JP3153657B2 - Method for producing polyphenylene sulfide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polyphenylene sulfide (hereinafter abbreviated as PPS), and more particularly, to a method for producing high molecular weight and granular PPS in high yield.

[0002]

2. Description of the Related Art PPS has heat resistance, chemical resistance, flame retardancy,
It is an engineering plastic with excellent mechanical strength, electrical properties, dimensional stability, etc.It can be formed into various molded products, films, sheets, fibers, etc. by extrusion molding, injection molding, compression molding, etc. It is widely used in a wide range of fields such as electronic devices and automobile devices. PP
As a method for producing S, Japanese Patent Publication No. 45-3368 discloses N
In an organic amide solvent such as -methyl-2-pyrrolidone,
A method of reacting an alkali metal sulfide such as sodium sulfide with a dihalo aromatic compound such as p-dichlorobenzene has been proposed. However, according to the method disclosed in the publication, only PPS having a low molecular weight and a low melt viscosity can be obtained. A method of heating such a low-molecular-weight PPS in the presence of air after polymerization to partially cross-link (cure) it to have a high molecular weight is known.
The mechanical properties are insufficient, and it is difficult to form into a sheet, film, fiber or the like.

[0003] Therefore, conventionally, high-molecular-weight PPS was used during polymerization.
In order to obtain PPS, various PPS manufacturing methods improved from the above method have been proposed. As a means for improving the polymerization method of PPS, there is known a method of adding various polymerization aids when reacting an alkali metal sulfide with a dihalo aromatic compound in an organic amide solvent. For example, as a polymerization aid, an alkali metal carboxylate (Japanese Patent Publication No. 52-12240)
No.), alkaline earth metals of aromatic carboxylic acids (JP-A-5
9-219332), alkali metal halides (U.S. Pat. No. 4,038,263), and sodium salts of aliphatic carboxylic acids (JP-A-1-161022). According to these methods, linear and high-molecular-weight PPS can be obtained, but a relatively large amount of a polymerization aid must be added. That is, the patent document discloses a very wide range of addition amount of the polymerization aid from a small amount to a large amount. However, in order to obtain a sufficiently high molecular weight PPS, a relatively large amount of the polymerization aid is used. Need to be added. Furthermore, in order to obtain a higher molecular weight PPS, it is necessary to use a large amount of expensive lithium acetate or sodium benzoate among the polymerization aids,
This leads to an increase in the production cost of PPS.

On the other hand, Japanese Patent Publication No. 33775/1988 discloses a method in which an alkali metal sulfide is reacted with a dihaloaromatic compound in an organic amide solvent to obtain PPS. 1) in the presence of 0.5 to 2.4 moles of water per mole of alkali metal sulfide;
After reacting at 80 to 235 ° C. to a conversion of 50 to 98 mol%, (2) 2.5 to 2.5 mol% per mol of alkali metal sulfide
A two-stage polymerization reaction has been proposed in which water is added so that 7.0 mol of water is present, and the temperature is raised to a temperature of 245 to 290 ° C. to continue the reaction. According to this method, high molecular weight and granular PPS can be obtained without adding a polymerization aid. However, in this method, depending on the polymerization conditions, a relatively large amount of finely divided polymer having a small particle size is generated together with the granular polymer, and as a result, the yield of the granular polymer is reduced, and the workability of post-treatment is also reduced. Sometimes. Therefore, an improved method for obtaining high molecular weight and granular PPS in high yield is strongly desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing high-molecular-weight and granular polyphenylene sulfide in high yield. The present inventors have conducted intensive studies and as a result, have found that the above-mentioned JP-B-63-3377.
According to the two-stage polymerization method of PPS disclosed in No. 5,
At least in a relatively large amount of coexisting water in the second step, a small amount of an alkali metal carboxylate is present, whereby high-molecular-weight and granular PPS can be obtained with a high yield. It has been found that body formation can be suppressed. The present invention has been completed based on these findings.

[0006]

Thus, according to the present invention, there is provided a method for producing polyphenylene sulfide by reacting an alkali metal sulfide with a dihalo aromatic compound in an organic amide solvent. Performed in two steps of step (1) and step (2), and at least in step (2), 0.001 to 0.20 mol of an alkali metal carboxylate per 1 mol of the charged alkali metal sulfide. A method for producing polyphenylene sulfide is provided.

(1) In an organic amide solvent containing 0.5 to 2.4 mol of water per mol of the charged alkali metal sulfide, the alkali metal sulfide and the dihalo-aromatic compound are mixed with one another.
Reacting at a temperature of 70 to 270 ° C. to obtain a conversion ratio of the dihalo aromatic compound of 50 to 98 mol% to form a polyphenylene sulfide prepolymer; and (2)
Water is added to the reaction system so that 2.5 to 10 mol of water is present per 1 mol of the charged alkali metal sulfide, and at a temperature of 245 to 290 ° C., 0.5 to 20
Continuing the reaction for a time to increase the conversion of the dihaloaromatic compound and converting the prepolymer into high molecular weight polyphenylene sulfide.

Hereinafter, the present invention will be described in detail. (Alkali metal sulfide) Preferred examples of the alkali metal sulfide used in the present invention include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide, and a mixture thereof. These alkali metal sulfides can be used as hydrates or aqueous mixtures or in anhydrous form. Further, an alkali metal sulfide prepared in situ in a reaction system from an alkali metal hydrosulfide and an alkali metal hydroxide can also be used.

(Dihalo Aromatic Compound) Examples of the dihalo aromatic compound used in the present invention include dihalobenzenes such as p-dichlorobenzene, m-dichlorobenzene and p-dibromobenzene, and 1-methoxy-2,5-dichlorobenzene. Aromatic compounds containing a substituent other than halogen, such as 3,5-dichlorobenzoic acid, are also used. Above all, p
Those having p-dihalobenzene represented by -dichlorobenzene as a main component are preferred. It is also possible to form a copolymer by combining two or more different dihaloaromatic compounds. In order to form a terminal of the produced polymer, or to use a monohalo compound (not necessarily an aromatic compound) in combination or to form a branched or cross-linked polymer for the purpose of controlling the polymerization reaction or the molecular weight. It is also possible to use a polyhalo compound (not necessarily an aromatic compound) of trihalo or higher.

(Polymerization Solvent) In the present invention, an organic amide solvent is used as a polymerization solvent. As the organic amide solvent, for example, N-methyl-2
Aprotic organic amide solvents represented by N-alkylpyrrolidone such as -pyrrolidone, 1,3-dialkyl-2-imidazolidinone, tetraalkylurea, hexaalkylphosphoric triamide , and the like; Is high, which is preferable. Among these, N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) is particularly preferred. The amount of the polymerization solvent used in the present invention is preferably in the range of 0.2 to 1 kg per mole of alkali metal sulfide.

(Alkali metal carboxylate) The alkali metal carboxylate used in the present invention has the general formula R (COOM)
_n (wherein R is an alkyl group having 1 to 20 carbon atoms,
Cycloalkyl group, aryl group, alkylaryl group,
Or an arylalkyl group. M is an alkali metal selected from lithium, sodium, potassium, rubidium, and cesium. n is an integer of 1 to 3. ). The alkali metal carboxylate can also be used as a hydrate or an aqueous solution. In this case, it is necessary to adjust the amount of coexisting water in the polymerization reaction system to be within a specified range. If the amount exceeds the specified amount, excess water must be removed by, for example, distillation.

Specific examples of the alkali metal carboxylate used in the present invention include, for example, lithium acetate, sodium acetate, potassium acetate, sodium propionate, lithium valerate, lithium benzoate, sodium benzoate,
Sodium phenylacetate, potassium p-toluate,
And mixtures thereof. Alkali metal carboxylate is prepared by adding an organic acid and one or more compounds selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal bicarbonates in an organic amide solvent in substantially equivalent stoichiometric amounts. It may be formed by adding each of them and reacting them. Among the alkali metal carboxylate salts, sodium acetate is particularly preferably used because it is inexpensive and easily available.

(Polymerization Reaction) In the present invention, in a method for producing polyphenylene sulfide by reacting an alkali metal sulfide with a dihalo aromatic compound in an organic amide solvent, the reaction is carried out in at least the above two-step process. An auxiliary step may be added before, after, or in the middle of these steps.

First Step (1) In the first step (1), that is, in the first step polymerization, an organic amide solvent containing 0.5 to 2.4 mol of water per mol of the charged alkali metal sulfide is used. , An alkali metal sulfide and a dihalo aromatic compound at 170 to 270 ° C,
The reaction is carried out at a temperature of from 80 to 235 ° C. to give a conversion of the dihalo-aromatic compound of from 50 to 98 mol% and to produce a polyphenylene sulfide prepolymer.

When starting the step (1), first, an alkali metal sulfide and a dihalo aromatic compound are added to an organic amide solvent at a temperature in a range of room temperature to 250 ° C., preferably in an inert gas atmosphere. The alkali metal sulfide is usually used in the form of a hydrate. When the content of water is less than 0.5 mol per mol of the charged alkali metal sulfide, the necessary amount is added and supplemented. When the water content of the alkali metal sulfide is too large, the mixture containing the organic amide solvent and the alkali metal sulfide is heated from 150 ° C. to about 210 ° C. under normal pressure before adding the dihaloaromatic compound. To remove excess water out of the system. If too much water is removed, add the shortage.

The coexisting water amount of the reaction system in the step (1) is as follows:
0.5 to 2.4 per mole of charged alkali metal sulfide
Mol, preferably in the range of 1.0 to 2.0 mol. If the amount of coexisting water is less than 0.5 mol, undesired reactions such as decomposition of the produced PPS are likely to occur. Conversely, if it exceeds 2.4 mol, the polymerization rate becomes extremely low, or the decomposition of the organic amide solvent or the produced PPS is decomposed. Are more likely to occur, and neither is preferable.

The first-stage polymerization is carried out at a temperature of 170 to 270 ° C., preferably 180 to 235 ° C. Within this temperature range, the temperature may be changed continuously or stepwise. If the temperature is too low, the polymerization rate becomes too slow, and if it exceeds 270 ° C., the generated PPS and the organic amide solvent are liable to decompose, and the degree of polymerization of the generated PPS becomes extremely low. In particular, when the alkali metal carboxylate is not contained during the first-stage polymerization, the temperature is preferably not higher than 235 ° C.

Amount of dihalo aromatic compound used (amount charged)
Is 0.9 to 0.9 mol per mol of the charged alkali metal sulfide.
2.0 moles, preferably in the range of 0.95 to 1.50 moles, is preferred for obtaining high molecular weight PPS. If it is less than 0.9 mol or more than 2.0 mol, it is not preferable because it is difficult to obtain high-viscosity PPS suitable for processing.

The time of switching from the first-stage polymerization, which is the end point of the first-stage polymerization, to the second-stage process (2), that is, the second-stage polymerization, is when the conversion of the dihaloaromatic compound in the system reaches 50 to 98 mol%. is there. If the conversion is less than 50 mol%, undesired reactions such as decomposition occur during the second-stage polymerization. Conversely, if the conversion exceeds 98 mol%, it is difficult to obtain PPS having a high degree of polymerization even after the second-stage polymerization. A conversion rate of about 85 to 95 mol% is preferable because PPS having a high degree of polymerization can be stably obtained.

Here, the conversion of the dihalo aromatic compound is calculated by the following equation. (A) When a dihalo aromatic compound (abbreviated as DHA) is added in excess of an alkali metal sulfide in a molar ratio. (B) In cases other than (a) above In the step (1), a relatively low molecular weight PPS having a melt viscosity (measured at 310 ° C. and a shear rate of 200 / sec) of about 5 to 300 poise is usually obtained. Therefore, the PPS obtained at this stage is called a prepolymer.

Second Step (2) In the second step (2), that is, in the second stage polymerization, the reaction system is adjusted so that 2.5 to 10 mol of water is present per 1 mol of the charged alkali metal sulfide. Water and add 2
The reaction is continued at a temperature of 45 to 290 ° C. for 0.5 to 20 hours to increase the conversion of the dihalo aromatic compound and to convert the prepolymer into a high molecular weight polyphenylene sulfide. In the present invention, at least during the subsequent polymerization,
In the reaction system, the alkali metal carboxylate is charged and is present in a very small amount of 0.001 to 0.20 mole per mole of the alkali metal sulfide.

In step (2), if the amount of coexisting water in the reaction system is less than 2.5 mol or exceeds 10 mol, the produced P
The degree of polymerization of PS decreases. In particular, the amount of coexisting water is 3.5 to
When the post-stage polymerization is performed in the range of 7.0 mol, a high polymerization degree of PP is obtained.
It is preferable because S is easily obtained. If the polymerization temperature in step (2) is lower than 245 ° C., only a low polymerization degree PPS can be obtained. On the other hand, when the temperature exceeds 290 ° C., there is a possibility that the produced PPS and the organic amide solvent are decomposed. In particular, 250-270
The range of ° C. is preferable because PPS having a high degree of polymerization is easily obtained. The post-polymerization step in the present invention is not a mere separation / granulation step of PPS produced in the pre-polymerization, but a pre-PP
This is for causing S (prepolymer) to increase the degree of polymerization.

The polymerization time of the step (2) is 0.5 to 20 hours, preferably 1 to 15 hours, more preferably 3 to 10 hours.
Time. If the polymerization time in the second-stage polymerization is too short, only PPS with a low degree of polymerization can be obtained.
Decomposition of S and the organic amide solvent is likely to occur. Switching from the first-stage polymerization to the second-stage polymerization may be performed under the second-stage polymerization conditions by transferring the slurry obtained in the first-stage polymerization to another reaction vessel, or the first-stage polymerization and the second-stage polymerization may be performed in the same reaction vessel. It may be carried out by changing the polymerization conditions. The time for adding water may be after the first-stage polymerization, and may be immediately before the reaction system is brought to the temperature of the second-stage polymerization, or may be after the temperature of the second-stage polymerization is reached. Is desired.

By the polymerization reaction in such a two-step process, a high molecular weight PPS having a melt viscosity of 10 poise or more, more preferably 1000 poise or more (measured at 310 ° C. at a shear rate of 200 / sec) can also be obtained. The PPS has an intrinsic viscosity of usually 0.10 or more, preferably 0.15 or more, more preferably 0.20 or more [η _inh :
1-chloronaphthalene solution (concentration: 0.4 g / 100 m
1) Measured at 208 ° C.).

(Alkali metal carboxylate) The alkali metal carboxylate used in the present invention or a compound for producing the same in the reaction system may be contained in at least the reaction system in the second step. Therefore,
The timing of the addition may be before the dehydration step before the start of the first-stage polymerization, at the start of the first-stage polymerization, at the start of the second-stage polymerization, or any combination thereof. When the alkali metal carboxylate is added at the start of the second-stage polymerization, the reaction system can be charged together with additional water. In the present invention, the alkali metal carboxylate is used in an amount of 0.001 to 0.2 mol, preferably 0.01 to 0.2 mol per mol of the charged alkali metal sulfide.
It is used in a limited range of 0.15 mol, more preferably 0.03 to 0.13 mol.

According to the method of the present invention, the yield of granular PPS can be improved. For the product obtained by the method of the present invention, the polymer (100 mesh on) collected by a screen having an opening diameter of 150 μm (100 mesh) is passed through a granular PPS, 100 mesh, and the opening diameter is 38 μm. A polymer (100 mesh pass & 390 mesh on) collected by a (390 mesh) screen is precipitated by adding a large amount of water in a fine powder component (390 mesh pass) passing through a 390 mesh screen. Alternatively, what is obtained by acid precipitation is called an ultrafine powder and will be described.

In the PPS polymerization method according to the two-step process of the present invention, the use of the alkali metal carboxylate in the above range improves the yield of particulate PPS. However, when the amount of the alkali metal carboxylate added is increased, the amount of the generated ultrafine powder tends to increase. That is, when the alkali metal carboxylate is increased within the above range,
Although the yield of granular PPS increases and the amount of fine powder produced decreases, the amount of ultrafine powder produced increases, so the yield of granular PPS by the addition of alkali metal carboxylate is limited. . In other words, in the two-stage polymerization method, when the alkali metal carboxylate is added to improve the yield of the granular PPS, the amount of the alkali metal carboxylate has an optimum range. Add the alkali metal carboxylate,
Further, it is also possible to increase the average particle diameter by increasing the stirring speed of the reaction system. However, in this case, too, the granular PP obtained by adding an alkali metal carboxylate is used.
There is a limit to the effect of improving the yield of S.

When the amount of the alkali metal carboxylate added is 0.
If the amount is less than 001 mol, the effect of improving the yield of granular PPS is small, while if it exceeds 0.20 mol, the amount of generated ultrafine powder increases, and no improvement in the yield of the granular polymer can be obtained. In order to improve the yield of the granular PPS and to suppress the production amount of the ultrafine powder, it is necessary to use 0.03 to 0.13 mol of the alkali metal carboxylate per 1 mol of the charged alkali metal sulfide. Is preferred. 0.2 mol of alkali metal carboxylate per mol of charged alkali metal sulfide
Even if it is added in excess of 0 mol, the effect of improving the yield of granular PPS is limited, and problems such as purification of the produced polymer and cost increase due to the use of a polymerization aid are caused. Further, according to the method of the present invention, it is possible to obtain a granular PPS having a small degree of dispersion of the particle size distribution, so that the handling property, the molding workability, and the like are further improved.

(Post-treatment) The post-treatment in the polymerization method of the present invention can be carried out by a conventional method. That is, after the end of the second-stage polymerization reaction, PPS can be obtained by filtering the cooled product slurry as it is or by diluting it with water or the like, repeating washing with water and drying, and then drying.

(Produced PPS) According to the method of the present invention, a granular PPS having an average particle size of 150 to 3000 μm and which can be easily handled and molded can be obtained in good yield. Since the PPS obtained by the method of the present invention has a linear high molecular weight, it can be molded not only by injection molding but also into extruded products such as sheets, films, fibers, and pipes. Although the PPS obtained by the method of the present invention can be used alone,
If desired, various inorganic fillers, fibrous fillers, various synthetic resins and the like may be blended and used.

[0031]

The present invention will be more specifically described below with reference to examples and comparative examples. The method for measuring physical properties is
It is as follows.

<Yield of granular polymer> The product after completion of the polymerization reaction was sieved and screened through screens having different openings as follows. Aperture diameter 150μm (100 mesh)
What was collected on the screen of the
After passing through 100 mesh, the aperture diameter was 38 μm (39
(0 mesh) is collected as fine powder.
And The yields of the granular polymer and the fine powder were based on the weight (theoretical amount) assuming that all the Na ₂ S in the autoclave after the dehydration step was converted to PPS. In addition, 100%
Most of the loss obtained by subtracting the sum of the yields of the granular polymer and the fine powder from the above is the ultrafine powder that has passed through 390 mesh.

<Intrinsic viscosity> Intrinsic viscosity (η _inh ) of PPS
Was measured at 208 ° C. using a solution of PPS dissolved in 1-chloronaphthalene (concentration: 0.4 g / 100 ml).

<Average Particle Size and Particle Size Distribution> The average particle size and particle size distribution of PPS are as defined in JIS K-0069 (19).
66), according to the dry method specified in JIS Z-8.
801 (1982). Eight different screen openings (7 mesh (2800 μm), 16 mesh (1000 μm
m), 24 mesh (710 μm), 32 mesh (5
00 μm), 60 mesh (250 μm), 100 mesh (150 μm), 150 mesh (106 μm),
200 mesh (75 μm)] are stacked on a tray in order from the one with the smallest opening to the one with the largest opening, and the polymer sample 5 is placed on the top 7-mesh sieve.
A mixture of 0.0 g and 0.3 g of carbon black for preventing static electricity was added.

Using an electromagnetic sieve shaker model A-3 (manufactured by Flicce, Germany), the screen is vibrated at 3000 times / minute, vibration 2 seconds / interruption 0.5 seconds, for 15 minutes, and then each screen is released. The sample remaining on each sieve was weighed to determine the weight percentage. Next, a particle size distribution curve was created on logarithmic normal probability paper, and the particle size at a cumulative 50% by weight was defined as the average particle size. In addition, in the particle size distribution curve, points of 5% by weight and 95% by weight are connected by a straight line, and the slope is read in accordance with the degree of dispersion log ₁₀ σ marked on the logarithmic probability paper for calculating the specific surface area of the powder. The degree of dispersion was used. σ is the geometric standard deviation.

COMPARATIVE EXAMPLE 1 N-methyl-2-pyrrolidone (NMP) was added to a 20-liter autoclave at 670.
0 g and 46.24% by weight of sodium sulfide (Na
3800 g of sodium sulfide pentahydrate crystals containing ₂ S)
After charging and purging with nitrogen gas, the temperature was gradually raised to 200 ° C. while stirring for about 4 hours, and 1503 g of water, NM
1281 g of P and 0.52 mol of H ₂ S were distilled off. The effective sodium sulfide in the can is 21.99 mol.

After the above-mentioned dehydration step, it is cooled to 150 ° C.
p-Dichlorobenzene (hereinafter abbreviated as p-DCB) 33
95 g (1.05 mol / 1 mol sodium sulfide) and N
2828 g of MP and 73 g of water were added (the total amount of water in the can was 1.5 mol / sodium sulfide 1 mol), and the mixture was reacted at 220 ° C. for 4.5 hours while stirring at a rotation speed of a stirrer of 300 rpm to perform pre-stage polymerization. After the completion of the first-stage polymerization, a small amount of the slurry is sampled, the remaining p-DCB amount is determined by a gas chromatograph method, and the above conversion (a) is calculated.
The conversion was determined to be 94.7%.

Next, the rotation speed of the stirrer was increased to 350 rpm, and 448 g of water was injected while stirring was continued (total water in the can was 2.6 mol / mol of sodium sulfide).
And the reaction was carried out for 5 hours to carry out post-stage polymerization. At the end of the second-stage polymerization, the conversion of p-DCB was 100%. After completion of the second-stage polymerization, the content was cooled to around room temperature, and the content was passed through a 100-mesh screen to screen out a granular polymer, and washed three times with acetone and seven times with water. The granular polymer was dried at 100 ° C. overnight. The granular polymer thus obtained has an average particle size of 390 μm and a dispersity of 0.
26, yield 79%, intrinsic viscosity 0.23. Also,
The yield of fine powder collected by a 390-mesh screen in the 100-mesh passing component was 12%.

[Example 1] The same formulation as in Comparative Example 1 was carried out, and the mixture was subjected to a dehydration step.
370 g and 0.52 mol of H ₂ S distilled out. The effective sodium sulfide in the can is 21.99 mol. Further, in the same manner as in Comparative Example 1, 3395 g of p-DCB
(1.05 mol / 1 mol sodium sulfide), NMP29
17 g and 129 g of water were added (total water volume in the can was 1.
5 mol / sodium sulfide 1 mol), and the former-stage polymerization was carried out.
The conversion of p-DCB at the end of the first-stage polymerization was 94.9%.

Next, a mixture of 183 g (0.1 mol / mol of sodium sulfide) of anhydrous sodium acetate (purity: 98.5%) and 448 g of water was injected while stirring continuously (total water volume in the can). Is 2.6 mol / sodium sulfide 1 mol), and post-stage polymerization was carried out. P-DCB at the end of second-stage polymerization
Was 100%. The product was treated in the same manner as in Comparative Example 1, and had an average particle size of 380 μm, a dispersity of 0.15,
A granular polymer having an intrinsic viscosity of 0.23 was obtained in a yield of 90%.
The yield of the fine powder was 3.3%.

[Comparative Example 2] The same preparation as in Comparative Example 1 was carried out, and the mixture was subjected to a dehydration step.
275 g and 0.54 mol of H ₂ S distilled out. The effective sodium sulfide in the can is 21.98 mol. Next, 3360 g of p-DCB was prepared in the same manner as in Comparative Example 1.
(1.04 mol / 1 mol sodium sulfide), NMP28
18 g and water 82 g (total water in the can is 1.5
Mol / mol of sodium sulfide), and pre-stage polymerization was carried out. The conversion of p-DCB at the end of the first-stage polymerization was 94.5%.

Next, 448 g of water was injected while stirring was continued (total water content in the can was 2.7 mol / sodium sulfide 1).
Mol), and post-stage polymerization was performed. P-DC at the end of the second-stage polymerization
The conversion of B was 99.8%. The product was treated in the same manner as in Comparative Example 1, and had an average particle size of 510 μm and a dispersity of 0.2.
7. A granular polymer having an intrinsic viscosity of 0.25 was obtained in a yield of 78%. The yield of the fine powder was 13%.

Example 2 A mixture was charged and dewatered in the same manner as in Comparative Example 1, and 1555 g of water and NMP1
318 g and 0.55 mol of H ₂ S were distilled off. The effective sodium sulfide in the can is 21.97 mol. Further, in the same manner as in Comparative Example 2, 3359 g of p-DCB
(1.04 mol / 1 mol sodium sulfide), NMP28
57 g and 126 g of water are added (total water content in the can is 1.
5 mol / sodium sulfide 1 mol), and the former-stage polymerization was carried out.
The conversion of p-DCB at the end of the first-stage polymerization was 94.3%.

Next, anhydrous sodium acetate (purity 98.
5%) 91 g (0.05 mol / sodium sulfide) and water 4
A mixture of 47 g was injected under pressure (total water in the can was 2.
(6 mol / 1 mol of sodium sulfide), and post-stage polymerization was carried out.
The conversion of p-DCB at the end of the second-stage polymerization was 99.8%. The product was treated in the same manner as in Comparative Example 1 to obtain a granular polymer having an average particle size of 390 μm, a dispersity of 0.19, and an intrinsic viscosity of 0.25 in a yield of 87%. The yield of fine powder is 7.
3%.

[Example 3] The same prescription as in Comparative example 1 was used, and the dehydration step was performed under almost the same conditions.
8 g, 1298 g of NMP, and 0.53 mol of H ₂ S were distilled off. The effective sodium sulfide in the can is 21.99 mol. Further, in the same manner as in Comparative Example 2, p-DCB
3361 g (1.04 mol / 1 mol sodium sulfide),
2842 g of NMP and 99 g of water were added (total water content in the can was 1.5 mol / mol of sodium sulfide), and pre-stage polymerization was performed. The conversion of p-DCB at the end of the first-stage polymerization was 9
It was 4.4%.

Next, anhydrous sodium acetate (purity 98.
5%) 183 g (0.1 mol / mol of sodium sulfide)
And a mixed solution consisting of water and 447 g of water were injected under pressure (total water in the can was 2.6 mol / mol of sodium sulfide), and post-stage polymerization was carried out. The conversion of p-DCB at the end of the second-stage polymerization was 99.
8%. The product was treated in the same manner as in Comparative Example 1, and had an average particle size of 460 μm, a dispersity of 0.16, and an intrinsic viscosity of 0.26.
Was obtained in a yield of 90%. The yield of fine powder is
3.3%.

Example 4 In a 20-liter autoclave, 6700 g of NMP and 46.24% by weight of Na were added.
3800 g of sodium sulfide pentahydrate crystals containing ₂ S,
And 187 g of anhydrous sodium acetate (purity 98.5%)
(0.1 mol / 1 mol of sodium sulfide), and after replacing with nitrogen gas, the mixture was gradually stirred for 20 hours with stirring for 20 hours.
The temperature was raised to 0 ° C., 1470 g of water, 1398 g of NMP,
And 0.54 mol of H ₂ S were distilled off. The effective sodium sulfide in the can is 21.96 moles. After the dehydration step, in the same manner as in Comparative Example 2, p-DCB3360 g
(1.04 mol / 1 mol sodium sulfide), NMP29
39 g and water 40 g were added (total water amount in the can was 1.5
Mol / mol of sodium sulfide).
The reaction was carried out at 20 ° C. for 4.5 hours to perform the first-stage polymerization. p
-The conversion of DCB was 95.1%.

Then, 447 g of water was injected while stirring was continued (total amount of water in the can was 2.6 mol / mol of sodium sulfide), the temperature was raised to 255 ° C., and post-stage polymerization was performed for 5 hours. The conversion of p-DCB at the end of the second-stage polymerization was 99.8.
%Met. The product was treated in the same manner as in Comparative Example 1 to obtain a granular polymer having an average particle size of 510 μm, a dispersity of 0.16, and an intrinsic viscosity of 0.25 in a yield of 90%. The yield of fine powder is
It was 4.0%.

[Example 5] The same preparation as in Comparative Example 1 was carried out, and the mixture was subjected to a dehydration step.
1323 g of P and 0.56 mol of H ₂ S were distilled off.
The effective sodium sulfide in the can is 21.96 moles.
Further, in the same manner as in Comparative Example 2, 3357 g of p-DCB
(1.04 mol / 1 mol sodium sulfide), NMP28
Add 64 g and 48 g of water (total water volume in the can is 1.5
Mol / mol of sodium sulfide), and the pre-stage polymerization was carried out. The conversion of p-DCB at the end of the first-stage polymerization was 94.5.
%Met.

After the first-stage polymerization, the mixture was once cooled to around room temperature, opened, and dried with anhydrous sodium acetate (purity 98.5%).
4 g (0.15 mol / mol of sodium sulfide) and water 44
7 g was added (total water content in the can was 2.6 mol / sodium sulfide 1 mol), followed by subsequent polymerization. The conversion of p-DCB at the end of the second-stage polymerization was 99.8%. The product was treated as in Comparative Example 1 and had an average particle size of 1370 μm
m, a degree of dispersion of 0.14, and a granular polymer having an intrinsic viscosity of 0.26 were obtained in a yield of 84%. The yield of the fine powder was 0.6%.

[Comparative Example 3] The same preparation as in Comparative Example 1 was carried out, and the mixture was subjected to a dehydration step.
349 g, and H ₂ S0.56 moles issued reservoir. The effective sodium sulfide in the can is 21.96 moles. Further, in the same manner as in Comparative Example 1, p-DCB3293 g
(1.02 mol / 1 mol sodium sulfide), NMP28
85 g and water 96 g were added (total water content in the can was 1.5 mol / sodium sulfide 1 mol), and pre-stage polymerization was performed. The conversion of p-DCB at the end of the first-stage polymerization was 93.1%.

Next, 447 g of water was injected under pressure (total water in the can was 2.6 mol / mol of sodium sulfide), and post-stage polymerization was carried out. The conversion of p-DCB was 99.5%. The product was treated as in Comparative Example 1 and had an average particle size of 45
A granular polymer having a particle size of 0 μm, a dispersity of 0.30 and an intrinsic viscosity of 0.33 was obtained in a yield of 86%. The yield of fine powder is 7.5%
Met.

Example 6 The same preparation as in Comparative Example 1 was carried out, and the mixture was subjected to a dehydration step.
372 g and 0.54 mol of H ₂ S distilled out. The effective sodium sulfide in the can is 21.98 mol. Further, in the same manner as in Comparative Example 3, p-DCB3296 g
(1.02 mol / 1 mol sodium sulfide), NMP29
14 g and 95 g of water are added (total water volume in the can is 1.5
Mol / mol of sodium sulfide), and pre-stage polymerization was carried out. The conversion of p-DCB at the end of the first-stage polymerization was 93.3%.

Next, anhydrous sodium acetate (purity 9
A mixed solution composed of 183 g (0.1 mol / 1 mol of sodium sulfide) and 448 g of water was injected under pressure (8.5%) (total water in the can was 2.6 mol / mol of sodium sulfide), and post-stage polymerization was carried out. . The product was treated as in Comparative Example 1 to give a granular polymer with a 92% yield. This granular polymer had an average particle size of 1700 μm, a particle size distribution of 0.16, and an intrinsic viscosity of 0.34. The yield of the fine powder was 0.8%.

Example 7 The same procedure as in Comparative Example 1 was carried out except that sodium sulfide containing 46.04% of Na ₂ S was used, and the mixture was subjected to a dehydration step. As a result, 1438 g of water, NMP
1380 g and 0.47 mol of H ₂ S distilled out. The effective sodium sulfide in the can is 21.95 mol. In the same manner as in Comparative Example 2, 3355 g (1.0
4 mol / mol of sodium sulfide) and 2909 g of NMP
Was added, and the pre-stage polymerization was carried out while stirring at a rotation speed of a stirrer of 350 rpm. Since no new water was added here, the amount of water in this step was 1.5 mol per 1 mol of sodium sulfide. The conversion of p-DCB at the end of the first-stage polymerization was 94.1%.

Subsequently, the rotation speed of the stirrer was increased to 400 rpm, and sodium acetate anhydride 183 was added while stirring was continued.
g (0.1 mol / sodium sulfide) and 447 g of water were injected under pressure (total water content in the can is 2.6 / mol of sodium sulfide), and post-stage polymerization was carried out. At the end of the second-stage polymerization, the conversion of p-DCB was 100%. After the end of the second-stage polymerization, the mixture was cooled to room temperature, and about 750 g of the content was uniformly sampled.
A granular polymer having an average particle diameter of 1070 μm, a degree of dispersion of 0.15, and an intrinsic viscosity of 0.28 was obtained with a yield of 93%. The yield of the fine powder was 0.2%.

Example 8 46.06% by weight of Na ₂ S
Was prepared and subjected to a dehydration step in the same manner as in Example 7 except that sodium pentahydrate crystals containing
429g, NMP1288g, and 0.50 moles of H ₂
S was collected. The effective sodium sulfide in the can is 21.9
3 moles. In the same manner as in Example 7, p-DCB was set to 3
353 g (1.04 mol / 1 mol sodium sulfide) and N
2812 g of MP was added, and pre-stage polymerization was performed. Here, since no new water was added, the amount of water in this step was 1.5 mol per 1 mol of sodium sulfide. The conversion of p-DCB at the end of the first-stage polymerization was 94.5%.

After the completion of the first-stage polymerization, the system was once cooled to around room temperature, and 365 g (0.2 mol / 1 mol of sodium sulfide) of anhydrous sodium acetate and 447 g of water were opened and added (total water amount in the can was 2.6). / 1 mol of sodium sulfide), followed by post-stage polymerization. At the end of the second-stage polymerization, the conversion of p-DCB was 100%. The treatment after the end of the second-stage polymerization was performed in the same manner as in Example 7, and the average particle diameter was 1390 μm,
A granular polymer having a dispersity of 0.18 and an intrinsic viscosity of 0.29 was obtained at a yield of 93%. The yield of the fine powder was 0.7%.
Table 1 shows the charged monomer ratios, polymerization conditions, and properties of the produced polymer in the above Examples and Comparative Examples.

[0059]

[Table 1] (Footnote) (* 1) Added during the second stage polymerization. (* 2) Added at the time of polymerization preparation. (* 3) 100 mesh on component. (* 4) 100 mesh pass, 390 mesh on component. (* 5) 390 mesh pass component. Mainly ultrafine powder.

The charge ratio of the monomers, that is, p-DCB / N
When a ₂ S is closer to 1, the molecular weight generally increases and the particle size tends to increase. Therefore, when compared at the same monomer charge ratio, it can be seen that there is a difference in properties between polymers having substantially the same intrinsic viscosity. When the stirring conditions are the same, the amount of fine powder generated decreases as the amount of the alkali metal carboxylate increases. However, the yield of ultrafine powder in the 390 mesh pass tends to increase, so that the yield of particulate polymer is not simply proportional to the increase in the amount of alkali metal carboxylate added. In Comparative Example 2 in which no alkali metal carboxylate was added, the average particle size was somewhat large, but the dispersity was wide and the yield was low. In Examples 7 and 8 in which the number of revolutions of the stirrer was increased by changing the stirring conditions, the yield of the granular polymer was improved, the average particle diameter was large, and the generation of fine powder was reduced.

[0061]

According to the production method of the present invention, high molecular weight and granular polyphenylene sulfide can be produced in high yield. Specifically, according to the present invention, the amount of coexisting water is significantly different between the former stage and the latter stage of polymerization.
In the two-stage polymerization method of PS, a granular polymer can be obtained economically in a high yield by including a very small amount of an alkali metal carboxylate at least in the second-stage polymerization.

Claims (1)

(57) [Claims] 1. A method for producing polyphenylene sulfide by reacting an alkali metal sulfide with a dihaloaromatic compound in an organic amide solvent, wherein the reaction comprises at least two steps of the following steps (1) and (2): A method for producing polyphenylene sulfide, wherein the method is carried out in a step and at least in step (2), 0.001 to 0.20 mol of an alkali metal carboxylate is present per 1 mol of the charged alkali metal sulfide. (1) 0.5 to 1 mol of charged alkali metal sulfide
In an organic amide solvent containing 2.4 mol of water, the alkali metal sulfide and the dihalo-aromatic compound are mixed in an amount of 170 to 270.
A reaction at a temperature of 50 ° C. to make the conversion of the dihaloaromatic compound 50 to 98 mol% to produce a polyphenylene sulfide prepolymer; and (2) 2.5 to 2.5 to 1 mol per mol of the charged alkali metal sulfide.
Water was added to the reaction system so that 10 mol of water was present, and at a temperature of 245 to 290 ° C, 0.5
Continuing the reaction for up to 20 hours to increase the conversion of the dihaloaromatic compound and to convert the prepolymer to high molecular weight polyphenylene sulfide.