CA1045271A - Process for making emulsion polymerized preplasticized vinyl resins - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
There is disclosed a process for preparing preplanti-cized vinyl resins by conducting the polymerization reaction of the vinyl monomer or monomers in the presence of a plasticizer therefor while employing an emulsion polymerization technique.
In said polymerization reaction the plasticizer and vinyl mono-mer or monomers are thoroughly mixed together prior to the start of the polymerization reaction and then said mixture is homogenized prior to the start of the reaction.

Description

10~5i~71 This invention relates to a process for making emulsion polymerized preplasticized vinyl resins.
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 at elevated tempera-tures of certain plasticizer, such as dioctyl phthalate, and the like. It has also been suggested to prepare vinyl resins by polymerizing the monomers in the presence of a plasticizer.
However, such suggestions and the disclosures thereof have been general in nature with no suggested details of how this objective might be specifically accomplished.
One of the problems encountered heretofore when mixing a plasticizer with a vinyl resin has been the poor colloidal stability of the resultant composition. Further, there is a low limit as to the amount of plasticizer that can be used and still obtain a product that is workable and not a sticky mass. In-addition, the plasticizer is easily extractable from the vinyl ':' resin and also has a tendency to migrate. Due to all these poor properties, vinyl resin latexes have poor shelf-life.
Merely preparing vinyl resins by polymerlzing in the presence of a plasticizer is not enough. Certain important steps must be followed in order to achieve the desired result, namely, to incorporate sufficient plasticizer to give the .~ .
~ i desired result with good colloidal stability and good heat and ,: i ;rl light stability.
~ We have unexpectedly found that preplasticized vinyl ; ~i .
resins can readily be made by polymerizing the vinyl monomer or monomers while in intimate admixture with a plasticizer therefor using an emulsion polymerization system. Most importantly, and particularly when significant amounts of plasticizer are ~ employed, the vinyl monomer or monomers and the plasticizer `, are homogenized prior to introduction into the reaction vessel.

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1()45271 -`
Thorough mixing prior to starting the polymerization reaction is imperative, otherwise coagulation will result. This new - process is referred to throughout the present application as ; .:
~ "plastimerization" for purposes of convenience.
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The invention relates to a process for producing preplasticized polymers of vinyl and vinylidene halide 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 of the monomer or monomers to be polymerized, from about 5 parts to about 100 parts by weight of a plasticizer for the finished polymer ~; based on 100 parts by weight of the monomer or monomers being `
;~ polymerized, a suitable emulsifier for the polymerization re-`~l action, and the aqueous reaction medium, homogenizing said premix to a particle size in the range of 0.5 to 15 microns with most of the particles being left at 2 microns, passing ' said homogenized premix to a reaction zone, emulsion polymeriz-,~ ing said homogenized premix in said zone in the presence of :; catalytic amounts of a suitable catalyst therefor and at a `~, 20 temperature below the glass transition temperature of the ,- l.
polymer or copolymer being produced, and thereafter recovering the preplasticized polymer or copolymer.
In the present invention, "vinyl resin" refers to polymers and copolymers of vinyl and vinylidene halides, such as vinyl chloride, vinylidene chloride, and the like. The vinyl halides and vinylidene halides may be copolymerized with each other or either 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 mentioned the ~ olefinically unsaturated carboxylic acids, ~t. -2-.... ~, - ,: . : . ,, ~ , - 104S27~
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such as acrylic acid, methacrylic acid, ethacrylic acld, ~-chloroacrylic acld, ~-cyanoacryllc acid, and the like esters of acrylic acid, such as methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, cyanoethyl acrylate, and the llke, esters of methacrylic acid, such :
as methyl methacrylate, butyl methacrylate, and the llke, nitriles, such as acrylonitrile and methacrylonltrlle, acrylamide, such as methyl acrylamide, N-methylol acrylamide, ~ :
N-butoxy methacrylamide, and the like; vinyl ethers, such as ethyl vinyl ether, chloroethyl vinyl ether, and the like, the vinyl ketones, styrene and styrene derivatives including ~- :
1~ 1 methyl styrene, vinyl toluene, chlorostyrene, and the like, vinyl naphthalene, allyl and vinyl chloroacetate, vinyl acetate, ~.
vinyl pyridene, methyl vinyl ketone, diolefins, including buta- -~
~:i diene, isoprene, chloroprene, and the like, and mixtures of any .:; . .
.~' of these types of monomers and other vinylidene monomers copoly-merizable therewith including esters of maleic and fumaric ~ acid, and the like, and other vinylidene monomers of the types .1 known to those skilled in the art. The present invention is particularly applicable to the manufacture of resinous latices ~-.':,. -. :
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, 1~4SZ71 made by t~e polymerizatlon, ln the presence of ~ sultable pla8-ticlzer there~sr, of vlnyl chloride or vlnylldene chloride alone :
; or in admixture with one or more vinylidene monomers copolymer-izable therewith in amounts as great as about 80~ by weight, based on the weig~t of the monomer mixture. The most preferred vinyl resin is polyvinyl chloride and the invention, for sim-plicity and convenience, will be described in connection there-with, it being understood that this is merely intended in an illustrative sense and not limitative.
The present process for preparing vinyl polymers or resins is by means of an emulsion polymerization technique in an aqueous medium in the presence o~ a plasticizer for the par-ticular vinyl polymer being prepared. Among the various plasti-,, . .~
ciæers that may be employed in making the vinyl polymers are . .
the organic phosphoric esters such as tricresyl phosphate, : ~i " triphenyl phosphate, isodecyl diphenyl phosphate, tributoxy ethyl phosphate, and the like; phthalic esters, such as dioctyl :i phthalate, dimethyl phthalate, dibutyl phthalate, dilauryl `-~ phthalate, dimethyl tetrachlorophthalate, butyl phthalyl butyl glycollate, and the like. In fact, any known plasticizer for polymeric vinyl halides may be employed in the polymerization i;~ reaction. It has been found that from about 5 parts to about ~-- ~
100 parts by weight o~ plasticizer, based on 100 parts by weight of monomer or monomers being polymerized can be charged as a polymerization ingredient. Usually an amount o~ plasticizer in the range of 15 parts to 90 parts by weight is suf~icient. When :$ amounts of plastlcizer greater than 100 parts by welght are em-ployed, the polymerization rate and the degree of conversion are adversely a~fected.
While the amount of plasticizer employed in the plas-timerization process is limited for practical purposes, further plasticizer can be incorporated in the ~inished plastlmerized , ~

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1~4S~71 vlnyl polymer or resin. The polymers produced by the process of the present inventlon have an unusually high afflnity to plasticiPers. Thls is believed to be due to the microstructure of the polymer particles and they seem to be nDre open struc-tured. In any event, it is possible to incorporate further plasticizer in the finished polym~r, by usual means, in varying amounts up to as high as 150 parts by weight of total plastici-zer based on the weight of 100 parts of monomer or monomers ori-ginally polymerized. By totaI plasticizer is meant the plasti-cizer in the polymer from the plastimerization process plus that added to the finished polymer. This feature of the poly-mers produced by the present invention makes them particularly attractive as blend resins, such as in polyblends with nitrile rubbers.
i 15 The aqueous medium used in making the vinyl polymers by the present inventive emulsion polymerization system usually contains an emulsifier. When emulsifiers are used to prepare the vinyl polymer latices, the general types of anionic and non-ionic emulsifiers are employed. Excellent results have been obtained when using anionic emulsifiers. Useful anionic emul-sifiers include alkali metal or ammonium salts of the sulfates of alcohols having from a to 18 carbon atoms, such as sodium lauryl sulfate, ethanolamine lauryl sulfate, ethylamine lauryl sulfate, and the like; alkali metal and ammonium salts of sulfon-ated petroleum and paraffin oils; sodium salts of aromatic sul-fonic acids, such as dodecane-l-sulfonic acid and octadiene-l- -sulfonic acid; aralkyl sulfonates, such as sodium isopropyl ben-zene sulfonate, sodium dodecyl benzene sulfonate, sodium iso-butyl naphthalene sulfonate, and the like; alkali metal and ammonium salts of sulfonate dicarboxylic acid esters, such as sodium dioctyl sulfosuccinate, disodium-n-octadecyl sulfosuc-cinate, and the like; alkali metal and ammonium salts of free 1045Z7~
acld o~ complex organlc mono- and dl-phosph~te esters, and the like. Nonionic emulsifler8, such as octyl- or nonylpnenyl polyethoxyethanol, may also be used. Vinyl polymer latices having excellent stability are obtained when employing the al-kali metal and ammonium salts of aromatic sulfonic acid, ar-alkyl sulfonates and long chain sulfonates.

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The amount of emulsifier employed may range in amount up to about 6% or more by weignt, based on the weight o~ 100 parts of monomer or monomers being polymerized. Tne emulsifier . , is pre-mixed with the monomer and plastlcizer prior to the start of the polymerization, particularly when the premix is nomogen-; ized, as explained more fully hereinafter. However, tne emul-. .
; sifier may be added incrementally or by proportioning through-out the polymerization reaction.

`~l 15 In carrying out the emulsion polymerization of vinyl `;~ monomers in accordance with the present invention in the presence ~ of a plasticizer for the polymer being produced, the polymeriza-. ,1 .
tion temperature is not critical. However, it is imperative that the reaction be conducted at a temperature below the glass transition temperature (Tg) of tne polymer being produced. If the temperature of polymerization is not below the Tg of the -` polymer, coagulation will result. For example, t~e Tg of poly- ~ -., .
vinyl chloride is 85C. and therefore, the polymerization of vinyl chloride must take place below about 85C. in order to produce a satisfactory product. We have found that temperatures . in the range of about 15C. to about 75C. are satisfactory for -. . .; , . :, .
polymerizing the vinyl monomers in accordance with the instant ~ A .

< process. Preferably, a temperature in the range of about 40C.

to about 55C. is employed.

The plastimerlzation process described herein is con-, ducted ln the presence of a compound capable of initiating the - polymerization reaction. Free radical yielding initlators, :.
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, l~SZ71 normally used for polymerizlng ole~inically uns~turated monomers, ~, are satisfactory for use in the present process. These inltia-tors or catalysts include, for example, the various peroxygen compounds, such as persulfates, benzoyl peroxide, t-butyl hydro-peroxide, cumene hydroperoxide, t-butyl diperphthalate, pelar-gonyl peroxlde, l-hydroxycyclohexyl hydroperoxide, and the like;
azo compounds, such as azodiisobutyronitrile, dimethylaZodiiso-butyrate, and the like. Particularly useful initiators are the . . , water-soluble peroxygen compounds, such as hydrogen peroxide, lauryl peroxide, isopropyl peroxydicarbonate, and the like, and the sodium, potassium and ammonium persulfates used by them-; /, selves or in an activated redox system. Typical redox systems .~ .
include alkali metal persulfates in combination with a reducing substance, such as sodium sulfite or sodium bisulfite, a reduc-ing sugar, dimethylamino propionitrile, a diazomercapto compound ~- and a water-soluble ferricyanide compound, or the like. Heavy metal ions may also be used to activate the persul~ate catalyzed polymerization. Particularly useful are alkali metal and am-monium persulfate. The amount of initiator used will generally be in the range between about 0.1% to about 3.0% by weight, based on the weight of 100 parts of monomer or monomers being .. '3 polymerized, and preferably between about 0.15~ and about 1.0%
by weight.
Generally, the initiator is charged completely at t~e outset of the polymerization. However, it is often advantageous ' t the employ incremental addition or proportioning of the initi-i ator tQroughout the polymerization reaction. When the initiator is charged at the outset it is added to the monomer premix with the other ingredients of the reaction mixture. This is particu-larly true when said premix is homogenized prior to lntroduction into the reactor. However, when adding the initiation to the premix and then homogenlzing; it is necessary that the tempera-, ...
.
., 1~45Z71 ture durlng the premlxing and homogenlzatlon steps be ~ept below ; the mlnlmum temperature of reactlvity of the partlcular inltla-tor or inltiators being employed. For example, when maklng a premix oP vinyl chloride, water and suitable emulsifiers, and ':~
then adding isopropyl peroxydicarbonate thereto, the temperature .;
is maintained at 20C during the mixing step and then during the homogenization step. Upon introduction of the homogenized mixture into the polymerization reactor, the temperature is ' then raised to that at which the reaction i5 to take place.
~ 10 One o~ the most important aspects of the process of .tl the instant invention is the step o~ homogenization. T~e plas-ticlzer must be thoroughly and intimately mixed with the mono- ~
mer or monomers when more than one is employed, prior to the ~-~ commencement of the polymerization reaction. This mixture is ~ 15 referred to as the monomer premlx and will also contain the water or reaction medium. Further, any emulsifier being employed will ~;~ likewise be added to the premix, all of the ingredients being `~ added with suitable agitation. If the catalyst or initiator is to be added prior to the commencement o~ the polymerization reaction, it is the last lngredient added to the premix. As has been pointed out, when adding the catalyst the temperature of 1 the premix should be below the minimum temperature at which the -' catalyst becomes reactive. Further, when a particular catalyst being employed is not water-soluble, it should be added to the premix in a suitable solvent therefor which will insure emulsi- - -~ication in the premix and even distribution. Needless to say, any such solvent should be inert to the reaction ingredients and reaction conditions. For example, when employing isopropyl peroxydicarbonate as a catalyst, it is added to the premix in hexane. In the Examples, which follow hereinafter, wherever ' isopropyl peroxydlcarbonate was used it was added to the premix or to the reactor in hexane.

.

1~4SZ';'l The monomer premix, or reaction premix, is thereafter subjected to ~omogenization prior to entering the polymerization step or reactor. Any convenient means of homogenizing may be employed, We have found that a one stage Manton-Gaulin homo-genizer (Model 31M-3TBA) is a convenient apparatus for homogen-izing the premixes contemplated by the instant invention. The ` premix leaves the homogenizer and goes directly into the reac-~.:
tion vessel which preferably contains an inert atmosphere, `~ such as nitro~en.
Homogenization is most important and necessarg with increasing plasticizer content in the premix to be polymerized.
Irrespective of the content of plasticizer used the best re-. . .~
;`~' sults, i.e., the most stable polymer latices, are obtained when the monomer and plasticizer are premixed and then homogenized `'5 15 prior to polymerization. Further, in addition to latex in-, stability, polymer buildup on the reactor walls occurs to a very detrimental extent when homogenization is not employed.
i Homogenization is necessary in order to assure the ' proper particle size. A particle size in the range of 0.5 to 15 microns is desirable, with most of the particles being less than 2 microns. It is to be noted that the particle size in-creases as the amount of plasticizer employed increases. How-ever, it is necessary to stay within the range of particle size ,,. ~ .
given in order to form a stable emulsion.
We have found that before homogenization the particle size of the monomer premix or emulsion will be in the range o~

2 to 40 microns with no plasticizer present and in the range of 10 to 50 microns with 90 parts by weight of plasticizer pre-sent. On the other ~and, after homogenization the particle size of the same premix or emulsion decreases to 0.5 to 2 mi-crons with no plasticizer present and to 0.5 to 15 microns with 90 parts by weight of plasticizer present. In the latter * Trademark 9 /

: ~045271 case most of the particles are less than 2 microns in size.
In the plastimerization process of the present inven- ~ -tion, pH is not critical provided that the homogenization step is applied. Good results have been obtained when using homo-genization in the present process in a pH range of from about

3 to about 10. However, if one is polymerizing a monomer pre-mix without homogenization then pH is critical and also, the particular emulsifier system emp:Loyed is important. In such a case, a highly alkaline reaction medium is required with a pH
, 10 of around 10. Also, the exact level of plasticizer that can be ; used without homogenization depends on the emulsifier system i used and on the pH of the polymerization reaction. For example, .,j :
high pH polymerizations using ammonium laurate emulsifier are better suited for plastimerization compared to sodium lauryl sulfate based polymerizations. However, when using homogeniza-. .... :
tion, as described herein, then any pH or emulsifier system may be employed and obtain stable plasticized vinyl resin latices.
-~ It should be noted that in addition to the choice of ,~ ;
the proper emulsifier system, the pH of the reaction system can be adjusted as by the use of ammonium hydroxide,and the like.
In addition one may employ buffering agents in the reaction mix-ture, such as trisodium phosphate, tetrasodium pyrophos~hate, ; and the like. In any event, the plasticized vinyl polymer la-tex produced may subsequently be adjusted to any desired pH by suitable means. ~-, To further illustrate the present invention, the fol-lowing specific examples are given, it being understood that - this is merely intended in an illùstrative and not a limitative -~ sense. In the examples all parts and percents are by weight unless otherwise indicated.
EXAMPLE I
In this example, two runs, along with a control run . ~ . - . . . .
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1(145Z71 were made to show that the plasticizer must be thoroughly mixed with the monomer prior to the start of the polymerization reac-tion. The recipes employed in the polymerizations are given in the following table in which all the figues are in parts by weight based on the weight of the total composition.
Table I
~I Run No. 1 2 Control Vinyl chloride 100 100 100 Dioctyl phthalate 15 15 15 - 10 Water (demineralized)200 200 200 Isopropyl peroxydi- o.o6 o.o6 o.o4 carbonate Sodium lauryl sulfate 4 - 4 (emulsi~ier) ~ 15 Straight-chain dodecyl - 4 -j benzene sodium sul-,'.! ~ate (emulsifier) ` In each of runs 1 and 2 a monomer premix tank or vessel was charged with vinyl chloride and the plasticizer dioctyl phthalate thoroughly mixed therein. ~hile agitating this mix-ture, the water and emulsifier were added. Therea~ter, the mix-ture was cooled to 20C. and the isopropyl peroxydicarbonate - added thereto. The tank was evacuated and nitrogen introduced.
The entire mixture was then agitated for 15 minutes under a nitrogen atmosphere. Thereafter the mixture (monomer premix) -was passed through a homogeniæer into a polymerization reactor containing a nitrogen atmosphere. The homogenizer was a one ~ -stage Manton-Gaulin!homogenizer (Model 31M-3TBA) operated at ~
,' , 750-1000 psi stage pressure. Therea~ter the contents of the reactor were heated to the polymerization temperature and the ~;~
reaction allowed to proceed to the desired conversion.
In the case o~ the control, all ingredients, except , the plasticizer dioctyl phthalate were charged to the reactor and mixed. A~ter the polymerization reaction had proceeded to 50% conversion of monomer to polymer latex, the plasticizer was metered into the reactor. The polymerization conditions and results o~ all the runs are given in the ~ollowing table:
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",, : 1045271 Table II
Run ~o. 1 2 Control Reaction Temp. C. 51 51 51 s ;~ Reaction Time, hours 12 16 Coagu: .ated Total solids, % 31.5 33 Conversion, % 84 88 Coagulum, % O O
i,, Plasticizer content. % 14.7 14.7 Slurry condition OK OK
pH 7.1 3.3 ;, Thus it can be seen that the addition of plasticizer after the start of polymerization does not work. It is believed the re~
sults are self-explanatory.
EXAMPLE II
The purpose of this example was to show the criticality ~ -of homogenization to obtain good polymer latices containing the appropriate amount of plasticizer and without having to ad~ust ~ -~
the pH. Xere again the recipes employed are given in the table which follows in which all figures are in parts by weight based ~-~', 20 on the weight of the total composition. Also, the runs made in ~ ' this example show the importance of homogenization wit~ increas-`'`i~ ing amounts of plasticizer and it is absolutely necessary when one employs more than about 60 parts of plasticizer to obtain ~; satis~actory results.
Following the procedure outlined in Example I, Runs 3 and 4 were prepared the same way except that the K2S20g was placed in the polymerization reactor prior to the introduction of the homogenized premix. In the case of the Controls 3 and

4, the same procedure was followed except that the premix was not homogenized prior to introduction into the polymerization ..~
~3 reactor. The recipe, polymerization conditions and results, . ,~
,~ in each case, are set out in the following table: ~-$~

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1~45Z71 It can readlly be 3een from the ~bove Table III that without homogenlzatlon no satls~actory product i8 obtalnable when employing high amounts of plasticizer (gO parts). Further, ad~u~tlng the pH to the highly alkaline side, as in Control 3, with NH40H did not help either. On the other hand, such a high pH does not affect the resultant product when the premix is homogenized, as witness Run 3. Without homogenization and with-, '3 out pH ad~ustment, it is impos~iblè to obtain a product, as witness Control 4.
EXAMPLE III -.
In this example a series of runs were made to show that homogenization is essential to secure a good latex in both batch polymerization and in a polymerization employing prem~x propor-tloning. Further, these runs also show that the exact level of plasticizer that can be used without homogenization depends on the emulsifier system and on the polymerization pH. In Table IV that follows the conditlons of reaction, recipe and results are set out in each case. Making of the premlx and homogeniza-tion was carried out as described in Example I. Adding all the , 20 material to the reactor and then polymerizing is referred to as -~ "batch polymerization" and adding the premix to the reactor ,;~ .
continuously or intermittently during the reaction is referred , to as proportioning. In Table IV several processes are referred .;~
; to whlch are identified as ~ollows:
(1) Batch polymerizatlon of homogenized premix.
(2) Batch polymer~zation of non-homogenized premix.
(3) Proportionlng of homogenized premix.
(4) Proportioning of non-homogenized premix.
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1~J45Z71 Looking at the Table above lt can be seen that homo-genization of t~e premix give6 superior results as witness runs 6, 8, 10 and 14. This is so irrespective of the emulsifier used and the pH of the system.
EXAMPLE IV
In this example a series of runs were made to illus- ~ -trate that the present invention, when employing homogenization of the monomer-plasticizer premix prior to the start of poly-merization, is not limited to the use of any particular emulsi-fier. Further, the inventive process is not limited to a parti-cular polymerization pE nor to a particular initiator or cata-lyst system. Again the general procedure outlined in Example I
was followed in each o~ the runs made. In each run the proce-dure involved the batch polymerization of a homogenized premix.
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--` 15 The following Table V contains all the data with respect to ` recipe, polymerization conditions and results.
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It i8 slgniflcant to note that the pH ln the above runs varled from 3.0 to 10.0 which did not affect the resultant ~; polymer latices when homogenization of the premix is employed.
EXAMPLE V
Two runs were made to demonstrate that the plastimeri-zation process should be conducted at a temperature below the glass transitlon temperature (Tg) o~ the polymer being produced.
In this example, in making a polyvinyl chloride latex, the temp- -r erature of polymerization should be below 80C. The general procedure of Example I was followed using a batch polymerization technique of a homogenized premix. The tabulation of data and results are in the following Table VI.
Table VI
, , Run No. 20 21 ~ 15 Vinyl chloride 100 100 .j Dioctyl phthalate 90 90 Sodium lauryl sulfate 4.0 4.0 .3 Water (demineralized) 200 200 Isopropyl peroxydicarbonate 0.1 0.005 Reaction time, hours 9 22 .~ Reaction temp., C. 51 80 Total solids, % 34 36 Coagulum, ~ 0 0 , pH 3.8 -The present invention offers many advantages such as the ability to produce vinyl resin latices having greatly im-proved colloidal stability. This property increases the shelf-aging of the vinyl resin latex. Further, the process described herein results in a more efficient incorporation of plasticizer in the polymer latex and more importantly,results in a reduced plasticizer extractability and migration.
The plastimerized vinyl resins produced by the pre-sent process are particularly useful in blending with latices o~ nitrile rubber, and the like, since it is possible to accom-, 35 plish such blending on a roll mill without sticking. Further, when non-flammable properties are desired in the preplasticized vinyl resin, it is a simple matter to choose a suitable plasti--~ , . ~ . - , 1~)4Si~71 clzer which will result ln ~uch propertle~. Numerous other advantages o~ the present inventlon will be readlly apparent to those skilled in the art.
While the present invention has been described in

- 5 terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present in-vention, which is to be limlted only by the reasonable scope of the appended claims.

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Claims (13)

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

1. A process for producing preplasticized polymers of vinyl and vinylidene halide 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 of the monomer or monomers to be polymerized, from about S parts to about 100 parts by weight of a plasticizer for the finished polymer based on 100 parts by weight of the monomer or monomers being polymerized, a suitable emulsifier for the polymerization reaction, and the aqueous reaction medium, homogenizing said premix to a particle size in the range of 0.5 to 15 microns with most of the particles being left at 2 microns, passing said homogenized premix to a reaction zone, emulsion polymerizing said homogenized premix in said zone in the presence of catalytic amounts of a suitable catalyst therefor and at a temperature below the glass transition temperature of the polymer or copolymer being produced, and thereafter recovering the preplasticized polymer or copolymer.

2. A process as defined in claim 1, wherein the monomer in the premix is vinyl chloride.

3. A process as defined in claim 1, wherein the plasticizer is dioctyl phthalate.

4. A process as defined in claim 1, wherein the emulsifier is sodium lauryl sulfate.

5. A process as defined in claim 1, wherein the catalyst is isopropyl peroxydicarbonate.

6. A process as defined in claim 1, wherein the polymerizing temperature is in the range of about 15°C. to about 75°C.

7. A process as defined in claim 1, wherein the catalyst is added to the monomer premix and the temperature of the premix is maintained below the minimum temperature of reactivity of the catalyst prior to entering said reaction zone.

8. A process as defined in claim 2, wherein the plasticizer is dioctyl phthalate.

9. A process as defined in claim 8, wherein the emulsifier is sodium lauryl sulfate.

10. A process as defined in claim 2, wherein the catalyst is isopropyl peroxydicarbonate.

11. A process as defined in claim 10, wherein the tempera-ture of reaction is below 80°C.

12. A process as defined in claim 11, wherein the emulsifier is sodium lauryl sulfate.

13. A process as defined in claim 12, wherein the plasticizer is dioctyl phthalate.