MXPA01007794A - Modacrylic copolymer composition - Google Patents

Abstract

The present invention relates to a modacrylic copolymer composition comprising acrylonitrile, vinylidene chloride, vinyl acetate, and at least one ionic comonomer. In one embodiment, the modacrylic copolymer composition comprises from about 45 to about 60%acrylonitrile, from about 35 to about 50%vinylidene chloride, from about 0.5 to about 5%vinyl acetate, and up to about 2%of a salt of p-sulfophenyl methallyl ether by weight of the total composition. The copolymer composition of the present invention provides acceptable color while having acceptable flame resistance.

Description

COMPACTION PE MODOLRIL COPOLYMER The invention relates to a modacrylic copolymer composition and to a method for making an itiodacrylic copolymer composition. This invention also relates to the conversion of a modacrylic copolymer composition to fiber and / or carpet with acceptable flame ignition characteristics.

BACKGROUND OF THE INVENTION A wide variety of polyacrylonitrile fibers have been spun which possess certain desirable physical properties such as high strength, high wet melting point, and good shrinkage resistance at elevated temperatures. These properties of polyacrylonitrile fibers facilitate their use in many commercial and textile applications. However, the use of polyacrylonitrile fibers was limited since these fibers do not possess sufficient flame retardant properties. In an effort to increase the flame retardant properties of acrylonitrile fibers, acrylonitrile has been copolymerized with certain monomers such as vinyl chloride and vinylidene chloride. The degree of improvement in this property varies with the type and amount of modifier copolymerized with acrylonitrile. However, it was difficult to provide acrylonitrile fibers with such a modifier that provides adequate flame retardant properties while also providing acceptable fiber properties such as acceptable color, high shrink strength, high strength, high wet melting point, and dyeability. acceptable. These difficulties are, in part, due to the difficulty of solubilizing vinyl chloride or vinylidene chloride. Various mixtures of acrylonitrile copolymer including acrylonitrile and vinylidene chloride have been developed. For example, in the patent of E.U.A. No. 2,769,793, which is incorporated herein by reference, discloses a mixture of acrylonitrile copolymer, containing 85 percent or more of acrylonitrile polymer, which can include a variety of monomeric components such as vinyl chloride, vinyl, vinylidene chloride, and the like. The mixture may also contain a dye receptor monomer. The patent of E.U.A. No. 3,828,014, which is incorporated herein by reference, refers to fibers formed from an acrylonitrile copolymer and one or more monoolefinically unsaturated copolymerizable monomers. However, these patents disclose acrylonitrile blends that do not provide adequate fiber properties, fiber processability, ignition resistance, and ability to dye at the same time. The fiber industry strives to provide fibers that do not only possess flame retardant properties, but also to provide improved fiber light resistance, fiber staining capacity and fiber color. The patent of E.U.A. No. 3,824,222, which is incorporated herein by reference, discloses a flame-retardant acrylic fiber containing acrylonitrile, vinylidene chloride and vinyl phosphonate. The patent of E.U.A. No. 3,974,130, which is incorporated by reference herein, refers to a non-flammable acrylonitrile-vinylidene chloride copolymer fiber that includes comonomers having a special affinity for colorants. However, these fiber compositions, designated modacrylics, contain large amounts of vinylidene chloride (ie, in concentrations above 25% by weight). The prior art compositions with vinylidene chloride suffered from poor fiber characteristics and poor color. For purposes of fiber formation, vinylidene chloride, in amounts necessary to impart flame resistance, can impart many undesirable properties to the fibers. Satisfactory copolymers of the prior art are not obtained when the content of vinylidene chloride exceeds 25% by weight of the copolymer composition due to the reduced flame retardancy or the whiteness of the reduced base copolymer. Vinylidene chloride also adversely affects the fiber's light resistance as well as other properties such as UV resistance. The large concentrations of vinylidene chloride in the copolymers of the prior art increase the processing complications due to the low solubility of vinylidene chloride, and results in fibers having unacceptable properties such as, insufficient fiber structure (e.g., tensile properties), light resistance and dyeability.

A satisfactory commercially manufactured modacrylic mixture was a combination of vinyl bromide and vinylidene chloride with other comonomers. Such a mixture contained 61.45 percent acrylonitrile, 1.5 percent sodium p-sulfophenylmetallyl ether, 12.5 percent vinyl bromide, 23.9 percent vinylidene chloride, and 0.65 percent styrene. This copolymer composition has the number Chemical Abstracts CAS # 31532-91-9, which is an acrylonitrile copolymer of vinyl bromide-vinylidene chloride. However, the availability of vinyl bromide has recently deteriorated. Also, there is a need for modacrylic fiber compositions that provide fibers with the combined properties of the desired fiber structure, resistance to light, color and flame retardancy. In addition, there is a need in other industries for flame retardant polyinner materials that can be formed into various products without encountering color complications inherent with the above monomer and copolymer compositions.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a modacrylic copolymer composition comprising acrylonitrile, vinylidene chloride, vinyl acetate and at least one ionic comonomer. The modacrylic copolymer composition comprises from about 45 to about 60% acrylonitrile, from about 35 to about 50% vinylidene chloride, from about 0.5 to about 5% vinyl acetate, and from about 0 to about 2% of a p-sulfophenylmethallyl ether salt, by weight of the total composition. The copolymer composition of the present invention provides acceptable fiber strength and color properties while having acceptable flame resistance and calcination resistance. This color of pressed polymer as defined in the examples of the mixture is from about -7 to about -11, approximately equal to the commercial mixture of vinyl bromide of the prior art previously described CAS # 31532-91-9. The copolymer composition of the present invention can be used in various forms including articles formed and articles formed in molecularly oriented fibers, strands, bristles, mono-filaments, and the like, and articles formed in various forms such as films, mixed material, laminar units , powders, particles, pellets, solutions, dispersions, gels, pastes and the like.

DETAILED DESCRIPTION OF THE INVENTION As used herein, the term "modacrylic" is a copolymer comprising more than about 45%, but less than 85% by weight of the acrylonitrile comonomer incorporated herein. The present invention relates to a modacrylic copolymer composition comprising acrylonitrile, vinylidene chloride, vinyl acetate, and at least one ionic comonomer. The modacrylic copolymer composition comprises from about 45 to about 60% acrylonitrile, from about 35 to about 50% vinylidene chloride, from about 0.5 to about 5% vinyl acetate, and up to about 2% of a salt of an ionic comonomer, preferably sodium p-sulfophenyl methallyl ether, by weight of the total composition. Generally, a small amount of an ionic comonomer, at least about 0.1% by weight, is useful for staining purposes and to help achieve a denser fiber structure. A preferred composition comprises from about 49 to about 59 percent acrylonitrile, from about 39 to about 49 percent vinylidene chloride, from about 0.5 to about 2.5 percent vinyl acetate, and between about 0.1 and 0.1 percent. about 1.5 percent of a p-sulfophenylmethalyl ether salt by weight of the total composition. The preferred salt of the p-sulfofenylmetalyl ether, an ionic comonomer, is the sodium salt.

Another preferred composition may contain from about 50 to about 57 percent acrylonitrile, from about 41 to about 48 percent vinylidene chloride, from about 0.5 to about 1.5 percent vinyl acetate, and about 0.5 percent. to about 1.5 of a p-sulfophenylmethalyl ether salt by weight of the total composition. Yet another preferred composition may contain from about 49 to about 53 percent acrylonitrile, from about 45 to about 49 percent vinylidene chloride, from about 0.8 to about 1.2 percent vinyl acetate, and about 0.8 to about 1.2 of a p-sulfophenylmethalyl ether salt by weight of the total composition. An example of a preferred composition may be acrylonitrile at 52.9 percent, p-sulfophenylmethalyl ether at 1.0 percent sodium, vinylidene chloride at 45.1 percent, and vinyl acetate at 1.0 percent, plus or minus about 0.1 percent , in weight for each component. Another example of a preferred composition may contain acrylonitrile at 50.2 percent, p-sulfophenylmetallyl ether at 1.0 percent sodium, vinylidene chloride at 47.8 percent, and vinyl acetate at 1.0 percent, plus or minus about 0.1 percent , in weight for each component. This description relates to the discovof a novel modacrylic copolymer composition containing vinyl acetate.

Many of the embodiments within the claims have a pressed polymer color number of -10%. This value is a result of a standard test as defined in the examples that reflect the amount of undesirable red in a copolymer. The result of the -10% test is as good as the color of the pressed polymer of the prior art mixture called CAS # 31532-91-9, as previously described. It is expected that the color values of the pressed polymer will be achieved of about -7% and about -15%, more preferably between about -7% to -12%, with copolymer compositions of the present invention. The test result of the pressed polymer color of -10% achieved with a composition of the present invention is better than the pressed polymer color of the commercially available copolymer of the prior art containing 59.5 percent acrylonitrile, 1 percent ether sodium p-sulfophenyl methallyl, 39 percent vinylidene chloride, and 0.5 percent styrene (hereafter called CAS # 9010-76-8, an acrylonitrile copolymer of vinylidene chloride). The chemical structure of the copolymer can be represented as follows: wherein the acrylonitrile, CAS number 107-13-1, vinyl acetate, CAS number 108-05-4, p-sulphophenylmetallyl ether of sodium, CAS number 1208-67-9 and vinylidene chloride, CAS numbers 75-34-4 are present in fractions by weight given by "v", "x", "y" and "z" respectively. The neutral modified vinyl comonomers of the present invention, particularly vinyl acetate, allow improvement in the white composition of base copolymer over the prior art compositions with more than 25% vinylidene chloride while maintaining flame resistance and other desirable properties. The use of 1% vinyl acetate in the modacrylic also reduces the levels of the activator and initiator required in the redox polymerization by 30%. Reduced activator and initiator levels help produce reduced chromophoric defects in polyacrylonitrile. See L. Patrón and U. Bastianelli. Appl. Polvm. Svmp., No. 25, 105 (1974) and J. Kim, C. Park, Y. Park. B Min, T Son, and J. Ryu, J. of the Korean Fiber Soc, 34, 49 (1997). However, the important differences in chromophoric functionality that were due to the cetono-imine were not seen according to the infrared absorbances specified in the literature. further, fabrics that are made from fiber of copolymer compositions of this invention pass the flame resistance test procedures as set forth in the National Fire Protection Association, also called NFPA 701 Small Scale Test for Flame-Resistant Textiles and Films, Edition of 1989. Fabrics that are made with fiber from the copolymer compositions of this invention also pass the flame resistance test procedures as set forth in Underwriters Laboratories Inc. Standard 214 Small-Flame Test for Flame-Propagation of Fabrics and Films, 1997 edition. As used herein, the term "flame resistant fabrics" means fabrics that pass a preponderance, ie, that more than 80% flame resistance tests are carried out, NFPA 701 (1989) and / or Underwriters Laboratories Inc. Standard 214 (1997). Fabrics that are made from the modacrylic copolymer fibers of this invention pass the small scale flame resistance tests NFPA 701 (1989) and UL 214 (1997). The whiteness of the modacrylic copolymer of this invention as measured by the pressed polymer color test is superior to the compositions without vinyl acetate. Finally, as much as 30% less of the activator and initiator is required for the redox polymerization when 1% vinyl acetate is incorporated in the modacrylic copolymer compared to the redox polymerization when vinyl acetate is not incorporated in the copolymer modacrilico. Other ionic comonomers, together with sodium p-sulphophenylmetalyl ether, can make acceptable fibers. As used herein, an "ionic comonomer" is an ionic comonomer that adds one or more ionic functional groups to the copolymer composition. The ionic functional groups can act as staining sites. Typical ionic functional groups include sulfonate, carboxylate, and sulfate moieties. The ionic comonomer provides the resulting composition with desirable basic stainability and copolymer structures that improve the subsequent processing of the copolymer, such as fiber spinning. Ionic comonomers containing sulfonate, also called "ionic sulfonate comonomers, are preferred. The ionic sulfonate comonomers according to the present invention can be represented by a vinyl monomer with a sulfonate salt or a sulfonic acid of the formula (II) ): (II) wherein A is an aromatic or aliphatic substituent that preferably has about 1-9 carbon atoms, typically a methyl group; B is hydrogen or an aliphatic substituent that preferably has from about 1-9 carbon atoms in the vinyl monomer; and M + represents a suitable counterion for the sulfonate group, for example an alkali metal cation, an alkaline earth metal cation, ammonium, or hydronium cation. The aliphatic and aromatic groups may be unsubstituted or substituted with various constituents such as halogen atoms, organic groups and the like. Preferably, the aliphatic group is a methyl group. Preferably, the aromatic group is a phenyl group or a phenyl ether group. Suitable ionic sulfonate comonomers include salts or sulphonic acids of allyl sulfonate, methallylsulfonate, styrenesulfonate, p-sulfophenyl methallyl ether, 2-methyl-2-acrylamidopropane sulfonate, tertiary acrylamido butylsulfonic acid, or mixtures thereof. The counter ion is usually sodium, although other alkali metals, hydronium and ammonium ions are suitable. As used herein, the term "salts" of ionic comonomers includes the acid form. Mixtures of two or more of the ionic comonomers are also suitable. The copolymer of the present invention can be prepared by any polymerization process, for example emulsion polymerization in an aqueous medium or an aqueous dispersion polymerization process. An anionic surface active agent can be used in combination with a small amount of a conventional nonionic surface active agent. Examples of anionic surface active agents are, for example, fatty acid salts, sulfates, sulfonates and phosphates. In the case of a solution polymerization process, solvents having a relatively small chain transfer constant, for example, ethylene carbonate, dimethylsulfoxide N, N-dimethylacetamide or N, N-dimethylformamide, which are particularly preferred, are preferably employed. . These solvents used as a polymerization medium may contain a small amount of water or other organic solvents, unless the uniform solubility of the copolymer and the polymerization capacity are avoided. The usual radical polymerization initiators are used as catalysts for polymerization. Examples of the polymerization initiators are, for example, persulfates such as ammonium persulfate, sodium persulfate, or potassium persulfate, combinations of a persulfate with a bisulfite such as sodium or ammonium bisulfite, azo compounds such as 2,2, azobis (2,4-dimethylvaleronitrile) and 2,2, -azob-isobutyronitrile, peroxides such as di (2-ethylhexyl) peroxydicarbonate, t-butyl peroxypivalate and lauroyl peroxide, and combinations of peroxides such as hydrogen peroxide with reducing agents organic substances such as L-ascorbic acid. These are suitably selected in accordance with the polymerization process. In one embodiment of the present invention, an acrylic fiber copolymer precursor is produced by a continuous free radical redox aqueous dispersion polymerization process, in which the water is the continuous phase and the initiator is water soluble. The redox system consists of persulfate (oxidation agent and initiator, sometimes called "catalyst"), sulfur dioxide or a bisulfite (reducing agent, sometimes called "activator") and iron (the actual redox catalyst). The salts of the initiator and activator can be used. Typical salts include ammonium, sodium or potassium. In a useful manner, similar results are obtained with up to 30 percent less initiator and activator when 1 percent of the vinyl acetate is incorporated, compared to the amounts required for essentially identical compositions but without vinyl acetate. For example, a minimum amount of 0.3 to 0.4 weight percent, based on the monomer, of the sodium persulphate initiator and a minimum amount of 0.6 to about 0.8 weight percent, based on the monomer, of bisulfite activator of ammonium, to achieve about 75% of the conversion of the monomer into copolymer. This corresponds to about 0.12 to about 0.17 moles of the initiator and about 0.6 to about 0.8 moles of the activator per kilogram of monomer for the given reaction conditions, i.e. iron concentration, water content, temperature, and time of residence as shown in Examples 10 and 11. A persulfate initiator, a peroxide initiator, or an azo initiator can be used to generate free radicals for the vinyl polymerization in place of the aforementioned redox system.

The usual wet and dry spinning processes are adapted for the preparation of a fiber from the copolymer of the present invention, and a wet-spinning process is particularly preferred. The usual solvents for the acrylonitrile polymers can be used as solvents for preparing a spinning solution, for example, acetonitrile, acetone, N, N-dimethylacetamide, N, N-dimethylformamide and dimethylsulfoxide. Since the copolymer dissolves uniformly, N, N-dimethylformamide, N, N-dimethylacetamide and dimethylsulfoxide, particularly N, N-dimethylacetamide are preferred. The spinning solution or the reaction mixture obtained by a solution polymerization and used as a spinning solution may, depending on the occasion, contain additives, for example, a stabilizer such as pigments, an organo-zinc compound or a reducing agent. organic, an agent for improving the tactile sensation such as a titanium compound or an aluminum compound, a flame retardant such as an antimony compound, a tin compound, or a bromide compound. The concentration of the copolymer in the spinning solution can be selected from 15 to 40% by weight. Wet spinning is generally carried out by extruding the spinning solution in 10 to 80% by weight of the aqueous solution of a solvent to form a filament, stretching the filament, washing it with water and drying it. If necessary, the filament obtained can also be stretched and treated with heat. In one embodiment of the present invention, the modacrylic fiber copolymer precursors thus obtained can be used to form modacrylic fibers by various methods, including dry and wet spinning tai such as those described in US Patents. Nos. 3,088,188; 3,193,603; 3,253,880; 3,402,235; 3,426,104; 3,507,823; 3,867,499; 3,932,577; 4,067,948; 4,294,884; 4,447,384; 4,873,142 and 5,496,510 each of which is incorporated herein by reference. The physical properties of the modacrylic copolymer composition of the present invention allow the composition to be used in a variety of applications. For example, the copolymer soluble in a variety of solvents including polar aprotic solvents such as N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide and the like; and in aqueous solutions such as zinc chloride (65%), sodium thiocyanate (55%), and the like. The modacrylic copolymer composition of the present invention possesses other desirable physical properties including ability to mix with other fibers, including acrylics and modacrylics. In one embodiment of the present invention, the copolymer composition is formed into fibers by a wet spinning process in a spin bath. Spinning processes are known in the art; see, for example, the patent of E.U.A. Nos. 4,067,948 and 3,867,499, the descriptions of which are incorporated herein by reference. The solvent in the spin bath is usually the same solvent in which the copolymer was dissolved before spinning. Water can also be included in the spinning bath and generally that portion of the spinning bath will comprise the rest. Organic spinning solvents suitable for the present invention include N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, and ethylene carbonate. Suitable inorganic solvents include aqueous sodium thiocyanate. Preferably, the solvent used in the spinning process of the present invention is N, N-dimethylacetamide. The spun filaments may be subjected to jet stretching. The jet stretch, which is the velocity of the first group of draw cylinders contacted by the filaments leaving the die divided by the speed of the copolymer solution through the spinneret, is controlled between 0.2 and 1.0, preferably 0.4 to 0.6. . To a lower jet stretch, there are the processing difficulties and a superior jet stretch, the sizes of the holes tend to increase. Subsequently, the filaments may be subjected to wet stretching. Wet stretching from about 2X to about 8X is provided by feeding the filaments in a second group of high speed cylinders and stretching the filaments wet. The temperature used in the wet drawing process may vary from about the glass transition temperature to less than the wet melt temperature of the copolymer. It is desired that the wet melt temperature of the copolymer be greater than about 120 ° C, preferably greater than about 130 ° C, to facilitate subsequent treatments, i.e., steam annealing. The wet melt temperature is measured by differential scanning calorimetry, where the polymer and water are placed in a pressure vessel and the endothermic is measured on a temperature scale. The change in specific heat indicates the wet melting temperature. This is a standard test and known in the art, and is fully described in Bruce G. Frushour, "Melting Behavior of Polyacrylonitrile Copolymers" in Polvmer Bulletin, 11, 375-382 (1984). The fibers produced by the above-described process can be treated by "in line relaxation" or batch annealing before final use. Line relaxation is achieved by feeding the filaments in a bath of hot water, steam or hot solvent and water bath, generally at a temperature of 80 ° C to boil and separate the filaments at a lower speed to compensate for the shrinkage that occurs. It takes place in the bathroom. The relaxed filaments are dried by conventional hot cylinders or hot air and adjusted to be used before they become short fibers without the need for a batch annealing process. The fibers formed from the copolymer of the present invention possess desirable combined physical properties over other copolymer fibers including improved fiber structure, flame retardant, whiteness, dyeability, light fastness, wet melting point and Similar. The copolymer composition of the present invention can be used in various forms including articles formed and formed in molecularly oriented fibers, i.e., strands, bristles, monofilaments, and the like. The copolymer can also be formed in other forms such as films, mixed compounds, laminar units, powders, particles, pellets, solutions, dispersions, gels, pastes and the like, either in pure form or mixed with other additives. The copolymer and fiber compositions of the present invention are further defined by reference to the following illustrative examples.

EXAMPLES 1 TO 5 The modacrylic polymers of the present invention, Examples 3 and 4, were prepared. For comparison purposes, a commercially available modacrylic containing acrylonitrile (AN), vinylidene chloride (VCb) and styrene was also used. These are comparative examples 1 and 5. Also for comparison purposes, a modacrylic was prepared without vinyl acetate (VA) or styrene, example 2. The compositions of the modacrylic polymers are shown in table 1.

TABLE 1 Composition of copolymers in examples 1 to 5 The polymers were formed into fiber products, then into strong green fabrics, and these fabrics were subsequently tested following the small-scale fire resistance tests NFPA 701 (1989) and UL 214 (1997) industrial standards. The process of forming the modacrylic copolymer into fiber, and forming fiber into fabric, is well known in the art. The fire resistance data obtained were: Example 1 had an average burn of 12.0 cm, and did not pass the test; Example 2 had an average burn of 11.4 cm, and did not pass the test; Example 3 had an average burn of 9.1 cm, and passed the test: Example 4 had an average burn of 9.2 cm, and passed the test; and example 5 had an average burn of 9.9 cm and passed the test. The comparative example without a neutral modification comonomer, example 2, did not pass the test. Examples containing styrene, examples 1 and 5, had mixed results. Fabrics made from the composition of the present invention, examples 3 and 4, passed the flame resistance test.

EXAMPLES 6 TO 9 The modacrylic polymers of the present invention, examples 6 and 7, were prepared. For comparison purposes, commercially available modacrylic containing vinylidene chloride and styrene, example 8, and a modacrylic with vinylidene chloride and vinyl bromide, example 9, were used. The compositions of the copolymers are shown in table 2. The last column provides color proof data of the pressed polymer (PPC). The results of the color test of the pressed polymer for Examples 6 and 7, -9.82% and -10.32% respectively, are better than the -10.43% achieved with the composition of acrylonitrile vinyl bromide and vinylidene chloride copolymer ( CAS # 31532-91-9) in comparative example 9. The result of the test for comparative example 8 was -19.23%. This is a significantly lower color compared to the color of the other samples tested.

TABLE 2 Composition of copolymers in examples 6-9 The pressed polymer color is a standard test, known in the art, comprising the following steps. A known weight of copolymer was placed in a die and subsequently compressed into a disk at 40,000 psi for 30 seconds. The disc color was subsequently measured. The color of the pressed polymer is the measurement as a pellet pressed from the polymer of% reflectance at 420 nm minus the% reflectance at 600 nm in BYK-Gardner Colorsphere. The more negative the color number of the pressed polymer, the greater the undesirable yellow-red color of the polymer.

EXAMPLE 10 An example of a continuous aqueous dispersion process with an ammonium counterion redox was prepared in the following manner. A reservoir reactor of 7.0 liters was maintained with continuous agitation (with two 6-blade impellers at 45 degrees rotating at 600 rpm) at a temperature of about 35 ° C. A number of feed streams were introduced into the reactor at rates such that the average residence time of the reactor was 150 minutes. The pH remained close to 3.5. The composition of the total feed is shown in Table 3. Polymerization was initiated by feeding aqueous solutions of ammonium persulfate (oxidizing agent and initiator, sometimes called "catalyst"), ammonium bisulfite (reducing agent, sometimes called "activator") and ferrous or ferric iron (the actual redox catalyst), and sulfuric acid (for pH control). These conditions resulted in 74.9% by weight of the conversion of monomer to copolymer. The final copolymer composition was 47.91% vinylidene chloride, 1.03% sodium p-sulphophenylmetalyl ether, 0.98% vinyl acetate and the rest acrylonitrile. It is recognized that the p-sulfophenylmetalyl ether salt may be another cation, ie, ammonium, but it is reported as a sodium salt for clarity. The color of pressed polymer for the copolymer was -9.57%.

TABLE 3 Feeding composition to the deposit reactor with aaitation keep going. example 10 Compound Quantity Units Acrylonitrile monomer 49.6 Parts by weight Vinylidene chloride monomer 48.6 Parts by weight Vinyl acetate monomer 0.9 Parts by weight P-sulfophenylmethalyl ether monomer 0.9 Parts by weight of sodium Water 200.0 Parts by weight Ammonium persulphate (initiator) 0.33% based on the ammonium bisulfate moperoomer as sulfur Dioxide (activator) 0.66% based on the monomer Iron (ferrous or ferric) 1.6 ppp based on the monomer Sulfuric acid Trace EXAMPLE 11 An example of a continuous aqueous dispersion process with sodium counterion redox follows. A 7.0 liter reservoir reactor was maintained with continuous agitation (with two 6-blade impellers at 45 degrees rotating at 500 rpm) at a temperature of about 35 ° C. A number of feed streams were introduced into the reactor at rates such that the average residence time was 150 minutes. The pH remained close to 3.4. The feed composition is shown in Table 4. Polymerization was initiated by feeding aqueous solutions of sodium persulfate (oxidizing agent and initiator, sometimes called "catalyst"), sodium bisulfite (the reducing agent, sometimes called " activator ") and ferrous or ferric iron (real redox catalyst), and sulfuric acid (for pH control). These conditions resulted in 76.9% by weight of the conversion of monomer to copolymer. The final copolymer composition was 46.88% vinylidene chloride, 1.06% sodium p-sulfophenylmetallyl ether, 1.14% vinyl acetate, and the acrylonitrile moiety. The pressed polymer color of the copolymer was -9.21%.

TABLE 4 C Co-expansion of the deposit to the deposit reactor with aqation keep going. example 11 Compound Quantity Units Acrylonitrile monomer 51.6 Parts Vinylidene chloride monomer 46.5 Parts Vinyl acetate monomer 1.0 Parts P-Sulfophenylmethallyl ether monomer 0.9 Sodium parts Water 200.0 Parts Sodium persulphate (initiator) 0.36% based on monomer Sodium bisulfate as sulfur Dioxide (activator) 0.72% based on the monomer Iron (ferrous or ferric) 1.6 ppi based on the monomer Sulfuric acid Trace Sodium bicarbonate Trace The above description of the specific embodiments of the present invention is not intended to be a complete list of each possible embodiment of the invention. Those skilled in the art will recognize that modifications can be made to the specific embodiments described herein that will be within the scope of the present invention.

Claims (24)

NOVELTY OF THE INVENTION CLAIMS

1. - A modacrylic copotimer comprising: (a) between about 49 and about 59% by weight of acrylonitrile; (b) between about 39 and about 49% by weight of vinylidene chloride; (c) between about 0.5 and about 5% by weight of vinyl acetate; and (d) between about 0.1 and about 2% by weight of an ionic comonomer.

2 - The copolymer according to claim 1, further characterized in that the copolymer comprises between about 50 and about 57% by weight of acrylonitrile, between about 41 and about 48% by weight of vinylidene chloride, between about 0.5 and about 1.5% by weight of vinyl acetate, and between about 0.5 and about 1.5% by weight of an ionic comonomer.

3. The copolymer according to claim 1, further characterized in that the copolymer comprises between about 49 and about 53% by weight of acrylonitrile, between about 45 and about 49% by weight of vinylidene chloride, between about 0.8 and about 1.2% by weight of vinyl acetate, and between about 0.8 and about 1.2% by weight of an ionic comonomer.

4. - The copolymer according to claim 1, further characterized in that the copolymer comprises between about 52.8 and about 53% by weight of acrylonitrile, between about 45 and about 45.2% by weight of vinylidene chloride, between about 0.9 and about 1.1% by weight of vinyl acetate, and between about 0.9 and about 1.1% by weight of an ionic comonomer.

5. The copolymer according to claim 1, further characterized in that the copolymer comprises between about 50.1 and about 50.3% by weight of acrylonitrile, between about 47.7 and about 47.9% by weight of vinylidene chloride, between about 0.9 and about 1.1% vinyl acetate, and between about 0.9 and about 1.1% by weight of an ionic comonomer.

6. The copolymer according to claim 1, further characterized in that the ionic comonomer comprises p-sulphophenylmethallyl ether or allylsulfonate salts, methallylsulfonate, styrenesulfonate, p-sulphophenylmethalyl ether, 2-methyl-2-acrylaminopropane sulfonate, acid tertiary acrylamido butylsulfonic, or mixtures thereof.

7. The copolymer according to claim 1, further characterized in that the copolymer is in the form of films, mixed compounds, laminar units, powders, particles, pellets, solutions, dispersions, gels, or pastes.

8. - The copolymer according to claim 1, further characterized in that the copolymer has a wet melt temperature greater than about 130 ° C.

9. A modacrylic copolymer comprising: (a) between about 45 and about 60 weight percent acrylonitrile; (b) between about 35 and about 50 weight percent vinylidene chloride; (c) between about 0.5 and about 5 weight percent vinyl acetate; and (d) between about 0 and about 2 weight percent of a p-sulfonophenylmetallyl ether salt.

10. The copolymer according to claim 9, further characterized in that the copolymer comprises between about 49 and about 59 weight percent acrylonitrile, between about 39 and about 49 weight percent vinylidene chloride, between about 0.5 and about 2.5 weight percent vinyl acetate, and between about 0.1 and about 2 weight percent of a p-sulfonophenylmetalyl ether salt.

11. The copolymer according to claim 9, further characterized in that the copolymer comprises between about 50 and about 57 weight percent acrylonitrile, between about 41 and about 48 weight percent vinylidene chloride, between about 0.5 and about 1.5 weight percent vinyl acetate, and between about 0.5 and about 1.5 weight percent of a p-sulfonophenylmetalyl ether salt.

12. - The copolymer according to claim 9, further characterized in that the copolymer comprises between about 49 and about 53 weight percent acrylonitrile, between about 45 and about 49 weight percent vinylidene chloride, between about 0.8 and about 1.2 weight percent vinyl acetate, and between about 0.8 and about 1.2 weight percent of a p-sulfonophenylmetalyl ether salt.

13. The copolymer according to claim 9, further characterized in that the copolymer comprises between about 52.8 and about 53 weight percent acrylonitrile, between about 45 and about 45.2 weight percent vinylidene chloride, between about of 0.9 and about 1.1 weight percent vinyl acetate, and between about 0.9 and about 1.1 weight percent of a p-sulfonophenylmetallyl ether salt.

14. The copolymer according to claim 9, further characterized in that the copolymer comprises between about 50.1 and about 50.3 weight percent acrylonitrile, between about 47.7 and about 47.9 weight percent vinylidene chloride, between about of 0.9 and about 1.1 weight percent vinyl acetate, and between about 0.9 and about 1.1 weight percent of a p-sulfonophenylmetallyl ether salt.

15. - The copolymer according to claim 9, further characterized in that the copolymer has a pressed polymer color number of about -7 to about -15%.

16. The copolymer according to claim 9, further characterized in that the copolymer has a pressed polymer color number of about -7% to about -12%.

17. The copolymer according to claim 9, further characterized in that the copolymer has a wet melt temperature greater than about 120 ° C.

18. A fiber comprising a modacrylic copolymer, wherein the modacrylic copolymer comprises: (a) between about 49 and about 59 weight percent acrylonitrile; (b) between about 39 and about 49 weight percent vinylidene chloride; (c) between about 0.5 and about 5 weight percent vinyl acetate; and (d) between about 0.1 and about 2 weight percent of an ionic comonomer.

19. The fiber according to claim 18, further characterized in that the modacrylic copolymer comprises between about 49 and about 53 weight percent acrylonitrile, between about 45 and about 49 weight percent vinylidene chloride, between about 0.8 and about 1.2 weight percent vinyl acetate, and between about 0.8 and about 1.2 weight percent of a p-sulfonophenylmetalyl ether salt.

20. - The fiber according to claim 18, further characterized in that the fiber is in fabric form.

21. The fabric according to claim 20, further characterized in that the fabric is a mixture of fiber types.

22. The fabric according to claim 20, further characterized in that the fabric is a flame resistant fabric.

23. A method for manufacturing a modacrylic copolymer, said method comprises reacting, in a polymerization process of free radical redox aqueous dispersion, monomers comprising an acrylonitrile, vinyl acetate, ionic comonomer and vinifidene chloride with at least one an initiator, activator, and a redox catalyst to form a copolymer, wherein the copolymer composition is between about 45 and about 60 weight percent acrylonitrile, between about 0.5 and about 5 weight percent acetate of vinyl, between about 0.01 and about 2 weight percent of an ionic comonomer, and between about 35 and about 50 weight percent of vinylidene chloride.

24. The method according to claim 23, further characterized in that the initiator comprises a persulfate salt, the activator comprises one or more sulfur dioxides or a bisulfite salt, and the catalyst comprises iron or a salt thereof.