JPH0778120B2 - Method for producing polyphenylene oxide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing polyphenylene oxide.
More specifically, by oxidatively polymerizing nuclear-substituted phenols,
It relates to a method for producing good quality polyphenylene oxide.

[Conventional technology]

Polyphenylene oxide obtained by the oxidative polymerization of nuclear-substituted phenol is known to be a useful resin, and in particular, a polymer alloy of it and polystyrene or polyamide has excellent thermal properties, mechanical properties, electrical properties, etc. In recent years, as a molding material, its application to various fields is expanding.

Conventionally, various methods for producing such polyphenylene oxide by oxidatively polymerizing a nuclear-substituted phenol are known,
A method using a catalyst system in which a copper compound, a manganese compound or a cobalt compound is combined with a ligand selected from various amines and bases is general, and there are many proposals relating to these.

[Problems to be Solved by the Invention]

However, the polyphenylene oxide obtained by the method using these catalysts generally has a problem of being colored when heated and melted (heat coloring), and its application range is limited as compared with other colorless engineering plastics such as polycarbonate. There's a problem.

As one of effective means for improving thermal coloring, a method of carrying out polymerization at a low temperature is known.

However, this method has a problem that the lower the temperature due to the large heat of polymerization, the more costly it is to maintain the temperature, and it cannot be said to be a sufficiently satisfactory method.

An object of the present invention is to provide a method for economically and advantageously producing a high-quality polyphenylene oxide with less heat coloring.

[Means for Solving the Problems]

Under these circumstances, the present inventors have conducted intensive studies to achieve the object of the present invention, as a result, when the polymerization temperature is lowered in the latter half of the oxidative polymerization, keep the economic benefit, Moreover, they have found that the thermal coloring is remarkably improved, and completed the present invention.

That is, a nucleus-substituted phenol is selected from at least one selected from i) manganese compounds, ii) hydroxides of group IA metals, alkoxides or phenoxides, and hydroxides or oxides of group IIA metals. Basic compound, ii
In the method for producing polyphenylene oxide by oxidative polymerization with an oxygen-containing gas in an isotropic solvent in the presence of a manganese-based catalyst consisting of i) alkanolamines and iv) amines, the consumption of oxygen requires the consumption of oxygen required for completion of the reaction. After reaching 80 to 100% of the theoretical value, the present invention provides a method for producing polyphenylene oxide, which is characterized in that the reaction is continued at a temperature at least 5 ° C lower than the temperature before the theoretical value.

The nuclear-substituted phenols used in the present invention have the general formula [I] (In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are any one of hydrogen, halogen, a hydrocarbon group, a hydrocarbonoxy group or a substituted hydrocarbonoxy group, and at least one of them. Is hydrogen, and at least one is other than hydrogen.) Specific examples include 2-methylphenol, 3-methylphenol, 2-ethylphenol, and 2-methylphenol. 6-benzylphenol, 2,6-dimethylphenol, 2-methyl-6-ethylphenol, 3-methyl-6-t-butylphenol, 2,6-diallylphenol, 2,6-diphenylphenol, 2,6-dichloro Phenol, 2,6-dibromophenol, 2,6-dimethoxyphenol, 2,3,6-trimethylphenol, 2,4-dimethyl-3-chlorophenol and the like can be mentioned. Preferred substituted phenols are 2,6-
Examples thereof include dimethylphenol and 2,3,6-trimethylphenol. These can be used alone or in combination.

The catalyst of the present invention includes at least one base selected from i) manganese compounds, ii) hydroxides of group IA metals, alkoxides or phenoxides, and hydroxides or oxides of group IIA metals. A manganese-based catalyst composed of a polar compound, iii) alkanolamines, and iv) amines is used.

As the manganese compound, manganese chloride, manganese halide such as manganese bromide, manganese nitrate, manganese sulfate, manganese carbonate, manganese formate, manganese acetate, manganese oxalate, manganese salt of an organic acid or an organic acid such as manganese naphthenate, Examples thereof include manganates such as sodium manganate, potassium permanganate, permanganates such as calcium permanganate, manganese hydroxide, manganese oxide and the like. These may be preferably used in the form of anhydrides or hydrates. Preferred manganese compounds include manganese chloride, manganese bromide, manganese acetate and the like.

One feature of the present invention is that oxidative polymerization proceeds by using an extremely small amount of a manganese compound. In carrying out the present invention, the manganese compound is used in an amount of 0.0001 mol or more, preferably 1 mol or more, per mol of the nuclear-substituted phenols.
It may be used in an amount of 0.0002 mol or more. When the amount used is less than 0.0001 mol per mol of the nuclear-substituted phenols, the oxidative polymerization does not substantially proceed or is extremely slow, which is not preferable. However, there is no particular limitation on the side that uses a large amount.

Examples of the basic compound used in the present invention include periodic tables such as lithium hydroxide, sodium hydroxide and potassium hydroxide.
Group IA metal hydroxides, calcium hydroxide, magnesium hydroxide, etc. Periodic Table IIA group metal hydroxides and their oxides, sodium methoxide, potassium methoxide,
Sodium ethoxide, sodium-n-propoxide, sodium-iso-propoxide, potassium-t-
Examples include alkoxides of Group IA metals of the periodic table such as butoxide, and phenoxides of Group IA metals of the periodic table such as sodium phenoxide and potassium phenoxide. Of these, sodium hydroxide and potassium hydroxide are particularly preferable. These basic compounds are supplied to the reaction system as they are or in the state of being dissolved in a polar solvent such as alcohol.

In carrying out the present invention, the basic compound is used in an amount of 10 to 1,000 mol, preferably 50 to 2 mol, per mol of the manganese compound used.
Used in a proportion of 00 mol. When the amount used is less than 10 mol per mol of the manganese compound, the polymerization rate is extremely slow, and when it is more than 1,000 mol, the effect is the same as the case of less than that and it is uneconomical, which is not preferable.

The alkanolamines used in the present invention have the general formula [II] R ¹ —NH—R ² —OH [II] (wherein R ¹ is hydrogen or a carbon which may have a hydroxyl group as a substituent). An alkanolamine in which the amino group represented by the formula 1-12 alkyl group and R ² represents the alkylene group having 2-12 carbon atoms is a primary or secondary amino group. . Specific examples of R ^{1 in} the formula include hydrogen, methyl group, ethyl group, propyl group, butyl group, 2-
A hydroxyethyl group etc. can be mentioned. Specific examples of R ² include ethylene group, propylene group, butylene group and the like. Specific examples of such alkanolamines include monoethanolamine, N-methylethanolamine, N-ethylethanolamine, iso-propanolamine, iso-butanolamine, diethanolamine and the like. Among these, preferable alkanolamines include monoethanolamine and diethanolamine.

In the present invention, the above-mentioned alkanolamines exert an action of promoting oxidative polymerization in a specific range of use ratio with respect to the nucleus-substituted phenols, and play the role of catalytic action. That is, in the practice of the present invention, the alkanolamines are used per mol of the nuclear-substituted phenols used.
It is used in a proportion of 0.005 to 0.3 mol, preferably 0.01 to 0.1 mol. The usage rate is 0 per mol of the nuclear-substituted phenols.
If less than 005 moles and more than 0.3 moles,
In both cases, a polyphenylene oxide having a practical molecular weight cannot be obtained, which is not preferable.

The amines used in the present invention have the general formula [III] R ⁴ R ₅ NH [III] (wherein R ⁴ and R ⁵ are hydrogen, an alkyl group having 1 to 24 carbon atoms or a carbon number of 7 to 24). Represents an aralkyl group, provided that R ⁴ and
It does not include those in which R ⁵ is both hydrogen, and also include those in which R ⁴ and R ⁵ are joined to form a ring. ) Is a primary or secondary amine. General formula (III)
Examples of amines represented by n-propylamine,
iso-propylamine, n-butylamine, iso-butylamine, sec-butylamine, n-hexylamine, n
-Primary amines such as octylamine, 2-ethylhexylamine, cyclohexylamine, laurylamine, benzylamine, and diethylamine, di-n-propylamine, di-n-butylamine, di-iso-butylamine, di-n- Specific examples include secondary amines such as octylamine, piberidine, and 2-pipecoline.

Particularly preferred amines are di-n-butylamine,
Mention may be made of secondary amines such as piperidine.

When using such amines in the practice of the present invention,
The amount used is based on 1 mol of the normally substituted phenol.
The amount is 0.001 to 0.2 mol, preferably 0.005 to 0.05 mol.

The organic solvent used in the present invention is not particularly limited as long as it is inert to the nuclear-substituted phenols and is liquid at the reaction temperature. Preferred examples include aromatic hydrocarbons such as benzene, toluene and xylene, chain and cyclic aliphatic hydrocarbons such as heptane and cyclohexane, halogenated hydrocarbons such as chlorobenzene, dichlorobenzene and dichloromethane, dioxane and diethyl ether. Ethers such as, ketones such as cyclohexanone and acetophenone, esters such as ethyl acetate and propiolactone, nitriles such as acetonitrile and benzonitrile, methanol, ethanol, n-
Propanol, isopropanol, n-butanol, se
Examples thereof include alcohols such as c-butanol, nitrobenzene, and sulfolane. These are used alone or as a mixture. Preferred organic solvents are mixed solvents of aromatic hydrocarbons and alcohols, and particularly preferred are toluene / methanol, toluene / ethanol, toluene / n-propanol, toluene /
Isopropanol, xylene / methanol, xylene /
A mixed solvent of ethanol, xylene / n-propanol, xylene / isopropanol and the like can be mentioned.

In the practice of the present invention, the organic solvent has a concentration of the nuclear-substituted phenols of 5 to 35% by weight, preferably 10 to 25%.
It is used in a proportion such that it will be weight percent. If the concentration is out of this range, a polyphenylene oxide having a practical molecular weight cannot be obtained, which is not preferable.

The oxygen-containing gas used in the present invention includes oxygen alone or an oxygen-containing gas such as air.

Thus, in carrying out the present invention, the above-mentioned nuclear-substituted phenols, manganese compounds, basic compounds, alkanolamines, amines and solvents are each separately or premixed with some or all of them. After that, it is supplied to the reactor and brought into contact with the oxygen-containing gas under a predetermined pressure. The supply rate of the oxygen-containing gas to the reaction system can be arbitrarily selected in consideration of heat removal, etc., but normally 10 Nml / mole of pure oxygen per mol of the charged nucleus-substituted phenols.
Minutes or more are adopted. It is necessary to bring oxygen into sufficient contact with the reaction mixture, and as a means for this, for example, a conventional gas-liquid contact means such as blowing an oxygen-containing gas into the reaction mixture under strong stirring can be used. . As a reaction system, either a batch system or a flow system can be adopted. The pressure during the reaction can be arbitrarily selected according to the purpose and is not particularly limited, but normal pressure or pressurization up to about 20 atm is preferably selected.

The temperature in the first half of the reaction is selected in such a range that the reaction proceeds smoothly and heat can be removed by ordinary cooling water, and is usually 30 to 100.
C, preferably 30 to 50 ° C. If the polymerization temperature is lower than 30 ° C, the economic benefit is not sufficient, and if it is higher than 100 ° C, smooth polymerization does not proceed, which is not preferable.

The reaction time at the above temperature varies depending on the selected conditions such as the amount of the catalyst, the concentration of the nuclear-substituted phenols or the feed rate of the oxygen-containing gas, but is generally preferably 0.5 to 20 hours.

Then, the consumption of oxygen depends on the theoretical value of oxygen required to complete the reaction.
80-100%, preferably 85-100%, more preferably 85-
After reaching 98%, it should be at least 5 ° C above the previous temperature
Keep at a lower temperature. Preferably, the temperature is kept at least 8 ° C lower than the previous temperature and 10 ° C or higher,
More preferably, the reaction is carried out while maintaining the temperature at least 8 ° C. lower than the temperature before that and 20 ° C. or higher.

If this temperature is not lower than the reaction temperature by 5 ° C. or more, the effect of improving the thermal coloring of the obtained polymer is not remarkable, which is not preferable.

After the oxygen consumption reaches a value lower than 80% of the theoretical value of oxygen required for the completion of the reaction, it is necessary to keep the temperature at least 5 ° C lower than the temperature before that because it is a reaction with a large exotherm in the first half of the reaction. Unfavorable.

In the present invention, the oxygen required for completion of the reaction is 10 of the theoretical value.
Even after reaching 0%, the reaction for increasing the degree of polymerization of the polymer continues, and keeping the temperature at least 5 ° C. lower than the temperature before that makes it possible to obtain a polymer having a high degree of polymerization and a markedly improved thermal coloring. Effective to get.

The reaction time is also appropriately determined in consideration of the reaction amount of oxygen in the first half of the reaction and the degree of polymerization of the produced polymer, but is preferably
About 0.5 to 10 hours is preferable.

After the reaction for a predetermined time, the produced polyphenylene oxide is obtained as a reaction mixture in the form of a solution dissolved in a polymerization solvent, or a reaction mixture in the form of a slurry that is solid and free-dispersed. Various methods can be adopted as a post-treatment method for taking out polyphenylene oxide as a final product from the reaction mixture. For example, after treating the reaction mixture with an acid such as hydrochloric acid or acetic acid to deactivate the catalyst in the system, it is contacted with a non-solvent for polyphenylene oxide such as alcohol, and the resulting slurry is subjected to solid-liquid separation, washing and drying. Method, the reaction mixture is treated with water containing a chelating agent such as EDTA and sodium pyrophosphate and / or a reducing agent such as sodium hydrosulfite, and then separated, and the organic phase is separated from the organic phase. A method of obtaining a water-dispersed slurry by removing the solvent by steam stripping, and subjecting it to solid-liquid separation and dry operation can be mentioned. For solid-liquid separation, a conventional solid-liquid separation means such as a centrifuge, a decanter, or a vacuum filter is used.
For drying, a usual device such as a vacuum dryer, a rotary dryer, a paddle dryer, and a flow dryer can be used.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.
The invention is not limited in scope by these examples.

Incidentally, the reduced viscosity (ηsp / C) of polyphenylene oxide in the examples is such that the concentration of polyphenylene oxide is 0.
It is a value measured at 25 ° C. for a chloroform solution of 5 g / dl. Regarding the degree of heat coloring, the polyphenylene oxide powder was placed in a mold and compression-molded at 250 ° C and 100 kg / cm ² for 10 minutes. The press sheet with a thickness of 1 mm obtained was manufactured by Nippon Denshoku Industries Co., Ltd. The transmitted color was measured with ND-101DP type, and the whiteness (W value) calculated from the obtained values of L, a, and b according to the following equation was evaluated.

Here, the larger the W value, the less the thermal coloring is.

Example 1 3570 g of xylene and 1220 of methanol were placed in a jacketed autoclave with a capacity of 10 L equipped with a stirrer, a thermometer, a condenser, and an air introduction tube reaching the bottom of the autoclave.
g, 2,6-Dimethylphenol 1222 g (10 mol) and sodium hydroxide 32 g (0.8 mol) were charged into a uniform solution, and then monoethanolamine 24.4 g (0.4 mol) and di-n-butylamine were added to the solution. 12.9 g (0.1 mol) and 0.99 g (0.005 mol) of manganese chloride tetrahydrate were added to methanol 10
A solution dissolved in 0 g was added. Then, the contents were vigorously stirred and air was blown into this at a speed of 1 / min. The reaction temperature and pressure were maintained at 35 ° C. and 6 kg / cm ² , respectively. The reaction temperature was brought to 30 ° C. when the oxygen consumption reached 85% of the theoretical value of oxygen required for completion of the reaction. After 12 hours from the start of blowing air, the air supply was stopped and the reaction mixture was thrown into 2250 g of methanol. The precipitated polyphenylene oxide was separated with a centrifuge and
After washing once with g of methanol and separating again, 28 g of sodium pyrophosphate and 19 g of sodium hydrosulfite were dispersed in an aqueous solution dissolved in 4.8 l of water, heated under stirring conditions, and treated at 80 ° C. for 1 hour. . The polyphenylene oxide separated by the centrifuge was washed twice with 5 l of water, then centrifuged and dried under reduced pressure at 150 ° C. overnight. As a result, 1140 g of powdered polyphenylene oxide was obtained.
The polyphenylene oxide obtained here was excellent in quality with little heat coloring. Table 1 shows the reduced viscosity and the W value.

Examples 2 and 3 and Comparative Example 1 Polyphenylene oxide was obtained in the same manner as in Example 1 except that the first half reaction temperature and the second half reaction temperature were changed as shown in Table 1. The reduced viscosity and the W value of the obtained polyphenylene oxide are shown in Table 1.

[Effects of the Invention] According to the present invention described in detail above, particularly in the production of colored resin products, there are advantages such as i) a wide range of color tones to be selected, ii) economical use of a small amount of pigment. An excellent quality polyphenylene oxide with little heat coloring can be obtained economically, and its industrial value is enormous.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ryuhei Matsui 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Petrochemical Co., Ltd. Resin Research Laboratory (72) Inventor Shigeki Kiriyama 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Petrochemical Co., Ltd. (56) Reference JP-A 63-54424 (JP, A) JP-A 56-7024 (JP, A) JP-A 1-236237 (JP, A) JP-A 48-55996 ( JP, A)

Claims (1)

[Claims] 1. A nucleus-substituted phenol is at least selected from i) manganese compounds, ii) hydroxides of group IA metals, alkoxides or phenoxides, and hydroxides or oxides of group IIA metals. One basic compound, ii
In the method for producing polyphenylene oxide by oxidative polymerization with an oxygen-containing gas in an organic solvent in the presence of a manganese-based catalyst consisting of i) alkanolamines and iv) amines, the consumption of oxygen requires the consumption of oxygen to complete the reaction. After reaching 80 to 100% of the theoretical value, a method for producing a polyphenylene oxide, which is characterized in that the reaction is continued at a temperature at least 5 ° C. lower than the temperature before that.