JP7699480B2 - Method for producing sulfur-containing polymer - Google Patents

Description

The present invention relates to a method for producing a sulfur-containing polymer. More specifically, the present invention relates to a method for producing a sulfur-containing polymer, which includes an oxidation step in which the polymer is oxidized using a specific compound.

Polycarbonate with aromatic rings and polymeric materials with a fluorene skeleton are known as high refractive index materials. Refractive index adjusting materials that improve the light extraction efficiency of LEDs and lens materials for imaging systems require materials with a large Abbe number, i.e., low light dispersion. Materials with sulfur or halogen molecules incorporated and materials containing metal oxide nanoparticles have been developed as such materials with high refractive index and low light dispersion.

For example, polyarylene sulfide is known as a material containing sulfur, and a method for producing polyarylene sulfide is known in which diphenyl disulfide and/or thiophenol is polymerized using a vanadium compound as an oxidation polymerization catalyst (see, for example, Patent Document 1).

JP 2015-048442 A

The inventors have conducted research and found that polyarylene sulfide obtained by oxidative polymerization using a vanadium compound as an oxidative polymerization catalyst has a problem with transmittance after heating. Therefore, the present invention aims to provide a method for producing a sulfur-containing polymer that has excellent transmittance after heating.

The present inventors conducted detailed studies on methods for oxidizing sulfide groups in polyarylene sulfide to sulfinyl groups, and discovered that when a specific compound is used, the transmittance of the resulting polymer after heating is improved, leading to the invention. That is, the present invention is a method for producing a sulfur-containing polymer having a sulfoxide skeleton in the main chain, which is characterized by including an oxidation step of oxidizing a sulfur-containing polymer having a sulfide skeleton in the main chain using at least one compound selected from the group consisting of hypochlorous acid, hypochlorites, and compounds capable of generating hypochlorous acid.

The method for producing a sulfur-containing polymer of the present invention includes a step of oxidizing a sulfur-containing polymer having a sulfide skeleton in the main chain using a specific compound, so that the sulfur-containing polymer having a sulfoxide skeleton in the main chain obtained by the production method has excellent transmittance after heating. As a result, materials using the polymer have excellent transmittance after heating, and are therefore useful as optical materials such as lenses.

The present invention will be described in detail below. It should be noted that a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.
In this specification, "(meth)acrylate" means "acrylate" or "methacrylate", "(meth)acrylic" means "acrylic" or "methacrylic", and "(meth)acryloyl" means "acryloyl" or "methacryloyl". (Meth)acrylate is also sometimes referred to as (meth)acrylic acid ester.

1. Method for Producing Sulfur-Containing Polymer The method for producing a sulfur-containing polymer of the present invention is a method for producing a sulfur-containing polymer having a sulfoxide skeleton in the main chain, and is characterized by including an oxidation step of oxidizing a sulfur-containing polymer having a sulfide skeleton in the main chain using at least one compound selected from the group consisting of hypochlorous acid, hypochlorites, and compounds capable of generating hypochlorous acid.

In the following description, the method for producing a sulfur-containing polymer of the present invention is also simply referred to as the production method of the present invention. In addition, in the present invention, "having a sulfide skeleton in the main chain" means that the main chain of the polymer has a structure containing at least one sulfide group (-S-), and "having a sulfoxide skeleton in the main chain" means that the main chain of the polymer has a structure containing at least one sulfinyl group (-S(=O)-).

The manufacturing method of the present invention includes an oxidation step of oxidizing a sulfur-containing polymer having a sulfide skeleton in the main chain. By the oxidation step, at least a part of the sulfide skeleton in the sulfur-containing polymer having a sulfide skeleton in the main chain is oxidized to a sulfoxide skeleton, and a sulfur-containing polymer having a sulfoxide skeleton in the main chain is obtained. In the present invention, the sulfur-containing polymer having a sulfide skeleton in the main chain subjected to the oxidation step is sometimes called a sulfide-containing polymer, and the sulfur-containing polymer having a sulfoxide skeleton in the main chain is sometimes called a sulfoxide-containing polymer.

<Sulfide-Containing Polymer>
The sulfur-containing polymer having a sulfide skeleton in the main chain, that is, the sulfide-containing polymer, is preferably, for example, a sulfur-containing polymer having a structural unit (A) represented by the following general formula (1).

(In formula (1), ^X1 represents a divalent aromatic hydrocarbon group which may have a substituent.)
Examples of the divalent aromatic hydrocarbon group include a phenylene group, a naphthylene group, an anthrylene group, a triphenylene group, a biphenylene group, a phenanthrylene group, etc. Among these, in terms of reducing the light dispersion of the polymer, the divalent aromatic hydrocarbon group is preferably a phenylene group, a naphthylene group, an anthrylene group, a biphenylene group, or a triphenylene group, and more preferably a phenylene group.

The substituent that the divalent aromatic hydrocarbon group may have (also referred to as "substituent A") is preferably a reactive functional group, a halogen atom, or an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or a sulfur-containing substituent that may have a substituent (also referred to as "substituent B").

Examples of the reactive functional group include acidic functional groups such as a carboxy group (-COOH), a phosphate group (-OPO(OH) ₃ ), a hydroxyl group (-OH), a sulfo group (-SO ₃ H), a sulfate group (-OSO ₃ H), a phosphonic acid group (-PO(OH) ₃ ), a phosphinic acid group (-PO(OH)-), and a mercapto group (-SH); basic functional groups such as an amino group, an ammonium group, an imino group, an amide group, an imide group, a maleimide group, and a cyano group; curable functional groups such as groups having a reactive unsaturated bond (for example, groups having a reactive double bond such as a vinyl group, a (meth)acryloyl group, an allyl group, and a methallyl group), and groups having a reactive ionic bond (for example, groups having a reactive cyclic ether group such as an epoxy group and an oxetane group); and groups containing these functional groups.

Examples of groups containing these functional groups include groups having the above-mentioned acidic functional group, basic functional group, or curable functional group, and a hydrocarbon chain or a bonding group. That is, in the present invention, the reactive functional group includes not only the above-mentioned acidic functional group, basic functional group, and curable functional group, but also groups containing these functional groups and a bonding chain. Examples of the bonding chain include divalent hydrocarbon groups such as alkylene groups and arylene groups, bonding groups such as ethers, esters, carbonyls, and amides, and combinations of these. For example, when it is said that the reactive functional group is preferably a carboxy group, it means that the reactive functional group is preferably a carboxy group and/or a group containing a carboxy group.

The preferred form of the reactive functional group varies depending on the various physical properties of the sulfoxide-containing polymer obtained by the production method of the present invention.
For example, from the viewpoint of improving the dispersibility of inorganic particles, an acidic functional group, a basic functional group, or a group containing these functional groups is preferred, and a carboxyl group, a phosphoric acid group, a phosphonic acid group, a hydroxyl group, or a group containing these functional groups is more preferred. From the viewpoint of low linear expansion coefficient, a carboxyl group, a phosphoric acid group, a phosphonic acid group, a hydroxyl group, or a group containing these functional groups is preferred, and a hydroxyl group or a group containing a hydroxyl group is more preferred. From the viewpoint of improving adhesion to the substrate, a carboxyl group, a phosphoric acid group, a phosphonic acid group, or a group containing these functional groups is preferred, and a phosphoric acid group, a phosphonic acid group, or a group containing these functional groups is more preferred. In addition, examples of substrates that can improve adhesion include inorganic substrates such as inorganic particle substrates (coatings), metal oxide particle substrates (coatings), glass substrates, silicone substrates, and copper substrates, and organic substrates such as organic particle substrates (coatings), and polymer film substrates. From the viewpoint of improving heat resistance, mechanical strength, and solvent resistance, a carboxy group, a hydroxyl group, an amino group, a maleimide group, a curable functional group, or a group containing these functional groups is preferred, and a carboxy group, a hydroxyl group, an amino group, a maleimide group, a vinyl group, a (meth)acryloyl group, an allyl group, a methallyl group, an epoxy group, an oxetane group, or a group containing these functional groups is more preferred.

Among them, the reactive functional group is preferably a carboxy group, a phosphate group, a phosphonic acid group, a hydroxyl group, a curable functional group, or a group containing these functional groups, in terms of being able to provide a higher refractive index along with excellent physical properties, more preferably a carboxy group, a phosphate group, a hydroxyl group, a vinyl group, an epoxy group, or a group containing these functional groups, and even more preferably a phosphate group, a hydroxyl group, a vinyl group, or a group containing these functional groups. Furthermore, in terms of being able to improve adhesion to the substrate with a low linear expansion coefficient in addition to a high refractive index, the reactive functional group is preferably a carboxy group, a phosphate group, or a group containing these functional groups.

The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, of which a bromine atom is preferred.

Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, and heptyl. Of these, alkyl groups having 1 to 18 carbon atoms are preferred, alkyl groups having 1 to 6 carbon atoms are more preferred, and methyl groups are even more preferred.

Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a s-butoxy group, a t-butoxy group, a pentyloxy group, a phenoxy group, a cyclohexyloxy group, and a benzyloxy group. Of these, an alkoxy group having 1 to 18 carbon atoms is preferred, an alkoxy group having 1 to 6 carbon atoms is more preferred, and a methoxy group is more preferred.

The aryl group may be a phenyl group, a naphthyl group, an anthryl group, a biphenyl group, a triphenyl group, or the like. Of these, a phenyl group is preferred. The number of carbon atoms in the aryl group is preferably 6 to 30, more preferably 6 to 18, and even more preferably 6 to 12.

Examples of the aralkyl group include a benzyl group, a phenethyl group, a phenylpropyl group, a phenylpentyl group, a phenylhexyl group, and a phenyloctyl group. The number of carbon atoms in the aralkyl group is preferably 7 to 14, and more preferably 7 to 9.

Examples of the sulfur-containing substituent include a thioalkyl group and a thioaryl group. Of these, a thioalkyl group is preferred. The number of carbon atoms in the sulfur-containing substituent is preferably 1 to 8, more preferably 1 to 6, and even more preferably 1 to 4.

The alkyl group, alkoxy group, aryl group, aralkyl group, and sulfur-containing substituent may further have a substituent (substituent B). Examples of the substituent (substituent B) include an alkyl group, a halogen atom, and a hydroxyl group. Among these, from the viewpoint of the solubility of the polymer, an alkyl group is preferred, and from the viewpoint of the dispersibility of the inorganic particles, a hydroxyl group is preferred.

Among these, the substituent (substituent A) that the divalent aromatic hydrocarbon group may have is preferably the alkyl group having 1 to 18 carbon atoms and a sulfur-containing substituent, more preferably a methyl group or a thioalkyl group, and particularly preferably a methyl group, in terms of being able to further increase the refractive index and Abbe number. Also, the substituent that the divalent aromatic hydrocarbon group may have is more preferably a hydroxyl group or a sulfur-containing substituent, more preferably a hydroxyl group, a thioalkyl group or a thioaryl group, and particularly preferably a hydroxyl group, in terms of being able to improve the dispersibility of inorganic particles.

The number of substituents A that the divalent aromatic hydrocarbon group may have is not particularly limited, but a smaller number is preferable in that the refractive index of the polymer will be even higher. Specifically, the number is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1.

In the divalent aromatic hydrocarbon group, the position to which the substituent A is bonded is not particularly limited. The same applies when the divalent aromatic hydrocarbon group is a phenylene group, and when the substituent A is, for example, an alkyl group, the position to which it is bonded is not particularly limited, but from the viewpoint of the solubility in solvents and light resistance of the resulting sulfoxide-containing polymer, it is preferable that it is bonded to the 4-position of the phenylene group.

The structural unit (A) is preferably a structural unit (A-1) represented by the following general formula (1-1), since this results in a higher refractive index.

(In the formula, R ¹ may be the same or different and represents a reactive functional group, a halogen atom, or an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or a sulfur-containing substituent, each of which may have a substituent. a represents the number of R ¹ and is an integer of 0 to 4.)
When there are a plurality of R ¹ 's, they may be the same or different.

The reactive functional group, halogen atom, or alkyl group, alkoxy group, aryl group, aralkyl group, or sulfur-containing substituent which may have a substituent represented by R ¹ is preferably the same as the substituent which the divalent aromatic hydrocarbon group in the above general formula (1) may have. Among them, in terms of being able to further increase the refractive index, the above R ¹ is more preferably a methyl group or a thioalkyl group, and particularly preferably a methyl group. In the above general formula (1-1), a represents the number of the substituents R ¹ and is an integer of 0 to 4. In terms of being able to further increase the refractive index, a is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1.

In a preferred embodiment, the sulfide-containing polymer is not limited to any particular sulfur-containing polymer having the structural unit (A), but may further contain a structural unit (B) represented by the following general formula (2) and/or a structural unit (C) represented by the following general formula (3).

(In formulas (2) and (3), ^X2 and ^X3 are the same or different and each represents a divalent aromatic hydrocarbon group which may have a substituent.)
In the structural unit (B) represented by the general formula (2), ^X2 represents a divalent aromatic hydrocarbon group which may have a substituent. The divalent aromatic hydrocarbon group represented by ^X2 is preferably the same as the divalent aromatic hydrocarbon group represented by ^X1 . The substituent which the divalent aromatic hydrocarbon group represented by ^X2 may have is preferably the same as the substituent which the divalent aromatic hydrocarbon group represented by ^X1 may have. The divalent aromatic hydrocarbon group represented by X2 and its substituent may be the same as or different from ^the divalent aromatic hydrocarbon group represented by ^X1 and its substituent.

The above structural unit (B) is preferably a structural unit (B-1) represented by the following general formula (2-1) because of its high polarity due to its solubility, etc.

(In the formula, R ² may be the same or different and represents a reactive functional group, a halogen atom, or an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or a sulfur-containing substituent, each of which may have a substituent. b represents the number of R ² and is an integer of 0 to 4.)
When there are a plurality of ^R2's , they may be the same or different.

Examples of the reactive functional group, halogen atom, or alkyl group, alkoxy group, aryl group, aralkyl group, or sulfur-containing substituent that may have a substituent, represented by R ² , include the same groups as those represented by R ¹ described above. Among them, in terms of being able to further increase the refractive index, the above R ² is more preferably a methyl group or a thioalkyl group, and particularly preferably a methyl group. In the above general formula (2-1), b represents the number of the substituents R ² and is an integer of 0 to 4. In terms of being able to further increase the refractive index, b is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1.

In the structural unit (C) represented by the general formula (3), ^X3 represents a divalent aromatic hydrocarbon group which may have a substituent. The divalent aromatic hydrocarbon group represented by ^X3 is preferably the same as the divalent aromatic hydrocarbon group represented by ^X1 . The substituent which the divalent aromatic hydrocarbon group represented by ^X3 may have is preferably the same as the substituent which the divalent aromatic hydrocarbon group represented by ^X1 may have. The divalent aromatic hydrocarbon group represented by ^X3 or its substituent may be the same as or different from the divalent aromatic hydrocarbon group represented by ^X1 or ^X2 or its substituent.

The above structural unit (C) is preferably a structural unit (C-1) represented by the following general formula (3-1) in terms of high transparency.

(In the formula, R ³ may be the same or different and represents a reactive functional group, a halogen atom, or an alkyl group, an alkoxy group, an aryl group, an aralkyl group, or a sulfur-containing substituent, each of which may have a substituent. c represents the number of R ³ and is an integer of 0 to 4.)
When there are a plurality of R ³ , they may be the same or different. The reactive functional group, halogen atom, or alkyl group, alkoxy group, aryl group, aralkyl group, or sulfur-containing substituent that may have a substituent, ^represented by R 3, may be the same as those represented by R ¹ described above. Among them, in terms of being able to further increase the refractive index, the R ³ is more preferably a methyl group or a thioalkyl group, and particularly preferably a methyl group. In the above general formula (3-1), c represents the number of the substituents R ³ and is an integer of 0 to 4. c is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1, in terms of further increasing the refractive index.

The sulfide-containing polymer may be a polymer containing only the structural unit (A), or may be a copolymer containing the structural unit (A) and the structural unit (B) and/or the structural unit (C). When it is a copolymer, the form is not particularly limited, and may be, for example, an alternating copolymer, a block copolymer, or a random copolymer. The sulfide-containing polymer may have one or more of the structural units (A), (B), or (C).

In the sulfide-containing polymer, the content of the structural unit (A) is preferably 50 to 100 mol%, more preferably 80 to 100 mol%, and even more preferably 95 to 100 mol%, based on 100 mol% of all structural units in the polymer. The total content of the structural units (B) and (C) is preferably 0 to 50 mol%, more preferably 0 to 20 mol%, and even more preferably 0 to 5 mol%, based on 100 mol% of all structural units.

In the sulfide-containing polymer, the total content of the structural units (A), (B) and (C) is preferably 50 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and particularly preferably 100 mol%, based on 100 mol% of all structural units in the polymer.

The sulfide-containing polymer may have a structural unit (D) other than the structural unit (A), the structural unit (B), and the structural unit (C). Examples of the structural unit (D) include a structural unit having at least the reactive functional group described above.

Examples of monomers into which the structural unit (D) can be introduced include monomers having a polymerizable double bond and the reactive functional group. Examples of the polymerizable double bond include vinyl groups, (meth)acryloyl groups, allyl groups, and methallyl groups, with the (meth)acryloyl group being preferred. Examples of monomers having the polymerizable double bond and the reactive functional group include carboxy group-containing (meth)acrylates such as 2-carboxyethyl (meth)acrylate, 2-carboxypropyl (meth)acrylate, 3-carboxypropyl (meth)acrylate, and 4-carboxybutyl (meth)acrylate; phosphoric acid group-containing (meth)acrylates such as 2-(meth)acryloyloxyethyl acid phosphate; epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate and 3,4-epoxycyclohexylmethyl (meth)acrylate; vinyl ether group-containing (meth)acrylates such as 2-(2-vinyloxyethoxy)ethyl (meth)acrylate.

The content of the structural unit (D) is preferably 0 to 50 mol%, more preferably 0 to 20 mol%, and even more preferably 0 to 5 mol%, relative to 100 mol% of all structural units in the polymer.

The sulfide-containing polymer preferably has the reactive functional group at the end of the main chain and/or at the side chain. By having the reactive functional group at least at the end of the main chain or at the side chain, the sulfoxide-containing polymer obtained after the oxidation reaction can exhibit excellent physical properties due to the reactive functional group. The case where the reactive functional group is present at the side chain includes not only the case where the reactive functional group is present at the side chain of the sulfide-containing polymer, but also the case where the substituent in the structural units (A) to (C) represented by the general formulas (1) to (3) is the reactive functional group or a group containing the reactive functional group.

The weight average molecular weight (Mw) of the sulfide-containing polymer is not particularly limited, but is preferably 500 to 10,000,000. When the weight average molecular weight is within the above range, the sulfoxide-containing polymer obtained by the manufacturing method of the present invention can be suitably used as an optical material. The weight average molecular weight is more preferably 1,000 or more, even more preferably 3,000 or more, and even more preferably 10,000 or more, while more preferably 1,000,000 or less, and even more preferably 100,000 or less.

The dispersity (weight average molecular weight/number average molecular weight) of the sulfide-containing polymer is preferably 1 or more and 10 or less. When the dispersity is within the above-mentioned range, the moldability of the sulfoxide-containing polymer obtained by the production method of the present invention is good. In terms of further improving the moldability, the dispersity is more preferably 5 or less, and even more preferably 3 or less.

The weight average molecular weight and number average molecular weight can be determined by gel permeation chromatography (GPC), specifically by the method described in the examples below. The degree of dispersion can be determined by dividing the weight average molecular weight by the number average molecular weight.

The sulfide-containing polymer preferably has a glass transition temperature (Tg) of 80 to 250°C. When the glass transition temperature is in the above-mentioned range, the sulfoxide-containing polymer obtained by the production method of the present invention can be easily molded. From the viewpoint of increasing the heat resistance of the sulfoxide-containing polymer obtained by the production method of the present invention, the glass transition temperature is more preferably 90°C or higher, and even more preferably 100°C or higher, and from the viewpoint of easy molding, it is more preferably 200°C or lower.

The glass transition temperature can be determined by a method in which a differential scanning calorimeter (DSC) is used to measure the intersection of the tangent line at the baseline and the inflection point on the DSC curve obtained by heating from room temperature to 250°C (heating rate 10°C/min) in a nitrogen gas atmosphere.

<Compound>
In the oxidation step, at least one compound selected from the group consisting of hypochlorous acid, hypochlorite, and compounds capable of generating hypochlorous acid is used. At least one compound selected from the group consisting of hypochlorous acid, hypochlorite, and compounds capable of generating hypochlorous acid is collectively referred to as compound (Z).

The hypochlorite is not particularly limited, but is preferably an alkali metal salt such as potassium hypochlorite or sodium hypochlorite; or an alkaline earth metal salt such as calcium hypochlorite.

Examples of the compound capable of generating hypochlorous acid include trichloroisocyanuric acid (TCCA), trichloroisocyanurates such as sodium trichloroisocyanurate, N-chlorosuccinimide, N-chlorophthalimide, alkali metal salts such as sodium hypochlorite, alkaline earth metal salts such as calcium hypochlorite, chlorous acid, alkali metal salts such as sodium chlorite, alkaline earth metal salts such as calcium chlorite, chlorine dioxide, chlorine, etc. Among these, trichloroisocyanuric acid (TCCA) is preferred.
The compound (Z) may be used alone or in combination of two or more kinds.
Among the above compounds (Z), hypochlorous acid, hypochlorites, and trichloroisocyanuric acid (TCCA) are more preferred, and trichloroisocyanuric acid (TCCA) is even more preferred.

<Oxidation reaction>
The oxidation reaction in the oxidation step is preferably carried out in a solvent. The solvent used in the oxidation reaction is also referred to as an oxidation reaction solvent.
Preferred examples of the oxidation reaction solvent include chlorinated hydrocarbons such as chloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, tetrachloroethylene, 1,1,2,2-tetrachloroethane, chlorobenzene, 1,2-dichlorobenzene, and 1,3-dichlorobenzene; ethers such as tetrahydrofuran, diethyl ether, and cyclopentyl methyl ether; amide solvents such as N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylformamide; organic solvents such as esters such as ethyl acetate; and water, and one or more of these can be used. Among these, ethers are more preferred, and tetrahydrofuran is even more preferred.

On the other hand, the oxidation reaction is preferably carried out in the presence of water, since the presence of water accelerates the oxidation reaction and enables the oxidation reaction to be completed in a short time even at a low temperature.
Therefore, the oxidation reaction solvent is preferably a mixed solvent of an organic solvent and water. The content of water is not particularly limited, but it is preferable that the content of water is 1 to 30 mass% relative to 100 mass% of the total amount of the oxidation reaction solvent (mixed solvent). It is more preferable that the content of water is 2 mass% or more, even more preferable that the content of water is 5 mass% or more, more preferably that the content of water is 20 mass% or less, and even more preferable that the content of water is 15 mass% or less.

In the oxidation step, it is preferable to mix the compound (Z) with the sulfide-containing polymer. When mixing, the compound (Z) may be used as is, or may be dissolved or dispersed in a solvent.

For example, when hypochlorous acid or a hypochlorite is used as compound (Z), it is preferable to use an aqueous solution containing these. As the aqueous hypochlorous acid (salt) solution, an aqueous sodium chloride solution, hydrochloric acid water, or hypochlorous acid water containing hypochlorous acid as the main component, obtained by electrolyzing a mixture of hydrochloric acid and sodium chloride, can also be used.

In addition, when mixing the above-mentioned compound capable of generating hypochlorous acid with the sulfide-containing polymer, the compound may be used as is, or the compound may be dissolved or dispersed in a solvent.

When mixing with the compound (Z), it is preferable that the sulfide-containing polymer is dispersed or dissolved in a solvent in advance. That is, it is preferable to mix the compound (Z) with a solution in which the sulfide-containing polymer is dissolved in a solvent or a dispersion in which the sulfide-containing polymer is dispersed. As the solvent, a solvent similar to the oxidation reaction solvent used in the oxidation reaction can be used.

The average particle size of the sulfide-containing polymer in the dispersion is preferably 100 μm or less, since it is easy to obtain a sulfoxide-containing polymer with a uniform degree of oxidation. The average particle size is more preferably 10 μm or less, and even more preferably 1 μm or less. There is no particular upper limit, but it is preferably 0.001 μm or more, and more preferably 0.01 μm or more. The average particle size is the 50% particle size in the volume-based particle size distribution, and can be measured by dynamic light scattering or static light scattering.

When water is contained in the oxidation reaction solvent, the sulfide-containing polymer may be added to a mixed solvent of an organic solvent and water and dispersed or dissolved in the mixed solvent, or the sulfide-containing polymer may be added to an organic solvent and dispersed or dissolved therein, and then water may be added.

The concentration of the sulfide-containing polymer in the solution is not particularly limited, but the content of the sulfide-containing polymer relative to 100% by mass of the solution is preferably 0.01 to 99.9% by mass, more preferably 0.1 to 80% by mass, and even more preferably 1 to 50% by mass.
The same applies to the concentration of the sulfide-containing polymer in the dispersion.

The mixing ratio of the compound (Z) to the sulfide-containing polymer is not particularly limited, but is usually preferably 0.01 to 100 moles, more preferably 0.1 to 10 moles, and even more preferably 0.1 to 3 moles, expressed as the amount (mol) of compound (Z) per mole of sulfur atoms in the sulfide-containing polymer.

The amount of hypochlorous acid generated from the compound (Z) is preferably 0.01 to 100 moles, more preferably 0.1 to 10 moles, and even more preferably 0.1 to 3 moles, expressed as the amount (mol) of hypochlorous acid generated from the compound (Z) per mole of sulfur atoms in the sulfide-containing polymer.

The reaction temperature of the above oxidation reaction is not particularly limited as long as it is a temperature at which the desired oxidation reaction proceeds, but from the viewpoint of facilitating the above oxidation reaction, it is preferably -20 to 200°C, more preferably 0°C or higher, and even more preferably 5°C or higher, and from the viewpoint of suppressing side reactions, it is more preferably 100°C or lower, and even more preferably 50°C or lower. The reaction time of the above oxidation reaction is not particularly limited, but is usually 0.1 to 100 hours, preferably 0.5 to 20 hours, more preferably 1 hour or more, and from the viewpoint of excellent productivity, it is more preferably 10 hours or less, and even more preferably 5 hours or less.

When a portion of the sulfide groups (-S-) in the sulfide-containing polymer are oxidized to sulfonyl groups (-SO ₂ -), the reaction may be carried out for a longer time than the above-mentioned reaction time. In this case, the amount of compound (Z) used is not particularly limited as long as the oxidation reaction of the desired sulfur atoms proceeds, but is usually preferably 1.5 to 100 mol, more preferably 2 to 50 mol, and even more preferably 2 to 10 mol, per mol of sulfur atoms in the sulfide-containing polymer.

The sulfoxide-containing polymer obtained by the oxidation step may contain residual acid, so it is preferable to wash it. The washing method is not particularly limited, and examples include washing methods using water, acid, base, etc. In addition, in order to remove unreacted substances, the polymer may be passed through a filter or washed with a solvent. The solvent is not particularly limited, but the same solvent as the reaction solvent can be used.

In the oxidation step, the use of the compound (Z) as an oxidizing agent is also one of the preferred embodiments of the production method of the present invention.
In the oxidation step, an oxidizing agent other than the compound (Z) can be used. The oxidizing agent is not particularly limited as long as it is a substance having oxidizing properties, and preferred examples thereof include nitric acid, dinitrogen tetroxide, nitrogen dioxide, sulfuric acid, hydrogen peroxide, ozone, and mixtures thereof, and one or more of them can be appropriately selected and used.

When an oxidizing agent other than the compound (Z) is used, it is preferable that the amount used is within a range that does not impair the effects of the present invention. For example, the total amount of oxidizing agents other than the compound (Z) relative to 100% by mass of the amount of compound (Z) used in the oxidation step is preferably 0 to 20% by mass, more preferably 0 to 5% by mass, and even more preferably 0 to 1% by mass. In addition, when it is desired to exert the effects of using an oxidizing agent other than the compound (Z), the total amount of oxidizing agents other than the compound (Z) relative to 100% by mass of the amount of compound (Z) used may be more than 20% by mass.

<Polymer End Control Step>
The production method of the present invention preferably further includes a terminal control step in which a reaction is carried out to control the polymer terminals. The sulfoxide-containing polymer obtained by the oxidation step has terminals that have, for example, a sulfonyl chloride structure (-S(=O) ₂ -Cl). By chemically modifying or altering the terminal structure, it is possible to improve the solubility or transmittance, or to impart new functions to the terminals.
Controlling the polymer terminals means controlling the terminals of the sulfoxide-containing polymer obtained by the oxidation reaction to have any structure. The reaction for controlling the polymer terminals is sometimes called a terminal control reaction.

The terminal control step may be performed on the sulfide-containing polymer, on the sulfoxide-containing polymer, or during the oxidation step. That is, it may be performed before the oxidation step, after the oxidation step, or simultaneously with the oxidation step.

Among these, it is preferable to carry out the polymer end control step after the oxidation step or simultaneously with the oxidation step, and it is preferable to start the end control reaction in the polymer end control step after the oxidation reaction in the oxidation step has started. That is, it is preferable to start the oxidation reaction first and then carry out the end control reaction after the oxidation reaction is completed or after the oxidation reaction has progressed to a certain extent.
The above-mentioned terminal control reaction is preferably carried out in a solvent, and the solvent may be the same as that used in the above-mentioned oxidation reaction.

The terminal control step is preferably a step using a reducing substance.
By using a reducing substance, for example, at least one end of the sulfoxide-containing polymer can be controlled to have a structure having a thiol group. Furthermore, by making the end a thiol group, it can be modified with a compound containing an ethylenically unsaturated double bond, and various functional groups can be introduced.

The reducing substance is not particularly limited, but preferred examples thereof include metal or semimetal hydrides and their complex compounds (ate complexes) such as sodium hydride, sodium borohydride, lithium aluminum hydride, butyl lithium, diborane, sodium cyanoborohydride, lithium triethylborohydride, lithium tri(sec-butyl)borohydride, potassium tri(sec-butyl)borohydride, diisobutylaluminum hydride, sodium bis(2-methoxyethoxy)aluminum hydride, tributyltin hydride, lithium hexamethyldisilazide, and lithium diisopropylamide; metals such as metallic tin and metallic zinc; compounds containing low-valent metal ions such as divalent iron ions and divalent tin ions; acid-based organic compounds such as formic acid and oxalic acid; phosphine-based organic compounds such as triphenylphosphine; and inorganic compounds such as hydrazine. One or more of these can be used. Among these, metals are preferred, and zinc is more preferred. When zinc is used, even if a heavy metal used as a catalyst or the like remains in the process of producing a sulfoxide-containing polymer, for example, in the process of producing a sulfide-containing polymer, the heavy metal can be removed, and a sulfoxide-containing polymer with reduced coloration can be easily obtained.
When a metal is used as the reducing substance, the form of the metal is not particularly limited, but it is preferably in the form of fine particles.

The terminal control reaction using the reducing substance is preferably carried out in the presence of an acid. By carrying out the reaction in the presence of an acid, the terminal control reaction to convert the terminal structure into a thiol can be promoted. This effect is more pronounced when a metal is used as the reducing substance, particularly when zinc is used. Examples of the acid include inorganic acids such as hydrohalic acids such as hydrochloric acid (hydrochloric acid), hydrobromic acid, hydroiodic acid, and hydrofluoric acid, sulfuric acid, and nitric acid; carboxylic acids such as formic acid, acetic acid, propionic acid, lauric acid, stearic acid, and benzoic acid; and sulfonic acids such as p-toluenesulfonic acid. Of these, hydrochloric acid is preferred.

The amount of the reducing substance used is not particularly limited, but it is preferable to use 0.01 to 1000% by mass of the reducing substance relative to 100% by mass of the sulfide-containing polymer. More preferably, it is 0.1% by mass or more, and even more preferably, it is 5% by mass or more, and more preferably, it is 100% by mass or less, and even more preferably, it is 50% by mass or less.

The amount of the acid used is not particularly limited, but it is preferable to use 0.01 to 5000% by mass of the acid relative to 100% by mass of the sulfide-containing polymer. More preferably, it is 0.5% by mass or more, even more preferably 10% by mass or more, and more preferably, it is 500% by mass or less, even more preferably, it is 100% by mass or less.

By using a reducing substance to perform an end-control reaction, it is possible to obtain, for example, a sulfoxide-containing polymer having a thiol group at the polymer end, and the polymer can be subjected to an enethiol reaction with, for example, a compound containing an ethylenically unsaturated double bond. By this reaction, it is possible to obtain a sulfoxide-containing polymer into which a functional group possessed by the compound has been introduced.

The above-mentioned compound containing an ethylenically unsaturated double bond is not particularly limited, but preferred examples include (meth)acrylic monomers such as (meth)acrylic acid and (meth)acrylic acid esters; vinyl monomers such as vinyl acetate, vinyl chloride, and vinylidene fluoride; allyl monomers such as allyl acetate, allyl chloride, allyl alcohol, allyl ether, and allyl cyanide; olefin monomers such as ethylene, propylene, pentene, hexene, cycloheptene, cyclohexene, 2-norbornene, and 2-cyclohexen-1-one; and styrene monomers such as styrene and divinylbenzene. Of these, one or more types can be used. Among them, (meth)acrylic monomers are preferred in that compounds having various functional groups are easily available industrially.

For example, by using (meth)acrylic acid as a compound containing an ethylenically unsaturated double bond, a carboxy group can be introduced to the polymer end, by using an alkyl (meth)acrylate ester, an alkyl group can be introduced to the polymer end, and by using a polyfunctional alkyl (meth)acrylate ester, an ethylenically unsaturated double bond ((meth)acryloyl group) can be introduced to the polymer end.

It is also preferable that the terminal control step is a step using ammonia, a primary amine, or a secondary amine. By using ammonia, a primary amine, or a secondary amine, at least one terminal of the sulfoxide-containing polymer can be controlled to "-S(=O)2-R". Here, R is _NH2 when ammonia is used, and is an amine residue resulting from the removal of hydrogen from the amino group in the amine used when an amine is used.

In the above terminal control step, it is also preferable to use a basic substance. That is, in the above terminal control step, it is preferable to react ammonia, a primary amine, or a secondary amine with the sulfoxide-containing polymer in the presence of a basic substance.

The basic substance is not particularly limited. For example, it may be ammonia, a primary amine, or a secondary amine, or it may be a basic substance other than these. For example, ammonia, a primary amine, or a secondary amine in an amount exceeding the equivalent amount for modifying the terminal may be used as the basic substance. However, because it is possible to suppress side reactions, a substance other than ammonia, a primary amine, or a secondary amine is preferable as the basic substance. For example, a tertiary amine, an alkali metal hydroxide, an alkali metal carbonate, etc. are preferable. As the tertiary amine, aliphatic tertiary amines such as triethylamine, tributylamine, and diisopropylethylamine, and aromatic amines such as pyridine and dimethylaminopyridine are preferable. As the alkali metal hydroxide, lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, etc. are preferable. As the alkali metal carbonate, lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, cesium hydrogen carbonate, etc. are preferable.

<Polymerization process>
The production method of the present invention preferably further includes a polymerization step of polymerizing a monomer component containing a sulfur-containing monomer to obtain a sulfur-containing polymer (sulfide-containing polymer) having a sulfide skeleton in the main chain. That is, in the production method of the present invention, it is preferable to use a sulfide-containing polymer obtained by polymerizing a monomer component containing a sulfur-containing monomer as the sulfide-containing polymer used in the oxidation step. The polymerization step is usually preferably carried out before the oxidation step.

The sulfur-containing monomer is not particularly limited as long as it is a monomer that can be polymerized to give the sulfur-containing polymer having a sulfide skeleton in the main chain. Disulfide compounds and thiol compounds are preferred, and diaryl disulfide compounds represented by the following general formula (4) and thioaryl compounds represented by the following general formula (5) are more preferred.

(In formulas (4) and (5), A ¹ and A ² are the same or different and each represents a monovalent aromatic hydrocarbon group which may have a substituent.)
The monovalent aromatic hydrocarbon group represented by ^A1 and ^A2 may be an aromatic hydrocarbon group obtained by converting the divalent aromatic hydrocarbon group represented by ^X1 in the general formula (1) into a monovalent group, such as a phenyl group, a naphthyl group, an anthryl group, a triphenyl group, a biphenyl group, a phenanthryl group, etc. Among these, a phenyl group, a naphthyl group, an anthryl group, a biphenyl group, or a triphenyl group is preferred, and a phenyl group is more preferred.

The substituents that the monovalent aromatic hydrocarbon groups represented by ^A1 and ^A2 may have and the number of the substituents are the same as those of the divalent aromatic hydrocarbon group represented by ^X1 in the general formula (1).

The diaryl disulfide compound is preferably a compound represented by the following general formula (4-1). The thioaryl compound is preferably a compound represented by the following general formula (5-1).

(In formulas (4-1) and (5-1), R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are the same or different and each represents a hydrogen atom, a halogen atom, a reactive functional group, or an alkyl group, alkoxy group, aryl group, aralkyl group, or sulfur-containing substituent group which may have a substituent.)
The halogen atom, reactive functional group, or optionally substituted alkyl group, alkoxy group, aryl group, aralkyl group, or sulfur-containing substituent is the same as each group represented by R ¹ in the above-mentioned general formula (1-1). Examples of the substituent that these groups may have include the same as the above-mentioned substituent B, and among them, an alkyl group, a halogen atom, or a hydroxyl group is preferable.

Specific examples of the diphenyl sulfide compounds include 3,3'-dimethyldiphenyl disulfide, 2,2'-dimethyldiphenyl disulfide, 2,2',3,3'-tetramethyldiphenyl disulfide, 2,2',5,5'-tetramethyldiphenyl disulfide, 2,2',6,6'-tetramethyldiphenyl disulfide, 3,3',5,5'-tetramethyldiphenyl disulfide, 2,2',3,3',5,5'-hexamethyldiphenyl disulfide, 2,2',3,3',6,6'-hexamethyldiphenyl disulfide, 2,2',3,3',5,5',6,6'-octamethyldiphenyl disulfide, Phenyl disulfide, 2,2'-diethyldiphenyl disulfide, 3,3'-diethyldiphenyl disulfide, 2,2',6,6'-tetraethyldiphenyl disulfide, 2,2',3,3'-tetraethyldiphenyl disulfide, 2,2',5,5'-tetraethyldiphenyl disulfide, 3,3',5,5'-tetraethyldiphenyl disulfide, 2,2',3,3',5,5'-hexaethyldiphenyl disulfide, 2,2',3,3',6,6'-hexaethyldiphenyl disulfide, 2,2',3,3',5,5',6,6'-octaethyldiphenyl disulfide, 2,2'-diphenyl propyldiphenyl disulfide, 3,3'-dipropyldiphenyl disulfide, 2,2',6,6'-tetrapropyldiphenyl disulfide, 2,2',3,3'-tetrapropyldiphenyl disulfide, 2,2',5,5'-tetrapropyldiphenyl disulfide, 3,3',5,5'-tetrapropyldiphenyl disulfide, 2,2',3,3',5,5'-hexapropyldiphenyl disulfide, 2,2',3,3',6,6'-hexapropyldiphenyl disulfide, 2,2',3,3',5,5',6,6'-octapropyldiphenyl disulfide, 2,2'-diisopropyldiphenyl disulfide, 3,3'-diisopropyldiphenyl disulfide, 2,2',6,6'-tetraisopropyldiphenyl disulfide, 2,2',3,3'-tetraisopropyldiphenyl disulfide, 2,2',5,5'-tetraisopropyldiphenyl disulfide, 3,3',5,5'-tetraisopropyldiphenyl disulfide, 2,2',3,3',5,5'-hexaisopropyldiphenyl disulfide, 2,2',3,3',6,6'-hexaisopropyldiphenyl disulfide, 2,2',3,3',5,5',6,6'-octaisopropyldiphenyl disulfide, etc.

Specific examples of the thiol compounds include 3-methylbenzenethiol, 2-methylbenzenethiol, thiophenol (benzenethiol), 2,3-dimethylbenzenethiol, 2,5-dimethylbenzenethiol, 2,6-dimethylbenzenethiol, and 3,5-dimethylbenzenethiol.

The disulfide compound can also be prepared by oxidation of a thiol compound. Therefore, in the polymerization step, a thiol compound can also be used as a precursor of the disulfide compound. A disulfide compound can be obtained by oxidatively bonding two molecules of a thiol compound. The method for oxidatively bonding is not particularly limited, and any known method can be used.

The polymerization is preferably oxidative polymerization. The oxidative polymerization is not particularly limited, and oxidative polymerization using a quinone compound or oxidative polymerization using a catalyst can be used. In the production method of the present invention, oxidative polymerization using a catalyst is preferred from the viewpoint of reducing the amount of waste liquid. In addition, whether oxidative polymerization using a quinone compound or oxidative polymerization using a catalyst is performed, by subjecting the obtained sulfide-containing polymer to the production method of the present invention described above, the obtained sulfoxide-containing polymer has excellent transmittance after heating.

For example, when a monomer composition containing a diaryl disulfide compound represented by the above general formula (4) or a thioaryl compound represented by the above general formula (5) is used as a raw material and oxidative polymerization is performed using a quinone compound, the resulting sulfide-containing polymer has a problem with transmittance after heating. The reason for this is unclear, but it is thought that the sulfide-containing polymer obtained by oxidative polymerization using the above quinone compound has a disulfide bond at its end, and the disulfide bond generates radicals when heated, which causes a reaction that causes coloring of the polymer. However, by subjecting the sulfide-containing polymer to the manufacturing method of the present invention described above (the oxidation step), the resulting sulfoxide-containing polymer has excellent transmittance after heating. It is thought that this is because the structure of the terminal of the polymer changes due to the oxidation step.

In addition, when a monomer composition containing a diaryl disulfide compound represented by the above general formula (4) or a thioaryl compound represented by the above general formula (5) is used as a raw material and oxidative polymerization using a catalyst is performed, the resulting sulfide-containing polymer has a problem with transmittance after heating, although there are differences depending on the composition of the catalyst used. The same is true even if the polymer is purified by a method such as reprecipitation or filtration. Although the cause is unclear, it is thought that this is because the sulfide-containing polymer obtained by oxidative polymerization using a catalyst has disulfide bonds at its terminals, and the metal components derived from the catalyst are strongly bonded (coordinated) to the disulfide bonds, which easily contribute to coloring due to heating.

However, by subjecting the sulfide-containing polymer to the manufacturing method of the present invention (the oxidation step) described above, the resulting sulfoxide-containing polymer has excellent transmittance after heating. The oxidation step changes the structure of the polymer's terminals, and although it is not clear, it is thought that this is because the metal components derived from the catalyst are liberated from the sulfoxide-containing polymer or are changed to a form that is less likely to contribute to coloring by heating.

Oxidative polymerization using a quinone compound will now be described. The quinone compound that can be used in oxidative polymerization using a quinone compound is not particularly limited, but examples include 2,3-dichloro-5,6-dicyano-parabenzoquinone (DDQ), 2,3,5,6-tetrachloroparabenzoquinone, 2,3,5,6-tetrabromobenzoquinone, 2,3,5,6-tetrafluoroparabenzoquinone, anthraquinone, 1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2,3-dibromo-1,4-naphthoquinone, 2,3-dicyano-1,4-naphthoquinone, 3,4,5,6-tetrachloroorthobenzoquinone, 3,4,5,6-tetrabromoorthobenzoquinone, and 3,4,5,6-tetrafluorobenzoquinone. Among these, DDQ is preferred because of its high oxidative power and ease of availability. The above quinone compounds may be used alone or in combination.

When using the quinone compound, it is also preferable to further use an acid. When an acid is used in combination with the quinone compound, the oxidizing power of the quinone compound can be maintained. The acid is not particularly limited, and examples thereof include sulfuric acid, acetic acid, methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, trifluoromethanesulfonic acid, 1,1,2,2-tetrafluoroethanesulfonic acid, trifluoroacetic acid, perfluoropropionic acid, and perfluorobutyric acid. Among these, 1,1,2,2-tetrafluoroethanesulfonic acid is preferable in terms of increasing the acidity. The above acids may be used alone or in combination of two or more.

When the quinone compound and the acid are used in combination, the amount of the acid added is preferably 10 to 1000 moles, more preferably 50 to 500 moles, and even more preferably 80 to 120 moles, per 100 moles of the total amount of the quinone compound added. The amount of the quinone compound added is preferably 0.1 to 3 moles, more preferably 0.8 to 1.5 moles, and even more preferably 0.9 to 1.1 moles, per 1 mole of the monomer component used.

In the above polymerization step, the polymerization temperature is not particularly limited as long as it is a temperature at which oxidative polymerization proceeds, but it is preferably 0 to 200°C in terms of facilitating the oxidative polymerization, more preferably 10°C or higher, and even more preferably 15°C or higher, and is more preferably 180°C or lower, and even more preferably 150°C or lower, in terms of being able to suppress side reactions. The polymerization time is not particularly limited, but is usually 0.1 to 100 hours, preferably 1 to 80 hours, more preferably 5 to 50 hours, and even more preferably 10 to 24 hours.

A solvent may be used in the above polymerization. Preferred solvents include, for example, dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, tetrachloroethylene, 1,1,2,2-tetrachloroethane, nitromethane, nitrobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, N-methylpyrrolidone, tetrahydrofuran, ethyl acetate, and cyclopentyl methyl ether.

As the above-mentioned solvent, it is preferable to reduce halogen-based solvents such as chloroform and chlorobenzene, which are highly environmentally harmful, particularly those containing chlorine and bromine, and the amount of these solvents used after the step of synthesizing the polymer is preferably 100% by mass or less, more preferably 50% by mass or less, even more preferably 10% by mass or less, and even more preferably 1% by mass or less, based on the polymer.

The oxidation polymerization using a catalyst will be described. In the polymerization step, the monomer component is polymerized in the presence of a catalyst. For example, it is more preferable to carry out the polymerization reaction by heating a composition containing the monomer component and the catalyst.
A composition containing a monomer component and a catalyst is also called a raw material composition, a composition from the start of a polymerization reaction to the end of the polymerization reaction is also called a reaction composition, and a composition obtained by a polymerization reaction is also called a polymer composition.

The catalyst is preferably a catalyst (oxidative polymerization catalyst) that has oxidative polymerization activity for the monomer components containing the disulfide compound and/or thiol compound. The catalyst is not particularly limited, but is preferably a substance containing a metal element such as vanadium (V), zirconium (Zr), titanium (Ti), cobalt (Co), nickel (Ni), manganese (Mn), or iron (Fe). The form of the substance containing a metal is not particularly limited, but examples include metals, metal compounds, and other forms containing the metal element.

The above metals include metals (simple substances) consisting of the metals alone, and alloys mainly composed of the metals. The above metal compounds are not particularly limited as long as they are compounds containing metals, and include inorganic compounds, organic acid salts, complexes (coordination compounds), and the like. The above inorganic compounds include, for example, halides, sulfates, nitrates, phosphates, silicates, carbonates, hydroxides, oxides, sulfides, tellurides, intermetallic compounds, and the like. Among these, halides are preferred. The above halides are preferably fluorides, chlorides, bromides, and iodides, and more preferably chlorides. The above organic acid salts are not particularly limited as long as they are organic acid salts containing metal elements, and include, for example, carboxylates, sulfonates, and the like. The above carboxylates are preferably, for example, acetates, oxalates, and the like. The above sulfonates are preferably, for example, paratoluenesulfonates, trifluoromethanesulfonates, and the like. The above complex is not particularly limited as long as it contains a metal element, but examples include ammine complexes, cyano complexes, halogeno complexes, hydroxy complexes, phthalocyanine complexes, porphyrin complexes, carbonyl complexes, salen complexes, ethylenediamine complexes, β-diketone complexes, and β-diketoester complexes.

Other examples of the above-mentioned forms of substances containing the above-mentioned metal elements include forms in which metal ions such as monovalent or trivalent metal ions are contained as cations in cation exchangers such as zeolite or mica.

The above-mentioned substances containing metal elements may be used alone or in combination of two or more kinds.
The substance containing the metal element is not particularly limited in its form in the raw material composition. For example, it may be dispersed in the raw material composition in a particulate form or the like, or may be present in a monomer component or in a solvent when a solvent is used. The solvent will be described later. The same applies to the form of the substance containing the metal element in the reaction composition.

Among the substances containing the above metal elements, substances containing vanadium as a metal element and substances containing iron (also referred to as vanadium-containing substances and iron-containing substances, respectively) are preferred because of their high catalytic activity for oxidative polymerization.

The iron-containing material preferably contains iron as a main component as a metal element. Specifically, the iron content relative to the total content of metal elements contained in the iron-containing material (100 mol%) is preferably 50 mol% or more, more preferably 80 mol% or more, even more preferably 95 mol% or more, even more preferably 98 mol% or more, and particularly preferably 100 mol%.

The vanadium-containing material preferably contains vanadium as a main component as a metallic element, and the preferred content of vanadium relative to the total amount of metallic elements is the same as the preferred content of iron in the iron-containing material.
The specific and preferred forms of the vanadium-containing substance and the iron-containing substance are similar to the forms described above for the substances containing the above metal elements.

The iron-containing substance is preferably an iron compound having chlorine in the molecule. Also, a compound containing iron with an oxidation number of 3 or more is preferable. Particularly preferable examples of such iron-containing substances include ferric chloride (Fe(Cl) ₃ ), 5,10,15,20-tetraphenyl-21H,23H-porphine iron chloride (III), and iron trifluoromethanesulfonate (III).

The vanadium-containing substance is preferably a metal containing vanadium, or an oxovanadium compound having a V=O bond in the vanadium compound molecule. Examples of the oxovanadium compound include vanadyl acetylacetonate, oxovanadium salen complex, N,N'-bissalicylideneethylenediamine oxovanadium, phthalocyanine oxovanadium, and tetraphenylporphyrin oxovanadium. The amount of the catalyst used in the polymerization is not particularly limited, but the total content of the metal elements contained in the catalyst relative to 100 mol% of the monomer component is preferably in the range of 0.001 to 50 mol%, and from the viewpoint of easily obtaining a sulfur-containing polymer with a high molecular weight and/or from the viewpoint of easily achieving removal of catalyst residues by a simple purification process, it is preferably 30 mol% or less, more preferably 10 mol% or less, and even more preferably 5 mol% or less, and from the viewpoint of increasing the polymerization reactivity, it is more preferably 0.01 mol% or more, even more preferably 0.1 mol% or more, and particularly preferably 1 mol% or more.

The polymerization is preferably carried out in the presence of oxygen. By carrying out the polymerization in the presence of oxygen, the oxidative polymerization reaction is further promoted. As a specific embodiment, a method of supplying an oxygen-containing gas during the polymerization reaction is preferred. That is, the polymerization is preferably carried out under the supply of an oxygen-containing gas. For example, a method of supplying an oxygen-containing gas to the gas phase during the polymerization reaction, a method of bubbling an oxygen-containing gas into the reaction composition during the polymerization reaction, etc. are adopted.

It is believed that by carrying out the above polymerization reaction in the presence of oxygen gas, it is possible to promote the hydrogen elimination reaction from the carbon constituting the aromatic ring contained in the monomer component. In addition, in the above polymerization step, the oxidation number of the metal contained in the catalyst can usually change, but by carrying out the polymerization reaction in the presence of oxygen gas, it is possible to maintain the valence of the metal contained in the catalyst at a high oxidation number, and therefore it is believed that the oxidative polymerization can be further promoted. From this perspective, a method of continuously supplying an oxygen-containing gas to the reaction composition during the polymerization reaction is preferable, and among these, a bubbling method is preferable.

The oxygen-containing gas is preferably a gas containing oxygen molecules (O ₂ ). The oxygen-containing gas may contain gas components other than oxygen molecules (O ₂ ). The gas components other than oxygen molecules (O ₂ ) contained in the oxygen-containing gas are not particularly limited, but preferably include rare gases such as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn); and inert gases such as nitrogen (N ₂ ). In addition to the inert gases, carbon dioxide gas (CO ₂ ), water vapor, etc. may be contained.

The content of oxygen molecules (O ₂ ) in the oxygen-containing gas is not particularly limited, but at room temperature (25° C.) and 1 atmospheric pressure, the volume ratio of oxygen molecules (O ₂ ) in the oxygen-containing gas is preferably 0.1 to 100 volume % relative to 100 volume % of the oxygen-containing gas. More preferably, it is 1 volume % or more, and even more preferably, it is 10 volume % or more. The upper limit is more preferably 60 volume % or less, and even more preferably, it is 30 volume % or less.

The total content of oxygen molecules (O ₂ ) and inert gas in the oxygen-containing gas is not particularly limited, but at room temperature (25° C.) and 1 atmospheric pressure, the total volume ratio of oxygen molecules (O ₂ ) and inert gas in the oxygen-containing gas is preferably 80 to 100% by volume relative to 100% by volume of the oxygen-containing gas, more preferably 95% by volume or more, and even more preferably 98% by volume or more.

The oxygen-containing gas is not particularly limited, and examples thereof include oxygen gas, a mixed gas of oxygen and nitrogen, air, etc. From the viewpoint of excellent economy, it is preferable to use air.
The water vapor concentration in the oxygen-containing gas is not particularly limited, but is preferably 1000 g/m3 or ^less , more preferably 10 g/ ^m3 or less, even more preferably 1 g/ ^m3 or less, and most preferably 0.1 g/ ^m3 or less, and dry air is preferred.

The supply amount of the oxygen-containing gas is not particularly limited, but is preferably 0.0001 m ³ /min to 10 m ³ /min in terms of the supply amount per minute (supply rate) per m ³ of the total volume of the reaction composition. From the viewpoint of increasing the reaction rate, it is more preferably 0.0005 m ³ /min or more, and even more preferably 0.001 ^{m 3} /min or more. From the viewpoint of easy control of the reaction temperature, the upper limit is more preferably 1 m ³ /min or less, and even more preferably 0.1 m ³ /min or less.

The supply amount of the oxygen-containing gas is not particularly limited, but is preferably 0.00002 ^{m 3 /} min to 2 m 3 /min in terms of the supply amount (supply rate) of oxygen (O ₂ ) per minute per m 3 of total volume of the reaction composition. From the viewpoint of increasing the reaction rate, it is more preferably 0.0001 m ³ /min or more, and even more preferably 0.0002 ^{m 3 /} min or more. From the viewpoint of easy control of the reaction temperature, the upper limit is more preferably 0.2 m ³ /min or less, and even more preferably 0.02 m ³ /min or less.

In the above polymerization step, it is preferable to further use an acid and/or a salt thereof. By using an acid and/or a salt thereof in combination with the above catalyst, it becomes easier to control the molecular weight of the polymer obtained by the polymerization reaction to a high range, and it becomes easier to obtain a high molecular weight sulfide-containing polymer even in a short period of time.

The above acid is preferably a Bronsted acid. Examples include inorganic acids such as phosphoric acid, phosphonic acid, nitric acid, hydrochloric acid, hydrobromic acid, sulfuric acid, persulfuric acid, and sulfurous acid; sulfonic acids such as methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, 10-camphorsulfonic acid, trifluoromethanesulfonic acid, and 1,1,2,2-tetrafluoroethanesulfonic acid; and carboxylic acids such as acetic acid, trifluoroacetic acid, perfluoropropionic acid, perfluorobutyric acid, and benzoic acid.

The acid is preferably one having an acid dissociation constant of -19 to 4. More preferably, the acid dissociation constant is 3 or less and -8 or more.

The salt of the above acid is not particularly limited as long as it is a salt of the above acid, but for example, salts of the above acid with metal elements of Group 1 of the periodic table such as sodium and potassium, metal elements of Group 2 of the periodic table such as magnesium and calcium, and ammonium are preferred. Among these, for example, sodium persulfate, ammonium persulfate, sodium toluenesulfonate, sodium trifluoromethanesulfonate, etc. are preferred. The salt of the above acid preferably has a pH of 1 to 6.9, more preferably 2 to 6, at 25°C when dissolved in pure water.

Examples of acids with an acid dissociation constant of -19 to 4 include inorganic acids such as phosphoric acid, nitric acid, sulfuric acid, persulfuric acid, sulfurous acid, hydrochloric acid, and hydrobromic acid; sulfonic acids such as methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, 10-camphorsulfonic acid, trifluoromethanesulfonic acid, and 1,1,2,2-tetrafluoroethanesulfonic acid; chlorocarboxylic acids such as chloroacetic acid, dichloroacetic acid, and trichloroacetic acid; and fluorocarboxylic acids such as fluoroacetic acid, difluoroacetic acid, trifluoroacetic acid, perfluoropropionic acid, perfluorobutyric acid, and 4-fluorobenzoic acid. Of these, 10-camphorsulfonic acid, trifluoromethanesulfonic acid, and persulfuric acid are preferred. The above acids and/or salts thereof may be used alone or in combination of two or more.

The amount of the acid and/or its salt used is preferably 0.01 to 100 mol %, more preferably 0.1 to 10 mol %, and even more preferably 0.5 to 5 mol %, based on 100 mol % of the monomer component.
The amount of the acid and/or its salt used is preferably 0.1 to 1000 mol %, more preferably 1 to 100 mol %, and even more preferably 5 to 50 mol %, relative to 100 mol % of the total amount of metal elements contained in the substance containing metal elements.

The pH of the entire reaction system (raw material composition containing the acid and/or its salt) to which the above acid and/or its salt has been added is preferably 0.1 to 7, more preferably 1 to 6, and most preferably 2 to 5, from the viewpoint of improving reaction efficiency. The pH is the value measured when the reaction system (raw material composition containing the acid and/or its salt) is directly measured, and is measured using pH test paper and a pH measuring device.

In the above polymerization step, the polymerization temperature is not particularly limited as long as it is a temperature at which polymerization, preferably oxidative polymerization, proceeds, but is preferably 0 to 300°C in terms of facilitating the progression of oxidative polymerization, more preferably 10°C or higher, and even more preferably 100°C or higher, and is more preferably 200°C or lower, and even more preferably 180°C or lower, in terms of being able to suppress side reactions. The polymerization time is not particularly limited, but is usually 0.1 to 300 hours, preferably 1 to 200 hours, more preferably 5 to 100 hours, and even more preferably 10 to 50 hours.

The polymerization reaction can be carried out with the monomer components in a molten state, or with the monomer components dissolved or dispersed in a solvent. When carried out in a molten state, it is preferable to set the polymerization temperature at a temperature equal to or higher than the melting point of the monomer components. In this case, it is preferable to heat the raw material composition and carry out the polymerization reaction while maintaining the temperature of the reaction composition at a temperature equal to or higher than the melting point of the monomer components.

When the monomer components are dissolved or dispersed in a solvent, the polymerization may be carried out at a temperature below the boiling point of the solvent, under reflux conditions, or under pressure while being heated to a temperature above the boiling point.

The above solvent is not particularly limited, but preferred solvents include, for example, dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, tetrachloroethylene, 1,1,2,2-tetrachloroethane, nitromethane, nitrobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, N-methylpyrrolidone, tetrahydrofuran, ethyl acetate, cyclopentyl methyl ether, etc. The amount of the above solvent used is not particularly limited, but is preferably 1 to 10,000 parts by mass, and more preferably 10 to 1,000 parts by mass, per 100 parts by mass of the above monomer component as the raw material.

In the above polymerization, the monomer components may be added sequentially during the polymerization reaction. In the above polymerization step, the polymerization may be performed in multiple stages, such as by oxidatively polymerizing the above-mentioned thiol compound to obtain a disulfide compound, and then oxidatively polymerizing the obtained disulfide compound.

By maintaining a composition (raw material composition) containing the monomer components and the catalyst at the polymerization temperature for the polymerization time, a polymerization reaction of the monomer components occurs, a sulfur-containing polymer (sulfide-containing polymer) is produced, and a polymer composition containing at least the polymer (sulfide-containing polymer) and the catalyst is obtained.

The production method of the present invention is characterized by having the oxidation step, but as described above, it is preferable to have the polymer end control step, and it is also preferable to have the polymerization step. The most preferred embodiment of the production method of the present invention is a production method comprising the polymerization step, the oxidation step, and the polymer end control step. For example, it is a production method comprising the following steps (1) to (3).
(1) Polymerization step: A monomer component containing a sulfur-containing monomer is polymerized to obtain a sulfur-containing polymer having a sulfide skeleton in the main chain (sulfide-containing polymer).
(2) Oxidation step: The sulfide-containing polymer is oxidized to obtain a sulfoxide-containing polymer.
(3) Polymer end control step: A reaction for controlling the polymer ends is carried out.

Here, as described above, it is preferable that the polymerization step (1) is carried out before the oxidation step (2), and the timing of carrying out the polymer end control step (3) is as described above. In particular, it is preferable that the polymer end control step (3) is carried out after the oxidation step (2) or simultaneously with the oxidation step (2), and it is preferable to start the end control reaction in the polymer end control step after the oxidation reaction in the oxidation step has started. In other words, it is preferable to start the oxidation reaction first, and then carry out the end control reaction after the oxidation reaction has been completed or after the oxidation reaction has progressed to a certain extent.

<Purification process>
The production method of the present invention preferably has a purification step in addition to the oxidation step, and more preferably has a purification step in addition to the oxidation step, the polymer end control step, and the polymerization step. When oxidative polymerization using a catalyst is performed in the polymerization step, the metal components contained in the metal compound used as the catalyst are likely to cause coloring, depending on the type of metal, and are therefore desirably removed. However, the metal components are strongly coordinated to the ends of the polymer (sulfide-containing polymer), making them difficult to remove.

Even if the polymer (sulfide-containing polymer) contains a metal component, by subjecting it to the oxidation process of the present invention, not only the sulfur atoms in the main chain of the polymer are oxidized but also the terminal structure is changed, so that the coordination force of the sulfur atoms in the polymer to the metal component is reduced, making it easier to remove.

Therefore, as the purification method, a conventionally known purification method can be used. For example, it is preferable to use a reprecipitation method. The reprecipitation method is not particularly limited, but for example, a method in which a composition containing a polymer such as a sulfide-containing polymer or a sulfoxide-containing polymer is dropped into hydrochloric acid acidified methanol to precipitate the polymer, which is then filtered to obtain a precipitate, and the obtained precipitate is washed with water or a lower alcohol such as methanol, etc. It is preferable to remove components derived from the compound (Z) used in the oxidation step by the above purification method.

In the purification step, a method using a conventionally known adsorbent such as activated carbon can be used to remove components derived from the compound (Z) used in the oxidation step and impurity components derived from the polymerization step. It is also preferable to use the reprecipitation method and a method using an adsorbent in combination. The timing of the purification step is not particularly limited, and the purification step may be performed before the oxidation step, after the oxidation step, or after the polymer end control step. In other words, the sulfide-containing polymer obtained after the purification step may be subjected to the oxidation step, or the purification step may be performed on a composition containing the polymer (sulfoxide-containing polymer) obtained in the oxidation step or the polymer end control step.

Among these, it is preferable to carry out the purification step on a composition containing a polymer obtained after carrying out any of the polymerization step, the oxidation step, and the polymer end control step, in that a sulfoxide-containing polymer having fewer impurities derived from the raw materials used in each step can be obtained. For example, when the production method of the present invention has a polymer end control step, it is preferable to carry out purification on a composition containing a polymer (sulfoxide-containing polymer) obtained after carrying out the oxidation step and the polymer end control step, and when the production method of the present invention does not have a polymer end control step, it is preferable to carry out purification on a composition containing a polymer (sulfoxide-containing polymer) obtained after carrying out the oxidation step.

The manufacturing method of the present invention may include other steps in addition to the polymerization step, the oxidation step, the polymer end control step, and the purification step. Examples of the other steps include an aging step, a neutralization step, a dilution step, a drying step, a concentration step, a solvent replacement step, and a dissolution step. These steps can be carried out by known methods.

2. Regarding the sulfur-containing polymer obtained by the production method of the present invention The sulfur-containing polymer obtained by the production method of the present invention described above is a sulfur-containing polymer having a sulfoxide skeleton in the main chain (sulfoxide-containing polymer). Among the sulfur-containing polymers obtained by the production method of the present invention, preferred sulfoxide-containing polymers are described below.

The sulfoxide-containing polymer has excellent transmittance after heating. The transmittance after heating can be determined, for example, by the visible light transmittance after heating at 260°C. Specifically, a sample containing the sulfoxide-containing polymer is heated in air at 260°C for 10 minutes, and the transmittance Ta (%) after heating is measured.

The above sample is a laminate of a colorless transparent glass substrate and a thin film of a sulfoxide-containing polymer with a thickness of 1 μm formed on one side of the substrate. The above sample can be prepared, for example, by applying a solution of a sulfoxide-containing polymer dissolved in a solvent to a colorless transparent glass substrate and one side of the substrate, followed by drying. A preferred example is a method in which a solution of a sulfoxide-containing polymer dissolved in hexafluoro-2-propanol to a concentration of 5% by mass is prepared, and the resulting solution is spin-coated at about 500 rpm for 60 seconds onto one side of a glass substrate (S1111, manufactured by Matsunami Glass Industry Co., Ltd.) with excellent visible light transmittance, and then dried at 100°C for 10 minutes to form a thin film (thickness 1 μm).

Visible light transmittance can be measured using a commercially available spectrophotometer. For example, a spectrophotometer (V-700 series ultraviolet, visible, and infrared spectrophotometer manufactured by JASCO) can be used. The visible light transmittance used to determine the transmittance after heating is usually the transmittance at a wavelength of 400 nm. Parallel line transmittance is also used as the transmittance.

For the above sulfoxide-containing polymer, the transmittance (Ta) after heating obtained by the above evaluation method is preferably 81% or more, more preferably 82% or more, and even more preferably 85% or more.

In addition, in the above sulfoxide-containing polymer, the transmittance (Tb) before heating at 260° C., in the above evaluation method, is preferably 82% or more, more preferably 83% or more, and even more preferably 85% or more.
The transmittance (Tb) can be measured in the same manner as the transmittance (Ta).
The above sulfoxide-containing polymer preferably has an absolute value of the difference between the transmittance (Ta) and the transmittance (Tb) of 5% or less, more preferably 3% or less, even more preferably 2% or less, and particularly preferably 1% or less.

The sulfoxide-containing polymer is preferably a sulfur-containing polymer having at least the structural unit (B) represented by the above general formula (2) as explained in the explanation of the sulfide-containing polymer, and the substituents that ^X2 and ^X2 may have are as explained in the explanation of the sulfide-containing polymer, including their preferred embodiments. Furthermore, the sulfoxide-containing polymer is preferably a sulfur-containing polymer having at least the structural unit (B-1) represented by the above general formula (2-1), and the substituents that ^R2 and ^R2 may have are as explained in the explanation of the sulfide-containing polymer, including their preferred embodiments.

The sulfoxide-containing polymer is a sulfur-containing polymer having a sulfoxide skeleton in the main chain, preferably a sulfur-containing polymer having the above-mentioned structural unit (B), but is not limited thereto, and may contain other structural units. For example, it may further contain the structural unit (A) represented by the above general formula (1) and/or the structural unit (C) represented by the above general formula (3), which were described in the description of the sulfide-containing polymer.

In the sulfoxide-containing polymer, the structural unit (A) is preferably the structural unit (A-1) represented by the above general formula (1-1), and the structural unit (C) is preferably the structural unit (C-1) represented by the above general formula (3-1). The substituents which ^X1 and ^X1 may have, the substituents ^{which X3} and ^X3 may have, the substituents which ^R1 and ^R1 may have, and the substituents which ^R3 and ^R3 may have, including preferred embodiments thereof, are as explained in the explanation of the sulfide-containing polymer.

The sulfoxide-containing polymer may be a polymer containing only the structural unit (B), or may be a copolymer further containing the structural unit (A) and/or the structural unit (C). When it is a copolymer, the form is not particularly limited, and may be, for example, an alternating copolymer, a block copolymer, or a random copolymer. The sulfoxide-containing polymer may have one or more of the structural units (A), (B), or (C).

The content of the structural unit (B) in the sulfoxide-containing polymer is preferably higher than the content of the structural unit (B) in the sulfide-containing polymer subjected to the oxidation step. In the sulfoxide-containing polymer, the content of the structural unit (B) is preferably 10 to 99 mol%, more preferably 30 to 97 mol%, and even more preferably 60 to 95 mol%, based on 100 mol% of all structural units in the polymer. The total content of the structural units (A) and (C) is preferably 1 to 90 mol%, more preferably 3 to 70 mol%, and even more preferably 5 to 40 mol%, based on 100 mol% of all structural units. The content of the structural unit (A) is preferably 1 to 90 mol%, more preferably 3 to 70 mol%, and even more preferably 5 to 40 mol%, based on 100 mol% of all structural units.

In the sulfoxide-containing polymer, the total content of the structural units (A), (B) and (C) is preferably 50 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and particularly preferably 100 mol%, based on 100 mol% of all structural units in the polymer.

The sulfoxide-containing polymer may have a structural unit (D) other than the structural unit (A), structural unit (B), and structural unit (C). Examples of the structural unit (D) include structural units having at least the reactive functional group described above. Monomers into which the structural unit (D) can be introduced are as described in the description of the sulfide-containing polymer. The content of the structural unit (D) is preferably 0 to 50 mol%, more preferably 0 to 20 mol%, and even more preferably 0 to 5 mol%, relative to 100 mol% of all structural units of the polymer.

The sulfoxide-containing polymer preferably has the reactive functional group at the end of the main chain and/or at the side chain. By having the reactive functional group at least at the end of the main chain or at the side chain, the sulfoxide-containing polymer obtained after the oxidation reaction can exhibit excellent physical properties due to the reactive functional group. The case where the reactive functional group is present at the side chain includes not only the case where the reactive functional group is present at the side chain of the sulfoxide-containing polymer, but also the case where the substituent in the structural units (A) to (C) represented by the general formulas (1) to (3) is the reactive functional group or a group containing the reactive functional group.

The sulfoxide-containing polymer preferably has a heavy metal content of 0.0001 ppm or more and 1200 ppm or less relative to the sulfur-containing polymer. The sulfoxide-containing polymer has a high refractive index and excellent light transmittance. It also has excellent transmittance after heating. The heavy metal content is more preferably 500 ppm or less relative to the polymer (solid content), even more preferably 200 ppm or less, and even more preferably 100 ppm or less. In addition, from the viewpoint that a molded product using the sulfoxide-containing polymer is likely to have excellent toughness, the heavy metal content is more preferably 0.001 ppm or more relative to the sulfoxide-containing polymer (solid content), and even more preferably 0.01 ppm or more. The heavy metal content can be determined by the above-mentioned ICP emission spectroscopy.

The sulfoxide-containing polymer preferably has an elemental ratio (O/S) of oxygen atoms O bonded to sulfur atoms S in the main chain to sulfur atoms S in the main chain of 0.1 to 1.5. When the elemental ratio is within the above range, the transparency and refractive index are further increased.
The sulfur atom S in the main chain specifically means, for example, in the structural unit (B) represented by the general formula (2), the sulfur atom S of -SO- in the main chain. In the structural unit (A) represented by the general formula (1), the sulfur atom S of -S- in the main chain, and in the structural unit (C) represented by the general formula (3), the sulfur atom S of -SO ₂ - in the main chain. The oxygen atom bonded to the sulfur atom S in the main chain specifically means, for example, in the structural unit (B) represented by the general formula (2), the oxygen atom O of -SO- in the main chain, and in the structural unit (C) represented by the general formula (3), the oxygen atom O of -SO ₂ - in the main chain.

The element content ratio (O/S) is preferably 0.3 or more, more preferably 0.5 or more, in order to further increase the transparency, and is preferably 1.3 or less, even more preferably 1.1 or less, in order to further increase the refractive index. The element content ratio can be determined by evaluating and measuring the peak intensities of the oxygen atom 1s orbital (O1s), carbon atom 1s orbital (C1s), and sulfur atom 2p orbital (S2p) using an X-ray photoelectron spectroscopy (XPS).

The weight average molecular weight (Mw) of the sulfoxide-containing polymer is preferably 500 to 10,000,000. When the weight average molecular weight is within the above range, it can be suitably used as an optical material. From the viewpoint of improving mechanical properties, the weight average molecular weight is more preferably 1,000 or more, even more preferably 3,000 or more, and even more preferably 10,000 or more, and from the viewpoint of reducing melt viscosity, it is more preferably 1,000,000 or less, and even more preferably 100,000 or less.

The dispersity (weight average molecular weight/number average molecular weight) of the sulfoxide-containing polymer is preferably 1 or more and 10 or less. When the dispersity is within the above range, molding becomes easy. In terms of further improving moldability, the dispersity is more preferably 5 or less, and even more preferably 3 or less. The weight average molecular weight and number average molecular weight can be determined by measurement using gel permeation chromatography (GPC), specifically, by the method described in the examples below. The dispersity can be determined by dividing the weight average molecular weight by the number average molecular weight.

The sulfoxide-containing polymer preferably has a glass transition temperature (Tg) of 80 to 250°C. When the glass transition temperature is in the above range, molding can be easily performed. From the viewpoint of increasing heat resistance, the glass transition temperature is more preferably 90°C or higher, and even more preferably 100°C or higher, and from the viewpoint of easy molding, it is more preferably 200°C or lower. The glass transition temperature can be determined by a method of evaluating the intersection of the tangent at the baseline and the inflection point from the DSC curve obtained by heating from room temperature to 250°C (heating rate 10°C/min) in a nitrogen gas atmosphere using a differential scanning calorimeter (DSC).

The sulfoxide-containing polymer preferably has a refractive index of 1.69 or more. When the refractive index is within the above range, the polymer can be widely and suitably used in a variety of applications, such as optical materials (members), mechanical parts materials, electrical and electronic parts materials, automobile parts materials, civil engineering and construction materials, molding materials, and also paints and adhesives. The refractive index is more preferably 1.7 or more, and even more preferably 1.71 or more. The refractive index can be determined by forming a film having a thickness of 50 nm using the polymer as a measurement sample, and measuring the film using a spectroscopic ellipsometer UVISEL (manufactured by HORIBA Scientific) with Na D line (589 nm).

The sulfoxide-containing polymer preferably has an Abbe number of 10 or more. When the Abbe number is in the above range, the light dispersion is small, and the optical material can be suitable for lenses. The Abbe number is more preferably 15 or more, even more preferably 18 or more, and even more preferably 20 or more. From the viewpoint of adjusting the light dispersion, the Abbe number is preferably 60 or less, and more preferably 55 or less. The Abbe number can be calculated by forming a film using the polymer in the same manner as in the measurement of the refractive index, measuring the refractive index at the D line (589.3 nm), F line (486.1 nm), and C line (656.3 nm) using the spectroscopic ellipsometer, and using the following calculation formula.
Abbe number (vD)=(nD−1)/(nF−nC)
In the formula, nD, nF, and nC represent the refractive indices at the Fraunhofer D line (589.3 nm), F line (486.1 nm), and C line (658.3 nm), respectively.

The sulfoxide-containing polymer obtained by the production method of the present invention has excellent transmittance after heating. Moreover, according to a preferred embodiment, since the polymer has a sulfoxide skeleton in the main chain, it has a high refractive index and is optically excellent in visible light transmittance. According to the preferred embodiment, it also has excellent solubility and processability. Moreover, the polymer obtained by the preferred embodiment of the production method of the present invention has a small amount of impurities used in the polymerization step, etc., and the material using the polymer has excellent colorless transparency and is suppressed from coloring over time.
Therefore, the sulfur-containing polymer (sulfoxide-containing polymer) obtained by the production method of the present invention can be used for various applications such as optical materials, either alone or as a composition in combination with other components.

3. Composition containing a sulfoxide-containing polymer obtained by the production method of the present invention The composition containing a sulfoxide-containing polymer obtained by the production method of the present invention will be described. The composition is also called a sulfoxide-containing polymer composition or a polymer composition.
The content of the sulfoxide-containing polymer in the sulfoxide-containing polymer composition is preferably 1 to 100% by mass, more preferably 10 to 50% by mass, and even more preferably 30 to 70% by mass, relative to 100% by mass of the total solid content of the sulfoxide-containing polymer composition.

The other components are not particularly limited and can be appropriately selected from known components depending on the purpose and application of the sulfoxide-containing polymer composition.
For example, the transparency and refractive index can be controlled by selecting an inorganic substance as another component. The sulfoxide-containing polymer and the sulfoxide-containing polymer composition containing an inorganic substance are also embodiments of the sulfoxide-containing polymer obtained by the production method of the present invention.

Examples of the inorganic substances include metals, inorganic oxides, inorganic nitrides, inorganic carbides, inorganic sulfides, inorganic hydroxides, etc. The inorganic substances may be used alone or in combination of two or more.
Examples of the metals include lithium (Li), sodium (Na), potassium (K), boron (B), magnesium (Mg), calcium (Ca), manganese (Mn), strontium (Sr), barium (Ba), titanium (Ti), zirconium (Zr), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), aluminum (Al), tin (Sn), silicon (Si), cesium (Ce), and indium (In).

As the inorganic oxide, a metal oxide containing a metal element is preferable. Examples of the metal oxide include a single metal oxide consisting of one metal element, a composite oxide consisting of two or more metal elements, and a solid solution oxide in which a different element is dissolved in the single metal oxide or the composite oxide. The different element may be a metal element or a nonmetal element other than oxygen, such as nitrogen or fluorine. Examples of the metal element include the metal elements described above. Examples of the single metal oxide include magnesium oxide, calcium oxide, strontium oxide, barium oxide, titanium oxide, zinc oxide, cerium oxide, silicon oxide, tin oxide, zirconium oxide, aluminum oxide, indium oxide, and the like. Examples of the composite oxide include perovskite-type composite oxides such as barium titanate, barium strontium titanate, strontium titanate, barium zirconium strontium titanate, barium zirconium titanate, and lead zirconate titanate; spinel-type composite oxides such as spinel and lithium titanate; and composite oxides such as aluminum titanate. The solid solution oxides include solid solution oxides in which a different metal element and/or a nonmetal element other than oxygen, such as nitrogen or fluorine, is dissolved in the single metal oxide or composite oxide.

The inorganic nitride is preferably a metal nitride, such as boron nitride, carbon nitride, aluminum nitride, etc. The inorganic carbide is preferably a metal carbide, such as silicon carbide, calcium carbide, titanium carbide, boron carbide, etc. The inorganic sulfide is preferably a metal sulfide, such as copper sulfide, zinc sulfide, cadmium sulfide, etc. The inorganic hydroxide is preferably a metal hydroxide, such as aluminum hydroxide, magnesium hydroxide, barium hydroxide, etc.

Among them, the inorganic material is preferably an inorganic oxide, more preferably a metal oxide, in that it is wide band gap (visible light transparent).Furthermore, among the inorganic materials, oxides mainly composed of metal elements Ti, Zr, Ce, Zn, In, Al, Si, and Sn are more preferable, in that they have no or little absorption in the visible light region, and therefore coloring by the inorganic material is suppressed, and a colorless and transparent composition is easily obtained, and titanium oxide ( _TiO2 ), zirconium oxide ( _ZrO2 ), cerium oxide ( _CeO2 ), zinc oxide ( _ZnO ), indium oxide ( _In2O3 ), _aluminum oxide ( _Al2O3 ), silicon oxide ( _SiO2 ), and tin oxide ( _SnO2 ) are particularly preferable.

Among the above inorganic substances, zirconium oxide, titanium oxide, and silicon dioxide are more preferable in terms of further improving the transparency of the sulfoxide-containing polymer composition and reducing the linear expansion of the composition, and zirconium oxide and titanium oxide are more preferable in terms of improving the refractive index of the sulfoxide-containing polymer composition. Perovskite-type complex oxides are preferable in terms of having a high relative dielectric constant and being suitable for use as a ferroelectric material or piezoelectric material. Boron nitride, aluminum hydroxide, and aluminum titanate are preferable in terms of having a high thermal conductivity and being suitable for use as a heat dissipation material.

From the viewpoint of imparting antistatic properties or electrical conductivity to the sulfoxide-containing polymer composition while suppressing coloration due to the addition of inorganic substances, solid solution oxides in which a different metal element or an additive element such as fluorine is solid-solved in zinc oxide (ZnO), indium oxide (In ₂ O ₃ ) or tin oxide (SnO ₂ ) are preferred. For example, zinc oxide in which In, Al or Ga is solid-solved, indium oxide in which Sn or Ti is solid-solved, tin oxide in which Sb or F is solid-solved, etc. are more preferred.

The shape of the inorganic material is not particularly limited and may be any of amorphous, granular, plate-like, fibrous, block-like, etc., but granular is preferred. The inorganic material may be surface-treated. The surface treatment is not particularly limited as long as it does not affect the effects of the present invention, and examples of known methods include a method using a silane coupling agent, a method of reacting a compound having a phosphoric acid group, and a method of reacting a compound having a carboxylic acid group.

The average particle diameter of the inorganic substance is preferably 1 nm or more and 1000 nm or less. When the average particle diameter of the inorganic substance is in the above-mentioned range, the light transmittance in the visible light region and the infrared region can be improved. The average particle diameter of the inorganic substance is more preferably 5 nm or more, even more preferably 10 nm or more, and more preferably 100 nm or less, and even more preferably 50 nm or less. The average particle diameter is obtained by observing the inorganic substance with a SEM (magnification 1000 to 100,000 times, preferably 10,000 times), analyzing the obtained image, determining the particle diameter (circular area equivalent diameter) of about 10 to 1000 individual particles (primary particles), and evaluating the 50% particle diameter based on the particle size distribution based on the number. For the image analysis, a known image analysis software (for example, Mac-View manufactured by Mountec Co., Ltd.) can be used.

The content of the inorganic substance is not particularly limited and can be appropriately set depending on the purpose and use of the sulfoxide-containing polymer composition. For example, the content of the inorganic substance is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, particularly preferably 70 parts by mass or more, and most preferably 80 parts by mass or more, relative to 100 parts by mass of the sulfoxide-containing polymer, in terms of further improving transparency and reducing linear expansion. In addition, from the viewpoint of reducing the melt viscosity during the production of a resin molded product, the content of the inorganic substance is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less, relative to 100 parts by mass of the sulfoxide-containing polymer.

In addition to the sulfoxide-containing polymer and inorganic substance described above, the sulfoxide-containing polymer composition may contain, for example, pigments, dyes, antioxidants, ultraviolet absorbers, resins, reactive diluents, light stabilizers, plasticizers, non-reactive compounds, chain transfer agents, thermal polymerization initiators, anaerobic polymerization initiators, polymerization inhibitors, inorganic fillers, organic fillers, adhesion improvers such as coupling agents, heat stabilizers, antibacterial and antifungal agents, flame retardants, matting agents, defoamers, leveling agents, wetting and dispersing agents, anti-settling agents, thickeners and anti-sagging agents, color separation inhibitors, emulsifiers, slip and scratch inhibitors, anti-skinning agents, drying agents, antifouling agents, antistatic agents, conductive agents (electrostatic assistants), solvents, and other components. Only one of these components may be used, or two or more of them may be used in combination. These components can be appropriately selected from known ones and used. The blending amounts of these components can be appropriately set.

When the sulfoxide-containing polymer composition is for use in an optical material, it may contain other components as appropriate depending on the application of the optical material. Specific examples of the other components include ultraviolet absorbers, IR cutters, reactive diluents, pigments, detergents, antioxidants, light stabilizers, plasticizers, non-reactive compounds, and defoamers.

The sulfoxide-containing polymer composition preferably has a glass transition temperature (Tg) of 80 to 250°C. When the glass transition temperature is in the above-mentioned range, molding processing can be easily performed. From the viewpoint of increasing heat resistance, the glass transition temperature is more preferably 90°C or higher, and even more preferably 100°C or higher, and from the viewpoint of easy molding processing, it is more preferably 200°C or lower. The glass transition temperature can be determined by the same method as the method for measuring the glass transition temperature of the polymer described above.

The sulfoxide-containing polymer composition preferably has a refractive index of 1.69 or more. If the refractive index is within the above range, it can be suitably used as an optical material, etc. The refractive index is more preferably 1.70 or more, and even more preferably 1.71 or more. The refractive index can be determined by the same method as the method for measuring the refractive index of the polymer described above.

The sulfoxide-containing polymer composition preferably has an Abbe number of 10 or more. When the Abbe number is in the above-mentioned range, the light dispersion is small, and the composition can be an optical material suitable for lenses. The Abbe number is more preferably 15 or more, even more preferably 18 or more, and even more preferably 20 or more. From the viewpoint of adjusting the light dispersion, the Abbe number is more preferably 60 or less, and even more preferably 55 or less. The Abbe number can be determined by the same method as the method for measuring the Abbe number of the polymer described above.

The sulfoxide-containing polymer composition preferably has a visible light transmittance of 70% or more. If the visible light transmittance is within the above range, it can be suitably used as an optical material. The visible light transmittance is more preferably 80% or more, even more preferably 85% or more, and even more preferably 88% or more. The visible light transmittance is a parallel line transmittance, and can be determined by the same method as the above-mentioned method for measuring the visible light transmittance of the sulfoxide-containing polymer.

The method for producing the sulfoxide-containing polymer composition is not particularly limited, and the composition can be prepared by mixing the sulfoxide-containing polymer, the inorganic substance, and other components as necessary. The mixing can be performed using known means such as a bead mill, a roll mill, a ball mill, a jet mill, a kneader, or a blender.

The sulfoxide-containing polymer and sulfoxide-containing polymer composition of the present invention are preferably thermoplastic. If the polymer is thermoplastic, it can be easily molded and has excellent productivity.

The sulfoxide-containing polymer and sulfoxide-containing polymer composition of the present invention can also be suitably used as a molding material. The molding method is not particularly limited, and examples thereof include injection molding, extrusion molding, the T-die method, the inflation method, and other methods generally known as methods for processing thermoplastic resins. In addition, the polymer may be molded into a desired shape by a casting method, coating method, or other method. The above-mentioned shape is not particularly limited, and examples thereof include various known shapes such as lenses, sheets, and films.

4. Uses The sulfoxide-containing polymer and the sulfoxide-containing polymer composition obtained by the production method of the present invention are suitably used for optical materials, optical device members, display device members, etc. Specific examples of such applications include optical applications such as eyeglass lenses, imaging lenses for cameras such as (digital) cameras, mobile phone cameras, and vehicle-mounted cameras, light beam condensing lenses, and lenses for light diffusion, LED sealing materials, optical adhesives, optical pressure-sensitive adhesives, optical transmission bonding materials, filters, diffraction gratings, diffractive optical elements, prisms, light guides, watch glasses, and transparent glasses and cover glasses for display devices; optical device applications such as photosensors (optical sensors (CMOS sensors, TOF sensors, etc.)), photoswitches, LEDs, micro LEDs, light-emitting elements, optical waveguides, multiplexers, branchers, disconnectors, optical splitters, and optical fiber adhesives; display device applications such as substrates for display elements such as LCDs, organic ELs, and PDPs, substrates for color filters, substrates for touch panels, index matching materials used in touch panels, etc., display protective films, display backlights, light guide plates, anti-reflection films, anti-fogging films, and light extraction enhancers for LEDs and organic ELs.

Among these, imaging lenses, filters, diffraction gratings, diffractive optical elements, prisms, light guides, LEDs, micro LEDs, light emitting elements, color filters, and touch panels are more preferred. In addition, the sulfoxide-containing polymer obtained by the manufacturing method of the present invention is likely to have a wide range of no absorption in the visible and infrared regions. Such polymers are also suitable for use as optical materials in the visible and infrared regions.

The sulfoxide-containing polymer and sulfoxide-containing polymer composition obtained by the manufacturing method of the present invention are used for various applications other than optical applications, such as mechanical part materials, electrical and electronic part materials, automobile part materials, civil engineering and construction materials, molding materials, and materials for paints and adhesives. For example, the sulfoxide-containing polymer obtained by the manufacturing method of the present invention is usually likely to have excellent heat resistance, and such polymers with excellent heat resistance can also be used as heat-resistant materials, ferroelectric materials, heat dissipation materials, separators for battery materials, filters such as gas separation membranes and liquid separation membranes, electrode materials for fuel cells and Li batteries, electrolyte materials, and other battery components. They can also be suitably used as insulating materials and antenna materials that utilize low dielectric properties.

The sulfoxide-containing polymer and sulfoxide-containing polymer composition obtained by the manufacturing method of the present invention can be suitably used as a molding material. Examples of molding methods include conventionally known injection molding, T-die method, inflation method, imprint molding, nanoimprint molding, and molding using a mold or resin mold. The desired shape may be formed by a casting method, coating method, or other method. The above-mentioned shape is not particularly limited, and examples thereof include various known shapes such as lenses, sheets, and films.

The sulfoxide-containing polymer and sulfoxide-containing polymer composition obtained by the production method of the present invention can be suitably used in etching processes such as plasma etching and resist processes utilizing solubility differences known in the art. They can also be suitably used in coating processes such as spin coating, bar coating, squeegee coating, and inkjet coating. The composition containing the sulfoxide-containing polymer obtained by the production method of the present invention is preferably a thermoplastic resin composition in terms of good processability, and is preferably a curable resin composition in terms of low viscosity and good conformability to fine metal molds and resin molds during molding.
As described above, the sulfoxide-containing polymer and the sulfoxide-containing polymer composition obtained by the production method of the present invention can be suitably used in a wide range of applications including optical applications.

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 "% by mass". The polymers obtained in the examples and comparative examples, and the sulfide-containing polymers used in the examples were evaluated according to the following methods.

<Measurement of heavy metal content>
Using an ICP emission spectrometer ICP-8100 (manufactured by Shimadzu Corporation), measurements were performed under appropriate plasma conditions (high frequency output 1.4 kW, coolant gas 20.0 L/min, plasma gas 1.40 L/min, carrier gas 0.60 L/min, plasma light source), and the amount of heavy metals (iron amount) in the polymer was evaluated based on the calibration curve, and the amount of heavy metals (ppm) relative to the polymer was determined. As a measurement sample, a sample appropriately diluted with a solvent so that the polymer concentration was 0.1 to 10 mass% was used. As a solvent, N-methylpyrrolidone was used for polymers with no main chain oxidation, and dimethylformamide was used for polymers with a main chain oxidation rate of 90% or more.

<Weight average molecular weight (Mw)>
The weight average molecular weight of the polymer was determined by gel permeation chromatography (GPC) under the following conditions.
Equipment 1: SHIMAZU, CBM-20A.
Apparatus 2: Agilent Technologies 1260 Infinity.
Detector: refractive index detector (RI) (SHIMAZU, SPD-20MA), and ultraviolet-visible-infrared spectrophotometer (SHIMAZU, SPD-20MA).
Column: TOSOH, TSKgel Super HM-N.
Column temperature: 40°C.
Flow rate: 0.3ml/min.
Calibration curve: Polystyrene Standards.
Eluent: chloroform, tetrahydrofuran.

<MALDI (time-of-flight mass spectrometry)>
The resulting polymer was subjected to MALDI measurement under the following conditions.
Equipment: Time-of-flight mass spectrometer (Bruker Autoflex III)
Sample preparation: Approximately 2 mg of a measurement sample, 20 mg of 2,5-dihydroxybenzoic acid as a matrix agent, and 2.0 mg of sodium iodide as an ionization agent were dissolved in 1.0 g of tetrahydrofuran, and the prepared solution was applied to a measurement target plate and then dried at room temperature for about 100 minutes.

^<1H-NMR>
The resulting polymer was subjected to ¹ H-NMR measurement under the following conditions.
Apparatus: Nuclear magnetic resonance apparatus (400 MHz) manufactured by JEOL Ltd.
Measurement solvent: deuterated dichloromethane, deuterated chloroform.
Sample preparation: Several mg to several tens of mg of the obtained polymer were dissolved in a measurement solvent.

<IR>
The obtained polymer was subjected to IR measurement under the following conditions.
Apparatus: JASCO Fourier transform infrared spectrophotometer (FT/IR-6100)
Sample preparation: Approximately 2 mg of sample was diluted with approximately 300 mg of dry potassium bromide (KBr). The mixture was ground in a mortar and pestle and molded.

<Element content ratio O/S ratio>
A sample was prepared by spin-coating 0.25 ml of the polymer solution on a silicon wafer to form a film, and a photoelectron spectrometer (JPS-9010TR, XPS device, light source: Mg, X-ray output: 400 W) manufactured by JEOL was used to measure the peak intensity derived from the 2p orbital of sulfur atoms and the peak intensity derived from the 1s orbital of oxygen atoms, and the integral ratio was calculated to calculate the O/S ratio. If necessary, the peak intensity derived from the 1s orbital of carbon atoms was also measured, and the O/S ratio was calculated taking the results into consideration. The measurement method and the position of the bond energy were based on the Handbook of X-ray Photoelectron Spectroscopy (JEOL, March 1991).
For those in which the sulfide and sulfoxide peaks could be separated by 1H-NMR measurement, the O/S ratio was calculated by calculating the integral ratio of each peak.

<Binding Energy>
0.25 ml of the polymer solution was spin-coated on a silicon wafer to form a film, and the binding energy was measured from the peak position of the 2p3/2 orbital of the sulfur atom using a JEOL photoelectron spectrometer (JPS-9010TR, XPS device).

<Organic elemental analysis>
The resulting polymer was subjected to elemental analysis using the following apparatus.
Apparatus: J Science Lab JM10.

<Transmittance>
(Sample Preparation)
A solution was prepared by dissolving the polymer in chloroform to a concentration of 5% by mass for the polymer (sulfide-containing polymer obtained in the Production Examples) subjected to the oxidation reaction in the Examples, and a solution was prepared by dissolving the polymer in hexafluoro-2-propanol to a concentration of 5% by mass for the polymer (polymer after oxidation reaction) obtained in the Examples and Comparative Examples. The resulting solution was spin-coated at about 500 rpm for 60 seconds on a glass substrate (S1111, manufactured by Matsunami Glass Industry Co., Ltd.) that has almost no absorption of visible light, and dried at 100° C. for 10 minutes to form a thin film (1 μm thick).
(measurement)
The transmittance of the obtained thin film was measured by a spectrophotometer (V-700 series ultraviolet, visible, and infrared spectrophotometer manufactured by JASCO Corporation). To evaluate the visible light transmittance, the transmittance at 400 nm was compared. Air was used as a control sample. The above transmittance is a parallel line transmittance.

<Transmittance after heating>
The thin film used in the evaluation of the transmittance of the thin film was heated at 260° C. for 10 minutes, and the transmittance of the thin film after heating was measured using the same method and conditions as those in the above <Transmittance of thin film>.

(Synthesis of Monomer)
[Synthesis Example 1]
In a 500 mL three-neck flask, water (98 mL), o-toluenethiol (2-methylbenzenethiol) (18.2 g, 0.147 mol), and tetrabutylammonium iodide (54.3 mg, 0.147 mmol) were added, and 30% hydrogen peroxide solution (15.2 mL, 0.147 mol) was added dropwise at 1 mL/min, followed by stirring at 60° C. for 2 hours. The mixture was cooled to room temperature, the supernatant (aqueous layer) was removed, and then an aqueous sodium thiosulfate solution was added, followed by stirring at room temperature for 2 hours, followed by removing the supernatant (aqueous layer). The reaction solid was filtered, washed with pure water and methanol in that order, and vacuum dried to recover bis(2-methylphenyl)disulfide. The yield was 98%. It was confirmed to be bis(2-methylphenyl)disulfide (2,2'-dimethyldiphenyldisulfide) by ¹ H-NMR, ¹³ C-NMR, and FAB-MS.

[Synthesis Example 2]
A synthesis reaction was carried out under the same conditions as in Synthesis Example 1, except that the raw material in Synthesis Example 1 was changed to p-toluenethiol (4-methylbenzenethiol) instead of o-toluenethiol, to obtain bis(4-methylphenyl)disulfide in a yield of 98%. The product was identified as bis(4-methylphenyl)disulfide (4,4'-dimethyldiphenyldisulfide) by ^1H -NMR, ^13C -NMR and FAB-MS.

(Synthesis of Sulfide-Containing Polymers)
[Production Example 1]
In a 500 mL three-neck flask, diphenyl disulfide (131.00 g, 0.6 mol) and bis(2-methylphenyl) disulfide (36.01 g, 0.15 mol) obtained in the above Synthesis Example 1 were added to iron (III) chloride (6.05 g, 37.30 mmol), (+)-CSA (1.73 g, 7.46 mmol), and Na ₂ S ₂ O ₈ (1.78 g, 7.46 mmol), and the reaction solution was heated at 160° C. while air bubbling (100 mL/min) and stirred for 40 hours to carry out oxidative polymerization. After cooling to room temperature, a black solid polymer (Ps1) was obtained in 92% yield. The structure of the obtained polymer (Ps1) was identified by ¹ H-NMR, GPC, ICP, XPS, and MALDI. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ=7.18 (m, 23H), 2.25 (m, 3H), weight average molecular weight (Mw) was 2400, and ICP analysis revealed that the iron content was 21500 ppm. XPS measurement revealed a peak at 160.3-164.9 eV, and peak separation revealed peaks at 160.3-164.9 eV (sulfide) and 163.5-164.9 eV (disulfide), with the peak area ratio of sulfide to disulfide being 93:7. Furthermore, repeating peaks at m/z 107.98 and m/z 122.04 were observed by MALDI measurement, and it was confirmed that the polymer contained -C ₆ H ₄ S- and -C ₆ H ₃ (CH ₃ )S- as the constituent element (A).

[Production Example 2]
A polymerization reaction was carried out under the same conditions as in Production Example 1, except that the monomer in Production Example 1 was changed to bis(4-methylphenyl)disulfide obtained in Synthesis Example 2 instead of bis(2-methylphenyl)disulfide, and the reaction time was changed to 60 hours, to obtain a polymer (Ps2) in a yield of 94%. The structure of the obtained polymer (Ps2) was identified by ¹ H-NMR, GPC, ICP, XPS, and MALDI. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ=7.20 (m, 23H), 2.25 (m, 3H), weight average molecular weight was 3040, and the iron content was 22500 ppm by ICP analysis. XPS measurement revealed a peak at 160.1-164.8 eV, and peak separation revealed peaks at 160.1-164.8 eV (sulfide) and 163.5-164.8 eV (disulfide), with the peak area ratio of sulfide to disulfide being 95: 5. MALDI measurement revealed repeating peaks at m/z 107.95 and m/z 122.02, confirming that the _polymer contained _-C6H4S- and _-C6H3 ( _CH3 ) _S- as components (A).

[Example 1]
In a 100 ml eggplant flask, the polymer (Ps1) (1.1 g) obtained in Production Example 1 and THF (1.0 M, 10 mL) as a solvent were added, and after stirring for 10 minutes, 1.0 mL of pure water (THF:water = 10:1) was added and stirred for 5 minutes. Next, while cooling the eggplant flask in an ice-cooled bath, trichloroisocyanuric acid (TCCA) (0.369 g) was added and stirred for 2 hours. After the reaction was completed, methanol (40 mL) was gradually added to the reaction solution to precipitate the product, and the precipitate in the reaction solution was filtered using a Kiriyama filter and washed with methanol and pure water. The obtained powder was then vacuum dried at room temperature to obtain a polymer (Po1) powder. The structure of the obtained polymer (Po1) was identified by ¹ H-NMR, XPS, ICP, IR, and elemental analysis. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ = 7.19 (m, 15H) δ = 7.56 (m, 8H), 2.35 (m, 3H), and IR showed peaks at around 1350 cm ^-1 and 1170 cm ^-1 derived from sulfone and a peak at around 1050 cm ^-1 derived from sulfoxide. Elemental analysis suggested that the polymer contained 1.35% by weight of chlorine atoms and had a terminal structure of -S(=O ₂ )Cl.

[Example 2]
In a 100 ml eggplant flask, 1.1 g of the polymer (Ps2) obtained in Production Example 2 and THF (1.0 M, 10 mL) as a solvent were added, and after stirring for 10 minutes, 1.0 mL of pure water (THF:water = 10:1) was added and stirred for 5 minutes. Next, while cooling the eggplant flask in an ice-cooled bath, TCCA (0.369 g) was added, and after stirring for 2 hours, zinc powder (0.131 g) was added and stirred at room temperature for 16 hours. After the reaction was completed, the product was precipitated by gradually adding methanol (40 mL) to the reaction solution, and the precipitate in the reaction solution was filtered using a Kiriyama filter and washed with methanol and pure water. The obtained powder was then vacuum dried at room temperature to obtain a polymer (Po2) powder. The structure of the obtained polymer (Po2) was identified by ¹ H-NMR, XPS, ICP, IR, and elemental analysis. As a result, ^1H -NMR ( _CD2Cl2 , _400MHz , ppm): δ = 7.19 (m, 9H) δ = 7.56 (m, 14H), 2.35 (m, 3H), and IR showed a peak derived from mercapto at about 2570 cm ^-1 . Elemental analysis confirmed that the chlorine atom content in the polymer was below the detection limit and that the terminal structure was -SH.

[Example 3]
In a 100 ml eggplant flask, the polymer (Ps1) (1.1 g) obtained in Production Example 1 and THF (1.0 M, 10 mL) as a solvent were added, and after stirring for 10 minutes, 0.5 mL of pure water was added and stirred for 5 minutes. Next, while cooling the eggplant flask in an ice-cooled bath, NaClO.5H ₂ O (0.987 g) was added, concentrated hydrochloric acid (0.5 mL) was gradually added, and after stirring for 2 hours, zinc powder (0.131 g) was added and stirred at room temperature for 16 hours. After the reaction was completed, the product was precipitated by gradually adding methanol (40 mL) to the reaction solution, and the precipitate in the reaction solution was filtered using a Kiriyama filter and washed with methanol and pure water. The obtained powder was then vacuum dried at room temperature to obtain a polymer (Po3) powder. The structure of the obtained polymer (Po3) was identified by ¹ H-NMR, XPS, ICP, and IR. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ=7.19 (m, 7H) δ=7.56 (m, 12H), 2.35 (m, 3H), and IR showed a peak derived from mercapto at about 2570 cm ⁻¹ , confirming that the terminal structure was —SH.

[Example 4]
In a 100 ml eggplant flask, the polymer (Ps1) (1.1 g) obtained in Production Example 1 and THF (1.0 M, 10 mL) as a solvent were added, and after stirring for 10 minutes, 1.0 mL of pure water (THF: water = 10: 1) was added and stirred for 5 minutes. Next, while cooling the eggplant flask in an ice-cooled bath, TCCA (0.369 g) was added, and after stirring for 2 hours, triethylamine (TEA) (0.506 g) was added and stirred at room temperature for 30 minutes. Furthermore, 1 mL of ammonia water (25%) was added as an introduced amine and stirred for 2 hours. After the reaction was completed, the product was precipitated by gradually adding 5% hydrochloric acid acidic methanol (40 mL) to the reaction solution, and the precipitate in the reaction solution was filtered by Kiriyama filtration and washed with methanol and pure water. Next, the obtained powder was vacuum dried at room temperature to obtain a polymer (Po4) powder. The structure of the obtained polymer (Po4) was identified by ¹ H-NMR, XPS, ICP and elemental analysis. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ = 7.19 (m, 5H) δ = 7.56 (m, 14H), 2.35 (m, 3H). XPS measurement showed a peak at 160.5-168.8 eV, with peak separation revealing peaks at 160.5-163.8 eV (sulfide), 160.9-168.8 eV (sulfoxide), and 166.0-168.8 eV (sulfone). The peak area ratio of sulfide, sulfoxide, and sulfone was 22:72:6. Elemental analysis confirmed that the chlorine atom content in the polymer was below the detection limit and the nitrogen atom content was 0.77%, and the terminal structure was -S(=O ₂ )NH ₂ .

[Example 5]
In a 100 ml eggplant flask, the polymer (Ps2) (1.1 g) obtained in Production Example 2 and THF (1.0 M, 10 mL) as a solvent were added, and after stirring for 10 minutes, 1.0 mL of pure water (THF: water = 10: 1) was added and stirred for 5 minutes. Next, while cooling the eggplant flask in an ice-cooled bath, TCCA (0.369 g) was added, and after stirring for 2 hours, zinc powder (0.131 g) was added and stirred at room temperature for 30 minutes. Furthermore, acrylic acid (AA) (0.144 g) was dropped as an alkyne reactant for the enethiol reaction, and stirred for 16 hours. After the reaction was completed, the product was precipitated by gradually adding methanol (40 mL) to the reaction solution, and the precipitate in the reaction solution was filtered by Kiriyama filtration and washed with methanol and pure water. Next, the obtained powder was vacuum dried at room temperature to obtain a polymer (Po5) powder. The structure of the obtained polymer (Po5) was identified by ¹ H-NMR, XPS, ICP, and IR. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ = 7.19 (m, 29H) δ = 7.56 (m, 32H), 2.35 (m, 8H), 2.52 (m, 2H), 3.11 (m, 2H), and IR showed a peak derived from a carboxyl group at about 1690 cm ^-1 , confirming that the terminal structure was -SCH ₂ CH ₂ COOH.

[Example 6]
In a 100 ml eggplant flask, the polymer (Ps1) (1.1 g) obtained in Production Example 1 and THF (1.0 M, 10 mL) as a solvent were added, and after stirring for 10 minutes, 1.0 mL of pure water (THF: water = 10: 1) was added and stirred for 5 minutes. Next, while cooling the eggplant flask in an ice-cooled bath, TCCA (0.369 g) was added, and after stirring for 2 hours, 10 mL of NMP was added as a solvent, and then K ₂ CO ₃ (0.691 g) was added and stirred at room temperature for 30 minutes. After stirring, diallylamine (DAA) was dropped as an amine and stirred at room temperature for 16 hours. After the reaction was completed, the product was precipitated by gradually adding 5% hydrochloric acid acidic methanol (40 mL) to the reaction solution, and the precipitate in the reaction solution was filtered by Kiriyama filtration and washed with methanol and pure water. Next, the obtained powder was vacuum dried at room temperature to obtain a polymer (Po6) powder. The structure of the obtained polymer (Po6) was identified by ¹ H-NMR, XPS, ICP, IR and elemental analysis. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ = 7.19 (m, 35H) δ = 7.56 (m, 26H), 2.35 (m, 8H), 3.81 (m, 4H), 5.09 (m, 4H), 5.57 (m, 2H). From IR, a peak derived from an allyl group was observed at about 990 cm ^-1 , peaks derived from sulfone at about 1350 cm ^-1 and 1170 cm ^-1 , and a peak derived from sulfoxide at about 1050 cm ^-1. From elemental analysis, it was confirmed that the chlorine atom content in the polymer was below the detection limit and the nitrogen atom content was 0.48%, and that part of the terminal structure was -S(=O ₂ )N(CH ₂ CH=CH ₂ ) ₂ .

[Example 7]
In a 100 ml eggplant flask, the polymer (Ps1) (1.1 g) obtained in Production Example 1 and THF (1.0 M, 10 mL) as a solvent were added, and after stirring for 10 minutes, 1.0 mL of pure water (THF: water = 10: 1) was added and stirred for 5 minutes. Next, while cooling the eggplant flask in an ice-cooled bath, TCCA (1.38 g) was added and stirred for 2 hours. Furthermore, 1 mL of ammonia water (25%) was added and stirred for 2 hours. After the reaction was completed, the product was precipitated by gradually adding 5% hydrochloric acid acidified methanol (40 mL) to the reaction solution, and the precipitate in the reaction solution was filtered by Kiriyama filtration and washed with methanol and pure water. The obtained powder was then vacuum dried at room temperature to obtain a polymer (Po7) powder. The structure of the obtained polymer (Po7) was identified by ¹ H-NMR, XPS, ICP, and elemental analysis. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ = 7.56 (m, 19H), 2.35 (m, 3H), and XPS measurement showed a peak at 160.8-168.9 eV, with peak separation revealing peaks at 160.8-163.6 eV (sulfide), 160.8-168.9 eV (sulfoxide), and 166.0-168.9 eV (sulfone). The peak area ratio of sulfide, sulfoxide, and sulfone was 2:92:6. Elemental analysis confirmed that the chlorine atom content in the polymer was below the detection limit and the nitrogen atom content was 0.80%, and that part of the terminal structure was -S(=O ₂ )NH ₂ .

[Comparative Example 1]
In a 50 ml eggplant flask, 0.33 g of the polymer (Ps1) obtained in Production Example 1 was added and dissolved in 3.0 mL of chloroform. Next, 65% metachloroperbenzoic acid (mCPBA) (0.796 g) was gradually added to the eggplant flask and stirred at room temperature for 16 hours. The reaction solution was then dropped into 20 mL of a hydrochloric acid-acidified methanol solution to precipitate the oxidized product. The precipitate was filtered using a Kiriyama filter, washed in this order with methanol and water, and dried in vacuum to obtain a brown polymer (PoC1). The structure of the obtained polymer (PoC1) was identified by ¹ H-NMR, XPS, and ICP. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ = 7.56 (m, 19H), 2.35 (m, 3H), and XPS measurement showed a peak at 161.8-168.5 eV, and peak separation yielded peaks at 161.8-168.5 eV (sulfoxide) and 161.8-163.5 eV (sulfide), with the peak areas of sulfoxide and sulfide being 97:3.

[Comparative Example 2]
In a 300 ml recovery flask, 6.73 g of the polymer (Ps1) obtained in Production Example 1 was added, and then 60.9 mL of cyclopentyl methyl ether (CPME) was added and dissolved at 70° C. To the obtained polymer solution, a solution of 66.7 mg of 1,1,1-trifluoroacetone added to 6.12 mL of 60% hydrogen peroxide water was added, and the mixture was stirred at 60° C. for 18 hours.
A mixed solvent of 122 mL of methanol and 122 mL of water was added to the stirred polymer solution, and the solid matter was filtered, washed with water and methanol, and dried under vacuum to obtain a brown polymer (PoC2). The structure of the obtained polymer (PoC2) was identified by ¹ H-NMR, XPS, and ICP. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ = 7.56 (m, 19H), 2.35 (m, 3H), and peaks were observed at 161.2-168.9 eV, and peak separation allowed the peaks to be separated into 161.2-168.9 eV (sulfoxide) and 161.2-163.8 eV (sulfide), with the peak areas of sulfoxide and sulfide being 96:4.

[Comparative Example 3]
In a 50 ml eggplant flask, 1.10 g of the polymer (Ps1) obtained in Production Example 1 was added, dissolved in a mixed solvent of 10 mL of tetrahydrofuran and 0.5 mL of methanol, sodium borohydride (0.151 g) was added, and the mixture was stirred at room temperature for 6 hours. After stirring, the solvent was removed by reducing pressure. Next, 10 mL of cyclopentyl methyl ether (CPME) was added and dissolved at 70°C. A solution of 12.3 mg of 1,1,1-trifluoroacetone in 0.030 mL of 60% hydrogen peroxide water was added to the obtained polymer solution, and the mixture was stirred at 60°C for 18 hours. The polymer solution after stirring was dropped into 400 mL of a 3% hydrochloric acid acidic methanol solution to precipitate, and the solid matter was filtered, washed with water and methanol, and dried in vacuum to obtain a polymer (PoC3). The structure of the obtained polymer (PoC3) was identified by ¹ H-NMR, XPS, and ICP. As a result, ¹ H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ = 7.19 (m, 13H) δ = 7.56 (m, 6H), 2.35 (m, 3H), and XPS measurement showed a peak at 160.3-168.1 eV, and peak separation revealed peaks at 160.3-167.8 eV (sulfide) and 164.6-167.8 eV (sulfoxide), with the peak area ratio of sulfoxide to sulfide being 30:70.

[Comparative Example 4]
In a 50 ml eggplant flask, 1.10 g of the polymer (Ps1) obtained in Production Example 1 was added, dissolved in a mixed solvent of 10 mL of tetrahydrofuran and 0.5 mL of methanol, sodium borohydride (0.151 g) was added, and the mixture was stirred at room temperature for 6 hours. After stirring, 1 mL of a hydrochloric acid acidic methanol solution was added dropwise, and the mixture was stirred for 30 minutes. The polymer solution after stirring was dropped into 400 mL of a 3% hydrochloric acid acidic methanol solution to precipitate, and the solid was filtered, washed with water and methanol, and dried in vacuum to obtain a polymer (PoC4). The structure of the obtained polymer (PoC4) was identified by 1H-NMR, XPS, ICP, and IR. As a result, 1H-NMR (CD ₂ Cl ₂ , 400 MHz, ppm): δ = 7.19 (m, 19H), 2.35 (m, 3H), XPS measurement showed only a 160.1-163.7 eV (sulfide) peak, and IR showed a peak derived from a mercapto group near 2570 cm ^-1 , confirming that the terminal structure was -SH.

Table 1 shows the evaluation results for the polymers (Po1) to (Po7) and (PoC1) to (PoC4) obtained in Examples 1 to 7 and Comparative Examples 1 to 4, respectively. As can be seen from Table 1, the polymers obtained in the Comparative Examples had low transmittance after heating, but all of the polymers obtained in the Examples had high transmittance after heating.

Claims (4)

A method for producing a sulfur-containing polymer having a sulfoxide skeleton in its main chain, comprising the steps of:
A method for producing a sulfur-containing polymer, comprising an oxidation step of oxidizing a sulfur-containing polymer having a sulfide skeleton in its main chain in a mixed solvent of an organic solvent and water, using at least one compound selected from the group consisting of hypochlorous acid, hypochlorites, and compounds capable of generating hypochlorous acid. The method for producing a sulfur-containing polymer according to claim 1, further comprising a polymer end control step. The method for producing a sulfur-containing polymer according to claim 2, wherein the polymer end control step uses a reducing substance or a basic substance. The method for producing a sulfur-containing polymer according to any one of claims 1 to 3 further comprises a polymerization step of polymerizing a monomer component containing a sulfur-containing monomer to obtain a sulfur-containing polymer having a sulfide skeleton in the main chain.