CA1070879A - Continuous latex stripping method - Google Patents
Continuous latex stripping methodInfo
- Publication number
- CA1070879A CA1070879A CA233,504A CA233504A CA1070879A CA 1070879 A CA1070879 A CA 1070879A CA 233504 A CA233504 A CA 233504A CA 1070879 A CA1070879 A CA 1070879A
- Authority
- CA
- Canada
- Prior art keywords
- steam
- latex
- contactor
- pressure
- tubular
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/14—Evaporating with heated gases or vapours or liquids in contact with the liquid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
- B01D3/38—Steam distillation
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In the typical embodiment disclosed in the application, continuous stripping of a monomer from a temperature and shear-sensitive polymer latex is accomplished by contacting the latex with steam in an unheated tubular contactor. Temperatures and pressures are controlled so as to permit complete stripping of the monomer without subjecting the latex polymer to excessive temperature or turbulent flow conditions.
In the typical embodiment disclosed in the application, continuous stripping of a monomer from a temperature and shear-sensitive polymer latex is accomplished by contacting the latex with steam in an unheated tubular contactor. Temperatures and pressures are controlled so as to permit complete stripping of the monomer without subjecting the latex polymer to excessive temperature or turbulent flow conditions.
Description
BRIEF SUMMARY OF THE INVENTION.
This invention relates to latex stripping methods and, more particularly, to a new and improved method o~ continuous and efficient stripping of latices which are~sensitive to excessive heat and agitation.
Heretofore, monomers have usually been extracted from polymeric latices of low stability by steam sparged, batch-type, vacuum stri~ping methods., Continuous stripping methods such as ' countercurrent tray columns, continuouS feea and overflow stirred .
,,. ' ~3~ ' ~ e~t7 ' ~
~_~ ,, ' l- ., -:
~ Z2301 1~7C~879 tan}c~ (similar physically to batch), and tortuous path dispersed flow ,~trippers as described by Palmason in U. S. patent No.
3, 469, 617, have been used to remove monomers from latices which are relatively insensitive to shear or overheating. For continuous production of foamy, low stability latices, by the batch method, multiple batch units must be installed, each with a complete - 3et of controls, to avoid foaming, and close operator attention .
to each batch unit is required. Coagulation yield losses and associated cleaning costs are high for many latices.
Continuous tortuous path type strippers, as described, for example, in Palmason U. S. patent No. 3, 469, 617, have been employed widely in latex stripping to overcome many of the above-mentioned problems of batch stripping methods. The Palmason method, by its very nature, treats a latex under highly turbulent conditions involving considerable shear and relatively high inlet steam-latex "mixing" temperatures. While these conditions enhancP stripping efficiencies, some latices are too unstable to process by this method. Continuous tower ~ype strippers are also undesirable for very unstable and foamy latices due to the cascading actions and the tendency of the trays to become plugged by coagulum, and because of increasing pressure and temperature from top to bottom of a column, they tend to cause dilution of the processed latex.
Accordingly, it is an object of the pxesent invention to provide a method for the continuous stripping of monomers from synthetic polymcr latices which are sensitive to agitation and high temperatures.
7~79 Thus, in accordance with the present invention, a metl~od is provided for stripping a volatile constituent from a mixture containing a latex polymer which is sensitive to shear and high temperature. The method comprises injecting the latex into a confined stream of steam and passing the steam-latex mixture concurrently through a tubular contactor having a length-to-diameter ratio of at least 20:1. The temperature at the point of injection is maintained between about 115F. and about 18~F.
Substantially all of the heat is supplied in the thbular contactor by means of the steam-latex mixture passing through the tubular contactor. The pressure at the point of injection is maintained between about 1.5 psia and about 7.5 psia. The steam-latex mixture is passed through at least one bend having an angle of at least 45 within the contactor and directly into a liquid-vapor separator. The pressure in the liquid-vapor ~eparator is maintained at at least 0.5 psia lower than the pressure maintained at the point of injection of the latex and the steam within the tubular contactor.
In certain embodiments of the invention, a latex to be stripped is initially injected into and contacted with stripping steam and then passed in cocurrent flow with the steam through an unheated tubular contactor section from which the stripped latex and monomer and/or solvent laden steam enter a cyclonic vapor-liquid separator under vacuum. The stripped or partially stripped latex flows out through the separator bottom and is pumped either to a subsequent stripping stage or a storage tan~
or other process step.
DESCRIPTION OF THE DRAWING
The single figure of the drawing schematically illustrates a representative apparatus arranged to carry out the invention.
~ _ 3 _ .
1~70~79 DETAILED DESCRIPTION
- In the typical embodiment of the apparatus for carrying out the invention schematically illustrated in the drawing, a latex polymer containing a monomer to be stripped is supplied at a controlled rate by a pump 10 through a temperature control 11 to an injecting "fid" 12 disposed near one end of a tubular contactor .~
- 3a -:., . :~
1C~7~3~379 13, Steam supplicd through a pressure control 14 and a ternperature control 15 is applied near the end 16 of the tubular co~ntactor 13 wh~ch is adjacent to the fid 12.
The fid 12 may be of the type described and illustrated in Fig. 3 of patent No. 3, 469, 617 and is positioned to provide an annular space bet~,veen its outer surface and the interior wall of the contactor 13 through which steam flows. An adjustable an~ular groove 17 in the fid injects the latex into the annular 6pace, causing it to mix with the steam without producing significant turbulence. To assure complete stripping without overheating the latex, the temperature of the steam and latex ~upplied to the contactor are controlled so that the temperature of the mixture at the point of mixing is at least 115F and no more than 180F, the particular temperature being dependent on the characteristics of the latex and the monomer as well as the structure of the contactor. Below 115 F stripping is not ac-complished efficiently and above 180 F heat sensitive latices are degraded.
In order to assure adequate contact between the steam and the latex without e~ccessive agitation, the tubular contactor is shaped with two successive 90 bends, designated 18 and 19 in the drawing. The contactor may be of the general type described, for example, in thc U. S. patent to Morro-v, No. 2, 487, 769, but no heat is applied to ihe wall o~ the contactor. The tubular con-
This invention relates to latex stripping methods and, more particularly, to a new and improved method o~ continuous and efficient stripping of latices which are~sensitive to excessive heat and agitation.
Heretofore, monomers have usually been extracted from polymeric latices of low stability by steam sparged, batch-type, vacuum stri~ping methods., Continuous stripping methods such as ' countercurrent tray columns, continuouS feea and overflow stirred .
,,. ' ~3~ ' ~ e~t7 ' ~
~_~ ,, ' l- ., -:
~ Z2301 1~7C~879 tan}c~ (similar physically to batch), and tortuous path dispersed flow ,~trippers as described by Palmason in U. S. patent No.
3, 469, 617, have been used to remove monomers from latices which are relatively insensitive to shear or overheating. For continuous production of foamy, low stability latices, by the batch method, multiple batch units must be installed, each with a complete - 3et of controls, to avoid foaming, and close operator attention .
to each batch unit is required. Coagulation yield losses and associated cleaning costs are high for many latices.
Continuous tortuous path type strippers, as described, for example, in Palmason U. S. patent No. 3, 469, 617, have been employed widely in latex stripping to overcome many of the above-mentioned problems of batch stripping methods. The Palmason method, by its very nature, treats a latex under highly turbulent conditions involving considerable shear and relatively high inlet steam-latex "mixing" temperatures. While these conditions enhancP stripping efficiencies, some latices are too unstable to process by this method. Continuous tower ~ype strippers are also undesirable for very unstable and foamy latices due to the cascading actions and the tendency of the trays to become plugged by coagulum, and because of increasing pressure and temperature from top to bottom of a column, they tend to cause dilution of the processed latex.
Accordingly, it is an object of the pxesent invention to provide a method for the continuous stripping of monomers from synthetic polymcr latices which are sensitive to agitation and high temperatures.
7~79 Thus, in accordance with the present invention, a metl~od is provided for stripping a volatile constituent from a mixture containing a latex polymer which is sensitive to shear and high temperature. The method comprises injecting the latex into a confined stream of steam and passing the steam-latex mixture concurrently through a tubular contactor having a length-to-diameter ratio of at least 20:1. The temperature at the point of injection is maintained between about 115F. and about 18~F.
Substantially all of the heat is supplied in the thbular contactor by means of the steam-latex mixture passing through the tubular contactor. The pressure at the point of injection is maintained between about 1.5 psia and about 7.5 psia. The steam-latex mixture is passed through at least one bend having an angle of at least 45 within the contactor and directly into a liquid-vapor separator. The pressure in the liquid-vapor ~eparator is maintained at at least 0.5 psia lower than the pressure maintained at the point of injection of the latex and the steam within the tubular contactor.
In certain embodiments of the invention, a latex to be stripped is initially injected into and contacted with stripping steam and then passed in cocurrent flow with the steam through an unheated tubular contactor section from which the stripped latex and monomer and/or solvent laden steam enter a cyclonic vapor-liquid separator under vacuum. The stripped or partially stripped latex flows out through the separator bottom and is pumped either to a subsequent stripping stage or a storage tan~
or other process step.
DESCRIPTION OF THE DRAWING
The single figure of the drawing schematically illustrates a representative apparatus arranged to carry out the invention.
~ _ 3 _ .
1~70~79 DETAILED DESCRIPTION
- In the typical embodiment of the apparatus for carrying out the invention schematically illustrated in the drawing, a latex polymer containing a monomer to be stripped is supplied at a controlled rate by a pump 10 through a temperature control 11 to an injecting "fid" 12 disposed near one end of a tubular contactor .~
- 3a -:., . :~
1C~7~3~379 13, Steam supplicd through a pressure control 14 and a ternperature control 15 is applied near the end 16 of the tubular co~ntactor 13 wh~ch is adjacent to the fid 12.
The fid 12 may be of the type described and illustrated in Fig. 3 of patent No. 3, 469, 617 and is positioned to provide an annular space bet~,veen its outer surface and the interior wall of the contactor 13 through which steam flows. An adjustable an~ular groove 17 in the fid injects the latex into the annular 6pace, causing it to mix with the steam without producing significant turbulence. To assure complete stripping without overheating the latex, the temperature of the steam and latex ~upplied to the contactor are controlled so that the temperature of the mixture at the point of mixing is at least 115F and no more than 180F, the particular temperature being dependent on the characteristics of the latex and the monomer as well as the structure of the contactor. Below 115 F stripping is not ac-complished efficiently and above 180 F heat sensitive latices are degraded.
In order to assure adequate contact between the steam and the latex without e~ccessive agitation, the tubular contactor is shaped with two successive 90 bends, designated 18 and 19 in the drawing. The contactor may be of the general type described, for example, in thc U. S. patent to Morro-v, No. 2, 487, 769, but no heat is applied to ihe wall o~ the contactor. The tubular con-
2~ tactor may be madc of any materials such as carbon steel, stain-less stecl, or glass, which has sufficicnt strength and is resist~nt to corrosit-n by chc~ icals ancl thc total lcngth-to-diamctcr ratio o the activc part of thc tul)ular contactor should bc at lcast 20:1 and may be as hi~h aY 200:1, I~ desircd, ~7~879 thc tubular contactor may have only one bend, and the angle of each bend may be as small as 45, Froln the outlet end 20 of the tubular contactor the mixture of steam, latex polymer, and extracted monomer flows to a cyclone-type vapor-liquid separator 22 from which the vapor constituents are removed through a line 23 connected through a .. . . .
pressure control unit 24. If desired, the exhausted vapor Irom the line 23 may be passed through a monomer and solvent recovery arrangement utilizing appropriate condensing and condensate removal equipment (not shown).
To assure effecient stripping of the monomer in the contactor 13 without e~;cessive heating or turbulence of the latex, the pressure control unit 24 maintains the pressure in the separator 22 at leasl: 0. 5 psi lower and preferable 1 to 7 psi lower than the pressure at the mixing point adjacent to the fid 12, which is maintained between about 1. 5 psia and about 7. 5 psia.
Pressures at the mixing point below about 1. 5 psia, seriously limit throughput capac ity and eficiency, while pr e s sure s greate r than about 7. 5 psia cause degradation of heat sensitive latlces.
For substantially complete and effect1ve stripping operation of certain latices at high flow rates while maintaining opcration within the required temperature and pressure ranges, a two-stage stripping operation is desirable. For this purpose, the latex drawin from the bottom of the separator 22 through a line 25 is transn~itted by a pump 26 into a second stage arranged and operated in the same manner descri~ed in connection with the first stage. For convcnicnce, the elements of the second stage corresponding to tho5e of the first stage are identified in the drawing with primed refcrence numerals, ! 2230 1~70879 .
~ he following typical examples are illustrative of the advantages achieved by the method of the invention:
Example 1 An acrylic polymer latex containing approximately 26-28%
solids and approximately 4% acrylonitrile monomer was to be stripped at a feed rate of approximately 24,000 lbs./hr. to a level of 0.4% acrylonitrile. To illustrate the disadvantages of the ~rior art, a two-stage process arra~ged in the manner shown in the drawing, but using tortuous path plate type contactors of the type described in U.S. patent No. 3,469,617! in place of the tubular contactors 13, and 131. While this arrangement worked well with respect to acrylonitrile removal, the rate of formation and accumulation of polymer coagulum in the plate contactors was excessive. This coagulum buildup caused the contactor pressure drop to increase, thus incxeasing the temperature which, in turn, accelerated the coagulum formation. The net result was an excessive required shutdown and cleaning frequency.
The same acrylic latex polymer was processed in accor-dance with the present invention utilizing dual parallel 6-inch ~iameter tubular contactors with length to diameter ratio of approximately 25:1 in the arrangement shown in the drawing. ~his ~ystem operated successfully without the problem of capacity reduc-tion due to coagulum deposits and the necessity for frequent cleaning. Typical operating parameters for an embodiment of the in~ention arranged for production at a commercial rate are given below:
1st Stage 2nd Stage ~atex feed rate, lbs./hr.24,000 ------Latex feed wt.% total solids 26 ------0 Latex feed wt.~ acrylonitrile 4.2 0.8 Steam rate, lbs./hr. 1,690 1,690 Mixing Temperature, F 151 148 .
2~301 379 l~t. Stage 2nd. Stage Separator Temperature, F lZ0 120 - Stripped latex wt; % total solid~ _ 26. 4 5tripped latex wt. % acrylonitrile 0.8 0. 4 The above data represents fully acceptable operation and a sub-stantial improvement over the operation of a system as described in U, S. patent No. 3, 469, 617.
Example 2 It was desired to strip toluene from a feed emulsion 1~ containing 15% toluene, 30~o rosin, and 55% water. This emulsion comprises emulsified particles of rosin-in-toluene solution in a continuous water phase. Rapid removal of toluene leaves a rosin-in^water emulsion which is very foamy and very sensitive to temperature and shear coagulation, To illustrate the disadvantages of the prior art, a run was made using a plate contactor of the type disclosed in U. S. patent No. 3, 469, 617 in a single stage process. Data from a 45-minute run are given below:
Start Run End Run Emulsion feed rate, lbs. hr 81 81 Feed wt. ~o toluene 14, 3 14. 3 Feed wt, % rosin solids 27. 8 27. 8 Stripping steam rate, lbs. /hr. 44 41 Mixing temperature, F 162 172 Separator pressure, mm Hg 116 125 Product wt. % toluene 0. 52 1. 4 Lbs. steam/lb. rosin 1. 9 1, 7 During this short run, coagulum formed and deposited in the plate contactor at an unacceptably high rate, causing the mixing pressure and temperature to ri se and requiring shutdown. The plates were opened and found to be heavily fouled.
In accordance with the present invention, a tubular contactor having a 1-1/2" diameter and a length to diameter ratio of ~8:1 and containing two 45 bends was assembled. When the same emulsion was supplied to the tubular contactor system, it operated successfuliy for 5 hours with no indication at that 22.01 time of serious coagulum deposits. Typical data taken during ~his two-stage run are given below.
1st Stage 2nd Stage Emulsion feed rate, lbs./hr. 245 211 Feed wt.~ toluene 14.1 2.2 ~eed wt.% rosin solids 26.6 27.8 Stripping steam rate, lbs./hr. 62 51 Mixing temperature, F 135 136 Separator pressure, mm Hg.118 115 Product wt.~ toluene 2.3 0.5 Lbs. steam/lb. rosln 1.9 0.93 m e above data represented fully acceptable operation and a dis-tinct advantage over the process of patent No~ 3,469,617.
The invention is especially effective for stripping feed emulsions in which the volatiles (monomers or solvents) to be stripped are mainly present, either dissolved or dispersed, in the water phase from which they can be rapidly removed. One such example is acrylonitrile which is water soluble. In the case of Example 2, the toluene is not water soluble; but, because of its high concentration, it acts similarly to a dispersed free solvent (in the water phase).
Attempts to use the invention to strip monomers or sol-vents which are closely bound to the latex have not thus far been successful. ~or example, the stripping of styrene from car-boxylated styrene-butadiene latices has not been accomplished apparently because the styrene is contained mainly inside the polymer particles and can not diffuse readily out to the water phase under the conditions of the test. The results were that styrene removal was poor and that severe foaming occurred, probably because styrene diffused from the polymer and vaporized as the latex discharged from the contactor into the separator.
From the fore~oing, it will be apparent that the present invention provides a high capacity continuous stripping method .
223~1 . 1~7~:)879 which operates without foaming, with low process holdup, good control, and OGCUpieS reiatively little plant space while'at the same time overcoming the relatively rapid coagulum plugging and necessary cleanout experienced by the Palmason method in this 5 ' service.
' Although the invention has been described herein with' reference to specific embodiments and typical examples, many mo*ifications and variations therein will readily occur to those skilled in the art. Accordingly, all such variations and modi-' ~
'fications are included within the intended scope of the invention as defined by the appended claims.
pressure control unit 24. If desired, the exhausted vapor Irom the line 23 may be passed through a monomer and solvent recovery arrangement utilizing appropriate condensing and condensate removal equipment (not shown).
To assure effecient stripping of the monomer in the contactor 13 without e~;cessive heating or turbulence of the latex, the pressure control unit 24 maintains the pressure in the separator 22 at leasl: 0. 5 psi lower and preferable 1 to 7 psi lower than the pressure at the mixing point adjacent to the fid 12, which is maintained between about 1. 5 psia and about 7. 5 psia.
Pressures at the mixing point below about 1. 5 psia, seriously limit throughput capac ity and eficiency, while pr e s sure s greate r than about 7. 5 psia cause degradation of heat sensitive latlces.
For substantially complete and effect1ve stripping operation of certain latices at high flow rates while maintaining opcration within the required temperature and pressure ranges, a two-stage stripping operation is desirable. For this purpose, the latex drawin from the bottom of the separator 22 through a line 25 is transn~itted by a pump 26 into a second stage arranged and operated in the same manner descri~ed in connection with the first stage. For convcnicnce, the elements of the second stage corresponding to tho5e of the first stage are identified in the drawing with primed refcrence numerals, ! 2230 1~70879 .
~ he following typical examples are illustrative of the advantages achieved by the method of the invention:
Example 1 An acrylic polymer latex containing approximately 26-28%
solids and approximately 4% acrylonitrile monomer was to be stripped at a feed rate of approximately 24,000 lbs./hr. to a level of 0.4% acrylonitrile. To illustrate the disadvantages of the ~rior art, a two-stage process arra~ged in the manner shown in the drawing, but using tortuous path plate type contactors of the type described in U.S. patent No. 3,469,617! in place of the tubular contactors 13, and 131. While this arrangement worked well with respect to acrylonitrile removal, the rate of formation and accumulation of polymer coagulum in the plate contactors was excessive. This coagulum buildup caused the contactor pressure drop to increase, thus incxeasing the temperature which, in turn, accelerated the coagulum formation. The net result was an excessive required shutdown and cleaning frequency.
The same acrylic latex polymer was processed in accor-dance with the present invention utilizing dual parallel 6-inch ~iameter tubular contactors with length to diameter ratio of approximately 25:1 in the arrangement shown in the drawing. ~his ~ystem operated successfully without the problem of capacity reduc-tion due to coagulum deposits and the necessity for frequent cleaning. Typical operating parameters for an embodiment of the in~ention arranged for production at a commercial rate are given below:
1st Stage 2nd Stage ~atex feed rate, lbs./hr.24,000 ------Latex feed wt.% total solids 26 ------0 Latex feed wt.~ acrylonitrile 4.2 0.8 Steam rate, lbs./hr. 1,690 1,690 Mixing Temperature, F 151 148 .
2~301 379 l~t. Stage 2nd. Stage Separator Temperature, F lZ0 120 - Stripped latex wt; % total solid~ _ 26. 4 5tripped latex wt. % acrylonitrile 0.8 0. 4 The above data represents fully acceptable operation and a sub-stantial improvement over the operation of a system as described in U, S. patent No. 3, 469, 617.
Example 2 It was desired to strip toluene from a feed emulsion 1~ containing 15% toluene, 30~o rosin, and 55% water. This emulsion comprises emulsified particles of rosin-in-toluene solution in a continuous water phase. Rapid removal of toluene leaves a rosin-in^water emulsion which is very foamy and very sensitive to temperature and shear coagulation, To illustrate the disadvantages of the prior art, a run was made using a plate contactor of the type disclosed in U. S. patent No. 3, 469, 617 in a single stage process. Data from a 45-minute run are given below:
Start Run End Run Emulsion feed rate, lbs. hr 81 81 Feed wt. ~o toluene 14, 3 14. 3 Feed wt, % rosin solids 27. 8 27. 8 Stripping steam rate, lbs. /hr. 44 41 Mixing temperature, F 162 172 Separator pressure, mm Hg 116 125 Product wt. % toluene 0. 52 1. 4 Lbs. steam/lb. rosin 1. 9 1, 7 During this short run, coagulum formed and deposited in the plate contactor at an unacceptably high rate, causing the mixing pressure and temperature to ri se and requiring shutdown. The plates were opened and found to be heavily fouled.
In accordance with the present invention, a tubular contactor having a 1-1/2" diameter and a length to diameter ratio of ~8:1 and containing two 45 bends was assembled. When the same emulsion was supplied to the tubular contactor system, it operated successfuliy for 5 hours with no indication at that 22.01 time of serious coagulum deposits. Typical data taken during ~his two-stage run are given below.
1st Stage 2nd Stage Emulsion feed rate, lbs./hr. 245 211 Feed wt.~ toluene 14.1 2.2 ~eed wt.% rosin solids 26.6 27.8 Stripping steam rate, lbs./hr. 62 51 Mixing temperature, F 135 136 Separator pressure, mm Hg.118 115 Product wt.~ toluene 2.3 0.5 Lbs. steam/lb. rosln 1.9 0.93 m e above data represented fully acceptable operation and a dis-tinct advantage over the process of patent No~ 3,469,617.
The invention is especially effective for stripping feed emulsions in which the volatiles (monomers or solvents) to be stripped are mainly present, either dissolved or dispersed, in the water phase from which they can be rapidly removed. One such example is acrylonitrile which is water soluble. In the case of Example 2, the toluene is not water soluble; but, because of its high concentration, it acts similarly to a dispersed free solvent (in the water phase).
Attempts to use the invention to strip monomers or sol-vents which are closely bound to the latex have not thus far been successful. ~or example, the stripping of styrene from car-boxylated styrene-butadiene latices has not been accomplished apparently because the styrene is contained mainly inside the polymer particles and can not diffuse readily out to the water phase under the conditions of the test. The results were that styrene removal was poor and that severe foaming occurred, probably because styrene diffused from the polymer and vaporized as the latex discharged from the contactor into the separator.
From the fore~oing, it will be apparent that the present invention provides a high capacity continuous stripping method .
223~1 . 1~7~:)879 which operates without foaming, with low process holdup, good control, and OGCUpieS reiatively little plant space while'at the same time overcoming the relatively rapid coagulum plugging and necessary cleanout experienced by the Palmason method in this 5 ' service.
' Although the invention has been described herein with' reference to specific embodiments and typical examples, many mo*ifications and variations therein will readily occur to those skilled in the art. Accordingly, all such variations and modi-' ~
'fications are included within the intended scope of the invention as defined by the appended claims.
Claims (8)
1. A method for stripping a volatile constituent from a mixture containing a latex polymer which is sensitive to shear and high temperature comprising injecting said latex into a confined stream of steam and passing the steam-latex mixture concurrently through a tubular contactor having a length-to-diameter ratio of at least 20:1, maintaining the temperature at the point of injection between about 115°F and about 180°F, supplying substantially all heat in said tubular contactor by means of the steam-latex mixture passing through said tubular contactor, maintaining the pressure at the point of injection between about 1.5 psia and about 7.5 psia, passing the steam-latex mixture through at least one bend having an angle of at least 45° within the contactor and directly into a vapor-liquid separator, and maintaining the pressure in the vapor-liquid separator at least 0.5 psia lower than the pressure maintained at the point of injection of the latex and the steam within the tubular contactor.
2. A method according to claim 1 wherein the pressure in the separator is maintained between 1 and 7 psia lower than the pressure at the point of injection in the contactor.
3. A method according to claim 1 wherein the steam-latex mixture is passed through at least one bend having an angle of about 90° within the tubular contactor.
4. A method according to claim 1 wherein the steam-latex mixture is passed through at least two bends each having an angle of at least 90° within the tubular contactor.
5. A method according to claim 1 including the steps of injecting latex removed from the separator into a confined stream of steam and passing the steam-latex mixture concurrently through a second tubular contactor having a length-to-diameter ratio of at least 20:1, maintaining the temperature at the point of injection in the second tubular contactor between about 115°F, and about 180°F, maintaining the pressure at the point of injec-tion in the second tubular contactor between about 1.5 psia and about 7.5 psia, passing the steam-liquid mixture through at least one bend having an angle of at least 45° within the second tubu-lar contactor and directly into a second vapor-liquid separator, and maintaining the pre-sure in the second vapor-liquid separator at least 0.5 psia lower than the pressure at the point of injec-tion of the latex and the steam within the second tubular contactor.
6. A method according to claim 5 wherein the pressure in the second separator is maintained between 1 and 7 psia lower than the pressure at the point of injection within the second tubular contactor.
7. A method according to claim 5 wherein the steam-latex mixture is passed through at least one bend having an angle of at least 90° within the second tubular contactor.
8. A method according to claim 5 wherein the steam-latex mixture is passed through at least two bends each having an angle of at least 90° within the second tubular contactor.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US49820174A | 1974-08-16 | 1974-08-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1070879A true CA1070879A (en) | 1980-01-29 |
Family
ID=23980003
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA233,504A Expired CA1070879A (en) | 1974-08-16 | 1975-08-15 | Continuous latex stripping method |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5141780A (en) |
| CA (1) | CA1070879A (en) |
| DE (1) | DE2532264A1 (en) |
| FR (1) | FR2281946A1 (en) |
| GB (1) | GB1466515A (en) |
| NL (1) | NL7508078A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2521401C3 (en) * | 1975-05-14 | 1985-07-18 | Chemische Werke Hüls AG, 4370 Marl | Process for the continuous removal of monomeric impurities from aqueous dispersions of homo- and copolymers of vinyl chloride |
| JPS549302A (en) * | 1977-06-23 | 1979-01-24 | Netsukou Gijiyutsu Kk | Drain recovery device in boiler |
| US4130527A (en) * | 1977-12-29 | 1978-12-19 | Stauffer Chemical Company | Method of treating a polymer latex to remove unreacted monomer by treatment in a column |
| CN1038762C (en) * | 1989-10-21 | 1998-06-17 | 日本石油化学株式会社 | Method for refining urushi (Japanese lacquer) |
| GB9407504D0 (en) * | 1994-04-15 | 1994-06-08 | Crown Chemtech Ltd | Stripping of volatile substances from less volatile fluids |
| JP4710289B2 (en) * | 2004-09-22 | 2011-06-29 | 東亞合成株式会社 | Continuous removal method of organic volatile substances |
| JP5002930B2 (en) * | 2005-09-13 | 2012-08-15 | 東亞合成株式会社 | Method for producing low odor emulsion |
| JP2018182161A (en) | 2017-04-18 | 2018-11-15 | Tdk株式会社 | Magnet, magnet structure, and rotation angle detector |
| JP7306893B2 (en) | 2019-06-27 | 2023-07-11 | ダイキョーニシカワ株式会社 | display panel |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2467769A (en) * | 1946-06-22 | 1949-04-19 | Du Pont | Removal of volatile substances from aqueous dispersions of elastomeric materials |
| CA1011089A (en) * | 1973-03-26 | 1977-05-31 | Lawrence C. Baughman | Method of stripping volatile material from an aqueous dispersion of polymeric substance |
-
1975
- 1975-07-07 NL NL7508078A patent/NL7508078A/en not_active Application Discontinuation
- 1975-07-18 DE DE19752532264 patent/DE2532264A1/en active Pending
- 1975-07-24 GB GB3105875A patent/GB1466515A/en not_active Expired
- 1975-07-31 FR FR7524014A patent/FR2281946A1/en active Granted
- 1975-08-04 JP JP9492975A patent/JPS5141780A/en active Granted
- 1975-08-15 CA CA233,504A patent/CA1070879A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| NL7508078A (en) | 1976-02-18 |
| DE2532264A1 (en) | 1976-02-26 |
| FR2281946A1 (en) | 1976-03-12 |
| FR2281946B1 (en) | 1979-02-02 |
| JPS5141780A (en) | 1976-04-08 |
| JPS5212229B2 (en) | 1977-04-05 |
| GB1466515A (en) | 1977-03-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |