CA1065540A

CA1065540A - Process for producing dispersion resins by homo or copolymerization of vinyl or vinylidene halides

Info

Publication number: CA1065540A
Application number: CA254,636A
Authority: CA
Inventors: Bela K. Mikofalvy; Thomas J. Doyle
Original assignee: BF Goodrich Corp
Current assignee: Goodrich Corp
Priority date: 1975-07-01
Filing date: 1976-06-11
Publication date: 1979-10-30
Also published as: ES449224A1; ZA763690B; AU1502276A; JPS526785A; FR2316251A1; SE7607419L; GB1529248A; NL7606888A; DK290376A; DE2628665A1; NO762244L; BE843626A; BR7604279A; PH11712A; FR2316251B1

Abstract

ABSTRACT OF THE DISCLOSURE

There is disclosed a process 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 temperatures preferably below about 48°C., i? the presence of an emulsi-fier system comprising the ammonium salt of a high fatty acid containing from 8 to 20 carbon atoms and at least one long chain alcohol containing from 14 to 24 carbon atoms wherein the ratio of alcohol to emulsifier is equal to or grater than 1.0 and wherein the reaction ingredients are thoroughly mixed, and preferably homogenized, prior to polymerization. The pro-cess produces paste resins having improved heat stability and flow properties and capable of producing films having high clarity and improved water resistance. More importantly, polymer build-up in the reactor is substantially reduced and multiple polymerizations can be run in the reactor without opening the same.

Description

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This invention relates to the production o~ vinyl and vinylidene halides and copolymers thereof.
It is well known that vinyl resins may be plasti-cized 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 dispersion resins or paste resins and are usually made employing an emulsion polymerization ~ 10 technique, although a suspension polymerization process can - be used.
When the vinyl resin is mixed or blended with a plasticizer, it is referred to as a "latex". By virtue of the flowability of the latex it can be processed into various useful products. The latices can be used in making molded products, coatings, and the like. Accordingly, the disper-.
sion resin must be capable of being mixed with a plasticizer ;~ - easily and uniformly to form low viscosity latices which are stable and of good clarity and containing particles of uni-~20 form and proper size.
With the customary emulsion polymerization pro-cesses, suitable latices have been difficult to obtain since ~-~ the latices usually contain particles of varying size and are either too fine or too large. Various proposals have ;~ 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 pro-posed. Also, varying the conditions of polymerization have been suggested. However,-in most of these cases, too much coagulation occurred with the resulting latex containing too ~ .

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1~ - 1 ~065540 much coagulum or partially agglomerated particles which precipitate reducing the yield. Further, the shelf-life 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.
Another frustrating and detrimental problem in the commercial production of polymers and copolymers of vinyl and vinylidene halides, when polymerized alone or with other vinylidene monomers having a terminal CH2=CK
group, is the formation of undesirable polymer build-up on the inner surfaces of the reactor. This deposit or build-up of polymer on said reactor surfaces not only interferes with heat transfer, but also decreases pro-ductivity and adversely affects polymer quality, such as producing finer particles than desired with the resultant adverse effect on viscosity. Obviously, this polymer build-up must be removed. If not, more build-up occurs rapidly on that already present resulting in a hard, insoluble crust.
In the past is was the practice to have an oper-ator enter the reactor and scrape the pol~mer build-up off the walls and off the baffles and agitators. This opera-tion was not only costly, both in labor and down-time of the reactor, but presented potential health hazards as well. Various methods have heretofore been proposed to remove the polymer build-up, such as solvent cleaning, various hydraulic and mechanical reactor cleaners, and the like, but none has proved to be the ultimate in polymer build-up removal. It would be desirable, of course, to have ~' ~L~6S540 a polymerization process in which polymer build-up does not occur. Unfortunately, none of the known emulsion polymerization processes are capable of solving ~his, and the other problems reiterated above. There is a de~inite need in the art for a polymerization process which meets all these criteria.
It has unexpectedly been found that when a proper combination of pol~merization conditions and ingredients are employed, latices can be produced which have all the necessary and desirable properties and with little or no polymer build-up. The process of the present invention comprises conducting the polymerization reaction of the vinyl monomer or monomers in an aqueous medium, using an oil-soluble polymerization catalyst or initiator, at a temperature in the range o-f about 30C to about 70C, and preferably below about 48C, in the presence of the ammonium salt of a high fatty acid containing from 8 to 20 carbon atoms, and at least one long chain alcohol con-taining from 14 to 2~ carbon atoms, wherein the ratio of alcohol to emulsifier is equal to or greater than 1.0, and wherein the reaction ingredients are thoroughly mixed prior to polymerization. The dispersion resins, or paste resins, so produced have improved flow properties and heat stability and are capable of producing films having excel-lent clarity and improved water resistance. When employing said process, the polymer build-up in the reactor i9 sub~
stantially reduced and multiple polymerizations can be run in the reactor without opening the same thereby substantially reducing the amount of vinyl chloride in the surrounding atmosphere.

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The aqueous medium i9 suitably an alkaline medium, the pH in the reaction zone being maintained in the range of about 7.0 to about 12Ø
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 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, such as acrylic acid, methacrylic acid, ethacrylic acid, ~-chloroacrylic acid, a-cYanoacrYlic acid, and the like, esters of acrylic acid, such a methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, cyanoethyl acrylate, '~

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and the like; esters of methacrylic acid, such as methyl meth-acrylate 3 butyl methacrylate t and the like; nltriles such as acrylonitrile and methacrylonitrile; acryl~nides, such as methyl acrylamide, N-methylol acrylamide, N-butoxy methacryl-amide and the like; vinyl 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, chlorostyrene, and the like; vinyl naphthalene, allyl and vinyl chloroacetate, vinyl acetate, vinyl pyricline, methyl vi~yl ketone, and other vinylidene monomers of the types known to those skilled in the art. The present inven tion is particularly applicable to the manufacture o~ vinyl dispersion resins ~r pastes made by the polymerization of vinyl chloride or vinylidene chloride alone or in admixture with one or more vinylldene monomers copolymerizable there-with in ~mounts as great as about 80% by weight, based on the weight of the monomer mixture. The most preferred vinyl dis-per ion resin is polyvinyl chloride and the in~ention, for simplicity and convenience, w~ll be described in connection o therewith, it being understood that this is merely intended ~ in an illustrative sense and not limitative.
; The present process for preparing vinyl dispersion resins is by means of the emulsion polymerization technique ,, in an aqueous medium. ~owever, in the lnstant invention it is necessary that certain ~peci~ied materials are present in the polymerizatiun medium and certain co~ditions o~ polymeri-zation must be met in order to achieve the desired results~
In the polymerization recipe it is necessar~ to employ a fatty acid derivative as an emulslfier. In order to get the proper and improved water resistance and heat stabllity in ~llms made from plastisols or latices o~ the vinyl dispers~on resins the ammonium salt o~ a long chain SS4~
saturated fatty acld is employed. We have found that if you use the alkali metal salts of the fatty acids you get dis-colored or yellow films from said plastisols. Further, the water resistance of films ~ails even if only traces of alkali metal is present. That is to say there must; be a complete absence o~ alkali metal ions. The saturatecl fatty acids use~ul in the present invention may be either natural or synthetic and should contain from 8 to 20 c:arbon atoms. As examples of such acids there may be named lauric, myristic, palmitic, marganic, stearic, and the like, beef tallow, coconut sil, and the like. The ammonium salt emulsi~ier is employed in ~n amount in the range of aboutO.5~ to about 40~ by weight based on the weight o~ the monomer or monomers being polymerized. It is also possible to use mixtures of the am~onium salts of the fatty acids in the emulsifier system.
The ammonium salt can ~e made by mixlng the ~atty acid and ammonium hydroxide, separating the salt and adding to the polymerizatlon medium in usual fashion. However, it is preferred to form to ~onium salt in situ; that is, the fatty acid and am~onium hydroxide are added separately to the pol~merization mixture or medium wherein they react to ~orm the salt. An excess o~ ammonium hydroxids over the equimolar amount wit~ the fatty acid should be employed.
Z5 This excess helps to maintain the reaction medium on the al~
kaline side which is important, as discu~sed below.
In addition to the ammonium salt of a long chain fatty ac~d emulsifier, a long chain saturated alcohol con-~ taining fro~ 14 to 24 carbon atoms is employed in co~bination therewith, Examples o~ such alcohol are tetradecanol, penta-decanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, ei~osanol, heneicosanol, docosanol, tricosanol, tetracosanol, ~ 6~5~
and the like. Mixtures o~ the alcohols can be employed.
For example, a 14 carbon alcohol and an 18 carbon alcohol.
Also, lower carb~n content alcohols can be ~ployed when mixed with the longer chain alcohols. For example, a mlx-ture of` dodecanol and octadecanol.
While a ratlo o~ alcohol to the a~on~um salt of the fatty acld of 1.0 can be used, the best results are obtained when sald ratio is ~reater than 1Ø
In the practice of the present invention, the polymerization reaction is conducted at a high pH. The process can be conducted at a pH in the range of about 7.0 to about 12Ø However, it is pre~erred to operate in a pH range of about 8.o to about 10.5. If the pH is too high it takes too much NH40H and if the pH is too 1OWJ ~or exam-ple, below 7.0, the polymer build-up ~n the reactor increases and the coagulum increases. The amount of NH40H needed to properly ad~ust the p~ will depend in part on the particu-lar emulsifier system being used in the reaction mixture.
T~e process described herein is conducted in the presence of a compound capable of initiating the polymeriza-tion reaction. Free radical yieldlng initiators, normally used ~or polymeri~ing olefinically unsaturated monomers, are satisfactory for use in the present proce s, provlded they do not contain alkali metals, such as sodium and potassium, and the like. The use~ul initiators or catalysts include, ~or example, the varlous p~roxygen compounds, such as persulfates, benzoyl peroxide, t-butyl hydroperoxide, t-butyl peroxyplvalate, cumene hydroperoxide, t-butyl di-perphthalate pelargonyl peroxide, l-hydroxycyclohexyl hydro-peroxide, and the like; azo compounds~ such as azodi~so~butyronitrile, dimethylazodiisobutyrate, and the like. Also use~ul initiators are the water-soluble peroxygen compounds, - 10655~0 such as hydrogen peroxide, lauryl peroxide, isopropyl peroxy-dicarbonate, and the like. The amount of initiator used will generally be in the range between about 0.01% to about 0.5% by weight, based on the weight of 100 parts of monomer or monomers being polymerized, and preferably between about 0.02% to about 0.1% by weight.
In the presçnt process the initiator or catalyst is charged completely at the outset of the polymerization.
The initiator or catalyst is charged at the outset by adding it to the monomer premix with the other ingredients of the reaction mixture. This is particularly true when said pre-mix is homogenized prior to introduction into the reactox.
~owever, when adding the initiator or catalyst to the nomer premix and then homogenizing, it is necessary that the temperature during the premixing and homogenization steps be kept below the minimum temperature of reactivity of the particular initiator or initiators being employed. For example, when making a premix of vinyl chloride. water, ~ ammonium salt of the fatty acid and the alcohol, and then adding t-butyl peroxypivalate thereto, the temperature is maintained at 25C. during the mixing step and then during the ho genization step. Upon introduction of the homo-genized mixture into the polymerization reactor, the tem-perature is then raised to that at which the reaction is to take place.
The temperature of reaction in the instant poly-merizat1on process is important since the intrinsic viscosity (IV~ is a direct function of the temperature of reaction.
That is, the higher the temperature the lower the IV.
Accordingly, the end use for the resin to be produced will normally dictate the reaction temperature. For example.
when producing dispersion resins to be used in coatings or casting flexible films, a higher temperature will be used ~6554~) in order to insure a freely flowable plastisol when the resin is mixed with a plasticizer and other additives norm~y used in the trade, such as dyes, pigments, ~illers, and the like. We have found that for the end uses to which the dispersion resins are partlcularly adapted~ polymerization temperatures in the range of about 30C. to about 70C. are satls~actory. It is preferred, ~owever, to employ a temp-erature in the range Qf about 40C. to about 55C. It should also be pointed out that as the temperature o~ reaction is increased, the polymer build-up increases. Howe~er, the build-up is not o~ the hard crusty type and can readily be rem w ed by ri~slng or hosing down with water and without ope~ing the reactor when appropriate spray nozzles are in-stalled ~n the reactor. On the other hand, even this build-up can be controlled to a certain extent by keeping the walls of the reactor cool during the polymerization react~on. This can be accompllshed by normal means, such as employing a Jacketed reactor with circulati~g cool water in the ~acket.
Using such a technique lt ~s possible to polymerize at higher zo temperatures to obtain desirable low IV dispersion resins and at the same time have reduced polymer build-up. For example, when the polymerization reaction medium is at a temperature o~ about 42C., water at a temperature of about 15C. would be circulated through the ~acket.
Plastisols are made with the dispersion resins o~
the present ~nvention by uni~ormly blending or ~timately mixin~, by conventional means, with 100 parts by weight of the dlspersio~ resin in powder form ~r~m about 30 to about 100 parts by weight o~ one or more plasticizers. The use~
~ul plasticizers may be descr~bed as the alkyl and alkoxy alkyl esters of dicarboxylic aclds or the eskers of a poly-hydric alcohol and monobasic acid, As examples o~ such ~65~i~0 materlals, there may be named dibutyl phthalate, dioctyl phthalate, dibutyl sebacate, dinonyl phthalate, di(2-ethyl hexyl)phth~late, di(2-ethyl hex~l)adipate, dilauryl phthalate, dimethyl te~rachlorophthalate, butyl phthalyl butyl glycollate, gl~ceryl stearate, and the like. The preferred plast~cizers are the liquid diesters of aliphatic alcoho~s having ~rom 4 ta 20 carbon atoms and dibasic carboxylic acids having from 6 to 14 carbon atoms.
The plastisols made ~rom the dispersion resins of the instant invention should have the desired yield and pre-ferably with little or no dilantency. ~ield ls simply de-fined as resistance to ~low and is normally determined numer-ically through ~iscosity measure~ents 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 v~scosity measurements of the plasti-sols at varying r.p.m.'s (revolutions per minute) a~ter initial preparation and at intervals o~ aging. The viscosity i~ 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 illustr~te the present invention, the follvwing speci~ic examples are given, it being understood that this ~s merely intended in an illustrative and not a limitative sense. In the examples all parts and percents are by weight unless otherwise lndicated.
EXAMPLE I
In this example, a series of runs were made to show the effect of using saturated alcohols of varying chain lengths.
In each case the following recipe was used with the exception ~' ~6S~i~O

o~ the alcohol which was varied in each run. All the figures are in parts by weight based on the welght of the total compo-sition.
Vinyl chloride lOOo O
Water (demineralized) 125.0 Lauric acid 2.0 NH40H o.244 ~ert-butyl peroxypival~te 0,05 ; Alcohols Variable In eac~ o~ the runs a monomer premix tank or vessel wa~ purged of air wlth nitrogen. Then the premix tank wa6 char~ed with the water a~d then the vinyl chloride with agita-tion. The temperature in the premix tank was controlled at about 25C. by means o~ a cooling ~acket. The laurlc acid and NH40H were charged followed by the alcohol and lastly, the tert-butyl peroxypivalate. The mixture was agitated ~or 15 minutes under a nitrogen atmosphere, Thereafter the mixture (monomer:premix) was passed through a Manton Gaulin 2 stage homogenizer at a temperature ~f 25~. into the polyme~ization reactor containing a nitrogen atmosphere. The pressure in ~ the first stage o~ the homogenizer was 600 ps~g. and in the : ~ second stage was 700 psig. Thereafter the contents of the ~: reactor were heated to the polymerization temperature, namely, : 45C. and held there throughout the reaction until the desired convers~on was obtained (~enced by a drop in pres~ure to 50 psig.). Therea~ter the reactor was cooled, vented and emptied. The coagulum~ scrapings and reactor conditions were recorded~ The pert~nent data is recorded in Table I
~ below.
3o In order to determlne RVF Viscosity~ plast~sols were made with the resin or polyvinyl chloride (PVC) o~ each run using the ~ollowing recipe:

'~ 6 5 ~ ~
PVC 100 parts Dioctyl phthalate 40 parts Dloctyl adipate 30 part~
Epxodized ~oybean oll5 part~
Ca-Zn pho~phite 3 parts The data wlth respect to viscosity is likeuise recorded in the ~ollowing Table I.

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It can be seen from the above results that the new impro~ed properties ln the products o~ the instant invention are not obtained to satis~actlon until the chain length of the alcohol re~ches 14 carbon atoms. It ls also at this point that a significant reduction in polymer build-up is observed, These runs clearly illustrate the advantages of the present inve~tion.
While the present invention has been de~cribed in terms of its speci~ic 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 invention9 which is to be limited only by the reasonable scope of the appended claims.

Claims

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 vinyli-dene halides and copolymers thereof with each other or either with one or more vinylidene monomers having at least one terminal grouping comprising forming a monomer premix containing the monomer or monomers to be polymerized, the aqueous reaction medium, a catalytic amount of an oil-soluble catalyst for the reaction, said catalyst being free of alkali metals, an ammonium salt of a saturated fatty acid containing from 8 to 20 carbon atoms, and at least one long straight chain saturated alcohol containing from 14 to 24 carbon atoms, and wherein the ratio of alcohol to the ammonium salt of the fatty acid 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 polymerizing said homogenized premix in said zone at a temperature in the range of about 30°C. to about 70°C., maintaining the pH in the reaction zone in the range of about 7.0 to about 12.0 until the reaction is com-plete and thereafter recovering the polymer or copolymer.

2. A process as defined in claim 1, wherein the ammonium salt is ammonium laurate.

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 ammonium salt is formed in situ in the monomer premix by adding to the premix the fatty acid and an excess over the equimolar amount of ammonium hydroxide.

5. A process as defined in claim 4, 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 long chain saturated alcohol is one containing 16 carbon atoms.

8. A process as defined in claim 1, wherein the ammonium salt is ammonium stearate.

9. A process as defined in claim 1, wherein the catalyst is lauroyl peroxide.

10. A process as defined in claim 5, wherein the monomer in the premix is vinyl chloride.

11. A process as defined in claim 10, wherein the catalyst is tert-butyl peroxypivalate.

12. A process as defined in claim 11, wherein the pH in the reaction zone is in the range of about 8.0 to about 10.5.

13. A process as defined in claim 12, wherein the tempera-ture in the homogenizing step is 25°C.

14. A process as defined in claim 13, wherein the tempera-ture in the reaction zone is 45°C.

15. A process as defined in claim 1, wherein the catalyst is present in the premix in an amount from about 0.01% to about 0.5%, by weight based on the weight of 100 parts of the monomer or monomers to be polymerized.

16. A process as defined in claim 15, wherein the monomer in the premix is vinyl chloride, the ammonium salt is selected from the group consisting of ammonium laurate and ammonium stearate and the catalyst is selected from the group consisting of tert-butyl peroxypivalate and lauroyl peroxide.