JPH0464619B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for purifying polyarylene sulfide resin, and more specifically, the present invention relates to a method for purifying polyarylene sulfide resin, and more specifically, from a polyarylene sulfide resin containing salt, to polyarylene sulfide resin having a significantly low salt content. The present invention relates to a novel and useful method for purifying polyarylene sulfide resins, by which polyarylene sulfide resins can be easily obtained. This invention is utilized in the field of purification of polyarylene sulfide resins such as polyphenylene sulfide resins containing salts. Polyarylene sulfide resins such as polyphenylene sulfide resins with a low salt content obtained by the method of the present invention can be used as materials with high heat resistance and high strength, for example in electrical and electrical applications.
Can be used in electronic fields, etc. [Prior art and its problems] Polyarylene sulfide resins such as polyphenylene sulfide resins are thermoplastic resins that partially have thermosetting properties, and have excellent chemical resistance and good stability over a wide temperature range. It has excellent properties as an engineering plastic, such as mechanical properties and heat-resistant rigidity. Polyarylene sulfide resins such as polyphenylene sulfide resins are usually obtained by polymerizing a dihalogen aromatic compound and an alkali metal sulfide in a polar solvent. for example,
The production of polyphenylene sulfide resin is usually p
-It is carried out by polymerizing dichlorobenzene and sodium disulfide in a polar solvent (Japanese Patent Publication No. 12240/1989, etc.), but salts such as common salt produced by the polymerization reaction are usually contained in the resin. 1000～
Approximately 3000ppm remains. If salt such as table salt remains, when polyarylene sulfide resin such as polyphenylene sulfide resin is applied to the electrical and electronic fields, the moisture-resistant insulation of the circuit will decrease and cause malfunction. The resin needs to be purified again to remove the salts. Conventionally, a method of carrying out a polymerization reaction in the presence of polyoxyethylene ether has been proposed as a method for producing polyphenylene sulfide resin with a low salt content such as common salt (Japanese Patent Application Laid-open No. 74127/1983).
There is a problem in that the polyoxyethylene ether needs to be removed after the polymerization reaction is completed, which is not practical. On the other hand, as a method for purifying polyphenylene sulfide resin, a method has been proposed in which heat treatment is performed at a high temperature of 238°C using sodium carbonate or the like in an aqueous slurry (Japanese Patent Application Laid-open No. 108136/1982).
There is a problem that the removal efficiency of salt is low. In addition, a purification method in which polyphenylene sulfide resin is brought into contact with a mixed solvent of a polar aprotic solvent and ethylene glycol has been proposed (Japanese Patent Application Laid-open No. 108135/1983), but the development of a more useful method is desired. was. [Object of the Invention] This invention has been made based on the above circumstances. That is, an object of the present invention is to solve the above-mentioned problems and to produce a polyarylene sulfide such as a polyphenylene sulfide resin in which the salt content is significantly reduced from a polyarylene sulfide such as a polyphenylene sulfide resin containing a salt. It is an object of the present invention to provide a new and useful method for purifying polyarylene sulfide resin, which makes it possible to easily obtain arylene sulfide resin. [Means for solving the above problems] The outline of the present invention for solving the above problems is to provide a method for purifying a salt-containing polyarylene sulfide resin. A method for purifying a polyarylene sulfide resin, which comprises contacting the polyarylene sulfide resin with a polar solvent and polyvinyl alcohol. The polyarylene sulfide resin containing the salt in the present invention is a polyarylene sulfide resin containing an alkali metal salt. Examples of the alkali metal salts include alkali metal halides, alkali metal carboxylates, and alkali metal sulfonates. Among these, alkali metal halides can be efficiently desalted from polyarylene sulfide resins by the method of the present invention. Specific examples of the alkali metal halides include:
Lithium fluoride, sodium fluoride, lithium chloride, potassium fluoride, rubidium fluoride, cesium fluoride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, sodium bromide, potassium bromide, rubidium bromide, cesium bromide , lithium iodide, sodium iodide, rubidium iodide, cesium iodide, etc.
Among them, lithium chloride, sodium chloride, and even sodium chloride often appear as substances to be desalted in the production of polyarylene sulfide resins, and are advantageously desalted by the method of the present invention. Examples of the alkali metal carboxylates mentioned above include compounds such as lithium acetate, sodium acetate, potassium acetate, rubidium acetate, cesium acetate, lithium propionate, lithium benzoate, etc. Among them, lithium acetate is used for polyarylene It often appears as something to be desalted in the production of sulfide resins and is conveniently removed by the process of this invention. Examples of the alkali metal sulfonate include sodium benzenesulfonate. The polyarylene sulfide resin to which the present invention is applied usually has a concentration ^of 500
Examples include those containing alkali metal salts in a content of ~5000 ppm, preferably 1000 to 3000 ppm. The polyarylene sulfide resin containing the above-mentioned salt in the present invention may contain one or more of the above-mentioned alkali metal salts as the alkali metal salt. The polyarylene sulfide resin related to the salt-containing polyarylene sulfide in the present invention is characterized in that the structure of the polymer forming the resin or the structure of the main part of the polymer is such that the sulfur atom and the carbon of the aromatic ring are It has a structure in which atoms are repeatedly bonded alternately. The structure of the polymer constituting the resin or the main part of the polymer is usually the following (formula a): (Here, S represents a sulfur atom. ^{R 1} , R ² ,
R ³ and R ⁴ are hydrogen, C ₁ to C ₂₀ alkyl group, C ₅ to
represents a _C20 cycloalkyl group, a _C6 - _C24 aryl group, a _C7 - _C24 alkaryl group or a _C7 - _C24 aralkyl group, and ^R1 , ^R2 , ^R3 , ^R4 is 2
may combine to form an aromatic ring or a heterocyclic ring, and -S-, -O-,

[expression] or

[Formula] A branched structure may be formed by bonding to other polyarylene sulfide units.
n is usually an integer in the range of 1 to 1000, preferably 3 to 600. ) can be expressed as Among these resins, polyphenylene sulfide resins are preferred because they can effectively exhibit the effects of the present invention. The polyarylene sulfide resin containing the salt of the present invention is produced when a dihalogen aromatic compound and an alkali metal sulfide are reacted in a polar solvent in the presence or absence of various additives. . After the reaction is complete, the polyarylene sulfide can be separated directly from the reaction solution by standard methods, e.g. by filtration or centrifugation, or
For example, it can be obtained by adding water and/or diluted acid and then fractionating it from the reaction solution. Following the filtration step, the polymer is generally recovered by washing, such as with water, to remove any inorganic components that may adhere to the polymer, such as alkali metal sulfides and alkali metal halides. In this way, the recovered polyarylene sulfide resin usually contains 500 to 5000 ppm of alkali metal salts such as alkali metal halides even after washing with water, washing, and extraction as described above. . For example, the polyphenylene sulfide resin is produced by reacting p-chlorobenzene and sodium sulfide in the solvent, but sodium ions are present in the produced resin.
It is known that about 1000 to 3000 ppm remains. The polyarylene sulfide resin containing the salt used in the present invention may be produced not only by the above-mentioned production method but also by any other method. .
In other words, whether it is a commercial product or a sample product,
It may be newly manufactured. For example, polyarylene sulfide resins containing the above-mentioned salts are manufactured by Phillips Corporation in the United States and are commercially available. The polyvinyl alcohol in the present invention is
It is an ordinary polyvinyl alcohol whose main chain structure or main part structure of the polymer can be represented by repeating [ _-CH2CH (OH)]- units. In the method of the present invention, polyvinyl alcohols having a degree of polymerization generally in the range of 30 to 5,000, particularly 200 to 2,000 are preferably used. If the degree of polymerization of the polyvinyl alcohol is less than 30, the removal rate of salts in the polyarylene sulfide resin may be low; if it is greater than 5000,
Polyvinyl alcohol may remain in the resin. The polyvinyl alcohol may be produced by any method; for example, a commercially available product may be used as is. Below, a method for purifying polyarylene sulfide containing the above-mentioned salt of the present invention will be explained. Polyarylene sulfide resin containing the above salt [hereinafter sometimes referred to as component (A)]. ] and the polyvinyl alcohol [hereinafter sometimes referred to as component (B). ] and a polar solvent [hereinafter sometimes referred to as component (C). ] and contact each other [here, contact means mixing, dissolving, dispersing, etc.]
let The temperature in this case is not particularly limited, but
This is usually done under heating at 100 to 250°C. After this contact heat treatment, it is cooled to room temperature to 80°C, and the solvent and the like are removed by a conventional separation method such as filtration or centrifugation, and the polyarylene sulfide resin is recovered. This recovered resin can be washed by a standard washing process such as washing with water, washing with other solvents, extraction process, etc., but in the method of the present invention, The resin can be further effectively washed and purified by washing with hot water. The polyarylene sulfide resin washed and purified by this hot water washing treatment is separated and recovered as a solid by a conventional separation method such as filtration or centrifugation. The recovered resin is dried by standard methods commonly used to obtain purified polyarylene sulfide. The salt content in the purified polyarylene sulfide obtained by such a method is
Typically, it can be significantly lower than 30 ppm. Note that the action of polyvinyl alcohol has not yet been clearly explained theoretically. Examples of the polar solvent used in the purification method of the present invention, that is, component C, include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-
Dipropylacetamide, N,N-dimethylbenzoic acid amide, caprolactam, N-methylcaprolactam, N-ethylcaprolactam N-isopropylcaprolactam, N-isobutylcaprolactam, N-propylcaprolactam, N-butylcaprolactam, N-cyclohexylcaprolactam , N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-isopropyl-2-
pyrrolidone, N-isobutyl-2-pyrrolidone,
N-propyl-2-pyrrolidone, N-butyl-2
-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-methyl-3-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-
Methyl-3-methyl-2-pyrrolidone, N-methyl-3,4,5-trimethyl-2-pyrrolidone,
N-methyl-2-piperidone, N-ethyl-2-
Piperidone, N-isopropyl-2-piperidone, N-isobutyl-2-piperidone, N-methyl-6-methyl-2-piperidone, N-methyl-
3-ethyl-2-piperodone, N-methyl-2-
Oxo-hexamethyleneimine, N-ethyl-2
-oxo-hexamethyleneimine, N-ethyl-
2-oxo-hexamethyleneimine, tetramethylurea, 1,3-dimethylethyleneurea, 1,3
-dimethylpropylene urea, 1-methyl-1-oxosulfolane, 1-ethyl-1-oxosulfolane, 1-phenyl-1-oxosulfolane, 1
-Methyl-1-oxosulfolane, 1-methyl-
Examples include 1-oxophosphane, 1-propyl-1-oxophosphane, 1-phenyl-1-oxophosphane, and the like. These solvents may be used alone or in combination of two or more. Further, among the various polar solvents mentioned above, N-alkyl lactams and N-alkylpyrrolidone are preferred, and N-methylpyrrolidone is particularly preferred.
These solvents may be used alone or in combination of two or more. The blending ratio of the components (A), (B), and (C) in the method of the present invention is as follows. That is, the (A) component/(B) component (weight ratio) is usually 1-100, preferably 2-10. This blending ratio
If it is larger than 100, the removal rate of salts in the polyarylene sulfide resin may not be sufficient;
On the other hand, if it is less than 1, it may become difficult to remove the polyvinyl alcohol or its decomposition products. In addition, the (A) component/(C) component (weight ratio) is usually
It is 0.01-0.5, preferably 0.02-0.3. If this blending ratio is larger than 0.5, the salt removal efficiency may decrease, while if it is smaller than 0.01, productivity may decrease. In the method of the present invention, when blending the components (A), (B), and (C), the order and method of adding and blending each component may be arbitrary. However, it is usually preferable to dissolve or disperse component (B) in component (C) and then mix it with component (A). Note that there is no particular restriction on the temperature at which the above-mentioned components are blended, but it generally suffices as long as it is at room temperature or above. In the present invention, the temperature of the contact heat treatment of the components (A), (B), and (C) is set to 150°C or higher, preferably
It can also be carried out at a temperature of 160°C or higher. This is because by setting the temperature of the heat treatment to 150° C. or higher, the polyvinyl alcohol used can be easily discharged from the system as a ketone, aldehyde, etc. If the temperature of the heat treatment is less than 150°C, the purification effect of the resin will be lowered, such as polyvinyl alcohol remaining in the resulting polyarylene sulfide resin, and a post-process such as hot water treatment will be required. The pressure during the contact heat treatment is not particularly limited, but is usually from the natural pressure of the heating system to 50 kg/cm ² preferably,
The natural pressure of the system is about 3 kg/cm ² . Heat treatment time is usually 10 minutes to 20 hours, preferably
30 minutes to 10 hours. As the contact heat treatment method, normal standard methods such as a batch method, a semi-batch method, and a continuous flow method can be used, but in order to increase the contact efficiency,
It is preferable to stir the system thoroughly. Also,
A method in which vapors of ketones, aldehydes, etc. produced by thermal decomposition of polyvinyl alcohol etc. are discharged from the system during the contact heat treatment can also be suitably used. At this time, it is preferable to carry out the reaction in an inert gas flow such as nitrogen gas. The hot water washing treatment is usually carried out at a temperature range of 60 to 200°C, preferably 80 to 130°C. When molding the polyarylene sulfide resin obtained by the method of this invention into various products,
Other polymers, pigments and fillers, such as graphite, metal powders, glass powders, quartz powders or glass fibers, carbon fibers, boron fibers, or additives commonly used for polyarylene sulfides, such as conventional stabilizers. It can be mixed with a mold release agent or mold release agent. Polyarylene sulfide resins such as polyphenylene sulfide resins obtained by the method of this invention have extremely low salt content such as common salt in the resin, so they have high moisture resistance and electrical insulation properties. Because it can be produced as a high molecular weight resin with low melt flow, it can be used as a matrix resin for various molded products and composite materials, and can also be made into various molded products, films, fibers, etc. It is an excellent engineering plastic that can be suitably used not only for mechanical parts but also for electrical and electronic parts. [Effects of the Invention] According to the present invention, a polyarylene sulfide resin containing salt such as common salt is purified, and a polyarylene sulfide resin having an extremely low salt content such as common salt or the like of 30 ppm or less is obtained. Fido resin can be easily obtained. The polyarylene sulfide resin purified by this method and having a low salt content can be suitably used in the electrical and electronic fields. [Examples] Next, Examples and Comparative Examples will be shown to further specifically explain the present invention. (Example 1) 500ml equipped with stirrer, cooler, and _N2 inlet tube
Commercially available polyphenylene sulfide (PPS) (Ryton V-1 manufactured by Phillips,
200 g of N ^- methylpyrrolidone (NMP) in which 5 g of polyvinyl alcohol (PVA) (manufactured by Wako Pure Chemical Industries, Ltd., polymerization degree = 500) was dissolved. was dispersed and heated and stirred at 250 RPM for 4 hours at 200° C. in a N ₂ stream. After the scheduled time, cool to room temperature and remove from NMP.
Filter the PPS and disperse it again in 200ml of ion-exchanged water.
Stirring at 100°C for 60 minutes was performed twice. The Na ⁺ content of the recovered PPS was measured by atomic absorption method and was found to be 20 ppm. (Comparative Example 1) The same procedure as in Example 1 was performed except that PVA was not used. Na ⁺ in the obtained PPS is
It was 640ppm. (Comparative Example 2) 20g of commercially available PPS used in Example 2 was added to ion-exchanged water.
The mixture was dispersed in 200 ml and washed by stirring at 150° C. for 4 hours in a N ₂ stream. Na ⁺ in recovered PPS is 1350ppm
It was hot. (Example 2) The same procedure as in Example 1 was carried out except that 10 g of PVA with a degree of polymerization of 1500 and 1 kg of NMP were used. The Na ⁺ content in the recovered PPS was 17 ppm. (Example 3) The same procedure as in Example 1 was carried out except that 25 g of PVA and 1 kg of NMP were used. The Na ⁺ content in the recovered PPS was 8 ppm. (Example 4) The same procedure as in Example 1 was carried out except that the temperature was changed from 200°C to 170°C and 4 hours were changed to 2 hours. The Na ⁺ content in the recovered PPS was 28 ppm.

Claims (1)

[Claims] 1. A method for purifying a polyarylene sulfide resin containing a salt, which comprises bringing the polyarylene sulfide resin containing a salt into contact with a polar solvent and polyvinyl alcohol. Method for purifying id resin. 2. The method for purifying a polyarylene sulfide resin according to claim 1, wherein the polyarylene sulfide resin is a polyphenylene sulfide resin. 3 The polyvinyl alcohol has a degree of polymerization of 200 to
2,000 polyvinyl alcohol.