Method of preparing polyarylene sulfide
According to the present invention, an alkali metal salt such as NaCl which is a major by-product of polyarylene sulfide polymerization may be recycled in the dehydration reaction for the preparation of a sulfur source, thereby providing a method of preparing a polyarylene sulfide with a high yield in an economical manner.
1. A method of preparing a polyarylene sulfide, the method comprising:
a first step of preparing a sulfur source including an alkali metal sulfide and a mixed solvent of water and an amide-based compound by dehydrating a product resulting from reaction of an alkali metal hydrosulfide, an alkali metal hydroxide, and an alkali metal salt in a mixed solvent of water and the amide-based compound in the presence of an alkali metal organic acid salt; and
a second step of polymerizing the polyarylene sulfide by adding a dihalogenated aromatic compound and an amide-based compound to a reactor containing the sulfur source,
wherein the alkali metal salt comprises sodium chloride, and wherein an alkali metal salt is produced as a polymerization by-product after the polymerization in the second step, and the alkali metal salt is recovered and recycled and added as the alkali metal salt of the first step.
2. The method of claim 1 , wherein the alkali metal salt is added in an amount of 0.1 to 10 equivalents with respect to 1 equivalent of the sulfur source.
3. The method of claim 1 , wherein water of the first step is added in an amount of 1 to 8 equivalents with respect to 1 equivalent of the amide-based compound.
4. The method of claim 1 , wherein during the reaction of the alkali metal hydrosulfide and the alkali metal hydroxide in the first step, an alkali metal organic acid salt is further introduced in an amount of 0.01 to 1.0 equivalent with respect to 1 equivalent of the alkali metal hydrosulfide.
5. The method of claim 1 , wherein the alkali metal organic acid salt of the first step includes lithium acetate, sodium acetate, or a mixture thereof.
6. The method of claim 1 , wherein the sulfur source of the first step includes water in a molar ratio of 2.5 to 3.5 with respect to 1 mole of sulfur.
7. The method of claim 1 , wherein the dihalogenated aromatic compound includes any one or more selected from the group consisting of o-dihalobenzene, m-dihalobenzene, p-dihalobenzene, dihalotoluene, dihalonaphthalene, dihalobiphenyl, dihalobenzoic acid, dihalodiphenyl ether, dihalodiphenylsulfone, dihalodiphenyl sulfoxide, and dihalodiphenyl ketone.
8. The method of claim 1 , wherein the polyarylene sulfide is produced in a yield of 80% or more, and has a melting temperature (Tm) of 270° C. to 300° C. and a crystallization temperature (Tc) of 180° C. to 250° C.
9. The method of claim 1 , further comprising the step of decreasing the temperature of the reactor containing the sulfur source at a temperature of 150° C. to 200° C., prior to the second step.
10. The method of claim 1 , further comprising the step of cooling the reaction mixture by adding water in an amount of 3 to 5 equivalents with respect to 1 mole of sulfur, after the polymerization reaction of the second step.
11. The method of claim 8 , further comprising the step of washing the reaction mixture with water and an amide-based compound, and then drying the reaction mixture, after the cooling step.