Process for the production of poly (diorganosiloxane)/polycarbonate block copolymers

The present invention provides a process for the production of poly(diorganosiloxane)/polycarbonate block copolymers in a melt using specific transesterification catalysts.

The present invention provides a process for the production of 
thermoplastic poly(diorganosiloxane)/polycarbonate block copolymers with 
average molecular weights M.sub.W (weight average, determined by gel 
chromatography) of 18000 to 60000, preferably of 19000 to 40000, from 
aromatic, Si-free diphenols, carbonic acid diaryl esters and 
polydiorganosiloxanes in the presence of catalysts at temperatures of 
between 80.degree. C. and 320.degree. C. and pressures of 1000 mbar to 
0.01 mbar, which process is characterised in that the catalysts used are 
quaternary ammonium compounds and/or quaternary phosphonium compounds of 
the formulae (I) and/or (II) 
##STR1## 
in which R.sub.1-4 are identical or different C.sub.1 -C.sub.30 alkyls, 
C.sub.6 -C.sub.10 aryls or C.sub.5 -C.sub.6 cycloalkyls, wherein at least 
one residue of R.sub.1-4 is a C.sub.8 -C.sub.30 alkyl, preferably C.sub.12 
-C.sub.20 alkyl and in which X.sup.- is an anion in which the 
corresponding acid/base pair H.sup..sym. +X.sup..crclbar. .revreaction.HX 
has a pKB of 1 to 11, in quantities of 10.sup.-1 to 10.sup.-8 mol, 
relative to 1 mol of Si-free diphenol, and that the polydiorganosiloxane 
component used comprises .alpha.,.omega.-bishydroxyaryl-, 
.alpha.,.omega.-bishydroxyalkyl-, .alpha.,.omega.-bisacyl- or 
.alpha.,.omega.-bishydroxyacyl-polydiorganosiloxanes in quantities by 
weight of 30 wt. % to 0.5 wt. %, preferably of 7 wt. % to 1 wt. %, 
relative to the total weight of Si-free diphenols and 
polydiorganosiloxanes. 
The polydiorganosiloxanes have degrees of polymerisation of their 
diorganosiloxane structural units "n" of 5 to 100, preferably between 5 
and 80 and in particular between 10 and 50. 
For the purposes of the present invention, Si-free diphenols are diphenols 
which contain no chemically attached silicon atoms. X.sup.- anions of (I) 
and (II) are, for example, tetraphenylhydridoborate and fluoride. 
The polydiorganosiloxane/polycarbonate block copolymers obtainable 
according to the invention have a diorganosiloxane structural unit content 
of between 30 wt. % and 0.5 wt. %, preferably of between 7 wt. % and 1 wt. 
%, in each case relative to the total weight of the 
polydiorganosiloxane/polycarbonate block copolymers. 
The polydiorganosiloxane/polycarbonate block copolymers produced using the 
process according to the invention have better mould release properties 
and flow, a rubber/glass transition which is displaced to lower 
temperatures and improved ESC behaviour. They are also produced in 
solvent-free form. 
The production of aromatic oligo/polycarbonates using the melt 
transesterification process is known from the literature and has been 
described, for example, in Chemistry and Physics of Polycarbonates, 
Polymer Reviews, H. Schnell, volume 9, John Wiley & Sons Inc. (1964). 
The production of polydiorganosiloxane/polycarbonate block copolymers by 
the phase interface process is known from the literature and has been 
described, for example, in U.S. Pat. No. 3,189,662, U.S. Pat. No. 
3,419,634, DE-OS 334 782 (Le A 22 594), EP 0 122 535 (Le A 22 594-EP). 
U.S. Pat. No. 5,227,449 describes the preparation of 
polydiorganosiloxane/polycarbonate block copolymers using the melt 
transesterification process from bisphenol, diaryl carbonate and silanol 
end-terminated polysiloxanes using catalysts which are used as binders for 
charge transport molecules in photoconductive layers. In this document, 
the siloxane compounds used are polydiphenyl- or polydimethylsiloxane 
telomers with silanol end groups (from the company Petrarch System, now 
Huls). 
It has now been found that, in comparison with conventional 
transesterification catalysts (see comparative Example 1c), it is more 
readily possible to synthesise polydiorganosiloxane/polycarbonate block 
copolymers via the transesterification process with catalysts of the 
general formulae (I) or (II) having at least one C.sub.8 -C.sub.30 alkyl 
residue on the nitrogen or phosphorus atom. 
The catalysts of the formulae (I) and (II) have already been used for the 
production of other polycarbonates, for example of bisphenol A 
polycarbonates. When the catalysts of the general formula (I) or (II) 
having at least one C.sub.8 -C.sub.30 alkyl residue on the N or P atom are 
used for this purpose, no particular effects are found in comparison with 
other ammonium or phosphonium catalysts (see comparative examples 1a and 
1b). 
The .alpha.,.omega.-bishydroxyaryl polydiorganosiloxanes to be used 
according to the invention are known, for example, from U.S. Pat. No. 
3,419,634. 
The .alpha.,.omega.-bishydroxyaryl polydiorganosiloxanes to be used 
according to the invention are known and commercially available, for 
example from the company Th. Goldschmidt, Essen. 
The .alpha.,.omega.-bisacyl polydiorganosiloxanes to be used according to 
the invention are known, for example, from DE-OS 33 34 782 (Le A 22 594). 
The .alpha.,.omega.-bishydroxyacyl polydiorganosiloxanes to be used 
according to the invention are known and commercially available, for 
example from the company Th. Goldschmidt, Essen. 
The polydiorganosiloxanes to be used according to the invention preferably 
have hydroxyaryloxy, hydroxyalkoxy, hydroxyacyloxy, 
.omega.-hydroxycaprolactone or acetoxy end groups. 
The polydiorganosiloxanes which are preferably to be used are in particular 
of the formulae (III), (IV) or (V) 
##STR2## 
In these formulae, R is a monocyclic or polycyclic arylene residue with 6 
to 30 C atoms, preferably 6 C atoms or a linear or branched alkylene 
residue with 1 to 30 C atoms, or 3 to 30 C atoms, preferably 3 to 10 C 
atoms. 
Preferred residues R are those of the formula (VIa) 
##STR3## 
in which --X-- is a C.sub.1 -C.sub.12 alkylidene, C.sub.7 -C.sub.12 
aralkylidene, C.sub.5 -C.sub.15 cycloalkylidene, --S--, --SO.sub.2 --, 
--O--, 
##STR4## 
or a single bond, particularly preferably 
##STR5## 
R.sup.1 and R.sup.2 are identical or different and linear, optionally 
halogenated alkyl, branched, optionally halogenated alkyl, aryl or 
halogenated aryl, preferably methyl. 
R.sub.3 is linear, optionally halogenated alkylene, branched, optionally 
halogenated alkylene or arylene, preferably linear or branched C.sub.1 
-C.sub.16 alkylene, particularly preferably linear propylene, linear 
butylene, linear pentylene and linear hexylene. 
The number of diorganosiloxane units "n" is obtained for the formula (III) 
from "o+p+q", for the formula (IV) from "n" and for the formula (V) from 
"o+p". In each case, it is between 5 and 100, preferably between 20 and 80 
and in particular between 25 and 50. The index "m" is 1 to 30, preferably 
5 to 15. 
Examples of residues R are 
##STR6## 
Examples of residues R.sup.1 -- are methyl, ethyl, propyl, butyl and 
phenyl. 
Examples of residues R.sup.2 -- are also methyl, ethyl, propyl, butyl and 
phenyl. 
Examples of residues --R.sub.3 -- are methylene, ethylene, i,n-propylene, 
i,n-butylene, i,n-pentylene and i,n-hexylene. 
Examples of compounds of the formulae (III), (IV) and (V) are 
##STR7## 
Si-free diphenols suitable for the process according to the invention are 
those of the formula (VI) 
##STR8## 
in which X is C.sub.1 -C.sub.12 alkylidene or C.sub.5 -C.sub.15 
cycloalkylidene, C.sub.7 -C.sub.12 aralkylidene, --SO.sub.2 --, 
##STR9## 
S or a single bond and R is CH.sub.3, Cl or Br and n is zero, 1 or 2. 
Preferred diphenols are, for example: 
4,4'-dihydroxydiphenyl, 
4,4'-dihydroxydiphenylsulphide, 
2,2-bis-(4-hydroxyphenyl)propane, 
2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)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, 
1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and 
1-phenyl-2,2-bis-(4-hydroxyphenyl)propane. 
Particularly preferred diphenols among those stated above are 
2,2-bis-(4-hydroxyphenyl)propane and 
1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane. 
Instead of the Si-free diphenols, it is also possible to use 
oligocarbonates containing OH groups prepared from these diphenols for the 
process according to the invention. 
For the purposes of the present invention, carbonic acid diesters are 
di-C.sub.6 -C.sub.20 -aryl esters, preferably the diesters of phenol or 
alkyl-substituted phenols, thus diphenyl carbonate or, for example, 
dicresyl carbonate. Relative to 1 mol of the sum of Si-free diphenols and 
polydiorganosiloxanes, the carbonic acid diesters are used in quantities! 
of 1.01 to 1.30 mol, preferably of 1.02 to 1.15 mol. 
The polycarbonate block copolymers may purposefully and controllably be 
branched by using small quantities of branching agents. Some suitable 
branching agents are: 
phloroglucinol, 
4,6-dimethyl-2,4,5-tri-(4-hydroxyphenyl)-hept-2-ene, 
4,6-dimethyl-2,4,5-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, 
2,6-bis-(2-hydroxy-5'-methylbenzyl)-4-methylphenol, 
2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)propane, 
hexa-(4-(4-hydroxyphenylisopropyl)phenyl-ortho-terephthalic acid ester, 
tetra-(4-hydroxyphenyl)methane, 
tetra-(4-(4-hydroxyphenylisopropyl)phenoxy)methane, 
1,4-bis-((4',4"-dihydroxytriphenyl)methyl)benzene and in particular 
.alpha.,.alpha.',.alpha."-tris-(4-hydroxyphenyl)-1,3,5-triisopropylbenzene. 
Further possible branching agents are 2,4-dihydroxybenzoic acid, the phenyl 
or cresyl esters thereof, trimesic acid, the phenyl or cresyl esters 
thereof, cyanuric chloride and 
3,3-bis-(3-methyl-4-hydroxyphenyl)-oxo-2,3-dihydroindole. 
The branching agents, which are optionally to be used in a quantity of 0.05 
to 0.3 mol. %, relative to the Si-free diphenols used, may be used 
together with the Si-free diphenols. 
Molecular weights are generally limited by the quantity of carbonic acid 
diaryl ester and by the reaction conditions. Monophenols, for example 
phenol or alkylphenols, may moreover additionally be added as chain 
terminators (c.f, for example, EP-360 598). 
Care should be taken to ensure that the reaction components, namely the 
Si-free diphenols, carbonic acid diaryl esters and the 
polydiorganosiloxanes contain no alkali metal and alkaline earth metal 
ions, wherein quantities of less than 0.1 ppm of alkali metal and alkaline 
earth metal ions may be tolerated. Such pure carbonic acid diaryl esters, 
polydiorganosiloxanes or Si-free diphenols may be obtained by 
recrystallising, washing or distilling the carbonic acid diaryl esters, 
polydiorganosiloxanes or Si-free diphenols. In the process according to 
the invention, the content of alkali metal and alkaline earth metal ions 
should be &lt;0.1 ppm in the Si-free diphenol, the polydiorganosiloxane and 
in the carbonic acid diester. 
For the purposes of the process according to the invention, examples of 
catalysts are: 
hexadecyltrimethylammonium tetraphenylhydridoborate, 
hexadecyltributylphosphonium tetraphenylhydridoborate, 
hexadecyltrimethylammonium fluoride, 
hexadecyltributylphosphonium fluoride. 
The catalysts of the formulae (I) and (II) are known from the literature 
(E. V. Dehmlov, S. S. Dehmlov, Phase Transfer Catalysts, 2nd edition, 
Verlag Chemie, 1983; Houben-Weyl, Methoden der organischen Chemie, 4th 
edition, volume XI/2, 1958, pages 591 et seq., volume XII/1, 1963, pages 
79 et seq., volume XIII/3b, 1983, pages 763 et seq. and Charles M. Starks 
and Charles Ciotta, Phase Transfer Catalysis, Academic Press, 1978) or may 
be produced using processes known from the literature (c.f. loc. cit.). 
These catalysts are preferably used in quantities of 10.sup.-2 to 10.sup.-8 
mol, relative to 1 mol of Si-free diphenol. The catalysts may be used 
alone or in combination with each other (two or more) or in combination 
with other transesterification catalysts known for polycarbonate 
production. Other known transesterification catalysts are, for example, 
alkali metal or alkaline earth metal compounds according to U.S. Pat. No. 
3,272,601, other ammonium or phosphonium compounds according to U.S. Pat. 
No. 3,442,864, JA 14 742/72 and U.S. Pat. No. 5,399,659 and guanidine 
systems according to U.S. Pat. No. 5,319,066. 
Examples of other known transesterification catalysts are alkali metal 
hydroxides, alkali metal phenolates, alkali metal diphenolates, 
tetramethylammonium hydroxide and tetramethylammonium 
tetraphenylhydridoborate. 
The process according to the invention may be performed in a single stage. 
In this case, the following procedure is used: 
The Si-free dihydroxy compound, the polydiorganosiloxane and the carbonic 
acid diester are melted at temperatures of 80.degree. to 250.degree. C., 
preferably of 100.degree. to 230.degree. C., particularly preferably of 
120.degree. to 190.degree. C. under standard pressure in 0 to 5 hours, 
preferably 0.25 to 3 hours. The catalyst may be added before the 
components are melted or to the melted components. An oligocarbonate is 
then produced by applying a vacuum, increasing the temperature and 
removing the monophenol by distillation. The polycarbonate is then 
produced in a polycondensation reaction by further increasing the 
temperature to 240.degree. to 400.degree. C. and reducing the pressure 
down to 0.01 mbar. Alternatively, the polydiorganosiloxane may also be 
added together with the catalyst to the other melted components. 
It is, however, possible to perform the process according to the invention 
in two separate stages, wherein, in the first stage, the oligocarbonate is 
produced using catalysts (I) and/or (II) and, in the second stage, the 
polycarbonate is produced from the oligocarbonates, wherein alkali metal 
or alkaline earth metal catalysts may optionally additionally be used, and 
the mixture is maintained at temperatures of 250.degree. to 320.degree. 
C., preferably of 280.degree. C. to 290.degree. C. and a pressure of &lt;100 
mbar to 0.01 mbar over a short period of &lt;3 hours to 10 minutes, 
preferably of &lt;1 hour to 20 minutes, particularly preferably of &lt;30 to 20 
minutes. 
The polydiorganosiloxane/oligocarbonates produced in this case as an 
intermediate have OH/aryl carbonate end group ratios in the range of 60:40 
to 5:95, preferably of 45:55 to 10:90, which may be determined by 
photometric determination of the OH end groups with TiCl.sub.4. 
The OH end group of the oligocarbonates is defined as: 
EQU x mol. %=100 (number of OH end groups)/(total number of end groups). 
The process according to the invention may be performed continuously or 
discontinuously in stirred tank reactors, film evaporators, falling-film 
evaporators, stirred tank reactors in series, extruders, kneaders, simple 
disk reactors and high viscosity disk reactors. 
The aromatic polycarbonate block copolymers of the process according to the 
invention should have weight average molecular weights M.sub.W of 18000 to 
60000, preferably of 19000 to 40000, determined by measuring the relative 
solution viscosity in dichloromethane or in mixtures of equal quantities 
by weight of phenol/o-dichlorobenzene, calibrated by light scattering. 
The polycarbonate block copolymers produced according to the invention have 
a light intrinsic colour, preferably have a low OH end group content of 
&lt;1200 ppm and are resistant to hydrolysis and heat. 
Fillers and reinforcing agents may be added to the polycarbonate block 
copolymers produced according to the invention in order to improve their 
properties. Such substances which may inter alia be considered are: 
stabilisers (for example UV, heat, gamma radiation stabilisers), 
anti-static agents, flow auxiliaries, mould release agents, flame 
retardants, pigments, finely divided minerals, fibres, for example alkyl 
and aryl phosphites, phosphates, phosphanes, low molecular weight 
carboxylic acid esters, halogen compounds, salts, chalk, silica flour, 
glass and carbon fibres. Other polymers, for example polyolefins, 
polyurethanes or polystyrene, may moreover be added to the polycarbonate 
block copolymers produced according to the invention. 
These substances are preferably added to the finished polycarbonate in 
conventional units, but, if required, addition may be made at another 
stage of the process according to the invention. 
The poly(diorganosiloxane)/polycarbonate block copolymers produced 
according to the invention may be used in any applications where known 
aromatic polycarbonates have hitherto been used and where good flow 
combined with improved mould release properties and elevated toughness at 
low temperature are additionally required, such as for example for the 
production of large exterior automotive components, switch boxes for 
outdoor use and protective helmets. 
The present invention accordingly also provides the use of the 
poly(diorganosiloxane)/polycarbonate block copolymers obtainable according 
to the invention for the production of large exterior automotive 
components, switch boxes for outdoor use and protective helmets.

EXAMPLES 
Comparative Example 1a 
114.15 g (0.500 mol) of bisphenol A and 113.54 g (0.530 mol) of diphenyl 
carbonate are weighed out into a 500 ml three-necked flask with a stirrer, 
internal thermometer and Vigreux column (30 cm, mirrored) with a bridge 
piece. Atmospheric oxygen is eliminated from the apparatus by applying a 
vacuum and purging with nitrogen (3 times) and the mixture is heated to 
150.degree. C. 0.13 g of cetyltrimethylammonium tetraphenylhydridoborate 
(CH.sub.3 (CH.sub.2).sub.15 N(CH.sub.3).sub.3 (B(C.sub.6 H.sub.5).sub.4) 
(0.05 mol. % relative to bisphenol A) are then added and the resultant 
phenol distilled off at 100 mbar. The temperature is simultaneously raised 
to up to 250.degree. C. The vacuum is then improved in stages to 1 mbar 
and the temperature raised to 260.degree. C. The temperature is then 
raised to 280.degree. C. and the mixture stirred for 1.5 hours at 0.1 
mbar. 
A solvent-free polycarbonate with a relative solution viscosity of 1.234 
(dichloromethane, 25.degree. C., 5 g/l) is obtained. The phenolic OH value 
of the polycarbonate is 340 ppm. 
Comparative Example 1b 
Comparative Example 1a) is repeated, but using tetraphenylphosphonium 
tetraphenylhydridoborate as the catalyst instead of cetyltrimethylammonium 
tetraphenylhydridoborate. A light coloured, solvent-free polycarbonate 
with a relative solution viscosity of 1.254 (dichloromethane, 25.degree. 
C., 5 g/l) is obtained in this case too. The phenolic OH value of the 
polycarbonate is 360 ppm. 
Example 1 
102.7 g (0.45 mol) of bisphenol A, 100.0 g (0.467 mol) of diphenyl 
carbonate and 5.4 g of .alpha.,.omega.-bisacetoxydimethylpolysiloxane, 
average degree of polymerisation P.sub.n =31, (5 wt. % relative to 
bisphenol A), are weighed out into a 500 ml three-necked flask with a 
stirrer, internal thermometer and Vigreux column (30 cm, mirrored) with a 
bridge piece. Atmospheric oxygen is eliminated from the apparatus by 
applying a vacuum and purging with nitrogen (3 times) and the mixture is 
heated to 150.degree. C. 0.13 g of cetyltrimethylammonium 
tetraphenylhydridoborate (CH.sub.3 (CH.sub.2).sub.15 N(CH.sub.3).sub.3 
B(C.sub.6 H.sub.5).sub.4, (0.05 mol. % relative to bisphenol A and 
diphenyl carbonate) are then added and the resultant phenol distilled off 
at 100 mbar. The temperature is simultaneously raised to 
180.degree.-190.degree. C. within approximately 50 minutes and then slowly 
raised to 250.degree. C. in a further 2 hours. The vacuum is then improved 
in stages to 1 mbar and the temperature raised to 280.degree. C. It is at 
this point that the principal quantity of phenol is eliminated. By further 
heating at 280.degree. C. and 0.1 mbar for 1.5 hours, a light coloured, 
solvent-free polycarbonate is obtained with relatively small and uniformly 
distributed siloxane domains, see FIG. 1. The relative solution viscosity 
is 1.280 (dichloromethane, 25.degree. C., 5 g/l). The phenolic OH value of 
the block copolycarbonate is 200 ppm. 
FIG. 1 shows the TEM micrograph of untreated ultra-thin sections of Example 
1. The diameter of the siloxane domains ranges from approximately 15 nm to 
&gt;2 .mu.m, distribution is relatively uniform (HAAN177). 
Comparative example 1c 
102.7 g (0.45 mol) of bisphenol A, 100.0 g (0.467 mol) of diphenyl 
carbonate and 5.4 g of .alpha.,.omega.-bisacetoxydimethylpolysiloxane, 
average degree of polymerisation P.sub.n =31, (5 wt. % relative to 
bisphenol A), are weighed out into a 500 ml three-necked flask with a 
stirrer, internal thermometer and Vigreux column (30 cm, mirrored) with a 
bridge piece. Atmospheric oxygen is eliminated from the apparatus by 
applying a vacuum and purging with nitrogen (3 times) and the mixture is 
heated to 150.degree. C. 0.3 g of a 1% masterbatch of 
tetraphenylphosphonium tetraphenylhydridoborate, P(C.sub.6 H.sub.5).sub.4 
B(C.sub.6 H.sub.5).sub.4, in diphenyl carbonate (0.001 mol. % relative to 
bisphenol A) are then added and the resultant phenol distilled off at 100 
mbar. The temperature is simultaneously raised to 250.degree. C. After 1 
hour, the vacuum is improved to 10 mbar. Polycondensation is achieved by 
reducing the vacuum to 0.5 mbar and raising the temperature to 280.degree. 
C. 
A light coloured, solvent-free polycarbonate is obtained with relatively 
large siloxane domains, see FIG. 2. The relative solution viscosity is 
1.28 (dichloromethane, 25.degree. C., 5 g/l). The phenolic OH value of the 
polycarbonate is 200 ppm. 
FIG. 2 shows the TEM micrograph of untreated ultra-thin sections of Example 
1c. The siloxane domains may be seen as dark particles having a diameter 
ranging from approximately 0.02 to &gt;2 .mu.m (HAAN 059). 
Example 2 
102.7 g (0.45 mol) of bisphenol A, 100.0 g (0.467 mol) of diphenyl 
carbonate and 5.4 g of a bisphenol A terminated polydimethylsiloxane are 
weighed out into a 500 ml three-necked flask with a stirrer, internal 
thermometer and Vigreux column (30 cm, mirrored) with a bridge piece. 
Atmospheric oxygen is eliminated from the apparatus by applying a vacuum 
and purging with nitrogen (3 times) and the mixture is heated to 
150.degree. C. 
0.13 g of cetyltrimethylammonium tetraphenylhydridoborate (CH.sub.3 
(CH.sub.2).sub.15 N(CH.sub.3).sub.3)B(C.sub.6 H.sub.5).sub.4, (0.05 mol. % 
relative to bisphenol A and diphenyl carbonate) are then added and the 
resultant phenol distilled off at 100 mbar. The temperature is 
simultaneously raised to 180.degree.-190.degree. C. within approximately 
50 minutes and then slowly raised to 250.degree. C. in a further 2 hours. 
The vacuum is then improved in stages to 1 mbar and the temperature raised 
to 280.degree. C. It is at this point that the principal quantity of 
phenol is eliminated. By further heating at 280.degree. C. and 0.1 mbar 
for 1.5 hours, a light coloured, solvent-free polycarbonate is obtained 
with a relative solution viscosity of 1.287 (dichloromethane, 25.degree. 
C., 5 g/l). 
FIG. 3 shows the TEM micrograph of untreated ultra-thin sections of Example 
2. The diameter of the siloxane domains ranges from 0.02 to 0.7 .mu.m. The 
distribution of the siloxane domains is very uniform (HAAN 114/2). 
Example 3 
102.7 g (0.45 mol) of bisphenol A, 100.0 g (0.467 mol) of diphenyl 
carbonate and 5.4 g of siloxane of the formula (IIIa) 
##STR10## 
with n=2.4, m=6 and a molecular weight M.sub.n of 810, the production of 
which is described in Ullmanns Encyklopadie der technischen Chemie, volume 
15, 1964, 3rd edition, pages 769 et seq. and is commercially available 
from Th. Goldschmidt as Tegomer H--Si 2111 are weighed out into a 500 ml 
three-necked flask with a stirrer, internal thermometer and Vigreux column 
(30 cm, mirrored) with a bridge piece. 
Atmospheric oxygen is eliminated from the apparatus by applying a vacuum 
and purging with nitrogen (3 times) and the mixture is heated to 
150.degree. C. 0.13 g of cetyltrimethylammonium tetraphenylhydridoborate 
(CH.sub.3 (CH.sub.2).sub.15 N(CH.sub.3).sub.3)B(C.sub.6 H.sub.5).sub.4, 
(0.05 mol. % relative to bisphenol A) are then added and the resultant 
phenol distilled off at 100 mbar. The temperature is simultaneously raised 
to 180.degree.-190.degree. C. within approximately 50 minutes and then 
slowly raised to 250.degree. C. in a further 2 hours. The vacuum is then 
improved in stages to 1 mbar and the temperature raised to 280.degree. C. 
It is at this point that the principal quantity of phenol is eliminated. 
By further heating at 280.degree. C. and 0.1 mbar for 1.5 hours, a light 
coloured, solvent-free polycarbonate is obtained with a relative solution 
viscosity of 1.268 (dichloromethane, 25.degree. C., 5 g/l). 
Example 4 
100 g of oligocarbonate (relative solution viscosity: 1.147, phenolic end 
groups 43%, approximately 0.025 mol OH), 117.8 g (0.55 mol) of diphenyl 
carbonate and 5.0 g of .alpha.,.omega.-bisacetoxydimethylpolysiloxane with 
an average degree of polymerisation P.sub.n of P.sub.n =31, (5 wt. % 
relative to bisphenol A), are weighed out into a 500 ml three-necked flask 
with a stirrer, internal thermometer and Vigreux column (30 cm, mirrored) 
with a bridge piece. Atmospheric oxygen is eliminated from the apparatus 
by applying a vacuum and purging with nitrogen (3 times) and the mixture 
is heated to a temperature of 250.degree. C. 0.008 g of 
cetyltrimethylammonium tetraphenylhydridoborate (CH.sub.3 
(CH.sub.2).sub.15 N(CH.sub.3).sub.3)B(C.sub.6 H.sub.5).sub.4 (0.05 mol. % 
relative to the phenolic end groups of the oligocarbonate) are then added 
and the resultant phenol distilled off at 100 mbar. The vacuum is improved 
in stages over approximately 60 minutes to 10 mbar and then to 0.1 mbar 
over a further 10 minutes and the temperature raised to 280.degree. C. It 
is at this point that the principal quantity of phenol is eliminated. By 
further heating at 280.degree. C. and 0.1 mbar for 1.5 hours and 
subsequent heating to 300.degree. C. at 0.1 mbar for 2 hours, a light 
coloured, solvent-free polycarbonate is obtained with a relative solution 
viscosity of 1.404 (dichloromethane, 25.degree. C., 5 g/l) with a value of 
the phenolic end groups of the block copolycarbonate of &gt;50 ppm.