WO1997045184A1 - Colonne et procede pour desodoriser des dispersions - Google Patents

Colonne et procede pour desodoriser des dispersions Download PDF

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Publication number
WO1997045184A1
WO1997045184A1 PCT/EP1997/002639 EP9702639W WO9745184A1 WO 1997045184 A1 WO1997045184 A1 WO 1997045184A1 EP 9702639 W EP9702639 W EP 9702639W WO 9745184 A1 WO9745184 A1 WO 9745184A1
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WIPO (PCT)
Prior art keywords
column
dispersion
dispersions
polymer
range
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Application number
PCT/EP1997/002639
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German (de)
English (en)
Inventor
Wolfgang HÜBINGER
Peter Keller
Rudolf Kaiser
Wolfgang Heider
Ulrich Eiden
Original Assignee
Basf Aktiengesellschaft
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Publication date
Priority claimed from DE1996121027 external-priority patent/DE19621027A1/de
Priority claimed from DE1997116373 external-priority patent/DE19716373A1/de
Application filed by Basf Aktiengesellschaft filed Critical Basf Aktiengesellschaft
Priority to BR9709367A priority Critical patent/BR9709367A/pt
Priority to AU30916/97A priority patent/AU3091697A/en
Priority to EP97925936A priority patent/EP0907393A1/fr
Publication of WO1997045184A1 publication Critical patent/WO1997045184A1/fr

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Classifications

    • 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
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/16—Fractionating columns in which vapour bubbles through liquid
    • B01D3/22—Fractionating columns in which vapour bubbles through liquid with horizontal sieve plates or grids; Construction of sieve plates or grids
    • B01D3/225—Dual-flow sieve trays
    • 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
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/16—Fractionating columns in which vapour bubbles through liquid
    • B01D3/22—Fractionating columns in which vapour bubbles through liquid with horizontal sieve plates or grids; Construction of sieve plates or grids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D19/00—Degasification of liquids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D19/00—Degasification of liquids
    • B01D19/0005—Degasification of liquids with one or more auxiliary substances
    • B01D19/001—Degasification of liquids with one or more auxiliary substances by bubbling steam through the liquid
    • B01D19/0015—Degasification of liquids with one or more auxiliary substances by bubbling steam through the liquid in contact columns containing plates, grids or other filling elements
    • 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
    • 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

Definitions

  • the invention relates to a column and a process for reducing the residual volatile content in dispersions (deodorization of dispersions), and to a device for producing polymer dispersions and the polymer dispersions obtained and their use.
  • residual volatiles used here denotes all such organic compounds with a boiling point (or start of boiling point) of at most 250 ° C.
  • the residual volatiles are undesirable in many applications of dispersions or suspensions, for example in the food or cosmetics sector or in interior applications, and efforts are made to remove them as completely as possible. Dispersions or suspensions are therefore subjected to a treatment which removes the volatile organic constituents. This treatment is mostly referred to as deodorization.
  • DE-A 25 50 023 discloses a degassing column with a plurality of trays one above the other.
  • An essential feature of this column is that a gap that is uniform over the circumference is left between each tray and the column jacket. This feature, however, greatly reduces the efficiency of the entire column, since the liquid phase can be trickled past the open edges without the desired stripping effect occurring.
  • DE-C 27 59 097 describes a process for removing monomers from dispersions, in which the column used is almost completely filled with liquid. As a result, however, the hold-up in the column is undesirably increased, and regularly necessary cleaning work is complex, so that, for example, when changing products problems occur again and again.
  • the specific free hole area is 1.6%.
  • DE-C 25 21 780 discloses a process for removing monomers with the aid of a column equipped with sieve plates, in which water vapor at a temperature of 100 to 150 ° C. under a pressure of 0.8 to 1.6 bar is used.
  • the method described here has the disadvantage that the relatively high temperatures can damage the products.
  • Water vapor is introduced in amounts of 1 to 5% by weight, based on the amount of dispersion added.
  • DE-A 27 33 679 describes a similar process for separating monomers by means of a column with perforated plates, in which the temperature in the column is 90 to 150 ° C. In order to reach the temperatures, the pressure in the column usually has to be raised.
  • this relatively high temperature level in the column also has the disadvantage that relatively temperature-sensitive products cannot be processed. Furthermore, no polymers can be used in the process mentioned here, which soften at temperatures below 90 ° C. Only relatively small plate Distances described in the column, otherwise the polymer is feared to back up on the column wall. The hole diameter is 10 mm, the specific free hole area 5.5 to 7.5%.
  • the object was to find an improved process which remedies the disadvantages mentioned and enables a technically simple and economical separation of the residual volatiles from aqueous suspensions or dispersions. It should also be possible to use relatively high amounts of steam in the process and it should also be possible to use relatively temperature-sensitive products, with high purities being achieved without the residence time in the column having to be increased appreciably.
  • a countercurrent column is to be provided which allows the process to be carried out in such a way that separate storage containers in front of the column can be dispensed with, and the cleaning of the column is simplified, so that product changes are easily possible.
  • the object is achieved by providing a countercurrent column for reducing the volatile content in dispersions which has 5 to 50 rain sieve trays and / or crossflow sieve trays, the specific free perforated area in the rain sieve trays 2 to 25% and in the crossflow sieve trays 1 to 10% is, in the rain screen trays the average hole diameter is 10 to 50 mm and in the cross-flow tray trays the average hole diameter is 2 to 10 mm.
  • the object is achieved by a process for the preparation of dispersions with a low residual volatile content by treating the dispersion with water vapor in a countercurrent column comprising rain sieve trays and / or crossflow sieve trays, the steam being added to a pressure of 0.1 to 0.7 bar in the column in countercurrent to the dispersion.
  • the dispersion feed is preferably 4 to 15 kg / cm 2 h for rain sieve trays and 15 to 25 kg / cm 2 h for cross-flow sieve trays.
  • residual volatiles has the meaning given at the beginning.
  • the measurement of residual volatiles is carried out according to DRAFT International Standard ISO / DIS 13741, Part 1 by gas chromatography. They are referred to in this standard as remaining monomers and other organic components.
  • examples include acrylic acid esters such as n-butyl acrylate and isobutyl acrylate, methacrylic acid esters such as methyl methacrylate, acrylonitrile, butadiene, styrene, vinyl acetate, vinyl chloride, and also by-products, for example acetaldehydes and ethylbenzene. Propionitrile, ethyl acrylate and 4-vinylcyclohexene are also listed.
  • the process according to the invention offers the possibility of separating monomers from aqueous suspensions or dispersions in a technically simple and economical manner with a relatively simple construction. Due to the simple design, the column is reliable and easy to clean in practical operation, and a product change is also easy due to the relatively low hold-up in the column. Furthermore, relatively high plate efficiencies can be achieved, whereby the number of plates in the column can be reduced. Due to the reduced pressure in the column, the temperatures in the column are relatively low, so that temperature-sensitive dispersions can also be used. The method also enables the use of relatively high amounts of steam, and it can soften the polymers in the suspension or Dispersion in the column can be reduced so far that the separation process is not affected.
  • the countercurrent column according to the invention can be operated with a very high throughput, so that the column itself can be designed to be small. This makes cleaning the column easier. Since the countercurrent columns are increasingly used not only for deodorization of a certain type of dispersions, but are also operated as part of multi-product systems with frequently changing products or dispersions, simple cleaning of the column used is desirable. The intensity of the cleaning of the column determines the quality of the dispersion obtained. Cleaning is simplified and accelerated by the column designed according to the invention, with smaller amounts of cleaning liquid being required. This enables the column to be operated much more economically and can be used in multi-product plants with frequently changing products. Because of the particularly simple cleaning, columns with rain sieve trays (also referred to as dual-flow trays) are preferred in multi-product systems over the cross-flow sieve trays that can also be used.
  • the columns according to the invention can comprise rain screen trays, cross-flow screen trays or combinations of rain screen trays and cross-flow screen trays exhibit. They preferably have either rain sieve trays or cross-flow sieve trays.
  • the number of trays is 5 to 50, preferably 8 to 40, particularly preferably 15 to 30.
  • the distance between the trays is preferably 250 to 800, particularly preferably 300 to 700, in particular 400 to 600 mm.
  • the column height is preferably 6 to 25, particularly preferably 10 to 20 m.
  • the diameter of the column, preferably with a circular cross section, is preferably 400 to 2500 mm, particularly preferably 800 to 1600 mm.
  • the rain screen trays have average hole diameters of 10 to 50, preferably 12 to 25 mm.
  • the average hole diameter is 2 to 10, preferably 4 to 8 mm.
  • the holes are preferably circular.
  • the specific free perforated area that is to say the percentage of each area filled by holes, is expediently 2 to 25% in the rain sieve trays, preferably 5 to 20%, particularly preferably 10 to 18%, expediently 1 to in the cross-flow sieve trays 10%, preferably 3 to 8%, particularly preferably 4 to 7%.
  • the specific free perforated area is preferably selected so that the following dispersion feeds, based on the free perforated area, are accessible with the stated amounts of steam.
  • Both the cross-sectional shape of the column and the shape of the holes can be adapted to the respective requirements. They are preferably circular cross sections or holes, although other shapes can also be suitable for special applications.
  • the column diameter of the column according to the invention is preferably enlarged in the upper region for gravity separation of dispersion droplets from the steam.
  • the diameter of this extension is at least 1 meter, in particular in the case of smaller columns. It can be up to 4 meters, especially for larger columns. As a rule, the head widening is approximately 1.5 times the diameter of the column trays.
  • the column preferably has an extension of 1 to 3 m, preferably 2 to 3 m, in the lower region, which represents the column bottom.
  • the deodorized dispersion is taken up in this column bottom. It serves as a pump template for subsequent process stages.
  • the dispersion is fed in in the upper region (head) of the column, preferably in the enlarged upper region (head extension) of the column.
  • a column with rain sieve trays is preferably used according to the invention, since it has no construction-related dead zones, which means reduced cleaning effort and allows higher efficiencies.
  • the column size in particular the column height and the number of trays, can be reduced.
  • the column preferably has 15 to 30 trays, which are arranged at a distance of 400 to 600 mm.
  • the column diameter is 800 to 1600 mm, especially 1000 to 1500 mm.
  • the specific free perforated area and the diameter of the column are selected so that a dispersion throughput in the range of in particular 5 to 30 t / h is possible with a dispersion feed of 4 to 15 kg / cm 2 h based on the free perforated area.
  • a crossflow sieve tray column preferably has the same external dimensions and number of trays as the rain sieve tray column.
  • the specific free perforated area and the diameter of the column are selected so that a dispersion addition in the range of in particular 10 to 30 t / h is possible with a dispersion feed of 15 to 25 kg / m 2 h based on the free perforated area.
  • the column according to the invention preferably has a discharge weir.
  • the weir height is preferably 50 to 200 mm.
  • the height of the column exit from the column is preferably 20 to 50 mm, particularly preferably 25 to 40 mm.
  • the specific hole area is about 6%.
  • the number of holes per floor is 2000 to 9000.
  • the column according to the invention can be integrated into a device for producing polymer dispersions.
  • a corresponding device according to the invention for producing polymer dispersions comprises a reactor (A), optionally a post-reactor (B), a column (C), as described above, a heat exchanger (D) for the evaporation, and, if appropriate, an expansion device (E) , a filter (F) and a conditioning device (G).
  • the outlet of the reactor (A) or of the secondary reactor (B) is preferably connected directly to the inlet of the column (C) without the interposition of a separate feed tank.
  • Corresponding devices are in the
  • Figure 1 shows a device with a rain sieve tray column in a schematic representation
  • Figure 2 shows a device with a cross-flow sieve tray column in a schematic representation.
  • Dispersion preparation is generally carried out batchwise in the reactor (A), the content of which is usually transferred to the after-reactor after, incompletely, the reaction.
  • the dispersion had to be transferred from the after-reactor (B) into a separate storage container from which the deodorization column was fed. This was necessary because the throughput of the column was significantly lower than the pumping throughput from the after-reactor (B).
  • the column (C) according to the invention preferably allows such a high throughput that when the after-reactor (B) is emptied the dispersion can be fed directly into the column, since the column has the same throughput may have, which occurs when emptying the post-reactor (B).
  • the entire device By dispensing with a separate storage container, the entire device can be simplified and thus constructed more cost-effectively. The operation is also less expensive because there is no need to control a separate storage container.
  • the aim In the parts of the plant which are not directly influenced by the column (s), the aim is to be able to pump at rates of 20 to 50 t / h.
  • a separate storage container or intermediate buffer upstream of the column can be dispensed with and the column can be fed directly from the after-reactor.
  • the relaxation stage (E) is generally provided in order to be able to adjust the water content of the dispersion discharged from the column bottom. Part of the introduced steam often condenses in the column, so that the water content of the dispersion in the column bottom is increased. In order to reduce the water content, the dispersion obtained can be expanded further (by reducing the pressure with the aid of vacuum equipment), as a result of which some of the water can be discharged as steam (El). The dispersion (E2) discharged from the relaxation stage (E) can thus be adjusted to a desired water content.
  • the columns and devices described above are advantageously used in the process according to the invention for producing dispersions with a low residual volatile content.
  • the dispersion obtained from the reaction generally a polymer dispersion, preferably an aqueous polymer dispersion, is passed through the column in countercurrent to the water vapor.
  • the water vapor is passed at a pressure of 0.1 to 0.7 bar in the column in countercurrent to the dispersion.
  • the pressure in the Column preferably adjusted so that the temperature at the top of the column is above the glass transition temperature of the polymer and the temperature in the bottom of the column is below the temperature at which the polymer dispersion loses its stability and, for example, decomposes or agglomerates or coagulates.
  • the pressure in the column is preferably 0.2 to 0.7 bar, particularly preferably 0.2 to 0.5 bar at the top of the column.
  • the temperature in the column is preferably from 50 to 90 C C, particularly preferably 60-82 ° C. Due to the pressure drop in the column, the temperature at the top of the column is lower than in the bottom of the column.
  • the inlet temperature of the dispersions is preferably 50 to 90 ° C, particularly preferably 60 to 80 ° C.
  • the temperature in the column bottom is preferably 70 to 90 ° C.
  • the outlet temperature of the dispersion corresponds to this temperature.
  • the pressure at the top of the column is 0.2 to 0.5 bar, above the bottom of the column 0.3 to 0.7 bar.
  • Design data for a rain sieve tray column are, for example: hole diameter 15 to 25 mm, surface loading 8 to 15 m 3 / m 2 h, specific loading, based on the hole cross section, 10 to 12 kg / cm 2 h, pressure at the column head 0.2 to 0.5 bar (absolute).
  • a cross-flow sieve tray column is designed, for example, as follows: hole diameter approximately 4 mm, surface loading 8 to 15 m 3 / m 2 h, specific free perforated area 5 to 10%, weir height 100 to 200 mm, pressure at the column head 0.2 to 0.5 bar, specific load, based on the hole cross section, 15 to 22 kg / cm 2 h.
  • the specific steam requirement in the process according to the invention is preferably 10 to 50%, particularly preferably 20 to 30% by weight, measured as water, based on the amount of dispersion introduced.
  • the steam throughput is preferably about 0.1 to 10 t / h, particularly preferably 1 to 8 t / h.
  • the throughput of dispersion is preferably 1 to 50 t / h, particularly preferably 5 to 30 t / h.
  • the throughput of dispersion is preferably 20 t / h or more, with lower production 5 to 10 t / h, on a pilot plant scale (test stage) about 1 to 2 t / h.
  • the throughput depends on the column diameter.
  • the specific surface loading of the column is 1.6 to 25, preferably 8 to 15, m 3 of dispersion per m 2 of cross-sectional area of the column and hour.
  • the inflow is preferably 4 to 15, particularly preferably 10 to 13 kg / cm 2 h for rain sieve trays, preferably 15 to 25, particularly preferably 15 to 22 kg / cm 2 h for cross-flow sieve trays.
  • the procedure according to the invention allows high specific throughputs in the column. Therefore, the dimensions of the column can be kept small, which on the one hand leads to an inexpensive construction and on the other hand reduces the inner surface of the column, which in turn reduces the cleaning effort when changing batches.
  • the residence time in the column is preferably 100 to 2000 s, particularly preferably 200 to 1000 s, in particular 400 to 800 s, depending on the dispersions used.
  • the invention also relates to the dispersions which can be prepared by the process according to the invention.
  • These are dispersions, in particular polymer dispersions, with a residual volatile content of less than 100 ppm, often even less than 50 ppm, in favorable cases even less than 25 ppm, which can be prepared by the above process.
  • the structure of the preferred dispersions is given below.
  • the dispersions used in the process according to the invention can be any dispersions which have removable levels of residual volatiles.
  • examples of such dispersions can be dispersions of contaminated soil, dispersions of inorganic particles, dispersions of biomolecules and preferably dispersions of organic compounds, in particular polymer dispersions.
  • the dispersions are preferably aqueous dispersions.
  • the aqueous polymer dispersions which are preferably suitable for the process according to the invention are fluid systems which, as a disperse phase in the aqueous dispersion medium, contain polymer particles in a stable disperse distribution.
  • the diameter of the polymer particles is generally mainly in the range from 0.01 to 5 ⁇ m, often mainly in the range of 0.01 to 1 ⁇ m.
  • the stability of the disperse distribution often extends over a period of at least one month, in many cases even over a period of at least 6 months.
  • aqueous polymer dispersions have the property of forming polymer films when the aqueous dispersion medium is evaporated, which is why aqueous polymer dispersions are used in many ways as binders, e.g. for paints or compositions for coating leather.
  • aqueous polymer dispersions into aqueous secondary and aqueous primary dispersions.
  • the aqueous secondary dispersions are those in the production of which the polymer is produced outside of the aqueous dispersion medium, for example in solution of a suitable non-aqueous solvent. This solution is then transferred to the aqueous dispersion medium and the solvent is separated off, generally by distillation, with dispersion.
  • aqueous primary dispersions are those in which the polymer is itself produced in disperse distribution in the aqueous dispersion medium. It is essentially common to all production processes that monomers which have at least one ethylenically unsaturated group are used for the synthesis of the polymer, or that the polymer is constructed exclusively from such monomers.
  • Such monomers having at least one ethylenically unsaturated group are usually incorporated by initiated polyreaction, the type of initiation used being determined in particular by the desired performance properties of the target product and therefore being adapted to this.
  • initiation for example, an ionic or a radical initiation can be considered.
  • Installation can also be done by catalytically initiated polymer-analogous reaction take place.
  • Radical initiation is used particularly frequently, which is why the incorporation of monomers having ethylenically unsaturated groups in the case of aqueous primary dispersions is generally by the method of free-radical aqueous emulsion polymerization and in the case of aqueous secondary dispersions is is generally the method the radical solution polymerization takes place.
  • the polyreaction conditions are chosen so that the desired properties of the polymer, such as molecular weight, molecular weight distribution and degree of branching, are obtained.
  • the aqueous polymer dispersions obtained after the reaction normally still have, in particular ethylenically unsaturated, monomers. Due to the increased reactivity of the ethylenically unsaturated double bond, residual monomers such as acrylonitrile and vinyl acetate are not completely harmless from a toxicological point of view and should therefore be removed from the dispersion.
  • the present method serves this purpose. The method can be used for all polymers dispersed in an aqueous medium, regardless of the type of polymer.
  • polymer here therefore encompasses both polycondensates such as polyesters, polyadducts such as polyurethanes and polymers which are accessible by ionic or radical polymerization.
  • Polycondensates such as polyesters
  • polyadducts such as polyurethanes
  • polymers which are accessible by ionic or radical polymerization.
  • Mixed variants of the syntheses mentioned, as well as copolymers, likewise result in dispersions which can be used according to the invention.
  • Suitable monomers having at least one monoethylenically unsaturated group for the process according to the invention are in particular, in a simple manner, radically polymerizable monomers, such as the olefins, for example ethylene, vinylaromatic monomers such as styrene, ⁇ -methylstyrene, o-chlorostyrene or vinyl toluenes, esters of vinyl alcohol and monocarboxylic acids having 1 to 18 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate, vinyl pivalate and vinyl stearate, and commercially available monomers VEOVA 9 to 11 (VEOVA is a trade name of Shell and stands for vinyl esters of carboxylic acids, which are also referred to as Versatic ® X acids), esters of ⁇ , /?
  • radically polymerizable monomers such as the olefins, for example ethylene, vinylaromatic monomers such as s
  • - mono-ethylenically unsaturated mono- and dicarboxylic acids such as acrylic acid, preferably having 3 to 6 carbon atoms.
  • Methacrylic acid, maleic acid, fumaric acid and itaconic acid with generally 1 to 12, preferably 1 to 8 and in particular 1 to 4 carbon atoms a pointing alkanols, such as acrylic acid and methacrylic acid methyl, ethyl, n-butyl, isobutyl, tert-butyl and -2-ethylhexyl ester, dimethyl maleate or n-butyl maleate, nitriles ⁇ .jS monoethylenically unsaturated carboxylic acids, such as acrylonitrile, and C 4 .
  • the monomers mentioned generally form the main monomers which, based on the total amount of the monomers to be polymerized by the free-radical aqueous emulsion polymerization process, normally account for more than 50% by weight unite. As a rule, these monomers have Water at normal conditions (25 ° C, 1 atm) only has a moderate to low solubility.
  • Monomers which have an increased water solubility under the abovementioned conditions are, for example, ⁇ , / J-monoethylenically unsaturated mono- and dicarboxylic acids and their amides, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, and also vinylsulfonic acid and their water-soluble salts, as well as N-vinyl pyrrolidone.
  • the abovementioned monomers which have increased water solubility, are normally only used as modifying monomers in amounts, based on the total amount of the monomers to be polymerized, of less than 50% by weight. , usually 0.5 to 20, preferably 1 to 10 wt .-%, with copolymerized.
  • Monomers which usually increase the internal strength of the films of the aqueous polymer dispersions normally have at least one epoxy, hydroxy, N-methylol, carbonyl or at least two non-conjugated ethylenically unsaturated double bonds.
  • Examples include N-alkylamides of 3 to 10 carbon atoms, a, ⁇ -monoethylenically unsaturated carboxylic acids and their esters with 1 to 4 carbon atoms, among which the N-methylol acrylamide and the N-methylol methacrylamide are particularly preferred , two vinyl-containing monomers, two vinylidene-containing monomers and two alkenyl-containing monomers.
  • the di-esters of dihydric alcohols with ⁇ , ⁇ -monoethylenically unsaturated monocarboxylic acids are particularly advantageous, among which acrylic and methacrylic acid are preferred.
  • alkylene monomers lenglykolacrylate diacrylates and dimethacrylates such as ethylene glycol diacrylate, butylene glycol diacrylate 1,3-, 1, 4-butylene glycol diacrylates and propylene glycol diacrylate, divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, diallyl maleate, Diallyl fumarate, methylenebisacrylamide, cyclopentadienyl acrylate or triallyl cyanurate.
  • methacrylic acid and acrylic acid-C j -Cg-hydroxyalkyl esters such as n-hydroxyethyl, n-hydroxypropyl or n-hydroxybutyl acrylate and methacrylate, and compounds such as diacetone acrylamide and acetylacetoxyethyl acrylate, respectively -methacrylate, ureidoethyl methacrylate and acrylamidoglycolic acid.
  • aqueous polymer dispersions produced exclusively by the free-radical aqueous emulsion polymer method based on the total amount of the monomers to be polymerized, the above monomers are also copolymerized in amounts of from 0.5 to 10% by weight.
  • Dispersants which ensure the stability of the aqueous polymer dispersion produced are usually also used in the course of the free-radical aqueous emulsion polymerization.
  • Both the protective colloids usually used to carry out free-radical aqueous emulsion polymerizations and emulsifiers come into consideration as such.
  • Suitable protective colloids are, for example, polyvinyl alcohols, cellulose derivatives or copolymers containing vinylpyrrolidone.
  • a detailed description of other suitable protective colloids can be found in the Houben Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Substances, Georg-Thieme-Verlag, Stuttgart, 1969, pages 411 to 420.
  • mixtures of emulsifiers and / or protective colloids can also be used.
  • emulsifiers are used as dispersants, the relative molecular weights of which, in contrast to the protective colloids, are usually below 1000. They can be anionic, cationic or nonionic in nature.
  • anionic emulsifiers are compatible with one another and with nonionic emulsifiers.
  • emulsifiers are, for example, ethoxylated mono-, di- and tri-alkylphenols (EO grade: 3 to 100, alkyl radical: C 4 to C 12 ), ethoxylated fatty alcohols (EO grade: 3 to 100, Alkyl radical: C 8 to C 18 ), and alkali and ammonium salts of alkyl sulfates (alkyl radical: C 8 to C 16 ), of sulfuric acid half-ethers of ethoxylated alkylphenols (EO degree: 3 to 100, alkyl radical: C 4 to C 12 ), of alkylsulfonic acids (alkyl radical: C 12 to C 18 ) and of alkylarylsulfonic acids (alkyl radical: C 9 to C 18 ).
  • EO grade: 3 to 100, alkyl radical: C 4 to C 12 ethoxylated fatty alcohols
  • alkyl radical: C 8 to C 18 alkali and ammonium salts of alkyl
  • emulsifiers such as sulfosuccinic acid esters can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Substances, Georg-Thieme Verlag, Stuttgart, 1961, pages 192 to 208.
  • the amount of dispersant used is 0.5 to 6, preferably 1 to 3,% by weight, based on the weight of the monomers to be polymerized by free radicals.
  • the aforementioned dispersants are generally suitable for stabilizing the process products according to the invention.
  • the process products according to the invention also comprise aqueous polymer dispersions of self-emulsifying polymers, that is to say of polymers which have ionic groups which, owing to the repulsion of charges of the same sign, are able to bring about stabilization.
  • the direct process products according to the invention preferably have anionic stabilization (in particular anionic dispersants).
  • aqueous polymer dispersion the residual monomer content of which is to be reduced in the manner according to the invention, is prepared by radical aqueous emulsion polymerization from monomer compositions of monomers having at least one ethylenically unsaturated group
  • monomer compositions are of particular importance with regard to the process according to the invention. which comprise at least two different monomers which have at least one ethylenically unsaturated group, and for the rest
  • esters of acrylic and / or methacrylic acid with alkanols and / or styrene having 1 to 12 carbon atoms or
  • the polymeric solids content in the suspension or dispersion is usually about 20 to 75% by weight, preferably about 40 to 70% by weight, particularly preferably 50 to 60% by weight.
  • the viscosities of the suspensions or dispersions used are at a temperature of 25 ° C. at about 10 to 5000 mPas, preferably 20 to 2000 mPas, particularly preferably 50 to 1000 mPas.
  • the viscosity of the dispersions used is preferably low. It can be in the range from 30 to 1000 mPas.
  • the density of the dispersions is preferably around 1 g / cm 3 .
  • the glass transition temperature is preferably determined from the temperature dependency of the specific heat in a differential thermal analysis (G. Goldbach in: Plastics, Order States and Properties in: Ulimanns Encyklopadie der Technische Chemie, Volume 15, pages 219 to 222, Weinheim, 1980).
  • the glass transition temperature of copolymers can also be calculated from the glass transition temperatures of the respective homopolymers, weighted according to the mass fractions of the monomers and the expansion coefficients of the polymers.
  • the minimum film bifunction temperature of the polymer is the lowest temperature at which a dispersion just forms a coherent film after the water has evaporated. It is close to the glass transition temperature of the polymer (H. Gerrens in: Polymerisationstechnik in: Ullmann Encyklopadie der Technische Chemie, Volume 19, page 141, Weinheim, 1989).
  • a metal plate on which a temperature gradient is applied serves as the measuring device.
  • the temperature at which the film begins to crack is observed (E. Penzel in: Polyacrylic and Polymethacrylic Compounds in: Ullmanns Encyklopadie der Technische Chemie, Volume 19, pages 17 to 18, Weinheim, 1980).
  • the glass transition temperature of the acrylates which are preferably used as the dispersion in the process according to the invention is between -62 and + 6 ° C. (see Table 8 from E. Penzel in: Polyacrylic and Polymethacryl Compounds in: Ullmanns Encyklopadie der Technische Chemie, Volume 19, page 17 to 18, Weinheim, 1980).
  • the resulting minimum film image temperatures of the polymers in the dispersions are therefore often far below the preferred operating temperature of the process according to the invention.
  • the dispersions to be treated are therefore often soft at the process temperature and easily form films.
  • the flow behavior depends on the solids content, the particle size, the particle size division and of the auxiliary system that was used in the manufacture. Structural viscosity and dilatancy are frequently observed flow anomalies.
  • the viscosity is measured under standardized measuring conditions in a capillary viscometer, Couette viscometer or cone-plate viscometer (C. Gerth: Rheometrie, Ullmanns Encyklopadie der Technische Chemie, Volume 19, pages 17 to 18, Weinheim 1980).
  • the invention further relates to a process for the preparation of these polymer dispersions with a low residual volatile content by the above process.
  • the method is particularly suitable for shear-sensitive dispersions, for example low-emulsifier or emulsifier-free formulations, sterically (with protective colloid or with starch) stabilized dispersions or self-dispersing systems (such as polyurethane dispersions), for thermosensitive dispersions.
  • shear-sensitive dispersions for example low-emulsifier or emulsifier-free formulations, sterically (with protective colloid or with starch) stabilized dispersions or self-dispersing systems (such as polyurethane dispersions), for thermosensitive dispersions.
  • stage a the reactor (A) comes to
  • Stage e) is carried out in the relaxation stage (E), stage f) in the filter
  • the assembly includes all the necessary steps that are necessary to complete the
  • antioxidants for example, stabilizers, antioxidants, and others.
  • Solvents, dispersants such as water, and other suitable substances can be added.
  • the polymer dispersions according to the invention are preferably used as adhesive raw materials, in sealing compounds, paper coating dispersions, plastering compounds, fillers, coatings, as lacquer and paint raw materials, binders or thickeners, in particular for interior applications. Due to the low content of residual volatiles, safe use in indoor applications is possible, with no or minimal evaporation of the remaining minimal amounts of residual volatiles.
  • foils such as glossy, metal or composite foils made of copper and / or aluminum and paper
  • technical laminations for example in vehicle construction, for foams or furniture foils
  • packaging adhesives as pressure sensitive adhesives, for example for paper labels and envelopes, as sealants and floor adhesives, as well as for special coatings and as binders.
  • They can be used as paper coating dispersions for the finishing of offset printing paper, gravure printing paper and cardboard. They can also be used as thickeners for printing inks and coating slips.
  • paint and varnish raw materials they are used for wood coatings, for the graphic industry, for technical paint applications such as corrosion protection, for emulsion paints and emulsion paints, for example for interior and exterior paints, especially for interior paints, for plasters and fillers for interior use. for cement coatings such as primers, facade paints and concrete roof tiles.
  • nonwoven coating compositions such as tufting, needle fleece and floor coverings or the carpet backing, as well as for molded foams and diving articles.
  • These applications preferably relate to interior applications, that is to say applications within closed buildings or vehicles.
  • the column (diameter 0.4 m) contains 8 cross-flow sieve trays at a distance of 50 cm from each other.
  • the sieve trays have holes with a diameter of 4 mm at a uniform distance. The holes make up 1.0% of the floor area.
  • the floors are connected to one another via laterally arranged shafts.
  • the respective drain shaft extends 40 mm above the floor. This creates a dispersion layer of this height (40 mm) on the floor during operation caused by the water vapor.
  • This column was fed with 0.2 t / h of a 50% aqueous polymer dispersion which was conveyed to the top sieve tray by means of an eccentric screw pump. In countercurrent, 40 kg / h of 4 bar steam were introduced into the column below the bottom tray.
  • dispersion runs over the 40 mm high overflow weir through the shaft to the next floor and so on.
  • the steam flows through the holes in the bottom floor, flows through the dispersion layer and thereby accumulates with the substances to be separated from the dispersion.
  • the floors above are flowed through in the same way.
  • the loaded one is at the top of the column Steam is drawn off using a vacuum (approx. 200 mbar) and condensed in a downstream condenser.
  • the dispersion is collected in a sump below the bottom floor and pumped from there for conditioning.
  • butyl acrylate is depleted from 415 ppm initial concentration to 140 ppm (tray 5). This corresponds to a depletion of 66% or a soil efficiency of around 14% of a thermodynamic equilibrium.
  • the column (diameter 0.4 m) contains 8 cross-flow sieve trays at a distance of 50 cm from each other.
  • the sieve trays have holes with a diameter of 4 mm at a uniform distance. The holes make up 5.3% of the floor area.
  • the floors are connected to each other via shafts. The shafts protrude 100 mm into the floor and form the drain weir.
  • the butyl acrylate content was reduced from 219 ppm at the beginning to 16 ppm, which corresponds to a depletion of 93%.
  • Example 3 Column with rain sieve trays
  • the column (diameter 0.4 m) contains 8 trays at a distance of 50 cm from each other.
  • the sieve trays have holes with a diameter of 10 mm at a uniform distance.
  • the holes make up 2.1% of the floor area.
  • the floors are not connected to one another via manholes. The dispersion flows in countercurrent to the steam through the same holes.
  • the column was charged with 200 kg / h of dispersion (corresponds to a surface load of 1.6 m 3 / m 2 h) from above and stripped with 40 kg / h of steam.
  • the pressure was 285 mbar.
  • the butyl acrylate content was reduced from 477 ppm at the beginning to 5 ppm, which corresponds to a depletion of 99%.
  • the efficiency of these rain screen trays was around 31% of a thermodynamic equilibrium. A significantly better depletion and a considerably higher soil efficiency were found with the preferred rain sieve trays than with the crossflow sieve trays.
  • the soil efficiency ⁇ achieved depends on the throughput related to the free cross-section. At low values (example 12) the efficiency can drop to 7.0%. At high throughputs, over 30% soil efficiency can be achieved regardless of the pressure (Examples 13 to 15).
  • the hole diameter in the crossflow sieve trays (example 4 to 11) is preferably 4 mm. Soil efficiency is affected by weir height and pressure. The column diameter is 400 mm in all examples.
  • the product ⁇ is an adhesive dispersion based on butyl acrylate and acrylonitrile with a solids content of 55%.
  • the product ß is a styrene / butadiene dispersion for paper coating, 50% solids content, 40 mPas viscosity.
  • the product ⁇ is a vinyl acetate-containing PSA dispersion, 70% solids content, 150 to 900 mPas viscosity. 17 is based on butylpropionate for a, ß on styrene and ⁇ on vinyl acetate.
  • FB means the surface loading of the floors with dispersion.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
  • Treating Waste Gases (AREA)
  • Housing For Livestock And Birds (AREA)
  • Gas Separation By Absorption (AREA)

Abstract

Dans une colonne de contre-courant destinée à diminuer la teneur en résidus volatils des dispersions, comprenant entre 5 et 50 tamis à double flux et/ou à flux transversal, la surface libre spécifique des orifices est comprise, pour les tamis à double flux, entre 2 et 25 %, et, pour les tamis à flux transversal, entre 1 et 10 %, et le diamètre moyen des trous est compris, pour les tamis à double flux, entre 10 et 50 mm, et, pour les tamis à flux transversal, entre 2 et 10 mm.
PCT/EP1997/002639 1996-05-24 1997-05-22 Colonne et procede pour desodoriser des dispersions WO1997045184A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BR9709367A BR9709367A (pt) 1996-05-24 1997-05-22 Coluna de contracorrente para abaixar o nível de voláteis residuais em dispersões aparelho para preparar dispersões de polímero processo para preparar dispers es dispersão e uso de dispers es de polímero
AU30916/97A AU3091697A (en) 1996-05-24 1997-05-22 Column and process for deodorising dispersions
EP97925936A EP0907393A1 (fr) 1996-05-24 1997-05-22 Colonne et procede pour desodoriser des dispersions

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE1996121027 DE19621027A1 (de) 1996-05-24 1996-05-24 Verfahren zur Abtrennung flüchtiger organischer Komponenten aus Suspensionen oder Dispersionen
DE19621027.5 1996-05-24
DE19716373.4 1997-04-18
DE1997116373 DE19716373A1 (de) 1997-04-18 1997-04-18 Kolonne und Verfahren zur Desodorierung von Dispersionen

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KR (1) KR20000015969A (fr)
CN (1) CN1226181A (fr)
AU (1) AU3091697A (fr)
BR (1) BR9709367A (fr)
CO (1) CO4990982A1 (fr)
ID (1) ID16979A (fr)
TR (1) TR199802417T2 (fr)
WO (1) WO1997045184A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000021632A1 (fr) * 1998-10-13 2000-04-20 Basf Aktiengesellschaft Tube de strippage a contre-courant
EP1029573A2 (fr) * 1999-02-18 2000-08-23 Nippon Shokubai Co., Ltd. Plateau perforé sans conduite de descente, plateau de distillation perforé sans conduite de descente et procédé de distillation
WO2000053561A1 (fr) * 1999-03-06 2000-09-14 Basf Aktiengesellschaft Condensation fractionnee d'un melange gazeux produit contenant de l'acide acrylique
EP1234865A3 (fr) * 2001-02-24 2004-01-07 Tesa AG Adhésifs acryliques à faible embuage
US6740691B1 (en) 1999-06-18 2004-05-25 National Starch And Chemical Investment Holding Corporation Removal of volatile organic compounds from polymer dispersions
DE102011087138A1 (de) 2011-11-25 2013-05-29 Wacker Chemie Ag Verfahren zur Herstellung von wässrigen Polymerdispersionen

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DE102011081828A1 (de) * 2011-08-30 2013-02-28 Evonik Degussa Gmbh Verfahren zur Umsetzung von Methylmercaptopropionaldehyd aus Roh-Acrolein und Roh-Methylmercaptan
MX2014002250A (es) * 2011-08-30 2014-04-25 Evonik Degussa Gmbh Metodo para producir una sal de metionina.
CN109758790B (zh) * 2017-11-09 2021-06-29 万华化学集团股份有限公司 一种去除丙烯酸乳液中挥发性有机化合物的装置与方法
CN108654124B (zh) * 2018-05-31 2020-11-24 万华化学集团股份有限公司 一种脱除乳液中挥发性有机化合物的装置及方法
KR102577183B1 (ko) * 2019-12-30 2023-09-11 한화솔루션 주식회사 증류장치 및 증류방법
CN113234363A (zh) * 2021-05-11 2021-08-10 广东米奇涂料有限公司 一种儿童墙面漆及其制备方法

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BE668280A (fr) * 1964-08-24 1966-02-14
FR2346377A1 (fr) * 1976-04-03 1977-10-28 Shinetsu Chemical Co Procede et installation pour l'elimination de chlorure de vinyle non transforme dans du pvc
FR2364230A1 (fr) * 1976-09-09 1978-04-07 Hoechst Ag Procede pour l'elimination continue des monomeres contenus dans des dispersions aqueuses de polymeres, notamment de chlorure de polyvinyle
US5382390A (en) * 1990-09-10 1995-01-17 Uop Multiple-downcomer fractionation tray with vapor directing slots and extended downcomer baffles

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BE668280A (fr) * 1964-08-24 1966-02-14
FR2346377A1 (fr) * 1976-04-03 1977-10-28 Shinetsu Chemical Co Procede et installation pour l'elimination de chlorure de vinyle non transforme dans du pvc
FR2364230A1 (fr) * 1976-09-09 1978-04-07 Hoechst Ag Procede pour l'elimination continue des monomeres contenus dans des dispersions aqueuses de polymeres, notamment de chlorure de polyvinyle
US5382390A (en) * 1990-09-10 1995-01-17 Uop Multiple-downcomer fractionation tray with vapor directing slots and extended downcomer baffles

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000021632A1 (fr) * 1998-10-13 2000-04-20 Basf Aktiengesellschaft Tube de strippage a contre-courant
US7238773B2 (en) 1998-10-13 2007-07-03 Basf Aktiengesellschaft Countercurrent stripping pipe
US6875406B1 (en) 1998-10-13 2005-04-05 Basf Aktiengesellschaft Counterflow stripping tube
EP1029573A3 (fr) * 1999-02-18 2000-11-02 Nippon Shokubai Co., Ltd. Plateau perforé sans conduite de descente, plateau de distillation perforé sans conduite de descente et procédé de distillation
US6755943B1 (en) 1999-02-18 2004-06-29 Nippon Shokubai Co., Ltd. Perforated tray without downcomer, perforated tray tower without downcomer
EP1029573A2 (fr) * 1999-02-18 2000-08-23 Nippon Shokubai Co., Ltd. Plateau perforé sans conduite de descente, plateau de distillation perforé sans conduite de descente et procédé de distillation
JP2002539105A (ja) * 1999-03-06 2002-11-19 ビーエーエスエフ アクチェンゲゼルシャフト アクリル酸含有生成物ガス混合物の分別凝縮
US6679939B1 (en) 1999-03-06 2004-01-20 Basf Aktiengesellschaft Fractional condensation of a product gas mixture containing acrylic acid
WO2000053561A1 (fr) * 1999-03-06 2000-09-14 Basf Aktiengesellschaft Condensation fractionnee d'un melange gazeux produit contenant de l'acide acrylique
US6740691B1 (en) 1999-06-18 2004-05-25 National Starch And Chemical Investment Holding Corporation Removal of volatile organic compounds from polymer dispersions
EP1234865A3 (fr) * 2001-02-24 2004-01-07 Tesa AG Adhésifs acryliques à faible embuage
US7510764B2 (en) 2001-02-24 2009-03-31 Tesa Ag Low-outgassing acrylic pressure-sensitive adhesive compositions
DE102011087138A1 (de) 2011-11-25 2013-05-29 Wacker Chemie Ag Verfahren zur Herstellung von wässrigen Polymerdispersionen
WO2013076264A1 (fr) 2011-11-25 2013-05-30 Wacker Chemie Ag Procédé de production de dispersions polymères aqueuses

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TR199802417T2 (xx) 1999-03-22
BR9709367A (pt) 1999-08-10
CO4990982A1 (es) 2000-12-26
EP0907393A1 (fr) 1999-04-14
ID16979A (id) 1997-11-27
CN1226181A (zh) 1999-08-18
AU3091697A (en) 1998-01-05
KR20000015969A (ko) 2000-03-25

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