GB1583362A - Method of polymerising vinyl halide with olefin polymers and copolymers and compositions thereof - Google Patents

Description

(54) METHOD OF POLYMERISING VINYL HALIDE WITH OLEFIN POLYMERS AND COPOLYMERS AND COMPOSITIONS THEREOF (71) We, HOOKER CHEMICALS & PLASTICS CORPORATION, a Corporation organised and existing under the laws of the State of New York, United States of America, of Niagara Falls, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a process for the preparation of vinyl or vinylidene halide polymer products having reduced grain size and melt viscosity, improved impact strength and easy processability. The polymer products are useful in the production of films, coatings, and molded articles. Scale build-up is eliminated during bulk polymerization process of the invention.

In our U.K. Patent Specification No. 1,436, 162 we describe and claim a process for the preparation of a vinyl halide polymer product, which process comprises bulk polymerising a monomer composition comprising at least 50% by weight of a vinyl halide monomer in the presence of a preformed polymer which consists essentially of a hydrocarbon polymer derived from one or more acyclic mono-olefins and optionally a cyclic or acyclic diene, has a weight average molecular weight of at least 50000, and is present in an amount of 0.005 to 20% by weight of the total weight of monomer.

The present invention provides a process for the preparation of a vinyl or vinylidene halide polymer product, which process comprises bulk polymerizing in the liquid phase a monomer composition comprising at least 50%, preferably at least 80%, by weight of a vinyl or vinylidene halide monomer in the presence of a trunk polymer and a free radical initiator compound, wherein the trunk polymer is added to the polymerization reaction mixture after the beginning of the polymerization reaction up to the stage at which 20% by weight of the monomer composition has been converted to polymer, the trunk polymer being used in an amount of 0.05% to 20%, preferably 0.1 to 10%, by weight, based upon said monomer composition, and being a polymer of an aliphatic hydrocarbon olefin monomer of 2 to 8 carbon atoms, which polymer is at least partially soluble or dispersible in said monomer composition and has a weight average molecular weight of 50,000 to 1,000,000.

Preferably the bulk polymerisation is carried out in two stages, a first stage wherein the reaction mixture is subjected to high speed agitation until 3% to 20% by weight of the monomer composition has been converted to polymer, and a second stage during which the resultant reaction mixture together with additional monomer composition is subjected to low speed agitation until the polymerization has been completed, the trunk polymer being added to the beginning of the second stage.

The trunk or olefin polymer is added to the polymerization reaction mixture according to the invention after the beginning of polymerization reaction, i.e. after conversion of monomer to polymer has commenced, up to the stage at which 20% of the monomer has been converted to polymer, preferably after 1% to 15%, more preferably 3% to 15%, conversion of monomer to polymer. When the polymerizatior is operated as a two stage process in accordance with the techniques of British Patent Specification No. 1,047,489 and U.S. Patent Specification No. 3,522,227, the olefin polymer is added to the pdlymerizationafter the completion of the first stage reaction, i.e. preferably after 3% to 150to by weight and more preferably 7% to 15% of the monomer has been converted to polymer. Conveniently, in carrying out the polymerization in two stages, the olefin polymer is added to the second stage so as to be present in the second stage reaction vessel prior to occurrence of any substantial polymerizatior therein.

The addition of the olefin polymer subsequent to initiation of the polymerization as described above provides, in general, a faster polymerization reaction, a lower concentration of residual vinyl halide monomer in the polymerization product, and especially, an excellent distribution of product particle size, i.e. the product is characterized by an especially narrow distribution of product particle sizes and contains a large, generally predominant, fraction of the most minute particles. Such improved product particle size distribution is of especial advantage in many uses of the product such as in injection molding and extrusion of articles such as pipe and siding. The aliphatic hydrocarbon olefin polymer which is used as the trunk polymer can be an olefin homopolymer, an olefin binary copolymer, or an olefin terpolymer, for example a terpolymer derived from olefin monomers and a polyene monomer preferably a diene monomer, the resulting terpolymer having available unsaturation. The olefin polymers used are characterized by being soluble, partially soluble or dispersible at polymerization temperature and pressure in the monomer composition. To facilitate solution or dispersion of the olefin polymer in the monomer composition temperatures ranging from 30 to 75 degrees centigrade are preferably used in mixing olefin polymer and monomer. In addition, if desired, a nitrogen atmosphere at a pressure of 1 to 2 atmospheres may be used during the bulk polymerization process according to the invention. The vapor pressure of monomer in the reactor during polymerization is significantly reduced by the dissolved olefin polymer so that the additional nitrogen pressure used increases the total pressure only a small amount as compared to a polymerization conducted without the use of dissolved olefin polymer. In this way, the increased pressure serves to prevent deposition of polymer on the reactor wall.

The polymer products obtained in accordance with the process of the invention can be of medium or high molecular weight and show improved processing characteristics as the result of the ability of the polymer to flux or flow during processing, for instance, during a molding operation, without sacrifice of other physical properties such as strength, and also show improved impact resistance. All these characteristics can be obtained in addition to the characteristic of reduced particle size over the usual 80 to 160 micron particle size polymers commonly produced by the best prior art bulk polymerization processes when the bulk polymerization process is either a two-stage process as has been described in the prior art, such as in U.S. Patent Specification No. 3,522,227, or a single stage bulk polymerization process.

The physical properties of the graft polymerization reaction product such as graft polymerized vinyl chloride are greatly influenced by the degree of interphase compatibilization. By this is meant the phase distribution of the rigid or brittle homopolymer or copolymer continuous phase and the tough rubbery disperse phase of the trunk polymer. During the bulk polymerization of this invention, the compatibilization or phase distribution takes place so that the physical properties of the product obtained are fixed and do not change substantially during further processing. The reaction product exhibits unexpectedly high impact strength for the amount of olefin polymer used in the graft copolymerization. Good thermal properties and high gloss when fabricated into films and molded objects also characterize the reaction product.

According to studies made using the scanning electron microscope,the bulk graft copolymerization process of the invention provides a product having 10 to 30 microns particle size in which the rubber and graft copolymer disperse phase has 0.1 to 0.5 micron diameter. A graft polymer produced by a suspension process is rather poor in physical properties since, as is well known, the reaction takes place in a large suspension droplet resulting in a product with 80 to 150 microns particle size in which the rubber disperse phase has 1 to 10 microns dia- meter. Graft polymers made using the suspension process have poor physical properties such as excessive shrinkage, poor gloss and flexibility at high temperature as a result of the residual strain in the molded product resulting from poor interphase compatibilization or phase distribution.

The trunk polymer upon reaction with the monomer composition forms a graft copolymer. The graft copolymer acts to stabilize a portion of the vinyl or vinylidene halide polymer which constitutes the disperse phase which is present and surrounded by the monomer continuous phase during the initial stage of reaction. The product obtained is a fine powder.

While the exact chemical nature of the polymer product formed by the process of the present invention is not known, it is believed that a graft copolymer is formed in which vinyl or vinylidene halide polymer forms upon the ole fin polymer. To obtain a maximum reduction in melt viscosity which is a standard measure of processability, the polymer used as the trunk polymer in graft polymerization should be incompatible with the vinyl or vinylidene halide polymer formed. During the processing of a polymer of a vinyl or vinylidene halide such as in molding, the physical properties of the polymer change during the processing as the result of the polymer being held at high temperatures for long periods in combination with the internal heat built up as a result of shear forces produced by the processing machinery. Thus, the physical properties of a graft polymer having a trunk polymer which is compatible with the vinyl or vinylidene halide polymer can change during processing as the result of solubilization of the trunk polymer into the vinyl or vinylidene halide polymer. In such a case, the impact strength would decrease during the processing. Therefore, the compositions of the present invention are directed to graft copolymers having an.olefin polymer backbone poly mer which is incompatible with the vinyl or vinylidene halide polymer formed thereon.

With suc11 an incompatible polymer backbone, the physical properties of the graft copolymer do not change during processing, since the incompatibility prevents the solubilization of the trunk polymer in the vinyl or vinylidene halide polymer. The melt viscosity is reduced by the choice of a graft copolymer and is not affected by the usual subsequent processing conditions.

The melt viscosity of the graft copolymer formed also depends upon the molecular weight of the trunk polymer, as well as the vinyl or vinylidene halide polymer formed thereon. A maximum reduction of melt vis- cosity can be expected from the graft copolymer where the trunk polymer is chosen so as to have low molecular weight and the vinyl or vinylidene halide monomer is polymerized so as to have a reasonably low molecular weight also. An ethylene-propylene diene modified polymer of 300,000 weight average molecular weight has been shown to be effective as well as similar polymers having low molecular weight in the range of 50,000 to 150,000 with the lower molecular weight olefin polymers being preferred for easy processing graft copolymers. Where maximum grafting efficiency during polymerization is desired, that is, where it is desirable to reduce the amount of free rubber remaining after polymerization, the molecular weight of the olefin polymer such as ethylene-propylene rubber can be higher than 300,000 and can range up to 1,000,000 and preferably is 300,000 to 500,000 in weight average molecular weight.

The vinyl or vinylidene halide monomers useful in the invention are the alpha-halosubstituted ethylenically unsaturated compounds which are capable of entering into an addition polymerization reaction, for example vinyl monohalides such as vinyl fluoride, vinyl bromide and vinyl iodide, as well as vinyl dihalides such as vinylidene fluoride, vinylidene chloride, vinylidene bromide and vinylidene iodide, although vinyl chloride is preferred. The polymers of the present invention can be formed of the same or different vinyl or vinylidene halides and, thus, the invention includes homopolymers, binary copolymers, terpolymers, and interpolymers formed by addition polymerization. Illustrative of the binary copolymers is a copolymer of vinyl chloride and vinylidene chloride.

The monomer composition preferably consists of vinyl or vinylidene halide monomer, but can contain a minor amount, e.g. up to 50 percent by weight, of at least one ethylenically unsaturated monomer copolymerizable there.

with. Preferably, any other ethylenically unsaturated monomer is used in amount of 20 percent or less by weight and more preferably in amount of 10 percent or less by weight of the total monomer composition. Preferred ethylenically unsaturated comonomers which can be used are monoolefinic hydrocarbons, such as ethylene, propylene, 3-methylbutene-1, 4methylpentene-l, pentene-1, 3,3-dimethylbutene-l, 4,4-dimethylbutene-1, octene-l and decene-l; styrene and its nuclear alpha-alkyl or aryl substituted derivatives, e.g. o-, m- or p-methyl, ethyl, propyl or butyl styrene; alphamethyl, ethyl, propyl or butyl styrene; phenyl styrene; halogenated styrenes such as alpha chloro-styrene; monoolefinically unsaturated esters including vinyl esters, e.g. vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, vinyl-p-chlorob enzoates, alky] methacrylates, e.g. methyl, ethyl, propyl, butyl and octyl methacrylate, alkyl crotonates, e.g.

octyl; alkyl acrylates, e.g. methyl, ethyl, propyl, butyl, 2ethyl hexyl and stearyl, hydroxyethyl and tertiary butylamino acrylates, isopropenyl esters, e.g. isopropenyl acetate, isopropenyl propionate, isopropenyl butyrate and isopropenyl isobutyrate; isopropenyl halides, e.g. isopropenyl chloride; vinyl esters of halogenated acids, e.g. vinyl alpha-chloroacetate, vinyl alpha-chloropropionate and vinyl alpha-bromopropionate; allyl and methallyl compounds, e.g. allyl chloride, allyl cyanide, allyl chlorocarbonate, allyl nitrate, allyl for- mate and allyl acetate and the corresponding methallyl compounds; esters of alkenyl alcohols, e.g. betaethyl allyl alcohol and betapropyl allyl alcohol; halo-alkyl acrylates, e.g.

methyl alpha-chloroacrylate and ethyl alpha chioroacrylate, methyl alpha-bromoacrylate, ethyl alpha-bromoacrylate, methyl alphafluoroacrylate, ethyl alpha-fluoroacrylate, methyl alpha-iodoacrylate and ethyl alphaiodoacrylate; alkyl alpha-cyanoacrylates, e.g.

methyl alpha-cyanoacrylate and ethyl alphacyanoacrylate; maleates, e.g. monomethyl maleate, monoethyl maleate, dimethyl maleate and diethyl maleate; and fumarates, e.g. monomethyl fumarate, monoethyl fumarate, dimethyl fumarate and diethyl fumarate; and diethyl glutaconate; monoolefinically unsaturated organic nitriles including, for example, fumaronitrile, acrylonitrile, methacrylonitrile, ethacrylonitrile, 1 ,l-dicyanopropene-1, 3octenenitrile, crotonitrile and oleonitrile; monoolefinically unsaturated carboxylic acids including, for example, acrylic acid, methacrylic acid, crotonic acid, 3-butenoic acid, cinnamic acid, maleic, fumaric and itaconic acids and maleic anhydride, amides of these acids, such as acrylamide; vinyl alkyl ethers and vinyl ethers, e.g. vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, vinyl n-butyl ether, vinyl isobutyl ether, vinyl 2ethylh.exyl ether, vinyl 2-chloro- ethyl ether, vinyl propyl ether, vinyl n-butyl ether, vinyl isobutyl ether, vinyl 2-ethylhexyl ether, and vinyl cetyl ether; vinyl sulfides, e.g.

vinyl beta-chloroethyl sulfide and vinyl beta- ethoxyethyl sulfide; and diolefinically unsaturated hydrocarbons containing two olefinic groups in conjugated relation and the halogen derivatives thereof, e.g. butadiene-l, 3; 2methyl-butadiene-l, 3; 2,3d-imethylbutadiene- 1, 3; 2ohiordbutadiene-l ,3, 2,3-dichloro- butadiene-1 ,3 and 2bromobutadiene-1 3.

Specific monomer compositions for forming copolymers can be illustrated by vinyl chloride and/or vinylidene chloride iand vinyl acetate, vinyl chloride -and/or vinylidene chloride and maleic cir fumaric acids, esters, vinyl chloride and/or.vinylidene chloride and acrylate or methacrylate ester, vinylchloride and/or vinylidene chloride and vinyl alkyl ether. These are given as illustrative-of the nunrous combina- tions of monomers possible for the formation of copolymers. The present invention includes all such combinations.

The free:radical bulk polymerization- of the monomer composition is coriducted in the- presence of the trunk polymer, for example an olefin homopolymer, binary copolymer or terpolymer. The olefin polymer may also contain an aliphatic hydrocarbon polyene, such as diene or triune, as a monomer unit. Preferably polyenes of-from 4 to 18 carbon atoms are em- ployed.

Preferred olefin monomers are the aliphatic hydrocarbon olefins including ethylene, propene, butene-l, isobutene, pentene, hexene, heptene, octene, 2-methylpropene-l, 3-methyl- butene-l, 4-methylpentene-l, 4-methylhexene 1 and 5-methylhexene-1 . - Preferred comonomers are those utilized to prepare homopolymers as listed above such as propene or butene-l with ethene or isobutylene with isoprene. Preferred termonomers are those utilized to prepare homopolymers and-copolymers as disclosed above such as-propene and ethene containing up to 15 percent, preferably up to 6 percent,by weight of polyene,.for example a diene such as dicycloperitadiene, 1, 3 -butadiene, cyclo-octadiene, ethylidene-nor- bornene, 1 ,4-hexad jene and other conjugated and especially non-eonjugated dienes with linear-or cyclic chains.

Trienes such as isopropylidene cyclopentadiene and the Diels-Alder mono- and di-adducts thereof with.cyclopentadiene may be used in place of the diene. The weight average molecu lar weight of the olefin trunk polymer is from 50000 to 1,000,000, preferably 50,000 to 300, 000, preferably the olefin polymer has anap- parent molecular weight as measured by solu tion viscosity of 50,000 to 200,000. The olefin polymer- can be liquid or. solid as desired. Where a maximum reduction in melt viscosity is de sired in the polymer product, the olefin poly mer used is a low molecular weight rubbery material having a molecular weight of from 80, 000 to 150,000. Where maximum grafting efficiency during polymerization is desired, i.e. where only a slight amount of ungrafted olefin polymer is desired to be left in the graft polymer, a high molecular weight olefin poly mer is utilized having a weight average molecu- lar weight of higher than 300,000 and from 300,000 up to 1,000,000, and preferably from 300,000 to 500,000.

The free radical bulk polymerization suitably takes place in accordance with the process of the invention at temperatures from 25 to 90 degrees centigrade. -The polymerization reaction is conducted in the presence of a free radical initiator compound. Useful free-radical initiator compounds are organic or inorganic peroxides, persulfates ozonides, hydroperoxides, peracids and percarbonates, azo compounds, diazonium salts, diazotates, peroxysulfonates, trialkyl boraneoxygen systems, and amine oxides.

Azobisisobutyronitrile is particularly useful in the present invention. The initiator is generally used in concentration ranging from 0.01 to 1.0 percent by weight based on the total weight of the monomer composition. For use in bulk polymerization, the initiators which are soluble in the organic phase, such as benzoyl peroxide, diacetyl peroxide, azobisisobutyronitrile or dilsopropyl peroxydicarb onate, dicyclohexylperoxydicarbonate, azobis (alpha-methyl.

gamma-carboxybutyronitrile); -caprylyl- peroxide, lauroyl peroxide, azobisisob utyramidine hydrochloride, t-butyl peroxypivalate, 2,4dichlorobenzoyl peroxide, azobis (alphagamma-dimethylvaleronitrile), and 2 ,2'--azobis (2,4-dimethyl valeronitrile) are preferably used.

Preferably the initator compound which is used is chosen from a group of initators known in the prior art as the +'hot catalysts" or those which have a high degree of free-radical initiating activity. Initiators with a lower degree of activity are less desirable in that they require longer polymerization times. Also, long polymerization times may cause preliminary - product degradation-evidenced by color problems, e.g. pinking.

The polymerization products of the present invention can be admixed with various conventional inert additives, such as fillers, dyes, and pigments. In addition, the polymerization products-can be mixed with plasticizers, lubricants, thermostabilizers and ultraviolet light stabilizers as desired.

The other conditions and measures of the process of the invention can be those conventionally employed in the previously-known methods for the bulk polymerization of vinyl chloride involving two-stage polymerization as disclosed in British Patent Specification No.

1,047,489 and U.S. Patent Specification No.

3,522,227. In the following abbreviated description of the process, for the sake of simpli city, the initial stage of the polymerization or copolymerization will be referred to as first stage reaction and the vessel in which this initial stage of polymerization is carried out will be referred to as "Prepolymerizer." The final or complementary stage of the polymerization will be called simply second stage reaction and the vessel in which it is carried out the "Polymerizer." In the first stage reactor, the means chosen to agitate the monomer or monomers is of a type capable of providing high shear and is commonly referred to as a "radial turbine type" agitator. At the start of the first stage reaction, the Prepolymerizer is charged with a monomer composition to which a catalyst has been added. Any polymerization catalyst generally used in bulk polymerization methods, that is, those hereinabove described, can be used to an extent which is usual for bulk polymerization processes. After addition of the vinyl chloride monomer to the first stage reactor, a small amount of monomer is vented in the process of removing the air from the first stage reactor vessel. The speed of the turbine type agitator generally lies between 500 and 2,000 revolutions per minute or a tip speed of 2 to 7 meters per second in the first stage reactor. A tip speed of 0.5 to 2 meters per second is used in the second stage reactor. These figures should not be regarded as limiting values. As soon as a conversion of at least 3 to 20 percent of the monomer composition has been obtained in the first stage reactor, the contents of the vessel are transferred to a second stage polymerizer vessel equipped to provide slow speed, low shear agitation so as to ensure proper temperature control of the reaction medium.

The reaction temperature in both first and second stage reactors generally ranges from 25 to 90, preferably 40 to 80, and especially 50 to 75, degrees centigrade. The reaction pressure in the first stage reactor preferably ranges from 130 to 210, especially 150 to 190, pounds per square inch. The reaction pressure in the second stage reactor preferably ranges from 80 to 120, especially 90 to 190, pounds per square inch.

The optical microscope and sieve analysis were used as a method of determining average particle size. A magnification of 155 times was used together with an eye piece having a scale graduated in microns to determine the average particle size directly in microns. A 325 mesh screen having openings of 44 microns was used.

The molecular weight of the polymer products of the invention is comparable to that of polymers presently commercially produced by bulk polymerization which ranges from 40,000 to 125,000 by the weight average method. To determine molecular weight, relative solution viscosity, RSV, was measured in tetrahydrofuran at 25 centigrade using a 1% by weight resin solution. This is a slight modification from ASTM 1243A wherein a 1% by weight resin solution in cyclohexanone is used. The RSV of polymers produced varied by this method from 1.6 to 2.7. Other test methods are described below.

A falling dart impact has been determined for polyvinyl chloride and related compositions using a falling dart apparatus manufactured by Gardner Laboratory, Inc., Bethesda, Maryland.

The apparatus consists of a 4-pound weight or dart with a rounded end of 1/2" diameter. The dart is allowed to fall through a guiding cylinder and to strike a sample which is held on a flat surface over a 5/8' diameter opening which is 1/4" deep. The guiding cylinder is calibrated in inches, the impact transmitted to the sample being dependent on the height of the fall of the dart. The height of fall in feet times the dart weight (4 pounds) gives an impact in ft.-lb.

units.

The sample for the test must be at least 1/2" wide but preferably 1" or wider. A thickness of 1/8" is desirable. The dart is allowed to fall on a sample from a given height. If the sample survives the impact without showing signs of breaking, cutting, or cracking (it may stretch or distort), it is recorded as passing that impact.

Higher falls of the darts are carried out until a failure is recorded. The impact strength is given as the highest pass. This apparatus measures impact strength up to 14 ft.-lb.

Izod Impact (notched) was measured following the procedure of ASTM D256. Heat distortion temperature was measured by ASTM D648 at 264 psi.

The melt viscosity was measured at 400 degrees Fahrenheit/63 rpm using the "Brabender" Plasticorder ("Brabender" is a Registered Trade Mark). Fifty-five grams of sample containing 2 parts per hundred grams resin of a tin stabilizer sold under the Trade Mark "Thermolite T-3 1" were charged into the "Brabender" chamber which was kept at 400 degrees Fahrenheit/63 rpm. After reaching the fusion point, the sample reaches an equilibrium torque. The equilibrium torque expressed in meter-grams (m-g) corresponds to the melt viscosity.

In order to further illustrate this invention the following Examples are given. In this specification, all parts, ratios and percentages are by weight, all pressures are gauge pressures, and all temperatures are in degrees centigrade unless otherwise specified.

EXAMPLE 1 A two stage reactor system operating at high speed agitation in the first stage and at low speed agitation in the second stage was used.

The first stage reactor was a vertical type reactor of 2.5 gallon capacity and stainless steel construction and equipped with a radial turbine type agitator. To this reactor were charged about 500 g. of vinyl chloride monomer, about 0.1 ml. of, as initiator, a 29 percent solution of acetyl cyclohexane sulfonyl peroxide in dimethyl phthalate sold under the Trade Mark "Lupersol 228P" initiator, and 0.25 ml. of a 40% solution of di-2-ethylhexyl peroxydicarbonate in dimethyl phthalate sold under the Trade Mark "Lupersol 223P".

To remove air from the reactor, about 50 g.

of the monomer were vented from the reactor.

With the agitator operating at a speed of about 1500 rpm, the reaction mixture was heated to about 75 and maintained at the latter temperature at an autogenous pressure of 150 to 178 psig for about 30 minutes. The resultant par tially polymerized mixture was then transferred to a 5 gallon stainless steel reaction vessel as second stage reactor containing 300 g. of additional vinyl chloride monomer,40 g. of an ethylene homopolymer of an especially finely divided state for easy dispersion in organic liquids sold under the designation "Microthene FN500?' by U.S. Industrial Chemicals Co. and 0.5 g. of lauroyl peroxide initiator. After venting 50 g. of the monomer from the reactor in order to remove entrapped air, the mixture was heated at 630 to 75.5 at an autogenous pressure of175 to 187 psig. with the agitator operating at about 300 rpm for about 6 hours. After the reaction mixture was allowed to cool, unreacted monomer was blown off and collected in a condensing circuit incorporating a filter to separate any particles of polymer carried over.

Final traces of residual monomer absorbed by the polymer particles were removed by placing the polymerizer ,under vacuum twice, changing over to a nitrogen atmosphere between each vacuum cycle. All the polymer was then passed through screening equipment. There was thus obtained 608 g. of polymer product corresponding to a conversion of 86.8% based on-the weight of vinyl chloride monomer charged to the polymerization. On screening through a 40 mesh screen (U.S. Standard Sieve Series), about 32% of the product particles passed through the screen while the remaining proportion was retained on the screen.

EXAMPLE 2 To the first stage of a two stage reaction system substantially of the type described in Example 1 there was added about 6.81 kg. of vinyl chloride monomer, 3.6 g. of, as initiator, a 40% solution of di-2ethyl hexyl peroxydicarbonate in mineral spirits, sold under the Trade Mark "Lupersol 223M" and 0.1 g. of a 50% methanol solution of "Gelva" (a densifying agent which is a 2:1 copolymer of vinyl acetate and crotonic acid sold by Monsanto Co.).

About 0.908 kg. of vinyl chloride monomer were vented from the reactor in order to remove entrapped air. The reaction mixture was heated to about 70" under an autogenous reac.- tion pressure of about 167 psig. with the radial turbine agitator operating at about 1500 rpm and agitated at these conditions of temperature and pressure for about twenty-five minutes, after which period the conversion of vinyl chloride to vinyl chloride polymer was about 8% and the reaction mixture was ready for transfer to the second stage reactor.

Meanwhile, in the second stage reaction vessel 273 -g. of an ethylene propylene dienemodified terpolymer (EPDM) of 160,000 weight average molecular weight, ethylene/ propylene ratio 55/45 and ethylidene norbornene present as diene in an amount of 3 + 0.5 percent, and which had been cut into fine shreds (the surfaces of which had been dusted with 200 g.- of a finely divided bulk vinyl chloride homopolymer to prevent agglomeration and promote dissolution of the EPDM in the second stage reaction mixture) was mixed under agitation with about 4.09 kg. of additional vinyl chloride monomer, 4 g. of dicyclohexyl peroxide-dicarbonate sold under the' Trade Mark "Lupersol 229", and 0.3 g. of 2,6 di-t-buyl pcresol antioxidant color stabilizer at 5 under pressure. The temperature of the reaction vessel was raised to SOC and the hot first stage reaction mixture described above was added thereto. After about 0.908 kg. of vinyl chloride had been blown off from the reactor to remove entrapped air, the reaction mixture was maintained at a temperature of about 58" and an autogenous pressure of about 130 psig for about 3 hours and 55 minutes with agitation at 63 rpm. At the end of the foregoing reaction period, the pressure of the reactor dropped indicating the completion of the polymerization.

About 6 g. of epoxidized soy bean oil heat stabilizer was added to the reaction mixture which was agitated for about 15 minutes to insure dispersion of the stabilizer in the reaction mixture. The reaction vessel was heated to 700 and unreacted monomer in the reaction mixture was vented from the reaction vessel over a period of 50 minutes. The polymer product was further freed of unreacted monomer by vacuum degassing of the product at 850 for a period of 8 hours and 25 minutes employing a vacuum of about 30 inches of mercury and was then discharged from the reactor. The pulverulent polymer product was obtained in a yield of 7.45 kg. (corresponding to about 82% conversion based on the monomer reactant employed in the reaction). A predominant fraction, namely about 80% of the polymer product, passed through a 10 mesh screen (U.S.

Standard Sieve Series) indicating that an especially large fraction of the product consists of desirably small-sized product particles. The latter product fraction contained only about 34 parts per million of residual vinyl chloride monomer.

EXAMPLE 3 In substantial accord with the procedure of Example 2, 6.81 kg. of vinyl chloride monomer was mixed with 3.612 g. of the "Lupersol" 223P initiator in the first stage reaction vessel.

After venting of 0.908 g. of monomer from the reactor to remove air entrapped in the reaction mixture, the reaction mixture was maintained at about 700 under an autogenous pressure of about 167 psig with agitation at about 1500 rpm for 25 minutes to effect about 8% conversion of monomer to polymer.

Meanwhile, into the second reaction stage vessel at OC there was charged about 454 g. of Epsyn 7006 (an ethylene propylene copolymer of a weight average molecular weight about 225,000 manufactured by the Copolymer Corporation) which had been shredded and dusted with about 200 g. of a bulk polymerized polyvinyl chloride as described in Example 2, and abouf 0.4 g of the 2,6-di-t-butyl cresol anti oxidant color stabilizer described in Example 2.

The mixture was freed of air by drawing a vac- uum of about 29 inches of mercury and thereafter flooding the vessel with nitrogen gas.

After a repetition of the air removal treatment, 5 g. of the 4'Lupersol 229" initiator described in Example 2, and 3.178 kg. of additional vinyl chloride monomer were added. After the reaction vessel had been sealed, the mixture was heated under agitation to SOC and the first stage reaction mixture described hereinabove was added. The reaction mass was then maintained at a reaction temperature of about 58 under an autogenous reaction pressure of about 130 psig. for about 3 hours and 25 minutes. At the end of the latter reaction period a drop in the reaction pressure indicated completion of the polymerization. The reaction mass was then heated to 70a and the unreacted monomer was vented from the reactor over a period of about 50 minutes. The product was freed of unreacted monomer by vacuum degassing at about X5" for a period of 4 hours and at about 0" for one hour employing a vacuum of about 30 inches of mercury and then discharged from the reaction vessel.

The pulverulent polymer was obtained in a yield of 7.67 kg. (corresponding to a conversion of about 84.5% based on the amount of monomer employed in the reaction). About 76.9% of the product was of such small size as to be capable of passing through the 10 mesh screen described in Example 2. The latter product fraction contained only 198 ppm of residual vinyl chloride monomer.

The procedures of the Examples can be varied somewhat if desired. For example in Examples 2 and 3, the addition of the olefin copolymer to the second stage of the reaction can be carried out by predispersing or pre-dissolving the olefin polymer in all Qr a portion of the vinyl chloride monomer which is to be added to the second stage reaction vessel and thereafter adding the resultant mixture to the second stage reaction vessel instead of adding the olefin polymer directly to the second stage reaction mixture as described in these Examples.

According to another preferred mode of carrying out the invention, as illustrated in Example l, it is advantageous when operating the polymerization in two stages to add to the first reaction stage only a portion, preferably about 60% by weight or more, especially 60% to 70% by weight, of the total monomer or monomers used throughout the polymerization reaction with the balance of the monomer or monomers being added at the beginning of the second reaction stage, i.e. with the olefin polymer. Such charging of only a portion of monomer reactant to the first reaction stage permits use of a first stage reaction vessel of smaller size than that used in the second reaction stage and also, in general, assists in providing a product of excellent particle size distiibution.

WHAT WE CLAIM IS: 1. A process for the preparation of a vinyl or vinylidene halide polymer product which process comprises bulk polymerizing in the liquid phase a monomer composition comprising at least 50% by weight of a vinyl or vinylidene halide monomer in the presence of a trunk polymer and a free radical initiator compound, wherein the trunk polymer is added to the polymerization reaction mixture after the beginning of the polymerization reaction up to the stage at which 20% by weight of the monomer composition has been converted to polymer, the trunk polymer being used in an amount of 0.05% to 20?So by weight, based upon said monomer composition, and being a polymer of an aliphatic hydrocarbon olefin monomer of 2 to 8 carbon atoms, which polymer is at least partially soluble or dispersible in said monomer composition and has a weight average molecular weight of 50,000 to 1,000,000.

2. A process according to claim 1 wherein the trunk polymer is added to the polymerization reaction mixture after at least 1% by weight of the monomer composition has been converted to polymer.

3. A process according to claim 2 wherein the trunk polymer is added to the polymerization reaction mixture after 3% to 15% by weight of the monomer composition has been converted to polymer.

4. A process according to claim 1, 2 or 3, wherein the vinyl or vinylidene halide is vinyl chloride and wherein the trunk polymer is an olefin homopolymer, an olefin binary copolymer or an olefin terpolymer.

5. A process according to claim 4 wherein the trunk polymer is a terpolymer which contains an aliphatic hydrocarbon diene as a monomer unit which is present in the proportion of up to 15% by weight of said terpolymer.

6. A process according to claim 5 wherein said diene is a non-conjugated diene and is present in said terpolymer in the proportion of up to 6% by weight of said terpolymer.

7. A process according to claim 4 wherein the trunk polymer is an ethylene homopolymer, an ethylenepropylene copolymer, an ethylene-propylene-diene modified terpolymer, a propylene homopolymer or an ethylene-butene1 copolymer.

8. A process according to claim 5 wherein the trunk polymer is an ethylene-propyleneethylidene norbornene terpolymer.

9. A process according to claim 5 wherein the trunk polymer is an ethylene-propylene-l, 4-hexadiene terpolymer.

10. A process according to any one of the preceding claims wherein the bulk polymerization is carried out in two stages, a first stage wherein the reaction mixture is subjected to high speed agitation until 3% to 20% by weight of the monomer composition has been converted to polymer, and a second stage during

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (21)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   oxidant color stabilizer described in Example 2.

   The mixture was freed of air by drawing a vac- uum of about 29 inches of mercury and thereafter flooding the vessel with nitrogen gas.

   After a repetition of the air removal treatment,

   5 g. of the 4'Lupersol 229" initiator described in Example 2, and 3.178 kg. of additional vinyl chloride monomer were added. After the reaction vessel had been sealed, the mixture was heated under agitation to SOC and the first stage reaction mixture described hereinabove was added. The reaction mass was then maintained at a reaction temperature of about 58 under an autogenous reaction pressure of about

   130 psig. for about 3 hours and 25 minutes. At the end of the latter reaction period a drop in the reaction pressure indicated completion of the polymerization. The reaction mass was then heated to 70a and the unreacted monomer was vented from the reactor over a period of about 50 minutes. The product was freed of unreacted monomer by vacuum degassing at about X5" for a period of 4 hours and at about 0" for one hour employing a vacuum of about 30 inches of mercury and then discharged from the reaction vessel.

   The pulverulent polymer was obtained in a yield of 7.67 kg. (corresponding to a conversion of about 84.5% based on the amount of monomer employed in the reaction). About 76.9% of the product was of such small size as to be capable of passing through the 10 mesh screen described in Example 2. The latter product fraction contained only 198 ppm of residual vinyl chloride monomer.

   The procedures of the Examples can be varied somewhat if desired. For example in Examples 2 and 3, the addition of the olefin copolymer to the second stage of the reaction can be carried out by predispersing or pre-dissolving the olefin polymer in all Qr a portion of the vinyl chloride monomer which is to be added to the second stage reaction vessel and thereafter adding the resultant mixture to the second stage reaction vessel instead of adding the olefin polymer directly to the second stage reaction mixture as described in these Examples.

   According to another preferred mode of carrying out the invention, as illustrated in Example l, it is advantageous when operating the polymerization in two stages to add to the first reaction stage only a portion, preferably about 60% by weight or more, especially 60% to 70% by weight, of the total monomer or monomers used throughout the polymerization reaction with the balance of the monomer or monomers being added at the beginning of the second reaction stage, i.e. with the olefin polymer. Such charging of only a portion of monomer reactant to the first reaction stage permits use of a first stage reaction vessel of smaller size than that used in the second reaction stage and also, in general, assists in providing a product of excellent particle size distiibution.

   WHAT WE CLAIM IS: 1. A process for the preparation of a vinyl or vinylidene halide polymer product which process comprises bulk polymerizing in the liquid phase a monomer composition comprising at least 50% by weight of a vinyl or vinylidene halide monomer in the presence of a trunk polymer and a free radical initiator compound, wherein the trunk polymer is added to the polymerization reaction mixture after the beginning of the polymerization reaction up to the stage at which 20% by weight of the monomer composition has been converted to polymer, the trunk polymer being used in an amount of 0.05% to 20?So by weight, based upon said monomer composition, and being a polymer of an aliphatic hydrocarbon olefin monomer of 2 to 8 carbon atoms, which polymer is at least partially soluble or dispersible in said monomer composition and has a weight average molecular weight of 50,000 to 1,000,000.
2. 2. A process according to claim 1 wherein the trunk polymer is added to the polymerization reaction mixture after at least 1% by weight of the monomer composition has been converted to polymer.
3. 3. A process according to claim 2 wherein the trunk polymer is added to the polymerization reaction mixture after 3% to 15% by weight of the monomer composition has been converted to polymer.
4. 4. A process according to claim 1, 2 or 3, wherein the vinyl or vinylidene halide is vinyl chloride and wherein the trunk polymer is an olefin homopolymer, an olefin binary copolymer or an olefin terpolymer.
5. 5. A process according to claim 4 wherein the trunk polymer is a terpolymer which contains an aliphatic hydrocarbon diene as a monomer unit which is present in the proportion of up to 15% by weight of said terpolymer.
6. 6. A process according to claim 5 wherein said diene is a non-conjugated diene and is present in said terpolymer in the proportion of up to 6% by weight of said terpolymer.
7. 7. A process according to claim 4 wherein the trunk polymer is an ethylene homopolymer, an ethylenepropylene copolymer, an ethylene-propylene-diene modified terpolymer, a propylene homopolymer or an ethylene-butene1 copolymer.
8. 8. A process according to claim 5 wherein the trunk polymer is an ethylene-propyleneethylidene norbornene terpolymer.
9. 9. A process according to claim 5 wherein the trunk polymer is an ethylene-propylene-l, 4-hexadiene terpolymer.
10. 10. A process according to any one of the preceding claims wherein the bulk polymerization is carried out in two stages, a first stage wherein the reaction mixture is subjected to high speed agitation until 3% to 20% by weight of the monomer composition has been converted to polymer, and a second stage during

    which the resultant reaction mixture together with additional monomer composition is subjected to low speed agitation until the polymerization has been completed, the trunk polymer being added at the beginning of the second stage.
11. 11. A process according to claim 10, wherein a portion, amounting to at least 60% by weight, of the monomer composition charged to the polymerization reaction is added in the first stage, the balance of the monomer composition being added at about the beginning of the second stage.
12. 12. A process according to claim 11 wherein there is added in the first stage 60% to 70% by weight of the monomer composition charged to the polymerization reaction.
13. 13. A process according to claim 10, 11 or 12 wherein 3% to 15% by weight of the monomer composition is converted to polymer in the first reaction stage.
14. 14. A process according to claim 13, wherein 7% to 15% of the monomer composition is converted to polymer in the first reaction stage.
15. 15. A process according to any one of the preceding claims wherein the trunk polymer is introduced to the polymerization reaction mixed with a portion of the monomer composition.
16. 16. A process according to any one of the preceding claims wherein the trunk polymer has a weight average molecular weight of 50,000 to 300,000.
17. 17. A process according to claim 1 substantially as described in any one of the Examples.
18. 18. A polymer product when prepared by a process as claimed in any one of the preceding claims.
19. 19. A polymer product according to claim 18 wherein the proportion of trunk polymer is 0.1% to 10% by weight based on the vinyl or vinylidene halide monomer units of the polymer product.
20. 20. A polymer product according to claim 18 wherein the trunk polymer is present as a rubber and graft polymer disperse phase having a particle diameter of 0.1 to 0.5 microns, the proportion of trunk polymer in said product being 1% to 20% by weight based on the vinyl or vinylidene halide monomer units of the polymer product.
21. 21. A polymer product according to claim 20 wherein the proportion of trunk polymer is 1% to 10% by weight.