Note: Descriptions are shown in the official language in which they were submitted.
~ ~7~i3~3 31.
PROCESS FOR I~E ~ANUFACrURE OF EIASTOMERS
IN PAR~ICU~TE FORM
~ACKGRCUND OF l~E INVE~TICN
,
1. Field of the Invention
The present invention relates to a process for manufacturing many
of the common ccmmercial elastomers. The elastomers that can be
manufactured by this process include, but are not limited to,
ethylene-propylene-die~e rubber, styrene-butadiene rubber,
styrene-butadiene the~plastic rubber, cis-polybutadiene ru~berl butyl
rukker and cis-polyisoprene rubber. The process applies to both batch
a~d continuous manufacturing processes. Furtherl the process is used
with elastomers prcduced in solution or in particulate form. A
modification of the process makes it applicable for the manufacture very
low molecular weight liquid polymers.
2 scription of the Prior Art.
. .
The manufacture of elastomers in anhydrous solvents or diluents
consists of a polymerization section, a catalyst rem~val section, an
elastom~r particwlation section, a diluent and monomer recycle
purificaticn section and an elastomer packaging and shipping section.
See, for exa~ple for unrelated types of processesJ U.S. Patent
3,',23,929, entitled "Olefin Poly~rization Process", issued Aug. 11,
1~70, to J.L. Paige et al; U.S. Patent 2,565,960, entitled "Preparation
of an Improved ~ydrocarbon Resin", issued Aug. 28, 1951, to J.D. Garber
et al; U.S. Patent 4,068,053, entitled "Me~hod of Removing Water From
Li/~d Olefin In The Polymerization of Olefins", issued ~an. 10, 1978,
to C.D. Miserlis et al.
E~istLng elastcmer processes do not normally use fine molecular
sieve removal steps prior to the xeactor in the poly~erization section,
although ~he use of m~lecular sieves is known in the art. Various
purification steps for other processes unrelated to the elastomer
process of this invention ~re shown in the prior art. See, for example,
U.S. Patent 2,900,430, entitled "Prccess For the Removal of straight
Chain A oe tylene Frcm Isoprene", issued ~ug. 18, 1959, to A.M. Henke et
: t i~,
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al; Uni-ted S-tates Paten-t 2,~06,795, entitled "Recovery and
Utilization of Normally Gaseous Olefins", is.sued September
29, 1959, to W. P. Bullard, et al; United States Patent
3,209,050, entitled "Purification of Diolefins", issued
September 28, 1965, to E. S. Hanson; Uni.ted States Patent
3,326,999, entitled "P~lrification of Olefins", issued June
20, 1967, to ~. D. Rhodes, Jr.; United States Patent 3,352,840,
entitled "Removal of Deposits From Polymerization Reactors",
issued November 14, 1967, to C. M. Oktay; Unlted S-tates Patent
3,514,426, entitled "Process For Suppressing Molecular Jump",
issued May 26, 1970, to R. E. Barrett; United States Patent
3,635,931, entitled "Polyisoprene From Amylenes Via-Amylene
Isomerization Oxidative Dehydrogenation Extractive Distilla-
tion and Polymerization of Low-Concentration Isoprene", issued
January 18, 1972, to J. W. Davison; United States Patent
4,016,349, entitled "Process for Removing Vanadium Residues
From Polymer Solutions", issued April 5, 1977, to J. M. McKenna;
United States Patent 4,182,801, entitled "Method of Drying
Liquid Olefin Monomer Feed in a Molecular Sieve Dryer in the
Polymerization of Olefins From Liquid Olefin Monomer", issued
January 8, 1980, to ~iserlis, et al; United States Patent
4,235,983, entitled "Purification o:E Olefin Recycle to Poly-
merization"~ issued November 25, 1980, to Steigelmann, et al;
and Paige. ~.
Existing processes utilize an expensive hot water
injection particulation section which also increases the cost
of diluent and monomer recycle purification and adds a water
waste disposal problem.
'rhe use of flassling or settling zones Eor recovery
of materials in processes unrelated to the elastomer process : .
~! - 2
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of this inven~ion is also known in the prior art. See, for
example, United Sta~es Patent 2,921,053, entitled "Recovery of
Olefins From Hydrocarbon Mixtures", issued January 12, 1960 to
R. F. Dye; and McKenna.
Further, some patents show the use of additives or
product separation. See, for example, U. S. Patent 4,098,980 to
Markle, et al. As set out infra, the reactants and other
materials are carefully specified, and no additional additives,
or place from which they could be in~roduced, are shown in the
specification, and the process operates as shown and without
any such additives.
SUMMARY OF THE PRESENT INVENTION
The present invention provides apparatus for the
manufacture of rubber from a variety of feeds, comprising:
feed means for selecting a subset o the variety of
feeds and conveying said suhset of the feeds;
reaction means for receiving said subset from the
feed means and for reacting the feeds to produce a product
mixture;
- 20 product separation means for receiving said product
mixture and separating said product from the other componen~s
of said mix~ure by densit~ separation.
The present invention also provides a process for the
manufacture of rubber, comprising:
A. providing feed s~ock;
B. reacting the feed stock to produce an effluent of
a rubber product and other components;
C. separatiny the rubber product and other components
by settling;
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~ 3~ 70677 ~
D. evaporating the effluent of Step C to separate the
rubber produc~ from o~her components.
By employing the apparatus and/or proces~ o~ the
present lnvention, many rubbers can be produced by the same
equipment. The rubbers lnclude, fnr example, styrene-butadlene
rubber, ethylene oxide-epichlorohyclrin rubber, styrene-
butadiene ~hermoplastic rubber, cis-polybutadlene, cis-
polyisoprene, ethylene propylene-diene rubber, thermoplastic
ethylene-propylene rubber and butyl rubber.
lQ The present invention eliminates several costly
portions of the rubber processes of the prior art. The process
of the presen~ invention may involve passing the reactan~s
through fine molecular sieves to remove impurities prior to the
reaction stage and then reacting same.
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Af-ter the reaction sta~e ancl prior -to separating
the elastomer and diluent or solvent, it is necessa:ry to re-
duce catalyst and monomer concentration in the reactor ef-
fluent. With a slurry system, this is accomplished as part
of this invention by flowi.ng the reactor effluent to near
the middle of a column and flowing fresh diluent from the
bottom of the column. The particles are allowed -to settle
in the fresh diluent and discharge with the fresh diluent to
: the fl.ash separation ~mi-ts discussed supra. The liquid from
the reactor effluent flows out of the top of the column.
The present invention also eliminates the costly
water injection particulation step and disengages the solvent
or diluent directly from dissolved or particulate elastomer .
by flashing the solvent or diluent as vapor and separating
particulate elastomer in a flash drum or cyclone.
The elastomer is then finish dried in a fluid bed
dryer, packaged and shipped.
The vapor is compressed, condensed to liquid, puri-
fied as needed and recycled.
Alternately, ln the case of an elastomer in solu-
tion, catalyst reduction is accomplished by contacting the
solution with catalyst complexing agents which form high
: density insoluble complexes that are separated by decanta-
tion or centrifugation. The clarified solution is then sep-
arated into particulate elastomer and solvent vapor by flash-
ing in a heated pipe and separated in a flask tank or cyclone
as above.
BRIEF DESCRIPTION OF THE DRAWINGS
. . . ~
Fox a further understanding of the nature and ob-
jects of the present inven-tion, reference should be had to
.
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the :Eollowing detailed description, taken in conjunction
with the accompanying drawlngs, in which like parts are
given like reference numerals, and wherein:
Figure 1 is a functional block diagram of the elastomer
process of the preferred embodiment of the present invention,
Figure 2 is a schematic of the elastomer process of
the preferred embodiment of the present invention; and
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FicJure 3 ls a sch~matic of an alternate confiyuration
of the preferred embodiment o~ the present Lnvention showing
the process opera-ting on an elastomer in solution with a
catalyst removal ~rom solution step; and
Fi~ure 4 is a schematic of an alternate configuration
of the preferred embodiment of the present invention for liquid
elastomer showing the process decanting of liquid elastomer
from diluent and catalyst, then stripping the remaining solvent
or diluent from the liquid elastomers.
~ CRIPTION OF THE PR~FERRED EMBODI~ENT
As shown in Figure 1, one preferred embodiment of the
process of the present invention includes eight major steps,
feed preparation and metering 10, reaction ~0, product
purification 30, product separation 40, compression 50, diluent
purification 60, product drying 70 and product finishing 80.
- Feed Preparation and Metering -
Referring to Figure 2r in feed preparation step 10,
there are multlple streams. The diluent or solvent stream 101 --
flows sequentially through a set of purification columns 103,
105. Column 103 is packed with 3A molecular sieves which reduce
`. moisture in the stream by adsorption to less than one part per
million. Column 105 is packed with 13X molecular sieves which
reduce oxygenated and acetylenic compounds in the stream by
; adsorption to less than one part per million. Compounds that
may be adsorbed by the 13~ sieves include any traces o~
alcohol, ketones, carbon monoxide, carbon dioxide, oxygen and
: acetylenic compounds. Reduction of these materials in the
stream to near zero reduces catalyst requirements and,
possibly, by-products which in turn improves post-reactor
purification systems.
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~.2~3~1 70677~4
The adsorption columns 103, 105 are constructed of
low carhon steel to pressure and temperature specifications in
the range of lO0 to 500 psig and 300 to 600F. The columns 103,
105 are regenerated by a heat purging cycle, not shown, and are
sized for optimum economic operation.
The preferred diluent 101 for most systems which
produce rubber in particulate form in the reactor is isobutane
except for (i) ethylene-propylene-dielle rubber, where the
preferred diluent is propylene, one of
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~.2'7~31~
the monomers, and ~ii) butyl rub~r where the preferred diluent is
methyl chloride. Also, when cis-polybutadiene or cis-polyisoprene is
produced as a solution in the r~actor, the preferred solvent is
cis-butene-2. Alternative diluents are propane, n~butane, and pentanes.
Also, depending on the catalyst, propylene, butene-l, trans-butene-2 and
pentene may be used as diluents.
The flow through columns 103, 105 to the reactor system 106 is
controlled by a flow control loop 104 downstream from the column 105.
Monomer streams 107, 109 are also introduced to the reactor 106 for
reaction step 20. These streams 107, 109 are as follows for the several
products of this process:
Stream 107 Stream 109
Styrene-Butadiene Rubber Butadiene Styrene
St~rene-Butadiene Block Rukber Butadiene Styrene
Ethylene~PrGpylene-Diene Rubber Ethylene Ethylidene
Nor~ornene
Cis-Polybutadiene Rubber Butadiene nil
Cis-P~lyisoprene Rubber Isoprene nil
Epichlorhydrin Rukber Epichlorohydrin Ethylene
oxide
Butyl Rubber Isobutylene Isoprene
Stream 107 is purified in columns 111, 113 connected in series, and
stream lO9 is purified in columns 115, 117 connected in series. Columns
111, 115 are packed with 3A molecular sieves which reduce moisture in
these monomers by adsorption to less than one part per million. Columns
113, 117 are packed with 13X molecular sieves which reduce oxygenated
and acetylenic ocmpounds in these strean~s to less than one part per
million~
The four ads~rption columns 113, 115, 117, 119 are made of low
carbon steel to pressure and temperature specification in the range of
100 to S00 psig and 300 to 600F depending on the products to be
manufactured at the plant. The columns 113, 115, 117, 119 are
regenerated by a heat purge ~ycle, not shown, and are sized for optimum
econo~ic operation.
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m e flow through columns 113, 115 is controlled by a flow control
lcop 119 that is reset or cascaded from an on-line process analyzer 121,
by control loop 123. Analyzer 121 receives samples rom the vapor line
125 between reactor 127 and vapor condenser 129. m is system is
satisfactory for volatile monomers such as butadiene, isoprene, ethylene
and propylene. Alternatively, stream 107 feed oontrol could be reset or
cascaded ~y oDntrol loop 131 from the on-line analyzer 133 which is
shown resetting or cascading the flow control loop 135 for stream 109
through columns 115, 117 to the reactor system 106.
~ tream 137 is a hydroge~ stream. This stream is dried in column
139. Column 139 is packed with 3A molecular sieve which reduce moisture
in the hydrcgen by adsorption to less than ~ne part per million.
Hydrogen flow through column 139 is controlled by a flow control loop
141. The flow rate is set on the basis of product molecular weight.
Alternatively, the on-line process analyzer 121 may be used to
reset the flow control based on hydrogen in the reactor vapor 125.
Hcwever, that relationship is a function of product molecular weight.
Stream 143 is the aluminum alkyl catalyst component that is us~d
for ethylene-propylene-diene rubber, cis-polybutadiene rubber,
ci~-polyisoprene rub~er, epichlorohydrin rubber and but~l rubber.
Me~erin~ pump 145 is shcwn in Fig. 2 controlling the flow of this
~ onent to either reac*or 127 or reactor 147 depending on the product.
Alternatively, a separate pump may be used for each reactor. A
stainless steel diaphr~m metering pump is normally used for this
selvioe.
; Stream 149 is a mcdifier or muxture of mndifiers to optLmize
catalyst effectiveness by m~derating the catalyst component reactions or
by preventing post reactions of the polymer. Mbter~lg pump 151 controls
the flow of stream 149 to reactor 127 or 147 depending on the prcduct.
Alternatively, indiviclual pumps may bc used for each ~odifier and/or for
each reactor. A stainless steel diaphrc~m metering pump is normally used
for this service.
~ ~6-
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Stream 153 is the key oatalyc;t component, and flow is controlled by
the stainless steel diaphram metering p~unp 155. I~s component varies
depending on the product and n~ay be a cobalt salt, a titarlium salt, a
vanadium salt or butyl lithium. A process using butyl lithium normally
does not require aluminum alkyl components or mcdifiers.
Streams 101, 107, lO9, 137, 143, 149 are shown in Fig. 2 being
mixed in-line as stream 157 or stream 159 to the reactors 127, 147
respectively. mese streams could alternatively enter the bottom of the
reactors 127, 147 individually, however in this scheme a m~re uniformly
mLxed feed is obtained for entry into the reactors 127, 147. For the
use of both reactors 127, 147, an alternate stream 152 is used to
intrcduce a moxed in-line stream to reactor 127 directly.
The key catalyst component stream 153 must enter the reactor 127
~or a stream 154 entering reactor 147 if both reactors of the preferred
embodineat are used) separately to prevent reaction before the
reactor(s).
- Reaction -
Tw~ reactors are shown in Figure 2 since tw~ or three reactors are
necessary to produce block polymers such as the styrene-butadiene block
ruhber~ A single reactor may be used to produce homopolymers c~nd random
coyolymers, hcwever for product quality flexibility, it may be desirable
to operate two reactors in parallel or in series. It should be
understood that the number of reactors is not a limitation for the
invention.
Fig. 2 shc~s ebullient or reflux cooled reactors 127, 147 connected
by gravity stream 160. Plternatively an auto-refrigeration system may
be used to recycle condensable vapors. Also, alternatively a pipe loop
or various other types of reactors may be used. The reactors 127, 147
should have a very high finish surface to minimiz~ sticking of rubber
particles to the reactor wall. Such a finish may be achieved by
polishing stainless, electro-polishing and possibly coatin~ the surface
of polished carbon steel with electro-less m cke~ or a hard teflon
~ 2'7 Fi~
surface. Also b~ffles should not protrude above the operatiny level in
the reaetor.
Eaeh reflux stream, stream 161 for reactor 127 and stream 163 for
reactor 147, is sprayed into the top of the respective reactor, all to
minimi2e stieking of p~rtieles.
An axial turbine agitator, agitator 165 for reaetor 127 and
agitator 167 for reaetor 147, is used to mix the reactants and suspend
the product partieles.
The pressure and temperature specifications for eaeh reaetor 127,
147 range from 150 to 500 psig and 300 to 550~F depending on the product
or products to be manufaetured.
e vapor effluent frc~n eaeh reactor 127, 147 flaws to a condenser,
condenser 169 for reaetor 127 and c~ndenser 171 for reactor 147, via
vapor streams 125, 173, respeetively. In the eondensers, the
condensibles of the vapors are liquified. The non~eondensible gases are
reeycled via a reeyele stream, stre~n 175 for reaetor 127 and stream 177
for reactor 147, by a blower, blower 179 for reaetor 127 and blawer 181
; for re~etor 147, to the bottom of each reactor, reactors 127, 147
respeeti~ely. m e liquified materials, such as the liquid reflux fm m
streams 161, 163 are pumped by a pump, pump 183 for reac~or 127 and pump
18, for reaetor 127, through a spray ring in each reactor, ring 187 for
reaetor 127 and r m g 189 ~or reactor 147. A stream 191 is provided to
vent a portion of the vapor recycle stream 175 to disposal, not shown,
automatlcally upon the rise of pressure on reaetor 127 ~eyond a set
po1nt detenmined by a pressure control loop 193.
; The simplest mode of operation is for the manufaeture of
homopol~ners and random copol~ners using only reaetor 127. In this mLde
the eo~bined stre~m 157 and the key eatalyst eomponent stream 153 flow
into the reaetor 127, and the rubber slurry discharges from the side of
the reaetor 127 as stream l9S to the wash eolumn 197.
For bloek copolymer, th~ combined stream 159, with only one monomer
and an alternate key catalyst aomponent stream 154, flow into reaetor
147. The seeond monomer stream 152 flows to the seeond reactor 127.
~ -8-
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Since the reac-tors 127, 1~7 are at the same pres-
sure, reactor 147 discharges by yravity through stream 160
to reac-tor 127. Reac-tor 127 discharges via stream 195 to
wash column 197 as before. In both modes the level con-trol
loop 199 provided on reactor 127 opera-tes the discharge valve
201 on the bottom of the wash column 197 to maintain level
in the reactors.
-Product Separation From Reactor Effluent-
The slurry from the reactor 127, stream 195, enters
the countercurrent wash column 197 about one-half to two-
thirds of the distance from the bottom of the column 197.
The key design parameters of the settling column 197 are the
ratio of liquid wash to liquid reactor effluent and the
; settling rate of the particles. The volumetric ratio of
settling liquid to reactor effluent liquid must be greater
than one to insure that the reactor effluent liquid dis-
charges at the top of the column 197 as stream 203 under
control by pressure control loop 205 goes to a purification
section, not shown, and is ultimately partially recycled
to stream 101 and partially recycled to column 197. The
preferred ratio is 1.25 to 1~75. The column 197 diameter
is designed such that the upward flow does not exceed the
particle settling rate with a preferred range of 2 to 7
feet per second for most elastomers. The liquid stream 207 .
is pumped to the bottom of column 197 by pump 209. The flow : :
is controlled by a flow control loop 211 which is reset or
cascaded by control loop 213 from the density controller
sensor, analy~.er 215.
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Alternatively, as shown in Figure 2, a portion
of stream 203 may be recycled via stream 206 directly to
reactor 147 of the reaction s-tep 20 under control of :Elow
control loop 208 to conserve catalyst and energy.
The bottom of column 197 discharges -the elastomer
particles in fresh diluent as stream 217. For discharge from
column 197, Figure 2 shows an intermittently discharging
three-way valve 201 operated by an open-closed position
timer 219 that is actuated by the reactor 127 level control
199. A gaseous stream 221 is recycled, as discussed infra,
to provide adequate velocity in stream 217.
Figure 2 shown a cone bottom 225 for the column
197. A number of alternate discharge configurations may be
posslble or even necessary. Alternatively, -the column 197
bottom section may be agitated or the column 197 mounted
on an agitated vessel.
Also the three-way valve 201 shown may be replaced
by a vane pump, a moyno pump, a continuously rotating plug,
or perhaps even a simple control valve depending on the size
of the flow and the characteristics of the slurry.
The surface of column 197 may be made of highly
polished stainless s-teel or electroless nickel coated car-
bon steel to minimize sticking of particles. The pressure
and temperature specification depend on the product manufac-
tured and diluent used but will usually range from lS0 to
500 psig and 300 to 550F, respectively,
; ~s shown in Figure 3, when the reactor effluent
in stream 195 is a solution, the settling column 197 is by-
passed. If catalyst removal is needed, Figure 3 shows stream
195 flowing to a mixer 226 where small amounts of catalyst
complexing agents from stream 228 via metering pump 230 are
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incorporated and reacted. The solution then flows to a
pair of hydrocyclones 227, 227A, or centrifuge, to separate
the denser catalyst complex. The clariEied polymer solu-
-tion is then discharged as stream 217 into the flash tube
229 under pressure control of valve 201 by pressure control
loop 232, rather than level control loop 199.
Waste :Erom cyclones 227, 227A is accumulated in
waste tanks 232, 232A, respectively, and is fed to waste
disposal (not shown) via stream 230 controlled by level con-
10 trollers 234, 234A, respectively. In addition, no flow is
permitted through control loop 211 and recycle from stream
207 all goes to stream 101 via stream 246.
The manufacture of liquid elastomer using another
alternate configuration of Figure 4 requires a different
modification of the process. A diluent is selected which
is not a solvent for the liquid polymer. The effluent of
the reactor 127 flows via stream 195 to a decanter 224. In
decanter 224, the liquid elastomer settles and is discharged
from the bottom of decanter 224 to an agitated film evapo-
20 rator 238 or a falling film dryer (not shown) via stream
248. The flow of fluid from decanter 224 is controlled by
interface controller 240. The remainder of the fluid in de-
canter 224 is diluent and flows via stream 203 to purifica-
tion. The vapor from film evaporator 238 flows to filter
237 via stream 235. The liquid from film evaporator 238
flows to storage (not shown) via stream 242. In addition,
no flow is permitted through control loop 211 and recycle
from stream 207 all goes to stream 101 via stream 246. Al-
ternately, the liquid elastomer could be discharged from
the bottom of decanter 224 to the flash tube 229.
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-Diluent Purl$ication-
The purifica-tion system is not shown in Figure 2
but would consist o:E a di.sti:llatio:n sys-tem -that removes low
boiling and high boiliny components and recycles via s-tream
2~3 the major center cut partly to the wash column via Elow
control 211 and the remainder to the begi.nning of the pro-
cess as part of stream 101 via stream 246 under control of
level control loop 244 which controls the level on vessel 245.
-Product Separation-
In either the configwration of Fugure 2 or Figure
3, the diluent or solvent 217 is flashed at the discharge
valve 201 by flash tube 229. Depending on the solids con-
centration, diluent and flash temperature, about one-half
to two-thirds of the liquid is vaporized instantaneously.
The flash tube 229 i.s a heat jacketed pipe connected between
the valve 201 and flash tank 233. The pipe diameter is de-
signed by provide a velocity of at least 3200 feet per minute
(53 feettsec) to convey the particles without sticking to
the flash tank 233. The length of the flash tube 229 is de-
signed to vaporize the remainder of the diluent and heat the
elastomer to the required temperature by providin~ sufficient
heat transfer surface and is a function of pipe diameter,
the desired rubber temperature and thus the amount of heat
to be transferred. As shown in Figure 2 and discussed supra,
for the concentrated slurries of this invention, some addi-
tional gaseous diluent is recycled by stream 221 to acheive
the necessary gas to solid ratio ~or dilute phase pneumatic
conveying through the flash tube 229.
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The ~as and par-ticula-te rubber ~rom the flash tube
229 enter the flash tan~ 233 -throucJh nozzle 23L where the gas
and particulate are separatec1. The flash tank 233 is designed
-to provide efficient cyclonic separation.
- Compression -
The gas from tank 233 exits tank 233 via stream 235and is filtered by filter 237 and compressed by compressors
239. Some of the gas is recycled from the first stage of
compressors 239 via stream 221 for flash tube conveying.
The majorlty of the gas is condensed after compression by
condensor 241, collected, and mixed with additional diluent
from purification stream 243 in vessel 245. The effluent
from vessel 245 is pumped to column 197 as wash liquid stream
207 using pump 209, as discussed supra and excess is mixed
with supply stream 101, via level controller 244.
The particulate rubber is discharged fromthe bot-
tom of tank 233 via a double trap door type valve 247 to the
fluid bed dryer 249.
The flash tank 233 is constructed of aluminum or
~; 20 stainless steel and polished to a hi~h finish and may be
coated with electroless nickel to minimize sticking of rub-
ber particles. Flashing pressure is in the range of 1 to 10
psig, and temperatures depend on the required particle temp-
erature to prevent agglomeration and other sticking of parti-
cles. This temperature ma~ range from -50 to 50F.
The remaining diluent gas and liquid, estimated
at perhaps 2%, is removed in the fluid bed dryer 249, using
closed loop nitrogen s-tream 251 as the fluidizing gas.
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76~
Figure 2 does not show the carbon or molecular
seive adsorption system used to remove hydrocarbon from
the nitrogen to maintain a reasonable concentration of hydro-
carbon in the nitrogen yas, but this is well known in the
art.
- Product Finishing -
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The particulate rubber is clischar~ed to the pneu-
matic conveying system from dryer 249 -throu~h -the double
trap door type valve 253 to s-tream 255 for pneumatic con-
veying product ~inishing step 80. The conveying medium for
tle pneumatic conveying system is air which enters the pro-
cess through filter 257. The air picks up the rubber parti-
cles at the venturi injector 259, and transports the parti-
cles via stream 261 to the cyclonic separa-tion-collector 263.
The motive force for this system is provided by a blower 265.
The particles are discharged from the collector 263 via a
double trap door type valve 267, where it goes to a baler
(not shown).
- Parameters -
The choice of a diluent or solvent is very im-
portant to this process. The diluent or solvent should have
a relative low boiling point to allow complete vaporization
from the elastomer at a temperature at which the elastomeric
particles are not sticky. This temperature is controlled by
a heated flash tube 229 ahead of the flash chamber 233 and
of course the choice of diluent or solvent. Obviously, the ..
diluent solubility characteristic relative to the polymer
must be such as to produce particulation in the reactor.
Thus the diluents or solvents are limited to C3, C4 and C5
hydrocarbons and Cl chlorinated hydrocarbon in most cases,
in these ionic catalyst polymerizations. Examples of such
diluents are propylene in ethylene-propylene-diene and methyl
chloride in butyl rubber polymerizations. This invention
includes the use of cis-butene-2 and mixtures of cis-butene-
2 with trans-butene-2 or butene-l and other C3, C~ and C5
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hyclrocarbons as a solvent ~or ci.s~polybutadiene, styrene-
bu-tadiene and cis-polyisoprene in app:L:ication to the pro-
cess of thls invention. Further, this i.nvention conceives
the use of C3, C4 and C5 hydrocarbons other -than cis-butene-
2 and cis internally unsaturated C5 olefins as diluents for
producing cis-polybutadiene, cis-polyisoprene and styrene-
butadiene random and block copolymer in particulate form.
A very important factor in producing quality cis-
polybu-tadi.ene, cis-polyisoprene, styrene-butadiene and ethyl-
ene-propylene-diene elastomers
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in particulate ~orm with the usual metal-oryanic catalysts
is -to add a modifier that minimizes or prevents cross-linking
reactions. Such modi.fiers are well ]~nown as Lewls bases.
Examples of the modifiers are ethers, tri alkyl amines and
dialkyl sulfides.
Another important feature of this process is the
use of electro-polishing or electroless nickel or teflon
to coat the surfaces of critical equipment to minimize or
prevent adhesion of elastomer. Equipment that may be coated
in this manner includes the reactors 127,147, the transfer
lines, the settling column 197 and the flash tank or cyclone
233.
Example 1 ~ `
A solution of 70 wt~% butadiene - 30 wt. % sty-
rene mixture at 30% concentration in isobutane is passed
through the 3A and 13X molecular sieves in sequence to
eliminate dissolved water and actylenic ana other organic
catalyst poisons. This stream and a n-butyl lithium stream
are separately metered to an autoclave reactor. The re- -
actor is equipped to remove the heat of polymerization by
the method of evaporating, condensing and recycling conden-
sate to the reactor. This method is commonly known as ebul-
lient or reflux cooling. rrhe conversion of butadiene and
styrene to styrene-butadiene rubber gives a slurry of this
rubber in isobutane. The size of the particles in the
` slurry is about 1/16" to 1/4", depending on the degree and
quality of agitation and the diluent composition. The re-
actor is equipped with a liquid level control that contin-
uously discharges an increment of the slurry. The slurry
passes to a settling column where the particles drop into
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fresh :isobutane and the fluiA from the reactor is discharged
:Erom the top of -the column. The settling column thus separ-
ates the particles :Erom the unreacted styrene and butad:i.ene.
The fluid from the top of the settling column may be parti-
ally recycled to the reactor to conserve s-tyrene-butadiene
and catalyst and the remainder is sent to a purlfication
section. The slurry from the bottom of the settling column
is discharged through a flash heater tube wherealmost all
the isobutane is vapori~ed, separated from the particles
in a flash tank, compressed, condensed, and recycled to the
settling column. The temperature of flashing is controlled
at a sufficiently low temperature to prevent stickiness of
` the rubber particles.
The rubber particles are discharged onto a closed-
loop nitrogen gas fluid bed dryer which removes residual
hydrocarbons. The rubber particles arepneumatically con-
veyed to a baling and packaging line.
Example 2
- The same process is used to manufacture styrene-
- 20 butadiene-styrene and styrene-isoprene-styrene block copoly-
mers except that three reactors is series are used. A 15
wt.% solution of styrene in propane is continuously fed
through 3A and 13X molecular sieves sequentially into the
first reactor along with a separate stream of n-butyl lithium
in isobutane. Polystyrene particles are continuously formed
and discharged from the first reactor to the second reactor.
Butadiene is continuously fed to the second reactor and
which continuously discharges to a third reactor (not shown).
Styrene is continuously fed to the third reactor.
The las-t reactor discharges to a settling column
where the particles are separated from the reactor fluid
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by dropping -through the fresh up-flowiny isobutane. The
overhead fluid from -the column is sent -to a purification
sec-tion. The block copolymer slurry is discharged through
a flash heater tube to a flash tank. Almost all the hydro~-
carbon fluid is vaporized in the flash tube. The vapors
from the flash tank are compressed, condensed and the con-
densate is recycled to the wash column.
The b]ock polymer particles are discharged from
the flash tank to a fluid bed dryer where the remainder of the
hydrocarbon fluid is vaporized and separated. The dry thermo-
plastic block copolymer is discharged from the fluid bed
dryer to a pneumatic conveying system and thence packaged.
Example 3
The same process is used to manufacture ethylene-
propylene-diene rubber. Propylene liquid is pumped through
3A and 13X molecular sieve in sequence. Propylene is the
diluent for the process. Ethylene is passed through 3A and
13X molecular sieves and mixed in-line with the propylene.
Diene monomer, catalyst modifier and the aluminum alkyl
catalyst component are also mixed in the propylene stream
enroute to the reactor. The vanadium ca-talyst component is
metered separately to the reactor.
The reactor is equipped for reflux cooling. Reflux
cooling may be accomplished as described in Example 1 or with
the use of a compressor to provide auto-refrigeration and
propylene recycle. Concentrations of polymer particles is
normally 25 to 35%. The reactor discharges continuously by
level control to a settling column where the rubber parti-
cles drop through the up-flowing fresh propylene. The
overhead from the settling column may be partially recycled
to the reactor to conserve catalyst and evergy and the
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remainder ls sent to a puriflcation unlt.
The slurry oE rubher particles ls discharged
through a heated flash tube -to a flash -tanlc. The tempera-
ture of the rubber particles is controlled to prevent stick-
iness by the design and amount of heat supplied to the flash
tube.
Essentially all of the propylene is vaporized in
a flash tube, separated in the flash tank and compressed,
condensed and the condensate is recycled to the settling
column. The rubber particles are discharged to a fluid
bed dryer which vaporizes and removes remaining hydrocarbon.
The rubber particles are discharged continuously from the
fluid bed dryer and pneumatically conveyed to the baling
and packaging line.
;~ Example 4
Cis-polybutadiene rubber is manufactured by the
same process sutadiene, 30 wt.% in n-butane, is metered
sequentially through 3A and 13~ molecular sieves and mixed
in line to the reactor with catalytic amounts of water
modifier, a Lewis base modifier and aluminum alkyl catalyst
component. A cobalt catalyst component is metered separately
to the reactor.
The reactor(s) is equipped for reflux cooling
; using either direct condensation of -the vaporized butane
and butadiene or by an auto-refrigeration system. The cis
polybutadiene rubber is a slurry in the diluent. The re-
actor continuously discharges the 30 wt.~ slurry to the
settling column where the rubber particles drop through up-
flowing fresh n-butane. The diluent from the reactor thus
is discharged from the top of the column. The fluid from
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-the -top of the column may be partially recycled to conserve
catalyst and energy ancl the remainder ls sent -to purification.
The slurry from -the bottom of the settl:ing column
is discharged continuously through a flash tube heater where
essentially all the diluent is vaporized to a Elash tank
where the particles are separated. The vapor is compressed,
condensed and recycled to the column. The rubber particles
are discharged continuously to a fluid bed dryer where the
remaining hydrocarbon is vaporized and removed. The dry-
cis-polybutadiene particles ranging from 1/6" to 1/4" are
discharged from the dryer and pneumatically conveyed to the
baling and packaging line.
Example 5
Cis polyisoprene is manufactured by the same pro-
cess. Isoprene, 30 wt.% in isobutane, is continuously metered
sequentially through 3A and 13X molecular sieves and mixed
in-line to the reactor(s) with aluminum alkyl catalyst com-
ponent and a catalyst modifier. A titanium catalyst com-
ponent is metered separately to the reactor.
The reactor(s) is equipped for reflux cooling
; using either direct condensation o~ the vaporized isobutane
or an auto-refrigeration system. The cis-polyisoprene rub-
ber is a slurry in the diluent. The reactor(s) continuously
discharges the 30 wt. ~ slurry to the settling column where
the rubber particles drop through the up-flowing fresh iso-
butane. The diluent from the reactor thus is discharged
f~om the top of the column~ This fluid from the top of the
column may be partially recycled fro~ the top of the column
to the reactor to conserve catalyst and energy and the re-
mainder is sent to the purification system.
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The slurry Erom -the bottom of the set-tl:ing column is
discharged con-tinuously through -the flash heater tube where
essentlally all the diluent is vaporlzed -to the Elash -tank.
Elashing temperature is controlled to prevent stickiness.
The vapor is compressed, condensed and recycled to the set-
tling column. The rubber particles are discharged to the
fluid bed dryer where the remainder oE the light hydrocarbons
are vaporized and removed.
~ The dry, cis-polyisoprene rubber particles are dis-
charged continuously from the fluid bed dryer and pneumati-
cally conveyed to the baling and packaging line.
Example 6
Epichlorohydrin homo and copolymer with ethylene
oxide is manufactured by the same process. Epichlorohydrin
or epichlorohydrin and ethylene oxide, 30 wt.% in isobutane,
are continuously metered sequentially through 3A and 13X
molecular sieves and mixed in-line to the reactor(s) with
a catalytic quantity of water. An aluminum alkyl catalyst
component is metered separately to the reactor(s).
The reactor(s) is equipped either for direct con-
densing of vaporized isobutane or with an auto-refrigeration
system. Epichlorin rubber is a slurry in the diluent. The
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reactor(s~ continuously discharges a 30 wt.~ slurry to the
settling column where the rubber particles drop through the up-
flowing fresh isobutane. The diluent from the reactor is
thus discharged from the top of the settling column. This
fluid may be partially recycled to the reactor to conserve
catalyst and energy and the remainder is sent to the puri-
fication system.
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The slurry Erom the bot-tom of -the se-ttling column
is continuously clischarged -tllrough the Elash heater tube
where essentially all -the dlluent is vaporized to the elash
tank. Flashlng temperature was controlled -to preven-t stick-
iness of the epichlorohydrin rubber particles. The vapor
from the flash tank is compressed, condensed and recycled
to the settling column. The rubber particles are discharged
to -the fluid bed dryer where any remaining llght hydrocarbon
is vaporized and removed.
The dry, epichlorohydrin rubber particles are con-
tinuously discharged from the fluid bed dryer and pneumati-
cally conveyed to the baling and packaging line.
Example 7
~utyl rubber (97% isobutylene-3~ isoprene) is
manufactured by the same process. Isobutylene-isoprene,
30 wt.% in methyl chloride, is continuously metered sequen-
tially through 3A and 13X molecular sieved and ~ixed in
line to the reactor(s) with catalytic quantities of water.
Aluminum alkyl chloride catalyst component is metered separ-
ately to the reactor.
The reactor(s) are e~uipped with either direct
condensation of vaporized methyl chloride or with an auto-
refrigeration system. Butyl rubber is a slurry in methyl
chloride. The reactor(s) continuously discharges the 30Wt~
slurry to the settling column where the particles drop through
up-flowin~ fresh methyl chloride. The diluent from the re-
actor is thus discharged from the top of the settling column.
This fluid may be partially recycled to conserve catalyst
and energy and the remainder is sent to the purification
system.
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The slurry from the bot-tom of the settling column
is continuously d:ischarged through the flash heater where
essentlally all the diluent and ligh-t hydrocarbons vaporize
to the :Elash tank. Flashing temperature is controlled to
prevent stickiness of the rubber particles. The vapor from
the flash tank is compressed, condensed and recycled to the
settling column. The butyl rubber particles are discharged
to the fluid bed dryer where any remaining methyl chloride
and light hydrocarbons are vaporised and removed.
The dry butyl rubber particles were discharged
continuously and pneumatically conveyed to the baling and
packaging line.
Example 8
Solution polymerized cis-polybutadiene is manu-
factured by a slight modification of this process. suta-
diene, 15 wt% in cis-butene-2, is continuously metered se-
quentially through 3A and 13X molecular sieves and mixed
in-line to the reactor(s) with catalytic amounts of water,
a modifier and an aluminum alkyl catalyst component. A
cobalt catalyst component is metered separately to the re-
actor(s).
The reactor(s) is equipped for either direct con-
densation of cis-butene-2 and butadiene vapor or with an
auto-refrigeration system.
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Cis-polybutadiene i5 a solution in cis-butene-2. The reactor(s)
continuously discharge the 15% cis-polybutadiene soluti~n through the
flash heater tube to the flash tank without the use of column 197. The
cis-polybutadiene solution is almost instantaneously converted to
particles conveyed in cis-butene-2 and butadiene vapor in the flash
tube. The flash tank separates the vapor and cis-polybutadiene
particles. The vapor is ccmpressed, condensed and sent to the
purification system.
The ruhber particles discharged to the fluid becl dryer where any
remaining light hydrocar~ons are vaporized and rem~ved. The dry
cis-polybutadiene particles are discharged continuously from the dryer
and pneumatically conveyed to the baling and packaging line.
EXample 9
Solution polymerized cis-polyisoprene is manufactured by a slight
modification of this process. Isoprene, 15 Wt~ in cis-butene-2, is
continuously metered sequentially through 3A and 13X molecular sieves
and nuxed in-line to the reactor(s) with a modifier and an aluminum
aLkyl catalyst component. A titanium catalyst component is metered
separately to the reactor~s~.
The reactor(s) is equipped either f~r direct condensation of the
ci~--butene-2 and isoprene vapor or with an auto-refrigelation system.
Cis-polyisoprene is a solution in cis-butene-2.
The reactor discharges continuously to an in-line muxer where it is
mixed with a small amount of a catalyst co~?lexing agent and then to a
hy ~ocyclone or centrifuge to separate the ccnplexed catalyst.
The clarified cis-polyisoprene solution is then flashed in the
heated flash tube where it is essentially instantaneously converted to
cis polysiopxene particles in cis-butene-2 vapor. m e flash temperature
is contxolled to prevent stickiness. me gas and xubker particles are
separated in the flash tank. The vapors are compressed, condensed and
sent to the purification system.
The ru~ber particles from the flash tank are cont muously
discharged to the fluid bed dryer where any remaining light hydrocaxbons
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are vaporized and removed. The cis-polyisoprene rubber particles are
continuously discharyed from the dryer and pnuematically conveyed to the
baling and packaging line.
It is to be understood that the process of this invention is not
limited to the specific pieces of equipment described above~
For example, batch operation would be sequential rather than
continual running of the reactors with the reactors charging from the
feed streams and discharging through the column and flash tube.
~ccordingly, although the system described in detail above is most
satisfactory and preferred, many variations in structure and method are
possible, such as changes in vessels, valves and materials of
construction describ~d ~E~-
Because many varying and different embodinents may be made withinthe scope of the inventive concept herein taught, and because
mcdifications may be made in accord3nce wit~ the descriptive
requirements of the law, it should be understood that the details herein
are to be interpreted as illustrative and not in a limiting sense.
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