JP6374343B2 - Process for producing polyphenylene ether - Google Patents

Description

  The present invention relates to a method for producing polyphenylene ether.

  Since polyphenylene ether is excellent in electrical insulation, heat resistance, hydrolysis resistance, and flame retardancy, the resin composition containing the polyphenylene ether is used in the fields of home appliances, OA equipment, automobile parts and the like.

  Conventionally, various methods have been disclosed for producing polyphenylene ether by oxidative polymerization of a phenolic compound. For example, in Patent Document 1, a specific catalyst is used for the purpose of efficient removal of water generated by oxidative polymerization of a phenolic compound, the absolute pressure of the reaction system is set to 0.098 MPa or more and less than 0.392 MPa, and oxygen is contained. A method for controlling the oxygen partial pressure of gas to 0.0147 MPa or more and 0.0883 MPa or less is disclosed. Furthermore, in Patent Document 1, the aeration rate of the oxygen-containing gas is set to 0.5 NL / min to 15 NL / min with respect to 1 kg of the reaction mixture. Describes that preferable results can be obtained by relatively increasing the aeration rate.

  On the other hand, in a general method for producing polyphenylene ether, an oxygen-containing gas is passed through the polymerization solution to oxidatively polymerize the phenolic compound. Therefore, at the initial stage of the oxidative polymerization, the volume of the polymerization solution is 10% to 30%. % Foaming occurs. In order to solve this problem, for example, Patent Document 2 discloses an antifoaming agent in a polymerization solution composed of 10 to 25 parts by mass of a phenolic compound, 75 to 90 parts by mass of an aromatic solvent, and 0.1 to 10 parts by mass of a catalyst. A method of suppressing foaming by adding 0.000001 to 0.0001 parts by mass is disclosed.

Japanese Patent Laid-Open No. 2002-3597 JP 2010-270250 A

  However, when adding a defoaming agent to the polymerization solution to cause the polymerization reaction based on the technique described in Patent Document 2, there is a concern that the oxidative polymerization activity is reduced. As described above, the techniques described in Patent Documents 1 and 2 do not sufficiently suppress foaming while maintaining the polymerization activity in the production of polyphenylene ether.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing polyphenylene ether capable of shortening the polymerization time while sufficiently suppressing foaming at the initial stage of oxidative polymerization.

  As a result of diligent research in view of the above object, the present inventors have increased the absolute pressure in the gas phase in the reactor for producing polyphenylene ether. We found that we can suppress. Therefore, the present invention has been completed based on the idea that the absolute pressure is increased to suppress foaming in the early stage of the reaction, and the absolute pressure is decreased in the later stage of the reaction to shorten the time until the completion of the reaction.

That is, the present invention is as follows.
[1]
Polymerization in which oxygen-containing gas (O) is passed through a polymerization solution containing the phenolic compound (M), the aromatic solvent (A), and the catalyst (C) in the reactor to oxidatively polymerize the phenolic compound. Having a process,
The polymerization step is
A first polymerization step in which the absolute pressure in the gas phase portion in the reactor is polymerized by controlling to a first pressure of more than 0.098 MPa and not more than 0.392 MPa;
After the first polymerization step, a second polymerization step in which the absolute pressure is controlled to a second pressure that is smaller than the first pressure and is 0.098 MPa or more and less than 0.392 MPa,
A process for producing polyphenylene ether, comprising:
[2]
The method for producing polyphenylene ether according to [1], wherein the second pressure is less than 90% of the first pressure.
[3]
When the total of the phenolic compound (M) and the aromatic solvent (A) is 100 parts by mass, the polymerization solution is 10 to 25 parts by mass of the phenolic compound (M) and the aromatic solvent (A) 75. The method for producing a polyphenylene ether according to [1] or [2], comprising -90 parts by mass and 0.1-10 parts by mass of the catalyst (C).
[4]
The phenolic compound (M) according to any one of [1] to [3], including 2,6-dimethylphenol or a mixture of 2,6-dimethylphenol and 2,3,6-trimethylphenol. Of producing polyphenylene ether.
[5]
The method for producing polyphenylene ether according to any one of [1] to [4], wherein the aromatic solvent (A) includes at least one selected from the group consisting of toluene, xylene, and ethylbenzene.
[6]
[1] to [5], wherein the catalyst (C) contains a copper compound, a bromine compound, a diamine compound, a tertiary monoamine compound, and one or more selected from the group consisting of a secondary monoamine compound. The manufacturing method of the polyphenylene ether in any one.
[7]
The method for producing polyphenylene ether according to any one of [1] to [6], wherein the oxygen concentration of the oxygen-containing gas (O) is 5 to 25% by volume.
[8]
The polyphenylene ether according to any one of [1] to [7], wherein the oxygen-containing gas (O) contains oxygen and nitrogen, and the oxygen concentration of the oxygen-containing gas (O) is 8 to 12% by volume. Production method.
[9]
The method for producing polyphenylene ether according to any one of [1] to [8], wherein an oxygen partial pressure of the oxygen-containing gas (O) is 0.0147 MPa or more and 0.0883 MPa or less.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of polyphenylene ether which can shorten superposition | polymerization time can be implement | achieved, fully suppressing the foaming of the oxidative polymerization initial stage.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist.

[Production method of polyphenylene ether]
In the method for producing polyphenylene ether of this embodiment, an oxygen-containing gas (O) is passed through a polymerization solution containing a phenolic compound (M), an aromatic solvent (A), and a catalyst (C) in a reactor. And a polymerization step of oxidatively polymerizing the phenolic compound. Furthermore, in the method for producing polyphenylene ether of the present embodiment, the polymerization step is a first polymerization in which the absolute pressure in the gas phase part in the reactor is controlled to a first pressure of more than 0.098 MPa and not more than 0.392 MPa. And after the first polymerization step, the second pressure is polymerized by controlling the absolute pressure to a second pressure that is smaller than the first pressure and less than or equal to 0.098 MPa and less than 0.392 MPa. A polymerization step. Since it is comprised in this way, according to the manufacturing method of the polyphenylene ether of this embodiment, superposition | polymerization time can be shortened, fully suppressing foaming of the oxidative polymerization initial stage. That is, according to the method for producing polyphenylene ether of the present embodiment, since the foaming of the polymerization solution can be suppressed without reducing the activity of the polymerization reaction, the polymerization time can be shortened.

[Switching from the first polymerization step to the second polymerization step]
When moving from the first polymerization step to the second polymerization step, the absolute pressure in the gas phase of the reactor is increased from 0.098 MPa to 0.392 MPa in the first pressure of 0.098 MPa to less than 0.392 MPa. Change to the second pressure. Thus, foaming of the polymerization solution can be suppressed by increasing the pressure in the gas phase part of the reactor in the first oxidative polymerization of the phenolic compound. Further, by lowering the pressure in the gas phase part of the reactor in the late stage of oxidative polymerization of the phenolic compound, it is possible to prevent a decrease in the polymerization activity in the late stage of polymerization. In the present specification, “first period” indicates a period corresponding to the first polymerization step in the present embodiment, and “late period” indicates a period corresponding to the second polymerization step in the present embodiment. This production method makes it possible to fully utilize the capacity of the reactor by suppressing foaming and to shorten the polymerization time. The second pressure may be lower than the first pressure, but it is preferable to reduce the pressure by 10% or more. In other words, the second pressure is preferably less than 90% of the first pressure. Furthermore, it is more preferable to continue the oxidation polymerization by reducing the second pressure by 15% or more from the first pressure, and it is more preferable to continue the oxidation polymerization by reducing the pressure by 20% or more. In addition, the absolute pressure in this embodiment can be measured as described in the examples described later.

  In the first half (first half) of the polymerization reaction, the height of the bubbles increases with the progress of the reaction and then decreases rapidly, and in the second half (second half) of the polymerization reaction, the bubbles disappear. The timing for switching from the first polymerization step to the second polymerization step may be after the point when the height of the foam starts to decrease, and is preferably between 10 minutes before and after the point when the bubble disappears completely. Specifically, the foam disappears completely in about 10 minutes after the height of the foam starts to decrease.

  The ratio of the polymerization time in the first and second stages of polymerization (reaction) in the present embodiment is not particularly limited as long as the desired effect of the present embodiment can be ensured, but from the viewpoint of shortening the polymerization time in the second stage, The latter polymerization time is preferably 92% or less of the previous polymerization time, more preferably 82% or less, and even more preferably 54% or less. Although not limited to the following, for example, a case where “first polymerization time: late polymerization time” is 55:45 or 65:35 is a typical preferable embodiment.

  The method for changing the absolute pressure in the reactor gas phase is not particularly limited, but what is easy to implement industrially is a method in which the absolute pressure in the reactor is changed with a pressure regulating valve in the reactor gas phase. In addition, the aeration amount of the oxygen-containing gas (O) in the first polymerization step and the second polymerization step may be changed, or the aeration amount of the nitrogen-containing gas and air may be changed.

  When the first pressure and the second pressure are respectively controlled to be greater than 0.098 MPa and less than or equal to 0.392 MPa and between 0.098 MPa and less than 0.392 MPa, the oxygen partial pressure contained in the oxygen-containing gas to be vented is an absolute pressure. It is preferably 0.0147 MPa or more and 0.0883 MPa or less. When the absolute pressure in the gas phase part of the reactor is A (MPa), the range of A is 0.098 ≦ A <0.392, and the lower limit value of the oxygen concentration in the oxygen-containing gas is [(0.0147 / A ) × 100] (%), and the upper limit of the oxygen concentration is the value represented by [(0.0883 / A) × 100] (%). It is preferable from the viewpoint of achieving the state of the gas phase portion.

[First polymerization step and second polymerization step]
In this embodiment, a polymerization solution containing the phenolic compound (M), the aromatic solvent (A), and the catalyst (C) is prepared and accommodated in the reactor, and the oxygen-containing gas is added to the polymerization solution in the reactor. A polyphenylene ether can be obtained by aeration of (O) and oxidative polymerization of the phenolic compound (M).

<Polyphenylene ether>
The polyphenylene ether produced in the polymerization step in the method for producing polyphenylene ether of this embodiment will be described below. The polyphenylene ether produced by the polymerization step is not particularly limited, but specifically, it is a homopolymer or copolymer having a repeating unit represented by the following formula (1).

In the formula (1), R ₁ and R ₄ are each independently selected from the group consisting of hydrogen, primary or secondary lower alkyl, phenyl, aminoalkyl, and hydrocarbonoxy. Represent. In the formula (1), R ₂ and R ₃ each independently represent any one selected from the group consisting of hydrogen, primary or secondary lower alkyl, and phenyl.

  The homopolymer of polyphenylene ether is not particularly limited. Specifically, poly (2,6-dimethyl-1,4-phenylene) ether, poly (2-methyl-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-hydroxyethyl-1,4-phenylene) ether, poly (2-methyl-6-chloroethyl-1,4-phenylene) ether and the like. Among these, poly (2,6-dimethyl-1,4-phenylene) ether is preferable from the viewpoint that the raw materials are inexpensive and are easily available.

  The polyphenylene ether copolymer is a copolymer containing phenylene ether units as monomer units. The copolymer of polyphenylene ether is not particularly limited, and specifically, a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol, 2,6-dimethylphenol and o-cresol. And a copolymer of 2,6-dimethylphenol, 2,3,6-trimethylphenol and o-cresol. Among these, a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol is preferable from the viewpoint that the raw materials are inexpensive and are easily available.

<Phenolic compound (M)>
The polyphenylene ether can be produced by oxidative polymerization of a phenolic compound (M) represented by the following formula (2).

In the formula (2), R ₅ and R ₇ are each independently selected from the group consisting of hydrogen, primary or secondary lower alkyl, phenyl, aminoalkyl, and hydrocarbonoxy. Represent. In the formula (2), R ₆ and R ₈ each independently represents any one selected from the group consisting of hydrogen, primary or secondary lower alkyl, and phenyl.

  The phenolic compound (M) is not particularly limited, and specifically, 2,6-dimethylphenol, 2,3,6-trimethylphenol, 2-methyl-6-ethylphenol, 2,6-diethyl. Phenol, 2-ethyl-6-n-propylphenol, 2-methyl-6-chlorophenol, 2-methyl-6-bromophenol, 2-methyl-6-isopropylphenol, 2-methyl-6-n-propylphenol 2-ethyl-6-bromophenol, 2-methyl-6-n-butylphenol, 2,6-di-n-propylphenol, 2-ethyl-6-chlorophenol, 2-methyl-6-phenylphenol, 2 , 6-diphenylphenol, 2,6-bis- (4-fluorophenyl) phenol, 2-methyl-6-tolylfe Lumpur, 2,6-di-tolyl phenols, and the like. These phenolic compounds (M) may be used alone or in combination of two or more. Moreover, even if the aromatic solvent (A) used as a polymerization solution contains a small amount of phenol, o-cresol, m-cresol, p-cresol, 2,4-dimethylphenol, 2-ethylphenol and the like as impurities. Since it is consumed by the polymerization reaction as part of the phenolic compound (M) and incorporated into the polyphenylene ether, it can be substantially used.

  Among these, the phenolic compound (M) is preferably 2,6-dimethylphenol or a mixture of 2,6-dimethylphenol and 2,3,6-trimethylphenol. Dimethylphenol is more preferred.

<Aromatic solvent (A)>
Although it does not specifically limit as an aromatic solvent (A), Specifically, what melt | dissolves a low molecular weight phenolic compound (M), and melt | dissolves a part or all of a catalyst (C) can be used. .

  Examples of such aromatic solvent (A) include, but are not limited to, aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; halogenated aromatic carbonization such as chlorobenzene, dichlorobenzene, and trichlorobenzene. Hydrogen: nitro compounds such as nitrobenzene, etc. Among these, the aromatic solvent (A) is preferably at least one selected from the group consisting of toluene, xylene, and ethylbenzene, and more preferably toluene.

  If necessary, the aromatic solvent (A) can be mixed with a solvent having a property compatible with water. Although it does not specifically limit as a solvent which has a property compatible with water, Specifically, Alcohols, such as methanol, ethanol, and propanol; Ketones, such as acetone and methyl ethyl ketone; Esters, such as ethyl acetate and ethyl formate; Examples thereof include amides such as dimethylformamide; sulfoxides such as dimethyl sulfoxide. One or more of these solvents can be used in combination of two or more if necessary.

  As the aromatic solvent (A) used in the polymerization step, a solvent that is substantially incompatible with water can be preferably used. As those that are substantially incompatible with water, aromatic hydrocarbon solvents such as toluene and xylene are preferred.

  In addition, the form of polymerization in this embodiment varies depending on the selection of the ratio of good solvent to poor solvent for polyphenylene ether, which is a polymer obtained by oxidative polymerization of the phenolic compound (M). Specifically, a solution polymerization method is achieved by increasing the ratio of the good solvent, and a precipitation polymerization method is performed in which the polymer is precipitated as particles in the reaction solvent as the reaction proceeds by increasing the ratio of the poor solvent. The form of polymerization in the present embodiment is not particularly limited, and the desired polymerization form can be appropriately selected by adjusting the amount of the poor solvent added to the aromatic solvent (A) as necessary.

<Catalyst (C)>
The catalyst (C) efficiently converts the phenolic compound (M) by passing an oxygen-containing gas (O) through a polymerization solution containing the phenolic compound (M), the aromatic solvent (A) and the catalyst (C). It is an effective oxidation catalyst for oxidative polymerization to produce polyphenylene ether.

  Although it does not specifically limit as a catalyst (C), Specifically, 1 or more types selected from the group which consists of a copper compound, a bromine compound, a diamine compound, a tertiary monoamine compound, and a secondary monoamine compound, It is preferable to contain, and it is more preferable to contain a copper compound, a bromine compound, a diamine compound, a tertiary monoamine compound and a secondary monoamine compound as essential components.

  Although it does not specifically limit as a copper compound used as a component of a catalyst (C), Specifically, a cuprous compound, a cupric compound, or mixtures thereof can be used. Although it does not specifically limit as a cuprous compound, Specifically, cuprous oxide, cuprous chloride, cuprous bromide, cuprous sulfate, cuprous nitrate, etc. are mentioned. Moreover, although it does not specifically limit as a cupric compound, Specifically, cupric chloride, cupric bromide, cupric sulfate, cupric nitrate, etc. are mentioned. Among these, preferred compounds for cuprous and cupric compounds are cuprous oxide, cuprous chloride, cupric chloride, cuprous bromide and cupric bromide. In addition, these copper salts may be synthesized at the time of use from copper oxide, copper carbonate carbonate, copper hydroxide, and the like, and the corresponding halogen or acid. For example, cuprous bromide can be obtained by mixing cuprous oxide and hydrogen bromide (solution thereof). A preferable copper compound is a cuprous compound. These copper compounds may be used alone or in combination of two or more.

  Although it does not specifically limit as a bromine compound used as a component of a catalyst (C), Specifically, hydrogen bromide, sodium bromide, potassium bromide, tetramethylammonium bromide, tetraethylammonium bromide, etc. are mentioned. These bromine compounds may be used in the form of an aqueous solution or a solution using an appropriate solvent. These bromine compounds may be used alone or in combination of two or more.

  A preferable combination of the above-described copper compound and bromine compound is an aqueous solution of cuprous oxide and hydrogen bromide. Although the usage-amount of these compounds is not specifically limited, 2 times mole or more and 10 times mole or less are preferable as a bromine atom with respect to the molar amount of a copper atom. Moreover, it is preferable that it is the range of 0.02 mol-0.6 mol as a copper atom with respect to 100 mol of phenolic compounds (M).

  Although the diamine compound used as a component of a catalyst (C) is not specifically limited, Specifically, the diamine compound etc. which are represented by following formula (3) are mentioned. Among the diamine compounds represented by the formula (3), N, N′-di-t-butylethylenediamine is preferable. Although the usage-amount of a diamine compound is not specifically limited, It can be 0.5 times mole amount or more with respect to the mol number of the copper atom normally used, and an upper limit is not specifically limited.

In the formula (3), R ₁ , R ₂ , R ₃ , and R ₄ are each independently hydrogen or a linear or branched alkyl group having 1 to 6 carbon atoms, and all are not hydrogen at the same time. . R ₅ is a C 2-5 linear or methyl branched alkylene group.

  Although it does not specifically limit as a tertiary monoamine compound used as a component of a catalyst (C), An aliphatic tertiary amine including an alicyclic tertiary amine, etc. are mentioned. The tertiary monoamine compound is not particularly limited, and specific examples include trimethylamine, triethylamine, tripropylamine, tributylamine, triisobutylamine, dimethylethylamine, dimethylpropylamine, allyldiethylamine, dimethyl-n-butylamine, diethylisopropyl. Examples thereof include amines and N-methylcyclohexylamine. These tertiary monoamines may be used alone or in combination of two or more. Although the usage-amount of a tertiary monoamine compound is not specifically limited, The range of 0.1 mol-15 mol is preferable with respect to 100 mol of phenolic compounds (M).

  Although it does not specifically limit as a secondary monoamine compound used as a component of a catalyst (C), Specifically, dimethylamine, diethylamine, di-n-propylamine, di-i-propylamine, di-n-butylamine, Di-i-butylamine, di-t-butylamine, dipentylamines, dihexylamines, dioctylamines, didecylamines, dibenzylamines, methylethylamine, methylpropylamine, methylbutylamine, cyclohexylamine, N (substituted or non-substituted) Substituted phenyl) alkanolamine, N-hydrocarbon substituted aniline and the like.

  Although it does not specifically limit as said N (substituted or unsubstituted phenyl) alkanolamine, Specifically, N-phenylmethanolamine, N-phenylethanolamine, N-phenylpropanolamine, N- (m-methylphenyl) Examples include ethanolamine, N- (p-methylphenyl) ethanolamine, N- (2 ′, 6′-dimethylphenyl) ethanolamine, N- (p-chlorophenyl) ethanolamine and the like.

  The N-hydrocarbon substituted aniline is not particularly limited, and specifically includes N-ethylaniline, N-butylaniline, N-methyl-2-methylaniline, N-methyl-2,6-dimethylaniline, Examples include diphenylamine.

  These secondary monoamine compounds may be used alone or in combination of two or more.

  Although the usage-amount of a secondary monoamine compound is not specifically limited, Generally it is the range of 0.05 mol-15 mol with respect to 100 mol of phenolic compounds (M).

<Other materials>
In the polyphenylene ether production method of the present embodiment, other materials that can be contained in the polymerization solution are not limited to the following. For example, tetraalkylammonium salt compounds, polyethylene glycol group-containing alkylamines, and polyethylene glycol group-containing alkylammoniums. There may be mentioned at least one selected from the group consisting of salt compounds. The content of the other materials is preferably within a range not exceeding 0.1% by mass from the viewpoint of improving the efficiency of the polymerization reaction. Specific examples of the other materials include compounds having a structure represented by the following formula (4), (5) or (6).

In the formula (4), R ₁ , R ₂ , R ₃ and R ₄ are each independently a linear or branched alkyl group having 1 to 22 carbon atoms, and X is a paired anion, preferably Cl ^-, Br ^- is an anion selected from.

In the formula (5), R ₅ represents a linear or branched alkyl group having 1 to 22 carbon atoms, and R ₆ is — (CH ₂ CH ₂ O) _n —H in addition to the group defined as R _5. The group represented by [n is an integer of 1 to 40] may be used, and R ₇ is a group represented by — (CH ₂ CH ₂ O) _n —H [n is an integer of 1 to 40]. .

In the formula (6), R ₈ and R ₉ represent a linear or branched alkyl group having 1 to 22 carbon atoms, and R ₁₀ is — (CH ₂ CH ₂ O) in addition to the group defined as R _8. ) _N —H [n is an integer of 1 to 40], and R ₁₁ is — (CH ₂ CH ₂ O) _n —H [n is an integer of 1 to 40]. is a group, X is a pair anion, preferably Cl ^-, Br ^- is an anion selected from.

  In the method for producing polyphenylene ether of the present embodiment, as a more specific example of the other materials, trioctylmethyl known by trade names of Aliquat 336 (manufactured by Henkel) and Capriquat (manufactured by Dojindo Laboratories). Ammonium chloride is preferably used.

<Preparation of polymerization solution>
In preparing the polymerization solution, the components of the phenolic compound (M), aromatic solvent (A), and catalyst (C) may be introduced into the reactor independently, respectively, and the phenolic compound (M), catalyst (C) may be previously dissolved in the aromatic solvent (A) and then introduced into the reactor. First, the catalyst (C) previously dissolved in a part of the aromatic solvent (A) is added to the reactor. The phenolic compound (M) dissolved in the remaining aromatic solvent (A) is then introduced into the reactor.

  The temperature of the polymerization solution in the polyphenylene ether polymerization step is preferably adjusted to 0 to 80 ° C., more preferably 10 to 60 ° C., more preferably 20 to 50 ° C. from the viewpoint of the progress of the reaction and the activity of the catalyst. It is further preferable to adjust to. It is preferable to set the temperature lower in the first half of the polymerization step and higher in the second half of the polymerization step. Thereby, the progress of the polymerization reaction tends to be further promoted.

  The polymerization solution is preferably prepared with a blending amount of 10 to 25 parts by mass of the phenolic compound (M), 75 to 90 parts by mass of the aromatic solvent (A), and 0.1 to 10 parts by mass of the catalyst (C). Here, the total mass part of the phenolic compound (M) and the aromatic solvent (A) is 100 parts by mass. By setting it as such a compounding quantity, it exists in the tendency for the effect which polyphenylene ether polymerization control is stabilized to be acquired. The amounts of the phenolic compound (M), aromatic solvent (A) and catalyst (C) in the polymerization solution are the same as those for the phenolic compound (M), aromatic solvent (A) and catalyst (C) to the reactor. The mass ratio when the introduction is completed.

  In the present embodiment, a polymerization solution containing 12 to 23 parts by mass of the phenolic compound (M), 77 to 88 parts by mass of the aromatic solvent (A), and 0.5 to 9 parts by mass of the catalyst (C) is used. More preferable is a polymerization solution containing 13 to 21 parts by mass of the phenolic compound (M), 79 to 87 parts by mass of the aromatic solvent (A), and 0.8 to 8 parts by mass of the catalyst (C). By setting it as the said preferable range, it exists in the tendency for polyphenylene ether polymerization control to become more stable.

  The absolute pressure in the gas phase part of the reactor is 0.098 MPa or more and 0.392 MPa or less. When the absolute pressure in the gas phase part of the reactor exceeds 0.392 MPa, it is not preferable because excessive equipment is required. When the pressure is less than 0.098 MPa, it becomes a negative pressure region from the atmospheric pressure.

<Aeration of oxygen-containing gas (O)>
The aeration start timing of the oxygen-containing gas (O) is not particularly limited. In the preparation of the polymerization solution, after introducing any of the phenolic compound (M), the aromatic solvent (A), and the catalyst (C) into the reactor. It is preferable to start the ventilation of the oxygen-containing gas (O).

  Although it does not specifically limit as oxygen-containing gas (O), Specifically, what mixed oxygen and arbitrary inert gas, air, or what mixed air and arbitrary inert gas is used. it can. Although it does not specifically limit as an inert gas, Specifically, arbitrary things can be used if there is no big influence with respect to a polymerization reaction. Nitrogen can be mentioned as a typical inert gas.

  The oxygen-containing gas (O) is not particularly limited. Specifically, the oxygen-containing gas (O) preferably has an oxygen concentration of 5 to 25% by volume, includes a nitrogen-containing gas and air, and has an oxygen concentration of 6 to 20% by volume. Some are more preferable, and those containing a nitrogen-containing gas and air and having an oxygen concentration of 8 to 12% by volume are more preferable. With such a preferable oxygen concentration, the gradual heating, the polymerization rate and the like tend to be more stable.

  In addition, when the oxygen concentration of the unreacted gas in the oxygen-containing gas (O) after aeration exceeds 11.6%, nitrogen or other non-reactive substances are present in the reactor gas phase portion from the viewpoint of preventing explosion of the solvent used. It is preferable to introduce an active gas and control the oxygen concentration to 11.6% or less.

  The air flow rate of the oxygen-containing gas (O) is not particularly limited, but is preferably 0.5 NL / min to 15 NL / min with respect to 1 kg of the phenolic compound (M) to be subjected to the polymerization reaction, and is 3 NL / min to 14 NL / min. More preferably, 6 NL / min to 13 NL / min is even more preferable. By setting it to 0.5 NL / min or more, the target polyphenylene ether quickly reaches the desired molecular weight, and the productivity tends to be improved. On the other hand, by setting it to 15 NL / min or less, the problems of excessive equipment and increase in the amount of exhaust gas can be avoided, and the economy tends to be excellent.

(Removal of foam layer)
In the initial stage of oxidative polymerization in a general polyphenylene ether polymerization process, a foamed layer may occur. When the oxidative polymerization is continued and the phenolic compound (M) in the polymerization solution is consumed, foaming is subtracted. Therefore, the cause of the foaming of the polymerization solution at the initial stage of oxidative polymerization is that the phenolic compound (M) It is inferred that there is a lot related to foaming.

  In the method for producing polyphenylene ether of the present embodiment, the oxidative polymerization is continuously carried out while suppressing the generation of the foam layer generated in the first polymerization step by the first pressure in the gas phase part of the reactor. Thereby, the production efficiency per unit volume of the reactor can be improved. In addition, about generation | occurrence | production of a foaming layer, it can evaluate by foaming amount and the said foaming amount can be measured by the method as described in the Example mentioned later.

  In the method for producing polyphenylene ether of the present embodiment, the oxidative polymerization is performed by lowering the absolute pressure in the second polymerization step below the first pressure. This makes it possible to shorten the reaction time without reducing the polymerization activity. In addition, about reaction time, it can measure by the method as described in the Example mentioned later.

  The absolute pressure in the gas phase of the reactor is not particularly limited as long as the amount of foaming at the initial stage of oxidation polymerization is within the allowable range of the reactor, but specifically, from the viewpoint of securing a sufficient foaming suppression effect, One pressure is preferably 0.294 MPa or more, and is 0.392 MPa or less from the viewpoint of preventing excessive oxidation polymerization equipment.

  In the method for producing polyphenylene ether of the present embodiment, since the generation of a foamed layer occurring at the initial stage of the polymerization step can be suppressed, in the prior art, a reactor that has been designed extra for the foamed layer portion of the polymerization solution. The capacity of can be utilized.

  After performing the polymerization step as described above, the polymerization reaction is stopped when the target degree of polymerization is reached. The method for stopping the polymerization reaction is not particularly limited, and a conventionally known method can be applied. As a usual stopping method, an acid such as hydrochloric acid or acetic acid, or ethylenediaminetetraacetic acid (EDTA) and a salt thereof, nitrilotriacetic acid and a salt thereof are added to the reaction solution to deactivate the catalyst, and the polymerization is stopped. It is done. After termination of the polymerization, the produced polyphenylene ether is separated, washed with a solvent that does not dissolve the polyphenylene ether such as methanol, and dried to recover the polyphenylene ether.

  In a preferred embodiment of the method for producing polyphenylene ether of the present embodiment, 2,6-dimethylphenol is used as the phenolic compound (M), and the catalyst component (C) is cuprous oxide as the copper compound and odor as the bromine compound. Hydrogen fluoride (used in aqueous solution), N, N'-di-t-butylethylenediamine as diamine compound, N, N-di-n-butylamine as secondary monoamine compound, N, N-dimethyl-n- as tertiary monoamine Although using what is a form which used five components of butylamine together is mentioned, the manufacturing method of the polyphenylene ether of this embodiment is not limited to this form.

  As described above, in the present embodiment, it is not necessary to have an antifoaming agent that affects the polymerization reaction in the polymerization solution, thereby suppressing foaming of the polymerization solution without reducing the activity of the polymerization reaction. Ethers can be produced.

  Hereinafter, the present embodiment will be specifically described with reference to specific examples and comparative examples thereof. However, the present embodiment is not limited to the following examples. Measuring methods for physical properties and characteristics, etc. applied to the examples and comparative examples are shown below.

[Measurement of liquid surface contact area]
A scale was attached to the side surface of the reactor, and the contact with the foam on the liquid surface (interface between the liquid phase and the foam) was measured with the reactor bottom as 0 point. That is, in each example, stirring was started at a constant speed of 500 rpm immediately after the polymerization solvent was introduced into the reactor, and measurement was performed every 10 minutes from the start of oxidative polymerization. Specifically, the height of the liquid level in the stirring state when the polymerization solution was stirred was measured, and the maximum value in the polymerization reaction period was defined as the height of the liquid level in each example.

[Measurement of foaming amount]
The amount of foaming was measured using the scale, and the maximum value in the polymerization reaction period of the thickness from the liquid level measured above to the top surface of the foamed layer was taken as the amount of foaming.

[Measurement of liquid viscosity and polymerization time]
Using a vibrating liquid viscometer (VISCOMATE VM-100A) manufactured by SEKONIC, the polymerization liquid of each example sampled as described later was adjusted to 40 ° C., and the liquid viscosity (unit: cP) was determined. The time point at which the aeration of the oxygen-containing gas (O) is started with respect to the polymerization solution is regarded as the start point of oxidative polymerization, and the time point when the value of the liquid viscosity is 45 cP is regarded as the stop point of oxidative polymerization. The polymerization time from the start to the termination of oxidative polymerization was measured.

[Example 1]
As a reactor, the upper limit of the height of the reaction liquid is 50 cm, and the inner diameter is 16 cm. The reactor is a sparger for introducing an oxygen-containing gas (O) at the bottom, a stirring turbine blade, and a sampling discharge. A valve is provided, a baffle is provided on the side of the reactor, a temperature control device is provided, a polymerization condenser component inlet is provided at the top of the reactor, and a reflux condenser with a decanter for condensate separation is provided in the vent gas line. A SUS reactor with a liter jacket was used. At the vent gas outlet of the decanter, a pressure regulating valve and a pressure measuring device were installed.

(Polymerization process)
2,5-dimethylphenol 0.85 kg, toluene 5.59 kg, and catalyst (C) (1.1 g cuprous oxide, 8.2 g 47% hydrogen bromide aqueous solution, 2.6 g di-t-butyl A polymerization solution comprising 63.2 g of ethylenediamine, 12.7 g of di-n-butylamine, 38.6 g of butyldimethylamine) is prepared, and this is introduced into the reactor, and the reaction temperature is 40 ° C. After adjusting the absolute pressure (first polymerization pressure) in the vapor phase of the vessel to 0.301 MPa, an oxygen-containing gas (O) having an absolute pressure of 0.301 MPa and an oxygen concentration of 9% as the aerated oxygen-containing gas (O) ) Was bubbled through the polymerization solution from the sparger to initiate oxidative polymerization of 2,6-dimethylphenol (the oxygen partial pressure of this oxygen-containing gas (O) was 0.301 MPa × 0.09 = 0.02709 MPa. The . Bubble generation was observed after the start of the oxidative polymerization, but it was recognized that the foam had completely disappeared 90 minutes after the start of the oxidative polymerization, so the absolute pressure (second polymerization pressure) in the reactor gas phase was reduced. The pressure was changed to 0.201 MPa, and oxidation polymerization was continued. Sampling was carried out in small portions every 5 minutes from the lapse of 60 minutes after oxidative polymerization, and the time required for the liquid viscosity to reach a specific value (polymerization time from the start of polymerization until reaching the liquid viscosity = 45 cP) was taken as the polymerization time. 139 minutes after the start of oxidative polymerization, 0.65 kg of 10% aqueous solution of ethylenediaminetetraacetic acid tetrasodium salt (Dojindo Laboratories reagent) was added to stop the oxidative polymerization, and after washing with 7.65 kg of methanol, 140 ° C The polyphenylene ether of Example 1 was obtained by drying for 120 minutes under temperature conditions. Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

[Example 2]
The polyphenylene ether of Example 2 was obtained by performing the same operation as in Example 1 except that the first polymerization pressure was 0.351 MPa and the second polymerization pressure was 0.251 MPa 79 minutes after the start of oxidative polymerization. It was. That is, in this example, it was recognized that the foam was completely removed after 79 minutes from the start of oxidative polymerization. Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

Example 3
The polyphenylene ether of Example 3 was obtained by performing the same operation as in Example 1 except that the first polymerization pressure was 0.351 MPa and the second polymerization pressure was 0.301 MPa 80 minutes after the start of oxidative polymerization. It was. That is, in this example, it was recognized that the foam was completely removed after 80 minutes from the start of oxidative polymerization. Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

Example 4
Example 2 except that xylene was used instead of toluene as the aromatic solvent (A), the first polymerization pressure was 0.351 MPa, and the second polymerization pressure was 0.251 MPa 84 minutes after the start of oxidative polymerization. The polyphenylene ether of Example 4 was obtained in the same manner as in Example 1. That is, in this example, it was recognized that the foam was completely removed after 84 minutes from the start of oxidative polymerization. Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

Example 5
Example 2 except that ethylbenzene was used instead of toluene as the aromatic solvent (A), the first polymerization pressure was 0.351 MPa, and the second polymerization pressure was 0.251 MPa 83 minutes after the start of oxidative polymerization. The polyphenylene ether of Example 5 was obtained in the same manner as in Example 1. That is, in this example, it was recognized that the foam was completely removed after 83 minutes from the start of oxidative polymerization. Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

Example 6
1.04 kg of 2,6-dimethylphenol, 6.82 kg of toluene, and catalyst (C) (1.3 g of cuprous oxide, 10.1 g of 47% hydrogen bromide aqueous solution, 3.2 g of di-t-butyl 77.9 g of ethylenediamine, 15.7 g di-n-butylamine, 47.6 g butyldimethylamine), the first polymerization pressure is 0.351 MPa, and the second polymerization pressure is oxidized. The same procedure as in Example 2 was performed, except that the pressure was changed to 0.251 MPa 78 minutes after the start of polymerization, to obtain the polyphenylene ether of Example 6. That is, in this example, it was recognized that the foam was completely removed after 78 minutes from the start of oxidative polymerization. Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

Example 7
2,5-dimethylphenol 0.85 kg, toluene 5.48 kg, and catalyst (C) (4.9 g cuprous oxide, 36.8 g 47% aqueous hydrogen bromide, 134.1 g di-n-butylamine ) 175.8 g, a first polymerization pressure was set to 0.301 MPa, and the second polymerization pressure was set to 0.201 MPa 92 minutes after the start of oxidative polymerization. The same operation was performed to obtain the polyphenylene ether of Example 7. That is, in this example, it was recognized that the foam was completely removed after 92 minutes from the start of the oxidative polymerization. Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

[Comparative Example 1]
A polyphenylene ether of Comparative Example 1 was obtained in the same manner as in Example 1 except that the absolute pressure in the gas phase of the reactor during the entire polymerization reaction was set to 0.251 MPa and was not changed. The obtained polyphenylene ether was weighed to determine the reduced viscosity. Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

[Comparative Example 2]
A polyphenylene ether of Comparative Example 2 was obtained in the same manner as in Comparative Example 1 except that the absolute pressure in the gas phase of the reactor during the entire polymerization reaction was set to 0.351 MPa and was not changed. Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

[Comparative Example 3]
Except having used xylene instead of toluene as an aromatic solvent (A), operation similar to the comparative example 1 was performed and the polyphenylene ether of the comparative example 3 was obtained. Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

[Comparative Example 4]
A polyphenylene ether of Comparative Example 4 was obtained in the same manner as in Comparative Example 1 except that ethylbenzene was used instead of toluene as the aromatic solvent (A). Further, the amount of foaming of the polymerization solution during oxidative polymerization and the height of the contact portion on the liquid surface were measured. The results are shown in Table 1.

  The method for producing polyphenylene ether of the present invention has industrial applicability as a production technique for materials such as automobile parts, heat-resistant parts, electronic device parts, and industrial parts.

Claims (9)

Polymerization in which oxygen-containing gas (O) is passed through a polymerization solution containing the phenolic compound (M), the aromatic solvent (A), and the catalyst (C) in the reactor to oxidatively polymerize the phenolic compound. Having a process,
The polymerization step is
A first polymerization step in which the absolute pressure in the gas phase portion in the reactor is polymerized by controlling to a first pressure of more than 0.098 MPa and not more than 0.392 MPa;
After the first polymerization step, a second polymerization step in which the absolute pressure is controlled to a second pressure that is smaller than the first pressure and is 0.098 MPa or more and less than 0.392 MPa,
A process for producing polyphenylene ether, comprising:   The method for producing a polyphenylene ether according to claim 1, wherein the second pressure is less than 90% of the first pressure.   When the total of the phenolic compound (M) and the aromatic solvent (A) is 100 parts by mass, the polymerization solution is 10 to 25 parts by mass of the phenolic compound (M) and the aromatic solvent (A) 75. The manufacturing method of the polyphenylene ether of Claim 1 or 2 containing -90 mass parts and 0.1-10 mass parts of said catalysts (C).   The said phenolic compound (M) contains 2,6-dimethylphenol or a mixture of 2,6-dimethylphenol and 2,3,6-trimethylphenol. Of producing polyphenylene ether.   The method for producing a polyphenylene ether according to any one of claims 1 to 4, wherein the aromatic solvent (A) contains at least one selected from the group consisting of toluene, xylene and ethylbenzene.   The catalyst (C) contains any one or more selected from the group consisting of a copper compound, a bromine compound, a diamine compound, a tertiary monoamine compound and a secondary monoamine compound. 2. A method for producing polyphenylene ether according to item 1.   The manufacturing method of the polyphenylene ether of any one of Claims 1-6 whose oxygen concentration of the said oxygen containing gas (O) is 5-25 volume%.   The polyphenylene ether according to any one of claims 1 to 7, wherein the oxygen-containing gas (O) contains oxygen and nitrogen, and the oxygen concentration of the oxygen-containing gas (O) is 8 to 12% by volume. Production method.   The method for producing polyphenylene ether according to any one of claims 1 to 8, wherein an oxygen partial pressure of the oxygen-containing gas (O) is 0.0147 MPa or more and 0.0883 MPa or less.