JPS593997B2 - Method for producing liquid dibasic acid anhydride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a liquid dibasic acid anhydride that is stable even at -25°C, and more specifically, to a method for producing a liquid dibasic acid anhydride that is stable even at -25°C.
-Tetrahydrophthalic anhydride and 4-methyl-delta-4-tetrahydrophthalic anhydride are each independently heated in the presence of an acidic ion exchange resin without using a diluent, and then mixed.-25 The present invention relates to a method for producing a liquid dibasic acid anhydride at °C.

Acid anhydrides, along with amine compounds, are widely used as curing agents for epoxy resins. Among them, liquid acid anhydrides can be mixed with epoxy resins at a relatively low temperature compared to solid acid anhydrides. It is easy to carry out, there is no precipitation and separation of acid anhydride even after mixing, and it is easy to store. When using a mixture with epoxy resin, it is easy to impregnate at a relatively low temperature and pour into a mold. It is preferably used because of its characteristics such as the ease of mixing the filler into the mixture.

For example, 3-methyl-delta-4-tetrahydrophthalic anhydride (hereinafter abbreviated as 103Me-Δ4-THPA) or 4-methyl-delta-4-tetrahydrophthalic anhydride (hereinafter abbreviated as 4Me-Δ4-THPA) The liquid acid anhydride obtained by isomerizing the liquid acid anhydride is one of the acid anhydrides that are used in the market. For the isomerization of 15 delta-4-tetrahydrophthalic anhydride and its derivatives, sulfuric acid, phosphoric acid, P2O5, PCl5, Po
It is known that the reaction is carried out at 70°C to 230°C using an inorganic acid such as Cl3 as a catalyst.

However, under these conditions, the catalyst and the acid anhydride react, producing undesirable products, which require purification by distillation to remove catalyst residues and by-products. 25 Also, according to Japanese Patent Publication No. 13455/1983, silica-alumina catalysts are used at 180 to 250°C, or acidic ion exchange resins are used at 100 to 150°C.
A method is also known in which a liquid dibasic acid anhydride is obtained by carrying out an isomerization reaction under conditions of °C.

This method 30 is preferable because it suppresses the production of by-products and allows the used catalyst to be easily removed. However, this method also requires a high temperature of 180 to 250°C in the case of a silica-alumina catalyst, and a relatively low reaction temperature is sufficient if an acidic ion exchange resin is used, but it is still over 100°C. Otherwise, a liquid product cannot be obtained, so deterioration of the expensive acidic exchange resin cannot be prevented, and coloring of the product becomes a problem. Furthermore, according to Japanese Patent Application Laid-open No. 51-1447,
When an aromatic hydrocarbon or a chlorinated hydrocarbon is present as a diluent when a strongly acidic ion exchange resin is used as a catalyst, a liquid product can be obtained even under mild reaction conditions 5 compared to a solvent-free system. Are listed. However, this method has the disadvantages of poor production efficiency due to the use of a large amount of diluent, and increased equipment costs due to the need for a diluent separation step. It also has a relatively high boiling point, making it difficult to remove completely. The present inventor overcame these drawbacks of the prior art and took advantage of the advantages found when using acidic ion exchange resins, namely, fewer by-products and ease of catalyst removal after the reaction. As a result of intensive research to develop a new method, 3M
We have discovered that when e-THPA and 4Me-THPA are used together, a liquid acid anhydride with an extremely low viscosity can be efficiently obtained at a temperature of 100°C or less even in the absence of a diluent. He has completed his invention.

That is, the main purpose of the present invention is to provide a method for efficiently producing a liquid dibasic acid anhydride with little coloring, and another purpose is to provide a method for efficiently producing a liquid dibasic acid anhydride that is less colored. An object of the present invention is to provide a method for producing a liquid dibasic acid anhydride. These objects of the present invention are based on 3Me-Δ4-TH
PA and 4Me-Δ4-THPA were each independently heated at 50 to 95°C in the presence of an acidic ion exchange resin without using a diluent.
, preferably after heat treatment at 70 to 95°C, the former 5
This can be achieved by mixing in a ratio of 0 to 30% by weight and 50 to 70% by weight of the latter.

In the present invention, the treatment with acidic ion exchange resin is
Performing at 0-95°C and 3-Me-TH after treatment
An important requirement is to mix PA and 4-Me-THPA in a specific ratio.

That is, by carrying out the reaction at 95° C. or lower, deterioration of the catalyst can be prevented and a product with less coloring can be obtained, and by mixing this product in the above ratio, -
A liquid eutectic mixture can be obtained even at 25°C. Other reaction conditions in the present invention are not particularly limited, but usually 3Me-Δ4-THPA or 4
Me-△4-THPA is mixed in the presence of an acidic ion exchange resin of 1 part by weight or more, preferably 5 parts by weight or less per 100 parts by weight of the charged amount, in an atmosphere of a gas inert to the reaction such as nitrogen or argon. This is carried out by heat treatment for 1 to 30 hours, preferably 0.5 to 5 hours.

The acidic ion exchange resin used may be any commercially available resin, such as Upper List 1.
5 (manufactured by Rohm and Haas). According to the present invention, the product can be produced with very little coloration of less than 1 cardinarity without distilling the product, and moreover, it can be produced at 0°C.
A liquid dibasic acid anhydride can be efficiently obtained, preferably at -5°C, but if desired, it can be distilled to obtain a product with even higher purity.

Furthermore, since no diluent is used in the present invention, equipment costs can be reduced, production efficiency is high, and no diluent remains in the product. The present invention will be explained in more detail with reference to Examples below. Note that all parts in Examples and Comparative Examples are based on weight. Example 1 In a 500 ml separable flask equipped with a stirrer, 10 parts of acidic ion exchange resin Upper List-15 (manufactured by Rohm and Haas) and 3Me-△4-THPA (melting point 6 "C") or 4Me-△4-THPA (melting point 64) were added. ℃), and after purging with nitrogen, the mixture was heated and reacted at 8°C for 3 hours.

After the reaction, upper list 15 was removed using a glass filter, and an isomerized product of 3Me-Δ4-THPA (melting point 53
C, product 1) and an isomerized product of 4Me-Δ4-THPA (melting point 22 C, product) were obtained. Next, the obtained product 1 and the product were mixed in the ratio shown in Table 1, and the melting point and hue of the mixture were measured. The results are shown in Table 1. Example
2 3Me-△4THPA or 4Me-△ was prepared in the same manner as in Example 1 except that the amount of the acidic ion exchange resin used in Example 1 was reduced to 5 parts and the reaction time was 2 hours.
When 4-THPA was treated, 3Me- with a melting point of 53°C was obtained.
△4-THPA isomerate (product) and 4 with melting point 4FC
Me-Δ4THPA isomerate (product) was obtained.

Next, when the two products were mixed in a ratio of 40 parts of the former and 60 parts of the latter, it was found that the melting point was -25°C or less and the cardner was 1.
The following eutectic mixture was obtained. Comparative Example 1 3Me-Δ4-THPA and 4-Me-Δ4-THPA were mixed at the ratio shown in Table 2, and the melting point of the mixture was measured.

The results are shown in Table 2. This result shows that even if the two are mixed without treatment with an acidic ion exchange resin, a eutectic mixture with a low melting point cannot be obtained.

Claims (1)

[Claims] 1 3-Methyl-delta-4-tetrahydrophthalic anhydride and 4-methyl-delta-4-tetrahydrophthalic anhydride were each independently heated at 50 to 95°C in the presence of an acidic ion exchange resin without using a diluent. After heat treatment with
A method for producing a dibasic acid anhydride that is liquid at -25°C, characterized in that the latter is mixed at a ratio of 0 to 30% by weight and the latter 50 to 70% by weight.