CA1041242A - Water-in-oil polymer dispersions with polymeric emulsifier - Google Patents

Abstract

Abstract of the Disclosure The Specification describes novel polymer dispersion comprising a dispersion in a continuous organic phase which is not completely miscible with water, of a fine particle size aqueous phase comprising a water-soluble high-molecular weight polymer dissolved in water or swelled with water, the disper-sion containing a water-soluble acid and a water-in-oil emulsifying agent sol-uble in the organic phase and comprising (a) a vinyl polymer of (i.) 10 to 50%
by weight of at least one vinyl monomer containing a basic nitrogen atom, (ii) 90 to 50% by weight of at least one vinyl monomer containing a side chain comprising an alkyl group of at least 6 carbon atoms, or a mixture of at least one such monomer with a minor amount of one or more further non-water-soluble.
vinyl monomers, and, if desired (b) one or more other surface-active compounds whereby the resulting HLB value of the complete emulsifying agent is below 6 at a pH value above 4, and above 8 at a pH value below 2. The above dispersions can be used to prepare aqueous solutions of the water-soluble polymer by admix-ing the dispersion with an excess of water, the acid in the dispersion serving to neutralise the basic nitrogen atoms of the vinyl polymer contained in the dispersion. Such dispersions render the polymer more quickly and completely soluble in water.

Description

The present invention relates to novel water-soluble polymer dispersions suitable for use in the preparation of aqueous solutions of such polymers.
Water~soluble polymers play an important role in indust-ry as si~ing agent, thickeners, flocculating-agents - etc. Aqeuous solutions of these polymers are highly viscous even at moderate concentrations and the polymers ., are therefore usually only manageable at low concentrations especiaily when they are of an extremely high molecular .~ .
weight. It is therefore not generally practical to mar~et these polymers in the form of solutions. In most cases, therefore they are dried to form soli.d produGts of fine particle size which have to be dissolved in water before use. In many cases the dissolution can only be carried 15 ~ out slowly, even with good stirring, especially when the dry product tends to form lumps in contact with water.
~ In order to avoid these disadvantages it already ; ~ has been suggested in U.S. Patent Specification No.
- 3,282,874 to suspend the water-soluble polymers in organic ~, ~ 20 liquids which are not miscible with water, and subsequently to mix the suspension with water, whilst stirring wellS
whereby the polymers are dissolved without the formation

2 - ~

of lumpsu In order to sta~ilise the suspension of the poly~er in the organic liquid sufficien~ly to provide a comparatively long storage time, an emulsifying agent of the "water in-oil" type is a~ded. However, it is a somewhat protracted working step to bring a stab.le dispersion and/or emulsion of this type into . ~
~ contact with an aqueous phase whereby the water-soluble ~ . .
polymers are dissolved. This applies particularly to dispersions of very fine-particle size. In German : . : -~ . lO Offenlegungsschrift 21 54 081 it is therefore suggested . ~ . .
' . to add to the aqueous phase an oil-in~water emulsifying I . ~ .
` 'agent whereby the dispersion of the water-solu~le polymer .
and/o~r the emulsion of the polymer solution in~the organic phàse.is reversed,~so that the polymer passes over into ~:': 15 : ~ the'aqueous phase and the originally continuous organic phase~is emulsified. In this way it is possible to convert '-a~water-soluble polymer~from an organic dispersion or .. . .
, , - .: . . - -':' ' . '- emulsion,'within a short time, into an aqueous solution;
- ' - ~ -' : however, the consumption of emùlsifying agents in this .
process is considerable. :`. ' :
.- .
~ - . . It is an object o the~present lnvent;on to provide .. . - ~

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new and advantageous dispersions of concentrated aqueous solutions of water-soluble polymers in an organic phase, which may readily be converted into dilute aqueous solutions of the polymers within a short time and without ex-cess usage of chemicals which may excessively pollute waste water.
;~: According to one feature of the present invention we provide poly-mer dispersions comprising a dispersion in a continuous organic phase which is not completely miscible with water, of a fine particle size aquPous phase . ~
comprising a water-soluble high-molecular weight polymer dissolved in water or swelled with water, the dispersion containing a water-soluble acid and a ` 10 water-in-oil emulsifying agent soluble in the organic phase which comprises .. ~a) a vinyl polymer of ti) 10 to 50% by weight of at least one vinyl monomer containing a basic ; ~ nitrogen atom, ; : ~ii) 90 to 50~ by weight of at least one non-water-soluble ester of :` acrylic or methacrylic acid with an alkanol containing 6 or more carbon atoms, :
or a mixture of at least one such ester with a minor amount of one or more further non-water-soluble, vinyl monomers; or a mixture of the said vinyl polymer ~a) with (b) one or more other surface-active compounds whereby the resulting HLB value of the complete emulsifying agent is below 6 at a pH
value above 4 and above 8 at a pH value below 2 ~ ~ According to a further feature of the present invention we provide : a process for the preparation of the dispersions as hereinbefore described ,: ~
: which comprises finely dispersing in a contimlous organic phase which is not completely miscible with water, an aqueous solution of at least one monomer : capable of forming a water-soluble polymer, and polymerising the said monomer in the presence of a radical-forming polymerisation initiator which is soluble : in wateT or in the organic phase~ and in the presence of a water-soluble acid and a water-in oil emulsifying agent soluble in the organic phase which com-prises ~a) a vinyl pclymer of ti) 10 to 50% b~ weight of at least one vinyl monomer containing a basic ` ' .

Z~2 nitrogen atom, (ii) 90 to 50% by wei~ht of at least one non-water-soluble ester of acrylic or methacrylic acid with an alkanol containing 6 or more carbon atoms, or a mixture of a~ least one such ester with a minor amount of one or more further non-water-soluble, vinyl monomers; or a mixture of the said vinyl polymer (a) with (b) one or more other surface-active compounds, whereby the resulting HLB value of the complete emulsifying agent is below 6 at a pH
value above 4 and above 8 at a pH value below 2.
The above-described dispersions are generally stable during storage over a quite long period. Surprisingl~, the stability of the suspension is not adversely influenced by the presence of the acid. Also the dispersions are so viscous that they dn not usually form a deposit, but can be conveyed as they are through pipes. In the above dispersions the aqueous phase will generally have a pH of above 4. As the dispersion contains an acidic aqueous phase, the emulsifying agent is converted from a water-in-oil type into an oil-in-water type in consequence of salt formation. The HLB value thereby rises to above 8, the dispersion becomes unstable and reversal takes place whereby the previously dispersed particles of the polymer phase pass over into the continuous aqueous phase and the previously continuous oil phase is sus-; 2Q pended or emulsified. The higher the water content of the polymer phase inthe dispersion the faster is the rate of uniform dissolution of the water-soluble polymer in the aqueous phase. It is most advantageous to disperse the organic dispersion in a sufficient amount of water, whilst stirring.
The invention enables water-soluble polymers of almost any type to be converted into aqueous solutions including non-ionic polymers such as e.g.
polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, poly-(hydroxyalk~
acrylate or -methacrylateJ water-soluble mixed polymers of the corresponding monomer components with one another or with limited amounts of non-water-sol-uble monomers, as well as cellulose ethers, etc~ It is also possible to bring :

~g~ 2 salt-like polymers into solutions in accordance with the invention, i.a. not only those of the cationic type such as poly(methacryloxy-ethyl)~trimethyl-ammonium chloride, but also those of the anionic type such as sodium salts of polyvinylsulphonic acid or polystyrene- --sulphonic acid. Salt-like polymers of this kind exist in the entire pH range in the form of salts, and on alteration of the pH value they do not undergo any change of their state of solution. On the other hand there are other polymers which only exist in the salt form at particular pH values~ e.g. polyacrylic acid~ which forms salts in ~0 the alkal;ne range. In this case the nitrogen atoms of the emulsify-ing vinyl polymer must be comparatively strongly basic so that the vinyl poly~r passes over into the corresponding salt form without the suspended polymer salt developing a strong buffer effect. A
;` limited buffer effect of the polymer can be compensated for by addi-tion of an amount of acid larger than that corresponding to the equivalent of the nitrogen groups of the emulsifying agent. If the polymer phase contains a partly-neutralised polymer i.e. one having : .
carboxyl and carboxylate groups~ then a reduced buffer effect of the polymer phase occurs.
i 20 Examples of polymers which only form salts in the acid range include: poly-~dimethylaminoethyl)-acrylate and -methacrylate.
Polymers of this type likewise exercise a buffer effect, i.e. they require more than the acid equi~alent which corresponds to that of the nitrogen groups of the emulsifying agent, in order to bring the ; HLB value into the range for the oil-in-water emulsions.
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It is true that the salts of these polymers react in an acid manner; however they obviously effect no conversion of the e~ulsifier into the oil~in-water type~
since a stable water in-oil dispersion is initially obtained. Apparent'y neutralisation reactions between the acid polymer phase and the surrounding emulsifier remain limited to the interface hetween the phases~ and ~- do not involve the bulk of the emulsify ng a~en~. Forthis reason it is also possible that the acid necessary :`
~or convertirg the emulsifying agent into the oil-in-water type may be contained, to a considerable extent, and in ` many cases exclusively in the polymer phase, even when it is not ~ound to the polymer.
;~ .
~e conce~2trat70~ of ~2e pDl~?e~ i~ the dispersed 15~ aqueous phase is preferably as hi~h as possible e.g.
~ S0 - 60% by weight. Generally these "solutions" do not - ~ form liquid droplets, but rather more or less solid swollen gel particles.
~ Low-viscosity oils are preferred as the organic phase - 20 ~ of the dispersions according to the invention9 since they provide a good dispersion of the suspended particles.
The di~ferent in density between the aqueous polymer phase - . ~

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z~z and the oil phase should preferably be as small as possible in order to ensure high stability for the dispersion.
~ils of high density are therefore pre erred. The densi~y of the oil phase can be increased by the addition of chlorohydrocarbons. Advantageously, the proportion of oil in the dispersion is kept as low as possible, e.g.
a propo'tion of 15 to 20% by volume of the total dispersion.
The proportion of tne aqueous polymer phase, accordingly, ~ can lie above the range of the "closest packing of spheres"
iO (74% by volume for the disperse phase). This is possible in that the dispersed droplets are of different sizes and :
car be defornled into non-spherical-shaped particles.
Of course, ~he ~iscosity of such a dispersion is high, for exampie about 1000 cP. If one uses oils of medium or ~ ~ .
high viscosity as the continuous phase, then the viscosity of the dispersion reaches very much higher values in as much as one does not considerably increase the proportion of , the oil phase At the same time the oil phase also is rendered more viscous by the emulsifier dissolved therein.
The thickening increases the stability of the dispersion but it should be kept within practical limits in order to ~ ~

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ensure the workability of the dispersion. Viscosities - of 1000 - 20,00~ cP are generally the most favourable.
The content of water-soluble polymers in the dispersion may exceed 50% by weight, if the polymer - 5 phase e.g. is 70% and the volume of the organic phase is restricted to a min;mum.
.
The easy reversibility of the dispersions according to the invention rests upon the pH-dependent en~ulsifying action Gf the emulsifying agent used. According to the ;nvention this emulsifying agent consists of a vinyl polymer of monomers witll a basic nitrogen atoms, and monomers with higher alkyl side~groups. In addition there can also optionally be used in minor amounts, a further surface-active compound, provided i-t does not result in the HLB value . ~: .
of the complete emulsifying agent being outside the specified range. The e~ lsifying action of the mentioned polymers depends upon the hydrophilic properties of the basic groups ` and the hydrophobic properties of the higher alkyl groups.
': :
- As is known, emulsifying agents with a predomin~nt hydrophobic portion belong to the water-in-oil emulsifiers~
wheress those with a predominant hydrophilic portion are oil-in~water emusifiers. The balance of the different

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components of the emulsifying agent is indicated quantitat~vely by the so-called "~liLB value" (HLB =
"Hydrophile Lipophile Balance"~ (The Atlas HLB-System, 4th Ed., 1963). Water-in-oil emulsifiers have HLB
values below 10, whereas oil-in-water emulsi.fiers have HLB values above ]0. The emulsifying agents contai.ned in the dispersions according to the invention are so composed that their hydrophiiic portion is only slightly active in the slightly acid, neutral, or alkaline range, w~lile its effectiveness strongly in~reases in the strongly acid range. This transition depends upon the salt formation of the basic nitrogen atom in the strongly acid range.
~ .
Vinyl monomers with basic nitrogen atom which can ; 15 ~ ~ be employed in the constitution of the emulsifying vinyl polymer include e.g. vinylpyridine, vinylimidazole and dialkylaminoalkyl esters or amides of acrylic or methacrylic acid~ e.g. dimethylaminoethyl acrylate or methacrylate, diethylaminopropyl acrylamide or -methacrylamide.
;~ 20 B Hydrophnbic components of the mulsifying agents are pLe~-esters of acrylic or methacrylic acid with alkanols containing six or more carbon atoms, such as hexanol, I ~ .

2g~2 ~:

octanol, decanol, or of commercial alcohol mixtures ; ~ e.g. tha~ mark?ted under the name "Lorol~. In additionto esters of this type 5 it is also possible to ~se therewith less hydrophobic co monomers such as e.g. styrene and ~' lower esters of acrylic or methacrylic acid. The proportion ~ by weight of the monomers with basic groups to the monomers -with higher alkyl groups is in each case so determined that the ~LB value in the non-neutralised condition lies below 6, preferably below 5, and, after conv~rsion of the `- 10 basic nitrogen atoms intc the salt forms above 8, in .
particular in the range of 10 to 15. This property '~ ' can~be achieved by the use of 10 to 50% by weig~lt, in~articular 20 to 30% by weight, of monomers with basic nitrogen atoms.~
15~ The~molecular weight of the emulsifying mixed . ~, . . .
polymer should advantageously be above lO,OOO in order 'to~p'rovide a good emulsifying effect. In order not to - , . .... . . . .
;~ thicken~unnecessarily the organic phase in which it is ~ dissolved, the molecular weight of the polymer is - ~ 20 preferably set so that the organic ~phase does not exceed ~ - :
~ ' a viscosity of 20~000 cP. The proportion of the polymers' .
~in the organic phase may~lie between 2~and 20% by weight~
- it being~appreciated the molecul~r weight of the polymer ~: f~,~J~ ~ /c ~ : :
~:

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may be the higher~ the lower its proportion.
The size of the suspended droplets of the aqueous phase is very substantially de2endent upon the type of the polymerisation initiator employed. If a water~soluble ir.itiator, such as e.g. potassium persulphate, is dissolved in the aqueous monomer phase, the polymerisation takes place in the droplets of the monoiner phase itself, and the suspended particles substantially retain the shape and size of the original droplets. The size of the droplets, ~nd therefore also of the final polymer phase particles, is determined by the amount of the emulsifying agent.
With an emulsifying agent content of 5 to 20%, based on `the we~ght of the monomer phase, particles are formed in the particularly adv~ntageous size range of 10 to 500 ~m.
By reduction of the en~ulsifier content, the particle size can be increased to lmm or greater.
; ~ ; If one uses a polymerisation initiator which is -soluble in the oil phase, e.g. 2,2'-azcbis-(ethylisobutyrate), then substantially finer particles may be formed, e.g.
having a part~cle size below 10~m. These systems are also designdted as organic dispersions. Their behaviour ., . . .
~i upon dissolution in water, with conversion o~ the water-in--oil emulsifier into an oil-in-water emulsifier, corresponds to the suspensions described above.
The dispersions according to the invention may be prepared for example by first dissolving the emulsifying agent in the oil phase and/or producing the emulsifying agent in situ by polymerisa-tion~ dispersing in the oil phase a concentrated aqueous monomer solution and then bringing the mixture to the polymerisa~ion temper-; ature. Depending upon the particle size desired, the initiator is contained in the monomer phase or in the oil phase. The acid neces-sary for conrerting the emulsifying agent may be present in the organic phase and/or in the polymer phase. If desired, a part of the water introduced with the monomer solution may be distilled off.
The obtained product is usuaIly ver~ stable upon storage.
When it is to be used~ the dispersion is for example run into a large mixing vessel filled with water. The oil phase emulsi-fied in the aqueous polymer solution has no harmful effects in many ~ applications and consequently need not be separated for such uses.
`~ In many cases the oil phase separates when the aqueous polymer solu-tion is left standing, and then it can easily be decanted off. In other cases it is possible to remove the organic phase by extraction with chlorohydrocarbons or to bind it with absorption agents.
` The quantity of acid added to the dispersion is so regula-; ted that it can convert the nitrogen-containing groups of the emulsi-~; fying agent into the salt form and thereby convert the emulsifying agent into an oil-in_water emulsifier. The acid quantity therefore should be at least approximately equivalent to the nitrogen groups of the emulsifying agent. GeneraIly an excess of the acid is not harmful.

j ,.~;, ~z The acid-containing polymer dispersions are conveniently produced in such manner that the acid, or at least a substantial part of the acid is added to the suspension, after the polymerisation has been substantiaIly concluded. In many cases a thickening effect is observed, which indicates that the acid is at least partially react-ing with the emulsifying agent. Since this thickening effect does not occur with all acids, probably also the nature of the acid has an influence upon the change of state of the emulsifier. However~
the emulsifying agent is nonetheless effective as a water-in~oil emulsifier. At any rate, it is, at the latest~ during the dissolu- -tion in water that the con~ersion into an oil-in-water emulsifier is achieved.
As acid additive there can be ussd practically any water-soluble inorganic or organic acid~ such cLS e.g. hydrochloric aeids, sulphuric acid, phosphoric acid, p-toluenesulphonic acid~ diphenyl-phospinic acid, acetic acid, chloroacetic acid, etc. Of these aeids, j:
; the inorganie aeids usually provide a good thickening effect which , may be desirable in the in~erests of improving the storage stab;l;ty .. . .
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of the polymer dispersion. If however the dispersion already has a high viscosity ~ithout any acid addition particularly when there is a high proportion of the polymer phase, then a further increase of the viscosity by the ;~ 5 addition of acid is undesirable since the tLanSpOrt and- measuring out of the suspension, and its dispersion in -~ water when dissolving, are thereby rendered more dlfficult~
In these cases, water-soluble organic acids are preferred since they provide a relatively si.lall increase in viscosity or none at all. Such acids include in particular orgAnic carboxylic acids, especially those with not more than 4 C-atoms, such as formic acid, acetic acid) propionic acid, isobutyric acid, chloroacetic acid, glycolic acid, acrylic acid, methacrylic acid, maleic~acid, fumaric acid;
-15 -as well as organic sulphonic acids such as ben2ene-sulphonic -~acids or~p-toluenesulphonic acid, and also organic phosphonic .
and phosphinic acids, for exa~ple diphenylphosphinic acid.
:
-These acids may be dissolved or emulsified in the organic phase of the polymer suspenslons according to the invention.
Basically, therei-ore those organic water-soluble acids are preferred wherein at least the necessary quantity is ~ . - . ' ~ : - .
~ ~ soluble in the~organic phase.

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z As indicated above, the acid, or a part thereof, may also be contained in the polymer phase. In this case, the acid in the organic phase should be as little soluble as possible, such as e.g.
inorganic mineral acids such as hydrochloric acid~ sulphuric acid, ammonium hydrogen sulphate or phosphoric acid. Preferably this acid is added to the aqueous monomer solution during the preparation of the polymer phase. In this form, the acid exercises no thickening effect. Preferably, only a part of the necessary quantity of acid, for example 5 to 50~ is contained in the polymer phase~ and the re-maining part contained in the organic phase.
The invention is of particular importance for the prepar-ation of solutions of water-soluble polymers of extremely high molecular weight. Whereas polymers of lower molecular weight, e.g.
up to about 50,000 such as are used for example as sizing agents, ~ ;
are still capable of flowing at polymer contents of 10 to 30% by weight, polymers with molecular weights of over 1 million, prefer-ably over 5 million are used, as flocculating agents or sedimentation-assisting agents. Even 5% solutions of these latter polymers are not capable of flowing, so that one must prepare aqueous supply-solutions of aboùt 1% dry content. Dispersions of water-soluble polymers ~o with molecular we7gnts of over 1 million there~ore represent a preferred embodiment of thP present invention.
The dispersions according to the invention rllay, if desired, contain conventional additives such as dyestuffs,

- 5 perfumes, disinfectants etc.
Instead of mineral oils, iOeO aliphatic, aromatic or mixed aromatic-aliphatic hydrocarbons~ or chlorohydrocarbons, the organic phase may comprise other OIganiC iiquidswhich are non-~niscible, or at least not completely miscible, with water, and which are not solvents for the dispersed polymers ~nd which are preferably also not solvents for the monomers ~onstituting the polymers.
;; The polymer phase does not need to be prepared in every case in the presence of the orga~;c phase and the ~; 15 emulsifying agent:. It may have been produced by pol~nerisation .
in aqueous or aqueous--alcoholic solution, or in acetone-water mixtures, optionally even in the absence of water.
.
It is thereby possible to use monomers which would otherwise dissolve in the organic phase. The polymer solution can then be dispersed in the emulsifier-containing organic phase s~nd water and,~or organic solven~ can be at least - part;ially distilled-off again.
_ ~q .

z -- The copolymers used as emulsifying agents may be produced directly in the oil phase by copolymerisation in which case ihey are produced in the form of statistical copolymers. However, it is also possible to use other known polymerisation processes wherein the hydrophilic and hydrophobic monomer units are arranged in differen~
blocks of a blocli or graft polymer. The copolymers are sufficiently active not only in the suspension polymerisation ~ of the aqueous monomer solution, but also in the storing of the suspension polymer over quite long periods of time, and also for emulsifying the oil phase after the reversal .
`~ of the suspension9 so that there is no need for the addition of further-s~face-active substances. 4 If hcwever further surface~-active substances are co-used, ~ then they must either undergo the same change of HLB valuet during acidification as the macromolecular dispersing agents, or they must be used only in such a quantity - that the HLB ~alue of the total emulsifying agent changes f-rom a value of less than 6 to a value of more than 8 at the pH-value displacement of from more than 4 to less than 2.

:
Generally lt is of no irnpo~tance which acid is used for the acidification ?rovided that it is sufficiently strong to raise the HLB value of the emulsifying agent to more than 8. In some cases this point already can be ~.
. .5 reached at a pH value over 2. Apart from the already-: named mineral acids thereore numerous inorganic and organic acids or acid salts are suitable for reversal of the ~ - suspension including for example~ hydrobromic acid, -.: ` perchloric acid, formic ecid, VaLioUS ~hloroacetic acids, .. 10 p-toluenesulphonic acid and ammonium hydrogen sulphate.
``~ . . Other possible variants within the scope of the -~ - invention will be evident to the expert in the art.
- This also a~plies with regard to the use of the dispersions and/or the~:solutions obtainable thererom extending to all -.:fields wherein one uses aqueous, in particular acidic`
queous. polymer solutions. It should be mentioned ` .
that~in many cases the acid polymer solution, after reversal.
- of.the~dispersionj can be neutralised again and can be :: .
~: freed from the thereby if necessary precipitated out .
~ 20 emulsifying agent, by filtering.
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The following Examples illustrate the present invention.
Example l A) Preparation of the emulsifier :
; S ~ 180 parts of paraffin oil 3.0 cSt/100 C(Isopar M~ofHumble Oil and Rerining Comp.) are placed in a reaction ~vessel with reflux cooler and stirring mechanism, and are heat~d to ~0 C. The following monomer mixture i5 allowed to flo~ into the oil over a period of 4 hours :
;:
260 parts of alkyl methacrylate with 12-18 (average 15) C-atoms in the alkyl group, 34 parts methyl methacrylate, 126 parts 2-dimeth~1aminoethylmethacrylate.
42 parts 2,2'~azobis(ethylisobutyrate).
15~ After completion of the introduction3 the mixture is stirred for a further 12 hours at 80C~ and subsequently heated to 100C for a further period of l hour. A highly-. - ~
~iscous solution is produced, with a polymer content of 70%.
B) Preparation of the dispersion :
110 parts of m;neral oil 1.15 cSt/100C (Shell Oil 1022) are placed in a reaction vessel with reflux cooler and stirring mechanism9 and are mixed with 40 parts of the :
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emulsifier solution obtained according to (A). To the organic phase, heated to 70C, the following aqueous phase is measured in over a period of 1~5 hours:
84 parts acrylamide, 196 parts 2-methacryloxyethyl-trimethyl-ammonium chloride, - - :
120 parts water3 ; Q~7 part~s Na-salt of 4,4'-azobis(4-cyanovaleric acid).
, ~
~ ~ -After completion of the introduction, the temperature . :
rises briefly to 90Ç; the mixture is stirred for a further 2 hours at 80C. The vissosiCy of the stabl~ milky dispersion is 6100 cP (Brookfield, Spindle III/6 rpm, 20C?
C) ` Conversion into aqueoùs solutionO
1.96 parts oL the dispersion obtained according to (B) are stirred for a short time in 98.04 parts of distilled ~ ~~waCer. Then 0.8 parts of 1% sulphuric acid are added dropwise,;and stirring is continued. The dispersed ~-pol~mer dissolves after a few minutes and forms a one-- percen~aqueous solution with a viscosity of 6800 cP
(Brookfield~Spindle IIl/6 rpm,~ 20C). ~ ~
~ 20 _ xample 2 ~ - A) Preparation of the emulsifier.

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180 parts of mineral oil 3.9 cSt/100 C (Schindler oil AFl) are placed in a reaction vessel with reflux cooler and stirring mechanism, and are heated to 80C. After ~:~ the addition of 2.1 ~arts of 2,2'-azobis(ethylisobutyrate) :
. 5 the following monomer mixture is allowed to flow into he oil over a period of 4 hours;
260 parts alkyl methacrylate with 12-18 (average 15) C-atoms in the alkyl group~
34 parts methyl methacrylate, 126 parts 2-dimethylaminoethylme~h~acrylate, 2 parts tert.-dodecylmercaptan, .
18.9 parts 2~2'-azobis(ethylisobutyrate), : After completion of the introduction, the mixture is stirred for a further 12 hours at 80C. A highly :.

~ viscous solution with a polymer content or 70% is obtained.

: B) ~ Preparation o~ the dispersion.

176 parts of mineral oil 3~9 cSt/100C(Schindler oil AFl) are pl~ced in a reaction vessel with re1ux cooler and stirring mechani.sm, and are mixed with 40 parts of the above emulsifier solution(A).: The following aqueous - phase i.s me.asured into the organic phase, which has been - heated to 70C9 over a period or 1 hour;
~ ~ .

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: ' ' ~: ' ; 140 parts acryl~nide, 140 parts 2-trimethylaMMoniumethylmethacrylate chloride, 120 parts water, 0.7 parts Na-salt of 4~4'-azobis(4-cyanoval2ric acid).
S After the end of the introduction, the tempera~ure -~ rises briefly to 80C. After stirring for a further 2 hours at 80C, the polym~risation mixture is cooled.
The viscosity of the stable milky dispersion amounts to 1100 cP (Brookfield, Spindle II/6 rpm 20C).
C) Conversion into the a~ueous so]ution.
2.2 parts of the above dispersion (B) are s irred for a short time in 97.8 parts of distilled water. Then 0.~ parts of 1% sulphuric acid are added thereto dropwise and stirring :~ .
is continued. After a few minutes, a 1% aqueous solution is produced, with a viscosity of 4000 cP (Brookfield, Spindle III/6 rpm/20C).

Examples 3 - 5 .., ~ . :
A. ~
. ~ ..
;180 parts paraffin oil (3.0 cSt/100C; trade product ~ Isopar M~ Humble Oil and Refining COM~. ) are placed in a ;,- reaction vess~l with reflux cooler and stirring mechanism9 and heated to 80C. The follow;ng monomer mixture is ~, ,'' ~

~A Je ~A~k , .

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: allowed to flow into the oil within a period of 4 hours;
~: ~ 260 parts alky1. methac~ylate with 12-18 (average 15) C-atoms `: in the alkyl ~roup, 34 parts methyl metnacrylate, 126 parts 2-dimethylaminoethylmethacrylate, ; . 42 parts 2,2'-azobis(ethylisobutyrate).
After the end of the introduction, the mixture is , ~
i~ stirred for a further 12 hours at 80C, and subsequently .~ ~ is heated for a further 1 hour tc 100C. A hi.ghly .. I0 vi~cous solution is produced, with a polymer content . : of 70%~ ~ ~
B~: Preparatlon of the dispersions .3)~ To 17 parts of mineral oil (trade product Shell oil 10223 and 4.7 parts (calculated as pure polymerj of the ~15 : ëmulsifying agent:prepared according to A)~ the following mo~omer mixture is added, with strong:stirring, within a period of one hour at 80C:; :~
.
- - . - -:~ 38.:3 parts water 12.0 parts 2-methacryloxyethyl-trimethyla~nonium chloride 28.0 parts acryl~mi.de - 0~0012 parts 4,4'-aæobis(4-cyanovaleric acid3c ~, ~6~ Z~Z
`
The monomer mixture is adjusted with sulphuric acid to pH 2. Three hours after conclusion of the monomer introduction 0-53 parts of acetic acid are added to the mixture which is still warm and the mixture is allowed to cool. The organosol obtained has a viscosity of 12,000 cP. When stirred illtO water it dissolves immediately and fo~r- e.g. a 1% solution of 3,000 cP.
4) The oper~tion is carried out as in Example 1, but the monomer solution is adjusted to pH 4.2. The organosol produced has a viscosity of 139000 cP. It dissolves in water somewhat slower than does the organosol produced ;~
according to ~xarnple 1, and has, in 1% aqueous solution, a viscosity of 2,800 cP. If the organosol contains 0.8 ~: :
parts of acetic acid (instead of 0.53 parts), the speed ~ of dissolution is clearly increasedO
~ , ~
5) The operation is carried out as in Example 1, but the monomer mixture is adjusted to pH 1 and the addltion of acetic acid is dispensed with. The obtained organosol `~ - has a viscosity of 2,000 cP. It is easily dissolved in - water and forms for example a 1% solution of 2~700 cP~ -If a further C.26 parts of acetic acid are added to the ;- : .
; organosol, then the 1% solution prepared therefrom rçaches ~, :, ' . ' : . , . ' ' , ' ! ~

; 3,700 cP. ~ 2 Exam~le 5 The method of operating according to Example 3 is repeated except that instead of the 4,4' azobis(4-cyanovaleric acid) ~issolved in the monomer phase, an , , .
~ equa~ amount of 292'~azobis(ethylisobutyrate) is dissolved : : ~
~ . in the oi]. phase. An organic dispersion is formed, with :. .
;~ - particles which are substantially ~iner in comparison .
to the suspension according to E~ample 3.
. 10 - On dissolving in water, a 1% aqueous solution of . 5,500 cP lS Obtall:led .

- ~

.

' . ' ' . ' : . ~ . ~ ' :

`''' ' ' ,'' ~ ', .

Claims (27)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Polymer dispersions comprising a dispersion in a continuous organic phase which is not completely miscible with water, of a fine particle size aqueous phase comprising a water-soluble high-molecular weight polymer dissolved in water or swelled with water, the dispersion containing a water-soluble acid and a water-in-oil emulsifying agent soluble in the organic phase which comprises (a) a vinyl polymer of (i) 10 to 50% by weight of at least one vinyl monomer containing a basic nitrogen atom, (ii) 90 to 50% by weight of at least one non-water-soluble ester of acrylic or methacrylic acid with an alkanol containing 6 or more carbon atoms, or a mixture of at least one such ester with a minor amount of one or more further non-water-soluble, vinyl monomers; or a mixture of the said vinyl polymer (a) with (b) one or more other surface-active compounds, whereby the resulting HLB value of the complete emulsifying agent is below 6 at a pH value above 4, and above 8 at a pH value below 2.

2. Dispersions as claimed in claim 1 wherein vinyl monomer (i) of the said vinyl polymer comprises vinylpyridine, vinylimidazole or an amide or dialkylaminoalkyl ester of acrylic or methacrylic acid.

3. Dispersions as claimed in claim 1 wherein vinyl monomer (ii) of the said vinyl polymer includes a minor amount of styrene and/or a lower ester of acrylic or methacrylic acid.

4. Dispersions as claimed in any of claims 1 to 3 wherein the said vinyl polymer is derived from 20 to 30% by weight of vinyl monomer (i).

5. Dispersions as claimed in any of claims 1 to 3 wherein the said vinyl polymer has a molecular weight of above 10,000.

6. Dispersions as claimed in any of claims 1 to 3 wherein the said vinyl polymer is employed in an amount of 2 to 20% by weight of the organic phase.

7. Dispersions as claimed in any of claims 1 to 3 wherein the said water-soluble polymer comprises units of acrylamide, vinylpyrrolidone, vinyl alcohol or a (hydroxyalkyl)-acrylate or methacrylate.

8. Dispersions as claimed in any of claims 1 to 3 wherein the said water-soluble polymer comprises units of (methacryloxy ethyl)-trimethyl-ammonium chloride.

9. Dispersions as claimed in any of claims 1 to 3 wherein the said water-soluble polymer comprises units of the sodium salt of vinylsulphonic or styrenesulphonic acid.

10. Dispersions as claimed in any of claims 1 to 3 wherein the said aqueous phase contains 50-60% by weight of the said water-soluble polymer.

11. Dispersions as claimed in any of claims 1 to 3 wherein the said water-soluble polymer has a molecular weight of at least 1,000,000.

12. Dispersions as claimed in any of claims 1 to 3 wherein the particle size of the aqueous phase in the organic phase is 10 to 500 mµ.

13. Dispersions as claimed in any of claims 1 to 3 wherein the said organic phase comprises a mineral oil.

14. Dispersions as claimed in any of claims 1 to 3 containing 15 to 20% by volume of the said organic phase.

15. Dispersions as claimed in any of claims 1 to 3 having a viscosity of 1,000 to 20,000 cP.

16. Dispersions as claimed in claim 1 wherein the acid is a water-soluble inorganic acid.

17. Dispersions as claimed in claim 1 wherein said acid is one of hydrochloric acid, sulphuric acid, ammonium hydrogen sulphate or phosphoric acid.

18. Dispersions as claimed in claim 1 wherein the said acid is a water-soluble organic acid.

19. Dispersions as claimed in claim 1 wherein the said acid comprises an organic carboxylic acid, sulphonic acid, phosphonic acid or phosphinic acid.

20. Dispersions as claimed in any of claims 16,18 and 19 wherein the said acid is dissolved or suspended in the said organic phase.

21. Dispersions as claimed in any of claims 16 to 18 wherein the said acid is dissolved or suspended in the said polymer phase.

22. Dispersions as claimed in any of claims 1, 16 and 18 wherein the s id acid is present in an amount at least equivalent to the basic nitrogen atoms present in the vinyl polymer.

23. Dispersions as claimed in claim 1 wherein the said aqueous phase has a pH value of above 4.

24. A process for the preparation of the dispersions as claimed in claim 1 which comprises finely dispersing in a continuous organic phase which is not completely miscible with water, an aqueous solution of at least one monomer capable of forming a water-soluble polymer, and polymerising the said monomer in the presence of a radical-forming polymerisation initiator which is soluble in water or in the organic phase, a water-soluble acid and a water-in-oil emulsifying agent soluble in the organic phase which comprises (a) a vinyl polymer of (i) 10 to 50% by weight of at least one vinyl monomer containing a basic nitrogen atom, (ii) 90 to 50% by weight of at least one non-water-soluble ester of acrylic or methacrylic acid with an alkanol containing 6 or more carbon atoms, or a mixture of at least one such ester with a minor amount of one or more further non-water-soluble, vinyl monomers;
or a mixture of the said vinyl polymer (a) with (b) one or more other surface-active compounds, whereby the resulting HLB value of the complete emulsifying agent is below 6 at a pH value above 4, and above 8 at a pH value below 2.

25. A process as claimed in claim 24 wherein the polymerisation is effected in the presence of a polymerisation initiator which is soluble in water, the resulting dispersions having a particle size of 10 to 500 µm.

26. A process as claimed in claim 24 wherein the polymerisation is effected in the presence of a polymerisation initiator which is soluble in the organic phase, the resulting dispersion having a particle size of less than 10 µm.

27. A method of preparing solutions of water-soluble high molecular weight polymers which comprises admixing a dispersion as claimed in and of claims 1 to 3 with an excess of water in the presence of an acid serving to neutralise the basic nitrogen atoms of the said vinyl polymer.