3,305,508 United States Patent Office Patented Feb. 21, 1967 2 3,305,508 EMULSIFICATION IN PRESENCE OF AN AL standing the reduced foam formation the losses of co PHATC OXYGEN COMPOUND . agulum are high. This is because coagulation is then Gerardus E. La Hei and Jacques A. Waterman, Amster caused by the comparatively large amount of highly water dam, Netherlands, assignors to Shell Oil Company, New soluble organic oxygen compounds that is needed, even York, N.Y., a corporation of Delaware when the concentration of emulsifier is but low, for Sup No Drawing. Filed Dec. 13, 1963, Ser. No. 330,266 pressing troublesome foam formation. Moreover, these Claims priority, application Netherlands, Feb. 5, 1963, processes are not sufficiently flexible, because, on the one 288,572 hand, enlargement of the latex particles through reduc 6 Claims. (Cl. 260-29.7) tion of the emulsifier concentration does not permit of a The invention relates to a process for the preparation O proportional reduction in quantity of organic oxygen com of aqueous dispersions of homopolymeric or copolymeric pounds and hence involves greater coagulum losses, and, macromolecular substances obtained by polymerization, on the other, reduction of particle size by raising the polycondensation or polyaddition of vinylidene com emulsifier content cannot be achieved without sacrificing pounds. More in particular, the preparation of artificial the advantage of suppressing troublesome foam forma latices is contemplated. 5 tion, or without increasing the quantity of organic oxygen If necessary, increased temperature and/or pressure can compoundsagulum losses. and hence also further increasing the co be applied in preparing the solutions of the macromolec Because of this the particle size is often too small for ular substances. the preparation of good macromolecular foams and too If in preparing artificial latices, one fails to take special 20 large for preparing latices of the quality that is the most measures during and/or after emulsification, very trouble desirable for dipping processes. some foam formation occurs when the solvent is removed It has now been found that not only can the aforesaid via the vapor phase, even if the concentration of emulsifier troublesome foam and slime formation be avoided, but is quite low, and this is accompanied by partial coagula the losses through coagulation can also be obviated en tion and often by the formation of “slime.” By "slime' 25 is understood a slimy mixture, presumably consisting of tirely or almost entirely, while, in addition, within cer a continuous solvent phase in which droplets of water tain limits the particle size of the latices can be con are dispersed, which contain polymer particles that have trolled by adjusting the emulsifier concentration, without been only partially freed of solvent and are hence in a sacrificing the advantages mentioned before. strongly swollen state. Moreover, if high emulsifier con 30 Now in accordance with this invention, the process is centrations are not applied, the latices thus obtained are carried out in the presence of certain aliphatic organic very coarse, which makes them unsuitable for being con oxygen compounds, which are in this case, too, brought centrated to what are called foam latices, from which into contact with the other substances exclusively before foam rubbers can be manufactured. In addition, such vaporization of the polymer solvent and which coarse dispersions, when concentrated, do not produce 35 (a) In the conditions under which the solvent for the latices that are suitable for dipping processes. If this polymer is removed, do not have an acid reaction process is carried out with higher emulsifier concentra towards the water phase (which therefore rules out, tions and/or if pressure is reduced during the removal of for instance, esters that are hydrolyzed under such con the solvent, surface dehydration of the foam formed will ditions and also phenols), and further increase the losses due to coagulation and slime 40 (b) In the quantity applied, are completely miscible at formation. The latices of non-rubberlike polymers, such 30 C, with the quantity of solvent applied. as those of polystyrene or of styrene/butadiene copoly The distinctive features are now, however: mers with a high styrene content, can very suitably be (1) That the organic oxygen compounds applied are mixed with, say, foam rubber latices, in order to prepare poorly soluble in water, that is to say, that at 30 C. therefromproperties. foam rubbers having improved mechanical their solubility in water is less than 20 g. per 100 ml., Processes are known for the preparation of artificial and latices from diene polymers or copolymers, in which the (2) That the quantity of oxygen compounds applied, as emulsification of the solutions of such polymers can be referred to water phase, is 0.5-30% by volume. effected. For instance, they may be formed in the pres 50 As a rule the emulsification takes place under normal ence of organic oxygen compounds that are highly soluble temperature and pressure conditions, but in certain cases in water, such as readily water-soluble alcohols, ketones it may be carried out at higher or lower temperature or ethers. Under the conditions at which the solvent is and/or pressure. removed, the oxygen compounds previously used are gen The aliphatic oxygen compounds useful for this pur erally completely miscible, at the emulsification temper 55 pose include especially alcohols and ketones having 4-10 ature and pressure, with the quantities of solvent used for carbon atoms per molecule. Carbinols are preferred, as the polymer and with water. The application of the well as ketones in which at least one of the alkyl radicals aforesaid organic oxygen compounds aimed at improv attached to the DCFO group has a branched structure. ing the emulsification. The entire quantity of such com Examples of organic oxygen compounds that have a pounds was therefore admixed before emulsification. 60 solubility in water of less than 20 g. per 100 ml. at 30° C. It was found that in the processes just described, during are n-butyl alcohol, isobutyl alcohol, secondary butyl the removal of the solvent for the polymer via the vapor alcohol, the various amyl alcohols, methyl isobutyl car phase, there is no longer troublesome foaming, while no binol, the hexanols, heptanols and octanols, methyl iso "slime,” or scarcely any, is formed, provided the ratio by butyl ketone, diethyl ketone, methyl n-butyl ketone, di volume of the sum of polymer and solvent to the sum 65 isobutyl ketone. of water and organic oxygen compounds is not too high Application of the limited classes of organic oxygen and the quantity of these oxygen compounds is not too compounds according to the invention has the advantage low. Applying equal emulsifier concentrations, the aver that such compounds cause a greater reduction of surface age particle size of the resultant latices is then consider tension than do those of higher solubility in water. Con ably smaller than when the processes are carried out in 70 sequently, insofar as better emulsification is the objective, the absence of organic oxygen compounds, but notwith in the present process Smaller quantities may suffice. Be sides, such organic oxygen compounds generally have 3,305,508 3 4 higher boiling points than those of good solubility in prene, polypiperylene, copolymers of dienes with each water, owing to which they can longer continue to exert other or of dienes with monovinyl aromatic compounds, their anti-foaming effect when the solvent is being re such as the butadiene/styrene copolymers (in which moved. For this reason, too, a smaller quantity of this either the butadiene content or the styrene content may category of substances is needed than of the readily predominate), or from mixtures of such polymers and/or water-soluble organic oxygen compounds. copolymers with each other. The treatment of polymers In consequence, and also because only a very small of vinylpyridines, acrylic esters, methacrylic esters, hydro proportion of the poorly water-soluble organic oxygen genated derivatives of the foregoing polymers, and the compounds will get into the water phase, the process con like also is contemplated. cerned has the important advantage that the risk of the O The polymers that can be applied in the process ac occurrence of coagulum losses through the presence of cording to the invention also comprise the block polymers too much organic oxygen compound is Substantially less and copolymers, as well as the graft polymers and co than in the known processes. On this account, it is pos polymers. - sible to control the particle size of the latex within cer In many cases polymers or copolymers will be applied tain limits, and without any appreciable coagulation, by in the form of the solution in which they were formed modifying the concentration of the emulsifier, for instance during their preparation. between 1 and 20% w. (on polymer). According to the viscosity of the solution, the concen An additional advantage is that as a rule the difference tration of the solutions to be emulsified according to the in boiling point between the organic oxygen compounds invention may vary within wide limits, for instance from and the customary solvents for the macromolecular sub 20 3% w. to 70% w. of macromolecular substance. As a stances is large and that no azeotropes are formed between rule, however, concentrations between 5 and 20% w, will these two types of components, so that these components be the most suitable. do not pass over together. For this reason it will almost The solvents that can be used in the present process invariably be possible easily to recover the solvents free depend, among other factors, on the nature of the from, or virtually free from, organic oxygen compounds. 25 macromolecular substance. Besides aliphatic, cyclo After the organic oxygen compounds have been re aliphatic and aromatic hydrocarbons, nonhydrocarbons moved from the dispersions, for instance by steam strip for instance chloroform, carbon tetrachloride, carbon ping, they too can easily be recovered from the water disulfide, ethers, and so on, may also be suitable solvents, containing condensates. For, on account of their poor Particularly suitable solvents for copolymers built up solubility in water, they segregate spontaneously from 30 entirely or predominantly of ethene and propene of such condensates, also when they are expelled in the form butene and which may have been obtained from an of an azeotrope with water. additional third comonomer (for instance a diene), are The particle size of the latices obtained can be judged the liquid alkanes of isoalkanes having a boiling point not only by determination of the dimensions, but also below 150° C. In such cases, methyl isobutyl carbinol from the results of measurements of the viscosity, the has proved to be a very suitable organic oxygen com surface tension and the optical density of the latices. pound. At high emulsifier concentrations very fine latices, For preparing artificial latices from polyisoprene a which therefore have a comparatively high viscosity, are suitable solvent will often be a mixture of branched formed without any trouble. These latices, after being pentenes, as this polymer is generally prepared in this concentrated to a solids content of about 40-60% by 40 solvent. With such solutions methyl isobutyl carbinol Weight, are, in the case of rubberlike macromolecular can again very well be applied as the organic oxygen materials, especially suitable for use in dipping processes, compound, as can also the butanols of which the hy for applying coatings to articles in general and in par droxyl group is attached to a primary or secondary ticular for carpet backing, tire cord dipping and for im carbon atom. pregnating textiles and paper. 45 The best results are obtained with the process accord If, however, low emulsifier concentrations are applied, ing to the invention if the ratio by volume of the sum latices can be obtained, also without encountering any of macromolecular substances and solvent to the sum of difficulty, for the preparation of foam latices, especially Water and organic oxygen compounds is between 0.5 for producing foams of rubberlike materials. The latices and 5. must then be concentrated to a solids content of more The emulsification is generally carried out in inten than 55% w, for instance to 65% by weight or even sively operating emulsification equipment, such as high Oc. Speed colloid mills with a turbomixed fitted in the intake Preferably, organic oxygen compounds with a boiling funnel, and also planetary mixers provided with wall point under normal conditions of less than 195. C. are Scrapers. - chosen. As a rule such oxygen compounds will then be 55 Suitable emulsifiers are ionic as well as non-ionic rep expelled from the dispersion during or after the removal resentatives or mixtures thereof. Preferably anionic of the solvent for the polymer, also via the vapor phase. emulsifiers are applied, such as alkali or ammonium soaps The representatives most highly preferred are those that of resin acids and/or fatty acids, for instance of oleic have a boiling point under normal conditions of below acid, palmitic acid, stearic acid, lauric acid, myristic 150° C., while in certain circumstances representatives 60 acid, arachic acid, ricinoleic acid. A very suitable are preferably used that have a solubility in water of less emulsifier of this type is also the moropholine oleate. than 5g. per 100 ml. at 30° C. Other useful anionic emulsifiers are the alkali or ammoni Generally, the quantity of the organic oxygen com um soaps of branched carboxylic acids, of alkyl or aryl pounds used is 0.1-30% (preferably 0.5-20%) by vol sulfuric acids, of alkyl or arylsulfonic acids, and also of ume calculated on water phase. 65 Sulfated or sulfonated glycidyl esters of carboxylic acids. The group of the aforesaid macromolecular substances The cationic emulsifiers are also very suitable. To this also comprises liquid representatives, in so far as their group belong, for instance, the quaternary ammonium average molecular weight is not lower than 1,000, for salts, such as tridecylbenzene, hydroxyethylimidazolinium instance the liquid polymers or copolymers of dienes chloride, stearyldimethylbenzylammonium chloride, cetyl having an average molecular weight of about 1200-12,- 70 pyridinium bromide, etc. It is, however, also possible 000. to use nonionic emulsifiers, for instance the phosphoric The new process is of particular importance for the esters of higher alcohols, such as capryl and octyl alcohol, preparation of artificial latices from polymers of vi and also the monoesters of oleic acid and pentaerythritol, nylidene compounds, such as poly(alpha olefins), con Sorbitan monooleate, etc. jugated diene polymers, such as polybutadiene polyiso 75 The emulsifiers may be added in several ways, for in 3,305,508 5 6 stance to the water phase, to the solvent phase, to the treatment. When the methyl isobutyl carbinol was re organic oxygen compound or to mixtures thereof. The moved an azeotrope of this alcohol, 75% v. of which emulsifiers can also be prepared in situ; the emulsifier- consisted of water, was expelled. Upon condensation forming components may then be distributed, if so de- of this azeotrope two layers were at once formed, of which sired, over several phases. 5 the upper one consisted almost entirely of methyl iso presenceDuring in the the emulsification dispersion of therecarbon is blackno objection and/or oneto the or Water.butyl carbinol and the bottom one almost exclusively of more other reinforcing or non-reinforcing solid fillers, for The remaining latex, which contained 4.8% w. of instance white fillers and certain resins, for instance polymer, was concentrated to a solids content of 61% w. phenol formaldehyde resins, urea formaldehyde resins, 10 by being centrifuged in a centrifuge at a speed of 20,000 coumarone resins and petroleum resins. revolutions per minute. The removal of the solvent, and, in so far as this is The surface tension and the viscosity of the concen possible, also of the organic oxygen compounds, is ef- trated lateX were determined. The viscosity measure fected in the vapor phase, preferably utilizing steam. ments were carried out at 25 C. in a Drage viscometer According to the combination of solvent and organic li) using the appropriate standard cup and the rotor (spindle) oxygen compounds chosen, the removal of these com- with a diameter of 24 mm., at 20.5, 64 and 200 rp.m. ponents can be carried out simultaneously or in succes- For comparison the experiment was repeated (experi sion, if necessary by raising the temperature of expulsion. ment 2) under otherwise similar conditions, but now Azeotropic formation may then occur, but usually only with 20% v. of isopropyl alcohol (IPA) calculated on of the organic oxygen compound with water. 20 water phase, instead of 10% v. of methyl isobutyl car Should there still be any trouble of foam formation binol. The quantities of alcohol were in both cases the during removal of solvent and organic oxygen com- minimum quantities that are under the given conditions pound, it can simply be obviated, if desired, by blowing necessary to prevent troublesome foam formation. Iso a gas, for instance air, in countercurrent through the propyl alcohol is an alcohol of very high solubility in foam. 25 water. The results, as regards coagulum losses and sur The latices obtained by the process according to the face tension and viscosity of the latices obtained, are invention after removal of the solvent and preferably presented in Table I. also of the organic oxygen compound, can be concen- In a third test (experiment 3), the conditions of ex trated in any desired manner. Thus, one can utilize for periment 1 were repeated, except that the methyl iso this purpose high-speed centrifuges, creaming or thick- 80 butyl carbinol was added in two stages, one-half before ening agents, or evaporation, for instance in a film evap- emulsification and one-half after emulsification.

TABLE I Properties of Concentrated Latex Quantity AmountCoagulum of Exp. Calc. on After Steam Drage Wiscosity, cp., No. Nature Water Treatment, Surface Rotor d5 24 mm. (No. of Phase Percent W. Tension, Revolutions per Min.) on Polymer dyn/cm.2 --- (20.5) (64) (200) 1------MBC------10 <1. 30 304 195 133 2------IPA.------20 5 30 890 450 250 8------MBC------10 k1 30 290 185 32 orator. In a more preferred alternative, the concentra- The concentrated latex obtained in experiment 1 was tion of water-soluble emulsifier in the latex to be concen- particularly suitable for application as a foam latex. The trated is raised to 20-100% w. of the macromolecular concentrated latex of experiment 2 was far less suitable substance dispersed, after which the unstable suspension for this purpose. Moreover, the loss of coagulum in obtained is allowed to segregate either spontaneously or 50 experiment 2 was much too high for commercial pur not spontaneously with formation of a top layer that gen- poses. The concentrated latex obtained in experiment 1 erally contains virtually all the macromolecular substance was mixed, per 100 parts by weight of polyisoprene, in the form of a concentrated latex. with 1 part by weight of sulfur, 1 part by weight of zinc The process concerned is easy and quick and, if so dithiocarbamate and 2 parts by weight of zinc oxide. desired, can be carried out continuously. 55 The mixture was then spread out to a film on a glass plate. After being dried this film was vulcanized at Example 1 100° C. for 25 minutes. The vulcanized film proved to 100 parts by volume of a 7.4% w. (i.e. 5% w./v.) 36. a tensile strength of 256 kg/cm2, a modulus at solution of a polyisoprene in a technical mixture of f % elongation of 8 kg/cm., an elongation at rupture tertiary amylenes were emulsified with 90 parts by volume 60 of 1043% and a set at break of 9%. of water, in which was dissolved 5% w. of potassium Example II oleate, calculated on polymer, and to which had been added 10 parts by volume of methyl isobutyl carbinol 100 parts by volume of the polyisoprenepolysop solution in (MBC). The polyisopreneo consistedo to an extent of partsamylenes by volume described of ain 30% Example w/v. solutionI was stirred of polystyrene with 3.3 92.5% W. of the cis-1,4-configuration and had an intrinsic 65 in benzene, so that the mixture contained 20 parts by viscosity of 7.4. The mixture was emulsified for 15 min- weight of polystyrene to 100 parts by weight of poly utes in a high-speed colloid mill, having an turbomixer isoprene. The mixture was then emulsified for 15 min. built in the intake funnel. with the aid of the apparatus described in Example I The emulsion obtained was completely freed of or- with 90 parts by volume of water in which 5% w. of ganic liquids by steam stripping, first at about 35–40° C. 70 potassium oleate, calculated on polymer, was dissolved of the amylenes (boiling point 34° C.) and then at 93- and to which 10 parts by volume of methyl isobutyl 100 C. of the methyl isobutyl carbinol (boiling point carbinol had been added. 130° C.) As this alcohol does not form an azeotrope The amylenes, the benzene and the methyl isobutyl car afreshwith amylenes, as solvent theafter amylenes condensation expelled without could any be further used 75 binolsteam werestripping. completely removed from the dispersion by 3,305,508 8 7 mer solution and aqueous phase prior to hydrocarbon The resultant latex, containing 5.1% w. of polymer vaporization 0.5-30% volume based on the aqueous phase mixture, was then concentrated in a film evaporator to a of an aliphatic oxygen compound having 4-10 carbon solids content of 64.5% w. After this concentration the atoms per molecule and having a solubility in water of latex was still thin-liquid. less than 20 grams per 100 cc. water at 30° C. of the Of the concentrated latex a vulcanized film was made group consisting of alcohols and ketones. as described at the end of Example I. The film proved 2. A process according to claim 1 wherein the oxygen to have a tensile strength of 136 kg./cm., a modulus at compound is added to the mixture subsequent to emulsi 300% elongation of 13 kg/cm., an elongation at rupture fication. of 868% and a set at break of 4%. 3. Process for preparing a latex of polymers of con Example III O jugated dienes, which comprises emulsifying one volume In order to know the effect of the nature and the quan of a solution of said polymer in a hydrocarbon solvent tity applied of some organic oxygen compounds upon. having 4-10 carbon atoms per molecule with 0.5-5 vol the interfacial tension of the polymer solution/water umes of an aqueous phase comprising water and an phase in the process according to the invention, some 5 emulsifying agent, and 0.5-30% by volume based on said determinations of the interfacial tension were carried aqueous phase of an aliphatic oxygen compound miscible out at 25 C. in the absence of polymer, the poorly water with said hydrocarbon solvent, having 4-10 carbon atoms soluble organic oxygen compounds being sec-butyl alco per molecule and having a solubility in water of less than hol and methyl isobutyl carbinol, the solvent being a 20 grams per 100 cc. water at 30° C., of the group con technical mixture of tertiary amylenes. The nature and 20 sisting of alcohols and ketones by intense agitation where quantity of the organic oxygen compound were varied by colloidal particles of the polymer solution suspended in these determinations. In all the determinations the in the aqueous phase are formed, removing the hydro ratio by volume of amylenes (water-organic oxygen. carbon solvent by vaporization and recovering a stable compound) was equal to 1. For comparison the effects of polymer4. Process latex. for preparing- a latex of a polymerized con isopropyl alcohol and acetone as the organic oxygen com 25 jugated diene which comprises emulsifying one volume pounds of good solubility in water were also ascertained. of a solution of a polymerized conjugated diene in a The results are shown in Table II. hydrocarbon solvent having 4-10 carbon atoms per mole TABLE II.-ORGANIC OXYGENCOMPOUND cule, with 0.5-5 volumes of an aqueous phase comprising 30 Water and an emulsifying agent and 0.5-30% by volume, Percent v. as based on said aqueous phase, of a hydrocarbon-soluble Solubility in referred to Interfacial alcohol having 4-10 carbon atoms per molecule and hav Nature water, g. per water plus tension, 100 mill. org. Oxygen dynefc.m. ing a water solubility of less than 20 grams per 100 cc. compound Water at 30° C., by intense agitation whereby colloidal particles of the polymer solution suspended in the aqueous None------0. 39 phase are formed, removing the hydrocarbon solvent and Sec. butyl alcohol------12.5 5 27 - 10 2 alcohol by vaporization and recovering a stable polymer 20 7.5 ateX. 30 7.5 5. Process for preparing a polyisoprene latex which Methyl isobutyl carbinol--- 1.8 105 22.57.5. 20 15 40 comprises emulsifying one volume of a solution of poly 30 2.5 isoprene in amylenes with 0.5-5 volumes of an aqueous Isopropylopropy alcohol------CO 105 20.5 phase comprising water and an emulsifying agent, and 20 8.5 0.5-30% by volume, based on said aqueous phase, of 30 6, 5 methyl isobutyl carbinol, by intense agitation whereby Acetone------co 50 3120 colloidal particles of the polymer solution suspended in 20 5 the aqueous phase are formed, removing the organic 30 14.5 liquids by vaporization and recovering a stable polyiso prene latex. We claim as our invention: 6. A process according to claim 3 wherein the poly 1. In the process for preparing a latex of a polymer mer is polyisoprene and the hydrocarbon solvent is an of the group consisting of polymers of polymerizable aromatic hydrocarbon. vinylidene compounds wherein one volume of a solu tion of said polymer in a water-immiscible solvent having References Cited by the Examiner 4-10 carbon atoms per molecule, is emulsified with 0.5- UNITED STATES PATENTS 5 volumes of an aqueous phase comprising water and an 2,615,010. 10/1952 Troyan ------260-29.7 emulsifying agent, by intense agitation whereby colloidal 2,953,556 9/1960 Wolfe et al. ------260-94.7 particles of the polymer solution suspended in the aqueous phase are formed, removing the hydrocarbon solvent by MURRAY TILLMAN, Primary Examiner. vaporization and recovering a latex therefrom, the im provement comprising adding to the mixture of poly J. ZIEGLER, Assistant Examiner.