JPH0665376A - Crosslinking of polyarylene sulfide resin - Google Patents

Abstract

PURPOSE:To markedly shorten the crosslinking time by improving the heat transfer to the resin particles. CONSTITUTION:A process for oxidatively crosslinking a polyarylene sulfide resin by heating in an oxygen atmosphere, which comprises heating the resin in the form of powder and/or particle by heating to a resin temperature in the range of 200-270 deg.C by far-infrared rays.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to oxidative crosslinking of a polyarylene sulfide resin (hereinafter abbreviated as PAS) produced from an alkali metal sulfide and a polyhaloaromatic compound in the presence of an organic polar solvent in an oxygen atmosphere. Relates to a method for cross-linking a polyarylene sulfide resin by heating the resin with far infrared rays.

[0002]

2. Description of the Related Art PAS used in engineering plastics and the like is a PAS produced by solution polymerization, which has a desired melt flow rate (hereinafter referred to as M
It is written as FR. ASTM D-1238-74; measured at 316 ° C., load 5 kg unit g / 10 minutes). This oxidative crosslinking generally proceeds by heating in a solid state or in a molten state at a melting point or higher in an oxygen atmosphere. As a method of oxidative crosslinking, a method of using a forced heating air circulation dryer described in U.S. Pat. No. 3,354,129, U.S. Pat. No. 3,717,620.
US Pat. No. 3,793,256, or a fluidized bed with a built-in bag filter. There are ways to do it. What is common to the above methods is that heated air is used for oxidative crosslinking.

[0003]

However, the heat transfer coefficient in this case is extremely small, it takes an extremely long time to heat the powder layer, and an apparatus having a large heat transfer area is required. Further, it has a drawback that the energy efficiency is extremely low despite supplying a large amount of heat.

An object of the present invention is to provide a novel method for crosslinking PAS which improves the heat transfer to the powder / granular layer and shortens the crosslinking time.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies made by the present inventors in view of such problems, as a result of using a far-infrared heater as a heat source under an oxygen atmosphere when crosslinking uncrosslinked PAS, Was found to be significantly improved, and the present invention has been completed.

That is, in the present invention, when the polyarylene sulfide resin is heated in an oxygen atmosphere for oxidative crosslinking,
A method for crosslinking a polyarylene sulfide resin is characterized in that the resin is heated by far infrared rays in an oxygen atmosphere.

[0007]

The PAS in the present invention is produced by polymerizing an alkali metal sulfide and a polyhaloaromatic compound in the presence of an organic polar solvent, for example, JP-B-45-3368.
U.S. Pat. No. 3,919,177, U.S. Pat. No. 4,645.
It is manufactured by a method such as disclosed in No. 826.

Alkali metal sulfides used in the production of PAS include lithium sulfide, sodium sulfide, rubidium sulfide, cesium sulfide and mixtures thereof. Such alkali metal sulfides can be used as a hydrate and / or an aqueous mixture or in anhydrous form. Alternatively, the alkali metal sulfide can be derived by the reaction of the alkali metal hydrosulfide and the alkali metal hydroxide. It should be noted that a small amount of alkali metal hydroxide may be added in order to react with the alkali metal hydrosulfide or the alkali metal thiosulfate, which are usually present in trace amounts in the 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, o-dichlorobenzene, Trichlorobenzene, tetrachlorobenzene, dichloronaphthalene, dibromobenzene, tribromobenzene, dibromonaphthalene, diiodobenzene, triiodobenzene, dichlorodiphenyl sulfone, dibromodiphenyl sulfone, dichlorobenzophenone, dibromobenzophenone, dichloro Examples thereof include diphenyl ether, dibromodiphenyl ether, dichlorodiphenyl sulfide, dibromodiphenyl sulfide, dichlorobiphenyl, dibromobiphenyl and the like, 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 polymer viscosity 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, ε
-Caprolactam, N-methyl-ε-caprolactam,
Hexamethylphosphoramide, tetramethylurea, N-
Dimethyl propylene urea, 1,3-dimethyl-2-imidazolidinone acid amidourea, and sulfones such as lactams, sulfolane, dimethyl sulfolane, and the like; nitriles such as benzonitrile; ketones such as methyl phenyl ketone and the like, and Mention may be made of mixtures thereof.

In the presence of these organic polar solvents, the polymerization conditions of the above-mentioned alkali metal sulfide and polyhaloaromatic compound are generally at a temperature of 200 to 330 ° C., preferably 210 to 3
The temperature should be 00 ° C., and the pressure should be in a range such that the polymerization solvent and the polyhaloaromatic compound as a polymerization monomer are substantially maintained in a liquid phase, and generally 1.1 kg / cm ² to 2
00 kg / cm ² gauge pressure, preferably 1.1 kg / c
It is selected according to the range of m ^{2 to 20} kg / cm ² gauge pressure. The reaction time varies depending on temperature and pressure, but is generally 10
It is in the range of minutes to 72 hours, preferably in the range of 1 hour to 48 hours. The PAS thus obtained usually takes the form of powder, but in the method of the present invention, in addition to such PAS powder, PAS particles granulated by an extruder or compression molding are also included in the object of oxidative crosslinking.

When far infrared rays are radiated to these objects in an oxygen atmosphere, the PAS itself generates heat, resulting in PA
The temperature of S itself rises, and oxidative crosslinking proceeds.

As the far infrared heater device to be used, a panel type heater, a rod type heater, a lamp type heater or the like can be used, but a rod type heater is preferable for heating PAS uniformly and rapidly.

To oxidize and cross-link PAS with far infrared rays, PAS can be used in the presence of air under the atmosphere of oxygen.
The resin temperature is from 200 to 270 ° C, preferably from 230 to 270 ° C.
It is preferable to control the temperature to be in the range of 250 ° C. The residence time in the far-infrared furnace depends on the viscosity to be finally obtained, but is 5 minutes to 120 minutes, which is extremely shorter than that using conventional heated air. It is considered that this is because far infrared rays are absorbed by the resin itself and the heating of the resin itself is extremely fast.

In order to continuously oxidize and crosslink PAS by the method of the present invention, uncrosslinked PAS in the form of powder or particles is continuously fed into a furnace equipped with a far infrared heater using a vibrating feeder, The resin temperature is 200 to 270 ° C., more preferably 230 to 250 ° C. while staying inside.
If heated to 0, the oxidative crosslinking will proceed continuously and simultaneously. During the oxidative cross-linking, the gas generated from the PAS is a volatile component such as a low boiling point component, which is discharged from the furnace and then used for gas cleaning.

An example of continuously oxidizing and crosslinking PAS by the method of the present invention will be described below with reference to the drawings.

In FIG. 1, the raw material PAS is an intermediate silo 1
And is quantitatively supplied by the supply feeder 2. A vibrating feeder 4 is installed in the far infrared furnace 3, and P
The resin layer of AS is controlled by the vibration motor so as to be in the range of 0.5 cm to 5 cm. When PAS passes through this vibrating feeder, it is heated by far infrared rays,
The temperature of itself is 200 to 270 ° C., more preferably 230.
It is controlled by the far-infrared furnace temperature controller 9 so as to be maintained at ˜250 ° C. The cross-linked PAS is discharged from the inside of the furnace by the discharger 11, then sent to the product silo 6 by pneumatic transportation, and then filled. In order to remove the gas generated in the furnace, the gas is sucked by the exhaust gas blower 7 and processed by the exhaust gas processing scrubber 8.

[0018]

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

Synthesis Example 1 A 1M ³ autoclave was charged with 110 kg (1420 mol) of 72.5% sodium hydrofluoride and 112 kg (1390 mol) of 48.0% sodium hydroxide. 90 ° C
Then, 480 kg of N-methylpyrrolidone was charged under a nitrogen atmosphere, and the temperature was raised to 200 ° C. with stirring for about 2 hours to distill 26 liters of water. The reaction system was closed and 208 kg of P-dichlorobenzene (1
420 mol) 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 the polymerization was 9.0 Kg / cm ² gauge pressure. After cooling the reactor, the contents were filtered off. The solid matter is washed with boiling water three times by boiling, dried at 150 ° C. for 10 hours, and is light grayish brown powdery PAS with a MFR1600 and a bulk density of 0.38 / cm ³ 140 Kg
Got This PAS is called resin A.

[0020] Synthesis Example 2 1M ³ autoclave N- methylpyrrolidone 440K
g, 132 kg (1010 mol) of sodium sulfide 2.7-hydrate, 500 g (12.6 mol) of sodium hydroxide, and 41 kg (50 mol) of anhydrous sodium acetate were charged. In a nitrogen atmosphere, the temperature was raised to 200 ° C. over 2 hours with stirring to distill 26 liters of water. The reaction system was closed, 148 kg (1010 mol) of P-dichlorobenzene and 100 kg of N-methylpyrrolidone were added, and 23
The reaction was carried out at 0 ° C for 1 hour and then at 260 ° C for 2 hours. At the end of the polymerization, the internal pressure was 8.1 Kg / cm ² gauge pressure. The resin was washed in the same manner as in Synthesis Example 1 and then dried to obtain a resin having an MFR of 800. This PAS is referred to as resin B.

Example 1 Resin A of MFR1600 obtained in Synthesis Example 1 was continuously placed in a far infrared furnace so that the PAS layer had a thickness of 3 cm.
It was supplied at 0 g / min. The far infrared heater was adjusted so that the resin temperature was 250 ° C. The residence time in the far infrared furnace was 45 min, and the product was sent from the far infrared furnace outlet to the product silo by pneumatic transportation. Oxidatively cross-linked PAS is MFR18
A PAS suitable for engineering plastic molding of 0 could be obtained.

Example 2 The resin A obtained in Synthesis Example 1 was compression molded and granulated,
Granulated PAS containing 50% by weight or more of particles of 0.7 mm or more was used. This was continuously supplied to the far infrared furnace so that the distance was 3 cm on the vibrating feeder. Resin temperature is 250 ℃
The far-infrared heater was adjusted so that It was sent to the product silo in the same manner as in Example 1 with a residence time of 60 min in the far infrared furnace. The oxidatively cross-linked PAS was MFR184, and a PAS suitable for engineering plastic molding could be obtained.

Example 3 The resin B of MFR800 obtained in Synthesis Example 2 was continuously supplied to the far infrared furnace at 500 g / min so that the PAS layer on the vibrating feeder had a thickness of 3 cm. The far infrared heater was adjusted to a resin temperature of 220 ° C. The residence time in the far infrared furnace was 70 min, and the product was sent to the product silo as in Example 1. The oxidatively cross-linked PAS was MFR145, and a PAS suitable for engineering plastic molding could be obtained.

Example 4 The resin B obtained in Synthesis Example 2 was compression molded and granulated.
-Granulated P containing 50% by weight or more of particles of 7 mm or more
AS. This was continuously supplied to the far infrared furnace so that the distance was 3 cm on the vibration feeder. Resin temperature is 220
Far-infrared rays were adjusted so that the temperature became 0 ° C., and sent to the product silo in the same manner as in Example 1 with a residence time of 70 min in the far-infrared furnace.
The oxidatively cross-linked PAS was obtained with MFR174, which was suitable for engineering plastics molding.

Comparative Example 1 15 kg of the resin A obtained in Synthesis Example 1 was charged into a 50 liter ribbon mixer having an internal stirring type moving layer having a heating jacket. The heat medium temperature was controlled in the range of 265 to 275 ° C so that the resin temperature was 250 ° C. The inside of the ribbon mixer was purged with air and kept under an oxygen atmosphere. Oxidative crosslinking proceeded in the mixer, but MFR
It took 8.5 hours to obtain 185 crosslinked PAS.

The results are summarized in the table below

[0027]

[Table 1]

[0028]

According to the method of the present invention, the heat transfer to PAS in powder or particle form is improved, and the crosslinking time is greatly shortened.

[Brief description of drawings]

FIG. 1 is a flowchart showing an example of a crosslinking method of the present invention.

[Explanation of symbols]

 1 Intermediate silo 2 Feed feeder 3 Far infrared furnace 4 Vibration feeder 5 Temperature control system 6 Product silo 7 Exhaust gas blower 8 Exhaust gas treatment scrubber 9 Far infrared furnace temperature controller 10 Blower blower 11 Discharger

Claims (4)

[Claims] 1. A method for crosslinking a polyarylene sulfide resin, which comprises heating the polyarylene sulfide resin in an oxygen atmosphere with oxidative crosslinking when the resin is heated by far infrared rays in an oxygen atmosphere. 2. The crosslinking method according to claim 1, wherein the resin temperature is in the range of 200 to 270 ° C. 3. The cross-linking method according to claim 2, wherein a powdery and / or particulate polyarylene sulfide resin is used. 4. The cross-linking method according to claim 3, wherein the polyarylene sulfide resin is continuously supplied to a far infrared furnace equipped with a vibration feeder.