JPS5842872B2 - Method for producing diester diacid anhydride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a diester dianhydride having an ester bond in the central main chain, which is generally used as an epoxy resin curing agent.

Pyromellitic diacid anhydride (PMDA), which is generally known as aromatic tetracarboxylic anhydride, and 3,3',4
・4'-benzophenonetetracarboxylic anhydride (BT
It is known that when DA) is mixed with an epoxy resin and cured, it has high curing reactivity without using a highly toxic amine catalyst, and also has excellent heat resistance and chemical resistance even when the amount of cured epoxy resin is used. It is being

However, the aromatic tetracarboxylic anhydride has particularly high melting points, poor compatibility with epoxy resins, and has disadvantages such as easy separation of the mixture and short pot life.

In particular, poor solubility in organic solvents is important for painting, laminating,
This makes it difficult to use as an adhesive.

To improve this point, aromatic tetracarboxylic anhydride 1
It is known to react with 0.5 mole of aliphatic diol to convert it into a form that can be dissolved in a solvent.

Conventional reaction solvents include methyl ethyl ketone (MEK),
Methyl isobutyl ketone (MIBK), cellosolve acetate, and the like are generally known.

The product obtained by solution reaction is mixed well with general epoxy resin, diluted with a majority solvent, and used for coatings, laminates, and adhesives.

The reaction in an organic solvent proceeds as shown in equation (1) below.

However, 1) In the formula, Ar represents an aromatic residue and R represents an aliphatic residue.

The reaction is carried out under reflux in an inert gas atmosphere, and after the reaction is cooled to room temperature, insoluble materials are filtered off.

This compound is stable for several months when stored in a dry atmosphere.

By appropriately selecting the structures of Ar and R in formula (1), when mixed with an epoxy resin appropriately, an epoxy resin composition that is highly reactive and can be cured near room temperature, chemical resistance, adhesive strength, An epoxy resin composition with excellent hardness etc., an epoxy resin composition with high flexibility, etc. can be obtained.

In addition, the increased solubility in organic solvents facilitates the application of dry lamination methods.

However, the conventional method for obtaining diester dianhydride, which is the desired reaction product, by the reaction of formula (1) requires a reaction time of at least several hours, has a low yield, and is insufficient depending on the type of aliphatic diol. It was also difficult to perform a similar reaction.

★★ The present invention relates to improvement of the solution reaction shown in equation (1).

That is, it is characterized by completing the reaction at a lower temperature and in a shorter time than conventional methods, and by increasing the yield, the desired compound can be obtained stably and economically.

A detailed explanation of the conventional example and the present invention will be given below.

Conventional example 3 equipped with N2 gas introduction pipe, thermometer, stirrer, and cooling pipe
PMDA and various aliphatic diols are charged together with a reaction solvent into a separable flask (No. 1), and the mixture is refluxed in an N2 gas atmosphere to obtain a desired diester di-acid anhydride according to formula (1).

The reaction solvent and reaction temperature were MEK (80°C),
MIBK/MEK (9/1) (100°C), cellosolve acetate (120°C), and xylene (140°C) were used.

The results are shown in Table 1. However, the solution concentration is approximately 40%.

A method using chillformamide as a reaction solvent will be explained.

PMDA436F, ethylene glycol 62g and N-N
100 Oy of dimethylformamide was charged, and the inside of the flask was replaced with N2 gas, followed by heating and stirring.

The temperature was raised from room temperature of 20 to 30°C to 60°C in about 20 minutes.

The opaque contents 81 change to a reddish-brown transparent solution due to the esterification reaction that proceeds rapidly at 50-60°C (10-20 minutes).

Distill this solution under reduced pressure at 60°C ± 10 deg**
A brittle solid is obtained.

This product dissolves more than 100% of each of acetone and MEKlooF, forming a uniform solution.

The organic elemental analysis result of the reaction product obtained by purification by the recrystallization method, and the methyl esterification and hydrolysis of the reaction product with methyl alcohol, and the titration with sodium hydroxide using phenolphthalein as an indicator. Table 2 shows the amount of acid anhydride (meg/f?) and the amount of acid anhydride (%) in the reaction product estimated from the amount of acid anhydride.

Theoretical values in elemental analysis are 2.8% hydrogen and 49.2% carbon.
%, which agrees well with the measurement results.

In addition, the estimated amount of acid anhydride in the reaction product is 92-96* *%, and it is easier to obtain diester dianhydride having the structure of the following two formulas, which accounts for at least 90% of the reaction product, compared to the conventional method. can be obtained.

Example 2 of the Present Invention Using the apparatus of the previous example, BTDA644.4P and ethylene glycol 62P were reacted according to the present invention in the same manner as in Example 1 using <N-N' dimethylformamide 200 (l) as the reaction solvent.

As in Example 1, the esterification reaction is quickly completed at 50-60°C (10-20 minutes) to obtain a reddish-brown transparent solution.

After vacuum distillation at 60°C ± 10 deg, vacuum drying (2
0 Hg, 80°C, 4 hours) The contents have a melting point of approximately 115
It is a brittle solid at ℃.

Absorption of esters, acid anhydrides, and carboxyl groups is observed in the infrared absorption spectrum.

Therefore, using 1610CrIl-1, which is based on aromatic residues, as an internal standard substance, a sample was prepared in which separately hydrolyzed acid was mixed, and the concentrations of anhydrous acid, ester, and free acid were each known. Acid anhydride amount by method (
%) was created to estimate the amount of acid anhydride in the reaction product.

As a result, the amount of acid anhydride in the reaction product was 92 to 96%, including acetone and MEK100f? A highly concentrated homogeneous solution of 100P or more can be obtained.

Therefore, the desired diester di-acid anhydride having the structure of the following three formulas can be easily obtained with a yield of at least 90%.

Example 3 of the present invention Using the apparatus of the previous example, BTDA644.4F and ethylene glycol 62? , N-N' A mixed solvent 2000S' containing dimethylformamide as a main component was charged into a flask, and the same operation as in Example 1 was performed.

Table 3 shows the composition of the mixed solvent and the conditions for completing the reaction.

As estimated from the infrared absorption spectrum of the acid anhydride amount of the reaction product recovered in the same manner as in Example 2, in each case 91 ~
95% and 1 for acetone and MEK100S'
A highly concentrated homogeneous solution of 0.001 or higher can be obtained.

Therefore, as in Example 2, at least 90% of the desired diester 4□ anhydride having the structure shown in formula 2.
It can be easily obtained with the above yield.

As described above, according to the present invention, it is possible to obtain a desired reaction product in high yield at a lower reaction temperature and in a much shorter time than in the reaction operations shown in conventional methods.

In addition, it is not limited by aliphatic diols, and for example, P-
It is also possible to react aromatic diols such as P'-1so-propylidene biphenol with tetracarboxylic acid anhydride.

Therefore, according to the present invention, it is possible to stably and economically obtain diester dianhydride with a low melting point, which has significantly better solubility than tetracarboxylic anhydride, compared to conventional methods, so that it can be mixed with an epoxy resin, coated, laminated, etc. It is possible to provide an epoxy resin composition that is stable, economical, and has excellent properties for applications such as adhesion.

Claims (1)

[Claims] I N-N'dimethylformamide alone or NN'
By using a mixture of dimethylformamide and either cellosolve acetate, methyl ethyl ketone, or methyl isobutyl ketone as a reaction solvent, and esterifying 1 mole of aromatic tetracarboxylic acid anhydride and 0.5 mole of diol in this reaction solvent. (However, Ar: benzene or benzophenone, R: ★301 ethylene) A method for producing a diester dianhydride, characterized by obtaining a diester dianhydride having the following structure.