JP3173018B2 - Method for producing cross-linked polyarylene sulfide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyarylene sulfide polymer obtained by oxidatively crosslinking a polyarylene sulfide polymer formed from an alkali metal sulfide and a polyhalo aromatic compound in the presence of an organic polar solvent, and particularly useful as a molding material. (Polyarylene sulfide polymer is referred to as PA
S).

[0002]

2. Description of the Related Art A PAS used for engineering plastics or the like is obtained by adding a particulate PAS produced by solution polymerization to a desired melt flow rate (hereinafter referred to as MFR).
(ASTM D-1238-74; measured at 316 ° C., load 5 kg, unit g / 10 min). This oxidative crosslinking generally proceeds by heating the PAS in a solid state or below the melting point or in a melting state above the melting point in an oxygen-containing atmosphere.

[0003] US Pat.
U.S. Pat. No. 3,717,620 discloses a method using a forced-air circulation type dryer described in U.S. Pat.
A method using a fixed vessel heating and mixing apparatus having a double spiral stirring blade, a method using a fluidized bed described in U.S. Pat. No. 3,793,256, and a flow with a cyclone described in JP-A-62-177027. There is a method using a bed or a method using a fluidized bed with a built-in bag filter.

The common feature of the above methods is that PAS is handled in the form of powder, which impedes heat transfer due to the formation of an adhesion layer on the inner wall of the reactor, prolongs the crosslinking time, and causes unevenness in product properties. This leads to a decrease in the recovery rate, productivity and workability due to the generation of dust and the generation of dust at the time of preparation and removal.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to reduce the heat transfer inhibition due to the formation of an adhering layer on the inner wall of the reactor, the extension of the crosslinking time and the occurrence of unevenness in product properties, and the recovery rate due to the generation of dust at the time of charging and discharging. Crosslinked PAS with improved productivity etc.
It is to provide a manufacturing method of.

[0006]

Means for Solving the Problems In view of the above problems, the present inventors have studied and found that the above problems can be remarkably improved if powdery PAS is compression-molded, granulated and then oxidatively crosslinked. The inventors have found that the present invention has been completed. That is, according to the present invention, a powdery PAS is compression-granulated, and the particle size of the PAS is reduced to 0.1.
After forming a granulated material containing 50% by weight or more of particles of 7 mm or more, it is heated and oxidized and crosslinked in an oxygen-containing atmosphere to obtain a bulk density.
Is 0.4 g / cm ³ or more of cross-linked polyarylene sulfate.
The present invention relates to a method for producing a PAS to be a granulated fid .

[0007]

In the present invention, PAS is an alkali metal sulfide,
It is produced by polymerizing a polyhalo aromatic compound in the presence of an organic polar solvent, for example, Japanese Patent Publication No. 45-3368.
No. 3,919,177, U.S. Pat.
No. 729, U.S. Pat. No. 4,645,826 and the like.

[0008] The alkali metal sulfide used in the production of PAS includes 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. Further, the alkali metal sulfide can be derived by a reaction between the alkali metal hydrosulfide and the alkali metal hydroxide. A small amount of alkali metal hydroxide may be added in order to react with a small amount of alkali metal sulfide or alkali metal thiosulfate which is usually present in alkali metal sulfide.

The polyhaloaromatic compound is a halogenated aromatic compound having two or more halogen atoms directly bonded to an aromatic nucleus, and specifically, p-dichlorobenzene, m-dichlorobenzene, o-dichlorobenzene,
Trichlorobenzene, tetrachlorobenzene, dichloronaphthalene, trichloronaphthalene, dibromobenzene, tribromobenzene, dibromonaphthalene, diiodobenzene, triiodobenzene, dichlorodiphenylsulfone, dibromodiphenylsulfone, dichlorobenzophenone, dibromobenzophenone , Dichlorodiphenylether, dibromodiphenylether, dichlorodiphenylsulfide, dibromodiphenylsulfide, dichlorobiphenyl, dibromobiphenyl, and the like, and mixtures thereof. These compounds may be block-copolymerized, or a small amount of a polyhalo-aromatic compound having three or more halogen substituents in one molecule may be used in order to increase the viscosity of the polymer due to the branched structure. .

Further, as the organic polar solvent, 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 urea of 1,3-dimethyl-2-imidazolidinonic acid and lactams; sulfones such as sulfolane and dimethylsulfolane , Nitriles such as benzonitrile;
Examples thereof include ketones such as methylphenyl ketone and the like, and mixtures thereof.

In the presence of these organic polar solvents, the conditions for the polymerization reaction of the alkali metal sulfide and the polyhaloaromatic compound are generally at a temperature of 200 ° C. to 330 ° C., preferably 210 ° C.
° C. is to 300 ° C., the pressure is a polyhalo aromatic compound as a polymerization solvent and polymerization monomers is should be in the range to retain the substantially liquid phase, generally 1.1 kg / cm ² ~
200 kg / cm ² gauge pressure, preferably 1.1 kg / cm ² to 2
It is selected from the range of 0 kg / cm ² gauge pressure. The reaction time varies depending on the temperature and pressure, but generally ranges from 10 minutes to 7 minutes.
It is in the range of 2 hours, preferably in the range of 1 hour to 48 hours.

In the present invention, the uncrosslinked powder PAS must be mechanically compression molded in a non-molten state. Various methods can be used for compression molding, and the method is not particularly limited. However, from the viewpoint of production stability of the compact, a method of pressing the powder PAS between two rotating press rolls is particularly desirable. Then, for example, by crushing the plate-like compressed material, it is possible to obtain a granulated material having a particle size suitable for oxidative crosslinking and subsequent melt extrusion molding.

Generally, the bulk density of a PAS powder containing 30% by weight or more of particles having a diameter of less than 0.7 mm is 0.2 to 0.4 g / cm.
³ , when oxidatively cross-linking, regardless of the method, an adhesion layer is formed on the inner wall of the reactor and heat transfer is easily inhibited. Further, dust is likely to be generated during charging to the reactor and removal from the reactor, which lowers workability. If the particle size and bulk density are increased by compression granulation of the PAS powder, adhesion to the inner wall of the reactor and generation of dust can be minimized. Considering the reactivity and workability at the time of oxidative crosslinking, 5% or more particles having a particle diameter of 0.7 mm
It is desirable that the content be 0% by weight or more. The bulk density is desirably 0.4 g / cm ³ or more.

Oxidative crosslinking of uncrosslinked PAS granules does not significantly change its shape. Regarding the workability in the melt extrusion step after the crosslinking, the same can be said for the oxidative crosslinking, so that the PAS granulated product after the crosslinking contains 50% by weight or more of particles having a particle diameter of 0.7 mm or more. It is desirable.
The bulk density is desirably 0.4 g / cm ³ or more.

[0015] When the powder PAS is compression molded,
There is no problem if a partially cross-linked PAS is mixed as necessary.

[0016]

Next, the present invention will be further described with reference to examples.

[Synthesis Example] In a 1 m ³ autoclave,
110 kg (1420 mol) of 5% sodium hydrosulfide and 112 kg (1390 mol) of 48.0% sodium hydroxide
Was charged. After the temperature was raised to 90 ° C, 480 kg of N-methylpyrrolidone was charged in a nitrogen atmosphere, and the temperature was raised to 200 ° C with stirring over about 2 hours to distill 26 L of water. The reaction system is sealed, and P-dichlorobenzene 20
8 kg (1420 mol) and N-methylpyrrolidone 150
kg was added and reacted at 250 ° C. for 2 hours. The internal pressure at the end of the polymerization was 9.0 kg / cm ² gauge pressure. After cooling the reaction vessel, the contents were separated by filtration. The solid was washed with boiling water three times, dried at 150 ° C. for 10 hours, and dried at 150 ° C. for 10 hours to obtain a light gray brown powdery PAS polymer 1 having an MFR of 1600 and a bulk density of 0.38 g / cm ^3.
40 kg were obtained. This polymer is called resin A.

Example 1 In this example, molding, pulverization and sizing were performed using a roll-type compression granulator (roller compactor).

The 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 / cm ² , the roll rotation speed was 15 rpm, and the granules were sized. After adjusting the screen aperture of the machine to 4.9mm,
Granulation was performed. The granulated product collected through compression, pulverization and sizing had an MFR of 1600 and a bulk density of 0.69 g / cm ³ , and 99% by weight of the whole had a particle size of 0.7 mm or more. This is referred to as granulated material A.

6.5 kg of the granulated material A thus obtained
Was supplied to a fluidized bed reactor preheated to 150 ° C. This heat treatment machine was equipped with a jacket having a bag filter and a stirrer inside, and had a tower height of 1.5 m and a tower diameter of 25 cm. The superficial velocity is 0.35 m / sec, and the filtration speed of the bag filter is 0.5 m / min.
C. air was introduced to fluidize the particles, and the jacket temperature was controlled so that the internal temperature of the heat treatment machine became 250.degree. After holding for 4 hours, the granulated product was taken out. The crosslinked granule has an MFR of 220 and a bulk density of 0.73 g / cm.
^{In 3} , the shape was almost the same as that of the 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 passing through the bag filter was 0.1%.

Example 2 6.5 kg of the granulated product A obtained in the same manner as in Example 1 was charged into a 50 L jacket-heated paddle dryer reactor and stirred while sending 2 L / min of air. The jacket temperature was controlled so that the internal temperature was 250 ° C., and after holding for 5 hours, the granulated product was taken out. The crosslinked granules have an MFR of 230,
With a bulk density of 0.74 g / cm ³ , the shape is almost the same as that of the uncrosslinked granulated material A, and is suitable for engineering plastic molding.
S could be obtained. The recovery rate was 98%.

Example 3 6.5 kg of the granulated product A obtained in the same manner as in Example 1 was charged into a 50 L jacket-heated double cone reactor and stirred while sending 2 L / min of air. The jacket temperature was controlled so that the internal temperature was 250 ° C., and after holding for 5 hours, the granulated product was taken out. The crosslinked granulated product has an MFR of 190, a bulk density of 0.74 g / cm ³ , and has a shape of an uncrosslinked granulated product A.
Thus, a PAS suitable for engineering plastic molding could be obtained. The recovery rate was 98%.

Comparative Example 1 Resin A obtained in Synthesis Example
4.0 kg was supplied to the same fluidized bed heat treatment machine as in Example 1 which had been preheated to 150 ° C. Superficial tower speed 0.35
Introduce air at 250 ° C so that the filtration speed of the bag filter becomes 0.5 m / min, and make the particles fluidize, and control the jacket temperature so that the internal temperature of the heat treatment machine becomes 250 ° C. did. 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 / cm ³ . The recovery rate was 99%, and the scattering rate of particles passing through the bag filter was 0.2%.

[Comparative Example 2] Resin A4.
0 kg was charged into a 50 L jacket-heated paddle dryer reactor with a capacity of 2 L / min, and stirred while sending air. 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. The MFR was 200 and the bulk density was 0.35 g.
/ Cm ³ . The recovery rate was 97%.

Comparative Example 3 Resin A6.
5 kg was charged into a 50 L jacket-heated double cone reactor having a capacity of 2 L / min, and stirred while sending air at 2 L / min. The jacket temperature was controlled so that the internal temperature became 250 ° C., and after holding for 6 hours, the crosslinked resin was taken out. The MFR was 210 and the bulk density was 0.35 g / cm.
^{Was 3} . The recovery was 96%.

[0026]

According to the present invention, when an uncrosslinked PAS is compression-granulated and then oxidatively crosslinked, an adhesion layer to the inner wall of the reactor is less likely to be formed than in the case of using the conventional method, so that heat transfer is inhibited. In addition, the crosslinking time can be reduced. Further, since the generation of dust is small, the workability such as charging and taking out is improved, and the yield is also excellent. This effect can be observed regardless of the type of the reactor.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-13304 (JP, A) JP-A-61-76529 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 3/00-3/28

Claims (3)

(57) [Claims] 1. A powdery uncrosslinked polyarylene sulfide is compression-molded and granulated, and particles having a particle diameter of 0.7 mm or more
After granulation containing 0% by weight or more, oxidative crosslinking is performed ,
Cross-linked polyarylene having a bulk density of 0.4 g / cm ³ or more
A method for producing a cross-linked polyarylene sulfide, which is a granulated sulfide . 2. The method for producing a cross-linked polyarylene sulfide according to claim 1, wherein the bulk density of the uncrosslinked polyarylene sulfide granules is 0.4 g / cm ³ or more. 3. The method for producing a cross-linked polyarylene sulfide according to claim 1, wherein the cross-linked polyarylene sulfide granule contains 50% by weight or more of particles having a particle diameter of 0.7 mm or more.