JP2953080B2 - Clarification method of polyarylene sulfide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to clarification of a polymer in a process for producing a polyarylene sulfide, and more particularly, to a method for efficiently removing a metallic foreign substance contained in a polymer slurry during a washing process after completion of a polymerization reaction. It relates to a method of removing well.

[0002]

2. Description of the Related Art In the production of polyarylene sulfide, metal-based foreign matter is liable to be mixed in from raw materials and equipment due to the use of highly corrosive raw materials, severe polymerization, and recovery conditions. In order to prevent this, various measures have been taken on the material, such as performing polymerization using expensive titanium or zirconium-based equipment. For example, titanium-based devices such as those disclosed in JP-A-61-23627 and JP-A-2-67322,
Special iron-chromium ferrite alloys as disclosed in JP-A-1-213338 and zirconium-based metal materials as disclosed in JP-A-1-156327 are examples.

[0003] However, it is difficult to completely prevent contamination from raw materials and elution of metals other than iron-based materials.
It is strongly desired to reduce this metallic foreign matter. In general, there is sieving by a vibrating screen or adsorption by a magnet, but this is not sufficient.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for removing metallic foreign matter from polyarylene sulfide having a relatively small particle size by using an expensive material to reduce iron based foreign matter. Rather, it is intended to provide a method of separating the polymer in the washing step.

[0005]

Means for Solving the Problems] clarification process of this invention, full
200 μm in the resulting polyarylene sulfide polymer-containing slurry having an average particle size of 10 μm to 0.5 mm during production of polyarylene sulfide using the lash recovery method
This is a clarification method characterized by continuously separating and removing metal-based foreign matters having a diameter of m to 10 mm without interrupting slurry transportation by utilizing a specific gravity difference in a vertical separation tank.

[0006] Here, polyarylene sulfide, which is obtained by reacting an alkali sulfide and an aromatic polyhalogen compound in a polar pay solvent, the particle size, Ru affected by the recovery process of the polymer. The present invention provides a 10 μm obtained by a so-called flash recovery method in which the solvent is scattered by reducing the pressure of the system from 240 ° C. or higher after completion of the polymerization.
Applies to polymers with an average particle size of ０．５0.5 mm . In the process of gradually cooling the polymerization system to recover the polymer in a granular form, the difference in the sedimentation speed of the foreign matter and the polymer particles in water is not preferable because it is small.

[0007] The polymer after polymerization is washed as an aqueous slurry. In the present invention, a vertical separation tank is installed on the way of transporting the aqueous slurry. With the installation of the tank as shown in FIG. 1, relatively heavy metal-based foreign substances settle down and can be extracted out of the system at any time. The metal-based foreign matter that can be removed has an average particle diameter of 200 μm to 1 μm.
It has a thickness of 0 mm and contains many components such as iron, nickel, chromium, and titanium. In some cases, there is a foreign substance containing silicon oxide as a main component that is mixed in from the outside.
When the slurry transport speed is about 2 to ³ m ³ / hr, the preferable size of the separation tank is about 500 mm in diameter and 2,000 in height.
mm. In addition, a pipe of about 40 mm is usually used for supplying and removing the slurry to and from the separation tank.

The average particle size in the slurry is 10 μm or more.
Sedimentation velocity of 0.5 mm polymer is 0.06-0.1 m
/ Min, but 200 μm to 10 mm for metallic foreign matter
Those having a diameter generally have a sedimentation velocity of 0.12 m / min or more, and a difference in the sedimentation velocity is generated due to a difference in specific gravity. is there. Incidentally, the specific gravity of the polymer is 1.32-1.
39, and the specific gravity of the separable particles is 1.90 or more.

The size and the like of the separation tank are as described above. In particular, the cross-sectional area of the separation tank is set so that the flow velocity in the tank is 0.1 to 0.2 m / min. In addition, by attaching two valves to the bottom, it is possible to extract metal-based foreign matter arbitrarily deposited out of the system without interrupting slurry transportation.

[0010] In order to increase the separation efficiency, the polymer content in the slurry is 30% or less, preferably 5 to 25%. Polymers having an average particle size of less than 10 μm are difficult to manufacture, and large particles having a particle size exceeding 0.5 mm are not preferable because separation from foreign matters becomes difficult.

[0011]

According to the present invention, the following effects are obtained by removing particulate metallic foreign matter. (1) The average value of the mechanical characteristics can be improved and the variation can be reduced. (2) The electrical properties of the molded article are improved.

[0012]

The present invention will now be described in more detail with reference to examples and comparative examples.

Embodiment 1 FIG . Comparative Example 1 Poly p- having a melt flow rate of 160 g / 10 min
In the process of producing phenylene sulfide by the flash recovery method, the analysis values of the polymer before and after the installation of the separation tank shown in FIG. 1 and the physical properties of the biaxially stretched film are shown in Table 1.
Shown in Here, the film was melt-pressed at 320 ° C., quenched and made amorphous, and M. Simultaneously biaxially stretched 3.5 times at 90 ° C. with a film stretcher of Long Co.,
The film was heat-set at 230 ° C. under a fixed length to prepare a film having a thickness of 20 μm. The withstand voltage was measured using an electrode having a diameter of 25 mm and the maximum voltage at which dielectric breakdown occurred.

[0014]

[Table 1]

As can be seen from the results shown in Table 1, the polymer from which the foreign matter was removed in the examples had a low iron content,
Further, it was confirmed that the tensile strength and the variation (difference between the maximum value / minimum value), which are considered to be caused by foreign matters when formed into a film, were small, and that the film was excellent in electric characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a vertical separation tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Slurry supply part 2 Slurry extraction part 3 Foreign matter extraction valve

Continuation of front page (56) References JP-A-61-255933 (JP, A) JP-A-62-232437 (JP, A) JP-A-63-132941 (JP, A) JP-A-63-159404 (JP) JP-A-51-139886 (JP, A) JP-A-3-86287 (JP, A) JP-A-62-294452 (JP, A) JP-A-63-1615 (JP, U) 46-11670 (JP, B1) Handbook of Classification Equipment, edited by Japan Powder Industry Association (Showa 53-5-15), published by Industrial Technology Center Co., Ltd. p. 88-111 (58) Field surveyed (Int.Cl. ⁶ , DB name) C08G 75/00-75/32 C08G 85/00 C08F 6/00-6/28 B03B 5/28-5/46

Claims (1)

(57) [Claims] 1. An average particle size of 10 μm to 0.1 μm in the production of polyarylene sulfide using a flash recovery method .
It is characterized by separating and removing metal-based foreign matter having a diameter of 200 μm to 10 mm in a 5 mm formed polyarylene sulfide polymer-containing slurry continuously by using a specific gravity difference by a vertical separation tank without interrupting slurry transportation. Clarification method of polyarylene sulfide.