MXPA00009717A - Polyacrylonitrile particles by surfmer polymerization and sodium removal by chemical exchange - Google Patents

Abstract

The present invention is an acrylic polymer particle which is consistently and substantially spherical in shape and which has a mean diameter that can be predetermined from about 30 microns in diameter to about 5 microns or less. Polyacrylonitrile is synthesized in an aqueous dispersion polymerization with an ionic monomer or"surfmer"to attain a narrow particle size distribution with a mean diameter as low as approximately 3±1.5 microns which is characteristic of an emulsion polymerization. The polymer comprises the ionic monomer and, optionally, a neutral comonomer. The mean particle size is dependent on the concentration of the ionic monomer present, the particular ionic monomer or monomers selected, and the counterion associated with the ionic monomers, the persulfate initiator, and the bisulfite activator. The counterions, often sodium ions, can be removed from the polymer particles by ion exchange with quarternary ammonium compounds.

Description

POLYACRYLONITRIL PARTICLES THROUGH POLYMERIZATION WITH SURFAMER AND ELIMINATION OF SODIUM THROUGH EXCHANGE CHEMICAL BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The present invention relates generally to polyacrylonitrile particle synthesis fields in an aqueous dispersion polymerization with an ionic comonomer or "surfammer" to obtain essentially spherical polyacrylonitrile polymer particles with a narrow and predetermined particle size distribution . The average particle size is directly proportional to the concentration of the ionic comonomer, the particular ionic comonomer selected, and the counterions associated with the ionic comonomers, the persulfate initiator and the bisulfite activator. This procedure facilitates the control of the particle size of the polymer when the polymer must contain a high number of dye sites. A high number of dye sites makes it easier to bind functional molecules to the polymer, and this allows the aqueous dispersion polymerization process to progress to much lower polymer to water ratios than normal aqueous polymerization processes. If a very high concentration of particular ionic comonomers is incorporated, the polymer particles may be too small to be filtered efficiently and must be separated by more costly centrifugal methods. At the same time, there are applications for polyacrylonitrile particles that have a small uniform diameter. Polyacrylonitrile particles below 5 microns have utility in battery applications. The polymer particle is useful after converting it into carbon powder for lithium-ion-carbon battery formulations. The important characteristics of the polymer particles to be used in advanced battery applications are a small average particle size of less than 5 microns, a narrow particle size distribution, an essentially spherical shape and a low sodium content. 2. DESCRIPTION OF THE RELATED TECHNIQUE The acrylonitrile and its comonomers can be polymerized by a number of methods using well-known free radicals. All commercial procedures are based on the free radical polymerization because it gives the combination of polymerization speed, ease of control, and properties that include whiteness, molecular weight, linearity and the ability to incorporate desired comonomers and, in most cases, of the cases, sites for coloring. By far, the polymerization method most widely used in the acrylic fiber industry is polymerization in aqueous dispersion or suspension polymerization. Polymerization in aqueous dispersion, a variant of suspension polymerization, is the most common commercial method. Water is the continuous phase. The water acts as a convenient means of heat transfer and cooling and the polymer recovers very easily by filtration or centrifugation. The initiators and dispersants used in the dispersion polymerization are soluble in water, while those used in the suspension polymerization are insoluble in water. The polyacrylonitrile particles made by this process grow mainly by agglomeration of smaller particles. Emulsion polymerization, on the other hand, is used mainly when a high level of a water-insoluble monomer is employed and therefore the propagation macroradicals are isolated from each other. As a consequence, encounters between macro-radicals are prevented and termination reactions are less frequent. In this process the agglomeration of smaller particles is not a factor in the growth of the polymer particle. Therefore, the particle size distribution is more a function of the initial micelle size. However, it is difficult to incorporate water-soluble comonomers in the polymer in an emulsion polymerization. In addition, the composition of the polymer will frequently change as the monomers are selectively incorporated in the polymer and consequently decrease in the monomeric layer that adheres.

The acrylonitrile polymers are made from acrylonitrile polymers that generally contain other comonomers. Almost all acrylic fibers are made from acrylonitrile copolymers containing one or more additional monomers which modify the properties of the fiber. Neutral comonomers including methyl acrylate, methyl methacrylate or vinyl acetate are used to modify the solubility of the acrylic copolymers in stirring solvents such as dimethylacetamide, to modify the morphology of the acrylic fiber and to improve the diffusion rate of the acrylic fiber. the dyes in the acrylic fiber. Despite its disadvantages of low reactivity and difficulty in controlling polymer and chain transfer in polymerization, vinyl acetate is increasingly the comonomer of choice for acrylic fibers, mainly due to its low cost. The dyes can be attached to the polymer in the end groups and where the ionic functional groups are available. The dyeability of the fiber depends largely on the molecular weight distribution of the polymer because most acrylic fibers obtain their dyeability from the sulfonate initiator and sulfate fragments at the ends of the chain of the polymer. Therefore, the content of dye sites of the fiber is inversely related to the number average molecular weight of the polymer and is very sensitive to the low molecular weight polymer fraction. With the trend of finer denier fibers in which more dye is required to obtain a given color, the need for colorant sites is increased. Over the years, many producers have gradually reduced the molecular weight of their polymer to increase the dyeability. The total number of dye sites required to be able to dye a wide range of shades with cationic dyes is 30 to 50 milliequivalents per kilogram (meq / kg) depending on the denier and structure of the fiber. Dry-spun fibers and micro-fiber fibers require a minimum of 40 meq / kg of dye sites. Where the number provided by the end groups is inadequate, a monomer containing sulfonate can be used to provide additional dye sites within the polymer structure. The carboxylic monomers have also been used as dye receptors. Ionic comonomers such as sodium p-styrenesulfonate, sodium methallylsulfonate, sodium p-sulfonylmetalyl ether, sodium 2-methyl-2-acryloamidopropansulfonate, or taconic acid can be added to provide dye sites in addition to the groups of extreme and to increase the hydrophilic character. These dye site comonomers contain sulfonate or carboxylate functional groups and a hydrocarbon functional group. Therefore, they have some capacity to act as surfactants. The name surfámero, which is another term for surfactant monomer or ionic monomer, has been coined for surfactant molecules that also act as a comonomer that can participate in a propagation reaction.

These materials react to produce polymer chains that bend on themselves to form spheres. The spheres are generally several tens of microns in diameter, mainly due to the agglomeration of smaller particles. The agglomeration can be partially controlled using surfactants or ionic monomers. Surfactants and monomers usually include counterions, often a cation such as sodium. Polyacrylonitrile particles of various sizes have utility in a variety of applications. It is known in the art to form carbon materials, typically fibers, by carbonizing acrylic or acrylonitrile polymers in fiber form. It has recently been discovered that acrylic polymers in the form of small particles (1.5 to 4.5 microns) can be carbonized to form a useful material in battery applications. In the carbonization process, the uniformity of the particle shape is essential to obtain a good result; however, the acrylics in the form of microparticles of the prior art are made by simply grinding larger particles and therefore have no uniformity of shape. In addition, sodium ions are harmful to this carbonization process. The surfactants absorbed in the polymer particles cause the sodium ions to also bind to the polymer particles.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a method for making an acrylic polymer particle which has a consistent and substantially spherical shape and which has a predetermined average particle diameter. Substantially spherical is defined as the diameter measured in any direction that is within 20% of any other diameter measurement on the same particle, with the particle at rest. The polymeric particles comprising acrylonitrile, an ionic comonomer or "surfammer", or a neutral comonomer have been synthesized in aqueous dispersion polymerization to obtain a narrow particle size distribution with an average diameter that can vary from about 35 microns, characteristic of an aqueous dispersion polymerization up to about 3 microns, characteristic of an emulsion polymerization. A "neutral comonomer" is a non-ionic comonomer that does not add ionic functional groups that can act as dye sites. Those neutral comonomers listed in the background section of this application are incorporated herein for reference. Vinyl acetate is the preferred organic comonomer used in the polymerization with acrylonitrile. Vinyl acetate is a modifying comonomer that improves the solubility of the acrylic polymer in the agitation solvent, dimethylacetamide, and imparts other desirable properties to the polymer.

This invention requires that an ion monomer be incorporated into the polymer at a concentration above that normally used in the industry to achieve dyeability. One purpose of the invention is to reduce the average particle size for a particular end-use application that requires such particles. The various ionic comonomers have varying degrees of effectiveness in reducing the average polymer particle. The ionic comonomer sodium methallylsulfonate is particularly effective in reducing the average particle size of the polyacrylonitrile polymers. The same average particle size can be obtained with higher concentrations of other ionic comonomers. For example, itaconic acid is less effective than many ionic comonomers with sulfonate base to reduce particle size but could be preferred in many cases. The small particle size is harmful to produce polymers in treatment if the required number of colorant sites is such that with sodium methanylsulphonate the particle size is too small to be easily collected by filtration, and considering that the application end does not require small size. In this case, other ionic monomers can be used. For example, it can also be used in sodium p-sulfophenyl metal ether to provide a sulfonate functional group without achieving the same degree of particle size reduction as that observed with similar concentrations of sodium methallylsulfonate. Therefore, a polymerization with a surfammer utilizing p-sulfophenyl metal sodium ether does not give particle diameters as small as those produced containing equivalent concentrations of sodium methallyl sulfonate. Itaconic acid, which contains two carboxylic acid groups, is preferred in some applications mainly because of its cost. It is also much less effective than sodium methallylsulfonate to reduce particle size, but it could be preferred based on the cost and the desired loading of dye sites and the desired particle size is greater than about 5 microns in diameter. Any of the ionic monomers with sulfonate or carboxylate base are effective in reducing the particle size, and the preferred ionic monomer can depend on the reagent costs, the efficiency of the plant to process a particular particle size and the desired number of sites for dye per kilogram of polymer. In a surprising way, the counterions associated with ionic monomer, persulphate initiator and bisulfite activator also influence the particle size of the polymers. Experiments have shown that the incorporation of approximately 4% by weight of itaconic acid (620 meq / carboxylate ion per kg of polymer) having sodium counterions from the sodium persulphate initiator, the sodium bisulfite activator and possibly other sources, will give a particle that is approximately 10 microns in diameter. The same particle size is achieved with the incorporation of only 2.5 wt% of itaconic acid (380 meq / carboxylate ion per kg of polymer) if the polymerization uses itaconic acid in a solution containing ammonium from ammonium persulphate, bisulfite of ammonium and other sources, such as the main contraion. A similar result could be achieved if the ammonium salts were added in sufficient quantity such that the cations normally associated with the polymerization ingredients are essentially replaced in the solution by ammonia. In tests in which the polymer particles were made incorporating 2.5 wt% of itaconic acid (380 meq / carboxylate ion per kg of polymer) with a sodium counter ion, the average particle size was about 17 microns in diameter. The ratio between the weight fraction of the polymer, which is an ionic comonomer, and the particle size is linear. The data in Table 1 were developed for itaconic acid in a polymerization with sodium counter-ions TABLE 1 Mean particle diameter of polymer against concentration of itaconic acid Itaconic acid Ion carboxylate Vinyl acetate Particle size% p meq / kg average weight percent in polymer microns 4.4 680 0.9 9.0 4.0 620 0.0 9.6 3.7 570 2.2 12.2 2.8 430 1.9 13.7 2.3 350 3.1 17 0.9 140 3.7 25 The data show a linear relationship in the range of concentrations tested with the average particle diameter decreasing by approximately 4.6 microns for each additional percent weight of itaconic acid or, alternatively, for each 154 meq / kg of additional carboxylate ions incorporated in the polymer. The neutral comonomer, vinyl acetate, has no apparent effect on the average particle size of the polymers. Less complete data for sodium methallylsulfonate suggest that the average particle diameter decreases by about 9.7 microns for each additional weight percent of sodium methallylsulfonate incorporated in the polymer. The smallest average particle diameter achieved is about 3 microns, although the particle size should continue to decrease, at a lower rate, with the addition of additional ionic monomer in the polymer. Alternatively, the addition of ammonia such as the ammonium ions that replace the sodium ions as the associated cation should also result in smaller sizes. The average particle diameter can be predetermined by adding a predetermined amount of a given ionic monomer. It is a second objective of this invention to allow the incorporation of high levels of dye sites while at the same time controlling the particle size so that the filtration can be used to separate the polymer from the water. An ionic comonomer will provide at least one colorant site. A large number of dye sites is useful because it has recently been discovered that functional molecules - such as those that impart antimicrobial activity, or those that alter the rheological properties of the polymer - can be substituted in the ionic functional group of the ionic comonomer . Generally less than 50 meq / kg of polymer is needed to fix dyes to the polymer. For the purposes of linking functional molecules to the polymer, the amount of dye sites must be greater than the amount needed to fix the dye. This amount may be in the range of about 100 meq of dye sites per kilogram of polymer (meq / kg) to about 1000 meq / kg of polymer. To make small polymer particles (about 5 microns or less), the preferred range is from about 200 meq / kg to about 1000 meq / kg, depending on the selected ionic monomer. In order to have dye sites available for the exchange of functional groups thereon, there must be at least about 50 meq / kg more than what is needed for the dye. This leads to a minimum number of colorant sites of approximately 100 meq / kg. As a practical aspect, not all colorant sites are exchanged with a derivatization unit in the polymer, and some loading of a derivatizing agent may be necessary to impart the desired properties to the polymer. The minimum number of preferred dye sites is about 150 meq / kg and the number of preferred minimum dye sites is about 200 meq / kg. The maximum number of colorant sites is not important, with the proviso that manufacturing equipment can process smaller polymer particles. For most applications, such as the exchange of antimicrobial agents on the dye sites available in the polymer, approximately 1000 meq / kg will suffice. The incorporation of ion monomer in a polymer implies a greater increase in costs, and for many applications less than 1000 meq / kg of dye sites, such as 800 meq / kg, and for many applications less than about 600 meq / kg of dye sites will be needed. If more than one derivative agent is needed, the maximum required number of colorant sites could be greater than 1000 meq / kg. If an ionic monomer especially effective in reducing the particle size of the polymer, such as methallylsulfonate, is used, loading the polymer with more than about 400 meq / kg will result in polymer particles which are difficult to filter from the aqueous solution. In this case, to make polymer particles that are about 3 microns in diameter, the amount of ionic monomer added to the polymer should be in the range of about 240 meq / kg to about 280 meq / kg of polymer. This high charge of ionic comonomers will create very small particles that are difficult to filter unless particular ionic comonomers are selected. Selecting weaker sulfonate and carboxylate based ionic comonomers will supply larger particles. The preferred dye site generally contains a sulfonate functional group (-SO3X, in which X is any appropriate cation and is frequently an alkali metal). The sulfate and carboxylate functional groups are also acceptable dye sites and may be preferred in some applications. Each ionic comonomer with sulfonate base does not have identical effects on the size of the particles. The selection of ionic comonomers will depend on the concentration of the necessary dye sites and the filtration characteristics in the plant. The presence of a high concentration of ionic monomer in the polymer and in the medium also allows the use of very low water-monomer ratios. If the amount of ionic monomer is high, ie about 4% by weight, water to monomer ratios as low as 2.0: 1 can be used. If the ionic monomer used is sodium metalsuifonate, a water to monomer ratio of 1.5: 1 can be used. Typically, it is not possible to go beyond a 2.5: 1 ratio in the standard formulation containing sodium p-sulfonylmetalyl ether. The benefit of the lower water to monomer ratio is that the facility has higher production rates from a given reactor and produces less dense polymer particles which are easier to dry. The reaction generally, but not necessarily, takes place in a continuously stirred tank reactor.

Aqueous dispersion polymerization using high concentrations of surfamer provides a polymeric particle which is essentially spherical in shape, with a small diameter, and which has a narrow particle size distribution. The surfámero obtains these results through several mechanisms. The acrylonitrile polymers that are synthesized in an aqueous dispersion grow by agglomeration of very small polymer particles that are initiated in the aqueous solution. These particles are hydrophobic and therefore agglomerate. The surfammer has the effect of changing the character of the particle to a more hydrophilic nature and therefore reduces agglomeration to essentially zero. So the primary mechanism of growth is the growth by incorporation of monomers in the polymer. The surfactant isolates better the macroradicals of propagation in micelles, with which the encounters between macroradicales are increased. Therefore, there is less monomeric material available for growth from each collision between a growing particle and a micelle containing monomer. The surfammer also prevents free radical initiators from being readily absorbed onto the surface of the polymer particles and initiate secondary growth, shifting instead this reaction to the aqueous phase in which new particles are formed. Finally, the more sulfonate groups are present, the greater the restriction of acrylonitrile diffusion in the particle. The overall effect is to obtain a small average particle diameter and a narrow particle size distribution even if the reaction is carried out in a tank reactor with continuous agitation. The larger amount of surfammer incorporated in the polymer gives the polymer a greater number of colorant sites and a higher amount of sodium that is ionically bound within the polymer. A potential disadvantage of this method is that the cation is normally ionically bound to the ionic functional group, usually sodium, is harmful to some uses. In particular, sodium is harmful if it is desired to convert the polyacrylonitrile particles to carbon particles. The removal of metals is important to improve the performance of coal from such polymers and improve the processing of carbon fiber for battery applications. Although it may be possible in some applications to use ionic monomers having ammonium counterions, in other applications this could result in an unacceptably small particle size. The cation ionically bound to the comonomer containing sulfonate or caboxylate, as well as the cation ionically bound to the sulfonate and sulfate end groups, can be exchanged with a quaternary ammonium salt. The protonated amines such as the tetramethylammonium quaternary salt, the tetrabutylammonium quaternary salt and Larostat 264A (also called in the present invention Larostat) which is the quaternary ammonium salt of a dimethyl fatty acid amine made from soybean oil , they are used successfully to exchange with the counterions in the functional groups sulfate, sulfonate and carboxylate available in the acrylic polymers.

The commercially available antistatic agent, Larostat 264A, is a preferred compound for exchanging sodium from the polymer when the subsequent use of the polymer involves carbonization. The incorporation of Larostat extends the exotherm that occurs in stabilization before carbonization, and may help to avoid particle-particle or fiber-polymer fiber fusion during the stabilization that leads to carbonization. It also appears to reduce the amorphous density and improve the orientation range of the fiber (stretch ratio) during fiber formation and stretching. The preferred method for exchanging sodium from the polymer is by washing the polymer, by chemical exchange with the acrylic polymer in a suspension, at a temperature near or above the wet glass transition point of the polymer. The glass transition is the range of temperatures through which a vitreous polymer flies elastic. Other changes that occur in the glass transition are pronounced increases in the specific volume, heat capacity and diffusion rate of the molecules absorbed. In dyeing operations it is often necessary to be above the glass transition of the wet fiber so that the dye molecules can diffuse into the fiber and reach the dye sites. This elevated temperature facilitates diffusion into and out of the polymer particle. The incorporation of neutral comonomers, preferably vinyl acetate, into the polymer as an additional comonomer also facilitates diffusion into and out of the polymer particle.

DESCRIPTION OF THE EXAMPLE MODALITIES The following examples are included to demonstrate various preferred embodiments of the invention. Those skilled in the art should appreciate that the techniques described in the examples that follow represent techniques discovered by the inventor which work well in the practice of the invention, and therefore can be considered to constitute the preferred modes for practicing it. However, those skilled in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments that are described and still obtain an equal or similar result without departing from the scope and scope of the invention.

EXAMPLE 1 An example of a continuous aqueous dispersion process is described below. A tank reactor with continuous stirring of 3.5 liters (with two impellers of 6 blades at 45 ° rotating at 600 rpm) was maintained at a temperature of 55 ° C. A number of feed streams were introduced into the reactor at speeds such that the average residence time was 60 minutes. The pH remained close to 3. The total composition of the supply material is given in Table 2. The polymerization is started by feeding aqueous solutions of sodium persulphate (oxidant, initiator) sodium bisulfite (reducing agent, activator), iron in ferrous or ferric state (redox catalyst) and sulfuric acid (for pH control). These conditions resulted in 86.5% conversion of monomer to polymer. The final polymer contained 3.1% by weight of sodium methallylsulfonate (200 meq / sulfate ion per kg of polymer), 3.9% by weight of vinyl acetate and the rest of acrylonitrile. The average particle size was 2.8 microns, with a bell-shaped distribution having 10% by weight of the particles below 1.3 microns and 10% by weight of the particles above 5.7 microns.

TABLE 2 Total composition of the feeding material Compound Quantity Units Acrylonitrile monomer 91.2 Parts Vinyl acetate monomer 4.6 Parts Sodium sodium sulphonate 4.2 Parts Water 150.0 Parts Sodium persulphate (initiator) 0.64% based on monomer Sodium bisulfate as 0.83% dioxide based on sulfur (activator ) Iron monomer (ferrous or ferric) 6.0 Parts per million monomer Trace Sulfuric Acid A second test essentially with the same feed currents and conditions resulted in 86.5% conversion of monomer to polymer. The final polymer contained 3.1% by weight of sodium metallilsulfanate, 4.0% by weight of vinyl acetate and the rest of acrylonitrile. The average particle size was 2.8 microns with a bell-shaped distribution having 10% by weight of the particles below 1.3 microns and 10% by weight of the particles above 6.9 microns.

EXAMPLE 2 The following is an example of a continuous aqueous dispersion process with a different ionic monomer. A continuously stirred 3.5-liter tank reactor (with two 6-blade impellers at 45 ° rotating at 400 rpm) was maintained at a temperature of 50 ° C. A number of feed streams were introduced into the reactor at speeds such that the average residence time was 65 minutes. The pH remained close to 3.15. The total composition of the feedstock is given in Table 3. These conditions resulted in 82.7% conversion of the monomer to polymer. The final polymer contained 5.0 wt.% Sodium p-sulfophenylmetallyl ether (200 meq / sulfonate ion per kg of polymer), 4.2 wt.% Vinyl acetate and the rest of acrylonitrile. The average particle size was 28 microns with a bell-shaped distribution having 10% by weight of the particles below 11 microns and 10% by weight of the particles above 56 microns. The particle sizes are in an order of magnitude greater than that observed with sodium methallylsulfonate as the surfammer, although both polymers contained even about 200 meq / sulfonate functional groups.

TABLE 3 Total composition of the feeding material Compound Quantity Units Acrylonitrile monomer 89.5 Parts Vinyl acetate monomer 5.0 Parts sodium p-sulfophenylmetalyl ether 5.5 Parts Water 250.0 Parts Sodium persulp (initiator) 0.65% based on monomer Sodium bisulfate as a 1.46% dioxide based on the sulfur (activator) monomer Iron (ferrous or ferric) 1.6 Parts per million monomer Sulfuric Acid Traces EXAMPLE 3 An example of a continuous aqueous dispersion process with a different surfamere is given below. A continuously stirred 3.5 liter tank reactor (with two 6-blade impellers at 45 ° rotating at 600 rpm) was maintained at a temperature of 50 ° C. A number of feed streams were introduced into the reactor at speeds such tthe average residence time was 75 minutes. The pH remained close to 3.0. The total composition of the feedstock is given in table 4.

TABLE 4 Total composition of the feeding material Compound Quantity Units Acrylonitrile monomer 97.0 Parts Vinyl acetate monomer 0.0 Parts Itaconic acid 3.0 Parts Water 250.0 Parts Sodium persulp (initiator) 0.33% based on monomer Sodium bisulfate as 0.74% dioxide based on the sulfur (activator) monomer Iron (ferrous or ferric) 1.6 Parts per million monomer Sulfuric Acid Traces These conditions resulted in 60% conversion of monomer to polymer. The final polymer contained 4.0 wt% of itaconic acid (620 meq / carboxylate ion per kg of polymer) and the rest of acrylonitrile. The average particle size was 9.6 microns, with a bell-shaped distribution having 10% by weight of the particles below 1.8 microns and 10% by weight of the particles above 25 microns.

EXAMPLE 4 A second example of a continuous aqueous dispersion process with itaconic acid and a small amount of vinyl acetate has little effect on the particle size but increases the conversion. A continuously stirred 3.5 liter tank reactor (with two 6-blade impellers at 45 ° rotating at 600 rpm) was maintained at a temperature of 50 ° C. A number of feed streams were introduced into the reactor at speeds such tthe average residence time was 75 minutes. The pH remained close to 2.94. The total composition of the feedstock is given in Table 5. These conditions resulted in 81% conversion of monomer to polymer. The final polymer contained 4.4% by weight of itaconic acid (680 meq / carboxylate ion per kg of polymer), 0.9% by weight of vinyl acetate and the rest of acrylonitrile. The average particle size was 9.0 microns, with a bell-shaped distribution having 10% by weight of the particles below 1.6 microns and 10% by weight of the particles above 28 microns.

TABLE 5 Total composition of the feeding material Compound Quantity Units Acrylonitrile monomer 94.8 Parts Vinyl acetate monomer 1.2 Parts itaconic acid 4.0 Parts Water 250.0 Parts Sodium persulp (initiator) 0.38% based on the monomer Sodium bisulfate as dioxidod of 0.86% based on the sulfur (activator) monomer Iron (ferrous or ferric) 1.6 Parts per million monomer Sulfuric Acid Traces EXAMPLE 5 In this example, polymer particles made in a solution tfavors the incorporation of sodium ions are exchanged with Larostat under various conditions and the amount of sodium removed from the polymer particle is determined. The theoretical amount of Larostat needed to exchange the sodium in the polymer was 0.286 grams of Larostat at 35% by weight per gram of polymer. Two grams of deionized water per gram of polymer were also used. The water and the Larostat are boiled and the polymer is added. The heat is removed and the solution is cooled in a period of 15 minutes. Then the polymer is filtered and the liquid is discarded. An additional six grams of deionized water is used to wash each gram of polymer in the filter. The unwashed polymer had approximately 5, 100 parts per million sodium by weight in the polymer, while the polymer subject to exchange contained only 636 parts per million sodium by weight. All compositions and methods described and claimed in the present invention can be made and executed without undue experimentation in light of the present disclosure. Although the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the art that variations can be applied to the compositions and methods and in the steps or sequences of steps of the method described in present invention without departing from the concept, scope and spirit of the invention. More specifically, it will be apparent that the agents described in the present invention can be substituted with some agents that are both chemically and physiologically related while at the same time equal or similar results can be obtained. All of such substitutes and obvious modifications for those skilled in the art are considered to be within the scope, scope and concept of the invention as defined by the appended claims.

Claims (10)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for preparing polymer particles comprising polyacrylonitrile in an aqueous dispersion polymerization process, which comprises polymerizing acrylonitrile monomer with an ionic monomer, characterized in that the ionic monomer comprises at least one colorant site, and because the amount of added ionic monomer is such that the number of colorant sites, incorporated in the polymer, from the ionic monomer is in the range of about 100 meq / kg of polymer to about 1,000 meq / kg of polymer.

2. The method according to claim 1, further characterized in that the ionic monomer comprises salts of p-styrenesulfonate, p-sulphophenyl metal ether, 2-methyl-2-acrylamidopropanesulfonate, itaconic acid, or salts thereof.

3. The method according to claim 1, further characterized in that the weight to weight ratio of water to monomer in the feedstock is about 2.0: 1 or less.

4. The method according to claim 1, further characterized in that the weight to weight ratio of water to monomer in the feedstock is about 1.6: 1 or less.

5. - The method according to claim 1, further characterized in that the ionic monomer comprises a carboxylate functional group or a sulfonate functional group.

6. The method according to claim 1, further characterized in that the polymer comprises a neutral comonomer.

7. The method according to claim 1, further characterized in that the ionic monomer comprises one or more of taconic acid or a salt thereof.

8. The method according to claim 1, further characterized in that the ionic monomer comprises one or more of methallylsulfonate or a salt thereof.

9. The method according to claim 1, further characterized in that the ionic monomer comprises one or more of methallylsulfonate or a salt thereof, and in that the polymer comprises a neutral comonomer.

10. The method according to claim 9, further characterized in that the ionic monomer comprises one or more of methallylsulfonate or a salt thereof, and the neutral comonomer comprises vinyl acetate. 1. The method according to claim 1, further characterized in that the ionic monomer comprises methallylsulfonate or a salt thereof, and the number of dye sites incorporated in the polymer is in the range of about 200 meq / kg to approximately 400 meq / kg of polymer. 12. The method according to claim 1, further characterized in that the ionic monomer comprises one or more of methallylsulfonate or a salt thereof, and the number of dye sites incorporated in the polymer is in the range of about 240. meq / kg to about 280 meq / kg of polymer. 13. The method according to claim 1, further characterized in that the ionic monomer comprises one or more of methallylsulfonate or a salt thereof, the number of dye sites incorporated in the polymer is in the range of about 240 meq / kg to about 280 meq / kg of polymer, and the polymer comprises a neutral comonomer. 14. The method according to claim 1, further characterized in that the number of dye sites incorporated in the polymer is in the range of about 150 meq / kg of polymer to about 1,000 meq / kg of polymer. 15. The method according to claim 2, further characterized in that the number of dye sites incorporated in the polymer is in the range of about 200 meq / kg of polymer to about 600 meq / kg of polymer. 16. The method according to claim 2, further characterized in that the number of dye sites incorporated in the polymer is in the range of about 200 meq / kg of polymer to about 800 meq / kg of polymer, and because the polymer comprises a neutral comonomer. 17. The method according to claim 6, further characterized in that the ionic monomer comprises one or more of p-sulfophenyl metalyl ether or a salt thereof, and the number of dye sites incorporated in the polymer is in the range from about 200 meq / kg of polymer to about 1,000 meq / kg of polymer, and because the neutral comonomer comprises vinyl acetate. 18. The method according to claim 1, further characterized in that the cations associated with the ionic comonomer are exchanged from the polymer using chemical exchange with a quaternary alkylammonium compound. 19. The method according to claim 18, further characterized in that the quaternary alkylammonium compound is a quaternary ammonium salt or an amine of dimethylgrase acid. 20. The method according to claim 2, further characterized in that the cations associated with one or more of the ionic monomers, activators, or initiators are ammonium. 21. The method according to claim 6, further characterized in that the neutral comonomer comprises vinyl acetate. 22. The product according to claim 1.