JP3163426B2 - Method for producing polyarylene thioether - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyarylene thioether, and more particularly, to a method for producing a polyarylene thioether capable of efficiently obtaining the polyarylene thioether under mild polymerization conditions.

2. Description of the Related Art Conventionally, polyarylene thioethers (hereinafter sometimes abbreviated as PAT) such as polyphenylene thioether (hereinafter sometimes abbreviated as PPT) have been known as dihalogen aromatic. It is produced by condensation polymerization of a compound and an alkali metal compound in a polar solvent under high temperature and pressure. However, in this method, the alkali metal salt remains in the PAT, and P
It degrades the electrical characteristics of the AT. There are problems such as high energy consumption and high cost. On the other hand, as a method of obtaining PAT by polymerizing thiophenol, US Pat. No. 8,988,988 is known. In this method, a very expensive catalyst such as MoCl ₃ / CF ₃ COOH is used. Industrially disadvantageous. Although a method using sulfuric acid as a catalyst is also known, it has a drawback that many by-products are generated and a crosslinked polymer is also largely formed. On the other hand, the inventors have filed an application for a PAT production method in which thiophenol or diphenyl disulfide is electropolymerized in the presence of an acid (Japanese Patent Application Laid-Open No. 63-241032). This method also uses large amounts of expensive acids.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-mentioned problems and to provide polyphenylene thioether and the like having excellent electrical characteristics, mechanical characteristics, chemical characteristics and the like. Polyarylene thioether,
In particular, a substantially linear polyphenylene thioether with few by-products of a crosslinked polymer can be obtained easily and inexpensively under mild polymerization conditions. It is an object of the present invention to provide a method for producing a polyarylene thioether which is extremely industrially advantageous. [Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors have found that thiophenol having an electron-donating substituent at positions 3 and 5 as a raw material monomer and The present inventors have found that a method of electrolytic polymerization using diphenyl disulfide is extremely effective for achieving the present invention, and have completed the present invention. That is, the monomers polymerized under the condition that no acid was present, and PAT could be synthesized using a wide range of solvents. . The gist of the present invention is that of the general formula [I] (However, in the formula [I], R ¹ and R ² each represent a substituent selected from the group consisting of a lower alkyl group and a lower alkoxy group. R ³ and R ^{4 each} represent a hydrogen atom or a lower alkyl group. And a substituent selected from the group consisting of a lower alkoxy group, wherein R ³ and R ⁴ may be the same type, and / or a thiophenol represented by the general formula [ II] (In the formula [II], S represents a sulfur atom, and R ⁵
To R ⁸ represents a lower alkyl group, selected from the group consisting of a lower alkoxy group group. R ^{9 to} R ¹² each represent a hydrogen atom, a lower alkyl group, or a lower alkoxy group. Note that R ^{5 to} R ¹² may be of the same type. A method for producing a polyarylene thioether, comprising subjecting a diphenyl disulfide represented by the formula (1) to electrolytic polymerization. R ¹ and R ^{2 in the} general formula [I]
Is described in more detail below. That is, specific examples of each of R ¹ and R ² include:
For example, methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, pentyl, hexyl, heptyl, octyl A lower alkyl group such as a methoxy group, an ethoxy group, a propoxy group,
Isopropoxy group, butoxy group, isobutoxy group, se
Examples thereof include lower alkoxy groups such as a c-butoxy group, a tert-butoxy group, and a pentyloxy group. Among them, groups such as a methyl group, an ethyl group, and a methoxy group are preferable. The details of R ³ and R ⁴ in the general formula [I] are as follows. That is, specific examples of each of R ³ and R ⁴ include, for example, a hydrogen atom; a methyl group, an ethyl group, a propyl group,
Methylethyl group, butyl group, 1-methylpropyl group, 2
A lower alkyl group such as -methylpropyl group, 1,1-dimethylethyl group, pentyl group, hexyl group, heptyl group, octyl group; methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group,
Examples thereof include lower alkoxy groups such as a sec-butoxy group, a tert-butoxy group, a pentyloxy group, and a hexyloxy group. Among these, a hydrogen atom; a lower alkyl group such as a methyl group and an ethyl group; and a lower alkoxy group such as a methoxy group are preferable, and a hydrogen atom, a methyl group, an ethyl group and the like are particularly preferable. Examples of the thiophenols represented by the general formula [I] include 3,5-dimethylthiophenol, 3,5-dimethoxythiophenol, 3-methyl-5-methoxythiphenol, and 2,3,5- Trimethylthiophenol,
2,3,5-triethylthiophenol, 2,3,5
6-tetramethylthiophenol, 2,6-diethyl-
3,5-dimethylthiophenol, 2,6-diethyl-
Preferred are 3,5-dimethoxythiophenol, 3,5-diethylthiophenol, 2,3,5,6-tetraethylthiophenol and the like. R ⁵ in the general formula [II]
For to R ^8, it is described below with more detail. That is, specific examples of each of R ^{5 to} R ⁸ include a methyl group, an ethyl group, a propyl group, a 1-methylethyl group, a butyl group, a 1-methylpropyl group, a 2-methylpropyl group, and a 1,1- Lower alkyl groups such as dimethylethyl group, pentyl group, hexyl group, heptyl group and octyl group; methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, sec
Lower alkoxy groups such as -butoxy group, tert-butoxy group, pentyloxy group and hexyloxy group. Among them, methyl group, ethyl group,
A lower alkyl group such as a methoxy group is preferable, and a methyl group and an ethyl group are particularly preferable. R ^{9 to} R in the general formula [II]
¹² will be described in more detail below. That is, specific examples of each of R ⁹ and R ¹² include, for example, a hydrogen atom; a methyl group, an ethyl group, a propyl group, a 1-methylethyl group, a butyl group, a 1-methylpropyl group, and a 2-methylpropyl group. A lower alkyl group such as 1,1,1-dimethylethyl group, pentyl group, hexyl group, heptyl group, octyl group; methoxy group, ethoxy group,
Lower alkoxy groups such as a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group and a hexyloxy group can be exemplified. Among these,
A hydrogen atom; a lower alkyl group such as a methyl group and an ethyl group; a lower alkoxy group such as a methoxy group are preferable, and a hydrogen atom, a methyl group, and an ethyl group are particularly preferable. That is, a diphenyl disulfide represented by the general formula [II] and a hydrogen atom, for example, 3,3 ′,
5,5′-tetramethyldiphenyl disulfide, 2,
2 ', 3,3', 5. -Hexamethyldiphenyl disulfide, 2,2 ', 3,3', 5,5 ', 6,6'-
Octamethyldiphenyl disulfide, 2,2 ', 3
3 ′, 5,5 ′, 6,6′-octaethyldiphenyl disulfide, 3,3 ′, 5,5′-tetramemethoxydiphenyl disulfide, 2,2 ′, 3,3 ′, 5,5 ′
-Hexamethoxydiphenyl disulfide, 2,2 ',
3,3 ', 5,5', 6,6'-octamethoxydiphenyl disulfide, 2,2 ', 6,6'-tetramethoxy-3,3', 5,5'-tetramethyldiphenyl disulfide, and the like Diphenyl disulfide can be mentioned. In the method of the present invention, the thioether represented by the general formula [I] and the thioether represented by the general formula [I]
I] One or two or more compounds selected from diphenyl disulfides represented by the formula (I) are homopolymerized or copolymerized to obtain various kinds and structures of polyarylene thioethers (homopolymers / copolymers or polyarylene thioethers thereof) Mixtures or compositions). Usually, general formula [III] (However, in the formula [III], R ^{13 to} R ¹⁶ are the same as R ^{1 to} R ⁴ in the general formula [I] or R ^{5 to} R ⁸ or R ^{9 to} R ^{12 in the} general formula [II]. N represents a positive number of 2 or more), particularly a linear or substantially linear polyarylene thioether having a very low degree of crosslinking. Can be obtained. This polymerization can be carried out in the absence of a solvent, but it is usually desirable to carry out the polymerization in the presence of a solvent. As the solvent, any solvent can be used as long as it does not substantially lose the polymerization activity, but a solvent that can dissolve commonly used monomers and a supporting electrolyte is desirable, and has a high decomposition potential and is electrochemically stable. What can perform electrolysis stably is preferred. Usually, examples of suitable solvents include, for example, nitromethane,
Examples thereof include dichloromethane, dibromomethane, tetrachloroethane, nitrobenzene, acetonitrile, and propylene carbonate. In addition, generally, if the number of donors is 17 or less, it can be suitably used. These solvents may be used singly or as a mixture of two or more, or if necessary, for example,
An inert solvent such as an aromatic hydrocarbon such as benzene or toluene may be appropriately mixed and used. The supporting electrolyte used for performing the electrolysis is not limited as long as it is one that stably undergoes electrolytic polymerization and does not hinder the reaction and maintains the ion concentration in the solution at a constant level. Preferred examples thereof include tetrabutylammonium tetrafluoroborate and tetrabutylammonium hexafluorophosphate. The electrode material used for the electrolysis is not particularly limited as long as it can stably carry out the electrolytic polymerization, but an electrochemically stable material is suitably used. Examples thereof include metals such as platinum, platinum black, and gold; graphite; conductive organic polymers such as polyphenylene, polypyrrole, and Nafion. Particularly, platinum electrodes and surfaces of platinum or platinum black, gold, and the like. An electrode coated with the conductive organic polymer is preferred. Shape of electrode material,
There is no particular relation to the area, for example, plate-like, film-like,
Various shapes such as a thin film, a thread, a rod, and a cylinder may be appropriately selected and used. As an arrangement method of the electrode material,
There is no particular limitation, and various known methods can be used. In short, one or more pairs of electrode materials such as electrode plates may be appropriately arranged so as not to contact each other. As the electrolysis system, a known system such as a bipolar system, a tripolar system, or a mixed system thereof can be used. As the type of electrolytic cell,
There is no particular limitation, and various known types can be used, but the type is a type in which the electrolytic reaction solution can be stirred or circulated, and the decomposition gas can be appropriately extracted, and the temperature is controlled. Those having a mechanism are preferably used. In the method of the present invention, the electrolytic polymerization is generally performed under the following conditions. The monomer concentration, that is, the total concentration of the thiophenols and the diphenyl disulfides in the electrolytic reaction solution to be used is not particularly limited, but is usually preferably, for example, in the range of 10 ^{−4 to} 10 mol / l. It is. The presence of water in the electrolytic reaction solution increases the polymerization rate, while reducing the polymerization activity,
Affects polymerization in various ways, but the concentration of water
If the concentration is higher than a certain level, the polymerization activity is usually remarkably reduced. Therefore, it is preferable to set the concentration within an allowable range. The allowable concentration range of this water is
Since it differs depending on the type of the solvent and the type of the monomer used, it cannot be defined uniformly, but is usually 0.1 mol% or less. The set potential and current for performing the electrolytic polymerization may be any range as long as the monomer to be used can be oxidized, but is usually 0.5 to 10 v (reference potential: Ag / AgC
l) is preferred. Note that the set potential and the current may be fixed values, or may be changed in various manners such as insertion and subtraction. The reaction temperature during the polymerization is not uniform depending on the type of the monomer used, but is usually-
The temperature is 5 to 150 ° C, preferably 0 to 50 ° C. The reaction pressure is not particularly limited, and usually can be suitably performed at normal pressure or the self-pressure of the reaction system. However, if necessary, the reaction can be carried out under pressure using a diluent gas or the like which does not hinder the polymerization reaction. The reaction time depends on the type of monomer to be used, its usage ratio, reaction temperature, set potential,
Although it differs significantly depending on other conditions such as current density, it is usually 0.01 to 80 hours, preferably 0.1 to 80 hours.
1 to 72 hours. In constituting the polymerization reaction system, the order and method of compounding the thiophenols and diphenyl disulfides and the solvent are not particularly limited, and they may be mixed simultaneously or stepwise in various orders and modes. it can. As a reaction method,
There is no particular limitation, and any of a continuous system, a non-continuous system, and a batch system may be used. In the case of using a batch system, it is desirable to stir the reaction system. By the above-described method, the desired polyarylene thioether can be obtained in a solution or on an electrode, in an electrolytic cell and in a solution after the current is supplied. The target polymer can be subjected to various post-treatments and recovered in various purities and forms. This post-processing can be performed according to various known methods. An example of this post-processing is as follows.
That is, when the polymerization reaction is completed or proceeds to a necessary extent, the reaction mixture is brought into contact with water, a lower alcohol such as methanol, or a mixture thereof to precipitate a product polymer. At this time, if necessary
A polymerization terminator such as a basic substance may be used in combination. The precipitated polymer is separated by a usual separation operation such as filtration.
Separated from liquid. The separated polymer is subjected to washing, such as dissolving, reprecipitating, separating, and washing with methanol as necessary, using an appropriate solvent and a reprecipitating solution, and then dried and purified to various purities. Can be recovered as polyarylene thioether. As a solvent used for the dissolution / reprecipitation, for example, N-methylpyrrolidone is preferably used from the viewpoint of efficiently dissolving the polymer. Further, as the reprecipitation solution and the washing solution, usually, for example, water, methanol or
Mixtures of these, particularly methanol and the like, can be suitably used. On the other hand, unreacted monomers, by-product low-molecular compounds, solvents, methanol, etc. in the mixture separated from the polymer are purified and recovered by ordinary distillation operations, and are repeatedly used in the reaction system or post-treatment process, or in various other ways. It can be effectively used for various applications. Further, the polymer film formed on the electrode can be used as it is after washing with methanol or the like. Polyarylene thioether such as polyphenylene thioether obtained by the method of the present invention is excellent in heat resistance, excellent in chemical resistance, resistance, strength, impact resistance, excellent in various mechanical properties such as abrasion resistance, in particular, Because it does not contain salts that degrade insulation resistance, such as salt, which has been a problem in the past, it has extremely excellent electrical properties of insulation resistance, and because the polymer structure is substantially linear, It is an engineering plastic with excellent processability, and it is used in the fields of electronics, electricity, machinery, paints, automobiles,
Equipment parts, machine parts,
It is suitably used as a material or the like.

According to the present invention, since a specific raw material monomer is used and a specific polymerization method called electrolytic polymerization is used, the reaction conditions are mild, the production method is simple, and the raw material and the catalyst are used. An industrially advantageous method for producing polyarylene thioether, such as low cost, can be provided.

【Example】

Example 1 3,5-dimethylthiophenol (2.7
A solution prepared by dissolving 8 g) in 100 ml of dichloromethane was placed in an electrolytic cell, and electrolysis was performed at 1.7 V using a platinum plate (2 × 5 cm) as an electrode. After applying a current of 2 F / mol, a polymer (0.84 g) was obtained in the tank. Elemental analysis, IR spectrum analysis, and measurement of melting point were performed on this polymer, and the following results were obtained. Elemental analysis (theoretical): C 70.1 (70.6) H 5.7 (5.9) S 23.3 (23.5) IR spectrum: υ ^C-H = 2850,2925,2950,2980, ^{304 0 υ C = H = 1460,1575} σ C-H = 880 1 H-NMR = 23,67 13C-NMR = 21.9,125,127,140,144 Mn: 15000 mp: 213 ° C these data From the results, the obtained polymer is poly (3,
5-dimethyl-1,4-phenylene sulfide).

Example 2 3,5-diethylthiophenol (3.3
0 g) in 100 ml of acetonitrile was placed in an electrolytic cell, and two sets of graphite (2 × 5c) were used as electrodes.
m), constant current electrolysis was performed at a current density of 1 mA / cm ² . After applying a current of 0.24 F / mol, a white polymer thin film was obtained on the electrode. This polymer was subjected to elemental analysis, IR spectrum analysis, ¹ NMR analysis, measurement of number average molecular weight, and measurement of melting point, and the following results were obtained. Elemental folding (theoretical): C 73.05 (73.12) H 7.41 (7.36) S 19.46 (19.52) IR _{spectrum: υ C-H = 2950,2980,3050 υ} C ^{_{= C = 1460,1560 σ C-H}} = 860 1 H-NMR = 1.25,2.7,7.0 13 C-NMR = 16,28,127,131,141,150 Mn: 3200 mp: 202゜ C From these data and the like, the obtained polymer was poly (3,3)
5-diethyl-1,4-phenylene sulfide).

Example 3 2-methyl-3,5-dimethoxythiophenol (3.66 g) was dissolved in a mixed solution of 25 ml of dichloromethane and 25 ml of nitrobenzene, put in an electrolytic cell, and charged with 1.9 V using a platinum electrode (5 × 5 cm). Was electrolyzed. After 2 F / mol of electricity, the solution was reprecipitated in methanol to obtain a polymer (3.12 g). The following measurement results were obtained for this polymer. Elemental folding (theoretical): C 58.1 (59.3) H 5.51 (5.49) S 17.5 (17.6) IR _{spectrum: υ C-H = 2870 υ} C = C = 1370 ^{_{, 1470,1600 σ CH = 885 1 H}} -NMR: σ (CH 3) = 2.3,3.8 σ (phenyl) = 6.9 mp: from 225 ° C such as those data, obtained The polymer is poly (2-
Methyl-3,5-dimethoxy-1,4-phenylene sulfide).

Example 4 3,3 ', 5,5'-Tetramethyldiphenyl disulfide (5.56 g) was added to acetonitrile 95
The solution dissolved in 0.1 ml was placed in an electrolytic cell, and a platinum plate (2 × 5 cm) was used as an electrode, and 50 mV from 0 V to 2.0 V was used.
/ Sec and electrolysis was performed. After energizing at 1 F / mol, a polymer (1.28 g) was obtained in the tank and on the electrode. The following measurement results were obtained for this polymer. Elemental folding (theoretical): C 70.3 (70.6) H 5.82 (5.9) S 23.49 (23.5) IR spectrum: υ _C-H = 2850,2925,2950,2980 _{, 30 40 υ C = C =} 1460,1575 σ C-H = 880 1 H-NMR = 2.3 (methyl), 6.7 (phenyl) 13 C-NMR = 125,127,140,144,22 mp : 225 ° C From these data and the like, the obtained polymer was poly (3,
5-dimethyl-1,4-phenylene sulfide).

Embodiment 5 2, 2 ', 3, 3', 5, 5 ', 6, 6'
A solution obtained by dissolving 3.3 g of octamethyldiphenyl disulfide and 90 ml of propylene carbonate was placed in an electrolytic cell, and subjected to constant current electrolysis at a current density of ² mA / cm ² using two sets of graphite electrodes (2 × 2 cm). 2.5F / m
After passing the current, the solution was reprecipitated in methanol to obtain a white polymer (3.09 g). The following measurement results were obtained for this polymer. Elemental folding (theoretical): C 72.1 (73.1) H 7.30 (7.32) S 19.5 (19.5) IR _{spectrum: υ C-H = 2980 υ} C = C = 1465 , 1570 Mn: 6400 (soluble part) mp: 254 ° C. From these data and the like, it was confirmed that the obtained polymer was poly (2,3,5,6-tetramethyl-1,4-phenylene sulfide). confirmed.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 75/00-75/04

Claims (1)

(57) [Claims] 1. The general formula [1] (Wherein, in the formula [1], R ¹ and R ² are each methyl
Group, ethyl group, propyl group, butyl group, pentyl group,
Xyl group, heptyl group, octyl group having 1 to 1 carbon atoms
A lower alkyl group in the range of 5 and a methoxy group;
Toxic group, propoxy group, isopropoxy group, butoxy
Group, isobutoxy group, pentyloxy group
Represents a substituent selected from the group consisting of lower alkoxy groups in the range of 1 to 5 . R ³ and R ⁴ are a hydrogen atom, methyl
, Ethyl, propyl, butyl, pentyl,
A hexyl, heptyl, or octyl group having 1 carbon atom
A lower alkyl group in the range of from 5 to 5 , and a methoxy group,
Ethoxy, propoxy, isopropoxy, butoxy
The number of carbon atoms of the di, isobutoxy and pentyloxy groups
Represents a substituent selected from the group consisting of lower alkoxy groups in the range of 1 to 5 . Note that R ^{1 to} R ⁴ may be the same type or different types. )
And / or a thiophenol represented by the general formula [I
I] (In the formula [II], S represents a sulfur atom, and R ⁵
To R ⁸ are a methyl group, an ethyl group, a propyl group, a butyl
Group, pentyl group, hexyl group, heptyl group, octyl group
A lower alkyl group having 1 to 5 carbon atoms , and a methoxy group, an ethoxy group, a propoxy group,
Poxy, butoxy, isobutoxy, pentyloxy
And represents a group selected from the group consisting of lower alkoxy groups having 1 to 5 carbon atoms, which are groups. R ^{9 to} R
¹² represents a hydrogen atom, a methyl group, an ethyl group,
Pill, butyl, pentyl, hexyl, heptyl
A lower group having 1 to 5 carbon atoms, which is an octyl group
Alkyl group , or methoxy group, ethoxy group,
Xy, isopropoxy, butoxy, isobutoxy
Group, a pentyloxy group having 1 to 5 carbon atoms
That represents a lower alkoxy group. Note that R ^{5 to} R ¹² may be of the same type. A) producing a polyarylene thioether, which comprises subjecting the diphenyl disulfide represented by the formula (1) to electrolytic polymerization in the absence of a Lewis acid and / or a protonic acid.