EP1311553A1

EP1311553A1 - High molecular weight cationic polymers, preparation method and uses thereof

Info

Publication number: EP1311553A1
Application number: EP01955439A
Authority: EP
Inventors: René c/o SNF SA HUND; Cédrick c/o SNF SA FAVERO; Pierre c/o SNF SA LYOT
Original assignee: SNF SA
Current assignee: SNF SA
Priority date: 2000-07-27
Filing date: 2001-07-19
Publication date: 2003-05-21
Also published as: FR2812295A1; AU2001277605A1; WO2002010225A1; US20040030039A1; FR2812295B1

Abstract

The invention concerns a method for preparing high molecular weight cationic polymers based on dialkyl diallyl ammonium salts in bead form by reverse suspension polymerisation. Said method uses a monomer or a mixture of monomers based on dialkyl diallyl ammonium salts at a concentration ranging between 67 and 77 wt. % and preferably between 68 and 72 wt. % of active substance. Said method enables to polymerise said type of monomer without developing specific stabilising system, without seeded polymerisation, without even adding surfactants to the formulation, without distillation in certain important cases, and while avoiding any risk of solidification. The invention also concerns the resulting polymers and their industrial use, in particular paper making, water treatment, mining, cosmetics, textile, and generally in all industrial techniques of coagulation/flocculation.

Description

High molecular weight cationic polymers, process for their preparation, and their applications.

The invention relates to the technical sector of reverse suspension polymerization which consists of the polymerization of a phase of water-soluble monomers dispersed in the form of droplets in a hydrophobic phase in the presence of stabilizing species. These droplets polymerize by the presence of initiating species of polymerization (initiators) making it possible to transform these drops of liquid into a soft gel composed mainly of water and of polymer. The water is then removed from the gel by azeotropic distillation in order to allow the separation of a solid phase, polymerized in the form of beads, from a hydrophobic phase. The beads are then brought to their final shape by means of a final drying which makes it possible to remove the hydrophobic phase residues.

More specifically, the present invention relates to a process for reverse suspension polymerization of cationic polymers of high molecular weight based on dialkyl diallyl ammonium salts. The invention also relates to the polymers obtained and their applications in industry.

By diallyl dialkyl ammonium salts, the invention includes all the compounds of general formula:

(CH2 = CH-CH2) ₂ N ⁺ R ₁ R ₂ , X ^'

X ^" : a halide which may be bromide, chloride, iodide, fluoride, or any counter ion of negative charge.

R ₁ and R ₂ : independently a hydrogen or an alkyl chain containing from 1 to 10 carbons.

The preferred monomer of this invention is diallyl dimethyl ammonium chloride or DADMAC. The prior art

The processes for synthesizing beads of water-soluble polymers from ethylenically unsaturated water-soluble monomers have been known since the 1950s. The techniques used and the necessary stabilizing species have been described by numerous patents. Examples include the patents DE 1110869 of 1959, US 2,982,749 of 1961, FR 2383200 of 1977, US 4,164,613 of 1977, or FR 2360612 of 1977.

The synthesis of water-soluble polymers from diallyl dialkyl ammonium salts has been described by Butler's work on the polymerization of diallylated compounds in a series of publications carried out between 1949 and 1957 (Butler, J. Am. Chem. Soc).

Due to their chemical structure, these polymers have given rise to much research. One of the main technical problems encountered by the industry during the polymerization of diallyl dialkyl ammonium salts is their low reactivity which does not allow polymers to be obtained satisfactorily in solid form and of very high molecular weight. However, there is a strong commercial demand, the solution of which has not been provided by the prior art.

At the origin of the main advances relating to this type of compound, the company Calgon ™ has developed methods enabling the performance of these polymers to be optimized during their use. Regarding the coagulation and / or flocculation processes, it has in particular recommended to its customers to inject the polymers of diallyl dialkyl ammonium halides in powder directly into the suspension to be treated (i.e. without pre-treatment step). -dissolution). US Patent 4,654,378 describes the process for producing homopolymers of diallyl dimethyl ammonium chloride in dry form by the UV polymerization technique. The product thus prepared is in the form of free flowing granules with a very high dissolution rate. Such a process is, however, technically very difficult to extrapolate for large-scale productions. The use of polyDADMAC in the form of solid particles has also been described by several bibliographical references. We will quote:

- Patent JP 49092855 which describes the use of organic coagulants and flocculants in the form of solid particles, having a weight

5 molecular between 20,000 and 10,000,000, such as polyamines, polyDADMAC, polyethylene imines, cationic polyacrylamide derivatives ... The polymer is added in the solid state (particle size between 0.01 and 1 mm) directly in the coagulation or flocculation tank. The polymers thus used have a higher efficiency compared to a conventional addition in solution.

- This same coagulation process has subsequently been described in JP 60202787 with the use of polyDADMAC as a coagulation agent and has also been taken up by patent EP 536194.

Among the industrial solutions that can be envisaged for the production in the solid form of polymers of diallyl dialkyl ammonium salts, the most promising route is suggested by US Pat. No. 4,158,726. This route consists in the preparation of beads of water-soluble polymers from cationic monomers by reverse suspension polymerization.

Technical problem :

However, one of the main problems encountered by the industry during the manufacture of beads of polymers of diallyl dialkyl ammonium salts comes from the significant risk of caking or formation of aggregates of polymer gels, more particularly during the 'azeotropic distillation step. This results in the loss of all or part of the production.

Therefore, the synthesis of beads of polymers of diallyl dialkyl salts. ammonium has always required an evolution of the reverse suspension polymerization technique to remedy these problems. In the prior art, the changes made are as follows:

Patent EP 0233014 uses the seeded polymerization technique to make stable beads. This patent shows that it is difficult to make beads of poly diallyl dialkyl ammonium halides directly because this results in the formation of aggregates.

(example 4 applied to DADMAC). By this seeded polymerization method, it is then possible to subject the suspension of soft gel to azeotropic distillation without risk of formation of aggregates.

- Patent EP 0495312 adds an emulsifier in addition to the polymeric stabilizer to the formulation in order to once again avoid the phenomena of aggregation. He notes that effectively, a polymerization according to standard reverse suspension processes, that is to say without the addition of an emulsifier, leads in the case of DADMAC to a high setting frequency; The molecular weights obtained remain below 3,000,000 for polymerization times greater than 5 hours.

Patent DE 3709921, for its part, develops a specific polymeric stabilizer in order to maintain a standard process of polymerization in reverse suspension, even for polyDADMAC beads. The beads are thus obtained without any aggregate but with a polymerization time of 17 hours followed by azeotropic distillation, which makes the industrialization of this process economically unviable.

- US Patent 4,833,198 uses a specific mixture of polymeric stabilizers and inorganic stabilizers in order to remedy the problems of aggregation of the beads. The scope of this stabilizer system includes polyDADMAC beads although no specific example appears. Description of the invention

According to the invention, it has surprisingly been found that it is possible to prepare beads or beads ("beads") of very high molecular weight of polymers based on one, or on a mixture of diallyl salts dialkyl ammonium according to a standard reverse suspension polymerization process using the monomer or mixture of diallyl dialkyl ammonium salt monomers at a concentration between 67 and 77% and preferably between 68 and 72% by weight of active material (so standard, this type of compound, the most used of which is DADMAC, is sold on the contrary in solution at concentrations between 62 and 65%).

This process does not require the development of a specific stabilizing system, nor of seeded polymerization, nor even of the addition of surfactants to the formulation. The beads or beads of diallyl dialkyl ammonium salts can therefore perfectly be produced in accordance with the description of the process of US Pat. No. 4,158,726.

This concentration range makes it possible to synthesize, surprisingly, in the form of beads, polymers of very high molecular weight never before produced for this type of monomer. For example, the homopolymers of DADMAC obtained by the invention have molecular weights which can easily reach 2.5 million and go up to 30 million.

In addition, surprisingly, the selection of this range of active material in diallyl dialkyl ammonium salts also makes it possible to reduce the polymerization times to less than 2 hours and generally to less than 1 hour whereas the conventional methods describe times of polymerization longer than 5 hours and up to 18 hours.

Another aspect of this invention is the influence that the concentration of active material (67-77%) of diallyl dialkyl ammonium salts has on the texture of the ball at the end of polymerization. Thanks to this range of active ingredient, it is surprisingly possible to dispense with the distillation step. azeotropic formerly critical, because the ball is already hard which simplifies the synthesis process, allowing in fact a substantial saving of time, energy and investment.

The invention also relates to a process for the preparation of water-soluble beads of branched polymers of diallyl dialkyl ammonium salts of high molecular weight. The condition for formulating these branched polymers being not to lower the active material of the aqueous phase below 67% and not to exceed 77% by weight. The branching agents which can be used are N-methyloI acrylamide, methylene bis acrylamide, amino triethanol, and any other multifunctional compound capable of branching. One can also use one of the known branching agents of diallylated compounds such as methyl triallyl ammonium chloride, triallylamine, tetraallyl ammonium chloride, tetra allyl ethylene diamine, and more generally all polyallylated compounds. It is also possible to make post-crosslinked polymers as described in patent WO 00/14124.

Another aspect of the invention relates to the possible addition of a polymer in the initial charge in order to make a mixture of polymers in the final bead. The polymer being dissolved in the aqueous phase before dispersion of the latter in the hydrophobic phase, and the polymer possibly being in liquid form, this cannot be assimilated to seeded polymerization which requires a step of absorption of the monomer. The polymers useful for blending with the polymers of diallyl dialkyl ammonium salts are all water-soluble polymers and in particular those of acrylic type and all of their known cationic, anionic and nonionic copolymers. The organic coagulants of the polyethylene imine, polyvinylamine, polyamine based on epichlorohydrin, dicyandiamide resin, melamine formaldehyde resin type can also be added for the mixture as well as inorganic polyelectrolytes such as for example aluminum polychlorides, aluminum chlorides, aluminum sulfates, and the like. In parallel with the invention, it has been found that by keeping a concentration of active material in the aqueous phase of between 67% and 77%, it is also possible to dispense with the distillation step during the copolymerization of diallyl dialkyl ammonium halides with any other water-soluble monomer (quaternized, salified or not) capable of copolymerizing, for example acrylamide and its derivatives, methacrylamide and its derivatives, acrylic acid, methacrylic acid, 2- acrylamido 2-methyl propane sulfonate (AMPS), dimethyl aminoethyl (meth) acrylate, (meth) acrylamido propyl trimethyl ammonium, N-vinyl pyrrolidone, and the like, and to obtain water-soluble polymers in the form of beads in a very wide range of molecular weights (10,000 - 30,000,000).

The present invention relates more precisely to the methods which have just been described and to their embodiments and variants.

The invention also relates to the polymers obtained in beads by these processes as well as their applications in industry; non-limiting examples include: the paper industry, water treatment (drinking or used), coagulation / flocculation techniques, the mining industry, the cosmetics industry, the textile industry ...

EXAMPLES

The polymers Pn and Xn were prepared according to the reverse suspension polymerization technique as described in patent US Pat. No. 4,158,726.

The polymerization conditions for these 15 tests are strictly identical with the use of an initiator known from DADMAC such as tert-butyl hydroxy peroxide (TBHP) or V50 (2,2'-azobis dihydrochloride [N- (2-hydroxyethyl) - 2-methylpropionamidine]) in accordance with US Patent 4,158,726.

The content of active material in the suspension can be between 0 and 60%, however the tests were carried out using a formulation containing 25% of active material. - The aqueous phase:

A chelator (EDTA (ethylene diamine tetraacetic acid), Versenex ™ 80 ...) is added to the aqueous phase which is then adjusted to pH 4.

- The hydrophobic phase:

The dispersion medium is a hydrophobic liquid insoluble in the aqueous phase. For ecological and toxicological reasons, the tests use an aliphatic hydrocarbon forming an azeotrope with water (for the dehydration of tests X1 and X2).

- The dispersion stabilizer:

The advantage of the present invention lies in the fact that most of the known stabilizers of reverse suspensions can be used (for example those described by patents US 2,982,749, US 4,158,726, GB 1482515 and GB 1329062) without this interfering in such a way. significant on the results observed. The stabilizer can therefore be any polymeric stabilizer but can also be an inorganic stabilizer or a mixture of the two. It is also possible to add a surfactant.

Before polymerization, the stabilizer is added to the hydrophobic phase. This phase is then degassed for 30 minutes with nitrogen with stirring (200 rpm). The aqueous phase is then dispersed and then polymerized. The polymerization times are variable and are summarized in the following table. At the end of polymerization, the beads are separated from the hydrophobic phase by filtration through a 50 μm sieve without prior dehydration step (except for X1 and X2). The beads are cleaned of their hydrophobic phase residues by a final drying in an oven (24 hours at 50 ° C). The balls are spherical in shape with a diameter between 50 μm and 1000 μm with a distribution generally centered on 350 μm. Optimization of the polymerization conditions will be accessible to the skilled person according to his personal knowledge, or by means of simple routine tests. It will thus be possible for him to play on the doses of initiators and on the possible addition of additives or transfer agents. Example 1:

The results obtained by bead polymerization as a function of the concentration of DADMAC and / or of the polymerization time (Tab 1) were compared with those of the bead polymers described in the prior art (Tab 2).

Table 2

EXAMPLE 2

In place of a DADMAC homopolymer, a 70 mol percent cationic DADMAC acrylamide copolymer is prepared using a 77% DADMAC and a 50% commercial acrylamide solution. The concentration of polymerizable material is 70%.

The polymerization lasts 45 minutes and the molecular weight of the copolymer beads is greater than 20,000,000. The addition of transfer agent of the type

10 mercaptoethanol makes it possible to control the molecular weight and thus using the same formulation to limit it to 3,560,000.

EXAMPLE 3

The homopolymer of DADMAC is in this example branched with 5000 ppm of methyl triallyl ammonium chloride, branching of DADMAC widely described in the literature (JE Morgan, MA Yorke, JE Boothe,, Adv. Chem. Ser. (1980), 187 (Ions Polym.), 235-252).

The DADMAC used is 70%. The polymerization lasts 1 hour. The molecular weight of the polymer is 7,730,000.

EXAMPLE 4

150 g of DADMAC at 85% and 32.1 g of polyamine (based on epichlorohydrin and dimethylamine) at 70% are mixed. The pH of the solution is adjusted to 4 after addition of EDTA. The content of polymerizable material in the aqueous phase is 69.6% and the content of active material in the suspension is 25%. The polymerization lasts 1 hour 30 minutes and the average molecular weight of the mixture is 3,140,000.

In conclusion, the various polymers produced according to the process of the invention, which illustrate it without however limiting it, present the improvements obtained both in terms of polymerization times (<2 hours) and in molecular weights achieved (> 2,500,000 ).

EXAMPLE 5

Comparative coagulation-flocculation tests were carried out on synthetic water. A comparison is made between the products of the invention and products sold commercially.

In order to compare the effectiveness of the different polymers under similar conditions, all of them were prepared in dilute solutions (the most common form commercially). However, use in dry form is possible and even advantageous.

The molecular weights of the polyDADMACs used in this study are estimated based on the evaluation system of patent WO 00/09453. This method, although approximate, allows a quick comparison of the molecular weights of the different products tested. The "synthetic" water of the example is prepared from tap water to which 0.015 g / l of humic acid and 2 g / l of kaolin are added.

The tests are carried out in a backlit glass column making it possible to measure a settling time between two marks spaced 26 cm apart.

The dosage in polyDADMAC is 6 ppm. The flocculant used is an acrylamide / acrylic acid copolymer of high molecular weight 10% anionic sold commercially by the applicant. The added dose is 0.5 ppm.

FL 45 CLV and FL 45 VHM are homopolymers of DADMAC in solution sold by the company SNF ™.

Percol 368 is a homopolymer of DADMAC in the form of pearls marketed by the company CIBA SC ™. The viscosities are Brookfield ™ viscosities measured with the LV 2, 3 or 4 modules and at the speed of 60, 30 or 12 revolutions per minute depending on the polymers.

EXAMPLE 6

Drip tests on paper pulp were carried out. The paper pulp is made in the laboratory by mixing 70% hardwood pulp, 10% softwood pulp and 20% mechanical pulp (white dripping value of 378 g).

This mixture is then cut with 20% calcium carbonate and diluted to 1.5% in water. 200 ml of this solution are diluted in 360 ml of water. 0.2% of polyDADMAC then 0.03% of the flocculant of Example 5 are added to this solution. The flocculated paste is then brought to 1 liter in order to carry out a CSF ("Canadian Standard Freeness") test.

The final drained mass thus makes it possible to compare the drainage qualities of the coagulants used. The results are as follows:

EXAMPLE 7

Comparative coagulation-flocculation tests were carried out on synthetic water. A comparison is made between several polyDADMACs in bead form of different molecular weights. The artificial or "synthetic" water of the example is prepared from tap water to which 2 g / l of bentonite are added.

The dosage in polyDADMAC is 6 ppm.

EXAMPLE 8

Comparative coagulation-flocculation tests were carried out on waste marble water (turbidity> 1500 NTU). A comparison is made between several polyDADMACs in bead form of different molecular weights.

The tests are carried out in a backlit glass column making it possible to measure a settling time between two marks spaced from

26 cm. After 10 minutes of decantation, 40 ml of supernatant are removed from which the residual turbidity is measured (in NTU: unit turbidity measurement standard). The dosage in polyDADMAC is 5 ppm.

EXAMPLE 9

Test carried out under the same experimental conditions as Example 8.

The polymer used is a polyDADMAC / polyamine mixture (based on epichlorohydrin and dimethylamine) in the form of beads as described on page 7 of the present application (1 18).

The results of Examples 5 to 8 show that, thanks to the process of the invention, the increase in the molecular weights of the polymers used allows a significant improvement in their performance in separation and in speed of sedimentation. It can also be seen that the process of the invention also makes it possible to obtain, at equivalent molecular weight, polymers having an increased performance compared to the techniques already known.

The present invention also covers:

polymers and copolymers obtained in beads by the methods described;

the application of the processes and polymers and copolymers described in the industry, in particular the paper industry, the treatment of water (drinkable or used), in general all the coagulation / flocculation techniques, the mining industry, cosmetics industry, the textile industry, and all similar applications which will be obvious to the skilled person;

products from the paper industry, water treatment (drinking or used), coagulation / flocculation techniques, the mining industry, the cosmetics industry, the textile industry, the products used for Bayer ™ process (alumina), obtained by implementing the processes and / or polymers and copolymers according to the invention;

as well as all the variants, either of implementation or of the process, or relating to the starting monomer (s), and so any variant or adaptation which will clearly appear to those skilled in the art, if necessary by using a few tests of routine.

Claims

1 Process for the manufacture of high and very high molecular weight beads of polymers based on a salt, or a mixture of salts, of diallyl dialkyl ammonium according to a reverse suspension polymerization process, characterized in that uses the monomer or mixture of diallyl dialkyl ammonium salt monomers at a concentration of between 67 and 77% by weight of active material.

2 Method according to claim 1 characterized in that said concentration is between 68 and 72% by weight of active material

3 Method according to any one of claims 1 to 2 characterized in that the polymerization times are reduced to less than 2 hours and generally to less than 1 hour.

4 Method according to any one of claims 1 to 3 characterized in that it does not require distillation.

5 Method according to any one of claims 1 to 4, characterized in that a branching system is added in order to obtain branched polymers in water-soluble beads of polymers of diallyl dialkyl ammonium salts of high molecular weight.

6 Method according to claim 5 characterized in that the branching agents which can be used are N-methyloI acrylamide, methylene bis acrylamide, amino triethanol, and any other multifunctional compound capable of branching, or one of the known branching agents for diallylated compounds such as chloride of methyl triallyl ammonium, triallylamine, tetraallyl ammonium chloride, tetra ailyl ethylene diamine, and more generally all polyallylated compounds.

7 Method according to any one of claims 1 to 5 characterized in that one carries out a post crosslinking. 8 A method according to any one of claims 1 to 7 characterized in that one carries out an addition of a polymer in the initial charge in order to produce a mixture of polymers in the final ball, the polymer being dissolved in the aqueous phase before dispersion of the latter in the hydrophobic phase, and the polymer may be in liquid form.

9 Method according to claim 8 characterized in that the polymers useful for blends with the polymers of diallyl dialkyl ammonium salts are all water-soluble polymers and particularly those of acrylic type and all their known cationic, anionic and nonionic copolymers, coagulants organic polyethylene imine type, polyvinylamine, epichlorohydrin-based polyamine, dicyandiamide resin, melamine formaldehyde resin which can be added for the mixture as well as inorganic polyelectrolytes such as for example polychlorides of aluminum, chlorides of aluminum, sulfates of 'aluminum.

10 Method according to any one of claims 1 to 9 characterized in that one performs a homopolymerization.

1 1 A method according to any one of claims 1 to 10 characterized in that one carries out a copolymerization of diallyl dialkyl ammonium halides with any other water-soluble monomer (quaternized, salified or not) capable of copolymerizing.

12 Method according to any one of claims 1 to 11 characterized in that a homopolymer of DADMAC is prepared.

13 A method according to any one of claims 1 to 11 characterized in that an acrylamide / DADMAC copolymer is prepared at a concentration of polymerizable material of 70%, the polymerization lasting less than 2 hours.

14 Method according to claim 13 characterized in that a transfer agent such as for example mercaptoethanol is added to the aqueous phase. 15 A method according to any one of claims 1 to 11 characterized in that a homopolymer of DADMAC branched with methyl triallyl ammonium chloride is prepared.

16 A method according to any one of claims 1 to 11 characterized in that the DADMAC monomer is mixed in the aqueous phase with a polyamine (based on epichlorohydrin and dimethylamine).

17 Method according to any one of claims 1 to 11 characterized in that the homopolymers of DADMAC obtained have molecular weights which can reach 2.5 million and up to 30 million.

18 Polymers and copolymers obtained in beads by the methods according to any one of claims 1 to 17.

19 Application of the methods according to any one of claims 1 to 17 and of the polymers and copolymers according to claim 18 in the industry, in particular the paper industry, the treatment of water (drinkable or used), coagulation techniques / flocculation, the mining industry, the cosmetics industry, the textile industry, the Bayer ™ process (alumina).

20 Products from the paper industry, water treatment (drinkable or used), coagulation / flocculation techniques, mining industry, cosmetics industry, textile industry, obtained by the implementation of the methods according to any one of claims 1 to 17 and / or of the polymers and copolymers according to claim 18.