GB1569440A

GB1569440A - Past bulk polymerisation process for preparing vinyl or vinylidene halide polymers

Info

Publication number: GB1569440A
Application number: GB3258877A
Authority: GB
Original assignee: Hooker Chemicals and Plastics Corp
Current assignee: Occidental Chemical Corp
Priority date: 1976-08-04
Filing date: 1977-08-03
Publication date: 1980-06-18
Also published as: ES461336A1; BR7705090A; IT1085675B; CA1102046A; JPS5411990A; FR2368502B2; FR2368502A2; DE2735022A1

Description

(54) POST BULK POLYMERISATION PROCESS FOR PREPARING VINYL OR VINYLIDENE HALIDE POLYMERS (71) We, HOOKER CHEMICALS & PLASTICS CORP, 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 the preparation of homopolymers and copolymers of a vinyl or vinylidene halide such as vinyl chloride characterized by the properties of small particle size, high bulk density, low plasticizer absorption and easy processability.

The viscosity of plastisols which utilize extender resins is affected not only by the plasticizer absorption characteristics of the polymers, but also by the average particle size, the particle size distribution and the bulk density of the particles. Polymers of the invention are particularly useful as extender polymers for this application.

They are also useful for the manufacture of films and as coatings for fabrics.

In an article entitled "Vapor Phase Polymerizaiton of Vinyl Chloride" in the Journal of Applied Polymer Science, Vol.

1, Pages 445-451, 1971, by Kahle et al., a process is disclosed for the polymerization of vinyl chloride utilizing a liquid bulk polymerized polymer as a seed for a subsequent vapor phase polymerizaiton process. The product is said to have reduced plasticizer absorption. In the process, general purpose grade polyvinyl chloride powder is ground to a suitable size to produce small particle size polymer product. Similar processes are disclosed in U.S. 3,595,840 and U.S. 3,622,553.

French Patent 1,588,381, discloses the addition of fresh vinyl chloride and initiator to a vinyl chloride reaction mixture which has already been bulk polymerized to a substantial extent in a single stage reactor and the submission of this mixture to bulk polymerization in order to obtain polyvinyl chloride granules having excellent plasticizer absorption in the cold and in various sizes according to the duration of their dwelling under polymerization conditions.

U.S. 3,583,956 relates to a process for producing vinyl chloride copolymers having a lower softening point than polyvinyl chloride comprising initially polymerizing vinyl chloride to at least 40% conversion, adding a different vinyl monomer in an amount less than remaining unreacted vinyl chloride and continuing the polymerization at a temperature at least 5 degrees centigrade higher than the first polymerization temperature, preferably 10 to 35 degrees centigrade. The specification discloses that the reaction can be carried out in bulk, solution, emulsion or suspension polymerization processes, but only suspension polymerization processes are described in the Examples.

U.S. 3,725,367 relates to the use of a vinyl chloride latex as a seed polymer in a bulk polymerization process to obtain small particle size vinyl chloride particles having a narrow granular size distribution within the range of 10-50 microns.

U.S. 3,687,923 relates to a process for the polymerizaiton of vinyl chloride in bulk comprising polymerizing a portion of the monomer so as to form seeds, and subsequently adding a larger portion of liquid monomer and continuing the polymerization with mild agitation. The amount of monomer used in the first stage of the polymerization should be at least 1/3 by weight of the total quantity of monomer, which is to undergo reaction. An Example shows a product containing 73% particles between 100 and 200 microns in size.

U.S. 2,961,432 relates to a process for the bulk polymerization of homopolymers and copolymers whereby mixtures of liquid monomers and polymer powders are formed and polymerization carried out.

The monomer used corresponds to the same monomer used to form the polymer powder.

This invention relates to a process for the preparation of a particulate vinyl or vinylidene halide polymer by bulk polymerization comprising the steps of: (1) polymerizing a monomer composition comprising at least 50% by weight of a vinyl or vinylidene halide monomer and optionally up to 50% by weight of an ethylenically unsaturated comonomer copolymerizable therewith, in a first stage using high speed agitation at a temperature of from 30 to 70"C in the presence of 0.05 to 4% by weight, based upon said monomer composition present in a said first stage, of an olefin polymer or halogenated olefin polymer until 3 to 20% by weight of said monomer composition has been converted to polymer particles, (2) continuing the preparation of particulate polymer by polymerization in a second stage during which the reaction mixture is subjected to low speed agitation until 30 to 95% by weight of the monomer composition has been converted to polymer, (3) introducing into said second stage polymerization additional monomer comprising at least one vinyl or vinylidene halide monomer or at least one comonomer which copolymerizes therewith or a mixture thereof, and (4) carrying out the polymerization of said additional monomer in said second stage polymerization to provide nonporous polymer particles by increasing the second stage polymerization temperature after 30 to 80% by weight of said reaction mixture has been converted to polymer, from a temperature of 30 to 70"C to a temperature of 60 to 80"C, said increase in polymerization temperature being 10 to 50"C.

The process of the invention is a twostage liquid bulk polymerization process comprising high speed agitation during a first stage in which 3 to 20%, preferably 7 to 12%, by weight of the composition is converted, followed by polymerization in a second stage with low speed agitation.

By the two-stage polymerization process of the invention, additional monomer is incorporated into the product during the second stage reaction after partial conversion of monomer composition to polymer.

Reactor productivity can be increased about 25% by the method of the invention.

Usually additional initiator is used, together with the additional monomer and preferably a higher temperature reactive additional initiator is added at the beginning of said second stage reaction and the post polymerization conducted in step (4) at a higher reaction temperature suitable to activate the additional initiator.

By the method of the invention high bulk density, low plasticizer absorption products can be obtained by the incorporation of additional monomer. It is not necessary to isolate the resin produced prior to the post polymerization, but only to polymerize the monomer composition to powder form prior to the introduction of the additional monomer. Where dissimilar monomers are used in the post polymerization step, besides reduced plasticizer absorption, reduced melt viscosity and increased impact strength products can be obtained.

The additional monomer or monomers are added either all at once or continuously at a stage in the bulk process where conversion of the initial monomer composition to the powder form has been obtained. This is a conversion of 30 to 95%, preferably 30 to 80%. Where the additional monomer or monomers are added continuously, the rate of addition is adjusted so as to provide for completion of addition before the end of the polymerization cycle. The proportion of monomer or monomers added is generally from 1 to 200% by weight, preferably from 2 to 150% by weight, on the weight of the resultant polymer.

The two-stage bulk polymerization process of the invention may be carried out using techniques disclosed in British Patent 1,047,489, and U.S. Patent 3,522,227.

The vinyl or vinylidene halide monomers which may be used in the process of the invention are vinyl fluoride, vinyl chloride, vinyl bromide, vinyl iodide, vinylidene fluoride, vinylidene chloride.

vinylidene bromide and vinylidene iodide, with vinyl chloride being preferred. The polymers of the present invention can be formed of the same or different monomers and thus can be homopolymers or copolv- mers, including terpolymers and tetrapoly- mers formed by addition polymerization.

Illustrative of these copolymers is a copolymer of vinyl chloride and vinylidene chloride.

While the monomer composition can consist of vinyl or vinylidene halide monomer, it need only contain a predominant amount, i.e. at least 50% by weight of vinyl or vinylidene halide, preferably 80?; by weight of a vinyl or vinylidene halide.

and a minor amount up to 50C.

by weight of another ethylenically unsaturated monomer copolymerizable therewith. Preferably, the other ethylenically unsaturated monomer is used in amounts of less than 20% by weight and more preferably in amounts less than 10% by weight of the monomer composition.

Suitable ethylenically unsaturated comonomers which can be used to form copolymers, including terpolymers and interpolymers, are monoolefinic hydrocarbons, i.e.

monomers containing only carbon and hydrogen, including ethylene, propylene, butene-l, 3-methyl-butene- 1, 4-methylpentene-l, pentene-l, 3,3-dimethylbutene-l, 4,4-dimethylbutene-l, octene-l, decene-l, styrene and its nuclear alpha-alkyl or aryl substituted derivatives, e.g. o-, m- or pmethyl, ethyl, propyl or butyl styrene; alpha-mehyl, ethyl, propyl or butyl styrene; phenyl styrene; halogenated styrenes such as alpha-chlorostyrene; monoolefinically unsaturated esters including vinyl esters, e.g. vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl laurate, vinyl benzoate, vinyl caproate, vinyl hexanoate and vinyl-p-chlorobenzoates, alkyl methacrylates, e.g. methyl, ethyl propyl, butyl, octyl, lauryl and stearyl methacrylates; alkyl crotonates, e.g. octyl crotonate; alkyl acrylates, e.g. methyl, ethyl, propyl, butyl, 2-ethyl hexyl, stearyl, n-hexyl, n-octyl, hydroxyethyl and tertiary butylamino acrylates, 2-ethoxy ethyl acrylate, 2methoxy ethyl acrylate; 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 esters, e.g. allyl formate and allyl acetate and the corresponding methallyl compounds; allyl chloride; allyl cyanide; allyl chlorocarbonate; allyl nitrate esters of alkenyl alcohols, e.g.

beta-ethyl allyl alcohol and beta-propyl allyl alcohol; halo-alkyl acrylates, e.g.

methyl alpha-chloroacrylate, ethyl alpha chloroacrylate, methyl alpha-bromoacryl ate, ethyl alpha-bromoacrylate, methyl alpha-fiuoroacrylate, ethyl alpha-fluoro acrylate, methyl alpha-iodoacrylate and ethyl alpha-iodoacrylate; alkyl alpha cyanoacrylates, e.g. methyl alpha-cyano acrylate and ethyl alpha-cyanoacrylate; itaconates. e.g. monomethyl itaconate, monoethyl itaconate, diethyl itaconate, the mono- and diesters of itaconic acid with C-3 to C-8 alcohols; maleates, e.g. mono methyl maleate, monoethyl maleate, di methyl maleate, diethyl maleate, the mono- and diesters of maleic acid with C-3 to C-8 alcohols; and fumarates, e.g. mono methyl fumarate, mono-ethyl fumarate, dimethyl fumarate, diethyl fumarate, the mono- and diesters of fumaric acid with C-3 to C-8 alcohols; diethyl glutaconate; monoolefinically unsaturated organic nitriles including, for example, fumaronitrile, acrylonitrile, methacrylonitrile, ethacrylonitrile, 1, l-dicyanopropene-l, 3octenenitrile, crotonitrile and oleonitrile; and monoolefinically unsaturated carboxylic acids and anhydrides including, for example, arcylic acid, methacrylic acid, crotonic acid, 3-butenoic acid, cinnamic acid, maleic, fumaric and itaconic acids and maleic anhyride. Amides of these acids, such as acrylamide, are also useful.

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 2-ethylhexyl ether, vinyl 2-chloroethyl ether and vinyl cetyl ether; and vinyl sulfides, e.g. vinyl beta-chloroethyl sulfide and vinyl beta-ethoxyethyl sulfide can also be included as can diolefinically unsaturated hydrocarbons containing two olefinic groups in conjugated relation and the halogen derivatives thereof, e.g. butadiene-1,3; 2-methylbutadiene1,3; 2,3-dimethylbutadiene-1 ,3; 2-chloro butadiene-1 ,3; 2,3-dichlorobutadiene-1 ,3; and 2-bromobutadiene-1,3 can also be used.

Specific monomer compositions which may be used in the first stage can be illustrated by vinyl chloride and/or vinylidene chloride and vinyl acetate, vinyl chloride and/or vinylidene chloride and maleic or fumaric acid esters, vinyl chloride and/or vinylidene chloride and acrylate or methacrylate ester, vinyl chloride and/or vinylidene chloride and vinyl alkyl ether.

These are given as illustrative of the numerous combinations of monomers possible for the formation of copolymers.

While such combinations are intended to be included within the scope of the present invention, it is preferred that monomer composition consists of vinyl or vinylidene halide monomer and most preferably of vinyl chloride.

The monomer or monomers added during the second stage can be the same or different than those used in the first stage, and where different, the monomer or monomers are preferably selected from those monomrs which polymerize at the same or a faster rate as the vinyl or vinylidene halide monomer. Examples of monomers useful in the post polymerization process of the invention are those listed above. Where impact strength is desired in the product of the process, monomers are used such as l-olefins of 2 to 10 carbon atoms, e.g. ethylene, propylene, pentene-l, butene-l, octene-l and decene-l; vinyl esters such as vinyl butyrate, vinyl stearate, vinyl laurate, vinyl caprate and vinyl hexanoate; alkyl methacrylates such as octyl methacrylate; alkyl acrylates such as ethyl acrylate, propyl acrylate, butyl acrylate, 2ethyl hexyl acrylate, stearyl acrylate, nhexyl acrylate and n-octyl acrylate; hydroxyether acrylates such as 2-methoxy ethyl acrylate, 2-ethoxy ethyl acrylate; maleates; fumarates and itaconates such as monomethyl maleate, monoethyl maleate, dimethyl maleate, diethyl maleate, monomethyl itaconate, monoethyl itaconate, dimethyl itaconate, diethyl itaconate, monomethyl fumarates, monoethyl fumarate dimethyl fumarate, diethyl fumarate, alkyl maleates, fumarates and itaconates having an alkyl group chain length of C-3 to C-8; vinyl alkyl ethers, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, vinyl n-butyl ether, vinyl isobutyl ether, vinyl 2-ethylhexyl ether and vinyl cetyl ether; diolefinically unsaturated hydrocarbons containing two olefinic groups in conjugated relation, such as butadiene-1,3; 2-methylbutadiene-1 ,3; 2,3 dimethylbutadience-l ,3; 2-chlorobutadiene The free radical bulk polymerization process of the invention is conducted in the presence of a free radical initiator.

Useful free-radical initiators are organic or inorganic peroxides, persulfates, ozonides, hydroperoxides, peracids and percarbonates, azo compounds, diazonium salts, diazotates, peroxy sulfonates, trialkyl borane-oxygen systems, and amine oxides.

Azobisisobutyronitrile is particularly useful in the present invention. The catalyst is generaly used in concentrations ranging from 0.01 to 1.0% by weight based on the total weight of the monomers. For use in bulk polymerization catalysts which are soluable in the organic phase, such as benzoyl peroxide, diacetyl peroxide, azobisisobutyronitrile, diisopropyl peroxydicarbonate, azobis (alpha-methyl-gama-carboxybutyro-nitrile), caprylyl peroxide, lauroyl peroxide, azobisisobutyramidine hydrochloride, t-butyl peroxypivalate, 2,4dichlorobenzoyl peroxide, azobis (alpha, gamma-dimethylvaleronitrile), and 2,2'azobis(2,4-dimethyl valeronitrile), are generally used. Preferably, the initiater which is used is chosen from a group of initiators 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 mixed with various conventional inert additives, such as fillers, dyes, and pigments. In addition, the polymerization products can be mixed with plasticizers, lubricants, thermo-stabilizers and ultraviolet light stabilizers as desired.

In the two-stage bulk polymerization process of the invention polymerization is first conducted in a first stage reactor with means chosen to agitate the monomer or monomers of a type capable of providing high shear and commonly referred to as a "radial turbine type" agitator. At the start of the first stage reaction, the vessel is charged with a monomer composition to which a catalyst has been added. Any polymerization catalyst generally used in bulk polymerization methods, can be used to an extent which is usual for bulk polymerization processes. After addition of the monomer composition 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 3 to 20% of the monomer composition has been obtained in the first stage reactor, the contents of the vessel are transferred to a second stage polymerization vessel equipped to provide slow speed, low shear agitation so as to ensure proper temperature control of the reaction medium.

The use of an olefin polymer additive in the first stage of the two-stage polymerization according to the invention provides especially good control of product particle size and also inhibits formation of reactor scale. It is advantageous to add to the reaction additional olefin polymer, preferably at the beginning of the second reaction stage, to inhibit scale formation.

Advantageously also, when additional olefin polymer is employed in the second stage of the polymerization, a surfactant may be added with the additional olefin polymer, the amount of surfactant being 0.01 to 0.2% based on the weight of monomer composition added up to that point.

The presence of the surface active agent in the second stage of the polymerization process of the invention results in more complete filling in of interstices in the polymer product particles, i.e. diminishes the porosity of polymer product particles.

Said diminution of the product particle porosity beneficially reduces the viscosity of plastisol formulations incorporating the polymer product as an extender resin.

Accordingly, the addition of the surface active agent to the second stage of the polymerization is beneficial even when no additional olefin polymer is added to the second stage of the polymerization.

The surfactants, or surface active agents, can be of the nonionic, cationic, or anionic type. The surface active agents are organic agents having structurally unsymmetrical molecules containing both hydrophilic and hydrophobic moieties. The non-ionics do not ionize but may acquire hydrophilic character from an oxygenated side chain, usualy polyoxyethylene. The oil-soluble part of the molecule can be aliphatic or aromatic in nature. The cationics ionize so that the oil-soluble portion is positively charged. Principal examples are quaternary ammonium halides such as benzethonium chloride and cetalkonium chloride. The anionics form negatively charged ions con taining in the oil-soluble portion of the molecule. The ionizable group is the hydrophilic portion. Examples are sodium salts of organic acids, such as stearic acid, and sulfonates or sulfates such as alkylaryl sul fonates, e.g. sulfonates of dodecylbenzene and sulfates of straight chain primary alcohols either fatty alcohols or products of the Oxo process, e.g. sodium lauryl sulfate. Examples of non-ionic surfactants that have proven effective are octylphenoxy polyethoxyethanols sold under the tradename " Triton X-100 " and " Triton X-35 " by the Rohm & Haas, Company, Phila delphia, Pennsylvania. Examples of anionic surfactants are as follows: calcium, zinc, magnesium, and nickel stearates. An example of an effective cationic surfactant is a quaternized amine sold under the tradename 4' Quaternary O" by the Ciba-Geigy Corporation.

Additional examples of suitable surfactants and more detailed description of their composition are presented in McCutcheon's Detergents and Emulsifiers, N. American Ed., 1975 Annual, p. 35-265.

The olefin polymer additives used in the process of the invention can be homopolymers or copolymers including terpolymers, of alpihatic hydrocarbon olefins of 2 to 8 carbon atoms. Polymers of the olefins which also contain monomer residues of aliphatic hydrocarbon polyenes, e.g. dienes or trienes, of 4 to 18 carbon atoms can also be used. While advantageously the olefin polymers used in the invention contain only hydrogen as substituents, halogenated olefin polymers such as chlorinated, brominated and fluorinated olefin polymers can also be employed. The weight average molecular weight of the olefin polymers, employed as additives can vary from 50,000 to 300,000 and higher, up to 1,000,000 and higher. Preferably the olefin polymer additive employed in the first stage of the process has a weight average molecular weight of 50,000 to 1,000,000 while the olefin polymer additive preferably added in the second stage has a weight average molecular weight of 50,000 to 300,000.

Preferably also, the first stage olefin polymer additive is a polyene-modified olefin polymer of the type described above, particularly an ethylene-propylene-ethylidene norbornene terpolymer, whereas the seecond stage olefin polymer additive is advantageously free of polyene monomer residues, particularly an ethylene-propylene copolymer.

The amount of olefin polymer added in the first stage of polymerization according to the invention is 0.05 to 4 weight percent, preferably 0.1 to 2 weight percent, based on the weight of monomer composition employed in the first reaction stage. The amount of olefin polymer charged to the reaction at the beginning of the second stage can be as low as 0.05 to 0.5% by weight, more usually is 0.05 to 3 weight percent, preferably 0.1 to 2 weight percent, based on the weight of monomer com position charged up to the point of the addition of the additional polymer.

The use of an olefin polymer in the first stage of a two-stage bulk polymerization process is described in U.K. Specification No. 1436162, while the addition of additional monomer to the second stage of a two-stage bulk polymerization process is described in U.K. Specification No.

1436165.

The present invention provides a bulk polymerization process for the production of high molecular weight vinyl or vinylidene halide polymers having small particle size, the individual particles or agglomerates being characterized as being non-porous. The pores of porous particles initially produced are believed to be filled in with a low molecular weight vinyl or vinyl halide polymer which renders such particles non-porous and more resistant to solvation at ambient temperature as compared to polymers of the prior art.

The reaction temperature in the first stage reactor is 30 to 70"C. The reaction pressure in the first stage reactor is generally from 130 pounds per square inch to 210 pounds per square inch, preferably 150 to 190 pounds per square inch and is dedetermined by the temperature used in the process. The reaction pressure in the second stage reactor is generally from 80 to 180 pounds per square inch, preferably from 90 to 105 pounds per square inch, and also is determined by the temperature used in the process.

During the post polymerization, the ternperature of the reactor contents is raised from a temperature of 30C to 700C to a temperature of 60 to 80"C, said increase in polymerization temperature being 10 to 50"C, and the pressure raised from a pressure of 115 to 215 pounds per square inch to a pressure of 160 to 265 pounds per square inch in order to initiate the reaction where a higher temperature initiator is added at the beginning of the second stage in the two-stage bulk polymerization reaction process. Further details can be obtained of a process of bulk polymerization in two stages in which the temperature of the reactor contents is raised during the second stage of the process by reference to U.S. Patent 3,933,771.

Post-polymerization conducted at a higher reaction temperature than is used initially in the second stage of the polymerization process results in the particles produced being non-porous, being less susceptible to solvation when in contact at room temperature with a primary plasticizer. The polymers also fuse at a lower temperature.

In the process of the invention, additional monomer is added during the second stage of the bulk polymerization process.

In addition to the aforesaid advantages of the post polymerization the addition of monomer during the second stage has the advantage of increasing the yield of polymer since by the addition of monomer during the second stage, a greater yield of product is obtained from the reaction vessel used. Reactor productivity can thus be increased by about 25%.

The following Examples illustrate this invention. In this specification and claims, all parts and percentages are by weight, all pressures are gauge pressures, and all temperatures are in degree Centigrade unless otherwise specified.

Example I A vertical stainless steel first stage reactor of 2-1/2 gallon capacity and stainless steel construction, equipped with a radial turbine type agitator of 3-1/4 inch outside diameter was charged with an air-free mixture of about 4540 g. of vinyl chloride, 0.38 ml of 50-53% solution of diisobutyryl peroxide initiator in odorless mineral spirits (Lupersol 227, Lucidol Division of the Pennwalt Company), 2.20 ml of a 40% solution of di (2-ethylhexyl) peroxydicarbonate initiator in mineral spirts (Lupersol 223M, Lucidol Div. of Pennwalt Co.), 0.776 g. of odorless mineral spirits, 1,081 g. of epoxidized soybean oil and 30 grams (corresponding to 1.15% of the vinyl chloride monomer reactant) of an ethylenepropylene-ethylidene norbornene terpolymer of weight average molecular weight of about 180,000 which had previously been dispersed in liquid vinyl chloride.

Over a period of 55 minutes, with high speed agitation employing an agitator speed of 2000 rpm, the mixture was heated from 20 to 70" under autogenous superatmospheric pressure and then was mainained at 70" for 15 minutes.

The reaction mixture was then transferred to a 5-gallon stainless steel second stage reactor vessel equipped with a spiral agitator of 11-1/8 inch outside diameter, which contained an air-free mixture of about 2270 g. of vinyl chloride monomer, 3.80 ml of the diisobutyryl peroxide initiator, 5.5 g. of lauroyl peroxide initiator, 0.776 g. of odorless mineral spirts, 5.48 g. of octylphenoxy polyethyoxy ethanol (a liquid surface active agent manufactured under the trademark Triton X-100 by Rohm and Haas Co.) and 91.0 g. (corresponding to 1.34% of the vinyl chloride monomer added to the polymerization reaction up to this point) of ethylenepropylene copolymer of a weight average molecular weight of about 160,000. The resulting mixture was agitated at a low speed of agitation of 63 rpm for three hours at 490 and then an additional 4540 g.

of vinyl chloride were added to the mixture over a 30 minute period. On completion of the addition the reaction mixture was agitated at 49" for 15 minutes. Over a 15 minute period the agitated reaction mixture was heated from 49" to 600 and then maintained at the latter temperature for 15 minutes to ensure that all of the diisobutyryl peroxide initiator was consumed.

Over about a 20 minute period, the agitated reaction mixture was heated from 60 to 720 and agitation of the reaction mixture was continued at the latter temperature until a drop in the reaction pressure indicated that polymerization was substantially complete (or no longer than about 8 hou

The product contained 12.6% of scale (i.e.

particles greater than about 0.5 inch size) 11.1% of particles greater than 20 mesh size but less than 0.5 inch size, 2.0% of particles greater than 40 mesh size but less than 20 mesh size, 16.6% of particles greater than 70 mesh size but less than 40 mesh size and 57.7% of particles less than 70 mesh size.

As determined by Coulter Counter analysis of the latter predominant fraction of the product, 84% of the fraction had an average particle of less than 44.1 microns, 50% of the fraction had an average particle size of less than 37.9 microns and 16% of the fraction had an average particle size of less than 31.6 microns.

The bulk density of the aforementioned fraction of product having an average particle size less than 70 mesh was 0.55 g. per cc. The plastisol viscosity of this fraction was 2960 centipoises as measured on a Brookfield viscometer at 25+3 , this value being about 8 % lower than the corresponding viscosity of a proprietory canventional vinyl chloride homopolymer extender resin (Borden 260SS, Borden Chemical Co.) prepared by the suspension mode of polymerization.

It will be appreciated by those skilled in the art that procedural modifications of the above-described experimental technique can be made without departing from the spirit and scope of the invention. For example, the staged raising (i.e. ramping) of the reaction temperature from 49" to 720 (which follows post-polymerization addition of additional monomer in the second reaction stage) can be accomplished more rapidly than by direct heating of the reaction mixture as described, i.e. by preheating the monomer, before its addition, to above 72" and then adding the hot monomer to the reaction mixture at 490 (by incremental addition, if desired), thereby raising the temperature of the resultant mixture from 49" to the desired final reaction mixture temperature of 72".

Example 2 A vertical stainless steel reactor equipped with a radial turbine type agitator and a marine propeller type agitator was charged with an air-free mixture of about 3506 Kg. of vinyl chloride, 340.00 grams of 2,2' azobis (2,4-dimethyl-4-methoxyvaleronitrile) containing approximately 35% H2O, 857.14 ml of a 75% solution of di(2-ethylhexyl) peroxy dicarbonate in mineral spirts, 750 ml of mineral spirits, 750 ml of epoxidized soybean oil and 24.33 Kg. (corresponding to 0.694% of the vinyl chloride monomer reactant) of an ethylenepropylene-ethylidene norbornene terpolymer of weight average molecular weight of about 180,000 which had previously been dispersed in liquid vinyl chloride. Over a period of 55 minutes, with high speed agitation, the mixture was heated from 20 to 70" under autogenous superatmospheric pressure and then maintained at 700 C. for 15 minutes.

The reaction mixture was transferred to a horizontal, reactor equipped with three paddle-type agitator vanes, which contained an air-free mixture of about 1.724 Kg. of vinyl chloride monomer, 10.2 Kg.

of the 2,2' azobis (2,4-dimethyl-4-methoxyvaleronitrile) initiator, 750 ml of regular mineral spirts and 3.9 liters of octylphenoxy polyethoxy ethanol (a liquid surfact active agent manufactured under the trademark Triton X-100 by Rohm and Haas Co.). The resulting mixture was agitated at low speed of agitation for approximately 4.5 hours at 470 and then an additional 2268 Kg. of vinyl chloride monomer containing 2.5 Kg. of lauroyl peroxide initiator were added to the mixture over a 30 minute period. On completion of the addition the reaction mixture was agitated at 470 for 15 minutes. Over a 15 minute period the agitated reaction mixture was heated from 47" to 60 and then maintained at the latter temperature for 15 minutes to ensure that all of the low temperature initiator had been consumed.

Over about a 15 minute period the reaction mixture was then heated from 60 to 72" and agitation of the reaction mixture was continued at the latter temperature until a drop in pressure indicated that polymerization was substantially completed (or no longer than about ten hours for the total duration in the first and second stage reaction zones).

Twelve liters of epoxidized soybean oil were added to the reaction mixture upon completion of reaction as a color and heat stabilizer. After the addition of the epoxidized soybean oil, the reaction mass was agitated for 15 minutes at 72 .

Unreacted vinyl chloride monomer was vented from the reactor and about 4899 Kg. (corresponding to a conversion of about 66.7% based on the total vinyl chloride monomer charged to the reaction) was recovered. As determined by gel permeation chromatography the weight average molecular weight and the number average molecular weight of the product were, respectively, about 102,000 and about 35,300 with the ratio of weight average molecular weight to number average molecular weight being about 2.88. The product contained 85.3% of particles less than 70 mesh size.

As determined by Coulter Counter analysis of the latter predominant fraction of the product, 84% of the fraction had an average particle of less than 84.0 microns, 50% of the fraction had an average particle size of less than 56.7 microns and 16% of the fraction had an average particle size of less than 38.7 microns.

The bulk density of the aforementioned fraction of product having an average particle size less than 70 mesh was 0.65 g.

per c.c. The plastisol viscosity of this fraction was 3438 centipoises as measured on a Brookfield Viscometer at 25+3 , this value being about 3% lower than the corresponding viscosity of a proprietary conventional vinyl chloride homopolymer ex tender resin (Borden 260SS, Borden Chemi cal Co.) prepared by the suspension mode of polymerization.

It will be appreciated by those skilled in the art that procedural modifications of the above-described process can be made without departing from the spirit and scope of the invention. For example, the staged raising (i.e. ramping) of the reaction tem perature from 47" to 720 (which follows post-polymerization addition of additional monomer in the second reaction stage) can be accomplished more rapidly than by direct heating of the reaction mixture as described, i.e. by preheating the monomer, before its addition, to above 72" and then adding to hot monomer to the reaction mixture at 47" (by incremental addition, if desired), thereby raising the temperature of the resultant mixture from 47" to the desired final reaction mixture temperature of 72".

WHAT WE CLAIM IS: - 1. A process for the preparation of a particulate vinyl or vinylidene halide poly mer by bulk polymerization comprising the steps of: (1) polymerizing a monomer composition comprising at least 50% by weight of a vinyl or vinylidene halide monomer and optionally up to 50% by weight of an ethylenically unsaturated comonomer copolymerizable therewith, in a first stage using high speed agitation at a temperature of from 30 to 70"C in the presence of 0.05 to 4% by weight, based upon said monomer composition present in said first stage, of an olefin polymer or halogenated olefin polymer until 3 to 20% by weight of said monomer composition has been converted to polymer particles, (2) continuing the preparation of particulate polymer by polymerization in a second stage during which the reaction mixture is subjected to low speed agitation, until 30 to 95% by weight of the monomer composition has been converted to polymer, (3) introducing into said second stage polymerization additional monomer comprising at least one vinyl or vinylidene halide monomer or at least one comonomer which copolymerizes therewith or a mixture thereof, and (4) carrying out the polymerization of said additional monomer in said second stage polymerization to provide non-porous polymer particles by increasing the second stage polymerization temperature after 30 to 80% by weight of said reaction mixture has been converted to polymer, from a temperature of 30 to 70"C to a temperature of 60 to 800 C, said increase in polymerization temperature being 10 to 50"C.

2. A process according to claim 1, wherein the olefin polymer present in the first stage is a polymer derived from an olefin and a polyene.

3. A process according to claim 1 or 2, wherein the olefin polymer present in the first stage has a weight average molecular weight of 50,000 to 1,000,000.

4. A process according to claim 1, 2 or 3, wherein the olefin polymer present in the first stage is an ethylene-propylene ethylidene norbornene terpolymer.

5. A process according to any one of the preceding claims, wherein polymerization in the second stage is carried out in the presence of additional olefin polymer added in an amount of 0.05 to 3% by weight, based upon the weight of monomer composition added up to the point of addition of said additional olefin polymer.

6. A process according to claim 5, wherein the additional olefin polymer has a weight average molecular weight of 50,000 to 300,000.

7. A process according to claim 5 or 6, wherein the additional olefin polymer is an ethylene-propylene copolymer.

8. A process according to any one of claims 5 to 7, wherein a surface active agent is added to the second stage polymerization with the additional olefin polymer in an amount of 0.01% to 0.2% based on the weight of monomer composition added up to the point of addition of said additional olefin polymer.

9. A process according to claim 8, wherein the surface active agent added in the second stage is octylphenoxy polyethoxy ethanol.

10. A process according to any one of the preceding claims, wherein 1 to 200% by weight of said additional monomer based upon the weight of the resultant polymer is added all at once.

11. A process according to any one of the preceding claims, wherein the monomer composition polymerized in the first stage consists of vinyl chloride and the additional monomer introduced in the second stage consists of vinyl chloride.

12. A process according to any one of the preceding claims, wherein the polymerization in step (2) is continued until

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. 50% of the fraction had an average particle size of less than 56.7 microns and 16% of the fraction had an average particle size of less than 38.7 microns. The bulk density of the aforementioned fraction of product having an average particle size less than 70 mesh was 0.65 g. per c.c. The plastisol viscosity of this fraction was 3438 centipoises as measured on a Brookfield Viscometer at 25+3 , this value being about 3% lower than the corresponding viscosity of a proprietary conventional vinyl chloride homopolymer ex tender resin (Borden 260SS, Borden Chemi cal Co.) prepared by the suspension mode of polymerization. It will be appreciated by those skilled in the art that procedural modifications of the above-described process can be made without departing from the spirit and scope of the invention. For example, the staged raising (i.e. ramping) of the reaction tem perature from 47" to 720 (which follows post-polymerization addition of additional monomer in the second reaction stage) can be accomplished more rapidly than by direct heating of the reaction mixture as described, i.e. by preheating the monomer, before its addition, to above 72" and then adding to hot monomer to the reaction mixture at 47" (by incremental addition, if desired), thereby raising the temperature of the resultant mixture from 47" to the desired final reaction mixture temperature of 72". WHAT WE CLAIM IS: -

1. A process for the preparation of a particulate vinyl or vinylidene halide poly mer by bulk polymerization comprising the steps of: (1) polymerizing a monomer composition comprising at least 50% by weight of a vinyl or vinylidene halide monomer and optionally up to 50% by weight of an ethylenically unsaturated comonomer copolymerizable therewith, in a first stage using high speed agitation at a temperature of from 30 to 70"C in the presence of 0.05 to 4% by weight, based upon said monomer composition present in said first stage, of an olefin polymer or halogenated olefin polymer until 3 to 20% by weight of said monomer composition has been converted to polymer particles, (2) continuing the preparation of particulate polymer by polymerization in a second stage during which the reaction mixture is subjected to low speed agitation, until 30 to 95% by weight of the monomer composition has been converted to polymer, (3) introducing into said second stage polymerization additional monomer comprising at least one vinyl or vinylidene halide monomer or at least one comonomer which copolymerizes therewith or a mixture thereof, and (4) carrying out the polymerization of said additional monomer in said second stage polymerization to provide non-porous polymer particles by increasing the second stage polymerization temperature after 30 to 80% by weight of said reaction mixture has been converted to polymer, from a temperature of 30 to 70"C to a temperature of 60 to 800 C, said increase in polymerization temperature being 10 to 50"C.

30 to 80% by weight of the monomer composition has been converted to polymer.

13. A process according to any one of the preceding claims, wherein the additional monomer is introduced into said second stage polymerization when about 50 to 95% by weight of the monomer composition has been converted to polymer.

14. A process according to claim 1 substantially as described in Example 1 or 2.

15. A particulate vinyl or vinylidene halide polymer when prepared by a process as claimed in any one of the preceding claims.

16. A plastisol of a polymer as claimed in claim 15.