JPH0686528B2 - Method for removing sodium salt from polyphenylene sulfide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for removing sodium salt from polyphenylene sulfide.

<Prior art and problems> Polyphenylene sulfide (hereinafter abbreviated as PPS) has excellent chemical resistance, good mechanical property retention in a wide temperature range, hardness at high temperature, and other excellent properties as an engineering plastic. Have

However, sodium salts of about 1000 to 5000 ppm usually remain in PPS, which has been an obstacle to applying pps molded products to the field of electric and electronic parts. In other words, when using PPS, which contains a large amount of ionic sodium salt, for sealing electronic components such as ICs and transistors, it may reduce the moisture-proof insulation of the circuit or cause malfunctions. It caused the inconvenience.

As a method for removing the sodium salt from PPS, a method of heating and extracting with an organic solvent (JP-A-57-108135) or 200 ° C.
The above method of extracting with hot water (JP-A-57-108136)
Have been proposed. However, the former requires a large amount of an expensive solvent such as N-methylpyrrolidone, and the latter has the problem that a high-pressure pot of 30 kg / cm ² or more must be used, so that it is an industrially advantageous method. It is hard to say.

In addition, PPS is Since it has a structure and is hydrophobic in nature and does not easily leak to water, the powder floats even if it comes into contact with water and a sufficient cleaning effect cannot be obtained.
Especially, it was difficult and time-consuming to remove the sodium salt contained in the porous PPS powder.

<Means for Solving Problems> In view of the above situation, the present inventors have earnestly studied a method for inexpensive removal of sodium salt from PPS, and as a result, PP
The present invention has been accomplished by finding that sodium salt can be removed from PPS at low cost by mixing S, water and a surfactant and heating the mixture.

That is, the present invention, in removing the sodium salt from the sodium salt-containing PPS, PPS, water and a surfactant are mixed, a method for removing the sodium salt from polyphenylene sulfide, characterized by heat treatment. It is provided.

The PPS in the present invention can be obtained by various known methods. For example, as a method for producing the same, p-dichlorobenzene is polymerized in the presence of sulfur and sodium carbonate, sodium sulfide or sodium hydrosulfide and sodium hydroxide or hydrogen sulfide and sodium hydroxide or sodium amino in a polar solvent. Polymerization in the presence of alkanoate, self-condensation of p-chlorothiophenol and the like can be mentioned. However, sodium sulfide and p- A general method is to react dichlorobenzene. At this time, in order to adjust the degree of polymerization, an alkali metal salt of carboxylic acid or sulfonic acid may be added, or alkali hydroxide may be added. Also, if it is 30 mol% as a copolymerization component, a meta bond Ortho-join Ether bond Sulfone bond Biphenyl bond Carbonyl bond Substituted phenyl sulfide bond Here, R represents an alkyl group, a nitro group, a phenyl group, an alkoxy group, a carboxylic acid group or a metal base of carboxylic acid), trifunctional bond It does not matter if it contains such a compound as long as it does not significantly affect the crystallinity of the polymer, but the copolymerization component is preferably 10
It is preferably not more than mol%. Particularly, when a phenyl, biphenyl, naphthyl sulfide bond or the like having a functionality of 3 or more is selected for the copolymerization, the content is preferably 3 mol% or less, more preferably 1 mol% or less.

As a specific method for producing such PPS, for example, (1) a reaction between a halogen-substituted aromatic compound and an alkali sulfide (US Pat. No. 2513188, JP-B-44-27671 and JP-B-45-33)
68), (2) Condensation reaction of thiophenols in the presence of an alkali catalyst or a copper salt (US Pat. No. 327416).
5 and British Patent No. 1160660), (3) Condensation reaction of an aromatic compound with sulfur chloride in the presence of a Lewis acid catalyst (see Japanese Examined Patent Publication No. 46-27255 and Belgian Patent No. 29437), (4) ) Method for producing polymer PPS (Japanese Patent Publication No. 52-12240)
No. 54, Japanese Sho 54-8719, Japanese Sho 53-25588, Japanese Sho 57-33
4, JP-B-55-43139, U.S. Pat.
24886) and the like.

The sodium salt in the present invention means a salt formed during the polymerization reaction of PPS, a salt derived from unreacted raw materials and impurities in the raw materials, and a salt capable of becoming ionic Na. For example, when using sodium chloride, sodium bromide, sodium iodide, sodium fluoride, sodium sulfide, sodium hydroxide, sodium sulfite, sodium thiosulfate, sodium sulfate, sodium carbonate and N-methylpyrrolidone as a reaction solvent Live N-methyl-4
-Sodium aminopropionate and its derivatives are mentioned.

As the surfactant in the present invention, carboxylate type,
Anionic surfactants such as sulfate ester type, sulfonate type and phosphate ester type, cationic surfactants such as amine salt type and quaternary ammonium salt type, amino acid type,
Examples thereof include amphoteric surfactants such as betaine type and nonionic surfactants such as polyglycol type, polyhydric alcohol type, fatty acid amide type and amine oxide type. From the viewpoint of the effect of removing alkali metal salts, it is particularly preferable to use an activator having excellent wettability and permeability. Such suitable surfactants include polyoxyethylene alkylphenyl ethers and nonionic surfactants such as polyoxyethylene alkyl ethers having relatively short alkyl groups (C _8-12 ), dialkyl sulfosuccinates, Anionic surfactants such as dodecylbenzene sulfonate, lauryl sulfate, alkylnaphthalene sulfonate, oleic acid butyl ester sulfate, and fluorine-based surfactants such as perfluoroalkyl sulfonate and perfluoroalkyl ethylene oxide adduct An agent is illustrated. It is desirable that all of these surfactants have a property that, when made into a 0.5 wt% aqueous solution, 0.5 g of PPS can be precipitated within 5 minutes, preferably within 2 minutes.

The water of the present invention may be any of neutral water such as tap water, ion-exchanged water and pure water, but tap water is usually used. This water may be preheated,
A surfactant may be mixed in advance.

In the present invention, water and a surfactant may be added to PPS and mixed to form a slurry, or water, a surfactant and PPS may be mixed at the same time, but usually PPS is added and mixed to water and a surfactant. Then, it can be made into a slurry. Although the PPS concentration in the slurry is not particularly limited, it is preferably 40% by weight or less from the viewpoint of the fluidity of the slurry. The amount of the surfactant used in the present invention is 0.01 to 10% by weight, preferably 0.02% with respect to water.
Used at ~ 5% by weight. Even if the surfactant is added in excess of the required amount, the effect of removing sodium salts does not change,
If the amount used is too small, the removal effect of the present invention cannot be obtained.

In the present invention, the slurry is heat-treated, but the heating temperature is 80 ° C.
Or more, preferably 100 ℃ or more, more preferably 100 ~ 160
℃ is required. If the heating temperature is too low, the removal of sodium salt will be insufficient.

The method of the present invention is preferably 1 to 6 times for PPS,
More preferably, by repeating 2 to 4 times, a more reliable sodium salt removing effect can be obtained. The treatment time of PPS according to the method of the present invention is 5 to 60 minutes, preferably 10 to 2
It takes about 0 minutes. Further, the PPS slurry may be passed and washed with hot or hot water containing no surfactant.

In the removal method of the present invention, conventionally known batch, semi-continuous or continuous various solid extraction methods can be adopted.
For example, in the case of batch operation, depending on the amount of alkali metal salt in PPS, desired purity, appropriate slurry concentration, the amount of surfactant used, heating temperature, treatment time, the number of cycles may be selected within the above range. it can.

<Effect> According to the removal method of the present invention, the sodium salt can be removed at a relatively low heating temperature by using the surfactant, so that the manufacturing cost can be greatly reduced. The PPS obtained according to the present invention has improved electrical characteristics and hygroscopicity, and thus is suitable for injection molded products such as electric and electronic parts, tubes,
Also used for pipes, fibers, films and blow molded products.

<Examples> Hereinafter, the present invention will be specifically described with reference to Examples. Examples 1 to 8 and Comparative Examples 1 and 2 A 1-stainless steel autoclave equipped with a stirring blade was charged with Na content of 2300 PPm, 30 g of PPS having an average particle size of 30 μm, 300 g of water and a surfactant as shown in Table 1. The mixture was heated and stirred at the temperature for 1 hour. Table 1 shows the pressure inside the container at this time. After cooling to 60 ℃, separate the PPS by suction excess,
Further, it was washed with 300 g of warm water and dried. The alkali metal salt remaining in this PPS is shown in Table 1 as the Na content.

The Na content in this PPS is the value in ppm units obtained by flame photometric analysis after sulfuric acid decomposition of a sample in a platinum crucible.

As described above, it was confirmed that the method of the present invention exerts an excellent sodium salt removing effect at a relatively low heating temperature.

Claims (1)

[Claims] 1. Removal of sodium salt from polyphenylene sulfide containing sodium salt, wherein polyphenylene sulfide, water and a surfactant are mixed and heat-treated to remove sodium salt from polyphenylene sulfide. Method.