BRPI0613479A2 - chemical process - Google Patents

Abstract

CHEMICAL PROCESS. The invention relates to a process for the production of a nitrogen-containing epihalohydrin polymer involving reaction of a nitrogen-containing precursor selected from the group consisting of amines, polyamines, polyamyrtoamides, polyurethanes and mixtures thereof, with epihalohydrin to form a solution of said epihalohydrin polymer, the process comprising a purification step to remove organic impurities from the solution formed of the epihalohydrin polymer, said purification step comprising contacting the epihalohydriraa polymer solution with a fluid under liquid under supercritical conditions or close to supercritical to extract organic impurities from the solution of the epihalohydrin polymer into the fluid, removing fluid enriched with organic impurities from the solution of the epihalohydrin polymer, and separating impurities into extracts from the removed fluid, in which the fluid comprises a substance that the atmospheric pressure and room temperature (<25 ° C) is gaseous. The invention also relates to a process for purifying a solution of a nitrogen-containing epihalohydrin polymer.

Description

"Chemical process"

The present invention relates to a process for producing a nitrogen-containing epihalohydrin polymer from a nitrogen-containing precursor comprising a purification step to remove organic impurities, particularly deepihalohydrin reaction products. The invention further relates to a process for purifying a solution of a nitrogen-containing deepihalohydrin polymer produced from precursor containing nitrogen from organic impurities.

In the preparation of nitrogen-containing epihalohydrin polymers, organic by-products may be obtained, some of which are often halogenated. Additionally, 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 papermaking. However, many halogenated organic compounds are toxic and / or objectionable from an environmental point of view, and for many applications, such as papermaking, it is desirable to lower the contents.

Several purification methods for removing chlorinated contaminants from polyaminoamideepihalohydrin polymers have been disclosed, for example, ion exchange in US 5516885, electrodialysis in US 5643430, ultrafiltration in WO 00/34358, active carbon treatment in WO 01/18093. a base in WO 99/33901, and enzymatic action in WO 02/50163. US 6576687 discloses a method of producing polycondensate solutions based on epichlorohydrin amine resins claimed to have a very low content of organic chlorine compounds. However, these methods of preparation and purification are either complicated to operate or insufficiently effective.

Removing residual polymer impurities or monomers has been shown to be removed by carbon dioxide extraction, see, for example, US 5034132 and US 6180755. It has also been shown to extract carbon dioxide impurities from polymer dispersions as described in EP374879.

CN 1350795 discloses removal of DCP and MCP from a plant protein hydrolytic liquid with supercritical or carbonolyxide dioxide.

US 2005/0037932 discloses a perfluoropolyether lubricant, the preparation of which includes a supercritical fluid extraction scrubbing step.

It is an object of the invention to provide a process for producing a nitrogen containing epihalohydrin polymer from a nitrogen containing precursor comprising an effective purification step for removing organic impurities, particularly halogen containing impurities.

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 produced from a nitrogen-containing precursor.

It is yet another object of the invention to provide 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 another object of the invention to provide efficient removal of 1,2- or 1,3-dihalo-2-propanol or 3-halo-1,2-propanediol from a polyaminoamide epihalohydrin polymer without significantly affecting its desired properties.

Through the present invention it will be made possible to achieve these objectives.

One aspect of the invention relates to a process for the production of a nitrogen containing epihalohydrin polymer involving reaction of a nitrogen containing precursor selected from the group consisting of amines, polyamines, polyaminoamides, polyurethanes and mixtures thereof with epihalohydrin to form a solution. of said epihalohydrin polymer, the process comprising a purification step for removing organic impurities from the solution formed of the epihalohydrin polymer, said purification step comprising contacting the deepihalohydrin polymer solution with a fluid under liquid at or near supercritical conditions for effecting impurity extraction. from the epihalohydrin polymer solution to the fluid by removing enriched fluid from organic impurities from the epihalohydrin polymer solution and separating impurities into extracts from the withdrawn fluid in the which fluid comprises a substance which at atmospheric pressure and room temperature (about 25 ° C) is gaseous.

Another aspect of the invention relates to a process for purifying a solution of a nitrogen containing epihalohydrin polymer by reacting a nitrogen containing precursor selected from the group consisting of amines, polyamines, polyaminoamides, and polyurethanes thereof with epihalohydrin, comprising contacting steps. the epihalohydrin polymer solution with a fluid under liquid under supercritical conditions or close to supercritical to extract organic impurities from the epihalohydrin polymer solution to the fluid, removing enriched organic impurities fluid from the deepihalohydrin polymer solution, and separating impurities into extracts from the withdrawn fluid, wherein the fluid comprises a substance at which atmospheric pressure and ambient temperature (about 25 ° C) is gaseous.

Extraction with a fluid under supercritical or near supercritical conditions has been found to have undoubtedly removed unwanted organic compounds, particularly halogen-containing compounds, from polymer in a comparatively simple procedure significantly negatively impacts its desired characteristics, for example as a papermaking additive, particularly, as a wet strength resin.

Typically, such fluid may be reused after separation of the extracted impurities. Preferred fluids are those having a critical temperature (Tcr) of about 200 ° C to about 100 ° C, more preferably from about 30 ° C to about 60 ° C, and a critical pressure (Pcr) of about 30 bar to about 500 ° C. more 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.

Additionally, carbon dioxide was found not to negatively impact the treated polymer. The fluid may be used in substantially pure form, or mixed with equal amounts of one or more co-solvents, surfactants, complexing agents, or the like.

The process-containing nitrogen-containing epihalohydrin polymers of the present invention include those that have been prepared with epihalohydrin, for example epichlorohydrin, as a reagent, or during polymerization, or in modification of an existing polymer.

The invention is particularly advantageous for nitrogen-containing deepihalohydrin polymers that are water soluble.

Nitrogen-containing epihalohydrin polymers include those formed by the reaction of nitrogen-containing precursors selected from amines, polyamines, polyaminoamides, polyurethanes and mixtures thereof.

More preferably, the polymers are polyaminoamide epihalohydrin polymers, which may also be referred to as polyamidoamine-epihalohydrin, and are useful as wet strength resins in papermaking.

Epihalohydrins which may be used include epibromohydrin and epichlorohydrin, preferably epichlorohydrin. Suitably, the polymers are produced using from about 0.5 to about 2 moles deepihalohydrin per mole of basic nitrogen in the nitrogen-containing precursor.

The nitrogen-containing precursor is preferably the polyaminoamide reaction product of a polycarboxylic acid or derivative thereof, suitably dicarboxylic acid or derivative thereof, and a polyamine. Carboxylic acid derivatives include, for example, anhydrides, esters and half esters. Suitable polycarboxylic acids include aliphatic or aromatic unsaturated or aromatic dicarboxylic acids. Preferably, the polycarboxylic acids contain less than 10 carbon atoms.

Preferred polycarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid and mixtures thereof, of which adipic acid is particularly preferred.

Preferred polyamines include polyalkylene polyamines, or mixtures thereof, having the following formula: wherein R1-R5 represent R1-R5 - (CR5H) bN (R3) - (CR4H) c- (CR5H) d-NH2 (!) hydrogen or lower alkyl, preferably up to C3, and ad represent integers from 0 to 4. Preferred polyalkylenes polyamines include diethylenetriamine, triethylene tetraamine, tetraethylene pentaamine, dipropylene triamine, and mixtures thereof.

The polyamines of formula (I) may be combined with other polyamines, or mixtures of other amines.

Preferably, these amines have any of the following formulas II-VII:

<formula> formula see original document page 8 </formula>

wherein R6-R14 represent hydrogen or lower alkyl, preferably up to C3, and -1 represent integers from 0 to 4, and m represents an integer from 0 to 5.

Polycarboxylic acid and polyamine may, for example, be applied in a molar ratio of from about 1: 0.5 to about 1: 1.5.

The epihalohydrin-based polymer containing nitrogen is preferably present in an aqueous solution, which may additionally comprise a water-immiscible solvent, such as methanol, ethanol and dimethylformamide. 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 about 50,000 to about 1,000,000 or higher.

The preparation of epihalohydrin polymers may be carried out by any process, such as those disclosed in any of US 4450045, US 3311594, US4336835, US 3891589, US 2926154, US 4857586, US 4975499, US5017642, US 5019606, US 5093470 and additional 5516885, but additionally. including a purification step comprising extraction with a fluid under supercritical and close to supercritical conditions as described. According to the invention, it is also possible to subtract nitrogen-containing epihalohydrin polymers commercially or otherwise readily available at such a purification step.

The epihalohydrin polymer solution is preferably an aqueous solution, and it has been found that only a small amount of water is removed in the purification step.

The solids content of the solution to be purified is preferably as high as possible, causing handling problems and may in many cases be higher than about 35 weight% or more, but is preferably from about 5 to about 30 weight%, more preferably from about 10 to about 25 weight%. The viscosity of the solution is preferably from about 1 to about 250 mPas, more 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 organic impurities. Halogen-containing impurities which may be removed include epihalohydrin such as, particularly epichlorohydrin, and reaction 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 purification according to the present invention, DXP and XPD, as well as remaining epihalohydrin, can be removed and eventually destroyed. For example, the polycycloamide epichlorohydrin polymers having a chlorosorganic content below about 0.01 wt%, and still below about 0.0001 wt% or less can be obtained.

Extraction occurs under conditions in which the fluid is a liquid, in a supercritical or near-de-critical state. Near supercritical means that the temperature is slightly low of Tcr, and / or the pressure is below Pcr, but the fluid properties are substantially equivalent to the case when temperature and pressure exceed Tcr and Pcr, respectively. The temperature in K is preferably at least about 0.9 χ Tcr, more preferably at least 0.95 χ Tcr. The pressure is preferably at least about 0.9 χ Pcr, more preferably at least 0.95 χ Pcr. For practical reasons, and to avoid decomposition of the epihalohydrin polymer, it is usually preferred to operate at a temperature of about 10 ° C to about 200 ° C. ° C, more preferably from about 40 ° C to about 120 ° C. For the same reasons, it is usually preferred to operate at a pressure of about 40 bar to about 500 bar, more preferably from about 75 bar to about 500 bar. Optimal conditions may vary depending on the epihalohydrin polymer that is purified, and which impurities are most desirable to remove. For example, it has been found that DCP is efficiently removed from epichlorohydrin polyaminoamide at a temperature preferably about 30 ° C to about 180 ° C, more preferably about 40 ° C to about 100 ° C, and a preferred pressure about 60 ° C. about 500 bar, more preferably about 75 bar to about 300 bar, while the CPD is efficiently removed from polyaminoamide epichlorohydrin at a temperature of from about 30 ° C to about 180 ° C, more preferably from about 50 ° C to about 100 ° C, and a preferred pressure of about 60 bar to about 500 bar, more preferably from about 150 bar to about 400 bar.

Extraction may be a one-stage process, but may also be performed in two or more stages, with the same or different conditions, the latter being of interest, and different optimum conditions for extraction of different types of halogen-containing impurities apply. The average residence time for the solution of the deep-halohydrin polymer in contact with fluid under or near supercritical conditions is preferably from about 5 minutes to about 120 minutes, preferably from about 15 minutes to about 60 minutes.

Purification by extraction may be carried out by batch, continuously, or a combination of these.

In one embodiment, extraction is performed by maintaining a solution of the novel epihalohydrin polymer, preferably under agitation, and contacting it with a continuous flow of fluid under liquid under supercritical and near-critical conditions for a time sufficient to achieve removal of halogen-containing impurities at a temperature. satisfactory degree. The temperature and pressure may remain substantially constant over the whole time, but may also be changed in stages or continuously. The purified polymer solution can then be withdrawn as a product, or transferred to an additional extraction step or any other treatment.

In another embodiment, extraction is performed by contacting the solution of the epihalohydrin polymer with a fluid under liquid, under near-supercritical and supercritical conditions, in a flow vessel or column, in each case with or without packaging. Both the polymer solution and the flow of fluid through the vessel or column, but also co-current flow, may come into question. If appropriate, part of the purified polymer solution may be recirculated. Temperature and pressure may be the same or different in various parts of the vessel or column. Any types of vessels or columns commonly used for extraction may be used, such as tray columns, or columns packed with structured or unstructured packages produced from, for example. , glass, metal or ceramic materials.

Separation of impurities extracted from the withdrawn fluid is suitably done by changing the temperature and / or pressure thereof to change the solubility properties such that the impurities are precipitated.

This is usually made easier by lowering the pressure to below Pcr. If necessary, the extracted impurities can be removed from carbon dioxide by purification with water or active carbon. After separation, the fluid may be reused after the temperature and pressure have been restored to the appropriate conditions for extraction. Separate impurities may be destroyed by any suitable means.

The invention will now be further described in conjunction with the following examples, which, however, are not intended to limit the scope thereof. Unless otherwise noted, all parts and percentages refer to parts and percent by weight.

Figure 1 is a flowchart for batch extraction, while Figure 2 is a flowchart for continuous extraction.

Example 1:

An aqueous solution of piliaminoamideepichlorohydrin (PAAE) polymer having a dry content of 20.7 wt.% Was purified by batch extraction with supercritical carbon dioxide in an experimental configuration according to Figure 1. Prior to purification, DCP concentrations were 267 μg / gd of CPD was 289 μς / g. The PAAE solution was kept under stirring in a 250 ml extraction vessel 4, subjected to a continuous stream of supercritical CO2 carbon dioxide brought from a vessel via a cooler 1, a pump 2, and a heat exchanger 3 under conditions relative to temperature, pressure and time. In a separator 5, the pressure was released, resulting in precipitation of the components extracted from carbon dioxide. After extraction, the content of DCP and CPD in the purified PAA solution was determined by gas chromatography. The results are shown in Table 1:

Table 1 Batch Extraction

<table> table see original document page 14 </column> </row> <table>

Examples 2-4:

An aqueous polyaminoamideepichlorohydrin (PAAE) polymer solution having a dry content of 21.2 wt% was purified by continuous extraction with supercritical carbon dioxide in an experimental configuration according to Figure 2. Prior to purification, DCP concentrations were 269.7 μq / g of CPD was 308.1 µg / g. Polymer solution F was brought via a pump 6 and a preheater7 to a packed column where it was contacted by a countercurrent flow of carbon dioxide circulating the cooler 1, a pump 2, a heat exchanger 3 and, after column 4, a separator 5. The polymerized solution was brought from column 4 to a Derafinate R vessel. In a separator 5, the pressure was released, and after purification with active carbon, recycled carbon dioxide. Examples 2 and 3 were operated as bubble extraction with column 4 filled with polymer solution, while Example 4 was operated as cell extraction with polymer solution flowing as a film in the packages in column 4. The results are shown in Table 2.

Table 2 Continuous Extraction

<table> table see original document page 15 </column> </row> <table> Example 5:

The treated polymers obtained in Examples 3 and 4, as well as the commercially available polyaminoamideepichlorohydrin polymer solution Eka WS 320, were treated with wet strength agents in the manufacture of paper on a pilot paper machine. The following conditions have been applied:

Pulp: 40 weight% eucalyptus, 40 weight% birch, 20 weight% pine sulfate

Paper Density: 70 g / m2Freedom: about 34 ° SRConsistency (box): 1.5%

Additional levels: 6.9 and 12 kg / tonne paperpH (main box): 7.2-7.5Stock Temperature: 30 ° C

After curing for 30 minutes at 100 ° C, the wet strength produced different papers were tested, and no difference can be verified between wet strength agents. Thus, it was found that the content of DCP and CPD in a polyaminoamide epichlorohydrin polymer solution can be significantly reduced by affecting its performance as a wet strength agent in papermaking.

Claims (10)

1. A process for the production of a nitrogen-containing deepihalohydrin polymer involving reaction of a nitrogen-containing precursor selected from the group consisting of amines, polyamines, polyaminoamides, polyurethanes and mixtures thereof with epihalohydrin to form a solution of said epihalohydrin polymer. A process comprising a purification step for removing organic impurities from the solution formed of the epihalohydrin polymer, said purification step comprising contacting the solution of the epihalohydrin polymer with a supercritical or near-supercritical fluid to effect the extraction of organic impurities. from the epihalohydrin polymer solution to the fluid by removing enriched fluid from organic impurities from the epihalohydrin polymer solution by extracting impurities in extracts from the drawn fluid in which the fluid comprises A substance which has atmospheric pressure and ambient temperature (about 25 ° C) is gaseous. 2. A process for purifying a solution of a nitrogen containing epihalohydrin polymer comprising the reaction of a nitrogen containing precursor selected from the group consisting of amines, polyamines, polyaminoamides, polyurethanes and mixtures thereof with epihalohydrin comprising the steps. contacting the epihalohydrin polymer solution with a fluid under liquid under supercritical or near supercritical conditions to extract organic impurities from the epihalohydrin polymer solution into the fluid by withdrawing enriched fluid from organic impurities from the epihalohydrin polymer solution and separating impurities in extracts from the withdrawn fluid, in which the fluid comprises a substance which at atmospheric pressure and room temperature (about 25 ° C) is gaseous. Process according to any one of claims 1-2, characterized in that the fluid is carbon dioxide. 4. A process according to claim 3 wherein the epihalohydrin polymer is a polyaminoamide-epihalohydrin polymer. 5. A process according to any one of claims 1-4, characterized in that the organic impurities comprise impurities containing organic halogen. 6. A process according to claim 5 wherein the halogen-containing impurities comprise at least one epihalohydrin and reaction products thereof. 7. A process according to any one of claims 5-6 wherein the epihalohydrin reaction products comprise at least one of 1,2- and 1,3-dichloro-2-propanol and 3-chloro-1. 2-propanediol. 8. A process according to any one of claims 1-7, characterized in that the solution of the epihalohydrin polymer is an aqueous solution. 9. A process according to any one of claims 1-8, characterized in that the extraction occurs at a temperature of about 10 to about 200 ° C. 10. A process according to any one of claims 1-9, characterized in that the extraction occurs at a pressure of about 40 to about 500bar.