JPS642625B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method for producing a modified polyarylene sulfide that is stable against heat, ultraviolet rays, etc. [Prior Art] Conventionally, polyarylene sulfide, particularly polyphenylene sulfide, has come to be used as a polymer with excellent heat resistance for coating purposes and molded products. However, these applications take advantage of the tendency of polymers to crosslink when heated in an oxidizing atmosphere, particularly in air. In thin-sheet materials such as films and sheets, if crosslinking or polymer chain cleavage occurs when heated at such high temperatures, or if deterioration occurs under high energy such as ultraviolet rays, the service life will be shortened, which is undesirable. In addition, various studies are being conducted to obtain polymers under high temperature and high energy conditions by modifying polyarylene sulfide or adding additives, but at present, the obtained polymers are not stable. There were some shortcomings, such as not being sufficient. [Object of the Invention] The present invention provides a modified polyarylene sulfide that exhibits little change in molecular weight when placed under high temperature or high energy conditions, reduces coloring and generation of sulfur-based gases, and causes less deterioration of molded products. The aim is to provide methods for manufacturing products. [Structure of the Invention] That is, the present invention provides a polyarylene sulfide whose main component is a structural unit represented by the general formula -(R-S-) (where R represents an aromatic nucleus having 6 or more carbon atoms). On the other hand, the general formula in the molecule

Heterocycle-containing group and/or general formula represented by [Formula] (where X is a group selected from NH, O, and S)

A compound having a hydrazide group represented by the formula [where R and R' are hydrogen, alkyl, and aryl groups] and a halogen or mercapto group and having a molecular weight of 350 or less is 0.05 to 10 Weight % (the above heterocycle-containing group and/or
This is a method for producing a modified polyarylene sulfide, which is characterized by reacting the modified polyarylene sulfide (or in terms of hydrazide group). The polyarylene sulfide in the present invention is
Its main component is the general formula -(R-S-), where R represents an aromatic nucleus having 6 or more carbon atoms. Typical examples of this aromatic nucleus include p-phenylene, m-phenylene, 2,6-naphthalene, 4,4'biphenylene, p,p'bibenzyl, and their nuclear-substituted products. , that is, the general formula

Polyp-phenylene sulfide represented by the structural unit of the formula is most preferred from the viewpoint of moldability, ease of handling, etc. Here, the term "main component" means containing at least 70 mol% of the above-mentioned structural units. If this main component is less than 70 mol%, undesirable results will occur, such as decreased crystallinity of the resulting polymer, low transition temperature, and poor physical properties when molded. If it is less than 30 mol %, it may contain an aromatic nucleus having a trivalent or higher bond, such as a 1,2,4-bonded phenylene nucleus, an aliphatic group, a heteroatom-containing group, etc. A method for producing the polyarylene sulfide of the present invention will be explained. The polymer is produced by a condensation reaction of a dihalogenated aromatic compound and a dithiol aromatic compound or a monohalogenated aromatic thiol, or a desalting condensation reaction of a dihalogenated aromatic compound and an alkali sulfide or an alkali hydrosulfide and an alkali or hydrogen sulfide and an alkali compound. However, the latter method of synthesis from a dihalogen aromatic compound and a sulfur source is preferred.
That is, this is a method of synthesizing polyarylene sulfide by sulfidizing a dihalogenated aromatic compound with a sulfur source in an amide polar solvent. Dihalogenated aromatic compounds used for this purpose include p-dichlorobenzene, p-dibromobenzene, m-dichlorobenzene, 2,6-dichloronaphthalene, 4,4'-dichlorobiphenyl, and p,p'-dichlorobenzene. Among them, p-dichlorobenzene is preferably used. In addition, as a sulfur source, sodium sulfide is used in the case of alkali sulfide, sodium bisulfide and sodium hydroxide are used in the case of a combination of alkali hydrosulfide and an alkali compound, and sodium hydroxide is used as the latter in the case of hydrogen sulfide and an alkali compound. It is preferable. Amide-based polar solvents include N,N dimethylacetamide, N-methylpyrrolidone, N,N'dimethylacetamide, N-methylpyrrolidone, N,
Examples include N'dimethylimidazolidinone, hexamethylphosphoramide, dimethylsulfoxide, and N-methylpyrrolidone is preferred. When water is contained in the sulfur source prior to polymerization, it is preferable to dehydrate the sulfur source, and distillation is convenient as a method for dehydrating. Dihalogenated aromatic compounds (and in some cases copolymerized components) are added to the system that has been dehydrated completely or until it contains a small amount of water.
Polymerization can be carried out by heating to a temperature in the range of 350°C to 350°C, preferably 220 to 300°C. In order to obtain a polyarylene sulfide having a high molecular weight, an auxiliary agent may be present in the polymerization system. Auxiliaries used for these purposes include the general formula R-(COOM) _o (where R
are mainly composed of hydrocarbon groups, M is an alkali metal, and n is an integer of 1 or more), and alkali metal salts of lithium halide sulfonic acids. Examples include lithium acetate, lithium benzoate, sodium acetate, disodium maleate, lithium chloride, and sodium benzenesulfonate. These auxiliaries used during polymerization can be used in an amount of 5 to 200 mol % based on the dihalogenated aromatic compound used. The polymer after polymerization can be isolated by washing with water or an organic solvent. In the present invention, 0.05 to 10
General formula for weight %

[Formula] (where X is a group selected from NH, O, S) or general formula

It is necessary that at least one or both of the compounds containing a hydrazide group represented by the formula: (where R and R' are hydrogen, an alkyl group, and an aryl group) are bonded. When both are bonded, the total amount of the heterocycle-containing group and the hydrazide group in the compound to be bonded needs to be in the range of 0.05 to 10% by weight. First, the heterocycle-containing group will be explained.

In the structure of [Formula], when X is NH, an imidazole ring is formed, when X is O, an oxazole ring is formed, and when X is S, a thiazole ring is formed. If the amount of these groups is less than 0.05% per polymer, the stabilizing effect will be small, and if the amount exceeds 10%, even if a stabilizing effect is obtained, other problems may occur, such as a decrease in the mechanical properties of the molded product or melting. This is not preferable because it causes a decrease in strength. The heterocycle-containing group in the present invention is an essential group.

The phenyl nucleus in this structure may have a substituent, and the C bonded to N and X may have any functional group, but Derivatives of benzimidazole, benzoxazole, benzthiazole are preferred. Furthermore, the heterocycle-containing compound used in the present invention must also have a halogen or mercapto group for reacting with the main chain, side chain, or terminal of the polyarylene sulfide. Compounds with heterocyclic groups having these functional groups include 2-mercaptobenzimidazole, 2-phenyl(2,4-dichlorobenz)oxazole, 2-mercaptobenzthiazole, and 2(p-chlorophenyl).
Examples include benzimidazole. These compounds can be added to the polymer system before, during, late in the polymerization, or just before molding to react during molding, but in order not to significantly alter the essential properties of the polyarylene sulfide, A method in which the compound is added to the polymerization reactor in the latter stage of polymerization to cause the reaction is preferred. Next, a hydrazide group, which is another group included in the present invention, will be explained. The hydrazide group has the general formula

[Formula] (where R and R' are groups selected from hydrogen, alkyl, and aryl groups), and the phenyl nucleus in this structure may have a substituent. Also, any substituent may be bonded to one of the N atoms of the hydrazide, but

〔Effect of the invention〕

The present invention exhibits the following excellent effects by incorporating a heterocycle-containing group and/or a hydrazide group having a specific structure into polyarylene sulfide. That is, when the polymer is heated to high temperatures, the molecular weight changes little, coloring and sulfur-based gas generation can be reduced, and deterioration due to high-energy irradiation such as ultraviolet rays can be reduced. Because it has such excellent characteristics, the polyarylene sulfide of the present invention is particularly useful as a material for molded products that require heat resistance, and provides a polymer that is optimal for thin films and sheets. be able to. In the present invention, the melt viscosity of the polymer was measured using a high-performance flow tester at a shear rate of 200 (seconds) at 300°C.
Measurements were made using a nozzle with a nozzle of 1 mmφ x 10 mm length under ^-1 . The present invention will be explained below with reference to Examples. Example 1, Comparative Example 1 100 moles of sodium sulfide nonahydrate, 45 moles of anhydrous sodium benzoate, and 25 moles of N-methylpyrrolidone were placed in a 100-capacity autoclave and heated with stirring, and the contained water was removed by distillation. did.
The internal temperature was heated to 220°C, and 15.1 kg of water containing a small amount of N-methylpyrrolidone was distilled off. After dehydration, 99 mol of p-dichlorobenzene and 36 g of 1,2,4-trichlorobenzene were added together with 5 kg of N-methylpyrrolidone, and the mixture was heated to 3 kg/kg under nitrogen at 170°C.
After pressurizing to cm ² , the temperature was raised to 260° C. and polymerization was carried out with stirring for 2 hours. After the polymerization was completed, the polymer was cooled and precipitated into distilled water, and the pH was adjusted to 6.5 with hydrochloric acid.
A small block of polymer was collected using a wire mesh with mesh openings. This polymer was repeatedly washed with distilled water under heating and then dried at 120°C under reduced pressure to obtain a white polymer having a melt viscosity of 3500 poise at 300°C. On the other hand, immediately after polymerization was carried out at 260°C for 2 hours, a solution of mercaptobenzimidazole sodium salt in N-methylpyrrolidone containing 5 mol% of p-dichlorobenzene was added to the polymerization system, and the mixture was heated at 250°C for 30
After stirring for a minute, the same post-treatment was performed and the mixture was heated at 300°C.
A white polymer with 4300 poise was obtained. The stability of these two polymers was investigated as shown in Table 1. The content of benzimidazole groups contained in the polymer was 1.5% by weight, calculated from the recovered unreacted mercaptobenzimidazole.

[Table] As is clear from Table 1, the present invention was found to be a stabilized polymer with reduced changes in molecular weight, gas generation, and coloring when heated.

Claims (1)

[Claims] 1. For polyarylene sulfide whose main component is a structural unit represented by the general formula -(R-S-) (where R represents an aromatic nucleus having 6 or more carbon atoms), the molecule and/or a heterocycle-containing group represented by the general formula [Formula] (wherein X is a group selected from ^NH , O, S) and/or a heterocyclic group represented by the general formula 0.05 to 10% by weight of a compound having a hydrazide group (group selected from groups) and a halogen or mercapto group and having a molecular weight of 350 or less (converted to the above heterocycle-containing group and/or hydrazide group)
A method for producing a modified polyarylene sulfide, which comprises reacting the modified polyarylene sulfide.