Method for producing modacrylic resin

Abstract

To provide a method for producing a modacrylic resin, the method enabling copolymerization of a monomer having an anionic functional group by suspension polymerization using an oil-soluble initiator.SOLUTION: A method for producing a modacrylic resin according to one embodiment of the present invention includes a polymerization step of subjecting a monomer composition including 35 to 84 mass% of acrylonitrile, 15 to 64.9 mass% of one or more halogen-containing monomers selected from the group consisting of vinyl halide and vinylidene halide, and 0.1 to 10 mass% of a monomer including an anionic functional group, to suspension polymerization, in the presence of an oil-soluble initiator and a surfactant, wherein the surfactant includes one or more selected from the group consisting of quaternary ammonium salt having one or more alkyl groups having 2 or more carbon atoms, and quaternary phosphonium salt having one or more alkyl groups having 2 or more carbon atoms.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a modacrylic resin obtained by copolymerizing a monomer having an ionic functional group.

Background Art

[0002] Modacrylic resins obtained by copolymerizing halogenated monomers such as acrylonitrile and vinyl chloride are used as raw materials for modacrylic fibers because they have a soft texture and flame retardancy when fiberized. Modacrylic resins are usually used to produce modacrylic fibers by wet spinning. From the viewpoints of densifying the fiber structure formation when coagulating the spinning dope and imparting dyeability to the fibers, monomers having ionic functional groups such as sulfonic acid group-containing monomers are copolymerized. For example, in Patent Documents 1 and 2, it has been studied to produce a modacrylic resin obtained by copolymerizing a monomer having an ionic functional group by emulsion polymerization or suspension polymerization using a water-soluble initiator, specifically a redox polymerization initiator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the modacrylic resins obtained by emulsion polymerization or suspension polymerization using a water-soluble initiator such as a redox polymerization initiator as described in Patent Documents 1 and 2 have a problem of high water content. In the case of suspension polymerization using a normal oil-soluble initiator, the water content of the modacrylic resin can be reduced. However, monomers having ionic functional groups cannot dissolve in monomer oil droplets containing monomers such as acrylonitrile, halogenated monomers, and oil-soluble initiators, and it has been difficult to obtain a modacrylic resin copolymerized with monomers having ionic functional groups.

[0005] In order to solve the above-mentioned conventional problems, the present invention provides a method for producing a modacrylic resin capable of copolymerizing a monomer having an anionic functional group by suspension polymerization using an oil-soluble initiator.

Means for Solving the Problems

[0006] One or more embodiments of the present invention relate to a method for producing a modacrylic resin, including a polymerization step of subjecting a monomer composition containing 35 to 84% by mass of acrylonitrile, 15 to 64.9% by mass of one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, and 0.1 to 10% by mass of a monomer containing an anionic functional group to suspension polymerization in the presence of an oil-soluble initiator and a surfactant, wherein the surfactant includes one or more selected from the group consisting of quaternary ammonium salts having one or more alkyl groups with 2 or more carbon atoms and quaternary phosphonium salts having one or more alkyl groups with 2 or more carbon atoms.

Effects of the Invention

[0007] According to one or more embodiments of the present invention, a modacrylic resin copolymerized with a monomer having an anionic functional group can be obtained by suspension polymerization using an oil-soluble initiator.

Modes for Carrying Out the Invention

[0008] As a result of repeated studies to solve the above-described problems, the inventors of the present invention have found that when one or more halogen-containing monomers selected from the group consisting of acrylonitrile, vinyl halides, and vinylidene halides, and a monomer containing an anionic functional group are suspension-polymerized in the presence of an oil-soluble initiator, a modacrylic resin copolymerized with a monomer having an anionic functional group can be obtained by the presence of at least one surfactant selected from the group consisting of quaternary ammonium salts having at least one alkyl group having 2 or more carbon atoms and quaternary phosphonium salts having at least one alkyl group having 2 or more carbon atoms in the polymerization system. This is presumably because, in the polymerization system, the monomer containing an anionic functional group is converted into a quaternary ammonium salt or a quaternary phosphonium salt, and the solubility in monomer oil droplets containing acrylonitrile, a halogenated monomer, an oil-soluble initiator, etc. is exhibited, so that acrylonitrile, the halogen-containing monomer, and the monomer containing an anionic functional group can be copolymerized.

[0009] In this specification, when a numerical range is indicated by "~", the numerical range includes both end values (upper limit and lower limit). For example, the numerical range of "X~Y" is a range including both end values of X and Y. Further, in this specification, when a plurality of numerical ranges are described, it is intended to include numerical ranges obtained by appropriately combining the upper and lower limits of different numerical ranges. Further, in this specification, when the upper limit and the lower limit of a numerical range are separately described in plural, it is intended to include numerical ranges obtained by appropriately combining the upper limit and the lower limit.

[0010] In one or more embodiments of the present invention, the method for producing a modacrylic resin includes a polymerization step of suspension-polymerizing one or more halogen-containing monomers selected from the group consisting of acrylonitrile, vinyl halides, and vinylidene halides, and a monomer containing an anionic functional group in the presence of an oil-soluble initiator and a surfactant.

[0011] The vinyl halide is not particularly limited, and examples thereof include vinyl chloride, vinyl bromide, and vinyl iodide. The vinylidene halide is not particularly limited, and examples thereof include vinylidene chloride, vinylidene bromide, and vinylidene iodide. These halogen-containing monomers may be used alone or in combination of two or more. From the viewpoint of heat resistance, it is preferable to use vinyl chloride and / or vinylidene chloride.

[0012] The monomer containing an anionic functional group is not particularly limited, and examples thereof include vinyl monomers containing various anionic functional groups. The anionic functional group is not particularly limited, and examples thereof include a sulfonic acid group, a sulfuric acid group, a sulfinic acid group, and a carboxy group (also referred to as a carboxylic acid group).

[0013] The monomer containing a sulfonic acid group is not particularly limited, and examples thereof include allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, styrene sulfonic acid, 2-methyl-1,3-butadiene-1-sulfonic acid, and metal salts (for example, sodium salts) and amine salts thereof.

[0014] The monomer containing a sulfuric acid group is not particularly limited, and examples thereof include vinyl sulfate, 4-allylphenol sulfate, and metal salts (for example, sodium salts) thereof.

[0015] The monomer containing a sulfinic acid group is not particularly limited, and examples thereof include vinyl sulfinic acid, allyl sulfinic acid, allylbenzene sulfinic acid, 2-acrylamidosulfinic acid, 2-acrylamidobenzenesulfinic acid, styrene sulfinic acid, and metal salts (for example, sodium salts) thereof.

[0016] The monomer containing the carboxyl group is not particularly limited, and examples thereof include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and metal salts (e.g., sodium salts) and amine salts thereof. The unsaturated monocarboxylic acid is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, etc. The unsaturated dicarboxylic acid is not particularly limited, and examples thereof include maleic acid, fumaric acid, itaconic acid, etc.

[0017] The monomer containing the anionic functional group described above may be used alone or in combination of two or more. Among them, from the viewpoint of polymerizability, monomers containing a sulfonic acid group and monomers containing a carboxyl group are preferable, and from the viewpoint of further enhancing the dyeability of modacrylic fibers obtained by fibrillating a modacrylic resin, monomers containing a sulfonic acid group are more preferable.

[0018] The quaternary ammonium salt only needs to have one or more alkyl groups having 2 or more carbon atoms and is not particularly limited. For example, those represented by the following general formula (1) can be used. In the following, unless otherwise specified, the "quaternary ammonium salt" means one having one or more alkyl groups having 2 or more carbon atoms.

[0019]

Chemical formula

[0020] However, in the general formula (1), R 1 , R 2 , R 3 and R 4 are each independently an alkyl group having 1 to 22 carbon atoms, a cycloalkyl group having 3 to 14 carbon atoms, or an aryl group having 6 to 18 carbon atoms, and at least one of R 1 , R 2 , R 3 and R 4 is preferably an alkyl group having 2 or more carbon atoms. In the general formula (1), R 1 , R 2 , R 3 and R4 is independently an alkyl group having 1 to 22 carbon atoms or an aryl group having 6 to 18 carbon atoms, and R 1 , R 2 , R 3 and R 4 is more preferably at least one of an alkyl group having 2 or more carbon atoms. R 1 , R 2 , R 3 and R 4 are each independently an alkyl group having 1 to 22 carbon atoms, and R 1 , R 2 , R 3 and R 4 is even more preferably at least one of an alkyl group having 2 or more carbon atoms. Further, in the general formula (1), the total number of carbon atoms of R 1 , R 2 , R 3 and R 4 is preferably 5 to 48, and more preferably 8 to 32.

[0021] In the quaternary ammonium salt, the alkyl group or aryl group may have one or more substituents. The substituents are not particularly limited, and examples thereof include a halogen atom, a hydroxyl group, a mercapto group, and the like.

[0022] In the general formula (1), X - may be a halogen, a carboxylate, a hydroxyl group, or a hydrogen sulfate group.

[0023] The quaternary ammonium salt may be a tetraalkylammonium salt in which all of R 1 , R 2 , R 3 and R 4 are alkyl groups. In the tetraalkylammonium salt, the four alkyl groups may be different alkyl groups, two may be the same alkyl group, three may be the same alkyl group, or all may be the same alkyl group.

[0024] The quaternary ammonium salt is R 1, R 2 , R 3 and R 4 Among them, three may be alkyl groups and the remaining one may be an aryl group, forming a trialkylmonoarylammonium salt. In the trialkylmonoarylammonium salt, the three alkyl groups may be different alkyl groups respectively, or two of them may be the same alkyl group.

[0025] The quaternary ammonium salt may be a dialkyldiarylammonium salt in which two of R 1 , R 2 , R 3 and R 4 are alkyl groups and the remaining two are aryl groups. In the dialkyldiarylammonium salt, the two alkyl groups may be the same or different from each other, and the two aryl groups may be the same or different from each other.

[0026] The quaternary ammonium salt may be a monoalkyltriarylammonium salt in which one of R 1 , R 2 , R 3 and R 4 is an alkyl group and the remaining three are aryl groups. In the monoalkyltriarylammonium salt, the three aryl groups may be different aryl groups respectively, or two of them may be the same aryl group.

[0027] The quaternary phosphonium salt only needs to have at least one alkyl group with 2 or more carbon atoms, and is not particularly limited. For example, those represented by the following general formula (2) can be used. In the following, unless otherwise specified, "quaternary phosphonium salt" means those having at least one alkyl group with 2 or more carbon atoms.

[0028]

Chemical formula

[0029] In the general formula (2), R 1 , R 2 , R 3and R 4 and X - may be the same as defined in the general formula (1), and duplicate explanations are omitted.

[0030] The quaternary phosphonium salt is R 1 R 2 R 3 and R 4 may all be tetraalkylphosphonium salts in which the alkyl groups are all alkyl groups. In the tetraalkylphosphonium salt, the four alkyl groups may each be a different alkyl group, two may be the same alkyl group, three may be the same alkyl group, or all may be the same alkyl group.

[0031] The quaternary phosphonium salt is R 1 R 2 R 3 and R 4 may be a trialkylmonoarylphosphonium salt in which three of them are alkyl groups and the remaining one is an aryl group. In the trialkylmonoarylphosphonium salt, the three alkyl groups may each be a different alkyl group or two may be the same alkyl group.

[0032] The quaternary phosphonium salt is R 1 R 2 R 3 and R 4 may be a dialkyldiarylphosphonium salt in which two of them are alkyl groups and the remaining two are aryl groups. In the dialkyldiarylphosphonium salt, the two alkyl groups may be the same or different from each other, and the two aryl groups may be the same or different from each other.

[0033] The quaternary phosphonium salt is R 1 R 2 R 3 and R 4 may also be a monoalkyltriarylphosphonium salt in which one of them is an alkyl group and the remaining three are aryl groups. In the monoalkyltriarylphosphonium salt, the three aryl groups may each be a different aryl group or two may be the same aryl group.

[0034] The surfactant may be one or more selected from the group consisting of tetraalkylammonium salts, trialkylmonoarylammonium salts, dialkyldiarylammonium salts, monoalkyltriarylammonium salts, tetraalkylphosphonium salts, trialkylmonoarylphosphonium salts, dialkyldiarylphosphonium salts, and monoalkyltriarylphosphonium salts.

[0035] More specifically, examples of the surfactant include tetraethylammonium bromide, tetrabutylammonium bromide, didodecyldimethylammonium bromide, and the like.

[0036] The above-described surfactant may be used alone or in combination of two or more.

[0037] The suspension polymerization can be carried out in the same manner as the suspension polymerization using an oil-soluble polymerization initiator of a general modacrylic resin, except that the polymerization is carried out in the presence of one or more surfactants selected from the group consisting of the quaternary ammonium salt and the quaternary phosphonium salt. For example, in addition to the monomer composition containing the above-described monomers and the surfactant, an aqueous medium, an oil-soluble polymerization initiator, a dispersant, and the like can be charged into a polymerization reactor all at once, in portions, or continuously to carry out the polymerization reaction.

[0038] The monomer composition contains 35 to 84% by mass of acrylonitrile, 15 to 64.9% by mass of one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, and 0.1 to 10% by mass of a monomer containing an anionic functional group. Thereby, a modacrylic resin can be obtained which contains 35 to 84% by mass of structural units derived from acrylonitrile, 15 to 64.9% by mass of structural units derived from one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, and 0.1 to 10% by mass of structural units derived from a monomer containing an anionic functional group.

[0039] The blending amount of the surfactant is not particularly limited. For example, it is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 9 parts by mass, still more preferably 1.0 to 8 parts by mass, even more preferably 1.5 to 7 parts by mass, and even more preferably 2.0 to 6 parts by mass, based on 100 parts by mass of the monomer composition. When the blending amount of the surfactant is 0.1 part by mass or more, the conversion rate of the monomer having an anionic functional group is improved. When the blending amount of the surfactant is 10 parts by mass or less, the washing of the resin after the polymerization reaction becomes easy.

[0040] The ratio Ws / Wa of the mass (Ws) of the surfactant to the mass (Wa) of the monomer containing the anionic functional group is not particularly limited. For example, it is preferably 0.005 to 5, more preferably 0.01 to 4, and still more preferably 0.1 to 3. When Ws / Wa is 0.005 or more, the conversion rate of the monomer having an anionic functional group is improved. When Ws / Wa is 5 or less, the washing of the resin after the polymerization reaction becomes easy.

[0041] The oil-soluble polymerization initiator is not particularly limited. For example, organic peroxide-based polymerization initiators, azo-based polymerization initiators, etc. can be mentioned. Examples of the organic peroxide-based polymerization initiator include diisobutyl peroxide, diisopropyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, t-butyl peroxypivalate, t-butyl peroxyneodecanoate, and 1,1,3,3-tetramethylbutyl peroxyneodecanoate. Examples of the azo-based polymerization initiator include 2,2'-azobisisobutyronitrile and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). These oil-soluble polymerization initiators can be used alone or in combination of two or more.

[0042] The oil-soluble polymerization initiator can be added to the polymerization system without particular restrictions, and for example, it can be dissolved in an organic solvent and used. Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane and isoparaffin; ketones such as acetone; and esters such as ethyl acetate and butyl acetate. These organic solvents can be used alone or in combination of two or more.

[0043] The compounding amount of the oil-soluble polymerization initiator is not particularly limited. For example, from the viewpoint of suppressing resin coloring, it is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 8 parts by mass, still more preferably 0.2 to 7 parts by mass, and even more preferably 0.4 to 6 parts by mass with respect to 100 parts by mass of the monomer composition.

[0044] As the dispersant, those used for polymerization in an aqueous medium can be appropriately used. For example, partially saponified polyvinyl acetate; water-soluble cellulose ethers such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, and carboxymethyl cellulose; polyethylene oxide; polyvinyl pyrrolidone, etc. These dispersants can be used alone or in combination of two or more.

[0045] The compounding amount of the dispersant is not particularly limited. For example, from the viewpoint of controlling the particle diameter of the resin, it is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 8 parts by mass, and still more preferably 0.1 to 7 parts by mass with respect to 100 parts by mass of the monomer composition.

[0046] The aqueous medium is not particularly limited, and various waters such as ion-exchanged water can be appropriately used. The aqueous medium is not particularly limited. For example, from the viewpoint of removing the heat of polymerization reaction, it may be 100 to 500 parts by mass with respect to 100 parts by mass of the monomer composition.

[0047] In the suspension polymerization, within a range that does not impair the object of the present invention, if necessary, other additives such as a chain transfer agent, a dispersion aid, an antioxidant, a polymerization degree regulator, a particle size regulator, a pH regulator, a gelation improver, an antistatic agent, a stabilizer, and a scale inhibitor can be appropriately used. The other additives may be used alone or in combination of two or more. The blending amount of the other additives may be, for example, 10 parts by mass or less based on 100 parts by mass of the monomer composition.

[0048] According to the suspension polymerization, a slurry-like modacrylic resin can be obtained. The slurry-like modacrylic resin is dehydrated and then dried to obtain a powder-like modacrylic resin. The water content of the modacrylic resin after dehydration and before drying may be 60% or less, or may be 45% or less. Thereby, the drying process can be simplified and the energy required for drying can be easily reduced. The drying is not particularly limited and can be performed using, for example, a hot air dryer. The drying temperature may be 50 to 100 ° C, or may be 55 to 85 ° C from the viewpoint of suppressing resin coloring. In this specification, the water content of the modacrylic resin after dehydration and before drying can be measured as described in the examples.

[0049] The conversion rate of the monomer containing an anionic functional group is not particularly limited and may be, for example, 10% or more, 20% or more, 30% or more, 35% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more. In this specification, the conversion rate of the monomer containing an anionic functional group can be measured as described in the examples.

[0050] The polymerization yield of the modacrylic resin is not particularly limited and is preferably 50 to 100%, more preferably 60 to 100%, and even more preferably 70 to 100% from the viewpoint of reducing the residual ratio of the raw material. In this specification, the yield of the modacrylic resin can be measured as described in the examples.

[0051] The particle size of the modacrylic resin (powder) is not particularly limited. For example, from the viewpoint of resin handleability, D10 based on volume is preferably 20 to 100 μm, D50 is preferably 70 to 200 μm, and D90 is preferably 100 to 400 μm. In this specification, the particle size of the modacrylic resin can be measured as described in the examples.

[0052] The modacrylic resin is not particularly limited. For example, when used in wet spinning, from the viewpoints of increasing the resin concentration of the spinning dope and realizing a dense fiber structure and achieving both fiber strength, the mass average molecular weight is preferably 10,000 to 500,000, more preferably 20,000 to 400,000, and even more preferably 30,000 to 200,000.

[0053] The modacrylic resin is not particularly limited. For example, from the viewpoint of increasing fiber strength and easily obtaining fibers with good comb-through properties, the molecular weight distribution (mass average molecular weight / number average molecular weight) is preferably 1.1 to 7.0, and more preferably 1.1 to 5.0. In this specification, the mass average molecular weight and number average molecular weight of the modacrylic resin can be measured as described in the examples.

[0054] The modacrylic resin is not particularly limited. For example, when dimethylformamide is used as the solvent, the specific viscosity at 30°C is preferably 0.05 to 0.60, and more preferably 0.05 to 0.50. In this specification, the specific viscosity can be measured as described in the examples.

[0055] The modacrylic resin can be suitably used as a raw material for modacrylic fibers. By including a structural unit derived from a monomer containing an anionic functional group, the modacrylic resin can form a dense structure when used in wet spinning and can also impart dyeability to the fibers.

Examples

[0056] Hereinafter, the present invention will be described in more detail with reference to examples. Note that the present invention is not limited to the following examples.

[0057] First, various measurement methods and evaluation methods will be described. (1) Polymerization yield of the modacrylic resin Based on the total mass (A) parts by mass of the non-volatile components used in the polymerization when the total amount of the monomers used is 100 parts by mass, the solid content concentration (Sc%) of the slurry or latex after the polymerization reaction, the acrylonitrile content (AN%) calculated by elemental analysis of the modacrylic resin, and the anionic functional group content (S%) determined from sulfur analysis, the polymerization yield was calculated by the following formula based on the following formula. The non-volatile components used in the polymerization mean all components except vinyl chloride. Polymerization yield (%) = (Sc% × A) / (1 - Sc% × (1 - AN% - S%)) (2) Conversion rate of the monomer containing an anionic functional group It is calculated by the following formula from the anionic functional group content (S%) determined from sulfur analysis and the polymerization yield (%) obtained in (1). In the following formula, the charged amount of the monomer containing an anionic functional group is represented by parts by mass when the total amount of the monomers used is 100 parts by mass. Conversion rate (%) = S% × Polymerization yield % × 100 / Charged amount of the monomer containing an anionic functional group (3) Water content of the modacrylic resin The mass (W0) of the water-containing resin obtained by dehydrating the slurry after polymerization using a centrifugal dehydrator at a centrifugal force of 640 × g for 5 minutes, and the mass (W1) of the dried resin obtained by drying the water-containing resin in a hot air dryer at 60 ° C for 24 hours were measured, and the water content of the modacrylic resin was calculated based on the following formula. Water content (%) = [(W0 - W1) / W1] × 100 (4) Particle diameter of the modacrylic resin (powder) It was measured by the laser diffraction / scattering method using a laser diffraction / scattering particle size distribution measuring device ("LA-950" manufactured by HORIBA, Ltd.). (5) Mass average molecular weight and number average molecular weight of the modacrylic resin Measurement and calculation were performed by the GPC method using gel permeation chromatography (HLC-8320GPC manufactured by Tosoh Corporation). Polystyrene was used as the standard polymer, and dimethylformamide was used as the mobile phase (eluent). (6) Specific viscosity ηsp of the modacrylic resin 1.0 g of the modacrylic resin was dissolved in 500 mL of dimethylformamide, and the specific viscosity ηsp was measured at 30 °C using an Ostwald viscometer.

[0058] (Example 1) Into a polymerization reactor, 53 parts by mass of vinyl chloride, 7.5 parts by mass of acrylonitrile, 192 parts by mass of ion-exchanged water, 0.25 parts by mass of partially saponified polyvinyl acetate (saponification degree of about 70 mol%, average degree of polymerization of 1700), 0.75 parts by mass of 1,1,3,3-tetramethylbutyl peroxyneodecanoate, and 1.0 part by mass of tetrabutylammonium bromide (hereinafter also referred to as TBABr) were charged. Then, with the temperature inside the polymerization reactor cooled to 15 °C or lower, stirring and dispersion were carried out for 15 minutes. Thereafter, the temperature inside the polymerization reactor was raised to 52.5 °C to initiate polymerization, and suspension polymerization was carried out at a polymerization temperature of 52.5 °C for 3 hours, and then the polymerization temperature was raised to 55 °C and suspension polymerization was carried out for another 3 hours. During polymerization, 2.0 parts by mass of sodium styrenesulfonate dissolved in 37.5 parts by mass of acrylonitrile and 18 parts by mass of ion-exchanged water was continuously added at a constant rate from immediately after the start of polymerization until the 5.5th hour. After completion of polymerization, the unreacted monomers inside the polymerization reactor were recovered, and then the slurry was discharged. The obtained slurry was dehydrated and dried at 60 °C for 24 hours in a hot air dryer to obtain a modacrylic resin (powder). The obtained modacrylic resin consisted of 48.6% by mass of structural units derived from acrylonitrile, 50.3% by mass of structural units derived from vinyl chloride, and 1.1% by mass of structural units derived from sodium styrenesulfonate. The mass average molecular weight was about 256,000, the molecular weight distribution was 4.65, and the specific viscosity was 0.447. The polymerization yield was 83%, and the conversion rate of sodium styrenesulfonate (hereinafter also referred to as 3S) was 40%.

[0059] (Example 2) A modacrylic resin was obtained in the same manner as in Example 1, except that 2.0 parts by mass of tetrabutylammonium bromide was charged. The obtained modacrylic resin was composed of 47.3% by mass of a structural unit derived from acrylonitrile, 51.0% by mass of a structural unit derived from vinyl chloride, and 1.7% by mass of a structural unit derived from sodium styrenesulfonate. The mass average molecular weight was about 230,000, the molecular weight distribution was 3.68, and the specific viscosity was 0.473. The polymerization yield was 82%, and the conversion rate of sodium styrenesulfonate was 70%.

[0060] (Example 3) A modacrylic resin was obtained in the same manner as in Example 1, except that 3.0 parts by mass of tetrabutylammonium bromide was charged. The obtained modacrylic resin was composed of 50.6% by mass of a structural unit derived from acrylonitrile, 47.1% by mass of a structural unit derived from vinyl chloride, and 2.3% by mass of a structural unit derived from sodium styrenesulfonate. The mass average molecular weight was about 214,000, the molecular weight distribution was 3.99, and the specific viscosity was 0.476. The polymerization yield was 79%, and the conversion rate of sodium styrenesulfonate was 97%.

[0061] (Example 4) Into a polymerization reactor, 52.8 parts by mass of vinyl chloride, 7.5 parts by mass of acrylonitrile, 190 parts by mass of ion-exchanged water, 0.25 parts by mass of partially saponified polyvinyl acetate (saponification degree of about 70 mol%, average degree of polymerization of 1700), 0.75 parts by mass of 1,1,3,3-tetramethylbutyl peroxyneodecanoate, and 1.0 part by mass of tetrabutylammonium bromide were charged. Then, with the temperature inside the polymerization reactor cooled to 15°C or lower, stirring and dispersion were carried out for 15 minutes. Thereafter, the temperature inside the polymerization reactor was raised to 52.5°C to initiate polymerization, and suspension polymerization was carried out at a polymerization temperature of 52.5°C for 3 hours. Then, the polymerization temperature was raised to 55°C and suspension polymerization was further carried out for 3 hours. During polymerization, 2.2 parts by mass of sodium 2-acrylamido-2-methyl-1-propanesulfonate (hereinafter also referred to as AMPSNa) dissolved in 37.5 parts by mass of acrylonitrile and 20 parts by mass of ion-exchanged water was continuously added at a constant rate from immediately after the start of polymerization until the 5.5th hour. After completion of polymerization, the unreacted monomers inside the polymerization reactor were recovered, and then the slurry was discharged. The obtained slurry was dehydrated and dried at 60°C for 24 hours in a hot air dryer to obtain a modacrylic resin. The obtained modacrylic resin was composed of 48.7% by mass of structural units derived from acrylonitrile, 50.4% by mass of structural units derived from vinyl chloride, and 0.9% by mass of structural units derived from sodium 2-acrylamido-2-methyl-1-propanesulfonate. The mass average molecular weight was about 214,000, the molecular weight distribution was 3.77, and the specific viscosity was 0.286. The polymerization yield was 81%, and the conversion rate of sodium 2-acrylamido-2-methyl-1-propanesulfonate was 39%.

[0062] (Example 5) A modacrylic resin was obtained in the same manner as in Example 4, except that 3.0 parts by mass of tetrabutylammonium bromide was charged. The obtained modacrylic resin was composed of 52.4% by mass of structural units derived from acrylonitrile, 45.3% by mass of structural units derived from vinyl chloride, and 2.3% by mass of structural units derived from sodium 2-acrylamido-2-methyl-1-propanesulfonate. The mass average molecular weight was about 233,000, the molecular weight distribution was 3.88, and the specific viscosity was 0.342. The polymerization yield was 83%, and the conversion rate of sodium 2-acrylamido-2-methyl-1-propanesulfonate was 81%.

[0063] (Example 6) A modacrylic resin was obtained in the same manner as in Example 1, except that 1.5 parts by mass of sodium methallylsulfonate (hereinafter also referred to as SMS) was used instead of 2.0 parts by mass of sodium styrenesulfonate. The obtained modacrylic resin was composed of 50.2% by mass of structural units derived from acrylonitrile, 49.1% by mass of structural units derived from vinyl chloride, and 0.7% by mass of structural units derived from sodium methallylsulfonate. The mass average molecular weight was about 258,000, the molecular weight distribution was 4.88, and the specific viscosity was 0.366. The polymerization yield was 79%, and the conversion rate of sodium styrenesulfonate was 38%.

[0064] (Example 7) A modacrylic resin was obtained in the same manner as in Example 1, except that 0.65 parts by mass of tetraethylammonium bromide (hereinafter also referred to as TEABr) was used instead of 1.0 parts by mass of tetrabutylammonium bromide. The obtained modacrylic resin was composed of 48.1% by mass of structural units derived from acrylonitrile, 51.6% by mass of structural units derived from vinyl chloride, and 0.3% by mass of structural units derived from sodium styrenesulfonate. The mass average molecular weight was about 242,000, the molecular weight distribution was 4.28, and the specific viscosity was 0.316. The polymerization yield was 85%, and the conversion rate of sodium styrenesulfonate was 14%.

[0065] (Example 8) A modacrylic resin was obtained in the same manner as in Example 1, except that 1.05 parts by mass of didodecyldimethylammonium bromide (hereinafter also referred to as DDDMABr) was used instead of 1.0 part by mass of tetrabutylammonium bromide. The obtained modacrylic resin was composed of 50.3% by mass of a structural unit derived from acrylonitrile, 48.6% by mass of a structural unit derived from vinyl chloride, and 1.1% by mass of a structural unit derived from sodium styrenesulfonate. The mass average molecular weight was about 259,000, the molecular weight distribution was 4.72, and the specific viscosity was 0.351. The polymerization yield was 78%, and the conversion rate of sodium styrenesulfonate was 44%.

[0066] (Comparative Example 1) A modacrylic resin was obtained in the same manner as in Example 1, except that tetrabutylammonium bromide was not charged into the polymerization reactor. The obtained modacrylic resin was composed of 50% by mass of a structural unit derived from acrylonitrile and 50% by mass of a structural unit derived from vinyl chloride, and did not contain sodium styrenesulfonate. The mass average molecular weight was about 235,000, the molecular weight distribution was 4.90, and the specific viscosity was 2.99. The polymerization yield was 70%, and sodium styrenesulfonate was not copolymerized.

[0067] (Comparative Example 2) A modacrylic resin was obtained in the same manner as in Example 4, except that tetrabutylammonium bromide was not charged into the polymerization reactor. The obtained modacrylic resin was composed of 49.8% by mass of a structural unit derived from acrylonitrile and 50.2% by mass of a structural unit derived from vinyl chloride, and did not contain sodium 2-acrylamido-2-methyl-1-propanesulfonate. The mass average molecular weight was about 207,000, the molecular weight distribution was 3.97, and the specific viscosity was 0.269. The polymerization yield was 81%, and sodium 2-acrylamido-2-methyl-1-propanesulfonate was not copolymerized.

[0068] (Comparative Example 3) A modacrylic resin was obtained in the same manner as in Example 1, except that 0.48 part by mass of tetramethylammonium bromide (hereinafter also referred to as TMABr) was used instead of 1.0 part by mass of tetrabutylammonium bromide. The obtained modacrylic resin consisted of 47.7% by mass of structural units derived from acrylonitrile and 52.3% by mass of structural units derived from vinyl chloride, contained no sodium styrenesulfonate, had a mass average molecular weight of about 248,000, a molecular weight distribution of 4.13, and a specific viscosity of 0.304. The polymerization yield was 80%, and sodium styrenesulfonate was not copolymerized.

[0069] (Comparative Example 4) Into a polymerization reactor, 54.5 parts by mass of vinyl chloride, 3.5 parts by mass of acrylonitrile, 210 parts by mass of ion-exchanged water, 0.02 part by mass of ammonium persulfate, 0.6 part by mass of sodium bisulfite, 0.0039 part by mass of iron sulfate, 0.3 part by mass of sulfuric acid (64% by mass), and 0.87 part by mass of sodium lauryl sulfate were charged. The pH in the polymerization reactor was adjusted to 2 - 3, and emulsion polymerization was carried out at a polymerization temperature of 50°C for a polymerization time of 5 hours to obtain a latex of a modacrylic resin. During the polymerization, 2.0 parts by mass of sodium styrenesulfonate was continuously added at a constant rate from the 1st hour to the 5th hour of the start of polymerization, and 40 parts by mass of acrylonitrile was continuously added at a constant rate from immediately after the start of polymerization to the 5.0th hour. Further, in order to keep the polymerization rate constant, 0.262 part by mass of ammonium persulfate used was continuously added at a constant rate from immediately after the start of polymerization to the 5.5th hour. Thereafter, the obtained latex of the modacrylic resin was subjected to salting out, dehydration, washing with water, and drying treatments to obtain a modacrylic resin. The obtained modacrylic resin consisted of 46.0% by mass of structural units derived from acrylonitrile, 52.0% by mass of structural units derived from vinyl chloride, and 2.0% by mass of structural units derived from sodium styrenesulfonate, had a mass average molecular weight of about 95,000, and a specific viscosity of 0.193. The polymerization yield was 97%, and the conversion rate of sodium styrenesulfonate was 95%.

[0070] In the examples and comparative examples, the water content and particle size of the modacrylic resin were measured as described above, and the results are shown in Table 1 below.

[0071]

Table 1

[0072] As can be seen from Table 1 above, in the examples, one or more halogen-containing monomers selected from the group consisting of acrylonitrile, vinyl halide, and vinylidene halide, and a monomer containing an anionic functional group were suspension-polymerized in the presence of an oil-soluble initiator and a quaternary ammonium salt having one or more alkyl groups having 2 or more carbon atoms, whereby a modacrylic resin copolymerized with a monomer containing an anionic functional group could be obtained.

[0073] On the other hand, in the case of Comparative Examples 1 and 2 in which no quaternary ammonium was used during suspension polymerization, and Comparative Example 3 in which a quaternary ammonium having only an alkyl group having 1 carbon atom was used, a monomer containing an anionic functional group could not be copolymerized. Further, in the case of Comparative Example 4 in which emulsion polymerization was carried out using a water-soluble initiator, specifically, a redox polymerization initiator, a modacrylic resin copolymerized with a monomer containing an anionic functional group could be obtained, but it was necessary to perform salting out, dehydration, water washing, and drying treatments on the latex of the acrylic resin obtained by emulsion polymerization, which was complicated, and the water content of the modacrylic resin after dehydration and before drying was high.

[0074] The present invention is not particularly limited, but for example, it is desirable to include the following embodiments.

[0075] [1] A method for producing a modacrylic resin, A polymerization step is included in which a monomer composition containing 35 to 84% by mass of acrylonitrile, 15 to 64.9% by mass of one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, and 0.1 to 10% by mass of a monomer containing an anionic functional group is subjected to suspension polymerization in the presence of an oil-soluble initiator and a surfactant. A method for producing a modacrylic resin, wherein the surfactant contains one or more selected from the group consisting of quaternary ammonium salts having one or more alkyl groups having 2 or more carbon atoms and quaternary phosphonium salts having one or more alkyl groups having 2 or more carbon atoms. [2] The method for producing a modacrylic resin according to [1], wherein the amount of the surfactant blended is 0.1 to 10 parts by mass with respect to 100 parts by mass of the monomer composition. [3] The method for producing a modacrylic resin according to [1] or [2], wherein the quaternary ammonium salt is a compound represented by the following general formula (1). [Chemical formula] (However, in the general formula (1), R 1 , R 2 , R 3 and R 4 are each independently an alkyl group having 1 to 22 carbon atoms or an aryl group having 6 to 18 carbon atoms, and R 1 , R 2 , R 3 and R 4 at least one of them is an alkyl group having 2 or more carbon atoms, and the alkyl group or the aryl group may have one or more substituents, and X - is a halogen, a hydroxyl group, or a hydrogen sulfate group.) [4] The method for producing a modacrylic resin according to any one of [1] to [3], wherein the quaternary phosphonium salt is a compound represented by the following general formula (2). [Chemical formula] (However, in the general formula (2), R 1 , R 2 , R 3 and R 4is, independently of one another, an alkyl group having 1 to 22 carbon atoms or an aryl group having 6 to 18 carbon atoms, and R 1 , R 2 , R 3 and R 4 at least one of which is an alkyl group having 2 or more carbon atoms, and the alkyl group or the aryl group may have 1 or more substituents, and X - is a halogen, a hydroxyl group, or a hydrogen sulfate group.) [5] The method for producing a modacrylic resin according to any one of [1] to [4], wherein the surfactant contains one or more selected from the group consisting of tetraalkylammonium salts, trialkylmonoarylammonium salts, dialkyldiarylammonium salts, monoalkyltriarylammonium salts, tetraalkylphosphonium salts, trialkylmonoarylphosphonium salts, dialkyldiarylphosphonium salts, and monoalkyltriarylphosphonium salts. [6] The method for producing a modacrylic resin according to any one of [1] to [5], wherein the ratio Ws / Wa of the mass (Ws) of the surfactant to the mass (Wa) of the monomer containing an anionic functional group is 0.005 to 5. [7] The method for producing a modacrylic resin according to any one of [1] to [6], wherein in the monomer containing an anionic functional group, the anionic functional group contains one or more selected from the group consisting of a sulfonic acid group, a sulfuric acid group, a sulfinic acid group, and a carboxy group. [8] The method for producing a modacrylic resin according to any one of [1] to [7], wherein the blending amount of the oil-soluble initiator is 0.05 to 1.0 part by mass with respect to 100 parts by mass of the monomer composition.

Claims

1. A method for producing a modacrylic resin, comprising: a polymerization step of subjecting a monomer composition containing 35 to 84% by mass of acrylonitrile, 15 to 64.9% by mass of one or more halogen-containing monomers selected from the group consisting of vinyl halides and vinylidene halides, and 0.1 to 10% by mass of a monomer containing an anionic functional group to suspension polymerization in the presence of an oil-soluble initiator and a surfactant; The method for producing a modacrylic resin, wherein the surfactant contains one or more selected from the group consisting of quaternary ammonium salts having at least one alkyl group having 2 or more carbon atoms and quaternary phosphonium salts having at least one alkyl group having 2 or more carbon atoms.

2. The method for producing a modacrylic resin according to claim 1, wherein the amount of the surfactant is 0.1 to 10 parts by mass with respect to 100 parts by mass of the monomer composition.

3. The method for producing a modacrylic resin according to claim 1, wherein the quaternary ammonium salt is a compound represented by the following general formula (1). [Chemical Formula 5] (However, in the general formula (1), R 1 , R 2 , R 3 and R 4 are each independently an alkyl group having 1 to 22 carbon atoms or an aryl group having 6 to 18 carbon atoms, and at least one of R 1 , R 2 , R 3 and R 4 is an alkyl group having 2 or more carbon atoms. The alkyl group or the aryl group may have one or more substituents. X - is a halogen, a hydroxyl group, or a hydrogen sulfate group.)

4. The method for producing a modacrylic resin according to claim 1, wherein the quaternary phosphonium salt is a compound represented by the following general formula (2). 【Chemical Formula 6】 (However, in the general formula (2), R 1 , R 2 , R 3 and R 4 are each independently an alkyl group having 1 to 22 carbon atoms or an aryl group having 6 to 18 carbon atoms, and at least one of R 1 , R 2 , R 3 and R 4 is an alkyl group having 2 or more carbon atoms. The alkyl group or the aryl group may have one or more substituents. X - is a halogen, a hydroxyl group, or a hydrogen sulfate group.)

5. The method for producing a modacrylic resin according to claim 1, wherein the surfactant contains one or more selected from the group consisting of tetraalkylammonium salts, trialkylmonoarylammonium salts, dialkyldiarylammonium salts, monoalkyltriarylammonium salts, tetraalkylphosphonium salts, trialkylmonoarylphosphonium salts, dialkyldiarylphosphonium salts, and monoalkyltriarylphosphonium salts.

6. The method for producing a modacrylic resin according to claim 1, wherein the ratio Ws / Wa of the mass (Ws) of the surfactant to the mass (Wa) of the monomer containing an anionic functional group is 0.005 to 5.

7. The method for producing a modacrylic resin according to claim 1, wherein in the monomer containing an anionic functional group, the anionic functional group contains one or more selected from the group consisting of a sulfonic acid group, a sulfuric acid group, a sulfinic acid group, and a carboxy group.

8. The method for producing a modacrylic resin according to claim 1, wherein the amount of the oil-soluble initiator is 0.05 to 1.0 parts by mass with respect to 100 parts by mass of the monomer composition.

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