AU2006266498B2

AU2006266498B2 - Chemical process

Info

Publication number: AU2006266498B2
Application number: AU2006266498A
Authority: AU
Inventors: Ulrich Fehrenbacher; Thomas Hirth; Andreas Pingel-Keuth; Christian Przybyla; Oliver Struck; Steffen Unser
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV; Akzo Nobel NV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV; Akzo Nobel NV
Priority date: 2005-06-30
Filing date: 2006-06-09
Publication date: 2010-08-26
Anticipated expiration: 2026-06-09
Also published as: KR20080028446A; NO20080520L; EP1902086A1; RU2399633C2; AU2006266498A1; JP2008545041A; BRPI0613479A2; CA2612134A1; CN101213242A; WO2007004972A1; RU2008103316A; CA2612134C; NZ564123A

Description

WO 2007/004972 PCT/SE2006/050188 1 CHEMICAL PROCESS The present invention relates to a process for the production of an nitrogen containing epihalohydrin polymer from a nitrogen-containing precursor comprising a purification step to remove organic impurities, particularly reaction products of 5 epihalohydrin. The invention further relates to a process for purifying a solution of a nitrogen containing epihalohydrin polymer made from nitrogen-containing precursor from organic impurities. At preparation of epihalohydrin polymers from nitrogen-containing precursors organic by-products may be obtained, some of which frequently are halogenated. Further, 10 unreacted epihalohydrin may also remain in the final product. A typical example is the preparation of polyaminoamide epichlorohydrin polymers that are useful as wet strength resins in paper making. However, many halogenated organic compounds are toxic and/or questionable from an environmental point of view and for many applications, such as paper making, it is desirable to decrease the content thereof. 15 Various purifications methods for removing chlorinated contaminants from polyaminoamide epihalohydrin polymers have been disclosed, for example ion exchange in US 5516885, electrodialysis in US 5643430, ultra-filtration in WO 00/34358, treatment with activated carbon in WO 01/18093, treatment with a base in WO 99/33901 and enzymatic action in WO 02/50163. US 6576687 discloses a method of producing 20 polycondensate solutions based on polyamide amine epichlorohydrin resins claimed to have a very low content of organic chlorine compounds. However, these preparation and purification methods are either complicated to operate or insufficiently effective. It has been disclosed to remove impurities or residual monomers from polymers by extracting with carbon dioxide, see e.g. US 5034132 and US 6180755. It has also 25 been disclosed to extract impurities with carbon dioxide from polymer dispersions, as described in EP 374879. CN 1350795 discloses removal of DCP and MCP from a hydrolytic liquid of plant protein by treating with liquefied or supercritical carbon dioxide. US 2005/0037932 discloses a perfluoropolyether lubricant, the preparation of 30 which includes a supercritical fluid extraction purification step. It is an object of the invention to provide a process for the production of a nitrogen containing epihalohydrin polymer from a nitrogen-containing precursor comprising an effective purification step for removing organic impurities, particularly halogen containing impurities. 35 It is another object of the invention to provide a process for efficiently removing organic impurities, particularly halogen containing impurities, from a solution of a nitrogen containing epihalohydrin polymer made from a nitrogen-containing precursor.

2 It is still another object of the invention to provide for efficient removal of epihalohydrin or reaction products thereof from a solution of a nitrogen containing epihalohydrin polymer without significantly negatively affecting its desired properties. It is a further object of the invention to provide for efficient removal of 1,2-, or 5 1,3-dihalo-2-propanol or 3-halo-1,2-propanediol from a polyaminoamide epihalohydrin polymer without significantly negatively affecting its desired properties. According to the present invention there is provided a process for purifying a solution of a nitrogen containing epihalohydrin polymer formed by reaction of a nitrogen containing precursor selected from amines, poly-amines, polyaminoamides, 1o polyurethanes or mixtures thereof with epihalohydrin comprising the steps of contacting the solution of the epihalohydrin polymer with a fluid under liquid, supercritical or near supercritical conditions to effect extraction of organic impurities from the solution of the epihalohydrin polymer to the fluid, withdrawing fluid enriched in organic impurities from the solution of the epihalohydrin polymer, and separating extracted impurities from the 15 withdrawn fluid, wherein the fluid comprises a substance that at atmospheric pressure and room temperature (about 250C) is gaseous. Another aspect of the invention concerns a process for purifying a solution of a nitrogen containing epihalohydrin polymer formed by reaction of a nitrogen-containing precursor selected from the group consisting of amines, poly-amines, polyaminoamides, 20 polyurethanes and mixtures thereof with epihalohydrin comprising the steps of contacting the solution of the epihalohydrin polymer with a fluid under liquid, supercritical or near supercritical conditions to effect extraction of organic impurities from the solution of the epihalohydrin polymer to the fluid, withdrawing fluid enriched in organic impurities from the solution of the epihalohydrin polymer, and separating 25 extracted impurities from the withdrawn fluid, wherein the fluid comprises a substance that at atmospheric pressure and room temperature (about 25*C) is gaseous. Extracting with a fluid under supercritical or near supercritical conditions has been found to efficiently remove unwanted organic compounds, particularly halogen containing compounds, from the polymer in a comparatively simple procedure without 30 significantly negatively affecting its desired properties, for example as additive in paper making and particularly as wet strength resin. Normally such fluid may also be re-used after separation of the extracted impurities. Preferred fluids are those that have a critical temperature (T) from about 200C to about 100*C, most preferably from about 30*C to 2328312_1 (GHMatters) 6/07110 WO 2007/004972 PCT/SE2006/050188 3 about 60 0 C, and a critical pressure (Por) from about 30 bar to about 500 bar, most preferably from about 70 bar to about 300 bar. Examples of fluids include carbon dioxide, nitrous oxide, ethane, ethane and propane. Carbon dioxide is particularly preferred as it is readily available, non-toxic and non-flammable. Further, carbon dioxide has been found 5 not to give any negative impact to the treated polymer. The fluid may by used in substantially pure form or mixed with small amounts of one or more co-solvents, surfactants, complexing agents or the like. Nitrogen containing epihalohydrin polymers in the process of the present invention include those that have been prepared with epihalohydrin, e.g. epichlorohydrin, 10 as a reactant, either during the polymerisation or in the modification of an existing polymer. The invention is particularly advantageous for nitrogen containing epihalodydrin polymers that are water soluble. Nitrogen containing epihalohydrin polymers include those formed by reactions of nitrogen containing precursors selected from amines, poly-amines, polyaminoamides, 15 polyurethanes and mixtures thereof. Most preferably, the polymers are polyaminoamide epihalohydrin polymers, which also may be referred to as polyamidoamine-epihalohydrin polymers, and are useful as wet strength resins in paper making. Epihalohydrins that can be used include epibromohydrin and epichlorohydrin, preferably epichlorohydrin. Suitably, the polymers are produced using from about 0.5 to about 2 moles of epihalohydrin per mole of 20 basic nitrogen in the nitrogen-containing precursor. The nitrogen-containing precursor is preferably the polyaminoamide reaction product of a polycarboxylic acid or a derivative thereof, suitably a dicarboxylic acid or derivative thereof, and a polyamine. Derivatives of carboxylic acids include e.g. anhydrides, esters and half esters. Suitable poly-carboxylic acids include saturated or unsaturated 25 aliphatic or aromatic dicarboxylic acids. Preferably, the polycarboxylic acids contains less than 10 carbon atoms. Preferred polycarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid and derivatives and mixtures thereof, of which adipic acid is particularly preferred. 30 Preferred polyamines include polyalkylene polyamines, or mixtures thereof, having the following formula:

H

2 N-(CR H)a-(CR 2 H)b-N(R 3

)-(CR

4

H)-(CR

5 H)d-NH 2 (1) in which R 1

-R

5 represent hydrogen or lower alkyl, preferably up to C 3 and a-d represent integers of from 0 to 4. Preferred polyalkylene polyamines include diethylene triamine, tri 35 ethylene tetra amine, tetraethylene penta amine, dipropylene triamine, and mixtures thereof. The polyamines of formula (1) can be combined with other polyamines or mixtures of other amines. Preferably, these amines have any of the following formulae II-VII: WO 2007/004972 PCT/SE2006/050188 4 I I

H-(-NH-(CH

2 )e-CR 6 H-)rNCH 2

CH

2 NH (II)

R

7

R

8

N-(-(CH

2 )g-CR 9

H-(CH

2 )h-N(R )-)i-H (Ill)

HRN-(CH

2 )j-CR 1 2

H-(CH

2 )k-OH (IV) 5 HNRR 13 R (V)

H

2

N-(CH

2 )-COOH (VI) I I

(CH

2 )m-NH-CO (VII) in which R 6

-R

1 4 represent hydrogen or lower alkyl, preferably up to C 3 , e-I represent integers 10 of from 0 to 4, and m represents an integer of from 0 to 5. The polycarboxylic acid and the polyamine may, for example, be applied in a molar ratio from about 1:0.5 to about 1:1.5. The nitrogen-containing epihalohydrin-based polymer is preferably present in an aqueous solution, that further may comprise a water-miscible solvent such as methanol, 15 ethanol or dimethyl formamide. The aqueous polymer solution is preferably prepared from an aqueous solution of a nitrogen-containing precursor. The molecular weights of the polymers are not critical and may, for example, be within the range of from about 50000 to about 1000000 or higher. Preparation of epihalodydrin polymers can be performed by any known process, 20 such as those disclosed in any one of US 4450045, US 3311594, US 4336835, US 3891589, US 2926154, US4857586, US4975499, US5017642, US 5019606 US 5093470 and US 5516885, but additionally including a purification step comprising extraction with a fluid under supercritical or near supercritical conditions as described herein. According to the invention it is also possible to subject commercially or otherwise 25 readily available nitrogen containing epihalohydrin polymers to such a purification step. The solution of the epihalohydrin polymer is preferably an aqueous solution and it has been found that only small amount of water are withdrawn in the purification step. The solids content of the solution to be purified is preferably as high as possible without causing handling problems and can in many cases be as high as about 35 wt% or 30 more, but is preferably from about 5 to about 30 wt%, most preferably from about 10 to about 25 wt%. The viscosity of the solution is preferably from about 1 to about 250 mPas, most preferably from about 5 to about 200 mPas. For example, the viscosity may be from about 1 to about 100 mPas or from about 5 to about 60 mPas. The invention is particularly advantageous for removing halogen containing 35 organic impurities. Halogen containing impurities that can be removed include epihalohydrin as such, particularly epichlorohydrin, and reactions products thereof such as 1,2- and 1,3-dihalo-2-propanol (DXP) and 3-halo-1,2-propanediol (XPD), particularly 1,2- and 1,3-dichloro-2-propanol (DCP) and 3-chloro-1,2-propanediol (CPD). By the WO 2007/004972 PCT/SE2006/050188 5 purification according to the present invention, DXP and XPD as well as any remaining epihalohydrin can be removed and eventually destructed. For example, it is possible to obtain polyaminoamide epichlorohydrin polymers with a content of organic chlorines below about 0.01 wt% and even below about 0.0001 wt% or less. 5 The extraction takes place under conditions in which the fluid is in a liquid, supercritical or near supercritical state. Near supercritical means that the temperature is slightly below T, and/or the pressure is slightly below P,, but the properties of the fluid are substantially equivalent to the case when the temperature and the pressure exceeds T, and P,. respectively. The temperature in K is preferably at least about 0.9 x T,, most preferably 10 at least 0.95 x T,. The pressure is preferably at least about 0.9 x P,, most preferably at least 0.95 x P,. For practical reasons and to avoid decomposition of the epihalohydrin polymer it is usually preferred to operate at a temperature from about 10*C to about 200*C most preferably from about 40*C to about 120"C. For the same reasons it is usually preferred to operate at a pressure from about 40 bar to about 500 bar, most preferably from about 75 bar 15 to about 400 bar. The optimal conditions may vary depending on which epihalohydrin polymer that is purified and which impurities that are most desirable to remove. For example, it has been found that DCP is efficiently removed from polyaminoamide epichlorohydrin at a preferred temperature from about 30*C to about 180"C, most preferably from about 40*C to about 100*C and a preferred pressure from about 60 bar to about 500 20 bar, most preferably from about 75 bar to about 300 bar, while CPD is efficiently removed from polyaminoamide epichlorohydrin at a preferred temperature from about 30*C to about 180*C, most preferably from about 50*C to about 100*C and a preferred pressure from about 60 bar to about 500 bar, most preferably from about 150 bar to about 400 bar The extraction may be a one stage process, but can also be performed in two or 25 more stages with the same or different conditions, the latter being of interest if different optimal conditions for extracting different kinds of halogen containing impurities apply. The average residence time for the solution of the epihalohydrin polymer in contact with fluid under supercritical or near supercritical conditions is preferably from about 5 minutes to about 120 minutes, most preferably from about 15 minutes to about 60 minutes. 30 The purification through an extraction may be performed batchwise, continuously or a combination thereof. In one embodiment the extraction is performed by maintaining a solution of the epihalohydrin polymer in vessel, preferably under agitation, and contacting it with a continuous flow of fluid under liquid, supercritical or near supercritical conditions during a 35 time sufficient to achieve removal of halogen containing impurities to a satisfactory degree. The temperature and pressure may remain substantially constant during the entire time but may also be changed stepwise or continuously. The purified solution of the WO 2007/004972 PCT/SE2006/050188 6 polymer can then withdrawn as a product or be transferred to a further extraction step or any other treatment. In another embodiment the extraction is performed by contacting the solution of the epihalohydrin polymer with the fluid under liquid, supercritical or near supercritical 5 conditions in a through-flow vessel or column, in each case with or without a packaging. Both the solution of the polymer and the fluid flow continuously through the vessel or column, preferably counter-currently, but also co-current flow could come into question. If appropriate, part of the purified polymer solution may be recirculated. The temperature and pressure may be the same or different in various parts of the vessel or column. Any 10 kind of vessels or columns commonly used for extraction can be used, such as tray-type columns or packed columns with structured or non-structured packings made of e.g. glass, metal or ceramic materials. The separation of extracted impurities from the withdrawn fluid is suitably done by altering the temperature and/or pressure thereof to change the solubility properties so 15 the impurities are precipitated. Usually this is easiest done by lowering the pressure to a level below Pr. If necessary the extracted impurities can removed from the carbon dioxide by purification with water or active carbon. After the separation the fluid can be re used after restoring the temperature and pressure to conditions suitable for the extraction. The separated impurities may be destructed by any suitable means. 20 The invention will be further described in connection with the following examples, which, however, are not intended to limit the scope thereof. Unless otherwise stated, all parts and percentages refer to parts and percent by weight. Figure 1 is a flow sheet for batchwise extraction while Figure 2 is a flow sheet for continuous extraction. 25 Example 1: An aqueous solution of polyaminoamide epichlorohydrin polymer (PAAE) having a dry content of 20.7 wt% was purified by batch-wise extraction with supercritical carbon dioxide in an experimental setup according to Fig. 1. Before the purification the concentrations of DCP was 267 pg/g and of CPD 289 pg/g. The solution of PAAE was maintained under agitation in a 250 ml extraction vessel 4 and subjected to 30 a continuous flow of supercritical carbon dioxide CO 2 brought from a vessel via a cooler 1, a pump 2 and a heat exchanger 3 under various conditions in respect of temperature, pressure and time. In a separator 5 the pressure was released, resulting in precipitation of the extracted components from the carbon dioxide. After the extraction the content of DCP and CPD in the purified PAAE solution was determined by gas chromatography. 35 The results are shown in Table 1: WO 2007/004972 PCT/SE2006/050188 7 Table 1 Batch extraction Conditions pg DCP/g pg CPD/g Temperature, pressure, redidence time, CO 2 flow 40 0 C, 150 bar, 30 min, 1.2 kg/h 69.9 249.4 70 0 C, 150 bar, 30 min, 1.2 kg/h 30.8 252 80 0 C, 150 bar, 30 min, 1.2 kg/h 45.8 141.8 80 0 C, 250 bar, 60 min, 1.2 kg/h < 5 227 Examples 2-4: An aqueous solution of polyamninoamide epichlorohydrin polymer (PAAE) having a dry content of 21.2 wt% was purified by continuous extraction with 5 supercritical carbon dioxide in an experimental setup according to Fig. 2. Before the purification the concentrations of DCP was 269.7 pg/g and of CPD 308.1 pg/g. The polymer solution F was brought via a pump 6, and a pre-heater 7 to a packed column 4 where it was contacted by a counter-current flow of carbon dioxide circulating via a cooler 1, a pump 2 a heat exchanger 3 and, after the column 4, a separator 5. The purified 10 polymer solution was brought from the column 4 to a raffinate vessel R. In a separator 5 the pressure was released and after purification with active carbon the carbon dioxide was recycled. In Examples 2 and 3 were run as bubble extraction with the column 4 filled with polymer solution, while Example 4 was run as film extraction with the polymer solution flowing as a film on the packings in the column 4. The results are shown in Table 15 2. Table 2 Continuous extraction Ex. Conditions pg DCP/g pg CPD/g Temperature, pressure, Feed flow, CO 2 flow 2 50*C, 200 bar, 1.8 kg/h Feed, 10kg/h CO 2 16.3 159.7 3 50*C, 200 bar, 1.2 kg/h Feed, 10kg/h CO 2 2.9 174.3 4 50*C, 200 bar, 1.2 kg/h Feed, 10kg/h CO 2 0.8 202.2 Example 5: The treated polymers obtained in Examples 3 and 4 as well as the 20 commercially available polyaminoamide epichlorohydrin polymer solution Eka WS 320 were tested as wet strength agents in paper making on a pilot paper machine. The following conditions were applied: Pulp: 40 wt% eucalyptus, 40 wt% birch, 20 wt% pine sulfate Paper density: 70 g/m 2 Freeness: about 340 SR Consistency (chest): 1.5% 8 Addition levels: 6, 9 and 12 kg/ tonne paper pH (head box): 7.2-7.5 Stock temperature: 300C After curing for 30 minutes at 100'C the wet strength of the different papers made were tested and no differences could be found between the wet strength agents. Thus, it was found that the content of DCP and CPD in a polyaminoamide epichlorohydrin polymer solution could be significantly reduced without affecting its performance as wet 5 strength agent in paper making. It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. In the claims which follow and in the preceding description of the invention, 10 except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 2328312 1 (GHMatters)

Claims

1. A process for purifying a solution of a nitrogen containing epihalohydrin polymer formed by reaction of a nitrogen-containing precursor selected from amines, poly 5 amines, polyaminoamides, polyurethanes or mixtures thereof with epihalohydrin comprising the steps of contacting the solution of the epihalohydrin polymer with a fluid under liquid, supercritical or near supercritical conditions to effect extraction of organic impurities from the solution of the epihalohydrin polymer to the fluid, withdrawing fluid enriched in organic impurities from the solution of the epihalohydrin polymer, and separating extracted 10 impurities from the withdrawn fluid, wherein the fluid comprises a substance that at atmospheric pressure and room temperature (about 250C) is gaseous.

2. A process for the production of a nitrogen containing epihalohydrin polymer wherein a solution of the polymer is purified in accordance with claim 1. 15

3. A process as claimed in claim 1 or 2, wherein the fluid is carbon dioxide.

4. A process as claimed in any one of claims 1 to 3, wherein the epihalohydrin polymer is a polyaminoamide-epihalohydrin polymer. 20

5. A process as claimed in any one of the claims 1-4, wherein the organic impurities comprise organic halogen containing impurities.

6. A process as claimed in claim 5, wherein the halogen containing impurities 25 comprise at least one of epihalohydrin and reaction products thereof.

7. A process as claimed in claim 5 or 6, wherein the reaction products of epihalohydrin comprise at least one of 1,2- and 1,3-dichloro-2-propanol and 3-chloro-1,2 propanediol. 30

8. A process as claimed in any one of the claims 1-7, wherein the solution of the epihalohydrin polymer is an aqueous solution.

9. A process as claimed in any one of the claims 1-8, wherein the extraction 35 takes place at a temperature from 10 to 200*C. 10

10. A process as claimed in any one of the claims 1-9, wherein the extraction takes place at a pressure from 40 to 500 bar. 5

11. A process for purifying a solution of a nitrogen containing epihalohydrin polymer substantially as herein described with reference to the accompanying examples.

12. A process for the production of a nitrogen containing epihalohydrin io polymer substantially as herein described with reference to the accompanying examples.

13. A process for purifying a solution of a nitrogen containing epihalohydrin polymer substantially as herein described with reference to the 15 accompanying drawings.

14. A process for the production of a nitrogen containing epihalohydrin polymer substantially as herein described with reference to the accompanying drawings. 2328312_1 (GHMatters)