Note: Descriptions are shown in the official language in which they were submitted.
Mo-1581-Ca
LeA 16,142-Ca
'''.' `
{;4
3,3-BI~-(4-HYDROXYARYL)-OXINDOLE
BRANCHING AGENTS FOR POLYCARBONATES
Background of the Invention
It is known to prepare high-molecular weight, linear,
soluble, thermoplastic aromatic polycarbonates by reaction of
bisphenols with polycarbonate-forming derivatives of carbonic
acid under polycarbonate-forming reaction conditions, say
accoraing to the processes of German Patent Specifications
971,790; 971,777; 959,497; 1,007,996; 1,031,512 and 1,046,311.
In contrast to most other plastics, melts of linear polycarbon-
ates exhibit Newtonian flow in the range of low rates of
deformation (=rates of shear), and non-Newtonian flow in the
range of high rates of deformation. For extrusion processes, it
is advantageous to have values of the apparent melt viscosity
which are as high as possible, On the other hand, for processing
by injection molding, it is desirable that the apparent melt
viscosity should have values which are as low as possible. In
spite of the non-Newtonian flow of linear polycarbonates in the
range of high rates of deformation, such as occur during
processing by injection molding, the accompanying lowering of
the apparent melt viscosity is too slight - that is to say the
apparent melt viscosity is still too high - for linear poly-
carbonates of high apparent melt viscosity to be employed for
injection molding. For this reason, linear polycarbonates with
low apparent melt viscosity are normally suitable for processing
by injection molding and those with high apparent melt viscosity
are normally suitable for extrusion processes. In other words,
in general, it is not possible to employ one and the same
", 1 ~
~~~eA 16,1~2-Ca
- `\
- .1~3G4.~
linear polycarbonate, particularly if the apparent melt
viscosity has a high value, both for processing by extru-
sion and for processing by injection molding.
Attempts have also been made to modify linear poly-
carbonates of high solution viscosity, through incorporationof functional bisphenols, in such a way that they show non-
Newtonian flow in the range of very low rates of deformation(processing by extrusion), and hence exhibit high shape
retention of the extruded ribbon. Such products are par-
ticularly suitable for the manufacture of hollow articles of
large volume in accordance with the extrusion-blowing process
(compare DT-OS (German Published Specification) 1,595,762).
Polyfunctional, especially trifunctional and tetra-
functional, phenols (compare DT-OS (German Published Speci-
fication) 1,595,641, DT-OS (German Published Specification)
1,570,533, DT-OS (German Published Specification) 2,039,536,
U.S. Patent Specification 3,541,049, DT-OS (German Published
Specification 2,113,347, U.S. Patent 3,799,953 and DT-OS
(German Published Specification) 2,254,918) or bisphenols
having an additional radical capable of undergoing condensa-
- tion such as, for example, the carboxyl group (compare DT-OS
(German Published Specification) 1,595,762) are known as
branching agents for aromatic polycarbonates.
In part, polyhydric phenols of functionality
greater than two are only obtainable via expensive purifica-
tion processes and at times show considerable differences in
respect of the reactivity of the phenolic hydroxyl groups.
A reduced reactivity of individual OH groups, especially of
OH groups in middle positions, towards carbonate-forming
compounds does not ensure complete incorporation of the
LeA 16,142 -2-
1~36~
compounds, so that greatly fluctuating degrees of
branching must be expected. The free phenolic hydroxyl
groups which are still present, because of the incomplete
conversion, can lead to undesired discolorations of the
material on repeated extrusion. For example, in the blow-
molding process re-extrusions must be expected particularly
frequently, since after trimming the hollow articles to
the desired shape up to 20% of excess material arises,
which must be added back to the next process cycle if it is
desired to operate economically. Hence, it is only possible
to incorporate those branching agents which even after
repeated extrusion lead to at most very slight discolorations
of the polycarbonate.
In the case of branching via cyanuric chloride, as
described in U.S. Patent 3,541,049, the functional groups of
the branching agent again show a marked gradation in reactiv-
ity. Furthermore, in the case of polycarbonate branched via
cyanuric chloride, the material shows yellowing phenomena
after exposure to light.
Again, in the case of the polyfunctional phenols
described in DT-OS (German Published Specification) 1,595,762
especially bisphenol-acids, the incorporation achieved is at
times only 75%.
The ortho-esters described in DT-OS (German Pub-
lished Specification) 2,254,918 and U.S. Patent 3,897,392
have the disadvantage that in the solution condencation pro-
cess the branched polycarbonates are not obtained directly;
instead, the ortho-esters must first be converted into
sufficiently reactive branching agent precondensates by an
LeA 16,142 -3-
. .'., ,
~)64~
intermediate reaction with aromatic dihydroxy compounds.
- Further, it was known from U.S. Patent Specifica-
tion 3,256,242 to manufacture aromatic polyesters containing
chlorine by condensation of chloroisophthalic acid dichloride
with bis-(4-hydroxyphenyl)-oxindole in equimolar ratios at
150 - 250C. This gave solely linear polyesters but no
crosslinked or branched products and no polyester-imides, as
- can be seen from the structural formulae and examples in the
. above specification. In other words, under the conditions
;~. 10 of the condensation disclosed in the above specification,
the formation of linear ester bonds is preferred, since
~: otherwise the amide group of the oxindole would also, at
: least partially, have to undergo a condensation, even if the
reactants are employed in the equimolar ratio instead of
employing 1.5 mols of dicarboxylic acid per mol of bis-(4-
~.~
. hydroxyphenyl)-oxindole.
It was the object of the present invention to dis-
: cover a new branching agent for linear, in particular aro-
matic, polycarbonates, which is practically completely
incorporated into the polycarbonate molecule in the processes
of phase boundary condensation, solution condensation and
melt condensation customary for the preparation of polycar-
bonates, so that discolorations largely do not occur, even
on repeated extrusion. Furthermore, the branching agent,
even if employed in small amounts, should impart a pronounced
. structural viscosity behavior to the branched polycarbonates
obtained so that a grade of polycarbonate is equally suit-
able for processing by extrusion and processing by injec-
tion molding, that is to say the branched polycarbonates
should, in the range of rates of deformation which are used
t LeA 16,142 _4_
:
;4~
for processing by extrusion and processing by injection
molding, exhibit a marked dependence of the apparent melt
viscosity on the particular rate of deformation. At the
same time, the apparent melt viscosity should be as high as
possible at low rates of deformation (extrusion) and as low
as possible at high rates of deformation (processing by
injection molding).
The object has been achieved by employing 3,3-
bis-(4-hydroxyaryl)-oxindoles (hereafter also referred to
as isatin-bisphenols) for the manufacture of high-molecular
weight, thermoplastic, soluble and branched polycarbonates.
- Summary of the Invention
The instant invention generally relates to a process
for the preparation of a high molecular weight branched
polycarbonate substantially free of cross-linking comprising
reacting a carbonic acid derivative with aromatic dihydroxy
compounds, from about 0.05 to about 2 mol percent of 3,3-bis-
(4-hydroxyaryl)-oxindole and about 0.1 to about 8 mol percent
of a monohydric phenol (the mol percentage being based on the
mols of the aromatic dihydroxy compound).
,
More particularly, the instant invention relates to
a process for the preparation of a thermoplastic, branched-
chain, high molecular weight, soluble polycarbonate comprising
condensing a difunctional aromatic halogen-free or halogen-
containing dihydroxy compound or a mixture thereof in thepresence of from about 0.05 to 2 mol % of a branching agent
and from about 0.1 to 8.0 mol % of a monofunctional aromatic hydrox~
compound, in each case relative to the mols (100 mol %) of
LeA 16,142 -Ca -5-
B
. : -,
... . . . . . . .
-~ the difunctional aromatic dihydroxy compound, with phosgene,
a bis-chlorocarbonic acid ester or another compound which
forms carbonate groups, in solution or by means of a phase
~. boundary reaction, at a temperature of from about 20 to 80C,
5 or with a carbonic acid diaryl ester in the melt at a tempera-
ture of from about 150 to 300C, the said branching agent being
a 3,3-bis-(4-hydroxyaryl)-oxindole of the formula (I):
Rl
R2 ~ = O (I)
N
i H
R3
wherein
10 Rl denotes a 4-hydroxyaryl radieal and`
R2 and R3 can be identical or different and denote
hydrogen or halogen atoms.
Preferably, Rl denotes a 4-hydroxyphenyl or 4-
hydroxynaphthyl radieal or a radieal of the formula II
R4
~ OH (II~
wherein
R4 and R5 ean be identieal or different and denote halogen,
sueh as chlorine and bromine, methyl, ethyl,
espeeially methyl, or hydrogen.
Particularly preferentially, Rl is the 4-hydroxyphenyl
radieal.
LeA 16,142-ea ~ -6-
.,~
.
Preferably, R2 and/or R3 denote hydrogen, chlorine
or bromine, especially hydrogen.
The instant invention also relates to a thermoplastic
high molecular weight polycarbonate having a relative viscosity
5 of about 1.230 to 1.450 measured in a solution of 0.5 g in 100
ml of methylene chloride at 25C and an average light scattering
molecular weight, MLS, of about lQ,000 to 100,000 said poly-
carbonate being branched by about 0.05 to 2 mol % of a 3,3-bis-
(4-hydroxyaryl)-oxindole.
More particularly, the instant inven~ion relates to
a high molecular weight branched polycarbonate substantially
free of crosslinking which comprises a polycarbonate polymer
containing residues of aromatic dihydroxy compounds, about
0.05 to 2 mol % of a 3,3-bis-(4-hydroxyaryl)-oxindole of the
:.
~ 15 formula
^'
¦ N
R3 H
wherein Rl, R2 and R3 have the same meaning as defined above
and about 0.1 to akout 8 mol percent of a monohydric phenol,
the mol percentages being based on the mols of the aromatic
20 dihydroxy compounds, said branched polycarbonate having a
-relative viscosity of about 1.230 to 1.450 measured in a
solution of 0.5 g in 100 ml of methylene chloride at 25C
and an average molecular weight by light scattering, MLS of
about 10,000 and 100,000.
LeA 16,142-Ca ~ -6a-
~' I~ ..
)
,-~
1(3~
Finally, the instant invention relates to extruded
or injection-molded articles manufactured from the above-
mentioned polycarbonates..
Detailed Description of the Invention
In view of the statements in U.S. Patent Specifica-
LeA 16,142-Ca -6b-
~2
,~
64~
tion 3,256,242, according to which the amide group of 3,3-
bis-(4-hydroxyphenyl)-oxindole tisatin-bisphenol) does not
enter into the reaction when the compound is reacted with
dicarboxylic acid chlorides, and accordingly only linear,
unbranched polyesters are obtained, it is surprising that
isatin-bisphenols react, under polycarbonate-forming reaction
conditions, not only via the two phenolic hydroxyl groups
but also via the carboxylic acid amide group. Furthermore,
it is extremely remarkable that the isatin-bisphenols are
incorporated almost completely into the polycarbonate so
that even if small amounts of isatin-bisphenols are used,~
extremely effective branching is achieved. The polycarbonates
obtain according to the invention possess a particularly
pronounced structural viscosity behavior and show, in the
range of low rates of deformation, an apparent melt viscosity
which is advantageous for extrusions and which drops, at
high rates of deformation, to the point that processing by
injection molding becomes possible, that i~ to say one and
the same grade of polycarbonate can be proce~sed both by
extrusion processes and by injection molding processes.
In contrast to polycarbonates which contain cocon-
densed units of branching agents with phenolic hydroxyl
groups which are sterically not completely free, for example,
of 2,6-bis-(2'-hydroxy-5'-methyl-benzyl)-4-methylphenol
(tris-cresol), the branched polycarbonates according to the
invention are distinguished by excellent heat stability so
that even after five-fold extrusion they show only a slight
increase in the color number.
In addition, the extruded ribbon of the polycarbo-
nates according to the invention possess high shape reten-
LeA 16,142 -7-
tion (melt strength), so that the polycarbonates are also
suitable for the manufacture of hollow articles of large
volume in accordance with the extrusion-blowing process.
The isatin-bisphenols of the formula I which serve
as branching agents are obtained by the acid-catalyzed reac-
tion of the corresponding isatins of the general formula III
with monohydric phenols such as, for example, phenol and
~-naphthol, which do not possess any substituents in the
para-position to the phenolic hydroxyl group, or phenols of
the general formula IV
III R2 ~ o ~ 4 IV
R3
in which
the radicals R2~ R3, R4 and R5 have the ~ame
meaning as in the formulae I and II.
The isatin-bisphenols can be prepared in accordance
-- with, or based on, the instructions of A. Baeyer and M.J.
Lazarus, Berichte der deutschen Chem. Gesellschaft 18, 2637
tl885).
In the reaction, the phenolic component is employed,
- 20 or initially introduced, in an up to ten-fold molar excess
and the phenol melt at the same time serves as the solvent.
The course of the reaction can be accelerated by adding acids,
especially mineral acids, such as for example, H2SO4, H3PO4
and HCl. If the acid catalyst, for example, concentrated 8ul-
phuric acid, at the same time serveq to bind the water which
LeA 16,142 -8-
arises in the reaction, it can be added in amounts of up to
100% by weight, relative to the sum of the starting com-
pounds.
The reaction is carried out at temperatures of
about 20 - 200C, preferably of about 40 - 160C. The bis-
phenols which crystallize well can be isolated directly from
the phenol melt. After extracting the excess phenol with
water, alcohol or aromatics, such as benzene or toluene,
the isatin-bisphenols can be purified by dissolving them in
alkalis such as dilute soidum hydroxide solution or ammonia
solution and subsequently precipitating them in acids, or
by recrystallization from common solvents such as alcohol,
glacial acetic acid, ethyl acetate or benzene.
- Examples of suitable isatins for the preparation of
isatin-bisphenols of the formula I are isatin, 5-chloroisatin,
7-chloroisatin, 5-bromoisatin, 7-bromoisatin, 5,7-dichloro-
isatin and 5,7-dibromoisatin. Isatin itself is preferred.
Suitable monohydric aromatic hydroxy compounds
for regulating the molecular weight are monophenols such as
m- and p-methylphenol, m- and p-ethylphenol, m- and p-
propylphenol and m- and p-isopropylphenol, p-bromophenol
and m- and p-butylphenol. p-Tert.-butylphenol is preferred.
In addition to bisphenol A, all other bisphenols
can be used as the difunctional aromatic dihydroxyl compounds.
Examples of suitable bisphenols are hydroquinone, resorcinol,
4,4'-dihydroxydiphenyl and bis-(hydroxyphenyl)-alkanes,
-cycloalkanes, -sulphides, -ethers, -ketones, -sulphoxides
or -sulphones, as well as ~,~'-bis-(hydroxyphenyl)-diiso-
; propylbenzene and the corresponding nuclear-alkylated and
LeA 16,142 -9-
.
10~;4~
nuclear-halogenated compounds. Polycarbonates based on
4,4'-dihydroxydiphenylpropane-2,2 (bisphenol A), tetra-
chlorobisphenol A (2,2 - bis-(3,5-dichloro-4-hydroxyphenyl)-
propane), tetrabromobisphenol A ~2,2-bis-(3,5-dibromo-4-
hydroxyphenyl)propane) and tetramethylbisphenol A (2,2-
bis-(3,5 - dimethyl-4-hydroxyphenyl)propane) and on tri-
nuclear bisphenol, such as ~ bis-(4-hydroxyphenyl)-p-
diisopropylbenzene and mixtures of these compounds, are
preferred. Bisphenol A is particularly preferred.
Preferred mixtures consist of about 0.5 - 99.5
mol~, preferably about 98 - 70 mol%, of bisphenol A and
about 99.5 - 0.5 mol~, preferably about 2 - 30 mol% of
tetrahalogenobisphenol A.
Further bisphenols ~uitable for the preparation
of polycarbonate are described in U.S. Patent Specifications
3,028,365S 2,999,835; 3,148,172; 3,271,368; 2,970,131;
2,991,273; 3,271,367; 3,280,078; 3,014,891 and 2,999,846.
The branched polycarbonates according to the inven-
tion can be obtained by phase boundary condensation and
solution condensation at temperatures of about 20 to 80C.
In the known phase boundary condensation, for
example, the isatin-bisphenol is dissolved in sodium hydro-
xide solution together with the bisphenol component and
a water-immiscible solvent, such as, for example, methylene
chloride, dichloroethane or chlorobenzene, is added. After
introducing phosgene at room temperature, the polycarbonates
according to the invention are isolated directly in high
- yields from the organic phase by distilling off the solvent
or by precipitation, and maximum incorporation of the
LeA 16,142 -10-
'
:
branching agent is achieved. The chain length of the poly-
carbonates can be adjusted by adding a chain stopper, in
most cases a monofunctional phenol such as, for example,
phenol or p-tert.-butylphenol. The polycondensation can
additionally be accelerated by tertiary amines, for example,
triethylamine.
In the known solution condensation, phosgenation
is carried out in solution in the absence of water and with
at least a two-fold molar amount of pyridine, relative to
phosgene employed, together with a co-solvent, such as, for
example, methylene chloride. The pyridinium chloride pro-
duced, and excess pyridine, are removed by washing with
dilute mineral acids and the polycarbonate solution obtained
is worked up in the usual manner.
In the phase boundary process and solution pro-
cess it is also possible to use, in addition to phosgene,
other carbonyl halides, such as, for example, carbonyl
fluoride and carbonyl bromide or their mixtures, or bis-
halogenocarbonic acid esters of dihydroxy compounds, such
as, for example, hydroquinone bis-chlorocarbonic a~id
ester, as carbonate-forming compounds.
In the known melt trans-esterification the bis-
phenols are again reacted in the presence of about 0.05 to
2.0 mol~ of branching agent and in the presence of a basic
catalyst, such as sodium bis-phenolate, with carbonic acid
- diaryl esters, at temperatures of about 150 to 300C and
with application of a vacuum, the phenol component arising
from the trans-esterification being distilled off at the
same time.
LeA 16,142 -11-
.
'' '
.
~6~
~ xamples of carbonic acid diaryl esters which
can be employed are diphenyl carbonate, di-(halogenophenyl)
carbonates, such as di-(chlorophenyl) carbonate, di-~bromo-
phenyl) carbonate, di-(trichlorophenyl) carbonate, di-
(tribromophenyl) carbonate and thè like, di-(alkylphenyl)
carbonates, such as di-(tolyl) carbonate and the like, di-
(naphthyl) carbonate, di-(chloronaphthyl) carbonate, phenyl
tolyl carbonate, chlorophenyl chloronaphthyl carbonate or
mixtures.
In the formation of polycarbonates from either
.
the solution polymerization reaction or the interfacial
polycondensation reaction it is necessary to add chain
stoppers such as monohydric phenols to the hydroxy compounds
which are reacted with phosgene or bis-chlorocarbonic acid
esters in order to obtain the desired polycarbonate product
having the desired properties of this invention. However,
in the transesterification reaction, i.e. in the case of the
reaction of the bis-phenols with carbonic acid aryl esters
in the melt, it is only necessary to add the branching
agent in the above stated amounts and thus omit the addi-
tion of the monohydric phenols providing care is taken to
- prevent the monohydric phenol which is liberated by the
reaction from the diaryl carbonate from being completely
removed from the reaction mixture. As long as the mono-
hydric phenol is present in the amount specified above, it -
will automatically participate in the synthesis of the
polycarbonates.
In the co-condensation of bisphenol A with tetra-
halogenobisphenols, for example, tetrabromobisphenol A, in
accordance with the solution condensation, phase boundary
LeA 16,142 -12-
.: :
,
~6~
condensation or melt condensation processes, the incorpora-
tion of the isatin-bisphenols results in a very particularly
greatly reduced tendency to drip and excellent self-extin-
guishing burning behavior, which has not been observed, to
- 5 this degree, with any of the previously known branching
agents. ~:
These halogen-containing polycarbonates branched
via isatin-bisphenols attain classification 94 V-O according
to UL (Underwriter's Laboratories) burning test ~subject 94),
even in the case of thin test specimens of wall thickness
1/16 inch, and can, according to IBM test class A (Inflam-
mability Testing of Plastics DNH 6-0430-102) be flamed for
at least 60 seconds without producing burning drips or
: continuing to burn for more than 30 seconds, while the limit
of the flame exposure time of the corresponding unbranched
polycarbonate i8 merely 30 - 35 seconds.
The same excellent burning behavior is achieved
by adding flameproofing additives, especially the alkali
metal or ammonium perfluoroalkane (Cl-C8)-sulphonates
described in DT-OS (German Published Specifications)
1,930,257 and 2,253,072, and U.S. Patent 3,775,367 within
.~ the limit of 0.005 to about 1% by weight, to branched
:- halogen-free polycarbonates obtained in accordance with
: the invention.
In the process according to the invention it is
again possible, as usual, to add adjuvants of all kinds,
before, during or after the process of preparation.
Examples which may be mentioned in this context are dyestuffs,
pigments,mold release agents, stabilizers against the ac-
tion of moisture, heat and W , lubricants and fillers,
LeA 16,142 -13-
,
~ )6~
such as glass powders, quartz products, graphite, molybdenum
sulphide, metal powders, powders of higher-melting plastics,
for example, polytetrafluoroethylene powder, natural fibers,
such as cotton, sisal and asbestos, and also glass fibers
of very diverse kinds, metal filaments and fibers which are
stable when present in the melt of the polycarbonates and
do not significantly damage the polycarbonates.
The thermoplastic, high-molecular weight, soluble
and branched polycarbonates obtained according to the inven-
tion have relative viscosities nrel of about 1.230 to 1.450,
measured on solutions of 0.5 g product in 100 ml of methylene
chloride at 25C, average molecular weights, measured by
light scattering, of about 10,000 to 100,000 and apparent
melt viscosities of about 104 to 102 (Pascal sec (= Pas)) at
300C and at rates of deformation of 10 to 5.103 ~sec
The polycarbonates according to the invention can -~
be used both for processing by extrusion and processing by
injection molding. Because of the excellent shape retention ,
of the extrudate, they are also suitable for the manufacture
of hollow articles by the blow-molding process. The excel-
lent structural-viscosity properties make it possible
readily to obtain, for example, extruded films having good
- mechanical properties and reduce stress-cracking.
Shaped articles, such as moldings of all kinds,
such as housings, bobbins, covers, domestic appliances and
the like can be manufactured by injection molding.
.
The percentages indicated in the Examples are by
weight unless stated otherwise. The relative viscosities
nrel were measured on 0.5 per cent strength solutions in
LeA 16,142 -14-
methylene chloride at 25C. The apparent melt viscosities,
measured in Pascal.sec. (= Pas) at the particular rate of
deformation (sec 1) specified, were determined at 300C.
- Further details are to be found in the Examples.
Preparation of 3,3-bis-(4-hydroxyphenyl)-oxindole
147 g of isatin and 470 g of phenol were brought
together and heated to 85C. Hydrogen chloride gas dried
over sulphuric acid is then passed in at 85C, during which
- the reaction temperature rises to 115C. This temperature
is maintained and hydrogen chloride is passed in for a fur-
ther 5 hours. The resulting crystal paste is stirred into
500 ml of benzene and the crystals, colored light yellow,
which are thereupon obtained are filtered off and dried.
After recrystallization from acetone/chloroform and drying
in a water pump vacuum at 90C, 260 g (82% yield) of color-
less crystals are obtained. Melting point 267C.
:
C20HlSNO3 (317-35) Calculated C 75.7 H 4.73 N 4.41%
Found 75.6 4.68 4.46%
3,3-Bis-(4-hydroxyphenyl)-oxindole, described as
isatin-bisphenol in the Examples which follow, corresponds
to the formula
H
HO~
. ~q , .
.~ ~ .
HO
LeA 16,142 -15-
~LU~
Preparation of 3,3-bis-(4-hydroxynaphthyl)-oxindole
147 g of isatin and 720 g of ~-naphthol are brought
together and initially heated to 100C. Hydrogen chloride
gas dried over sulphuric acid is then passed in, during
which the temperature rises to 150C. After the exothermic
reaction has subsided the reaction temperature is maintained
at 115C for a further 5 hours and after cooling, 1,000 ml
of ethanol are added to the solidified crystal mass. The
crystals, freed from excess phenol, are filtered off and
dried. 334 g (80~ yield) of colorless crystals are
obtained from chloroform/acetone. Melting point 300C,
with decomposition.
C28HlgNO3 (417.47) Calculated C 80.60 H 4.55 N 3.36%
Found 80.48 4.51 3.42
3,3-Bis-(4-hydroxynaphthyl)-oxindole corre~ponds
to the formula --
OH
' :
H
The following Examples illustrate the invention:
Example 1
2.280 kg of bisphenol A (BPA) and 6.34 g of isatin-
bisphenol (0.2 mol ~ of branching agent, based on the bis-
phenol A as 100 mol %) are dissolved in 21 kg of 6.2%
strength sodium hydroxide solution under nitrogen. A solu-
LeA 16,142 -16-
tion of 38 g of p-tert.-butylphenol in 25 kg of unstabilized
methylene chloride is added and 1.285 kg of phosgene are
passed into the total reaction mixture over the course of 1
hour at 25~, while stirring vigorously at pH 13 - 14. 6 g
of triethylamine and 400 ml of 45% strength sodium hydroxide
solution are then added and condensation is allowed to con-
tinue for a further hour. The organic phase is separated
off and washed twice with 2% strength phosphoric acid, and
then with water, either three times or until the aqueous
phase is free from electrolyte. After distilling off the
solvent, 2.45 kg of polycarbonate of relative viscosity
nrel = 1.419 are obtained.
The DTA thermogram (DTA = differential thermal
analysis) confirms that the branched polycarbonate is heat-
stable up to at least 360C.
The flow as a function of the preheat time alsoproves the heat stability of the polycarbonate. Over a
period of 20 minutes, the apparent melt viscosity ~m
remains constant at 67,000 Poise.
Example 2
4.56 kg of BPA and 22.8 g of isatin~bisphenol
(0.36 mol % of branching agent, relative to bisphenol A)
are dissolved in 42 kg of 6.2% strength sodium hydroxide
solution under nitrogen and a solution consisting of 84
g of p-tert.-butylphenol and 50 kg of unstabilized methylene
chloride is added. While stirring vigorously, 2.57 kg of
phosgene are passed in over the course of 1 hour at room
temperature (pH of the solution 13 - 14). After adding 12
g of triethylamine and 850 ml of 45% strength sodium hydrox-
LeA 16,142 -17-
,' ' . ~ ':
..
ide solution the reaction is allowed to continue for afurther hour. When the alkaline phase is free from bis-
phenol A, the phases are separated and the organic phase
is washed twice with 2% strength phosphoric acid, and with
water three times or until no further electrolyte is
detectable in the wash water. 4.95 kg of branched polycarbo-
nate are obtained from the organic phase after distilling
off the solvent.
~ rel = 1.330 Mn = 34~700 ~ S = 49~300
~ S = molecular weight measured by light scattering.
Comparison Experiment A
:
A polycarbonate was prepared under the same con-
ditions as in Example 2 except that no isatin-bisphenol was
added as branching agent.
.~ . .
15 nrel = 1.325 M~ = 34,500 ~ S ' 34~900
Example 2 and Comparison Experiment A indicate the
high branching which is achieved by co-condensation of
isatin-bisphenol in the polycarbonate, as can be seen from
the difference of the molecular weights determined by vis-
cosity measurement and by light-scattering measurement.
Example 3
4.0 kg of bisphenol A, 11.12 g of isatin-bisphenol
(0.2 mol % of branching agent, relative to the bisphenol A)
and 1.32 g of sodium borohydride are dissolved in 21 kg of
6.2% strength sodium hydroxide solution under nitrogen. A
solution of 72.3 g of p-tert.-butylphenol in 44.0 kg of
(unstabilized) methylene chloride is added and 2.256 kg of
LeA 16,142 -18-
~3~
phosgene are passed in to the reaction solution over the
course of 1 hour at room temperature, while stirring vig-
orously and keeping the pH at 13 - 14. After adding 10.5 g
of triethylamine and 300 ml of 45% strenqth NaOH, the reac-
tion is allowed to continue for a further hour.
The organic phase is separated off and washed
twice with 2% strength phosphoric acid, and with water three
times or until the aqueous phase is free from electrolyte.
The solvent is distilled off and 4.3 kg of polycarbonate
of relative viscosity:~ rel = 1.340 are obtained.
~; The color numbers of the polycarbonate were deter-
mined as follows:
The measurements on the previously prepared 801u-
tion were carried out in a 5 cm thick cell with the sample
exposed to monochromatic test illumination, standard light
C, on a Hardy spectrograph (polycarbonate-free methylene
chloride being placed in the comparator beam). The chosen
concentration correspondR to a sheet thickness of 2.0 mm.
Number of extrusions 1 2 3 4 5
Color number 0.28 0.32 0.34 0.36 0.39
Comparison Experiment B
A branched polycarbonate was prepared in accordance
with the same process as in Example 3, but using 21.6 g of
tris-cresol (2,6-bis-~2'-hydroxy-5'-methylbenzyl)-4-methyl-
phenol) (0.2 mo~ ~, relative to bisphenol A) instead ofisatin-bisphenol as the branching agent. The color number
was determined analogously to Example 3.
LeA 16,142 -19-
Number of extrusions 1 2 3 4 5
Color number 0.31 0.45 0.51 0.58 0.67
It can be seen clearly that, while the initial
color number is about the same, the color number of the
polycarbonate prepared according to the invention only changes
slightly after 5 extrusions, while with the polycarbonate
from the comparison experiment a very marked change in the
color number can be observed after 5 extrusions, which
excludes use of the material for repeated extrusions.
. .
Example 4
3.030 kg of bisphenol A, 22.3 g of isatin-bisphenol
(0.5 mol %, relative to the sum of bisphenol A and tetra-
bromobisphenol A) and 1 g of sodium borohydride are dissolved
in a solution of 24.9 kg of water and 2.250 kg of 45~
strength sodium hydroxide solution, and 67.6 g of p-tert.-
butylphenol in 34.8 kg of unstabilized methylene chloride
are added. 2.070 kg of phosgene are passed in over the
course of one hour at 25C, with vigorous stirring, and
- thereafter a solution of 427 g of tetrabromobisphenol A in
2.4 kg of 6.2% ~trength sodium hydroxide solution is added.
In the course thereof, the pH value of the reaction solu-
tion should be kept at 10 - 11. After adding 60 ml of tri-
; ethylamine, the reaction is allowed to continue for a further
hour. The organic phaQe is separated off and washed twice
with 2% strength phosphoric acid, and with water three timesor until no further electrolyte is detectable. After con-
centrating the orgnaic phase, 3.75 kg of polycarbonate con-
taining bromine (bromine content 5.8~ by weight) and having
a relative viscosity ~rel = 1.284 are obtained.
LeA 16,142 -20-
Burning ch~racteristics:
UL Sub~ect 94 1/16 inch 94 v-O (best possible
value).
- IBM test (DMH 6-0430-102) Cl. A, 4 mm/60 sec.
According to the IBM test, the test bar must be
flamed for 60 seconds before the material begins to produce
burning drips or continues to burn for more than 30 seconds.
Comparison Experiment C
A polycarbonate containing bromine (5.8~ by weight
of bromine) is prepared in accordance with the same process
as in Example 4, but without addition of branching agent.
Burning characteristics:
UL Subject 94 1/16 inch 94 V-2
IBM test (DMH6-0430-102) Cl. B, 4 mm~'35 sec.
In the case of the unbranched polycarbonate, the
formation of burning drips and the continuation of burning
for more than 30 seconds commences after only 35 seconds
(flaming) and hence substantially earlier than for the
grades of material branched via isatin-bisphenol.
Example 5
228 g of bisphenol A, 227 g of diphenyl carbonate
and 0.634 g of isatin-bisphenol (0.2 mol %, relative to the
bisphenol A) are fused, together with 0.2 mg of sodium bis-
phenolate, in an oxygen-free atmosphere, the temperature
being raised from 200C to 300C over the course of 5 hours,
while the pressure is lowered from 100 mm Hg to 2 mm Hg.
After distilling off the phenol produced in the transesteri-
fication, a transparent polycarbonate of relative viscosity
LeA 16,142 -21-
1 ~ 3 6 ~
nrel = 1.265 is obtained.
Example 6
The dependence of the apparent melt viscosity on
the rate of shear was determined at 300C (nozzle L/D 20) for
- 5 the polycarbonates prepared in Example 4 and Comparison
- Experiment C, in order to make clear the pronounced structural
viscosity of the polycarbonates according to the invention.
a) Polycarbonate according to Example 4
Apparent
melt visco-
sity (Pas)3,9003,300 2,250 1,750 900 650
Rate of
deformation 1 2 2
(sec~l) 2 101 5xlO 10 5xlO 103
15 b) Polycarbonate according to Comparison Experiment C
Apparent
melt visco-
sity (Pas)1,1001,100 1,100 1,080 900 - ~-
Rate of 1 1 2 2 3
defo ~ation2 10 5xlO 10 5xlO 10
(sec
Example 7 Burning characteristics of compositions according
to the invention
A polycarbonate (relative viscosity nrel 1.343)
which was prepared analogously to Example 4, but without
tetrabromobisphenol A, using 0.5 mol %, relative to bisphenol
A, of isatin-bisphenol as a branching agent, and which con-
tained 0.1% by weight of potassium perfluorobutanesulphonate,
relative to polycarbonate, as a flameproofing agent, was sub-
jected to the burning test according to Subject 94 of
Underwriters' Laboratories, U.S.A.
LeA 16,142 -22-
3 ~f A.
Result: even with a minimum wall thickness of
specimen provided in this test, namely 1/16 inch, the
material was classified in the best rating category, namely:
94V-O. (No burning drips. Burning continues for <5 seconds).
.
Comparison Experiment D
The polycarbonate from Example 7, but without added
potassium perfluorobutanesulphonate, was examined by the
Subject 94 burning test of Underwriters' Laboratories,
- U.S.A.
Result: at 1/16 inch wall thickness the material
was not classified as a plastic of low inflammability, since
the time for which it continued burning was too long (>30
seconds).
Example 8 Processing by injection molding
Linear polycarbonates based on bisphenol A, pre-
pared according to the phase boundary process (see H. Schnell
"Chemistry and Physics of Polycarbonates" Interscience
Publisher (1964) page 33) and having a relative viscosity
~rel f about 1.290 are processed in the usual manner at
280C, using certain settings of the injection molding
machine (injection pressure, injection speed and the like)
to give standard thin-walled test specimens (length 127 mm,
` width 42.7 mm, thickness 1.6 mm). At lower temperatures,
problems in filling the mold arise. ~he apparent melt
viscosity of such a product is about 6.102 Pas at a low
rate of deformation (D~5 sec ).
The branched polycarbonate described in Example 7
; ~ could be converted to the thin-walled test specimens men-
LeA 16,142 -23-
: .: . : .
- ,
.
tioned under the same machine conditions, because of the
pronounced structural viscosity of the polycarbonate, even
though its apparent melt viscosity (5.5x103 Pas3 at a low
rate of deformation of ~5.sec 1 was almost 10 times greater.
S It is to be understood that any of the components
and conditions mentioned as suitable herein can be sub-
stituted for its counterpart in the foregoing examples and
that although the invention has been described in consider-
able detail in the foregoing, such detail is solely for the
purpose of illustration. Variations can be made in the in-
vention by those skilled in the art without departing from
the spirit and scope of the invention except as it may be
limited by the claims.
: .
LeA 16,142 -24-
. .
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'.: ~ :,,
