Note: Descriptions are shown in the official language in which they were submitted.
3~
.OLYCARBONATES STABILIZED BY HALOHYDROCARBON,
HALOCARBON OR SILANE GROUPS
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to my Canadian
copending application Serial No. 344 447; filed
January 25, , 1980, entitled "IMPROVE~
PLASTIC SOLAR PANEL STRUCI'URE AND METHOD AND
APPARATUS FOR MAKING THE SAME".
BACK~ROUND OF THE INVENTION
Numerous previous investigators have
described methods for chemically passivating
thermoplastic resins and for protecting certain
~hermoplastic resins from ultraviolet attack by
additives that absorb incident radiation. Rauhut
U.S. patent 3,974,368, Augusl: 10, 1976, describes
passivating polyethylene surfaces using silanes,
e.g., dimethyldichlorosilane and the like. Uhl
U.S. patent 3,810,775, May 1~, 1974, describes a
process for making water repellant fiberous
materials by applying a copolymer of ethylene and
a vinyl halosilane or vinyl alkoxy silane. Anyos
and Moyer U.S. patent 3l423,483, January 21, 1969,
describes production of a fluorescent polymer
using polybenzoxazole units.
2s A modern processparticularly suitable and
often employed for the production of thermoplastic
aromatic polycarbonates consists of reacting
phosgene with suitable bisphenols in an aqueous
solution or suspension of alkali or alkaline earth
r--~
~?
metal salts. The polycarbonates that are obtained
are high molecular weight linear chains of
repeating units "X" and "Y"; distributed more or
less at random; ranging from high ratios of
5 x to high ratios of ~ having end groups
" Y " " x "
of t~-] and {Rl-O-C-O~ where ~ is
'~-V~ }0~
. ~ n
and Y is ~-O-B-O-~-] all more fully described in
Wulff, Schnell, and Bottenbruch 3,4~2~065, January
1~, 1969.
The linear chain polycarbonate thus
produced can be cross-linked in the presence of
oxygen or free radical forming catalysts such a5
dibenzyl peroxide and dicumyl peroxide with the
resultant cross-linked polymer being much more
insc>luble than the linear polymer to high
tem~)erature steam. A preferred bisphenol
intermediate for the cross-linked polycarbonate i5
"Bi,phenol Cy" 1,1-bis(4 hydroxyphenyl)
cycLododecane, but the resulting cross-linked
resin presents substantially more difficult
processing parameters than the linear
polycarbonate.
;
Examination of the stepwise attack on
linear polycarbonates by strong bases offers an
alternative to cross~linking for purposes of
prod~!cing stress corrosion resistance while
retaining favorable processing characteristics.
Strong bases, and to a lesser extent, water, at
temperatures ranging from 140F to 200F produce
stres,s corrosion responses in linear
polycarbonates. This response is enhanced by the
presence of residual or induced stress and is
increased with increasing temperature. Stress
corrosion responses characterized by cracking,
pitting, loss of ductility, and weight loss by
mass fall out of exposed areas may be noted as
attacks following stepwise polymer bond
breakage. Chemical reactions first producing bond
breakage are most likely those involving
relatively energy-rich, vulnerable, end group
sites on the linear polymer chain. The compounds
formed by reacting the energy-rich units with
stress corrodant constituents are more voluminous
than the reactant and create a stress field
sufficient to cause macroscopic fractures. The
corrosion velocity or rate of attack is a function
of the rate of supply of an environmental
reactant, and the amount of energy or stress
available. Corrodant diffusion rates, surface to
volume effects, and crack opening by externa
forces thus play important roles in defining
attack velocities.
The importance of the end group's
chemical xeactivity may be noticed by comparing
preparation of thermoplastic polycarbonates with
the preparation of a thermoplastic polysulfone.
Polysulfone is prepared by reacting bisphenol A
,
and 4,4-dichlorodiphenyl sulfone with potassium
hydroxide in dimethyl sulfoxide. The
characteristic polysulfone resin
C~
~ ~ n
offers no site of high unit energy and minimal
potential for chemical reactions causing pressure
generating increased volume products. It is
necessary to remove all but slight traces of water
before polymerization to prevent hydrolysis of the
dihydric phenol salt, and subsequent formation of
the monosodium salt of 4-chloro-4-hydroxydiphenol
sulfone. End groups of [HO-] are absent.
In this connection consider the most
common polycarbonate polyester resin.
Polycarbonate polyesters produced from
bisphenol A are characterizedl by units of:
C~3 ' O ' '
3~ ! n
C~3
Bisp~enol a~it Carbonate
Radical
~0 Polycarbonate resins may be slowly
produced by a non-catalyzed condensation reaction
between bisphenol A and phosgene.
C13 ~ C313 "~
~3 CE~3 n
where n is the degree of polymerizationO
This reaction may be greatly accelerated
by basic catalysts. With basic catalyst
acceleration, the reaction is assumed to be:
~& ~ l2~ +~ ~
c~3 CE13 n
15 Mel~lorganic Bisphenol Phosgene Poly~arbonate ecipitate
Where M is typically Li, Na, or K,
obtained from a salt solution in aqueous medium or
from salt or hydride dissolution in the fused
bisphenol A resin.
Traces of the metal organic bisphenol,
the catalytic salt, the hydroxyl end groups, and
unreacted bisphenol in the polycarbonate resin may
cause stress corrosion through the following
typical stress producing reactions.
''
.
~`
H3 CH3
{}OM t H20 ~ 2 t ~ O EQ-3
3 , CH3
., . : . . .. . .
Exceptionally high proton mobilities in
certain phases such as ice compared to water are
illustrative of proton transfer along the hydrogen
bond. Protons released by reactions with
polycarbonate constituents also diffuse, forming
hydroxyl and hydronium stress producing radicals,
CH3 C~3
H2 I HO-O_ C {~-- OH ~ H~ {} I ~ OH EQ-4
3 ;~
CH~ CH3
HO {~_ C {~- OH ~2H ~ ~ o ~ C {} O~ EQ-4a
C~3
102Na HCO3 ~ Na2CO3 I H20 ~ CQ2 EQ-5
Polycarbonate resins may also be produced
I by catalytic synthesis of bisphenol A and carbon
: monoxida:
.
-
3~
C33 [ C33
This reaction is promoted by firstdissolving the bisphenol A in a suitable solvent
such as tetrahydrofuran (THF) and then activating
it with hydrogen. Activated hydrogen is
introduced to the bisphenol A through the high
shear path of reactor 300 in FIGURE S (described
later) to produce the following activated
intermediate:
CB3 3~ ~3 E3
0 8~ C ~l + (B~H) ~ ~o{~--C ~0 . E~7
CE13 H CH3 B
The activated intermediate is then
immediately reacted with carbon monoxide to
produce polycarbonate.
.
.: -
~1 ~3 8 _ _
+~.. {>~ .~2~2 E~8
~i a~3 E~ CE13
This linear molecule may be grown as
large as desired in the form:
~-] ~}~,,~~ 1 ~
SUMMARY OF THE INVENTION
It is an object of the present invention
to pro~duce aromatic polycarbonate resins having
strongly bonded end caps resulting in uniform unit
site free energies of ~ormation and resistance to
chemical attack.
It is a further object of this invention
to produce aromatic polycarbonate resins having
strongly bonded fluorescent polymer units
resulting in interaction with incident light to
wave shift ultraviolet radiation portions to
visible and infrared radiation.
It is another object of this invention to
produce within aromatic polycarbonate resins
uniform unit site free energies of formation and
include fluorescent polymer units during initial
polymerization steps.
It is an additional object or this
invention to react aromatic polycarbonate resins
with halogenated organo compounds during
thermoplastic processing of the polycarbonate
resin to produce more or less uni~orm free energy
unit ites throughout the poly~arbonate chain
including end caps. This object is further
defined as a cost effective means for limiting the
amount of reactant halogenated organosilane to
only l:he replacement requirement for labile
protons occurring at the molecular chain ends.
Stress relief annealing may be useful in
occasional conventional polycarbonate product
instances but upon the application of mechanical
loads or thermal stress in the presence of a
stres~; corrodant, product failures may be
expect:ed. The linear polycarbonate can, however,
be moclified by preferentially reacting hydrogen at
the end units with a suitable halogenated
intermediate such as 1,1 1-trichloro-2,2,2-
trifluoroethane according to the following type:
Old
E~ , E~
Group `}~ }~ , o a~p
3a ~ ~ C--C~A{~ ])~2 + 13CF3 t [C~3OE'2
~ O--~--A--~ O-C~n~ O--C-O_]n2 + ~
,
'
,~
.,
In the formulae R is an alkyl,
cycloalkyl, aryl, or alkoxy group or halogen
atoms, and n is an integer of from 0 to 4.
Examples of alkyl radicals represented by R above
having from 1 to 10 carbon atoms, preferably from
1 to 5 carbon atoms, are methyl, ethyl, propyl,
isopropyl, butyl, pentyl, hexyl, octyl, and decyl;
aryl radicals such as phenyl, naphthyl, biphenyl,
tolyl, xylyl, and 50 forth; aralkyl radicals such
as benzyl, ethylphenyl, and so forth; cycloalkyl
radicals such as cyclopentyl, cyclohexyl, and so
forth; alkoxy radicals having from 1 to 5 carbon
atoms, preferably from 1 to 3 carbon atoms are
methoxy, ethoxy, propoxy, butoxy, pentoxy, as well
as monovalent hydrocarbon radicals containing
inert substituents therein such as halogen atoms,
e.g., chlorine, bromine or fluorine may be
employed. It will be understood that where more
than one R is used, they may be alike or
different.
In the formulae A can be cycloalkylene,
alkylidene, cycloalkylidene, or sulfone, Rl can be
alkylene, alkyleneoxyalkylene, poly(~lkyleneo~y-
alkylene~ or arylene, nl is an integer o~ at least
one and n2 is 0 or an integer of at least one.
The total of nl and n2 is such that the polymer
normally has a molecular weight of more than about
10,000, usually at least about 20,000 and can be
up to about 150,000 or higher. When n2 is arylene
then nl can be 0. Preferably, however, there are
more nl units than n2 units.
The polymers are prepared in conventional
fashion by reacting phosgene with the appropriate
dihydroxy compound or mixture of dihydroxy
35 compc,unds.
Examples of suitable dihydroxy compounds
for preparing the polycarbonates are bis(4-
hydroxyphenyl)-cyclododecane r 1~ l-di~ ( 4-
hydroxyphenyl)-ethane, l,1-di-(4-hydroxyphenyl)-
propane, lrl-di-(4-hydroxyphenyl)-butane, l,l-di-
~4-hydroxyphenyl)-2-methyl-propane, 1,1-di-(4-
hydroxyphenyl~-heptane, l,l-di-(4-hydroxyphenyl)-
l-phenylmethane, di-(4-hydroxyphenyl)-4-
methylphenyl-methane, di-(4-hydroxyphenyl)-4-
ethylphenylmethane, di-(4-hydroxyphenyl)-4-
isopropylphenyl-methane, di-(4-hydroxyphenyl)-4-
butylpllenyl-methane, di-(4-hydroxyphenyl)-
benzylmethane, di-(4-hydroxyphenyl)-alpha-
furylmethane, 2,2-di-(4-hydroxyphenyl)-octane,
lS 2,2-di-(4-hydroxyphenyl)-nonane, di-(4-
hydroxyphenyl)-l-alpha-furyl~-ethane, l,l~di-(4-
hydroxyphenyl)-cyclopentane, 2,2-di-(4-
hydroxyphenyl)-decahydronaphthalene, 2,2-di-(4-
hydroxy-3-cyclohexylphenyl)-propane, 2,2-di-(4-
hydroxy-S-isopropylphenyl)-butane, 1,1-di-(4
hydroxy-3-methylphenyl)-cyclohexane, 2,2-di-(4~
hydroxy-3-butylphenyl)-propane, 2,2-di-(4-hydroxy-
3-phenylphenyl)-propane, 2,2-di-(4-hydroxy-2-
methylphenyl)-propane, l,l-di-(4-hydroxy-3-methyl-
6-butylphenyl)-butane, 1,1-di-~4-hydroxy-3-methyl-
6-t:ert.-butylphenyl)-ethane, 1,1-di-(4-hydroxy-3-
methyl-6-tert.-butylphenyl)-propane, 1,1 di-(4-
hyclroxy-3-methyl-6-tert.-butylpheiqyl)-butane, 1,1-
di-(4-hydroxy-3-methyl-Ç~tert.-butylphenyl)-
isobutane, 1,1-di-(4-hydroxy-3-methyl-6-tert.-
butylphenyl)-heptane, l,l-di-(4-hydroxy-3-methyl-
6-lert.-butylphenyl)-1-phenyl-methane, 1,1-di-(4-
hydroxy-3-methyl-6-tert.-butylphenyl)-2-methyl-2-
pentane, 1,1-di-(4-hydroxy-3-methyl-6-tert.-
butylphenyl)-2-ethyl-2-hexane, 1~1-di-(4~hydroxy-
.
. ~ :
12
3-methyl-6-tert.-amylphenyl)-butane, di-(4-
hydroxyphenyl)-methane, 2,2-di(4-hydroxyphenyl)-
propane, l,l-di-(4-hydroxyphenyl)-cyclohexane,
1,1-di-(4-hydroxy~3-methylphenyl)-cyclohexane,
1,1-di-(2-hydroxy-4-methylphenyl)-butane, 2,2-di-
(2-hydroxy-4-tert.-butylphenyl)-propane, l,l-di-
(4-hydroxyphenyl)-1-phenylethane, 2,2-di-(4-
hydroxyphenyl)-butane, 2,2-di-(4-hydroxyphenyl)-
pentane, 3,3-di-(4-hydroxyphenyl)-pentane, 2,2-di-
(4-hydroxyphenyl)-hexane, 3,3-di-(4-
hydroxyphenyl)-hexane, 2,2-di-(4-hydroxyphenyl)-4-
methylpentane, 2,2-di-(4-hydroxyphenyl)-heptane,
4,4-di-(4-hydroxyphenyl)-heptane, 2,2-di-(4-
hydroxyphenyl)-tridecane, 2,2-di-(4-hydroxy-3-
methylphenyl-propane, 2,2-di-(4-hydroxy-3-methyl-
3'-isopropylphenyl)-butane,2,2-di-(3,5-dichloro-4-
hydroxyphenyl)-propane, 2,2-di-(3,5-dibromo-4-
hydroxyphenyl)-propane, di-(3-chloro-4-
hydroxypnenyl)-methane, di-(2-hydroxy-5-
fluorophenyl)-methane, di-(4-hydroxy-phenyl)-
phenylmethane, l,l-di-(4-hydroxyphenyl)-1-
phenylethane, and the like.
Any suitable aliphati dihydroxy compounds
may be used such as for example, ethylene glycol,
~5 diethylene glycol, triethylene glycol,
polyethylene glycol, thioglycol, ethylene
dithioglycol, 1,3-propane-diol, 1,3-butanediol,
1,4 butanediol, 1,3~(2-methyl)-propanediol, 1~5-
pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-
decanediol and the like.
Any suitable cycloaliphatic dihydroxy
compound may be used such as, for example, 1,4-
cyclo-hexane-diol, 1,2-cyclohexane-diol, 2,2-
(4,4'-dihydroxy-dicyclohexylene)-propane, and 2,6-
dihydroxy-decahydro-naphthaleneO
3~
13
Examples of suitable aromatic dihydroxy
compounds which may be employed are hydroquinone,
resorcinol, pyrocatechol, 4,4'-dihydroxydiphenyl,
1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthanele,
1~4-dihydroxynapthalene, 1,5-dihydroxynaphthalene,
dihydroxyanthracene, 2,2'-dihydroxydinaphthyl-
l,li- and o, m, and p-hydroxybenzyl alcohol and
the like.
In addition, di-(monohydroxyaryl)-
sulfones may be employed such as, for example, di(4-hydroxy-phenyl)-sulfone, di-(2-hydroxyphenyl)-
sulfone, di-(3 hydroxyphenyl)-sulfone, di-(4-
hydroxy-2-methylphenyl)-sulfone, di-(4-hydroxy-3-
methylphenyl)-sulfone, di-(2-hydroxy-4-
methylphenyl)-sulfone, di-(4-hydroxy-2-ethyl-
phenyl)-sul~one, di-(4-hydroxy-3-ethylphenyl)-
sulfone, di-(4-hydroxy-2-tert-butylphenyl)-
sulfone, di-(4-hydroxy-3-tert.-butylphenyl~-
sulfone, di-(2-hydroxy-1-naphthyl)-sulfone and the
like.
The preferred polycarbonates are those
made from either bisphenol A alone or a mixture of
bisphenol A and bisphenol Cy. When the poly-
carbonates are made from a mixture of bisphenol Cy
(or ring substituted bisphenol Cy) with bisphenol
A (or other dihydric compound) the polycarbonate
will have X repeating units from the bisphenol Cy
and Y repeating units from the other dihydric
compound (e.g., bisphenol A) in which the ratio of
the units X:Y can vary widely, e.g., the ratio X:Y
can vary from 5:95 to 95:5.
In addition to the phenolic hydroxy end
groups, the polymer also can have the end group
R2-O-~~O- where R2 is alkyl up to 4 carbon atoms,
14
e.g.l methyl, ethyl, propyl or butyl, cycloalkyl
up to 6 carbon atoms, e.g., cyclopentyl or
cyclohexyl, phenyl, alkylphenyl, e.g., p-tolyl,
o-tolyl, p~ethylhexyl or p-butylphenyl, cycloalkyl
phenyl, e.g., p-cyclohexyl-phenyl, phenylamino,
etc.
Elimination of an end group hydrogen and
capping the polycarbonate chain end with a
hydrophobic unit exemplifies one goal of the
invention~
The preferred method for elim nating the
vulnerable end unit hydrogen in the polyc~rbonate
chain is to react dried pol~mer~ produced as
described above, e.g., in the manner described in
the Wulff et al patent 3,422,065, with suitable
pressurized vapor such as halogenated organo
silicon compounds during pelletizing extrusion
operations. This reaction is facilitated by the
high surface to volume ratio of the powder and
flakes of the polycarbonate resin feed stock, the
agitation and kneading provided by the action of
the extruder feed screws, and by the elevated
temperatures attendant the melt-in process. The
preferred point of vaporous reactant introduction
(see FIGURE 2) is near the melt plug of the
extruder 100. Hydrogen chloride, HBr, or HF gas
or other gas produced by the reaction is
preferably vented to a water aspirator 102
connected to the upper portions of the reaction
extruder at 104.
By choosing the intermediate chemical to
have end capping and fluorescent functions,
another goal of the invention may be realized.
For instance, 0.5 to 1.0 weight percent
trichlorodiphenyltriphenodioxazine may be added to
3~3~
polycarbonate during initial polymerization for
purposes of producing a chemically bound
fluorescent unit through labile hydrogen
displacement. The resulting 6,13-dichloro-3,10-
diphenodioxazine unit has good stability and
serves to convert incident U.V. radiation into
longer wave length visible and infrared
radiation. Other suitable fluorescent end caps
include benzoxazole: produced by labile hydrogen
displacement by chlorobenzoxazole or
chlorobenzoxazole silane.
The polymerization end cap addi~ion of
fluorescent units having about the same energy of
formation as other polycarbonate units provides
permanent U.V. and stress corrosion protection to
the altered resin. U.V. energy is converted to
visible and in~rared energy. Stress corrosion is
prevented because there are no energy-rich sites
for chemical attack.
The vulnerable phenolic hydrogen on the
polycarbonate can be reacted with other
appropriate halogenated intermediates, especially
where the halogens are fluorine, chlorine or
bromine, as well as with silanes. Typical
compounds are volatile halocarbons,
halohy~rocarbons, halosilanes, halohydrosilanes.
There can also be employed silanes which are
devoid of halogen. Examples of suitable reaction
intermediates o~ the types just described are set
forth in Table 1.
.. ; -. . , . :
. ~ .
; ~
.
.
16
Table 1
Reaction Intermediates
Com
pound
11 methacryloxypropyltri-
methoxysilane CH2=C(CH3)COO(cH2)3si(ocH3)3
12 m~ercaptopropyltrimethoxysilane HSCH2CH2CH2si(OcH3)3
13 glycidoxypropyltrimethoxysilane CH2~ CH2O(CH2)3Si(OcH3)3
14 amin~propyltriethoxysilane H2NCH2CH2cH2si(C2H5)3
36 carbon tetrachloride ~C14
15 trichlorofluoromethane CC13F
16 dichlorodifluoromethane CC12F2
17 chlorotrifluoromethane CClF3
18 bromotrifluoromethane CBrF3
35 carbontetrafluoride CF4
19 chloroform CHC13
20 dichlorofluoromethane CHC12F2
21 chlorofluoromethane CH~ClF
22 methylene fluoride CH2F2
23 1,1,2,2-tetrachloro-1,2-
difluoroethane CC12FOC12F
24 1,1,1,2-tetrachloro-2,2-
difluoroethane CC13CCIF2
251,1,2-trichloro-1,2,2-
t~ifluoroethane CC13FCClF2
261,1,1-trichloro-2,2,2~
tri~luoroethane CC13CF3
271,2-dichlorohexa~luorocyclobutane C4C12F6
28 chloroheptafluorocyclobutane C4ClF7
29 octafluorocyclobutane C4F8
chloromethyldimethylchlorosilane ClCH2(CH3)2SiCl
1 trimethyl~hlorosilane (CH3)35iC
3 trichloromethylsilane CH3SiC13
17
Table 1 (Continued)
2 s,ilicon te~rafluoride SiF4
30 silicon tetrachloride SiC14
31 hydrasilicontrifluoride ESiF3
6 hydrasilicontrichloride ~SiC13
32 disilicon hexafluoride Si2F6
33 disilicon hexachloride Si2Cl~
34 t:etrasilicon decafluoride Si4Flo
' 7 silicon fluorochlorodibromide SiFCIBr2
8 methyl trichlorosilane (CH3)SiC13
37 dimethyl dichlorosilane (CH3)2SiCl2
9 1:rimethyl bromosilane (CE3)3siBr
4 ~riethylchlorosilane (C~2Hs)SiCl
10 hexaethyldisilane (C2H5)65i2
38 :Eluoroform C~F3 OCH3
39acryloxypropyltrimethoxysilane CH2-CHC~20~H2CH2CH2-Si OCH3
: OCH3
TABLE 2
ound Fluorescent Reaction Intermediates
41 6,13-trichloro-3-10-diphenyl-
triphenodioxazine
fluorodichlorodiphenyltriphenodioxazine
44 quinine chlorosulfate
~6 3-aminochlorophthalimide
l15 n-nitrochlorodimethylaniline
43 aluminum chelate of 2,2'-dihydroxy-1- ?
l'azonaphthalene-4-sulfonic acid
47 4-dimethylchloroamino-4-nitrostilbene
48 Rhodamine B-chlorosilane
: 49 Magdela Red Chlorosilane
42 Zinc trimethylsulfide
:
18
,Table 2 (Continued)
Zinc dialkyl dithiocarbamates
52 4-(4-Nitrophenylazo) chlorophenol
53 Zinc ethyl xanthate
54 Zinc fluoromethylsilane
59 Zinc ethyldichloroformate .,
57 Zinc isopropyldichlorofQrmate
56 Zinc phenyldichloroformate
58 Zinc 1; 4 cyclohexanediol
bischloroformate
Rhodamine 110
66 Rhodamine 19 Perchlorate
67 Zinc Xanthene
68 Silicon Xanthene
Rhodamine 123
72 l-Naphthoyl Chloride
5~i Zinc benzoyldichloride
Zinc phenylchlorocarbonate
61 Rubrene chloride
62 Sodium Fluorescein
63 Rhodamine B
64 Rhodamine B. Perchlorate
It s~ould be realized that Table 1 and
Table 2 are illustrative only and the reactive
intermediates are not limited thereto.
The amount of fluid reactant for
replacing the phenolic hydrogen is not critical.
There should be enough employed to remove all of
the phenolic hydrogen atoms to provide the
hydrophohic end unit but an excess of the fluid
reactant can be employed.
-
19
Referring for the moment to previous
Equations 1 through 8, as has just been pointed
out, upon reaching the desired molecular weight,
the polymerization is terminated by addition of an
end cap intermediate selected from Table 1 or
Table 2 to produce desired chemical and physical
properties.
This end capping reaction is typified as
shown in Equation 9.
~o{~ c 0~ -.c--o [-O~ H
CH3 al3 CO 13
(CH3)~ Sill ~ CH~ --Si-- [; {~ C ~ 13 ~ HC~ EQ-g
C~13 CH3 CH3
Polymer produced by the above set out
technique may be separated from the solvent by
evaporation whereupon a clear film of tough stress
corrosion resistant polycarbonate is cast. This
film may be cast upon selected substrates to
produce laminates or spray cast upon silicone or
- fluorocarbon trays, conveyers, or wheels that
allow peeling or shedding away the dry film for
chopping and thermoplastic processing into film,
sheet, tube and profiles.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be understood best in
connection with the drawings wherein:
FIGURE 1 shows vertical plasticizing
extruder for carrying out the process of the
invention;
FIGURE 2 shows the screw and barrel
assembly of the extruder of FIGURE l;
FIGURE 3 illustrates details of the vent
and port of the extruder;
FIGURE 4 is a diagrammatic illustration
of a polycarbonate polymerization unit;
FIGURE 5 is a diagrammatic illustration
of a system for polymerizing polycarbonate;
FIGURE 6 is a diagrammatic illustration
of a system for producing carbon monoxide; and
FIGURE 7 is a diagrammatic illustration
of a reactor used in the system of FIGURE 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
zo As shown in FIGURE 1, the polymer
conversion objects of the invention may be
realized with the aid of a plasticizing
extruder. In operation, feed polycarbonate resin,
usually in the form of powder granules, flakes, or
pellets is loaded by a suitable means s^~ch as
vacuum loader 4 into drying hopper 5. Resin
entered into hopper 5 is held in residence until
dry. This is usually accomplished by circulation
of 250F dessicant dried -60F dew point air for
resin exposures of 2 to 4 hours. Resin is then
continuously fed by a double lead extension (not
shown) of screw 106 that extends about 12" into
3q~
21
the bottom zone of hopper 5. Resin at about 250F
entering the upper zone (ZONE 1) of the 3-1/2"
30/1 L/D extruder is controllably further heated
to between 300F and 450F by suitable sources
such as electric resistance band heaters,
circulating hot oil heaters, or steam jacket
heaters. A vaporous reactant such as any of those
set forth in Table 1 are delivered under suitable
pressure from source container 108 to pressure
regulator 110 and through line 112 to extruder
barrel 116 at a entry port 114. Entry port 114 is
suitably an annular ring 3/8" wide x 1/4" deep
machined into the inside diameter or bore of the
outer shell of extruder barrel 116 at about 24"
below the entry to barrel 116. This distributor
port ring is covered by barrel inner liner of
wear-resistant material selection typically no
more than 1/4" in thic~ness. Small diameter
(preferably 0.030" max.) holes spaced at 1/4"
circumferential intervals in the wear-resistant
inner liner tube thus communicate the vapors
delivered from 112 to the resin mass within the
extruder.
The reactant vapors are delivered under
sufficient pressure to flow into the compressed
but non-fused resin mass and travel in both axial
directions, toward the resin entry and toward the
extruder output. Vapor entrainment into the resin
mass is assured by the kneading action of screw
106. It is preferred to cause entering resins
within the feed section to be more tightly
compressed than at the first transition section.
This i,s accomplished by utilizing a double screw
flight design within the feed section followed by
a single screw flight design through the first
- . . . ~ . .
.
22
transition and remaining screw sections. The
entry zone for reactant vapors therefore, is
preferably at a point below more tightly compacted
resin and above a resin fusion point. As shown,
the extruder screw flight depth is preferably
gradually diminished through the transition zone
to a first meter zone. Melt fusion of the resin
at the lower portion of the first meter zone is
maintained by control of the heater band setting
in the first meter zone in conjunction with the
screw rpm. Vapors entering barrel assembly 116
through port ring 114 are immediately reacted with
resin surfaces and continue to react as the resin
and entrained vapors are recompressed and resin
melting occurs. Venting of by-product vapors such
as HCl, HBr, and other volatiles through vent ring
104 is preferably at a point where approximately
60~ to 80% of the resin mass has fused. Vent 104
is preferably an annular gap 3/8" wide x 14" deep
machined in the inside diameter outer shell of
barrel assembly 116 about 56" below the top of the
barrel. This ring is fitted with a porous
sintered particle type 310 stainless steel
cylinder treated with polytetrafluoroetylene for
the purpose of allowing non-plugging venting of
unreac~ed vapors and by-product vapors to a
suitabLe disposal facility. Vaporous effluent
from 104 is delivered under developed pressure or
to a suitable pump 102. This pump may be a water
seal vacuum pump such as a NASH 1/2 HP or a water
aspirator of common design. Hydrogen halide
vapors and resulting a~ids produced by the above-
described reactions are then neutralized by
suitable bases such as sodium hydroxide or other
low cost alkaline mediums in sump 120.
23
Plastic resin masses achievin~ 100~
fusion in the first melting zone continue to be
worked by the action of screw 106 and undergo
thGrough homogenization through second transition
and second meter zones of the extruder before
exiting as completely reacted, homogeneoust stress
corrosion and ultraviolet radiation resistant
thermoplastic suitable for forming by dies into
any desirable shape.
Preparation of stress corrosion resistant
polymers may be more desirable for some products
than preparation of combined ultraviolet and
stress corrosion resistant poly~mers. Selection of
reactants from Table 1 offers a wide variety of
final properties in addition to improved stress
corrosion resistance. For instance, extruded
sheet and film products made from Compound 11, 12,
13, 14 (Table 1) vapor reacted polycarbonate has
enhanced adhesion to printing inks without the
need for conventional primers, corona discharge,
or flame treatments. Hot melt resin products made
from polycarbonate resin so treated develop
improved adhesion to all polyesters and thus offer
an important improvement to weld joining
techniques.
By using Compounds 2, 15, 16, 17, 18, 20,
21, 22, 23, 24, 25, 26, 27, 28, 29, 32 and 35
(Table 1), the resulting stress corrosion
resistant poly~carbonate is particularly grease and
3Q water repellant and thus suited for food service,
home funishing, and similar applications requiring
antisoiling and low adhesion qualities. Products
may be injection molded, fabricated sheet-like
forms, or made from fiberous embodiments and
retain desired antisoiling properties.
24
Somewhat more economical achievement of
greatly improved stress corrosion resistance and
for some applications a desirable degree of
hydrophobicity follows treatment using Compounds
1, 3, 4, 5, 8, 9, 10 and 37 (Table 1) reactant
vapors.
The vapor reactants cited above for
purposes of producing improved stress corrosion
and ultraviolet resins vary greatly in chemical
reactivity. This is particularly true with
respect to the agitation, smearing, and kneading
of tlle reactants at elevated temperatures as
provided by the extruder. Thus it has been found
useful in some cases to dilute the vapors with an
inert carrier gas such as carbon dioxide,
nitrogen, argon, or dry air for purposes of
preventing explosive rates of reaction during
introduction to the barrel at entry pressures
sufficient to overcome locally existant resin
pressures.
For instance, a mixture of 2~ to 5%,
e.g. r 3.5%, trimethylchlorosilane in 95~ to 98%,
e.g., 96.5%, nitrogen (by volume) at an entry
pressure o~ 5 to 7, e.g., 6, atmospheres at 114
and 10 to 20 atmospheres at 126 provides complete
conversion of conven~ional bisphenol A based
polycarbonate to stress corrosion resistant resin
in a Type 430 outer tube, Type 431 hardened inner
liner, Type 431 hardened and chrome plated screw,
3-1/2" diameter 30/1 L/D ratio extruder.
Nitrogen, hydrogen chloride gas, and unreacted
excess trimethylchlorosilane pass through vent 104
to dlsposal or recovery sink 120.
`6
FIGURE 3 illustrates details of vent 104
and port 114. (Port 12Ç is typical to port
114.) Braze sealed 3/8" AN type tube fitting 172
is sufficiently large enough for adding reactant
vapors to 3/8" wide x 1/4" deep annular ring
166. Forty-four radially oriented .028" diameter
holes 174 provide communication of enteriny vapors
to the barrel as shown.
Vent 104 utilizes a stainless screen mesh
or porous sintered Type 310 stainless steel ring
160 to pass fluid vapors and gases while filtering
solid resin particles and flakes. The screen
structure 160 is preferably 250 x 250 mesh, 1/2"
wide, spiraled 4 to 6 layers and seam welded at
each end. A stiff bristled stainless steel brush
154 is attached to screw 106 as shown. In
operation, the wire mesh filter cylinder 160 is
continually wiped clean by helically formed brush
154 which i5 attached to and empowered by screw
106.
The present invention further includes
the development of uniform unit site free energies
of formation in polycarbonate resins through the
facility of liquid phase reactions. For example
~isphenol A feed stocks, e.g., bisphenol A, may be
dissolved in a suitable solvent such as ethylene
chloride, methylene chloride, petrol, ligroin,
cyclohexaner methylcyclohexane benzene, toluene,
xylene, chloroform, carbontetrachloride,
trichloroethylene, dichloroethylene, methyl
acetate, and ethyl acetate and reacted wi~h
phosgene to produce polycarbonate. This reaction
may, for purposes of maintaining desired reaction
rates be developed in an aqueous atmosphere and
controlled by various additions of catalysts and
. .
26
pH modifiers as is conventional in the art.
Replacement of non-uniform free energy of
forma~ion end units and labile hydrogen may be
accomplished in the separated non-aqueous liquid
phase by addition of reactants selected from Table
1.
As an illustration of the liquid phase
reaction, a mi~ture including 10.8 lbs. bisphenol
At 4.7 lbs. sodium hydroxide, 22.4 lbs. methylene
chloride, and 62.1 lbs. distilled water is
agitated to a slurry suspension and slowly
phosgenated with about 4.9 lbs. phosgene. About
0.36 lbs. of 4~ solution of triethylamine is then
added and the slurry is agitated for about two
hours or until the desired molecular weight is
reached. Additional methylene chloride may be
added to reduce the viscosity of the organic phase
to facilitate washing with hydrochloric acid and
then with dionized water until neutral.
Phosgenation accelerated by the sodium
hydroxide basic aqueous atmosphere thus produces
polycarbonate in solution in methylene chloride
the polycarbonate having the general formula:
~rL~, ~~1~0~
c~3
n
This solution and any water present may
be dried by any suitable means or evaporated
completely to produce dry, clear, polycarbonate
film, and redissolved in dry methylene chloride.
:~a~ 6
27
The polycarbonate in solution in dry
methylene chloride or other suitable solvent,
e.y., a 15 to 60% by weight solution in methylene
chloride may be reacted with a compound from Table
1, e.g., 0~01 to 5~ of the compound by weight of
the polycarbonate resin, to produce stress
corrosion resistant polycarbonate as follows:
~o~l~~ + ~C~3)35iC
la ~ile
CEi3 CEI3 O
CE~3 CE~3
Gr~up ~P~oduct
The reaction can take place at 30F to 200F with
lS the compound o Table 1 in gaseous ~orm.
Removal of the hydrogen chloride or other
similar by-product may be by aqueous
neu~ralization washing followed by evaporative
redrying, or through evaporation of the methylene
2a chloride and venti~g of the HCl vapors during
melting of the resulting resin.
Phosgenation and modification of high
free energy unit sites may also be carried out
without the aid of water slurry atmospheres.
Bisphenol A dissolved in suitable dry solvents
such a dimethyl sulfoxide (CH3SOCH3), methylene
chloride (C~2C12), or ethylene dichloride
. ' ' ' . ~ ' ~
.
28
(c~H4cl2)r in suficiently dilute concentration to
control reaction rates and resulting viscosity
increases corresponding to molecular weight growth
upon phosgenation provides a suitable atmosphere
for reacting the newly polymerized polycarbonate
with a Table 1 reactant selected for specifically
desired resulting properties. The condensation
reaction may be terminated upon desired molecular
growth by addition of dry ammonia or hydrogen gas
followed by an end group reactant selected from
Table :L.
~ + Eo~ l ~o~ o~ll~o-lc ~
c~3 CJ13
For example:
~;3 ~_o~ * 2(C~3)3 SiCl ~
5CE~3-SI--O-I[~ Si-a~3 ~ 2EICl
~ 93 ` ~3 c~
The resulting polymer illustrated has uniform unit
site free energies of formation and increased
hydrophobicity at the end caps. Other properties
as discussed above may be achieved corresponding
to the reactant selected from Table 1.
Preparation of the polymer for
thermoplastic processing such as injection molding
or extrusion involves separation of the by-
products XCl and MaCl, and evaporative recovery of
39 ~?
29
the solvent. NaCl precipitate may be filtered or
centrifugally separated. It is preferred to
recover the HCl as a valuable by-product for sale.
One of the preferred mechanical
embodiments for polymerizing the polycarbonate
unit tc, the desired molecular weight i5
illustrated in FIGURE 4. A coniform Type 310
stainless steel helical spiral 200 is brazed to an
inside Type 310 stainless steel conical form 202
and to an outside Type 310 stainless steel conical
form 204~ The resulting tubular path 206 is a
coniform spiral starting at 210 and ending at
208. Attached to the inlet 210 is a suitable tube
connection 212 to pump 214, and attached to the
outlet is a suitable tube connection 216, to form
a circulation loop as shown involving the conical
spiral and pump 214.
Selected solvent, e.g., methyl chloride,
600 parts by weight, and bisphenol A 230 parts by
weight, in solution is pumped into the aforesaid
pump 214 circuit by pump 220 from reservoir 218.
Upon filling the pump 214 circuit, valves 222 and ~-
224 are closed. upon establishment of a steady
state rate of circulation of the bisphenol A in
solvent solution through the pump 214 circuit, 110
parts by weight of phosgene (COC12) is admitted
through valves 228 and 226 into the spiral portion
as shown. The reaction is carried out at 90F.
The buoyant upward force developed by the
reactant phosgene gas is somewhat countered by the
fluid motion forces of the bisphenol solvent
solution that flows countercurrent to the
phosgene's upward spiral. This insures high
exposure of the phosgene to the bisphenol A
solvent solution.
,:
-
.
,
Control of the reaction rate is offered
by the rate of phosgene addition, the rate of
circulation, and the reaction temperature.
Optimum reaction temperature is maintained by heat
exchange through pump circuit 240 which is
connected to a similar subspiral 242 constructed
as 206 but preferably circulated wi~h hot or cold
water.
Upon completion of the reaction and
development of the desired molecular weight, e.g.,
after six hours, the polymerization is terminated
by addition of pressurized hydrogen through valves
226 and 230. The inventory of solvent, and
polycarbonate with hydrogen end groups is now
transferred to reservoir 250. Replacement of
fluids drained to 250 is by an inert gas such as
argon, CO2, or the like, as supplied from pressure
cylinder 252 through valve 254 to accumulator 256.
Fluid stored in 250 may then be
centrifugally filtered to remove NaCl precipitate
and recirculated through a similar loop as
described above to replace the hydrogen end caps
with more desirable units as previously described
by reaction with chemicals sele~ted from Table 1,
e.g., usin~ trimethylchlorosilane at a temperature
of 90F.
Re~erring to FIGURE 5, the system starts
with unloading bisphenol A powder from railcar 330
through suitable line 332 to cyclone separator
324. 324 is empowered by a suitable high-volume
air pump 326. Dust is collected in filter 328.
Bulk storage o~ bisphenol A is provided in silo
322. Delivery through tube 332 to cyclone
separator 319 and drier-hopper 320 is empowered by -
pump 326 or a similar pump. Dessicant dryer 318
31
provides rapidly circulated -60F dew point, 250~F
air for an average dwell time of two hours to dry
powder in 320. Thoroughly dried, clean bisphenol
A is added through valve 321 to reservoir 308
where it is dissolved in a suitable solvent such
as dimethylsulfoxide added through valve 309. The
solution is passed through pump 306 and valve 304
to reactor 300. Reactor 300 is preferably
constructed of 300 series stainless steel
according to a design previously described with
respect to reactor 204. Circulation of the
dissolved bisphenol A and solvent is provided by
pump 356 through 3-way valves 353 and 354 to
spira:L path 302 within reactor 300. Hydrogen is
added through valve 340, pressure regulator 346
and valve 350 after being activated at 352.
Activation of hydrogen by heating and development
of increased energy states upon passage through an
electrical arc in 352 decreases the re~uired
temperature of the solution c:irculated through
300. Hydrogen is added until the total pressure
is about 250 psi. Variable clisplacement pump 356
is operated so as to produce high shear ~low of
the bisphenol A solvent solution through 300 as
hydrogen is added. Valve 348 is then closed and
carbon monoxide is admitted from 341 through
valves 348 and 350 to reactor 300. ~ydrogen is
released from the bisphenol A-hydrogen
intermediate as carbonate radicals are formed and
link bisphenol units into polycarbonate polymer.
Displaced hydrogen is collected in separator 334
as the solution in reactor 300 is continually
circulated until the desired molecular weight is
reached. Hydrogen collected in separator 334 is
then pumped by compressor 336; through filter 338,
32
valve 340, into storage as a compressed gas in
342. Upon reaching the desired molecular weight,
the polymer is end-capped by admitting a suitable
reactant, selected from Table 1 or Table 2 through
valve 372 from reservoir 374. Polycarbonate
polymer of the desired molecular weight in
solution is diverted through valve 353 to high
pressure pump 358. Reactor 386, of a construction
similar to 3D0, may be employed to heat the
polycarbonate-solvent solution under pressure to a
temperature well in excess of the atmospheric
pressure boiling point of the solvent. ~igh
pressure solutions of polycarbonate and solvent
are sprayed through suitable noz~les 360 on
extended surface conveyor 362. Chamber 370 is
operated at total pressure below the partial
pressure of the selected solvent and immediate
evaporation of the solvent is achieved. Solvent
vapors are condensed in conclenser 314~ Condensed
liquid solvent is stored in reservoir 312.
Polycarbonate which is deposited on conveyor 362
is displaced by rotary brooms 36~ and 366. Flakes
of polycarbonate are pelletized for handling,
shipping, and furtber use eficiencies by e~truder
392.
Bisphenol A resin in granular powder form
is handled by conventional chemical plant
equipment including a suitable silo 322, hopper
dryer 320~ dessicant type air drier 318 and mixer
3Q 308. The selected solvent is condensed and
handled by conventional chemical plant equipment,
includin~ a properly selected condenser tower 316,
tank 312, valve 309, and mixer 308.
33
Bisphenol A dissolved in the selected
solvent, e.g., methylene chloride, is circulated
throu~h conventional pump 306 and valve 304 to
reactor 300. Reactor 300 may be of any suitable
conventional design but is preferably built for
purposes of producing extremely high suface to
volume ratio flows of fluids and balancing high
buoyant forces of reactant gas additions with
viscuous forces of countercurrent flowing liquid
fluids. In large-scale production, it is believed
that a stainless steel, aluminum, or titanium
alloy tube coil surrounded with a suitable
temperature control bath would produce an
economical reaction path. For instance, a 600-
foot long, Type 316, one~inch diameter stainlesssteel tube housed within a 600-foot long 1-1/4"
diameter Type 316 stainless steel coaxial tube
coiled on a vertical axis cylindrical or conical
support and fitted at each end with conventional
Type 316 stainless steel coaxial bra2e fittings
enables close temperature control from fluid such
as water or silicone fluid circulated in the O.~.
tube. Circulation and conversion of more than
14,000 gallons of bisphenol A-solvent solution
(e.g., using methylene chloride as the solvent) to
14,000 gallons of polycarbonate-solPent solution
per day may be practically achieved. Thi~ enables
about 600,000 pou~ds of low-cost, improved stress
corrosion resistant polycarbonate per year to be
produced by the subject invention.
Polymerization of t~e polycarbonate to
desired molecular weights followed by end-capping
and spray drying in 370 may also be accomplished
at considerable savings compared to conventional
plant equipment. Pressurization by pump 358 of
` i
34
the heated polycarbonate-solvent solution to 20
atmospheres pressure enables extremely fine sprays
to be developed in airless spray nozzles 360.
Polymerized polycarbonate-solvent
solutions sprayed from 360 may be aimed away from,
parallel to, or at moving conveyor 362.
Preferably the belting of this conveyor is
compri.sed of fluorocarbon material manufactured as
a coarse plush, velvet-like rug, similar to some
artifi.cial turf materials. Extremely high surface
areas expose drying polycarbonate films that are
formecl on the surface of the fluorocarbon velvet
hairs.
Dried polycarbonate films are to a large
extent deposited on the outer tips of the conveyor
material. Upon reaching rotary broom 364, these
deposits are whisked off of the conveyor surfaces
and fall into the hopper around extruder screw
extension 390. Rotary broom 364 is operated at
considerably higher tangential velocities than the
conveyor surface. Another rotary broom 366
preferably operating at tangential velocities
above that of the conveyor provides pick-up and
cleaning of surfaces laid down by the action of
25 3640 The continuous conveyor is then routed as
shown, back to the spray line for facilitating the
separation of polycarbonate and solvent.
Extruder 392 consists of a vented barrel
393, a screw 390, a gear reduction unit 396, and a
drive 1notor 398. For the plant schematically
illustrated in FIGURE S, the components are sized
as shown in Table 3.
.
.
Table 3
Pilot Plant Example
Component Component
Number Name ~ Specificatlon
332 Transfer tube 2-1/2 dia~ Aluminum tuhing,
polybutylene sweeps
324 Cyclone separator 1,500 lb/hr Epoxy coat interior
surfaces
326-328 Bag filter assay 100 lb/hr Recyclable bag type
322 Storage silo 200,000 lb. Welded constructionr
epoxy lined
320 Dryer hopper 1,000 lb. Insulated for 360F
service
318 Dessicant 1,500 G2M -60F dew point;
250 air
324 Solvent condenser 80,000 lb/day Stainless steel
312 ~Iolding tank 1,500 gal. Stainless steel
308 Mixing tank 1,500 gal. 25HP totaly
enclosed motor
drive, stainless
steel
306 Transfer pump 200 G~M, Stainless wetted
10 PSIG conponents
304-309- Flow control 200 GPM, Stainless wetted
353-35~l- valves 3,000 PSIG oomponents solenoid
359 operated
336 Hydrogen 3,000 PSIG, 10 HP totaly
compressor 3 stage enclosed
342 Hydrogen storage 3,000 PSIG Stainless steel
341 Carbon monoxide 3,000 lb/day Incomplete
production & combusion of carbon
storage with oxygen
340-34~- Gas control 3,000 PSI Stainless steel
350 valves
372 1,000 GæM solenoid operated
- .
:,
, '
36
Table 3 (Continued)
346 Pressure regulator 0-3000 PSI Rated for CO, H2
1,000 GPM with downstream
check valve
334 Hydrogen separator 500 PSI~
tanks 1,000 GPM
300 Reactor 100 GPM, 500 Coaxial 1" bore and
PSI, 400F 1-1/2" bore stain-
less steel tubes;
600' long
388 Heat exchanger 100 GPM Coaxial 1" bore and
3,000 PSI, l- V2" ~ore stain-
500F less steel tubes,
300' long
358 Solution pump 100 GPM, Stainless wetted
3,000 PSI, oomponents, carbon
500F and ceramic seals
370 Hermetically 6' x 75' Stainless steel
sealed spray oonveyor with liner, insulated for
hopper totally en- 250F operation
closed 2û HP
variable speed
motor drive
393 Pelletizer 4" dia. 30/1; Var.iable speed
L~) vented drive
extruder,
10() En?
380 Fluid heater/ 50 GPM 5F to
cooler 500F silioone
oil; heater or
cooler, 50 PSI
Carbon monoxide is preferably produced at
the suite of use by excess carbon to oxygen
combustion in a fluidized bed of relatively pure
carbon. FIGURE 6 illusrates the preferred
embod.iment for carbon monoxide production. Carbon
del.ivered by any suitable means~ including railcar
450 is conveyed to storage silo 468 by suitable
transfer and grinding equipment including tubing
.: .
- ~,
~ ' ''
...
37
452" cyclone separator 454, hammer mill 460,
cycllone separator 4~2r filter bag 464, and blower
466~. Carbon particles ranging from dust to pea-
sized nodules stored in 468 are transferred to
drier hopper 47B and into fluidized column 496 by
screw 484. Hardened 4140 steel screw 482 is
prei-erably designed with a compression ratio of
about 3/1; a screw diameter of 3~l, and an L/D
rati.o of about 15 for purposes of compacting the
carbon particles moving through transfer barrel
4~2" to form a seal against the flow of carbon
monoxide produced in reactor 496.
Carbon monoxide is produced in reactor
496 by the combustion of carbon with oxygen that
may be supplied from any economical source. The
suriace reaction starts on porous silicon carbide
cone 499 through with oxygen passes and combines
with carbon supplied from the fluidized bed to
form carbon monoxide. Cone 499 is housed in
reaction box 498, detailed more fully in FIGUR~ 7.
1-1/2 2 ~ 2C -~ CO + CO2
Start-up requires electrical resistance
heating cone 4~9 to 1,500F or more. Cone 499 is
m~intained between 1,800F and 0F by control of
the rate of oxygen addition through regulation o~
the oxygen pressure by regulator 500. Little
carbon dioxide is produced however, any carbon
dioxide present on the surface of 499 is reacted
with orange-white hot carbon in 496 to produce
carbon monoxide.
C2 + C--~ 2 CO
3~
The carbon monoxide production is
exothermic and once started, continues at rates
dependent upon the oxygen pressure. Heat produced
by the reaction is carried upward within insulated
reactor 496 ~o preheat carbon working down to the
reaction cone. Reactor 496 has a bore of 12", a
height of 15', and is lined with a .250 wall Type
310 stainless steel tube. Carbon monoxide at
about 2~0F is filtered through sintered stainless
steel shot filter 490 and is supplied at about S00
psi to storage 341 for polycarbonate manufacture.
As shown in FIGURE 7, stainless steel
tube 496 is preferably welded to adapter flange
516. Adapter flange 516 is a 1" thick Type 310
stainless plate and provides transfer of the
column load of 496 to insulative bricks 521. 516
also supports Type 304 stainless steel cup 523
which is sealed against 516 by a copper gasket and
12 equally spaced 1/2 - 13T]PI screws 525. Cup 523
provides support for porcelain insulator 530.
Insulator 530 electrically isolates heat resisting
compression spring 528 that thrysts porcelain
adapter cup 526 and silicon carbide resistance
element 512 upward into tapered hole 510 of cone
499 to assure good electrical contact through all
temperatures of operation. Cooling coil 532
provides circulation of suitable cooling fluids
such as silicone oil to limit the temperature of
the cylindrical walls of cup 523 to about 400F.
Considerable cooling is provided by the incoming
oxygen, however, on start-up and shut-down
conditions, 5~3 requires additional heat
dissipation through 532.
39
Start-up is provided by establishing a
low positive pressure of oxygen through 524, and
applying alternating 25V, 300A current through the
circuit 544, 542, 522, 512, 499, 516 and 546.
Resistor element 512 presents the most thermally
insulated, highest resistance portion of the
circuit and reaches 2400-2800F and heats 499 to
at least 1500F by conduction and radiation.
After czrbon monoxide production is detected at
486, electrical resistance heating may be
stopped. Gas tight sealing 499 to 516 is provided
by conductive graphite electrode tar 518.
Shut-down is simply accomplished by
stopping the flow of oxygen through 524. Ash
forming impurities in the carbon selected for
carbon monoxide production eventually build a slag
over 518 and in long production runs may be
removed by hot tapping through removable plug 552.
Rebuilding is usually required by erosion
of 499 and destructive scaling of the lower
portion of 496, and involves torch cutting 496 at
a satisfactory height and at 516; removal of slag
and 499: replacement of 512, 518, 499 and the
. removed length of 496. Heliarc weld sealing the
replacement length of 496, restacking and banding
insulative bricks 520, completes the short
rebuilding process. More complete rebuilding to
replace cup assembly 523 involves removal of
insulative bricks 520 and 521; cutting 596 at a
3Q satisfactory height; disconnecting 524, 534, 542
and 544; and change-out o~ pieces needing
replacement.
Carbon selected for carbon monoxide
production may be of any suitable description
ranging ~rom low ash coal products to petroleum
sourced carbon black. The following examples
assume that the carbon and oxygen purity
specifications allow direct carbon monoxide
production without additional purification except
for non-volatile ash-slag disposal.
Unless otherwise designated, all parts
and percentages are by weight.
Examp:Le A
Extruder Converted Resin:
Polycarbonate resin such as that
available from Mobay Chemical Corporation
designated by the brand name "Merlon~' or from the
General Electric Company designated "Lexa~' is
processed through an extruder modified to include
vapor input ports above the melt zone. ~ach vapor
input æone is provided with a separate pressure
regulator and inward flow of reactant vapor is
adjusted to produce a completely end-capped
polymer. Vaporous reaction products are vented
throuc~h an evacuated exit port between the entry
ports~.
In a 3-1/2" vertical 30/1 L/D, extruder,
the upper inport port is about 14" from the screw
top (about 2" below the feed section of the
scr~w); the exhaust vent is about 26" below th
screw top; and the lower inport port is about 56"
below the screw top. The extruder is run at 90
rpm and produces a throughput of about 620 pounds
of converted polycarbonate per hour, at a flange
pressure of about 3,100 psi. The upper
temperature control zone of the extruder
corresponding to the feed section of the screw is
maintained at 250F. The first vent zone
corresponding to the section between the feed
~7
~',
3~
sect.ion and the exhaust vent is maintained at
350~E. The second vent zone, corresponding to the
sect;on between the exhaust vent and the lower
input port is maintained at 450F. The remaining
zones below the lower input port are maintained at
500 to 520~F. A pelletizing die assembly that
incorporates filter screens and a final vent is
maintained at 500F.
An end-capping reagent such as trimethyl
chlorosilane [(CH3)3 SiCl] is added at the upper
and :Lower input vents at a total rate of about 25
to 30 pounds per hour on start-up. The rate of
addition is then gradually reduced over a period
of about one hour until a water-clear extrudate
having completely converted end-caps is
produced~ Completeness of conversion is
determined by the ability of a 3-mil film cast
from a methylene chloride solution of the produced
polymer to withstand 30 minutes contact at 300~F
with the re5idue of a 15% ammonium laurylsulfate-
water solution without stress corroding. The
minimum addition rate of trimethyl chlorosilane
depends upon the rate of non-reactive escape and
upon the polycarbonate feedstock molecular weight
and ranges between about 5 pounds per hour and 12
pounds per hour.
le B
Solvent Atmosphere Converted Resin:
Polycarbonate pellets such as resin
designated "Lexan~' or "Merlon~' by the General
Electric and Mobay companies are dissolved in
methylene chloride solven~. About 100 parts of
resin are dissolved in about 700 parts of solvent
using a Neptune E. Blender. The solution is
.. ,~
3~j
42
maintained at about 50F in a coaxial tube reactor
described above. About 5 parts of trimethyl
chlorosilane [(CH3)3 SiCl] are gradually
introduced to the solution circulated in the
reactor. Circulation through the reactor is
maintained at an average velocity of about 40l per
second with a stainless steel centrifugal pump for
about 30 minutes. The converted polymer in
solvent solution is transferred to a second
reactor and pressurized to 2,000 psi with a
positive displacement Pesco A-200~pump. The
temperature of the polymer-solvent solution in the
second reactor is gradually increased by about
250F by countercurrent heat exchange from heated
silicone fluid. The heated solution is then
pressure sprayed through four carbide tipped spray
nozzles aimed so the most divergent portion of the
fan is to a 2~ deep, 4' wide, 10' long tray of
water. Most of the methylene chloride solvent
evaporates before the spray droplets fall on the
water. The sprayed flakes of converted
polycarbonate are washed on a stainless screen
with additional water, dried by a Conair D-2B0
Drier and extruded by a 2" extruder to produce
2~ pellets.
Example C
Bisphenol A resin is dried by passing
-60~F dew point, 250F air through a hopper
containing the resin for three hours. 230 parts
dried bisphenol A resin is mixed in 1,000 parts
dimethyl sulfoxide and entered into a coaxial tube
reactor by a Pesco A-100 positive displacement
pump and circulated at 40' per second average
velocity. Additional solvent is added to
~ .
43
completely fill the reactor volume. The solution
is pressurized to lOG psi by heating to about
220F in response to circulation o~ heated
silicone fluid through the annular space between
the outer tube and the inner tube of the
reactor. ~Iydrogen is added until the total
pressure is about 250 psi. Thirty p~rts carbon
monoxide produced by reacting carbon with oxygen
in a fluidized column are added to the circulating
solution of bisphenol A and dimethyl sulfoxide at
about 300 psi. The temperature of the circulating
solution is reduced by heat exchange to 200F
silicone 1uid to about 210F durin~ CO addition
to maintain 300 psi overall pressure. Circulation
is continued for about 15 minutes or until the
desired molecular weight has been reached. The
molecular weight is then fixed and the end groups
capped by adding about 25 p~rts Rhodamine 123.
The temperature is then increased by circulation
of 3009F silicone fluid through the annular space
between the coaxial tubes of the reactor and the
pressure is increased by the restricted thermal
expansion of the solvent-solute solution to about
2,000 psi. Polycarbonate flakes are produced by
- 25 spraying the 2,000 psi solution over a bath of
70~? isopropanol. Solvent escapes from the
atomized spray as solidified polycarbonate falls
into the isopropanol to be collected.
Example D
230 units of dry bisphenol A are
dissolved in 1000 units of dry methanol at 80F.
The solution is pumped into a Type 316 stainless
steel coaxial tube re~ctor by a Pesco A-100 pump
.~.,~
4~
and circulated at about 40 feet per second. The
solution is heated and pressurized to about 255F,
400 psi by circulation of heated silicone fluids
in the annular space between the inner tube and
the outer tube. Three parts hydrogen are passed
through an electrical arc activator and added to
the circulating solution. 35 parts carbon
monoxide at about 250F, 500 psi are added. The
solution is slowly cooled to 80CF and added to
1000 units methylene chloride. The double solvent
solution is circulated with samples taken every
five minutes until a suitable molecular weight is
reached. The molecular weight growth is
terminated and end caps are developed by adding
1.5 parts 3-amino chloroacridine. The
polycarbonate rich methylene chloride solution is
centrifugally separated from the methanol solution
and polycarbonate is precipitated by any suitable
means or deposited as a clear varnish upon
evaporation of the methylene chloride solvent.
EXAMPLE E
100 units of dry polycarbonate are
dissolved in 1200 units methylene chloride. 750
units dry methanol are added and a portion of the
solution is transferred ~o the inner tube of a
1000 ml stainless steel coaxial tube reactor
packed with wheat grain size zinc shot. This
portion is designated Sample "A". Silicone oil is
circulated between the outer tube and inner tube
for temperature control. The solution in the
inner tube is circulated through the zinc shot
with a hermetically sealed positive displacement
pump. The circulating solution is brought to
~5
250F and 15 units of 1,1,2-trichloro-1,2,2-
trifluoroethane are added. Circulation is
continued for 10 minutes at 250F and then cooled
to 70F.
Polycarbonate from samples of the reacted
solution (Sample A) and the unreacted solution
(Sample B) are cast by evaporation. Sample A is
found to resist stress corrosion from 15~ ammonium
lauryl sulfate solution residues at 300F while
Sample B fails to resist stress corrosion under
the same test.
BXAMPLE F
_
100 parts of Lexan polycarbonate are
dissolved in 700 parts methylene chloride at
70F. A sample of solution is withdrawn and
marked Sample A. 5 parts l-naphthoyl chloride are
added to the remaining solution and the solution
is stirred for 30 minutes. A second sample is
withdrawn and marked Sample B. Films are cast
from Samples A and B. Comparison of accelerated
ultraviolet testing of samples A and B show marked
differences with Sample B showing reduced
yellowing and embrittlement due to ultraviolet
exposure. A and B comparisons of stress corrosion
due to exposure to the residues of a 15% ammonium
lauryl sulfate-water solution at 300F show
reduced effect upon Sample B.
Unless otherwise indicated all parts and
units are by weight. Parts and units are used
interchangeably. The composition can comprise,
consist essentially of or consist of the materials
set forth. The process can comprisP, consist
essentially of or consist of the steps set forth.
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