CA1138150A - Use of an electrolyte in the emulsion polymerization process for producing vinyl dispersion resins - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
There is disclosed a process for preparing vinyl dispersion resins by conducting the polymerization reaction of the vinyl monomer or monomers in an aqueous alkaline medium, using an oil-soluble polymerization initiator, at low temperatures, in the presence of an emulsifier system comprising the ammonium salt of a high fatty acid containing 8 to 20 carbon atoms and at least one long straight chain alcohol containing from 14 to 24 carbon atoms, and in the presence of an electrolyte, such as for example, ammonium carbonate ((NH4)2CO3), and wherein the reaction ingredients are thoroughly mixed, and preferably homogenized, prior to polymerization.
The aqueous emulsion of the polymer(s) so produced are capable of being tray dried into friable aggregates of individual spheres of polymer particles. The tray dried resin can easily be formulated into plastisols of high North Fineness and high gloss. In addition, polymer buildup in the reactor is reduced.

Description

USE OF AN ELECTROLYTE IN THE EMULSION
POLYMERIZATION PROCESS FOR PRODUCING
VINYL DISPERSION RESINS

BACXGROUND OF THE INVENTION
It is well known that vinyl resins may be plasticized or changed from the hard, horny and stiff state to a soft, plastic workable condition by the addition thereto, at elevated temperatures, of certain plasticizers, such as dioctyl phthalate, and the like.
These vinyl polymers or resins are referred to as dis-persion resins or paste resins and are usually made employing an aqueous emulsion polymerization technique.
In some cases, a suspension polymerization process has been used, but emulsion polymerization is preferred.
15When the vinyl dispersion resin is mixed or blended with a plasticizer, it is referred to as a "plastisol". By virtue of the flowability of the plas-tisol, it can be processed into various useful products.
For example, the plastisols can be used in making molded products, films, coatings, and the like. Accordingly, the vinyl dispersion resin must be capable of being mixed with the plasticizers easily and uniformly to form low viscosity plastisols which are stable, containing particles of uniform and proper size, and capable of 25 producing films, and like products, of good clarity.
With the customary emulsion polymerization processes, suitable latices have been difficult to obtain since the latices usually conta.in particles of varying size and are either too fine or too large.
30 Various proposals haYe heretofore been made to overcome these difficulties but not with the ultimate success desired. For example, the use of various different emulsifiers and catalysts have been proposed. Also, varying the conditions of polymerization has been 35 suggested. However, in most o these cases, too much , 1~38~5 coagulation occurred with the resulting latex containing too much coagulum or partially agglomerated particles which precipitate reducing the yield. Further, the shelf~ife of such latices leave much to be desired. It is desirable to have latices which change very little during storage with respect to viscosity and have and maintain good heat stability.
In U.S. Patent No. 4,076,920, issued February 28, 1978, a process for preparing vinyl dispersion resins is disclosed and claimed which produces polymers having unique properties for certain end uses. However, here, as in other prior art processes, it is necessary to spray dry the latex or polymer emulsion resulting in aggregates of the polymer particles which requires grinding to break them up into a size capable of being used in plastisols. As a result of the crushing and grinding required to reduce the polymer to a size capable of being used in plastisols and, also because of the varying sizes and irregular shapes of the ground frag-ments, the plastisols produced from them have highviscosities relative to their solids content. Further, the excessive grinding required develops excessive heat which tends to fuse the polymer.
As opposed to "pearl" or suspension polymer-ization, where the polymer particles are large enough to be filtered, vinyl dispersion resins cannot be recovered from the water emulsions by filtration and tray drying because they go through the filters and also because the small particles pack tightly together during tray drying forming "cake" that even after grinding remains hard to formulate into smooth plastisols making it practically useless for most commercial operations. The particles of polymer to be used in a plastisol should preferably be spherical in shape to present as small a particle surface as possible for minimum solvation. Also, a dispersion of spheres provides the lowest flow viscosity for charging molds, coating and like operations (See U.S.
Patent No. 3, 179, 646, issued April 20, 1965).
Another problem in making vinyl dispersion resins is the formation of undesirable polymer buildup on the inner surfaces of the reactor. This deposlt or bulldup of polymer on sald reactor surfaces not only interferes with heat trans-fer, but also decreases productlvity and adversely affects polymer quallty, such as produclng finer particles than desired with the resultant adverse effect on viscosity. Ob-vlously, thls polymer bulldup must be removed, withlts atten-dant dlfflcultles. It would be most deslrous to prevent or substantially eliminate polymer bulldup ln the flrst instance.
We have unexpectedly found that when the emulsion polymerizatlon of vlnyl dlsperslon reslns ls conducted ln the presence of an electrolyte, such as, for example, the "fugltlve" ammonium carbonate ((NH4)2CO3), whlch evaporates durlng drylng, the resultlng aqueous polymer emulslon can be tray drled lnto friable aggregates of lndividual spheres of polymer particles which can be separated into lndivldual spherical polymer particles by simple light rubbing or crush-ing. In the process of the present lnventlon, whereln tray drying is employed, in additlon to the electrolyte, the poly-merlzatlon reaction of the vlnyl monomer or monomers ls con-ducted in an aqueous alkallne medlum uslng a free radlcal yleldlng polymerlzation initlator, at a temperature of about 30C to about 70C, ln the presence of an emulslfier for the polymerization system, for example an ammonlum salt of a hlgh fatty acld containing from 8 to 20 carbon atoms, and at least one long straight chain alcohol contalnlng from 14 to 24 carbon atoms, wherein the ratio of alcohol to emulsifier is equal to or greater than 1.0 and whereln the reaction ingre-dients are thoroughly mixed, and preferably homogenized, prior to polymeriza-.~

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tion. When employing the process of the invention, thepolymer buildup in the reactor is reduced and multiple polymerizations can be run in the reactor without open-ing the same thereby substantially reducing the amount 5 of unreacted monomer in the surrounding atmosphere.
DETAILED DESCRIPTION
In the present invention, "vinyl dispersion resin" refers to polymers and copolymers of vinyl and vinylidene halides such as vinyl chloride, vinylidene chloride, and the like. The vinyl halides and vinyl-idene halides may be copolymerized with one or more vinylidene monomers having at least one terminal CH2=C
grouping. As examples of such vinylidene monomers may be be mentioned the ,~-olefinically unsaturated car-boxylic acids, such as acrylic acid, methacrylic acid,-cyanoacrylic acid, and the like; esters of acrylic acids, such as methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, cyanoethyl acrylate, and the like; esters of methacrylic acid, such as methyl meth-acrylate, butyl methacrylate, and the like; nitrilessuch as acrylonitrile and methacrylonitrile; acrylamides, such as methyl acrylamide, N-methylol acrylamide, N-butoxyl methacrylamide, and the like; v nyl ethers, such as ethyl vinyl ether, chloroethyl vinyl ether, and the like; the vinyl ketones; styrene and styrene derivatives including a-methyl styrene, vinyl toluene, chloro-styrene, and the like; vinyl naphthalene, allyl and vinyl chloroacetate, vinyl acetate, vinyl pyridine, methyl vinyl ketone, and other vinylidene monomers of the types known to those skilled in the art. The present invention is particularly applicable to the manufacture of vinyl dispersion resins or pastes made by the poly-merization of vinyl chloride or vinylidene chloride alone or in admixture with one or more vinylidene monomers copolymerizable therewith in amounts as great as about 80~ by weight, based on the weight of the ~i38~50 monomer mixture. The most preferred vinyl dispersion resin is polyvinyl chloride (PVC) and the invention, for simplicity and convenience, will be described in connec-tion therewith, it being understood that this is merely intended in an illustrative and not a limitative sense.
The important aspect of the instant invention is the provision of a process for producing vinyl dis-persion resins wherein, after the formulation of the polymer latex or aqueous polymer emulsion, the same can 10 be dried into friable aggregates of individual spheres of polymer particles by simple tray drying. This elim-inates the troublesome spray drying and grinding which very often results in undesirable polymer quality. The inventive concept which enables one to tray dry the 15 polymer emulsion is in the use of an electrolyte in the polymerization recipe. The electrolytes useful in the present invention are ammonium carbonate ((NH4)2CO3), calcium chloride (CaC12), calcium carbonate (CaCO3), ammonium phosphate, the bicarbonates, the sodium salts 20 such as carbonates, bicarbonates and phosphates, and the like. The amount of electrolyte suitable for use in the present invention will vary from about 0.05% to about 6.0% by weight, based on the weight of the monomer or monomers being polymerized. Preferably an amount in the 25 range of 0.1% to 2.0% by weight is employed.
The friable aggregates resulting from the process of the instant invention represent a distinct advantage or improvement over prior known means for recovering vinyl dispersion or paste resins from the 30 water for use in plastisols, for example, spray drying and subsequent grinding. The friable aggregates of the present process can easily be handled in the post poly-merization stages of polymer or resin recovery. The friable aggregates are easily formed and the individual 35 spherical particles of the vinyl dispersion resins, of a size required for paste resins are easily formed by crushing, simple grinding or rubbing of said aggregates.
Usually, the individual spherical particles of polymer will have a size or diameter in the range of 0.1 micron to about 10.0 microns. For most of the commercial uses 5 of plastisols today, it is preferred to have polymer particles in the range of 0.2 micron to 2.0 microns.
Surprisingly, there are other pluses in the use of the electrolytes in the emulsion polymerization process besides the ability to use tray drying and get 10 an improved quality product. For example, when employ-ing the electrolyte in the polymerization recipe the rate of conversion of monomer(s) to polymer is increased resulting in an overall decrease in the time for com-plete polymerization which in turn results in increased 15 production per unit of time thereby reducing the cost of making vinyl dispersion resins when using the present process.
Another surprising feature of the present invention is that polymer buildup on the internal sur-20 faces of the reactor is reduced. While it is not knownprecisely why such reduction in buildup occurs, it is believed to be due in part not only to the presence of the electrolyte in the recipe, but also to the speed of the reaction and the lower reaction temperatures, since 25 it is known that the higher the temperature of reaction for prolonged periods of time increases the likelihood of excessive polymer buildup. In any event, the polymer buildup problem is greatly improved when using th~
present invention. Further, when employing the present 30 process, the vinyl dispersion resin and the plastisol application properties, such as heat stability, water resistance, flow properties, and the like, are not adversely effected and in fact, if anything, they are improved.
When making vinyl dispersion resins by the emulsion polymerization procedure it is necessary to ~3~1g~

employ a proper emulsifier or emulsifier system. For example, various fatty acid derivatives and salts there-of may be employed, as well as the sulfate and sulfonate type soaps of from C12 to C20 alkyl or aryl hydrocarbons, 5 or various combinations thereof. However, in the present invention, in order to get the proper water resistance and heat stability in films made from plasti-sols of the vinyl dispersion resins, preferably the ammonium salt of a long chain saturated fatty acid is 10 employed as the emulsifier. The saturated fatty acids which are useful may be either natural or synthetic and should contain from 8 to 20 carbon atoms. As examples of such acids there may be named lauric, myristic, palmitic, marganic, stearic, and the like, beef tallow, 15 coconut oil, and the like. The ammonium salt emulsifier is employed in an amount in the range of about 0.5% to about 4.0% by weight based on the weight of the monomer or monomers being polymerized. One can also use mix-tures of the ammonium salts of the fatty acids in the 20 emulsifier system.
The ammonium salts of the fatty acids can be made by mixing the fatty acid and = onium hydroxide, separating the salt and then adding the same to the polymerization medium or polymerization premix in the 25 usual fashion. However, it is preferred to form the ammonium salt in situ, that is, by adding the fatty acid and ammonium hydroxide separately to the polymerization mixture or medium wherein they react to form the salt.
An excess of ammonium hydroxide, over that necessary to 30 react with the fatty acid, should be employed in order to maintain the reaction medium on the alkaline side.
In addition to the ammonium salt of a long chain fatty acid emulsifier, it is often desirable to employ a long straight chain saturated alcohol in com-35 bination therewith, said alcohol being one containingfrom 14 to 24 carbon atoms. Examples of such alcohols ~3siso , are tetradecanol, pentadecanol, hexadecanol, hepta-decanol, octadecanol, nonadecanol, eicosanol, heneico-sanol, tricosanol, and tetracosanol. Mixtures of the alcohols can also be employed and in many cases an alcohol mixture is preferred, such as, for example, a mixture of a 14 carbon alcohol and an 18 carbon alcohol.
Also, lower carbon content alcohols can be employed when mixed with the longer chain alcohols, such as a mixture of dodecanol and octadecanol. When employing an alcohol, the ratio of alcohol to the ammonium salt of the fatty acid of 1.0 can be used., However, the best results are obtained when said ratio is greater than 1Ø
As pointed out above, the reaction medium should be maintained on the alkaline side, and prefer-ably at a high pH. The present process can be conductedat a pH in the range of about 7.0 to about 12Ø How-ever, it is preferred to operate in a pH range of about 8.0 to about 10.5. If the pH is too high it takes too much NH40H and if the pH is too low, for example, below 7.0, the polymer buildup in the reactor increases and the coagulum increases. The amount of NH40H needed to properly adjust the pH will depend in part on the par-ticular emulsifier system being used in the reaction mixture. Of course, other alkaline agents may be employed to adjust the pH of the reaction mixture, such as NaOH, KOH, etc. The choice of a particular alkaline agent depends upon the ingredients in the reaction medium.
The process of the present invention, wherein an electrolyte is employed in the reaction mixture and the product is tray dried, is conducted in the presence of a compound or compounds capable of initiating the polymerization reaction. Free radical yielding initi-ators, normally used for polymerizing olefinically unsaturated monomers, are satisfactory. The useful initiators or catalysts include, for example, the 1~38~50 g various peroxygen compounds, such as lauryl peroxide, isopropyl peroxydicarbonate, benzoyl peroxide, t-butyl hydroperoxide, t-butyl peroxypivalate, cumene hydro-peroxide, t-butyl diperphthalate, pelargonyl peroxide, 5 l-hydroxycyclohexyl hydroperoxide, and the like; azo compounds such as azodiisobutyronitrile, dimethylazo-diisobutyrate, and the like. Also, useful initiators are the water-soluble peroxygen compounds, such as hydrogen peroxide, persulfates, such as potassium per-sulfate, ammonium persulfate, and the like. The amountof initiator used will generally be in the range of from about 0.01~ to about 0.5% by weight, based on the weight of the monomer or monomers being polymerized, and pre-ferably from about 0.02% to about 0.1~ by weight.
In the present process, the initiator may be charged completely at the outset of the polymerization or it may be added incrementally to the reactor during the course of the polymerization reaction. However, it is preferred to charge the initiator at the outset by adding it to the monomer premix with the other ingredi-ents of the reaction mixture. This is advantageous when said premix is homogenized prior to introduction into the reactor. When adding the initiator to the monomer premix and then thoroughly mixing with high speed agi-25 tation or stirring, or when homogenizing the premix,such as when an alcohol(s) is employed in the reaction mixture, it is necessary to keep the temperature below the minimum temperature of reactivity of the particular initiator or initiators being employed. This minimum 30 temperature of reactivity of any one initiator is readily determinable by one skilled in the art and very often, is supplied by the initiator or catalyst manu-facturer. After introduction of the monomer premix into the reactor, the temperature is adjusted to that at 35 which the reaction is to take place.

~38~o The temperature of reaction of the instant emulsion polymerization process is important since the intrinsic viscosity (IV) of the resultant vinyl disper-sion resin is a direct function of the temperature of 5 reaction. That is the higher the temperature the lower the IV. Accordingly, the end use for the vinyl disper-sion resin to be produced will normally dictate the reaction temperature. For example, when producing vinyl dispersion resins to be used in coatings or in casting 10 flexible films, a lower temperature will be employed in order to attain a higher IV which is desirable ~or many coating applications and film-forming operations. We have found that for the end uses to which the vinyl dis-persion resins of this invention are particularly adapted, polymerization temperatures in the range of about 30C to about 70C are satisfactory. However, it is preferred to employ a temperature in the range of about 30C to about 55C.
Another factor, which must be considered with respect to the temperature of the reaction, is that of polymer buildup in the reactor. In general, as the temperature of reaction is increased, the polymer build-up in the reactor increases. However, the polymer buildup is not of the hard crusty type and can be re-moved by rinsing or hosing down with water and withoutopening the reactor when appropriate spray nozzles are installed in the reactor. On the other hand, even this buildup is controlled and reduced by the presence of the electrolyte in the reaction medium. In combination with the electrolyte, the walls of the reactor are kept cool during the polymerization reaction, especially during the early stages of the reaction when most of the build-up, if any, forms. The regulation of the temperature of the reaction can be accomplished by normal means, such as employing a jacketed reactor with circulating cool water or other liquid in the jacket. It is believed li38~o that a synergistic effect results from the use of the electrolyte with a cooled reaction medium in the early stages of the reaction cycle since polymer buildup is reduced. Repeated cycles can be run without cleaning the inner surfaces of the reactor between charges or cycles thus increasing the efficiency of the process and reducing the cost of producing vinyl dispersion resins having a wider scope of end uses.
Upon completion of the polymerization reaction, the vinyl dispersion resin is isolated in powder form, that is, in the form of discrete spherical polymer particles. This is accomplished by filtering the latex from the polymerization reactor in order to recover the friable aggregates of polymer, tray drying the filtered latex at a temperature in the range of about 23C to about 100C. under atmospheric pressure during the course of which the electrolyte comes off. The drying tempera-ture can be lower or higher than the limits of said range of temperature depending upon whether or not the drying step takes place under a vacuum or under positive pressure. The time of the tray drying step will depend upon the particular polymer being dried. However, the tray drying should continue until the water content of the polymer is about 0.1% by weight or lower. The time, 25 of course, will vary with the temperature being employed.
The important thing is not to subject the polymer to prolonged heating at elevated temperatures since such heating may deleteriously affect the quality of the polymer, such as discoloration, etc. After tray drying, 30 the friable aggregates of individual spheres of polymer particles that are found are crushed lightly or rubbed to separate the individual spheres and the dried polymer or resin is recovered in powder form. The powdered resin is then ready to be made into plastisols. It 35 should be pointed out that other forms or methods of drying may be used, such as rotary dryers, air jet ~i38150 dryer, fluid bed dryer, etc., so long as spray drying is not employed. Tray drying, however, is preferred.
Plastisols are made with the vinyl dispersion resins of the present invention by uniformly blending or 5 intimately mixing, by conventional means using heat and agitation, with 100 parts by weight of the vinyl disper-sion resin in the form of discrete spherical polymer particles, from about 30 to about 100 parts by weight of one or more plasticizers. The useful plasticizers may 10 be described as the alkyl and alkoxy alkyl esters of dicarboxylic acids or the esters of a polyhydric alcohol and a monobasic acid. As examples of such plasticizers, there may be named dibutyl phthalate, dioctyl phthalate, dibutyl sebacate, dinonyl phthalate, di(2-ethyl hexyl) phthalate, di(2-ethyl hexyl) adipate, dilauryl phtha-late, dimethyl tetrachlorophthalate, butyl phthalyl butyl glycollate, glyceryl stearate, and the like. The preferred plasticizers are the liquid diesters of ali-phatic alcohols having from 4 to 20 carbon atoms and di-basic carboxylic acids having from 6 to 14 carbon atoms.
The plastisols made from the vinyl dispersionresins of the present invention should have the desired yield and preferably with little or no dilatency. Yield is simply defined as resistance to flow and is normally determined numerically through viscosity measurements employing well known standard techniques. Normally such values are arrived at by calculation from viscosity measurements using a Brookfield Model RVF Viscometer according to ASTM method D1824-61T. Yield is determined from viscosity measurements of the plastisols at varying r.p.m.'s (revolutions per minute) after initial prepara-tion and at intervals of aging. The viscosity is measured in centipoises (cps.) at a temperature of 23C.
In the specific examples, that follow hereinafter, viscosity measurements were made at 2 rpm. and 20 rpm.
and are expressed as V2 and V20 respectively.

To further illustrate the present invention, the following specific examples are given, it being understood that this is merely intended in an illustra-tive and not a limitative sense. In the examples all parts and percents are by weight unless otherwise indicated.
EXAMPLE I
In this Example, a series of runs were made to show the various aspects of the present invention.
The recipes used and the conditions of reaction are set forth in the table which follows. In the table, all figures are in parts by weight based on the weight of the total composition.

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~.~38~0 In runs 2 and 3 above, where alcohols were employed in recipes, a monomer premix tank or vessel was evacuated. The premix tank was first charged with the water and then, under agitation, the electrolyte was 5 added followed by the emulsifier and then the alcohol mixture. The catalyst was added next, and lastly, the vinyl chloride. The temperature in the premix tank was controlled at about 25C, by means of a cooling jacket.
The mixture was agitated for about 15 minutes. There-10 after, the mixture, or monomer premix was passed througha Mantin Ganlin 2 stage homogenizer at a temperature of 25C into the polymerization reactor which had pre-viously been evacuated. The pressure in the first stage of the homogenizer was 600 psig. and in the second stage 15 was 700 psig. The contents of the reactor were then heated to the reaction temperature of 45C and held there throughout the reaction until the desired conver-sion was obtained. The reactor was then cooled, vented and the polyvinyl chloride (PVC) latex or slurry 20 was removed and dried~ Pertinent data is given in Tale II below.
In runs 1, 4 and 5 the ingredients were added to and mixed in the polymerization reactor. Further, the emulsifier was proportioned into the reactor during 25 the course of the reaction. In the case of runs 1 and 4, a PVC seed was added to the reactor on which the vinyl chloride was pverpolymerized to obtain a larger particle size. In the case of run 5, however, a small amount of emulsifier (sodium lauryl sulfate) was added 30 initially in place of the seed (PVC). In the case of runs 4 and 5, the temperature of the reaction mixture was held at 40C until about 58% to 60% conversion was reached and then the temperature was reduced to 35C and held there until the reaction was complete. Thereafter, 35 in each case, the reactor was cooled, vented and PVC
ltex or slurry was removed and dried.

~38i~o In order to determine the Brookfield Viscosity, plastisols were made with the resin or PVC of each run using the following recipe:

PVC 100 parts Dioctyl phthalate 40 parts Dioctyl adipate 30 parts Epoxidized soybean oil3 parts Barium-Cadmium-Zinc Phosphite 2 parts The data with respect to viscosity is recorded in the following Table II.

I o o Z I U ~ ~ Z

o o o o o ZI '3 ~

o o o o ,1 ~ o CO o o o ~ ~ ~ ~ ~ CO o ~ ~

H
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. ~ O ~ .a) .0 o ~ ~~ ~ ,, o ~ ~ ~ 0 z ~ 0 ~ ~ x ,1 a c~ a~ ~ o l 0 ~ :~ O H ~_ u~ a ~ E~ u~ m O ~l ~, As can be seen from the above results, the use of an electrolyte permits tray drying to give good dry cake break-up and superior plastisol properites.
EXAMPL~ II
In this Example, a series of runs were made to show the effect of varying the concentration of the electrolyte. The same polymerization procedure as in Example I was employed with the exception that homogen-ization was not used. The plastisols were also made as in Example I. The results are in the following table:

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~38.~so In the above Tables, under Slurry Viscosity, the term "Whipped Cream" is the ideal condition for the slurry or latex. In Table No. III it is noted that the important property of "Dry Cake Break-Up" was excellent or very good. The results clearly show the advantage of employing an electrolyte followed by tray drying.
It can thus be seen from the above description and examples that employing an electrolyte in the poly-merization medium, it is possible to filter and tray dry emulsion polymerization latices with a resultant im-provement in properties of the vinyl dispersion resins so produced. More importantly, spray drying and the harsh grinding step attendant thereto, which adversely affects polymer quality, is eliminated by the process of the present invention. Further, the process produces more dispersion resin per unit of time with improved properties and with substantial reduction of polymer buildup on the internal surfaces of the polymerization reactor. These factors all contribute to a low cost vinyl dispersion resin process. Numerous other advan-tages of the present invention will be apparent to those skilled in the art.
While the present invention has been described in terms of its specific embodiments, certain modifica-tions and equivalents will be apparent to those skilledin the art and are intended to be included within the scope of the present invention, which is to be limited only by the reasonable scope of the appended claims.

Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for producing polymers of vinyl and vinylidene halides and copolymers thereof with each other or either with one or more vinylidene monomers having at least one terminal CH2=C< grouping comprising forming a monomer premix containing the monomer or monomers to be polymerized, an aqueous reaction medium having a pH of about 7 to about 12, from about 0.01% to about 0.5% by weight of a free radical yielding catalyst based on the weight of 100 parts of monomer or monomers being polymerized, from about 0.05% to about 6.0% by weight of an electrolyte based on the weight of the monomer or monomers, an emulsifier for the polymerization system, at least one long straight chain saturated alcohol containing from 14 to 24 carbon atoms where-in the ratio of alcohol to emulsifier is equal to or greater than 1.0, homogenizing said premix at a temperature below the reactivity of the catalyst or catalysts employed, passing said homogenized premix to a reaction zone, emulsion poly-merizing said homogenized premix in said zone at a temperature in the range of about 30°C to about 70°C to form friable agg-regates of individual spheres of polymer particles, maintain-ing the pH in the reaction zone in the range of 7 to about 12 until the reaction is complete, removing the polymer emul-sion from said reaction zone and filtering the same to recover said friable aggregates of polymer, tray drying the polymer and friable aggregates of polymer while removing the electro-lyte therefrom, and lightly crushing said friable aggregates to form individual spheres of polymer particles, and wherein polymer buildup in said reaction zone is reduced.

2. A process as defined in Claim 1 wherein the emulsifier is the ammonium salt of a high fatty acid contain-ing from 8 to 20 carbon atoms.

3. A process as defined in Claim 1 wherein the monomer in the premix is vinyl chloride.

4. A process as defined in Claim 1 wherein the alcohol is a mixture of C14 and C18 alcohols.

5. A process as defined in Claim 2 wherein the fatty acid is lauric acid.

6. A process as defined in Claim 1 wherein the catalyst is tert-butyl peroxypivalate.

7. A process as defined in Claim 1 wherein the electrolyte is (NH4)2CO3.

8. A process as defined in Claim 1 wherein the tray drying of the polymer is conducted at a temp-erature in the range of about 23°C to about 100°C at atmospheric pressure.

9. A process as defined in Claim 1 wherein the size of the dried individual spheres of polymer particles is in the range of about 0.1 micron to about 10.0 microns.

10. A process as defined in Claim 1 wherein the electrolyte is CaCO3.

11. A process as defined in Claim 9 wherein the monomer in the premix is vinyl chloride.

12. A process as defined in Claim 11 wherein the electrolyte is (NH4)2CO3.

13. A process as defined in Claim 12 wherein the emulsifier is ammonium laurate.

14. A process as defined in Claim 13 wherein the catalyst is tert-butyl peroxypivalate.

15. A process as defined in Claim 14 wherein the pH in the reaction zone is maintained in the range of about 8.0 to about 10.5.

16. A process as defined in Claim 15 wherein the size of the dried individual spheres of polymer particles is in the range of about 0.2 micron to about 2.0 microns.

17. A process as defined in Claim 16 wherein the alcohol is a mixture of C14 and C18 alcohols.

18. A process as defined in Claim 1 wherein the monomers in the premix are vinyl chloride and vinyl acetate.

19. A process as defined in Claim 18 wherein the electrolyte is (NH4)2CO3.