JPH08239474A - Production of polyphenylene sulfide - Google Patents

Abstract

PURPOSE: To produce a polyphenylene sulfide having a melt viscosity markedly increased as compared with that of the starting polyphenylene sulfide and being excellent in viscosity stability also in a molten state. CONSTITUTION: A polyphenylene sulfide terminated with a covalently bonded chlorine, mainly consisting of repeating units represented by the formula:-ϕ- S-(wherein-ϕ-is p-phenylene) and having a melt viscosity of 10P or above at 316 deg.C, is reacted with 0.05-1.0mol, most desirably 0.2-0.5mol, per equivalent of the covalently bonded chlorine atoms contained in the polymer, alkali metal sulfide at desirably 210-270 deg.C in an organic amide solvent to obtain a polymer having a melt viscosity higher as compared with that of the starting polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a polyphenylene sulfide (hereinafter referred to as P) having a high molecular weight and excellent melt viscosity stability.
(Sometimes abbreviated as PS).

PPS has been attracting attention as an electric / electronic component, an automobile equipment member and the like due to its excellent heat resistance and chemical resistance. Also, it can be molded into various molded parts, films, sheets, fibers, etc. by injection molding, extrusion molding, etc.
In particular, it is widely used in fields where heat resistance and chemical resistance are required.

[0003]

2. Description of the Related Art As a method for producing PPS, a method of reacting a dihaloaromatic compound with an alkali metal sulfide such as sodium sulfide in an aprotic polar solvent such as N-methylpyrrolidone has hitherto been industrially widely used. It is used and is disclosed in, for example, Japanese Patent Publication No. 45-3368. However, the PPS produced by this method has a low molecular weight and melt viscosity and cannot be used for films, sheets, fibers and the like. Therefore, conventionally, a method of increasing the molecular weight by thermal crosslinking treatment has been adopted, but since this crosslinked PPS is mechanically weak, it is difficult to process it into a film, sheet, fiber or the like.

High molecular weight PPS that does not rely on thermal crosslinking has recently been produced and various improved processes have been proposed. For example, in Japanese Patent Publication No. 52-12240, an alkali metal carboxylate is used as a polymerization aid in the reaction system. According to this method, the addition amount of the polymerization aid is required to be about equimolar to the alkali metal sulfide, and in order to obtain PPS having a higher polymerization degree, lithium acetate and benzoic acid among the polymerization aids are used. It is necessary to use a large amount of sodium. Also, with this method,
Since the polymerization aid is separated and collected at the time of collecting PPS after the polymerization reaction, complicated auxiliary equipment and a large amount of cost are required, which is extremely disadvantageous from an economical point of view.

The method described in JP-A-63-39926 is a method in which the reaction is carried out in two stages, and a large amount of water is positively added in the second stage to obtain a high molecular weight PPS. In this method, water must be added during the reaction, so at the end of the first step, the temperature is once lowered to normal pressure and then water is added, or water is injected under pressure into a reaction can. It is necessary, and in fact, the operation is complicated and disadvantageous. Further, since a large amount of water is present in the second stage, the pressure becomes about 20 kg / cm ² G or more, which is not preferable because relatively expensive high pressure equipment is required.

Conventionally, there are various difficulties in obtaining a high molecular weight PPS only by polymerization, and it can be said that a simpler and economically advantageous production method has not been found yet. On the other hand, although it is not a method aimed at increasing the molecular weight of PPS,
A relatively simple method has been proposed as a method for improving the reactivity of polymer end groups.

Japanese Unexamined Patent Publication (Kokai) No. 2-140233 discloses that a relatively large amount of an alkali metal sulfide and / or an alkali metal hydrosulfide is added to a polar aprotic solvent after the polymerization or the isolation of the polymer. It is a method of obtaining a highly reactive PPS having a thiolate group or a thiol group at the polymer terminal by reacting with PPS. According to this method, the melt viscosity of PPS was apparently increased by about 2 times, but the increase of the polymer chain length, that is, the increase in the molecular weight was hardly achieved. Further, at 200 ° C or higher, there is almost no increase in viscosity.
On the contrary, at 0 ° C., the viscosity and the molecular weight are remarkably lowered, and it cannot be said to be a suitable method from the viewpoint of improving the melt viscosity and increasing the molecular weight. Further, the polymer obtained by this method is disadvantageous in terms of molding because it has a drawback that the viscosity stability upon melting is poor and that a large amount of gas is generated.

[0008]

In view of the above points, the present inventors have found that PPS having a high molecular weight and excellent melt viscosity stability.
In order to obtain the compound by a relatively simple method, it is possible to easily increase the molecular weight by adding a strictly limited amount of an alkali metal sulfide to the amount of the polymer terminal chlorine of PPS and polymerizing. Found and arrived at the present invention.

[0009]

That is, the present invention provides [-
[phi] -S-] (however,-[phi]-represents a p-phenylene group.) as a main constituent component, 3
Polyphenylene sulfide (a) having a melt viscosity of 10 poise or more at 16 ° C. and 0.05 to 1.0 mol, preferably 0.1 to 0.7 mol, relative to 1 equivalent of covalent chlorine contained in this polymer. It is characterized in that a polymer having a larger melt viscosity and a higher molecular weight than the original polymer is obtained by reacting 1 mol, more preferably 0.2 to 0.5 mol of an alkali metal sulfide (b) in an organic amide solvent. This is a method for producing polyphenylene sulfide, and its details will be described below.

An important requirement of the present invention is that PPS having a chlorophenyl group at the polymer end is used in order to linearly increase the polymerization degree of PPS, and 0.05 to 1.50 per 1 equivalent of covalent bond chlorine is used. The reaction is carried out with 0 mol, preferably 0.1 to 0.7 mol, more preferably 0.2 to 0.5 mol of an alkali metal sulfide. If the amount of this sulfide is less than the above range, or conversely too much, the degree of polymerization does not extend, or the polymer is decomposed to lower the degree of polymerization, and the object of the present invention cannot be achieved.

The PPS used in the present invention is not particularly limited, and known methods such as JP-B-45-3368 can be used.
Examples thereof include PPS produced by the method disclosed in Japanese Patent Publication No. 52-12240 and high polymerization degree PPS produced by the method disclosed in Japanese Patent Publication No. 52-12240. S-] (provided that -φ- is the same as above) as a main constituent unit, and contains covalent chlorine at the terminal, 31
The melt viscosity at 6 ° C should be 10 poise or higher. Here, the main constituent unit is at least 70 mol% or more, preferably 90 mol% or more, in the general formula [-φ-S
-], And the remaining constitutional unit is a unit copolymerizable with [-φ-S-], for example,

[0012]

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[0013]

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[0014]

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[0015]

[Chemical 4]

[0016]

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[0017]

[Chemical 6]

[0018]

[Chemical 7]

And the like. Other copolymerizable units include those having a functional group having active hydrogen such as an amino group, a thiol group, a hydroxyl group and a carboxyl group in the aromatic nucleus.

Examples of the alkali metal sulfide used in the present invention include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide and the like, and mixtures thereof. They may be used in the form of hydrates, anhydrides or aqueous solutions. These alkali metal sulfides can be obtained by reacting an alkali metal hydrosulfide with an alkali metal base, or hydrogen sulfide with an alkali metal base. Even if they are prepared in the reaction system, or those prepared in advance are used. You can use it. Among the above alkali metal sulfides, sodium sulfide is particularly preferable.

The amount of the alkali metal sulfide added is appropriately 0.05 to 1.0 mol, preferably 0.1 to 1.0 mol, relative to 1 equivalent of covalent chlorine contained in the PPS used.
The amount is 0.7 mol, more preferably 0.2 to 0.5 mol. If the amount is less than 0.05 mol, the reaction between the chlorophenyl group at the polymer terminal and the alkali metal sulfide does not proceed sufficiently, and the melt viscosity hardly increases. On the other hand, if the amount exceeds 1.0 mol, the reaction between the chlorophenyl group at the end of the polymer and the alkali metal sulfide will proceed after the start of the reaction, and a viscosity increase will be seen once. Perhaps because of this, only a polymer having a low viscosity can be obtained and the increase in melt viscosity cannot be achieved.

Examples of the organic amide solvent used in the present invention include N-methylpyrrolidone, N-ethylpyrrolidone,
N, N-dimethylformamide, N, N-dimethylacetamide, N-methylcaprolactam, N, N′-dimethylpropyleneurea, tetramethylurea, 1,3-dimethylimidazolidinone, hexamethylphosphoric triamide, etc. and mixtures thereof Can be mentioned. Of these, N-
Methylpyrrolidone and N-methylcaprolactam are particularly preferable from the viewpoint of being chemically stable and easily obtaining a high molecular weight polymer.

The amount of the organic amide solvent used is appropriately in the range of 1.0 to 8.0 weight ratio, preferably 2.0 to 6.0 weight ratio with respect to PPS. Illustrating a suitable operation in the method of the present invention, an organic amide solvent, PPS and an appropriate amount of an alkali metal sulfide are charged into an autoclave in an inert gas atmosphere, the system is closed, and then the temperature is raised with stirring. Then, the reaction is carried out at 210 to 270 ° C, preferably 220 to 250 ° C for 0.5 to 10 hours. If the reaction temperature is lower than 210 ° C, the polymerization rate will be remarkably slowed. On the other hand, if the reaction temperature is higher than 270 ° C, the decomposition of the polymer will proceed rapidly and the degree of polymerization tends to be lowered.

The recovery of PPS from the reaction mixture thus obtained is carried out by heating under normal pressure or reduced pressure to distill off only the solvent, and then the residual solid matter is separated into water, acetone, methyl ethyl ketone or alcohols. A method of washing once or twice or more with a solvent, neutralization, washing with water, filtering and drying, or adding water, acetone, methyl ethyl ketone, alcohols and ethers to the reaction mixture after the reaction, polymer and inorganic salt, etc. The method of precipitating the solid product of, and filtering it, washing and drying it.

The PPS obtained as described above is a PPS having a significantly increased melt viscosity and molecular weight as compared with that before the reaction, and is a polymer having excellent viscosity stability even when melted.

The PPS obtained by the method of the present invention is
1 in air or in a slightly oxidizing atmosphere, if necessary
The melt viscosity can be further increased by performing heat treatment at 50 ° C. or higher. Various moldings can be processed by injection molding, extrusion molding, rotational molding, and the like.

Since the polymer according to the present invention falls within the category of thermoplastic polymers, various applicable modifications of thermoplastic resins are possible. For example, a powdery filler such as carbon black, calcium carbonate powder, silica powder or titanium oxide powder, or a fibrous filler such as carbon fiber, glass fiber, asbestos or polyaramid fiber can be filled and used. Further, as a polymer alloy, polycarbonate, polyphenylene oxide, polyamide,
It is also possible to use a mixture of one or more synthetic resins such as polyacetal, polysulfone, polyethersulfone, polybutylene terephthalate, polyethylene terephthalate, liquid crystal polyester, polyimide, polystyrene, ABS and various elastomers. it can.

Further, a plasticizer such as an aromatic hydroxy derivative or a releasing agent, a silane-based titanate-based coupling agent,
Lubricants, crystal nucleating agents, rust preventives, flame retardants and the like may be added as necessary.

The PPS obtained by the method of the present invention may be used alone or in combination with the above-mentioned fillers and additives by injection molding or extrusion molding to obtain various molded products, films, sheets, pipes,
Can be processed into fibers, etc.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Evaluation of Physical Properties> (1) Content of Covalent Chlorine of PPS It was calculated by subtracting ionic chlorine content from total chlorine content. The total chlorine content was determined by ashing a sample of about 20 mg by an oxygen flask combustion method, absorbing it in a sodium carbonate absorption liquid, and measuring the chlorine ions contained in this liquid by ion chromatography analysis. The ionic chlorine content is about 2
The sample of g was dissolved in 30 ml of biphenyl by heating and then cooled, and a solution of diluted sulfuric acid added thereto was subjected to potentiometric titration with a silver nitrate solution to quantify only ionic chlorine.

(2) Melt viscosity of PPS Using a Shimadzu high-performance flow tester, preheating at 316 ° C. for 5 minutes, 10 kg load, nozzle hole diameter 0.5 mm, length 1.
It was measured under the condition of 0 mm.

(3) Melt Viscosity Stability It was measured in the same manner as the above melt viscosity except that it was preheated at 316 ° C. for 20 minutes, and expressed as the ratio of the melt viscosity at 20 minutes to 5 minutes of preheating.

(4) Amount of evolved gas of PPS 0.1 g of dried sample was placed in a vial and sealed in a sealed state.
After heating at 30 ° C. for 10 minutes, the mixture was cooled in a sealed state, and 5 μl of the supernatant obtained by adding 1 ml of acetone to this was injected into a capillary column type gas chromatographic analyzer to measure the area values of all peaks of the generated gas components. The sum was expressed as the amount of gas generated.

(5) Molecular weight Gel permeation chromatography using 1-chloronaphthalene as a moving layer (SSC-produced by Senshu Kagaku Co., Ltd.)
7,000), the retention time measured at 210 ° C. was converted to a molecular weight using standard polystyrene, and the peak top molecular weight was corrected by the universal calibration method.

[Reference Example 1] A method for producing the PPS used in Examples and Comparative Examples of the present invention will be described. In a titanium autoclave with a capacity of 20 liters, 2,568 g (20.0 mol) of 2.7 hydrate of sodium sulfide (60.8 wt% of Na ₂ S) was added.
And N-methylpyrrolidone (NMP) 5832 g were charged, and the temperature was raised to 202 ° C. with stirring under a nitrogen stream and water 5
The distillate containing 18 g was distilled off. The reaction system was cooled to 180 ° C., 2940 g (20.0 mol) of p-dichlorobenzene and 2808 g of NMP were charged, and the system was sealed. This was heated to 220 ° C over 30 minutes, polymerized at 220 ° C for 3 hours, and further polymerized at 250 ° C for 2 hours. After the polymerization, the system was cooled to room temperature, and 10.8 liter of water was added to the taken out slurry, followed by filtration and solid-liquid separation by a conventional method, and this cake was washed twice with 10.8 liter of water and then with 4 liter of acetone. After washing with water, filtration, and vacuum drying at 90 ° C. for 5 hours.

The melt viscosity of the obtained PPS is 210 poise.
And the molecular weight was 17,800. Also melt viscosity stability
Was 1.00, and no change in viscosity was observed during melting. this
Covalent chlorine content of polymer is 0.09 meq / g
And the amount of generated gas is 4.8 x 10 ⁶It was the peak area.

[Example 1] PPS1 having a melt viscosity of 210 poise and a covalent chlorine of 0.09 meq / g prepared in Reference Example 1 was placed in a titanium autoclave having a volume of 1 liter.
29.6 g (1.2 unit mol) and N-methylpyrrolidone (NMP) 389 g, and sodium sulfide (Na ₂ S)
2.7H ₂ O) (0.52 g, 4.1 mmol) was charged, the system was placed in a nitrogen atmosphere and then sealed, the temperature was raised to 230 ° C. over 30 minutes while stirring, and the reaction was carried out at this temperature for 3 hours. I went. After completion of the reaction, cool the autoclave to room temperature,
The contents were poured into 3 liters of water and the slurry was filtered off. Further, this cake was washed twice with 3 liters of water and once with 2 liters of acetone, and then washed with a vacuum drier 90%.
It was dried under reduced pressure at 5 ° C for 5 hours.

The yield of the produced polymer was 128.3 g (recovery yield 99.0%), and the melt viscosity was 750 poise.
Thickened 3.5 times compared to the original PPS. The molecular weight is 264
The value was 00, which was significantly higher in molecular weight than the original PPS. Further, this polymer has a melt viscosity stability of 0.99, shows almost no change in viscosity during melting, and has excellent viscosity stability. Furthermore, the generated gas amount is 3.5 × 10 ⁶ peak area, It was a high-purity polymer that generated very little gas.

Example 2 As a result of carrying out the reaction and treatment in the same manner as in Example 1 except that the reaction temperature was maintained at 220 ° C. for 3 hours, the resulting PPS had a melt viscosity of 530 poise and a molecular weight of 24,000. Which was higher in molecular weight than the original PPS. Also, melt viscosity stability is 1.
00, the amount of generated gas was 2.5 × 10 ⁶ peak area, the viscosity stability was good, and the generated gas was small.

Comparative Example 1 PPS1 having a melt viscosity of 210 poise and covalent chlorine of 0.09 meq / g prepared in Reference Example 1 was placed in a titanium autoclave having a capacity of 1 liter.
29.6 g (1.2 unit mol) and N-methylpyrrolidone (NMP) 389 g, and sodium sulfide (Na ₂ S)
2.7H ₂ O) (3.04 g, 24.0 mmol) was added,
The system is placed under a nitrogen atmosphere, then sealed, and stirred for 30
The temperature was raised to 180 ° C over a period of time, and the reaction was carried out at this temperature for 3 hours. After completion of the reaction, the autoclave was cooled to room temperature, the contents were put into 2 liters of water, and the slurry was filtered. Further, the cake was washed twice with 1 liter of 0.1N dilute hydrochloric acid and then with 2 liters of pure water once with 2 liters of acetone, and then dried under reduced pressure at 30 ° C. for 8 hours in a vacuum dryer.

The yield of the produced polymer was 127.1 g (collection yield 98.1%), and the melt viscosity was 480 poise. This polymer is about 2. apparently compared to the original PPS.
Although the viscosity was tripled, the molecular weight was 16,800, which was a little lower than the original PPS. That is, it was not possible to obtain PPS having an increased molecular weight by the method of this comparative example. The melt viscosity stability is 0.70.
Was extremely bad, and the generated gas amount was extremely large at 14.0 × 10 ⁶ peak area.

[Comparative Example 2] N as an alkali metal sulfide
As a result of carrying out the reaction and treatment in the same manner as in Example 1 except that 36.0 mmol of a ₂ S 2.7H ₂ O was charged and the reaction temperature was maintained at 220 ° C. for 3 hours, the melt viscosity of the obtained PPS was At 26 poises, the molecular weight was 10600, clearly indicating a decrease in molecular weight. Further, the melt viscosity stability was 0.55, the generated gas amount was 18.5 × 10 ⁶ peak area, the viscosity stability was poor, and the generated gas was extremely large.

[Comparative Example 3] N as an alkali metal sulfide
a ₂ S 2.7H ₂ O was added in an amount of 0.2 mmol except that
Reaction and treatment were carried out in the same manner as in Example 1. The results are shown in Table 1. The amount of sodium sulfide added was too small, and almost no increase in melt viscosity was observed.

[Comparative Example 4] N as an alkali metal sulfide
The reaction and treatment were carried out in the same manner as in Example 1 except that 15.0 mmol of a ₂ S 2.7H ₂ O was charged. The results are shown in Table 1. When the amount of sodium sulfide added was too large with respect to the chlorine content, the melt viscosity was significantly reduced.
Further, the melt viscosity stability was extremely poor, and the amount of generated gas was remarkably large.

[Examples 3 to 7] In the same manner as in Example 1, a predetermined amount of PPS, alkali metal sulfide and N-methylpyrrolidone shown in Table 2 were charged, and reaction and treatment were performed at a predetermined temperature and time. I went. Table 2 shows the results.

[Examples 8 to 10] In the same manner as in Example 1, PPS, alkali metal sulfide and N-methylpyrrolidone shown in Table 3 were charged in predetermined amounts, and reacted and treated at predetermined temperature / time. I went. The results are shown in Table 3.

[Example 11] p-dichlorobenzene was added to 3
Reference Example 1 except that 410 g (23.2 mol) was charged.
Polymerization and post-treatment were carried out in the same manner as in. The obtained PPS
In the same manner as in Example 1, using P shown in Table 3
A predetermined amount of PS, an alkali metal sulfide and N-methylpyrrolidone were charged, and the reaction and treatment were performed at a predetermined temperature and time. The results are shown in Table 3.

Example 12 Polymerization was carried out in the same manner as in Reference Example 1 except that 1320 g of lithium acetate was charged at the same time as sodium sulfide and the polymerization was carried out at 220 ° C. for 6 hours. After the polymerization, the slurry taken out after cooling was filtered, and the same post-treatment as in Reference Example 1 was performed except that the solid content was washed with 4 liters of NMP and 4 liters of isopropyl alcohol. Using the obtained PPS, in the same manner as in Example 1, PPS, an alkali metal sulfide and N-methylpyrrolidone shown in Table 3 were charged in predetermined amounts, and reacted and treated at a predetermined temperature / time. . The result is the third
Shown in the table.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

[Table 3]

[0053]

According to the method of the present invention, PPS having a significantly increased melt viscosity as compared with that before reaction and having excellent viscosity stability even during melting can be obtained by a simple method. The high molecular weight PPS obtained by this method can be processed into various molded products, films, sheets, pipes, fibers and the like by injection molding or extrusion molding alone or in combination with various fillers.

Claims (4)

[Claims] 1. A melt viscosity at 316 ° C. is 10 poises, containing a repeating unit represented by the general formula [-φ-S-] (where -φ- represents a p-phenylene group) as a main constituent. The polyphenylene sulfide (a) containing covalent chlorine at the terminal and the alkali sulfide (b) in an amount of 0.05 to 1.0 mol per 1 equivalent of covalent chlorine contained in the polymer are added to the organic amide. A method for producing polyphenylene sulfide, which comprises reacting in a system solvent to obtain a polymer having a higher melt viscosity than the original polymer. 2. The method according to claim 1, wherein 0.1 to 0.7 mol of an alkali metal sulfide is reacted in an organic amide solvent with respect to 1 equivalent of covalent chlorine contained in polyphenylene sulfide. 3. The method according to claim 1, wherein 0.2 to 0.5 mol of an alkali metal sulfide is reacted in an organic amide solvent with respect to 1 equivalent of covalent chlorine contained in polyphenylene sulfide. 4. In an organic amide solvent, 210 to 270 ° C.
The method according to claim 1, wherein the reaction is carried out within the range.