JPH06256501A - Production of polyphenylene ether resin free from deterioration of color due to long-term heating - Google Patents

Abstract

PURPOSE:To produce a polyphenylene ether resin free from deterioration of color due to long-term heating. CONSTITUTION:An aldehyde compound represented by the formula RACHO (R is hydrogen, an alkyl group, a substituted alkyl group, an allyl group, a substituted allyl group, phenyl group or a substituted phenyl group) or a compound expressed by the formula (CHsO)x. [(x) is an integer of >=2, where CH2O units have a cyclic or non-cyclic structure], is brought into contact with a polyphenylene etherbased resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyphenylene ether resin powder having an excellent color tone. More specifically, the present invention relates to a method for producing a polyphenylene ether-based resin in which deterioration of color tone due to long-term heating is suppressed in a polyphenylene ether-based resin which is repeatedly or repeatedly subjected to heat.

[0002]

2. Description of the Related Art Generally, a polyphenylene ether resin has a formula (3)

[0003]

[Chemical 1]

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each hydrogen, an alkyl group, a substituted alkyl group, a halogen group, a hydrocarbon oxy group, a substituted hydrocarbon oxy group, an alkenyl group,
(Representing a substituted alkenyl group, an allyl group, a substituted allyl group, a phenyl group, and a substituted phenyl group), using a catalyst composed of a combination of a metal salt and various amines for oxidative polymerization. (Japanese Patent Publication Sho 42-3195
JP-B-45-23555, JP-A-64-33
No. 131) is well known.

The polyphenylene ether obtained by oxidative polymerization of such phenols has excellent mechanical properties, electrical properties, heat resistance and the like, and has low water absorption, and has recently attracted attention as a thermoplastic engineering plastic. However, in addition to these advantages, they have the drawbacks that they are susceptible to thermal oxidative deterioration and that the color tone is significantly deteriorated, so there is a problem in that their use is limited for applications that are susceptible to thermal oxidative deterioration. In order to avoid this problem, it has been proposed to use various stabilizers such as amines and organic phosphoric acid compounds.

Apart from this, a method of modifying the polyphenylene ether resin itself has also been proposed. For example, JP-B-49-17679, JP-B-49-48197, JP-B-53-12553 and the like disclose heat treatment by blocking the phenolic hydroxyl group of polyphenylene ether by a method such as esterification or etherification. Proposed improvement of oxidative deterioration.

However, the polyphenylene ether resin modified by these methods is melt-molded, although a film produced by cast molding from a solution in which the polyphenylene ether resin is dissolved in a solvent shows some modification effect. When evaluated with a test piece or film, a sufficient stabilizing effect is not recognized. In addition, JP-A-2-
Japanese Patent Publication No. 276823 discloses a method for improving deterioration due to thermal oxidation by using a 6-chroman ring skeleton as a terminal structure of a polyphenylene ether resin. However, even with such a structure, if the melting operation is repeated, it is still impossible to prevent the deterioration of the color tone due to thermal oxidation deterioration.

[0008]

It is necessary to suppress the thermal oxidative deterioration of the polyphenylene ether resin according to the purpose while maintaining the excellent mechanical properties, electrical properties, heat resistance, etc. of the polyphenylene ether resin. . Basically, it is necessary to suppress long-term thermal oxidative deterioration due to repeated melting operations, and this method must be able to be performed by a simple method.

[0009]

Means for Solving the Problems The present inventors have completed the present invention as a result of extensive studies to achieve the above object. That is,
The present invention provides a polyphenylene ether-based resin in a good solvent, a poor solvent or a mixed solvent of a good solvent and a poor solvent for the polyphenylene ether-based resin in the range of 10 to 220 ° C. with respect to the polyphenylene ether-based resin of 0.01.
A method for producing a polyphenylene ether resin excellent in thermal oxidative deterioration, which comprises subjecting a compound represented by formula (1) or formula (2) in an amount of at least wt% to a contact heat treatment. According to this method, it is possible to easily produce a polyphenylene ether-based resin excellent in thermal oxidative deterioration. Further, the polyphenylene ether resin produced by this method has the following formula (4):

[0010]

[Chemical 2]

(Wherein R _A is hydrogen, an alkyl group, a substituted alkyl group, an allyl group, a substituted allyl group, a phenyl group or a substituted phenyl group. R ₁ , R ₂ and R ₃ are hydrogen and an alkyl group, respectively. A substituted alkyl group, a halogen group, a hydrocarbon oxy group, a substituted hydrocarbon oxy group, an alkenyl group, a substituted alkenyl group, an allyl group, a substituted allyl group, a phenyl group or a substituted phenyl group, and R _B is hydrogen or a phenylene ether unit. Is a polyphenylene ether resin excellent in thermal oxidative deterioration.
The present invention will be described in detail below.

The polyphenylene ether resin in the present invention is defined as containing a phenylene ether unit as its repeating unit and is not particularly limited. The typical one is the general formula (5).

[0013]

[Chemical 3]

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently hydrogen, an alkyl group, a substituted alkyl group, a halogen group, an aryl group, a substituted aryl group, a phenyl group or a substituted phenyl group). It consists of the represented phenylene ether unit. Typical examples of typical homopolymers of polyphenylene ether resins include poly (2,6-dimethyl-1,4-phenylene) ether and poly (2-methyl-ether).
6-ethyl 1,4-phenylene) ether, poly (2,
6-diethyl-1,4-phenylene) ether, poly (2-ethyl-6-n-propyl-1,4-phenylene) ether, poly (2,6-di-n-propyl-1,)
4-phenylene) ether, poly (2-methyl-6-n)
-Butyl-1,4-phenylene) ether, poly (2-
Ethyl-6-isopropyl-1,4-phenylene) ether, poly (2-methyl-6-chloroethyl-1,4-)
Homopolymers such as phenylene) ether, poly (2-methyl-6-hydroxyethyl-1,4-phenylene) ether or poly (2-methyl-6-chloroethyl-1,4-phenylene) ether are mentioned.

The polyphenylene ether copolymer is 2,
Copolymer of 6-dimethylphenol and 2,3,6-trimethylphenol or copolymer of o-cresol or 2,3,6-trimethylphenol and o-
Examples thereof include polyphenylene ether copolymers mainly having a polyphenylene ether structure, such as cresol copolymers. Further, in the polyphenylene ether-based resin of the present invention, as long as it does not violate the gist of the present invention, other various phenylene ether units which have been proposed to be present in the conventional polyphenylene ether resin may be used as a partial structure. You may include it. Examples of those proposed as a partial structure which may coexist in a small amount include JP-A-1-297428 and JP-A-63-3.
The 2- (dialkylaminomethyl) -6-methylphenylene ether unit, the 2- (N-alkyl-N-phenylaminomethyl) -6-methylphenylene ether unit, etc. which are described in the Japanese Patent No. 01222 are mentioned. Further, a polyphenylene ether resin in which a small amount of diphenoquinone or the like is bound in the main chain is also included. Further, for example, JP-A-2-276823 and JP-A-63-10.
8059, and polyphenylene ether modified with a compound having a carbon-carbon double bond, as described in JP-A-59-59724 and the like.

The polyphenylene ether resin used in the present invention has a number average molecular weight of 1,000 to 10 as a molecular weight.
It is preferably 10,000. A more preferred range is from about 6,000-60,000. The number average molecular weight in the present invention is a polystyrene equivalent number average molecular weight determined by gel permeation chromatography using a calibration curve of standard polystyrene. When such a polyphenylene ether resin has such a molecular weight, the effect of the oxidative deterioration of the polyphenylene ether resin by the method of the present invention against thermal oxidation is more remarkable.

In the present invention, such a polyphenylene ether resin is prepared by using a corresponding phenol compound and a catalyst comprising a combination of a metal salt and various amines.
A method of oxidative polymerization (for example, JP-B-42-3195, JP-B-45-23555, and JP-A-64-33).
No. 131, etc.). The solvent used for the polymerization is generally a mixture of a good solvent and a poor solvent for the polyphenylene ether resin, but depending on the ratio of these, it is possible to carry out solution polymerization without precipitation of polyphenylene ether resin particles throughout the polymerization. However, it also becomes a precipitation polymerization in which the polyphenylene ether resin particles are precipitated in the latter stage of the polymerization.

The above polyphenylene ether-based resin is added to the polyphenylene ether-based resin in a good solvent, a poor solvent or a mixed solvent of a good solvent and a poor solvent at a temperature of 10 to 220 ° C. with respect to the polyphenylene ether-based resin.
A contact heating treatment is performed with an amount of the compound represented by formula (1) or formula (2) of 01 wt% or more. In the present invention,
The polyphenylene ether resin can be used both in a solution state and a slurry state. When preparing such a mixture, in the case of precipitation polymerization, the polymerization mixture can be used as it is, or a slurry obtained by subjecting it to a catalyst removal treatment and a by-product removal treatment can be used. In the case of solution polymerization, it is possible to use the polymerization solution as it is after completion of the polymerization, or a solution obtained by subjecting it to catalyst removal and by-product removal.

Further, when the polyphenylene ether-based resin powder or the like is already obtained, it can be dissolved in an organic solvent according to the present invention or dispersed in a slurry form and subjected to a contact heat treatment. . Examples of the good solvent for the polyphenylene ether resin usable in the present invention include aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene, halogenated methylene chloride, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene. Hydrocarbons and nitro compounds such as nitrobenzene can be used, and examples of the poor solvent for the polyphenylene ether resin include water, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol and tert-
Alcohols such as butanol, ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran and diethyl ether, esters such as ethyl acetate,
It is common to use amides such as dimethylformamide, but not limited to these examples. Furthermore, a mixed solvent of these good solvent and poor solvent can be used.

In the present invention, the solvent is basically the solvent alone or a good solvent for the polyphenylene ether resin,
Among the combinations of poor solvents, solvents that are excellent in safety, economy and operability should be used. For example, a mixed solvent of aromatic hydrocarbon and alcohol is preferably used. The concentration of the polyphenylene ether resin in the present invention is preferably 0.1 to 80 wt% in the mixture weight,
Particularly preferably, it is in the range of 5 to 30 wt%.

The reaction mixture may contain the catalyst used for the polymerization, a small amount of the reagent used for the purpose of removing the catalyst and the removal of by-products, and the like. Examples of the compound represented by the formula (1) used in the present invention include formaldehyde, acetaldehyde, propylaldehyde, butyraldehyde, acrolein, benzaldehyde and the like. Examples of the compound represented by the formula (2) include trioxane and polyoxymethylene. Formaldehyde, trioxane and polyoxymethylene are preferably used.

Further, in the present invention, other kinds of polymers may be contained in addition to the polyphenylene ether resin as long as the object of the present invention is not impaired. Examples of the other type polymer include polymers of unsubstituted and substituted vinyl monomers, thermoplastic resins such as polyamide, polysulfone, polyester, polycarbonate, polyarylate and polyimide, and thermosetting resins such as melamine resin.

The temperature for the contact heat treatment depends on the kind of the solvent and the composition of the good solvent and the poor solvent for the polyphenylene ether resin, but is preferably in the range of 10 to 220 ° C. When the heat treatment temperature is lower than 10 ° C., the deterioration of the treated polyphenylene ether resin against thermal oxidation does not change at all compared to before treatment. If the heat treatment temperature is higher than 220 ° C., the deterioration behavior due to thermal oxidation may be worse than that before the treatment. The heat treatment temperature should be appropriately selected so that the desired oxidative deterioration behavior with respect to thermal oxidation is obtained.

The container for heat treatment may be either a closed system or an open system, but it is preferably carried out under stirring, and it is preferred to use a container equipped with a stirring function or a liquid circulation device. It is also possible to use a reactor such as a kneader. Although the time for performing the heat treatment cannot be generally specified depending on the temperature for performing the heat treatment, it is generally several minutes to one hour, and it is meaningless to make it too long.

The atmosphere for the heat treatment is preferably an inert gas atmosphere in terms of safety, but the heat treatment may be performed in the presence of oxygen and air. Generally, nitrogen, argon, helium or the like is used as the inert gas. According to this method of performing heat treatment in this manner, it is possible to easily produce a polyphenylene ether-based resin having excellent resistance to thermal oxidative deterioration, and there are many industrial advantages.

[0026]

EXAMPLES Next, industrially very important poly (2,6-
The present invention will be described more specifically with respect to dimethyl-1,4-phenylene) ether, but the present invention is not limited to these examples. (Preparation of Sample) Polyphenylene ether as a raw material was subjected to oxidative coupling of 2,6-xylenol in the presence of dibutylamine by using xylene and methanol as a solvent according to the method described in JP-A-64-33131. Polymerized and produced, methanol containing ethylenediaminetetraacetic acid tetrasodium salt was added in an amount of about 3 times that of the polyphenylene ether resin, washed at 40 ° C. with warm washing and then filtered to remove the catalyst and by-products. This wet polymer was dispersed in an appropriate amount of a mixed solvent of methanol and xylene to obtain a slurry containing polyphenylene ether resin particles. The solvent composition in this slurry was xylene: methanol = 60: 40 weight ratio. The polyphenylene ether resin concentration in the obtained polyphenylene ether resin slurry was 20 wt%. This polyphenylene ether resin slurry is designated as A.

Next, A was once filtered off, and appropriate amounts of methanol and xylene were added to this wet polymer to prepare a slurry of polyphenylene ether. The solvent composition in this slurry was xylene: methanol = 43: 57 weight ratio. The polyphenylene ether resin concentration in the obtained polyphenylene ether resin slurry was 20 w.
It was t%. This polyphenylene ether resin slurry is designated as B.

Next, B was once filtered off, and appropriate amounts of methanol and xylene were added to this wet polymer to prepare a slurry of polyphenylene ether. The solvent content in this slurry was xylene: methanol = 23: 77 weight ratio. The polyphenylene ether resin concentration in the obtained polyphenylene ether resin slurry was 20 w.
It was t%. This polyphenylene ether resin slurry is designated as C.

The samples A to C were prepared at about 30 ° C.
I went there. Next, C was filtered off and a sample dried under vacuum was prepared. This dried polyphenylene ether resin powder is designated as D. Contact heat treatment with formaldehyde was performed on these samples in the following examples. The measurement was performed under the following conditions.

The ¹ H-nuclear magnetic resonance absorption spectrum is measured with GX-270 manufactured by JEOL Ltd. using CDCl ₃ as a solvent, and tetramethylsilane is used as a reference. The color tone of polyphenylene ether is defined by the color index and measured as follows. 0.5 g of polyphenylene ether compression-molded at 310 ° C. is dissolved in chloroform to make the total amount 10 ml, the absorbance at 480 nm is measured at 25 ° C., and calculated by the following formula. The value of this color index is used as a means for evaluating the degree of thermal oxidation of polyphenylene ether, and the lower the value, the less the coloring of polyphenylene ether due to heating and the better the color tone.

[0031]

[Equation 1]

Here, A ₄₈₀ : Absorbance at ₄₈₀ nm a: Cell length (cm) b: Solution concentration (g / ml) The polyphenylene ether resin treated with formaldehyde was analyzed by ¹ H-nuclear magnetic resonance absorption spectrum analysis. Since a characteristic singlet signal is obtained in the vicinity of 31 ppm, this can be known.

Similar effects can be obtained even when other aldehyde compounds are used.

[0034]

Example 1 1 wt% of the polyphenylene ether slurry A was added to the polyphenylene ether dry weight.
Formaldehyde was added and the mixture was heated at 90 ° C. for 30 minutes while stirring in a 300 ml autoclave. After completion of the heat treatment, the reaction mixture was cooled to room temperature, filtered, and dried under vacuum for 1 hour.

The polyphenylene ether resin was heated at 310 ° C.
When the color index was measured by compression molding with 1., it was 3.1 (first heating). The polyphenylene ether which had been heated for the first time was crushed by a freeze crusher, compression molded again at 310 ° C., and the color index was measured to be 4.8 (second heating). The polyphenylene ether which had been heated for the second time was crushed by a freeze crusher, compression-molded again at 310 ° C., and the color index was measured to be 6.1 (third time heating). The results are shown in Table 1. Further, ¹ H-nuclear magnetic resonance absorption spectrum measurement of these polyphenylene ethers was carried out to confirm whether or not a singlet signal was present at 3.31 ppm. The results are also shown in Table 1.

[0036]

Example 2 1 wt% of the polyphenylene ether slurry B was added to the polyphenylene ether dry weight.
Formaldehyde was added and the mixture was heated at 120 ° C. for 30 minutes while stirring in a 300 ml autoclave. After completion of the heat treatment, the reaction mixture was cooled to room temperature, filtered, and dried under vacuum for 1 hour.

This polyphenylene ether at 310 ° C.
When compression molding was performed and the color index was measured. 3.
It was 0 (first heating). The first heated pot
Grind the rephenylene ether with a freeze grinder and
The color index was measured by compression molding at 310 ° C.
However, it was 4.1 (second heating). Second addition
Crush the heated polyphenylene ether with a freeze crusher
And then compression molded again at 310 ° C to color index
It was found to be 5.2 (the third addition
heat). The results are shown in Table 1. Also these polyphs
Of enylene ether ¹H-nuclear magnetic resonance absorption spectroscopy
The singlet signal at 3.31 ppm.
I confirmed whether it exists. The results are also shown in Table 1.
Indicated.

[0038]

Example 3 1% by weight based on the dry weight of polyphenylene ether was added to the slurry C of polyphenylene ether described above.
Formaldehyde was added and the mixture was heated at 140 ° C. for 30 minutes while stirring in a 300 ml autoclave. After completion of the heat treatment, the reaction mixture was cooled to room temperature, filtered, and dried under vacuum for 1 hour.

This polyphenylene ether was heated at 310 ° C.
When compression molding was performed and the color index was measured, 2.
9 (first heating). The first heated pot
Grind the rephenylene ether with a freeze grinder and
The color index was measured by compression molding at 310 ° C.
However, it was 3.8 (second heating). Second addition
Crush the heated polyphenylene ether with a freeze crusher
And then compression molded again at 310 ° C to color index
The measured value was 4.9 (the third addition
heat). The results are shown in Table 1. Also these polyphs
Of enylene ether ¹H-nuclear magnetic resonance absorption spectroscopy
The singlet signal at 3.31 ppm.
I confirmed whether it exists. The results are also shown in Table 1.
Indicated.

[0040]

Comparative Example 1 Sample D is a polyphenylene ether resin powder obtained without the heat treatment according to the present invention. This polyphenylene ether was compression molded at 310 ° C., and the color index was measured and found to be 3.0 (first heating). The polyphenylene ether that had been heated for the first time was crushed with a freeze crusher, and compression-molded again at 310 ° C to measure the color index.
It was 3.3 (2nd heating). The polyphenylene ether which had been heated for the second time was crushed by a freeze crusher, compression molded again at 310 ° C., and the color index was measured. As a result, it was 19.2 (third time heating). The results are shown in Table 1. Moreover, ¹ H-nuclear magnetic resonance absorption spectrum of these polyphenylene ethers was measured,
It was confirmed whether a singlet signal was present at 3.31 ppm. The results are also shown in Table 1.

[0041]

Example 4 A dry powder of polyphenylene ether of sample D was dissolved in a solvent of toluene / methanol = 90/10 weight ratio to obtain 15 wt% of polyphenylene ether resin.
Solution. 1 wt% of formaldehyde was added to this solution based on the dry weight of polyphenylene ether, and the mixture was stirred with a 300 ml autoclave to prepare 1
Heat treatment was performed at 90 ° C. for 30 minutes. After completion of the heat treatment, the reaction mixture was cooled to room temperature, methanol was added to the reaction mixture to precipitate polyphenylene ether, which was filtered off and dried under vacuum for 1 hour.

This polyphenylene ether resin was added to 310
It was 3.4 when compression-molded at ℃ and the color index was measured (first heating). The polyphenylene ether which had been heated for the first time was crushed by a freeze crusher, compression molded again at 310 ° C., and the color index was measured to be 5.1 (second heating). The polyphenylene ether which had been heated for the second time was crushed by a freeze crusher, compression-molded again at 310 ° C., and the color index was measured and found to be 6.3 (third time heating). The results are shown in Table 1. Further, ¹ H-nuclear magnetic resonance absorption spectrum of these polyphenylene ethers was measured to confirm whether or not a singlet signal was present at 3.31 ppm. The results are also shown in Table 1.

[0043]

[Table 1]

[0044]

According to the present invention, it is possible to provide a polyphenylene ether resin which is extremely stable against thermal deterioration without causing deterioration of color tone due to long-term heating.

Claims (3)

[Claims] 1. A polyphenylene ether resin in a good solvent, a poor solvent or a mixed solvent of a good solvent and a poor solvent for a polyphenylene ether resin, in the range of 10 to 220 ° C., 0.01 to the polyphenylene ether resin.
an amount of not less than 10% by weight of formula (1) or (2) _RA- CHO (1) (wherein _RA is hydrogen, an alkyl group, a substituted alkyl group, an allyl group, a substituted allyl group, a phenyl group or a substituted group) A phenyl group.) Contact with an aldehyde compound represented by (CH ₂ O) _X (2) (wherein x is an integer of 2 or more and the CH ₂ O unit has a cyclized or non-cyclized structure) A method for producing a polyphenylene ether-based resin, which comprises treating. 2. The production method according to claim 1, wherein the aldehyde represented by the formula (1) is formaldehyde. 3. The method for producing a polyphenylene ether resin according to claim 1, wherein the polyphenylene ether resin is poly- (2,6-dimethyl-1,4phenylene) ether.