JP2002039462A - Liquid feed pipe and method of manufacturing polyallylene sulfide using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and inexpensively manufacture and supply polyallylene sulfide superior in quality. SOLUTION: This method of continuously manufacturing polyallylene sulfide by the polymerization condensation of alkali metal sulfide and a dihalogenated aromatic compound comprises distributing a reactive mixed liquid containing the polyallylene sulfide in a liquid feed pipe which is formed by connecting a pipe inner diameter and an inner ring diameter of a seal material via a pipe joint having the same size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid sending pipe and a method for producing polyarylene sulfide using the same, and more particularly, to a liquid sending pipe having no or very little dead space in which a flowing liquid stays. The present invention relates to a method for continuously and efficiently producing a polyarylene sulfide by flowing a reaction mixture containing the polyarylene sulfide using the method.

[0002]

2. Description of the Related Art Polyarylene sulfide (hereinafter referred to as PA)
It may be abbreviated as S. ) Resins, especially polyphenylene sulfide (PPS) resin, are known as engineering resins having excellent mechanical strength, heat resistance, etc. and particularly high rigidity, and are used for materials of electronic and electric equipment parts and various high-rigidity materials. Useful as In the production of these resins, a dihalogenated aromatic compound such as p-dichlorobenzene and the like have been conventionally used in an aprotic organic solvent such as N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP). A method of reacting with a sodium salt such as sodium sulfide has been generally used. But,
In this case, since the by-produced sodium chloride is insoluble in a solvent such as NMP, it is taken into the resin, and it has not been easy to remove it by washing. In addition, it is extremely difficult with these methods to continuously treat the resulting resin and by-produced sodium chloride at a high temperature.

For this reason, Japanese Patent Application Laid-Open No. Hei 7-207027 proposes a method for continuously producing a PAS resin by performing polymerization using a lithium salt instead of a sodium salt in an NMP solvent. According to this, since lithium chloride is by-produced instead of sodium chloride, this lithium chloride is soluble in many aprotic organic solvents (solvents for polymerization) such as NMP. The reduction can be achieved relatively easily, and the polymer can be continuously processed at a high temperature. However, in order to treat a reaction solution containing a large amount of lithium chloride or the like at a high temperature, a material having heat resistance or corrosion resistance, for example, a stainless steel or a Hastelloy material, or a titanium alloy or the like is used as a material of a pipe or the like. It is desirable to use.

Further, in the above-mentioned method, even if a material having heat resistance and corrosion resistance is employed, the piping can be removed for connection and maintenance at a construction site, and maintenance for troubles such as blockage can be performed. In consideration of the nature, there is a case where it is necessary to increase the number of connecting portions of the pipe in order to divide the pipe into small pieces. Conventionally, for these purposes, a pipe flange connection method, a gray lock, or the like has been generally used as a connection method of a pipe joint. The PAS resin produced by the above-mentioned polymerization reaction is 250
If the temperature is lower than ℃, it is solidified and cannot be transferred by piping.
For this reason, the piping for transferring the PAS resin reaction liquid is a double piping (jacket structure), and the outer pipe is heated by flowing a heating medium. However, such a joint structure of a double pipe has a structure in which a dead space is formed inside the gasket surface of the pipe flange, so that the resin is retained, and as a result, the resin is deteriorated or decomposed. In addition, there is a disadvantage that the decomposed product easily causes a corrosive environment in the gap. Especially P
The AS resin undergoes coloration and deterioration when subjected to a long-term heat history, resulting in deterioration of the quality of the resulting PAS resin, particularly in applications where high quality is required, for example, in the electric and electronic precision fields. Causes serious problems.

[0005]

As described above, in the conventional continuous production method of the PAS resin, the degradation of the polymer is suppressed by improving the structures of the pipes and joints for transferring the reaction solution. In addition, it is required to maintain the soundness of the manufacturing apparatus by devising the structure and material of the joint that does not generate a corrosive environment. Therefore, an object of the present invention is to solve the above-mentioned disadvantages and to provide a continuous production method of a PAS resin capable of efficiently producing a high-quality PAS resin at a low cost.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to achieve the above-mentioned object, and have found that the size of the inner ring diameter of the sealing material used for the joint portion of the pipe is determined by the size of the pipe. It has been found that by matching the inner diameter of the liquid, the occurrence of dead space in the pipe during liquid feeding can be suppressed. The present invention has been completed based on such findings.
That is, the present invention provides a liquid feed pipe connected by a pipe joint in which the inner diameter of the pipe and the inner ring diameter of the seal material are the same. Further, the present invention, when continuously producing polyarylene sulfide by polycondensation of an alkali metal sulfide and a dihalogenated aromatic compound, a reaction mixture containing polyarylene sulfide is passed through the above-mentioned liquid sending pipe. Another object of the present invention is to provide a method for producing polyarylene sulfide, which is characterized by being distributed.

An example of the liquid supply pipe of the present invention will be specifically described with reference to FIG. FIG. 1 is an example of a sectional view of a pipe joint connected to the pipe of the present invention. In the figure, 1 is an inner tube,
2 is an outer tube, 3 is a flange, 4 to 6 are seal materials (gaskets), 4 is an outer ring portion, 5 is a spiral portion, 6 is an inner ring portion, and 7 is a fillet welded portion. The pipe for sending liquid of the present invention may be a single pipe, but a pipe having a double structure (jacket structure) of an inner pipe for sending liquid 1 and an outer pipe 2 for circulating a heat medium provided around the inner pipe 1 for sending liquid. preferable. With such a structure, the liquid flowing through the inner tube can be heated or heated by the heat medium of the outer tube. In particular, when transferring a reaction mixture containing polyarylene sulfide, it is required to keep the inside of the inner tube at a high temperature. Therefore, the above-described double-structured piping is preferable.

In such a pipe having a double structure, the pipe joint has a flange standard adapted to the outer pipe. For this reason, the seal material to be inserted between the flanges usually has the same diameter as the outer tube, but if this is done, the diameter will be larger than the inner tube, so there will be a gap in this part, resulting in dead space. Will happen. Therefore, in the piping of the present invention, in order to eliminate such a dead space, a sealing material (for example, an O-ring) provided with the inner ring portion 6 inside the flange 3 as shown in FIG. 1 is inserted. Here, the size of the inner ring diameter of the sealing material is made to match the inner diameter of the pipe (the inner diameter of the inner pipe 1).

FIG. 2 is a conceptual diagram of the side surface of the sealing material. In FIG. 2A, an inner ring portion 6 having a size matching the inner ring diameter to the inner diameter of the inner tube is formed, and a spiral portion 5 (this portion is crushed by a clamping force and sealed) is formed outside thereof.
FIG. 2B shows a sealing material having a configuration in which an outer ring portion 4 is further formed on the outer side thereof. FIG. 2B shows a configuration in which the width of the outer ring portion 4 is increased, and a spiral portion 5 is formed inside the outer ring portion 4. The diameter of the inner ring is adjusted to the inner diameter of the inner tube.
If a liquid (liquid material) is allowed to flow through a pipe connected using a pipe joint provided with a sealing material having such a configuration, dead space does not occur, so that there is no stagnation of the liquid, and the heating ( Alternatively, it can be transported in a state of being kept warm. In order to enhance the corrosion resistance, it is preferable that a part or the whole of the liquid contact part of the pipe and the pipe joint is made of at least one material selected from stainless steel, Hastelloy alloy, titanium and titanium alloy. Part or all of the material is preferably made of at least one material selected from stainless steel, Hastelloy alloy, titanium and titanium alloy. Further, it is preferable that the pipe joint be airtight to nitrogen gas up to at least 5 MPa and watertight up to at least 7.5 MPa. Although these materials may be different between the pipe and the pipe joint, it is preferable to use the same material and reduce the influence of thermal expansion from the viewpoint of the strength of the pipe and the reduction of dead space. In addition, it is preferable that the pipe joint be uniformly heated by a heating medium jacket, an electric cast heater, or the like depending on use conditions. In the case of the heat medium jacket, the heat medium jacket is covered with the pipe to form a double pipe. If the piping is relatively large, baffles may be provided in the heating medium jacket,
It is preferable to increase the number of flow paths of the heating medium so that the heating medium is uniformly heated.

Next, a method for producing the polyarylene sulfide of the present invention will be described. The production method of the present invention is carried out by flowing a reaction mixture containing polyarylene sulfide through the above-mentioned liquid sending pipe. This polyarylene sulfide is produced by polycondensing an alkali metal sulfide with a dihalogenated aromatic compound. This polycondensation reaction usually proceeds by reacting the above-described alkali metal sulfide with a dihalogenated aromatic compound in an aprotic organic solvent. Here, as the aprotic organic solvent, a solvent conventionally used in the production of polyarylene sulfide, such as N-methyl-2-pyrrolidone, is used. In addition, as this aprotic organic solvent, the above-mentioned N-methyl-2-
In addition to pyrrolidone, various amide compounds, lactam compounds, urea compounds, organic sulfur compounds, cyclic organic phosphorus compounds, and the like can be used alone or as a mixture.

As the alkali metal sulfide, alkali metal compounds such as sodium sulfide, lithium sulfide and potassium sulfide can be mainly used. These may be used alone or in combination of two or more.
Further, alkaline earth sulfides and other sulfur sources may be used in combination. Here, lithium sulfide can be mentioned as the most preferable.

On the other hand, as the dihalogen aromatic compound,
For example, dihalogenbenzenes such as m-dihalobenzene (the same applies hereinafter) and p-dihalobenzene; 2,3-dihalotoluene, 2,5-dihalotoluene, 2,6-dihalotoluene, 3,4-dihalotoluene, 2, 5-dihaloxylene, 1-ethyl-2,5-
Dihalobenzene, 1,2,4,5-tetramethyl-3,
6-dihalobenzene, 1-normalhexyl-2,5-
Dihalogenalkyl-substituted benzenes such as dihalobenzene, 1-cyclohexyl-2,5-dihalobenzene or dihalogencycloalkyl-substituted benzenes; 1-phenyl-2,5-dihalobenzene, 1-benzyl-2,5-
Dihalogenaryl-substituted benzenes such as dihalobenzene and 1-p-toluyl-2,5-dihalobenzene;
Dihalogen biphenyls such as 4'-dihalobiphenyl;
Examples thereof include dihalogen naphthalenes such as 1,4-dihalonaphthalene, 1,6-dihalonaphthalene, and 2,6-dihalonaphthalene. Here, the halogen is generally chlorine or bromine.

The polyarylene sulfide can be obtained by polycondensing the above-mentioned alkali metal sulfide with a dihalogenated aromatic compound in an aprotic organic solvent. The condensation is carried out in a two-stage or three-stage polymerization tank, and the above-described liquid-feeding pipe of the present invention is used as a pipe connecting these polymerization tanks or a pipe from the last polymerization to the extruder. Therefore, a reaction mixture containing polyarylene sulfide, specifically, a melt of polyarylene sulfide or polyarylene sulfide dissolved in an aprotic organic solvent, and optionally unreacted alkali Liquid materials containing metal sulfides and dihalogenated aromatic compounds are in circulation. When the pipe has a double structure, the liquid material flowing through the inner tube is heated (preferably heated to 250 ° C. or more) by the heat medium of the outer tube, so that the polyarylene sulfide in the liquid material is heated. Because it flows smoothly without solidification and the piping joints are devised,
Since there is no dead space in the flow of the inner tube, there is no stagnation, and as a result, the polyarylene sulfide can be transported with high quality without deterioration (coloring, decomposition, gelation, etc.) during transportation. In addition, there is also an advantage that the inside of the pipe is less likely to become a corrosive environment because there is no accumulated matter or decomposed matter. Furthermore, if a part or all of the liquid contact part of the pipe and the pipe joint is formed of a material having corrosion resistance, especially corrosion resistance to a lithium halide compound generated during the reaction, the pipe material is contained in the polyarylene sulfide product. Because it does not elute, a high quality polyarylene sulfide product is obtained. As such a corrosion resistant material, for example,
Stainless steel such as SUS316L, SCS14, and SUS329J4L, Hastelloy alloy, titanium, and titanium alloy are preferable. Particularly, Hastelloy alloy, titanium and titanium alloy are more preferable.

Further, it is desirable that the pipe and the pipe joint used in the manufacturing method of the present invention have heat resistance. Here, having heat resistance means that the airtightness and pressure resistance of the pipe joint exceed the airtightness and pressure required during operation even at high temperatures, and the pipe joint is subjected to the force such as thermal expansion of the material constituting the pipe itself. It says that there is no problem in use. In the case of the method of the present invention for producing a polyarylene sulfide resin, the heat-resistant temperature is 250
It is desirable that the temperature be between -350 ° C. Also, at such high temperatures, the pipe joints (correctly over the entire pipe)
It is preferable that the material has airtightness to nitrogen gas up to at least 5 MPa and watertightness up to at least 7.5 MPa.

[0015]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 (1) Raw material synthesis operation N-methyl-2 was placed in a raw material synthesis tank (1 m ³ ) equipped with a stirring blade.
554 kg of pyrrolidone and lithium hydroxide (LiO
H.1H ₂ O) was charged, and the temperature was raised to 140 ° C., and water contained in the raw material lithium hydroxide was removed by batch distillation. After the completion of this operation, 65 N kiloliter of gaseous hydrogen sulfide was blown while maintaining the temperature at 130 ° C. By this operation, lithium sulfide was synthesized by the following formula. LiOH + H ₂ S → LiSH + H ₂ O Thereafter, the supply of hydrogen sulfide was stopped, and the synthesis tank was again set to 2
The temperature was raised to 05 ° C. With the increase in temperature, water produced as a by-product when hydrogen sulfide was blown was removed by batch distillation, and a reaction represented by the following formula was allowed to proceed. 2LiSH → Li ₂ S + H ₂ S ↑ The temperature of the synthesis tank was lowered to 60 ° C., and 143 kg of p-dichlorobenzene were charged, thereby completing the raw material preparation operation.

(2) Polymerization operation Using the raw material synthesized by the operation of the above (1), the supply amount is 15 k
A polymerization reaction was carried out in a three-stage CSTR (continuous stirred tank reactor) at g / hr to synthesize polyphenylene sulfide. 3
The reaction solution discharged from the bottom of the reaction tank at the stage was led to a stationary tank, and the reaction solution and the polyphenylene sulfide phase were separated.
The polyphenylene sulfide phase extracted from the bottom of the standing tank is a washing solution (a mixture of N-methyl-2-pyrrolidone and water).
And then separated again by a stationary separation tank. This washing operation of polyphenylene sulfide was repeated in two steps, and the washed polyphenylene sulfide phase was led to an extruder with a devolatilization function to remove volatile solvents (mainly N-methyl-2-pyrrolidone), and then cooled with water and pelletized. To obtain a product of polyphenylene sulfide. Product production is about 2
kg / hr. The obtained polyphenylene sulfide was dissolved at a concentration of α-chloronaphthalene of 0.4 g / deciliter, and the viscosity was measured at a temperature of 206 ° C. using an Ubbelohde viscometer. As a result, the intrinsic viscosity (η _inh ) = 0.15 by adjusting the component ratio of the raw material and the like.
The conditions which can be manufactured in the range of 0.31 have been found. In the above-mentioned polymerization operation, everything from the polymerization reaction tank outlet to the extruder inlet was connected by a double-pipe pipe having a jacket structure, and the operating temperature (heat medium temperature of the outer pipe) was 250 to 310 ° C. . In addition, all of the joints connected to these pipes are shown in FIG.
A sealing material (gasket) having an inner ring having the same diameter as the inner diameter of the pipe as shown in FIG. In addition, about 1/3 of the material of the pipe and the joint was Hastelloy C22, and the remaining 2/3 was SUS316L. After one year of operation, when a penetrating inspection (color check inspection) was performed on the welded portion of the pipe joint and the contact surface of the pipe flange gasket, no corrosion such as cracking or pitting was observed at any place.

COMPARATIVE EXAMPLE 1 A seal material (gasket) having no inner ring was used at several places as a seal material of the joint portion in Example 1, and the shape was such that a dead space was formed in the pipe (particularly in the inner pipe). After one year of operation, a penetrating inspection (color check inspection) was performed on the surface of the pipe flange gasket contact surface.
Cracking was observed in the dead space of the S316L flange material. Further, when the metal structure of this portion was observed by a sump inspection method, it was presumed to be stress corrosion cracking from the form of the crack.

Comparative Example 2 A portion of the polyphenylene sulfide was sampled from the bottom of the reaction tank of Example 1, charged into a 1-liter titanium autoclave, and heated at 260 ° C. at the same temperature as the transfer pipe.
A time retention experiment was performed, and the molecular weight was measured by the molecular weight measurement method described above. The η _{inh of} the polyphenylene sulfide taken out of the reaction tank was 0.28, and the η _inh of the polyphenylene sulfide after the residence test for 8 hours was 0.24.
From this, as a result of the retention experiment for 8 hours, it was found that the molecular weight of polyphenylene sulfide was reduced and degradation was caused.

[0019]

The polyarylene sulfide produced by using the pipe of the present invention and the reaction mixture containing the same are less likely to be decomposed and deteriorated by the polymer, and the joint structure which does not generate a corrosive environment can be produced. The soundness of the device can be maintained. As a result, polyarylene sulfide of excellent quality can be efficiently produced and can be supplied at low cost.

[Brief description of the drawings]

FIG. 1 is an example of a sectional view of a pipe joint connected to a pipe of the present invention.

FIG. 2 is a conceptual diagram of a side surface of a sealing material in the pipe joint of the present invention.

[Explanation of symbols]

 1: inner pipe 2: outer pipe 3: flange 4: outer ring part of seal material 5: spiral part of seal material 6: inner ring part of seal material 7: fillet welded part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H016 AD05 AD08 AE01 3H111 AA01 BA03 BA04 BA05 CA16 CB14 CB27 DA08 DA11 DA14 DA23 DB10 DB22 EA20 4J030 BA03 BA49 BB29 BB31 BC08 4J031 CG12 CG25 CG35

Claims (7)

[Claims] 1. A liquid supply pipe connected by a pipe joint having the same inner diameter as the inner diameter of the seal and the inner diameter of the pipe. 2. The piping according to claim 1, wherein the piping has a double structure of an inner tube for sending liquid and an outer tube for flowing a heat medium provided around the inner tube. 3. The pipe according to claim 1, wherein a part or the whole of the liquid contact part of the pipe and the pipe joint is made of at least one material selected from stainless steel, Hastelloy alloy, titanium and titanium alloy. 4. The pipe according to claim 1, wherein a part or the whole of the sealing material is made of at least one material selected from stainless steel, Hastelloy alloy, titanium, and titanium alloy. 5. The pipe joint is gas-tight to nitrogen gas at least up to 5 MPa and at least 7.5M.
The pipe according to any one of claims 1 to 4, which has water tightness up to Pa. 6. A method for producing a polyarylene sulfide continuously by polycondensing an alkali metal sulfide with a dihalogenated aromatic compound, wherein the reaction mixture containing the polyarylene sulfide is mixed with the reaction mixture according to any one of claims 1 to 5. A method for producing polyarylene sulfide, which comprises flowing through a pipe described in Crab. 7. The method according to claim 6, wherein the alkali metal sulfide is lithium sulfide.