JPS6333774B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new and useful method for purifying polyphenylene sulfide, and more particularly to a method comprising heat treating polyphenylene sulfide in an aromatic solvent. Polyphenylene sulfide (hereinafter abbreviated as "PPS") can be melt-molded into engineering plastics, films, fibers, etc. using methods such as injection molding or extrusion. It is widely used in various molded products that take advantage of its chemical properties. A common method for producing PPS is to react an aromatic halide such as p-dichlorobenzene with sodium sulfide in an organic amide solvent, as described in Japanese Patent Publication No. 3368/1983.
On the other hand, as an improved polymerization reaction method for obtaining PPS with a high degree of polymerization, the addition of an alkali metal carboxylate as a polymerization aid is also disclosed in Japanese Patent Publication No. 52-12240. Separately, when such PPS is applied to films, fibers, or various electrical or electronic parts, the salt contained in the polymer ( It is desirable to minimize the amount of inorganic electrolyte impurities (also called ash) such as NaCl). In particular, when the PPS is used as a coating or sealing material for electronic components such as ICs, transistors, and capacitors, there is a risk of leakage due to corrosion or disconnection of electrodes and wiring of these components. Inconveniences such as an increase in current occur, but in order to prevent such troubles from occurring, it is absolutely necessary to use a polymer in which electrolyte impurities as described above are reduced as much as possible. By the way, in the case of the PPS production method as described above, as a result of the secondary production and precipitation of almost the same amount of salt as the produced polymer, there is PPS contains a large amount of residual salt, so PPS with a high electrolyte impurity content
In the resin composition obtained using
The drawback is that the electrical characteristics are significantly inferior to those using PPS. Therefore, as a measure to eliminate these defects and improve the electrical characteristics, PPS powder obtained through normal processing was repeatedly boiled in deionized water for a long time. In this line,
A method of reducing impurities as much as possible by eluting water-extractable electrolyte components from PPS is described in JP-A-55-156342. However, according to the research conducted by the present inventors, when reducing impurities by the above-mentioned hot water boiling extraction method, it not only takes an unnecessarily long time; The content of electrolyte impurities has also not been reduced as much as expected, and the disadvantage is that no matter how many times or dozens of times the extraction operation is repeated, a polymer with higher purity cannot be obtained. However, on the other hand, the PPS can be prepared by heating a mixture of PPS and an alkali metal carboxylate or lithium halide in an organic amide solvent, as disclosed in U.S. Pat. No. 4,071,509. Even when methods are tried to reduce the content of inorganic components, PPS purified by any of these methods cannot be used as a coating or sealing material for electronic components. The purity was still not satisfactory. However, as described above, the present inventors
As a result of intensive studies to establish a useful purification method that eliminates the drawbacks of various conventional purification methods, we found that organic solvents containing one or more aromatic nuclei in one molecule, such as aromatic hydrocarbons (hereinafter referred to as When the PPM polymer was heat-treated in an aromatic solvent (referred to as an aromatic solvent), only the impurities consisting of electrolyte components containing sodium ions could be removed without any decomposition of the polymer itself, and the content of such inorganic electrolyte impurities could be removed. The present invention was completed by discovering that the amount can be efficiently reduced in an extremely short period of time. That is, in the present invention, PPS containing impurities consisting of electrolyte components is heated to 0.1
The present invention provides a method for purifying PPS of extremely high purity, which is characterized in that it is possible to efficiently reduce the content of impurities by removing only the above-mentioned impurities without decomposing the polymer by treatment for ~10 hours. In carrying out the method of the present invention, the PPS used is an MI (melt index) value measured according to the method of ASTM D1238-70,
In other words, a sample with a polymer solution concentration of 10,000 (g/10 min) or less when measured at a load of 5 kg and a temperature of 315.6°C (600〓), or an intrinsic viscosity of 0.4 g/100ml, is placed in α-chlornaphthalene at 206°C. (403〓)
The value is calculated by dividing the natural logarithm of the "relative viscosity value" based on the viscosity measured by the "polymer concentration", that is, the following formula [η] = ln (relative viscosity value) / polymer concentration [ ], and the polymer concentration A suitable PPS is one in which the value obtained by extrapolating to infinitesimal, ie, "zero" is 0.05 or more. In addition, the PPS used in carrying out the method of the present invention is the following formula: The structure with the repeating unit shown is 70
If it contains mol% or more, preferably 90 mol% or more, it is copolymerized with other components, or has a partially branched structure, or a partially crosslinked structure. Of course, it can be used even if In this case, typical copolymer components include

Trifunctional units such as [Formula],

Ethe like [formula] etc. unit,

Sulfone units such as [Formula],

Ketones such as [formula] unit,

Meta units such as [formula] or general formulas [However, R in the formula is an alkyl group, a phenyl group,
It is an alkoxy group, carboxyl group, amino group, sulfone group, or nitro group. ] There are substituted sulfide units as shown in the following. Further, in carrying out the method of the present invention, the amount of electrolyte impurities contained in the polymer is arbitrary, and there is no particular restriction on the amount of electrolyte impurities contained in the PPS used, but at least 0.2% by weight of, for example, sodium・Those containing ions as electrolyte components are used. The above-mentioned PPS is a special public service issued in 1973 as mentioned above.
It is manufactured according to the method described in Japanese Patent No. 3368 and Japanese Patent No. 52-12240. In the method of the present invention, it is necessary to use an aromatic solvent as a solvent to separate and remove impurities such as common salt from the PPS polymer. Such aromatic solvents are organic solvents containing one or more aromatic nuclei in one molecule, such as aromatic hydrocarbons, aromatic alcohols, aromatic ethers, halogenated aromatic hydrocarbons, aromatic nitriles, and aromatic amines. It is. Representative aromatic solvents include toluene, xylene, ethylbenzene, naphthalene,
Aromatic hydrocarbons such as tetralin, cumene, diphenyl, triphenyl; Aromatic alcohols such as benzyl alcohol, phenol, cresol, p-chlorophenol; Benzyl ethyl ether,
Aromatic ethers such as anisole, ethyl phenyl ether, diphenyl ether; fluorobenzene, chlorobenzene, 1-chloronaphthalene,
Examples include halogenated aromatic hydrocarbons such as dichlorobenzene; aromatic nitriles such as benzonitrile; aromatic ketones such as benzophenone; and aromatic amines such as quinoline. Good too. Among these, diphenyl ether is particularly preferred. The amount of the aromatic solvent used is preferably in the range of 1 to 100 parts by weight per 1 part by weight of the above-mentioned PPS. On the other hand, when carrying out the method of the present invention, the following polyoxyalkylene compounds can be added in order to further enhance the effect of removing inorganic electrolyte impurities as described above. Typical polyoxyalkylene compounds include polyoxyalkylene glycols with a number average molecular weight (hereinafter abbreviated as "molecular weight") of 150 or more, such as polyoxyethylene glycol or polyoxypropylene glycol; The terminal hydroxyl group in these glycols is C ₁
Examples include nonionic surfactants etherified or esterified with an alkyl group and/or an aryl group consisting of ~ _C30 , among which particularly preferred compounds include polyoxyethylene, monooctyl ether, and polyoxyethylene.・Monolauryl ether, polyoxyethylene monooctylphenyl ether, polyoxyethylene, nonylphenyl aldehyde condensate,
Polyoxyethylene monolauryl ester; or polyoxypropylene monooctyl ether, polyoxypropylene monolauryl ether, polyoxypropylene monooctylphenyl ether, polyoxypropylene, nonylphenyl aldehyde condensate, polyoxypropylene mono lauryl ester, etc. These may be used as a mixture of two or more. Furthermore, such polyoxyalkylene compounds include 15-crown-5,18-crown-6,
Dibenzo-18-crown-6, dicyclohexyl-18-crown-6, dibenzo-24-crown-
Crown ether compounds such as 8 or dicyclohexyl-24-crown-8 can also be used. The appropriate amount of these polyoxyalkylene compounds to be used is 0.01 to 200% by weight, preferably 0.5 to 100% by weight, based on the PPS. Furthermore, as with the polyoxyalkylene compound, an alkyl phenyl formaldehyde condensate represented by the following formula A can also be used as an additive to further enhance the effect of separating and removing inorganic electrolyte impurities. Formula A: (In the formula, R ¹ is an alkylene group having 4 to 4 carbon atoms,
R ² is hydrogen, or an alkyl group and/or an aryl group having 1 to 30 carbon atoms; m and n each represent an average degree of polymerization; 2 to 50, preferably 2 to 10; 0 to 90, preferably 3 to 20; represents. ) Examples of R ¹ in the above formula A are -CH ₂ CH ₂ -,

[Formula] (-CH ₂ )- ₃ ,

[Formula] (-CH ₂ )- ₄ ,

[Example 1]

In an autoclave equipped with a stirrer, 1993 g of N-methylpyrrolidone and sodium sulfide 2.7 hydrate were added.
537g (4.1 moles), 1.6g of sodium hydroxide
(0.04 mol) and 144 g of sodium benzoate
(1.0 mol) and gradually raised the temperature to 200℃ under a nitrogen atmosphere over about 2 hours while stirring.
102ml of water was distilled off. Next, after cooling the reaction system to 150°C, 603g (4.1 mol) of p-dichlorobenzene and 250g of N-methylpyrrolidone were added, and the reaction was carried out at 230°C for 2 hours and then at 260°C for 3 hours. The internal pressure at the end of the polymerization reaction was 9.0 Kg/cm ² . After that, the autoclave was cooled and the contents were filtered, and the cake (solid content) was washed three times with hot water and twice with acetone, and then washed with 120 ml of water.
After drying at °C, 412 g of pale gray-brown granular PPS was obtained (yield = 93%). The intrinsic viscosity [η] of the PPS obtained here is 0.27
And the content of sodium ions was 1230 ppm. Next, 20 g of this PPS, 200 g of diphenyl ether, and 26.6 g of sodium benzoate were charged into an autoclave equipped with a stirrer, the temperature was raised under a nitrogen atmosphere, and heating was continued at 265° C. for 2 hours while stirring. The internal pressure at the end of heating was 1.0 Kg/cm ² . After that, the autoclave was cooled and the contents were separated, and the cake (solid content) was washed three times with hot water and then twice with acetone, and then dried to recover the polymer, yielding 20 g of polymer. However, the intrinsic viscosity value of this polymer was 0.29, and the sodium ion content was 26 ppm. In this way, when the method of the present invention is followed, not only is the content of impurities consisting of sodium ions in PPS significantly reduced, but there is no decomposition of the polymer, but rather the molecular weight is slightly increased. Favorable results are obtained. [Example 2] The same operations as in Example 1 were repeated, except that sodium benzoate was not used in the step of purifying the polymer obtained by polymerization in Example 1, and the final result was obtained. The obtained polymer has an intrinsic viscosity value of
0.26 and the sodium ion content was 25 ppm. This indicates that similar effects can be expected even in the absence of sodium benzoate. [Comparative Example 1] The same operation as in Example 1 was repeated, except that 200 g of water was used instead of diphenyl ether and heated at 200° C. for 2 hours. Internal pressure at the end of heating is 15.3
It was Kg/ ^cm2 . The finally obtained polymer had a slightly lower intrinsic viscosity value of 0.25, and the sodium ion content was still high at 980 ppm. [Comparative Example 2] The same operation as in Example 2 was repeated except that 200 g of N-methylpyrrolidone was used instead of diphenyl ether, and the intrinsic viscosity of the final polymer obtained was as low as 0.17. The sodium ion content was 570 ppm, which was not satisfactory. [Examples 3 to 10] In the process of purifying PPS obtained by polymerization in Example 1, the same procedure was carried out except that the solvent, alkali metal salt, and the amount used were changed as listed in Table 1. This was carried out in the same manner as in Example 1. The results are shown in Table 1. [Examples 11 to 14] Instead of sodium benzoate, 418 g (4.1 mol) of lithium acetate dihydrate was used, and 1.8 g (0.01 mol) of 1,
While adding 2,4-trichlorobenzene, N-
A polymerization reaction was carried out in the same manner as in Example 1, except that the amount of methylpyrrolidone was increased to 310 g.
The amount of distilled water during this period was 250 ml, the internal pressure at the end of polymerization was 9.6 Kg/ ^cm2 , the yield and yield of pale gray-brown granular PPS was 394 g and 89%, and this PPS had an intrinsic viscosity value of was 0.34, and the sodium ion content was 860 ppm. Thereafter, in the step of purifying this polymer, the same procedure as in Example 1 was carried out except that the solvent, polyoxyalkylene compound, and amount used were changed as shown in Table 2. The results are shown in Table 2. [Examples 15 to 19] In the process of purifying the polymer obtained by the polymerization shown in Examples 11 to 14, the solvent, alkyl phenyl formaldehyde condensate, and the amount used were changed as listed in Table 3. Example 1 except that
I went in the same way. The results are shown in Table 3.

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Claims (1)

[Claims] 1 Polyphenylene sulfide containing impurities consisting of electrolyte components is treated in an organic solvent containing one or more aromatic nuclei in one molecule at 100 to 350°C for 0.1 to 10 hours to reduce the content of the electrolyte components. A method for purifying polyphenylene sulfide, characterized by reducing the amount of polyphenylene sulfide.