JPH04248841A - Production of crosslinked polyarylene sulfide - Google Patents

Abstract

PURPOSE:To produce a powdery crosslinked polyarylene sulfide excellent in production efficiency in high yield. CONSTITUTION:A powdery uncrosslinked polyarylene sulfide is compression molded and granulated. The resultant granulated material in which >=50wt.% thereof preferably have >=0.7mm grain diameter and >=0.4g/cm<3> bulk density is then oxidatively crosslinked.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a polyarylene sulfide polymer particularly useful as a molding material, which is obtained by oxidatively crosslinking a polyarylene sulfide polymer produced from an alkali metal sulfide and a polyhaloaromatic compound in the presence of an organic polar solvent. (Polyarylene sulfide polymer is hereinafter referred to as PA
(referred to as S).

0002

[Prior Art] PAS used in engineering plastics, etc., is manufactured by solution polymerization and is further processed to obtain a desired melt flow rate (hereinafter referred to as MFR).
ASTM D-1238-74; 316°C,
It was oxidized and crosslinked to a load of 5 kg (measured in g/10 minutes). This oxidative crosslinking generally proceeds by heating PAS in a solid phase below its melting point or in a molten state above its melting point in an oxygen-containing atmosphere.

[0003] As a method of oxidative crosslinking, US Pat. No. 3,35
No. 4,129, using a forced heated air circulation dryer; US Pat. No. 3,717,620, US Pat.
A method using a container-fixed heating mixer having heavy helical stirring blades, a method using a fluidized bed described in U.S. Pat. There are methods such as using a bed or using a fluidized bed with a built-in bag filter.

[0004] What all of the above methods have in common is that PAS is handled in powder form, which leads to the formation of an adhesion layer on the inner wall of the reactor, which inhibits heat transfer, prolongs the crosslinking time, and causes uneven product properties. Furthermore, dust generation during loading and unloading causes a decrease in recovery rate, productivity, and deterioration of workability.

[0005]

Problems to be Solved by the Invention The present invention solves the problems of heat transfer inhibition due to the formation of an adhesion layer on the inner wall of the reactor, prolongation of crosslinking time and unevenness of product properties, as well as recovery rate due to dust generation during charging and unloading. Crosslinked PAS with improved productivity etc.
The objective is to provide a manufacturing method.

[0006]

[Means for Solving the Problems] In view of the above problems, the present inventors have found that the above problems can be significantly improved by compression molding powdered PAS, granulating it, and then oxidizing and crosslinking it. This discovery led to the completion of the present invention. That is, the present invention relates to a method for producing PAS in which powdered PAS is compressed and granulated and then heated in an oxygen-containing atmosphere to cause oxidative crosslinking.

[0007]

[Constitution] In the present invention, PAS is an alkali metal sulfide,
It is produced by polymerizing a polyhaloaromatic compound in the presence of an organic polar solvent.
No., U.S. Patent No. 3919177, U.S. Patent No. 4415
No. 729, US Pat. No. 4,645,826, and the like.

Alkali metal sulfides used in the production of PAS include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide, and mixtures thereof. Such alkali metal sulfides can be used as hydrates and/or aqueous mixtures or in anhydrous form. Alternatively, an alkali metal sulfide can also be derived by a reaction between an alkali metal hydrosulfide and an alkali metal hydroxide. Note that a small amount of alkali metal hydroxide may be added in order to react with the alkali metal hydrosulfide and alkali metal thiosulfate that normally exist in a small amount in the alkali metal sulfide.

[0009] Polyhaloaromatic compounds are halogenated aromatic compounds having two or more halogen atoms directly bonded to an aromatic nucleus, and specifically include p-dichlorobenzene, m-dichlorobenzene, o-dichlorobenzene,
Trichlorobenzene, tetrachlorobenzene, dichloronaphthalene, trichlornaphthalene, dibromobenzene, tribromobenzene, dibromonaphthalene, diiodobenzene, triiodobenzene, dichlorodiphenylsulfone, dibromodiphenylsulfone, dichlorobenzophenone, dibromobenzophenone , dichlordiphenyl ether, dibromidiphenyl ether, dichlordiphenyl sulfide, dibromidiphenyl sulfide,
Examples include dichlorbiphenyl, dibrombiphenyl, etc. and mixtures thereof. These compounds may be block copolymerized, or a small amount of a polyhaloaromatic compound having three or more halogen substituents in one molecule may be copolymerized in order to increase the viscosity of the polymer due to the branched structure. .

Furthermore, as organic polar solvents, formamide, acetamide, N-methylformamide, N,N-
Dimethylformamide, N,N-dimethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-
Ethyl-2-pyrrolidone, ε-caprolactam, N-methyl-ε-caprolactam, hexamethylphosphoramide, tetramethylurea, N,N-dimethylpropyleneurea, amide of 1,3-dimethyl-2-imidazolidinonic acid Examples include urea and lactams; sulfones such as sulfolane and dimethylsulfolane; nitriles such as benzonitrile; ketones such as methylphenyl ketone; and mixtures thereof.

[0011] The polymerization reaction conditions of the alkali metal sulfide and the polyhaloaromatic compound in the presence of these organic polar solvents are generally at a temperature of 200°C to 330°C, preferably 210°C.
°C to 300 °C, and the pressure should be in a range to maintain the polymerization solvent and the polymerization monomer, the polyhaloaromatic compound, substantially in the liquid phase, typically 1.1 kg/cm
2-200kg/cm2 gauge pressure, preferably 1.1k
The pressure is selected from the range of g/cm2 to 20 kg/cm2 gauge pressure. The reaction time varies depending on temperature and pressure, but is generally in the range of 10 minutes to 72 hours, preferably 1
The range is from 1 hour to 48 hours.

In the present invention, it is necessary to mechanically compression mold uncrosslinked powder PAS in a non-molten state. Although various methods can be used for compression molding and are not particularly limited, a method in which powdered PAS is forced between two rotating press rolls is particularly desirable from the viewpoint of stability in producing a compressed product. For example, by pulverizing the compressed material in the form of a plate, it is possible to obtain a granulated material having a particle size suitable for oxidative crosslinking and subsequent melt extrusion.

Generally, the bulk density of PAS powder containing 30% by weight or more of particles with a diameter of less than 0.7 mm is 0.2 to 0.4 g/
cm3, and when cross-linking by oxidation, regardless of the method used, an adhesion layer is likely to be formed on the inner wall of the reactor and inhibit heat transfer. Further, dust is likely to be generated during charging into the reactor and removal from the reactor, reducing work efficiency. By increasing the particle size and bulk density by compressing and granulating the PAS powder, it is possible to minimize the adhesion to the inner wall of the reactor and the generation of dust. Considering the reactivity and workability during oxidative crosslinking, it is desirable that the uncrosslinked PAS granules contain 50% by weight or more of particles having a particle diameter of 0.7 mm or more. Further, it is desirable that the bulk density is 0.4 g/cm3 or more.

[0014] Even if uncrosslinked PAS granules are crosslinked by oxidation, their shape does not change much. Regarding the workability during the melt extrusion process after crosslinking, the same thing can be said as during oxidative crosslinking, so the PAS granules after crosslinking contain 50% by weight or more of particles with a particle size of 0.7 mm or more. This is desirable. Further, it is desirable that the bulk density is 0.4 g/cm3 or more.

[0015] When compression molding powder PAS,
There is no problem even if partially cross-linked PAS is mixed and carried out as necessary.

[0016]

[Examples] Next, the present invention will be further explained with reference to Examples.

[Synthesis Example] 72.0 kg in 1 m3 autoclave.
110 kg (1420 mol) of 5% sodium bisulfide and 112 kg (1390 mol) of 48.0% sodium hydroxide were charged. After raising the temperature to 90°C, 480 kg of N-methylpyrrolidone was charged under a nitrogen atmosphere, and 200 kg of N-methylpyrrolidone was charged.
The temperature was raised to 0.degree. C. while stirring for about 2 hours, and 26 L of water was distilled off. The reaction system was sealed, 208 kg (1420 mol) of P-dichlorobenzene and 150 kg of N-methylpyrrolidone were added, and the mixture was reacted at 250°C for 2 hours. The internal pressure at the end of polymerization was 9.0 kg/cm2 gauge pressure. After cooling the reaction vessel, the contents were filtered. The solids were boiled and washed with hot water three times, dried at 150℃ for 10 hours, and then
1600, and 140 kg of a pale gray-brown powdery PAS polymer having a bulk density of 0.38 g/cm3 was obtained. This polymer is called Resin A.

[Example 1] In this example, a roll-type compression granulator (roller compactor) was used to perform molding, pulverization, and granulation.

[0019] Resin A obtained in the synthesis example was charged into a hopper with a screw feeder of a roller compactor, the rotation speed of the screw feeder was 100 rpm, the roll compression pressure was 1.7 ton/cm2, and the roll rotation speed was 15 rpm.
After adjusting the screen opening of the granulator to 4.9 mm, granulation was performed. The granulated material recovered through compression, crushing, and sizing has an MFR of 1600 and a bulk density of 0.69.
g/cm3, and 99% by weight of the whole has a particle size of 0.7 m.
It was more than m. This is called granulate A.

Granules A6.5k thus obtained
g was fed to a fluidized bed reactor that had been preheated to 150°C. This heat treatment machine has a jacket with a bag filter and a stirrer inside, and has a tower height of 1.5 m and a tower diameter of 25 cm. Air at 250°C is introduced so that the superficial velocity is 0.35 m/sec and the filtration speed of the bag filter is 0.5 m/min to fluidize the particles, and the internal temperature of the heat treatment machine becomes 250°C. The jacket temperature was controlled as follows. After holding for 4 hours, the granules were taken out. The crosslinked granules have an MFR of 220 and a bulk density of 0.7.
At 3 g/cm3, the shape was almost the same as that of uncrosslinked granules A, and a PAS suitable for engineering plastic molding could be obtained. The recovery rate was 99%, and the scattering rate of particles that passed through the bag filter was 0.1%.

[Example 2] 6.5 kg of granulated material A obtained in the same manner as in Example 1 was charged into a jacket heated paddle dryer reactor having a capacity of 50 L, and stirred while supplying air at a rate of 2 L/min. The jacket temperature was controlled so that the internal temperature was 250°C, and the granules were taken out after being maintained for 5 hours. The crosslinked granules have an MFR of 23
0, the bulk density was 0.74 g/cm3, the shape was almost the same as that of uncrosslinked granules A, and it was possible to obtain a PAS suitable for engineering plastic molding. The recovery rate was 98%.

[Example 3] 6.5 kg of granulated material A obtained in the same manner as in Example 1 was charged into a jacket heating type double cone reactor having a capacity of 50 L, and stirred while supplying air at a rate of 2 L/min. The jacket temperature was controlled so that the internal temperature was 250°C, and the granules were taken out after being maintained for 5 hours. The crosslinked granules have an MFR of 190,
The bulk density is 0.74 g/cm3, and its shape is almost the same as that of uncrosslinked granules A, making it suitable for engineering plastic molding.
I was able to get AS. The recovery rate was 98%.

[Comparative Example 1] Resin A4 obtained in Synthesis Example
．． 0 kg was supplied to the same fluidized bed heat treatment machine as in Example 1, which had been preheated to 150°C. The superficial velocity is 0.35
m/sec, the filtration speed of the bag filter is 0.5 m/m
The particles were fluidized by introducing air at 250°C so that the heat treatment temperature was 250°C, and the jacket temperature was controlled so that the internal temperature of the heat treatment machine was 250°C. After holding for 4 hours, the crosslinked resin was taken out and found to have an MFR of 240 and a bulk density of 0.33 g/cm3. The recovery rate was 99%, and the scattering rate of particles that passed through the bag filter was 0.2%.

[Comparative Example 2] Resin A4 obtained in Synthesis Example.
0 kg was placed in a jacket heating paddle dryer reactor with a capacity of 50 L, and the mixture was stirred while supplying air at a rate of 2 L/min. The jacket temperature was controlled so that the internal temperature was 250°C, and after holding for 6 hours, the crosslinked resin was taken out, and the MFR was 200 and the bulk density was 0.3.
It was 5g/cm3. The recovery rate was 97%.

[Comparative Example 3] Resin A6 obtained in Synthesis Example.
5 kg was charged into a jacket heating type double cone reaction vessel with a capacity of 50 L, and the mixture was stirred while supplying air at a rate of 2 L/min. The jacket temperature was controlled so that the internal temperature was 250°C, and after holding for 6 hours, the crosslinked resin was taken out, and the MFR was 210 and the bulk density was 0.35g.
/cm3. The recovery rate was 96%.

[0026]

[Effect of the invention] When uncrosslinked PAS is compressed and granulated and then crosslinked by oxidation as in the present invention, it is difficult to form an adhesion layer on the inner wall of the reactor compared to when using the conventional method, so heat transfer is inhibited. Therefore, the crosslinking time can be shortened. Furthermore, since less dust is generated, workability such as loading and unloading is improved, and the yield is also excellent. This effect can be observed regardless of the type of reactor.

Claims (5)

[Claims] 1. A method for producing crosslinked polyarylene sulfide, which comprises compression molding and granulating powdered uncrosslinked polyarylene sulfide, followed by oxidative crosslinking. 2. The method for producing crosslinked polyarylene sulfide according to claim 1, wherein the uncrosslinked polyarylene sulfide granules contain 50% by weight or more of particles having a particle size of 0.7 mm or more. 3. The method for producing crosslinked polyarylene sulfide according to claim 1, wherein the bulk density of the uncrosslinked polyarylene sulfide granules is 0.4 g/cm 3 or more. 4. The method for producing crosslinked polyarylene sulfide according to claim 1, wherein the crosslinked polyarylene sulfide granules contain 50% by weight or more of particles having a particle diameter of 0.7 mm or more. 5. The method for producing crosslinked polyarylene sulfide according to claim 1, wherein the bulk density of the crosslinked polyarylene sulfide granules is 0.4 g/cm 3 or more.