noticeable with optical lenses.

The following examples serve to further explain the invention.

Examples

Determination of the rheo-optic constant C _R :

Birefringence in injection molded bodies, one of the most important optical properties, can be described as a material property by the rheo-optical constant. This can be negative or positive. The greater their absolute value, the greater the birefringence in injection molded parts. The measurement method of the rheo-optical constant is known (EP 0 621 297 A). The plane-parallel 150 to 1000 micron test specimens required for this can be produced by melt pressing or film casting.

The molecular weight is determined by measuring the relative viscosities at 25 ° C. in methylene chloride and a concentration of 0.5 g per 100 ml of methylene chloride.

The T _g determination was carried out in accordance with the CEI / IEC 1074 standard. The water absorption was determined according to DIN 53495 (method 1 + 1L). The density was determined according to the Archimedean principle (Mettler density determination kit).

The hydrogenated dimer fatty acid used (Pripol ^® 1009 from Uniqema) has the following specifications: iodine number <10, monomer content of <0.1%, content of trimer <1%.

example 1

The following polyester carbonate is manufactured:

3036.2 g of sodium carbonate are dissolved in 12.2 kg of water and about 10 l of methylene chloride in a stirred kettle with slow stirring. Then a solution of 1093.4 g Pripol ^® 1009 in 27 1 methylene chloride is added and 5 minutes touched. At temperatures below 15 ° C and a pH of 10 to 8, 944.5 g of phosgene are introduced in about 30 minutes with vigorous stirring. A solution of 4035.7 gl, l-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1248 g sodium hydroxide and 25 l water is then pumped in in 15 minutes. Then a further 3214.8 g of phosgene are introduced for 70 to 80 minutes, a pH of 11 to 12 being maintained by metering in 30% sodium hydroxide solution. The reaction mixture is stirred for 5 minutes, then 58.6 g of 4-tert-butylphenol are added. After a further 5 minutes, 18 ml of N-ethylpiperidine are added and stirring is continued for 30 minutes. The phases are then separated; after acidification, the organic phase is then washed neutral with water and freed from solvent, extruded and granulated.

Example 2

The following polyester carbonate is manufactured:

In a stirred tank reactor 2776.8 g sodium carbonate in 11.1 kg of water, 998.4 g of Pripol ^® 1009 and 33.9 1 of methylene chloride is dissolved under slow stirring. At temperatures below 15 ° C and a pH of 10 to 8, 863.2 g of phosgene are introduced in about 30 minutes with vigorous stirring. Then a solution of 2620.8 gl, l-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane,

1040 g of 2,2-bis (4-hydroxyphenyl) propane, 1248 g of sodium hydroxide and 22.7 l of water were pumped in. A further 3214 g of phosgene are then passed in for about 90 minutes, a pH of 11 to 12 being maintained by metering in 30% strength sodium hydroxide solution. The reaction mixture is stirred for 5 minutes, then 79 g of 4-tert-butylphenol are added. After a further 5 minutes, 18 ml of N-ethylpiperidine are added and stirring is continued for 45 minutes. The phases are then separated; after acidification, the organic phase is then washed neutral with water and freed from solvent, extruded and granulated. Comparative example

3104.4 g of l, l-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are dissolved in 30.3 kg of water and 880 g of sodium hydroxide in a stirred kettle. Then 22.8 l of methylene chloride are added. At temperatures of 15 ° C to 25 ° C and a pH of 11 to 13 1978.3 g of phosgene are introduced in about 40 minutes with vigorous stirring. The pH is maintained by metering in 30% sodium hydroxide solution. The reaction mixture is stirred for 5 minutes, then 82.5 g of isooctylphenol are added. After a further 5 minutes, 20 ml of N-ethylpiperidine are added and stirring is continued for 45 minutes. The phases are then separated; after acidification, the organic phase is then washed neutral with water and freed from solvent.

The polyester carbonates obtained and a standard CD material (Makrolon CD 2005) have the following properties, given in Table 1:

Table 1

Example 3

Manufacture of compact discs

The granules produced in Examples 1 and 2 are processed on a Netstal Diskjet injection molding machine at 320 ° C. melt temperature and 60 ° C. mold temperature to compact disks (diameter: 118 mm, thickness: 1.2 mm).

Comparative example

As a comparison, compact disks are produced from bisphenol A-PC (Makrolon CD 2005) under the conditions of Example 3.

The birefringence properties listed in Table 2 are measured on these compact disks at a radius of 35 mm.

Table 2

Claims

claims

Copolyester carbonate containing recurring, bifunctional structural units A, derived from acids according to formula (I),

in which

D stands for a mixture of divalent hydrocarbon radicals which contain 30 to 42 carbon atoms, D substantially corresponds to formula la and / or Ib and / or Ic and / or Id and / or Ie

in which

Ei, E ₂ , E ₃ and E ₄ in formula Ic and Id for each of the substituents - (CH ₂ ) i-, - (CH ₂ ) _j -, - (CH ₂ ) _k CH ₃ and - (CH ₂ ) ιCH ₃ stand and a, b, c, d, e, f, g, h, i, j, k, l, m, n, o and p independently represent an integer between 1 and 10.

2. Copolyestercarbonate according to claim 1, characterized in that the starting materials used for the bifunctional structural elements A have an iodine number less than about 15.

3. Copolyestercarbonate according to claim 1, characterized in that the educts used for the bifunctional structural elements A have less than about 1.5% portions with functionalities greater than 2.

4. copolyester carbonate according to any one of claims 1 to 3, characterized in that the glass temperature is about 120 to 185 ° C.

5. Copolyestercarbonate according to any one of claims 1 to 4, characterized in that the water absorption when saturated is less than about 0.35%.

6. copolyester carbonate according to any one of claims 1 to 5, characterized in that the polyester carbonate at least one of the other bifunctional structural units B different from A according to formula (II)

-O-R-O-C- (II),

II O contains

wherein the radical -ORO- stands for any diphenolate radicals in which -R- is an aromatic radical having 6 to 40 carbon atoms, which may contain one or more aromatic or fused aromatic nuclei, optionally containing heteroatoms, and optionally with Ci to Cπ -Alkyl radicals or halogen is substituted and may contain aliphatic radicals, cycloaliphatic radicals, aromatic nuclei or heteroatoms as bridge members. - 25 -

14. molded article containing a copolyester carbonate according to any one of claims 1 to 13, in particular optical lenses, plates and films.

15. Machine-readable data carrier, characterized in that it is based on a substrate made of a copolyester carbonate according to claims 1 to 13.

- 24 -

7. Copolyester carbonate according to claim 6, characterized in that the bifunctional carbonate structural units of the formula (II) have a glass transition temperature greater than about 170 ° C as homopolycarbonate.

8. Copolyester carbonate according to claim 6, characterized in that at least one of the bifunctional carbonate structural units B of the formula (II) is derived from 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

9. copolyester carbonate according to claim 6, characterized in that at least one of the bifunctional carbonate structural units B of the formula

(II) derived from 2,2-bis (4-hydroxyphenyl) propane.

10. Copolyestercarbonate according to claim 6, characterized in that at least one of the bifunctional carbonate structural units B of the formula (II) of 6,6'-dihydroxy-3,3,3 ', 3'-tetramethyl-l, r-spiro (bis ) -indan or 1,1-

Bis- (3-methyl-4-hydroxyphenyl) cyclohexane or l- (p-hydroxyphenyl) - 1, 3,3-trimethyl-5-indanol.

11. Copolyestercarbonate according to any one of claims 6 to 10, characterized in that 0.5 to 49 mol%, based on 100 mol% of the bifunctional

Structural units A and B, bifunctional structural units A are included.

12. Copolyestercarbonate according to any one of claims 1 to 11, characterized in that the average weight-average molecular weight M _{w is} 7,000 to 40,000.

13. Copolyestercarbonate according to any one of claims 1 to 12, characterized in that the glass transition temperature is approximately 125 to 150 ° C and that 5-20 mol%, based on 100 mol% of the bifunctional structural units A and B, contain bifunctional structural units A. and that the weight average molecular weight M _{w is} 9,000 to 30,000.