JP2003026804A - Method for polyarylene sulfide production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyarylene sulfide which suppresses corrosion on the surface of a reactor during a dehydration process and has a high whiteness. SOLUTION: The polyarylene sulfide is produced in the presence of 5-9 mols of water based on 1 mol of an alkali metal hydrosulfide. An aqueous solution of the alkali metal hydrosulfide is mixed with an aqueous solution of the alkali metal hydroxide by using equipment having a wetted part constituted of austenite ferrite-based stainless steel.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyarylene sulfide, and more specifically, a method for producing a polyarylene sulfide having high whiteness, which can suppress corrosion of a reactor surface during a dehydration step. It is about the method.

Polyarylene sulfide has been attracting attention as a member for electric / electronic parts and a member for automobile equipment by taking advantage of its excellent heat resistance and chemical resistance. Also injection molding,
It can be molded into various molded parts, films, sheets, fibers, etc. by extrusion molding and is widely used in fields requiring heat resistance and chemical resistance.

[0003]

As a typical method for producing polyarylene sulfide, a method of reacting a dihalogenated aromatic compound with an alkali metal sulfide such as sodium sulfide in an aprotic organic solvent such as N-methylpyrrolidone is known. It is disclosed in Japanese Patent Publication No. 45-3368.

That is, this is a method in which an alkali metal sulfide having water of hydration is heated and dehydrated prior to the polymerization to react with a dihalogenated aromatic compound to obtain a polymer. According to this method, the alkali metal sulfide, which is highly corrosive, is kept at a high temperature in the dehydration process, so that the alkali metal sulfide reacts with the material of the reactor to form metal sulfide (iron sulfide, nickel sulfide, etc.). To do. Since this by-product metal sulfide is insoluble in the solvent, it remains in the polymer. As a result, it is known that the thermal stability, electrical characteristics and whiteness of the polymer are deteriorated.

In order to solve the above problems, it is disclosed that it is preferable to use a titanium material having excellent corrosion resistance.
For example, Japanese Patent Application Laid-Open No. 61-23627 describes that a titanium material is used in the liquid contact part in the dehydration step.

Further, in JP-A-62-143932, an alkali metal sulfide, water and an organic solvent are used in a ratio of 1:10.
A method of suppressing corrosion and reducing the iron content by reacting with p-dichlorobenzene after mixing, heating and dehydrating in a ratio of -20: 1 to 10 (molar ratio) is described.

Further, JP-A-1-213338, JP-A-5-178994, and JP-A-9-278888 disclose iron-chromium ferritic stainless steel, a high-purity chromium material, and a nickel-containing ferrite material each having a specific composition. An apparatus for producing a polyarylene sulfide composed of a phase stainless steel or an austenitic stainless steel, and a method for producing a polyarylene sulfide using the same are described.

[0008]

However, JP-A-61-161
Since the titanium material described in Japanese Patent No. 23627 is more expensive than stainless steel or the like, the production cost is high. Also,
In the method described in JP-A-62-143932, dehydration requires a long time, so that productivity is lowered and the obtained polyarylene sulfide still has iron content of several tens pp.
m, and the color tone has not reached a satisfactory level. In addition, Japanese Patent Laid-Open Nos. 1-213338 and 5-1993
Although the manufacturing apparatus described in Japanese Patent No. 178994 has excellent corrosion resistance, it has poor workability and it is very difficult to obtain the material itself. Further, the production apparatus described in JP-A-9-278888 also shows excellent corrosion resistance, but only the test results in a specific polymerization system using lithium hydroxide and hydrogen sulfide as raw materials are described, and the usual polymerization method is used. It is a serious question whether or not it has corrosion resistance.

The present invention has been made in view of the above problems, and relates to a method for producing a polyarylene sulfide having high whiteness, which can suppress the corrosion of the reactor surface during the dehydration step.

[0010]

That is, the present invention provides a method for producing polyarylene sulfide in an aprotic organic solvent, which is characterized in that the production is carried out by the following steps 1 and 2. Method. Step 1: Using a manufacturing apparatus in which the wetted part is composed of austenite-ferritic stainless steel having a chromium content of 20 to 30% by weight and a nickel content of 0.1 to 10% by weight, an alkali metal hydrosulfide is used. When mixing the aqueous solution and the aqueous alkali metal hydroxide solution, 5 to 9 mol of water is present per 1 mol of the charged alkali metal hydrosulfide, and then dehydration is performed while heating Step 2: In the reaction system The present invention relates to a step of producing a polyarylene sulfide by reacting with a dihalogenated aromatic compound in a state where water is 0.5 to 2.0 mol per mol of a charged alkali metal hydrosulfide, and Details will be described.

Examples of the alkali metal hydrosulfide used in the present invention include lithium hydrosulfide, sodium hydrosulfide, potassium hydrosulfide, rubidium hydrosulfide, and cesium hydrosulfide. Among these, sodium hydrosulfide is preferable from the viewpoint of cost and availability. These may be used alone or in combination of two or more.

Examples of the alkali metal hydroxide used in the present invention include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide. Among them, sodium hydroxide is preferable from the viewpoints of cost and availability. These may be used alone or in combination of two or more.

The water referred to in the present invention includes water contained in the alkali metal hydrosulfide aqueous solution and the alkali metal hydroxide aqueous solution and water produced by the reaction between the alkali metal hydrosulfide and the alkali metal hydroxide. , Means the total amount of water present in the system. Since the reaction between the two proceeds instantaneously, it can be calculated by assuming that the by-produced water is generated quantitatively. As the amount of water in step 1 of the present invention,
It is essential that water is present in the system in a range of 5 to 9 mol per mol of alkali metal hydrosulfide, and above all, it is set to 5.5 to 7.5 mol per mol of alkali metal hydrosulfide. preferable. If the amount of water in the system is less than 5 mol per mol of alkali metal hydrosulfide, the material of the reactor is significantly corroded and the color tone of the produced polymer is adversely affected. Further, if the amount of water in the system exceeds 9 mol per mol of alkali metal hydrosulfide, it takes a long time for dehydration,
This is not preferable because it causes a decrease in productivity and increases the amount of energy used during dehydration.

The aprotic organic solvent used in the present invention is
Organic polar solvents that are stable at high temperatures are preferred. For example, N, N
-Dimethylacetamide, N-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone, hexamethylphosphoramide, tetramethylurea, 1,3-dimethyl-2-
Examples thereof include amides such as imidazolidinone, sulfolanes such as sulfolane and dimethylsulfolane, sulfoxides such as tetramethylene sulfoxide, methylphenyl ketones, etherified polyethylene glycols such as polyethylene glycol dialkyl ethers, and mixtures thereof. Of these, N-methyl-2-pyrrolidone is preferable because it is chemically stable and easily available.

The amount of the aprotic organic solvent used in the present invention is not particularly limited, but is 1 to 5 mol, preferably 1.5 to 3 mol, and particularly 2 to 1 mol per mol of the alkali metal hydrosulfide.
2.5 mol is preferred. If the amount of the aprotic organic solvent used is less than 1 mol per 1 mol of the alkali metal hydrosulfide, the corrosion of the reactor is significantly unfavorable. Further, if the amount of the aprotic organic solvent used exceeds 5 mol per 1 mol of the alkali metal hydrosulfide, it takes a long time to raise the temperature during dehydration, which is not preferable from an economical point of view.

The heat dehydration in the present invention is usually 190 to
This is a step of distilling excess water by heating to 220 ° C., and is performed under normal pressure or reduced pressure. If the ultimate dehydration temperature exceeds 220 ° C., the material of the reactor will be significantly corroded, which is not preferable.

In the production apparatus used in the present invention, the wetted part is composed of austenite-ferritic stainless steel containing 20 to 30% by weight of chromium and 0.1 to 10% by weight of nickel as essential components. It has a feature. Among them, chromium content is 22-27% by weight, nickel content is 2-
It is preferably made of austenitic-ferritic stainless steel composed of 8% by weight. Further, as an optional component, other elements such as silicon, titanium, manganese,
It may also contain molybdenum, copper or the like. As an example of such an alloy, for example, JIS standard SUS329J
1, SUS329J2L, SUS329J4L, etc., but among them, SUS329J1, SUS329J
4L is preferable, and SUS329J1 is particularly preferable.

A slurry obtained by mixing an alkali metal hydrosulfide and an alkali metal hydroxide in an aprotic organic solvent, heating and dehydrating the mixture is mixed with a dihalogenated aromatic compound and 18
A polyarylene sulfide can be synthesized by reacting at 0 to 280 ° C. The dihalogenated aromatic compound used in the present invention is a dihalogenated aromatic compound in which two halogen atoms are directly bonded to an aromatic nucleus, and examples thereof include p-dichlorobenzene, o-dichlorobenzene and m-dichlorobenzene.
Dichlorobenzene, p-dibromobenzene, o-dibromobenzene, m-dibromobenzene, p-diiodobenzene, o-diiodobenzene, m-diiodobenzene,
Dichloronaphthalene, dibromonaphthalene, diiodonaphthalene, dichlorobiphenyl, dibromobiphenyl,
Examples thereof include diiodobiphenyl, dichlorodiphenyl sulfone, dibromodiphenyl sulfone, diiododiphenyl sulfone, dichlorobenzophenone, dibromobenzophenone, diiodobenzophenone, dichlorodiphenyl ether, dibromodiphenyl ether, diiododiphenyl ether, and mixtures thereof. Among them, p-dichlorobenzene is preferable from the viewpoint of easy availability and heat resistance of the resulting polyarylene sulfide. The dihalogenated aromatic compounds may be used in combination of two or more kinds. Further, the polyarylene sulfide according to the present invention is a polymer of the above dihalogenated aromatic compound, but trichlorobenzene, tribromobenzene, triiodobenzene, tetrachlorobenzene, tetrabromobenzene, tetraiodobenzene for adjusting the molecular weight. It is also possible to use a small amount of polyhalogenated aromatic compound together. The amount of the dihalogenated aromatic compound used is usually in the range of 0.90 to 1.1 mol per mol of the alkali metal hydrosulfide.

Further, in the present invention, it is possible to add a polymerization aid or a phase separation agent for helping to increase the molecular weight of the polymer. The polymerization aid is not particularly limited as long as it is a salt soluble in an aprotic organic solvent, and examples thereof include alkali metal carboxylates such as sodium acetate and sodium benzoate, lithium chloride and the like. The phase separating agent is not particularly limited as long as it can be a poor solvent for polyarylene sulfide, and examples thereof include water and isooctane.

The post-treatment of the slurry after polymerization can be carried out by a conventional method. For example, the polyarylene sulfide can be obtained by cooling the product slurry obtained after the completion of the polymerization as it is, or by diluting it with water or an organic solvent, filtering and repeating washing with water and drying. The product slurry may be filtered while still hot. Moreover, you may wash | clean with the same organic solvent as a polymerization solvent, another organic solvent, and / or high temperature water. Furthermore, it is also possible to treat the polyarylene sulfide with an acid.

The polyarylene sulfide obtained according to the present invention may be heat-treated or untreated, and may be used alone or as a reinforcing filler for glass fibers, known inorganic fillers such as mica, talc and silica, pigments, flame retardants, It can be molded into various molded products, films, sheets, pulps, fibers and the like by injection molding, extrusion molding and the like by blending with stabilizers and other polymers.

[0022]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 SUS329J1 (manufactured by NOF CORPORATION, 25% Cr)
-5% Ni-1.5% Mo) test piece: 35 x 1
5 × 3 mm (length × width × thickness) was suspended in a 3 L separable flask equipped with a stirring blade, and a dehydration reaction was performed under the following conditions.

N-methyl-2-pyrrolidone 915 g
(8.38 mol), 47% aqueous sodium hydrosulfide solution (477 g, 4.0 mol), 48% sodium hydroxide 3
33 g (4.0 mol) was added. The total amount of water in the system is 498 g, which is 252.8 g of water entrained with an aqueous solution of sodium hydrosulfide, 173.2 g of water entrained with an aqueous solution of sodium hydroxide, and 72 g of water that is a byproduct of the reaction progressing quantitatively. . This corresponds to 6.9 mol per mol of charged sodium hydrosulfide. Then, while stirring, 2
The temperature was raised to 05 ° C. At this time, 1.1% of N-methyl-
404 g of a distillate containing mainly 2-water containing 2-pyrrolidone was distilled off. After the completion of dehydration, the system was cooled and the reaction product was taken out. This operation was repeated 10 times, the test piece was taken out from the system, the corrosion rate was measured, and the surface microscope observation was performed. As a result, the corrosion rate is 0.006 mm / y
It was very small, retained the initial metallic luster, and had a good surface condition.

Examples 2 to 3 When the aqueous sodium hydrosulfide solution was added, water was added at 42% each.
Corrosion test was conducted under the same conditions as in Example 1 except that 100 g and 114 g were added. Corrosion rate is 0.005mm / y
It was very small, retained the initial metallic luster, and had a good surface condition.

Examples 4 to 5 SUS329J4L (manufactured by Sumikin Welding Industry Co., Ltd., 25% Cr-6
% Ni-3% Mo-1% Cu), SAF2507 (manufactured by Sandvik Co., 25% Cr-7% Ni-4% Mo-0.
A test piece of 3% N) was hung and the test was conducted under the same conditions as in Example 1. Corrosion rate is 0.020 mm /
y was as small as 0.006 mm / y, retained the initial metallic luster, and had a good surface condition.

Comparative Example 1 Instead of the 48% aqueous sodium hydroxide solution used in Example 1, 165 g (4.0%) of sodium hydroxide having a purity of 97% was used.
mol) was used, and a corrosion test was performed under the same conditions as in Example 1. The corrosion rate was as large as 0.61 mm / y, and severe general corrosion was also observed in the surface observation.

Comparative Examples 2 to 5 SUS304 (20% Cr-10% Ni-1% Mn austenitic stainless steel), SUS316 (18% Cr)
-11% Ni-2% Mo austenitic stainless steel), titanium (Ti), titanium-palladium alloy (Ti
A test piece (containing -0.15% Pd) was suspended and a corrosion test was performed under the same conditions as in Example 1. In all cases, the corrosion rate was 0.1 mm / y or more, and the surface gloss was lost.

Reference Example 1 A test piece of titanium (Ti) was suspended, and 520 g of 60% sodium sulfide was used instead of the 47% sodium hydrosulfide aqueous solution and the 48% sodium hydroxide aqueous solution used in Example 1.
A corrosion test was conducted under the same conditions as in Example 1 except that (4.0 mol) was used. The corrosion rate of Ti is 0.016 mm /
It was as small as y and kept a good surface condition. From this result, it is clear that the corrosion resistance of the wetted part alloy differs depending on the raw material system and the amount of water.

Example 6 In a 0.5 L autoclave having an inner cylinder made of SUS329J1, 59.6 g of 47% sodium hydrosulfide aqueous solution (0.
50 mol), 48% aqueous sodium hydroxide solution 40.8
g (0.49 mol) and 114 g (1.15 mol) of N-methyl-2-pyrrolidone (NMP) were added. The amount of water in the system was 31.
6 g, 21.2 g of water entrained in the aqueous sodium hydroxide solution, and 9 g of water that is a by-product of the reaction progressing quantitatively
The total is 61.8 g, and the charged sodium hydrosulfide is 1
This corresponds to 6.87 mol per mol. Then, the system was heated to 200 ° C. and dehydrated, whereby 51 g of a distillate mainly containing water containing 1% NMP was distilled off.
Then, it was cooled to 150 ° C. and p-dichlorobenzene 7
3.5 g (0.5 mol) was added together with 63.6 g of NMP, the system was sealed under a nitrogen stream, the temperature was raised to 2 at 225 ° C.
Polymerization was carried out for 3 hours at 250 ° C. After the polymerization was completed, the system was cooled, the obtained slurry was filtered, and the solid content was repeatedly washed with hot water at 80 ° C. to remove the by-product NaCl. Then, the obtained cake was dried at 100 ° C. for 12 hours to obtain a polymer. When the whiteness of the polymer was measured using a color meter (SM-4 manufactured by Suga Test Instruments Co., Ltd.), the whiteness was 75.

Examples 7 to 8 When the aqueous sodium hydrosulfide solution was added, water was added to each of 5.3.
g and 14.3 g were added, and polymerization and post-treatment were carried out under the same conditions as in Example 1. The whiteness of all the obtained polymers was 78.

Comparative Example 6 Instead of the 48% aqueous sodium hydroxide solution used in Example 6, 20.6 g (0.
Polymerization under the same conditions as in Example 6, except that 5 mol) was used,
Post-treatment was performed. The whiteness of the obtained polymer was 64.

Comparative Examples 7 to 8 Polymerization and post-treatment were carried out under the same conditions as in Example 6 except that an autoclave having an inner cylinder made of titanium and an inner cylinder made of SUS316 was used. The whiteness of the obtained polymer was 65 and 54, respectively.

The corrosion test and polymerization results are summarized in Tables 1 and 2. From these results, it is clear that according to the method of the present invention, the corrosion of the reactor is suppressed and a polymer having high whiteness can be obtained.

[0035]

[Table 1]

[Table 2]

As is apparent from the above description, according to the present invention, it is possible to suppress the corrosion of the reactor surface during the dehydration step and to produce a polyarylene sulfide having a high whiteness.

Claims (2)

[Claims] 1. A method for producing a polyarylene sulfide in an aprotic organic solvent, characterized in that the production is carried out by the following steps 1 and 2. Step 1: Using a manufacturing apparatus in which the wetted part is composed of austenite-ferritic stainless steel having a chromium content of 20 to 30% by weight and a nickel content of 0.1 to 10% by weight, an alkali metal hydrosulfide is used. When mixing the aqueous solution and the aqueous alkali metal hydroxide solution, 5 to 9 mol of water is present per 1 mol of the charged alkali metal hydrosulfide, and then dehydration is performed while heating Step 2: In the reaction system A step of producing a polyarylene sulfide by reacting with a dihalogenated aromatic compound in a state where water becomes 0.5 to 2.0 mol per mol of a charged alkali metal hydrosulfide. 2. The material of the manufacturing apparatus according to claim 1 is JI
A method for producing a polyarylene sulfide, which is S standard SUS329J1 or SUS329J4L.