JPH0125323B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an acrylonitrile polymer that provides fibers that have flame retardancy and excellent devitrification prevention properties. Acrylic fibers have many excellent chemical and physical properties such as dyeability, texture, and light resistance. However, in recent years, our living environment has become increasingly exposed to the dangers of disasters such as fire, and as people's living standards have improved, there has been a rapid rise in demand for flame retardant textile products, especially acrylic. The flammability of fibers is becoming a major problem. Since acrylic fibers inherently lack flame retardancy, they are not preferred for use in interior products such as curtains and carpets that require flame retardancy, clothing for infants and the elderly, and the like. In order to improve this drawback, conventional methods include adding a flame retardant to the spinning dope and spinning, adding a flame retardant through post-processing, and spinning a mixture of a flame retardant polymer and an acrylic polymer. Although it has been considered, nothing that is fully satisfactory has yet been obtained. Although this imparts flame retardant properties, since a large amount of flame retardant is added, the original physical properties of acrylic fibers
It is difficult to obtain permanent flame retardancy because the texture is poor, and the flame retardant falls off during dyeing, washing, etc., resulting in a decrease in flame retardancy. In addition, in the mixed spinning method,
It is difficult to keep the spinning stock solution uniform and stable,
This is because it is difficult to produce industrially. On the other hand, as a method of semi-permanently imparting flame retardancy, acrylonitrile is treated with halogen-containing monomers such as vinyl chloride, vinylidene chloride, vinyl bromide, etc.
A method of copolymerizing vinylidene bromide and the like has been used. In this case, it is said that the higher the halogen content, the better the flame retardancy, but on the other hand, the anti-devitrification properties are significantly reduced, which has the major disadvantage of impairing fiber properties, processability, and marketability. ing. The reason for this is that acrylic fibers that contain a large amount of vinyl halide monomers are generally manufactured using a wet spinning method, which tends to create fine voids within the fiber structure, and that the softening temperature of the fibers is low. Therefore, it is presumed that this is due to the fact that it easily swells in a relatively low temperature range. Therefore, in order to improve the devitrification properties of acrylic fibers containing large amounts of vinyl halide monomers, it is particularly important to prevent the formation of fine voids within the fiber structure in the coagulation bath. be. As a method to improve such devitrification, so-called acrylic synthetic fibers containing 85% or more of acrylonitrile are generally copolymerized with vinyl monomers containing sulfonic acid groups, which also serve as a dye binding site. devitrification is prevented. However, as in the present invention, it is difficult to form a dense fiber structure with so-called modacrylic synthetic fibers containing a large amount of vinyl halide monomers, so a vinyl monomer containing a sulfonic acid group is introduced. Not only is it extremely difficult to prevent devitrification, but the devitrification prevention property may even further deteriorate. For this reason, in the modacrylic fiber industry, there is an urgent need to improve this anti-devitrification property to the same level as that of acrylic fibers, but it is still not possible to obtain a material that has both sufficiently satisfactory flame retardancy and anti-devitrification properties. Not yet. As a method for improving the devitrification property of modacrylic fibers from the polymerization stage, Japanese Patent Publication No. 53-9299,
No. 53-9300 describes a method of solution polymerization by adding a copolymer containing a large amount of anionic monomer to the polymerization system. However, in all of these methods, an acrylonitrile copolymer containing a large amount of anionic monomer is produced in advance, and this is added to the polymerization system before solution polymerization, so a hydrophilic copolymer is separately prepared, In order to obtain stable fiber performance, the amount added must be adjusted depending on the polymerization yield of solution polymerization, which makes the manufacturing method complicated. moreover,
Since the thermal history of the anionic monomer-containing copolymer initially added to the polymerization system is doubled because it undergoes two polymerizations, it is also unfavorable from the viewpoint of preventing coloration. Moreover, when sodium allylsulfonate or sodium methacrylsulfonate is used as an anionic monomer as a copolymerization component of the polymer initially added to the polymerization system, the amount used is relatively large, so dimethylformamide, etc. It is difficult to dissolve in organic solvents, and the solution polymerization system tends to be non-uniform. In order to prevent such adverse effects, if the monomer concentration in the polymerization system is lowered and the amount of solvent is increased, the degree of polymerization of the resulting polymer will be lowered and productivity will be lowered. In addition, it is difficult to maintain the obtained spinning stock solution as a homogeneous solution because the difference between the hydrophilicity and hydrophobicity of the mixed copolymers is relatively large. In some cases, depending on the type of organic solvent used, the hydrophilic copolymer may not dissolve or may only swell.
Spinning using a spinning dope lacking such uniformity causes problems such as nozzle clogging and yarn breakage, making it difficult to stably produce fibers.
Furthermore, copolymers with high hydrophilicity tend to leak into coagulation baths or washing baths, which reduces their devitrification prevention effect by half, and it is difficult to stably obtain qualities such as dyeability, making them industrially advantageous. It cannot be called a method. As a result of intensive research into acrylic synthetic fibers that are flame retardant and have excellent anti-devitrification properties, the present inventors have found that a copolymer mainly composed of acrylonitrile/vinyl chloride and/or vinylidene chloride in a specific composition range can be used as a high-grade synthetic fiber. Fibers with flame retardancy are obtained, and when producing this copolymer, a specific sulfonic acid group-containing vinyl monomer is copolymerized using a special method, resulting in extremely good devitrification prevention properties. The present invention was achieved by discovering that fibers with a high degree of stability can be obtained. That is, the present invention provides a method for polymerizing 40 to 65% by weight of acrylonitrile, 31 to 59.9% by weight of vinyl chloride and/or vinylidene chloride, and 0.1 to 4% by weight of a sulfonic acid group-containing vinyl monomer satisfying formula (2). ,
This is a method for producing an acrylonitrile polymer, which is polymerized under conditions that satisfy the following formula (1). 0<Y−X<83 ...(1) Z ₁ /Z ₂ >1 ...(2) (wherein, , indicates the percentage of the polymer formed at the end of the addition to the total polymer, and Z ₁ and Z ₂ indicate the reactivity ratio of the sulfonic acid group-containing vinyl monomer and acrylonitrile, respectively.) The present invention will be described in detail below. Explain. The composition of the acrylonitrile polymer containing a vinyl halide monomer obtained by the present invention is as follows:
40~65% by weight acrylonitrile (AN) and 31~
It needs to be an acrylonitrile-based polymer mainly containing 59.9% by weight of vinyl chloride (VC) and/or vinylidene chloride (VD). The content of acrylonitrile in the polymer composition was specified to be 40 to 65% by weight because if it is less than 40% by weight, it will not be possible to maintain the fiber performance as a synthetic fiber such as devitrification prevention property when made into a fiber. Moreover, if it exceeds 65% by weight, it is difficult to provide a high degree of flame retardancy, although the properties as a synthetic fiber can be easily obtained. In addition, when acetone, acetonitrile, especially acetone is used as a solvent for the spinning stock solution, the content of acrylonitrile is preferably 40 to 58% by weight (vinyl chloride and/or vinylidene chloride is 38 to 59.9% by weight), and more preferably 40 to 55% by weight. It is more preferable to set it as 41 to 59.9 weight% of vinyl chloride and/or vinylidene chloride. This is because if the acrylonitrile content exceeds 58% by weight, the solubility of the polymer in acetone decreases, making it difficult to prepare a uniform solution suitable for spinning. On the other hand, the content of vinyl chloride and/or vinylidene chloride was specified as 31 to 59.9% by weight because if it is less than 31% by weight, it cannot provide high flame retardancy when made into fibers, and if it exceeds 59.9% by weight This is because although it is easy to obtain flame retardancy, it is difficult to maintain the fiber performance as a synthetic fiber. The acrylonitrile polymer obtained by the present invention mainly contains acrylonitrile and vinyl chloride and/or vinylidene chloride as described above, but it also contains a specific amount of a sulfonic acid group-containing vinyl monomer that satisfies formula (2) as described later. It is essential to use it as a copolymer component. In addition to these copolymerizable components, a small amount of a monoolefinic monomer copolymerizable therewith may be contained. Examples of monoolefinic monomers that can be copolymerized include acrylic acid, methacrylic acid, and their esters, acrylamide, methacrylamide, vinyl acetate, and vinyl bromide. There is no problem even if the content is 10% by weight or less. A small amount of a sulfonic acid group-containing monovinyl monomer that does not satisfy formula (2) may be copolymerized as the monoolefinic monomer, but this may impair the hydrophobicity of the hydrophobic portion of the copolymer of the present invention. It should be kept to a minimum. Furthermore, the acrylonitrile-based polymer containing a halogenated vinyl monomer obtained by the present invention contains 0.1 to 4% by weight of a sulfonic acid group-containing vinyl monomer that satisfies the above formula (2), and has the formula ( It is necessary that the polymerization is carried out under conditions satisfying 1), and in particular, formula (1) is preferably 3% or more and 75% or less. This is because when the value of formula (1) is 0%, there is little copolymer copolymerized with a sulfonic acid group-containing vinyl monomer in the produced polymer, and the copolymer is relatively hydrophilic. As a result, the spinning stock solution prepared from this polymer lacks uniformity, resulting in frequent nozzle clogging and thread breakage, as well as the tendency for the hydrophilic copolymer to flow out in the coagulation bath or washing bath. Therefore, when made into fibers, they lack fiber properties such as dyeability, and stable quality cannot be obtained. This tendency is particularly observed in the production method in which acrylonitrile and vinyl chloride and/or vinylidene chloride are mixed with a sulfonic acid group-containing vinyl monomer satisfying formula (2) and then polymerized, that is, when X=0, Y=0. It is often seen in In addition, if the value of formula (1) is 83% or more,
Among the polymers produced, there are many copolymers made by copolymerizing vinyl monomers containing sulfonic acid groups, but
Due to the small amount of sulfonic acid group-containing vinyl monomer component contained in each copolymer, it is difficult to give the fibers a dense coagulated structure in a coagulation bath. This is because it is difficult. Note that the preferred value of formula (1) varies depending on the solvent of the spinning stock solution used during spinning. That is, when acetone, acetonitrile, particularly acetone, is used, the value of formula (1) is preferably more than 16% and less than 83%, particularly preferably 33% or more and 75% or less. Furthermore, when using dimethylformamide, dimethylacetamide, dimethylsulfoxide, especially dimethylformamide, the value of formula (1) is 0%.
preferably more than 61%, especially 3%
More preferably, it is 40% or less. The reason for this is that the coagulation structure differs depending on the type of solvent used during spinning, and when making the copolymer of the present invention into fibers, it is necessary to use a copolymer that gives the fibers a dense coagulation structure in a coagulation bath. The copolymer of the present invention must be selected depending on the solvent used. In addition, in the present invention, the sulfonic acid group-containing vinyl monomer used to satisfy formula (1) is specified to satisfy formula (2) because this value is 1 or less. Due to its poor copolymerizability, it does not copolymerize immediately even if it is added to the polymerization system, and even if its supply is stopped, it remains as an unreacted monomer due to its poor reactivity, and the copolymerization reaction is delayed. This is because it is not possible to quantitatively and efficiently obtain a copolymer having a copolymerization amount and composition effective for preventing devitrification when it is slowly carried out and made into fibers, so there is no point in using it while satisfying formula (1). be. It is unclear why fibers with improved devitrification prevention properties are obtained from polymers containing vinyl monomers containing sulfonic acid groups with this value exceeding 1, but these monomers have high copolymerizability. For,
When added to the polymerization system, it quickly copolymerizes, and if its supply is stopped, the copolymerization reaction quickly ends, leaving almost no unreacted monomer, so the sulfonic acid group-containing vinyl monomer The copolymer containing the copolymer and the copolymer without the copolymer are produced very smoothly and quantitatively, and a copolymer having a copolymerization amount and composition effective for preventing devitrification when made into fibers can be easily obtained. It is estimated that Furthermore, in the present invention, since a copolymer containing a sulfonic acid group-containing vinyl monomer that satisfies formula (2) and a copolymer not containing it are produced in the same polymerization system, the formula (2) When the addition of the sulfonic acid group-containing vinyl monomer that satisfies ( ) to the polymerization system is started or finished, a very small amount of copolymer is produced in which the content of the sulfonic acid group-containing vinyl monomer continuously increases and decreases. It is thought that this further promoted the appearance of a dense coagulated structure that is effective in preventing devitrification of the fibers. Examples of the sulfonic acid group-containing vinyl monomer satisfying formula (2) used in the present invention include sulfonic acid group-containing acrylic or methacrylic acid esters such as methacryloyloxypropylsulfonic acid, styrene sulfonic acid and vinylbenzyl sulfonic acid, etc. These include sulfonic acid group-containing vinyl monomers having styrenic unsaturated bonds, and salts thereof such as sodium, potassium, and ammonium, and it is necessary to use one or more of these. The content of the sulfonic acid group-containing vinyl monomer satisfying formula (2) in the copolymer obtained by the present invention is:
It is preferably 0.1 to 4% by weight, preferably 0.3 to 3% by weight. If it is less than 0.1% by weight, the difference in hydrophilicity between a polymer copolymerized with a sulfonic acid group-containing vinyl monomer and a polymer not copolymerized is small, making it difficult to provide a dense solidified structure. Also 4% by weight
If the value exceeds 100%, the difference in hydrophilicity in the copolymer will become too large, resulting in uneven coagulation, resulting in a large number of voids, or the copolymer containing a sulfonic acid group-containing vinyl monomer may This is because the coalescence may flow out, making it impossible to stably obtain qualities such as devitrification prevention properties and dyeability when made into fibers. Moreover, the manufacturing cost also increases, which is economically disadvantageous. When the preferable molecular weight of the polymer obtained by the present invention is shown using specific viscosity, it is preferably 0.13 to 0.60, and particularly preferably 0.15 to 0.54. Note that this specific viscosity was measured at 30°C for a solution in which 2 grams of the polymer was dissolved in 1 liter of dimethylformamide. Methods for adding the sulfonic acid group-containing vinyl monomer satisfying formula (2) into the polymerization system include a continuous addition method and an intermittent addition method. The amount added may be determined by an equal addition method, a gradual increase/decrease method, or a combination thereof, but an even continuous addition method is particularly preferred. Although it is not clear why the copolymer meeting the requirements of the present invention can improve the devitrification property when made into fibers, it is unclear why modacrylic synthetic fibers made of copolymers containing a large amount of vinyl halide monomers can be used. In order to improve devitrification during production, it is necessary to prevent the formation of fine voids within the fiber structure in the coagulation bath. For this purpose, it is essential to prepare a polymer that continuously produces a uniform and dense coagulated structure in a coagulation bath, and a polymer that satisfies the conditions of the present invention is a vinyl polymer containing a sulfonic acid group that satisfies formula (2). Because the proportion of the copolymer containing monomers and the amount of copolymerization are kept well-balanced, the hydrophilic copolymer and hydrophobic copolymer are ideally balanced and integrated. It is thought that this causes continuous uniform precipitation behavior and the appearance of a dense solidified structure, which prevents devitrification when made into fibers. The copolymer obtained according to the present invention can be produced by any polymerization method such as emulsion polymerization or suspension polymerization in an aqueous medium or an aqueous medium containing an organic solvent, or solution polymerization. When produced by emulsion polymerization, there are preferred polymerization methods as described below. Catalysts used in polymerization include common radical polymerization initiators, such as persulfates, or combinations of persulfates and acidic sulfites or salts thereof;
Further examples include azo compounds such as azobisdimethylvaleronitrile and peroxides such as benzoyl peroxide, but are not particularly limited. Among polymers for acrylonitrile fibers with low acrylonitrile content, called modacrylic fibers, solution polymerization methods are relatively rarely used in the production of acrylonitrile polymers containing vinyl chloride. few. This is because while the solution polymerization method has its advantages, depending on the solvent used, the solvent molecules tend to cause a chain transfer reaction with the growing polymer radicals, which tends to reduce the average weight. It is difficult to maintain fiber physical properties and devitrification prevention properties, and furthermore, because the polymerization rate is low, the polymerization time is long and the polymer solution is easily colored. This is because acrylonitrile-based polymers containing vinyl are large. Therefore, the present inventors investigated various methods for producing acrylonitrile polymers containing halogenated monomers by emulsion polymerization as in the present invention, and as a result, they improved the drawbacks of the conventional emulsion polymerization method, and We have discovered an economically advantageous manufacturing method that allows easy production of an acrylonitrile polymer that provides fibers with excellent flame retardancy and anti-devitrification properties, and have arrived at the invention of the method for manufacturing the polymer of the present invention. It is. That is, the invention of the method for producing the polymer of the present invention is
In polymerizing 40 to 65% by weight of acrylonitrile, 31 to 59.9% by weight of vinyl chloride and/or vinylidene chloride, and 0.1 to 4% by weight of a sulfonic acid group-containing vinyl monomer satisfying the above formula (2), the above formula This is a method for producing an acrylonitrile polymer in which emulsion polymerization is carried out under conditions that satisfy (1) and the following formula (3). Y>71...(3) As mentioned above, in the invention of the method for producing the polymer of the present invention, the content of acrylonitrile in the composition of the acrylonitrile polymer is defined as 40 to 65% by weight, This is because, especially in emulsion polymerization methods, if the content exceeds 65% by weight, it is difficult to keep the aqueous polymer solution stable. Furthermore, in order to obtain a polymer powder from an aqueous polymer solution in emulsion polymerization, the polymer is first separated from the aqueous solution by salting out, coagulation, and filtration, and then washed with water, dehydrated, and dried. However, if the content of acrylonitrile exceeds 65% by weight, the water content during dehydration will increase, resulting in a decrease in drying efficiency, which is industrially undesirable. In addition, the content of the sulfonic acid group-containing vinyl monomer that satisfies (2) is 4% by weight or less as described above,
Particularly in the emulsion polymerization method, if the amount exceeds 4% by weight, the highly hydrophilic polymer generated in the polymerization system will easily flow out during filtration, water washing, and dehydration after salting out, resulting in poor devitrification prevention and dyeing properties. This is because the quality cannot be stably obtained. The method for adding the sulfonic acid group-containing vinyl monomer satisfying formula (2) includes the continuous addition method and the intermittent addition method, as described above. The amount to be added may be determined by an equal addition method, a gradual increase/decrease method, or a combination thereof, but an even continuous addition method is particularly preferred. The reason why the value of Y in formula (3) is specified to exceed 71% in the emulsion polymerization method of the invention of the method for producing the polymer of the present invention is that if it is less than 71%, the resulting emulsion polymer aqueous solution is unstable. Therefore, it becomes easier to solidify,
This is because it is relatively difficult to proceed with stable polymerization or to stably store an aqueous emulsion polymer solution.
Note that the value of Y is more preferably 75% or more and 96% or less. This is because when the value of Y exceeds 96%, the aqueous solution of the emulsion polymer is stable, which is preferable, but the water content of the water-containing resin increases and the drying efficiency tends to decrease slightly. . Anionic surfactants are particularly effective as surfactants for the emulsion polymerization method used in the invention of the method for producing the polymer of the present invention. Examples include salt. In addition to the anionic surfactant, a small amount of a normal nonionic surfactant may also be used in combination with the surfactant used. The higher the amount of these surfactants used, the better the quality of the polymer produced, but if too much surfactant is used, the water content of the hydrous resin will become extremely high, leading to a rapid deterioration of drying efficiency. 0.1 to 10% by weight, especially 0.2 to 5% by weight based on the total monomer, as this may cause a decrease in the quality of wastewater from the polymerization process.
It is preferable to use Catalysts used in the polymerization of the method for producing the polymer of the present invention include common radical polymerization initiators,
For example, persulfate which is a thermal decomposition initiator or
persulfates and ferrous salts, which are redox initiators;
Examples include, but are not limited to, Fuenton's reagent based on hydrogen peroxide and ferrous iron, persulfate and sodium thiosulfate, persulfate and acidic sodium sulfite, and hydrogen peroxide and oxycarboxylic acid. Also, the polymerization temperature is 30
It is desirable to employ a temperature of ~70°C, and the monomer concentration is preferably 10 to 70% by weight based on the total polymerization system. In addition to the aqueous medium, the polymerization medium useful for carrying out the invention of the manufacturing method may contain a small amount of an ordinary organic solvent that is uniformly soluble in the aqueous medium. Considering the water quality of water and wastewater, it is not a very good method from an industrial perspective. The polymer is usually separated from the emulsion polymer aqueous solution by using an aqueous solution of electrolytes such as salts for salting out, such as sodium chloride, calcium chloride, magnesium sulfate, and aluminum sulfate, followed by filtration, water washing, dehydration, and drying. Through this process, a polymer powder is obtained. In this way, the invention of the method for producing a polymer of the present invention improves the drawbacks of the conventional emulsion polymerization method, makes it possible to economically produce a polymer from a stable aqueous emulsion polymer solution, and furthermore, Modacrylic synthetic fibers with excellent flammability and devitrification prevention properties can be obtained. Note that a solution polymerization method is also mentioned as one of the methods for producing the copolymer of the present invention. As the solvent used in the polymerization, it is preferable to use ethylene carbonate, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, etc., which have a relatively small chain transfer constant. In addition to these organic solvents, as the polymerization medium, a small amount of water or other organic solvent may be used as long as it does not interfere with the uniform solubility or polymerization of the copolymer. Catalysts used in the polymerization include common radical polymerization initiators, such as persulfates such as ammonium persulfate and potassium persulfate, or 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,
Azo compounds such as 2'-azobis-isobutyronitrile, peroxides such as di(2-ethylhexyl) peroxydicarbonate, t-butyl peroxypivalate, lauroyl peroxide, or hydrogen peroxide and L - Although combinations with ascorbic acid are not particularly limited, it is particularly preferable to use a low-temperature activated catalyst from the viewpoint of maintaining the degree of polymerization and preventing discoloration. Further, it is preferable that the polymerization temperature is 35 to 70°C, and the monomer concentration is preferably 20 to 70% by weight based on the total polymerization system. Incidentally, in the polymerization, a coloring inhibitor such as an epoxy compound, an organic tin compound, or an organic reducing agent may be used as necessary. As a method for removing unreacted monomers such as acrylonitrile, vinyl chloride, vinylidene chloride, etc. from the polymer solution mixture obtained in this way, if vinyl chloride is present as an unreacted monomer, It is preferable to first remove most of the vinyl chloride under normal pressure and then also recover monomers such as acrylonitrile and vinylidene chloride under reduced pressure.
The operating conditions for monomer removal under reduced pressure are 10~
Preferably, it is carried out at 200 mmHg and 40-90°C.
At this point, in order to adjust the ease of removal of unreacted monomers and the final polymer concentration, in each removal step,
It is desirable to add the organic solvent used in the polymerization system as appropriate. To produce fibers from the copolymer obtained according to the present invention, both conventional wet and dry spinning methods are possible, but wet spinning is particularly preferred.
As the solvent for the spinning dope, acetonitrile, acetone, dimethylacetamide, dimethylformamide, dimethylsulfoxide, etc., which are ordinary solvents for acrylonitrile polymers, are used, but as mentioned above, the preferable value of formula (1) depends on the solvent. Depending on the solvent used, it is necessary to select the copolymer to be used. The spinning dope may contain ordinary stabilizers against heat and light, additives for improving texture, or flame retardants for further increasing flame retardancy. The fibers obtained in this manner improve the drawbacks of conventional acrylonitrile synthetic fibers, and can provide fibers with excellent flame retardancy and anti-devitrification properties. Next, a method for evaluating the flame retardancy, devitrification property, and dyeability of fibers made from the copolymer obtained according to the present invention will be explained. Flame retardancy was measured using an oxygen index flame tester. In the oxygen index method, first 3 denier 300
Six book filaments were twisted 75 times in a 25-inch length to make two rope-shaped specimens, and this was further twisted to 75 times.
The sample was deflated and placed upright in the holder of an oxygen index combustion tester to measure the percentage of oxygen required for the sample to burn for 5 cm. The higher the value indicated by the oxygen index method, the more flame retardant. The devitrification was measured by the transmittance method. First, a 3-denier filament was treated in boiling water for 30 minutes, then cut into 3 mm lengths. 200 mg of this was collected, sandwiched uniformly between quartz plate glasses, and placed in a 1 cm thick quartz cell containing 3 ml of parachlorotoluene. Ta. Using the untreated yarn as a blank, the transmittance of the boiling water treated yarn was measured using a spectrophotometer at a wavelength of 650 mμ.
The larger the numerical value indicated by the transmittance, the better the devitrification prevention property. Dyeability was determined using 2.5% by weight of malachite green dye on a 3 denier filament in boiling water at 90°C.
The exhaustion rate of the dye was measured when dyeing was carried out for minutes. The larger the stainability value, the better the stainability. Next, a method for measuring the water content of a water-containing resin obtained by salting out an emulsion polymer aqueous solution in the method for producing a polymer of the present invention will be described. 1000 ml of an aqueous emulsion polymer solution was heated to 55°C, and 100 ml of a 20% aqueous sodium chloride solution was added thereto with stirring. The generated polymer slurry was further stirred and heated until the liquid temperature reached 90℃.
After holding for 8 minutes, the mixture was cooled to 70°C. next,
Polyester cloth with a diameter of 12cm (air permeability approx. 45cm/
sec) was immersed in this salted-out slurry aqueous solution for 5 seconds under a reduced pressure of 200 mmHg, and then dehydrated for 30 seconds. The amount of water-containing polymer obtained in this way is Wg, and the weight of the polymer after drying it at 70℃ for 6 hours is
When W is _0g , the water content is expressed as follows. Water content (%) = W - W ₀ /W ₀ ×100 The present invention will be explained in detail with reference to Examples below. The yields of the polymers shown in the Examples and Comparative Examples are expressed as follows. It is. Polymer yield (%) = Amount of polymer produced up to that point x 100/(Final total amount of monomers added to the polymerization system) - (Final amount of recovered unreacted VC) Example 1 Internal volume 15 Emulsion polymerization was carried out using a pressure-resistant polymerization reactor. The polymerization conditions were: 40.4 parts of acrylonitrile (AN), 12.8 parts of vinylidene chloride (VD),
Using 260 parts of water to 46.1 parts of vinyl chloride (VC), using a combination of ammonium persulfate and acidic sodium sulfite as a polymerization initiator, and using 0.9 parts of sodium lauryl sulfate as a surfactant,
The pH of the polymerization system was adjusted to 2.2, the reaction temperature was 38°C, and the polymerization time was 7 hours. During this emulsion polymerization, 0.7 parts of vinylbenzylsulfonate sodium (VBSA) was added as a sulfonic acid group-containing vinyl monomer from 2 hours (polymer yield 29.3%) to 6 hours (polymer yield 29.3%). Rate 85.4
%) was continuously added to the polymerization system in equal amounts. In order to keep the composition of the produced polymer uniform, out of the acrylonitrile and vinylidene chloride used,
29.6 parts of acrylonitrile and 4.6 parts of vinylidene chloride were continuously added to the polymerized thread over the entire polymerization time as the polymerization progressed. Furthermore, in order to keep the polymerization rate constant, a portion of the ammonium persulfate used was continuously added. The composition of the thus obtained polymer was 49.2% by weight of acrylonitrile, 15.3% by weight of vinylidene chloride, 34.6% by weight of vinyl chloride, and 0.9% by weight of sodium vinylbenzyl sulfonate, and 18.7 parts of unreacted vinyl chloride was recovered. The yield of polymer at that point is
It was 96.8%. The polymer obtained by this polymerization method (specific viscosity
Since 0.192) had a Y content of 88.2%, its aqueous polymer solution was extremely stable, and the water content of the water-containing resin obtained by salting out was as good as 98.5%. In addition, the synthetic fiber obtained by dissolving this polymer in acetone to make a 30% spinning stock solution and wet-spinning it into a 35% acetone aqueous solution has a permeable Y-X value of 58.0%. Excellent devitrification prevention with a rate of 78.8%.
The flame retardancy was also good with a atomic index value of 32.2. Examples 2 to 8 Comparative Examples 1 to 4 X, Y by changing the time to start or end the addition of the sulfonic acid group-containing vinyl monomer to the polymerization system
The effect of the value on polymer properties and devitrification prevention properties was investigated. The polymerization conditions were as follows: 40.4 parts of acrylonitrile, 59.1 parts of vinyl chloride, 270 parts of water, a combination of ammonium persulfate and acidic sodium sulfite as a polymerization initiator, and 0.8 parts of sodium lauryl sulfate as a surfactant. and the pH of the polymerization system to 2.3.
The reaction temperature was adjusted to 39° C. and the polymerization time was 7 hours. During this polymerization, as a vinyl monomer containing a sulfonic acid group, 0.5 part of sodium styrene sulfonate was added between 6 hours after the start of polymerization, and an equal amount was added between 4 hours and 7 hours after the start of polymerization. By this time, the addition of each had been completed. The composition of the obtained polymer is acrylonitrile
49.4% by weight, vinyl chloride 50.0% by weight, and sodium styrene sulfonate 0.6% by weight, and the yield of the polymer was about 96%. Table 1 shows the properties of these polymers and the results of the anti-devitrification properties of fibers obtained by dissolving these polymers in acetone to prepare a spinning dope and wet spinning in an acetone aqueous solution. The flame retardance was good with an oxygen index value of 28.1 because the compositions of the polymers were the same.

[Table] Since Examples 2 to 7 all satisfied the conditions of the present invention, the aqueous solutions of the polymers were stable and had an improved drying efficiency with a water content of 120% or less. In addition, the fibers obtained from these materials also have low transmittance.
It had an excellent devitrification prevention property of 70% or more. However, since Example 8 satisfied the conditions Y-X, the devitrification prevention property was good;
Since the value of Y was 71% or less, the stability of the aqueous polymer solution was poor, and it solidified after one day. Also,
In Comparative Examples 1 to 4, none of the conditions Y-X were satisfied, so the devitrification prevention properties were poor, and in Comparative Example 1, the value of Y was about 69%, so there was a problem with the stability of the aqueous polymer solution. It was hot. Examples 9 to 13 Comparative Examples 5 to 8 The effects of sulfonic acid group-containing vinyl monomers on polymerization properties and devitrification prevention properties were investigated. As the sulfonic acid group-containing vinyl monomer, sodium methacryloyloxypropylsulfonate (SPMA), sodium styrene sulfonate (SSS), which satisfies formula (2),
Ammonium styrene sulfonate (ASS), vinylbenzyl sodium sulfonate (VBSA), and as a comparative example, the reactivity ratio of acrylonitrile to that without adding a sulfonic acid group-containing vinyl monomer is 1 or less. Sodium methallylsulfonate (SMAS) and sodium allylsulfonate (SAS), which are vinyl monomers containing sulfonic acid groups, have a reactivity ratio of . The polymerization conditions were the same as in Example 1, but in Comparative Examples 7 and 8 using SMAS and SAS, the polymerization rate was slow, so the polymer yield was adjusted to about 97% with a polymerization time of 7 hours. The experiment was carried out by adjusting the amount of catalyst. Table 2 shows the properties and devitrification prevention properties of the obtained polymer. In addition, the values of Y-X and Y of the obtained polymer were 56 to 60% and 87 to 89, respectively.
%, and the composition of the polymer is also AN48~50% by weight,
VD was 14 to 16% by weight and VC was 34 to 36% by weight, both of which satisfied the conditions of the present invention. These polymers were dissolved in acetone to prepare a 30% spinning stock solution, and then wet spinning was performed in a coagulation bath of a 35% acetone aqueous solution to obtain modacrylic synthetic fibers. Table 2 shows the results of the devitrification prevention properties of the obtained synthetic fibers. Regarding flame retardancy, the oxygen index value is approximately
It was good at 31-32.

[Table] Examples 9 to 13 use a sulfonic acid group-containing vinyl monomer that satisfies formula (2), so the aqueous solutions of the produced polymers are extremely stable and have a water content of 120%.
All of the following were good, and the fibers obtained from these had excellent devitrification prevention properties. However, in Comparative Example 5 in which the sulfonic acid group-containing vinyl monomer was not added, the stability of the aqueous polymer solution was somewhat poor, and the devitrification prevention property was also poor with a transmittance of 60% or less. In addition, in Comparative Example 6, which uses a vinyl monomer containing a sulfonic acid group that satisfies formula (2), since the amount used was large, a polymer with poor water content and poor drying efficiency was obtained. The resulting spinning dope contained acetone-insoluble matter and had poor thread-preventing properties, and its devitrification-preventing properties were not particularly improved. In Comparative Examples 7 and 8, SMAS and SAS were used as the sulfonic acid group-containing vinyl monomer, but
When these monomers are added to the polymerization system, they cause a chain transfer reaction with the growing polymer radicals.
A situation occurred in which the polymerization rate decreased. Therefore, the amount of catalyst used was increased to maintain the polymerization rate, but the produced aqueous polymer solution lacked stability and had an inferior water content of 130% or more.
The fibers obtained from these had poor devitrification prevention properties and unsatisfactory dyeability, probably because a copolymer having a composition and copolymerization amount effective for preventing devitrification was not obtained. Example 14 Emulsion polymerization was carried out using a pressure-resistant polymerization reactor having an internal volume of 15 mm. The polymerization conditions were: 58.6 parts of AN, 1.5 parts of methyl acrylate (MA), 38.2 parts of VD, and water.
450 parts, and 0.2 parts of ammonium persulfate, 0.7 parts of sulfur dioxide, and 0.002 parts of ferrous sulfate as polymerization initiators.
The reaction temperature was 40° C. and the polymerization time was 5 hours using 1.2 parts of sodium lauryl sulfate as a surfactant and 2 parts of hydroquinone as a molecular weight regulator. During this emulsion polymerization, 1.7 parts of SSS was added as a sulfonic acid group vinyl monomer from 3 hours (polymer yield: 59.1%) to 4 hours (polymer yield: 59.1%).
71.9%) was continuously added to the polymerization system in equal amounts.
In order to maintain the polymerization rate, 0.15 part of the 0.2 part of ammonium persulfate used was continuously added to the polymerization system over the entire polymerization time as the polymerization proceeded. The composition of the polymer thus obtained is
AN56.0 weight%, MA1.3 weight%, VD40.6 weight%,
SSS was 2.1% by weight, and the yield of the polymer was 82.1%. Further, the specific viscosity was 0.341. In the polymer obtained by this polymerization method, Y is
Since the polymer aqueous solution was 87.6%, the aqueous polymer solution was extremely stable, and the water content of the water-containing resin obtained by salting out was as good as 118.2%. In addition, the synthetic fiber obtained by dissolving this polymer in dimethylformamide to make a 24% spinning stock solution and spinning it in a 60% dimethylformamide aqueous solution has a Y-X value of
15.6%, the transmittance was 86.6%, and the devitrification prevention property was excellent, and the flame retardancy was also good with an oxygen index value of 30.5. Examples 15 to 20 Comparative Example 9 Solution polymerization was carried out using a pressure-resistant polymerization reactor with an internal volume of 15, and the time to start or end the addition of the sulfonic acid group-containing vinyl monomer to the polymerization system was changed to change Y-X. The effect of the value on devitrification prevention was investigated. The polymerization conditions were as follows: 58.5 parts of AN, 40.0 parts of VD, 92 parts of dimethylformamide as a solvent, 0.28 parts of azobisdimethylvaleronitrile as a polymerization initiator, reaction temperature: 50°C, polymerization time: 11 hours. During this polymerization, 1.5 parts of SSS as a sulfonic acid group-containing vinyl monomer was added between the start of polymerization and 11 hours after the end of polymerization, and an equal amount was continuously added until 11 hours after the end of polymerization. The addition was completed within the time. The composition of the obtained polymer was AN55-56% by weight,
VD was 41-43% by weight, SSS was 2.4-2.6% by weight, and the yield of the polymer was about 57-60%. Furthermore, dimethylformamide was added to these polymer solutions to
A 20% polymer solution was prepared again, and unreacted monomers were removed under operating conditions of 30 mmHg and 50°C to obtain a polymer solution with a spinning stock solution concentration of approximately 25%. This polymer solution was wet-spun in a 57% dimethylformamide aqueous solution, then stretched three times in a 30% dimethylformamide aqueous solution, washed and dried with water, further hot-stretched three times, and then A relaxation heat treatment was performed in this state. Table 3 shows the devitrification prevention and dyeability properties of the modacrylic synthetic fibers thus obtained.

[Table] Examples 15 to 20 all satisfied the conditions of the present invention, so they were excellent in preventing devitrification, and their dyeability was also good at 90% or higher. In addition, the flame retardance is good with an oxygen index value of 31 to 32, and the fiber physical properties are 3 denier yarn with a strength of 3.0 to 3.5 g/d and an elongation of 25 to 30.
%, and a well-balanced Young's modulus of 350 to 450 Kg/mm ² was obtained. However, in Comparative Example 9, in which polymerization was started after mixing AN, VD, and SSS, the devitrification property was relatively good, but the dyeing property was poor and it could not be put to practical use at all. Example 21 Solution polymerization was carried out using a pressure-resistant polymerization reactor having an internal volume of 30 mm. Polymerization conditions are AN61.5 parts, VD37.0
parts, 0.5 parts of SAS, 76 parts of dimethylformamide as a solvent, 0.21 parts of azobisdimethylvaleronitrile as a polymerization initiator, and a reaction temperature of 55 parts.
The polymerization was carried out at 10°C for 10 hours. During this polymerization, dissolved in 20 parts of dimethylformamide
A solution of 1.0 part of SSS was added from 3 hours after the start of polymerization (polymer yield 21.1%) to 4 hours after the start of polymerization (polymer yield 28.4%).
%) was continuously added to the polymerization system in equal amounts. The composition of the polymer thus obtained is
AN58.1wt%, VD39.7wt%, SSS1.6wt%,
The SAS was 0.6% by weight, and the yield of the polymer was 61.3%. Moreover, the specific viscosity was 0.368. The synthetic fiber obtained by removing unreacted monomers and wet spinning from this polymer solution under the same conditions as in Examples 15 to 20 has a Y-X value of 11.9%, so the transmittance is low.
It had an excellent devitrification prevention property of 85.5%, and also had excellent flame retardancy and dyeability, with an oxygen index value of 30.0 and a dye exhaustion rate of 94.6%.

Claims (1)

[Claims] 1. 40-65% by weight of acrylonitrile and 31-59.9% by weight
When polymerizing 0.1 to 4% by weight of vinyl monomer containing a sulfonic acid group that satisfies formula (2) with vinyl chloride and/or vinylidene chloride (wt%), the polymerization is performed under conditions that satisfy the following formula (1). A method for producing an acrylonitrile polymer. 0<Y−X<83 ...(1) Z ₁ /Z ₂ >1 ...(2) (wherein, , represents the percentage of the polymer formed at the end of the addition to the total polymer, and Z ₁ and Z ₂ represent the reactivity ratio of the sulfonic acid group-containing vinyl monomer and acrylonitrile, respectively.) 2 The following formula (3) 2. The method for producing an acrylonitrile polymer according to claim 1, wherein emulsion polymerization is carried out under conditions that satisfy (1). Y>71...(3)