JP3042640B2 - Method for separating polyarylene sulfide oligomer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating a polyarylene sulfide oligomer from a mixed solution containing the polyarylene sulfide oligomer, and more particularly, to a method for separating polyarylene sulfide granules from a reaction mixture during production of the polyarylene sulfide. The present invention relates to a method for separating a polyarylene sulfide oligomer which is particularly preferably used when a polymer and a by-product NaCl are removed and then a reaction by-product polyarylene sulfide oligomer is separated from the reaction mixture.

[0002]

2. Description of the Related Art Polyarylene sulfide (PAS)
Is generally produced by reacting a dihalogen aromatic compound with an alkali metal sulfide or alkali metal hydrosulfide in a polar solvent such as N-methyl-2-pyrrolidone (NMP). In the production of the above PAS, the synthesized PAS polymer is withdrawn from the reaction tank together with the reaction solvent. Then, the PAS polymer in the reaction mixture containing the reaction solvent, the PAS polymer, and the like is separated from the reaction mixture by sieving or the like, and is made into a product through a washing operation or the like.

On the other hand, the reaction mixture from which the PAS polymer has been removed contains NaCl, PAS oligomers, catalysts and the like as by-products. Among them, NaCl is insoluble in NMP, which is a reaction solvent, and has a relatively large particle size, so that it can be separated by a separation operation using centrifugal force or the like. It is also desired to separate and collect and reuse the PAS oligomer, which is one of the remaining by-products, from the viewpoint of effective utilization of resources.

[0004]

However, PAS oligomers exist in a range from those dissolved in the reaction solvent to insoluble ones depending on the molecular weight, and the PAS oligomers are very fine in particle size. However, there is a problem that separation cannot be performed by a filtration operation or a centrifugation operation.
It is also conceivable to concentrate and remove the oligomer by a solvent evaporation operation.
It is economically disadvantageous in that a loss of P occurs and a special evaporator must be used. On the other hand, if an expensive solid-liquid separator such as a precoat filter is used,
Although only the oligomer insoluble in the reaction solvent can be removed, the filter aid is discharged together with the removed oligomer, so that the oligomer must be discarded as industrial waste and its effective use cannot be achieved.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a separation method capable of easily separating a PAS oligomer from a mixed solution containing the PAS oligomer by ordinary centrifugation. . It should be noted that JP-A-64-33137 and JP-A-63-2157.
No. 28 discloses a method for recovering a PAS oligomer, but all intend to recover the PAS oligomer from a reaction mixture from which only the PAS polymer has been removed, and the recovered PAS oligomer contains a large amount of NaCl. Therefore, it is difficult to reproduce and use it as it is. In addition, there is also a problem that the PAS oligomer cannot be efficiently recovered because the ordinary filtration operation is used for recovering the PAS oligomer.

[0006]

The present inventors have made intensive studies to achieve the above object, and as a result, have found that a mixed solution containing a solvent and a PAS oligomer is soluble in the solvent and the PAS oligomer is soluble in the mixed solvent. It has been found that when water is added as an insoluble liquid, the PAS oligomer precipitates in the form of particles that can be centrifuged, and then this PAS oligomer can be easily separated by ordinary centrifugation. That is, for example, in the production of the aforementioned PAS,
Since the PAS oligomer present as an insoluble component in the reaction solvent after polymerization is in the form of fine particles in the form of primary particles, the separation operation is difficult. However, the PAS oligomer that is soluble in the reaction solvent and insoluble in the PAS oligomer is converted to PAS oligomer. By adding to the reaction mixture from which the polymer and NaCl had been removed, it was found that the PAS oligomer was aggregated and granulated into a secondary particle form having a particle size of about 100 μm, and separation by ordinary centrifugation became possible. .

Therefore, the present invention provides a method for separating a PAS oligomer from a mixed solution containing a solvent and a PAS oligomer, comprising adding a liquid soluble in the solvent and insoluble in the PAS oligomer to the mixed solution. P is used to separate the PAS oligomer from the mixture by centrifugation.
A method for separating an AS oligomer is provided.

Hereinafter, the present invention will be described in more detail. FIG. 1 shows the separation method of the present invention. In the present invention,
First, water as a liquid that is soluble in the solvent and insoluble in the PAS oligomer is added to a mixed solution containing the solvent and the PAS oligomer. In this case, the separation method of the present invention can be applied to any mixed solution in which the PAS oligomer is dissolved and / or dispersed in a solvent. In addition, the separation method of the present invention can be used in the production of PAS.
PAS from the reaction mixture from which the polymer and NaCl have been removed
It is particularly preferably used when separating oligomers. In this case, the separation method of the present invention is effectively used for any reaction mixture obtained by a known method for producing PAS (for example, JP-A-1-246127).

As a method for producing such a PAS, for example, there is a method in which a dihalogen aromatic compound is reacted with an alkali metal sulfide and / or an alkali metal hydrosulfide in a polar solvent. In this case, examples of the type of the dihalogen aromatic compound, the alkali metal sulfide, the alkali metal hydrosulfide, or the polymerization operation thereof include, but are not limited to, those described below. .

(A) Dihalogen aromatic compound As the halogen aromatic compound, for example, dihalobenzenes such as m-dihalobenzene 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-dihalobenzene, 1-cyclohexyl-2, Alkyl-substituted dihalobenzenes such as 5-dihalobenzene or cycloalkyl-substituted dihalobenzenes; 1-phenyl-2,5-
Aryl-substituted dihalobenzenes such as dihalobenzene, 1-benzyl-2,5-dihalobenzene, 1-p-toluyl-2,5-dihalobenzene; dihalobiphenyls such as 4,4'-dihalobiphenyl; 1,4-di Dihalonaphthalenes such as halonaphthalene, 1,6-dihalonaphthalene and 2,6-dihalonaphthalene, 3,5-dihalobenzoic acid, 4,4′-dihalodiphenyl ether, 4,4′-
Dihalodiphenyl ether, 4,4′-dihalodiphenyl ketone, 4,4′-dihalodiphenyl sulfide,
4,4'-dihalodiphenylsulfoxide and the like.

(B) Alkali metal sulfide and alkali metal hydrosulfide Examples of the alkali metal sulfide include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide and cesium sulfide. Examples of the alkali metal hydrosulfide include lithium bisulfide (LiH
S), sodium hydrosulfide (NaHS), potassium hydrosulfide (KHS), rubidium hydrosulfide (RbHS), calcium hydrosulfide (CaHS), and cesium hydrosulfide (CsHS)
And the like.

(C) Polar solvent Examples of the polar solvent include organic amide compounds, lactam compounds, urea compounds, and cyclic organic phosphorus compounds. Specifically, N, N-dimethylformamide, N, N
N-dimethylacetamide, N, N-diethylacetamide, N, N-dipropylacetamide, N, N-dimethylbenzoic acid amide, caprolactam, N-methylcaprolactam, N-ethylcaprolactam, N-isopropylcaprolactam, N-isobutylcaprolactam ,
N-Normalpropylcaprolactam, N-Norbutylbutylcaprolactam, N-cyclohexylcaprolactam, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-isobutyl-2-pyrrolidone, N -Normal propyl-2
-Pyrrolidone, N-n-butyl-2-pyrrolidone,
N-cyclohexyl-2-pyrrolidone, N-methyl-3
-Methyl-2-pyrrolidone, N-cyclohexyl-2-
Pyrrolidone, N-ethyl-3-methyl-2-pyrrolidone, N-methyl-3,4,5-trimethyl-2-pyrrolidone, N-methyl-2-piperidone, N-isopropyl-2-piperidone, N-methyl- 2-piperidone, N-
Ethyl-2-piperidone, N-isopropyl-2-piperidone, N-methyl-6-methyl-2-piperidone, N
-Methyl-3-ethyl-2-piperidone, tetramethylurea, N, N'-dimethylethyleneurea, N, N'-dimethylpropyleneurea, 1-methyl-1-oxosulfolane, 1-ethyl-1-oxosulfolane , 1-phenyl-1-oxosulfolane, 1-methyl-1-oxophosphorane, 1-n-propyl-1-oxophosphorane, 1-phenyl-1-oxophosphorane and the like. The separation method of the present invention can be particularly preferably used when N-alkyllactam or N-alkylpyrrolidone, particularly N-methyl-2-pyrrolidone, is used as the polar solvent.

(D) Polymerization Aid If necessary, for example, lithium chloride is used as a polymerization aid. (E) Polymerization reaction operation In the polymerization reaction, a dihalogen aromatic compound is brought into contact with an alkali metal (water) sulfide in a polar solvent, if necessary, using a polymerization aid to form PAS.

In the present invention, specific examples of the liquid which is soluble in the solvent and in which the PAS oligomer is insoluble (hereinafter referred to as poor solvent) include water, benzene, xylene and the like. It is preferably used because it is advantageous.

The amount of water as a poor solvent to be added to the mixture is preferably 0.1 to 5 weights, more preferably 0.1 to 1 weight, per 1 weight of the mixture. When the amount is less than 0.1% by weight, the effect of separating the PAS oligomer may be insufficient.
The centrifugation operation may be disadvantageous in handling and equipment.

In the present invention, next, a poor solvent is added to a mixed solution containing a solvent and a PAS oligomer, and then the PAS oligomer is separated from the mixed solution (treatment solution) by centrifugation. In this case, the method of centrifugation is not particularly limited, and centrifugation can be performed using a normal arbitrary centrifugal separator.However, when a centrifugal disk type separator or a separator type decanter is used as the centrifugal separator, PAS oligomers can be separated particularly efficiently.

[0017]

EXAMPLES Next, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to the following examples. Polyphenylene sulfide (P
After the production of PS), Examples 1 and 2 were prepared from the reaction mixture.
2. The PPS oligomer was separated as in Comparative Examples 1 and 2 (see FIG. 1).

[Production of PPS] NMP 500 was placed in a reaction vessel.
Liter, 0.83 Kgmol of Na ₂ S · 5H ₂ O and L
After charging 0.83 Kgmol of iCl, the reaction tank temperature was set to 1
Dehydration was performed under the conditions of 30 to 145 ° C., a rectification tower top pressure of 100 Torr, and a dehydration time of 1 to 2 hours. Next, 0.83 Kgm of PDCB (p-dichlorobenzene) was introduced into the reaction vessel.
and polymerized at a reaction temperature of 260 ° C. for 3.0 hours. The obtained reaction mixture was cooled, and only granular PPS polymer was separated from the reaction mixture by a 60-mesh screen. This PPS polymer was made into a product through processes such as washing.

[Separation of PPS Oligomer] NaCl was separated and removed from the reaction mixture from which the PPS polymer had been separated by centrifugation, and then the PPS oligomer was separated by the operations shown in the following Examples and Comparative Examples. Example 1 Water was added as a poor solvent to a reaction mixture from which NaCl had been separated and removed (PPS oligomer concentration: 1.5% by weight) so that water: reaction mixture = 1: 1 (weight ratio). This allows
P in a mixture of water and a reaction mixture (hereinafter referred to as a treatment solution)
The PS oligomer concentration was 0.75% by weight. next,
As a centrifugal separator, a centrifugal disk type separator (LAPX202 manufactured by Alfa Laval) was used, and a centrifugal force of 7500 G (9
Centrifugal separation was performed under operating conditions of 500 rpm), a processing flow rate of 55 l / hr, and a processing temperature of 70 ° C. as a result,
The PPS oligomer recovery was 99.99% by weight.
The concentration of the PPS oligomer in the separated solution after centrifugation was below the detection limit (20 wt ppm). Further, the liquid content of the separated solid [{liquid content / (liquid content + solid content)} × 10
0] was 91.6% by weight.

Example 2 Water was added as a poor solvent to a reaction mixture from which NaCl was separated and removed (PPS oligomer concentration: 1.22% by weight) so that water: reaction mixture = 1: 1 (weight ratio). As a result, the concentration of the PPS oligomer in the processing solution was 0.61% by weight.
It became. Next, using a separation plate type decanter (KVZ-25S-V2 type, manufactured by Mitsubishi Chemical Corporation) as a centrifuge, a centrifugal force of 3000 G (4630 rpm) and a processing flow rate of 460 to 460
Centrifugation was performed under operating conditions of 1290 l / hr and a processing temperature of 90 ° C. As a result, the PPS oligomer recovery was 93.5 to 94.8% by weight. The concentration of the PPS oligomer in the separated solution after centrifugation is 320 to 40.
It was 0 ppm by weight. Further, the liquid content of the separated solid is 5%.
It was 7.1% by weight.

COMPARATIVE EXAMPLE 1 A reaction mixture from which NaCl had been separated and removed (PPS oligomer concentration: 0.71% by weight) was used as it was without adding a poor solvent, and a decanter (KVZ-25S manufactured by Mitsubishi Chemical Corporation) was used as a centrifuge. Centrifugal force 3000
G (4630 rpm), processing flow rate 800 liter / h
r, centrifugation was performed under operating conditions of a processing temperature of 110 ° C. As a result, the PPS oligomer could not be separated.
The PPS oligomer concentration in the separated liquid after centrifugation was 0.71% by weight.

COMPARATIVE EXAMPLE 2 Water was added as a poor solvent to a reaction mixture from which NaCl was separated and removed (PPS oligomer concentration: 1.42% by weight) so that water: reaction mixture = 1: 1 (weight ratio). As a result, the concentration of the PPS oligomer in the processing solution was 0.71% by weight.
It became. Next, filter paper (supplementary particle diameter 0.8
μ), pressure filtration was performed by a leaf test.
The pressure filtration conditions were a filtration pressure of 2 kg / cm ² G and a filtration temperature of 80 to 130 ° C. As a result, the average filtration specific resistance of the filter cake was α _AV = 6.5 × 10 ¹² m / kg, and the filtration operation was difficult.

[0023]

As described above, according to the method for separating a polyarylene sulfide oligomer of the present invention, the polyarylene sulfide oligomer is easily separated from a mixed solution containing the polyarylene sulfide oligomer by ordinary centrifugation. be able to. In this case, since the polyarylene sulfide oligomer separated by the method of the present invention has not undergone thermal degradation or the like, when the method of the present invention is applied to the reaction mixture obtained in the production of polyarylene sulfide, the separated polyarylene sulfide oligomer Can be recycled to the reaction system, and the polyarylene sulfide oligomer can be reused at a high rate for effective use.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a method for separating a polyarylene sulfide oligomer of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 75/00-75/02 C07C 319/26-319/28 C07C 321/24

Claims (3)

(57) [Claims] 1. A reaction mixture obtained by producing a polyarylene sulfide containing a polyarylene sulfide oligomer in the form of primary particles and a solvent, wherein the polyarylene sulfide polymer and NaCl are removed from the reaction mixture. In the method for separating a sulfide oligomer, the NaCl is removed by centrifugation, and water is added at a ratio of 0.1 to 5 weight per 1 weight of the reaction mixture to aggregate the polyarylene sulfide oligomer. A method for separating polyarylene sulfide oligomers, comprising: separating a polyarylene sulfide oligomer in a secondary particle form from the reaction mixture by centrifugation after forming the secondary aryl form. 2. The polyarylene sulfide oligomer is a polyarylene sulfide compound obtained by reacting a dihalogen aromatic compound with an alkali metal sulfide and / or an alkali metal hydrosulfide in a polar solvent, wherein the polyarylene sulfide oligomer is 60 mesh. 2. The method for separating a polyarylene sulfide oligomer according to claim 1, which is a polyarylene sulfide compound other than the polyarylene sulfide polymer separated by the screen. 3. The method for separating a polyarylene sulfide oligomer according to claim 1, wherein the centrifugation is performed using a centrifugal disk type separator or a separator type decanter.