JP3941158B2 - Process for producing poly- (1,4-phenylene ether) having hydroxyl groups at both ends - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing poly- (1,4-phenylene ether) having hydroxyl groups at both ends, which is useful as a polymer material having excellent thermal stability.
[0002]
[Prior art]
Poly- (2,6-dimethylphenylene ether) (hereinafter sometimes abbreviated as PPE) obtained by oxidative polymerization using a transition metal complex catalyst of 2,6-dimethylphenol is known to be a useful resin. It has been. However, PPE has a drawback that it is difficult to melt-mold with PPE alone because the methyl group substituted on the aromatic ring is susceptible to oxidative degradation, and is generally positioned as a general-purpose engineering plastic as a polymer alloy with polystyrene.
[0003]
On the other hand, poly-1,4-phenylene ether, which is a polymer of unsubstituted phenol, has a melting point of 298 ° C. (glass transition temperature) as described in Europ. Polym. J., 4, 275 (1968). Is expected to be used as a connector for electronic parts, for example, as an ultra-high heat-resistant resin.
[0004]
However, in the method of producing poly-1,4-phenylene ether by oxidative polymerization of an unsubstituted phenol having no substituent at the 2-position in the presence of a transition metal complex catalyst, There was a drawback that ortho branching was likely to occur.
Here, the ortho-position branching means that the benzene ring in the phenol polymer has a 1,2,4-trisubstituted benzene structure, a 1,2-disubstituted benzene structure, a 1,2,6-trisubstituted benzene structure, , 4,6-tetrasubstituted benzene structure and the like, and is a structure that disrupts the originally desired 1,4-disubstituted benzene chain.
[0005]
By the way, poly- (1,4-phenylene ether) having hydroxyl groups at both ends is also useful as an ultra-high heat-resistant resin, and further used for copolymerization for the purpose of increasing the molecular weight, It is very useful for adding functional groups for the purpose of improving physical properties. Regarding the production method, for example, JP-A-59-168029 describes a method in which a mixture of phenols and bisphenols is reacted with oxygen in an organic solvent in the presence of a transition metal complex catalyst. Specifically disclosed is a process for producing a polymer obtained from 2,6-disubstituted phenols and propane or methane having two hydroxyphenyl groups having a substituent at the ortho position relative to the hydroxyl group. Nothing is specifically disclosed as to whether or not an unsubstituted poly- (1,4-phenylene ether) can be produced.
[0006]
In JP-A-2-214724, a mixture of a phenol halogenated at the para-position and a bisphenol or hydroquinone is reacted in a polar aprotic solvent in the presence of Cu (I) halide to form hydroxyl groups at both ends. Although a method for producing poly- (1,4-phenylene ether) having an alkyl group is disclosed, there is a problem that it is practically necessary to add an alkali metal hydroxide of an equivalent amount or more with respect to the phenolic hydroxyl group. there were.
[0007]
Japanese Patent Publication No. 44-28917 discloses 4- (4-hydroxyphenoxy) -phenol, 4,4′-dihydroxydiphenyl ether or 4,4′-bis (4-hydroxyphenoxy) -diphenyl ether at a temperature of 250 to 300 ° C. The method for producing poly- (1,4-phenylene ether) having hydroxyl groups at both ends by heating is shown, but in this case, there is a problem that high temperature is required.
[0008]
[Problems to be solved by the invention]
Under such circumstances, the problem to be solved by the present invention, that is, the object of the present invention is to produce a poly- (1,4-phenylene ether) having hydroxyl groups at both ends with few branches at the ortho position under mild conditions. Is to provide.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have found a method using a specific starting material and have completed the present invention. That is, the present invention relates to a process for producing poly- (1,4-phenylene ether) having hydroxyl groups at both ends by oxidizing 4,4′-dihydroxydiphenyl ether in an organic solvent in the presence of a transition metal complex catalyst and an oxidizing agent. It depends on.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The catalyst in the production method of the present invention is a transition metal complex catalyst, and a transition metal complex catalyst having activity in the oxidation reaction of phenols can be usually used. More preferably, a complex catalyst of manganese, cobalt or copper is used, and a copper complex catalyst is more preferably used. Examples of transition metal complexes include transition metal complexes obtained by contacting transition metal halides such as CuCl and CuBr with nitrogen-containing aromatic compounds such as pyridine, imidazole and oxazole.
The catalyst can be used in any amount, but is preferably 0.01 to 50 mol%, preferably 0.02 to 10 mol based on 4,4′-dihydroxydiphenyl ether (hereinafter sometimes abbreviated as DHPE). % Is more preferable.
[0011]
Any oxidant may be used in the present invention, but oxygen is preferably used. Any oxygen source can be used, but oxygen gas or air is preferably used.
[0012]
The organic solvent that can be used in the present invention is not particularly limited as long as it is inert to DHPE and liquid at the reaction temperature. Examples of preferred solvents include benzene, toluene, xylene, chlorobenzene, dichlorobenzene, chloroform, dioxane, diglyme, anisole and the like. These are used alone or as a mixture.
The concentration of DHPE is preferably 0.5 to 50% by weight, more preferably 1 to 30% by weight.
[0013]
The reaction temperature for carrying out the present invention is not particularly limited as long as the reaction medium is kept in a liquid state, but is preferably 0 ° C to 150 ° C.
[0014]
【Example】
The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited by these examples.
[0015]
In the following examples and comparative examples, the infrared absorption spectrum of the polymer was measured using a 1600 infrared spectrophotometer (KBr method) manufactured by PerkinElmer.
[0016]
An index (o / p) indicating the ortho branching amount of the polymer was determined from the infrared absorption spectrum of the polymer as follows. According to Europ. Polym., J., 4, 275 (1968), a structure having a substituent at positions 1, 2, 4 of the benzene ring has a peak at 970 cm ^-1 and has a substituent at positions 1, 4 The structure shows that a peak appears at 1010 cm- ¹ . The value obtained by dividing the peak area by the former peak area from the ortho bond and the latter peak area was defined as o / p. The calculation of the peak areas using spectral analysis software manufactured by Perkin-Elmer Corporation (GRAMS Analyst for 1600 Series), between the ortho bond derived peak area of 948~988cm ^-1, while the para bond derived peak of 994～1018Cm ^-1 As sought.
[0017]
Example 1
In a 50 ml eggplant flask equipped with a magnetic stirrer and a reflux condenser, 25 mg of CuCl, 33 mg of 2-methylbenzimidazole and 0.5 ml of chloroform were put and stirred at room temperature for 15 minutes while blowing oxygen gas. To this was added 1.01 g of DHPE dissolved in a mixed solvent of 15 ml of anisole and 5 ml of diglyme, and stirring was continued at 50 ° C. for 4 hours while blowing oxygen gas. After completion of the reaction, the reaction mixture was poured into 100 ml of methanol containing 0.5 ml of concentrated hydrochloric acid. The precipitate was collected by filtration and dried under reduced pressure at 100 ° C. for 5 hours. The yield was determined from the weight of the polymer, and it was 53%. The ortho branching amount (o / p) of the polymer was 0.4.
[0018]
Example 2
As a result of performing oxidative polymerization in the same manner as in Example 1 except that 50 mg of CuCl and 48 mg of 2-ethylimidazole were used as the catalyst and 10 ml of diglyme was used as the solvent, the yield was 55% and o / p was 0.3. there were.
[0019]
Comparative Example 1
Oxidative polymerization was carried out in the same manner as in Example 1 except that 50 mg of CuCl and 66 mg of 2-methylbenzimidazole were used as the catalyst, and 404 mg of DHPE and 1887 mg of phenol were used as the monomers. The yield of the polymer was 33% and o / p was 0.8.
[0020]
Infrared absorption spectra of the polymers obtained in Example 1 and Comparative Example 1 are shown in FIG.
From the results shown above, in Comparative Example 1 using a mixture of phenol and DHPE as a monomer, a large amount of ortho branching (o / p) was observed in the infrared absorption spectrum, and 690 cm ⁻¹ and 752 cm ^−1. In Example 1 and 2 using only DHPE, the peak derived from the mono-substituted benzene ring is small and the amount of ortho-position branching (o / p) is small. Is not observed at all. As a result, it was shown that the polymers obtained in Examples 1 and 2 had hydroxyl groups at both ends, and the ortho-position branching was reduced as compared with the prior art.
[0021]
【The invention's effect】
As described above, according to the present invention, poly- (1,4-phenylene ether) having hydroxyl groups at both ends in which the branching at the ortho position is reduced as compared with the prior art can be produced under mild conditions. .
[Brief description of the drawings]
1 is an infrared absorption spectrum of the polymers obtained in Example 1 and Comparative Example 1. FIG.

Claims (2)

It has hydroxyl groups at both ends, characterized by oxidizing 4,4'-dihydroxydiphenyl ether in an organic solvent in the presence of a transition metal complex catalyst obtained by contacting a copper halogen compound with an imidazole compound and an oxidizing agent. Production method of poly- (1,4-phenylene ether). Method for producing a (1,4-phenylene ether) - oxidizing agent, poly having hydroxyl groups at both terminals according to claim 1, characterized in that the oxygen.

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