JPS5918393B2 - Method for producing liquid dibasic acid anhydride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing liquid dibasic acid anhydrides that are stable even at 0°C, and more specifically, 3-methyl-delta-4-tetrahydrophthalic anhydride and 4-methyl-delta-4-tetrahydrophthalic anhydride. The present invention relates to a method for producing a liquid dibasic acid anhydride at 0° C., which comprises heat-treating a mixture of 4-tetrahydrophthalic anhydride in the presence of an acidic ion exchange resin.

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 can be easily carried 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 it has characteristics such as easy mixing of filler into the mixture.

For example, 3-methyl-delta-4-tetrahydrophthalic anhydride (hereinafter abbreviated as 3Me-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 delta-4-tetrahydrophthalic anhydride and its derivatives, sulfuric acid, phosphoric acid, P2O5, PC5, Po
It is known that the reaction is carried out under conditions of 70°C to 230°C using an inorganic acid such as Cl3 as a catalyst.

However, under these conditions, the catalyst and acid anhydride may react and form undesirable products, resulting in purification by distillation to remove catalyst residues and by-products. According to Japanese Patent Publication No. 43-13455, a silica-alumina catalyst is used at 180 to 250°C.
under the conditions of 5 or using an acidic ion exchange resin.
There is also known a method of performing an isomerization reaction under conditions of 0 to 150°C to obtain a liquid dibasic acid anhydride.

This method 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 when using an acidic ion conversion resin, but it still requires a reaction temperature of 100°C or higher. Otherwise, it will not be possible to obtain a liquid product, making it impossible to prevent the expensive acidic exchange resin from deteriorating, and causing problems such as coloring of the product. Furthermore, according to JP-A-51-1447, when an aromatic hydrocarbon or a chlorinated hydrocarbon is present as a diluent when using a strongly acidic ion exchange resin as a catalyst, the reaction is slower than in a solvent-free system. It is stated that a liquid product can be obtained even under these conditions.

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 has overcome these drawbacks of the prior art and has developed a new method that takes advantage of the advantages seen when using acidic ion exchange resins, namely, fewer by-products and ease of catalyst removal after the reaction. As a result of intensive studies to develop a method that can be used as The present inventors have discovered that this can be efficiently obtained, and have completed the present invention.

In other words, the main purpose of the present invention is to provide a method for efficiently producing a liquid dibasic acid anhydride with little coloring.
Another object is to provide a method for producing a liquid dibasic acid anhydride that prevents a decrease in catalyst activity and allows easy removal of the catalyst.

These objects of the present invention are 3Me-Δ4-THPA6O
~20% by weight, preferably 55-25% by weight and 4Me-
△4-THPA4O~80% by weight, preferably 45~7
5% by weight of the mixture without diluent in the presence of an acidic ion exchange resin at 50-95°C, preferably at 70-95°C.
This can be achieved by heat treatment.

In the present invention, 3Me-Δ4-THPA and 4Me-
The important requirements are to use Δ4-THPA in a specific ratio and to carry out the reaction at 50-95°C.

That is, when no diluent is used, 3Me-△4-
A liquid product cannot be obtained even if THPA and 4Me-Δ4THPA are used alone, and the same is true when they are used together in a ratio outside the range specified in the present invention. However, 3Me-Δ4-THPA and 4Me-Δ4-TH
Even when each PA is used alone, a liquid eutectic mixture can be obtained by mixing the products in the specified ratios as described above. On the other hand, by carrying out the reaction at 95° C. or lower, deterioration of the catalyst can be prevented and a product with less coloration can be obtained. However, 50
If the reaction temperature is lower than ℃, the reaction rate of isomerization is slow and it is not practical, so the reaction temperature is 50 to 95℃, preferably 70 to 95℃.
A temperature of 95°C is appropriate. Other reaction conditions in the present invention are not particularly limited, but usually 3M
A mixture of e-Δ4-THPA and 4Me-Δ4-THPA is treated with nitrogen,
0.1~ under an inert gas atmosphere such as argon
This is carried out by heat treatment for 30 hours, preferably 0.5 to 5 hours.

The acidic ion exchange resin used may be any commercially available resin, such as Upper List 15 (manufactured by Rohm and Haas). It has very little coloration of less than 1 Cardner without the need for
Although a liquid dibasic acid anhydride can be efficiently obtained at a temperature of .degree. C., preferably -5.degree. C., a product with even higher purity can be obtained by distillation if desired. 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 the examples are based on weight. Example
1 In a 500 ml separable flask with a stirrer, 10 parts of acidic ion exchange resin Upper List-15 (manufactured by Rohm and Haas) and 3Me-△4-THPA (melting point 61°C) and 4Me-△4-THPA (melting point 64°C) were added. mixture 100
After replacing the mixture with nitrogen, the mixture was heated and reacted at 80° C. for 3 hours.

After the reaction, the viscosity of the isomerized products at 80° C. was measured, and all were found to be liquids with extremely low viscosities of 10 centipoise or less. Next, Reupper List-15 was removed using a glass filter to obtain an isomerized product. The results are shown in Table 1. From this result, 3Me-Δ4-THPA and 4M
It can be seen that when e-Δ4-THPA is used in a specific ratio, a liquid product can be easily obtained in a short time even at a low temperature of 80° C. compared to the conventional method, and it is also extremely less colored.

In contrast, 3Me-△4-THPA or 4Me-△
When each of 4-THPA is used alone, a low melting point isomerized product cannot be obtained, and in this case, the same effect can be obtained even if the amount of Upper List 15 is increased to 15 parts and the reaction time is extended to 5 hours. It was hot. Example 2 3Me△4- in a 500ml separable flask with a stirrer
Equivalent mixture of THPA and 4Me-Δ4-THPA 1
00 parts and heated to 70°C to form a uniform eutectic mixture.

After bringing this system to a predetermined reaction temperature, upper list 1
5 was added in a predetermined amount and allowed to react for a predetermined time. The results are shown in Table 2. From this result, it can be seen that the reaction does not proceed at 40°C, while at 100°C, it becomes undesirably colored. Example 3 A reaction was carried out in the same manner as in Example 2, except that the reaction temperature was fixed at 80° C. and the amount of Upper List 15 used and the reaction time were changed as shown in Table 3.

The results are shown in Table 3. This result shows that even when the amount of catalyst used is small, good results can be obtained by slightly extending the reaction time.

Example 4 A reaction was carried out 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.

The results are shown in Table 4. This result shows that a product with a low melting point can be obtained even under mild isomerization conditions.

Claims (1)

[Claims] 1 A mixture of 60-20% by weight of 3-methyl-delta-4-tetrahydrophthalic anhydride and 40-80% by weight of 4-methyl-delta-4-tetrahydrophthalic anhydride was added to an acidic ion exchange resin without using a diluent. 50-95 in the presence of
A method for producing a dibasic acid anhydride that is liquid at 0°C, the method comprising heating at 0°C.