CA1166396A - Polycarbonates stabilized by halohydrocarbon, halocarbon or silane groups - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A carbonate resin having the phenolic hydrogen end atoms replaced by stress corrodant preventive groups which are halohydrocaroon groups, halocarbon groups or a silane groups or the hydrogen end atoms replaced by a capping group having fluorescent properties to provide ultraviolet light and stress corrosive protection.

Description

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.

'' .
~`

{}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 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-.

. ~ :

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~

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, 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.

.. ; -. . , . :
. ~ .
; ~
.

.

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 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 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 :

,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.

-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~

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 - . . . ~ . .
.

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.

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.

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 . .

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 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 . ' ' ' . ~ ' ~

.

(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 ~?

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 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, 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.

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 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 - .
:, , ' 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 .: .
- ~, ~ ' '' ...

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.

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 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 ~ .

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.

' '' . ~ ~
' ', ' .

Claims (40)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A polycarbonate resin having the phenolic hydrogen end atoms replaced by (1) stress corrodant preventive groups which are halohydrocarbon groups, halocarbon groups or silane groups where the silane group is a halosilane, a haloalkylsilane, a hydro-siliconhalide, an amino lower alkyl lower alkoxy silane, a glycidyloxy lower alkyl lower alkoxy silane, a mercapto lower alkyl lower alkoxy silane, an acryl or methacryl oxy lower alkyl lower alkoxy silane or (2) a capping group having fluorescent properties to provide ultraviolet light and stress corrosion protection or (3) a combination of (1) and (2).

2. A polycarbonate resin having the phenolic hydrogen end atoms replaced by stress corrodant pre-ventive groups which are halohydrocarbon groups, halo-carbon groups or silane groups where the silane group is a halosilane, a haloalkylsilane, a hydrosiliconhalide, an amino lower alkyl lower alkoxy silane, a glycidyloxy lower alkyl lower alkoxy silane, a mercapto lower alkyl lower alkoxy silane, an acryl or methacryl oxy lower alkyl lower alkoxy silane.

3. A polycarbonate resin according to Claim 2, wherein the stress corrodant preventive group is a halo-hydrocarbon group or a halocarbon group and at least a portion of the halogen is fluorine.

4. A polycarbonate resin according to Claim 2, wherein the stress corrodant preventive group is a silane and is a halosilane, a haloalkylsilane, a hydro-siliconhalide, an amino lower alkyl lower alkoxy silane, a glycidoxy lower alkyl lower alkoxy silane, a mercapto lower alkyl lower alkoxy silane, an acryl or methacryl oxy lower alkyl lower alkoxy silane.

5. A polycarbonate resin according to Claim 4 having the formula:

where A is cycloalkylene, alkylidene, cycloalkylidene, or sulfone, R1 is alkylene, alkyleneoxyalkylene, poly-(alkyleneoxyalkylene) or arylene, R is alkyl, cycloalkyl, aryl, aralkyl, alkoxy or halogen of atomic weight 9 to 80, n is an integer from 0 to 4, n1 is an integer of at least one, n2 is 0 or an integer of at least one, the total of n1 and n2 is such as to define the molecular weight of the polymer with the proviso that when R1 is arylene then n1 can be 0 and X is the stress corrodant preventive group.

6. A polycarbonate resin according to Claim 5 includes bisphenol A units as a part of the units in n1.

7. A polycarbonate resin according to Claim 6, wherein n2 is 0.

8. A polycarbonate resin according to Claim 7, wherein all the nl units are bisphenol A units.

9. A polycarbonate resin according to Claim 7, wherein a portion or the n1 units are bisphenol Cy units.

10. A polymer according to Claim 7, wherein X
is where R1, R2 and R3 are all lower alkyl.

11. A polymer according to Claim 10, wherein R1, R2 and R3 are all methyl.

12. A process for preparing a polycarbonate resin having the phenolic hydrogen end atoms replaced by either (1) stress corrodant preventive groups which halohydrocarbon groups, halocarbon groups or silane groups where the silane group is a lower alkyl silane, a halosilane, a haloalkylsilane, a hydrosiliconhalide, an amino lower alkyl lower alkoxy silane, an acryl or methacryl oxy lower alkyl lower alkoxy silane or (2) a capping group having fluorescent properties to provide ultraviolet light and stress corrosion protection or (3) a combination of (1) and (2) which comprises (a) extruding a polycarbonate resin having phenolic hydrogen end atoms and adding a silane as defined above to the resin in the extruder to form the silane containing stress corrodant preventive groups in place of the hydrogen end atoms, or (b) adding a silane as defined above to a solution of polycarbonate resin having phenolic hydrogen end atoms and allowing the silane to react with the polycarbonate resin in solution until there are formed silane containing stress corrodant preven-tive groups in place of the hydrogen atoms, or (c) extruding a polycarbonate resin having phenolic hydrogen end atoms and adding a fluorine containing halohydrocarbon or halocarbon to the resin in the extruder to form the fluorine containing stress corrodant preventive groups in place of the hydro-gen end groups, or (d) adding a fluorine containing halohydrocarbon or halocarbon to a solution of a polycarbonate resin having phenolic hydrogen atoms and allowing the fluorine containing compound to react with the polycarbonate resin in solution until there are formed fluorine containing stress corrodant preven-tive groups in place of the hydrogen end atoms, (e) extruding a polycarbonate resin having phenolic hydrogen end atoms and adding a silane as defined previously, halohydrocarbon or halocarbon to the resin in the extruder to form stress corrodant preventive groups in place of hydrogen atoms, or (f) heating a solution of a polycarbonate resin having phenolic hydrogen end atoms, said solution also containing a silane as defined previously, halo-hydrocarbon or halocarbon, to a temperature suf-ficient to react said silane, halohydrocarbon or halocarbon with said resin and form stress corro-dant preventive silane, halohydrocarbon or halo-carbon end groups in place of the hydrogen end atoms.

13. A process of preparing the polycarbonate resin comprising extruding a polycarbonate resin having phenolic hydrogen end atoms and adding the silane to the resin in the extruder to form the silane containing stress corrodant preventive groups in place of the hydro-gen end atoms.

14. A process according to Claim 13, wherein the silane is added in gaseous form.

15. A process according to Claim 13, wherein the silane is trimethylchlorosilane.

16. A process of preparing the polycarbonate resin comprising adding a silane to a solution of a polycarbonate resin having phenolic hydrogen end atoms and allowing the silane to react with the polycarbonate resin in solution until there are formed silane con-taining stress corrodant preventive groups in place of the hydrogen atoms.

17. A process according to Claim 16, wherein the silane is trimethylchlorosilane.

18. A process according to Claim 17, wherein the solvent is methylene chloride or dimethyl sulfoxide.

19. A process according to Claim 15, wherein the silane reaction is accelerated by heating the poly-carbonate solution.

20. A process of preparing the polycarbonate resin comprising extruding a polycarbonate resin having phenolic hydrogen end atoms and adding the fluorine con-taining halohydrocarbon or halocarbon to the resin in the extruder to form the fluorine containing stress corrodant preventive groups in place of the hydrogen end groups.

21. A process according to Claim 20, wherein the fluorine containing compound is added in gaseous form.

22. A process of preparing the polycarbonate resin comprising adding a fluorine containing halohydro-carbon or halocarbon to a solution of a polycarbonate resin having phenolic hydrogen atoms and allowing the fluorine containing compound to react with the poly-carbonate resin in solution until there are formed fluorine containing stress corrodant preventive groups in place of the hydrogen end atoms.

23. A process according to Claim 22 including heating the solution.

24. A process according to Claim 23, wherein the heating is to 300°F.

25. A process of preparing the polycarbonate resin comprising extruding a polycarbonate resin having phenolic hydrogen end atoms and adding a silane, halo-hydrocarbon or halocarbon to the resin in the extruder to form the stress corrodant preventive groups in place of hydrogen end atoms.

26. A process according to Claim 25, wherein the silane, halohydrocarbon or halocarbon is added in gaseous form.

27. A process of preparing the polycarbonate resin comprising heating a solution of a polycarbonate resin having phenolic hydrogen end atoms, said solution also containing a silane, halohydrocarbon or halocarbon, to a temperature sufficient to react said silane, halo-hydrocarbon or halocarbon with said resin and form stress corrodant preventive silane, halohydrocarbon or halocarbon end groups in place of the hydrogen end atoms.

28. A proces.s according to Claim 27, wherein the heating is to at least 300°F.

29. A polycarbonate resin according to Claim 2, wherein the stress corrodant preventive group is a halo-hydrocarbon group or a halocarbon group.

30. A polycarbonate resin according to Claim 29, wherein the halohydrocarbon or halocarbon group contains chlorine.

31. A polycarbonate resin having the phenolic hydrogen end atoms replaced by a capping group having fluorescent properties to provide ultraviolet light and stress corrosion protection.

32. A polycarbonate resin according to Claim 30, wherein the capping group contains a 6,13-dichloro-3,10-diphenodioxazine unit or a benzoxazole unit.

33. A polycarbonate resin according to Claim 30, wherein the capping unit is formed by reacting the polycarbonate with trichlorodiphenyltriphenodioxazine, chlorobenzoxazole or chlorobenzoxazole silane.

34. A polycarbonate according to Claim 33, wherein the capping unit is formed by reacting the poly-carbonate with trichlorodiphenyltriphenodioxazine.

35. A polycarbonate according to Claim 33, wherein the capping unit is formed by reacting the poly-carbonate with chlorobenzoxazole.

36. A polycarbonate according to Claim 31 containinq capping units of both (1) a compound impart-ing fluorescent properties to the polycarbonate and (2) a halohydrocarbon, a halocarbon or a silane.

37. A polycarbonate according to Claim 36, wherein (2) is a silane.

38. A polycarbonate according to Claim 37, wherein the capping units are formed by reacting a poly-carbonate with both (1) trichlorodiphenyltriphenodi-oxazine or chlorobenzoxazole and (2) a silane.

39. A polycarbonate according to Claim 36, wherein the silane is trimethylchlorosilane.

40. A polycarbonate resin according to Claim 1 or 2, wherein the halohydrocarbon or halocarbon group contains chlorine and is the residue from removing one of the atoms attached to the carbon atom of methylene chloride, chloroform or carbon tetrachloride.