DE19524868C2 - Process for the preparation of comb-like, branched, water-soluble cationic acrylamide copolymers with high molecular weight - Google Patents

Abstract

The present invention relates to a process for the preparation of water-soluble, precisely branched, cationic, modified acrylamide copolymers with a high molecular weight and in particular DADMAC-acrylamide copolymers. DOLLAR A In the preparation according to the process of the invention, an initial, stabilized oil-in-water emulsion is added during the progressive polymerization by adding an inverse emulsion of a water-soluble initiator in oil or by separately adding an aqueous solution of an initiator and a solution of lower Reverse HLB wetting agents in oil to a water-in-oil emulsion.

Description

The present invention relates to a ver drive to the production of new water-soluble chen, branched in a specific way, katio nisch-modified acrylic copolymers with high Molecular weight and especially on DADMAC-Arcyl amide copolymers. Copolymers of this type are in Water treatment methods useful as flocculation means for cleaning industrial water, as Sludge conditioner for urban water or as Drainage and retention aid for the paper machine position.

Due to the increasing environmental awareness at the Implementation of industrial processes and under the  Consideration of the decreasing supply of water ver associated with the obligation to use it multiple times are water-soluble polymers with a high molecular weight important products these days with ever increasing economic importance. High polyelectrolytes Molecular weights are indu in a large number strial procedure used to determine the degree of separation of solids from liquid streams through Koagu lation, flocculation, clarification, deposition, retention device or other mechanisms.

The polymerization of diallyl-dimethyl-ammonium chloro rid (DADMAC) leads to water-soluble cationic Polymers. In contrast, acrylamide gives the Polymerization water-soluble polymers, which are essentially non-ionic in nature. Hence the Copolymerization of DADMAC and acrylamide monomers to form copolymers with different Cation property, depending on the amount of DADMAC units built into the copolymer chain were.

The copolymerization of DADMAC and acrylamide in Lö solution is well known and for example in the US 2 923 701. That `s how it is known that the molecular weight of the Co polymer is limited when a solution polymer tion process is applied. In many examples The prior art therefore tries to do this by using an emulsion polymerization tech nik to overcome. According to the teaching of the U.S. patent No. 3 920 599, for example, stable water-in  Oil copolymer emulsions prepared or it will Production of stable emulsion copolymers from DADMAC and acrylamide in US 4,077,930 which is inverted by the addition of water can be. In other patents he is clarifies that the use of different types of initiators for latex copolymerization should be preferred, as in the case of the US 4,439,500, with ammonium persulfate being the preferred is a free radical initiator, or in the case of the CA. 2,021,984, in which 2,2'-azobis- (2,4- Dimethyl) valeronitrile as an excellent initiator is published.

The addition of chain transfer agents to the prevention change in gel formation during the polymerization considered necessary in any case. Suitable ket Transfer agents are at the beginning of the polymer tion process added. Examples of such Additives are low alkyl alcohols or mercaptoal kohole, but halogenated kohlwas used to suppress gel formation. The Contents of otherwise similarly performed synthesis The procedure is the use of special types of ket means of transmission. So in the case of the CA 2 063 656 the need for natri Formation added at the end of the polymerization to obtain a gel-free latex copolymer. In contrast, in EP 0 363 024 preferred use of sodium hypophosphite as a Chain transfer agent explained. The addition of the Chain transfer agent is also here at the end of  Procedure carried out immediately before a last heating period follows to increase the residual monomer content minimize.

Because of the very different reactivities of acrylamide and DADMAC at the free radical Polymerization results in different copoly merization parameters (Jaeger et. al. Acta Polymerica 36: 100-102 (1985). Therefore, at an intermit copolymerization process in the beginning Lichen phase formed of polymer chains rich in acrylamide. Later increases due to the rapidly decreasing acrylic the concentration in the reaction mixture of DADMAC in the copolymer. Also listen the reaction with a DADMAC conversion of approx. 80% on. This disadvantage is common to all publications of the prior art mentioned, for example in the CA 2 021 984, CA 2 063 656 or U.S. 3,920,599.

To increase the level of DADMAC conversion, however also because of achieving a more even Distribution of the cationic functional groups in the copolymer is described in EP 0 363 024 a gradual or continuous acrylamide pull but released to the original latex that only part of the necessary acrylamide concentration contains. On the other hand, this process leads to poly mer with molecular weights that are significantly lower are compared to polymers that correspond by a intermittent process the.  

It is known that the application properties ser soluble polymers their polymer molecular weight correspond. Furthermore, it is more general today knows that the increase in polymer molecular weight by chain branching to polymers with improved Properties leads. EP 0 374 458 ver publishes the synthesis of such a type DADMAC acrylamide polymer emulsion using ge small amounts of polyfunctional monomers such as Methylenebisacrylamide as a chain branching agent and EP 0 374 457 describes the same Ver drive in an inverse microemulsion. Due to the Risk of gel formation from an uncontrolled The polyfunctional monomers are overdosed Using polyfunctional monomers from the standpoint the reaction security from disadvantageous.

An improved process for the synthesis of branches ten acrylamide copolymers is in the US 5 211 854. The problem of gel formation during the copolymerization due to use polyfunctional copolymers thereby the Co polymerization of acrylamide with a cationic Macromonomer containing units prevented. On this type of comb-like polymer structures Obtained acrylamide as a polymer backbone, the cationic charges as chain units of the sides chain are arranged. The macromonomer comes in one introductory synthesis step in a solution po Synthesis process synthesized, with Glückli Peroxide as a free radical initiator and Cu (II) sulfate as an oxidative chain transfer  Resource is used to form a terminal unung to produce saturated double bond. The received Macromonomer is then considered the cationic component used in the copolymerization with acrylamide, whereby the polymerization process in a conventional inverse emulsion technology is carried out.

US 5,298,566 describes comb-like branches water-soluble polymers by radical Copolymerization of water-soluble monomers (e.g. Acrylamide) with water-soluble macromonomers (e.g. Acrylamide copolymer with cationic chain units) getting produced.

The aim of the present invention is a method for the production of new, water-soluble, quaternary Branched, cationic ammonium groups High molecular weight acrylamide copolymers to develop, with DADMAC being the preferred cationi are monomer units.

The invention is characterized by the characteristic features of claim 1 solved. Give the subclaims advantageous embodiments. The so made th cationic, branched copolymers are through characterized a comb-like structure, in which In contrast to the copolymers of the prior art cationic functional groups units of a rigid polymer backbone, however the acrylamide units in the side chains of the Macromolecule are arranged.  

The general structure of the backbone of the prepared comb-like cationic copolyelectrolytes of the invention is shown in Formula 1:

- [A-B-NR -] -

The sequence - [AB-NR -] - represents a rigid backbone of repeating cationic monomer units [A], which contains a well-defined amount of tertiary functional amine groups [B-NR-]. The chain units [A] preferably consist of DADMAC, but other cationic, monomeric structures are also like
2-acryloyloxy-ethyl-trimethyl-ammonium chloride,
3-methacrylamidopropyl trimethyl ammonium chloride or
2-methacryloyloxyethyl trimethyl ammonium chloride useful for the formation of the polymer structure.

The functional unit [B-NR-] of the backbone chain includes a component that comes from the class of ethylenically unsaturated and an amine function ent holding monomers such as dialkyl aminopropyl methacrylic Amide, dialkyl aminoethyl acrylate or dialkyl amino ethyl methacrylate and diallylalkylamine selected is. The preferred structure of the sequence is [B-NR-] however, triethanolamine.

The water-soluble, comb-like, cationic polyelectrolytes are polymers based on Acrylamide as well as on a suitable water-soluble chen, cationic prepolymer based on min least 1 mol% up to 50 mol% from amine functions  containing compounds.

The molecular weights of the combs produced branched cationic acrylamide copolymers are in the generally very high, the molecular weights are however, applying the general laws of the free radical polymerization adjustable.

The new graft copolymers are according to the invention via a two-step polymerization process manufactured. First, the amine group containing Prepolymer by a free radical copolymer sation of DADMAC and the unsaturated amine monomer in a known manner or by DADMAC homopolymeri sation using a special redox inti tion system made of triethanolamine and ammonium persulfate. The polymerization is preferably in a solution polymerization technology carried out.

The graft copolymerization of acrylamide onto the Cationic prepolymer containing amine groups mostly follows in a water-in-oil emulsion technology. Surprisingly, no polymer is found sation instead if an aqueous solution of the Initia tors to a water-in-oil emulsion of the active mole cool in a hydrocarbon is added.

It was therefore very surprising that the Polymerisa tion progresses very steadily when the polymerisa tion process with an oil-in-water emulsion a point in time before a phase reversal takes place  begins; the phase reversal is achieved by adding a Water-in-oil emulsion of the initiator performed. As far as possible, the separate addition of the aq initiator solution and the solution of the low HLB Wetting agent used in a hydrocarbon become, which leads to comparable polymerization results nits leads.

In general, the polymer emulsion can be prepared using any organic liquid of the following type as a solvent:

• - Aromatics such as benzene, toluene or xylene or
• - aliphatic hydrocarbons, mineral oils, Kerosene, petroleum.

A particularly useful oil is the branched chain Isoparaffin solvent with the trade name "Isopar M".

As an emulsion for stabilizing the inverse Mixed systems are distinguished from emulsions types of wetting agents used. Therefore, Sorbitan esterty low HLB wetting agent pus (products of the SPAN series, ICI) can be selected and a preferred emulsifier is sorbitan monooleate (SPAN 80). As a stabilizer with a higher HLB value fortunately polyoxyethylene modified Sorbi tanester (TWEEN products, ICI) is used. In addition, NEN polymeric wetting agents as part of the Sta bilization system can be used. However, it must be a HLB value of the wetting agent mixture between 5 and  7 can be achieved.

The oxidant in the initiation system is one Salt of persulfuric acid, preferably ammonium per sulfate.

The water phase consists of acrylamide, DADMAC prepo lymer, which is a reduction component of the initiation systems, and caustic soda, the proportion of which Ingredients between 20 and 70% by mass and preferred fixed proportion between 40 and 60 mass% lies, and is by blowing with nitrogen gas freed from oxygen. The sow is separated from this erstoff from the organic phase, which from the Koh Hydrogen liquid and a selected one High HLB wetting agent is by blowing removed with nitrogen gas.

Separated from this is an oxygen-free, inverse Emulsion of the oxidation component of the initiator Stems manufactured, the oil phase one or more Contains wetting agents caused by low HLB who te are marked.

The initiator emulsion is separated or continuously to the oil-in-water emulsion given.

The reaction temperature is in the course of all steps te of the polymerization process kept constant and is preferably between 15 and 50 ° C set between 20 and 35 ° C.  

The novel water-in-oil emulsions, which are under Use of the ingredients described here and produced by the methods described here have low macro viscosities and are characterized by a high degree of stability. The following examples are for the purpose only the explanation shown and are not as Be limitations of the present invention.

Example 1:

The inverse emulsion polyemeration was carried out in one double-walled 1 l glass reactor carried out with provided with a special stirrer made of stainless steel was. The stirrer speed was during the Pha se the initiator addition at 750 rpm and in the polymer Risation phase selected to 300 rpm.

Preparation of the aqueous phase:

The glass reactor was treated with 140 g of 60% aqueous solution solution of acrylamide and a solution of 84 g of one DADMAC prepolymer containing 3 mol% of triethanolamine units contained in 75 g of water. The vis The mixture was stirred under gentle agitation for 30 minutes Blow through with nitrogen gas before adding 2 g of 1N NaOH was added.

Production of the oil phase:

5 g of Tween 85 were mixed in 100 g of Isopar M in one Detached container and the mixture was mixed with  Blow through nitrogen for 30 minutes.

The oil phase then became that within 5 minutes added aqueous phase and the oil-in Water emulsion was continued with nitrogen 30 Blow through for minutes. At the same time, the Reak tion mixture tempered to 25 ° C.

A water-in-oil emulsion of the Initiator made in Isopar M. For this emul solution was a solution of 50 mg ammonium persulfate in 30 g water in a mixture of 3 g Span 80 and 7 g Hypermer 2296 in 30 g Isopar M using a Ultraturrax dispersed at 8000 rpm. The received Emulsion was also nitrogen for 30 minutes blow through.

The initiator emulsion was then within 30 minutes added to the primary emulsion, resulting in a subsequent inversion of the initial latex leads. The latex was at a regulated tempera polymerized from 25 ° C for four hours. It was de low viscous, stable latex with a through average particle size of 5 microns obtained. The complete polymerization conversion was through Gravimetry detected. The phase reversal was by adding 10 g of latex to a mixture of 1 g High HLB wetting agent (Nonidet P40, FLUKA) in 150 g deionized water at 60 ° C with agitation using a propeller stirrer at 3000 rpm carried out. The viscosity (specific viscos act / c) a 0.2% solution of the inverted sample  in 1 N NaCl was determined to be 10.34 dl / g.

Example 2:

The same procedure as in Example 1 was used uses and the production of the primary emulsion was also carried out in the same way it was de changed the addition rule. The influx releasing reagents (the aqueous persulfate solution and the oil mixture) were made using two ge of separate pump currents. The analysis of the closing achieved stable latex resulted in complete Polymerization conversion and the viscosity of one inverted sample was also in the same size order (10.08 dl / g). It was a change tion observed in the particle size distribution. It there was a wider distribution with one average size of 8 µm.

Example 3:

The same rule was used as above. The Reagent addition was divided into two steps. To complete addition of the first portions of the separated th oil or water phase resulted in an HLB value of Systems of 9. At this point the reaction under the reaction conditions for 30 minutes before starting the second addition phase.

The reagents added are shown in Table 1 ben.  

Table 1: Graft copolymerization by inverse emulsion polymerization

After the end of the second addition period, the Polymerization for another four hours at the reak tion temperature of 25 ° C continued. It surrendered a stable latex. The polymerization conversion was 100%. The latex was through a double modal particle size distribution with almost two same maxima of the distribution curve at 1.5 and 10 µm marked. The viscosity of the 0.2% Solution of an inverted sample in 1 N NaCl became too 13.36 dl / g determined.  

Examples 4 and 5:

The same procedure as in Example 1 was followed leads the ratio of DADMAC prepolymer to Acry lamid was changed, however. The added reagents tien and the values of the viscosity (specific Visko sity / c) of the 0.2% solutions of the obtained Graft copolymers in 1 N NaCl are listed in Table 2 leads.

Table 2: Graft copolymerization by inverse emulsion polymerization

The emulsions obtained were stable for a long time bil, the particle sizes were determined to be 4.5 µm and a 100% polymerisation conversion into received two comparative experiments.

Examples 6 and 7:

In the following comparative examples, the Peculiarity of the polymerization process under Be using a polymeric compound as part of what initiation system compared to one ordinary inverse emulsion technique shown.

It was the same process for making one Graft copolymer emulsion as used in Example 1. A copolymer from DADMAC was used as the DADMAC prepolymer with dimethyl aminoethyl methacrylate with 5.5 mol% Amine functions used. The following table 3 ent holds the added reagents for both experiments te.

The latex polymerization of the comparative example 6 gave a stable copolymer emulsion in which the monomeric acrylamide was completely converted.

The viscosity of the 0.2% solution of an inverted th copolymer sample in 1 N NaCl became 11.37 dl / g certainly.

In the polymerization example 7, in the persulfate was added in aqueous solution was carried out internally no poly within a response time of eight hours  merization.

Table 3: Regulation used in the comparative tests

Claims (5)

1. A process for producing a comb-like branched, water-soluble cationic acrylamide copolymer, in which with
1-40 mol% of a stiff cationic water-soluble prepolymer backbone of the general formula I
- [AB-NR -] - I
wherein A is an unsaturated ammonium compound and B-NR- from the class of ethylenically unsaturated, functional amine-containing monomers or from triethanolamine or diethanolalkylamine and the proportion of B-NR- 1 up to 50 mol%,
and 60-99 mol% of an acrylamide
a graft copolymerization is carried out by means of an inverse emulsion polymerization process in the form of a free radical polymerization using a redox initiation system, an initial, stabilized oil-in-water emulsion being added during the progressive polymerization by adding an inverse emulsion of a water-soluble initiator in oil or by separately adding an aqueous solution of the initiator and a solution of low HLB wetting agent in oil to a water-in-oil emulsion, the prepolymer containing amine units being the reducing agent and a salt of persulfonic acid being part of the initiation system and that the initial oil-in-water emulsion stabilized by a high HLB wetting agent reaches between 75 and 95% of the mass of the entire batch. 2. The method according to claim 1, characterized records that the initial oil-in-water Emulsion 80-90 mol% of the total batch replaced. 3. The method according to claim 1 or 2, characterized characterized in that the persulfate salt in a aqueous solution and wetting agent with low HLB, dissolved in oil, separated and at the same time as the initial oil-in-water Emulsion are added and that the same Proportions of both the aqueous and the oil phase 5-25%, preferably 10-20% of the total batch to reach. 4. The method according to at least one of claims 1 to 3, characterized in that the unsaturated ammonium compound is selected from 2-acryloyloxy-ethyl-trimethyl-ammonium chloride, 3-methacrylamidopropyl-trimethyl-ammonium chloride, 2-methacryloyloxy-ethyl-trimethyl-ammonium chloride , but preferably diallyl dimethyl ammonium chloride (DADMAC).

• 1. The method according to at least one of claims 1 to 4, characterized in that the ethylenically unsaturated amine-containing monomers are selected from dialkyl aminoethyl acrylates, dialkyl amino ethyl methacrylates, dialkyl aminopropyl acrylamides, dialkyl aminopropyl methacryl amides , alkyl-substituted and unsubstituted diallylamines.

6. The method according to at least one of claims 1 to 5, characterized, that the comb-like branched polyelectrolyte Molecular weight <1 million, preferred <10 million g / mol.