Note: Descriptions are shown in the official language in which they were submitted.
~ ~33~ 8CH-2526
This invention re]ates to aromatic polycarbonate resinshaving
improved flame retardance and improved water vapor transmission.
BACKGROUND O~ THE I~VENTION
Polycarbonate polymers are known as being excellent molding
materials since products made therefrom exhibit such properties
as high impact strength, toughness, high transparency, wide
temperature limits (high impact resistance below -60C and a U~
thermal endurance rating of 115C with impact), good dimensional
stability, good creep resistance, and the like. It would be
desirable to add to this list of properties that of improved
flame retardance so that products made from such polycarbonate
polymers could be safely used by the consumer and also meet the
increasing requirements of certain flame retardant criteria
being established by local and federal government agencies as
well as the manufacturers of such products. It would also be
desirable to improve the moisture barrier property of such poly-
carbonates thereby enabling them to be used in a wider range of
product applications.
It is known to obtain polycarbonates which contain halogen-
ated monomers as -their main, polymeric building blocks. For
example, U.S. Patent 3,028,365 discloses a host of polycarbonate
compositions including tetrabromobisphenol-A and a dichloro-
methylenediphenol monomer, as well as processes for obtaining
these polycarbonates.
U.S. Patent 3,062,781 discloses that halogenated polycar-
bonates can be obtained by first halogenating a diphenol contain-
ing at least two halogen substituents. However, the only
dihalogenated diphenol disclosed is dichlorobisphenol-A.
German Patent P25 20 317.2 discloses that halogenated poly-
carbonates can be obtained by halogenating bisphenol-A
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~3~03~ 8C~1-2526
(~,4~-isopropylidenediphenol) to produce a mix-ture of unreacted
bisphenol-A and statistical mixtures of halogena-ted bisphenol-A
(BPA). The halogenated bisphenols disclosed comprise, primarily,
tri- and tetrahalogenated BPA.
In general, these prior art re~erences recogniæe that flame
retardance can be imparted to polycarbonates by halogenating the
monomeric building blocks from which they are obtained. In
addition, these references suggest that the greater the degree of
halogenation of the monomer, the better will be the fire retar-
dance imparted to the polymer. U.S. Patent 3,062,781 also
indicates that halogenated diphenols have reduced permeability to
steam. However, none of these references discloses or sugges-ts
that a high molecular weight aromatic polycarbonate resin having
improved flame retardance as well as improved water vapor trans-
mission can be obtained from particular halogenated diphenols.
SUMMARY OF THE INVENTION
It has now been found that improved flame retardance and
water vapor transmission can be imparted to high molecular weight,
aromatic polycarbonate resins by selecting appropria-te diphenols
to be halogenated. In general, -this is accomplished by control
ling the degree to which the particular diphenols are halogenated.
Accordingly, the diphenols are halogenated so that there are
obtained either highly pure dihalogenated diphenols or predeter-
mined statistical mixtures comprising predominantly mono- and
dihalogenated diphenols together with some unreacted diphenol.
Preferably, these predetermined, statistical, halogenated
diphenol mixtures can be continuously obtained by either:
(l) dissolving or suspending the diphenol in a solvent system
comprising methylene chloride and water and thereafter introducing
~,~; ;, .
.~
~ CH-2526
a halogen into the solven~ system; or, (2) dissolving or
suspending the diphenol in methylene chloride and then reacking
the diphenol with sulfuryl chloride and, optionally,
introducing another halogen therein; or (3) dissolving
or suspending the diphenol in methylene chloride and then
introducing a halogen therein while concurrently purging the
reaction with an inert gas. These processes are described
inter alia in United States Patent 'L~O. 4,210,765 aated
July 1, 1980, which is assigned to the same assignee of
this case.
While any of the halogens can be employed, chlorine
and bromine are preferred~ Thus, the diphenols that can be
used to obtain the high molecular weight aromatic polycarbonates
of the invention can be represented by the general form~lla
Xn (I)
C\ { ~ OH
Xm ~ Y
wherein Xm and Xn can each independently be a halogen and
mixtures thereof; m and n are each 0.0 to about 2.5 with the
proviso that m + n equal at least 0.1 and no more than about 2.5;
and, Y and Y' can independently be hydrogen and a halogen,
preferably chlorine or bromine. In formula I above, the values
for m and n represent the number of halogen substituen-ts per mole
of monomer.
It is possible to employ two or more different diphenols
or a copolymer with a glycol or with hydroxy or acid terminated
polyester, or with a dibasic acid in the event a carbonate
copolymer or interpolymer rather than a homopolymer is desired
for use in preparing khe aromakic polycarbonate. Blends of any of
these materials can also be used -to obtain the aromatic
poLycarbonates.
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~CLI-2526
,
These halogenated diphenols can then be employed to obtain th~
high molecular weight aromatic polycarbonates of the invention
which can be linear or branched homopolymers or copolymers as
well as mixtures thereof or polymeric blends and which generally
have an intrinsic viscosity (IV) or about 0.40-].. 0 dl/g as
measured in methylene chloride at 25C. These high molecular
weight aromatic polycarbonates can be typically prepared by
reacting the halogenated diphenol with a carbonate precursor.
~he carbonate precursor used can be either a carbonyl halide,
a carbonate ester or a haloformate. The carbonyl halides can be
carbonyl bromide, carbonyl chloride and mixtures thereof. The
carbonate esters can be diphenyl carbonate, di-(halophenyl)
carbonates such as di-(chlorophenyl) carbonate, di-(bromophenyl)
carbonate, di-(trichlorophenyl) carbonate, di-(tribromophenyl)
carbonate, etc., di-(alkylphenyl) carbonate such as di(tolyl)
carbonate, etc., di-(naphthyl) carbonate, di-(chloronaphthyl)
carbonate, phenyl tolyl carbonate, chlorophenyl chloronaphthyl
carbonate, etc., or mixtures thereof. Th~ haloformates that can
be used include bis-haloformates o~ dihydric phenols (bischloro-
formates of hydroquinone, etc.) or ylycols (bishaloformates of
ethylene glycol, neopentyl glycol, polyethylene glycol, etc.).
While other carbonate precursors will occur to those skilled in
the art, carbonyl chloride, also known as phosgene, is preferred.
Also included are the polymeric derivatives of a dihydric
phenol, a dicarboxylic acid and carbonic acid such as are
disclosed in U.S. Patent 3rl69,121 dated February 9, 1965 -
Goldberg.
Molecular weight regulators, acid acceptors and catalysts
can also be used in obtaining the aromatic polycarbonates o~ tllis
--4
;~.
8CH-2526
invention. The use~ul molecular weight regulators inclu~e mono-
hydric phenols such as phenol, chroman-I, paratertiarybutylphenol,
parabromophenol, primary and secondary amines, etc. Preferably,
phenol is employed as the molecular weight regulator.
A suitable acid acceptor can be either an organic or an
inor~anic acid acceptor. A suitable organic acid acceptor is a
tertiary amine such as pyridine, triethylamine, dimethylaniline,
tributylamin~, etc. The inorganic acid acceptor can be either a
hydroxide, a carbonate, a bicarbonate, or a phosphate of an
alkali or alkaline earth metal.
The catalysts which can be employed are those that typically
aid the polymerization of the diphenol with phosgene. Suitable
catalysts include tertiary amines such as triethylamine, tripro-
pylamine, N,N-dimethylaniline, quaternary ammonium compounds such
as, for example, tetraethylammonium bromide, cetyl triethyl
ammonium bromide, tetra-n-heptylammonium lodide, tetra-n-propyl
ammonium bromide, tetramethylammonium chloride, tetramethyl
ammonium hydroxide, tetra-n-butyl ammonium iodide, benzyltrimethyl
ammonium chloride and quaternary phosphonium compounds such as,
for example, n-butyltriphenyl phosphonium bromid~ and methyl
triphenyl phosphonium bromide.
Also included herein are branched polycarbonates wherein a
polyfunctional aromatic compound is reacted with the diphenol and
carbonate precursor to provide a thermoplastic randomly branched
polycarbonate. These polyfunctional aromatic compounds contain
at least three functional ~roups which are carboxyl, carboxylic
anhydride, haloformyl, or mixtures thereof. Illus-tra-tive of
polyfunctional aromatic compounds which can be employed include
trimellitic anhydride, trimellitic acid, trimellityl trichloride,
4-chloroformyl phthalic anhydride, pyromellitic acid, pyromelli-
tic dianhydride, mellitic acid, mellitic anhydride, t:rimesic acid,
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~ 8C~1-2526
benzophenonetetracarboxylic acid, benzophenonetetracarboxylic
anhydride, and the like. The preferred polyEunctional aromatic
compounds are trimellitic anhydride and trimellitic acid or their
acid halide derivatives.
Blends of linear and branched aromatic polycarbonates are
also included within the scope of this invention.
Other well known materials can also be employed for their
intended function and inc]ude such materials as anti-sta-tic agents,
mold release agents, thermal stabili~ers, ultraviolet light
stabilizers, reinforcing fillers such as glass and other inert
fillers, foaming agents, and the li~e.
Accordingly, the high molecular weight aromatic polycarbon-
ates of the invention can be represented by the general formula
(II)
~ {~ I ~ O -- C
wherein Xm, Xn, m, n, Y and Y' are the same as identified in
formula I above.
PREFERRED EMBODIMENT OF THE INVENTIQN
The following examples are set forth to more fully and
clearly illustrate the present invention and are intended to be,
and should be construed as being, exemplary and not limitative of
the invention. Unless otherwise stated, all parts and percentages
are by weight.
In the following examples, the ilame retardancy of the poly-
carbonates obtained was determined by feeding the polycarbonates
into an extruder which was operated at about 26SC and the
extrudates were each cornminuted into pellets. The pellets were
then injection molded at about 3l5C in-to test bars of about 5 in.
.~. . .
~.
~CH-2526
by 1/2 in. hy about 1/16-1/8 in. thick. The test bars (5 for each
polycarbonate) were then subject to the test procedure set forth
in Underwriters' Laboratories, Inc. Bulletin UL-94, Burning Test
for Classifying Materials. In accordance with this test procedure,
materials so investigated are rated either V 0, V-I or V-II based
on the results of 5 specimens. The criteria for each V tfor
vertical) rating per UL-94 is briefly as follows:
"V-0": Average flaming and/or glowing after removal of
the igniting flame shall not exceed 5 seconds
and none of the specimen5 shall drip flaming
particles which ignite absorbent cotton.
"V-I": Average flaming and/or glowing after removal
of the igniting flame shall not exceed 25
seconds and the glowing does not travel
vertically for more than 1/~" of -the specimen
after flaming ceases and glowing is incapable
of igniting absorbent cotton.
"V II": Average flame and/or glowing after removal of
the igniting flame shall not exceed 25 seconds
and the specimens drop flaming particles which
ignite absorbent cotton.
In addition, a test bar which continues to burn for more than 25
seconds after removal of the igniting flame is classified, not by
UL-94, but by the standards of the instant invention, as "burns".
~5 Further, UL-94 re~uires that all test bars in each test group
must meet the V type rating to achieve the particular classifica-
tion Otherwise, the 5 bars receive the rating of the worst
single bar. For example, if one bar is classified as V-II and
the other four (4) are classified as V-0, then the rating for all
would be V-II.
-~;r
,~ - 7
~CH-2S26
0~
The moisture barrier properties for the polycarbonates and
copolycarbonates in the ensuing examples were determined using
Modern Controls, Inc. instruments, i.e., water vapor transmission
rate (WVTR) measurements were obtained on an I~D-2C instrument
pursuant to ASTM F-372-73. This method is based on infrared
analysis and the results obtained are expressed in grams/24 hrs./
100 in.2/mil at 100F and 90~ relative humidity (RH).
EXAMPLE 1
~ Compound: 2,2'-Dichloro-4,4'-
(dichlorovinylidene)diphenol (DCDVD)
Into a slurry of 281.14 parts by weight (l.0 partmole) of
4,4l-(dichlorovinylidene)diphenol (DVD) in 2000 parts by volume
methylene chloride that was purged continuously with a slow
stream of nitrogen, there was introduced, at ambient temperature,
in the course of ca. 5 hours, 142 parts by weight (2.0 partmole)
of chlorine gas. At the end of the slightly exothermic reaction,
only a small amount of DVD remained undissolved. This was
filtered off and the essentially colorless solution was analyzed
by gas chroma-tography, which indica-ted -the following compos:ition:
Retent~on Composition
Compound _ Time (Min.) (Mole %)
4,4'-(dichlorovinylidene)diphenol (DVD)18.97 0.2
2-chloro-4,4'-(dichlorovinylidene) 20.11 8.6
diphenol (CDVD)
2,2 7 -dichloro~4,4'-(dichlorovinylidene)20~91 91.0
diphenol (DCDVD)
2,2',~'-trichloro-4,4'-(dichlorovinyli- 21.91 0.2
dene)diphenol (TCDVD)
p-cumylphenol (reference) 12.36
Incremental addition of 2.8 parts by weight of more chlorine
raised the assay of dichloro-DVD (DCD~D) as follows:
~ 3~8CH-2526
Compound Composition (Mole %)
DVD 0
CDVD 2.2
DCDVD 93-7
TCDVD 4.1
Washings of the nearly colorless methylene chloride solution
with water produced a yellow methylene chloride solution tha-t was
separated from the aqueous phase. Circa one-fourth of its volume
of methanol was added to it and decolorized by stirring the
yellow solution with 5 parts by wei~ht zinc powder for about 1
hour. Filtration an~ evaporation of the solvent mixture on a
rotary evaporator left behind a white crystalline mass that was
recrystallized from a mixture of hexane and cyclohexane (1.0:1.5
volume ratio). The colorless crystals of 2,2'-dichloro-4,4'-
(dichlorovinylidene)diphenol thus ob-tained had an assay of 99.1%
and a melting point of 110.0-110.5C. Elemental analysis
confirmed its composition. Chlorine: found, 40.6; theoretical,
40.5~. Carbon: found, 4~.0; theoretical, ~8.0~ ~Iydrogen: found,
2,2; theoretical, 2.3%.
EXAMPLE 2
Preparation of the polycarbonate of 2,2'-Dichloro-
4,4' ~ )diphenol
Into a mixture of 87.5 parts by weight (0.25 partmole) 2,2'-
dichloro-4,4'-(dichlorovinylidene)diphenol (DCDVD), 300 parts by
volume water, 300 parts by volume methylene chloride, 0.47 parts
by weight phenol and 0.5 parts by weight triethylamine, there was
introduced, at ambient temperature, 30 parts by weight phosgene
in 30 minutes while maintaining the p~ value of the two-phase
system at approxima'cely 11 (between 10 and 12~5) by simultaneously
'~'
.,~.
8CH~252~
t~3~38
adding a 25 percent sodium hydroxide solution. ~t the end of the
addition period, the pH of the aqueous phase was 11.4 and the
DCDVD content o~ this phase was less than l part per million, as
determined by ultraviolet analysis. The methylene chloride phase
was separated from the aqueous phase, washed with an excess of
dilute lO.01 normal) a~ueous hydrochloric acid, and three times
with deionized water. The polymer was precipitated by adding
the neutral and salt-free methylene chloride solution to an excess
of methanol and filtering off the white polymer, which was dried
at 95C. The resultant pure DCDVD polycarbonate had the
properties shown in the Table.
EXAMPLE 3
The procedure of Example 2 was repeated except that DCDVD
was replaced with a mixture of 43.75 parts by weight DCDVD (0.125
partmole) and 28.5 parts by weight 4,4'-isopropylidenediphenol,
(BPA) (0.125 partmole). Work-up of the reaction product yielded
a copolycarbonate with the properties shown in the Table.
EXAMPLE 4
The procedure of Example ?. was repeated, except that DCDVD
was replaced with a mixture consisting oE 21.9 parts by weight
DCDVD (0.0625 partmole) and 42.75 parts by weight 4,4'-isopropyli-
denediphenol (BPA) (0.1875 partmole). The resultant polycarbonate
had the properties shown in the Table.
EXAMPLE 5
Preparation of a New Ternary Composition
The procedure of Example 1 was repeated except that 71.0
parts by weight (1.0 partmole) chlorine was employed. At the end
of the reaction, gas chromatographic analysis indicated the
following composition:
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8CH-2526
Reten~ion Composition
Diphenol Compound Time (Min.) (Mole %)
4,4'-(dichlorovin~lidene)diphenol 20.80 28.7
2-chloro-4,4'-(dichlorovinylidene) 22.34 45.2
diphenol
2,2'-dichloro-4,4'-(dichlorovinylidene) 23.52 26.1
diphenol
p-cumylphenol (reference) 15.32
~AMPLE 6
The procedure of Example 2 was repeated except for substitu-
ting an equivalent amount of the ternary mixture (78.9 parts by
weight) Gbtained in Example 5, for the 87.5 parts by weight of
DCDVD. A colorless, tough polycarbonate was obtained having the
properties set forth in the Table.
EXAMPLE 7
Preparation of a New Compound: 2,2'-Dibromo-4,4'-
(dichlorovinylidene)diphenol
The procedure of Example l was repeated, except that the
chlorine gas was replaced with an equivalent amount of liquid
bromine (320.0 parts by weight, 2 partmole), diluted with five
fold its volume of methylene chloride. After decolorization with
zinc powder and purification by charcoaling a white crystalline
mass, comprising 2,2'-dibromo-4,4'-(dichlorovinylidene)diphenol
was obtained that, after recrystallization from a hexane-cyclo-
hexane mixture (1:1) yielded white crystals of 97.8% purity and
107.5-108.5C melting point. Elemental analysis confirmed the
composition. Chlorine: found 16.1; theoretical, 16.2%. Bromine:
found 36.6; theoretical, 36.4%. Carbon: found 38.1; theoretical,
38.3%. Hydrogen: found, 1.8; theoretical, 1.8%.
EX~MPLE 8
The procedure of Example 2 was repeated except that 109.7
parts by weight (0.25 partmole) of 2,2'-dibromo-4,4'-(dichloro-
~ 8CH-2526
vinylidene)diphenol was usea in place of DCDVD. A polycarbonate
was obtained havin~ the properties set forth in the Table.
TABLE
Properties of Polycarbonates and Copolycarbonates
UL Ratin~
ExampleSpecimen Thickness
No. _ I.V. 1.56 mm 3.13 mm WVTR
2 0.55 V-0 V-0 1.4
3 0.588 V-0 V-0 3.3
4 0.592 V-0 V-0 6.1
6 0.576 V-0 V-0 1.8
8 0.482 V-0 V-0 3.0
As the results in the foregoing table reveal, excellent
flame retardance is imparted to the polycarbonates and copolycar-
bonates of the invention while concurrently improving their water
vapor transmission properties.
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