JPH0611780B2 - Method for producing aromatic methylene resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an aromatic methylene resin from an aromatic compound and formaldehyde. More specifically, trioxane, which is a trimer of an aromatic compound and formaldehyde, is polycondensed in the presence of a strongly acidic cation exchange resin catalyst, and contains no or substantially no oxygen atom, and about 2 to 10 aromatics. The present invention relates to a method for producing an aromatic methylene resin having a chemical structure in which a group nucleus is bonded with a methylene group.

(Prior Art) As is well known, when certain aromatic compounds are reacted with formaldehyde in the presence of an acid catalyst, an aromatic formaldehyde resin bonded with a methylene group, an ether group, an acetal group or the like is produced (for example, Molecular Chemistry, 12: 335 (1955)). This formaldehyde resin is characterized in that it has an oxygen-containing functional group such as an ether or acetal group and also has an oxygen-containing substituent such as a methylol group in the aromatic nucleus. Meta-xylene as an aromatic compound, formaldehyde resin produced using methylene and the like is already marketed as xylene resin, mesitylene resin and the like, a phenolic resin modifier, or an epoxy resin,
It is mixed with acrylic resin, polyurethane, etc. and used as an adhesive, an adhesive, etc. It is also known that if the production conditions of this formaldehyde resin are further severed, an aromatic methylene resin in which diaaralkylmethane and several aromatic nuclei are bonded by a methylene group is produced (for example, by Tadashi Yamamoto " Formaldehyde ”p. 342 (196
0)). However, in the case of a catalyst such as sulfuric acid that has been often used conventionally, the corrosion of the equipment is severe and side reactions such as sulfonation are unavoidable, and it is extremely difficult to separate and isolate the aromatic methylene resin from the catalyst, There is no industrialized case yet.

(Problems to be Solved by the Invention) The above-mentioned formaldehyde resin has excellent compatibility with other resins because it has highly reactive oxygen-containing functional groups, but has poor thermal stability because it has high reactivity. There is a drawback that.

An object of the present invention is to provide a method for easily producing an aromatic methylene resin having high thermal stability while having compatibility with other resins which is almost the same as formaldehyde resin.

(Conditions for Solving Problems) The present invention uses a solid strong acid cation exchange resin as a catalyst while using an aromatic compound and trioxane, which are raw materials similar to the formaldehyde resin, with respect to the aromatic compound. By using trioxane in an excessively small amount in terms of formaldehyde, aromatic methylene containing all or substantially no oxygen atoms, that is, containing no oxygen-containing functional group that causes thermal instability, is bonded with a methylene group. It is a method for producing a resin.

In general, the polycondensation reaction between an aromatic compound and formaldehyde is a sequential reaction that leads to an oxygen-free methylene bond through an intermediate having an oxygen-containing functional group such as methylol, ether, or acetal group, and therefore, in a normal liquid-phase catalyst, Even if a part of the aromatic methylene resin consisting only of methylene bonds is produced, it is extremely difficult to recover the whole as an aromatic methylene resin consisting only of methylene bonds.

However, it has been found that when a solid strong acid cation exchange resin is used as a catalyst, the polycondensation reaction proceeds on the solid surface, so that deoxygenation easily proceeds. Then, as a result of intensive studies on the polycondensation reaction of an aromatic compound and trioxane using a strongly acidic cation exchange resin catalyst, the present invention has been accomplished. That is, when the aromatic compound and the trioxane are reacted under the condition of the aromatic compound / formaldehyde molar ratio of 1 or more using the strongly acidic cation exchange resin as a catalyst, it is possible to obtain no reaction even under the relatively mild condition. Alternatively, an aromatic methylene resin containing substantially no oxygen atoms and about 2 to 10 aromatic nuclei bonded by a methylene group was obtained. Further, since this catalyst is a solid, it is extremely easy to separate it from the produced resin, and since the reaction conditions are mild, no corrosion of the equipment is observed. In addition, the produced aromatic methylene resin is superior in thermal stability to ordinary oxygen-containing formaldehyde resins, and exhibits the same compatibility as ordinary formaldehyde resins in compatibility tests with other resins. It was confirmed.

(Function) The aromatic compound according to the present invention means benzene, toluene,
In addition to benzene derivatives such as xylene, methylethylbenzene and trimethylbenzene, polycyclic aromatic compounds such as naphthalene and anthracene and derivatives thereof can be used. It is also possible to use a mixture in which these compounds are arbitrarily mixed. However, it is a natural result that the respective compounds have different reactivities, and the yields of the obtained resins are different even if they are reacted under the same conditions. Due to the difference in reactivity,
It does not become an aromatic methylene resin having an aromatic nucleus in the same mixing ratio as the raw material.

The formaldehyde according to the present invention theoretically takes any form as long as it forms a monomeric formaldehyde during the reaction. If necessary, formaldehyde is separately generated and dissolved in the aromatic compound as a raw material. It can also be used. However, the formaldehyde monomer is usually an extremely unstable substance, and the method using trioxane, which is a non-aqueous system that further promotes deoxygenation and is easily dissolved in the starting aromatic compound, is the best method. Trioxane, which is a trimer of formaldehyde, is a crystalline solid that is stable in air at room temperature, but it dissociates into formaldehyde monomer by the action of a strongly acidic cation exchange resin in the reaction system.

The strong acid cation exchange resin used in the catalyst of the present invention is not particularly limited as long as it has a strong acid group as a functional group, but preferably has a specific surface area of 20 to 110 m ² / g and 150 to 1
An ion exchange resin having an average pore size of 200Å and chemically and physically stable in a non-aqueous solution is preferable. For example, Amberlyst 15 (Rohm and Haas Company) is superior.

The aromatic methylene resin production apparatus for carrying out this reaction may be of any type such as a usual batch type or flow type, regardless of the shape.

The reaction conditions for producing the aromatic methylene resin of the present invention are:
Generally, the following reaction conditions can be used, though it depends on the kind of the aromatic compound as the raw material and the desired properties of the resin to be produced. Reaction temperature 50 to 150 ° C., preferably 70 to 90
C, reaction time 0.1 to 12 hours, preferably 2 to 7 hours, pressure 1 to 20 atm, preferably atmospheric pressure, molar ratio of aromatic compound / formaldehyde 1 to 10, preferably 1 to 3, aromatic compound / strong acid. Total cation exchange resin exchange capacity 1-
10, preferably about 1 to 3 can be carried out.

The produced aromatic methylene resin can be obtained by separating the catalyst, washing with water, and then removing the unreacted oil by distillation. Since the catalyst is a solid, it can be easily separated by a simple solid-liquid separation operation such as filtration. The filtrate contains a trace amount of acidic substances generated from the acid groups of the catalyst, which can be easily washed off with water. Further, even when unreacted formaldehyde remains, it can be removed simultaneously with the acidic substance by washing with water. When there is no unreacted formaldehyde, the acidic substance can be removed with a basic anion exchange resin, basic alumina or the like. Since the boiling point difference between the produced aromatic methylene resin and the unreacted raw material aromatic compound is 50 to 100 ° C., the unreacted oil is easily removed by simple distillation or a simple distillation operation such as a rotary evaporator. be able to.

The aromatic methylene resin thus produced is generally yellow to
It is a blackish brown viscous liquid, and as a result of measurement with an elemental analyzer, an infrared spectrophotometer, a nuclear magnetic resonance apparatus, etc., it has a chemical structure in which the starting aromatic compound is bound with a methylene group, and has no or substantially no oxygen atom. It became clear that it was a resin that hardly contained. In addition, when comparing the thermal stability of this aromatic methylene resin with a formaldehyde resin synthesized with a sulfuric acid catalyst from the same aromatic by a thermobalance, the former is far superior in thermal stability, It was found that there was almost no difference in compatibility with other resins.

(Examples) Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1 In a four-necked flask (internal volume 1) equipped with a stirring blade and a reflux condenser, 212 g of meta-xylene and 30 of trioxane.
g, cation exchange resin (Amberlyst 15) 100g
Was charged and reacted at a reaction temperature of 78 to 106 ° C. for 7 hours.
After the reaction was completed, the catalyst was separated by filtration, and the catalyst was washed with toluene 100
After washing with g, add 2 parts of pure water to the mixture of toluene and reaction solution.
00m was added and the aqueous layer was removed with a separatory funnel. After that, unreacted meta-xylene and toluene were removed by vacuum simple distillation (120 ° C / 10 mmHg) to remove meta-xylene methylene resin 12
3.4 g was obtained. As a result of elemental analysis, oxygen content is 0% by weight
Met. The thermogravimetric measurement results of the obtained resin are shown in FIG.
The compatibility test results for other resins are shown in Table 1.

Example 2 The same apparatus as in Example 1 was used, but a C ₉ aromatic fraction (heavy reformed oil 1
540 g of a fraction having a boiling point range of 50 to 180 ° C.), 60 g of trioxane, a cation exchange resin (Amberlyst 15)
100 g was charged and reacted at a reaction temperature of 78 to 84 ° C. for 4 hours. After the completion of the reaction, the same treatment as in Example 1 was carried out to obtain 239 g of a C ₉ aromatic methylene resin. As a result of elemental analysis, the oxygen content was 0.2% by weight. The results of thermogravimetric measurement of the obtained resin are shown in FIG. 2, and the results of the compatibility test with other resins are shown in Table 1.

Comparative Example 1 As a result of elemental analysis of a commercially available meta-xylene formaldehyde resin (“Nican L” manufactured by Mitsubishi Gas Chemical Co., Inc.), the oxygen content was 8.8% by weight. The results of thermogravimetric measurement are shown in FIG. 1, and the results of the compatibility test with other resins are shown in Table 1.

Comparative Example 2 In the same apparatus as in Example 1, 240 g of the same C ₉ aromatic fraction as in Example 2, 284 g of commercially available 37% formalin, and commercially available 9
100 g of 7% sulfuric acid was charged and reacted at a reaction temperature of 97 to 103 ° C. for 1.5 hours. After the reaction was completed, 100 g of toluene was added, the mixture was transferred to a separating funnel, and washed repeatedly with pure water to remove the catalyst and acidic substances. Thereafter, the same operation as in Example 1 was carried out to distill 137 g of C ₉ aromatic formaldehyde resin.
Got As a result of elemental analysis, the oxygen content was 13.1% by weight. The results of thermogravimetric measurement are shown in FIG. 2, and the results of the compatibility test with other resins are shown in Table 1.

(Effect of the Invention) As is clear from the results of FIGS. 1 and 2, the aromatic methylene resin obtained in the present invention has improved heat resistance as compared with the conventional aromatic formaldehyde resin synthesized from the same aromatic compound. Has been done. Further, as seen in Table 1, in the compatibility test with other resins, the aromatic methylene resin and the aromatic formaldehyde resin show almost the same compatibility.

[Brief description of drawings]

FIG. 1 is a comparative diagram of thermogravimetric measurement results of Example 1 and Comparative Example 1, and FIG. 2 is a comparative diagram of thermogravimetric measurement results of Example 2 and Comparative Example 2.

Claims (3)

[Claims] 1. A process for producing an aromatic methylene resin containing substantially no oxygen atom, which is obtained by reacting an aromatic compound with formaldehyde in the presence of a strongly acidic cation exchange resin. 2. The method for producing an aromatic methylene resin according to claim 1, wherein formaldehyde is generated from trioxane in the reaction system. 3. A process for producing an aromatic methylene resin according to claim 2, wherein the amount of formaldehyde with respect to the aromatic compound is less than its chemical equivalent amount of trioxane.