AU2006248161B2

AU2006248161B2 - Process for preparing a polymer dispersion and a polymer dispersion

Info

Publication number: AU2006248161B2
Application number: AU2006248161A
Authority: AU
Inventors: Mathias Hahn; Andre Laschewsky; Bernd Paulke; Christian Przybyla; Oliver Struck
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV; Akzo Nobel NV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV; Akzo Nobel NV
Priority date: 2005-05-20
Filing date: 2006-05-09
Publication date: 2010-02-18
Anticipated expiration: 2026-05-09
Also published as: CA2608408A1; KR100923849B1; NO20076511L; RU2394841C2; ZA200709250B; MX2007013907A; KR20080012301A; WO2006123993A2; BRPI0610071A2; WO2006123993A3; JP4799611B2; MX276303B; CN100558751C; AU2006248161C1; AU2006248161A1; JP2008540796A; EP1881997A2; RU2007147474A; CA2608408C; CN101180321A

Description

WO 2006/123993 PCT/SE2006/050112 1 PROCESS FOR PREPARING A POLYMER DISPERSION AND A POLYMER DISPERSION 5 The present invention relates to a process for preparing a polymer dispersion. It also relates to a polymer dispersion, the use of the polymer dispersion and a process for producing paper. Background of the invention An important use of aqueous dispersions of anionic charged polymers is 10 retention and dewatering aid in paper manufacturing industry. Further uses of such polymer dispersions are as aids in various processes where they act as, for example, flocculants when treating wastewater or aids in other solid-liquid separation processes in, for example, the metal-, ceramic-, printing-, biotechnological-, and pharmaceutical industries. They can also be used as thickeners in, e.g., chemical- biotechnological-, 15 pharmaceutical-, and cosmetic industries and soil improving agents. Generally, these polymer dispersions comprise a dispersed polymer and a dispersant in which the dispersant usually is a polymeric dispersant. Anionic polymer dispersions are generally prepared by polymerising a reaction mixture of water-soluble anionic and non-ionic monomers in the presence of a salt. 20 Finished polymer will precipitate from the aqueous salt solution and, by using a suitable dispersant, form a stable polymer dispersion. WO 01/18063, US 5,837,776 and US 5,605,970 disclose processes for preparing a dispersion of a water-soluble polymer comprising polymerising water-soluble monomers in an aqueous reaction mixture containing a salt. 25 Factors to consider are, for example, the process viscosity, active content, stability, good retention properties, and easiness of preparing the polymer dispersion sometimes including preparing the stabiliser. Also, criteria such as environmental and safety aspects are of importance. There are a number of criteria that the polymer dispersion should fulfil to give good 30 results in the final application and be of commercial interest. Such criteria are for example low-cost production, rapid performance, effective flocculation or dewatering, and long shelf life. Prior art anionic polymer dispersions described contain significant amounts of salt which makes up a great part of the weight of the polymer dispersion. There is 35 presently a desire to reduce, or completely avoid, the use of salt in polymer dispersions due to environmental and economical reasons.

WO 2006/123993 PCT/SE2006/050112 2 The viscosity of the reaction mixture when producing the polymer dispersion, "the process viscosity", should be kept low and viscosity peaks should be avoided, or at least reduced as much as possible, during the production of the polymer dispersion. The shelf life of the dispersion, i.e., the stability of the polymer dispersion over 5 time, is an important property. An efficient dispersant is needed for keeping the polymer particles stable in dispersion without settling as sediment. A further factor to consider is the active content, i.e., the amount of dispersed polymer in the polymer dispersion. A high active content minimises transportation costs and gives easier handling at the end-application. By using an efficient dispersant, 10 dispersions with a high active content can be obtained at the same time the viscosity can be kept low. However, an increase of the active content above a certain level may not always give improved performance in retention and dewatering in a papermaking process. During preparation of a polymer dispersion, deposits of polymer may form and 15 stick to the reaction vessel and stirrer. This leads to time consuming cleaning procedures of the reaction equipment. It is an object of the present invention to provide a, preferably salt-free, water soluble anionic polymer dispersion having high stability and high active content. The polymer dispersion should also give good retention and dewatering results when used in 20 papermaking processes, act as a good flocculant in other processes such as waste water treatment, act as a good thickener in various applications such as cosmetic formulations and also be possible to use in soil improvement processes. It is further an object of the present invention to provide a process for preparing a, preferably salt-free, water soluble anionic polymer dispersion in which the process viscosity is kept low and smooth during 25 preparation without any large viscosity peaks, and which gives no deposits. Finally, it is an object of the present invention to provide a process for producing paper in which the polymer dispersion is used. The invention 30 By "stabiliser" is herein meant a polymer which function is to keep dispersed polymer particles/droplets in dispersion. By "co-stabiliser" is herein meant a polymer which function is to make a polymer formed from polymerisation of one or more monomers to precipitate out from solution into solid particles or liquid droplets. 35 According to the invention it has surprisingly been found that a highly stable polymer dispersion having high active content of a dispersed polymer and low process viscosity can be achieved by a process for preparing a polymer dispersion comprising WO 2006/123993 PCT/SE2006/050112 3 polymerising one or more anionic monomers (m 1 ) and one or more non-ionic vinyl monomers (M 2 ) present in a reaction mixture further comprising a polymeric stabiliser (B) and a polymeric co-stabilisers (C). The invention further comprises a polymer dispersion comprising a dispersed 5 polymer (A) of one or more anionic monomers (m 1 ) and one or more non-ionic vinyl monomers (m 2 ), a polymeric stabiliser (B), and a polymeric co-stabiliser (C). The reaction medium is suitably an aqueous medium. The polymer dispersion is suitably an aqueous polymer dispersion. The polymer dispersion is suitably water soluble. The polymer particles/droplets suitably has an average size (thickness) of up to 10 about 25 pm, also suitably from about 0.01 to about 25 pm, preferably from about 0.05 to about 15 pm, most preferably from about 0.2 to about 10 pm. The polymeric stabiliser (B) is suitably an organic polymer. Preferably the polymeric stabiliser (B) is a polymer of one or more monomers belonging to the group of acrylic acid, methacrylic acid, itaconic acid, 2-acrylamido-2-methyl-1-propane sulphonic 15 acid (AMPS), 2-acrylamido-2-methyl-1-butane sulphonic acid (AMBS), acryloyloxyethyl sulphonic acid, methacryloyloxyethyl sulphonic acid, acryloyloxypropyl sulphonic acid, methacryloyloxypropyl sulphonic acid, vinyl sulphonic acid, allyl sulphonic acid, methallyl sulphonic acid, styrene sulphonic acid, maleic acid, maleamidic acid, and/or vinyl phosphonic acid. Other suitable polymeric stabilizers are copolymers of maleic acid or 20 maleamidic acid, respectively, with styrene or vinyl ethers, or alpha-olefins which may contain additional comonomers. Preferably, the polymeric stabiliser (B) is a copolymer of acrylic acid or methacrylic acid with a further of the listed monomers, preferably 2 acrylamido-2-methyl-1 -propane sulphonic acid (AMPS). The weight average molecular weight of the polymeric stabiliser (B) is suitably 25 from about 5.000 to about 5.000.000 g/mole, preferably from about 10.000 to about 1.000.000 g/mole, more preferably from about 20.000 to about 1000.000 g/mole, most preferably from about 35.000 to about 500.000 g/mole. The polymer dispersion suitably comprises from about 0.2 to about 5 weight % of the polymeric stabiliser (B) based on the total weight of the dispersion or reaction mixture, 30 preferably from about 0.5 to about 3 weight %, most preferably from about 0.8 to about 1.5 weight %. The polymeric co-stabiliser (C) is suitably an organic polymer. Preferably, the polymeric co-stabiliser (C) is a polymer of one or more monomers belonging to the group of acrylic acid, methacrylic acid, vinyl sulphonate, styrene sulphonic acid, itaconic acid, 35 vinylphosphonic acid, 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS), 2 acrylamido-2-methyl-1-butane sulphonic acid (AMBS), acryloyloxyethyl sulphonic acid, WO 2006/123993 PCT/SE2006/050112 4 methacryloyloxyethyl sulphonic acid, acryloyloxypropyl sulphonic acid, and methacryloyloxypropyl sulphonic acid. Preferably, two or more co-stabilisers (C) are present in the reaction mixture and polymer dispersion. 5 The weight average molecular weight of the polymeric co-stabiliser (C) is suitably from about 100 to about 50.000 g/mol, preferably from about 500 to about 30.000 g/mol, more preferably from about 1.000 to about 20.000 g/mol, even more preferably from about 1.000 to about 15.000 g/mol, most preferably from about 1.000 to about 10.000 g/mol. 10 The polymer dispersion suitably comprises from about 2 to about 50 weight % of one or more polymeric co-stabilisers (C) based on the total weight of the dispersion or reaction mixture, preferably from about 3 to about 25 weight %, most preferably from about 5 to about 15 weight %. The polymeric stabiliser (B) and the polymeric co-stabiliser (C) in the reaction 15 mixture or polymer dispersion are preferably made up from different monomers or, if they are made up from the same monomers, contain different monomer ratios. The polymeric stabiliser (B) or polymeric co-stabiliser (C) is suitably not a dextrin or dextrin derivative. The one or more anionic monomers (m 1 ) suitably belong to the group of acrylic 20 acid, methacrylic acid, (styrene sulphonic acid), 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS), 2-acrylamido-2-methyl-1-butane sulphonic acid (AMBS), acryloyloxyethyl sulphonic acid, methacryloyloxyethyl sulphonic acid, acryloyloxypropyl sulphonic acid, methacryloyloxypropyl sulphonic acid, vinyl sulphonic acid, and their alkali, earth alkali or ammonium salts. 25 The one or more non-ionic monomers (M 2 ) suitably belong to the group of acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N ethylacrylamide, N-ethylmethacrylamide, N-isopropylacrylamide, N isopropylmethacrylamide, N,N-dimethylacrylamide, N-t-butylacrylamide, N-t butylmethacrylamide, N-hydroxyethylacrylamide, N-(tris-(hydroxymethyl)-methyl) 30 acrylamide, N-vinyl formamide, N-vinyl acetamide, hydroxyalkylacrylate or hydroxyalkylmethacrylate with C2-C4 alkyl, alkylacrylate or alkylmethacrylate with Cl-C4 alkyl, benzylacrylate or benzylmethacrylate, esters of acrylic or methacrylic acid with dihydroxy-(polyethylene oxide) having 1-20 ethylene oxide units, or esters of acrylic or methacrylic acid with monomethoxyhydroxy-(polyethylene oxide) having 1-20 ethylene 35 oxide units. Preferably, the one or more non-ionic monomers (M 2 ) belong to the group of acrylamide, acrylate or methacrylate esters.

WO 2006/123993 PCT/SE2006/050112 5 The molar ratio between the anionic monomer (m 1 ) and the non-ionic monomer

(M

2 ) is suitably from about 1:99 to about 25:75, preferably from about 3:97 to about 20:80, most preferably from about 5:95 to about 15:85. The weight average molecular weight of the dispersed polymer (A) is suitably 5 from about 1.000.000 to about 15.000.000 g/mole, preferably from about 1.500.000 to about 10.000.000 g/mole, most preferably from about 2.000.000 to about 8.000.000 g/mole. The polymerisation is suitably a free-radical polymerisation. The initiator is suitably a radical former, preferably a water-soluble azo-initiator, a water-soluble 10 peroxide, or a water-soluble redox initiator. Preferred initiators include 2,2'-azobis (amidinpropane) hydrochloride, 2,2'-azobis-(2-methyl-N-(2-hydroxyethyl)-propionamide, 4,4'-azobis-(4-cyanovaleric acid) and its alkali and ammonium salts, t-butylhydroperoxide, perhydrol, peroxydisulphate, or the before mentioned peroxides in combination with a reducing agent such as sodium metabisulphite or ferrous salts. 15 The polymer dispersion suitably comprises from about 5 to about 40 weight % of the dispersed polymer (A) based on the total weight of the dispersion, preferably from about 10 to about 30 weight %, most preferably from about 12 to about 25 weight %. The amount of one or more inorganic salts in the polymer dispersion is suitably from 0 to about 1.9 weight % based on the total weight of the dispersion or reaction 20 mixture, preferably from 0 to about 1 weight %, more preferably from 0 to about 0.5 weight %, most preferably from 0 to about 0.1 weight %, or substantially salt-free. By "inorganic salts" is herein suitably meant any inorganic salt, preferably salts belonging to the group of inorganic alkali metal, alkali earth metal or ammonium halides, sulphates and phosphates. 25 The polymer dispersion may also comprise additional substances, such as cross-linkers and branching agents. The polymerisation temperature when may vary depending on, e.g., which monomers and polymerisation initiator are being used. Suitably, the polymerisation temperature is from about 30 to about 90*C, preferably from about 35 to about 70*C. The 30 process is suitably a semi-batch process, i.e., the monomers m 1 and m 2 are both present at the beginning of the polymerisation process and further added at a later stage, either in one or more portions or continuously over a period of time during the reaction. The reaction mixture is suitably stirred during the polymerisation process at a stirring rate suitable for the process. Suitably, the stirring rate is from about 100 to about 1000 rpm. 35 The invention further comprises use of a polymer dispersion as retention and dewatering aid for paper manufacturing, as thickening agent, as soil improvement agent and/or as an additive for increasing the dry strength of paper. The polymer dispersion of WO 2006/123993 PCT/SE2006/050112 6 the present invention can more specifically be used as aid in various processes as, for example, flocculants when treating wastewater or aids in other solid-liquid separation processes in, for example, the metal-, ceramic-, printing-, biotechnological-, and pharmaceutical industries. The polymer dispersion can also be used as thickener in, e.g., 5 chemical- biotechnological-, pharmaceutical-, and cosmetic industries. Finally, the present invention comprises a process for the production of paper from an aqueous suspension containing cellulosic fibres, and optional fillers, which comprises adding to the suspension an aqueous polymer dispersion according to the invention, forming and draining the suspension on a wire. 10 When using the polymer dispersion, according to the invention, in papermaking processes, the dispersion is added to the suspension of cellulosic fibres, and optional fillers, to be dewatered in amounts which can vary within wide limits depending on, inter alia, type and number of components, type of furnish, filler content, type of filler, point of addition, etc. The dispersed polymer is usually added in an amount of at least 0.001%, often at least 15 0.005% by weight, based on dry substance in the stock to be dewatered, and the upper limit is usually 3% and suitably 1.5% by weight. The polymer dispersion according to the invention is suitably diluted before adding it to the cellulosic suspension. Further additives which are conventional in papermaking can of course be used in combination with the polymer dispersion according to the invention, such as, for example, silica-based sols, dry 20 strength agents, wet strength agents, optical brightening agents, dyes, sizing agents like rosin-based sizing agents and cellulose-reactive sizing agents, e.g. alkyl and alkenyl ketene dimers, alkyl and alkenyl ketene multimers, and succinic anhydrides, etc. The cellulosic suspension, or stock, can also contain mineral fillers of conventional types such as, for example, kaolin, china clay, titanium dioxide, gypsum, talc and natural and synthetic calcium 25 carbonates such as chalk, ground marble and precipitated calcium carbonate. The term "paper", as used herein, include not only paper and the production thereof, but also other cellulosic fibre-containing sheet or web-like products, such as for example board and paperboard, and the production thereof. The process can be used in the production of paper from different types of suspensions of cellulose-containing fibres and the suspensions 30 should suitably contain at least 25 % by weight and preferably at least 50 % by weight of such fibres, based on dry substance. The suspension can be based on fibres from chemical pulp such as sulphate, sulphite and organosolv pulps, mechanical pulp such as thermome chanical pulp, chemo-thermomechanical pulp, refiner pulp and groundwood pulp, from both hardwood and softwood, and can also be based on recycled fibres, optionally from de-inked 35 pulps, and mixtures thereof.

WO 2006/123993 PCT/SE2006/050112 7 The invention will now further be described in connection with the following examples which, however, not should be interpreted as limiting the scope of the invention. 5 Examples Example 1: A stabiliser made of methacrylic acid (MAA) and 2-acrylamido-2-methyl-1 propane sulphonic acid (AMPS) in a mole ratio of 80:20 was prepared: A mixture of 85g ultra-pure water, 8.24g AMPS (solid), 16.62g MAA and 11.5g NaOH (50%) was adjusted 10 to pH 7 by means of NaOH (50%). 0.02g EDTA (solid) was given into the mixture. Further ultra-pure water was added to reach a total mass of 127g. This was filled into a double wall 150ml glass reactor with anchor stirrer, nitrogen inlet, reflux condenser and bottom valve. The mixture was stirred with 150/min and purged with nitrogen. The reactor content was heated up to 45*C. 0.05g V-50 (2,2'-Azobis-(2-amidinopropane) dihydrochloride) 15 were added. After 60min, temperature was increased up to 50*C. The mixture was polymerised over 72 h at 50*C and 150/min. The stabiliser was purified and isolated by ultrafiltration and freeze-drying. The weight average molecular weight was about 15.000 g/mole. 20 Examples 2-7: A polymer dispersion was prepared by polymerising a monomer mixture comprising acrylamide and acrylic acid in the presence of a polymeric stabiliser and a polymeric co-stabiliser. A mixture of 30 g water, 24.3 g co-stabiliser polyacrylic acid (45%, Sigma 25 Aldrich, Mw 1.200), 1.2 g stabiliser poly (MAA-co-AMPS) (80:20) copolymer (according to example 1, Mw 15.000), 28.1 g acrylamide (50 wt%), 1.07 g acrylic acid, 0.04 g sodium formiate, 0.03 g EDTA, and 1.17 g NaOH (50 wt%) was stirred and the pH was adjusted to 7. Water was added up to 100 g and during 8 hours azo-initiator VA-044 (4%) (2,2' azobis-(N,N'-dimethyleneisobutyramidine) dihydrochloride, Wako) was added (0.5 g in 30 steps). The temperature was kept at 35*C. After 16 hours, the stirring was stopped. Five further polymer dispersions were prepared using the same procedure as described above but changing the ratio non-ionic monomer and anionic monomer, using a second non-ionic monomer in the dispersed polymer, and also using as co-stabiliser in some cases a combination of polyacrylic acid and polymethacrylic acid. As stabiliser 1.2 35 weight % poly-(MMA-co-AMPS) in a mole ratio of 80:20 was used. The active contents (polymer content) in the stabiliser was around 15 weight%. 11 weight % of co-stabiliser was used.

WO 2006/123993 PCT/SE2006/050112 8 In Table 1, the following abbreviations are used: AAm = acrylamide AA = acrylic acid MMA = methylmethacrylate 5 t-BuA = t-butyl acrylate n-BuA = n-butyl acrylate PAA = polyacrylic acid PMAA = polymethacrylic acid 10 Table 1. Dispersion anionic monomer non-ionic co-stabiliser stabiliser monomer Example 2 AA (10 mol-%) AAm PAA (Mw 1.200) poly-(MMA-co-AMPS) (90 mol-%) (Mw 15.000) Example 3 AA (15 mole-%) AAm PAA (Mw 1.200) poly-(MMA-co-AMPS) (85 mole-%) (Mw 20.000) Example 4 AA (15 mole-%) AAm PAA (Mw 1.200) poly- (MMA-co-AMPS) (85 mole-%) PMAA (Mw 9.500) (Mw 20.000) (1:1 ratio) Example 5 MMA (10 mole-%) AAm PAA poly-(MMA-co-AMPS) AA (10 mole-%) (80 mole-%) (Mw 1.200) (Mw 20.000) Example 6 MMA (10 mole-%) AAm PAA poly-(MMA-co-AMPS) t-BuA (10 mole-%) (80 mole-%) (Mw 1.200) (Mw 20.000) Example 7 MMA (10 mole-%) AAm PAA (Mw 1.200) poly-(MMA-co-AMPS) n-BuA (10 mole-%) (80 mole-%) PMAA (Mw 9.500) (Mw 20.000) (1:1 ratio) The process viscosity was low (lower than -2000 mPas) for all dispersions. Example 8: 15 The polymer dispersions prepared in Examples 2-4 were tested for retention and dewatering performance in papermaking processes by means of a Dynamic Drainage Analyser (DDA) available from Akribi, Sweden. The furnish used was based on 60 % by weight of bleached 80/20 birch-pine pulp and 40 % by weight of calcium carbonate. The WO 2006/123993 PCT/SE2006/050112 9 stock volume was 800 ml, the pulp concentration 5 g/L and the conductivity 1.5 mS/cm. The stock was stirred at a speed of 1500 rpm while the following was added to the stock: an anionic trash catcher (0.5 kg/t), polymer dispersion (1.0 kg/t) and finally anionic inorganic particles (0.5 kg/t). The temperature was 22.5*C. A vacuum of 0.35 bar was 5 used for the analysis. The retention time (s) and turbidity (NTU) was measured. Table 2. Polymer dispersions and application tests Polymer Application tests dispersion Polymer load Retention time Turbidity (kg/t) (s) (NTU) Example 2 1.0 15.2 198 Example 3 1.0 14.6 220 Example 4 1.0 13.2 214 It is concluded that the dispersions according to the invention function well in 10 retention and dewatering aids. Example 9: The shelf life, measured as sedimentation stability, was tested for the dispersions according to Examples 2-7. A 10 g sample of each dispersion was 15 centrifuged for 30 minutes at 3000 rpm. The amount of polymer sediment was determined for each sample. No sample gave any polymer sediment Thus, it is concluded that polymer dispersions with long shelf life can be obtained by the present invention, also at high active contents.

Claims

1. Process for preparing a water-soluble polymer dispersion comprising polymerising one or more water soluble anionic monomers (mi) and one or more non ionic vinyl monomers (m 2 ) present in a reaction mixture further comprising 5 - a polymeric stabiliser (B) being a polymer of one or more monomers belonging to the group of acrylic acid, methacrylic acid, itaconic acid, 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS), 2-acrylamido-2-methyl-1-butane sulphonic acid (AMBS), acryloyloxyethyl sulphonic acid, methacryloyloxyethyl sulphonic acid, acryloyloxypropyl sulphonic acid, methacryloyloxypropyl sulphonic acid, vinyl sulphonic acid, allyl sulphonic 10 acid, methallyl sulphonic acid, styrene sulphonic acid, maleic acid, maleamidic acid, and/or vinyl phosphonic acid, or a copolymer of maleic acid or maleamidic acid, respectively, with styrene, vinyl ethers or alpha-olefins, and - a polymeric co-stabiliser (C) being a polymer of one or more monomers belonging to the group of acrylic acid, methacrylic acid, vinyl sulphonate, styrene sulphonic acid, itaconic 15 acid, vinylphosphonic acid, 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS), 2 acrylamido-2-methyl-1-butane sulphonic acid (AMBS), acryloyloxyethyl sulphonic acid, methacryloyloxyethyl sulphonic acid, acryloyloxypropyl sulphonic acid, and methacryloyloxypropyl sulphonic acid, the weight average molecular weight of the polymeric stabiliser (B) is from about 20.000 20 to about 1.000.000 g/mole and the weight average molecular weight of the polymeric co stabiliser (C) is from about 1.000 to about 15.000 g/mole.

2. Water-soluble polymer dispersion comprising - a dispersed polymer (A) of one or more water soluble anionic monomers (m 1 ) and one or more non-ionic vinyl monomers (m 2 ), 25 - a polymeric stabiliser (B) being a polymer of one or more monomers belonging to the group of acrylic acid, methacrylic acid, itaconic acid, 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS), 2-acrylamido-2-methyl-1 -butane sulphonic acid (AMBS), acryloyloxyethyl sulphonic acid, methacryloyloxyethyl sulphonic acid, acryloyloxypropyl sulphonic acid, methacryloyloxypropyl sulphonic acid, vinyl sulphonic acid, allyl sulphonic 30 acid, methallyl sulphonic acid, styrene sulphonic acid, maleic acid, maleamidic acid, and/or vinyl phosphonic acid, or a copolymer of maleic acid or maleamidic acid, respectively, with styrene, vinyl ethers or alpha-olefins, and - a polymeric co-stabiliser (C) being a polymer of one or more monomers belonging to the group of acrylic acid, methacrylic acid, vinyl sulphonate, styrene sulphonic acid, itaconic 35 acid, vinylphosphonic acid, 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS), 2 acrylamido-2-methyl-1-butane sulphonic acid (AMBS), acryloyloxyethyl sulphonic acid, C3181PcTk

2007-s-24 AMED S&LHEET %#I- "LUUUO IV - 16 1124-08-207 methacryloyloxyethyl sulphonic acid, acryloyloxypropyl sulphonic acid, and methacryloyloxypropyl sulphonic acid, the weight average molecular weight of the polymeric stabiliser (B) is from about 20.000 to about 1.000.000 g/mole and the weight average molecular weight of the polymeric co 5 stabiliser (C) is from about 1.000 to about 15.000 g/mole.

3. Process according to claim 1, or polymer dispersion according to claim 2, wherein the reaction mixture is an aqueous medium and the polymer dispersion is an aqueous polymer dispersion.

4. Process according to any one of claims 1 or 3, or polymer dispersion 10 according to any one of claims 2-3, wherein the polymer particles/droplets have an average size of up to about 25 pm.

5. Process according to any one of claims I or 3-4, or polymer dispersion according to any one of claims 2-4, wherein two or more co-stabilisers (C) are present in the reaction mixture and the polymer dispersion. 15

6. Process according to any one of claims I or 3-5, or polymer dispersion according to any one of claims 2-5, wherein the polymeric stabiliser (B) and the polymeric co-stabiliser (C) are made up from different monomers.

7. Process according to any one of claims I or 3-6, or polymer dispersion according to any one of claims 2-6, wherein the anionic monomer (m 1 ) suitably belongs to 20 the group of acrylic acid, methacrylic acid, (styrene sulphonic acid), 2-acrylamido-2 methyl-1 -propane sulphonic acid (AMPS), 2-acrylamido-2-methyl-l-butane sulphonic acid (AMBS), acryloyloxyethyl sulphonic acid, methacryloyloxyethyl sulphonic acid, acryloyloxypropyl sulphonic acid, methacryloyloxypropyl sulphonic acid, vinyl sulphonic acid, and their alkali, earth alkali or ammonium salts. 25

8. Process according to any one of claims 1 or 3-7, or polymer dispersion according to any one of claims 2-7, wherein the one or more non-ionic monomers (m 2 ) belong to the group of acrylamide, methacrylamide, N-methylacrylamide, N methylmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N isopropylacrylamide, N-isopropylmethacrylamide, N,N-dimethylacrylamide, N-t 30 butylacrylamide, N-t-butylmethacrylamide, N-hydroxyethylacrylamide, N-(tris (hydroxymethyl)-methyl)-acrylamide, N-vinyl formamide, N-vinyl acetamide, hydroxyalkylacrylate or hydroxyalkylmethacrylate with C2-C4 alkyl, alkylacrylate or alkylmethacrylate with C1-C4 alkyl, benzylacrylate or benzylmethacrylate, esters of acrylic or methacrylic acid with dihydroxy-(polyethylene oxide) having 1-20 ethylene oxide 35 units, or esters of acrylic or methacrylic acid with monomethoxyhydroxy-(polyethylene oxide) having 1-20 ethylene oxide units. C3181PCTk 2007-08-24 AMENDED SHEET 14 UU~ LUW 12

9. Process according to any one of claims I or 3-8, or polymer dispersion according to any one of claims 2-8, wherein the one or more monomers (M 2 ) belong to the group of acrylamide, acrylate or methacrylate esters.

10. Process according to any one of claims I or 3-9, or polymer dispersion 5 according to any one of claims 2-9, wherein the amount of inorganic salt is from 0 to about 1.9 weight % based on the total weight of the dispersion or reaction mixture.

11. Process according to any one of claims I or 3-10, or polymer dispersion according to any one of claims 2-10, wherein the amount of one or more inorganic salts is from 0 to about 0.5 weight % based on the total weight of the dispersion or reaction 10 mixture.

12. Process according to any one of claims I or 3-11, wherein the reaction mixture comprises from about 3 to about 20 mol % of the one or more water soluble anionic monomers (m 1 ).

13. Process according to any one of claims I or 3-12, wherein the reaction 15 mixture comprises from about 80 to about 97 mol % of the one or more non-ionic vinyl monomers (m 2 ).

14. Process according to any one of claims 1 or 3-13, wherein the reaction mixture comprises from about 0.5 to about 3 weight % of the polymeric stabiliser (B).

15. Process according to any one of claims I or 3-14, wherein the reaction 20 mixture comprises from about 3 to about 25 weight % of the polymeric co-stabiliser (C).

16. Polymer dispersion according to any one of claims 2-11, comprising from about 10 to about 30 weight % of the dispersed polymer (A).

17. Polymer dispersion according to any one of claims 2-11 or 16, comprising from about 0.5 to about 3 weight % of the polymeric stabiliser (B). 25

18. Polymer dispersion according to any one of claims 2-11 or 16-17, comprising from about 3 to about 25 weight % of the polymeric co-stabiliser (C).

19. Use of a polymer dispersion according to any of claims 2-11 or 16-18 as retention and dewatering aid for paper manufacturing, as additive for increasing the dry strength of paper, as thickening agent, and/or as soil improvement agent. 30

20. Process for the production of paper from an aqueous suspension containing cellulosic fibres, and optional fillers, which comprises adding to the suspension a polymer dispersion according to any of claims 2-11 or 16-18, forming and draining the suspension on a wire. C3181PCTk 2007-08-24 AMENDED SHEET 13

21. Process for preparing a water-soluble polymer dispersion according to claim 1, or a water-soluble polymer dispersion according to claim 2, and substantially as herein described with reference to any one of Examples 2 to 7. Dated 21 December, 2009 5 Akzo Nobel N.V. Fraunhofer-Gesellschaft zur Forderung der angewandten Forschung e.V. Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON