JP2011068830A - Method of manufacturing aromatic azomethine resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an aromatic azomethine resin at a low cost, the aromatic azomethine resin being capable of forming a sheet or film easily, having excellent heat resistance and dimensional stability and having characteristics as an N-type semiconductor. <P>SOLUTION: The method of manufacturing the aromatic azomethine resin includes a step of performing condensation reaction starting from an aromatic diamine and an aromatic dialdehyde using an aromatic azomethine as a solvent for the condensation reaction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an aromatic azomethine resin.

  Aromatic azomethine resins obtained by mixing and heating aromatic diamines and aromatic dialdehydes are hard and excellent in heat resistance, so they are not only used as materials for electronic and electrical equipment, but also in the space field, This resin is expected to be used in a wide range of fields such as aviation and electronic communication.

  On the other hand, the aromatic azomethine resin has low solubility in a solvent. For this reason, it is difficult to form an aromatic azomethine resin into a sheet or film by casting.

  In order to enhance the solubility of the aromatic azomethine resin in a solvent, conventionally, a technique for synthesizing an aromatic azomethine resin having a substituent having fluorine introduced into the side chain has been disclosed (for example, see Non-Patent Document 1). .)

PNANAV KUMAR GUTCH, Journal of Polymer Science; Part A: Polymer Chemistry, Vol. 39, p. 383-388 (2001)

  However, aromatic diamines and aromatic dialdehydes having a fluorine-introduced substituent, which are raw materials for synthesizing aromatic azomethine resins having a substituent having fluorine introduced into the side chain, are very expensive and expensive. Therefore, there is a problem that it is not suitable for practical use.

  Therefore, in the present invention, an aromatic azomethine resin, which is easy to form into a sheet and film, is excellent in heat resistance and dimensional stability, and has properties as an N-type semiconductor, can be produced at low cost using general raw materials. It aims at providing the method of manufacturing by.

As a result of diligent research to solve the above-described problems of the prior art, the present inventors have found that dimethylacetamide, dimethylformamide, dioxane, cresol, and the like, which have been conventionally used for the synthesis of aromatic azomethine resins, have been used. Instead, by using a low molecular weight aromatic azomethine, it was found that an aromatic azomethine resin having an excellent heat resistance and dimensional stability can be produced at low cost by being easily formed into a sheet or a film. Completed.
That is, the present invention is as follows.

[1]
A method for producing an aromatic azomethine resin, comprising a step of performing a condensation reaction using an aromatic diamine and an aromatic dialdehyde as raw materials and using aromatic azomethine as a solvent for the condensation reaction.

[2]
The method for producing an aromatic azomethine resin according to [1], wherein an aromatic azomethine having a molecular weight of 300 or less is used as a solvent for the condensation reaction.

[3]
The aromatic azomethine, which is a solvent for the condensation reaction, is a method for producing an aromatic azomethine resin according to [1] or [2], wherein the molecular structure is represented by the following formula (1).

  In said formula (1), R1-R4 is respectively independently a hydrogen atom or a C5 or less alkyl group.

[4]
Using the aromatic azomethine as a solvent, the aromatic diamine and the aromatic dialdehyde are subjected to a condensation reaction to obtain an aromatic azomethine resin solution, and the aromatic azomethine resin solution is heated to remove the aromatic azomethine The method for producing an aromatic azomethine resin according to any one of [1] to [3].

  According to the present invention, it is possible to obtain an aromatic azomethine resin which is easy to form into a sheet or a film and has excellent heat resistance and dimensional stability, using raw materials available at low cost.

The nuclear magnetic resonance (NMR) spectrum of aromatic azomethine which is a solvent is shown. The measurement volatility | heat volatility and thermal analysis of aromatic azomethine which is a solvent are shown. The measurement graph by the cyclic voltammetry of the aromatic azomethine resin of an Example is shown.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail.
In addition, this invention is not restrict | limited to the following embodiment, A various deformation | transformation can be implemented within the range of the summary.

[Method for producing aromatic azomethine resin]
In the present embodiment, an aromatic azomethine resin is produced by using an aromatic diamine and an aromatic dialdehyde as raw materials and using an aromatic azomethine as a solvent for the condensation reaction, performing a condensation reaction.

The raw material used for the condensation reaction will be described.
(Aromatic diamine)
Examples of the aromatic diamine include commonly used aromatic diamines such as paraphenylene diamine, metaphenylene diamine, 2,4-diaminotoluene, paraoxydianiline, and diaminodiphenyl ether.

(Aromatic dialdehyde)
Examples of the aromatic dialdehyde include commonly used aromatic dialdehydes such as terephthalaldehyde, isophthalaldehyde, and 2,2′-bipyridine-4,4′-dicarboxaldehyde.

The condensation solvent will be described.
(Aromatic azomethine)
In the method for producing an aromatic azomethine resin of the present embodiment, aromatic azomethine is used as a condensation solvent.
The aromatic azomethine is preferably a so-called low molecular weight aromatic azomethine having a molecular weight of 300 or less. From a practical viewpoint such as solubility, aromatic azomethine having a molecular weight of 181 or more is preferable.
Use of an aromatic azomethine having a molecular weight of 300 or less facilitates heat removal during the synthesis of the target aromatic azomethine resin.
If an aromatic azomethine having a molecular weight exceeding 300 is used, the solubility is lowered and it is difficult to remove by evaporation.

  Specifically, as the aromatic azomethine that is the condensation solvent, a compound having a molecular structure represented by the following formula (1) can be used.

  In said formula (1), R1-R4 is respectively independently a hydrogen atom or a C5 or less alkyl group.

Examples of the “alkyl group having 5 or less carbon atoms” that can be substituted include, but are not limited to, for example, methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, isobutyl group , S-butyl group, t-butyl group, cyclobutyl group, cyclopropylmethyl group, n-pentyl group, cyclopentyl group, cyclopropylethyl group, and cyclobutylmethyl group.
Since the aromatic azomethine represented by the above formula (1) preferably has a smaller molecular weight, the substituents R1 to R4 are preferably hydrogen or a methyl group, more preferably hydrogen, and the substituents R1 to R4 are all hydrogen. The molecular weight is 181.

A method for producing aromatic azomethine used as a solvent will be described.
The aromatic azomethine used as a solvent represented by the above formula (1) is obtained by a condensation reaction of an aromatic aldehyde represented by the following formula (2) and an aromatic amine represented by the following formula (3).

As the aromatic aldehyde represented by the above formula (2), for example, benzaldehyde, p-methylbenzaldehyde, m-methylbenzaldehyde and the like can be preferably used.
In the above formula (2), R1 and R2 are each independently a hydrogen atom or an alkyl group having 5 or less carbon atoms.

As the aromatic amine represented by the above formula (3), for example, aniline, p-toluidine, m-toluidine and the like can be preferably used.
In the above formula (3), R 3 and R 4 are each independently a hydrogen atom or an alkyl group having 5 or less carbon atoms.

The temperature and time of the condensation reaction between the aromatic aldehyde and the aromatic amine in producing the aromatic azomethine are not particularly limited, but are usually 30 to about 50 to 150 ° C. in a nitrogen atmosphere. What is necessary is just to make it react for minutes-5 hours.
Further, the solvent used in the condensation reaction is not particularly limited, and for example, dimethylacetamide, dimethylformamide, dioxane and the like can be used.
For example, when dimethylformamide is used as the solvent, the reaction can be allowed to proceed completely by reacting at 140 ° C. for about 2 hours.
Further, from the viewpoint of the condensation reaction, the aromatic aldehyde represented by the above formula (2) and the aromatic amine represented by the above formula (3), which are raw materials, may be blended at 1: 1 (molar ratio). preferable.

By the condensation reaction of the aromatic aldehyde and the aromatic amine, water is generated as a by-product.
In order to remove such water, a method of drying by flowing nitrogen into the reaction vessel, a method of dropping toluene by azeotropic distillation during the condensation reaction, or the like can be applied.

  After the condensation reaction between the aromatic aldehyde and the aromatic amine is completed, the solution is poured into a large amount of cold water with stirring to precipitate aromatic azomethine, which is a condensation solvent used in this embodiment. it can. After the precipitate is filtered, vacuum drying is performed to obtain aromatic azomethine as a condensation solvent.

The aromatic dialdehyde and aromatic diamine described above are used as raw materials, and the aromatic azomethine resin of this embodiment is manufactured using aromatic azomethine as a condensation solvent.
At this time, when the total weight of the raw material aromatic dialdehyde and aromatic diamine is 100 parts by mass, the amount of the aromatic azomethine is not particularly limited as long as the raw material can be sufficiently dissolved. For example, 100 mass parts-3000 mass parts are suitable.
If the solvent is less than 100 parts by mass, sufficient solubility may not be obtained, and even if an amount exceeding 3000 parts by mass is used, the solubility does not improve and the efficiency of solvent removal in the next step decreases. To do.

The temperature and time of the condensation reaction between the aromatic dialdehyde and the aromatic diamine are not particularly limited, but are usually 30 minutes to 5 minutes in a nitrogen atmosphere under a temperature condition of about 50 ° C. to 200 ° C. Perform time reaction.
Moreover, it is preferable to mix | blend the aromatic dialdehyde and aromatic diamine which are raw materials by 1: 1 (molar ratio) from a viewpoint of a condensation reaction.

  Water is generated as a by-product by the condensation reaction between the aromatic dialdehyde and the aromatic diamine. Examples of the method for removing the water include a method of flowing nitrogen in a reaction vessel and drying, a method of dropping toluene during the condensation reaction and removing it by azeotropic distillation.

As described above, a condensation reaction is performed to remove water as a by-product, and then aromatic azomethine as a solvent is removed.
Examples of the method for removing the solvent include a method in which a solution of the aromatic azomethine resin after the condensation reaction is cast, formed into a film, and then dried by heating.
In addition, when precipitation is intense during the condensation reaction, the solvent in the reaction where condensation has progressed to some extent is cast to form a film, and then the solvent can be removed by heating and drying.

  As a casting method, for example, it is uniformly applied on a polyethylene terephthalate sheet or a glass plate by using a knife coater method, a spin coating method or the like, and then in a heating oven controlled at 120 to 250 ° C. for 10 minutes to A method of obtaining a film-like aromatic azomethine resin by heating and drying for 2 hours to remove the solvent by heating and drying is used.

  The aromatic azomethine resin obtained by the production method of the present embodiment can be formed into a film shape or a sheet shape using a commonly available material as a raw material, and has excellent heat resistance and dimensional stability.

  Hereinafter, although the Example of this invention and the comparative example with respect to this are given and demonstrated concretely, this invention is not limited to the following example. In the following, “%” means mass%.

The characteristics of aromatic azomethine used as a solvent were measured as follows.
<Nuclear magnetic resonance spectrum (NMR spectrum)>
Measurement was performed using 1H-NMR (600 MHz) manufactured by Varian Inova.
At that time, deuterated chloroform was used for the measurement, the number of spectrum integrations was 256, and the relaxation time was 10 seconds.
<Heat volatility and heat decomposition resistance>
Using a thermogravimetric analyzer TG / DTA6200 (manufactured by SII Technology Co., Ltd.), the weight loss due to heating was measured at a temperature rising rate of 10 ° C./min.
At the same time, as secondary information, heat generation and endotherm from the sample were detected by DTA (differential thermal analysis).

The characteristics of the aromatic azomethine resin produced in the following examples were measured as follows.
<Cyclic voltammetry>
As shown in the examples described later, the redox characteristics of the aromatic azomethine resin coated and cured on a platinum plate were measured using a potentiostat (part number HABF-501F) manufactured by Hokuto Denko Corporation. .
The platinum plate having the cured aromatic azomethine resin was put into a 0.1 M acetonitrile solution of tetrabutylammonium phosphorus hexafluoride, and a silver / silver chloride electrode was used as a reference electrode.
The sweep rate was 50 mV / second, and the measurement was performed between 0 and -2 volts.

[Example 1]
(Production of solvent)
First, aromatic azomethine used as a solvent for the condensation reaction was produced as follows.
In a 1000 mL round bottom flask equipped with a reflux condenser, 106 g (1 mol) of benzaldehyde (Wako Pure Chemicals, product number 025-12206) and 93 g (1 mol) of aniline (Wako Pure Chemicals, product number 019-03996) were used as raw materials. Was added. Further, 360 g of dimethylformamide (Wako Pure Chemicals, product number 045-02916) was added, and nitrogen substitution was performed by flowing nitrogen into the flask at a rate of 5 mL / min for 30 minutes while stirring. Then, it melt | dissolved by heating in the oil bath set to 130 degreeC.
Further, toluene was slowly dropped into the flask at a rate of 50 mL / hour.
The dropped toluene formed an azeotropic compound with water generated during the condensation reaction, and the azeotropic compound was exhausted out of the system by a stream of nitrogen.
The reaction between the aniline and benzaldehyde is carried out with stirring at a speed of 120 revolutions / minute using a stirring blade, and heating is stopped in an oil bath set at 130 ° C., and heating is stopped after 1 hour. Cooling to room temperature with stirring.
The reaction solution after cooling was poured into about 2 liters of cold water with stirring to precipitate aromatic azomethine.
After removing the cold water from the supernatant, it was further washed with stirring using 2 liters of water, and then the precipitated aromatic azomethine was filtered off.
Then, the aromatic azomethine used as a solvent of a condensation reaction was obtained by vacuum-drying at 40 degreeC for 24 hours.

When the aromatic azomethine was analyzed by NMR, the spectrum shown in FIG. 1 was obtained.
The numerical value in FIG. 1 shows the integration ratio.
As shown in FIG. 1, it was confirmed by NMR spectrum that it has a —HC═N— group unique to azomethine.
Since the chemical shift of the hydrogen atom in the —HC═N— group is 8.6 ppm, which is particularly high compared to others, it can be clearly distinguished from the hydrogen atom in the aromatic.
Moreover, since the integration ratio was in agreement with the expectation, it was judged that the desired aromatic azomethine was obtained.

In order to use the aromatic azomethine produced as described above as a solvent in an aromatic azomethine resin production process described later, it is necessary to be able to be volatilized and removed. Therefore, heat volatility and thermal analysis were measured using a thermogravimetric analyzer.
The measurement results are shown in FIG.
The DTA curve (vertical left) represents heat generation / endotherm from the measurement sample.
The TG curve (right vertical axis) represents the change in weight with temperature.
As shown in the DTA curve, a large endothermic peak was confirmed at about 60 ° C. Thereby, it turned out that melting | fusing point of the aromatic azomethine obtained by the above is about 60 degreeC.
In addition, as shown in the TG curve, the weight reduction started at about 120 ° C. and reached 0 at 240 ° C., so it was found that the synthesized aromatic azomethine was extremely excellent in volatility.

(Manufacture of aromatic azomethine resin)
Next, using the aromatic azomethine obtained as described above as a solvent, an aromatic azomethine resin was produced as follows.
In a 50 mL beaker containing a magnetic stir bar, 1.08 g (0.01 mol) of paraphenylenediamine (Wako Pure Chemicals, product number 164-01532) and terephthalaldehyde (Wako Pure Chemicals, product number 207-03595) are used as raw materials. 1.34 g (0.01 mol) was added.
As a condensation solvent, 20 g of the aromatic azomethine prepared as described above and 3 g of toluene (Wako Pure Chemicals, product number 204-01866) were added.
The beaker was placed on a hot plate equipped with a stirring function and heated while stirring.
The surface temperature of the hot plate was adjusted with a dial so as to be 150 ° C.
After 30 minutes, the solution had a yellow color characteristic of azomethine.
This solution was applied to a platinum plate using a spin coat and placed on a hot plate set at a surface temperature of 240 ° C. to completely volatilize and remove aromatic azomethine as a solvent.
By this series of operations, a dense film of aromatic azomethine resin having a thickness of about 2 μm was formed on the platinum plate.

Cyclic voltammetry was used to measure the redox characteristics of the aromatic azomethine resin film produced as described above.
The measurement results are shown in FIG. In FIG. 3, the applied potential is plotted on the horizontal axis and the response current value is plotted on the vertical axis.
As a result, a reduction wave was observed at -1.7 V and an oxidation wave was observed at around -1.4 V, and it was revealed that this aromatic azomethine resin has properties as an N-type semiconductor.
Moreover, also in visual observation, electrochromism in which the color of the film changes from yellow to reddish brown at an applied potential of about −1.5 V was observed.
The membrane was scraped from a platinum plate to obtain an aromatic azomethine resin powder.
The thermal decomposition resistance of this powder was evaluated by measuring the weight loss due to heating at a heating rate of 10 ° C./min using a thermogravimetric analyzer TG / DTA6200 (manufactured by SII Technology). The temperature at which the weight decreased by 1% was 480 ° C. This revealed that the aromatic azomethine resin of the present invention has extremely high heat resistance.

[Comparative Example 1]
In a 50 mL beaker containing a magnetic stir bar, 1.08 g (0.01 mol) of paraphenylenediamine (Wako Pure Chemicals, product number 164-01532) and terephthalaldehyde (Wako Pure Chemicals, product number 207-03595) are used as raw materials. 1.34 g (0.01 mol) was added.
Further, 20 g of dimethylformamide (Wako Pure Chemicals, product number 045-02916) was added as a solvent in place of the aromatic azomethine used in Example 1 above, and 3 g of toluene (Wako Pure Chemicals, product number 204-01866) was further added. It was.
The beaker was placed on a hot plate having a stirring function and heated while stirring.
The surface temperature of the hot plate was adjusted with a dial so as to be 150 ° C.
However, after about 20 minutes, the whole reaction solution becomes cloudy, and after 30 minutes, almost all of the resin precipitates, and the subsequent operation cannot be performed, and an aromatic azomethine resin formed into a sheet or film is produced. I couldn't.

  The aromatic azomethine resin obtained by the production method of the present invention has high heat resistance and electrical properties such as electrochromism, and therefore has conductivity in electronic equipment / electric equipment materials, space field, aviation field and electronic communication field. As a polymer, it has industrial applicability.

Claims (4)

Using aromatic diamine and aromatic dialdehyde as raw materials,
A method for producing an aromatic azomethine resin, comprising a step of performing a condensation reaction using aromatic azomethine as a solvent for the condensation reaction.   The method for producing an aromatic azomethine resin according to claim 1, wherein an aromatic azomethine having a molecular weight of 300 or less is used as a solvent for the condensation reaction. The method for producing an aromatic azomethine resin according to claim 1 or 2, wherein the aromatic azomethine, which is a solvent for the condensation reaction, has a molecular structure represented by the following formula (1).
(In the above formula (1), R1 to R4 are each independently a hydrogen atom or an alkyl group having 5 or less carbon atoms.) Using the aromatic azomethine as a solvent, the aromatic diamine and the aromatic dialdehyde are subjected to a condensation reaction to obtain a solution of an aromatic azomethine resin,
The method for producing an aromatic azomethine resin according to any one of claims 1 to 3, wherein the aromatic azomethine resin is heated to remove the aromatic azomethine.