"Process for Making an Acrylonitrile and Olefinically Unsaturated Polvmer'', which is a divisional of 08/387, 303 filed on February 27,1995 entitled,"Process for Making an Acryionitrile and Olefinically Unsaturated Polymer", which is a continuation-in-part of 08/150.515 filed on November 10,1993, entitled,"Process for Making an Acryionitrile and Olefinicallv Unsaturated Polymer".

Field of the Invention The present invention relates to thermally stable, thermoplastic, melt processable multipolymers of acrylonitrile monomer, halogenated monomers and optionally olefinically unsaturated monomers. The unique assembly of acrylonitrile monomers, halogenated monomers and optionallv olefinically unsaturated monomers provides for nitrile multipolvmers that can be thermally processed into nitrile fibers or nitrile articles.

It is understood that the term"multipolymer"means polymers, copolymers, terpolvmers and multipolymers prepared from an acrylonitrile monomer and at least one of a vinyl halogen monomer and optionally an olefinically unsaturated monomer (s).

It is understood that the term"modacrylic"as defined by the U. S. Federal Trade Commission. for modacrylic fibers, is from 35% to 85% polymerized acrylonitrile units.

Background of Invention Nitriie polymers are desirable in the production of fibers, films, molded objects, packaging and the like. Nitrile polymers have excellent physical, chemical, and mechanical properties such as gas and moisture barrier, chemical resistance, rigidity, heat resistance, UV resistance and microorganism resistance. However, nitrile poiymers especiallv nitrile polymers containing hatogenated monomers degrade when thermally processed because of the long

repeating sequences of both acrylonitrile monomer units and halogenated monomer units in the polymer chain. The polymers of nitrile monomers and halogen monomers are not melt processable and require the use of solvent because of the long sequences of nitrile monomer units and/or halogen monomer units.

The known processes for the manufacture of fibers and articles produced from polymers of nitrile monomers and halogenated monomers are based on solvent technology. Polymers of nitrile monomers and halogenated monomers cannot be processed in the melt because they decompose at these processing temperatures. The polymers of nitrile monomers and halogenated monomers degrade at increasing rates above 150°C. The polymers become yellow, orange, red and eventually black as they thermally degrade. To avoid these problems, the state of the art conversion of polymers of nitrile monomers and halogenated monomers to nitrile fibers or articles is by solution processes. Only fibers or articles made from solution based processes are available by current technology. The broader range of thermally formed nitrile articles, i. e. bottles, films, parts and the like are not possible from polymers of nitrile monomers and halogenated monomers made by current polymerization processes.

The production of nitrile fibers or articles from solution based extrusion has numerous drawbacks. In the case of modacrylic fibers, the acrylonitrile monomer is copolvmerized with halogenated monomers. The incorporation of halogenated monomers brings about a decrease in the thermal stability of the modacrylic polymer. The use of solution based processes results in the need to remove the solvent from the resulting fibers or articles. The removal of solvent leads to voids in the structure and a decrease in the dimensional uniformity of the product resulting in the loss of mechanical and barrier properties in the product. Furthermore, large quantities of solvent need to be recycled.

It is advantageous to produce a fiber or an article by a solvent free melt process from a thermally stable, thermoplastic, nitrile multipolymer. Further, it is desirable that the multipolymer and resulting product be uniform throughout and substantially void free. The thermal stability of the multipolymer herein allows for thermal processing at higher operating speeds in the absence of solvent; while simultaneously producing fibers or articles with improved physical, mechanical and chemical properties. Furthermore, fibers or articles of complex shape and cross section can be produced from melt processable, thermally stable, thermoplastic multipolymers.

Summarv of the Invention The present invention provides for a melt processable multipolymer comprising about 20% to less than 50% polymerized acrylonitrile, about 80% to about 40% polymerized halogenated monomers and about 0% to 10% of polymerized olefinically unsaturated monomer.

The resulting multipolymer is thermally stable, thermoplastic and thermally processable. The multipolymer contains a relatively uniform distribution of each of the monomers in the multipolymer chain. The present invention provides for a multipolymer that is thermally stable. thermoplastic and has excellent chemical, mechanical and physical properties.

The present invention provides for a process for making the thermally stable, thermoplastic multipolymer by polymerizing an acrylonitrile monomer, at least one of a halogenated monomer and optionally at least one of an olefinically unsaturated monomer in which the rate of addition of the acrylonitrile monomer and the halogenated monomer and the optional olefinically unsaturated monomer is equal to or less than the rate of polvmenzation to maintain a monomer starved process.

The present invention further provides for melt processing the thermally stable, thermoplastic, multipolymer in the absence of solvents into fibers or articles. The present invention further encompasses such processing steps such as melt spinning, resulting in fibers that may be used in woven knitted or non-woven applications, and articles that are thermally processed through thermoforming, compression molding, extrusion, injection molding, blow molding, calendering, thermoforming, fusion coating and the like.

Specific Embodiment The unique thermally processable multipolymer used in this invention comprises an acrylonitrile monomer, a halogenated monomer and optionally an olefinically unsaturated monomer, wherein the multipolymer is homogeneous with a substantially uniform microstructure. Exemplary ways to make the thermally stable, thermoplastic, multipolymers are found in USPN 5,618,901 entitled "A Process For Making A High Nitrile Multipolymer Prepared From Acrylonitrile and Olefinically Unsaturated Monomers" ; USPN 5,602,222 entitled"A Process For Making An Acrylonitrile Methacrylonitrile Olefinically Unsaturated Monomers" ; and USPN 5,596,058

entitled"Process for Making Acrylonitrile/Methacrylonitrile Co-polymers,"all incorporated herein.

The multipolymer comprises about 20% to less than 50%, preferably about 30% to less than 50%, and more preferably about 40% to less than 50% of a polymerized acrylonitrile monomer, at least one of about 80% to about 40%, preferably about 70% to about 40%. and more preferably about 65% to 40% of a polymerized halogenated monomer and one or more of 0% to about 20%, preferably 0% to about 15% and more preferably about 0.1 % to about 10% of a polymerized olefinically unsaturated monomer.

The halogenated monomers employed in the multipolymer are one or more halogenated monomers polymerizable with the acrylonitrile monomer. The halogenated monomers employed in the multipolymer can be a single monomer or combination of monomers. The choice of halogenated monomer or combination of monomers depends on the properties (i. e., flame retardancy) desired for the resulting multipolymer and products.

The halogenated monomers include but are not limited to vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide, vinylidene fluoride, halogen substituted propylene monomers, aromatic halogen monomers such as the chlorostyrenes, and the like. The preferred halogenated monomers are vinyl chloride, vinyl bromide and vinylidene chloride.

The olefinically unsaturated monomer are employed in the multipolymer is one or more of an olefinically unsaturated monomer with a C=C double bond polymerizable with acrylonitrile. The olefinically unsaturated monomer excludes halogenated monomer. The olefinically unsaturated monomer is optionally employed in the multimonomer mixture depending on the properties desired for the multipolymer and resulting products. The olefinically unsaturated monomer can be a single polymerizable monomer or a combination of polvmerizable monomers. The choice of olefinically unsaturated monomer or combination of monomers depends on the properties desired for the resulting multipolymer and product.

The olefinically unsaturated monomer includes but is not limited to acrylates, methacrylates, acrylamide and its derivatives, methacrylamide and its derivatives, maleic acid and derivatives, vinyl esters, vinyl ethers, vinyl amides, vinyl ketones, styrenes, ionic monomers, acid containing monomers, base containing monomers, olefins and the like.

The acrylates include but are not limited to C, to C, 2 alkyl, aryl and cyclic acryiates : such as methyl acrylate, ethyl acrylate and functional derivatives of the acrylates such as 2-hydroxyethyl acrylate, 2-chloroethyl acrylate and the like. The preferred acrylates are methyl acrylate and ethyl acrylate.

The methacrylates include but are not limited to C, to C, 2 alkyl, aryl and cyclic methacrylates; such as methyl methacrylate, ethyl methacrylate, phenyl methacrylate, butyl methacrylate, isobomyl methacrylate, 2-ethylhexyl methacrylate and functional derivatives of the methacrylates such as 2-hydroxyethyl methacrylate, 2-chloroethyl methacrylate and the like. The preferred methacrylate is methyl methacrylate.

The acrylamides and methacrylamides and each of their N-substituted alkyl and aryl derivatives include but are not limited to acrylamide, methacrylamide, N-methyl acrylamide, N, N-dimethyl acrylamide and the like.

The maleic acid monomers include but are not limited to maleic acid monododecvl maleate, didodecyl maleate, maleimide, N-phenyl maleimide.

The vinyl ethers include but are not limited to C, to C : vinyl ethers such as ethyl vinyl ether, butyl vinyl ether and the like.

The vinyl esters include but are not limited to vinyl acetate, propionate, butyrate and the like. The preferred vinyl ester is vinyl acetate.

The vinyl amides include but are not limited to vinyl pyrrolidone and the like.

The vinyl ketones include but are not limited to C, to Cs vinyl ketones such as ethyl vinyl ketone, butyl vinyl ketone and the like.

The styrenes include but are not limited to substituted styrenes, multiple-substituted styrenes, methylstyrenes, styrene, indene and the like. Styrene is of the formula:

wherein each of A, B, D and E is independently selected from hydrogen (H), C, to C, alky) groups and halogen.

The ionic monomers include but are not limited to sodium vinyl sulfonate, sodium styrene sulfonate, sodium methallyl sulfonate, sodium acrylate, sodium methacrylate and the like. The preferred ionic monomers are sodium vinyl sulfonate, sodium styrene sulfonate and sodium methallyl sulfonate.

The acid containing monomers include but are not limited to acrylic acid. methacrvlic acid, vinyl sulfonic acid, itaconic acid, styrene sulfonic acid and the like. The preferred acid containing monomers are itaconic acid, stryrene sulfonate acid and vinyl sulfonic acid.

The base containing monomers include but are not limited to vinyl pyridine, 2- aminoethyl-N-acrylamide, 3-aminopropyl-N-acrylamide, 2-aminoethyl acrylate, 2-aminoethyl methacrylate and the like.

The olefins include but are not limited to isoprene, butadene, C : to C8 straight chained and branched alpha-olefins such as propylene, ethylene, isobutylene, diisobutylene, I-butene and the like. The preferred olefins are isobutylene, ethylene and propylene.

The choice of olefinically unsaturated monomer or combination of monomers depends on the properties desired for the resulting multipolymer and its end use. Polymerizing monomers of acrylonitrile and the halogenated monomer increases the flame resistance of the multipolymer and flame retardancy its end products. For instance, polymerizing monomers of acrylonitrile. halogenated monomer and alpha methyl styrene and/or indene results in a multipolymer and its end products with flame resistance and improved heat distortion temperature and glass transition temperature. Polymerizing monomers of acrylonitrile, halogenated monomer, and isobutylene improves the flexibility of the multipolymer and its end products. Polymerizing monomer of acrylonitrile, halogenated monomer and acrylates and/or methacrylates improves the processability of the multipolymer and its end products. Polymerizing acid-containing monomers, base containing monomers and/or hydroxyl group containing monomers with an acrylonitrile monomer and halogenated monomer provides useful dye sites which enhance the colorability of the resulting multipolymer.

In the practice of the present invention the polymerization process is carried out as an mulsion, a solution, a suspension or in continuous addition bulk. The present invention can be practiced as a semibatch or continuous process. Preferably, the polymerization process is carried out as an mulsion or a suspension. The process of the present invention is not carried out as

batch process, which batch process is defined herein as a process in which all the reactants are charged initially to the reaction vessel prior to the initiation of polymerization.

Initially, acrylonitrile monomers, halogenated monomers, and optionally the olefinically unsaturated monomers are contacted in an aqueous medium at about 0.1 % by weight to about 15% by weight of the total polymerization reaction media. The initial multimonomer mixture contains about 5% by weight to less than 50% by weight acrylonitrile monomer, about 10% by weight to about 90% by weight halogenated monomer and about 0% by weight to about 20% boy weight olefinically unsaturated monomers.

The aqueous medium contains water and a suitable surfactant such as an emulsifier or a dispersing agent. The surfactants and their uses are known to those skilled in the art.

A molecular weight modifier may be added to the initial multimonomer mixture in the range of about 0% by weight to about 5% by weight, preferably about 0.1% by weight to 4% by weight and most preferably about 0.1 % by weight to about 3% by weight of the total multimonomer mixture.

The initial multimonomer mixture is placed into a reaction vessel containing aqueous medium. The reaction vessel with the aqueous medium is purged with an inert gas, such as nitrogen, argon and the like. Preferably, but optionally, the inert gas purge is continued throughout the polymerization reaction. The initial multimonomer mixture is then heated to a temperature in the range of about 20°C to about 120°C and preferably about 10°C to about 80°C. The temperature of the polymerization reaction is maintained throughout the process in the range of about 20°C to about 120°C and preferably about 10°C to about 80°C.

An initiator is added to the initial multimonomer mixture to start the polymerization reaction. The initiator is added generally in the range of about 0.01% by weight to about 5% by weight of the total multimonomer mixture.

After the polymerization reaction commences, a multimonomer feed mixture of acrylonitrile monomer, halogenated monomer and optionally an olefinically unsaturated monomer, is continuously added to the polymerization reaction in the reaction vessel. The combined weight of the unreacted acrylonitrile monomer, unreacted halogenated monomer and unreacted optional olefinically unsaturated monomer present in the polymerizing mixture, at any time. is not greater than about 20% by weight, preferably not greater than about 15% by weight, and most preferably not greater than about 10% by weight of the polymerizing mixture.

The multimonomer feed mixture contains about 5% by weight to about less than 50% by weight acrylonitrile monomer, about 10% by weight to about 90% by weight halogenated monomer and 0% by weight to about 20% by weight olefinically unsaturated monomer. The molar ratio of the acrylonitrile monomer, halogenated monomer and the olefinically unsaturated monomer in the multimonomer feed mixture, is fixed and remains constant throughout the polymerization process resulting in a homogeneous multipolymer. The feed molar ratio of the acrylonitrile monomer to halogenated monomer to olefinically unsaturated monomer depends on the desired multipolymer composition.

A molecular weight modifier is optionally added to the polymerization mixture.

Preferably, the molecular weight modifier is added continuously to the polymerization mixture.

The molecular weight modifier is preferably added to the polymerization reaction media in the range of about 0% by weight to about 5% by weight, preferably about 0.1% by weight to about 4% by weight, and most preferably about 0.1% by weight to about 3% by weight of the total multimonomer mixture.

The molecular weight modifier includes but is not limited to mercaptans, alcohols, halogen compounds or any other chain transfer agent known to those skilled in the art.

Mercaptans are the preferred molecular weight modifier and include mono-mercaptans, multifunctional mercaptans or combinations thereof. The mercaptans include but are not limited to C to C, 8 alkyl mercaptans whether straight chained, branched, substituted or unsubstituted, d-limonene dimercaptan, and the like. The preferred mercaptans are the CS to C,2 alkyl mercaptans whether straight chained, branched, substituted or unsubstituted, for example, t-dodecyl mercaptan and n-octyl mercaptan. The molecular weight modifier can be employed singularly or in combination. The molecular weight modifier can be the same or a different molecular weight modifier as is employed with the initial multimonomer mixture.

The molecular weight modifier that may be useful, controls the molecular weight of the polymerized multipolymer chain by terminating the growing chain. The molecular weight modifier useful in the present invention produces a multipolymer with a molecular weight in the range of about 15,000 molecular weight to about 500,000 molecular weight.

The initiator is added typically as a single solution, continuously or incrementally, to the poivmenzation mixture. The initiator is added at a rate to maintain the polymerization rate. which rate can be determined by those skilled in the art. The concentration of the initiator is

generally in the range of about 0.01 % by weight to about 5% by weight of the total multimonomer mixture.

The initiator is any free radical initiator known to those skilled in the art. The initiator includes but is not limited to azo compounds, peroxides, hydroperoxides, alkyl peroxides, peroxydicarbonates, peroxyesters, dialkyl peroxides, persulfates, perphosphates, and the like.

Persulfates are the preferred initiators. The initiator can be employed singularly or in combination with reducing compounds to enhance their reactivity (redox). The initiator can be the same or a different initiator as is employed to start the polymerization reaction.

The polymerization mixture is agitated by any known method, such as stirring, shaking and the like. The reaction is continued until polymerization has proceeded to the desired extent. generally from about 30% to about 90% conversion.

The polymerization reaction is stopped by cooling; adding an inhibitor; such as diethy) hydroxylamine, 4-methoxyphenol and the like; discontinuing the multimonomer feed mixture ; removing unreacted monomer, and the like. The inhibitors and their use are known to those skilled in the art.

At the conclusion of the polymerization reaction the multipolymer is a solid, slurry or a latex. Any known technique may be used to isolate the multipolymer such as crumb coagulation. spraying the solution of the multipolymer into a heated and/or evacuated chamber to remove the water vapors, stripping, filtration, centrifugation and the like.

The multipolymer produced by the process of the instant invention is a thermally stable. thermoplastic multipolymer containing polymerized acrylonitrile monomer and polymerized halogenated monomer and optionally polymerized olefinically unsaturated monomer. The multipolymer is homogeneous in that the composition and sequencing of the multipolymer produced is substantially the same throughout the process.

The process for producing a thermally stable, thermoplastic, melt processable multipolymer from the monomers is accomplished by controlling the rate of addition of the acrvlonitrile monomer, the halogenated monomer and the olefinically unsaturated monomer relative to the rate of polymerization. The process of the invention is a monomer starved process in which the polymerization reaction rate exceeds or equals the multimonomer feed mixture addition rate. The low concentration of the unreacted multimonomers during the polymerization step generates a monomer starved condition which prevents long sequences of each of the monomers in the multipolymer chain. The multipolymer chain contains short sequences of

polymerized halogenated monomer interdispersed between short sequences of polymenzed acryionitrile monomer for example, AN-AN-Z-AN-AN-Z-Z-AN-Z-Z (AN=acrylonitrile unit and Z=halogen unit). The halogenated monomers are substantially uniformly interdispersed among the acrylonitrile units in the multipolymer. These shorter acrylonitrile sequenced multipolymers have a lower melting point and reduced melt viscosity which allows melt/thermal processing in the absence of solvent. The multipolymer allows for unique properties in the fibers or articles such as dimensional stability, improved orientation, substantially free of voids, uniformity, strength, toughness, flexibility, resistance to degradation by W light, resistance to biological attack and the like.

The thermally stable, thermoplastic multipolymer can be processed by a combination of one or more of any thermal processes and/or thermoforming techniques. The multipolymer is thermoplastic, thermally stable and thermally processable without the addition of any solvents.

The multipolymer of the present invention may be further thermal processed by spinning, molding, extruding and the like without the use of solvents. Such thermal processing steps include, but are not limited to, thermoforming, orientation, blowing, lamination, coating, extrusion, sealing, prestretching compression molding, injection molding, blow molding, calendering, fusion coating and the like. The thermal process temperature is higher than the glass transition temperature of the multipolymer from about 100oC to about 300oC and preferably about 130oC to about 240oC.

An exemplary method to make melt spun acrylonitrile olefinically unsaturated fibers and the process to make the fibers is described in USSNs 08/574,312 and 08/780,754 entitled"Melt Spun Acrylonitrile Olefinically Unsaturated Fibers and the Process to Make the Fibers". An exemplary method to make thermally melt processable articles from multipolymer as described in USSN 09/255,092 entitled"Thermally Melt Processable Multipolymers of Acrylonitrile and Olefinically Unsaturated Monomers".

It will be readily apparent to one skilled in the art that the multipolymer and resulting products may be further modified by the addition of lubricants, dyes, leaching agents, pigments, delustering agents, stabilizers, static control agents, antioxidants, reinforcing agents such as fillers and the like. It is understood that any additive possessing the ability to function in such a manner can be used as long as it does not have a deleterious effect on the thermal characteristics of the multipolymer and products thereof.

The thermal processing occurs in the absence of solvent. Such articles produced here include uniaxial and/or biaxial films, sheets, tapes, laminates, shaped articles, coated structures. composite structures, fibers and the like. The multipolymer may be utilized in numerous applications such as for use in filaments, fibers, fabrics, woven fabrics, non-woven fabrics, flame retardant fabrics, films, carbon sheets, carbon films, sheets, pipes, tubing, molded articles, coated laminates, wire coverings, substrates for xerography, packaging, tapes, bottles, coatings, laminates, barrier products, membranes, molded articles and the like. The products of this invention may be further used in packaging, barrier applications, electrical insulators. photographic films, engineering films and the like.

Examples The following examples are presented to illustrate the present invention. It should be understood, however, that the invention is not limited to the specific details set forth in the examples.

Example 1 Preparation of 50/50, Acrylonitrile/Vinyl Chloride Copolymer: A 1 liter stainless steel polymerization reactor capable of retaining about 150 psi. of pressure was equipped with a stirrer, electrical heater and control system, nitrogen purge and one monomer mixture feed line with pump. The reactor was initially charged with about 560 gm of water and about 22.9 gm of Dowfax 8390 (surfactant from Dow Chemical Co.), purged with nitrogen gas, sealed and brought to about 22°C. An initiator system comprised of about 1.28 gm ammonium persulfate, about 0.3 gm of sodium meta-bisulfite and about 0.08 gm of ferrous sulfate was charged and immediately followed by an initial monomer mixture charge of about 0.94 gm acrylonitrile, about 15.1 gm of vinyl chloride and about 0.32 gm of n-octyl mercaptan under pressure. A monomer feed of 45.2 gm acrylonitrile, 105.4 gm of vinyl chloride and about 3.0 gm of n-octyl mercaptan was then added to the reactor in a uniform manner over a period of three hours. The reaction was allowed to proceed for one half hour after the feed was complete then the reactor was vented of excess vinyl chloride gas and the resulting latex drained from the reactor. The temperature of the reaction ranged from about 22 to about 28°C. The latex was

coagulated in 3 liters of stirred water at about 95°C containing about 4 gm of magnesium sulfate. filtered and dried.

The final conversion to copolymer based on overall monomers was 60% and had a composition of about 48.7 weight percent acrylonitrile by"C NMR and a molecular weight of 22,000 Mw by Gel Permeation Chromatography (GPC) and a Melt Index of 47 (g/10 min.) at 200°C with a 10 kg load.

Example 2 Preparation of 40/60, Acrylonitrile/Vinyl Chloride Copolymer: A 1 liter stainless steel polymerization reactor capable of retaining 150 psi. of pressure was equipped with a stirrer, electrical heater and control system, nitrogen purge and one monomer mixture feed line with pump. The reactor was initially charged with about 560 gm of water and about 22.9 gm of Dowfax 8390 (surfactant from Dow Chemical Co.), purged with nitrogen gas, sealed and brought to about 22°C. An initiator system comprised of about 1.28 gm ammonium persulfate, about 0.3 gm of sodium meta-bisulfite and about 0.08 gm of ferrous sulfate was charged and immediately followed by an initial monomer mixture charge of about 0.94 gm acrylonitrile, about 15.11 gm of vinyl chloride and about 0.32 gm of n-octyl mercaptan under pressure. A monomer feed of 28.6 gm acrylonitrile, about 122.0 gm of vinyl chloride and about 3.0 gm of n-octyl mercaptan then was added to the reactor in a uniform manner over a period of three hours. The reaction was allowed to proceed for one half hour after the feed was complete then the reactor was vented of excess vinyl chloride gas and the resulting latex drained from the reactor. The temperature of the reaction ranged from about 22 to about 28°C. The latex was coagulated in 3 liters of stirred about 95°C water containing about 4 gm of magnesium sulfate, filtered and dried.

The final copolymer had a composition of about 41.2 weight percent acrylonitrile by 13C NMR and a molecular weight of 50,000 Mw by Gel Permeation Chromatography (GPC) and a Melt Index of 85 (g/20 min.) at 200°C with a 10 kg load.

Example 3 Preparation of Acrylonitrile and Vinylidene Chloride Copolymer (47/53, AN/VDC) A 2 liter glass polymerization kettle equipped with a temperature controlled water jacket, flat blade stirrer, inert gas purge line, and 3 feed lines with pumps was charged with 757gms of

distilled water, about 18.86gms of Dowfax 8390 (surfactant from Dow Chemical Co.), about I gms of acrylonitrile, about 1 gms of vinylidene chloride and about 0.18gms of n-octyl mercaptan and brought to about 9oC under nitrogen gas. To this was added about 0.22gms of sodium meta-bisulfite, about 0.44gms of ferrous sulfate and about 0.22gms of ammonium persulfate to initiate the reaction. Upon initiation, three continuous streams were pumped into the reactor uniformly for a period of 5 hours. Stream one consisted of about 89.1 gms of acrylonitrile, about 108.9gms of vinylidene chloride and about 1.58gms of n-octyl mercaptan.

Stream two consisted of about O. 55gms of ammonium sulfate in 100gms of water. Stream three consisted of about 0.04gms of ferrous sulfate in lOOgms water.

After five hours the resulting latex was coagulated in 3 liters of hot water containing about 6gms of AI, (SO,) 3. The polymer was collected by filtration and dried by fluid bed at about 60oC for 5 hours. The conversion was 84.5% with a composition of about 47.3weight percent AN and about 53.7 weight percent VDC with a molecular weight of 202,000 Mw by Gel Permeation Chromatography (GPC).

Example 4 Preparation of Terpolymer of Acrylonitrile, Vinylidene Chloride and Methyl Acrylate A 2 liter glass polymerization kettle equipped with a temperature controlled water jacket, flat blade stirrer, inert gas purge line, and one feed line with pump and charged with about 600gms of distilled water, about 28.57gms of Dowfax 8390 (surfactant from Dow Chemical Co.), about 7.6gms of acrylonitrile (AN), about 1 lgms of vinylidene chloride (VDC), about 1.4gms of methyl acrylate (MA) and about 0.20gms of n-octyl mercaptan and brought to 18oC under nitrogen gas. To this was added about 0.40gms of sodium meta-bisulfite, about 0.1 Ogms of ferrous sulfate and about 1.2gms of ammonium persulfate to initiate the reaction. Upon initiation, a continuous stream consisting of about 68.4gms of acrylonitrile, about 99.0gms of vinylidene chloride about 12.6gms of methyl acrylate and about 1.8gms of n-octyl mercaptan was pumped into the reactor uniformly over a period of about 3 hours. The reaction was continued for one half hour after the addition was complete.

After three and one half hours the resulting latex was coagulated in 3 liters of hot water containing about 6gms of MGS04. The polymer was collected bv filtration and dried by fluid bed at about 600C for about 5 hours. The conversion was 82.45% with a composition of 43. 3 weight percent AN, 48. weight percent VDC and 8.5 weight percent MA From the above description of examples and invention; those skilled in the art will perceive improvements, changes and modifications in the invention. Such improvements. changes and modifications are intended to be covered by the claims.