CA1274942A - Acrylic acid polymerization - Google Patents
Acrylic acid polymerizationInfo
- Publication number
- CA1274942A CA1274942A CA000518311A CA518311A CA1274942A CA 1274942 A CA1274942 A CA 1274942A CA 000518311 A CA000518311 A CA 000518311A CA 518311 A CA518311 A CA 518311A CA 1274942 A CA1274942 A CA 1274942A
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- Canada
- Prior art keywords
- polymerization
- carbon dioxide
- initiator
- percent
- carried out
- Prior art date
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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
- C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
- C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
- C08F20/04—Acids, Metal salts or ammonium salts thereof
- C08F20/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
Abstract
ABSTRACT OF THE DISCLOSURE:
The instant invention is directed to a process for preparing acrylic acid and methyacrylic acid polymer. This process comprises polymerizing acrylic acid in a polymerization zone in carbon dioxide in the presence of a catalyst. The reaction is advantageously carried out at a temperature and pressure at which the carbon dioxide is in a supercritical state.
The instant invention is directed to a process for preparing acrylic acid and methyacrylic acid polymer. This process comprises polymerizing acrylic acid in a polymerization zone in carbon dioxide in the presence of a catalyst. The reaction is advantageously carried out at a temperature and pressure at which the carbon dioxide is in a supercritical state.
Description
~27~
ACRYLIC ACTD POLYMERIZATION
Background of the Invention This invention relates to a process for homo-polymerizing monoethylenically unsaturated C3 to C5 car-boxylic acids and more specifically to homopolymerization in carbon dioxide.
It is well known in the art to produce polymers by dispersing the starting monomer in a liquid solvent. One of the major disadvantages of conventional liquid solvents is that they are relatively costly and generally must be removed from the final product. Accordingly, it is a purpose of the in~tant invention to provide a process for polymerizing the above carboxylic acids which greatly facilitate~ the separation of the polymer from any ~olvents or reaction media.
The ~ournal of Organic Chemi~tr~, 1984, vol. 49, pages 5097 to 5101, discloses the use oE liquid and super-critical carbon dioxide as a solvent for various organic compounds. It includes a relatively long table illustrating solubilitie~ of various organic compound~ in li~uid CO2 and indicates that most of those that are soluble in liquid CO2 are also soluble in supercritical carbon dioxide.
U.S. Patent 3,294,772 discloses polymerization of l-olefins containing from 3 to 8 carbon atoms u~ing the olefin itself as a solvent under supercritical conditions ~i b and in the absence of any additional solvent. Polymeriza-tion is then followed by lowering the ~upercritical pressure while retaining the olefin in fluid form to precipitate only the crystalline portion of the olefin composition main-taining the non-crystalline portion in solution followed by fractionation.
U.S. Patent ~,250,331 discloses an extraction process using supercritical carbon dioxide by itself or with another supercritical gas to react with a salt of a car~
boxylic acid in aqueous medium to produce the carboxylic acid which separates from the aqueous phase and dissolves in the ~upercritical gas phase. In this patent, the carbon dioxide i~ used as a solvent but also as a reactant to convert a salt of a carboxylic acid to produce the organic acid itself.
Summary of the Invention The instant invention i9 directed to a process for preparing homopolymers of C3-C5 monoethylenically unsatu-rated carboxylic acid preferably acrylic acid and methy-acrylic acid, crotonic acid, alpha-methyl crotonic acid, alphaethylacrylic acid, dimethyl acrylic acid, alpha-chloro acrylic acid and vinyl lactic acid. A~ used throughout the instant ~pecification and claims, excepting the examples, the expression "acrylic acid" includes methacrylic acid.
This process comprise~ polymerizing the carboxylic acid in a ~7~
polymerization zone in fluid carbon dioxide in the presence of an initiator or catalyst.
In the following specification, the words "initiator" and "catalys-t" are used interchangeably.
Henceforth, only the word "initiator" will be employed.
In the following specification, the reaction is also disclosed as being carried out in fluid carbon dioxide, i.e. in carbon dioxide in a liquid or supercritical state.
The invention as claimed hereinafter is however restricted to the process where the reaction is carried in carbon dioxide in a supercritical state, exclusively. This of course means that the reaction is carried out at a temperature and pressure at which the carbon dioxide is in such a supercritical state.
~ supercritical fluid exists as a form of matter in which its liquid and gaseous states are indistinguishable from one another. The critical temperature of the fluid is the temperature above which that fluid cannot be liquefied by an increase in pressure. The critical pressure of a fluid is simply the pressure of the fluid at its critical temperature. Carbon dioxide is a supercritical fluid when its temperature exceeds 31C and the pressure exceeds 73 atmospheres (about 1070 psi).
Fluid carbon dioxide has the advantage as a reaction medium, that it is neither toxic nor flammable, is relatively inexpensive and may be removed from the polymer at low -temper-tures.
De crlption of the Preferred Enbodimen-ts In accordance with a preferred embodiment of the instant invention the carboxylic acid is polymerized by charging the acid, liquid CO2, and ini-tiator to a high pressure reaction vessel and heating to initiate polymeriza- _ tion. The mixture is allowed to react for a period of ~rom about 0.25 to 5 hours depending on the rate of polymeriza-tion desired. It has been found that the instant process can be most practical in producing acrylic acid polymers having a molecular weight of from about 1000 to 1,000,000.
At the end of the reaction period the pressure in the reaction vessel is reduced to atmospheric leaving a solid, water-soluble acrylic acid polyrner and catalyst residue, the carbon dioxide going off as a gas. A preferred initiator is
ACRYLIC ACTD POLYMERIZATION
Background of the Invention This invention relates to a process for homo-polymerizing monoethylenically unsaturated C3 to C5 car-boxylic acids and more specifically to homopolymerization in carbon dioxide.
It is well known in the art to produce polymers by dispersing the starting monomer in a liquid solvent. One of the major disadvantages of conventional liquid solvents is that they are relatively costly and generally must be removed from the final product. Accordingly, it is a purpose of the in~tant invention to provide a process for polymerizing the above carboxylic acids which greatly facilitate~ the separation of the polymer from any ~olvents or reaction media.
The ~ournal of Organic Chemi~tr~, 1984, vol. 49, pages 5097 to 5101, discloses the use oE liquid and super-critical carbon dioxide as a solvent for various organic compounds. It includes a relatively long table illustrating solubilitie~ of various organic compound~ in li~uid CO2 and indicates that most of those that are soluble in liquid CO2 are also soluble in supercritical carbon dioxide.
U.S. Patent 3,294,772 discloses polymerization of l-olefins containing from 3 to 8 carbon atoms u~ing the olefin itself as a solvent under supercritical conditions ~i b and in the absence of any additional solvent. Polymeriza-tion is then followed by lowering the ~upercritical pressure while retaining the olefin in fluid form to precipitate only the crystalline portion of the olefin composition main-taining the non-crystalline portion in solution followed by fractionation.
U.S. Patent ~,250,331 discloses an extraction process using supercritical carbon dioxide by itself or with another supercritical gas to react with a salt of a car~
boxylic acid in aqueous medium to produce the carboxylic acid which separates from the aqueous phase and dissolves in the ~upercritical gas phase. In this patent, the carbon dioxide i~ used as a solvent but also as a reactant to convert a salt of a carboxylic acid to produce the organic acid itself.
Summary of the Invention The instant invention i9 directed to a process for preparing homopolymers of C3-C5 monoethylenically unsatu-rated carboxylic acid preferably acrylic acid and methy-acrylic acid, crotonic acid, alpha-methyl crotonic acid, alphaethylacrylic acid, dimethyl acrylic acid, alpha-chloro acrylic acid and vinyl lactic acid. A~ used throughout the instant ~pecification and claims, excepting the examples, the expression "acrylic acid" includes methacrylic acid.
This process comprise~ polymerizing the carboxylic acid in a ~7~
polymerization zone in fluid carbon dioxide in the presence of an initiator or catalyst.
In the following specification, the words "initiator" and "catalys-t" are used interchangeably.
Henceforth, only the word "initiator" will be employed.
In the following specification, the reaction is also disclosed as being carried out in fluid carbon dioxide, i.e. in carbon dioxide in a liquid or supercritical state.
The invention as claimed hereinafter is however restricted to the process where the reaction is carried in carbon dioxide in a supercritical state, exclusively. This of course means that the reaction is carried out at a temperature and pressure at which the carbon dioxide is in such a supercritical state.
~ supercritical fluid exists as a form of matter in which its liquid and gaseous states are indistinguishable from one another. The critical temperature of the fluid is the temperature above which that fluid cannot be liquefied by an increase in pressure. The critical pressure of a fluid is simply the pressure of the fluid at its critical temperature. Carbon dioxide is a supercritical fluid when its temperature exceeds 31C and the pressure exceeds 73 atmospheres (about 1070 psi).
Fluid carbon dioxide has the advantage as a reaction medium, that it is neither toxic nor flammable, is relatively inexpensive and may be removed from the polymer at low -temper-tures.
De crlption of the Preferred Enbodimen-ts In accordance with a preferred embodiment of the instant invention the carboxylic acid is polymerized by charging the acid, liquid CO2, and ini-tiator to a high pressure reaction vessel and heating to initiate polymeriza- _ tion. The mixture is allowed to react for a period of ~rom about 0.25 to 5 hours depending on the rate of polymeriza-tion desired. It has been found that the instant process can be most practical in producing acrylic acid polymers having a molecular weight of from about 1000 to 1,000,000.
At the end of the reaction period the pressure in the reaction vessel is reduced to atmospheric leaving a solid, water-soluble acrylic acid polyrner and catalyst residue, the carbon dioxide going off as a gas. A preferred initiator is
2-t-butylazo-2-cyanobutane. Other pre~erred initiators are 2,2'-aæobis-(2-methylbutyronitrile), t-butylhydroperoxide and benzylperoxide. Other initiators that may be employed are hydrogen peroxide, persulfates, benzyolperoxides, methyl ethyl ketone peroxide, perphthalic acid, and perbenzoic acid.
Liquid carbon dioxide may be obtained at ~emper-atures as low a~ -55C and pressure~ as low as 77 psi and there are po~sible way~ to initiate polymerization at low temperatures such as the use of peroxide initiators.
Preferably the minimum temperature i~ about -15C and the minimum pressure is about 335 psi. Since the liquid carbon dioxide char~ed is often at very low temperatures it may be necessary in order to initiate polymerization to heat the carbon dioxide.
-- ar --Suitable free-radical initiators are all free-radical donors which have a half~ e of <3 hours at the temperatures selected~ If, for example, polymerization is started at a low temperature and completed at a higher temperature, two or more initiators have to be used. By way of example, the following initiators are suitable at the stated polymerization temperatures:
50 to 60C:
acetylcyclohexanesulfonyl peroxide, diacetyl peroxydicarbo-nate, dicyclohexyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, tert.-butyl perneodecanoate and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 70 to 80C
. .
tert.-butyl perpivalate, dioctanoyl peroxide, dilauroyl peroxide and 2,2'-azobis(2,4-dimethylvaleronitrile), tert.-butylazo-2-cyanobutane, 90 to lOO~C:
dibenzoyl peroxide, tert.-butyl per-2-ethylhexanoate, tert.-butyl permaleate and 2,2-azobls(isobutyronitrile), 110 to 120:
bis(tert.-butylperoxy)cyclohexane, tert.-butyl peroxyiso-propylcarhonate and tert.-butyl peracetate, 9~L~
130 to 140C:
2,2-bis(tert.-butylperoxy)butane, dicumyl peroxide, ditert.-amyl peroxide and di-tert.-butyl peroxide, .
p-menthane hydroperoxide, pinane hydroperoxide, cumene hydroperoxide and tert.-butyl hydroperoxide.
By concomitantly using redox coinitiators, for example benzoin, dimethylaniline or complexes or salts, which are soluble in organic solvents of heavy metals, such as copper, cobalt, manganese, iron, nickel or chromium, the half-lives of the stated peroxides, particularly the hydroperoxides, can be reduced, so that, for example, tert.-butyl hydroperoxide in the presence of 5 ppm of copper(II) acetylacetonate is effective at as low as 100C.
Polymerization may be carried out in the presence of from about 0.05 to 10 percent, preferably about 0.1 to 5 percent by weight of polymerization regulators. Examples of suitable regulators are 2-rnercaptoethanol, mercaptopro-panol3, mercaptobutanols, n~dodecylmercaptan, tert,-dodecyl-mercaptan, thioglycolic acid and thiophenol.
The reaction is generally carried out in a pres3ure vessel and since the reaction i9 exothermic the temperature i9 subsequently controlled by cooling. Exces-sively high temperatures may result in some degree of decomposition and crosslinking, rendering the polymer ~27~
insoluble in solvents. Accordingly, it is preferred to control the tempera~ure at a maximum of 140C and preferably a maximum of 85C and in general the pressure should not exceed 4500 psi.
It is preferred that the reaction composition contain from about 1 to 50 percent carboxylic acid, about 50 to 95 percent CO2, and about 0.1 to 0.7 percent initiator.
It is most preferred that the composition contain about 10 to about ~0 percent carboxylic acid, about 60 to about 90 percent carbon dioxide and about 0.1 to about 0.3 percent initiator.
For batch processing the reaction may be carried out in any reactor capable of sustaining high pressures which is provided with adequate heating and cooling means.
However, continuous processing methods are also pos~ible. A
continuous process is illustrated in the drawing which is a schematic view of one continuous process embodying the principles of the invention.
With reEerence more particularly to the drawing carbon dioxide i,s introduced into reactor 1 through conduit
Liquid carbon dioxide may be obtained at ~emper-atures as low a~ -55C and pressure~ as low as 77 psi and there are po~sible way~ to initiate polymerization at low temperatures such as the use of peroxide initiators.
Preferably the minimum temperature i~ about -15C and the minimum pressure is about 335 psi. Since the liquid carbon dioxide char~ed is often at very low temperatures it may be necessary in order to initiate polymerization to heat the carbon dioxide.
-- ar --Suitable free-radical initiators are all free-radical donors which have a half~ e of <3 hours at the temperatures selected~ If, for example, polymerization is started at a low temperature and completed at a higher temperature, two or more initiators have to be used. By way of example, the following initiators are suitable at the stated polymerization temperatures:
50 to 60C:
acetylcyclohexanesulfonyl peroxide, diacetyl peroxydicarbo-nate, dicyclohexyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, tert.-butyl perneodecanoate and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 70 to 80C
. .
tert.-butyl perpivalate, dioctanoyl peroxide, dilauroyl peroxide and 2,2'-azobis(2,4-dimethylvaleronitrile), tert.-butylazo-2-cyanobutane, 90 to lOO~C:
dibenzoyl peroxide, tert.-butyl per-2-ethylhexanoate, tert.-butyl permaleate and 2,2-azobls(isobutyronitrile), 110 to 120:
bis(tert.-butylperoxy)cyclohexane, tert.-butyl peroxyiso-propylcarhonate and tert.-butyl peracetate, 9~L~
130 to 140C:
2,2-bis(tert.-butylperoxy)butane, dicumyl peroxide, ditert.-amyl peroxide and di-tert.-butyl peroxide, .
p-menthane hydroperoxide, pinane hydroperoxide, cumene hydroperoxide and tert.-butyl hydroperoxide.
By concomitantly using redox coinitiators, for example benzoin, dimethylaniline or complexes or salts, which are soluble in organic solvents of heavy metals, such as copper, cobalt, manganese, iron, nickel or chromium, the half-lives of the stated peroxides, particularly the hydroperoxides, can be reduced, so that, for example, tert.-butyl hydroperoxide in the presence of 5 ppm of copper(II) acetylacetonate is effective at as low as 100C.
Polymerization may be carried out in the presence of from about 0.05 to 10 percent, preferably about 0.1 to 5 percent by weight of polymerization regulators. Examples of suitable regulators are 2-rnercaptoethanol, mercaptopro-panol3, mercaptobutanols, n~dodecylmercaptan, tert,-dodecyl-mercaptan, thioglycolic acid and thiophenol.
The reaction is generally carried out in a pres3ure vessel and since the reaction i9 exothermic the temperature i9 subsequently controlled by cooling. Exces-sively high temperatures may result in some degree of decomposition and crosslinking, rendering the polymer ~27~
insoluble in solvents. Accordingly, it is preferred to control the tempera~ure at a maximum of 140C and preferably a maximum of 85C and in general the pressure should not exceed 4500 psi.
It is preferred that the reaction composition contain from about 1 to 50 percent carboxylic acid, about 50 to 95 percent CO2, and about 0.1 to 0.7 percent initiator.
It is most preferred that the composition contain about 10 to about ~0 percent carboxylic acid, about 60 to about 90 percent carbon dioxide and about 0.1 to about 0.3 percent initiator.
For batch processing the reaction may be carried out in any reactor capable of sustaining high pressures which is provided with adequate heating and cooling means.
However, continuous processing methods are also pos~ible. A
continuous process is illustrated in the drawing which is a schematic view of one continuous process embodying the principles of the invention.
With reEerence more particularly to the drawing carbon dioxide i,s introduced into reactor 1 through conduit
3. Acrylic acid is metered into conduit 3 through conduit 5 and initiator i.s metered into conduit 3 through conduit 7.
Pressure is maintained in conduit 3 and reactor 1 by means of carbon dioxide compressor 9. The reactor 1 may simply be a length of pipe with internal baffling to provide for mixing of the reactants. The temperature in the reactor i~
controlled by means of a jacket 11 supplied with heating and cooling fluids through conduit 13 which fluid exits through conduit 15. In order to initiate polymerization, the reaction mixture i3 heated in the reactor 1 by mean~ of a hot fluid pa~sing through the jacket 11. As the reaction proceeds it becomes exothermic and then it is necessary to cool the reaction by means of the fluid passing through jacket 11.
One means for accomplishing heating and cooling is to employ water as the cooling fluid entering through a conduit 17. One means for providing the necessary initial heat, is by injecting steam into the water in conduit 17 ~rom a conduit 19 by means of a steam injection device 21.
After the reaction becomes exothermic and self sustaining, little or no steam may be re~uired since the primary purpose of the fluid in the jacket at this time is to malntain the reaction mass at optimum temperature. All this ~ay be accomplished by rneans of a main control valve 23 and a steam control valve 25 which are controlled by a controller 27 connected to valves 23 and 25 by suitable means such aq pneumatic or electrical connections 29 and 31. The con-troller 27 .in turn is actuated by a temperature sensitive device (not shown) in the exit conduit 33 from the reactor 1 which temperature sensitive device is connected to the controller 27 by suitable means, i e., electrical, pneu-matic, etc., 35.
The product is continuously removed from the reactor 1 to one or more storage vessels ~hrough conduit 33. To permit continuous operation of the reactor 1, it is desirable to employ multiple storage tanks, for example three storage tanks 37, 39, and 41, provided with conduits 43, 45, and 47 respectively connected to conduit 33 through valves 49, 51, and 53. The product is continuously removed from the reactor to the ~torage vessels where the pressure is reduced to atmospheric. At atmospheric pressure the C02 vaporiæes leaving behind solid product. Accord-ingly, the multiple storage tanks 37, 39, and 41 are equipped with conduits 43, 45, and 47 and valves 49, 51, and 53 whereby the storage tanks may be used in rotation. Thus product can be transferred into one of the tanks, Eor example tank 37, with valve 49 open while valves 51 and 53 are clo~ed to permit removal of the solid product from the other two tanks. The tanks are then used in rotation. Thus there is always a tank available to receive the product.
Spray nozzles 50, 52 and 5~ are provided in the tan~cs and the design of the spray nozzles can be such as to obtain a specific particle size of the polyacrylic acid product. The spray nozzle itself may act a3 a pressure reducing device whereby pressure in excess of 335 psi i3 maintained in the _ g _ reactor 1 and the conduits 33, 43, 45, and 47 on the supply side of the nozzles while tha pressure is atmospheric in the tanks 37, 39, and 41. If the nozzles do not provide sufficient resistance to maintain the desired pressure in the reactor 1, a suitable conventional pressure reducing valve (not shown) may be provided in conduit 33 or three of them may be provided in conduits 43, 45, and 47, all as well known to those skilled in the art.
The carbon dioxide vapor returns to the system from the tank~ through conduits 55, 57, and 59 and valves 61, 63, and 65 into conduit 67 to compressor 9 where it is compressed. The compressed carbon dioxide then pas~es through conduit 71 into supply conduit 3. Make up carbon dioxide and catalyst are added to the system as needed through valve 73.
The homopolymer~ of ethylenically unsatu-rated C3- to C5-carboxylic acids have many uses, for example, sizing agents in the textile industry, auxiliaries in the paper industry for improving the dry-strength of paper and as ingredients in detergents.
Urlle~s otherwise stated, throughout the instant specification and claim~, all temperature~ are in C and all percentages are by weight.
The following examples are provided in order to better illustrate the instant invention.
The molecular weight given in the Exampl~s was measured by gel permeation chromatography ~GPC) with aqueous elution agents. The separating columns were calibrated with polystyrene sulphonates having a narrow molecular weight distribution and supplied by Pressure Chem. Co., and the calibration was converted to the molecular weight of sodium polyacrylat~ on the aENoIT principle (J. Chim. Phys. 63 (1966) 1507) with the aid oE the SPATORICO and BEYER
mea3uring data (J. Appl. Polym. Sci. 19 (1975) 2933).
7~
Examples 1-3 In each of the three examples, the amount of carbon dio~ide in gram~ ~hown in the table below wa~ charged to a 300-milliliter stainless steel autoclave equipped with an agitator, cooling coil, and electrical heating means.
The C02 waq then heated to the reaction temperature indi-cated in the table in C which re ulted in the respective reactor pressures set forth in the table. Acrylic acid in the amounts in grams shown in the Table along with a liquid initiator, al~o in the amount~ in grams shown in the Table, were then charged and the tertiary mixture allowed to react. The initiator employed was Luazo*82 2-t-butylazo-2--cyanobutane. ~ue to the exothermic condition, temperature and pressure increa~ed to the values ~hown in the Table below. After reacting for 3 hours, the vessel was vented to remove the C02 and the pressure in the reaction ve~el wa~
reduced to atmo~pheric leaving a solid, water-soluble acrylic acid polymer having a molecular weight of about 10, ooo.
TA~LE
Acrylic Reaction Exotherm Reactor Exotherm Example C0~ Acid Initiator Temp. Temp~ Press. Press.
1 ~ ~ )_ ~ ~ (C) ~ (llm) (2aOtSm) 2 155 20.6 0.50 80 83 205 270 3 160 10.0 0.20 78 ~3 290 300 * trademark It will be noted that the exotherm temperature for Example 1 exceeded the maximum set forth above. The product also showed some slight signs o~ c3eterioration in Example 1. Accordingly, the exotherm temperature was controlled more carefully for Examples 2 and 3 through the use of the cooling coil, as shown in the Table above.
Example ~
Example 2 is repeated employing the continuous process and apparatus shown in the attached drawing and described above. A solid, water-soluble acrylic acid polymer powder having a molecular weight of about 10,000 is produced.
Example 5 Thirty grams of acrylic acid, 0.3 g of tertiary-butyl-per-2-ethylhexanoate and 120 g of liquid carbon dioxide were placed in a 300 ml autoclave equipped with a stirrer and electrical heating means. The autoclave was then sealed, the contents were ~tirred and heated to a temperature of 80C. The polymerization wa~C3 carried out at 80C for five ilours~ A pressure of 1~0 bar was meac3ured under the reaction conditions~ The pressure was then released and a ~ine powder of a water-soluble polyacrylic acid having a molecular weight of 500,000 was obtained. The polyacrylic acid can be used as an agent for improving the dry strength of paper.
~2~ L2 Example 6 Example 5 was repeated, except that the polymer-ization was carried out at 90C. A pressure of 185 bar was measured and a water-soluble polyacrylic acid having a molecular weight of 550,000 in the form of a fine powder was obtained.
Example 7 Thirty gramq of acrylic acid, 0.9 g of tertiary-butyl perbenzoate, 0.1 g of 2-mercaptoethanol and 300 g of liquid carbon dioxide were placed in a 300 ml autoclave equipped with a stirrer and electrical heating means which was then sealed. The contents of the autoclave were then stirred and heated to a temperature of 120C. Thi~ tempera-ture was kept constant for five hours, the pre~sure being 230 bar. ThereaEter the pres~ure in the autoclave was reduced to atmospheric, leaving a solid, water-soluble polyacrylic acid having a molecular weight of 100,000.
The polymer can be u~ed in detergents as a sub~titute for sodium tripolypho~phate.
Example a Fifteen gram~ of methacrylic acid, 0.15 g of tertiary-butyl per-2-ethyl-hexanoate and 135 g of liquid carbon dioxide were placed in a 300 ml autoclave equipped with a ~tirrer and electrical heating mean~ which wa~ then ~ealed. The contents of the autoclave were stirred and ~%7~
heated at 80C and kept at the temperature for five hours, the pressure being 160 bar~ The pressure was then re leased. A fine powder of water-soluble polymethacrylic acid having a molecular weight of 100,000 was obtained. The polymer can be used in detergents as a substitute for sodium tripolyphosphate.
Exam~le 9 Eight hundred grams of liquid carbon dioxide were introduced into a 2.5 liter autoclave equipped with a stirrer, a device for adding liquids and electrical heating means, and the autoclave was sealed. The contents of the autoclave were then heated at 80C. As soon as this temperature was reached, a solution of 2 gram4 of tertiary-butyl per-2-ethylhexanoate in 200 g of acrylic acid was then continuously added to the autoclave over a period of 2.25 hours, the temperature being kept constant at 80C and the pressure being 110 bar. After the addition of the monomer and the initiator, the reaction mixture wa~ kept for two hours at 80C. The pressure was then released, a flaky white volu~inous powder of polyacrylic acid having a molecular weight of 350,000 was obtained. The polymer was soluble in water and can be used as a sizing agent in the textile industry.
Examele 10 The procedure of Example 9 was repeated, except that 700 g of liquid carbon dioxide, 300 g of acrylic acid and 3 g of tertiary-butyl per-2-ethylhexanoate were used, the preqsure being 100 bars. Here again, a flaky white voluminous powder of polyacrylic acid was obtained. I'he molecular weight of the polymer wa~ 400,000.
The polymer obtained was water-soluble and can be used as an auxiliary in the production of dry-strength paperO
Exa~ele 11 The procedure of Example 10 was repeated, except that 450 g of carbon dioxide were used and the addition of acrylic acid and initiator was completed within two hours, the pressure being 85 bars. A lumpy water-qoluble powder of polyacrylic acid having a molecular weight of 350,000 was obtained.
Pressure is maintained in conduit 3 and reactor 1 by means of carbon dioxide compressor 9. The reactor 1 may simply be a length of pipe with internal baffling to provide for mixing of the reactants. The temperature in the reactor i~
controlled by means of a jacket 11 supplied with heating and cooling fluids through conduit 13 which fluid exits through conduit 15. In order to initiate polymerization, the reaction mixture i3 heated in the reactor 1 by mean~ of a hot fluid pa~sing through the jacket 11. As the reaction proceeds it becomes exothermic and then it is necessary to cool the reaction by means of the fluid passing through jacket 11.
One means for accomplishing heating and cooling is to employ water as the cooling fluid entering through a conduit 17. One means for providing the necessary initial heat, is by injecting steam into the water in conduit 17 ~rom a conduit 19 by means of a steam injection device 21.
After the reaction becomes exothermic and self sustaining, little or no steam may be re~uired since the primary purpose of the fluid in the jacket at this time is to malntain the reaction mass at optimum temperature. All this ~ay be accomplished by rneans of a main control valve 23 and a steam control valve 25 which are controlled by a controller 27 connected to valves 23 and 25 by suitable means such aq pneumatic or electrical connections 29 and 31. The con-troller 27 .in turn is actuated by a temperature sensitive device (not shown) in the exit conduit 33 from the reactor 1 which temperature sensitive device is connected to the controller 27 by suitable means, i e., electrical, pneu-matic, etc., 35.
The product is continuously removed from the reactor 1 to one or more storage vessels ~hrough conduit 33. To permit continuous operation of the reactor 1, it is desirable to employ multiple storage tanks, for example three storage tanks 37, 39, and 41, provided with conduits 43, 45, and 47 respectively connected to conduit 33 through valves 49, 51, and 53. The product is continuously removed from the reactor to the ~torage vessels where the pressure is reduced to atmospheric. At atmospheric pressure the C02 vaporiæes leaving behind solid product. Accord-ingly, the multiple storage tanks 37, 39, and 41 are equipped with conduits 43, 45, and 47 and valves 49, 51, and 53 whereby the storage tanks may be used in rotation. Thus product can be transferred into one of the tanks, Eor example tank 37, with valve 49 open while valves 51 and 53 are clo~ed to permit removal of the solid product from the other two tanks. The tanks are then used in rotation. Thus there is always a tank available to receive the product.
Spray nozzles 50, 52 and 5~ are provided in the tan~cs and the design of the spray nozzles can be such as to obtain a specific particle size of the polyacrylic acid product. The spray nozzle itself may act a3 a pressure reducing device whereby pressure in excess of 335 psi i3 maintained in the _ g _ reactor 1 and the conduits 33, 43, 45, and 47 on the supply side of the nozzles while tha pressure is atmospheric in the tanks 37, 39, and 41. If the nozzles do not provide sufficient resistance to maintain the desired pressure in the reactor 1, a suitable conventional pressure reducing valve (not shown) may be provided in conduit 33 or three of them may be provided in conduits 43, 45, and 47, all as well known to those skilled in the art.
The carbon dioxide vapor returns to the system from the tank~ through conduits 55, 57, and 59 and valves 61, 63, and 65 into conduit 67 to compressor 9 where it is compressed. The compressed carbon dioxide then pas~es through conduit 71 into supply conduit 3. Make up carbon dioxide and catalyst are added to the system as needed through valve 73.
The homopolymer~ of ethylenically unsatu-rated C3- to C5-carboxylic acids have many uses, for example, sizing agents in the textile industry, auxiliaries in the paper industry for improving the dry-strength of paper and as ingredients in detergents.
Urlle~s otherwise stated, throughout the instant specification and claim~, all temperature~ are in C and all percentages are by weight.
The following examples are provided in order to better illustrate the instant invention.
The molecular weight given in the Exampl~s was measured by gel permeation chromatography ~GPC) with aqueous elution agents. The separating columns were calibrated with polystyrene sulphonates having a narrow molecular weight distribution and supplied by Pressure Chem. Co., and the calibration was converted to the molecular weight of sodium polyacrylat~ on the aENoIT principle (J. Chim. Phys. 63 (1966) 1507) with the aid oE the SPATORICO and BEYER
mea3uring data (J. Appl. Polym. Sci. 19 (1975) 2933).
7~
Examples 1-3 In each of the three examples, the amount of carbon dio~ide in gram~ ~hown in the table below wa~ charged to a 300-milliliter stainless steel autoclave equipped with an agitator, cooling coil, and electrical heating means.
The C02 waq then heated to the reaction temperature indi-cated in the table in C which re ulted in the respective reactor pressures set forth in the table. Acrylic acid in the amounts in grams shown in the Table along with a liquid initiator, al~o in the amount~ in grams shown in the Table, were then charged and the tertiary mixture allowed to react. The initiator employed was Luazo*82 2-t-butylazo-2--cyanobutane. ~ue to the exothermic condition, temperature and pressure increa~ed to the values ~hown in the Table below. After reacting for 3 hours, the vessel was vented to remove the C02 and the pressure in the reaction ve~el wa~
reduced to atmo~pheric leaving a solid, water-soluble acrylic acid polymer having a molecular weight of about 10, ooo.
TA~LE
Acrylic Reaction Exotherm Reactor Exotherm Example C0~ Acid Initiator Temp. Temp~ Press. Press.
1 ~ ~ )_ ~ ~ (C) ~ (llm) (2aOtSm) 2 155 20.6 0.50 80 83 205 270 3 160 10.0 0.20 78 ~3 290 300 * trademark It will be noted that the exotherm temperature for Example 1 exceeded the maximum set forth above. The product also showed some slight signs o~ c3eterioration in Example 1. Accordingly, the exotherm temperature was controlled more carefully for Examples 2 and 3 through the use of the cooling coil, as shown in the Table above.
Example ~
Example 2 is repeated employing the continuous process and apparatus shown in the attached drawing and described above. A solid, water-soluble acrylic acid polymer powder having a molecular weight of about 10,000 is produced.
Example 5 Thirty grams of acrylic acid, 0.3 g of tertiary-butyl-per-2-ethylhexanoate and 120 g of liquid carbon dioxide were placed in a 300 ml autoclave equipped with a stirrer and electrical heating means. The autoclave was then sealed, the contents were ~tirred and heated to a temperature of 80C. The polymerization wa~C3 carried out at 80C for five ilours~ A pressure of 1~0 bar was meac3ured under the reaction conditions~ The pressure was then released and a ~ine powder of a water-soluble polyacrylic acid having a molecular weight of 500,000 was obtained. The polyacrylic acid can be used as an agent for improving the dry strength of paper.
~2~ L2 Example 6 Example 5 was repeated, except that the polymer-ization was carried out at 90C. A pressure of 185 bar was measured and a water-soluble polyacrylic acid having a molecular weight of 550,000 in the form of a fine powder was obtained.
Example 7 Thirty gramq of acrylic acid, 0.9 g of tertiary-butyl perbenzoate, 0.1 g of 2-mercaptoethanol and 300 g of liquid carbon dioxide were placed in a 300 ml autoclave equipped with a stirrer and electrical heating means which was then sealed. The contents of the autoclave were then stirred and heated to a temperature of 120C. Thi~ tempera-ture was kept constant for five hours, the pre~sure being 230 bar. ThereaEter the pres~ure in the autoclave was reduced to atmospheric, leaving a solid, water-soluble polyacrylic acid having a molecular weight of 100,000.
The polymer can be u~ed in detergents as a sub~titute for sodium tripolypho~phate.
Example a Fifteen gram~ of methacrylic acid, 0.15 g of tertiary-butyl per-2-ethyl-hexanoate and 135 g of liquid carbon dioxide were placed in a 300 ml autoclave equipped with a ~tirrer and electrical heating mean~ which wa~ then ~ealed. The contents of the autoclave were stirred and ~%7~
heated at 80C and kept at the temperature for five hours, the pressure being 160 bar~ The pressure was then re leased. A fine powder of water-soluble polymethacrylic acid having a molecular weight of 100,000 was obtained. The polymer can be used in detergents as a substitute for sodium tripolyphosphate.
Exam~le 9 Eight hundred grams of liquid carbon dioxide were introduced into a 2.5 liter autoclave equipped with a stirrer, a device for adding liquids and electrical heating means, and the autoclave was sealed. The contents of the autoclave were then heated at 80C. As soon as this temperature was reached, a solution of 2 gram4 of tertiary-butyl per-2-ethylhexanoate in 200 g of acrylic acid was then continuously added to the autoclave over a period of 2.25 hours, the temperature being kept constant at 80C and the pressure being 110 bar. After the addition of the monomer and the initiator, the reaction mixture wa~ kept for two hours at 80C. The pressure was then released, a flaky white volu~inous powder of polyacrylic acid having a molecular weight of 350,000 was obtained. The polymer was soluble in water and can be used as a sizing agent in the textile industry.
Examele 10 The procedure of Example 9 was repeated, except that 700 g of liquid carbon dioxide, 300 g of acrylic acid and 3 g of tertiary-butyl per-2-ethylhexanoate were used, the preqsure being 100 bars. Here again, a flaky white voluminous powder of polyacrylic acid was obtained. I'he molecular weight of the polymer wa~ 400,000.
The polymer obtained was water-soluble and can be used as an auxiliary in the production of dry-strength paperO
Exa~ele 11 The procedure of Example 10 was repeated, except that 450 g of carbon dioxide were used and the addition of acrylic acid and initiator was completed within two hours, the pressure being 85 bars. A lumpy water-qoluble powder of polyacrylic acid having a molecular weight of 350,000 was obtained.
Claims (19)
1. A process for preparing homopolymers of monoethylenically unsaturated C3-C5 carboxylic acids by polymerization of said acids in a polymerization zone in carbon dioxide in the presence of an initiator, wherein said polymerization is carried out at a temperature and pressure at which said carbon dioxide is in a supercritical state.
2. The process of claim 1, wherein the polymerization is carried out in a batch reactor.
3. The process of claim 1, wherein the polymerization is carried out in a continuous flow reactor.
4. The process of claim 1, 2 ou 3, wherein said initiator is 2-t-butylazo-2-cyanobutane.
5. The process of claim 1, 2 ou 3, wherein a polymerization regulator is also present.
6. The process of claim 1, wherein the polymerization is carried out with from about 1 to about 50 percent carboxylic acid, about 50 to about 95 percent carbon dioxide, and about 0.1 to about 0.7 percent initiator.
7. The process of claim 6, wherein a polymerization regulator is also present in an amount of about 0.05 to about 10 percent.
8. The process of claim 1, wherein the polymerization is carried out with about 10 to about 40 percent carboxylic acid, about 60 to about 90 percent carbon dioxide, and 0.10 to 0.3 percent initiator.
9. The process of claim 8, wherein said initiator is 2-t-butylazo-2-cyanobutane.
10. The process of claim 8, wherein said initiator is tertiary-butyl per-2-ethylhexanoate.
11. The process of claim 8, 9 or 10, wherein a polymerization regulator is also present in an amount of about 0.1 to 5.0 percent.
12. The process of claim 6, wherein the polymerization temperature is about 31 to 140°C, the polymerization pressure is about 1070 to 4500 psi, and the polymerization time is about 0.25 to 5 hours.
13. The process of claim 12, wherein the polymerization temperature is about 31 to 85°C.
14. The process of claim 6, 12 or 13, wherein said initiator is 2-t-butylazo-2-cyanobutane.
15. The process of claim 6, 12 or 13, wherein said initiator is tertiary-butyl per-2-ethylhexanoate.
16. The process of claim 6, or 13, wherein the carboxylic acid polymer has a molecular weight of from about 1,000 to 1,000,000.
17. The process of claim 12, wherein the carboxylic acid polymer has a molecular weight of from about 1,000 to 1,000,000.
18. The process of claim 6, 12 or 17, wherein the polymerization is carried out in a batch reactor.
19. The process of claim 6, 12 or 17, wherein the polymerization is carried out in a continuous flow reactor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77801385A | 1985-09-20 | 1985-09-20 | |
| US778,013 | 1985-09-20 |
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| Publication Number | Publication Date |
|---|---|
| CA1274942A true CA1274942A (en) | 1990-10-02 |
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ID=25112023
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000518311A Expired - Fee Related CA1274942A (en) | 1985-09-20 | 1986-09-16 | Acrylic acid polymerization |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US5328972A (en) * | 1992-09-28 | 1994-07-12 | Rohm And Haas Company | Process for preparing low molecular weight polymers |
| US5496901A (en) * | 1992-03-27 | 1996-03-05 | University Of North Carolina | Method of making fluoropolymers |
| US5559198A (en) * | 1994-07-08 | 1996-09-24 | Minnesota Mining And Manufacturing Company | Process for preparing poly(vinyl trifluoroacetate) and poly(vinyltrifluoroacetate/vinyl ester) copolymers in supercritical Co.sub. |
| US5688879A (en) * | 1992-03-27 | 1997-11-18 | The University Of North Carolina At Chapel Hill | Method of making fluoropolymers |
| US5780565A (en) * | 1994-07-08 | 1998-07-14 | Minnesota Mining And Manufacturing Company | Supersatmospheric reaction |
| US5863612A (en) * | 1992-03-27 | 1999-01-26 | University North Carolina--Chapel Hill | Method of making fluoropolymers |
| EP0946944A2 (en) * | 1996-07-10 | 1999-10-06 | Commonwealth Edison Company | Polymer dispersants and methods of use in a nuclear steam generator |
| WO2000005273A1 (en) * | 1998-07-23 | 2000-02-03 | Basf Aktiengesellschaft | Method for producing powder-shaped cross-linked polymerizates |
| CN1079099C (en) * | 1998-11-26 | 2002-02-13 | 中国科学院广州化学研究所 | Method for preparing polyacrylic acid in supercritical carbon dioxide medium |
| EP1339755A1 (en) * | 2000-10-09 | 2003-09-03 | University Of North Carolina At Chapel Hill | Methods for preparing polymers in carbon dioxide having reactive functionality |
| US6806332B2 (en) | 1999-11-12 | 2004-10-19 | North Carolina State University | Continuous method and apparatus for separating polymer from a high pressure carbon dioxide fluid stream |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5496901A (en) * | 1992-03-27 | 1996-03-05 | University Of North Carolina | Method of making fluoropolymers |
| US5688879A (en) * | 1992-03-27 | 1997-11-18 | The University Of North Carolina At Chapel Hill | Method of making fluoropolymers |
| US5739223A (en) * | 1992-03-27 | 1998-04-14 | The University Of North Carolina At Chapel Hill | Method of making fluoropolymers |
| US5863612A (en) * | 1992-03-27 | 1999-01-26 | University North Carolina--Chapel Hill | Method of making fluoropolymers |
| US5922833A (en) * | 1992-03-27 | 1999-07-13 | The University Of North Carolina At Chapel Hill | Method of making fluoropolymers |
| US5328972A (en) * | 1992-09-28 | 1994-07-12 | Rohm And Haas Company | Process for preparing low molecular weight polymers |
| US5559198A (en) * | 1994-07-08 | 1996-09-24 | Minnesota Mining And Manufacturing Company | Process for preparing poly(vinyl trifluoroacetate) and poly(vinyltrifluoroacetate/vinyl ester) copolymers in supercritical Co.sub. |
| US5780565A (en) * | 1994-07-08 | 1998-07-14 | Minnesota Mining And Manufacturing Company | Supersatmospheric reaction |
| EP0946944A2 (en) * | 1996-07-10 | 1999-10-06 | Commonwealth Edison Company | Polymer dispersants and methods of use in a nuclear steam generator |
| EP0946944A4 (en) * | 1996-07-10 | 2001-01-03 | Commw Edison Co | Polymer dispersants and methods of use in a nuclear steam generator |
| US6430249B2 (en) | 1996-07-10 | 2002-08-06 | Commonwealth Edison Company | Polymer dispersants and methods of use in a nuclear steam generator |
| WO2000005273A1 (en) * | 1998-07-23 | 2000-02-03 | Basf Aktiengesellschaft | Method for producing powder-shaped cross-linked polymerizates |
| CN1079099C (en) * | 1998-11-26 | 2002-02-13 | 中国科学院广州化学研究所 | Method for preparing polyacrylic acid in supercritical carbon dioxide medium |
| US6806332B2 (en) | 1999-11-12 | 2004-10-19 | North Carolina State University | Continuous method and apparatus for separating polymer from a high pressure carbon dioxide fluid stream |
| US6914105B1 (en) | 1999-11-12 | 2005-07-05 | North Carolina State University | Continuous process for making polymers in carbon dioxide |
| US7410620B2 (en) | 1999-11-12 | 2008-08-12 | North Carolina State University | Apparatus for continuous production of polymers in carbon dioxide |
| EP1339755A1 (en) * | 2000-10-09 | 2003-09-03 | University Of North Carolina At Chapel Hill | Methods for preparing polymers in carbon dioxide having reactive functionality |
| EP1339755A4 (en) * | 2000-10-09 | 2006-03-22 | Univ North Carolina | Methods for preparing polymers in carbon dioxide having reactive functionality |
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