Title of Invention	"A PROCESS FOR POLYMERIZING (A) ACRYLONITRILE MONOMER, (B) METHACRYLONITRILE MONOMER AND (C) AN OLEFINICALLY UNSATURATED MONOMER"
Abstract	A process for making a thermally stable melt processable acryloni-trile/methacrylonitrile/olefinically unsaturated multipolymer, comprising polymerizing a mixture of acrylonitrile monomer, methacrylonitrile monomer, and olefmically unsaturated monomer in which the rate of addition of the multimonomer mixture is set by the rate of polymerization so that the concentration of unreacted acrylonitrile monomer, unreacted methacrylonitrile monomer and unreacted olefinically unsaturated monomer is low and the polymerization process is in a monomer starved condition.

Title of Invention

"A PROCESS FOR POLYMERIZING (A) ACRYLONITRILE MONOMER, (B) METHACRYLONITRILE MONOMER AND (C) AN OLEFINICALLY UNSATURATED MONOMER"

Abstract

A process for making a thermally stable melt processable acryloni-trile/methacrylonitrile/olefinically unsaturated multipolymer, comprising polymerizing a mixture of acrylonitrile monomer, methacrylonitrile monomer, and olefmically unsaturated monomer in which the rate of addition of the multimonomer mixture is set by the rate of polymerization so that the concentration of unreacted acrylonitrile monomer, unreacted methacrylonitrile monomer and unreacted olefinically unsaturated monomer is low and the polymerization process is in a monomer starved condition.

Full Text	The present invention relates to a process for polymerizing (a) acrylonitrile monomer, (b) methacrylonitrile monomer and (c) an olefmically unsaturated monomer. The present invention relates to a process for producing a homogenous acrylonitrile/methacrylonitrile multipolymer, with improved thermal stability, that is melt processable. More specifically, the invention relates to a monomer starved process for producing an acrylonitrile/methacrylonitrile/olefinically unsatruated multipolymer in which the polymerization rate exceeds or equals the addition rate of the multimonomers of acrylonitrile monomer, methacrylonitrile monomer, and olefinically unsaturated monomer. Acrylic polymers are desirable to produce fibrous textiles, films, molded objects, packaging applications, and the like because the acrylic polymers have a high nitrile polymer content. Nitrile polymers have excellent physical, thermal, and mechanical properties such barrier properties, chemical resistance, rigidity, heat resistance, UV resistance, moisture, retention, and bacteria resistance. Acrylonitrile and methacrylonitrile monomers are nitrile monomers useful to produce acrylic polymers. In the past, high nitrile polymers have been limited to containing about 20% by weight polymerized acrylonitrile since higher acrylonitrile content leads to non-melt processable polymers. U.S. Patent No. 3,565,876 discloses that up to about 20% by weight of an acrylonitrile monomer can be copolymerized with a methacrylo-nitrile monomer to form an extrudable copolymer which can be readily oriented and possesses excellent physical properties. Increasing the acrylonitrile content above about 20% by weight in the acrylonitrile/methacrylonitrile copolymer results in a resin which is thermally unstable and not processable by any standard economical commercial melt processing techniques including extrusion. High acrylic polymers are conventionally processed by solvent techniques such as wet spinning acrylic fibers. The use of solvents is disadvantageous because the solvents must be removed from the acrylic polymer prior to end use resulting in voids in the acrylic fiber. Furthermore, the solvents are typically toxic and their disposal has negative impact on the environment. U.S. Patent No. 5,106,925 discloses a process for producing an acrylonitrile/methacrylonitrile copolymer that is melt processable in the absence of solvent. The patent discloses that acrylonitrile/methacrylonitrile copolymer is produced under flooded monomer process conditions. In the flooded monomer process, the molar weight ratios of the acrylonitrile monomer and methacrylonitrile monomer must be carefully controlled and adjusted throughout the polymerization process in relationship to the conversion of the comonomers to copolymer. The copolymer conversion is tracked throughout the process so that the addition of comonomers may be adjusted to obtain the desired copolymer. Thus, this process is disadvantageous because of the necessity to track, to predict the copolymer conversion rate, and to adjust the rate of addition of the comonomers throughout the process. It is advantageous to produce a homogeneous acrylonitrile/methacrylo-nitrile/olefinically unsaturated multipolymer with improved thermoplastic properties which multipolymers are melt processable in the absence of a solvent. Further, it is desirable to produce an acrylonitrile/methacrylonitrile/olefmically unsaturated multipolymer by a process in which the feed ratio of the monomers is fixed and constant throughout the polymerization process. It is advantageous to confer improved properties on an acrylonitrile/methacrylonitrile copolymer by the addition of an olefinically unsaturated polymerizable monomer into the acryloni-trile/methacrylonitrile copolymer. The addition of an olefinically unsaturated monomer to an acrylonitrile/methacrylonitrile copolymer improves properties such as thermal stability, strength, rheology, processability, colorability, moisture retention, flexibility, and the like. Summary of the Invention The present invention provides a new and an improved process for producing an acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymerwith improved thermal stability, excellent mechanical, and excellent physical properties. The process comprises polymerizing a mixture of acrylonitrile monomer, methacrylo-nitrile monomer, and olefinically unsaturated monomer in which the rate of addition of the acrylonitrile monomer, the methacrylonitrile monomer, and the olefinically unsaturated monomer is set to be equal to or less than the rate of polymerization to maintain a monomer starved process. Further, the weight of unreacted acrylonitrile monomer, unreacted methacrylonitrile monomer, and unreacted olefinically unsaturated monomer is not greater than 15% of the weight of the polymerizing mixture. Further, the molar ratio of acrylonitrile monomer, methacrylonitrile monomer, and olefinically unsaturated monomer is fixed and constant for the multimonomer feed throughout the polymerization process. In particular, the process for polymerizing an acrylonitrile monomer, a methacrylonitrile monomer, and an olefinically unsaturated monomer for producing acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer comprises the steps of; 1. heating an initial multimonomer mixture comprising acryloni trile monomer and methacrylonitrile monomer under an inert atmosphere in the range of about 40°C to about 120°C, 2. adding an initiator to the initial multimonomer mixture to start a polymerization reaction, and unreacted monomer (a), (b), and (c) is never greater than 15 wt % of the polymerizing mixture throughout the polymerization; (iv) optionally, continuously or incrementally adding a molecular weight modifier to the polymerization mixture in the range of about 0 to about 5 wt % of the total weight of the reaction mixture wherein the molecular weight modifier is selected from the group consisting of mercaptans, alcohols, halogen compounds, and combinations thereof; and (v) maintaining the polymerization temperature in the range of about 40°C to about 120°C forming a homogeneous copolmer wherein the copolymer composition is similar to the three monomer molar feed ratio and wherein the copolymer is melt processable without the use of solvents. Detailed Description of the Invention The present invention relates to a process for producing thermally stable melt processable homogeneous acrytonitrile/methacrylonitrile/olefinically unsaturated multipolymes. The new and improved process for producing a thermally stable melt processable multipolymer of acrylonitrile, methacrylonitrile and olefmically unsaturated monomer is accomplished by controlling the rate of addition of the acrylonitrile monomer, methacrylonitrile monomer, and olefmically 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 multimour^er mixture addition rate. The low concentration of the multimonomers during the addition step prevents long sequences of acrylonitrile monomer in the multipolymer. The multipolymer contains small sequences of methacrylonitrile and olefmically unsaturated monomer interdispersed between small sequences of bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide, vinylidene fluoride, sodium vinyl sulfonate, sodium styrene sulfonate, sodium methallyl sulfonate, sodium acrylae, sodium methacrylate, acrylic acid, methacrylic acid, vinyl sulfonic acid, itaconic acid, vinyl pyridine, N-amino ethyl acrylamide, N- amino propyl acrylamide N-amino ethyl acrylate, N-amino ethyl methacrylate, propylene, ethylene, isobutylene, diisobutylene, 1-butene, and combinations thereof, to produce a melt processable acrylonitrile/methacrylonitrile/olefmically unsaturated copolymer, said process comprising the steps of: (i) heating an initial mixture of about 0.1 to 15 wt % monomer (a), about 20 to about 99 wt % monomer (b), and about 0 to about 40 wt % monomer (c) under an inert atmosphere in the range of about 40°C to about 120°C wherein each wt % recited is with respect to the total initial mixture weight; (ii) adding an initiator to the initial monomers mixture of step (i) to start a polymerization reaction wherein said initiator comprises from about 0.01 wt % to about 5 wt % of the total initial mixture weight; and wherein the initiator is selected from the group consisting of azo compounds, peroxides, hydroperoxides, alkyl peroxides peroxydicarbonaes, peroxyesters, dialkyl peroxides, persulfates, perphosphates, and combinations thereof; (iii) adding a three monomer feed mixture comprising about 20 to about 99 wt % monomer (a), about 0.1 to about 80 wt % monomer (b), and about 0.1 to about 40 wt % monomer (c; +o the initial polymerization mixture of step (ii) wherein the three monomer feed mixture has a fixed and constant molar ratio of monomer (a) to monomer (b) to monomer (c) within the specified wt % ranges and is maintained at the fixed ratio at a constant rate of addition which is less than or equal to the polymerization rate so that the combined weight of 3. adding a multimonomer fed mixture comprising an acrylonitrile monomer, a methacrylonitrile monmer and an olefinically unsaturated monomer to the polymeriztion mixture wherein the multimonomer feed mixture has a fixed and constant molar ratio of acrylonitrile monomer to methacrylonitrile monomer to olefinically unsaturated monomer and further wherein the addition rate of the multimonomer feed mixture is less than or equal to the polymerizationrate. The process of the present invention produces homogeneous acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymers in which the units of acrylonitrile, methacrylonitrile, and olefinically unsaturated monomer are interdispersed randomly throughout the polymerized chain in relatively small monomer units resulting in a thermally stable melt processable multipolymer with improved characteristics. The acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer is melt processable in the absence of solvent or plasticizing agent to produce acrylic products. Thus according to the present invention, there is provided a process for polymerizing (a) acrylonitrile monomer, (b) methacrylonitrile monomer and (c) an olefinincally unsaturated monomer selected from the group consisting of methyl acrylate, ethyl acrylate, phenyl acrylate, butyl acrylate, isobornyl acrylate, 2-hydroxy ether acrylate, 2-chloro ethyl acrylate, 2-ethyl hexyl acrylate, methyl methacrylate, ethyl methacrylate, phenyl rr.;"thacrylate, butyl methacrylate, isobornyl methacrylate, 2-hydroxyethyl methacrylate, 2-chloro ethyl methacrylate, 2-ethyl hexyl methacrylate, acrylamide, N-methyl acrylamide, N-dimethyl acrylamide, vinyl acetae, vinyl propionate, vinyl butyrate, ethyl vinyl ether, butyl vinyl ether, vinyl pyrrolidone, ethyl vinyl ketone, butyl vinyl ketone, styrene, methyl styrene, indene, vinyl chloride, vinyl acrylonitrile for example, AN-AN-X-MAN-AN-X-X-AN-MAN-MAN-X(X=olefm-ically unsaturated monomer), allowing for melt processability of the acryloni-trile/methacrylonitrile/olefinically unsaturated multipolymer in the absence of solvent. Additionally, employing the olefinically unsaturated monomer in the acryloni-trile/methacrylonitrile polymer backbone reduces the amount of repeating acrylonitrile sequences resulting in a more random multipolymer. The rate of addition of the acrylonitrile monomer, methacrylonitrile monomer, and olefinically unsaturated monomer is incremental or continuous, preferably continuous, throughout the polymerization reaction. The molar ratio of the multimonomer feed mixture of acrylonitrile monomer, methacrylonitrile monomer, and olefinically unsaturated monomer is constant throughout the process. The process produces a homogeneous composition of the multipolymer similar to the molar ratio of the incoming multimonomer feed mixture. i The olefinically unsaturated monomer employed in the present invention is any olefinically unsaturated monomer with a C=C double bond polymerizable with an acrylonitrile monomer and/or a methacrylonitrile monomer. The olefinically unsaturated monomer employed in the multimonomer mixture can be a single polymerizable monomer resulting in a terpolymer or a combination of polymerizable monomers resulting in a multipolymer. The olefinically unsaturated monomer generally includes but is not limited to acrylates, methacrylates, acrylamide and its derivatives, vinyl ethers, vinyl amides, vinyl ketones, styrenes, halogen containing monomers, ionic monomers, acid containing monomers, base containing monomers, olefins, and the like. The acrylates include but are not limited to C1 to C12 alkyl, aryl and cyclic acrylates such as methyl acrylate, ethyl acrylate, phenyl acrylate, butyl acrylate and isobornyl acrylate and functional derivatives of the acrylates such as 2-hydroxy ethyl acrylate, 2-chloro ethyl acrylate, 2-ethyl hexyl acrylate and the like. The preferred acrylates are methyl acrylate and ethyl acrylate. The methacrylates include but are not limited to C1 to C12 alkyl, aryl and cyclic methacrylates such as methyl methacrylate, ethyl methacrylate, phenyl methacrylate, butyl methacrylate and isobornyl methacrylate and functional derivatives of the methacrylates such as 2-hydroxy ethyl methacrylate, 2-chloro ethyl methacrylate, 2-ethyl hexyl methacrylate and the like. The preferred methacrylate is methyl methacrylate. The acrylamides and their N-substituted alkyl and aryl derivatives include but are not limited to acrylamide, N-methyl acrylamide, N-dimethyl acrylamide 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 ethers include but are not limited to C1 to C8 vinyl ethers such as ethyl vinyl ether, butyl vinyl ether and the like. The vinyl amides include but are not limited to vinyl pyrrolidone and the like. The vinyl ketones include but are not limited to C1 to C8 vinyl ketone such as ethyl vinyl ketone, butyl vinyl ketone and the like. The styrenes include but are not limited to methylstyrene, styrene, indene, a styrene of the formula (Formula Removed) wherein each of A, B, C, and D is independently selected from hydrogen (H) and C1 to C4 alkyl group, substituted styrenes, multiply-substituted styrenes and the like. The halogen containing monomers include but are not limited to vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide, vinylidene fluoride, halogen substituted propylene monomers and the like. The preferred halogen containing monomers are vinyl bromide and vinylidene chloride. 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, methacrylic acid, vinyl sulfonic acid, itaconic acid and the like. The preferred acid containing monomers are itaconic acid and vinyl sulfonic acid. The base containing monomers include but are not limited to vinyl pyridine, N-amino ethyl acrylamide, N-amino propyl acrylamide, N-amino ethyl acrylate, N-amino ethyl methacrylate and the like. The olefins include but are not limited to isoprene, butadiene, C2 to C8 straight chained and branched alpha-olefins such as propylene, ethylene, isobutylene, diisobutylene, 1-butene and the like. The preferred olefins are isobutylene, ethylene and propylene. The choice of olefmically unsaturated monomer or combination of monomers depends on the properties desired to impart to the resulting multipolymer and its end use. For instance, polymerizing monomers of acrylonitrile, methacryloni-trile, and styrene and/or indene results in a multipolymer and its end products with improved heat distortion temperature and glass transition temperature. Polymerizing monomers of acrylonitrile, methacrylonitrile, and isobutylene improves the flexibility of the multipolymer and its end products. Polymerizing monomers of acrylonitrile, methacrylonitrile, 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 a methacrylonitrile monomer enhances the colorability of the resulting multipolymer. Polymerizing monomers of acrylonitrile, methacrylonitrile, and a halogen containing monomer increases the flame resistance of the multipolymer and its end products. In the practice of the present invention the polymerization process is carried out as an emulsion, a solution, a suspension or in bulk. Preferably, the polymerization process is carried out as an emulsion, or a suspension. The present invention can be practiced as a semicontinuous or continuous process. Initially, acrylonitrile monomer, methacrylonitrile monomer, and olefmically unsaturated monomer is 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 99% by weight to about 20% by weight acrylonitrile monomer, about 0.1% by weight to about 80% by weight methacrylonitrile monomer, and about 0% by weight to about 40% by weight olefmically unsaturated monomer. Preferably, the initial multimonomer mixture is richer in acrylonitrile monomer than the multimonomer feed mixture because the acrylonitrile monomer is more soluble in the aqueous medium than is the methacrylonitrile monomer. 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 container containing aqueous medium. The reaction container 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 multim6nomer mixture is then heated to a temperature in the range of about 40°C to about 120°C, preferably about 50°C to about 90°C and most preferably about 65°C to about 75 °C. The temperature of the polymerization reaction is maintained throughout the process in the range of about 40 °C to about 120°C, preferably about 50°C to about 90°C and most preferably about 65°C to about 75°C. An initiator is added to the heated initial multimonomer mixture to start the polymerization reaction. The initiator is added to the reaction container generally as a single solution. The initiator is added generally in the range of about 0.01 % by weight to about 5% by weight of the total multimonomer mixture. Simultaneously, after, or preferably immediately after the polymerization reaction has been initiated, a multimonomer feed mixture of acrylonitrile monomer, methacrylonitrile monomer, and olefinically unsaturated monomer is incrementally or continuously added to the polymerization reaction in the reaction container. Preferably the multimonomer feed mixture is continuously added to the polymerization reaction. The combined weight of the unreacted acrylonitrile monomer, unreacted methacrylonitrile monomer, and unreacted olefinically unsaturated monomer present in the polymerizing mixture, at any time, is not greater than about 15% by weight, preferably not greater than about 10% by weight, and most preferably not greater than about 5% by weight of the polymerizing mixture. The multimonomer feed mixture contains about 99% by weight to about 20% by weight acrylonitrile monomer, 0.1 % by weight to about 80% by weight methacrylonitrile monomer, and 0.1% by weight to about 40% by weight olefinically unsaturated monomer. The molar ratio of the acrylonitrile monomer, the methacrylonitrile monomer, and the olefinically unsaturated monomer in the multimonomer feed mixture, is fixed and constant throughout the polymerization process resulting in a homogeneous multipolymer. The molar ratio of acrylonitrile monomer to methacrylonitrile monomer to olefinically unsaturated monomer depends on the desired acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer composition. The multipolymer composition is essentially the same as the composition of the multimonomer feed mixture. A molecular weight modifier is optionally added to the polymerization mixture. Preferably, a molecular weight modifier is employed in the polymerization mixture. The molecular weight modifier is added continuously or incrementally to the polymerization mixture. Preferably, the molecular weight modifier is added continuously to the polymerization mixture typically by being added into the multimonomer feed 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 are generally a mono-mercaptan, multifunctional mercaptan or combinations thereof. The mercaptans include but are not limited to C5 to C18 alkyl mercaptans whether straight chained, branched, substituted or unsubstituted, d-limonene dimercaptan, dipentene dimercaptan, and the like. The preferred mercaptans are the C5 to C12 alkyl mercaptans whether straight chained, branched, substituted or unsubstituted, for example dodecyl mercaptan, and 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 controls the molecular weight of the polymerized acrylonitrile/methacrylonitrile/olefmically unsaturated polymer chain by terminating the growing chain. The molecular weight modifier useful in the present invention produces an acrylonitrile/methacrylonitrile/olefmically unsaturated 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 polymerization mixture. Preferably, the initiator is added continuously. 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% by weight to about 5% by weight of the total comonomer 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. The initiator can be the same or a different initiator as is employed to start the polymerization reaction. The polymerization mixture is continuously or intermittently agitated by any known method, such as stirring, shaking, and the like. Preferably, the polymerization mixture is continuously agitated. The reaction is continued until polymerization has proceeded to the desired extent, generally from about 40% to about 99% conversion, and preferably from about 70% to about 95% conversion. The (polymerization reaction is stopped by cooling, adding an inhibitor, such as diethyl hydroxylamine, 4-methoxylphenol, and the like, discontinuing the multimonomer feed mixture and the like. The inhibitors and their use are known to those skilled in the art. It will be readily apparent to one skilled in the art that the acryloni-trile/methacrylonitrile/olefinically unsaturated multipolymer may be further modified by the addition of lubricants, dyes, leaching agents, plasticizers, pseudoplasticizers, pigments, delustering agents, stabilizers, static 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 melt characteristics and thermal stability of the multipolymer. At the conclusion of the polymerization reaction the acrylonitrile/meth-acrylonitrile/olefinically unsaturated multipolymer is isolated as a slurry, or a latex. Any known technique may be used to isolate the acrylonitrile/methacrylonitrile/olefm-ically unsaturated 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 acrylonitrile/rnethacrylonitrile/olefinically unsaturated multipolymer produced by the process of the instant invention is generally high nitrile multipoly-mers containing polymerized acrylonitrile monomer, methacrylonitrile monomer, and olefmically unsaturated monomer. The multipolymer comprises about 20% by weight to about 99% by weight polymerized acrylonitrile, about 0.1% by weight to about 80% by weight polymerized methacrylonitrile, and about 0.1% by weight to about 40% by weight polymerized olefmically unsaturated monomer. The acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer is thermally stable and melt processable without the addition of any additives or stabilizers. The multipolymer of the present invention may be further processed by spinning, molding, extruding and the like without the use of solvents. The acrylonitrile/methacrylonitrile/olefmically unsaturated multipolymer possesses excellent thermal, physical, and mechanical properties and can be readily oriented. Further, the acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer may be utilized in numerous applications such as for use as fibers, sheets, films, pipes, tubings, molded articles, and the like. Specific Embodiments The following example demonstrates the process and advantages of the present invention. Equipment. A 2 liter circulating hot water jacketed reactor was equipped with a reflux condenser, a thermocouple/controller, a paddle for agitation, which paddle was set at about 230 rpm, an argon purge tube (continuous), a monomer feed pump, and an initiator feed pump. Multimonomer feed mixture and ammonium persulfate initiator aqueous solution are metered, as separate single solutions, by Masterflex Microprocessor controlled feed pumps. Component. The overall polymerization components for Example 1 are as follows: Component Grains (gm) Water 1260.0 Rhofac RE-610 12.6 Acrylonitrile 228.9 Methacrylonitrile 153.3 Methyl Acrylate 37.8 N-octyl mercaptan 8.4 Ammonium Persulfate 2.646 Total: 1703.65 Procedure. The reactor was pre-charged with about 1260 gm of water and about 12.6 gm of Rhofac RE-610 surfactant, made by Rhone Poulenc, which had been pre-dissolved at about 50°C with stirring at about 200 rpm. The reactor was heated to about 70°C with continuous argon purging. The initial multimonomer mixture contained about 2.1 gm of n-octyl mercaptan, 39.9 gm of acrylonitrile and 2.1 gm of methacrylonitrile was added to the reactor. About 0.882 gm of ammonium persulfate initiator was added to the reactor to initiate the polymerization reaction. The multimonomer feed mixture containing about 6.3 gm of the n-octyl mercaptan was continuously pumped into the reactor at a constant, fixed 50/40/10 weight ratio of acrylonitrile monomer to methacrylonitrile monomer to methyl acrylate monomer. Simultaneously, about 1.764 gm of the ammonium persulfate initiator was pumped into the reactor as a 100 ml total volume aqueous solution. Both the multimonomer feed mixture stream and the initiator stream were fed into the reactor as separate streams. Total polymerization reaction time was about 6 hours. After the polymerization reaction was completed the resulting multipolymer emulsion was filtered through a piece of pre-weighed cheesecloth to collect and separate any coagulum from multipolymer. The coagulum is bundled in a cheesecloth and rinsed with warm tap water. The cheesecloth is dried overnight at about 60°C. Then the dried cheesecloth/coagulum is weighed. The coagulum was about 0.1 % by weight multimonomers. About 2500 gm of distilled water containing about 14.8 gm of aluminum sulfate was heated to about 75°C in a stainless steel beaker with continuous stirring. The filtered multipolymer emulsion was poured into the hot aluminum sulfate solution while stirring to coagulate the multipolymer as crumb. The multipolymer crumb was separated by hot filtration and then washed with about 2 to about 3 liters of distilled water. The washed multipolymer crumb was dried overnight on a filter. The multipolymer crumb was then washed by stirring in about 2 to about 3 liters of absolute methanol and soaked overnight. The slurry of multipolymer crumb was then filtered, and dried for about 3 to about 24 hours on a funnel. The multipolymer was then dried in a fluidized bed dryer at about 55°C for about 3 hours. The polymerization reaction resulted in a multipolymer composition for example 1 of about 50.4% by weight acrylonitrile, about 42.3% by weight methacrylonitrile, and about 7.3% by weight methyl acrylate. Example 2 The same procedure was followed as above for Example 1 except the mixture of components was a weight ratio of 52/43/5 of acrylonitrile to methacrylonitrile to methyl acrylate. Example 3 The same procedure was followed as above for Example 1 except the mixture of components was a weight ratio of 63/27/10 of acrylonitrile to methacrylonitrile to methyl acrylate. Comparative Example A. The same procedure was followed as above for Example 1 except the mixture of components was different in that the monomer feed did not contain the olefmically unsaturated monomer of methyl acrylate. The copolymerization reaction resulted in a copolymer composition of about 53.1 % by weight acrylonitrile and about 46.9% by weight methacrylonitrile. TESTING. Molecular Weight: The molecular weight (MW) of a polymer was determined by Gel Permeation Chromatography (GPC) in dimethyl formamide solvent and calibrated with polystyrene standards. This is a known standard method. NMR Analysis: Samples for NMR Analysis were prepared using DMSO-D6 as solvent. Compositions were determined using 1H spectra and sequence distributions were determined using 13C spectra. 1H spectra were obtained using a Varian Gemini 300 Spectrometer at 300 MHz and/or a Varian VXR-400 Spectrometer at 400 MHz. 13C spectra were obtained using a Varian Gemini 300 Spectrometer at 75.5 MHz and/or a Varian VXR-400 Spectrometer at 100.7 MHz. The numerical data is presented in Table I. Brabender Plasticorder: The Brabender plasticorder, available from C.W. Brabender Instruments Inc. , South Hackensack, New Jersey, is a low shear melt mixing device that measures the torque (meter-grams, m-g) required to melt stir a molten polymer. The test determines whether a polymer may be melted and processed employing standard thermoplastic equipment. The Brabender analyses were run at about 200°C with torque readings taken at about 5 minute intervals to about 30 minutes. This method measures polymer degradation as a function of time, temperature, and physical abrading. The numerical data is presented in Table II. Results: A very uniform and homogeneous acrylonitrile/methacrylonitrile/methyl acrylate terpolymer was produced by the process described herein. The final conversion to multipolymer was about 90% based on total multimonomers. t The weight average molecular weight of the multipolymer Examples 1, 2 and 3 were in the range of about 42,000 to about 48,000. Polydispersity, or ratio between weight average molecular weight to number average molecular weight was about 2.0. The desired multipolymer composition of example 1 was 50/40/10 acrylonitrile/methacrylonitrile/methyl acrylate by weight. NMR data demonstrated that the sequencing in the example 1 multipolymer of the acrylonitrile monomer (AN), methacryloriitrile monomer (MAN) and methyl acrylate monomer (MA) was interdispersed and had a high degree of randomness as shown in Table I. TABLE I (Table Removed) * A=acrylonitrile, M=methacrylonitrile Methyl acrylate was not measured because the technique is not sensitive to the methyl acrylate. The Brabender torque data for examples 1, 2 and 3 was in the range of about 564 m-g to about 900 m-g and for comparative example A was 940 m-g to 1920 m-g. This demonstrates that the multipolymer is more easily melt processed than the comparative example A. The Brabender torque data is shown in Tables II and III below: TABLE II (Table Removed) The above table demonstrates the use of a termonomer decreases viscosity and the multipolymer is more easily processed. TABLE III (Table Removed) The above table demonstrates the improved melt stability of the multipolymer compared to the comparative copolymer at a similar molecular weight. From the above descriptions of the invention, those skilled in the art will perceive improvements, changes and modifications in the invention. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims. WE CLAIM-; 1. A process for polymerizing (a) acrylonitrile monomer, (b) methacrylonitrile monomer and (c) an olefmically unsaturated monomer selected from the group consisting of methyl acrylate, ethyl aery late, phenyl acrylate, butyl acrylate, isobornyl acrylate, 2-hydroxy ether acrylate, 2-chloro ethyl acrylate, 2-ethyl hexl acrylate, methyl methacrylate, ethyl methacrylate, phenyl methacrylate, butyl methacrylate, isobormyl methacrylate, 2-hydroxyethyl methacrylate, 2-chloro ethyl methacrylate, 2-ethyl hexyl methacrylate, acrylamide, N-methyl acrylamide, N-dimethyl acrylamide, vinyl acetate, vinyl propionate, vinyl butyrate, ethyl vinyl ether, butyl vinyl ether, vinyl pyrrolidone, ethyl vinyl ketone, butyl vinyl ketone, styrene, methyl styrene, indene, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide, vinylidene fluoride, sodium vinyl sulfonate, sodium styrene sulfonate, sodium methallyl sulfonate, sodium acrylate, sodium methacrylate, acrylic acid, methacrylic acid, vinyl sulfonic acid, itaconic acid, vinyl pyridine, N-amino ethyl acrylamide, N-amino propyl acrylamide, N-amino ethyl acrylate, N-amino ethyl methacrylate, propylene, ethylene, isobutylene, diisobutylene, 1-butene, and combinations thereof to produce a melt processable acrylonitrile/methacrylonitrile/olefinically unsaturated copolymer, said process comprising the steps of: (i) heating an initial mixture of about 0.1 to 15 wt % monomer (a), about 20 to about 99 wt % monomer (b), and about 0 to about 40 wt % monomer (c) under an inert atmosphere in the range of about 40°C to about 120°C wherein each wt % recited is with respect to the total initial mixture weight; (ii) adding an initiator to the initial monomers mixture of Step (i) to start a polymerization reaction wherein said initiator comprises from about 0.01 wt % to about 5 wt % of the total initial mixture weight; and wherein the initiator is selected from the group consisting of azo compounds, peroxides, hydroperoxides, alkyl peroxides, peroxydicarbonates, peroxyesters, dialkyl peroxides, persulfates, perphosphates, and combinations thereof; (iii) adding a three monomer feed mixture comprising about 20 to about 99 wt % monomer (a), about 0.1 to about 80 wt % monomer (b), and about 0.1 to about 40 wt % monomer (c) to the initial polymerization mixture of Step (ii) wherein the three monomer feed mixture has a fixed and constant molar ratio of monomer (a) to monomer (b) to monomer (c) within the specified wt % ranges and is maintained at that fixed ratio at a constant rate of addition which is less than or equal to the polymerization rate so that the combined weight of unreacted monomer (a), (b), and (c) is never greater than 15 wt % of the polymerizing mixture throughout the polymerization; (iv) optionally, continuously or incrementally adding a molecular weight modifier to the polymerization mixture in the range of about 0 to about 5 wt % of the total weight of the reaction mixture wherein the molecular weight modifier is selected from the group consisting of mercaptans, alcohols, halogen compounds, and combinations thereof; and (v) maintaining the polymerization temperature in the range of about 40°C to about 120°C forming a homogeneous copolymer wherein the copolymer composition is similar to the three monomer molar feed ratio and wherein the copolymer is melt processable without the use of solvents. 2. The process as claimed in claim 1 wherein the polymerization of Step (v) is conducted as an emulsion, a solution, a suspension, or in bulk. 3. The process as claimed in claim 1 wherein the molecular weight modifier is added to the initial three monomer mixture of Step (i), the three monomer feed mixture of Step (iii), or to both mixtures. 4. The process as claimed in claim 1 wherein the molecular weight modifier of Step (iv) is a mercaptan selected from the group consisting of C5 to CIS alkyl mercaptans wherein the alkyl groups are straight- chained, branched, substituted, unsubstituted, and combinations thereof. 5. A process for polymerizing (a) acrylonitrile monomer, (b) methacrylonitrile monomer and (c) an olefinically unsaturated monomer substantially as herein described with reference to the foregoing examples.

Full Text

The present invention relates to a process for polymerizing (a) acrylonitrile monomer, (b) methacrylonitrile monomer and (c) an olefmically unsaturated monomer.
The present invention relates to a process for producing a homogenous acrylonitrile/methacrylonitrile multipolymer, with improved thermal stability, that is melt processable. More specifically, the invention relates to a monomer starved process for producing an acrylonitrile/methacrylonitrile/olefinically unsatruated multipolymer in which the polymerization rate exceeds or equals the addition rate of the multimonomers of acrylonitrile monomer, methacrylonitrile monomer, and olefinically unsaturated monomer.
Acrylic polymers are desirable to produce fibrous textiles, films, molded objects, packaging applications, and the like because the acrylic polymers have a high nitrile polymer content. Nitrile polymers have excellent physical, thermal, and mechanical properties such barrier properties, chemical resistance, rigidity, heat resistance, UV resistance, moisture, retention, and bacteria resistance. Acrylonitrile and methacrylonitrile monomers are nitrile monomers useful to produce acrylic polymers.
In the past, high nitrile polymers have been limited to containing about 20% by weight polymerized acrylonitrile since higher acrylonitrile content leads to non-melt processable polymers. U.S. Patent No. 3,565,876 discloses that up to about 20% by weight of an acrylonitrile monomer can be copolymerized with a methacrylo-nitrile monomer to form an extrudable copolymer which can be readily oriented and possesses excellent physical properties. Increasing the acrylonitrile content above about 20% by weight in the acrylonitrile/methacrylonitrile copolymer results in a resin which is thermally unstable and not processable by any standard economical commercial melt processing techniques including extrusion.
High acrylic polymers are conventionally processed by solvent techniques such as wet spinning acrylic fibers. The use of solvents is disadvantageous because the solvents must be removed from the acrylic polymer prior to end use resulting in voids in the acrylic fiber. Furthermore, the solvents are typically toxic and their disposal has negative impact on the environment.
U.S. Patent No. 5,106,925 discloses a process for producing an acrylonitrile/methacrylonitrile copolymer that is melt processable in the absence of solvent. The patent discloses that acrylonitrile/methacrylonitrile copolymer is produced under flooded monomer process conditions. In the flooded monomer process, the molar weight ratios of the acrylonitrile monomer and methacrylonitrile monomer must be carefully controlled and adjusted throughout the polymerization process in relationship to the conversion of the comonomers to copolymer. The copolymer conversion is tracked throughout the process so that the addition of comonomers may be adjusted to obtain the desired copolymer. Thus, this process is disadvantageous because of the necessity to track, to predict the copolymer conversion rate, and to adjust the rate of addition of the comonomers throughout the process.
It is advantageous to produce a homogeneous acrylonitrile/methacrylo-nitrile/olefinically unsaturated multipolymer with improved thermoplastic properties which multipolymers are melt processable in the absence of a solvent. Further, it is desirable to produce an acrylonitrile/methacrylonitrile/olefmically unsaturated multipolymer by a process in which the feed ratio of the monomers is fixed and
constant throughout the polymerization process. It is advantageous to confer improved properties on an acrylonitrile/methacrylonitrile copolymer by the addition of an olefinically unsaturated polymerizable monomer into the acryloni-trile/methacrylonitrile copolymer. The addition of an olefinically unsaturated monomer to an acrylonitrile/methacrylonitrile copolymer improves properties such as thermal stability, strength, rheology, processability, colorability, moisture retention, flexibility, and the like.
Summary of the Invention
The present invention provides a new and an improved process for producing an acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymerwith improved thermal stability, excellent mechanical, and excellent physical properties. The process comprises polymerizing a mixture of acrylonitrile monomer, methacrylo-nitrile monomer, and olefinically unsaturated monomer in which the rate of addition of the acrylonitrile monomer, the methacrylonitrile monomer, and the olefinically unsaturated monomer is set to be equal to or less than the rate of polymerization to maintain a monomer starved process. Further, the weight of unreacted acrylonitrile monomer, unreacted methacrylonitrile monomer, and unreacted olefinically unsaturated monomer is not greater than 15% of the weight of the polymerizing mixture. Further, the molar ratio of acrylonitrile monomer, methacrylonitrile monomer, and olefinically unsaturated monomer is fixed and constant for the multimonomer feed throughout the polymerization process.
In particular, the process for polymerizing an acrylonitrile monomer, a methacrylonitrile monomer, and an olefinically unsaturated monomer for producing acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer comprises the steps of;
1. heating an initial multimonomer mixture comprising acryloni
trile monomer and methacrylonitrile monomer under an inert
atmosphere in the range of about 40°C to about 120°C,
2. adding an initiator to the initial multimonomer mixture to start
a polymerization reaction, and
unreacted monomer (a), (b), and (c) is never greater than 15 wt % of the
polymerizing mixture throughout the polymerization;
(iv) optionally, continuously or incrementally adding a molecular weight
modifier to the polymerization mixture in the range of about 0 to about 5 wt %
of the total weight of the reaction mixture wherein the molecular weight
modifier is selected from the group consisting of mercaptans, alcohols, halogen
compounds, and combinations thereof; and
(v) maintaining the polymerization temperature in the range of about 40°C
to about 120°C forming a homogeneous copolmer wherein the copolymer
composition is similar to the three monomer molar feed ratio and wherein the
copolymer is melt processable without the use of solvents.
Detailed Description of the Invention
The present invention relates to a process for producing thermally stable melt processable homogeneous acrytonitrile/methacrylonitrile/olefinically unsaturated multipolymes.
The new and improved process for producing a thermally stable melt processable multipolymer of acrylonitrile, methacrylonitrile and olefmically unsaturated monomer is accomplished by controlling the rate of addition of the acrylonitrile monomer, methacrylonitrile monomer, and olefmically 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 multimour^er mixture addition rate. The low concentration of the multimonomers during the addition step prevents long sequences of acrylonitrile monomer in the multipolymer. The multipolymer contains small sequences of methacrylonitrile and olefmically unsaturated monomer interdispersed between small sequences of bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide, vinylidene
fluoride, sodium vinyl sulfonate, sodium styrene sulfonate, sodium methallyl
sulfonate, sodium acrylae, sodium methacrylate, acrylic acid, methacrylic acid,
vinyl sulfonic acid, itaconic acid, vinyl pyridine, N-amino ethyl acrylamide, N-
amino propyl acrylamide N-amino ethyl acrylate, N-amino ethyl methacrylate,
propylene, ethylene, isobutylene, diisobutylene, 1-butene, and combinations
thereof, to produce a melt processable
acrylonitrile/methacrylonitrile/olefmically unsaturated copolymer, said process comprising the steps of:
(i) heating an initial mixture of about 0.1 to 15 wt % monomer (a), about 20 to about 99 wt % monomer (b), and about 0 to about 40 wt % monomer (c) under an inert atmosphere in the range of about 40°C to about 120°C wherein each wt % recited is with respect to the total initial mixture weight; (ii) adding an initiator to the initial monomers mixture of step (i) to start a polymerization reaction wherein said initiator comprises from about 0.01 wt % to about 5 wt % of the total initial mixture weight; and wherein the initiator is selected from the group consisting of azo compounds, peroxides, hydroperoxides, alkyl peroxides peroxydicarbonaes, peroxyesters, dialkyl peroxides, persulfates, perphosphates, and combinations thereof; (iii) adding a three monomer feed mixture comprising about 20 to about 99 wt % monomer (a), about 0.1 to about 80 wt % monomer (b), and about 0.1 to about 40 wt % monomer (c; +o the initial polymerization mixture of step (ii) wherein the three monomer feed mixture has a fixed and constant molar ratio of monomer (a) to monomer (b) to monomer (c) within the specified wt % ranges and is maintained at the fixed ratio at a constant rate of addition which is less than or equal to the polymerization rate so that the combined weight of 3. adding a multimonomer fed mixture comprising an acrylonitrile monomer, a methacrylonitrile monmer and an olefinically unsaturated monomer to the polymeriztion mixture wherein the multimonomer feed mixture has a fixed and constant molar ratio of acrylonitrile monomer to methacrylonitrile monomer to olefinically unsaturated monomer and further wherein the addition rate of the multimonomer feed mixture is less than or equal to the polymerizationrate.
The process of the present invention produces homogeneous
acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymers in which
the units of acrylonitrile, methacrylonitrile, and olefinically unsaturated
monomer are interdispersed randomly throughout the polymerized chain in
relatively small monomer units resulting in a thermally stable melt processable
multipolymer with improved characteristics. The
acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer is melt processable in the absence of solvent or plasticizing agent to produce acrylic products.
Thus according to the present invention, there is provided a process for polymerizing (a) acrylonitrile monomer, (b) methacrylonitrile monomer and (c) an olefinincally unsaturated monomer selected from the group consisting of methyl acrylate, ethyl acrylate, phenyl acrylate, butyl acrylate, isobornyl acrylate, 2-hydroxy ether acrylate, 2-chloro ethyl acrylate, 2-ethyl hexyl acrylate, methyl methacrylate, ethyl methacrylate, phenyl rr.;"thacrylate, butyl methacrylate, isobornyl methacrylate, 2-hydroxyethyl methacrylate, 2-chloro ethyl methacrylate, 2-ethyl hexyl methacrylate, acrylamide, N-methyl acrylamide, N-dimethyl acrylamide, vinyl acetae, vinyl propionate, vinyl butyrate, ethyl vinyl ether, butyl vinyl ether, vinyl pyrrolidone, ethyl vinyl ketone, butyl vinyl ketone, styrene, methyl styrene, indene, vinyl chloride, vinyl acrylonitrile for example, AN-AN-X-MAN-AN-X-X-AN-MAN-MAN-X(X=olefm-ically unsaturated monomer), allowing for melt processability of the acryloni-trile/methacrylonitrile/olefinically unsaturated multipolymer in the absence of solvent. Additionally, employing the olefinically unsaturated monomer in the acryloni-trile/methacrylonitrile polymer backbone reduces the amount of repeating acrylonitrile sequences resulting in a more random multipolymer.
The rate of addition of the acrylonitrile monomer, methacrylonitrile monomer, and olefinically unsaturated monomer is incremental or continuous, preferably continuous, throughout the polymerization reaction. The molar ratio of the multimonomer feed mixture of acrylonitrile monomer, methacrylonitrile monomer, and olefinically unsaturated monomer is constant throughout the process. The process produces a homogeneous composition of the multipolymer similar to the
molar ratio of the incoming multimonomer feed mixture.
i The olefinically unsaturated monomer employed in the present
invention is any olefinically unsaturated monomer with a C=C double bond polymerizable with an acrylonitrile monomer and/or a methacrylonitrile monomer. The olefinically unsaturated monomer employed in the multimonomer mixture can be a single polymerizable monomer resulting in a terpolymer or a combination of polymerizable monomers resulting in a multipolymer.
The olefinically unsaturated monomer generally includes but is not limited to acrylates, methacrylates, acrylamide and its derivatives, vinyl ethers, vinyl amides, vinyl ketones, styrenes, halogen containing monomers, ionic monomers, acid containing monomers, base containing monomers, olefins, and the like.
The acrylates include but are not limited to C1 to C12 alkyl, aryl and cyclic acrylates such as methyl acrylate, ethyl acrylate, phenyl acrylate, butyl acrylate and isobornyl acrylate and functional derivatives of the acrylates such as 2-hydroxy ethyl acrylate, 2-chloro ethyl acrylate, 2-ethyl hexyl acrylate and the like. The preferred acrylates are methyl acrylate and ethyl acrylate.
The methacrylates include but are not limited to C1 to C12 alkyl, aryl and cyclic methacrylates such as methyl methacrylate, ethyl methacrylate, phenyl methacrylate, butyl methacrylate and isobornyl methacrylate and functional derivatives of the methacrylates such as 2-hydroxy ethyl methacrylate, 2-chloro ethyl methacrylate, 2-ethyl hexyl methacrylate and the like. The preferred methacrylate is methyl methacrylate.
The acrylamides and their N-substituted alkyl and aryl derivatives include but are not limited to acrylamide, N-methyl acrylamide, N-dimethyl acrylamide 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 ethers include but are not limited to C1 to C8 vinyl ethers such as ethyl vinyl ether, butyl vinyl ether and the like.
The vinyl amides include but are not limited to vinyl pyrrolidone and the like.
The vinyl ketones include but are not limited to C1 to C8 vinyl ketone such as ethyl vinyl ketone, butyl vinyl ketone and the like.
The styrenes include but are not limited to methylstyrene, styrene, indene, a styrene of the formula
(Formula Removed)
wherein each of A, B, C, and D is independently selected from hydrogen (H) and C1 to C4 alkyl group, substituted styrenes, multiply-substituted styrenes and the like.
The halogen containing monomers include but are not limited to vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide,
vinylidene fluoride, halogen substituted propylene monomers and the like. The preferred halogen containing monomers are vinyl bromide and vinylidene chloride.
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, methacrylic acid, vinyl sulfonic acid, itaconic acid and the like. The preferred acid containing monomers are itaconic acid and vinyl sulfonic acid.
The base containing monomers include but are not limited to vinyl pyridine, N-amino ethyl acrylamide, N-amino propyl acrylamide, N-amino ethyl acrylate, N-amino ethyl methacrylate and the like.
The olefins include but are not limited to isoprene, butadiene, C2 to C8 straight chained and branched alpha-olefins such as propylene, ethylene, isobutylene, diisobutylene, 1-butene and the like. The preferred olefins are isobutylene, ethylene and propylene.
The choice of olefmically unsaturated monomer or combination of monomers depends on the properties desired to impart to the resulting multipolymer and its end use. For instance, polymerizing monomers of acrylonitrile, methacryloni-trile, and styrene and/or indene results in a multipolymer and its end products with improved heat distortion temperature and glass transition temperature. Polymerizing monomers of acrylonitrile, methacrylonitrile, and isobutylene improves the flexibility of the multipolymer and its end products. Polymerizing monomers of acrylonitrile, methacrylonitrile, 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 a methacrylonitrile monomer enhances the colorability of the resulting multipolymer. Polymerizing monomers of acrylonitrile, methacrylonitrile, and a halogen containing monomer increases the flame resistance of the multipolymer and its end products.
In the practice of the present invention the polymerization process is carried out as an emulsion, a solution, a suspension or in bulk. Preferably, the polymerization process is carried out as an emulsion, or a suspension. The present invention can be practiced as a semicontinuous or continuous process.
Initially, acrylonitrile monomer, methacrylonitrile monomer, and olefmically unsaturated monomer is 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 99% by weight to about 20% by weight acrylonitrile monomer, about 0.1% by weight to about 80% by weight methacrylonitrile monomer, and about 0% by weight to about 40% by weight olefmically unsaturated monomer. Preferably, the initial multimonomer mixture is richer in acrylonitrile monomer than the multimonomer feed mixture because the acrylonitrile monomer is more soluble in the aqueous medium than is the methacrylonitrile monomer.
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 container containing aqueous medium. The reaction container 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 multim6nomer mixture is then heated to a temperature in the range of
about 40°C to about 120°C, preferably about 50°C to about 90°C and most preferably about 65°C to about 75 °C. The temperature of the polymerization reaction is maintained throughout the process in the range of about 40 °C to about
120°C, preferably about 50°C to about 90°C and most preferably about 65°C to
about 75°C.
An initiator is added to the heated initial multimonomer mixture to start
the polymerization reaction. The initiator is added to the reaction container generally

as a single solution. The initiator is added generally in the range of about 0.01 % by
weight to about 5% by weight of the total multimonomer mixture.
Simultaneously, after, or preferably immediately after the polymerization reaction has been initiated, a multimonomer feed mixture of acrylonitrile monomer, methacrylonitrile monomer, and olefinically unsaturated monomer is incrementally or continuously added to the polymerization reaction in the reaction container. Preferably the multimonomer feed mixture is continuously added to the polymerization reaction. The combined weight of the unreacted acrylonitrile monomer, unreacted methacrylonitrile monomer, and unreacted olefinically unsaturated monomer present in the polymerizing mixture, at any time, is not greater than about 15% by weight, preferably not greater than about 10% by weight, and most preferably not greater than about 5% by weight of the polymerizing mixture.
The multimonomer feed mixture contains about 99% by weight to about 20% by weight acrylonitrile monomer, 0.1 % by weight to about 80% by weight methacrylonitrile monomer, and 0.1% by weight to about 40% by weight olefinically unsaturated monomer. The molar ratio of the acrylonitrile monomer, the methacrylonitrile monomer, and the olefinically unsaturated monomer in the multimonomer feed mixture, is fixed and constant throughout the polymerization process resulting in a homogeneous multipolymer. The molar ratio of acrylonitrile monomer to methacrylonitrile monomer to olefinically unsaturated monomer depends on the desired acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer composition. The multipolymer composition is essentially the same as the composition of the multimonomer feed mixture.
A molecular weight modifier is optionally added to the polymerization mixture. Preferably, a molecular weight modifier is employed in the polymerization mixture. The molecular weight modifier is added continuously or incrementally to
the polymerization mixture. Preferably, the molecular weight modifier is added continuously to the polymerization mixture typically by being added into the multimonomer feed 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 are generally a mono-mercaptan, multifunctional mercaptan or combinations thereof. The mercaptans include but are not limited to C5 to C18 alkyl mercaptans whether straight chained, branched, substituted or unsubstituted, d-limonene dimercaptan, dipentene dimercaptan, and the like. The preferred mercaptans are the C5 to C12 alkyl mercaptans whether straight chained, branched, substituted or unsubstituted, for example dodecyl mercaptan, and 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 controls the molecular weight of the polymerized acrylonitrile/methacrylonitrile/olefmically unsaturated polymer chain by terminating the growing chain. The molecular weight modifier useful in the present invention produces an acrylonitrile/methacrylonitrile/olefmically unsaturated 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 polymerization mixture. Preferably, the initiator is added continuously. 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% by weight to about 5% by weight of the total comonomer 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. The initiator can be the same or a different initiator as is employed to start the polymerization reaction.
The polymerization mixture is continuously or intermittently agitated by any known method, such as stirring, shaking, and the like. Preferably, the polymerization mixture is continuously agitated.
The reaction is continued until polymerization has proceeded to the desired extent, generally from about 40% to about 99% conversion, and preferably from about 70% to about 95% conversion.
The (polymerization reaction is stopped by cooling, adding an inhibitor, such as diethyl hydroxylamine, 4-methoxylphenol, and the like, discontinuing the multimonomer feed mixture and the like. The inhibitors and their use are known to those skilled in the art.
It will be readily apparent to one skilled in the art that the acryloni-trile/methacrylonitrile/olefinically unsaturated multipolymer may be further modified by the addition of lubricants, dyes, leaching agents, plasticizers, pseudoplasticizers, pigments, delustering agents, stabilizers, static 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 melt characteristics and thermal stability of the multipolymer.
At the conclusion of the polymerization reaction the acrylonitrile/meth-acrylonitrile/olefinically unsaturated multipolymer is isolated as a slurry, or a latex. Any known technique may be used to isolate the acrylonitrile/methacrylonitrile/olefm-ically unsaturated 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 acrylonitrile/rnethacrylonitrile/olefinically unsaturated multipolymer produced by the process of the instant invention is generally high nitrile multipoly-mers containing polymerized acrylonitrile monomer, methacrylonitrile monomer, and olefmically unsaturated monomer. The multipolymer comprises about 20% by weight to about 99% by weight polymerized acrylonitrile, about 0.1% by weight to about 80% by weight polymerized methacrylonitrile, and about 0.1% by weight to about 40% by weight polymerized olefmically unsaturated monomer.
The acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer is thermally stable and melt processable without the addition of any additives or stabilizers. The multipolymer of the present invention may be further processed by spinning, molding, extruding and the like without the use of solvents. The acrylonitrile/methacrylonitrile/olefmically unsaturated multipolymer possesses excellent thermal, physical, and mechanical properties and can be readily oriented. Further, the acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer may be utilized in numerous applications such as for use as fibers, sheets, films, pipes, tubings, molded articles, and the like.
Specific Embodiments
The following example demonstrates the process and advantages of the present invention. Equipment.
A 2 liter circulating hot water jacketed reactor was equipped with a reflux condenser, a thermocouple/controller, a paddle for agitation, which paddle was set at about 230 rpm, an argon purge tube (continuous), a monomer feed pump, and an initiator feed pump. Multimonomer feed mixture and ammonium persulfate initiator aqueous solution are metered, as separate single solutions, by Masterflex Microprocessor controlled feed pumps. Component.
The overall polymerization components for Example 1 are as follows:
Component Grains (gm)
Water 1260.0
Rhofac RE-610 12.6
Acrylonitrile 228.9
Methacrylonitrile 153.3
Methyl Acrylate 37.8
N-octyl mercaptan 8.4
Ammonium Persulfate 2.646
Total: 1703.65
Procedure.
The reactor was pre-charged with about 1260 gm of water and about 12.6 gm of Rhofac RE-610 surfactant, made by Rhone Poulenc, which had been pre-dissolved at about 50°C with stirring at about 200 rpm. The reactor was heated to about 70°C with continuous argon purging. The initial multimonomer mixture contained about 2.1 gm of n-octyl mercaptan, 39.9 gm of acrylonitrile and 2.1 gm of methacrylonitrile was added to the reactor. About 0.882 gm of ammonium persulfate initiator was added to the reactor to initiate the polymerization reaction.
The multimonomer feed mixture containing about 6.3 gm of the n-octyl mercaptan was continuously pumped into the reactor at a constant, fixed 50/40/10 weight ratio of acrylonitrile monomer to methacrylonitrile monomer to methyl acrylate monomer. Simultaneously, about 1.764 gm of the ammonium persulfate initiator was pumped into the reactor as a 100 ml total volume aqueous solution. Both the multimonomer feed mixture stream and the initiator stream were fed into the reactor as separate streams. Total polymerization reaction time was about 6 hours.
After the polymerization reaction was completed the resulting multipolymer emulsion was filtered through a piece of pre-weighed cheesecloth to collect and separate any coagulum from multipolymer. The coagulum is bundled in a cheesecloth and rinsed with warm tap water. The cheesecloth is dried overnight at about 60°C. Then the dried cheesecloth/coagulum is weighed. The coagulum was about 0.1 % by weight multimonomers.
About 2500 gm of distilled water containing about 14.8 gm of aluminum sulfate was heated to about 75°C in a stainless steel beaker with continuous stirring. The filtered multipolymer emulsion was poured into the hot aluminum sulfate solution while stirring to coagulate the multipolymer as crumb. The multipolymer crumb was separated by hot filtration and then washed with about 2 to about 3 liters of distilled water. The washed multipolymer crumb was dried overnight on a filter. The multipolymer crumb was then washed by stirring in about 2 to about 3 liters of absolute methanol and soaked overnight. The slurry of multipolymer crumb was then filtered, and dried for about 3 to about 24 hours on a funnel. The multipolymer was then dried in a fluidized bed dryer at about 55°C for about 3 hours.
The polymerization reaction resulted in a multipolymer composition for example 1 of about 50.4% by weight acrylonitrile, about 42.3% by weight methacrylonitrile, and about 7.3% by weight methyl acrylate.
Example 2
The same procedure was followed as above for Example 1 except the mixture of components was a weight ratio of 52/43/5 of acrylonitrile to methacrylonitrile to methyl acrylate.
Example 3
The same procedure was followed as above for Example 1 except the mixture of components was a weight ratio of 63/27/10 of acrylonitrile to methacrylonitrile to methyl acrylate. Comparative Example A.
The same procedure was followed as above for Example 1 except the mixture of components was different in that the monomer feed did not contain the olefmically unsaturated monomer of methyl acrylate. The copolymerization reaction resulted in a copolymer composition of about 53.1 % by weight acrylonitrile and about 46.9% by weight methacrylonitrile.
TESTING. Molecular Weight:
The molecular weight (MW) of a polymer was determined by Gel Permeation Chromatography (GPC) in dimethyl formamide solvent and calibrated with polystyrene standards. This is a known standard method. NMR Analysis:
Samples for NMR Analysis were prepared using DMSO-D6 as solvent. Compositions were determined using 1H spectra and sequence distributions were determined using 13C spectra. 1H spectra were obtained using a Varian Gemini 300 Spectrometer at 300 MHz and/or a Varian VXR-400 Spectrometer at 400 MHz. 13C spectra were obtained using a Varian Gemini 300 Spectrometer at 75.5 MHz and/or a Varian VXR-400 Spectrometer at 100.7 MHz. The numerical data is presented in Table I. Brabender Plasticorder:
The Brabender plasticorder, available from C.W. Brabender Instruments Inc. , South Hackensack, New Jersey, is a low shear melt mixing device that measures the torque (meter-grams, m-g) required to melt stir a molten polymer. The test determines whether a polymer may be melted and processed employing standard thermoplastic equipment. The Brabender analyses were run at about 200°C with torque readings taken at about 5 minute intervals to about 30 minutes. This method measures polymer degradation as a function of time, temperature, and physical abrading. The numerical data is presented in Table II. Results:
A very uniform and homogeneous acrylonitrile/methacrylonitrile/methyl acrylate terpolymer was produced by the process described herein. The final conversion to multipolymer was about 90% based on total multimonomers.
t
The weight average molecular weight of the multipolymer Examples 1, 2 and 3 were in the range of about 42,000 to about 48,000. Polydispersity, or ratio between weight average molecular weight to number average molecular weight was about 2.0.
The desired multipolymer composition of example 1 was 50/40/10 acrylonitrile/methacrylonitrile/methyl acrylate by weight. NMR data demonstrated that the sequencing in the example 1 multipolymer of the acrylonitrile monomer (AN), methacryloriitrile monomer (MAN) and methyl acrylate monomer (MA) was interdispersed and had a high degree of randomness as shown in Table I.
TABLE I
(Table Removed)

* A=acrylonitrile, M=methacrylonitrile
Methyl acrylate was not measured because the technique is not sensitive to the methyl
acrylate.
The Brabender torque data for examples 1, 2 and 3 was in the range of about 564 m-g to about 900 m-g and for comparative example A was 940 m-g to 1920 m-g. This demonstrates that the multipolymer is more easily melt processed than the comparative example A. The Brabender torque data is shown in Tables II and III below:
TABLE II
(Table Removed)
The above table demonstrates the use of a termonomer decreases
viscosity and the multipolymer is more easily processed.
TABLE III
(Table Removed)
The above table demonstrates the improved melt stability of the multipolymer compared to the comparative copolymer at a similar molecular weight.
From the above descriptions of the invention, those skilled in the art will perceive improvements, changes and modifications in the invention. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.

WE CLAIM-;
1. A process for polymerizing (a) acrylonitrile monomer, (b) methacrylonitrile monomer and (c) an olefmically unsaturated monomer selected from the group consisting of methyl acrylate, ethyl aery late, phenyl acrylate, butyl acrylate, isobornyl acrylate, 2-hydroxy ether acrylate, 2-chloro ethyl acrylate, 2-ethyl hexl acrylate, methyl methacrylate, ethyl methacrylate, phenyl methacrylate, butyl methacrylate, isobormyl methacrylate, 2-hydroxyethyl methacrylate, 2-chloro ethyl methacrylate, 2-ethyl hexyl methacrylate, acrylamide, N-methyl acrylamide, N-dimethyl acrylamide, vinyl acetate, vinyl propionate, vinyl butyrate, ethyl vinyl ether, butyl vinyl ether, vinyl pyrrolidone, ethyl vinyl ketone, butyl vinyl ketone, styrene, methyl styrene, indene, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide, vinylidene fluoride, sodium vinyl sulfonate, sodium styrene sulfonate, sodium methallyl sulfonate, sodium acrylate, sodium methacrylate, acrylic acid, methacrylic acid, vinyl sulfonic acid, itaconic acid, vinyl pyridine, N-amino ethyl acrylamide, N-amino propyl acrylamide, N-amino ethyl acrylate, N-amino ethyl methacrylate, propylene, ethylene, isobutylene, diisobutylene, 1-butene, and combinations thereof to produce a melt processable acrylonitrile/methacrylonitrile/olefinically unsaturated copolymer, said process comprising the steps of:
(i) heating an initial mixture of about 0.1 to 15 wt % monomer (a), about 20 to about 99 wt % monomer (b), and about 0 to about 40 wt % monomer (c) under an inert atmosphere in the range of about 40°C to
about 120°C wherein each wt % recited is with respect to the total initial mixture weight;
(ii) adding an initiator to the initial monomers mixture of Step (i) to start a polymerization reaction wherein said initiator comprises from about 0.01 wt % to about 5 wt % of the total initial mixture weight; and wherein the initiator is selected from the group consisting of azo compounds, peroxides, hydroperoxides, alkyl peroxides, peroxydicarbonates, peroxyesters, dialkyl peroxides, persulfates, perphosphates, and combinations thereof;
(iii) adding a three monomer feed mixture comprising about 20 to about 99 wt % monomer (a), about 0.1 to about 80 wt % monomer (b), and about 0.1 to about 40 wt % monomer (c) to the initial polymerization mixture of Step (ii) wherein the three monomer feed mixture has a fixed and constant molar ratio of monomer (a) to monomer (b) to monomer (c) within the specified wt % ranges and is maintained at that fixed ratio at a constant rate of addition which is less than or equal to the polymerization rate so that the combined weight of unreacted monomer (a), (b), and (c) is never greater than 15 wt % of the polymerizing mixture throughout the polymerization;
(iv) optionally, continuously or incrementally adding a molecular weight modifier to the polymerization mixture in the range of about 0 to
about 5 wt % of the total weight of the reaction mixture wherein the molecular weight modifier is selected from the group consisting of mercaptans, alcohols, halogen compounds, and combinations thereof; and
(v) maintaining the polymerization temperature in the range of about 40°C to about 120°C forming a homogeneous copolymer wherein the copolymer composition is similar to the three monomer molar feed ratio and wherein the copolymer is melt processable without the use of solvents.
2. The process as claimed in claim 1 wherein the polymerization of
Step (v) is conducted as an emulsion, a solution, a suspension, or in
bulk.
3. The process as claimed in claim 1 wherein the molecular weight
modifier is added to the initial three monomer mixture of Step (i), the
three monomer feed mixture of Step (iii), or to both mixtures.
4. The process as claimed in claim 1 wherein the molecular weight
modifier of Step (iv) is a mercaptan selected from the group consisting of
C5 to CIS alkyl mercaptans wherein the alkyl groups are straight-
chained, branched, substituted, unsubstituted, and combinations
thereof.
5. A process for polymerizing (a) acrylonitrile monomer, (b)
methacrylonitrile monomer and (c) an olefinically unsaturated monomer
substantially as herein described with reference to the foregoing
examples.

Documents:

1360-del-1994-abstract.pdf

1360-del-1994-assignment.pdf

1360-del-1994-claims.pdf

1360-del-1994-correspondence-others.pdf

1360-del-1994-correspondence-po.pdf

1360-del-1994-description (complete).pdf

1360-del-1994-form-1.pdf

1360-del-1994-form-13.pdf

1360-del-1994-form-2.pdf

1360-del-1994-form-4.pdf

1360-del-1994-form-6.pdf

1360-del-1994-form-9.pdf

1360-del-1994-gpa.pdf

1360-del-1994-petition-124.pdf

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Patent Number

190351

Indian Patent Application Number

1360/DEL/1994

PG Journal Number

31/2009

Publication Date

31-Jul-2009

Grant Date

12-Mar-2004

Date of Filing

27-Oct-1994

Name of Patentee

INSTITUTE OF TEXTILE TECHNOLOGY

Applicant Address

2551 IVY ROAD, CHARLOTTESVILLE, VIRGINIA 22903-4615, U.S.A.

Inventors:

#	Inventor's Name	Inventor's Address
1	RICHARD CHESTER SMIERCIAK	1112 E. GARFIELD, AURORA, OHIO 44240, U.S.A.
2	EDDIE WARDLOW, JR.	3102 VAN AKEN BLVD. SHAKER HT., OHIO 44120, U.S.A.
3	LAWRENCE ERNIE BALL	4288 WEST BATH ROAD, AKRON, OHIO, U.S.A.
4	RICHARD CHESTER SMIERCIAK	1112 E. GARFIELD, AURORA, OHIO 44240, U.S.A.
5	EDDIE WARDLOW, JR.	3102 VAN AKEN BLVD. SHAKER HT., OHIO 44120, U.S.A.
6	LAWRENCE ERNIE BALL	4288 WEST BATH ROAD, AKRON, OHIO, U.S.A.
7	RICHARD CHESTER SMIERCIAK	1112 E. GARFIELD, AURORA, OHIO 44240, U.S.A.
8	EDDIE WARDLOW, JR.	3102 VAN AKEN BLVD. SHAKER HT., OHIO 44120, U.S.A.
9	LAWRENCE ERNIE BALL	4288 WEST BATH ROAD, AKRON, OHIO, U.S.A.

PCT International Classification Number

C08F 220/46

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	08/150,515	1993-11-10	U.S.A.