N-vinyl lactam copolymers and compositions containing the copolymer.

Abstract

To provide an N-vinyl lactam copolymer designed for fiber applications that can confer enhanced hygroscopicity, and to provide a composition including the copolymer.SOLUTION: An N-vinyl lactam copolymer comprises an N-vinyl lactam monomer-derived structural unit (a) and a nitrile monomer-derived structural unit (b), and also comprises a phosphorus atom-containing compound-derived structural unit.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an N-vinyl lactam-based copolymer capable of imparting excellent hygroscopicity in fiber applications, a method for producing the same, a composition comprising the N-vinyl lactam-based copolymer, a method for producing the composition, and additionally a method for producing acrylic fibers or modacrylic fibers. [Background Art]

[0002] In recent years, driven by consumers' pursuit of hygiene and comfort, fibers are required to be imparted with functions such as hygroscopicity, antibacterial and deodorant properties, heat retention, heat generation, and flexibility, and various technologies have been developed. For example, as a method for imparting functionality to synthetic fibers, a technique of kneading a functional component in the fiberization process step has been developed. Methods for imparting functionality at the yarn or fabric stage after the fiberization process have also been developed, and such methods can be applied regardless of the type of fibers such as synthetic fibers and natural fibers. Patent Document 1 discloses a technique of imparting hand feeling and the like by coating fibers with a fiber treatment agent. Further, Patent Documents 2 and 3 disclose a resin composition for processing cellulosic substrates using a carboxyl group-containing polymer (A) and a polyvalent oxazoline compound (B). Patent Document 4 discloses a fiber treatment agent containing a polyhydric alcohol and a polycarboxylic acid. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2008-280652 [Patent Document 2] Japanese Unexamined Patent Publication No. 2000-129144 [Patent Document 3] Japanese Unexamined Patent Publication No. 2000-119968 [Patent Document 4] Japanese Unexamined Patent Publication No. 2016-79530 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] As mentioned above, various fiber treatment agents have been disclosed, but conventional fiber treatment agents lacked sufficient heat resistance during fiber processing and were not adequately compatible with hygroscopic properties, leaving room for improvement.

[0005] This disclosure has been made in view of the above-mentioned circumstances, and aims to provide an N-vinyl lactam copolymer that can impart excellent hygroscopic properties to textile applications, a method for producing the same, a composition containing the N-vinyl lactam copolymer, a method for producing the composition, and in addition thereto, a method for producing acrylic fibers or modacrylic fibers. [Means for solving the problem]

[0006] In other words, the N-vinyl lactam copolymer of this disclosure is This is an N-vinyllactam copolymer having structural units (a) derived from an N-vinyllactam monomer and structural units (b) derived from a nitrile monomer, and also having structural units derived from a phosphorus atom-containing compound. [Effects of the Invention]

[0007] According to this disclosure, an N-vinyl lactam copolymer that can impart excellent hygroscopic properties to textile applications, a method for producing the same, a composition containing the N-vinyl lactam copolymer, a method for producing the composition, and in addition thereto, a method for producing acrylic fibers or modacrylic fibers can be provided. [Modes for carrying out the invention]

[0008] The embodiments of this disclosure are described in detail below. The following description of preferred embodiments is illustrative in nature and is not intended to limit the disclosure, its applications, or its uses in any way.

[0009] In the following explanation, unless otherwise specified, "%" refers to "mass%".

[0010] [N-vinyl lactam copolymer] The N-vinyllactam copolymers of this disclosure are not particularly limited as they have structural units (a) derived from an N-vinyllactam monomer and structural units (b) derived from a nitrile monomer, and structural units derived from a phosphorus atom-containing compound.

[0011] The structural unit (a) derived from the N-vinyllactam monomer is not particularly limited as long as the monomer-derived structural unit is included as the structural unit (a) in the N-vinyllactam copolymer of this disclosure by polymerizing the N-vinyllactam monomer. In other words, an N-vinyllactam monomer is a precursor of a structural unit derived from an N-vinyllactam monomer. The aforementioned N-vinyllactam monomers are monomers having a cyclic lactam ring, and examples include N-vinyl-2-pyrrolidone, N-vinylcaprolactam, N-vinyl-4-butylpyrrolidone, N-vinyl-4-propylpyrrolidone, N-vinyl-4-ethylpyrrolidone, N-vinyl-4-methylpyrrolidone, N-vinyl-4-methyl-5-ethylpyrrolidone, N-vinyl-4-methyl-5-propylpyrrolidone, N-vinyl-5-methyl-5-ethylpyrrolidone, N-vinyl-5-propylpyrrolidone, N-vinyl-5-butylpyrrolidone, N-vinyl-4-methylcaprolactam, N-vinyl-6-methylcaprolactam, N-vinyl-6-propylcaprolactam, and N-vinyl-7-butylcaprolactam. Among these, N-vinyl-2-pyrrolidone and / or N-vinylcaprolactam are preferred because they exhibit good polymerizability, good color stability of the resulting polymer at high temperatures, and good solubility in solvents. One or more of the above N-vinyllactam monomers can be used.

[0012] The structural unit (b) derived from the nitrile monomer is not particularly limited as long as the monomer-derived structural unit is included as the structural unit (b) in the N-vinyl lactam copolymer of this disclosure by polymerizing the nitrile monomer. In other words, nitrile monomers are precursors to structural units derived from nitrile monomers. Examples of the aforementioned N-vinyl lactam monomers include (meth)acrylonitrile. Specifically, these include acrylonitrile and methacrylonitrile. Among these, acrylonitrile is preferred because of its good polymerizability.

[0013] The N-vinyl lactam copolymers of this disclosure are not particularly limited as long as they have structural units derived from a phosphorus atom-containing compound. The structural units derived from the phosphorus atom-containing compound can be introduced into the N-vinyllactam copolymer of this disclosure by, for example, using a phosphorus compound such as hypophosphorous acid (salt) as a chain transfer agent during the production of the N-vinyllactam copolymer of this disclosure, as described later.

[0014] The phosphorus atom is not particularly limited as long as it is included in the N-vinyllactam copolymer as a structural unit derived from the phosphorus atom-containing compound. Having a structural unit derived from the phosphorus atom-containing compound makes it possible to suppress discoloration (yellowing) when the N-vinyllactam copolymer is heated. Examples of structural units derived from the phosphorus atom-containing compound include hypophosphorous acid (salt) groups (meaning hypophosphorous groups or hypophosphorous bases), phosphite (salt) groups (meaning phosphite groups or phosphite bases), and it is preferable that at least one selected from the group consisting of these is included. More specifically, examples include phosphonic acid (salt) groups and phosphinic acid (salt) groups. Among these, phosphinic acid (salt) groups are preferred. That is, the N-vinyllactam copolymer of this disclosure may have phosphinic acid (salt) groups in its main chain.

[0015] Examples of the aforementioned salts include metal salts, ammonium salts and organic amine salts, with metal salts being preferred. Examples of metal salts include alkali metal salts such as lithium salts, sodium salts and potassium salts; alkaline earth metal salts such as calcium salts and magnesium salts; and transition metal salts; among which alkali metal salts are preferred. When the structural unit containing a phosphorus atom is a structural unit composed of a hypophosphorous acid group, a phosphorous acid group, or a metal base thereof, for example, after forming a hypophosphorous acid (salt) group and / or a phosphorous acid (salt) group in the main chain of the polymer, conversion to a desired acid or metal salt is also possible by adding an acid or a base. Similarly, conversion is also possible by treatment with an ion exchange resin or the like.

[0016] The N-vinyl lactam-based copolymer of the present disclosure essentially comprises a structural unit (a) derived from an N-vinyl lactam-based monomer and a structural unit (b) derived from a nitrile-based monomer. When the total amount of the N-vinyl lactam-based copolymer is 100% by mass, the content of the structural unit (a) is preferably 15 to 99% by mass, more preferably 40 to 98% by mass, still more preferably 70 to 97% by mass, even more preferably 73 to 96% by mass, and still even more preferably 78 to 92% by mass. When the content of the structural unit (a) falls within the aforementioned range, it is preferable from the viewpoint that excellent hygroscopicity can be imparted.

[0017] When the total amount of the N-vinyl lactam-based copolymer is 100% by mass, the content of the structural unit (b) is preferably 1 to 85% by mass, more preferably 2 to 60% by mass, still more preferably 3 to 30% by mass, even more preferably 4 to 27% by mass, and still even more preferably 8 to 22% by mass. When the content of the structural unit (b) falls within the aforementioned range, the copolymer of the present invention tends to easily remain in fibers during fiber production by wet spinning and when washing fiber products, which is preferable from the viewpoint of enabling efficient functional impartation. It is also preferable in that it can suppress the level of coloring (yellowing) when a composition with an acrylonitrile-based polymer is heated, and tends to suppress a decrease in molecular weight due to thermal decomposition.

[0018] In the N-vinyl lactam-based copolymer of the present disclosure having a structural unit derived from the phosphorus atom-containing compound, the content ratio of the structural unit derived from the phosphorus atom-containing compound is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass or more, based on 100% by mass of the total mass of the N-vinyl lactam-based copolymer of the present disclosure. Further, the content is preferably 10% by mass or less, more preferably 7% by mass or less, and still more preferably 6% by mass or less. By including the phosphorus atom-containing compound within the above range, for example, when the copolymer is used as a modifier for fibers or the like, yellowing under high temperature conditions can be suppressed, and a decrease in fiber strength can also be suppressed by suppressing a decrease in molecular weight due to thermal decomposition. In addition, when calculating the mass percentage of structural units derived from a phosphorus atom-containing compound relative to the total mass of the N-vinyl lactam-based copolymer of the present disclosure, if the case falls under the aforementioned circumstances, the calculation shall be performed in terms of sodium salt. The amount of the structural unit derived from the phosphorus atom-containing compound contained in the N-vinyl lactam-based copolymer of the present disclosure can be measured by the method described in the examples mentioned later.

[0019] The N-vinyllactam copolymers of this disclosure may include structural units (a) derived from N-vinyllactam monomers, structural units (b) derived from nitrile monomers, and structural units (e) derived from monomers other than those derived from phosphorus atom-containing compounds. Monomers that can serve as precursors to structural units derived from other monomers include, specifically, carboxyl group-containing monomers other than (meth)acrylates, such as (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, 2-methylene glutaric acid, and their salts; hydroxyl group-containing alkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and α-hydroxymethylethyl (meth)acrylate; alkyl (meth)acrylates, which are esters of alkyl groups with 1 to 18 carbon atoms of (meth)acrylic acid, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; and alkyl (meth)acrylates such as methoxymethyl (meth)acrylate and methoxyethyl (meth)acrylate. Coxyalkyl (meth)acrylates; amino group-containing acrylates such as dimethylaminoethyl (meth)acrylate or its quaternary derivatives; amide group-containing monomers such as (meth)acrylamide, dimethylacrylamide, and isopropylacrylamide; vinyl esters such as vinyl acetate; alkenes such as ethylene and propylene; aromatic vinyl monomers such as styrene; maleimide derivatives such as maleimide, phenylmaleimide, and cyclohexylmaleimide; monomers having sulfonic acid groups such as 3-allyloxy-2-hydroxypropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid, and vinylsulfonic acid, and their salts; monomers having phosphonic acid groups such as vinylphosphonic acid and (meth)allylphosphonic acid; aldehyde group-containing vinyl monomers such as (meth)acrolein; alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and butyl vinyl ether; other functional group-containing monomers such as vinyl chloride, vinylidene chloride, and allyl alcohol;Examples include polyalkylene glycol chain-containing monomers such as polyalkylene glycol (meth)acrylate, monoalkoxy polyalkylene glycol (meth)acrylate, vinyl alcohol, (meth)allyl alcohol, and monomers having a structure in which 1 to 300 moles of alkylene oxide are added to unsaturated alcohols such as isoprenol; and others. These other monomers may be used individually or in combination of two or more. The notation for carboxylate salts, sulfonates, and phosphonates (salts) is the same as for the salts mentioned above. The same applies to preferred forms.

[0020] When the N-vinyl lactam copolymer of this disclosure contains the other structural unit (e), it is preferable that the content of structural unit (e) is 20% by mass or less, when the total amount of structural unit (a), structural unit (b), structural unit derived from the phosphorus atom-containing compound, and other structural unit (e) is 100% by mass. More preferably, it is 15% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less. Particularly preferably, it is 0% by mass.

[0021] The N-vinyllactam copolymers of this disclosure can be produced by the manufacturing method described later, and the resulting N-vinyllactam copolymers of this disclosure may be random copolymers, block copolymers, or graft copolymers depending on the manufacturing method. From the viewpoint of commercial production efficiency, random copolymers are preferred. Furthermore, if the N-vinyl lactam copolymer of this disclosure is a random copolymer, it is preferable in that the copolymer of the present invention tends to remain in the fibers during the production of fibers by wet spinning and when textile products are washed, thus enabling efficient functionalization.

[0022] The N-vinyl lactam copolymers of this disclosure are not particularly limited as long as their weight-average molecular weight is between 10,000 and 600,000. More preferably, they are between 50,000 and 450,000, even more preferably between 60,000 and 350,000, even more preferably between 70,000 and 300,000, and even more preferably between 80,000 and 250,000. The N-vinyl lactam copolymers of this disclosure are preferable if their weight-average molecular weight is 10,000 or more, as they tend to remain within the fibers during wet spinning fiber production and when textile products are washed, thus enabling efficient functionalization. Furthermore, if their weight-average molecular weight is 600,000 or less, they are preferable in that they offer excellent handling when dissolved in a solvent. The weight-average molecular weight of the N-vinyl lactam copolymer in this disclosure shall be the value measured by the method described in the examples below.

[0023] [Method for producing N-vinyl lactam copolymers] The method for producing an N-vinyl lactam copolymer according to this disclosure includes a polymerization step in which monomers to be used as raw materials are subjected to a polymerization reaction.

[0024] <Monomer components> As described above, the N-vinyllactam copolymers of this disclosure require structural units (a) derived from N-vinyllactam monomers, structural units (b) derived from nitrile monomers, and structural units derived from phosphorus atom-containing compounds. The monomer corresponding to the aforementioned structural unit (a) can be represented as monomer (A). Furthermore, the monomer corresponding to the aforementioned structural unit (b) can be represented as monomer (B). The monomer (A) and monomer (B) are as described above, and the same applies to the preferred form. Furthermore, the phosphorus-containing compounds that are precursors to structural units derived from phosphorus-containing compounds are as described above, and the same applies to the preferred form. Furthermore, if the N-vinyl lactam copolymer of this disclosure contains structural unit (e) derived from the other monomer, the monomer corresponding to the structural unit derived from the other monomer can be represented as monomer (E). The monomer (E) is as described above.

[0025] The monomers used in the polymerization step of the N-vinyl lactam copolymer of this disclosure are not particularly limited, as long as monomer (A) and monomer (B) are essential. When the total amount of monomer (A) and monomer (B) is 100% by mass, the content of monomer (A) is preferably 15 to 99% by mass. More preferably 40 to 98% by mass, even more preferably 70 to 97% by mass, even more preferably 73 to 96% by mass, and even more preferably 78 to 92% by mass. The proportion of monomer (A) used within the above range is preferable in that it can impart excellent hygroscopic properties.

[0026] When the total amount of monomer (A) and monomer (B) is 100% by mass, it is preferable that the content of monomer (B) is 1 to 85% by mass. More preferably, it is 2 to 60% by mass, even more preferably 3 to 30% by mass, even more preferably 4 to 27% by mass, and even more preferably 8 to 22% by mass. When the proportion of monomer (B) used is within the aforementioned range, the copolymer of the present invention tends to remain in the fibers during the production of fibers by wet spinning and when washing textile products, which is preferable in that it allows for efficient imparting of functionality. It is also preferable in that yellowing tends to be suppressed when producing compositions with acrylonitrile polymers.

[0027] The monomer used in the polymerization step of the N-vinyl lactam copolymer of this disclosure may be monomer (A) and other monomers (E) other than monomer (B). When using the aforementioned other monomer (E), if the total amount of monomer (A), monomer (B), and the other monomer (E) is 100% by mass, the amount of monomer (E) used is preferably 20% by mass or less. More preferably, it is 15% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less. Particularly preferably, it is 0% by mass.

[0028] Furthermore, when calculating the proportion of other monomers used in the total monomer components, if the other monomer has a salt of an acidic group, the salt of that acidic group shall be used as the corresponding acidic group (in acid terms), and if it has a salt of an amino group, the salt of that amino group shall be used as the corresponding amino group (in amine terms) in the calculation. Similarly, when calculating structures derived from other monomers relative to structural units derived from the total monomer components, when calculating structural units derived from other monomers relative to the total mass of the N-vinyllactam copolymer of this disclosure, the calculation shall be done in acid terms and amine terms, respectively, if applicable.

[0029] The N-vinyllactam copolymers of this disclosure can be produced by random polymerization, block polymerization, or graft polymerization using the monomer preparation method described above. From the viewpoint of commercial production efficiency, random polymerization is preferred for the N-vinyllactam copolymers of this disclosure. Furthermore, random copolymers are preferred because the copolymer of the present invention tends to remain in the fibers during the production of fibers by wet spinning and when textile products are washed, allowing for efficient impartment of functionality.

[0030] In the polymerization reaction during the production of the N-vinyl lactam copolymer according to this disclosure, the monomer components, polymerization initiators, etc., can be added to the reaction vessel by various methods. Suitable methods for adding the monomer components and polymerization initiators to the reaction vessel include: a method in which all of the monomer components are placed in the reaction vessel and copolymerization is carried out by adding the polymerization initiator to the reaction vessel; a method in which a portion of the monomer components are placed in the reaction vessel and copolymerization is carried out by continuously or stepwise (preferably continuously) adding the polymerization initiator and the remaining monomer components to the reaction vessel; a method in which the polymerization solvent is placed in the reaction vessel and the entire amount of monomer components and polymerization initiator is added; and a method in which a portion of the monomers are placed in the reaction vessel and copolymerization is carried out by continuously (preferably continuously) adding the polymerization initiator and the remaining monomer components to the reaction vessel. Among these methods, copolymerization is preferred by sequentially adding the polymerization initiator and monomer components to the reaction vessel, as this method can narrow the molecular weight distribution and composition distribution of the resulting copolymer and is expected to improve the dispersibility and / or compatibility with fibers when used as a modifier for fibers.

[0031] The method for adding monomer (A) and monomer (B) is preferably to continuously add each monomer component to the reactor. Furthermore, it is preferable that the addition of monomer (A) is completed in its entirety before that of monomer (B). It is preferable that monomer (A) is added in its entirety before monomer (B), as this improves the polymerization rate and narrows the compositional distribution.

[0032] <Radical polymerization initiator> In polymerization of the monomers, it is preferable to use a radical polymerization initiator. In the manufacturing method of this disclosure, and particularly in the polymerization step, it is preferable to use an azo polymerization initiator and / or an organic peroxide as the radical polymerization initiator. An azo polymerization initiator is a compound that has an azo bond and generates radicals upon heat or other means.

[0033] The azo polymerization initiators usable in this disclosure are not particularly limited, but include 2,2'-azobis-2-amidinopropane dihydrochloride, 2,2'-bis(2-imidazolin-2-yl)[2,2'-azobispropane] dihydrochloride, 2,2'-bis(2-imidazolin-2-yl)[2,2'-azobispropane] disulfate, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate dihydrate, 2,2'-azobis-(propane-2-carbamidin) dihydrochloride, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine], 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} dihydrochloride, and 2,2'-azobi Examples include su[2-(2-imidazolin-2-yl)propane], 2,2'-azobis(1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis[N-(2-hydroxyethyl)-2-methylpropanamide], 4,4'-azobis-4-cyanovaleric acid, azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), dimethyl2,2'-azobis(2-methylpropionate), etc. Among these, those with a 10-hour half-life temperature of 30°C to 90°C are preferred, and more preferably those with a 10-hour half-life temperature of 40°C to 70°C, because they tend to efficiently produce N-vinyl lactam polymers and the resulting polymers tend to have good color at high temperatures.Specifically, 2,2'-azobis-2-amidinopropane dihydrochloride, 2,2'-bis(2-imidazolin-2-yl)[2,2'-azobispropane] dihydrochloride, 2,2'-bis(2-imidazolin-2-yl)[2,2'-azobispropane] disulfate, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate dihydrate, 2,2'-azobis-(propane-2-carboamidine) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile) ), 2,2'-azobis(2-methylbutyronitrile), dimethyl-2,2'-azobis(2-methylpropionate) are preferred, 2,2'-azobis-2-amidinopropane dihydrochloride, 2,2'-bis(2-imidazolin-2-yl)[2,2'-azobispropane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate dihydrate, 2,2'-azobis(2,4-dimethylvaleronitrile) are more preferred, and 2,2'-azobis-2-amidinopropane dihydrochloride and 2,2'-azobis(2,4-dimethylvaleronitrile) are most preferred. Furthermore, azo polymerization initiators containing carboxyl groups (such as 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]) may adversely affect coloration, so if used as desired, it is preferable to use as little as possible, and even more preferable not to use them at all.

[0034] Examples of organic peroxides usable in this disclosure include alkyl hydroperoxides such as tert-butyl hydroperoxide, di-tert-butyl peroxide, cumene hydroperoxide, tert-hexyl hydroperoxide, and p-menthane hydroperoxide; tert-butyl peroxyacetate, disuccinoyl peroxide, and peracetic acid. Among these organic peroxides, those with a 10-hour half-life temperature of 30°C to 180°C are preferred, and those with a 10-hour half-life temperature of 40°C to 170°C are preferred.

[0035] The manufacturing method of this disclosure, particularly the radical polymerization initiator used in the polymerization step, preferably requires one or more selected from the azo polymerization initiator and the organic peroxide, but other radical polymerization initiators may also be used in combination. Examples of such initiators include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate, and hydrogen peroxide. The radical polymerization initiator used in the present invention is preferably the azo polymerization initiator described above.

[0036] The amount of radical polymerization initiator used (total amount if multiple types are used) is preferably 0.1% to 5% by mass relative to the total monomer components, unless otherwise specified. More preferably 0.15% to 3% by mass, even more preferably 0.2% to 1% by mass, and even more preferably 0.3% to 0.8% by mass. Using 0.1% by mass or more of the radical polymerization initiator is preferable because it tends to facilitate adjustment of the molecular weight of the polymer, reduces the amount of impurities, and suppresses discoloration during heating. Using 5% by mass or less of the radical polymerization initiator is also preferable because it can suppress discoloration caused by the reaction between radicals derived from the polymerization initiator and nitrile groups during the polymerization process.

[0037] There are no particular limitations on the method of adding the polymerization initiator to the reaction system (polymerization vessel), but it is preferable to add the polymerization initiator continuously or in steps. When adding the polymerization initiator continuously, the rate of addition may be varied.

[0038] The polymerization initiator may be added directly without dissolving in the solvent, but it is preferable to dissolve it in the solvent described later and then add it to the reaction system (polymerization vessel).

[0039] <Reducing agent> In the manufacturing method of the present disclosure, particularly in the polymerization step, a reducing agent may be used, for example, to adjust the molecular weight of the N-vinyllactam copolymer of the present disclosure. The usable reducing agents are not particularly limited, but include thiol compounds such as mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, octyl 3-mercaptopropionic acid, 2-mercaptoethanesulfonic acid, n-dodecyl mercaptan, octyl mercaptan, and butyl thioglycolate; halides such as carbon tetrachloride, methylene chloride, bromoform, and bromotrichloroethane; hydroxyl group-containing compounds other than the above alcohol compounds; phosphorous acid, phosphite, hypophosphorous acid, hypophosphite, and their hydrates; lower oxides and their salts such as sulfurous acid, bisulfite, dithionic acid, metabisulfite, and bisulfites (including compounds that dissolve in water to produce bisulfites). These salts are metal salts such as sodium, ammonium salts, or organic amine salts. Two or more of the above reducing agents may be used. Reducing the amount of metal salts such as sodium salts is preferable when used in special industrial applications such as the manufacture of hollow fiber membranes, or in electrical materials applications such as semiconductor cleaning.

[0040] <Chain movement agent> The polymerization step is preferably carried out in the presence of a phosphorus atom-containing compound. By chain transfer to the phosphorus atom-containing compound, substituents containing phosphorus atoms can be efficiently introduced into the N-vinyl lactam copolymer of this disclosure. Furthermore, low molecular weight can be efficiently achieved. Examples of phosphorus atom-containing compounds and preferred embodiments thereof include hypophosphorous acid (salt), phosphorous acid (salt), phosphoric acid (salt), hypophosphorous acid esters, phosphorous acid esters, and phosphate esters, unless otherwise specified. Due to their high chain transfer efficiency, hypophosphorous acid (salt), phosphorous acid (salt), and hypophosphorous acid esters are preferred, with hypophosphorous acid (salt) being more preferred. When using phosphorus atom-containing compounds, one type or two or more types may be used.

[0041] In the polymerization step, the amount of the phosphorus atom-containing compound used is preferably 0.1 mg to 100 mg, more preferably 0.5 mg to 70 mg, and even more preferably 1 mg to 60 mg, per 1 g of monomer (total monomer) used. Note that if the phosphorus atom-containing compound is a salt, the above range is calculated using the mass of the corresponding sodium salt. For example, if it is ammonium hypophosphate, the mass is calculated using the corresponding sodium salt, sodium hypophosphate. The method of adding the phosphorus atom-containing compound to the reaction system (polymerization vessel) is not particularly limited, but it is preferable to add 20% by mass or more of the total amount of phosphorus atom-containing compound to the reaction system (polymerization vessel) before adding the monomer components. More preferably, it is 30% by mass or more, and even more preferably 40% by mass or more. By adding 20% ​​by mass or more of the total amount of phosphorus atom-containing compound to the reaction system (polymerization vessel) before adding the monomer components, the phosphorus atom-containing compound can be efficiently introduced into the polymer.

[0042] The polymerization step may optionally use a chain transfer agent other than the phosphorus atom-containing compound (hereinafter also referred to as "other chain transfer agents"). Examples of other chain transfer agents include thiol-based chain transfer agents such as mercaptoethanol and mercaptopropionic acid; halides such as carbon tetrachloride and methylene chloride; secondary alcohols such as isopropyl alcohol and glycerin; sulfites such as sodium sulfite; bisulfites such as sodium bisulfite; dithionites such as sodium dithionite; and pyrosulfites such as potassium pyrosulfite. When using the above-mentioned other chain transfer agents, they may be used alone or in combination of two or more.

[0043] <Reducible Compounds> In the manufacturing method of the present disclosure, particularly in the polymerization step, heavy metal ions (or heavy metal salts) may be used as reducing compounds that act as decomposition catalysts for polymerization initiators. In the present invention, heavy metals have a specific gravity of 4 g / cm³. 3This refers to the metals mentioned above. Among heavy metals, iron and / or copper are preferred, and as the reducing compound, heavy metal salts such as Mohr's salt (Fe(NH4)2(SO4)2·6H2O), ferrous sulfate heptahydrate, ferrous chloride, ferric chloride, copper(I) sulfate and / or its hydrate, copper(II) sulfate and / or its hydrate, copper(II) chloride and / or its hydrate may be used.

[0044] When using the aforementioned heavy metal ions, they can be used in a range of, for example, 0.1 to 10 ppm. However, it is preferable not to use them in special industrial applications such as the manufacture of hollow fiber membranes or in electrical materials applications such as semiconductor cleaning.

[0045] <Other additives> In the manufacturing method of this disclosure, particularly in the polymerization step, ammonia and / or amine compounds may be used for purposes such as promoting the polymerization reaction and preventing hydrolysis of N-vinyl lactam. Ammonia and amine compounds function as co-catalysts in the polymerization reaction. That is, when ammonia and / or amine compounds are included in the reaction system, the polymerization reaction proceeds even more rapidly compared to when they are not included. They can also function as basic pH adjusters. However, since ammonia causes odor and also affects coloration, it is preferable to use it in small amounts. When using ammonia, it may be used as a gaseous element at room temperature, or as an aqueous solution (ammonia water). The addition of ammonia and / or amine compounds can be carried out by any appropriate method; for example, they may be added to the reaction vessel from the beginning of polymerization, or they may be added sequentially to the reaction vessel during polymerization.

[0046] Any suitable amine compound can be used as the amine compound. Specifically, primary amines, secondary amines, and tertiary amines are examples. There may be only one amine or two or more of the above amines.

[0047] Examples of the primary amines include monoethanolamine, allylamine, isopropylamine, diaminopropylamine, ethylamine, 2-ethylhexylamine, 3-(2-ethylhexyloxy)propylamine, 3-ethoxypropylamine, 3-(diethylamino)propylamine, 3-(dibutylamino)propylamine, tetramethylethylenediamine, t-butylamine, sec-butylamine, propylamine, 3-(methylamino)propylamine, 3-(dimethylamino)propylamine, and 3-methoxypropylamine. One primary amine may be used, or two or more may be used in combination.

[0048] Examples of the aforementioned secondary amines include aliphatic secondary amines such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, N-methylethylamine, N-methylpropylamine, N-methylisopropylamine, N-methylbutylamine, N-methylisobutylamine, N-methylcyclohexylamine, N-ethylpropylamine, N-ethylisopropylamine, N-ethylbutylamine, N-ethylisobutylamine, N-ethylcyclohexylamine, N-methylvinylamine, and N-methylallylamine; N-methylethylenediamine, N-ethylethylenediamine, N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N-methyltrimethylenediamine, N-ethyltrimethylenediamine, and N,N'-dimethyltrimethylenediamine. Examples include aliphatic diamines and triamines such as amines, N,N'-diethyltrimethylenediamine, diethylenetriamine, and dipropylenetriamine; aromatic amines such as N-methylbenzylamine, N-ethylbenzylamine, N-methylphenethylamine, and N-ethylphenethylamine; monoalkanolamines such as N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-isopropylethanolamine, N-butylethanolamine, and N-isobutylethanolamine; dialkanolamines such as diethanolamine, dipropanolamine, diisopropanolamine, and dibutanolamine; and cyclic amines such as pyrrolidine, piperidine, piperazine, N-methylpiperazine, N-ethylpiperazine, morpholine, and thiomorpholine. One of the above secondary amines may be used, or two or more may be used in combination. Among these secondary amines, dialkanolamines and dialkylamines are preferred, dialkanolamines are more preferred, and diethanolamine is particularly preferred.

[0049] Examples of the tertiary amines include trialcanolamines such as trimethylamine, triethylamine, tripropylamine, triisopropylamine, triethanolamine, tripropanolamine, triisopropanolamine, and tripbutanolamine. One or more of these tertiary amines may be used. Among these tertiary amines, trialcanolamines are preferred, and triethanolamine is particularly preferred.

[0050] When using the aforementioned ammonia and amine compounds, the total amount used is preferably 0.01 parts by mass or more, and more preferably 0.02 to 1 part by mass, per 100 parts by mass of N-vinyllactam. Within this range, the reaction rate tends to improve, and the hydrolysis and discoloration of N-vinyllactam due to the decrease in pH during the reaction are suppressed.

[0051] Furthermore, when a copper salt is used as the heavy metal salt, and ammonia is also used, a copper ammine complex salt may be formed. Examples of copper ammine complex salts include diamminecopper salt ([Cu(NH3)2]2SO4·H2O, [Cu(NH3)2]Cl, etc.) and tetraamminecopper salt ([Cu(NH3)4]SO4·H2O, [Cu(NH3)4]Cl2, etc.).

[0052] <Polymerization solvent> The polymerization step is preferably carried out in the presence of a solvent. Examples of solvents include one or more selected from water, methyl alcohol, ethyl alcohol, isopropyl alcohol (2-propanol), n-butyl alcohol, diethylene glycol, and other alcohols. Water and isopropyl alcohol are preferred solvents. Water is more preferred. Since the nitrile monomer has low solubility in water, polymerization reactions can be easily carried out using organic solvents. However, the N-vinyl lactam copolymer of this disclosure is preferably dried after the polymerization process and handled as a powder. When organic solvents are used in the polymerization process, explosion-proof equipment is required for the drying process. When water is used in the polymerization process, explosion-proof equipment is not required, and the cost of capital investment can be reduced. Furthermore, even when organic solvents are used in the polymerization process and then replaced with water, the process time is extended. Therefore, when water is used, there is no need to replace the solvent, and productivity can be improved. The amount of solvent used is preferably 40 to 1000% by mass per 100% by mass of monomer.

[0053] The polymerization process is preferably carried out such that the solid content concentration (the concentration of non-volatile components in the solution) after polymerization is 10 to 80% by mass, more preferably 15 to 70% by mass, and even more preferably 20 to 60% by mass, relative to 100% by mass of the polymerization solution.

[0054] <Other polymerization conditions> The polymerization temperature is preferably 50°C or higher, more preferably 60 to 105°C, and even more preferably 65 to 95°C. When the polymerization temperature is within the above range, the amount of residual monomer components tends to decrease, and the performance tends to be efficiently realized. It should be noted that the polymerization temperature does not need to be kept constant throughout the polymerization reaction. For example, polymerization may be started from room temperature, and the temperature may be raised to the set temperature at an appropriate heating time or rate, and then the set temperature may be maintained thereafter. Alternatively, the polymerization temperature may be varied over time (raised or decreased) during the polymerization reaction, depending on the dropwise addition method of monomer components and initiators.

[0055] Regarding the pH during polymerization, from the viewpoint of suppressing the generation of impurities or by-products, a pH of 5 or higher is preferred, 6 or higher is more preferred, and 11 or lower is preferred.

[0056] The pressure within the reaction system may be at normal pressure (atmospheric pressure), under reduced pressure, or under pressurized pressure. However, in terms of the molecular weight of the resulting polymer, it is preferable to carry out the reaction under normal pressure or under pressurized pressure with the reaction system sealed. Furthermore, in terms of equipment such as pressurizing and depressurizing devices, pressure-resistant reaction vessels, and piping, it is preferable to carry out the reaction under normal pressure (atmospheric pressure). The atmosphere within the reaction system may be an air atmosphere, but an inert atmosphere is preferred. For example, it is preferable to replace the system with an inert gas such as nitrogen before the start of polymerization.

[0057] The polymerization time is preferably 30 minutes or more and 5 hours or less. Longer polymerization times tend to increase the coloration of the polymerization solution. After polymerization is complete, a maturation step (a step of holding the polymer under heating and temperature control conditions) may be included to reduce the amount of monomers remaining in the polymerization solution. The maturation time is usually 1 minute or more and 4 hours or less. In this invention, "polymerization time" refers to the time during which monomers are added, unless otherwise specified. Adding a polymerization initiator (booster) during the maturation time is preferable because it can further reduce the amount of monomers remaining in the polymerization solution.

[0058] In the later stages of polymerization, it is preferable to make the completion time of initiator addition the same as, or later than, the completion time of monomer addition, because this can reduce the amount of monomer remaining in the polymerization solution.

[0059] <Addition of organic acids> In this disclosure, an organic acid or an aqueous solution thereof may be added to the reaction solution after the polymerization reaction is complete (hereinafter also referred to as the organic acid addition step). In this case, it is preferable to maintain the reaction temperature at which the polymerization reaction occurred. This allows the remaining N-vinyl lactam to be hydrolyzed by the acid, thereby reducing the amount of unreacted monomer (i.e., the amount of monomer remaining in the reaction solution). For example, if the monomer is N-vinyl-2-pyrrolidone, it will be hydrolyzed to 2-pyrrolidone by the acid.

[0060] Preferred organic acids that can be used to reduce the amount of residual monomer are carboxylic acids having a boiling point higher than the reaction solution temperature at the time of organic acid addition (e.g., 100°C or higher). Specifically, examples include formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, aspartic acid, citric acid, glutamic acid, fumaric acid, malic acid, maleic acid, phthalic acid, trimellitic acid, pyromellitic acid, etc. These organic acids may be used individually or in combination of two or more.

[0061] The amount of organic acid used can be adjusted appropriately according to the amount of N-vinyl lactam used during the polymerization reaction and is not particularly limited, but for example, the pH of the reaction solution after polymerization should preferably be 5 or less, more preferably 3 or more and 4 or less. Specifically, the amount of organic acid used is preferably 100 ppm or more and 30,000 ppm or less, more preferably 500 ppm or more and 20,000 ppm or less, relative to the amount of N-vinyl lactam used.

[0062] <Residual monomer amount> The method for producing N-vinyllactam copolymers according to this disclosure is preferable because it allows for a reduction in the amount of unreacted monomers remaining. The amount of remaining monomers is preferably 200 ppm or less relative to the obtained N-vinyllactam polymer of this disclosure. More preferably 100 ppm or less, even more preferably 50 ppm or less, and particularly preferably 10 ppm or less. When the amount of remaining monomers is within the above range, it is preferable because the amount of impurities is low, discoloration during heating is suppressed, and odor tends to be suppressed. Furthermore, since remaining monomers are easily soluble in the electrolyte solvent and there is a concern that they may impair battery performance, reducing the amount of remaining monomers is preferable because it does not impair battery performance.

[0063] <Amount of impurities derived from monomers> The method for producing N-vinyllactam copolymers according to this disclosure is preferable because it allows for a reduction in the amount of monomer-derived impurities. For example, if the monomer is N-vinyl-2-pyrrolidone, the monomer-derived impurity is 2-pyrrolidone. The amount of monomer-derived impurities is preferably 5000 ppm or less relative to the obtained N-vinyllactam polymer of this disclosure. More preferably, it is 3000 ppm or less, even more preferably 2000 ppm or less, and particularly preferably 1500 ppm or less. A monomer-derived impurity within the aforementioned range is preferable because it tends to suppress discoloration during heating and odor. Furthermore, since impurities are easily soluble in the electrolyte solvent and can impair battery performance, reducing the amount of impurities is preferable because it does not impair battery performance.

[0064] <Drying process> To obtain an N-vinyllactam copolymer from the N-vinyllactam copolymer solution obtained in the polymerization step, a drying step may be performed. The drying step is a step that involves powdering, and also includes a grinding step. Drying and grinding can be carried out by known general methods, for example, powder can be obtained by spray drying, freeze drying, fluidized bed drying, drum drying, belt drying, etc. When heating and drying at atmospheric pressure, the drying temperature is preferably around 100 to 250°C and the drying time is preferably around 0.2 to 180 minutes. When drying under reduced pressure, the drying temperature should be appropriately selected according to the degree of reduced pressure. When drying an N-vinyllactam copolymer solution with a weight-average molecular weight of 600,000 or less, spray drying is preferred.

[0065] <Other processes> The manufacturing method of this disclosure requires a polymerization step and may optionally include the organic acid addition step, drying step, etc., but may also optionally include other steps. For example, it may include a purification step, desalting step, concentration step, dilution step, pH adjustment step, etc. The color tone of the resulting N-vinyllactam copolymer solution can be improved by treating the reaction solution (polymerization solution) with a cation exchange resin. The step of treating with a cation exchange resin can be carried out during polymerization (in parallel with the polymerization step) or after polymerization. Treatment with a cation exchange resin during the polymerization reaction can be carried out by any suitable method. Preferably, it is carried out by adding a cation exchange resin to the reaction vessel in which the polymerization reaction of monomer components is taking place. Specifically, for example, a method can be used in which a cation exchange resin is added to the reaction vessel in which the polymerization reaction is taking place, finely suspended, and then filtered. Any suitable time can be adopted for the treatment with the cation exchange resin. Preferably, it is 1 minute to 24 hours, more preferably 3 minutes to 12 hours, and even more preferably 5 minutes to 2 hours. The manufacturing method disclosed herein does not have to include any of the above-mentioned other steps, but may include one or more of them.

[0066] [Composition] The compositions of this disclosure include structural units (a) derived from N-vinyllactam monomers, and An N-vinyl lactam copolymer having structural units (b) derived from nitrile monomers and structural units derived from phosphorus atom-containing compounds, When the total amount of all structural units is taken as 100% by mass, the composition is not particularly limited as long as it contains an acrylonitrile copolymer that contains 35% by mass or more of structural units derived from acrylonitrile.

[0067] The acrylonitrile copolymers of this disclosure are not particularly limited as long as they contain 35% by mass or more of structural units derived from acrylonitrile, when the total amount of all structural units is considered to be 100% by mass. The acrylonitrile copolymers of this disclosure are copolymers obtained by copolymerizing acrylonitrile (monomer) with other monomers. However, the copolymer has a content of 0% by mass or more and less than 15% by mass of the N-vinyllactam monomer. Examples of the aforementioned other monomers include methyl acrylate and sulfonic acid group-containing vinyl monomers. As the sulfonic acid group-containing vinyl monomer, methacrylic sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, isoprene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and metal salts and amine salts of these, such as their sodium salts, can be used. The sulfonic acid group-containing vinyl monomer may be used individually or in combination of two or more types. Furthermore, if flame retardancy is to be imparted, vinyl chloride and vinylidene chloride may be used as monomers to form the acrylonitrile copolymer of this disclosure. When an acrylonitrile copolymer of the present disclosure containing 35% by mass or more and less than 85% by mass of structural units derived from acrylonitrile is processed into fibers, it can be called modacrylic fiber, and when a copolymer containing 85% by mass or more of structural units derived from acrylonitrile is processed into fibers, it can be called acrylic fiber.

[0068] As described above, the acrylonitrile copolymers of this disclosure are not particularly limited as long as they contain 35% by mass or more of structural units derived from acrylonitrile, when the total amount of all structural units is considered to be 100% by mass. More preferably, they contain 45% by mass or more, even more preferably 70% by mass, and particularly preferably 85% by mass or more. When the structural units derived from acrylonitrile in the acrylonitrile copolymer of this disclosure are within the aforementioned range, it is preferable in that the resulting fibers have good strength, good process passability in the spinning process, and produce high-quality spun yarn.

[0069] The compositions of this disclosure are not particularly limited, as they must include the N-vinyl lactam copolymer and the acrylonitrile copolymer, and may also include other polymers, additives, solvents, etc. When the total amount of the composition disclosed herein is 100% by mass, the mass ratio of the N-vinyl lactam copolymer to the acrylonitrile copolymer is preferably 0.1:99.9 to 30:70. More preferably 1:99 to 25:75, even more preferably 2:98 to 20:80, even more preferably 3:97 to 15:85, and even more preferably 4:96 to 12:88.

[0070] [Method for producing acrylic fibers or modacrylic fibers] The method for producing acrylic fibers or modacrylic fibers according to this disclosure is not particularly limited as long as it includes the following two steps. Step 1) A step to prepare a composition solution by dissolving an N-vinyllactam copolymer having structural units (a) derived from an N-vinyllactam monomer and structural units (b) derived from a nitrile monomer, and structural units derived from a phosphorus atom-containing compound, and an acrylonitrile copolymer containing 35% by mass or more of structural units derived from acrylonitrile when the total amount of all structural units is 100% by mass, in a solvent. Step 2) A step of bringing the composition solution into contact with another liquid other than the solvent.

[0071] Step 1) in this disclosure is a step of dissolving the N-vinyl lactam copolymer and the acrylonitrile copolymer in a solvent to obtain a composition solution. The dissolution method is not particularly limited and can be carried out by various methods of the public art. The solvent refers to a liquid that can dissolve the N-vinyl lactam copolymer and the acrylonitrile copolymer at a liquid temperature of 20°C. Examples of the aforementioned solvents include dimethyl sulfoxide, dimethylacetamide, and dimethylformamide. Among these, dimethyl sulfoxide solvent is preferred because it offers excellent spinning performance during wet spinning.

[0072] Step 2) in this disclosure is a step of bringing the composition solution prepared in Step 1) into contact with a liquid other than the solvent. As a result of going through step 2) above, solid matter precipitates. This can be used to obtain the acrylic fibers or modacrylic fibers of this disclosure by wet spinning.

[0073] The other liquid used in step 2) refers to a solvent in which the acrylonitrile copolymer has low solubility at a liquid temperature of 20°C and can be precipitated. Other liquids besides the aforementioned solvents include aqueous solutions of dimethyl sulfoxide, dimethylacetamide, and dimethylformamide. Among these, an aqueous solution of the solvent used in step 1) is preferred because it is easy to reuse after recovery.

[0074] Furthermore, the acrylic or modacrylic fibers of this disclosure can be obtained by wet spinning and then moist heat treatment in step 2) using the composition solution prepared in step 1).

[0075] [Applications of N-vinyl lactam copolymers] The N-vinyl lactam copolymers and / or compositions of the present disclosure can be used in a variety of applications, including, but are not particularly limited, as manufacturing aids for hollow fiber membranes, cleaning agents for semiconductors, additives for adhesives and sealants, manufacturing aids for electronic components, detergent additives, cosmetic additives, thickeners, ink additives, pigment dispersants, dispersants for positive and negative electrode materials for batteries, dispersants for inorganic particles, hydrophilic agents, additives for paint compositions, surface treatment agents, resin modifiers, binders for inorganic substances, ceramic binders, additives for inorganic compositions, fiber treatment agents, and additives for functional fibers. In particular, when used in combination with various fibers, it exhibits excellent heat resistance during fiber processing, minimal discoloration, and superior performance as a moisture-absorbing agent for various fibers, making it preferable. [Examples]

[0076] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "percent mass".

[0077] <Measurement of weight-average molecular weight (GPC)> Equipment: HLC-8320GPC manufactured by Tosoh Corporation Detector: RI Columns: Showa Denko Corporation Shodex KD-806M (2 connected in series), KD-G 4A Column temperature: 40℃ Flow rate: 0.8ml / min Calibration curve: Created using a cubic equation based on Mp and elution time, using Polystyrene Standards (Mp = 3,242,000, 990,500, 483,400, 215,000, 74,800, 10,110). Eluent: N,N-dimethylformamide (containing 0.1% LiBr).

[0078] <Analysis of phosphorus atom-containing compound content (ion chromatography)> The phosphorus atom content of the compound was determined by ion chromatography under the following conditions. Equipment: IC-2010 manufactured by Tosoh Corporation Detector: Conductivity detector Column: Shodex ICSI-904E Guard column: Shodex ICSI-90 Column temperature: 25℃ Eluent: 0.1% by mass sodium bicarbonate aqueous solution Flow rate: 1.2mL / min Injection volume: 100μL This measurement allowed us to calculate the amount of unreacted phosphorus-containing compound and subtract it from the added amount to determine the proportion of structural units derived from the phosphorus-containing compound in the molecule.

[0079] <Heat resistance yellowing test (YI) of copolymers> Each copolymer was dried in a vacuum dryer at 50°C for 12 hours, then heated at 260°C under a nitrogen atmosphere for 60 minutes, and air-cooled in a desiccator. After grinding the obtained samples, YI was calculated using a colorimeter under the following conditions and the formula described in JIS K7373. Equipment: “Color difference meter SE-2000” manufactured by Nippon Denshoku Kogyo Co., Ltd. Method: Samples before and after heating are placed in a quartz cell and measured in "reflection mode" under light shielding. Based on the YI results obtained, the following conclusions were reached. ◎: Less than YI25 ○: YI25 or higher and less than 30 △: YI30 or more and less than 40 ×: YI40 or higher

[0080] <Heat resistance of copolymers> The weight-average molecular weight of the copolymer was measured before and after the heat resistance yellowing test, and the heat resistance of the copolymer was evaluated using the following formula. Heat resistance=Mw2 / Mw1 Mw1: Weight-average molecular weight (before the heat resistance yellowing test of the copolymer) Mw2: Weight-average molecular weight (after heat resistance yellowing test of copolymer) Based on the heat resistance results obtained, the following conclusions were reached. ◎: Heat resistance of 0.97 or higher ○: Heat resistance of 0.93 or higher and less than 0.97 △: Heat resistance of 0.85 or higher and less than 0.93 ×: Heat resistance less than 0.85

[0081] <Hygroscopic properties of copolymers> The mass (X) of the copolymer was measured after drying at 110°C for 2 hours. Subsequently, the mass (Y) of the copolymer was measured after standing for 24 hours in an environment adjusted to 20°C and 65% RH. Then, the mass (Z) of the copolymer was measured after standing for 24 hours in an environment adjusted to 30°C and 90% RH. The moisture absorption rate of the copolymer was calculated using the following formula. Moisture absorption rate (%)={(ZX) / X-(YX) / X}×100 Based on the obtained moisture absorption rate results, the following conclusions were reached. ◎:Moisture absorption rate 25% or more ○: Moisture absorption rate of 20% or more but less than 25% △: Moisture absorption rate 15% or more but less than 20% ×: Moisture absorption rate less than 15%

[0082] <Measuring the b* value of film> Equipment: “Color difference meter SE-2000” manufactured by Nippon Denshoku Kogyo Co., Ltd. Measurement mode: Transmission

[0083] <Hygroscopic properties of resin compositions> The moisture absorption rate of the resin composition was calculated using the same procedure as the hygroscopicity test for the copolymer, except that the resin composition was used instead of the copolymer. Compared to the case without copolymer addition, the degree of improvement in moisture absorption rate was determined as follows. ◎: Improvement in moisture absorption rate of 1% or more ×: Improvement in moisture absorption rate is less than 1%

[0084] <Manufacturing Example 1> In a 2.5L stainless steel reaction vessel equipped with a reflux condenser, stirrer, nitrogen inlet tube, and temperature sensor, 143.0g of deionized water, 31.1g of 5% by weight sodium hypophosphate monohydrate aqueous solution (hereinafter referred to as "5% SHP"), and 2.2g of 1% by weight sodium hydroxide aqueous solution (hereinafter referred to as "1% NaOH") were charged, and the mixture was heated to 71°C while stirring under a nitrogen atmosphere. Next, while stirring, 79.9 g of N-vinylpyrrolidone (hereinafter referred to as "NVP") was added to the polymerization reaction system at 71°C in two stages: 30 minutes followed by 319.6 g over 150 minutes. 8.2 g of 9% by weight 2,2'-azobis(2,4-dimethylvaleronitrile) 2-propanol solution (hereinafter referred to as "9%V-65") was added in two stages: 30 minutes followed by 24.7 g over 180 minutes. 31.1 g of 5% SHP was added over 180 minutes, 215.8 g of deionized water over 210 minutes, and 44.4 g of acrylonitrile (hereinafter referred to as "AN") was added from the tip nozzle through separate supply channels for 200 minutes, starting 10 minutes after the start of NVP addition. The addition of AN, 5% SHP, and deionized water was carried out continuously at a constant dropping rate. Furthermore, the addition of all components except AN was started simultaneously with the addition of NVP. After the addition of AN was completed, the reaction solution was maintained at 71°C for another 60 minutes (aged) to complete the polymerization. After the polymerization was complete, 100.0 g of deionized water was added dropwise to the reaction solution with stirring to obtain an aqueous copolymer solution (A-1). The aqueous copolymer solution (A-1) was dried under reduced pressure in a vacuum dryer at 90°C, and the dried material was then pulverized in a lab mill to obtain copolymer powder (A-2). The weight-average molecular weight of the obtained copolymer powder (A-2) was 188,000. In addition, the content of unreacted sodium hypophosphite (anhydrous) in the powder was 1581 ppm, so the content of sodium hypophosphite (anhydrous) in the copolymer was 4230 ppm.

[0085] <Manufacturing Example 2> In a 2.5L stainless steel reaction vessel equipped with a reflux condenser, stirrer, nitrogen inlet tube, and temperature sensor, 179.9g of deionized water, 34.9g of 4% SHP, and 2.8g of 1% NaOH were charged, and the mixture was heated to 71°C while stirring under a nitrogen atmosphere. Then, while stirring, 100.6g of NVP was added to the polymerization reaction system at 71°C in two stages: over 30 minutes followed by 402.2g over 150 minutes. 10.3g of 9% V-65 was added in two stages: over 30 minutes followed by 24.2g over 180 minutes. 34.9g of 4% SHP was added for 180 minutes, 294.8g of deionized water for 210 minutes, and 55.9g of AN for 200 minutes starting 10 minutes after the start of NVP addition, each substance was added dropwise through separate supply routes via a tip nozzle. AN, 4% SHP, and deionized water were added dropwise continuously at a constant dropping rate. The addition of all components except AN was started simultaneously with the addition of NVP. After the addition of AN was completed, the reaction solution was held (aged) at 71°C for another 60 minutes, after which 109.1 g of 5% by weight malonic acid aqueous solution (hereinafter referred to as "5% malonic acid") and 10.9 g of deionized water were added. After this, the solution was held (aged) at 71°C for another 60 minutes to complete the polymerization. After the polymerization was completed, 239.5 g of deionized water was added dropwise to the reaction solution with stirring to obtain copolymer aqueous solution (B-1). The copolymer aqueous solution (B-1) was dried under reduced pressure in a vacuum dryer at 90°C, and then the dried material was pulverized in a lab mill to obtain copolymer powder (B-2). The weight-average molecular weight of the obtained copolymer powder (B-2) was 234,000. Furthermore, the amount of unreacted sodium hypophosphite (anhydrous) contained in the powder was 1757 ppm, so the amount of sodium hypophosphite (anhydrous) in the copolymer was 2393 ppm.

[0086] <Manufacturing Example 3> In a 2.5L stainless steel reaction vessel equipped with a reflux condenser, stirrer, nitrogen inlet tube, and temperature sensor, 157.6g of deionized water, 30.3g of 5% SHP, and 2.2g of 1% NaOH were charged, and the mixture was heated to 71°C under a nitrogen atmosphere while stirring. Then, while stirring, 88.1g of NVP was added to the polymerization reaction system at 71°C in two stages: 30 minutes followed by 303.3g for 155 minutes, 9.1g of 9% V-65 in two stages: 30 minutes followed by 21.2g for 180 minutes, 30.3g of 5% SHP for 185 minutes, 250.1g of deionized water for 210 minutes, and 97.8g of AN for 200 minutes starting 10 minutes after the start of NVP addition, each substance was added dropwise through separate supply routes via a tip nozzle. AN, 5% SHP, and deionized water were added dropwise continuously at a constant dropping rate. The addition of all components except AN was started simultaneously with the addition of NVP. After the addition of AN was complete, the reaction solution was maintained (aged) at 71°C for another 60 minutes to complete the polymerization. After polymerization was complete, 110.0 g of deionized water was added dropwise to the reaction solution with stirring to obtain an aqueous copolymer solution (C-1). This aqueous copolymer solution (C-1) was dried under reduced pressure in a vacuum dryer at 90°C, and the dried material was then pulverized using a lab mill to obtain copolymer powder (C-2). The weight-average molecular weight of the obtained copolymer powder (C-2) was 203,000. The content of unreacted sodium hypophosphite (anhydrous) in the powder was 1181 ppm, resulting in a sodium hypophosphite (anhydrous) content in the copolymer of 3966 ppm.

[0087] <Manufacturing Example 4> In a 2.5L stainless steel reaction vessel equipped with a reflux condenser, stirrer, nitrogen inlet tube, and temperature sensor, 159.1g of deionized water, 43.2g of 4% SHP, and 2.2g of 1% NaOH were charged, and the mixture was heated to 71°C while stirring under a nitrogen atmosphere. Subsequently, while stirring, 88.9g of NVP was added to the polymerization reaction system at 71°C in two stages: 30 minutes followed by 306.2g for 155 minutes. 9.1g of 9% V-65 was added in two stages: 30 minutes followed by 21.4g for 180 minutes. 43.2g of 4% SHP was added for 185 minutes, 228.0g of deionized water for 210 minutes, and 98.8g of AN for 200 minutes starting 10 minutes after the start of NVP addition, each substance was added dropwise through separate supply routes via a tip nozzle. AN, 4% SHP, and deionized water were added dropwise continuously at a constant dropping rate. The addition of all components except AN was started simultaneously with the addition of NVP. After the addition of AN was completed, the reaction solution was maintained (aged) at 71°C for another 60 minutes, after which 4.0 g of 88% formic acid aqueous solution (hereinafter referred to as "88% formic acid") and 4.0 g of deionized water were added. After this, the solution was maintained (aged) at 71°C for another 30 minutes to complete the polymerization. After the polymerization was completed, 241.9 g of deionized water was added dropwise to the reaction solution with stirring to obtain copolymer aqueous solution (D-1). The copolymer aqueous solution (D-1) was dried under reduced pressure in a vacuum dryer at 90°C, and then the dried material was pulverized in a lab mill to obtain copolymer powder (D-2). The weight-average molecular weight of the obtained copolymer powder (D-2) was 237,000. Furthermore, the amount of unreacted sodium hypophosphite (anhydrous) contained in the powder was 1433 ppm, so the amount of sodium hypophosphite (anhydrous) in the copolymer was 4378 ppm.

[0088] <Manufacturing Example 5> In a 2.5L stainless steel reaction vessel equipped with a reflux condenser, stirrer, nitrogen inlet tube, and temperature sensor, 150.0g of deionized water, 29.1g of 4% SHP, and 2.1g of 1% NaOH were charged, and the mixture was heated to 71°C while stirring under a nitrogen atmosphere. Then, while stirring, 83.8g of NVP was added to the polymerization reaction system at 71°C in two stages: 30 minutes followed by 288.6g for 155 minutes. 8.6g of 9% V-65 was added in two stages: 30 minutes followed by 20.2g for 180 minutes. 29.1g of 4% SHP was added for 185 minutes, 236.4g of deionized water for 210 minutes, and 93.1g of AN for 200 minutes starting 10 minutes after the start of NVP addition, each additive was added dropwise through separate supply routes via a tip nozzle. AN, 4% SHP, and deionized water were added dropwise continuously at a constant dropping rate. The addition of all components except AN was started simultaneously with the addition of NVP. After the addition of AN was completed, the reaction solution was held (aged) at 71°C for another 60 minutes, after which 90.9 g of 5% malonic acid and 9.1 g of deionized water were added. After this, the solution was held (aged) at 71°C for another 60 minutes to complete the polymerization. After the polymerization was complete, 209.1 g of deionized water was added dropwise to the reaction solution with stirring to obtain an aqueous copolymer solution (E-1). The aqueous copolymer solution (E-1) was dried under reduced pressure in a vacuum dryer at 90°C, and then the dried material was pulverized in a lab mill to obtain copolymer powder (E-2). The weight-average molecular weight of the obtained copolymer powder (E-2) was 187,000. Furthermore, since the amount of unreacted sodium hypophosphite (anhydrous) contained in the powder was 1480 ppm, the amount of sodium hypophosphite (anhydrous) derived from the copolymer was 2670 ppm.

[0089] <Manufacturing Example 6> In a 2.5 L stainless steel reaction vessel equipped with a reflux condenser, stirrer, nitrogen inlet tube, and temperature sensor, 373.9 g of deionized water, 9.0 g of 25% SHP, and 0.14 g of 48% NaOH were charged, and the mixture was heated to 90°C under a nitrogen atmosphere while stirring. Then, while stirring, 500.0 g of NVP was added to the polymerization reaction system at 90°C for 360 minutes, and 27.0 g of 10% by weight of 2,2'-azobis(2-methylpropionamidine) dihydrochloride aqueous solution (hereinafter referred to as "10% V-50") was added for 390 minutes, each through separate supply channels via a tip nozzle. The addition of each component was carried out continuously at a constant dropping rate. After the addition of NVP was completed, the reaction solution was maintained (aged) at 90°C for another 60 minutes, and then 8.5 g of 88% formic acid was added. After this, the mixture was held (aged) at 90°C for another 60 minutes, and then 3.6 g of 48% NaOH was added. After this, the mixture was held (aged) at 90°C for another 60 minutes to complete the polymerization and obtain an aqueous copolymer solution (F-1). The aqueous copolymer solution (F-1) was dried under reduced pressure in a vacuum dryer at 90°C, and then the dried material was pulverized in a lab mill to obtain copolymer powder (F-2). The weight-average molecular weight of the obtained copolymer powder (F-2) was 90,000. Furthermore, the content of unreacted sodium hypophosphite (anhydrous) in the powder was 15 ppm, so the content of sodium hypophosphite (anhydrous) in the copolymer was 4135 ppm.

[0090] <Manufacturing Example 7> In a 2.5 L stainless steel reaction vessel equipped with a reflux condenser, stirrer, nitrogen inlet tube, and temperature sensor, 144.7 g of deionized water, 94.3 g of 10% by weight thioglycerol aqueous solution (hereinafter referred to as "10% thioglycerol"), and 2.0 g of 1% NaOH were charged, and the mixture was heated to 71°C while stirring under a nitrogen atmosphere. Next, while stirring, 80.9g of NVP was added to the polymerization reaction system at 71°C in two stages: 30 minutes followed by 278.5g over 155 minutes. 8.3g of 9% V-65 was added in two stages: 30 minutes followed by 19.5g over 180 minutes. 94.3g of 10% thioglycerol was added for 185 minutes, 128.8g of deionized water for 210 minutes, and 89.8g of AN was added for 200 minutes starting 10 minutes after the start of NVP addition, each through separate supply channels via the tip nozzle. The addition of AN, 10% thioglycerol, and deionized water was carried out continuously at a constant dropping rate. The addition of all substances except AN was started simultaneously with the addition of NVP. After the completion of the addition of AN, the reaction solution was maintained (aged) at 71°C for another 60 minutes, after which 87.8g of 5% malonic acid and 8.8g of deionized water were added. The mixture was then maintained at 71°C for another 60 minutes (maturation) to complete the polymerization. After polymerization was complete, 212.2 g of deionized water was added dropwise to the reaction solution while stirring to obtain an aqueous copolymer solution (G-1). The aqueous copolymer solution (G-1) was dried under reduced pressure in a vacuum dryer at 90°C, and the dried material was then pulverized in a lab mill to obtain copolymer powder (G-2). The weight-average molecular weight of the obtained copolymer powder (G-2) was 388,000.

[0091] <Examples 1-5, Comparative Examples 1 and 2> The results of evaluating the copolymer powders obtained in Production Examples 1-7 are shown.

[0092] [Table 1]

[0093] <Example 6> The copolymer powder (A-2) obtained in Production Example 1 was dissolved in dimethyl sulfoxide (hereinafter referred to as "DMSO") to obtain a 10% by mass solution (A-3). Next, commercially available acrylic fiber ("Acrylic Muslin," a dyeing test fiber manufactured by Irozome Co., Ltd.) was dissolved in DMSO to obtain a 10% by mass solution (S). Solution (A-4), obtained by mixing solution (A-3) and solution (S) in a ratio of 1:9, was dried at 110°C for 1 hour under reduced pressure, then at 120°C for 15 hours under reduced pressure, and finally at 130°C for 2.5 hours under reduced pressure to obtain a film with a thickness of 100 μm. The evaluation results of the b* value and moisture absorption rate of the obtained film are shown in the table below. For the copolymer-free product necessary for evaluating the moisture absorption rate, the film obtained by drying solution (S) under the above conditions was used. Furthermore, it was confirmed that fibers containing the copolymer of the present invention can be obtained by extruding solution (A-4) into a 62% by mass DMSO / water mixed solution and stretching it.

[0094] <Examples 7-10, Comparative Examples 3-4> A 100 μm thick film was obtained in the same manner as in Example 6, except that copolymer powders (B-2) to (G-2) were used instead of copolymer powder (A-2). The b* value and moisture absorption rate evaluation results of the obtained film are shown in the table below.

[0095] [Table 2]

Claims

1. Structural units (a) derived from N-vinyllactam monomers, and Having a structural unit (b) derived from a nitrile monomer, The main chain has structural units derived from phosphorus atom-containing compounds, The content of structural units derived from the phosphorus atom-containing compound is 0.1% by mass or more and 6% by mass or less, based on 100% by mass of the total mass of the N-vinyllactam copolymer. The structural unit derived from the phosphorus atom-containing compound is a hypophosphorous group or a hypophosphorous base. The content of the aforementioned structural unit (a) is 40 to 98% by mass. N-vinyl lactam copolymer.

2. The weight-average molecular weight is between 50,000 and 450,000. The N-vinyl lactam copolymer according to claim 1.

3. Structural units (a) derived from N-vinyllactam monomers, and Having a structural unit (b) derived from a nitrile monomer, The main chain has structural units derived from phosphorus atom-containing compounds, The content of structural units derived from the phosphorus atom-containing compound is 0.1% by mass or more and 6% by mass or less, based on 100% by mass of the total mass of the N-vinyllactam copolymer. The structural unit derived from the phosphorus atom-containing compound is a hypophosphorous group or a hypophosphorous base. The content of the aforementioned structural unit (a) is 40 to 98% by mass. N-vinyl lactam copolymer and Assuming the total amount of all structural units is 100% by mass, Structural units derived from acrylonitrile Contains 35% or more by mass Acrylonitrile copolymers Composition containing.

Images