CA1081880A - Process and device for the manufacture of polymer dispersions with low monomer content - Google Patents
Process and device for the manufacture of polymer dispersions with low monomer contentInfo
- Publication number
- CA1081880A CA1081880A CA232,194A CA232194A CA1081880A CA 1081880 A CA1081880 A CA 1081880A CA 232194 A CA232194 A CA 232194A CA 1081880 A CA1081880 A CA 1081880A
- Authority
- CA
- Canada
- Prior art keywords
- vessel
- dispersion
- wall
- spray
- outlet
- 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F6/00—Post-polymerisation treatments
- C08F6/001—Removal of residual monomers by physical means
- C08F6/003—Removal of residual monomers by physical means from polymer solutions, suspensions, dispersions or emulsions without recovery of the polymer therefrom
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/16—Evaporating by spraying
-
- 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
- B01D3/06—Flash distillation
-
- 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
- B01D3/343—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances the substance being a gas
- B01D3/346—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances the substance being a gas the gas being used for removing vapours, e.g. transport gas
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J10/00—Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor
- B01J10/02—Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor of the thin-film type
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/18—Stationary reactors having moving elements inside
- B01J19/1868—Stationary reactors having moving elements inside resulting in a loop-type movement
- B01J19/1881—Stationary reactors having moving elements inside resulting in a loop-type movement externally, i.e. the mixture leaving the vessel and subsequently re-entering it
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
- B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
- B01J2219/00094—Jackets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
- B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
- B01J2219/00103—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor in a heat exchanger separate from the reactor
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
- Polymerisation Methods In General (AREA)
Abstract
PROCESS AND DEVICE FOR THE MANUFACTURE OF
POLYMER DISPERSIONS WITH LOW MONOMER CONTENT.
ABSTRACT OF THE DISCLOSURE:
Polymer dispersions are subjected to a spray treatment to reduce the monomer content thereof. The dispersions are sprayed against the wall of a vessel by means of at least one spray nozzle.
POLYMER DISPERSIONS WITH LOW MONOMER CONTENT.
ABSTRACT OF THE DISCLOSURE:
Polymer dispersions are subjected to a spray treatment to reduce the monomer content thereof. The dispersions are sprayed against the wall of a vessel by means of at least one spray nozzle.
Description
HOE 74/F ~,~
`~ ~08~880 This invention relates to a process and a device for a spray treatment of polymer dispersions to reduce the content of monomers thereof.
The monomer content of polymer dispersions should be as low as possible for various reasons. On the one hand, during storage of the dispersions the monomers still preæ~t~nreacti~un-controlled manner and thus detrimentally affect the properties of the dispersions and the coatings made therefrom. On the other hand, monomers evaporating with the water when the dis-persions are dried may be injurious to health. Especially in the processing of dispersions to obtain plastics p~wders~
for example in the industrial product~on of polyvinyl chloride, considerable monomer amounts escape with the drying air if the dispersions have a high monomer content, for example above 0.1 % by weight, which must be reduced because o~ environmental protection. Moreover, packing material for foodstuff made from ~
dispersions having a high monomer content may alter the odor and ~ -taste of the packed goods so that they may become unpalatable.
Various processes have been proposed to reduce the monomer content of aqueous polymer dispersions.
In general, the monomers are removed by pressure release of the polymerization mixture.
It is also known to free polymer dispersions of mor.omers by passing through steam or inert gases To this effect con-25 ~ siderable amounts of steam or gas are required which cause difficulties, above all in the case of dispersions tending to foam. The addition of defoamers increases the expenses, is not always effective and may detrimentally affect the properties of 29 the dispersions. To avoid the aforesaid difficulties it has
`~ ~08~880 This invention relates to a process and a device for a spray treatment of polymer dispersions to reduce the content of monomers thereof.
The monomer content of polymer dispersions should be as low as possible for various reasons. On the one hand, during storage of the dispersions the monomers still preæ~t~nreacti~un-controlled manner and thus detrimentally affect the properties of the dispersions and the coatings made therefrom. On the other hand, monomers evaporating with the water when the dis-persions are dried may be injurious to health. Especially in the processing of dispersions to obtain plastics p~wders~
for example in the industrial product~on of polyvinyl chloride, considerable monomer amounts escape with the drying air if the dispersions have a high monomer content, for example above 0.1 % by weight, which must be reduced because o~ environmental protection. Moreover, packing material for foodstuff made from ~
dispersions having a high monomer content may alter the odor and ~ -taste of the packed goods so that they may become unpalatable.
Various processes have been proposed to reduce the monomer content of aqueous polymer dispersions.
In general, the monomers are removed by pressure release of the polymerization mixture.
It is also known to free polymer dispersions of mor.omers by passing through steam or inert gases To this effect con-25 ~ siderable amounts of steam or gas are required which cause difficulties, above all in the case of dispersions tending to foam. The addition of defoamers increases the expenses, is not always effective and may detrimentally affect the properties of 29 the dispersions. To avoid the aforesaid difficulties it has
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.
HOE 74/F 9i6 also been proposed to destroy, by a rapid pressure reduction, the foam formed during the passage of steam at a speed of more than 100 m/sec, to separate the steam from the broken dis-persion foam and to add the foam to the boiling dispersion.
This process is carried out in continuous manner, the steam consumption is high and the expenditure pertaining to apparatus is considerable.
According to another kno~m process the dispersion is mixed with steam or hot inert gases in a tube and after a short period of time the three phase mixture is divided again into dispersion and gaseous phase. It has also been proposed to atomize polymer dispersions in steam flowing at a high speed, to pass the - -mixture between heated plates to a release zone where the dis-persion is separated from the gaseous phase in a cyclone~ The two latter processes are carried o~t continuously but also require high amounts of steam and considerable expenditure pert ining to apparatus. In spite of the high velocity of flow, thed~p~cn is easily overheated~ and coagulations and backing of the polymers on the walls of the apparatus may occur.
Moreover, monomers included in the polymer core, which require a certain diffusion time, are removed to an insufficient extent only. In most cases a prior degassing is necessary.
In another known process the dispersion is conducted in a tube in counter current flow with steam. In this case, too, 25 ~ the expenditure pertaining to apparatus is relatively high and with high passage rates dispersions with low surface tension start to foam. Moreover, deposits of solids may readily cause - clogging.
29 Finally, it has been proposed to spray the dispersion into _ 3 _ ~ ".~
``` -` 1C~8~880 a steam atmosphere in such a manner that the sprayed part-icles fall through the steam owing to gravity. For this process a large and relatively expensive vessel is required.
It is an object of the present invention to provide a continuous process for the removal of monomers from polymer dispersions using relatively inexpensive apparatus and a reduced energy consumption, and more particularly to provide a process and apparatus for the removal of monomers from dispersions which tend to foam and to form incrustations in parts of the apparatus, which are sensitive to shearing and high temperatures and which normally require a prolonged treatment time, for example more that 30 minutes, for a substantial removal of the monomers.
In one of its aspects the invention provides a process for the preparation of a polymer dispersion having a low monomer content in which at least one monomer in aqueous phase is subjected to emulsion or suspension polymeri-zation. The resultant dispersion is sprayed in a vertical vessel and onto the wall of the vessel in the form of a hollow cone or disk having a scattering angle of from 30 to 180 ~ degrees in the form of droplets having a diameter of at most 6 mm (measured by the method of Fraser-Eisenklam, Trans.
Instn. Chem. Engs., volume 34, pages 301-302 (1956) with a dispersion of 20C at atmospheric pressure). The dispersion ~25 is then allowed to run down the wall of the vessel and is collected at an outlet in the lower part of the vessel, and gaseous constituents are withdrawn above the outlet of the dispersion.
In another of its aspects the invention provides apparatus for use in the removal of at least one monomer from r~ 1 . .:. . , . : , , .
. ~ . . . . . . . . .. .
~ 08~880 an aqueous untreated polymer dispersion to provide a treated polymer dispersion. The apparatus includes a vessel having an inner wall which is symmetrical about a vertical axis, a gas outlet at the top of the vessel, and a further outlet at the bottom of the vessel for drawing off the polymer dispersion after treatment to remove the monomer. Spray means is positioned substantially at the vertical axis and adapted to spray the untreated polymer dispersion in droplets having a diameter of at most 6 mm generally radially in the form of a hollow cone or a disk having a scattering angle of from 30 to 180 degrees onto the lnner wall above a level where the treated polymer dispersion would collect before leaving the vessel through said further outlet. Means is also provided for delivering the untreated polymer dispersion with the monomer in aqueous phase to the spray means.
These and other aspects of the invention will be better understood with reference to the drawings, in which:
Fig. 1 is a somewhat diagrammatic sectional view of one embodiment of apparatus according to the invention and for use in a process according to the invention;
~ Figs. 2 and 3 are views similar to that shown in Fig. 1 and illustrating alternative embodiment~ of the structure;
Fig. 3a is a sectional view on line A-A of Fig.
. - , . . . .
.,: , : , . . : . .
.
HOE 74/F 9i6 also been proposed to destroy, by a rapid pressure reduction, the foam formed during the passage of steam at a speed of more than 100 m/sec, to separate the steam from the broken dis-persion foam and to add the foam to the boiling dispersion.
This process is carried out in continuous manner, the steam consumption is high and the expenditure pertaining to apparatus is considerable.
According to another kno~m process the dispersion is mixed with steam or hot inert gases in a tube and after a short period of time the three phase mixture is divided again into dispersion and gaseous phase. It has also been proposed to atomize polymer dispersions in steam flowing at a high speed, to pass the - -mixture between heated plates to a release zone where the dis-persion is separated from the gaseous phase in a cyclone~ The two latter processes are carried o~t continuously but also require high amounts of steam and considerable expenditure pert ining to apparatus. In spite of the high velocity of flow, thed~p~cn is easily overheated~ and coagulations and backing of the polymers on the walls of the apparatus may occur.
Moreover, monomers included in the polymer core, which require a certain diffusion time, are removed to an insufficient extent only. In most cases a prior degassing is necessary.
In another known process the dispersion is conducted in a tube in counter current flow with steam. In this case, too, 25 ~ the expenditure pertaining to apparatus is relatively high and with high passage rates dispersions with low surface tension start to foam. Moreover, deposits of solids may readily cause - clogging.
29 Finally, it has been proposed to spray the dispersion into _ 3 _ ~ ".~
``` -` 1C~8~880 a steam atmosphere in such a manner that the sprayed part-icles fall through the steam owing to gravity. For this process a large and relatively expensive vessel is required.
It is an object of the present invention to provide a continuous process for the removal of monomers from polymer dispersions using relatively inexpensive apparatus and a reduced energy consumption, and more particularly to provide a process and apparatus for the removal of monomers from dispersions which tend to foam and to form incrustations in parts of the apparatus, which are sensitive to shearing and high temperatures and which normally require a prolonged treatment time, for example more that 30 minutes, for a substantial removal of the monomers.
In one of its aspects the invention provides a process for the preparation of a polymer dispersion having a low monomer content in which at least one monomer in aqueous phase is subjected to emulsion or suspension polymeri-zation. The resultant dispersion is sprayed in a vertical vessel and onto the wall of the vessel in the form of a hollow cone or disk having a scattering angle of from 30 to 180 ~ degrees in the form of droplets having a diameter of at most 6 mm (measured by the method of Fraser-Eisenklam, Trans.
Instn. Chem. Engs., volume 34, pages 301-302 (1956) with a dispersion of 20C at atmospheric pressure). The dispersion ~25 is then allowed to run down the wall of the vessel and is collected at an outlet in the lower part of the vessel, and gaseous constituents are withdrawn above the outlet of the dispersion.
In another of its aspects the invention provides apparatus for use in the removal of at least one monomer from r~ 1 . .:. . , . : , , .
. ~ . . . . . . . . .. .
~ 08~880 an aqueous untreated polymer dispersion to provide a treated polymer dispersion. The apparatus includes a vessel having an inner wall which is symmetrical about a vertical axis, a gas outlet at the top of the vessel, and a further outlet at the bottom of the vessel for drawing off the polymer dispersion after treatment to remove the monomer. Spray means is positioned substantially at the vertical axis and adapted to spray the untreated polymer dispersion in droplets having a diameter of at most 6 mm generally radially in the form of a hollow cone or a disk having a scattering angle of from 30 to 180 degrees onto the lnner wall above a level where the treated polymer dispersion would collect before leaving the vessel through said further outlet. Means is also provided for delivering the untreated polymer dispersion with the monomer in aqueous phase to the spray means.
These and other aspects of the invention will be better understood with reference to the drawings, in which:
Fig. 1 is a somewhat diagrammatic sectional view of one embodiment of apparatus according to the invention and for use in a process according to the invention;
~ Figs. 2 and 3 are views similar to that shown in Fig. 1 and illustrating alternative embodiment~ of the structure;
Fig. 3a is a sectional view on line A-A of Fig.
3; and Figs. 4 and 5 are views similar to Fig. 1 and illustrating more embodiments incorporating the invention.
As seen in Fig. 1 apparatus is provided com-prising a vertical cylindrical vessel 1 with an outlet for liquid 2 in the lower part, a stirrer 4 and an outlet for the withdrawal of gas 5 in the upper part of the vessel.
_ 5 ., .. ,,, , ... ,, . . ,, .. , . , . ~ ~ , ~ . - .
~ HOE 74/F 916 ` -` 1081880 In the interior the vessel contains a spraying device in the form of a spxay nozzle 6 which sprays liquid against the wall of the vessel in the form of a hollow cone 7. If one substance nozzle is preferred such as that described `- 5 in Chemical Eng. Prog. volume 49 pages 185 - 186. Thisnozzle will give a sharply defined hollow cone.
. ~ .The level of the dispersion in the vessel is at such a height 8 that the surface of the dispersion is not hit by the sprayed-material. The dispersion is conveyed ,/ 10 to the spraying device by a pump 9 and heated by the means ,:
;~ of steam introduced through conduit 10. In a continuousprocess, untreated dispersion is supplied through conduit 3 and meets purified dispersion issuing from outlet 2. Part of this mixture is removed through conduit 15 and the remainder .~. .
lS continues on to the nozzle 6. The flow in conduit 3 is small compared with that in outlet 2 and the flow in conduit 15 ., .
is comparable to that in conduit 3. Consequently the degree of purification achieved will be related to the relative flow rates in outlet 2 and conduit 3.
In batch production the charge will be fed to ~ nozzle 6 while outlet 2 is closed. After the batch has ,., ; been fed through nozzle 6, the flow through conduit 3 will be stopped so that the purified dispersion can be collected from outlet 2.
; 25 In the embodiment shown in Fig. 2 the vessel 1 is provided with two outlets, one for the withdrawal of liquid 2, the other one for the removal of gases 5, and with a stirrer 4. The spraying device is composed of three nozzles 6a, one above the other, the cones of sprayed .,. .~ .
~ 30 material of whlch do not overlap and practically do not hit `; 1 , ,. . ` . . . . .
~ HOE 74/F 916 ---` 1081880 , the surface of the dispersion 8. Heated dispersion is -;; supplied through three conduits 31' 32 and 33, which may come from different stages of the process.
In the e~bodiment shown in Figure 3 the spraying device consists of four flat nozzles 6b producing together a hollow cone of sprayed material 7. The vessel 1 is provided with a jacket 11 through which a heating or cooling medium is circulated which is supplied through , conduit 20 and withdrawn through conduit 21.
In the embodiment represented in Figure 4 a ; .~
~ rotating spraying disk 12 is used as spraying device the , .
; axis of rotation 13 of which coincides with the axis of !' .
the vessel. The dispersion is supplied through conduit 14 and sprayed in the form of a disk 7.
The device shown in Figure 5 comprises a , . .
,, cylindrical vessel the lower part 1 of which has a smaller ; diameter than the upper part 25 and protrudes to a certain ;` extent into the upper part so that an annular groove 19 ` is formed from which the liquid is withdrawn through conduit 15. Both parts of the vessel are provided with a spraying ~ device 6a and 17, respectively, the cones of sprayed . .:
material emitted therefrom, 7 and 18, hitting the wall of the vessel above the level of the dispersion 8 and 19, , respectively. The gaseous products are withdrawn at the top of the vessel through conduit 5. The dispersion is fed to the spraying device 6a of the lower part of the vessel 'j through conduit 3, withdrawn at the bottom through conduit 2, .,, . :
pumped by pump 9 through a heat exchanger 24 and supplied ~,......................................................................... .
~ to the upper spraying device through conduit 16. The treated , ;, , dispersion is discharged through conduit 15. The upper r`~
;,,.:: - - - - .. ~ . . . .. . . . .. .. . . . .
---" 1081880 section of the vessel is provided with a jacket 11 through which a liquid heating or cooling medium is circulated ; which is introduced through conduit 20 and discharged through conduit 21. Numerals 22 and 23 indicate the inlet and outlet for the heating medium for heat exchanger 24.
' The following examples illustrate the invention.
E X A M P L E 1:
. .
, In a device as shown in Figure 3 with a vessel having a diameter of 1.4 meters and a height of 2.8 meters , 1,500 kg of an aqueous dispersion, prepared by continuous emulsion polymerization and containing 45% by weight of polyvinyl chloride (K value 78) and 0.8% by weight of monomeric vinyl chloride, were sprayed per hour through 4 flat nozzles spraying the material in the form of a hollow cone with a scattering angle of 120. The co~ditions a~d results arè
,~ listed in the following table. The gaseous vinyl chloride was discharged at the head of the vessel, recovered, subjected to the usual purification and recycled into the polymerization.
~ 20 The treated dispersion was discharged at the bottom of the ,$
'l - vessel. No heating or cooling medium was circulated through the jacket of the vessel.
When processed on a calander into a rigid sheet the pulverulent polyvinyl chloride obtained after drying had the same processing properties as a powder made from ; an untreated dispersion.
,il E X A M P L E 2:
In the device as used in Example 1, 1,500 kg of an aqueous dispersion prepared by continuous emulsion polymerization and having a content of 45~i by weight of poly-j.
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, vinyl chloride (K value 59) and 0.6% by weight of monomeric vinyl chloride were sprayed per hour, the treated dispersion was discharged at the bottom of the vessel and the gaseous ' vinyl chloride at the head. Through the jacket a heating medium of 70C was circulated.
When processed on an extruder into rigid profiles the polyvinyl chloride powder obtained after drying had the same properties as a powder obtained from an untreated dispersion.
E X A M P L E 3:
.. ..
;~ A device as shown in Figure 5 having the ; following dimensions was used: lower part of vessel 1 diameter 2 m, height 6 m, upper part of vessel 25 diameter 2.5 m, ;.i : height 5m.6,300 kg per hour of aqueous dispersion, prepared ; 15 by continuous emulsion polymerization containing 4~ by weight of monomeric vinyl chloride and 42% by weight of ", .
sl vinyl chloride/butadiene!acrylonitrile copolymer with 93~ by weight of polymerized vinyl chloride were sprayed in the lower part with an excenter nozzle (6a) under a spraying 1:
angle of 90, the dispersion collected at the bottom of the ~ vessel~was discharged, transported over pump 9 into heat exchanger 24 and then sprayed again in the upper part by means of a nozzle 17 forming a hollow cone of the material with a scattering angle of 90. The jacket 11 of the vessel was heated to 70C by a liquid medium. The data are indicated in the following table.
.. .
I The gaseous vinyl chloride escaping at the . ~ .
head of the vessel was passed to a recovery plant. The -~
treated dispersion was withdrawn from the collecting groove -., - : .
~ 30 19 through conduit 15.
3"'~ .
9 - .
~C~81~80 E X A M P L E 4:
A device as shown in Figure 1 was used having a diameter of 3 m and a height of 10 m. 10 m3 of an aqueous dispersion, prepared by suspension poly-merization and having a content of 33% by weight vinyl chloride (K value 55) were introduced per hour into the cycle system through conduit 3 and heated together with treated dispersion discharged through conduit 2 to 75C
by steam having a pressure of up to 1.5 atmospheres intro-i 10 duced through conduit 10. By means of a p~mp 9 the heated s~ dispersion was fed to the spraying nozzle spraying the dispersion in the form of a hollow cone with a scattering angle of 90. Through conduit 15, 10 m of treated dispersion were discharged per hour. In the vessel the amount of dispersion was kept constant at about 20 m3. The data are , also indicated in the following table.
E X A M P L E S 5 to 7:
The treatment was carried out as described in ~ Example 4 with the exception that20 m of dispersion were ;, 20 supplied and withdrawn per hour and the pressure in the vessel and the inlet temperature were varied as indicated ', in the table . ... .
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-` 108~880 - The vessel used in accordance with the invention can be composed of two or more superimposed cylindrical parts, in which case the lower part having a smaller diameter projects concentrically into the upper part having a larger diameter (cf. Figure 5 of the drawing).
The ring-shaped groove formed should have at least one outlet for the liquid. Each of the cylindrical parts can be provided with a spraying device which can be connected in such a manner that the treatment can be carried out in one vessel in several successive stages. Also the vessels can be used in series.
The wall of the vessel can be provided with -heating or cooling means over its entire surface or over parts theréof, for example a jacket through which a liquid heating or cooling medium is circulated. It may be advantageous to heat or cool the wall of the vessel in the areas in which it is hit internally by the sprayed dispersion. It may be suitable to equip the vessel with stirring means for the contents and to provide for one or several gas inlets.
To spray the dispersion there is preferably ~
, ~ used at least one spray nozzle emitting the spray in the - -form of a hollow cone which is mounted in the upper part of the vessel in such a manner that the axis of the hollow cone ; of sprayed material is approximately congruent with the axis of the vessel. The material is preferably sprayed in downward direction.
The scattering angle of the hollow cone ! i.e.
; the angle between two opposite surface lines of the cone of sprayed material should be in the range of from 30 to 180, ` 30 that is to say the material can also be sprayed in the form , .
~ 13 _ ., - . . .. . : ~.: . .. . - . - :
of a horizontal disk. A scattering angle of from 80 to 120 is preferably chosen.
In the nozzle the most narrow cross sectional area for the passage of the dispersion should correspond to about two times the diameter of the solid particles in the dispersion. In general, a free cross section of the passage ~ area of at least 1 mm will be chosen for capacity reasons, a '; cross section of the passage area of from 5 to 100 and more advantageously from 10 to 50 mm being preferred.
The spray nozzle should spray the dispersion in such a manner that the largest droplets have a diameter of at most 6 mm. Especially good results are obtained when the average size of the droplets, determined as described above with a dispersion of 20C at atmospheric pressure, is in the range of from 0.05 to 3 mm.
The issuing speed of the droplets from the spray nozzle, determined by the method of H.Hege, Aufbereitung-i,~ stechnik 1969, pages 142 - 143, is preferably in the range ,,~ of from 5 to 250 m/sec., more preferably 10 to 100 m/sec.
,. . .
, 20 After having left the spray nozzle and before ~J'~' hitting the wall of the vessel the droplets should cover a .
distance of at least 20 cm. The largest distance which is at most 400 cm is determined by economical considerations with regard to the dimensions of the vessel and by the size and issuing speed of the droplets, a distance in the range of from 40 to 200 cm being preferred.
After having hit the wall of the vessel the .;
, droplets form a thin layer which flows downward, collects :
in the lower part of the vessel and is withdrawn through an ~i 30 outlet. The level of the liquid in the vessel, which may . j .
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~ -`` 1081880 be stirred, should be regulated in such a manner that at most a minor proportion, for example less than 5~ by weight, . of the sprayed dispersion strikes the surface of the liquid.
One half or more of the vessel can be filled with dispersion and simultaneously it may serve as a collecting and homogen-izing vessel. In general, the level of the dispersion in the j vessel will not be too high, since the sprayed dispersion, while running down the wall of the vessel, is additionally degassed and with a high level of the dispersion the danger increases that sprayed droplets directly fall on the surface of the dispersion. It is expedient to choose a level of the dispersion in the vessel of about 1/10 to 1/2 of the total ' inner height of the vessel. To have space for a large amount of dispersion in a vessel having a relatively small total volume without too high a liquid level the upper p~rt of the vessel may have a smaller diameter, for example 1/4 to 3/4 of the diameter of the lower part. To improve the degassing ~ effect the dispersion is preferably heated prior to spraying ; to a temperature of from 50 to 150C, more preferably 70 to 100C.
~ Heating of the dispersion in the container can be effected by a heatable jacket or by introducing steam into the dispersion. In the latter case, the total amount of steam should condense in the liquid and the liquid should ,~ 25 not start to boil.
It is expedient to maintain in the vessel a pressure above the saturation pressure of steam above the dispersion collected in the lower part of the vessel. In general, the pressure should be not more than 200 mm Hg, preferably not more than 100 mm Hg below the saturation .. .: . : .~ , ... : ., : -, ,. . ::
, '. ,' ' ' , ~ , ' .. :. . ., ' .. : ',: , .. ,,, .. ~ ~ . . . .
~ ` 1081880 pressure of the steam in the sprayed dispersion. It can ; also be equal to the saturation pressure of the steam of the sprayed dispersion or exceed that value by at most 500 mm Hg. During the prolonged period of treatment, which is often required to remove the monomers larger ; amounts of`water should not evaporate with the monomer(s) in order not to reduce unnecessarily the economy of the process, not to thicken the dispersion to an undesired ~ extent and not to deteriorate the quality of the final P 10 product. In general, the dispersion has a satifactory ~' content of residual monomer with an evaporated amount of water of from 0.2 to 5 kg for 100 kg of dispersion. In some -, cases, it may, however, be expedient to evaporate more '~ than 5 kg water for 100 kg dispersion.
;~; 15 The pressure necessary for spraying the ~I dispersion can be produced by a pump or other suitable means.
.. .
It is also possible, however, directly to spray the dispersion under pressure originating from the polymerization.
;~ Prior to spraying the dispersion can be heated ,, ., 20 either indirectly in the conduit to the spray nozzle, for ~ example by a heat exchanger, or directly by introducing steam. In the latter case, at most a minor amount of a ~.t gaseous phase-, for example less than 5% by volume, should ` be formed. The proportion of the gaseous phase should be ~- 25 as low as possible.
The process of the invention can be carried out in one or several series connected vessels. The sprayed dispersion is collected and passed again through the spraying device of the same vessel or preferably to the spray-2'~ 30 ing device of a following vessel. In certain cases it may iq~ 16 -.. ....
. .~ , : ~ , -.
, : : . : , ' .
,~, be of advantage partially to recycle the dispersion in the same vessel and to pass the rema~nder to the following vessel. The series-connected vessels can be mounted one beside or one above the other with the gas spaces of the S individual vessel expediently being separated from one another.
The vapors escaping during the spraying of the dispersion are withdrawn through an opening above the spraying device, condensed and optionally recycled to a recovery plant for the monomers. To i~prove the removal of volatile constituents from the dispersion inert gases can be introduced into the gas space of the vessel in which the dispersion is sprayed, for example air, nitrogen, or preferably optionally superheated steam. When the dispersion is treated in several series connected vessels the consumption of the lS inert gas can be reduced by passing the gaseous constituents removed from the vessels in countercurrent flow to the dispersion from vessel to vessel.
Besldes the spraying device described above other modes of construction may also be used, for example an arrangement of a plurality of nozzles one above the other on -- the axis of the container and each producing a hollow cone of sprayed material with as little as possible overlapping ; of the individual spray cones (cf. Figure 2 of the drawing), or an arrangement of at least 2 and preferably 3 to 12 nozzles on a concentric ring around the axis of the vessel emitting flat rays in the shape of circle sectors which hit equally large portions of the opposite wall under equal angles of from 15 to 90, preferably 40 to 60 (cf. Figure 3).
It is likewise possible to use a rotating disk as spraying device, the axis of rotation of which is . ~, .
~ ~ - 17 -" . , .~ ' . ' ': ' .
':' ' . . : , . ,, .. .: , ' . . ' .
-- 3.08~880 ; congruent with the axis of the vessel (cf. Figure 4). The process of the invention can be combined with other processes for the removal of monomers from dispersions. It can be . _ .
used with special advantage in all cases where foaming problems occur, especially when relatively large amounts of gas escape from dispersions tending to foam.
The process of the invention is reliable and permits the simple production of dispersions of low monomer content, for example less than 0.03% by weight or with repeated spraying even far iess, in many cases with the equipment already present by mounting little expensive additional installations. By spraying the particles of the dispersion onto the optionally heated wall of the vessel a very good degassing effect is obtained without detrimental foam formation. It is particularly advantageous that up ; to 10% by weight, calculated on the dispersion, of larger particles having a diameter of up to 5 mm do not cause any ~ ':
? trouble.
The treated dispersions can be used as such 20 or they can be further processed to obtain the solid polymer ~ by a known process, optionally after centrifugation or another ; method of concentration, for example by spray, conveying or contact drying, without the drying air being polluted by residual monomers.
;~ 2~ The process of the invention has little effect ~ on the properties of the dispersions. The~dispersions as well J~ as the dry polymers made therefrom can be used in the usual manners and in this case, too, troubles caused by the monomer(s) do not occur or are substantially done away with.
The treatment according to the present invention is `~ D
,, : .
- . . ..
-.
especially suitable for polymer dispersions which are sensi~ive to shearing forces and elevated temperature, tend to foam and ~orm incrustations i~ the apparatus and difficultly ~ive off - the monomers, for example polystyrene or styrene copolymer dispersionsor dispersions produced by emulsion or suspension polymerization of polyvinyl chloride and its copolymers and graft polymers containing up to 30 % by weight of comonomers, preferably up to 20 ~ by weight.
The vinyl chloride homo-, graft- or copolymer dispersions to be treated according to the present invention can be pre-pared by continuous or discontinuous polymerization processes with or without the use of a seedy polymer. The polymers are prepared in aqueous emulsion suspension in the presence of from 0.001 to 3 % by weight, preferably from 0.01 to 0.3 % by ~5 weight, calculated on the monomers, of the usual free radical forming catalysts, for example diaryl anddiacyl peroxides such as diacetyl, acetyl-benzoyl, dilauroyl, dibenzoyl, bis-2,4-di-chloro-benzoyl and bis-2-methyl-benzoyl peroxides; dialkyl per-oxides such as di-tert.butyl peroxide; per-esters such as tert.
` 20 butyl percarbonate, tert.butyl peracetate, tert.butyl peroctoate ~- and tert.butyl perpivalate; dialkyl peroxy dicarbonates such as l diisopropylj diethyl-hexyl, dicyclohexyl and diethylcyclohexyl peroxy dicarbonates; mixed anhydrides of organic sulfo-peracids and organic acids such as acetylcyclohexyl-sulfonyl peroxide;
and azo compounds used as polymerization catalysts such as azo- -isobutyronitrile; persulfates, for example potassium, sodium and ammonium persulfates; hydrogen peroxide, tert.butyl hydro-peroxide and other water-soluble peroxides, as well as mixtures 29 of different catalysts. The peroxidic catalysts can also be .-- 19 --D~
. ~ . . . . . , . . . .. . ... . ~ .
.. .. . . ..... .. . .~. .. . .; ~ .
. . .. . . . ~ .... ... . . ... .
1~81880 used in the presence of from 0.01 to 1 % by weight, calculated on the monomers, of at least one reducing substance suitable for the synthesis of a redox catalyst system, for example ~ sulfites, bisulfites, dithionites, thiosulfates, and aldehyde sulfoxylates, for example formaldehyde sulfoxylate. The poly-merization can also be carried out in the presence of soluble metal salts, for example of copper, silver, iron, or chromium, in amounts of from 0.05 to 10 ppm., calculated as metal on the monomer(æ).
The polymerization can also be carried out in the pre-sence of from 0.01 to 1 % by weight, preferably from 0.05 to 0.3 % by weight, calculated on the monomers, of at least one of the usual protective colloids, for example polyvinyl al-¢ohols which may contain up to 40 mole % of acetyl groups;
cellulose derivatives such as water-soluble methyl cellulose, carboxymethyl cellulose and hydroxyethyl cellulose; gelatin;
copolymers of maleic acid or the semi-esters thereof; styrenes;
polyvinyl pyrrolidone; and copolymers of vinyl acetate and ~inyl pyrrolidone.
The polymerization can also be carried out in the presence . .
of from 0.0~ to 5 % by weight, calculated on the monomers, of one or more emulsifiers which may be used in admixture with the above protective colloids. Suitable emulsifiers, which may be anionic, amphoteric, cationic, or non-ionic are, for 25~ example, alkali and alkaline earth metal and ammonium salts of fatty acids, for example of lauric, pal~itic or stearic acid, of acid fatty alcohol sulfuric acid esters, paraffin sulfonic acids, alkylaryl sulfonic acids such as dodecylbenzene or 29 dibutyl-naphthalene sulfonic acid, of sulfo-succinic acid _ 20 -- - -: . . :
.
5 ' ' `
,, i HOE 74/F 916 `` ~081880 .
~ialkyl esters, as well as the alkali metal and ammonium salts --of fatty acids containing epoxide groups, such as epoxy-stearic acid, of reaction products of per-acids, for example per-acetic acid with unsaturated fatty acids such as oleic acid or linoic acid, or unsaturated hydroxyl derivatives of fatty acids such as ricinoleic acid. Suitable amphoteric or cationic emulsifiers ; are, for example, alkyl betains, such as dodecyl betain, as well as alkyl pyridinium salts such as lauryl pyridinium hydro-chloride; and alkyl ammonium salts such as oxethyl dodecyl ammonium chloride. Suitable non-ionic emulsifiers are, for example, partial fatty acid esters of polyhydric alcohols such as glycerol monostearate, sorbitol monostearate, sorbitol mono-laurate, oleate, or palmitate~ polyhydroxy ethylene ethers of fatty alcoholi~ or aromatic hydroxy compounds, polyoxethylene esters of fatty acids and polypropylene oxide-polyethylene oxide condensation products.
Besides the catalysts, protective colloids and/or emul-sifiers, the polymerization mixture may also contain buffer ~ubstances, for example alkali ~etal acetates, borax, alkal~
metal phosphates, alkali metal ¢arbonates, ammonia, or ammonium ~_ salts of carboxylic acids; and moleculi~r weig~t regulators, .~ .
for example aliphatic aldehydes having from 2 to 4 carbon atoms, chioro- and bromo-hydrocarbons, for example di- and trichloro-ethylene, chloroform, bromoform and methylene chloride, and mercaptans.
Suitable polymerization auxiliaries ~or making the vinyl chloride polymers to be used are described, for example in "Polyvinylchlorid und Vinylchlorid-Misch-polymerisate" by 29 H.Kainer,Springer Verlag, Berlin/Heidelberg/New York, 1965, ~; :
.i , .
. .
'' ,~il. ~
` ` ~081880 NOE 74/F 916 :
pages ~3 - 59.
For copolymerization with vinyl chloride, one or more of the following monomers can be used; olefins such as ethylene - or propylene; vinyl esters of linear or branched carboxylic - 5 acids having from 2 to 20 carbon atoms, preferably 2 to 4 carbon atoms, for example vinyl acetate, propionate, butyrate and 2-ethylhexoate; vinyl-isotridecanoic acid esters; vinyl halides, for example vinyl fluoride, vinylidene fluoride, vinylidene chloride; vinyl ethers; vinyl pyridine; unsaturated acids such as maleic, fumaric, acrylic and methacrylic acid and the mono and diesters thereof with mono- and di-alcohols having from 1 to 10 carbon a~oms; maleic anhydride; maleic imide and the N-substitution products thereof ~ith aromatic, cyclo-aliphatic and optionally branched aliphatic substituents;
acrylonitrile; and s*rene.
~or graft polymerization, elastomeric polymers can be used, which are obtained by polymerizing one or more of the following 3 monomers: dienes, for example butadiene and cyclopentadiene;
olefins such as ethylene and propylene; styrene; unsaturated !
~ 20 acids such as acrylic and methacrylic acids and the esters `;~~ théreof with mono- and dialcohols having from 1 to 10 carbon atoms; acrylonitrile; vinyl compounds, for example vinyl esters of linear and branched carboxylic acids having from 2 to 20 and preferably from 2 to 4 carbon atoms; and vinyl halides such as vinyl chloride and vinylidene chloride.
: s After the polymerization, further substances for stabi-lizing or improving the processing properties can be added to ; the aqueous polymer dispersion. In special cases known anti-29 - foaming agents may be added although this is generally not . ,~ ' : . ' ' ' ' , ' ' , ~' ' ' ' ' . ' ' ' , ' ,' ' ' ' ' 81880 ~
necessary.
A particularly advantageous form of nozzle is known as an eccentric spray nozzle. This nozzle receives ~ the dispersion to be sprayed tangentially on a circle lying vertically with respect to the centre axis of the nozzle.
The flow follows a spiral path in the direction of the nozzle axis until the nozzle outlet permits discharge vertically with respect to the rotary motion of the dlspersion.
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As seen in Fig. 1 apparatus is provided com-prising a vertical cylindrical vessel 1 with an outlet for liquid 2 in the lower part, a stirrer 4 and an outlet for the withdrawal of gas 5 in the upper part of the vessel.
_ 5 ., .. ,,, , ... ,, . . ,, .. , . , . ~ ~ , ~ . - .
~ HOE 74/F 916 ` -` 1081880 In the interior the vessel contains a spraying device in the form of a spxay nozzle 6 which sprays liquid against the wall of the vessel in the form of a hollow cone 7. If one substance nozzle is preferred such as that described `- 5 in Chemical Eng. Prog. volume 49 pages 185 - 186. Thisnozzle will give a sharply defined hollow cone.
. ~ .The level of the dispersion in the vessel is at such a height 8 that the surface of the dispersion is not hit by the sprayed-material. The dispersion is conveyed ,/ 10 to the spraying device by a pump 9 and heated by the means ,:
;~ of steam introduced through conduit 10. In a continuousprocess, untreated dispersion is supplied through conduit 3 and meets purified dispersion issuing from outlet 2. Part of this mixture is removed through conduit 15 and the remainder .~. .
lS continues on to the nozzle 6. The flow in conduit 3 is small compared with that in outlet 2 and the flow in conduit 15 ., .
is comparable to that in conduit 3. Consequently the degree of purification achieved will be related to the relative flow rates in outlet 2 and conduit 3.
In batch production the charge will be fed to ~ nozzle 6 while outlet 2 is closed. After the batch has ,., ; been fed through nozzle 6, the flow through conduit 3 will be stopped so that the purified dispersion can be collected from outlet 2.
; 25 In the embodiment shown in Fig. 2 the vessel 1 is provided with two outlets, one for the withdrawal of liquid 2, the other one for the removal of gases 5, and with a stirrer 4. The spraying device is composed of three nozzles 6a, one above the other, the cones of sprayed .,. .~ .
~ 30 material of whlch do not overlap and practically do not hit `; 1 , ,. . ` . . . . .
~ HOE 74/F 916 ---` 1081880 , the surface of the dispersion 8. Heated dispersion is -;; supplied through three conduits 31' 32 and 33, which may come from different stages of the process.
In the e~bodiment shown in Figure 3 the spraying device consists of four flat nozzles 6b producing together a hollow cone of sprayed material 7. The vessel 1 is provided with a jacket 11 through which a heating or cooling medium is circulated which is supplied through , conduit 20 and withdrawn through conduit 21.
In the embodiment represented in Figure 4 a ; .~
~ rotating spraying disk 12 is used as spraying device the , .
; axis of rotation 13 of which coincides with the axis of !' .
the vessel. The dispersion is supplied through conduit 14 and sprayed in the form of a disk 7.
The device shown in Figure 5 comprises a , . .
,, cylindrical vessel the lower part 1 of which has a smaller ; diameter than the upper part 25 and protrudes to a certain ;` extent into the upper part so that an annular groove 19 ` is formed from which the liquid is withdrawn through conduit 15. Both parts of the vessel are provided with a spraying ~ device 6a and 17, respectively, the cones of sprayed . .:
material emitted therefrom, 7 and 18, hitting the wall of the vessel above the level of the dispersion 8 and 19, , respectively. The gaseous products are withdrawn at the top of the vessel through conduit 5. The dispersion is fed to the spraying device 6a of the lower part of the vessel 'j through conduit 3, withdrawn at the bottom through conduit 2, .,, . :
pumped by pump 9 through a heat exchanger 24 and supplied ~,......................................................................... .
~ to the upper spraying device through conduit 16. The treated , ;, , dispersion is discharged through conduit 15. The upper r`~
;,,.:: - - - - .. ~ . . . .. . . . .. .. . . . .
---" 1081880 section of the vessel is provided with a jacket 11 through which a liquid heating or cooling medium is circulated ; which is introduced through conduit 20 and discharged through conduit 21. Numerals 22 and 23 indicate the inlet and outlet for the heating medium for heat exchanger 24.
' The following examples illustrate the invention.
E X A M P L E 1:
. .
, In a device as shown in Figure 3 with a vessel having a diameter of 1.4 meters and a height of 2.8 meters , 1,500 kg of an aqueous dispersion, prepared by continuous emulsion polymerization and containing 45% by weight of polyvinyl chloride (K value 78) and 0.8% by weight of monomeric vinyl chloride, were sprayed per hour through 4 flat nozzles spraying the material in the form of a hollow cone with a scattering angle of 120. The co~ditions a~d results arè
,~ listed in the following table. The gaseous vinyl chloride was discharged at the head of the vessel, recovered, subjected to the usual purification and recycled into the polymerization.
~ 20 The treated dispersion was discharged at the bottom of the ,$
'l - vessel. No heating or cooling medium was circulated through the jacket of the vessel.
When processed on a calander into a rigid sheet the pulverulent polyvinyl chloride obtained after drying had the same processing properties as a powder made from ; an untreated dispersion.
,il E X A M P L E 2:
In the device as used in Example 1, 1,500 kg of an aqueous dispersion prepared by continuous emulsion polymerization and having a content of 45~i by weight of poly-j.
~ 8 -, . . : . , : ~ . .. .
.. . , ,: ~ . , , . ~ :
, vinyl chloride (K value 59) and 0.6% by weight of monomeric vinyl chloride were sprayed per hour, the treated dispersion was discharged at the bottom of the vessel and the gaseous ' vinyl chloride at the head. Through the jacket a heating medium of 70C was circulated.
When processed on an extruder into rigid profiles the polyvinyl chloride powder obtained after drying had the same properties as a powder obtained from an untreated dispersion.
E X A M P L E 3:
.. ..
;~ A device as shown in Figure 5 having the ; following dimensions was used: lower part of vessel 1 diameter 2 m, height 6 m, upper part of vessel 25 diameter 2.5 m, ;.i : height 5m.6,300 kg per hour of aqueous dispersion, prepared ; 15 by continuous emulsion polymerization containing 4~ by weight of monomeric vinyl chloride and 42% by weight of ", .
sl vinyl chloride/butadiene!acrylonitrile copolymer with 93~ by weight of polymerized vinyl chloride were sprayed in the lower part with an excenter nozzle (6a) under a spraying 1:
angle of 90, the dispersion collected at the bottom of the ~ vessel~was discharged, transported over pump 9 into heat exchanger 24 and then sprayed again in the upper part by means of a nozzle 17 forming a hollow cone of the material with a scattering angle of 90. The jacket 11 of the vessel was heated to 70C by a liquid medium. The data are indicated in the following table.
.. .
I The gaseous vinyl chloride escaping at the . ~ .
head of the vessel was passed to a recovery plant. The -~
treated dispersion was withdrawn from the collecting groove -., - : .
~ 30 19 through conduit 15.
3"'~ .
9 - .
~C~81~80 E X A M P L E 4:
A device as shown in Figure 1 was used having a diameter of 3 m and a height of 10 m. 10 m3 of an aqueous dispersion, prepared by suspension poly-merization and having a content of 33% by weight vinyl chloride (K value 55) were introduced per hour into the cycle system through conduit 3 and heated together with treated dispersion discharged through conduit 2 to 75C
by steam having a pressure of up to 1.5 atmospheres intro-i 10 duced through conduit 10. By means of a p~mp 9 the heated s~ dispersion was fed to the spraying nozzle spraying the dispersion in the form of a hollow cone with a scattering angle of 90. Through conduit 15, 10 m of treated dispersion were discharged per hour. In the vessel the amount of dispersion was kept constant at about 20 m3. The data are , also indicated in the following table.
E X A M P L E S 5 to 7:
The treatment was carried out as described in ~ Example 4 with the exception that20 m of dispersion were ;, 20 supplied and withdrawn per hour and the pressure in the vessel and the inlet temperature were varied as indicated ', in the table . ... .
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-` 108~880 - The vessel used in accordance with the invention can be composed of two or more superimposed cylindrical parts, in which case the lower part having a smaller diameter projects concentrically into the upper part having a larger diameter (cf. Figure 5 of the drawing).
The ring-shaped groove formed should have at least one outlet for the liquid. Each of the cylindrical parts can be provided with a spraying device which can be connected in such a manner that the treatment can be carried out in one vessel in several successive stages. Also the vessels can be used in series.
The wall of the vessel can be provided with -heating or cooling means over its entire surface or over parts theréof, for example a jacket through which a liquid heating or cooling medium is circulated. It may be advantageous to heat or cool the wall of the vessel in the areas in which it is hit internally by the sprayed dispersion. It may be suitable to equip the vessel with stirring means for the contents and to provide for one or several gas inlets.
To spray the dispersion there is preferably ~
, ~ used at least one spray nozzle emitting the spray in the - -form of a hollow cone which is mounted in the upper part of the vessel in such a manner that the axis of the hollow cone ; of sprayed material is approximately congruent with the axis of the vessel. The material is preferably sprayed in downward direction.
The scattering angle of the hollow cone ! i.e.
; the angle between two opposite surface lines of the cone of sprayed material should be in the range of from 30 to 180, ` 30 that is to say the material can also be sprayed in the form , .
~ 13 _ ., - . . .. . : ~.: . .. . - . - :
of a horizontal disk. A scattering angle of from 80 to 120 is preferably chosen.
In the nozzle the most narrow cross sectional area for the passage of the dispersion should correspond to about two times the diameter of the solid particles in the dispersion. In general, a free cross section of the passage ~ area of at least 1 mm will be chosen for capacity reasons, a '; cross section of the passage area of from 5 to 100 and more advantageously from 10 to 50 mm being preferred.
The spray nozzle should spray the dispersion in such a manner that the largest droplets have a diameter of at most 6 mm. Especially good results are obtained when the average size of the droplets, determined as described above with a dispersion of 20C at atmospheric pressure, is in the range of from 0.05 to 3 mm.
The issuing speed of the droplets from the spray nozzle, determined by the method of H.Hege, Aufbereitung-i,~ stechnik 1969, pages 142 - 143, is preferably in the range ,,~ of from 5 to 250 m/sec., more preferably 10 to 100 m/sec.
,. . .
, 20 After having left the spray nozzle and before ~J'~' hitting the wall of the vessel the droplets should cover a .
distance of at least 20 cm. The largest distance which is at most 400 cm is determined by economical considerations with regard to the dimensions of the vessel and by the size and issuing speed of the droplets, a distance in the range of from 40 to 200 cm being preferred.
After having hit the wall of the vessel the .;
, droplets form a thin layer which flows downward, collects :
in the lower part of the vessel and is withdrawn through an ~i 30 outlet. The level of the liquid in the vessel, which may . j .
~ 14 -... ....... . . . . . .
- . . - ~ , . .
. ~ ~.: :.: .
,.' ' ' : .'1`"'~' ' ' ,~,.- ;, . .
~ -`` 1081880 be stirred, should be regulated in such a manner that at most a minor proportion, for example less than 5~ by weight, . of the sprayed dispersion strikes the surface of the liquid.
One half or more of the vessel can be filled with dispersion and simultaneously it may serve as a collecting and homogen-izing vessel. In general, the level of the dispersion in the j vessel will not be too high, since the sprayed dispersion, while running down the wall of the vessel, is additionally degassed and with a high level of the dispersion the danger increases that sprayed droplets directly fall on the surface of the dispersion. It is expedient to choose a level of the dispersion in the vessel of about 1/10 to 1/2 of the total ' inner height of the vessel. To have space for a large amount of dispersion in a vessel having a relatively small total volume without too high a liquid level the upper p~rt of the vessel may have a smaller diameter, for example 1/4 to 3/4 of the diameter of the lower part. To improve the degassing ~ effect the dispersion is preferably heated prior to spraying ; to a temperature of from 50 to 150C, more preferably 70 to 100C.
~ Heating of the dispersion in the container can be effected by a heatable jacket or by introducing steam into the dispersion. In the latter case, the total amount of steam should condense in the liquid and the liquid should ,~ 25 not start to boil.
It is expedient to maintain in the vessel a pressure above the saturation pressure of steam above the dispersion collected in the lower part of the vessel. In general, the pressure should be not more than 200 mm Hg, preferably not more than 100 mm Hg below the saturation .. .: . : .~ , ... : ., : -, ,. . ::
, '. ,' ' ' , ~ , ' .. :. . ., ' .. : ',: , .. ,,, .. ~ ~ . . . .
~ ` 1081880 pressure of the steam in the sprayed dispersion. It can ; also be equal to the saturation pressure of the steam of the sprayed dispersion or exceed that value by at most 500 mm Hg. During the prolonged period of treatment, which is often required to remove the monomers larger ; amounts of`water should not evaporate with the monomer(s) in order not to reduce unnecessarily the economy of the process, not to thicken the dispersion to an undesired ~ extent and not to deteriorate the quality of the final P 10 product. In general, the dispersion has a satifactory ~' content of residual monomer with an evaporated amount of water of from 0.2 to 5 kg for 100 kg of dispersion. In some -, cases, it may, however, be expedient to evaporate more '~ than 5 kg water for 100 kg dispersion.
;~; 15 The pressure necessary for spraying the ~I dispersion can be produced by a pump or other suitable means.
.. .
It is also possible, however, directly to spray the dispersion under pressure originating from the polymerization.
;~ Prior to spraying the dispersion can be heated ,, ., 20 either indirectly in the conduit to the spray nozzle, for ~ example by a heat exchanger, or directly by introducing steam. In the latter case, at most a minor amount of a ~.t gaseous phase-, for example less than 5% by volume, should ` be formed. The proportion of the gaseous phase should be ~- 25 as low as possible.
The process of the invention can be carried out in one or several series connected vessels. The sprayed dispersion is collected and passed again through the spraying device of the same vessel or preferably to the spray-2'~ 30 ing device of a following vessel. In certain cases it may iq~ 16 -.. ....
. .~ , : ~ , -.
, : : . : , ' .
,~, be of advantage partially to recycle the dispersion in the same vessel and to pass the rema~nder to the following vessel. The series-connected vessels can be mounted one beside or one above the other with the gas spaces of the S individual vessel expediently being separated from one another.
The vapors escaping during the spraying of the dispersion are withdrawn through an opening above the spraying device, condensed and optionally recycled to a recovery plant for the monomers. To i~prove the removal of volatile constituents from the dispersion inert gases can be introduced into the gas space of the vessel in which the dispersion is sprayed, for example air, nitrogen, or preferably optionally superheated steam. When the dispersion is treated in several series connected vessels the consumption of the lS inert gas can be reduced by passing the gaseous constituents removed from the vessels in countercurrent flow to the dispersion from vessel to vessel.
Besldes the spraying device described above other modes of construction may also be used, for example an arrangement of a plurality of nozzles one above the other on -- the axis of the container and each producing a hollow cone of sprayed material with as little as possible overlapping ; of the individual spray cones (cf. Figure 2 of the drawing), or an arrangement of at least 2 and preferably 3 to 12 nozzles on a concentric ring around the axis of the vessel emitting flat rays in the shape of circle sectors which hit equally large portions of the opposite wall under equal angles of from 15 to 90, preferably 40 to 60 (cf. Figure 3).
It is likewise possible to use a rotating disk as spraying device, the axis of rotation of which is . ~, .
~ ~ - 17 -" . , .~ ' . ' ': ' .
':' ' . . : , . ,, .. .: , ' . . ' .
-- 3.08~880 ; congruent with the axis of the vessel (cf. Figure 4). The process of the invention can be combined with other processes for the removal of monomers from dispersions. It can be . _ .
used with special advantage in all cases where foaming problems occur, especially when relatively large amounts of gas escape from dispersions tending to foam.
The process of the invention is reliable and permits the simple production of dispersions of low monomer content, for example less than 0.03% by weight or with repeated spraying even far iess, in many cases with the equipment already present by mounting little expensive additional installations. By spraying the particles of the dispersion onto the optionally heated wall of the vessel a very good degassing effect is obtained without detrimental foam formation. It is particularly advantageous that up ; to 10% by weight, calculated on the dispersion, of larger particles having a diameter of up to 5 mm do not cause any ~ ':
? trouble.
The treated dispersions can be used as such 20 or they can be further processed to obtain the solid polymer ~ by a known process, optionally after centrifugation or another ; method of concentration, for example by spray, conveying or contact drying, without the drying air being polluted by residual monomers.
;~ 2~ The process of the invention has little effect ~ on the properties of the dispersions. The~dispersions as well J~ as the dry polymers made therefrom can be used in the usual manners and in this case, too, troubles caused by the monomer(s) do not occur or are substantially done away with.
The treatment according to the present invention is `~ D
,, : .
- . . ..
-.
especially suitable for polymer dispersions which are sensi~ive to shearing forces and elevated temperature, tend to foam and ~orm incrustations i~ the apparatus and difficultly ~ive off - the monomers, for example polystyrene or styrene copolymer dispersionsor dispersions produced by emulsion or suspension polymerization of polyvinyl chloride and its copolymers and graft polymers containing up to 30 % by weight of comonomers, preferably up to 20 ~ by weight.
The vinyl chloride homo-, graft- or copolymer dispersions to be treated according to the present invention can be pre-pared by continuous or discontinuous polymerization processes with or without the use of a seedy polymer. The polymers are prepared in aqueous emulsion suspension in the presence of from 0.001 to 3 % by weight, preferably from 0.01 to 0.3 % by ~5 weight, calculated on the monomers, of the usual free radical forming catalysts, for example diaryl anddiacyl peroxides such as diacetyl, acetyl-benzoyl, dilauroyl, dibenzoyl, bis-2,4-di-chloro-benzoyl and bis-2-methyl-benzoyl peroxides; dialkyl per-oxides such as di-tert.butyl peroxide; per-esters such as tert.
` 20 butyl percarbonate, tert.butyl peracetate, tert.butyl peroctoate ~- and tert.butyl perpivalate; dialkyl peroxy dicarbonates such as l diisopropylj diethyl-hexyl, dicyclohexyl and diethylcyclohexyl peroxy dicarbonates; mixed anhydrides of organic sulfo-peracids and organic acids such as acetylcyclohexyl-sulfonyl peroxide;
and azo compounds used as polymerization catalysts such as azo- -isobutyronitrile; persulfates, for example potassium, sodium and ammonium persulfates; hydrogen peroxide, tert.butyl hydro-peroxide and other water-soluble peroxides, as well as mixtures 29 of different catalysts. The peroxidic catalysts can also be .-- 19 --D~
. ~ . . . . . , . . . .. . ... . ~ .
.. .. . . ..... .. . .~. .. . .; ~ .
. . .. . . . ~ .... ... . . ... .
1~81880 used in the presence of from 0.01 to 1 % by weight, calculated on the monomers, of at least one reducing substance suitable for the synthesis of a redox catalyst system, for example ~ sulfites, bisulfites, dithionites, thiosulfates, and aldehyde sulfoxylates, for example formaldehyde sulfoxylate. The poly-merization can also be carried out in the presence of soluble metal salts, for example of copper, silver, iron, or chromium, in amounts of from 0.05 to 10 ppm., calculated as metal on the monomer(æ).
The polymerization can also be carried out in the pre-sence of from 0.01 to 1 % by weight, preferably from 0.05 to 0.3 % by weight, calculated on the monomers, of at least one of the usual protective colloids, for example polyvinyl al-¢ohols which may contain up to 40 mole % of acetyl groups;
cellulose derivatives such as water-soluble methyl cellulose, carboxymethyl cellulose and hydroxyethyl cellulose; gelatin;
copolymers of maleic acid or the semi-esters thereof; styrenes;
polyvinyl pyrrolidone; and copolymers of vinyl acetate and ~inyl pyrrolidone.
The polymerization can also be carried out in the presence . .
of from 0.0~ to 5 % by weight, calculated on the monomers, of one or more emulsifiers which may be used in admixture with the above protective colloids. Suitable emulsifiers, which may be anionic, amphoteric, cationic, or non-ionic are, for 25~ example, alkali and alkaline earth metal and ammonium salts of fatty acids, for example of lauric, pal~itic or stearic acid, of acid fatty alcohol sulfuric acid esters, paraffin sulfonic acids, alkylaryl sulfonic acids such as dodecylbenzene or 29 dibutyl-naphthalene sulfonic acid, of sulfo-succinic acid _ 20 -- - -: . . :
.
5 ' ' `
,, i HOE 74/F 916 `` ~081880 .
~ialkyl esters, as well as the alkali metal and ammonium salts --of fatty acids containing epoxide groups, such as epoxy-stearic acid, of reaction products of per-acids, for example per-acetic acid with unsaturated fatty acids such as oleic acid or linoic acid, or unsaturated hydroxyl derivatives of fatty acids such as ricinoleic acid. Suitable amphoteric or cationic emulsifiers ; are, for example, alkyl betains, such as dodecyl betain, as well as alkyl pyridinium salts such as lauryl pyridinium hydro-chloride; and alkyl ammonium salts such as oxethyl dodecyl ammonium chloride. Suitable non-ionic emulsifiers are, for example, partial fatty acid esters of polyhydric alcohols such as glycerol monostearate, sorbitol monostearate, sorbitol mono-laurate, oleate, or palmitate~ polyhydroxy ethylene ethers of fatty alcoholi~ or aromatic hydroxy compounds, polyoxethylene esters of fatty acids and polypropylene oxide-polyethylene oxide condensation products.
Besides the catalysts, protective colloids and/or emul-sifiers, the polymerization mixture may also contain buffer ~ubstances, for example alkali ~etal acetates, borax, alkal~
metal phosphates, alkali metal ¢arbonates, ammonia, or ammonium ~_ salts of carboxylic acids; and moleculi~r weig~t regulators, .~ .
for example aliphatic aldehydes having from 2 to 4 carbon atoms, chioro- and bromo-hydrocarbons, for example di- and trichloro-ethylene, chloroform, bromoform and methylene chloride, and mercaptans.
Suitable polymerization auxiliaries ~or making the vinyl chloride polymers to be used are described, for example in "Polyvinylchlorid und Vinylchlorid-Misch-polymerisate" by 29 H.Kainer,Springer Verlag, Berlin/Heidelberg/New York, 1965, ~; :
.i , .
. .
'' ,~il. ~
` ` ~081880 NOE 74/F 916 :
pages ~3 - 59.
For copolymerization with vinyl chloride, one or more of the following monomers can be used; olefins such as ethylene - or propylene; vinyl esters of linear or branched carboxylic - 5 acids having from 2 to 20 carbon atoms, preferably 2 to 4 carbon atoms, for example vinyl acetate, propionate, butyrate and 2-ethylhexoate; vinyl-isotridecanoic acid esters; vinyl halides, for example vinyl fluoride, vinylidene fluoride, vinylidene chloride; vinyl ethers; vinyl pyridine; unsaturated acids such as maleic, fumaric, acrylic and methacrylic acid and the mono and diesters thereof with mono- and di-alcohols having from 1 to 10 carbon a~oms; maleic anhydride; maleic imide and the N-substitution products thereof ~ith aromatic, cyclo-aliphatic and optionally branched aliphatic substituents;
acrylonitrile; and s*rene.
~or graft polymerization, elastomeric polymers can be used, which are obtained by polymerizing one or more of the following 3 monomers: dienes, for example butadiene and cyclopentadiene;
olefins such as ethylene and propylene; styrene; unsaturated !
~ 20 acids such as acrylic and methacrylic acids and the esters `;~~ théreof with mono- and dialcohols having from 1 to 10 carbon atoms; acrylonitrile; vinyl compounds, for example vinyl esters of linear and branched carboxylic acids having from 2 to 20 and preferably from 2 to 4 carbon atoms; and vinyl halides such as vinyl chloride and vinylidene chloride.
: s After the polymerization, further substances for stabi-lizing or improving the processing properties can be added to ; the aqueous polymer dispersion. In special cases known anti-29 - foaming agents may be added although this is generally not . ,~ ' : . ' ' ' ' , ' ' , ~' ' ' ' ' . ' ' ' , ' ,' ' ' ' ' 81880 ~
necessary.
A particularly advantageous form of nozzle is known as an eccentric spray nozzle. This nozzle receives ~ the dispersion to be sprayed tangentially on a circle lying vertically with respect to the centre axis of the nozzle.
The flow follows a spiral path in the direction of the nozzle axis until the nozzle outlet permits discharge vertically with respect to the rotary motion of the dlspersion.
' , ., .
, . . .
.. j - . .
, , . ~
` ~ - 23 -.. ..
- . , - : ., : , : ,: - , : .
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the preparation of a polymer dispersion having a low monomer content in which at least 1 monomer in aqueous phase is subjected to emulsion or suspension polymerization, the process comprising the steps:
spraying the resultant dispersion in a vertical vessel onto the wall of the vessel at an issuing speed in the range of from 5 to 250 m/sec in the form of a hollow cone having a scattering angle of from 80 to 120° in the form of droplets having a diameter of at most 6 mm, the droplets covering a distance of 20 to 400 cm before they hit the wall of the vessel; permitting the dispersion to then run down the wall of the vessel; collecting the dispersion at an outlet in the lower part of the vessel; and collecting the gaseous constituents from a gas space above the spraying outlet of the dispersion.
spraying the resultant dispersion in a vertical vessel onto the wall of the vessel at an issuing speed in the range of from 5 to 250 m/sec in the form of a hollow cone having a scattering angle of from 80 to 120° in the form of droplets having a diameter of at most 6 mm, the droplets covering a distance of 20 to 400 cm before they hit the wall of the vessel; permitting the dispersion to then run down the wall of the vessel; collecting the dispersion at an outlet in the lower part of the vessel; and collecting the gaseous constituents from a gas space above the spraying outlet of the dispersion.
2. A process as claimed in claim 1 in which the dispersion is heated prior to spraying.
3. A process as claimed in claim 1 or claim 2 in which the sprayed droplets have a mean diameter in the range of 0.05 to 3 mm.
4. A process as claimed in claim 1 or claim 2 in which the droplets cover a distance of between 50 and 200 cm before they hit the wall of the vessel.
5. A process as claimed in claim 1 or claim 2 in which the issuing speed of the droplets is in the range 10 to 100 m/sec.
6. A process as claimed in claim 1 or claim 2 in one of steam, an inert gas, and a mixture of steam and inert gas is blown into the gas space of the vessel.
7. A process as claimed in claim 1 or claim 2 in which the dispersion is sprayed in several series-connected vessels having separate gas spaces.
8. Apparatus for use in the removal of at least one monomer from an aqueous untreated polymer dispersion to provide a treated polymer dispersion, the apparatus comprising: a vessel having an inner wall which is symmetrical about a vertical axis, a gas outlet at the top of the vessel and a further outlet at the bottom of the vessel for drawing off the polymer dispersion after treatment to remove the monomer; spray means positioned substantially at the vertical axis and adapted to cause a spray lying within a conical band defined by a lower cone making an angle of 40° with the axis and an upper cone making an angle of 60° with the axis, the spray being made up of droplets having a diameter of at most 6 mm and impinging onto the inner wall above a level where the treated polymer dispersion would collect so that the sprayed dispersion runs down the wall to meet collected dispersion before leaving the vessel through said further outlet; and means adapted to deliver the untreated polymer dispersion with the monomer in aqueous phase to the spray means.
9. Apparatus as claimed in claim 8 in which the inner wall is cylindrical.
10. Apparatus as claimed in claim 8 or claim 9 in which the spray means comprises a spray nozzle having a diameter of at least 1 mm.
11. Apparatus as claimed in claim 8 or claim 9 in which the spray means comprises a spray nozzle having a diameter in the range of from 5 to 100 mm.
12. Apparatus as claimed in claim 8 or claim 9 and further comprising a second vessel similar to the first-mentioned vessel, in which the apparatus further comprises means feeding treated polymer dispersion from said outlet to another spray means in the second vessel for further treat-ment of the polymer dispersion.
13. Apparatus as claimed in claim 8 or claim 9 in which the inner wall is heated at least where the spray strikes the inner wall.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2435704A DE2435704C3 (en) | 1974-07-25 | 1974-07-25 | Process and apparatus for the continuous removal of residual monomers from aqueous dispersions of vinyl chloride polymers |
| DEP2435704.8 | 1974-07-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1081880A true CA1081880A (en) | 1980-07-15 |
Family
ID=5921434
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA232,194A Expired CA1081880A (en) | 1974-07-25 | 1975-07-24 | Process and device for the manufacture of polymer dispersions with low monomer content |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS5137175A (en) |
| AT (1) | AT341772B (en) |
| BE (1) | BE831744A (en) |
| CA (1) | CA1081880A (en) |
| CH (1) | CH614962A5 (en) |
| DE (1) | DE2435704C3 (en) |
| ES (1) | ES439556A1 (en) |
| FR (1) | FR2279766A1 (en) |
| GB (1) | GB1508813A (en) |
| HU (1) | HU175479B (en) |
| IT (1) | IT1040006B (en) |
| NL (1) | NL168848C (en) |
| SE (1) | SE420734B (en) |
| YU (2) | YU39029B (en) |
| ZA (1) | ZA754769B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10272354B2 (en) | 2014-10-16 | 2019-04-30 | Rvt Process Equipment Gmbh | Liquid distributor of a process-technology column |
Families Citing this family (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL7607736A (en) * | 1974-07-25 | 1977-01-20 | Hoechst Ag | METHOD AND DEVICE FOR PREPARING POLYMER DISPERSIONS WITH A LOW MONOMERING CONTENT. |
| JPS5128890A (en) * | 1974-09-04 | 1976-03-11 | Mitsui Toatsu Chemicals | MIHANNOENKABINIRUMONOMAA NO JOKYOHOHO |
| JPS5147075A (en) * | 1974-10-19 | 1976-04-22 | Shinetsu Chemical Co | Jugoshuryogono mihannotanryotaijokyohoho |
| JPS51127187A (en) * | 1975-04-26 | 1976-11-05 | Kureha Chem Ind Co Ltd | A process and an apparatus for recovering monomers |
| JPS52147689A (en) * | 1976-06-02 | 1977-12-08 | Mitsui Toatsu Chem Inc | Continuous removal of unreacted vinyl chloride monometer |
| DE2701147C2 (en) * | 1977-01-13 | 1987-01-02 | Wacker-Chemie GmbH, 8000 München | Process for the production of vinyl chloride copolymers with a low residual monomer content |
| DE2832972A1 (en) * | 1978-07-27 | 1980-02-07 | Wacker Chemie Gmbh | METHOD FOR PRESSURE AND RESIDUE DEGASSING OF A PVC-WATER MIXTURE IN THE POLYMERIZATION AUTOCLAVE AT THE HIGHEST POSSIBLE SEPARATION DEGREE OF THE TRANSMISSION IN A ADDITIONAL SEPARATOR AND RETURN OF THE TRANSMISSION TO THE RESTOURY |
| IT1121511B (en) * | 1979-05-28 | 1986-04-02 | Montedison Spa | PROCEDURE FOR THE EXTRACTION OF THE VINYL CHLORIDE MONOMER FROM THE POLYVINYL CHLORIDE LACTICS AND EQUIPMENT FOR ITS REALIZATION |
| GB2247415A (en) * | 1990-08-29 | 1992-03-04 | Shell Int Research | Discharge device for reducing foam |
| DE19517680C2 (en) * | 1995-05-13 | 1997-06-12 | Buna Sow Leuna Olefinverb Gmbh | Process for reducing foam development |
| NZ511502A (en) * | 2001-05-04 | 2002-03-01 | Wen Sen Shih | Two-chamber water distillation apparatus |
| DE102011119341A1 (en) | 2011-11-25 | 2013-05-29 | Heraeus Quarzglas Gmbh & Co. Kg | Process for the production of synthetic quartz glass using the soot method |
| DE102011119374A1 (en) | 2011-11-25 | 2013-05-29 | Heraeus Quarzglas Gmbh & Co. Kg | Process for the production of synthetic quartz glass |
| DE102011119373A1 (en) | 2011-11-25 | 2013-05-29 | Heraeus Quarzglas Gmbh & Co. Kg | Process for the production of synthetic quartz glass |
| DE102011119339A1 (en) | 2011-11-25 | 2013-05-29 | Heraeus Quarzglas Gmbh & Co. Kg | Sputtering process for the production of synthetic quartz glass |
| DE102013209673B3 (en) * | 2013-05-24 | 2014-05-22 | Heraeus Quarzglas Gmbh & Co. Kg | Process and evaporator for the production of synthetic quartz glass |
| WO2020241252A1 (en) * | 2019-05-31 | 2020-12-03 | 昭和電工株式会社 | Method for producing purified chloroprene-based-polymer latex |
| WO2020241251A1 (en) | 2019-05-31 | 2020-12-03 | 昭和電工株式会社 | Method for producing chloroprene-based-polymer latex |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1799467A (en) * | 1927-03-07 | 1931-04-07 | Thomas B Jarvies | Vapor-heating system |
| NL79746C (en) * | 1953-11-06 | |||
| GB1090976A (en) * | 1964-02-12 | 1967-11-15 | Dunlop Rubber Co | Improvements in or relating to volatilization of residual liquid monomers |
| DE1495177A1 (en) * | 1964-05-05 | 1969-03-13 | Basf Ag | Process and device for the continuous removal of volatile components from polyamides |
| BE709965A (en) * | 1967-01-27 | 1968-05-30 | ||
| JPS546269B1 (en) * | 1970-12-18 | 1979-03-27 | ||
| DE2130616A1 (en) * | 1971-06-21 | 1972-12-28 | Franz Froitzheim | Evapn of liqs - using a hot surface |
| DE2259740C3 (en) * | 1972-12-04 | 1981-10-08 | Siemens AG, 1000 Berlin und 8000 München | Device for degassing liquids |
-
1974
- 1974-07-25 DE DE2435704A patent/DE2435704C3/en not_active Expired
-
1975
- 1975-07-17 ES ES439556A patent/ES439556A1/en not_active Expired
- 1975-07-18 NL NLAANVRAGE7508630,A patent/NL168848C/en not_active IP Right Cessation
- 1975-07-21 SE SE7508274A patent/SE420734B/en not_active Application Discontinuation
- 1975-07-22 CH CH959375A patent/CH614962A5/en not_active IP Right Cessation
- 1975-07-23 GB GB30782/75A patent/GB1508813A/en not_active Expired
- 1975-07-23 IT IT25691/75A patent/IT1040006B/en active
- 1975-07-24 ZA ZA00754769A patent/ZA754769B/en unknown
- 1975-07-24 CA CA232,194A patent/CA1081880A/en not_active Expired
- 1975-07-24 YU YU01888/75A patent/YU39029B/en unknown
- 1975-07-24 AT AT572175A patent/AT341772B/en not_active IP Right Cessation
- 1975-07-24 FR FR7523097A patent/FR2279766A1/en active Granted
- 1975-07-24 JP JP50089699A patent/JPS5137175A/ja active Pending
- 1975-07-25 BE BE158619A patent/BE831744A/en not_active IP Right Cessation
- 1975-07-25 HU HU75HO1822A patent/HU175479B/en unknown
-
1981
- 1981-07-10 YU YU1719/81A patent/YU41460B/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10272354B2 (en) | 2014-10-16 | 2019-04-30 | Rvt Process Equipment Gmbh | Liquid distributor of a process-technology column |
Also Published As
| Publication number | Publication date |
|---|---|
| GB1508813A (en) | 1978-04-26 |
| NL7508630A (en) | 1976-01-27 |
| AT341772B (en) | 1978-02-27 |
| ES439556A1 (en) | 1977-02-16 |
| SE420734B (en) | 1981-10-26 |
| SE7508274L (en) | 1976-01-26 |
| DE2435704B2 (en) | 1979-09-27 |
| FR2279766A1 (en) | 1976-02-20 |
| HU175479B (en) | 1980-08-28 |
| CH614962A5 (en) | 1979-12-28 |
| YU188875A (en) | 1982-05-31 |
| FR2279766B1 (en) | 1980-07-25 |
| YU171981A (en) | 1983-09-30 |
| IT1040006B (en) | 1979-12-20 |
| ZA754769B (en) | 1976-08-25 |
| DE2435704C3 (en) | 1987-06-19 |
| NL168848B (en) | 1981-12-16 |
| NL168848C (en) | 1984-05-16 |
| BE831744A (en) | 1976-01-26 |
| DE2435704A1 (en) | 1976-02-05 |
| YU39029B (en) | 1984-02-29 |
| ATA572175A (en) | 1977-06-15 |
| YU41460B (en) | 1987-06-30 |
| JPS5137175A (en) | 1976-03-29 |
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