CA1161597A - Emulsion copolymer cation exchange resins and ion exchange process therewith - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
According to one aspect of the invention as disclosed, emulsion copolymer particles with diameters smaller than 1.5 micrometers and functionalized with cation exchange functional groups are prepared and suspended as emulsions in liquid media to form liquid cation exchange materials.
Also, emulsion copolymer particles with diameters less than 1.5 micrometers are functionalized with anion exchange functional groups by a method involving coagulation of the emulsion, according to another aspect of the invention disclosed herein. Both weakly basic and strongly basic anion exchange resins are prepared from aromatic or acrylic copolymers, and the emulsion coagula may be resuspended to form anion exchange emulsion4. Additionally, by a further aspect of the invention as disclosed, ions are exchanged between emulsion ion exchange resins and conventional ion exchange resins during both batch and column contact. This process may be used to place the emulsion resin or the conventionai resin in the desired ionic form.

Description

ION EXCHANGE PROCESS IN~OLVING EMULSION
1~ }~XC~ANti;~ ~S I~S
Background of the Invention The present invention concerns fine-particle-size ion exchange resins and methods ~or their preparation.
In particular it concerns spherical, crosslinked emulsion copolymer particles in a size range of from about 0.01 to about 1.5 micrometers in diameter, which bear ion exchange functional groups, and emulsions ~f these particles. It further concerns the preparation of these particles and emulsions, and the use of these particles and emulsions in removing dissolved and undissolved material from liquids.
Pinely divided ion exchange materials have been used extensively as filter media for the simultaneous filtration and deionization of condensate water from steam turbine generators, and to a lesser extent in pharmaceutical applications such as drug carriers and ~ablet disintegrators, and in other commercial ~0 applications.
In the past such finely divided ion exchange materials have been produced by grinding or otherwise physically reducing the size of ion exchange particles produced by conventional processes involving the separate i 25 steps of poly~erîzation -- most commonly suspension ; polymerization -- and func~ionalization.
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Schultz and Crook (I & EC Product Research and Development, Vol. 7, pp. 120 125, June, 1968) have produced partlcles of ground lon exchange resin with average diameters of one mlcron or smaller, but the partlcles are not spherical, and the range of dlameters wlthln a given sample of such materlals ls large~ i.e., the partlcles are not uniformly slzed. Even though large partlcles may constitute only a small fractlon of the total number of ground particles, they represent a much larger fractlon of the sample weight. As a result, such ground reslns exhiblt settllng of a signirlcant fractlon of the lon exchange materlal welght from aqueous suspenslon.
- Suspenslon polymerization lnvolves suspending droplets o~ organlc llquid contalnlng monomers 9 polymerizatlon inltlators and suspenslon stabllizers in an aqueous-phase medlum. The droplet slze, largely a functlon of agitatlon rate, controls the ~lnal polymer partlcle size, which normally ranges down to about 40 mlcrometers, although slzes down to 5 mlcromekers (US
Patent 3,357,158) or 10 micrometers (US Patent 3,991,017) have been disclosed. Ion exchange materlals have also been produced by bulk polymerizatlon.
Physlcally reduclng the particle slze of such polymers in bulk or bead ~orm to sub-mlcron slzes ls dlfflcult and expenslve, and produces materlal wlth undeslrable physlcal characterlstics such as lrregular particle shape and broad partlcle-slze dlstrlbutlon. It may also produce undeslrable heat degradatlon of the resln.
Sub-mlcron slzed, spherlcal polymer particles have been prepared in the past, lncluding some with limited ion exchange functionallty. These particles were ~, .... .

prepared rrOm monomers which contained ion exchange functlonal groups, such as acrylic and methacryllc acid, or dialkylaminoalkyl acrylates and methacrylates. In most cases the polymerlzatlon reactlon used was emulæion polymerizatlon. Thus Haag et al (U.S. Patent 3,847,857) used "...from 5 to 70% by weight...of one or more monomers containing an amine or quaternary ammonlum group..." (column 2, llnes 56-59) ln forming a functional, cros~linked emulsion ion exchange resin for use ln palnts and other coatings.
Rembaum et al (U.S. Patent 3,985,632) similarly prepared chromatographic adsorbents by emulslon polymerizlng monomer mlxtures contalning minor amounts of monomers wlth amlne functlonallty (column 5, llnes 25-46). Fitch (U.S. Patent 3,104,231) used up to 15% by weight of monomers containlng carboxyllc acid groups when preparlng crossllnked emulslon copolymers. He cautlons that higher content of such monomers leads "to elther solublllty of the copolymer ln water or dllute alkali or slgnificant swelling of the copolymer ln ~uch aqueous medla." (column 6, llne 70 - column 7, line 4).
Hatch (U.S. Patent 3,957,698) describes a precipitation polymerization for maklng crossllnked, spherlcal ion exchange resin particles in a size range similar to that of emulsion polymer partlcles. The precipltatlon process inherently produces larger particles, in the range of 0.1-10 micrometers (compare 0.01-1.5 mm for emulsion polymerizatlon)) and involves the precipitation of polymer particles from a monomer-solvent solution ln which polymer is insoluble. In emulsion polymerization the monomer is only slightly ~oluble ln the solvent, and the polymer particles are formed when monomer-swollen soap mlcelles contact solvent-phase-initlated polymer chains. Hatch mentions that "sultable micro bead resins can be prepared by suspenslon or emulsion polymerization..." He then describes suspenslon polymerization but fails to indicate any detail of an emulsion polymerization process (column 3, lines 30-40). The ion exchange microbeads of Hatch are weak acid reslns made from carboxylic acid monomers such as acrylic or methacrylic acld, although the uRe of esters of these acids is mentloned, wlth hydrolysls subsequent to polymerlæatlon. Hatch exempllfles the preparation of a microbead from vlnylbenzyl chlorlde (Example 43, but the partlcle slze (3-7 microns~ ls clearly outside the range of the present inventlon, and no attempt ls made to lmpart lon exchange functionallty to the mlcrobead itself untll it has been incorporated ln an ion exchange resin matrlx. Hayward (U.S. Patent 3,g76,629) also prepared weakly acldic cation exchange resins of a size '~less than 2~ microns" using a modified suspension polymerization and carboxylic acid monomers.
Tamura (Nippon Kagaku Kaishi 76 (4), pages 654-8, 1976) discloses the preparation of strongly acidic catlon exchange resln material from emulæion copolymers. Tamura coagulated styrene-divinylbenzene copolymer emulsions and functionallzed them with fumlng sulfuric or chlorosulfuric acids. He subsequently mlxed the coagulum into a polypropylene membrane, but dld not teach that the coagulum might be re emulsified.
The Inventlon According to this lnventlon a novel class of ., .55i~

small-particle-size, spherlcal lon exchange reslns, having partlcle diameters smaller than those hereto~ore known ln the art, has been discovered. These resins are prepared from crossllnked emulsion copolymer partlcles, and may possess a degree of functlonallzation greater than about 0.7, and as high as about 1.5, functional groups per monomer unlt. The process by whlch these resins are prepared involves functionalization of the emulsion copolymer particles wlth weakly acidic, strongly acldic, weakly baslc or strongly basic lon exchange ~unctional groups. The emulsion copolymer particles may be ~unctionalized dlrectly, as by hydrolysls, sul~onatlon, and simllar reactlons, or indlrectly by such reactions as chloromethylation followed by a functionalization reaction such as amlnation. To facilitate handling of the particles, the emulsion may be coagulated, and the large coagulum particles handled like large polymer beads for lsolation and reaction. Alternatively, the emulslon copolymer partlcles may be dried prior to functionallzing them. After functionalization the partlcles ~ay be resuspended as an emulslon of discrete particles by high-shear mixing, ultrasonic vibration5 mild grindlng or other comminuting method which disrupts the agglomerated pieces without damaging the spherical partlcles of the emulslon lon exchange resln.
The ion exchange resins of this invention may be prepared in narrow particle-size ranges with mean values ln the submicroscopic range (which term, as used hereln, means having particle diameters below about 1.5 mlcrometers), variable from about 0.01 micrometers to about 0.5 micrometers ln diameter, and by the use of ~. J

special technlques, to as large as about 1.5 micrometers ln dlameter~ They may be prepared as catlon or anion exchange re~lns, that is, with strongly acldic, strongly baslc, weakly acldic or weakly basic functionallty.
The lnventlon, in a further aspect, resides ln a process for changlng the ionic form of a plurallty of ion exchange resins of the same lon exchange type, at least one of the reslns being in the physical form of approximately spherical~ submlcroscoplc beads and lnltlally belng substantlally ln a flrst lonlc form, and the balance of the resins being ln the physical form of macrobeads and inltially being substantially in a second lonlc form, which process comprises contacting the macrobeads in the second lonic form wlth an emulslon of the submicroscopic beads ln the first ionic form until ion exchange occurs between the ions of the submicroscopic beads and the lons of the macrobeads.
This aspect Or the inventlon is disclosed and claimed in Canadlan Application No. 335,831 of Berni P. Chong, filed September 18, 1979, of whlch the present application ls a dlvislonal.
In the Drawings:
Figures 1-3 and 4a-4d are electron photomicrographs of typical lon exchange materlals of ~he present lnvention. Figures 1-3 are photomlcrographs of three dif~erent slzes of anion exchange emulsion reslns in the hydroxyl form, at a magniflcatlon of X50,000. Flgures 4a-4d are photomlcrographs of a slngle floc at four dif~erent magnifications; khe floc was prepared by mlxlng a cation exchange emulslon resin with an anion exchange i `"'7 emulslon resin. Each of the materlals shown ln these photomicrographs was prepared by methods taught hereln.
Figure 1 shows a strongly baslc anlon exchange emulslon resin ln the hydroxyl ion form, derlved from a copolymer contalnlng 3% (weigh~) divinylbenzene and prepared according to Example 14 below, coagulated according to ~xample 2 belowJ chloromethylated and aminated accordlng to Example 17 below, and converted to the hydroxyl form accordlng to Example 21 below.
~lgure 2 shows a strongly baslc anion exchange emulslon resln ln the hydroxyl ion form, derived from a copolymer contalning 3% (welght) dlvlnylbenzene and prepared according to Example 1 below, coagulated according to Example 2 below, chloromethylated and amlnated according to Example 17 below, and converted to the hydroxyl form according to Example 21 below.
Figure 3 shows the strongly basic anion exchange emulslon resln in the hydroxyl lon form of Example 21 below.
Figure 4b shows the floc of Example 22 below at a magnlflcatlon of X300; Flgure 4a shows the same ~loc at a magniflcatlon of X1000; Flgure 4d shows the same floc at a magnlficatlon of X3000; and Figure 4c shows the same floc at a magnification of X10,000.
By referring to the partlcles shown ln the ~igures, lt may be seen that thece partlcles are approxlmately spherlcal, that as prepared they have a relatively narrow partlcle-slze dlstribution, and that they may be prepared ln dlfferent partlcle slzes. The 3o partlcles of these flgures range ln size from about 0.017 micrometers to about 0.45 mlcrometers.
Although the figures lllustrate strongly baslc '~
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anion exchange emulsion resins, the partlcles of other anion exchange emulsion reslns, and of cation exchange emulsion reslns, have slmilar appearances and size dis~rlbutlon.
The a~gregations of partlcles ln these ~igures were concluded by the laboratory preparlng the photomlcrographs to be artlfacts assoclated wlth preparation o~ the samples for mlcrography.
In the case of strongly acidic and baslc, and weakly baslc reslns, the formation of physically stable coagula from the crossllnked emulslon copolymers makes posslble the lsolation o~ the copolymers for functionallzatlon. Because of their small partlcle slze the emulslon copolymer particles cannot practlcally be flltered or otherwlse separated from the llqulds in whlch they are prepared, nor could functlonalized copolymer partlcles be separated from the functlonalization mixtures. After coagulatlon, the large coagulum particles can be filtered and washed ln much the same way as ion exchange resin beads of conventlonal size. Functlonallzatlon of the coagulated emulsion copolymer involves conventional reactions well known in thi~ art.
Weakly acidlc emulslon copolymer resins haYe physlcal properkies ~lmilar to those of the resins described above, but they need not be coagulated prlor to isolatlon and functlonallzatlon. A preferred method of preparing the weakly acldlc resins of this lnvention involves adding a crosslinked acrylic ester emulslon 3 copolymer to an alkali hydroxide solution. Upon addition the emulsion may coagulate, but as the copolymer ester linkages are hydrolyzed to form .
~' 5~7 carbox~lic acid groups in the salt ~orm, any coagulum formed re-suspends to form an emulsion of the salt o~
the functionalized resin. The functlonal groups o~ the resin may then be converted to the free acid form by treating the emulsion wlth a c~nventional, strongly acldic catlonlc exchange resln in the ~ree acld ~orm.
The emulslon copolymer lon exchange reslns of this lnventlon posses~ the followlng advantageous propertles:
(a) regular, generally ~pherlcal shape, (b) a high degree of structural rlgidity whlch ls controllable by the degree of crossllnking in the emulslon copolymer, (c) a controllable, small particle size, the medlan value of which may be varied from about 0.01 to about 1.5 micrometers, (d) a narrow particle slze range; photomlcrographlc analysis shows ranges typlcally i 9 nanometers o~
the partlcle medlan dlameter for about 80% of the particles, (e) a large surrace area per unit weight, varlable wlth partlcle dlameter ~rom about 4 square meters per gram to as great as about 120 square meters per gram, compared wlth about 0.1 square meter per gram ror typlcal, small-dlameter conventlonal lon exchange reslns, (f) a high degree of ion exchange functlonality, varlable to greater than one functlonal group per monomer unit, 0 (g) the abllity to form essentially non-settling emulslons, except ln the largest partlcle sizes, (h) a particle size lncrease on hydratlon, controlled .

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by the degree of crosslinklng ln the emulslon copolymer, whlch is variable from about 10% to about 500% or more of the dry particle diameter, (1) water insolublllty and negllglble water extractabllity, and deslrable sensible properties of (~) subdued taste, (k) ablllty to mask the taste of materials bound to the resln, (l) a smooth, non-grltty texture to the mouth, and (m) a smooth, non-lrrltatlng texture to the skin.
The emulsion copolymers from whlch the ion exchange resln of thls invention are derived may be prepared by conventlonal emulsion polymerlzation technlques. These techniques typically involve, but are not llmlted to, polymerlz~ation of an emulsion comprising the monomers and a surface-actlve agent.
The polymerlzatlon ls usually lnltlated by a water-soluble lnitlator. It 18 well known that the action of most such initlators is lnhlb$ted by the presence of oxygen, so oxygen-exclud1ng technlques, such as uslng lnert gas atmosphere and deoxygenated solutions and emulslons, are preferably employed ln the polymerization. The cholce of surface-actlve agents and lnitlators wlll be apparent to one skilled in this artO The monomers from which the emulsion copolymers are derived comprise a ma~or amount of a monoethylenlcally unsaturated monomer or mixture of such monomers and a minor amount of a polyethylenlcally unsaturated monomer or mlxture of such monomers which act to crosslink the polymer. The followlng are examples of monoethylenically unsaturated monomers .

useful ln preparing the emulsion copolymers: aromatic monomers, including polycyclic aromatic monomers such as vinylnaphthalenes and monocycllc aromatic monomers such as styrene and substituted styrenes J whlch lnclude ethylvinylbenzene3 vinyltoluen~ and vinylbenzyl chlorlde; and acrylic monomers, the esters of methacrylic and acrylic acid, such as methyl acrylate, ethyl acrylate, propyl acrylate, lsopropyl acrylate, butyl acrylate, tert-butyl acrylate, ethylhexyl acrylate, cyclohexyl acrylate, lsobornyl acrylate, benzyl acrylate, phenyl acrylate, alkylphenyl acrylate, ethoxymethyl acrylate, ethoxyethyl acrylate, ethoxypropyl acrylate, propoxymethyl acrylate, propoxyethyl acrylate, propoxypropyl acrylate, ethoxyphenyl acrylate, ethoxybenzyl acrylate, and the corresponding methacryllc acid esters.
In the case of the acrylic esters, the preferred embodiment employs lower aliphatic esters of acryllc acid in whlch the aliphatlc group contalns from 1 to 5 carbon ato~s. Thls ls a partlcularly preferred embodlment when the copolymers therefrom are to be employed as lntermediates in the preparation of either carboxylic cation-exchange emulsion copolymer reslns or anlon-exchange emulsion copolymer resln~. In the pr~paratlon of both the carboxyllc exchanger and the anlon exchanger, the ester group is replaced. Thus, the practlcal choice ls methyl or ethyl acrylate.
Suitable polyunsaturated cross-llnklng monomers lnclude the following: divinylbenzene, divinylpyridine, di~inyltoluenes, dlvinylnaphthalenes, ethylene glycol dimethacrylate, divinylxylene, dlvinylethylbenzene, dlvlnylsulfone, dlvinylketone, ., I
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dlvinylsulfide, trivinylbenzene, trivinylnaphthalene, trlmethylolpropane, trimethacrylate, polyvlnylanthracenes and the polyvinylethers of glycol 3 glycerol, pentaerythritol, and resorcinol.
Partlcularly preferred cross-linklng monomers include the following: polyvlnylaromatlc hydrocarbons such as dlvinylbenzene and trlvinylbenzene, glycol dlmethacrylates ~uch as ethylene glycol dimethacrylate, and polyvlnyl ethers of polyhydrlc alcohols, such as dlvlnoxyethane and trlvlnoxypropane. Aqueous emulslon polymerlzatlon Or mixtures of ethylenically unsaturated monomers are descrlbed ln United States Patent Nos.

2,753,318 and 2,918,391, among others.
As noted above, emulslon copolymer ion exchange resins of thls lnventlon may be prepared with medlan partlcle diameters from about 0.01 to about 1.5 mlcrometers; they may also be prepared in a range of preferred medlan partlcle dlameters from about 0.01 to about 0.5 micrometers. The median partlcle dlameter of the resln may be accurately controlled withln these ranges, and the dlstrlbutlon of partlcle dlameters about the median value ls narrow, ~ar narrower than distributions obtained wlth commlnuted reslns of small partlcle dlameter. Control of the resln particle diameter depends on the emulslon copolymer, even though the partlcle slze ls increased by functionali~ation.
Such control of the emulslon copolymer particle diameter ls well known. For example, within the copolymer particle diameter range of about 0.05 to about 0.3 mlcrometers the slze may be controlled by varying the level of surface active agents present ln the polymerlzation mixture, an increase in these agents

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tending to produce a smaller emulsion copolymer particle. Crosslinker levels ln the polymer tend also to exert an effect on copolymer particle diameter; more highly crossllnked copolymer particles tend not to swell as much when they hydratê as llghtly crosslinked particles. Below diameters of about 0.1 mlcrometers special surface active agents may be used to control partlcle size down to about 0.01 micrometers as lllustrated below in Example 14. Copolymer particles larger than about 0.3 micrometers may be formed by further reductlon of the level of surface active agents, or by growing larger partlcles from "seed"
particles of pre-formed emuislon copolymers. Polymer partlcles may be formed ln this way to as large as about 1 micrometer in diameter; subsequent functionallzation produced ion exchange resln particles wlth diameters as large as about 1.5 mlcrometers J The process of making large copolymer particles ls lllustrated below ln Example 13.
Crosslinker levels may be selected between about 0.1% and about 25%, a more preferred range being from about 1% to about 20%. Selection of crossllnker levels depends upon the particular type of resin, physlcal properties, and the level of functionallty deslred ln the emulsion lon exchange resin product. For example, sul~onic acld functionalized resins are prepared from emulsion copolymers with higher levels of crosslinker than copolymers for preparing amlne functionallzed resins. SimilarlyJ if very low swelling is desired, a processing advantage that permits the use of smaller reactlon containers, higher crosslinker levels are used. Ranges of about 3% to about 12% crosslinker are ~ill S~7 typlcal for sulfonic acid ~unctlonallzed reslns with low swelllng properties, and hlgher levels may be used when exceptionally low swelling ls desired. Levels above about 25% may be employed for speclal purposes, ~ so long as the crosslinker, as well as the monoethylenlcally unsaturated monomer, may be functlonallzed to produce a reasonable number Or functlonal groups per monomer unit. Where more rapld kinetlcs are desired, lower crosslinker levels are selected. While anlon exchange emulslon reslns pre~erably contain crossllnker levels between about 0.1% and about 7% or higher, they more preferably contain from about 0.5% to about 3% crosslinker. The selectlon of specific crossllnker levels to produce the deslred balance of physlcal properties is well known to those skilled with conventional lon exchange resins, and the same guldlng princlp~es are used wlth emulslon resins.
To permit further handllng, the emulsion copolymer ls coagulated using one of several well-known procedures. A preferred coagulation procedure is to add the emulslon to a hot saline solution; aqueous solutlons at concentratlons from saturated to about 2%
(wt) sodlum chloride or other lnorganlc salts such as calcium chloride, aluminum sulfate and others may be used. Aqueous sulfuric acld solutlons, concentrated to about 4% (wt), are also suitable, and aqueous alkali hydroxlde solutions such as those of potasslum or sodium hydroxlde are especially ~uitable for 3o coagulation and slmultaneous hydrolysis and functlonalization of acrylic ester copolymers.
Addltion of the emulsion to the stlrred coagulant ~,. I

solutlon allows the coagulum to dlsperse as particles with slze dependent upon the stirrlng rate; the useful slze spans a wlde range but for easiest handllng should not fall below small granules i~to the powder range~
Addltion of the coagulant solution to the emulslon 18 posslble, but tends to produce an unwieldy coagulated mass rather tha~ coagulum particles. The emulsion may also be coagulated by drying lt; spray drylng ls a preferred procedure for the preparation of ~trongly baslc resln product from an aromatlc copolymer; the partlcles produced by thls procedure tend to be too small for e~ficlent handllng when used for functionalization reactlons that requlre subsequent flltration and washing. Other useful procedures for coagulatlng the copolymer emulslon include vlgorous stlrrlng, alternating freezlng and thawing, and addltlon of an organlc solvent to the emulsion.
Once produced, the coagulum particles are coherent enough to withstand typlcal handllng techniques used ln the washing, filtration, and functionalization of conventional, suspension-polymerized ion exchange beads. The coagulum is preferably freed from ~ater by evaporation at ambient or higher temperatures, or by rinsing with a water-miscible, dry, organic solvent~ to prepare it for convention functionalization reactions.
In general the reactions employed to functionallze emulsion copolymer ion exchange resins are the same as those used to produce ion exchange resins from conventional, suspension-polymerized copolymers. As a 3~ high degree Or functlonalization ls deslrable because it produces a large number of functional ion exchange sltes per unit welght of resin, the emulsion ion i ~3~6 - 15 ~
exchange resins of the present inventlon are functionallzed to between about 0.7 and about 1~5 functlonal groups per monomer unit. The more preferred range is from about o.8 to about 1.2 functional groups per monomer unit. The term, "functlonal groups per monomer unit", as used herein, refers to the number of lon exchange~functlonal groups per total monomer unlts, both "backbone", monoethylenically unsaturated monomer and crossllnklng, polyethylenically unsaturated monomer. For example, ln the case of an aromatlc backbone monomer and aromatlc crosslinker monomer used to prepare a copolymer, this term would refer to the number of functional groups per aromatic ring in the polymer. Simllarly, in the case of a copolymer with a functlonalized acryllc backbone and an unfunctionalized aromatlc crossllnker, the degree of functlonalization wlll be the functlonal ion exchange groups per total monomer unlts, both acrylic and aromatic. The degree of functionalizatlon may be thought of as the number of functlonal groups per mole of all the monomers which constitute the copolymer. Some of the typlcal processes for functionalizlng the copolymer are lllustrated below.
Strongly acldlc emulsion copolymer lon exchange resins of this invention may be prepared, for example, by ~eating coagulum particles of crossllnked styrene or substituted styrene emulslon copolymer with concentrated sul~urlc acid to produce a sulfonlc acld-functionalized resin, rinsing the product free of 3o excess acid ~ith water, and re-suspending the coagulated emulsion partlcles by the processes descrlbed above.
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Weakly acidlc emulsion copolymer ion exchange resins Or thls invention may be prepared, for example, by hydrolyzing crosslinked acryllc ester emulslon copolymers with alkall metal hydroxide solutlons, to form carboxyllc acid-functionallzed reslns. It should be noted that thls partlcular procedure does not requlre that~the emulsion be coagulated prior to functionalizatlon; upon addition o~ the emulslon to the hydroxlde solutlon coagulation may occur, but as the ester llnkages are hydrolyzed any coagulum of the copolymer resin re-suspends. The carboxyllc acid-functionallzed resln produced by thls procedure ls ln the alkall metal ~orm, and may be converted to the free acld (hydrogen) form by contactlng lt wlth a conventional, strongly acldlc catlon resin ln the hydrogen form. Slmllarly, acryllc ester copolymer reslns may be hydrolyzed wlth strong ac~ds to produce carboxylic acld-~unctionallzed reslns in the hydrogen form, but ln this case the product is a coagulum rather than an emulslon.
Strongiy basic emulsion copolymer ion exchange reslns of this lnvention may be prepared~ for example, by chloromethylatlng coagulated particles of crosslinked styrene emulsion copolymer with chloromethyl methyl ether ln the presence of a Lewis acld such as aluminum chloride, and treating the resultlng lntermediate emulslon copolymer material with a tertiary amine such as trimethylamlne t~ ~orm a quaternary amlne chloride ~unctional group.
Alternatively~ a strongly basic quaternary amihe resin may be prepared by treating a croRslinked acryllc ester emulsion copolymer with a diamine containing both a I

tertiary amlne group and a primary or secondary amlne group, such as dimethylaminopropylamine or di(3-dimethylaminopropyl)amine, and quaternizing the resulting weakly basic resin with an alkyl halide such as methyl chloride.
Weakly basic emulsion copolymer lon exchange resins Or thi~ invention are prepared, for example, in the same manner described for strongly basic resins, except that for a styrene copolymer primary or secondary amlnes are emplo~ed instead of tertlary amlnes, and for an acryllc ester copolymer the resln is not quaternized with an alkyl hallde.
While the functlonalized coagulum particles possess ion exchange propertles, and are sufficiently cohesive that they may be used in conventlonal ion exchange processes in much th~e same manner as conventional resin beads, a preferred form for utillzing the materlals of this invention ls the re-suspended form. Re~suspension of the functionallzed coagulated particles may be achieved by the processes described above, i.e., by high-shear mixing, ultrasonic vibration, mild grinding, or other comminuting method whlch disrupts the coagulum without damaging the spherical resin particles. Spontaneous resuspension of the emulslon partlcles occurs during preparation of the strongly basic product from aromatic copolymers under some condltions, eliminating the nee~ for a commlnuting step~
It should be noted that the hydrophoblc nature of the unfunctlonalized emulslon copolymer partlcies encourages coagulatlon. Once ~unctionallzed the ion exchange resln partlcles are relatively hydrophlllc;
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they tend not to coagulate from emulslon form under the conditions suggested for the unfunctionallzed copolymer emulsionsO Photomicrographic and other physlcal evldence lndicates that the emulsions of the functionallzed ion exchange re~sin particles tend to contaln largely lndividual particles. On drying a sample of su~h an emulslon the partlcles may remaln as lndlvldual partlcles, or they may form small, loosely bound clusters of partlcles. These clusters may be disrupted by very mild force - rubblng between the flngers ls often sufficlent - ln contrast to the tightly bound nature of the coagula. m e loose clusters also tend to dlsperse spontaneously upon addltlon to water, to form emulslons of the lndivldual resln partlcles.
In general 3 the emulslo~ copolymer lon exchange resins of thls inventlon may be used ln any applicatlon where ground lon exchange reslns, produced by bulk or suspenslon polymerlzatlon, are used, but because of the special propertles of the reslns of this invention, they often prove superlor to ground reslns. In addltlon, these special properties permlt reslns of this inventlon to be used for a wlde varlety of appllcatlons where ground resins are unsultable.
Among the uses for the reslns of thls inventlon are those as orally admlnlstered medicines or medical treatments. These include the use of the weakly acidic resins in the calcium or magnesium form as gastric antacids, of the strongly acidic reslns ln the sodlum form ln treating hyperkalemia, of the strongly acidic resins in the calcium form or the strongly baslc reslns ln the chloride form ln treatlng hypercholesterolemla, and of the weakly acldic resins in the calcium form in treatlng gallstones. Further such uses are as drug - carriers and sustalned release agents for drugs and other materials; in this applicatlon and others an added advantage is the masking of ob~ectionable flavors or odors of the adsorbed materials. The reslns may further be us-ed ln the treatment of acute poisoning, such as by heavy metals, drugs, and the endotoxlns, exotoxlns, enterotoxlns and the like of mlcro-organisms. Other u~es ln the area of lnteinal medlclnelnclude removal of pyrogens ~rom materlals whlch would come into contact wlth the blood, removal of mlcro-organlsms from the stomach and lntestlnes~ and use as an lnJectable contrast medium for radiography.
Further uses of the resins of thls lnvention are ln the area of external medlslnes and medical treatments. These lnclude use as pH control agents, for the treatment of contact dermatltls caused by poison lvy or other agents, as antl-perspirants, deodorants, and skln mlcroblocldes, as antl-irritants either for thls property alone or whlle also servlng as a drug carrler, and ln the treatment of bltes or stlngs from lnsects, arachnlds, snakes and the llke.
Domestlc and industrlal uses of the resins of thls inventlon are ln the areas of flocculation, riltratlon and delonlzation. Comblnlng the strongly acldic resins ln the hydrogen form with the strongly basic reslns ln the hydroxyl form produces a floc which may be used as a flltratlon and deionizatlon medium for condensate water9 or as a flocculant and filtratlon ald for fermentation broths. The strongly basic or weakly basic resins may be used to remove free acids from .

~P~ 9~

edible oils and for decolorizing crude sugars and molasses. The strongly basic and weakly basic resins may be used to remove fulvic and humlc acids ~rom potable water, and to blnd and remove micro-organlsms from such water~ The floc formed by comblning weakly acidic and weakly baslc reslns may be used for deionization-of water, crude sugars and the like. The floc formed by combining strongly basic and strongly acidic resins may be used for demineralizatlon of process fluids, crude sugars, whey, and the llke.
Further uses for the resins of thls invention are as additives to paper and nonwoven textile materials.
They may be incorporated into disposable dlapers and sanitary napkins as deodorants and anti-bacterial agents. They also serve as dye acceptors for incorporation into paper, te~tiles and paints; in this appllcation they may alæo be blended into polymers prior to flber extrusion.
Further uses for the resins of this inventlon are as formulatlng aids for agricultural products. They may serve as controlled-release substrates for blologlcally active materlals, lncluding pesticides, fertilizers, growth hormones, minerals and the like, as suspenslon alds ~or pesticide formulations and simllar applications where thelr emulsifiabillty and ion exchange activity are desirable, and as pH control agents.
Still ~urther uses for the resins o~ this lnvention are in the area of catalysis and scavenging. They may serve as high-surface-area, heterogeneous acid or base catalysts, ~or example, in the conversion of cumene hydroperoxide to phenol and ~, !
~ . ., .~. .
!

r9~7 acetone, as an acld acceptor, for example, in the synthesis of ampicillin, and as a scavenger for products, by-products or metabolites to shlft reaction equlllbria toward completion. They may serve as enzyme actlvators, for example~ ln fructose conversion, and as substrates ~or immobilizlng enzymes. The dr~ resins may be used as deslccants for organic solvents.
Miæcellaneous uses for the reslns of this invention include use of the weakly acidic resins ln synthetic detergents as sequestering agents and replacements for phosphate builders; use, especially of the weakly acidlc reslns in the potassium for~, as tablet disintegrating agents; and use as extractants in hydrometallurgy, for the recovery of germanium, uranium, zinc and the llke. The small si~e of the reslns allows their use in ultrafiltratlon appllcatlons within the lumens of flne hollow fibers. They may be used RS ion exchangers or adsorbents rOr removing metals or metal porphyrins from petroleum reslduesO
They may be used as high-surface-area extractants for the puriflcation of organlc acids such as lactlc, citrlc~ tartaric and slmilar ~clds produced by fermentatlon. They may be used to remove proteins and amino acids ~rom the waste water of sugar refinerles, slaughter houses and the like~ and the resulting loaded reslns, because of their pleasant mouth feel and lack of taste, may be fed dlrectly to domestic animals such as cattle.
Sugar decolorization and clarlfication uslng emul~ion ion exchange resins of the present lnvention offers slgnlflcant advantages over conventlonal processes. Conventlonally raw sugar solutions are treated wlth regenerable adsorbents such as bone char, actlvated carbon, or conventional lon exchange resins. These adsorbents require chemical regenerants or heat for regeneration, and produce undesirably dllute sugar solutions. In most refineries several decolorization operations follow the clarification operations, often including a sulfur dioxlde bleach, addition of non-recoverable powdered carbon, or use of a rlocculatlng agent. The emulsion resins of the present lnventlon permlt a slngle-step decolorization and clarifi¢ation. When added to lmpure sugar solutlons they form coherent, fllterable flocs with the charged partlculate impurities usually present in such solutlons. Although the resin particles are incorporated into the floc, they retain their ion exchange functionallty, and therefore remove dissolved ionic impuritles and color-imparting impurities from the solutions. They further remove particulate and color-lmpar~ing impurities elther by co-preclpitation during the formatlon of the floc, or by retalning such impurlties durlng flltratlon of the floc-contalnlng solution. Yet another mechanlsm by whlch the flocs remove lmpurltles from the solutions ls adsorptlon onto the partlcles which comprlse the flocs; being extremely small, these particles contribute high surface area to the flocs~ By one or more of these mechanisms the emulslon lon exchange reslns of thls lnvention remove from the sugar solutions the lmpurlties which impart color and lack of clarity, and addltlonally salts and the precursors to the color lmpuritles. The flocs containing adsorbed and entralned impurities may be removed from the sugar solution by filtration, ~; ' flotatlon or other known processes. The sugars whlch may be treated include cane, corn, beet and other sugars. The excellent kinetlcs o~ these emulsion reslns, resulting from their fine partlcle size, allow them to act far more rapidly as lon exchangers than the conventlonal lon exchange resins heretofore employed, and the flocs -themselves have the added advantage o~
actlng as a fllter aid. The use of the emulslon reslns of thls invention for decolorizing and cl~rifylng sugar solutions is illustrated ln Example 27 below.
In those cases where lnsufflclent charged particulate lmpurities are present ln the impure sugar solutlon to incorporate all of the added emulsion resin lnto the floc, a separate flocculating agent may be added to the solution. Such flocculating agents lnclude both lonlc sur~ace-actlve agents havlng a charge opposite that of the emulsion resln, nonlonlc surface-actlve agents and ~lnely divided lon exchange materials having a charge opposite that of the emulsion resin. These ion exchange materlals may be ground conventional resins or emulsion reslns.
While the preferred emulsion resins for sugar decolorization and clarlflcation are anion exchange emulsion resins and the strongly basic anion exchange emulslon resins are most prererred, acidic, cation exchange emulsion resins may also be used to treat sugars, and especially to treat sucrose for the purpose of inverting it. Inversion, the process of hydrolyzing the 12-carbon sucrose to a mixture of the 6-carbon sugars, glucose and fructose, occurs in the presence of certain enzymes or of hydrogen ions.
Strongly acidic emulsion cation exchange resins may be . I
~.

~l~6~ 7 used to supply these hydrogen ions without lntroducing undeslrable soluble anions into the sugar. Following lnverslon the catlon exchan~e emulslon resln may be removed from the lnvert sugar æolution with a conventlonal flocculatlng agent or by addltlon of an anion exchange emulsion resln such as a stron~ly baslc emul~lon resln. When such an emulslon resin is used, lt tends to further clarlfy and decolorlze the sugar solutlon, and the floc whlch forms acts as a flltration ald. The advantage of ~uch a process over conventional treatment of sucrose solutlo~s in a bed of cation exchange resln beads ls that a more concentrated, hence more vlscous, solutlon may be treated wlth the emulslon resln than wlth the bead resins.
As noted above, combining a cationic emulsion copolymer resin wlth an anl~lc emulslon copolymer resln allows the oppositely charged partlcles of the two types of resins to lnteract and form a loose, electrostatically bound floc. The floc has excellent klnetic propertles for ion exchange because llqulds readily penetrate lt, and because the lndlvldual particles themselves are so small that they are readily penetrated. The floc ls readlly dlærupted by shear forces, but because the electrostatlc attractlon of the opposltely charged partlcles remains, the floc re-forms when the shear force ls removed. Becau3e of thls the floc may be pumped by conventional, llquid-handling pumps as though lt were a llquld. It may also be supported on relatlvely coarse, low-pressure-drop filter screens where the electroætatic attraction mlnimizes particle sloughage during use. In addltion to the delonlzation propertles, these flocs have ~ .
~...,,~.

~6~

excellent filtratlon properties, as shown by Example 25 below. The delonlzatlon and filtration properties of these flocs may be utlllzed simultaneously, as when removlng ions and particulate matter from steam generator condensate water. In such an appllcatlon the floc ls usually pre-coated onto the fllter cloth, filter screen; fllter leaf or other mechanlcal fllter means. The floc may be pre-formed by mixlng the catlonlc and anlonlc copolymer resln emulslons prlor to transferring lt to the filter ltself, or the floc may be prepared ln the liquid to be treated and ~lltered by addlng emulslons of the catlonlc and anlonlc emulslon copolymer reslns to the llquld. In thls latter case, entralnment of partlculate matter wlthin the floc as it forms may be an addltional advantage. The flocs descrlbed hereln may be prepa~ed by mixlng strongly acldlc emulsion copolymer reslns wlth strongly baslc or weakly baslc emulslon copolymer reslns and weakly acldic emulsion copolymer reslns with strongly basic or weakly baslc emulslon copolymer resins. They may be formed by mixing particles of one or more catlonlc emulslon resins wlth particles of one or more anlonic resins; weakly acldlc and strongly acidic emulsion reslns may be mixed~ as may weakly baslc and strongly baslc emulslon reslns, and these mlxtures may be used to form flocs. Emulslon resins havlng dlfferent particle sizes may be mlxed to form flocs, including a multipllclty of catlonlc emulslon reslns having different sizes, or a multipllclty of anionic emulslon resins havlng different sizes; such mlxtures are used to control the texture, and hence the filtering and other handling characteristics, of the flocs. The ., I

- 25a -formation of flocs i~ lllustrated in Examples 22 and 23 below.
Flocs prepared from weakly acidic and weakly basic emulsion reslnQ have the addltional useful property of being thermally regenerable. ~hat ls, the floc may be used to remove anions and cations from a relatively cold llquld,~~and these anlons and cations may be replaced with hydrogen and hydroxyl lons from a relatlvely hot aqueous llquid durlng regeneratlon.
Such flocs dlffer from conventional thermally regenerable reslns which are usually large, hard beads contalnlng areas of both acldlc and baslc functlonallty. Because the thermally regenerable floc can form a large, coherent mass, it may be used with moving-bed delonlzatlon equlpment. In such equlpment the floc ls coated on a movl~g fllter support whlch continuously transports the floc through a deloni~ation section, where it contacts the cold llquld being treated, and through a regeneratlon section, where lt contac~ a hot, aqueous regeneration llquld. It may similarly be used in contlnuous-delonlzatlon processes ln whlch the floc is clrculated by pump1ng through a delonlzation vessel and a regeneration vessel, the floc moving through the deionlzation vessel in a dlrectlon opposite to the flow of treated liquid. The thermal regenerability of the weak acld-weak base flow at two dlfferent pH values, and a comparison of lts thermal capaclty with that of a co~nventional thermally regenerable bead resin is illustrated ln Example 24 below.
In the formatlon o~ flocs upon mixlng cationic and anlonic emulsion resin materlals, a single partlcle ?~ I

establlshes an electrostatlc attraction for more than one partlcle of opposlte charge. Especlally where larger particles of one charge, as for lnstance partlcles between about 0.7 and about 1.5 micrometers ln diameter, are mlxed wlth rlne partlcles, as for instance those wlth diameters smaller than 0.1 mlcrometer, of the opposlte charge, many fine particles may cluster about the large partlcles. As a result the ratlo of catlonic emulsion resln to anionlc emul~lon re~ln in flOcs may be varied over a wlde range by ad~usting partlcle slzes. Flocs may be prepared with the cationic resin to anlonlc resln ratio ranglng from about 9:1 to about 1:9. Even ln the case of partlcles of opposlte charges havlng approxlmately the same dlameter the catlonlc resln to anlonic resln ratio may be varied over at least the range from about 3:~2 to about 2:3; thls is a preferred range, regardless of diameter. A more preferred ratio of cationic resln to anionic resin is about 1:1.
The emulslon copolymer ion exchange reslns of thls inventlon may be changed from one lonic form to another by contactlng them wlth conventlonal lon exchange resins, that ~s, wlth lon exchange resins having particle sizes of about 40 mlcrometers or larger, and preferably those reslns suited for use in conventlonal ion exchange beds. Particles o~ ion exchange resln having diameters of about 40 micrometer~ or greater are referred to herein as "macrobeads", regardless of whether they are spherical beads or of other geometric shapes. For example, an emulsion anion exchange resin prepared in the chloride form may be changed to the hydroxyl form by passing an emulsion of the resln !
.~ ' .

- 26a -through a conventlonal bed o~ strongly basic anlon exchange resin in the hydroxyl form. Chloride ions of the emulsion resin are exchanged for hydroxyl lons of the conventional large-bead resln as the emulslon resin passes through the column. Because the lons are exchanged by each resin, the lonlc form of the conventlonal re~ln ls also changed. This process may therefore be used to change the ionlc form of the emulsion resln to a desired form, or to change the resins of fixed beds to a deslred ionlc form, as in ion exchange bed regeneratlon. Indlvldual or mlxed emulsion reslns, and lndividual or mixed conventional resins, may be employed in this process. The emulsion resins are preferably of the same ion exchange type as the conventlonal reslns; "ion exchange type" as used herein meaning the ionic type of the lon exchange functional groups: either substantially cationic (acidic) or substantially anlonic (basic).
Ion exchange will occur between such resins both ln a batch process, where the exchange i8 allowed to reach equilibrlum, and in a column or bed process, where continuous equillbratlon produces a hlgh converslon to the deslred ionic form, ~ust as lt does in conventlonal treatment of ionized solutions with ion exchange beds. Thls process ls lllustrated ln Examples 8, 19 and 21, below.
The ~ollowing examples are intended to illustrate, and not to llmlt, the lnvention. All percentages used herein are by welght unless otherwlse speclfied, and all reagents are o~ good commercial quallty.

Thls example illustrates the preparation of a ~' ~ ~o styrene-divinylbenzene emulslon copolymer. A monomer emulslon i9 prepared by stlrrlng vlgorously under a nitrogen atmosphere 370 g of deoxygenated water, 48.2 g o~ Triton X-200 (trademark of Rohm and Haas Company, PhiladelphlaJ Pennsylvania, for the sodium salt of an alkyl aryl polyether sulfonate sur~ace-actlve agent contalning ?8% solids), 348.8 g of styrene and 5I.2 g of commercial-grade divinylbenzene (54.7%
divinylbenzene, balance essentially ethylvinylbenzene). An aqueous lnitiator solutlon is prepared by dissolving 2.0 g of potassium persulfate in 100 g o~ deoxygenated water, and 50 g Or the monomer 801ution iS added to the lnitiator solution. The mlxture ls stlrred to develop a l-inch vortex and is heated to 70C under the nitrogen atmosphere. When polymerlzation begins, as evidenced by a Rudden decrease in opaclty, the remalning monomer emulsion is added over a period of 1.5 hours. The temperature is held at 70C ~or one hour a~ter the addition is completed. The polymer emulsion ls cooled to room temperature and filtered through cheesecloth. The measured sollds content of the emulsion is 43.0%, - versus a calculated value of 45%.
Example 2 This example illustrates the brine coagulation of the polymer emulsion prepared ln Example 1. A 1400-ml quantity of 25% aqueous sodium chloride solutlon ls heated to 100C. While stirring the solution, 700 ml o~ the emulsion prepared in Example 1 are added at as rapid a rate as is posslble wi$hout the solution temperature ~alling below 95C. The solution temperature i~ held at 100-103C for 30 minutes, and - I

- 27a -the solld coagulum ls flltered out on a USA Standard Serles 150~m talternatlve deslgnation No. 100) sieve. The coagulum ls rinsed with water and drled overnlght at 100C; the yleld after drylng ls 292.1 g.
Example 3 This example illustrates the sulfurlc acld coagulation ~f the polymer emulsion prepared in Example 1. To 250 ml of stlrred, concentrated sulfuric acid, 41 ml of the polymer emulsion of Example 1 are added through a Pasteur plpette with lts tip beneath the sur~ace of the acld. The resultlng vermiform coagulum i8 about 1.5 mm ln diameter and 5-7 mm long.
Example 4 Thls example illustrates the sulfonatlon of the coagulum of Example 2 to form a strongly acldic cation exchange materlal. A 20-g ~uantity of the dry coagulum from Example 2 is mixed wlth 120 ml of concentrated sulfuric acid and heated under nitrogen atmosphere with stirrlng to 120C; lt is held at thls temperature for 5 hours. The reaction mixture ls allowed to cool, and water is added as rapidly as posslble without allowing the temperature to rise above 95C. The solid material is allowed to settle, and the supernatant liquid is removed. About 120 ml of water are added to the solid materlal and then removed. The solid material is transferred to a fllter tube, rlnsed with water and dralned; the yield is 103.8 g of material with 31.7%
solids, The cation exchange capacity of this materlal ls 5.22 milliequivalents per gram of the material in dry, H+ form, compared with 5.26 meq/g theoretical.
It should be noted that theoretlcal lon exchange capaclty and theoretical degree of functlonalization, ~ ' `

as used hereln, is ba~ed upon the assumption of one functional group per aromatic ring (styrene resins) or per monomer unit (acrylic reslns). Since this value may be exceeded under certaln cpnditions, measured values greater than "theoretical" may occur.
Example 5 Thls ex~mple lllustrateæ the chloromethylation and amlnolysis of the coagulum from Example 2. A 20-g sample of the dry coagulum from Example 2 ls ~welled in a mlxture of 17 ml Or chloromethyl methyl ether and 69 ml of propylene dichloride. Whlle stlrring this slurry a solution of 19 g of alumlnum chloride ln 25 ml of chloromethyl methyl ether ls added slowly wlth coollng, keeping the temperature at 32C or less throughout the addltion. The reaction mixture is held at 32C for 2 hours and then~ is cooled to 15C. Water is added dropwise with coollng, keeping the temperature to 30C or less. The aqueous layer ls decanted from the swollen organic layer and the product is washed twice with water, once with 4% aqueous sodium hydroxide solutlon, and once again wlth water. The solid product is filtered; its weight while still wet with propylene chloride is 105 g. A 15-g sample of this chloromethylated lntermediate is slurrled with water containlng 40 mg of 1200-molecular-weight poly(ethylenelmine). The mixture is heated and the propylene chlorlde strlpped out The mlxture i8 cooled and 9 ml of 25% trlmethylamine are added. The temperature of the mlxture ls raised to 70C, held constant for 5 hours, and raised to 95C to strip out the excess trlmethylamlne. The resultlng solid ls transferred to a filter tube~ rlnsed with water and ~. , ,"'`'; ' ~, . .

1 n~i~7 - 28a -dralned; the yield is 14.6 g of material with a sollds 1~ ..

: 2 5 content of 35.9~. The anion exchange capacity of this material is 3.64 meq/g of dry material in the chloride form. Microanalysis shows it to have the following composition:
C 67.1~
~ 8.49%
O 6.82%
N 4.82%
Cl 12.37%
13 (corre~te~ ~or O = ~zO) N = 3.7 meq/g.
Cl = 3.8 meq/g.
Example 6 This example illustrates the aminolysis of a vinylbenzyl chloride-divinylbenzene emulsion copolymer coagulum. An emulsion copolymer of vinylbenzyl chloride and divinylbenzene (commercial grade, containing 54.7%
divinylbenzene and the balance essentially ethylvinylbenzene) is prepared according to the procedure of Example 15 below; the copolymer contains 8%
divinylbenzene and has a measured solids conten~ of 29.6%. The emulsion copolymer is allowed to stand until it coagulates, and 50 9 of the coagulum are slurried with a solution of 0.15 9 of 1200-molecular weight poly(ethyleneimine3 in 100 ml of water. ~he slurry is heated to 60C, held at that temperature for one hour, and transferred to a pressure reactor. To the reactor 40 g of 40~ dimethylamine and 5.4 g of 50% aqueous sodium hydroxide solution are added. The mixture is stirred and heated to 60~C, held at that temperature for one hour, then heated to 87C and held at that temperature for hours. The reactor is cooled and purged with nitrogen and the reaction mix~ure is filtered. The solids are rinsed with water and drained; microanalysis of a small, dried sample of the solids shows the following ~.

5~?7 values:
C81.59%
H9.00%
O2.52%
N6.57%
(results are corrected for O = H2O).
N = 4.8 meq/g, as compared to a theoretical value of 5.3 meq/g.
Example 7 Thls example lllustrates the preparation of a methyl acrylate-divinylbenzene emulsion copolymer. A
dlsperslon of 24 g of Triton X-200 ln 360 g of deoxygenated water ls prepared under a nitrogen atmo phere ln a l-llter, round-bottomed flask, and is stirred to create a l-inch vortex. A mlxture of 29 g of divlnylbenzene (commerclal grade contalnlng 55.2%
dlvinylbenzene and the balance essentlally ethylvlnylbenzene) and 171 g of methylacrylate is added to the aqueous dispersion, followed by 4 ml of freshly prepared, 820 ppm ferrous ~ulfate solutlon and 50 ml of deoxygenated water containing 1.0 g of ammonlum persulfate solution. This mixture is stirred for about 15 mlnutes and cooled to 20C. A solution of 1.0 g of sodlum metablsulfite ln 20 ml of water and 5 drops of 70% t-butyl hydroperoxlde are added to the mlxture.
After a 5-minute lnduction perlod the temperature is observed to rlse to 80C durlng a perlod of 6 minutes, and thereafter to fall slowly. After 30 minutes, the mixture is cooled to room temperature and filtered 3 through cheesecloth. The solids content of the filtered emulsion i8 determined to be 31.0%, as compared to a theoretlcal value of 31.4~.

Example 8 Thls example lllustrates the hydrolysls and resuGpension o~ the methylacrylate-dlvinylbenzene copolymer Or Example 7 to produce a weak-acld-functionalized ion exchange resln emulslon. A 200-g sample of the emulslon produced in Example 7 is added to a stirred solutlon of 57.4 g of 50% aqueous sodlum hydroxide solutlon in 250 ml of water -- thls represents a 20% excess Or base -- and the emulslon ls observed to coagulate. Thls mlxture ls heated to 93C, held at that temperature ~or 2 hours, and cooled to room temperature. The coagulum ls observed to re-suspend ln the sodlum hydroxlde solutlon durlng the stlrrlng and heatlng perlod. The emulslon product is dlluted to 800-850 ml with water and ls passed through a column of "Amberlite IR-120" catlon exchange resln (trademark of Rohm and Haas Company, Phlladelphia, Pennsylvania, for a sulfonlc acid functionalized, styrene/divinylbenzene gel catlon exchange bead resin) in the H~ ~orm to remove the excess sodium hydroxlde and convert the product to the ~ree acld form. The sol~ds content of the resultlng emulslon ls 4.74%J and the weak acid cation exchange capaclty is 9.4 meq/g of dry polymer.
Example 9 ~ his example lllustrates resuspenslon o~ the functlonallzed emulslon copolymer coagula prepared in preceding examples. The runctionallzed coagulum ls trans~erred to a hlgh-speed blender container 3o (minibottle assembly of a "Waring Blendor"*, *Trademark ..;~.,.
j model 7011-31 BL 41) and ~ust covered with water. The blender ls operated at high or low speed for one-hal~
minute to twenty minutes, as required to re-suspend the emulslon.
Example 10 This example lllustrates the aminolysls and resuspension.of the emulsion copolymer coagulum prepared as descrlbed in Example 6. A 17-g sample of the coagulum 18 slurrled in 125 ml of water and 9.0 g of anhydrous trlmethylamlne are added. The temperature 18 observed to ri~e to 33C; the slurry is further heated to 65C, and the excess trimethylamlne is swept off with a nitrogen gas stream. The resultlng product, although very thick, is fully suspended. The solids content of the emulslon is 16.3%.
Example 11 The partlcle-slze distrlbution of a sample of the OH form of a strongly basic, emulslon copolymer ion exchange resln, prepared a~ descrlbed ln Examples 1, 2 and 5 by amlnatlng a chloromethylated styrene-7%
dlvlnylbenzene emulslon copolymer wlth trimethylamlne, ls measured by electron photomlcrography. The mean partlcle dlameter ls 147 nanometers (1 mlcrometer =
1000 nanometers~, approxlmately 76% of the partlcle diameters fall wlthln a 18-nanometer range, and approxlmately 95% of the partlcle dlameters fall withln a 33-nanometer range.
Example 12 The partlcle size dlstribution of a sample of weakly acldic, carboxylic acid functlonalized, acrylate emulsion copolymer lon exchange resin containlng 8%
divinylbenzene, ln the H form, prepared as described in Examples 7 and 8, is measured by electron photomlcrography. The mean particle diameter is 48 nanometers, approxlmately 84% of the particle dlameters fall withln a l9-nanometer range, and approximately 95% of the partIcle dlameters ~all wlthln a 29-nanometer range.
Example 13 Thls example lllustrates the preparatlon o~ a styrene-divinylbenzene emulsion copolymer havlng a partlcle slze larger than 0.5~ m by a process whlch lnvolves adding the monomer solutlon to a pre-formed copolymer emulslon for polymerlzation. A monomer emulslon is prepared by stlrrlng vigorously under a nitrogen atmosphere 180 g Or deoxygenated water, 14.3 g f Trlton X-200 377.8 g of styrene, 22.2 g of dlvlnylbenzene (54% dlvlnylbe~nzene, balance largely ethylvlnylbenzene) and o.8 g of ammonlum persulfate.
Vnder a nltrogen atmosphere ln a separate contalner 348 g of deoxygenated water ls stirred to develop a l-inch vortex and is heated to 95C. To this 13 g o~ a prevlously prepared emulsion copolymer is added, followed by 1.2 g of ammonlum persulfate. (The previously prepared emulsion.copolymer is a 3g divlnylbenzene-styrene emulslon copolymer containlng 43.3% sollds, previously prepared accordlng to the method of Example 1 and having a partlcle slze of approximately 0.1~m.) The mixture ls stirred for 30 seconds and the monomer emulsion prepared above ~s added dropwise during a 3.5-hour perlod; the temperature ls malntalned at about 90C. When the addition ls complete the temperature ls malntained at 90C for 30 mlnutes, after which 33.7 g of TRITON X-200 qs~

i~ added. The emulslon i3 cooled to room temperature and flltered through cheesecloth. The measured solids content is 36.5% ve~sus a calculated value of 42.4%.
Example 14 This example lllustrates the preparation of a styrene-dlvlnylbenzene emulslon copolymer of ~ine particle size; A monomer emulsion is prepared by stlrrlng vigorously under a nitrogen atmosphere 90 g of deoxygenated water, 2.73 g of Siponate DS-4 (trademark Or Alcolac, Inc. for the sodium 3alt o~ dodecylbenzene sulfonic acld), 123.5 g o~ styrene, 72.5 g of dlvlnylbenzene (55.2% dlvlnylbenzene, balance largely ethylvlnylbenzene) and 4.0 g Or glacial methacrylic acid. Under a nitrogen atmosphere in a separate contalner 350 g of water, 33.09 g of Slponate DS-4, and 1.0 g of potassium persulfate~are stirred and heated to 85C. The above monomer emulslon is added dropwise during a 3.5-hour period while the temperature is maintained at 85C. A solution o~ 0.4 g of ~otassium persulfate ln 75 ml of water is added and the mixture ls stirred at 85C for 2 hours. The product is cooled to room temperature and flltered through cheesecloth.
The measured sollds content is 26.0% versus a calculated value Or 27.0%.
Example 15 This example lllustrates the preparatlon of vlnylbenzyl chloride-divinylbenzene emulslon copolymer. A mixture o~ 1.0 g of potassium persulfate, 35.74 g Or Slponate DS-4 and 350 g Or deoxygenated water are stirred under a nltrogen atmosphere. A
mixture of 171 g Or vlnylbenzyl chlorlde and 29 g of dlvinylbenzene (55.2% divinylbenzene, balance largely 5~

ethylvinylbenzene) are added. This mixture ls cooled to 0-10C and swept with nltrogen for 2 hours. A
solutlon of 1.0 g of potassium persulfate ln 50 g of water ls added and the temperature is raised to 30~C
for 18 hours. A ~olutlon of 0.48 g of sodlum bicarbonate in 20 g of water is added and the temperature ls ralsed to 40C for 6-24 hours. The product i8 cooled to room temperature and ls flltered through cheesecloth. The measured solids content ls 29.6% versus a calculated value of 31.8%.
Example 16 This example illustrates the brine coagulation of the polymer emulsion prepared ln Example 7. A 40 g sample of polymer emulslon prepared in Example 7 ls added to lOO ml of a stirred solution of 25% sodium chloride ln water at 100C. ~he temperature is maintained for 2 mlnutes and cooled to 50C. The solid product is flltered and rinsed with water followed by methanol. The sollds content of the water-rinsed coagulum is 50%.
Example 17 Thls example illustrates the chloromethylation and aminolysls of the copolymer emulslon prepared ln Example 13. A sample of the copolymer emulslon prepared in Example 13 was coagulated and drled accordlng to the method of Example 2. A 44.4 g sample of dry coagulum is swelled ln 403 ml of propylene dichloride at room temperature for 1,5 hours. The slurry ls stirred and 80.5 ml of chloromethyl methyl ether ls added. The mixture ls cooled to 10C and a solution o~ 34.5 g of aluminum chlorlde in 42 ml of chloromethyl methyl ether is added dropwise over 20 - 35a -minutes whlle the temperature is malntained at 10C.
The stlrred mixture is held at 10C for 4 hours; it is subsequently added to 350 ml Or water with sufflcient cooling that the temperature never rises above 3CC.
The reaction mixture ls dilutea with 250 ml of water, stlrred for 30 minutes and the phases are permltted to separate. The aqueous phase is decanted and the organlc layer 1~ batch washed three tlmes with water, once wlth 4% sodlum hydroxlde solutlon, and twlce more wlth water. Approxlmately 25% of thls product, B0 ml of 25% aqueous trlmethylamine, 3 g of 50% sodlum hydroxlde solution and 120 ml of water are comblned and heated to 65C during a 3-hour perlod. The temperature ls then ralsed to about 75C and the propylene dlchlorlde-water azeotrope ls stripped out. The material ls cooled to 50~C and nitrogen is swept across the surface of the stirred product to remove excess trlmethylamine. The polymer emulslon product ls allowed to stand overnlght and ls decanted from any - small resldue of settled solid. The sollds content of the product i8 17%.
Example 18 Thls example illustrates the aminolysls of a chloromethylated styrene dlvlnylbenzene copolymer coagulum prepared as described in Example 5. A 20 g sample of a 7% dlvinylbenzene-styrene copolymer coagulum ~ I

. - 36 -prepared according to Example 2 is chloromethylated according to the procedure of Example 5. Approximately 20% of the propylene dichloride-swollen product, 100 ml of water, and 25 ml of 25~ aqueous trimethylamine are stirred at room temperature for the two hours and heated to 65C for five hours. The temperature is raised to 85C and the propylene dichloride and excess trimethylamine are stripped out. The aminolyzed product is a solid which is filtered and rinsed with water.
~
This example illustrates the conversion of a hydrolyzed and resuspended methyl acrylate-divinylbenzene emulsion copolymer from the salt form to the free acid form by batch treatment with a strong-acid ion exchange resin. A sample of 237.7 g (0.71 eq) of a methyl acrylate-divinylbenzene copolymer emulsion prepared according to Example 7 is hydrolyzed with 250 g of 12.5%
sodium hydroxide solution according to the prooedure of Example 8. The resulting thick, homogeneous product is slurried with 500 ml (0.9 eq) of Amberlite IR-120 ion exchange resin (product of the Rohm and ~aas Company, Philadelphia, Pennsylvania) in the ~+ form and rapidly becomes more fluid. . The beads of Amberlite IR-120 ion exchange resin are filtered and rinsed with water; the combined filtrate and rinses weigh 672 9 (9.17% solids, 97% of theory). Microanalysis shows the following results:
C=55.92%
~z6.18%
O=34OS4%
Na=144 ppm.
~?B~L
; This example illustra~es the amination of the emulsion polymer coagulum prepar~d in Example 16, A
sample of the coagulum prepared in Example 16 is dried at ...... .. . ... . . . . . .
. , ~ . ,. . . ,~ . ~

- ~7 -110C and 4 g of the dry solid is heated with 15 g of bis(3-dimethylaminopropyl3amine to 230C for two hours. The methanol produced is swept away with a stream of nitrogen. The reactlon mixture ls dlluted wlth methanol and the coagulum is flltered, rlnsed wlth methanol and with water, and drained. The solids content of the aminated product is 40% versus 50% for the water-rinsed starting material.
Example 21 This example illustrates the lon exchange and converslon of a strong-base-functionallzed copolymer emulæion prepared accordlng to Example 17 from the chloride form to the hydroxide form by means of column treatment with Amberlite IR-120 and Amberlite IRA-400 lon exchange reslns (products of Rohm and Haas Company, Philadelphia, Pa.), in the hydrogen and hydroxyl forms respectively. A 5 ml sample ~f a strong-base-functionallzed copolymer emulsion prepared according to Example 17 is passed through a column of 8.55 ml of Amberllte IR-120 ion exchange resin in the H~ at a rate of 0.5 bed volumes per hour; it is washed through the column with deionized water. The effluent is then passed through a column of 7 6 ml of Amberlite IRA-400 ion exchange resin in the OH at 0.5 bed volumes per hour and is similarly washed through the column with deionized water. A total of 13.1 ml of effluent iæ
collected. A 4 ml sample of this effluent is titrated to a pH = 7 endpoint with 4.35 ml of 0.1 N hydrochloric acid. A 0.5 g sample of effluent and .56 ml of 0.1 N
hydrochloric acid are evaporated to dryness, yielding 0.16~ g of a æolid material; 2.99% solidæ in the hydroxyl form is calculated. A titrable strong base "~ ~

capacity of 3.64 meq/g is calculated.
Example 22 Thls example illustrates the preparation of a floc from a strong-acid-functionalized copolymer emulsion and a stro~g-base-functionalized copolymer emulsion. A
sample of 11 ml of a 0.5%-solids suspension of a strong-base-r~nctionalized copolymer emulsion ln the hydroxide form, prepared according to Example 5, column treated wlth sodium hydroxide and resuspended as in Example 9, and a sample of 9 ml of a 0.5%-sollds strong-acid-functionalized copolymer emulsion prepared according to Example 4 and resuspended as in Example 9 are comblned and shakenO The result is a solid floc which settles, leaving a clear, supernatant liquid.
Example 23 This example illu~trates~the preparation of a floc from a weak-acid-functionalized copolymer emulslon and a weak-base-functlonallzed copolymer emulsion. A
sample of 5 ml of a 2.07% solids, weak-acld-functionallzed copolymer emulsion prepared accordlng toExample 8 and a sample of 2.5 ml of a 3.97% solids, weak-base-functionalized copolymer emulslon prepared accordlng to Example 6 are combined and shaken.
Deionized water is added and the product ls a solid ~loc which settles, leaving a hazy supernatant liquid.
Example 24 This example illustrates the thermal regenerabillty of the floc produced by combining weak acid and weak base emulsion resins. A floc is prepared according to Example 23, the quantity of weak base and weak acid resin emulsions belng selected to yleld 0.2 g of floc. This floc ls transferred to 16 ml of water, ;,,,~

and the pH is ad~usted to 5.6 by addition of dilute acid or base, as required, with rapid mixing. Sodlum chloride is added to the mixture until its concentration in the liquid phase is approximately 100 ppm, and the mlxture is allowed to equillbrate at room temperature. The speciflc resistance is determlned to be 7200 ohm-cm, equlvalent to 70 ppm ~odium chloride. The mixture ls heated to 92C while stlrrlng, and ls allowed to equlllbrate at that temperature. Stlrrlng ls stopped, the floc is allowed to settle whlle the temperature ls malntained, and a portlon of the supernatant llquid ls transferred to a conductlvlty cell. Thls sample ls allowed to cool to room temperature, and its specific reslstance ls determlned to be 4900 ohm-cm, equivalent to 102 ppm sodium chlorlde. The sample.of supern~tant llquid is returned to the total mlxture, whlch is then cooled to room temperature. The pH and speciflc reslstance are measured again, and are found to be equal to the initial, room temperature values.
Thls procedure is repeated using a second sample of the same floc, and agaln uslng a typical, thermally regenerable, hybrld lon exchange resin, the preparatlon of which ls descrlbed ln U.S. Patent 3,991,017. The 25 measurement results for these materlals are shown in the followlng table:
;

;~i ' I

, -. ~16~ 7 ~I JJ

~a ~ ~ qJ

.e .

u~ I`

~ Q~ o o s ~ . . tn m U
E V ~ t`~
, P~ Z--~

~P

~ J~ I

.~ ~ E~

; ~ o o S:

a~ ~Q o a~ o o ~ .C

a~ _ a~

U~ ~ r~ ~ ~ X

liil Q1 ~ V ~0 _I O ~n U ~o U~ 0 D A ~~

a~

~n .n ~ ' a~ ~ ~

.ri ~ V ~ ~ ~0 W ~ I ~ s.
E
S W o o C

0~ o o o ~,0 -- ~ ~ O

u~ ~; u~

U~ ~

.C _I

.. ~ ~

9) n 04 _i ~ ~ V

~ U~ -~

U~

This example illustrates the use of a strong acid-strong base floc for filtration of a finely divided, suspended material from water. A floc is prepared according to Example 22, the quantity of strong base and strong acid resin emulsions being selected to yield 79.5 mg of floc containing 47~ cation resin and 53% anion resin. This floc is transferred to a 1/2-inch (1.3 cm) diameter glass tube containing a 100-mesh nylon screen.
A room-temperature ~spen~ion of 300 ppb hema~i~e (yellow iron oxides) in water is allowed to pass through the tube at a flow rate of 3.7 gpm/ft2 (18 ml/minute absolute flow rate), at an inlet pressure of 25 psi ~1.70 atmospheres~. The pressure drop across the bed of floc 15 and the Silting Index of the effluent are monitored with time. The determination is stopped after 630 minutes, when the pressure drop approaches the 25-psi inlet pressure, although the floc is still filtering acceptably, as indirated by the Silting Index. The 0 results of this determination are shown in Table II below.
The Silting Index is a number determined using the Millipore Silting Index Apparatus (Millipore Catalogue No. XX6801300), and is based on the times required ~o deliver pre-determined volumes of liquid through a 0.45-micron Millipore filter. Silting Index is described in Federal Tes~ Me~hod 5350.

. .. . . . . . . .. ..
. . . .

J~

TAB
Time, Minutes~ ~L~ ea~ Silting Index 2 ~.7 0.7 0.9 1.53 1.0 1.~ _ 1.2 106 1.3 1.6~
160 1.4 0.81 208 1.~ 1.00 255 1~7 1.17 310 l.B 1.76 350 2.0 2.09 400 4.4 3.19 440 7.8 2.15 490 13.4 2.45 540 19.2 2.47 580 - 24.1 2.2~
630 ~4.7 2.20 .

_x2mple 26 This example illustrate~ the use of the strong acid-strong base floc for deionization. A floc was prepared according to Example 22, the ~uantities of strong base and strong acid resin emulsion being selected to yield 20Q mg of floc containing 40% cation and 60%
anion emulsion sesin. This floc was transferred to a 1/2-inch (1.3 cm) diameter glass tube containing a 100-mesh nylon screen. A solution containing 9.76 ppm NaCl calculated as CaCO3 was allowed to pass downward through the tube at a flow rate of 3.7 gpm/ft2 (18 ml/minute absolute flow rate) at room temperature, at an inlet pressure of 25 psi (1.70 atmosphere). The pressure drop across the bed and the specific resistance of the effluent are monitored. Breakthrough is defined as the poin~ at which the ef~luent resi ~civity declines to 4 . O
megohm-cm (approximately 1096 leakage). This break'chrough 5 occurs at about 23. 5 minutes, and is equivalent to a calculated capacity of 0.048 g Cl /9 dry anion resin.
The results of this determination are tabulated in Table III below:
T~.BLE III
Specific Resistance Time, MinutesPressure Drop, psime~ohm-cm 1 0 6.20 3 o 7.60 6 0 8.40 0 8.40 0 8.20 0 6.00 0 3.10 0 1.60 0 0.60 0 0.275 0 0.140 0 0.094 Exam~le 27 This example illustrates the decoloriza~ion of a washed, raw sugar solution using emulsion ion exchange resins. A 125-ml sample of washed, raw sugar solution, t~pical of that received at refineries, and having an ICUMSA color of 900 and a concentration of 65 Brix ~s hea~ed t~ 80C. To this is added 0.20 g, dry basis ~equivalent to 2000 parts resin per million parts sugar solids), of strongly bas;c anion exchan~e resin emulsion in the chloride form, made from the emulsion copolymer of ~ 5~

Example 1, coagulated accordin~ to ~xample 2, chlor inated and aminolyzed according to Example 17. The mixture is stirred for five minutes, and is then transferred to a pressure filter where it is filtered through diakomaceous earth supported on coarse filter paper. The sugar solution filters rapidly, and the filtrate is a clarified, decolorized solution with an ICUM5A color of 180.
Tne ICUMSA color determination by Revised ICUMSA
Method 4 is described in the Cane 5ugar Handbook, 10th Edition, published by John Wiley and Sons. This color determination is made at a wave length of 420 nanometers and a measured p~ of 7.0, and the result is extrapolated to a sugar concentration of 100%.
Example 28_ This example illustrates the suspension in an organic solvent of a floc prepared from cation and anion emulsion resins. A 9-ml sample of strongly acidic emulsion cation exchange resin, prepared according to Exæmple 4 and resuspended as a 0.5~ solids emulsion accor~ing to Example 9 is mixed with an ll-ml sample of strongly basic emulsion anion exchange resin, prepared according to Example 18, rinsed as a coagulum with 4%
aqueous sodium hydroxide solution to correct it to the 2~ hydroxyl form and resuspended as a 0.~% solid~ e~ulsion according to Example 9, to form a floc. The floc is transferred to a sintered glass filter funnel, allowed to drain, and rinsed with acetone to replace the water from the floc. The floc is observed to retain its flocculant 30 character in the non-aqueous, acetone medium. The floc is subse~uently dried, first in a stream of nitrogen and finally in an oven at 95~C. The dried floc is photographed using a scanning electron microscope, and is observed to have a microporous structure, that is, relatively large void spaces exist within the structure of cohered, emulsion resin beads.

, . . , , .. ~ , . .. ,.. . . ; . ,. . . ~. . . . .... .. ...... ...... .. . .

Claims (17)

1. A liquid cation exchange material comprising an emulsion of submicroscopic, approximately spherical beads of crosslinked copolymer having diameters within the range from about 0.01 to about 1.5 micrometers, and bearing from about 0.7 to about 1.5 cation exchange functional groups per monomer unit, the cation exchange functional groups being selected from the group consisting of strongly acidic functional groups and the free acid form of weakly acidic functional groups.

2. The liquid cation exchange material of Claim 1 wherein the cation exchange functional groups are strongly acidic functional groups.

3. The liquid cation exchange material of Claim 2 wherein the copolymer is an aromatic copolymer.

4. The liquid cation exchange material of Claim 3 wherein the copolymer is an styrene copolymer.

The liquid cation exchange material of Claim 4 wherein the styrene copolymer is a copolymer of styrene and divinylbenzene.

6. The liquid cation exchange material of claim wherein the cation exchange functional groups are the free acid form of weakly acidic functional groups.

7. The liquid cation exchange material of claim 6 wherein the copolymer is an acrylic copolymer.

8. A weakly acidic cation exchange composition derived from the liquid cation exchange material of Claim 6 comprising approximately spherical beads of crosslinked copolymer having diameters within the range from about 0.01 to about 1.5 micrometers and bearing from about 0.7 to about 1.5 weakly acidic cation exchange functional groups in the free acid form per monomer unit.

9. The liquid cation exchange material of Claim wherein the beads have a mean diameter of from about O.01 to about 0.5 micrometers.

10. A process for preparing submicroscopic cation exchange resin particles comprising approximately spherical beads of crosslinked copolymer having diameters within the range from about 0.01 to about 1.5 micrometers and bearing from about 0.7 to about 1.5 strongly acidic cation exchange functional groups per monomer unit, which process compxises the steps of:
a) emulsion polymerizing a mixture of a major amount of a monoethylenically unsaturated monomer and a minor amount of a polyethyl-enically unsaturated monomer to form an emulsion of crosslinked copolymer beads, b) adding the emulsion to a coagulant liquid to form coagulum particles of the copolymer beads, c) separating the coagulum particles, from the emulsion polymerization medium, and d) functionalizing the copolymer beads with strongly acidic cation exchange functional groups.

11. The process according to Claim l0 wherein the functionalized copolymer beads remain coagulated during functionalization, and are subsequently resuspended in a liquid medium to form an emulsion.

12. The process according to Claim 10 wherein the copolymer beads are functionalized with strongly acidic cation exchange functional groups by reacting them with concentrated sulfuric acid.

13. A process for preparing submicroscopic cation exchange resin particles comprising approximately spherical beads of crosslinked copolymer having diameters within the range from about 0.01 to about 1.5 micrometers and bearing from about 0.7 to about 1.5 weakly acidic cation exchange functional groups per monomer unit, the weakly acidic groups being in the free acid form, which process comprises the steps of:

a) emulsion polymerizing a major amount of an acrylic ester monomer and a minor amount of a polyethylenically unsaturated monomer to form an emulsion of crosslinked acrylic copolymer beads, and b) hydrolyzing the ester linkages of the acrylic copolymer beads with a strong acid to form carboxylic cation exchange functional groups in the free acid form, and to concurrently form a coagulum of the functionalized copolymer beads.

14. The process of Claim 13wherein the coagulum of the functionalized copolymer beads is resuspended to form an emulsion of the functionalized copolymer beads.

15. A process for preparing submicroscopic cation exchange resin particles comprising approximately spherical beads of crosslinked copolymer having diameters within the range from about 0.01 to about 1.5 micrometers and bearing from about 0.7 to about 1.5 weakly acidic cation exchange functional groups per monomer unit, the weakly acidic groups being in the free acid form, which process comprises the steps of:
a) emulsion polymerizing a major amount of an acrylic ester monomer and a minor amount of a polyethylenically unsaturated monomer to form an emulsion of crosslinked acrylic copolymer beads, b) hydrolyzing the ester linkages of the acrylic copolymer beads with an alkali hydroxide to form carboxylic cation exchange functional groups in the alkali salt form, and (c) contacting the emulsion of functionalized copolymer beads with strongly acidic cation exchange resin in the free acid form, to convert the functionalized emulsion copolymer beads in the emulsion to the free acid form.

16. A method for the removal of cationic impurities from a liquid containing such impurities which comprises contacting the liquid with an emulsion of submicroscopic, approximately spherical beads of crosslinked copolymer having diameters within the range from about 0.01 to about 1.5 micrometers, and bearing from about 0.7 to about 1.5 cation exchange functional groups per monomer unit.

17. The method of Claim 16 wherein the emulsion is removed from the liquid after removal of the impurities by adding a flocculating agent to the liquid to form a floc with the emulsion particles, and subsequently separating the floc from the liquid.