JPH10265574A - Modification of left lithium halide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to convert the subject compound left in a polyarylene sulfide resin into a compound not causing the deterioration in the performances, such as mechanical properties, of the resin by treating the resin containing the compound with a specific amount of an inorganic salt or acid. SOLUTION: (A) A polyarylene sulfide resin e.g. the polymer having repeating units of the formula [R<1> is a 1-6C alkyl, phenyl, amino, a halogen, etc.; (m) is 0-4; (n) is an average polymerization degree of 1.3-30] in an amount of >=70 mol.%} is treated with (B) an inorganic salt [e.g. a salt of an alkali(ne earth) metal except the lithium] or acid (an acid except hydrochloric acid, concretely phosphoric acid or sulfuric acid) reacting with the component A in an A/B theoretical molar ratio of 1/(0.3-2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for modifying residual lithium halide. More specifically, the present invention relates to a method for modifying a lithium halide present as an impurity in a polyarylene sulfide resin into a harmless one which does not cause a decrease in the performance of the polyarylene sulfide resin.

[0002]

2. Description of the Related Art Polyarylene sulfide (hereinafter referred to as PA)
S), especially polyphenylene sulfide (hereinafter sometimes referred to as PPS) resin,
It is known as an engineering plastic having excellent mechanical strength and heat resistance, as well as good electrical properties and high rigidity, and is widely used as various materials such as materials for electronic and electric equipment parts.

[0003] For the production of these resins, a dihalogenation such as p-dichlorobenzene or the like has conventionally been carried out in an aprotic organic solvent such as N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP). A method of reacting an aromatic compound with a sodium salt such as sodium sulfide has been generally used. However, in this case, since the by-produced sodium halide is insoluble in a solvent such as NMP, it is taken into the resin, and it has not been easy to remove it by washing.

Therefore, when polymerization is carried out using a lithium salt instead of a sodium salt to produce lithium halide as a by-product, the lithium halide is soluble in many aprotic organic solvents such as NMP (solvent for polymerization). Therefore, it is possible to reduce the residual lithium concentration in the resin, and the method using this lithium salt has been spotlighted. However, even when polymerization is performed using a lithium salt, the product PA
There is a problem that it remains in the S resin. In particular, product PA
From the viewpoint of increasing the molecular weight of S and reducing the residual monomer by improving the conversion, the Li / S ratio when directly reacting the lithium salt and the sulfur compound tends to be preferably set to a high value, for example, 2 or more. For this reason, there has been caused a problem that the excess lithium tends to remain as impurities in the product PAS.

In order to remove the lithium halide remaining in the product PAS resin as this impurity, it is usually necessary to use NM.
Washing is performed with a solvent such as P. However, as the residual amount of lithium halide increases, the number of times of washing must be increased, which is disadvantageous in terms of process, and also causes a cost increase due to the use of a large amount of solvent. It was also. Further, when lithium halide is present as an impurity in the product PAS resin, when a composite material with glass fiber or the like is manufactured using such PAS resin, poor adhesion between the PAS resin and glass fiber is caused. However, there has been pointed out a problem that the mechanical properties deteriorate.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-described problems, and has been developed in consideration of impurities in a product PAS resin.
In particular, it is an object of the present invention to provide a method for modifying an alkali metal halide compound, particularly lithium halide, and further lithium chloride into another lithium compound which does not cause deterioration of the performance of the PAS resin.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above object can be achieved by using a specific method. The present invention has been made based on such findings. That is, in the present invention, in a polyarylene sulfide resin containing lithium halide, when the theoretical number of moles of inorganic salts or acids reacting with 1 mole of lithium halide present is n, 0.3n
The present invention provides a method for modifying the lithium halide, which is characterized by treating with ~ 2 nmol of an inorganic salt or an acid.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. 1. Polyarylene Sulfide Resin The polyarylene sulfide (PAS) targeted in the present invention is not particularly limited, but specifically has the structural formula -Ar-S- (where Ar is an arylene group)
Is a polymer containing 70 mol% or more of the repeating unit represented by. The typical one is represented by the following structural formula (I)

[0009]

Embedded image

(Wherein R ¹ is an alkyl group having 6 or less carbon atoms, an alkoxy group, a phenyl group, a carboxylic acid / metal salt,
A substituent selected from an amino group, a nitro group, a halogen atom such as fluorine, chlorine, and bromine, and m is an integer of 0 to 4. N is an average degree of polymerization and is in the range of 1.3 to 30), and is a polyphenylene sulfide having a repeating unit represented by at least 70 mol%.

According to the production method, PAS is generally known to have a substantially linear molecular structure having no branched or cross-linked structure and a PAS having a branched or cross-linked structure. It is also effective for Examples of the PAS include homopolymers and copolymers (hereinafter abbreviated as PPS) containing 70 mol% or more, more preferably 80 mol% or more of paraphenylene sulfide units as repeating units. Examples of the copolymerizable structural unit include a metaphenylene sulfide unit, an orthophenylene sulfide unit, a p, p′-diphenylene ketone sulfide unit, a p, p′-diphenylene sulfone sulfide unit, a p, p′-biphenylene sulfide unit, and p , P'-diphenylene ether sulfide unit,
p, p'-diphenylene methylene sulfide unit, p,
p'-diphenylene cumenyl sulfide unit, naphthyl sulfide unit and the like. Further, as the polyarylene sulfide of the present invention, in addition to the substantially linear polymer, a branched or cross-linked polyarylene sulfide polymerized by using a small amount of a monomer having three or more functional groups as a part of the monomer, Further, a blended polymer obtained by blending this with the above-mentioned linear polymer can also be used.

The target PAS resin is, for example, one obtained by subjecting a dihaloaromatic compound and a sulfur source to a polycondensation reaction in an organic polar solvent by a method known per se, and by any production method. It may be something. Examples of objects that can be more effective when the method of the present invention is applied include, for example, lithium hydroxide and a sulfur compound by introducing a liquid or gaseous sulfur compound into an aprotic solvent containing lithium hydroxide. The reaction of lithium hydroxide with sulfur compounds in PAS obtained by introducing dihalogenated aromatic compounds into the reaction solution and conducting polycondensation, followed by separation by centrifugation or filtration. Performed under the condition of Li / S = 2 or more (molar ratio). Originally, the PAS obtained under such conditions was separated from the polycondensation reaction solution by centrifugation or filtration, and then repeatedly washed with an organic solvent, water, or the like to sufficiently remove impurities such as lithium halide. Although it is necessary to perform, in the present invention, it is not necessary to repeatedly wash with an organic solvent, water, or the like by treating the lithium halide as described below and changing the material into a substance that does not cause a decrease in mechanical strength. As a result, the number of times of cleaning can be reduced.

Preferred examples of the PAS resin include, for example, polyphenylene sulfide (hereinafter sometimes referred to as PPS) resin represented by the following structural formula (II).

[0014]

Embedded image

2. Method for modifying lithium halide The present invention relates to a polyarylene sulfide resin containing lithium halide, particularly lithium chloride, wherein n is the theoretical number of moles of an inorganic salt or acid that reacts with 1 mole of lithium halide present. , 0.3 n to 2 nmol of an inorganic salt or acid to modify the contained lithium halide. Method Using Inorganic Salts In the method, the lithium in the lithium halide is exchanged with an alkali metal (eg, sodium, potassium, etc.) or an alkaline earth metal (eg, magnesium, calcium, etc.) other than lithium to obtain, for example, a halogen. It is a method of denaturing to sodium chloride or the like. As inorganic salts,
An alkali metal salt or an alkaline earth metal salt other than lithium is used. Specific examples include carbonates, phosphates, nitrates, and sulfates of alkali metals or alkaline earth metals other than lithium, and sodium phosphate or sodium carbonate is preferably used.

The method comprises the steps of reacting a polyarylene sulfide resin containing lithium halide in a mixed solvent of water / aprotic solvent at 80 to 300 ° C., preferably 200 to 300 ° C.
The reaction can be carried out by reacting with the above-mentioned inorganic salts in the range of -280 ° C. In this case, the ratio of water to the aprotic solvent is water / (water + aprotic solvent) = 4 to
60%, more preferably 10 to 50% is preferably used. Outside this range, the inorganic salts may not be dissolved in the aprotic solvent, and the reaction does not proceed smoothly. Further, when the theoretical number of moles of the inorganic salt reacting with 1 mole of the present lithium halide is n, 0.3
The reaction is carried out using n to 2 nmol of inorganic salts. If the amount is less than 0.3 nmol, modification is not sufficiently performed, and lithium halide remains in the product resin, so that mechanical properties cannot be improved. On the other hand, if it exceeds 2 nmol, an excessive amount of inorganic salts will remain in the product resin, which is not preferable.

As the aprotic solvent, generally, aprotic polar organic compounds (for example, amide compounds,
Lactam compounds, urea compounds, organic sulfur compounds, cyclic organic phosphorus compounds, etc.) can be suitably used,
The aprotic organic solvent can be used alone or as a mixture of two or more kinds, and further mixed with other solvent components which do not disturb the object of the present invention. Among various aprotic organic solvents, preferred is N-
Alkyl caprolactam and N-alkyl pyrrolidone, particularly preferred is N-methyl-2-pyrrolidone.

The removal of the solvent after the reaction is usually carried out by distilling off the solvent by flashing, but it may be carried out by filtration. Method Using Acid In this method, a lithium halide is reacted with an acid other than hydrochloric acid to convert the acid into a lithium salt of the acid. The acid used is not particularly limited as long as it is other than hydrochloric acid, but an acid having low volatility, for example, phosphoric acid or sulfuric acid is preferably used. In these cases, even if the converted lithium phosphate or lithium sulfate is present as an impurity in the product PAS resin, when a composite material with glass fiber or the like is manufactured using such PAS resin, the PAS resin and glass fiber may be mixed. It does not cause poor adhesion and does not cause deterioration of mechanical properties.

The method comprises the steps of reacting a polyarylene sulfide resin containing lithium halide, especially lithium chloride,
Preferably in the same aprotic solvent as described above, 80
The reaction can be carried out by reacting with the above-mentioned acids at a temperature in the range of 300 to 300C, preferably 200 to 280C. Also,
The reaction is carried out using 0.3 n to 2 nmol of inorganic salts, where n is the theoretical number of moles of the acid that reacts with one mole of the lithium halide present. If the ratio is out of the range, the same problem as in the case of the inorganic salts may occur.

The removal of the solvent after the reaction is usually carried out by distilling off the solvent by flashing, but it may be carried out by filtration.

[0021]

The present invention will be described more specifically with reference to the following examples. [Evaluation of physical properties] Samples obtained in Examples and Comparative Examples were
Using a 0 mmφ extruder, the composition was mixed with glass fiber (“03JAFT591” manufactured by Asahi Glass Co., Ltd.) to prepare a composition comprising 60% by weight of polyphenylene sulfide resin and 40% by weight of glass fiber. Further, a sample for evaluating physical properties was prepared using a 50-ton injection molding machine, and mechanical properties were measured in accordance with ASTM D790. [Production Example] [Production of polyphenylene sulfide resin] N-methyl-2-pyrrolidone (3326.4 g, 33.6 m) was placed in a 10-liter stainless steel autoclave equipped with a stirrer and equipped with a stirrer.
ol) and 287.4 g (12 mol) of lithium hydroxide, and the temperature was raised to 130 ° C. After the temperature was raised, hydrogen sulfide was blown into the liquid at 3 liter / minute for 2 hours to synthesize lithium hydrosulfide.

Subsequently, the reaction was carried out under a stream of nitrogen (20
(0 ml / min), and the reacted hydrogen sulfide was partially dehydrogenated. As the temperature rose, water produced as a by-product of the synthesis of lithium sulfide started to evaporate. This by-product water was condensed by a condenser and extracted out of the system. The water was distilled out of the system and the temperature of the reaction solution rose. When the temperature reached 180 ° C., the temperature was stopped and the temperature was kept constant. Retention time 2
Lithium sulfide synthesis was completed in time. After the reaction, lithium sulfide was precipitated in the solvent as a solid.

The slurry was sampled while stirring, and the concentration of lithium sulfide present was measured by the following method. The sulfur concentration was analyzed by an iodometry method, and the lithium concentration was analyzed by an ion chromatogram. The analysis result is S
/Li=0.498 (mol / mol). The autoclave was continuously charged with paradichlorobenzene (PD
CB) 882.0 (6 mol) was charged, the temperature was raised to 220 ° C., and prepolymerization was performed for 2 hours. Thereafter, the polymerization temperature was raised to 260 ° C., and polymerization was performed for 3 hours. After the completion of the polymerization, the reaction product was cooled to 100 ° C. or lower and taken out of the autoclave. The polymer was separated from the reaction using a granular, 60 mesh sieve. [Washing] N-methyl-2-pyrrolidone (3 kg) was added to the granular polyphenylene sulfide (hereinafter sometimes referred to as PPS) obtained by the above polymerization, and washed at 150 ° C. for 1 hour. After filtration, the resultant was dried at 200 ° C. under a vacuum condition all day and night. As a result, 550 g of granular PPS was obtained. After the granular PPS was calcined and incinerated, the amount of residual lithium was measured by an atomic absorption method.
It was 800 ppm. This sample is called "Sample A"
And [Example 1] N550 was added to 550 g of the sample A obtained above.
3 kg of -methyl-2-pyrrolidone and 28 g of trisodium phosphate / 12-hydrate were added, and the mixture was stirred at 150 ° C for 1 hour. Then, a sample was obtained by filtration and vacuum drying.

The results are shown in Table 1.

[0025]

[Table 1]

Example 2 The procedure of Example 1 was repeated, except that the reaction temperature was changed to 260 ° C.
Table 1 shows the results. Example 3 A reactor having a high-viscosity stirrer was charged with 550 g of sample A, 1 kg of N-methyl-2-pyrrolidone and 2.4 g of phosphoric acid, followed by stirring at 260 ° C. for 1 hour. Thereafter, the valve was gradually opened to remove N-methyl-2-pyrrolidone. Further, the pressure was reduced by a vacuum pump and the temperature of the reactor was raised, and N-methyl-2-pyrrolidone was completely removed at 300 ° C. At that time, since the effluent was acidic, it was confirmed that hydrochloric acid had flowed out. The reactor was cooled with stirring to obtain a sample. Table 1 shows the results. [Comparative Example 1] N was added to 550 g of the sample A obtained above.
-Methyl-2-pyrrolidone only 3 kg, 150 ° C
For 1 hour. Then, a sample was obtained by filtration and vacuum drying. Table 1 shows the results.

[0027]

As described above, according to the present invention, it is possible to modify lithium halide present as an impurity in a polyarylene sulfide resin into a harmless one which does not cause a decrease in the performance of the polyarylene sulfide resin. did it.

Claims (1)

[Claims] In a polyarylene sulfide resin containing lithium halide, 0.3 n to 2 nmol of an inorganic salt or acid reacting with 1 mol of the present lithium halide is defined as n. A method for modifying a lithium halide, comprising treating with a salt or an acid.