JP4894090B2 - Process for producing polyphenylene sulfide and extruded product - Google Patents

Description

【００６３】
【発明の効果】
以上説明したように、本発明によれば、高分子量のＰＰＳを効率よく短時間に製造することができる。したがって、本発明の高分子量ＰＰＳの製造方法は、工業的規模でのＰＰＳを安全かつ経済的に製造する方法として好適である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing polyphenylene sulfide (hereinafter abbreviated as PPS) and an extrusion molded product obtained by the method, and more particularly to a method for efficiently producing high molecular weight PPS in a short time and an extrusion molded product. Is.
[0002]
[Prior art]
PPS is an engineering plastic that excels in heat resistance, chemical resistance, flame resistance, mechanical strength, electrical properties, and dimensional stability. Various types of molding methods such as injection molding, extrusion molding, and compression molding can be used. Since it can be molded into molded articles, films, sheets, fibers, etc., it is widely used in a wide range of fields such as electrical / electronic equipment and automobile equipment.
[0003]
As a method for producing PPS, Japanese Patent Publication No. 45-3368 discloses an alkali metal sulfide such as sodium sulfide and a dihaloaromatic compound such as p-dichlorobenzene in an organic amide solvent such as N-methyl-2-pyrrolidone. In this method, only PPS having a low molecular weight and a low melt viscosity can be obtained. Such a low molecular weight PPS can be increased in molecular weight by heating in the presence of air after polymerization and oxidative curing (curing). However, the cured PPS thus obtained has poor mechanical properties. Since it is sufficient and not linear, it has been difficult to form a sheet, film, fiber, or the like.
[0004]
In recent years, in order to obtain a high molecular weight PPS at the time of polymerization, various production methods improved from the above method have been proposed. As a means for improving the polymerization method of PPS, a method of adding various polymerization assistants when reacting an alkali metal sulfide and a dihaloaromatic compound in an organic amide solvent is typical. A method using an alkali metal carboxylate as an auxiliary agent (Japanese Patent Publication No. 52-12240), a method using an alkaline earth metal salt of an aromatic carboxylic acid (Japanese Patent Laid-Open No. 59-219332), and an alkali A method using a metal halide (US Pat. No. 4,038,263) and a method using a sodium salt of an aliphatic carboxylic acid (Japanese Patent Laid-Open No. 1-161022) are also proposed.
[0005]
According to these methods, it is possible to obtain linear and high molecular weight PPS by polymerization, but in order to obtain PPS having a high degree of polymerization in a shorter time, expensive such as lithium acetate and sodium benzoate are used. It is necessary to carry out the polymerization using a polymerization aid, and even if an inexpensive polymerization aid such as sodium acetate is simply applied, there is a problem that the polymerization time is long and it is economically disadvantageous.
[0006]
On the other hand, Japanese Patent Publication No. 63-33775 proposes to employ a specific two-stage polymerization method in a method of obtaining PPS by reacting an alkali metal sulfide and a dihaloaromatic compound in an organic amide solvent. ing. That is, in this prepolymerization step, the reaction is carried out at a temperature of 180 to 235 ° C. in the presence of 0.5 to 2.4 mol of water per mol of the charged alkali metal sulfide. After producing a low-viscosity prepolymer with a compound conversion rate of 50 to 98 mol%, 2.5 to 7 mol of water per mol of charged alkali metal sulfide is present in the subsequent polymerization step. Is a two-stage polymerization method in which water is added to the reaction system and the temperature is raised to a temperature of 245 to 290 ° C. to continue the reaction. In this method, in order to obtain a sufficiently high molecular weight PPS, There is a problem that a long polymerization time is required.
[0007]
Further, JP-A-6-145355 discloses that alkali metal carboxylate is compared with 0.001 to 0.20 mol in the presence of 0.5 to 2.4 mol of water per mol of alkali metal sulfide. However, the main purpose of this method is to increase the yield by precipitating granular PPS, and the amount of such a small amount of alkali metal carboxylate is reduced. It was difficult to obtain PPS with a high degree of polymerization in a short time with the amount used.
[0008]
[Problems to be solved by the invention]
The present invention has been achieved as a result of studying the solution of the problems in the prior art described above as an issue.
[0009]
Accordingly, an object of the present invention is to provide a method for efficiently producing a high molecular weight polyphenylene sulfide in a short time.
[0010]
[Means for Solving the Problems]
As a result of diligent research to achieve the above object, the present inventors have found that it is difficult to efficiently obtain a high degree of polymerization polyphenylene sulfide in a short time even if only the polymerization aid or only the amount of water is increased. In the low temperature stage of the process, a process for producing a prepolymer by reacting the dihaloaromatic compound to 30 to 80 mol% is provided, and the polymerization assistant amount and the water content are regulated to a specific ratio, and the prepolymer is heated at a high temperature. As a result of the reaction, it was found that PPS having a high degree of polymerization was obtained in a short time and reached the present invention.
[0011]
  That is, the present invention produces polyphenylene sulfide by reacting an alkali metal sulfide and a dihaloaromatic compound in a temperature range of 200 ° C. or more and less than 290 ° C. in an organic amide solvent in the presence of a polymerization aid. A process for producing polyphenylene sulfide, characterized in that the reaction is carried out at least by the following steps 1 and 2.A method for producing polyphenylene sulfide, characterized in that a polymerization aid is added before the dehydration step before the start of polymerization.Is to provide.
[0012]
Step 1: In an organic amide solvent, an alkali metal sulfide and a dihaloaromatic compound are converted within a temperature range of 200 ° C. or higher and lower than 245 ° C. with a conversion rate of 30 to 30 ° C.60Reacting to a mole% to form a polyphenylene sulfide prepolymer, and
  Step 2: In the step of converting the prepolymer into high molecular weight polyphenylene sulfide within a temperature range of 245 ° C. or more and less than 290 ° C., the amount of polymerization aid in the system is charged and 0.33 to 0 per mole of alkali metal sulfide A process for producing polyphenylene sulfide, characterized in that the amount is 70 mol.
[0013]
In the method for producing polyphenylene sulfide of the present invention, in the method for producing polyphenylene sulfide by reacting an alkali metal sulfide with a dihaloaromatic compound in the presence of a polymerization aid in an organic amide solvent, Water is added to the reaction system so that the amount of water in the system in step 2 is 1.0 mol or more and less than 2.5 mol per mol of the charged alkali metal sulfide, and the molar ratio of the water to the polymerization aid is It is preferable to convert the prepolymer to high molecular weight polyphenylene sulfide by setting [polymerization aid amount (mole) / water content (mole)] to 0.1 to 0.7.
[0014]
Furthermore, in the method for producing polyphenylene sulfide of the present invention, in the method for producing polyphenylene sulfide by reacting an alkali metal sulfide and a dihaloaromatic compound in an organic amide solvent in the presence of a polymerization aid, It is preferable to carry out the reaction in a system containing a polymerization stabilizer typified by 0.01 to 0.2 mol of alkali metal hydroxide per mol of alkali metal sulfide.
[0015]
  Moreover, the organic amide solvent in the said process 1 contains 0.5 mol or more and less than 1.5 mol of water per mol of alkali metal sulfide prepared, polymerization time T1 of the said process 1 (Min), 20 minutes or more including temperature rise and fall time120 minutesAnd polymerization time T1 including the temperature increase / decrease time of step 1 (Min) And polymerization time T2 including the temperature increase / decrease time of step 2 (Min) Ratio (T1 / T2) is preferably 0.1 to 2.0.
[0016]
Furthermore, since the polyphenylene sulfide resin obtained by the production method of the present invention has a sufficiently high melt viscosity and excellent toughness, it is particularly useful as an extruded product.
[0017]
In addition, the method for synthesizing polyphenylene sulfide in the present invention is also useful in terms of improving productivity by polymerizing a medium-low viscosity polymer in an extremely short time.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail in the order of alkali metal sulfide, dihaloaromatic compound, molecular weight regulator, branching / crosslinking agent, polymerization solvent, polymerization aid, polymerization stabilizer, polymerization reaction, post-treatment and produced PPS.
[0019]
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 of two or more thereof. Particularly preferred is sodium sulfide. These alkali metal sulfides can be used as hydrates or aqueous mixtures or in the form of anhydrides. Further, an alkali metal sulfide prepared in situ in the reaction system from an alkali metal hydrosulfide and an alkali metal hydroxide, or an alkali metal sulfide prepared in a separate reaction tank before the reaction can be used. . Also, an alkali metal sulfide prepared in situ in the reaction system from an alkali metal hydroxide such as lithium hydroxide or sodium hydroxide and hydrogen sulfide, or an alkali metal sulfide prepared in a separate reaction tank before the reaction Can also be used.
[0020]
In the present invention, the amount of charged alkali metal sulfide means the remaining amount obtained by subtracting the loss from the actual charged amount when a partial loss of alkali metal sulfide occurs before the start of the reaction due to dehydration operation or the like. It shall be.
[0021]
Dihaloaromatic compounds
Examples of the dihaloaromatic compound used in the present invention include dihalobenzenes such as p-dichlorobenzene, m-dichlorobenzene and p-dibromobenzene, and 1-methoxy-2,5-dichlorobenzene and 3,5-dichlorobenzoic acid. And dihaloaromatic compounds containing a substituent other than halogen. Especially, the dihalo aromatic compound which has p-dihalobenzene represented by p-dichlorobenzene as a main component is preferable. Particularly preferably, it contains 80 to 100 mol% of p-dichlorobenzene. It is also possible to combine two or more different dihaloaromatic compounds into a copolymer.
[0022]
Molecular weight regulator, branching / crosslinking agent
In the present invention, a monohalo compound (not necessarily an aromatic compound) can be used in combination for forming the end of the produced PPS or adjusting the polymerization reaction or the molecular weight. In addition, in order to form a branched or crosslinked polymer, a polyhalo compound of trihalo or higher such as 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene (not necessarily an aromatic compound), active hydrogen It is also possible to use a halogen-containing aromatic compound and a halogen-aromatic nitro compound in combination.
[0023]
Polymerization solvent
In the present invention, an organic amide solvent is used as a polymerization solvent. Examples of the organic amide solvent include N-alkylpyrrolidone such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone, caprolactams such as N-methyl-ε-caprolactam, 1,3-dialkyl-2- Aprotic organic amide solvents represented by imidazolidinone, tetraalkylurea, hexaalkylphosphoric triamide and the like, and mixtures thereof are preferably used because of high stability of the reaction. Among these, use of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) is particularly preferable. The amount of the polymerization solvent used in the present invention is preferably in the range of 0.2 to 10 mol, more preferably in the range of 2 to 5 mol, per mol of the charged alkali metal sulfide.
[0024]
Polymerization aid
In the present invention, a polymerization aid is used in order to obtain PPS having a high degree of polymerization in a shorter time. Specific examples of the polymerization aid include alkali metal carboxylates and lithium halides generally known as polymerization aids for PPS.
Particularly preferred are alkali metal carboxylates.
[0025]
The alkali metal carboxylate has a general formula R (COOM) n (wherein R is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group, an alkylaryl group or an arylalkyl group. , Lithium, sodium, potassium, rubidium and cesium, and n is an integer of 1 to 3). Alkali metal carboxylates can also be used as anhydrous, hydrated or aqueous solutions. Specific examples of the alkali metal carboxylate include, for example, lithium acetate, sodium acetate, potassium acetate, sodium propionate, lithium valerate, sodium benzoate, sodium phenylacetate, potassium p-toluate, and mixtures thereof. Can be mentioned. Alkali metal carboxylate is an organic acid, an organic acid, and one or more compounds selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal bicarbonates, with approximately equal chemical equivalents. You may form by adding and making it react one by one. Among the alkali metal carboxylates, sodium acetate is particularly preferably used because it is inexpensive and easily available.
[0026]
  The amount of these polymerization aids used is 1 mol of the charged alkali metal sulfide.0.33Mol to 0.7 mol,0.33The range of -0.45 mol is more preferable, and the range of 0.33-0.42 mol is still more preferable. If it is less than the above range, the effect of increasing the degree of polymerization is insufficient, and if it exceeds the above range, not only the effect of increasing the degree of polymerization can be obtained, but also the polymerization required to obtain a polymer of the same degree of polymerization. Conversely, the time becomes longer.
[0027]
  These polymerization aids,rearAs contained in the reaction system in the step polymerization process (post-process 2 below), ThatWhen to addHeavyOf the dehydration processBefore.
[0028]
  Polymerization stabilizer
  In the present invention, a polymerization stabilizer may be used to stabilize the polymerization reaction system and prevent side reactions. The polymerization stabilizer contributes to stabilization of the polymerization reaction system and suppresses undesirable side reactions. One measure of the side reaction is the generation of thiophenol, and the addition of a polymerization stabilizer can suppress the generation of thiophenol. Specific examples of the polymerization stabilizer include compounds such as alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, and alkaline earth metal carbonates. Among them, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide are preferable..
[0029]
These polymerization stabilizers can be used alone or in combination of two or more. The polymerization stabilizer is usually 0.01 to 0.2 mol, preferably 0.020 to 0.15 mol, more preferably 0.03 to 0.10 mol, relative to 1 mol of the charged alkali metal sulfide. Used in. If this ratio is small, the stabilizing effect is insufficient. Conversely, if the ratio is too large, it is economically disadvantageous or the polymer yield tends to decrease. The polymerization stabilizer may be added before the dehydration step before the start of the pre-stage polymerization, at any point during the start of the pre-stage polymerization or in the middle of the post-stage polymerization, or any combination thereof. Preferably, it is before the dehydration step or at the start of the previous stage polymerization. In addition, when a part of alkali metal sulfide decomposes | disassembles at the time of spin-drying | dehydration operation and hydrogen sulfide generate | occur | produces, the alkali metal hydroxide produced | generated as a result can also become a polymerization stabilizer.
[0030]
Polymerization reaction
In the present invention, when producing PPS by reacting an alkali metal sulfide and a dihaloaromatic compound in an organic amide solvent in the presence of a polymerization aid, the above reaction is carried out at least in the following step 1 and Line by 2Add a polymerization aid before the dehydration step before the start of polymerizationIt is also characterized byNisoThere may be additional steps such as other pre-processing steps and post-processing steps.
[0031]
Step 1: In an organic amide solvent, an alkali metal sulfide and a dihaloaromatic compound are converted within a temperature range of 200 ° C. or higher and lower than 245 ° C. with a conversion rate of 30 to 30 ° C.60Reacting to a mole% to form a polyphenylene sulfide prepolymer; and
Step 2: Charge the amount of polymerization aid in the system per mole of alkali metal sulfide0.33A step of converting the prepolymer into a high molecular weight polyphenylene sulfide within a temperature range of 245 ° C. or more and less than 290 ° C.
When starting the above step 1, the alkali metal sulfide and the dihaloaromatic compound are added to the organic amide solvent, desirably in an inert gas atmosphere at room temperature to 220 ° C., preferably 100 to 220 ° C.. ThisThe order in which these raw materials are charged may be out of order or even simultaneously. Alkali metal sulfides are usually used in the form of hydrates. If the water content is less than 0.5 moles per mole of charged alkali metal sulfides, the required amount of water is added to replenish. It is preferable to do. If the alkali metal sulfide content is too high, before adding the dihaloaromatic compound, the mixture containing the organic amide solvent and the alkali metal sulfide is heated to remove excess water out of the system. Needed (dehydration process). In addition, when water is removed too much by this operation, it is normal to replenish by adding a deficiency.
[0032]
In addition, the alkali metal sulfide includes an alkali metal sulfide prepared in situ in the reaction system from an alkali metal hydrosulfide and an alkali metal hydroxide, or an alkali metal adjusted in a separate reaction tank before the reaction. Sulfides can also be used. Although there is no particular limitation on this method, desirably, an alkali metal hydrosulfide and an alkali metal hydroxide are added to an organic amide solvent in an inert gas atmosphere at a temperature ranging from room temperature to 150 ° C., preferably from room temperature to 100 ° C. A method in which the temperature is raised to at least 150 ° C. or higher, preferably 180 to 250 ° C. under normal pressure or reduced pressure, to distill off water (dehydration step). A polymerization aid may be added at this stage. Moreover, in order to accelerate | stimulate distillation of a water | moisture content, you may react, adding toluene etc.
[0033]
The amount of coexisting water in the reaction system in Step 1 above is usually in the range of 0.5 to 1.5 mol, preferably 0.8 to 1.2 mol, per mol of the charged alkali metal sulfide. By defining the amount of coexisting water in step 1 in such a relatively small range, PPS having a high degree of polymerization can be obtained in a shorter time.
[0034]
The reaction temperature in Step 1 is preferably 200 ° C. or higher and lower than 245 ° C., and the average reaction temperature is preferably 220 ° C. or higher and 240 ° C. or lower.
[0035]
  In step 2 above, the amount of polymerization aid is charged and per mole of alkali metal sulfide.0.33It is important to set it to ˜0.70 mol. A more preferable range of the polymerization assistant amount is0.33It is -0.45 mol, and 0.33-0.42 mol is still more preferable. If it is less than the above range, the effect of increasing the degree of polymerization is insufficient, and if it exceeds the above range, not only the effect of increasing the degree of polymerization beyond that can be obtained, but also an adverse effect on the polymerization time.
[0036]
  These polymerization aids,rearAs contained in the reaction system in the step polymerization process (post-process 2 below), ThatWhen to addHeavyOf the dehydration processBefore.
[0037]
In step 2, it is desirable to add water so that the amount of water in the polymerization system is 1.0 mol or more and less than 2.5 mol per mol of the charged alkali metal sulfide. The addition timing of water may be any of the start time, the intermediate time, and the end time of the above process, but it is preferable to start the addition before half of the time required for the above process 2. If the amount of water is less than the above range, the effect of increasing the degree of polymerization decreases.On the other hand, if the amount exceeds the above range, not only the polymerization time becomes longer, but also the pressure in the polymerization vessel increases, Since a polymerization kettle having high pressure resistance is required, it is not preferable in terms of economy and safety.
[0038]
In the above step 2, it is preferable that the molar ratio of the moisture present in the reaction system and the polymerization assistant [polymerization assistant amount (mol) / water content (mol)] is 0.1 to 0.7. Even if this molar ratio is less than the above range or exceeds the above range, it is difficult to obtain a sufficiently high degree of polymerization PPS in a short time. A more preferable range of the molar ratio is 0.25 to 0.45.
[0039]
In particular, water is added to the reaction system so that the amount of water in the above step 2 is 1.0 mol or more and less than 2.5 mol per mol of the charged alkali metal sulfide, and the mol of the water and the polymerization aid. By converting the prepolymer to high molecular weight polyphenylene sulfide at a ratio of [polymerization aid amount (mol) / water content (mol)] of 0.1 to 0.7, a high degree of polymerization PPS can be obtained in a short time. Preferred above.
[0040]
The reaction temperature in Step 2 is preferably 245 ° C. or higher and lower than 290 ° C., and the average reaction temperature is preferably 250 ° C. or higher and 280 ° C. or lower. A reaction temperature exceeding the above range is not preferable because the inside of the reaction system tends to decompose.
[0041]
In the present invention, the amount (charge) of the polymerization stabilizer used is usually 0.01 to 0.2 mol, preferably 0.06 to 0.15 mol per mol of the charged alkali metal sulfide. Is desirable to obtain high molecular weight PPS. If the amount used is too small, undesirable side reactions cannot be suppressed, and it becomes difficult to obtain a PPS having a sufficiently high degree of polymerization. On the other hand, if the amount is too large, it is economically disadvantageous or the polymer yield tends to decrease.
[0042]
In this invention, the usage-amount (preparation amount) of a dihalo aromatic compound is 0.9-2.0 mol normally with respect to 1 mol of preparation alkali metal sulfide, Preferably it is 0.95-1.5 mol, More preferably The range of 1.0 to 1.3 mol, more preferably 1.01 to 1.10 mol, is desirable for obtaining a high molecular weight PPS. When this use ratio is less than 0.9 mol or more than 2.0 mol, it is difficult to obtain a high-viscosity (high polymerization degree) PPS suitable for processing.
[0043]
Moreover, at the time of switching from the said process 1 to the process 2, the conversion rate of the dihalo aromatic compound in a system is 30-.60When it reaches the mol%TheWhen the conversion is less than 30 mol%, an undesirable reaction such as decomposition tends to occur during the subsequent polymerization in Step 2. Also, the conversion rate is60Mol%Exceeding rangeThen, since reaction time becomes long, it is not economically preferable.
[0044]
The conversion rate of the dihaloaromatic compound (abbreviated as DHA here) is a value calculated by the following formula. The remaining amount of DHA can be usually determined by gas chromatography.
[0045]
(A) When dihaloaromatic compound is added in excess by molar ratio to alkali metal sulfide
Conversion = [DHA charge (mol) -DHA remaining amount (mol)] / [DHA charge (mol) -DHA excess (mol)]
(B) In cases other than (a) above
Conversion = [DHA charge (mol) -DHA remaining amount (mol)] / [DHA charge (mol)]
In the present invention, the polymerization time in Step 1 is preferably in the range of 20 minutes to less than 2 hours, and more preferably in the range of 60 minutes to 110 minutes. If the reaction time is less than the above range, it is often difficult to achieve a sufficiently high degree of polymerization. Even if a time exceeding the above range is taken, the resulting effect of increasing the degree of polymerization is reduced, which is economically disadvantageous. It becomes.
[0046]
In addition, the polymerization time in Step 2 is preferably in the range of 80 to 220 minutes, and more preferably in the range of 100 minutes to 180 minutes. If the reaction time is less than the above range, it is often difficult to achieve a sufficiently high degree of polymerization. Even if a time exceeding the above range is taken, the resulting effect of increasing the degree of polymerization is reduced, which is economically disadvantageous. It becomes.
[0047]
By applying the method of the present invention, PPS having the most excellent polymerization degree and economical efficiency can be obtained in the total polymerization reaction time in the range of 1 to 10 hours, particularly in the range of 4 to 8 hours. Here, the total polymerization reaction time indicates the total time in which the polymerization system is in the range of 200 ° C. to 290 ° C. including the temperature raising, constant temperature, and temperature lowering processes after the monomer raw material is charged.
[0048]
  In particular, in Step 1, the polymerization time T1 (including the temperature rising time from the start of polymerization and reaching 245 ° C. when moving to Step 2)Min) And the polymerization time T2 including the temperature rise time after reaching 245 ° C. and the temperature fall time after completion of the polymerization in the transition from the step 1 to the step 2 in the step 2 (Min) In the range of T1 / T2 = 0.1 to 2.0, more preferably in the range of T1 / T2 = 0.4 to 1.5, and still more preferably T1 / T2 = 0.5 to 0.00. By controlling in the range of 8, a high degree of polymerization PPS can be obtained in a shorter time.
[0049]
Post-processing
In the present invention, the post-treatment after completion of the polymerization reaction can be performed by a conventional method. For example, after completion of the polymerization reaction, the polymerization solvent is volatilized and removed by flash method, followed by repeated washing with water and drying, and the filtered product slurry is filtered as it is or diluted with water. Then, PPS can be obtained by repeatedly washing with water and drying. The product slurry may be sieved through the polymer while still in the high temperature state. Further, after the above filtration and sieving, PPS may be washed with the same organic amide solvent as the polymerization solvent, organic solvents such as ketones and alcohols, and high-temperature water. PPS can also be treated with an acid such as acetic acid or hydrochloric acid or a salt such as ammonium chloride.
[0050]
Generated PPS
According to the method of the present invention, a high molecular weight PPS having an MFR of 110 g / 10 min or less, more preferably 80 g / 10 min or less, can be obtained in a high yield in a short time. Since the PPS obtained by the method of the present invention has a high molecular weight in a linear form, it can be formed into not only injection molded products but also extruded products such as sheets, films, fibers and pipes by extrusion molding. it can.
[0051]
The PPS obtained by the method of the present invention can be used alone, but various inorganic fillers, fibrous fillers, various synthetic resins and the like may be blended and used as desired.
[0052]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The physical properties were measured according to the following methods.
[0053]
(1) Polymer yield
Based on the weight (theoretical amount) assuming that all sodium sulfide in the autoclave after the dehydration step was converted to PPS. If sodium sulfide is charged in excess of the dihaloaromatic compound, it may not be converted to PPS at all, but even in that case, the amount of sodium sulfide should be considered as a standard.
[0054]
(2) Polymer melt viscosity
Using a Toyo Seiki melt indexer (length 8.00 mm, hole diameter 2.095 mm orifice, sample amount 7 g, preheating time 5 minutes from sample preparation to measurement start, load 5000 g) under the condition of 315.5 ° C. Measurements were made and the polymer melt flow rates were compared.
[0055]
[Example 1]
(Dehydration process)
In a 1 liter autoclave equipped with a stirrer, 118 g (1.00 mol) of 47% sodium hydrosulfide, 42.9 g (1.03 mol) of 96% sodium hydroxide, 163 g (1) of N-methyl-2-pyrrolidone (NMP) .65 mol), 32.8 g (0.4 mol) of sodium acetate, and 150 g of ion-exchanged water, and gradually heated to 240 ° C. over about 3 hours while flowing nitrogen at normal pressure to distill 212 g of water and 4 g of NMP. After dispensing, the reaction vessel was cooled to 160 ° C. The amount of water remaining in the system per mole of the alkali metal sulfide charged was 1.05 mol including the water consumed for the hydrolysis of NMP. The amount of hydrogen sulfide scattered was 2 mol%.
(Process 1)
Next, 147 g (1.00 mol) of p-dichlorobenzene (p-DCB) and 131 g (1.31 mol) of NMP were added, the reaction vessel was sealed under nitrogen gas, and the mixture was stirred at 240 rpm to 200 ° C to 235 ° C. The temperature was raised to 0.8 ° C. at a rate of 0.8 ° C./min and held at 235 ° C. for 35 minutes. Thereafter, the temperature was raised under the following conditions, and the process shifted to Step 2.
(Process 2)
That is, the temperature was raised to 270 ° C. at a rate of 0.8 ° C./min and held for 90 minutes. After 10 minutes had reached 270 ° C., 14.4 g (0.8 mol) of water was injected into the system over 15 minutes. The water content in the system was 1.8 mol per 1 mol of the alkali metal sulfide charged, including the water generated as a by-product in the polymerization process. After 90 minutes at 270 ° C., it was cooled to 200 ° C. at a rate of 1.0 ° C./minute, and then rapidly cooled to near room temperature.
(Recovery process)
Take out the contents, dilute with 0.5 liters of NMP, filter off the solvent and solids with a sieve (80 mesh), wash the resulting particles several times with 1 liter of warm water, filter and remove the PPS polymer particles Got. This was dried with hot air at 80 ° C. and dried under reduced pressure at 120 ° C.
[0056]
The melt flow rate of the obtained PPS was 40 g / 10 min, and the yield was 92%.
[0057]
The same operation as described above was performed halfway, and after reacting at 235 ° C. for 35 minutes, the polymerization system was rapidly cooled when the temperature was raised to 245 ° C. at a rate of 0.8 ° C./min. When p-DCB in the polymerization content was measured by a gas chromatographic method, the conversion was 60%.
These results are shown in Table 1.
[Example 2]
Except that the amount of water injected after 10 minutes after reaching 270 ° C. was 0 mol (in addition, the amount of water in the system is 1.0 mol including the water generated as a by-product in the polymerization step), Polymerization and recovery operations were performed in the same manner as in Example 1. The results are shown in Table 1.
[0058]
From this result, it can be seen that the higher the water content in the system, the better the degree of polymerization.
[Comparative Example 1]
Polymerization and recovery operations were performed in the same manner as in Example 1 except that the amount of sodium acetate was 0.20 mol. The results are shown in Table 1.
[Comparative Example 2]
Polymerization and recovery operations were performed in the same manner as in Example 1 except that the amount of sodium acetate was 0.80 mol. The results are shown in Table 1.
[Example 3]
Polymerization and recovery operations were performed in the same manner as in Example 1 except that the reaction time at 270 ° C. was 60 minutes. The results are shown in Table 1.
[0059]
As a result, even if the polymerization time is shortened by 30 minutes, a sufficiently high degree of polymerization can be efficiently obtained.
It turns out that it is obtained.
[Example 4]
Polymerization and recovery operations were performed in the same manner as in Example 1 except that the holding time at 235 ° C. was shortened from 35 minutes to 20 minutes and the holding time at 270 ° C. was extended from 90 minutes to 105 minutes. The results are shown in Table 1.
[Comparative Example 3]
Polymerization and recovery operations were performed in the same manner as in Example 1 except that the holding time at 235 ° C. was extended from 35 minutes to 50 minutes and the holding time at 270 ° C. was reduced from 90 minutes to 75 minutes. The results are shown in Table 1.
[0060]
As a result, Example 4,Comparative Example 3The degree of polymerization tends to be lower than that of Example 1, and even when the total polymerization time is the same, adjusting the polymerization time ratio of Step 1 and Step 2 can obtain a PPS with a higher degree of polymerization. It turns out that it is important.
[Comparative Example 4]
  Polymerization and recovery operations were performed in the same manner as in Example 1 except that the amount of 96% sodium hydroxide charged was 40.8 g (0.98 mol). The results are shown in Table 1.
[0061]
From this result, it can be seen that a larger amount of the polymerization stabilizer typified by sodium hydroxide is superior in increasing the degree of polymerization.
[0062]
[Table 1]

[0063]
【The invention's effect】
As described above, according to the present invention, high molecular weight PPS can be efficiently produced in a short time. Therefore, the method for producing high molecular weight PPS of the present invention is suitable as a method for producing PPS on an industrial scale safely and economically.

Claims (7)

In the method of producing polyphenylene sulfide by reacting an alkali metal sulfide and a dihaloaromatic compound in a temperature range of 200 ° C. or more and less than 290 ° C. in the presence of a polymerization aid in an organic amide solvent, the reaction described above Is a method for producing polyphenylene sulfide characterized in that it is carried out by at least the following steps 1 and 2 , wherein a polymerization assistant is added before the dehydration step before the start of polymerization .
Step 1: In an organic amide solvent, an alkali metal sulfide and a dihaloaromatic compound are reacted in a temperature range of 200 ° C. or higher and lower than 245 ° C. so that the conversion is 30 to 60 mol%. In the step of producing a prepolymer of sulfide and in the step 2: converting the prepolymer into high molecular weight polyphenylene sulfide within a temperature range of 245 ° C. or more and less than 290 ° C., an amount of a polymerization auxiliary in the system is charged A method for producing polyphenylene sulfide, characterized in that 0.33 to 0.70 mol per mol of sulfide. In step 2, water is added to the reaction system so that 1.0 to 2.5 moles of water per mole of the alkali metal sulfide charged is present, and the molar ratio of moisture to the polymerization aid. as polymerization aid amount (mol) / amount of water (mol)] of 0.1 to 0.7, the prepolymer of polyphenylene sulfide of claim 1 Symbol mounting, characterized in that converted to high molecular weight polyphenylene sulfide Production method. The method for producing polyphenylene sulfide according to claim 1 or 2 , wherein the polymerization time T2 (minute) in the step 2 is in the range of 100 minutes to 180 minutes including the temperature rise and temperature drop times. In a method for producing polyphenylene sulfide by reacting an alkali metal sulfide with a dihaloaromatic compound in the presence of a polymerization aid in an organic amide solvent, 0.01 to 0.00 per mol of the charged alkali metal sulfide. The method for producing polyphenylene sulfide according to any one of claims 1 to 3 , wherein the reaction is carried out in a system containing 2 mol of a polymerization stabilizer. Water content of the organic amide solvent in the step 1, according to any one of claims 1 to 4, wherein the charged alkali metal sulfide less than 1 mole per 0.5 to 1.5 moles A method for producing polyphenylene sulfide. The polymerization time T1 (min) of the step 1 is 20 minutes or more and less than 120 minutes including the temperature rising and temperature lowering time. The polyphenylene sulfide according to any one of claims 1 to 5 , Production method. The ratio (T1 / T2) of the polymerization time T1 (minutes) including the temperature increase / decrease time in the step 1 and the polymerization time T2 (minutes) including the temperature increase / decrease time in the step 2 is 0.1 to T2. It is 2.0, The manufacturing method of the polyphenylene sulfide of any one of Claims 1-6 characterized by the above-mentioned.