WO2003100169A1

WO2003100169A1 - Process for preparing a dispersion polymer

Info

Publication number: WO2003100169A1
Application number: PCT/IB2002/001865
Authority: WO
Inventors: Sungwook Han
Original assignee: Green Technology Inc.
Priority date: 2002-05-27
Filing date: 2002-05-27
Publication date: 2003-12-04
Also published as: AU2002310569A1

Abstract

The method of the invention is directed to the polymerization of acrylamide and cationic or anionic monomer(s) in a salt solution with the use of PEI (Poly Ethylene Imine), SMA (Styrene Maleic Anhydrous) and non-ionic surfactant mixture as dispersant and the incorporation of PAC (Poly Aluminium Chloride) and/or a collodial silica during the polymerization for performance enhancement.

Description

Process for Preparing a Dispersion Polymer

Field of Invention

The present invention is in the technical field of preparing a dispersion polymer to be used as retention/drainage aids in papermaking and wastewater treatment and emulsion breaker. This process requires the use of PEI(Poly Ethylene Imine), SMA(Styrene Maleic Anhydrous) and non ionic surfactant mixture as dispersant, and the use PAC(poly aluminum chloride) and/or a colloidal silica.

Background of the invention

The field of invention

The invention relates to the field of retention, dewatering, and formation aids in papermaking process and wastewater treatment, oil-water separation with hydrophilic dispersion polymers.

In the manufacture of paper, an aqueous cellulosic suspension or slurry is formed into a paper sheet. These three aspects in the below is extremely important for the cost effective papermaking.

1) Drainage:

The cellulosic slurry generally contains less than 1 % solids contents (dry weight basis) whereas the finished sheet is required to have more than 94% solid contents. The most cost effective dewatering process is drainage. Also used, yet less cost effective, are felt blanket, blotting, pressing, evaporation, pressing, vacuum etc. as dewatering methods. Since the drainage is the most cost effective and the very first step of dewatering, any improvement of performance of drainage greatly affects the cost and efficiency of dewatering in papermaking. 2) Retention:

The paper furnish contains cellulosic fibers (2-3 millimeter in size), mineral fillers (added to enhance brightness, opacity and other paper characteristics, typically a few micrometers in size), small particles, and other furnish components. Maximum retention of cellulosic fiber, mineral filler, and other small particles on the fiber mat leads to numerous benefits for papermakers.

A) Retention of Mineral Fillers:

Most widely used mineral fillers, such as Calcium Carbonate, Clay are often less expensive than fibers. These mineral fillers are a good substitute for cellulosic fibers when retained properly in the papermaking process. These mineral fillers also often required to be used to achieve a certain sheet properties (brightness, opacity, optimum interaction with printing ink).

B) Retention of other furnish components, particularly small particulates:

As the fiber mat is formed on the wire (typically 200 mesh), these small particulates are not retained and pass through the spaces (pores) between cellulosic fibers in the fiber mat being formed on the wire in papermaking process. The maximum retention of these small particulates is most desired in papermaking process because they can be attached to additives, such as sizing agents, dyes and others, in significant portion, further prohibit the effective performance of these additives. Many papermills recycle their Whitewater. With continuous recycle of Whitewater back into the furnish, the amounts of small particulates increase in the furnish. These further levels prohibit, to a large degree, the effective performance of expensive functional additives, such as Titanium oxide upon recycling of Whitewater. The increased concentration of small particles in the furnish in Whitewater can cause deposit problems, which leads to poor runnability, and poor product quality. An effective retention of mineral fillers, and small particles in the furnish leads to (1) reduced usage of cellulosic fiber, (2) enhanced performance of functional additives, such as sizing agent, and Titanium Oxides, (3) enhanced performance of mineral fillers, (4) reduction in waste material and its disposal, (5) raw material cost saving, (6) enhanced processing, runnability, product quality, and (7) cleaner Whitewater, which will contribute to lower the papermaking cost in overall.

3) Formation: It relates to level of uniform density and thickness of paper and paperboard both on any particular point of the sheet and across the width of the sheet. When retention and drainage aids are applied to form a floe in wet end, the size of the floe is to do with the formation, retention, and drainage. Large floe may be good for retention and drainage, but leads to poor formation. Small floes may bring much better formation, however it may adversely affect retention and drainage. As the retention increase to higher level over 75%, it is known that the formation becomes an apparent problem in papermakings.

In the field of wastewater treatment, sludge dewatering, and oil-water separation application, using water soluble dispersion polymer without oil is important and effective way for those applications. Furthermore, the product from this invention offers ease of use and handling, free from fire hazard(no oils).

Description of the Prior Art.

U.S. Patents Nos. 5,098,520 and 5,185,062 disclose to add high molecular weight cationic polymer and then a medium molecular weight anionic polymer (which includes ionizable sulfonate) to papermaking cellulosic slurry, to improve drainage and retention.

U.S. Patents Nos. 4,753,710 and 4,913,775 teach, in order to improve retention and drainage, to add to an aqueous cellulosic papermaking suspension (1) a high molecular weight linear cationic polymer before shearing the suspension, followed by the addition of (2) bentonite after shearing. The shearing is generally provided by one or more of cleaning, mixing, pumping of papermaking process. The shearing breaks down the large floes formed by the high molecular weight polymer into microflocs, and further agglomeration then ensues with the addition of bentonite clay particles. U.S. Patent No. 6,238,521 teaches to add coagulants (such as starch, low molecular weight cationic synthetic polymers, alum), to add a cationic dispersion polymer which is a copolymer comprising about 30 mole % of DADMAC (diallydimethylammoniumchloride) and about 70 mole % Acrylamide before shearing. Either before or after the a cationic dispersion polymer in the above is added, mieroparticles selected from the group consisting of copolymer(anionic) of acrylic acid and acrylamide, bentonite, dispersed silica are added.

U.S. Patent No. 6,059,930 discloses adding of an effective amount of a hydrophilic dispersion polymers (preferably a copolymer of DMAEA.MCQ(dimethylamonoethyl acrylate methyl chloride quaternary) and acrylamide to an aqueous cellulosic papermaking slurry to improve retention and drainage. These also have been different types of dispersion polymer preparation methods. The polymerization method of a dispersion polymer in salt solution is well known art for many years. It is based on the phenomena of salting out that particles dissolved in the salt solution are changed to crystals, and larger particles as the salt concentration of the salt solution changes.

U.S. Patent No 6059930(Nalco) teaches the use of preferred dispersants include homopolymers of diallyldimethyl ammonium chloride(DADMAC), dimethylaminoethyl acrylate methyl chloride quaternary salt(DMAEA.MCQ) and dimethyl- aminoethyl methacrylate methyl chloride quaternary salt(DMAEMA.MCQ).

EP Patent No 637598(Nalco)discloses that the dispersion polymer is made by using dispersant comprises copolymer of DADMAC and DMAEA.BCQ or of DADMAC/EHA

EP 657478 Patent No. indicates the salt concentration of the aqueous solution where dispersion polymer is made is 17-19% by weight of a polyvalent anionic salt U.S. Patent No. 4929655(Kyoritsu Co) teaches the cationic monomer represented by the formula (I) is meth)acryloyloxyethyldimethylbenzylammonium chloride. The other cationic monomer represented by the formula (II) is (meth)acryloyloxyethyltrimethylammonium chloride. The organic high-molecular multivalent cation is a polymerization product of water-soluble monomers comprising 20 to 100 mole % of (meth)acryloyloxyethyltrimethylammonium chloride and 80 to 0 mole % of (meth) acrylamide.

U.S. Patent No 5938937(Nalco) discloses that cationic monomer is selected from group consisting of DMAEA.MCQ, DMAEM.MCQ and DADMAC. The dispersant polymer is used in an amount of from 1 to 10 percent by weight based on the total weight of monomers. The dispersant polymer is composed of preferably 20 mole percent or more of cationic units such as DMAEA.MCQ, DMAEM.MCQ and diallyidimethylammonium chloride (DADMAC).

U.S. Patent No 5587415 teaches the use of, the quaternary aliphatic halide salts of dimethylaminoethyl(meth)acrylate as the cationic monomer and the like is employed instead of the quaternary benzyl chloride salts.The cationic polymer dispersant is the polymerization product of one or more hydrochloric acid or sulfuric acid neutralized or methyl chloride or dimethyl sulfate quarternized monomer selected from the group consisting of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminohydroxypropyl (meth)acrylate, and dimethylaminopropyl (meth)acrylamide.

EP Patent No. 717 056 discloses that the amphoteric dispersion polymer is obtained by polymerizing a mixture of monomers comprising a cationic monomer Formula (I), (II) and an anionic monomer in aqueous salt solution.The cationic monomer represented by the formula (I) is (meth)acryloyioxyethyldimethylbenzylammonium chloride. The other cationic monomer represented by the formula (II) is (meth)acryloyloxyethyltrimethylammonium chloride. However, there is a better way to prepare dispersion polymers using PEI(Poly Ethylene Imine), SMA(Styrene Maleic Anhydrous), non ionic surfactant mixture as dispersant with incorporation of a colloidal silica and/or inorganic flocculants for the enhanced performance with these added benefits.

1 ) Water soluble, contains no unwanted oils.

2) Easy of handling — simple static mixing. No aging, no conditioning often associated with an inverse water in oil emulsion polymer, is required.

3) Enhanced performance over water-soluble dispersion polymer in the area of retention, drainage, and formation which is made with PEI and/or

SMA as dispersants and which contains a colloidal silica or a PAC(Poly Aluminum Chloride).

4) The product with PAC(Poly Aluminum Chloride) and/or a colloidal silica incorporated during the polymerization process offer suprising performance enhancement over similar types of dispersion polymer without PAC(Poly Aluminum Chloride) and/or a colloidal silica in the polymer solution. It is more convenient, economical one step process over the process which require addition of dispersion polymer and these inorganic flocculants and/or colloidal silica in the papermaking process and wastewater treatment, oil-water separation application.

Summary of the invention

The method of the invention calls for polymerization of acrylamide and cationic or anionic monomer(s) in salt solution with the use of PEI(Poly Ethylene Imine), SMA(Styrene Maleic Anhydrous) and non-ionic surfactant mixture as dispersant and the incorporation of PAC(Poly Aluminum Chloride) and/or a colloidal silica during the polymerization for performance enhancement.

Detailed Description of the invention

The object of the present invention is to provide a dispersion of a water-soluble nonionic, cationic and/or anionic polymer prepared by use (meth)acryalamide and 1)use of a cationic monomer mixture consisting essentially Formula I and/or Formula II and/or DMAEA.DMSQ(dimethylaminoethyl acrylate dimethylsulfate quatemized monomer)

formula I

wherein R1 is hydrogen atom or methyl; R2 and R3 are each independently alkyl group having 1 to 3 carbon atoms; A1 is oxygen atom or NH;

B1 is alkylene group having 2 to 4 carbon atoms or hydropropylene; and X1 is anionic counter ion.

CHι -=C — R- s X_x" l- I

O -= C — Az — θι~ N*— R j

I

formula π

wherein R4 is hydrogen atom or methyl;

R5 and R6 are each independently alkyl group having 1 to 2 carbon atoms; R7 is hydrogen atom or alkyl group having 1 to 2 carbon atoms; A2 is oxygen atom or NH;

B2 is alkylene group having 2 to 4 carbon atoms or hydropropylene; and X2 is anionic counter ion.

or 2) by use of Nonionc monomer, such as Acrylamide or 0-97 mol% Methacrylamide.

3) by use of Anionic monomer, such as Acrylic acid or 0-30 mol% Itaconic acid.

The polymerization, copolymerization, terpolymerization is carried out in an aqueous salt solution which can dissolve the monomers used, but does not dissolve the resulting polymer, copolymer, or terpolymer with stirring and in the presence of a dispersant which is mixture of PEI(Poly Ethylene Imine) and SMA(Styrene Maleic Anhydrous). In the invention, PAC(Poly Aluminum Chloride) controls the formation of the nuclei, thus control the speed of the polymerization. It also neutralizes the negative charges of fine particle and anionic trash material, which result in enhanced retention in papermaking, and enhanced flocculation in wastewater treatment. PEI(Poly Ethylene lmine)contributes the speed control of polymerization and suppress the dramatic viscosity increase during the polymerization process. Its high electrical charges help to produce the smaller size polymeric particles since the high charged PEI prohibits with a strong repulsion the particles formed in a large size. SMA(Styrene Maleic Anhydrous) contributes the enhanced nuclei formation, resulting in better speed control of salting out and overall polymerization. Non ionic surfactant helps the formation of the nuclei and small size particle. It also contributes the stable dispersion of the particle with increased repulsion between particles being formed through steric structure.

Any salts may be employed for preparing the aqueous dispersion, so long as they do not dissolve the resulting polymer. Typical examples of the salts include polyvalent anion salts such as sodium sulfate, ammonium sulfate, magnesium sulfate, aluminum Sulfate

As for the salt concentration, it will depend on the molar ratio of cationic monomers represented by the formulas (1) and (2), and the kind of the salt employed. In general a range of from 20-25% by weight. According to the present invention the kind and the amount of the used salt in the aqueous salt solution is such that the employed monomers and the employed dispersant are dissolved but the resulting polymer are not dissolved in the aqueous salt solution.

The preferred amount of dispersant is between 1-10% by weight, based on the total weight of monomers. When the amount of dispersant is less than 1 % by weight, the polymerization gives sticky polymer particles which tend to result in separation of a bulky polymer mass. The polymerization temperature will depend on the kind of the initiator. The preferred initiator is azo type initiators.

The polymer dispersion of the present invention is used in the waste water treatment field as a flocculants, and in the paper manufacturing field as a paper chemical. The flocculants is used as a floating agent or a dehydrating agent, and in the paper chemical is used as a retention aid for a sizing agent and as a . drainage aid.

In the waste water treatment, the dispersion according to the present invention may be diluted as an aqueous solution, and may be added into the waste water comprising sludge. Then, the comprised sludge is flocculated by the polymer, and the flocculated sludge is then filtrated and dehydrated, or is then floated and raked together.

When the dispersion of the present invention is used in the waste water treatment process as a flocculants, it shows higher floatation speed and improved dehydrating capacity.

In the paper manufacturing process, the dispersion according to the present invention may be fed into the process as a dilute aqueous solution. When making paper, the contained water must be smoothly drained. On the contrary, the contained paper chemicals, e.g a sizing agent, must be certainly retained therein. Accordingly, it is necessary for the polymer to have a property so as to highly drain the contained water and/or a property so as to certainly retain the contained paper chemical agents. Examples

The following examples are intended to be illustrative of this invention and show the ordinary skill how to use and make the invention. These examples are not intended to limit the invention or its protection in any way.

Throughout examples and claim, these terms have following meanings.

1 Dispersion Polymer: Polymers made by a precipitation polymerization process which produces well defined particles, containing very high molecular weights.

2 VA-044 and VA-50:azo type initiator from Wako(Japan)

3 DMAEA.MCQ- dimethylaminoethyl acrylate methyl chloride quaternary

4 DMAEA.BCQ- dimethylaminoethyl acrylate benzyl chloride quaternary 5 DMAEA.DMSQ- dimethylaminoethyl acrylate dimethylsulfate quaternary

Example 1

Add to reactor and stir them at 250 rpm at 32C with nitrogen gas purge for 20 minutes Ammonium sulfate 134.094g, 50% acrylamide 207.229g, 80% benzyl chloride quatemized acrylate monomer 20.482g, 20% poly-methyl chloride quatemized acrylate 6.000g, 25% active solid polyethyleneimine (PEI) solution 24.000g, 40% active solid styrene maleic anhydride (SMA) resin solution 12.000g, nonionic surfactant 0.240g, Glycerin 1.200g, PAC (poly aluminum chloride 12.000g, deionized water 326.449g.

Add to the reactor 0.012 gram of VA-044 and stir them at 250 rpm at 32C for 6 hours. After first 6 hours of reaction, add to the reactor 0.024 gram of VA-044 and stir them at 250 rpm at 32C for 12 hours. Add to the reactor 56.306 gram of sodium sulfate to get about 600 gram of the product. The viscosity of 3% solution of the product is 102 cps.

Example 2 Add to the reactor ammonium sulfate 135.957g, 50% acrylamide 168.812g, 80% benzyl chloride quatemized acrylated monomer, 44.493g, 25 % active solid polyethyleneimine (PEI) solution 36.000g, 40% active solid styrene maleic anhydride (SMA) resin solution 24.000g, nonionic surfactant 0.300g, Glycerin 3.000g, sodium citrate 3.000g, cationic colloidal silica 24.000g, deionized water 306.796g and stir them at 250 rpm at 47C with nitrogen gas purging for 20 minutes.

Add 0.012 gram of V-050 and stir them at 250 rpm, at 47C for 4 hours.

Add to the reactor 6 gram of 20% poly methyl chloride quatemized acrylate and 0.024 gram of VA-050 and stir them at 250 rpm, at 47C for 12 hours.

Add to the reactor 47.643 gram of sodium sulfate to produce about 800 gram of the product. The 3% solution viscosity of the product is 75 cps.

Example 3

Add to the reactor ammonium sulfate 123.81 Og, 50% acrylamide 127.326g, 80% benzyl chloride quatemized acrylate monomer 78.609g, 80% methyl chloride quatemized acrylate monomer 17.821 g, Itaconic acid 3.192g, 20% poly-methyl chloride quatemized acrylate 7.200g, 25% active solid polyethyleneimine (PEI) solution 14.400g, 40% active solid styrene maleic anhydride (SMA) resin solution 21.600g, nonionic surfactant 0.360g, Glycerin 4.320g, potassium carbonate 5.000g, PAC (poly aluminum chloride 36.000g, deionized water 293.931 g and stir them at 250 rpm at 35C with the nitrogen gas purging for 20 minutes. Add to the reactor 0.012 gram of VA-044 and stir them at 250 rpm at 35C for 6 hours. Add to the reactor 0.024 gram of VA-044 and stir them at 250 rpm at 35C for 12 hours. Add to the reactor 66.430 gram of ammonium sulfate to produce about 800 gram of the product. The 3% solution viscosity of the product is 97 cps.

Example 4

Add to the reactor ammonium sulfate 125.043g, 50% acrylamide 51.968g, 80% benzyl chloride quatemized acrylate monomer 123.271 g, 80% methyl chloride quatemized acrylate monomer 44.249g, 20% poly-methyl chloride quatemized acrylate 8.000g, 25% active solid, polyethyleneimine (PEI) solution 32.000g, 40% active solid styrene maleic anhydride (SMA) resin solution 24.000g, nonionic surfactant 0.400g, cationic starch 10% solution 40.000g, deionized water 300.512g and stir them at 250 rpm at 35C with the purging of nitrogen gas for 20 minutes. Add to the reactor 0.012 gram of VA-044 and stir them at 250 rpm at 35C for 6 hours. Add to the reactor 6 gram of sodium citrate and 0.024 gram of VA-044 and mix them for 12 hours. Add to the reactor 44.557 gram of ammonium sulfate to produce about 800 gram of the product. The 3% solution viscosity of the product is 84 cps.

Example 5

Add to the reactor ammonium sulfate 114.094g, 50% acrylamide 21.955g, 80% benzyl chloride quatemized acrylate monomer 130.197g, 80% methyl chloride quatemized acrylate monomer 56.082g, 20% poly-dimethyl sulfate quatemized acrylate δ.OOOg, 25% active solid polyethyleneimine (PEI) solution 24.000g, 40%) active solid styrene maleic anhydride (SMA) resin solution 1 δ.OOOg, nonionic surfactant 0.160g, sodium citrate 1.500g, anionic colloidal silica 16.000g, deionized water 371.007g and mix them at 250 rpm at 47C with nitrogen gas purging for 20 minutes. Add to the reactor 0.012 gram of V-50 and continuously mix them for 4 hours. Add to the reactor 1.5 gram of sodium citrate and 0.024 gram of V-50 and mix them for 12 hours. Add 39.5 gram of ammonium sulfate to produce the product. The 3% solution viscosity of the product is 53 cps.

Example 6

Add to the reactor Ammonium sulfate 136.888g, 50% acrylamide 186.772g, 80% dimethyl sulfate quatemized acrylate monomer 33.268g, 20% poly-methyl chloride quatemized acrylate 6.000g, 25% active solid polyethyleneimine (PEI) 24.000g, 40% active solid styrene maleic anhydride (SMA) resin solution 12.000g, nonionic surfactant 0.300g, Glycerin 3.000g, PAC (poly aluminum chloride 12:000g, deionized water 342.161 g. and mix them vigorously with homomixer for 30 minutes. We, then, purge the nitrogen gas to the reactor at 32C for 20 minutes. Add to the reactor 0.012 gram of VA-044 and mix them well at 800 rpm for 2 hours first and at 250 rpm for the next 4 hours. Add to the reactor 0.024 gram of VA-044 and mix them well at 800 rpm for 6 hours. Add to the reactor 0.3000 gram of nonionic surfactant. In 30 minutes, add to the reactor 43.312 gram of sodium sulfate while mixing at 250 rpm to produce about 800 gram of product. The 3% solution viscosity of the product is 101 cps.

Example 7

Add to the reactor ammonium sulfate 128.339g, 50% acrylamide 214.788g, 20% poly-methyl chloride quatemized acrylated monomer 5.400 gram, 25 % active solid polyethyleneimine (PEI) solution 14.400g, 40% active solid styrene maleic anhydride (SMA) resin solution 15.000g, nonionic surfactant 0.240g, Glycerin 3.600g, PAC 12 gram, deionized water 321.614g and stir them at 400 rpm at 25C with nitrogen gas purging for 20 minutes and add 1 % solution of ammonium persulfate 0.24 ml and 1 % solution of sodium persulfate 0.12 ml to initiate the reaction. For the next 3 hours, drop the 80% benzyl chloride quatemized acrylate monomer 15.757 gram. When the temperature reach 32C, start mix at 250 rpm. 3 hours later, add 0.012 gram of VA-044. In 6 hours, add 0.024 gram of VA-044 and mix at 400 rpm at 35C for 4 hours. Add to the reactor 68.861 gram of sodium sulfate to produce about 800 gram of the product. The 3% solution viscosity of the product is 110 cps.

To sum it up, the invention describes a processes of making water soluble, hydrophilic dispersion polymer containing a colloidal silica or an inorganic flocculant with the following features:

1 ) The process requires to use cationic or anionic monomer plus non ionic acrylated monomer and PEI(Polyethyleneimine),SMA(Stayrene Maleic Anhydride), non ionic surfactant mixture as dispersants in the anionic salt solution under the existence of free radical initiator. The product from this invention is to be used as retention, drainage aids in papermaking or oil-water emulsion breaker, or solid liquid separator in various types of wastewater treatment

2) Preferably,the nonionic monomer is Acrylamide or Methacrylamide, 0-97 mol%.

3) Further, preferably the cationic monomer is blend of DMAEA.BCQ quatemized salt, DMAEA.MCQ quatemized salt, and DMAEA.DMSQ quatemized salt mixture, 3 -100 mol%.

4) Preferably, the anionic monomer is acrylic acid or itaconic acid, 0-30 mol%. 5) Preferabl, anionic salt is selected from mixture of ammonium sulfate, ammonium chloride, sodium sulfate, sodium chloride, ammonium phosphate, sodium phosphate, sodium citrate.

6) Also, preferably the dispersant is selected from mixture of poly-DMAEA.MCQ quatemized salt, poly-DMAEA.DMSQ quatemized salt, PEI(Polyethyleneimine), SMA(Styrene Maleic Anhydride).

7) The amount of PEI is then preferably 0.1-5% by weight, based on the total weight of monomers used.

8) The amount of SMA(Styrene Maleic Anhydride) is preferably 0.5-10 % by weight, based on the total weight of monomers used. 9) The amount of non ionic surfactant is preferably 0.1 -0.5 % by weight, based on the total weight of monomers used.

10) Preferably, the salt concentration of the aqueous solution is 21 -25% by weight of polyvalent anionic salt.

11 ) Dispersant is preferably added to a reactor on a small portion before or during the process in a several sequences.

12) The process preferably requires specific and accurate temperature control respectively in these 3 phases: 1 initiation phase(high shear),2)Process phase(low shear), 3)Stabilization phase(high shear).

13) The process also preferably requires a specific and accurate control on both shear and mixing speed in these 3 phases respectively: 1 initiation Phase(high shear),2)Process phase(low shear), 3)Stabilization phase(high shear).

Claims

Claims:

1. A processes of making water soluble, hydrophilic dispersion polymer containing a colloidal silica or an inorganic flocculant for the use as retention, drainage aids in papermaking or oil-water emulsion breaker, or solid liquid separator in various types of wastewater treatment, said process comprises the use of a cationic or anionic monomer plus a non ionic acrylated monomer and PEI(Polyethyleneimine),SMA(Stayrene Maleic Anhydride), and a non ionic surfactant mixture as dispersants in the anionic salt solution under the existence of free radical initiator.

2. The process of claiml , wherein the nonionic monomer is Acrylamide or Methacrylamide, in the amount of 0-97 mol%.

3. The process of claiml , wherein the cationic monomer is a blend of DMAEA.BCQ quatemized salt, DMAEA.MCQ quatemized salt, and DMAEA.DMSQ quatemized salt mixture, in the amount of 3 -100 mol%.

4. The process of claiml , wherein the Anionic monomer is acrylic acid or itaconic acid, in the amount of 0-30 mol%.

5. The process of claiml , wherein the anionic salt is selected from the group consisting of ammonium sulfate, ammonium chloride, sodium sulfate, sodium chloride, ammonium phosphate, sodium phosphate, sodium citrate, and mixtures thereof.

6. The process of claiml , wherein the dispersant is selected from the group of poly-DMAEA.MCQ quatemized salt, poly-DMAEA.DMSQ quatemized salt, PEI(Polyethyleneimine), SMA(Styrene Maleic Anhydride), and mixtures thereof.

7. The process of claim 6, wherein the amount of PEI is 0.1-5% by weight, based on the total weight of monomers used.

8. The process of claim 6, wherein the amount of SMA(Styrene Maleic Anhydride) is 0.5-10 % by weight, based on the total weight of monomers used.

9. The process of claim 1 , wherein the amount of non ionic surfactant is 0.1-0.5 % by weight, based on the total weight of monomers used

10. The process of claim 1 , wherein the salt concentration of the aqueous solution is 21-25% by weight of polyvalent anionic salt.

11. The process of claim 1 , wherein the dispersant is added to a reactor on a small portion before or during the process in several sequences.

12. The process of claim 1 , wherein the temperature is specificly and accurately controlled respectively in the following three phases: i) Initiation phase(high shear), ii)Process phase(low shear), iii)Stabilization phase(high shear).

13. The process of claim 1 , wherein both shear and mixing speed are specificly and accurately controlled in the following three phases, respectively: i)lnitiation Phase(high shear), ii)Process phase(low shear), iii)Stabilization phase(high shear).