SE444175B - PROCEDURE FOR THE PREPARATION OF WATER-IN-OIL EMULSIONS OF WATER-SOLUBLE ANIONIC COPOLYMES OF SODIUM ACRYLATE AND ACYLAMIDE - Google Patents

Description

8101426-8 10 15 20 25 30 35 2 According to the invention, it has been found that very high molecular water-soluble anionic copolymers of sodium acrylate and acrylamide can be prepared by emulsion polymerization f? by addition to the emulsion before the polymerization of from about 2% by weight of salt, which consists of sodium chloride or lithium bromide, based on the total weight of the emulsion, to the salt saturation point in the aqueous phase of the emulsion during polymerization the temperature. A preferred embodiment of the method according to the invention consists in that (a) preparing an aqueous phase containing sodium acrylate and acrylamide and a water-soluble salt, which consists of sodium chloride or lithium bromide, dissolved in water, (b) preparing an oil phase comprising an inert hydrophobic liquid and a water-in-oil emulsifier dissolved therein, (c) dissolving a chemical free radical initiator in the aqueous phase or the oil phase, depending on the solubility of the initiator creates, (d) dispersing the aqueous phase in the oil phase to form an emulsion, and (e) polymerizing the water-soluble monomers.

It is worth noting that there are many variations of the above procedure, which can be used. For example the chemical free radical initiator can then be added the aqueous phase and the oil phase have been emulsified. Likewise, one can emulsion of the monomer is formed and passed in portions or continuously to a "publisher" of the emulsion in the reactor.

No matter what special procedure is used, it is essential that the aqueous phase is properly dispersed in phase. The molecular weight of the product polymer increases significantly with decreasing size of the aqueous phase droplets which are dispersed in the oil phase. According to the invention, they are dispersed the size of the aqueous phase droplets is about 5 μm or less, preferably otherwise about 1 μm or less. Droplet size of 5 μm or less can be achieved by any suitable method, including stirring. mixing of the aqueous phase and oil phase in a rapid 1% 10 15 20 25 30 35 810142M6-8 3 running mixer or homogenizer or conducting mixer through a colloid grinder with a small gap setting.

The above-mentioned monomers produce polymers which are anionic. In this.description means' anionic polymer 'means a polymer consisting of 1 - 99% by weight of polymer sodium acrylate and 99 - 1% by weight of polymerized acrylic amide, by weight of polymerized monomers.

Preferably the sodium acrylate comprises from about 10 8 to about 50% of the total monomer weight.

The monomers and water described above constitute the water phase of the water-in-oil emulsion. The monomers can be used in amounts of from about 10 8 to about 30%, preferably from about 20% to about 30 S, calculated on the weight of the emulsion.

The aqueous phase also contains a dissolved aqueous soluble salt. It has been found that the addition of salt to the emulsion before the polymerization leads to several beneficial effects. Polymerization the speed increases, so that the time required for essentially complete conversion of monomer to polymer, abbreviated. In addition to this effect on poly- the merisation speed will have the advantage that conversions of monomer to polymer over approx 90%, in particular over about 95 8, is obtained under reversal of a small amount of chemical initiator when salt is present in the emulsion than when salt is not present. In addition, significant edge increases of the produced water-soluble the molecular weight of the polymers when salt is present in the emulsions before the polymerization. In this writing is used reduced specific viscosity (RSV) as a measure of the molecular weight of the water-soluble the polymers in the emulsions. Thus lies typical RSV for water-soluble copolymers of sodium acrylate and acrylamide prepared by emulsion polymerization in the presence of salt at oh, 'w fl se fiflfi vu fl-' wraw "w- fl: 8101426-s fl fåå ”å; 10 15 20 25 30 35 4 about 50 ° C in the range 27-31, while water-soluble copolymers more of sodium acrylate and acrylamide prepared with same process, but in the absence of salt, RSV of only Ä ca 22 - 24. ä ' Another benefit of the presence of salt is a dramatic effect on the appearance of the emulsions produced.

Emulsions without salt are milky, while those containing holding salt are translucent, with some approaching transparency.

The amount of salt used depends on the particular the salt, its solubility properties and polymerization properties the conditions. Generally, the amount of salt used is from about 2%, calculated on the total weight of the whole emulsion, to the saturation point of the salt in the aqueous phase at merisation temperature, and preferably from about half saturation to saturation.

Salts useful in the process of the invention is sodium chloride and lithium bromide. The pre-; the extracted salt is sodium chloride. 1 The oil phase of the emulsion comprises an inert hydrogen fob liquid and a water-in-type emulsifier oil. Any inert hydrophobic liquid can be used, including, for example, aliphatic and aromatic carbon hydrogen and halogenated hydrocarbons such as toluene, xylene, dichlorobenzene, perchlorethylene, hexane, heptane, kerosene, mineral oil and 'Isopar M' a highly pure isoparaffin technical material from Exxon Corp. The preferred inert the hydrophobic liquid is 'Isopar M'. Likewise, each can conventional water-in-oil emulsifier is used, such as sodium hexadecyl phthalate, sorbitan monooleate, sorbitan monostearate, mono- and diglycerides, poly- ethoxylated sorbitol hexaoleate, sodium cetyl or -stearyl phthalate, metal soaps or combinations hence. In general, the emulsions used in the oil phase have the drug a low hydrophilic-lyophilic balance, e.g. fwv - i - -t.r. ,,, .., .. 1 ,:, ._ ,. _,, _ _ .W V d), Fräs: W. 1.5 ' Äš å. .f 'L t 5.

J 8101 426-8 l “EF W« "'**.'. ff ~ = 1: azv.mæzf S * '"ß-wr: - about 3 to about 5. preferred emulsifiers are sorbitan monooleate and a mixture of polyethoxylated sorbitol hexaoleate and mono- and diglycerides. These emulsifiers make up about 0.5 S to about 10%, preferably about 1% to about 5%, of the emulsion 5 sion weight.

The ratio of water phase to oil phase can vary strong. Generally, the water-in-oil emulsions contain about 20 to about 80% aqueous phase and about 80 to about 20% oil phase, calculated on the whole weight of the water-in-oil emulsion. One preferred ratio water phase to oil phase is about 70 - 75% 10 aqueous phase to about 30 - 25% oil phase, calculated on water-in- the weight of the oil emulsion.

As stated above, the polymerization is initiated by a chemical free radical initiator. The initiator can be solved in Oil phase or in the aqueous phase, depending on the solubility characteristics. Examples of water-soluble initiators are H, N ' azobis-U-cyanovaleric acid (ACVA) of the formula _ CH3 CH3 HOOC-CH2-CH2-C-N = N-C-CH2-CH2-COOH 20 I 1 CN CN potassium persulfate (K2S2O8) and t-butyl hydroperoxide. Example on oil-soluble initiators is azobisisobutyronitrile (AIBN) with the formula 25 ' CH3 and H3 CH, -C-N = N-C-CH3 "I CN CN 2,2'-azobis (2,1-dimethylvaleronitrile) (ADVN) of the formula 30 ïH3 AÉH3 ÉH3 E83 ïH-cH2-ï-N = N_ï "Cu2-I CH3 CN CN CH3 3; and benzoyl peroxide. In addition, water-soluble initiators redox types can be used, e.g. bromate / bisulfite or or KPrCl / Na2S2O5), v metabisulfite (eg KErO3 / NaHSO3 un ' E in ä? å å % ä f. »F ~ 8101426-8 10 15 20 25 30 6 ~ "": - 'i v: .-. Show IfW / F fifi we flfl v- fl- nu fl wwx t “IJ- persulfate / bisulfite (eg KZSZOB / NaHSO 3) and bisulfite / t-bu- tyl hydroperoxide (eg NaHSO 3 / t-butyl hydroperoxide).

The amount of chemical initiator used depends on several factors. As a general rule, the reaction rate is direct proportional to the reaction temperature, i.e. when reacting the temperature decreases, the reaction becomes slower due to a decrease in the activity of the initiator. If a desired reaction rate must be maintained, therefore the amount must initiator is increased when the reaction temperature is lowered. This is particularly important in view of the benefits achieved by polymerization at lower temperature, as indicated below.

By adjusting the reaction temperature and the initiator content polymerization can be achieved within a reasonable time and with a reasonable time percentage conversion of monomer to polymer (eg at least about 95%) while maintaining the benefits of lower polymerization sation temperature. ' Although the concentration of initiator may vary, it is thus generally reversed in amounts from about 0.1 to about 10,000 parts per million (ppm), calculated on the weight of the monomers, typically from about 0.1 to about 1000 ppm, when a redox initiator used, and preferably from about 1.0 to about 10,000 ppm when a thermal initiator, e.g. HCVA, ADVN or AIBN used.

As stated above, one can get some benefits by polymerize at relatively low temperatures, i.e. during about HOOC, preferably from about HOOC 11 to about 0 ° C, wherein from about 30 ° C to about 10 ° C is particularly preferred. Polymerens RSV increases significantly when the polymerization is carried out with the process according to the invention at, for example, ZOOC instead for SOOC. Typical RSV values of those of the invention at a polymerization temperature of about The soluble polymers are thus about 27-31. process is prepared at a polymerization temperature of approx u0 ° C water soluble polymers with RSV of about 32 - 35 and at 2o ° c av ca as - no.

Pessa low reaction temperatures can be reached anywhere rf'- appropriate way, e.g. by introducing reaction vessels vfff »'w n 8101426-8 7 constant temperature bath »arrange kY1 $ 1í fl8 ° P P“ fl t the reaction vessel or the like. It is to be noted that poly- merisation is an exothermic reaction and that the reaction mixture The temperature of the reaction can therefore vary slightly during polymerization. if it is not operated under isothermal conditions. _ .- looks. A typical relationship between the reaction time and reaction Å the temperature of the mixture for a polymerization carried out the following examples at a bath temperature of about 30 ° C are given in Table A. The initial temperature of 22 ° C is maintained before the initiation of the reaction to prevent polymerization tion prematurely.

Table A Reaction time Temp. ° C Reaction time Temp. ° C (minutes) (minutes) 0 22.0 52 33.0 7 ~ 31.0 60 32.1 15 36.0 90 31.0 25 38.9 110 30.6 35 3ß, 5 300 30.0 The best way to perform the procedure according to the invention is illustrated by the following examples. In the examples and in the whole description otherwise "percent" and "part" refer to over-n all weight percent and weight percent unless otherwise indicated. The conversion of monomer to polymer is given in the examples.

This conversion is measured by taking a sample of it prepared emulsion sets a known volume of an acidified solution of bromate and bromide, which brominates monomer in solution. Iodometric titration is then applied to to determine the excess bromine in the emulsion, so that the amount monomer can be calculated.

A typical method for determining the conversion by bvumcring and iodometric titration consist in preparing a 1% emulsion solution by adding 1.5 g of it prepared the emulsion to 1M8, S g of water, containing 0.2 g "Rene 20", a nonionic invert surfactant sold by ICI Americas Inc. The resulting solution is tumbled over night to ensure complete resolution. A 50.0 g g: vu; 0101426-8 W fl w fl n fl wvm I V ' V L. <1, av '2V; -a @ _ ~:; ¿_ f É in* ä ' 8% aliquot of the 1% emulsion solution is weighed into an É iodine flask, and 25 ml of 0.1 N aqueous solution of Kßr-KBrO in the flask followed by 15 ml of 10% H 2 SO 4 and the flask closes quickly with plug. In the gutter of the flask, place 10 ml of 10% Solution of KI, and the flask is placed in the dark for 30 minutes. ter. 20 ml of the 10% CI solution is introduced into the vial by holding through the gutter and slow removal of prop- pen, so that no bromine gas is lost. The mixed ~. «« »= 1 _: _ ~, _. =:; _ Zø _: _ $ q___ titrated with 0.1 N aqueous Na 2 S 2 O 3. Same Procedure is performed on a blank sample of 1% emulsion solution, § containing all the ingredients of the tested emulsion Q without the monomer or polymer. The conversion of monomer Ä to polymer can then be calculated using the following formula: _ ruvs - vs) 15 Conversion = 100 - -ñ: ï-çñ- É where N = the normality of the Na2S2O3 solution g VB = volume of Na 2 S 2 O 3 solution in ml for titration of É the blind test É VS = volume Na 2 S 2 O 3 solution in ml for titration lä of the sample A = weight of total monomers per gram of original lig emulsion B = mol total monomers per gram total monomers 25 more D = weight of the 1-proc. emulsion solution tested in grams.

The RSV of the polymers produced is also given in len. RSV is measured by diluting a portion of it for measurement. Conversion of monomer to polymer prepared 1-prec. the emulsion solution with 2 m. NaCl to a polymer solution with 0.025 g / dl, based on the calculated percentage conversion the conversion of monomer to polymer. For an emulsion which is originally contains 25% by weight of monomer based on emulsion. Weight of the solution, which after the polymerization has 96% conversion of monomer to polymer, the weight is thus calculated 1-proc. emulsion solution to be used in preparation no n ï of a solution with 0,025 g / dl in ¿m Nail on the following obtained: 10 15 20 25 30 35 a1 ouzs-a weight - = -Zg- fi gßg = min g where E = percentage monomer concentration in the original few liga emulsionen ä F = percentage conversion from monomer to polymer. É 10.2 g of the 1% emulsion are diluted to 50.0 g with deionized water, and 57.1 g 19.6%. NaCl solution å is added to form the polymer solution at 0.025 g / dl.

RSV is measured with an Ubbelohde viscometer in a con- constant temperature bath at 30 ° C. The viscometer is filled with 2 m NaCl solution until the solution level between the lines is too high and low level of the lower bladder. The solution must work to the bath temperature (30 ° C). The solution is then drawn up in the viscosity tube using the suction bladder until it is above for the line between the two upper bladders. The time in the second as it takes for the solution to fall from the top to the bottom line at the measuring ball is noted, and the the procedure is repeated until two consecutive attempts match within É 5% apart. The mean value from these two experiments was is reversed in the following calculations.

The viscometer is emptied and rinsed thoroughly with polymer the solution of 0.025 g / dl. The above for 2 m NaCl solution is written procedure is repeated with the polymer solution of 0.025 g / dl. RSV can then be calculated according to the following formula: ts - K / ts _ 1 to ° K / t> RSV = ________JL_____.

C where ts = run-out time_for polymer solution of 0.025 g / dl to = run-out time for 2 m NaCl solution K = correction of the viscometer for kinetic energy C = polymer concentration in g / dl, in this case 0.025.

Example 1 This example illustrates the preparation of a water oil emulsion containing a water-soluble saayolvm fl r of a fi qß-an fi “~ .V» v1 = + nnh acrvlamide. 8101426-8 10 15 20 25 30 35 ~ t (J, tårafesi-: fl fnsà-lßh I¿f «1: .-« á- »š-- - v 10 vattsnfam »enas gen» merge; of 111m g p of a 09.55 percent. aqueous solution of acrylamide (87, S g acrylic- E amide), 110.3 g 3H, 0-proc. aqueous solution of sodium acrylate (37.5 g sodium acrylate), 0.25 g 1%. aqueous solution of the heavy metal chelating agent 'Versene 80', which is the sodium the salt of diethyltriaminepentaacetic acid (sold by Dow Chemical C0.), N0.0 g NaCl, 5.0 g 1-proc. aqueous solution of ACVA (H00 ppm ACVA, based on the weight of the monomers) and 25.89 g of water (total 3S8.0 g). .

The oil phase is prepared by combining 129.5 g "Isoparß%" with 12.5 g of a water-in-oil emulsifier (mixture of mono- and diglycerides and polyethoxylated sorbic tolhexaoleate), so that the total weight of oil phase becomes 1N2.0 g.

The aqueous phase and the oil phase are combined, and the The mixture is homogenized for 2 minutes in a Raring mixer at high speed, so that a water-in-oil emulsion is formed.

To prevent premature polymerization, the emulsion is flushed. the nitrogen with nitrogen in a nylon bag placed in an ice water bath.

The played emulsion is introduced into a 1.5 l resin kettle sat in a water bath with constant temperature. The kettle is equipped with a crescent-shaped stainless steel stirrer (normally driven at about 360 rpm), one nitrogen inlet and one - -æ. = °; = mf: thermistor probe.

The polymerization is carried out at a bath temperature of 50 ° C for 5 hours. A copolymer of sodium acrylate and acrylic amide is produced with an RSV of 29.2. The conversion from monomer to polymer is 97.8 8.

In general, the percentage conversion of mono- more proportionally proportional to polymer and RSV, i.e.

RSY decreases as conversion increases. This connection between conversion and RSV are illustrated by Table B, which shows the results The latency of several polymerizations. The polymerizations are carried out in according to the procedure described in Example 1 except that the initiator, the initiator concentration and The reaction time is varied as indicated in Table B. 8101425-8 11 Table B Conversion Polymers- Bath- Initiator Polymer monomer to RSV isation temp. (ppm) time of polymer 1 soäc AcvA, uoo 9 h 93.9 6 91.1 2 sooc AcvA, non 9 h 92.9% 31.6 9 so c AcvA, uoo 6 h 91.6 6 29.2 u sogc Acva, zsoo a h 96.9 6 91.3 6 se c AcvA, 2500 6 h 96.0 9 96, 6a so ° c, Anvu, uoo 1 h 69,6 9 us, eb aoäc ADVN, uoo 2 h 66,6 6 - 66 aooc ADVN, uno 3 h 91.9 6 96.6 6a aooc ADVN, uno u h 99.9 6 37.6 66 ao c Anvn, uno s h 99.9 6 91.9 (1) Polymerizations 1 - 5 are separate polymerizations.

The polymerizations 6a-6e are a single polymerization with sampling was hour. (2) Calculated on the monomer weight. sàemgel 2 - 29 The following examples illustrate the effect of NaCl on those with the process of the invention produced the RSV of the polymers.

The emulsions are made from the same ingredients and on the same method as in Example 1 except that the chemical the type and amount of initiator, the temperature and the amount of NaCl varied as indicated in Table 1. f ”'^, 8101426-8 12 Table 1 _ "" "" 'Omvandlmgll . . 0 ' Ex. Bad0emp., Inztxator \ NaC1 (d) :: g; ::: I K¿v 2 so ° c, 0 0 Acva, 000 0 91.8 1 29.2 0 so ° c, s n A000, 100 0 93.8 ß 30.1 0 s0 ° c, s n Anvu ,. 00 0 00,1 0 20.0 0 s0 ° 0, s n x s 08,20 0 00.7 1 30.2 0 s0 ° c, 0 h xåröa, 100/0 01.0 0 00.0 000003, 00 (”) 1 so ° c, 0 n A100, 100 0 00,0 0 20,0 0 00 ° 0, 0 h A100, 100 0 01.0 0 20.1 0 0020, s h 0:00, 000 0 00,0 0 22,0 10 0000, s n A100, 000 0 00,2 0 20,0 11 00 c, s h A100, 000 0 01.1 0 22.0 12 0020, s n Acvn, 000 0 00,0 0 20,0 10 so c, s h A100, 000 0 00,2 0 22,1 10 00 ° C, s n Acva, 2000 0 00 0 00,1 10 0020, 0 n Anvu, 000 0 00,0 0 02,0 10 0000, s n Anvn, 000 0 00,0 0 00,0 12 0000, s n Anvu, 000 0 00,0 0 00,0 10 0000, 0 n Anvu, 000 0 00,0 0 00,2 10 0000, s n A100, 2000 0 00,2 0 02,0 20 00 0, 0 n xavoa, 100/0 00,0 0 00,0 000003, 00 (°) 21 00 ° 0, s n uaasos, 100/0 00,2 0 00,0 0 TBHP, 20 (b) (0) 22 00 0, 0 n xzszo, 20/0 01.0 0 02.0 ua fl soa, 0 (”) 20 0020, s.n Anvu, 000 0 00 0 00,0 20, 0000, 0 n Anvn, 000 0 00 0 01.0 20 0000, s n Acva, 2000 0. 00 0 00,2 20 0000, s n Acvn, 0000 0 00,0 0 00,0 22 0000, s n Acva, 0200 0 00,0 0 20,0 20 0000, 0 n AcvA, 0000 0 00 0 00,0 20 00 0, s n Acva, 0100 0 00,0 0 00,0 (a) Calculated on the monomer weight (b) The first component of the redox system is dissolved in water faacn before emulsification. The second component t¿ll0üLL0 under the polymerization in ten equal doses evenly distributed over the polymerization time. (c) TBH? is t-butyl hydroperoxide. (d) Calculated on the total weight of the emulsion. "~ '~, ~ r5.-_ n--; .. 01 10 15 20 25 30 81 01 426-8 13 The data in Table 1 show that the presence of NaCl in during the polymerization significantly increases the set the RSV of the polymers at similar values of the conversion of monomer to polymer while increasing the conversion from monomer to polymer. For example, a comparison shows of Examples 2 and 12, that under the same polymerization conditions sees both the conversion and RSV increase dramatically (from 88% to 97.8% and from 2N, respectively, to 29.2) when NaCl comes in the emulsion.

Comparisons of the results from the other examples, where the polymerization conditions are identical except presence of NaCl, i.e. examples 16 - 18 and 23 and IH and 25, further illustrates this improvement in conversion and RSV. This increase in both conversion and RSV is visible hardly surprising given the inverse proportionclla relationship between conversion and RSV as illustrated by Table B above. 4 Example 30 The following example illustrates the effect of Lißr on those with process according to the invention of the polymers prepared RSV. The emulsions are made from the same ingredients and on the same way in Example 1, except that LiBr is used in instead of NaCl, and the amount of initiator and reaction temperature The temperature is as shown in Table 2.

Table 2 . _ (a) Qmvandling Ex B: ÉšemP "Inëtlâšop% LíBr (b) monomer to Pin 'pp polymer J' so 3o ° c, s h AcvA, zson 10 96 s: sn (a) Calculated on the weight of the monomers. (b) Calculated on the total weight of the emulsion.

Comparison of data in Table 2 with data from examples plen 23-29 in Table 1, in the synnex of Example 25, in which the reaction the conditions are the same fi if in this example disregarded from the presence of LiBr in the emulsion, highlights increase in RSV with a simultaneously high percentage t "_ .CTQ occurs when LiBr is present in the emulsion .- “'< v => m-- ~ s «-» -. ~ ..I.,.,., N. “^ _ šïwwz fl w fi w-nw-e-vgw; than:: à- _ »_ § 8101426-a Ä 10 15 20 25 30 35 14 Comparative Examples I - IV The following comparative examples show that such water- ii soluble salts such as KCl and Na2S0u have no measurable effect on those produced by the method according to the invention set RSV of the polymers. The emulsions are made from the same ingredients and in the same manner as in Example 1, except gg from using KCl and Na2 $ 0u instead of NaCl or LiBr and the type and concentration of the initiator and the reaction m (new:: flä- the temperature is varied as indicated in Table I.

Table I É . - (a) Conversion É Ex. Badtemp. Initiator%. ¿ m Kc1 Naqsølfl ”ggggï: H11 RSV 1 ange, s h ADVN, sou a - se s 32.8: 11 ao c, s h AcvA, zsoo a - ss s s2,1§ 111 scâc, s h ADVN, soo - 2 and s 27.2? Iv ao c, s n AcvA, zsoo - 2 ss% 3o, e¿ (a) Calculated on the weight of the monomers i .- »_ ,,,.:. §f« w «e \ i (b) Calculated on the whole emulsion Comparison of data in Table I with data for examples 23 - 29 in Table 1 show that the presence of KCl or Na 2 SO 4 in p the emulsions before the polymerization do not lead to any significant increasing the RSV of the polymer at a high percentage conversion ling. Ä Examples 31 - 37 The following example illustrates the effect of a reduction of the polymerization temperature of those of the process according to the invention produced the RSV of the polymers. Emulsionerra made from the same ingredients and in the same way as in Example 1 except that the type and chemical initiator amount and the polymerization temperature are varied as indicated in Table 3. The amount of chemical initiator used increases when the polymerization temperature is lowered, in order to substantially equip valent reaction rate and percentage conversion of mono- more to polymer should be maintained at all temperatures. Oh Data in parentheses are taken from the previous example.

E 8101426 ~ 8 3 1 L 15 š ggpell 3 Example Bath temp., Initiator (a) Conversion 0 tia (ppm) monomer tzll Rav polymer (2) (so ° c, s n) (ncva, uno) (s1, a 1) (2s, 2) (3) (so ° c, s n) (acvn, 1so) (s3, a 1) (3o, 1) (u) (sogc, s n) (Anvu. ao) (ss, 1 1) (2s, a) (s) (sooc, s h) (xys oß 21) (su, 1 1) (3o, 2) (s) (so c, s h) (xß 3, 100 / (s1, a 1) (30-9) Naasoa, uo) (b) (1) (sogc, s h) (A1au, '1oo) (ss, s 1: :: ¿.s) (3) '(so ° c, s n) (Aras, 1sc) (s1, s 1) .f: 1_ * (9) (soøc, s n) (Alan, noo) (ss, ~ 1) (2v, s) (10) (so c, s n) (Alan, soo) (9s, 2 1) (2s, s) (11) (so? C, s n) (axsn, soo) (s1,1 1) (22, ~) 31 uogc, s n Acva, 1ooo 9a, s 1 33, s 32 uooc, s n Anvu, zoo 93.3 1 3 ~, s 33 uooc, s n Arns, 1ooo 93.1 1 32.1 31 no c, 3 n xaroa, 1oo / 93.2 1 32.3 nansoa, ~ ø (b) (11) (aoâc, s n) '(AcvA, zsoo) (ss 1) (3s, 1) (13) (aooc, s n) (Anvu, non) (su, s 1) (3v, ~) (1s) (aooc, s h) (Apvu, soo) (ss, o 1) (3u, s) (11) (aooc, s n) (Anvu, soo) (ss, ~ 1) (3u, o) (13) (sooc, s n) (Anvu, soo) (a) (ss, 9 1) (3s, v) (19) (3o ° c, s n) (arsa, zsoo (ss, 2 1) (3v, a) (20) (so c, s n) (xavoa, 1oo / (sa, s 1) (3u, o) uanco3, uo (”)) (21) (3o ° c, s n) (ua fl coa, 1oo / (ss, 2 1) (3 ~, u) TB3P_ 20 (b) (c), (22) (30 ° C, s n) cxzszoa. 20 / (s1, ~ 1) (32.3) uaasoa, a (b)) as zogc, s n Anvn, 1332 91 1 10.1 35 zooc, s n Anvu, zooo se 1 33.2 31 zo c, s n Acvn, aoou se 1 3e, o (a) Calculated on the monomer weight. (b) The first component of the redox system is dissolved in water phase before emulsification. The second component is added during the polymerization in ten equal doses evenly distributed over the polymerization time. (c) TBHP is t-butyl hydroperoxide. (d) 1 Q NaCl, based on the whole emulsion, is used instead for 8 S. _ I. _ ._11 '_ _. fi _ ;, -> ¿¿-... «, _ w, ~, --.- ~ .1,., _-,. . »¿~ '1' ..- ^, _ \ _ j f:>, ^" _ ', " “Www is1o142s-s 10 u 16 g Examples I - 11 are control examples and reduction of the RSV of the polymer, which results shows it of use so ° c.

RSV som ernàs while maintaining equivalent conversion of monomer to polymer.

For example, the RSV of the polymers prepared at 20 ° C is present in the range 38 - M0, while the polymers produced at SUOC merers RSV is 22 - 31 with the conversion of monomer to the increased concentration of initiator at The data in Table 3 illustrate the increase of by lowering the polymerization temperature polymer substantially the same at both temperatures.

Claims (3)

8101426-a _ï ~. ~ Rm-. ~ '~ Rw fl um ~ swr-f'êš w-rf' Rel. 17 PATENT REQUIREMENTS By means of a free radical initiator chemically initiated water-in-emulsion polymerization process for the preparation of water-soluble anionic copolymers of sodium acrylate and acrylamide, characterized by adding a salt in the form of sodium chloride or lithium bromide in an amount of from about 2% by weight %, calculated on the whole emulsion, and up to the saturation level of the salt, to the aqueous phase of the water-in-oil emulsion before the polymerization and disperses the aqueous phase and the oil phase, whereby the droplet size of the aqueous phase in the formed emulsion becomes about 5 μm or less. 2. A process according to claim 1, characterized in that the temperature of the water-in-oil emulsion is kept below about 0 DEG C. during the polymerization. 3. A process according to claim 1, characterized in that the salt is sodium chloride.