Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-12-09
2002-02-26
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
Reexamination Certificate
active
06350798
ABSTRACT:
Thermoplastic aromatic polycarbonates are in themselves thermally stable. If these polycarbonates contain low molecular weight additives containing ester groups, for example mould release agents, a slight reduction in the molecular weight of the aromatic polycarbonates occurs in the melt, for example during extrusion or during injection moulding treatment, as a result of transesterification with the additive. This disadvantage is of consequence in the event of repeated processing of these additive-containing polycarbonates or indeed in the event of re-use of polycarbonate waste material.
This disadvantage arises in particular when the thermoplastic polycarbonate contains impurities in the form of traces of alkali compounds, alkaline-earth compounds or heavy metal compounds.
It has surprisingly been discovered that the addition of saccharine in amounts of from 0.001 wt. % to 5.0 wt. %, preferably from 0.005 wt. % to 1.5 wt. %, extensively prevents this undesirable transesterification of aromatic polycarbonates which contain additives containing ester groups.
The present invention thus provides the use of saccharine in amounts of from 0.001 wt. % to 5.0 wt. %, preferably from 0.005 wt. % to 1.5 wt. %, based on 100 wt. % polycarbonate, to stabilise thermoplastic aromatic polycarbonates which contain from 0.01 wt. % to 5 wt. %, preferably from 0.05 wt. % to 3 wt. %, again based on 100 wt. % polycarbonate, of ester group-containing additives.
The present invention further provides polycarbonate moulding compositions containing
A) 100 wt. % thermoplastic aromatic polycarbonate, and additionally
B) 0.001 wt. % to 5.0 wt. %, preferably from 0.005 wt. % to 1.5 wt. %, based on 100 wt. % of A, of saccharine, and additionally
C) 0.01 wt. % to 5 wt. %, preferably from 0.05 wt. % to 3 wt. %, again based on 100 wt. % of A, of ester group-containing additives.
Thermoplastic aromatic polycarbonates covered by the present invention include both homopolycarbonates and copolycarbonates; the polycarbonates may, in known manner, be either linear or branched.
These polycarbonates are produced in the known way from diphenols, carbonic acid derivatives, optionally chain terminators and optionally branching agents.
Details of polycarbonate production are to be found in many patent specifications filed over approximately the last 40 years. Reference will be made here, by way of example, merely to Schnell, “Chemistry and Physics of Polycarbonates”, Polymer Reviews, Volume 9, Interscience Publishers, New York, London, Sydney 1964, to D. Freitag, U. Grigo, P. R. Müller, H. Nouvertne', BAYER AG, “Polycarbonates” in Encyclopedia of Polymer Science and Engineering, Volume 11, Second Edition, 1988, pages 648-718 and finally to Drs. U. Grigo, K. Kircher and P. R. Müller “Polycarbonates” in Becker/Braun, Kunststoff-Handbuch, Volume 3/1, Polycarbonates, Polyacetals, Polyesters, Cellulose Esters, Carl Hanser Verlag Munich, Vienna 1992, pages 117-299.
Diphenols suitable for producing polycarbonates are, for example, hydroquinone, resorcinol, dihydroxydiphenyls, bis(hydroxyphenyl)alkanes, bis(hydroxyphenyl)cycloalkanes, bis(hydroxyphenyl) sulfides, bis(hydroxyphenyl) ethers, bis(hydroxyphenyl) ketones, bis(hydroxyphenyl) sulfones, bis(hydroxyphenyl) sulfoxides, &agr;,&agr;′-bis(hydroxyphenyl)-diisopropylbenzenes, together with their ring-alkylated and ring-halogenated compounds.
Preferred diphenols are 4,4′-dihydroxydiphenyl, 2,2-bis-(4-hydroxyphenyl)propane, 2,4-bis-(4-hydroxyphenyl)-2-methylbutane, 1,1-bis-(4-hydroxyphenyl)-p-diisopropyl-benzene, 2,2-bis-(3-methyl-4-hydroxyphenyl)propane, 2,2-bis-(3-chloro-4-hydroxyphenyl)propane, bis-(3,5-dimethyl-4-hydroxyphenyl)methane, 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)propane, bis-(3,5-dimethyl-4-hydroxyphenyl) sulfone, 2,4-bis-(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane, 1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-p/m-diisopropylbenzene, 2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane, 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)propane, 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis-(4-hydroxyphenyl)-1-phenylethane and 1,1-bis-(4-hydroxyphenyl)cyclohexane.
Diphenols which are particularly preferred are 2,2-bis-(4-hydroxyphenyl)propane, 2,2-bis-(3,5-dimethyl-4-hydroxy-phenyl)propane, 2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane, 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)propane, 1,1-bis-(4-hydroxyphenyl)cyclohexane and 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.
These and other suitable diphenols are described, for example, in U.S. Pat. Nos. 3,028,635, 2,999,835, 3,148,172, 2,991,273, 3,271,367, 4,982,014 and 2,999,846, in German published patent applications 1 570 703, 2 063 050, 2 036 052, 2 211 956 and 3 832 396, French patent specification 1 561 518, the monograph “H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964” and in Japanese published patent applications 62039/1986, 62040/1986 and 105550/1986.
In the case of homopolycarbonates, only one diphenol is used, whereas, in the case of co-polycarbonates, several diphenols are used.
Suitable carbonic acid derivatives are, for example, phosgene or diphenyl carbonate.
Both monophenols and monocarboxylic acids are suitable for use as chain terminators. Suitable monophenols are phenol itself, alkylphenols such as cresols, p-tert.-butylphenol, p-n-octylphenol, p-iso-octylphenol, p-n-nonylphenol, and p-iso-nonylphenol, halophenols such as p-chlorophenol, 2,4-dichlorophenol, p-bromophenol and 2,4,6-tribromophenol together with mixtures thereof.
Suitable monocarboxylic acids are benzoic acid, alkyl-benzoic acids and halobenzoic acids.
Preferred chain terminators are phenols of the formula (I)
in which
R is a branched or unbranched C
8
and/or C
9
alkyl residue.
The quantity of chain terminator to be used amounts to from 0.1 mol % to 5 mol %, based on the number of mol of the diphenols used in each case. Chain terminators may be added before, during or after phosgenation.
Suitable branching agents are the trifunctional or more than trifunctional compounds known in polycarbonate chemistry, in particular those with three or more than three phenolic OH groups.
Suitable branching agents are, for example, phloroglucinol, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-2-heptene, 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-hydroxyphenyl-isopropyl)phenol, 2,6-bis-(2-hydroxy-5′-methylbenzyl)-4-methylphenol, 2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)-propane, hexa-(4-(4-hydroxyphenylisopropyl)phenyl)-orthoterephthalic acid ester, tetra-(4-hydroxyphenyl)-methane, tetra-(4-(4-hydroxyphenylisopropyl)phenoxy)-methane and 1,4-bis-(4′,4″-dihydroxytriphenyl)methyl)-benzene together with 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride and 3,3-bis-(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole.
The quantity of branching agent optionally to be used amounts to from 0.05 mol % to 2 mol %, again based on the number of mol of the diphenols used in each case.
The branching agents may either be present with the diphenols and the chain terminators in the initial aqueous alkaline phase or be added in solution in an organic solvent prior to phosgenation. In the case of a trans-esterification process, the branching agents are added together with the diphenols.
All these measures for producing thermoplastic polycarbonates are familiar to the person skilled in the art.
The polycarbonates to be used according to the invention have average weight average molecular weights Mw, determined by measuring the relative viscosity in CH
2
Cl
2
at 25° C. with a concentration of 0.5 g in 100 ml CH
2
Cl
2
, of between 10,000 and 80,000, preferably between 15,000 and 40,000.
Ester group-containing additives for thermoplastic polycarbonates are, in particular, plasticisers and mould release agents, as described in the literature and also used for processing thermoplastic polycarbonates.
The
Ebert Wolfgang
Haese Wilfried
Hufen Ralf
Bayer Aktiengesellschaft
Buttner David J.
Franks James R.
Gil Joseph C.
Pries Aron
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