JPS62522A - Production of aromatic resin and thermosetting composition used therefor - Google Patents

Abstract

PURPOSE:To obtain an aromatic resin of excellent heat resistance industrially and inexpensively, by mixing an (alkyl)naphthalene with a crosslinking agent comprising an aromatic compound at a specified ratio and forming a thermosetting substance comprising an intermediate condensation product. CONSTITUTION:A staring material consisting mainly of naphthalene and/or an alkylnaphthalene is mixed with a crosslinking agent consisting mainly of an aromatic compound having at least two hydroxymethyl or halomethyl groups at a ratio represented by the formula. This mixture is heated to 70-300 deg.C in the presence of an acid catalyst to form a thermosetting substance comprising an intermediate condensation product. In the formula, W1 is the weight of the starting material, W2 is the weight of the crosslinking agent, (a) is the MW or average-MW of the starting material, (b) is the MW or average MW of the crosslinking agent and (n) is the number of the hydroxymethyl or halomethyl groups which are bonded with 1mol of the aromatic compound as the crosslinking agent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing a heat-resistant aromatic resin, a thermosetting composition that provides the resin, and a method for producing a thermosetting substance.

[Prior art]

Conventionally, it has been known to produce aromatic hydrocarbon resins by using aromatic hydrocarbon compounds as raw materials, adding polymarine to them, and subjecting them to a heating reaction in the presence of an acid catalyst. , xylene-formalin resin is known. However, such resins do not exhibit thermosetting properties, and even when heated, they do not provide a heat-resistant cured resin. Furthermore, Japanese Patent Publication No. 37-17499 discloses a method of obtaining a cured resin by using polyaromatic hydrocarbon glycol as a raw material and reacting it with acenaphthene or formaldehyde resin of acenaphthene under an acidic catalyst. . However, this method has difficulties in producing the polyaromatic hydrocarbon glycol used as a raw material, and cannot be said to be an industrially advantageous method.

〔the purpose〕

The present invention provides a method for industrially producing an aromatic hydrocarbon resin with excellent heat resistance at low cost, and also provides a thermosetting composition and a thermosetting composition that easily produce an aromatic hydrocarbon resin with excellent heat resistance. An object of the present invention is to provide a method for producing a curable substance.

〔composition〕

The inventors of the present invention have conducted extensive research to develop a method for industrially producing aromatic resins with excellent heat resistance at low cost. When an aromatic compound having at least two hydroxymethyl groups or halomethyl groups is mixed with a raw material at a specific mixing ratio, and this mixture is subjected to a heat reaction, an infusible cure with excellent heat resistance can be obtained. It was discovered that a resin can be obtained, and the present invention was completed.

According to the present invention, as a first invention, naphthalene and/or
Alternatively, a raw material mainly composed of alkylnaphthalene and a crosslinking agent mainly composed of an aromatic compound having at least two hydroxymethyl groups or halomethyl groups are combined using the relational formula % (where vl is the raw material weight, w2 is the weight of the crosslinking agent,
a is the molecular weight or average molecular weight of the raw material, b is the molecular weight or average molecular weight of the crosslinking agent, n is the number of hydroxymethyl groups or halomethyl groups bonded to 1 mole of the aromatic compound as the crosslinking agent, and 2 or more is an integer), and this mixture is heated to 70 to 300°C in the presence of an acid catalyst to produce a thermosetting substance consisting of an intermediate condensation reaction product of the mixture. A method for producing a thermosetting aromatic resin is provided, and as a second invention, a raw material containing naphthalene and/or alkylnaphthalene as a main component and an aromatic compound having at least two hydroxymethyl groups or halomethyl groups are provided. The crosslinking agent as the main component is mixed in a proportion that satisfies the relational formula % (in the formula, W□, W2.a, b, and n have the same meanings as above), and this mixture is mixed in the presence of an acid catalyst. under,
A method for producing a heat-resistant aromatic resin is provided, which is characterized by heating to 70 to 350°C to produce an infusible cured product, and as a third invention, a method for producing a heat-resistant aromatic resin comprising naphthalene and/or alkylnaphthalene as a main component. a mixture of a raw material, a crosslinking agent whose main component is an aromatic compound having at least two hydroxymethyl groups or halomethyl groups, and an acid catalyst, or an intermediate condensation reaction product thereof; A thermosetting composition is provided, characterized in that the crosslinking agent is present in a proportion that satisfies the relational formula % (wherein vl, v2, a, b and n have the same meanings as above). Ru.

The thermosetting composition of the present invention can be heated to produce an infusible condensed polycyclic polynuclear aromatic resin (hereinafter referred to as C0PN) with excellent heat resistance.
(referred to as A resin). This C, OP N A resin is a heat-infusible aromatic hydrocarbon polymer substance having a basic structure in which naphthalene rings are bonded via methylene bonds through one or more aromatic rings.

When the thermosetting composition of the present invention is heat-cured, the aromatic compound having a hydroxymethyl group or a halomethyl group acts as a crosslinking agent to condense (crosslink) naphthalene rings and polymerize it. During the reaction, when a crosslinking agent having a hydroxymethyl group is used, water is produced as a by-product, and when a cross-linking agent having a halomethyl group is used, hydrogen halide is produced as a by-product. Since this reaction is promoted by an acid catalyst, the curing reaction mechanism is considered to be based on a cationic reaction mechanism.

The cured product (solidified product) obtained from the thermosetting composition of the present invention has a structure in which naphthalene rings are randomly crosslinked with crosslinking groups, and is heated at 120°C for 2 hours.
The yield of this cured product, which becomes infusible after about 0 hours, is usually 2 to 3% higher than the theoretical yield calculated as if it were produced by a dehydration reaction. This is thought to be because the moisture generated by the reaction is not yet completely removed from the system in the initial stage of curing, and because the crosslinking reaction is not completely completed. This cured product becomes a completely cured product by heating to a temperature of 200° C. or higher.

The cured product after this post-curing treatment is hard and has extremely high heat resistance. For example, according to the results of thermogravimetric analysis at a heating rate of 10°C/min, the product obtained by post-curing at 200°C for 1 hour has a temperature of 480°C even in air.
There is no significant weight loss up to ℃. This post-cured product is an electrical insulator whose resistance value cannot be measured with a normal digital tester.

C0P obtained from the curing reaction of the thermosetting composition of the present invention
The structure of NA resin is outlined above, but
Next, the influence of various factors on the component composition of the composition of the present invention, its precondensation reaction, and its curing reaction will be explained.

(1) Raw material The raw material used in the present invention is naphthalene and/or alkylnaphthalene, or a mixture containing these as main components. Examples of raw materials consisting of mixtures containing naphthalene and/or alkylnaphthalene as main components include naphthalene fractions fractionated from coal-based or petroleum-based hydrocarbon oils.

In the present invention, the reaction between the raw material and the crosslinking agent is as follows:
Of course, the reaction can be carried out as a solution reaction using an appropriate solvent. In particular, it is meaningful to treat only the initial stages using solution reactions. However, as the molecular weight of the product increases, solubility decreases, so it is usually easier to work in the molten state without using a solvent. Comparing the reactivity of hydroxymethyl group and halomethyl group as crosslinking agents, the latter is much larger and proceeds from a lower temperature. Therefore, the latter is suitable for reactions in a solution state at low temperatures.

When a hydroxymethyl aromatic compound is used as a crosslinking agent, the reaction initiation temperature starts from approximately 70°C to 120°C.

In the present invention, naphthalene oil obtained by fractional distillation of coal tar is a preferred raw material.

(2) Crosslinking agent As a crosslinking agent, hydroxymethyl group (HOCHz-)
Alternatively, an aromatic compound having at least 2, usually 2 to 3 halomethyl groups (XCH2-1X: halogen) is used, and in this case, the aromatic compound may be a fused ring aromatic compound or a non-fused aromatic compound. Generally, those having 1 to 5, preferably 1 to 4 benzene nuclei are used. Specific examples of crosslinking agents derived from such aromatic compounds include benzene, xylene, naphthalene, anthracene, pyrene,
or poly(hydroxymethyl) compounds such as alkyl derivatives thereof, and poly(halomethyl) compounds. Further, poly(hydroxymethyl) compounds and poly(halomethyl) compounds of coal tar fractions and petroleum fractions containing the above-mentioned aromatic compounds can be used. Among the crosslinking agents used in the present invention, di(hydroxymethyl)benzene, di(hydroxymethyl)xylene and tri(hydroxymethyl)benzene are particularly preferred.

Comparing poly(hydroxymethyl) aromatic compounds and poly(halomethyl) aromatic compounds, the latter exhibit much greater reactivity and are generally more suitable for low temperature solution reactions, while the latter are better suited for high temperature solution reactions. The former is suitable for solvent reactions.

When obtaining the C0PNA resin of the present invention, in the poly(hydroxymethyl) aromatic compound and poly(halomethyl) aromatic compound used as a crosslinking agent, the aromatic nucleus thereof is more likely to be a condensed polycyclic aromatic nucleus than a benzene nucleus. Poly(hydroxymethyl) compounds and poly(halomethyl) compounds, which are condensed polycyclic aromatic compounds such as di(hydroxymethyl)naphthalene and di(halomethyl)naphthalene, are preferable in terms of reactivity, and therefore serve as preferable crosslinking agents.

(3) Crosslinking agent / raw material molar ratio When using a 2-substituted crosslinking agent, if the crosslinking agent / raw material molar ratio is set to 0.5, a dimer will be produced, resulting in a product with a low melting point, and 0.5. As the value exceeds 5 and approaches 1.75, the curing speed becomes faster and the strength of the cured product increases. Start giving things.

When a complex mixture such as naphthalene oil is used as a raw material, its average molecular weight is useful as a criterion for determining the amount of crosslinking agent mixed. Summarizing a lot of experience, if average molecular weight is used, the effects of the crosslinking agent/source material molar ratio described above still apply to mixtures such as naphthalene oil. If this relationship is expressed in terms of mixed weight rather than molar ratio, as the average molecular weight increases, the weight of the crosslinking agent to be mixed will decrease in inverse proportion. Taking the case where a disubstituted product is used as a crosslinking agent as an example, in order to obtain a homogeneous and strong cured product, the weight ratio of the raw material and the crosslinking agent must satisfy the following relational expression. That becomes a requirement.

(Ilz/Vz)X(a/b)=0.55~3.0 (
Preferably 0.75 to 2.0) In the above formula, wl is the weight of the raw material, v2 is the weight of the crosslinking agent, a is the molecular weight or average molecular weight of the raw material, and b is the molecular weight or average molecular weight of the crosslinking agent.

Generally speaking, when using a crosslinking agent with n reactive groups (hydroxymethyl group or halomethyl group), in order to obtain a homogeneous and strong cured product, the raw material mixing ratio should be determined according to the following relational expression: Satisfaction becomes a requirement.

1, I X 1/n≦(V 2 /W 1)
/b) ≦6 In order to obtain the desired cured solid product, as mentioned above, the proportion of the crosslinking agent used has a minimum value corresponding to the number of reactive groups that the crosslinking agent has, and in the present invention, the following relational expression % The proportion of crosslinking agent used when the formula % is satisfied is defined as the minimum crosslinking proportion value of the crosslinking agent. At a crosslinker proportion below this value, only the initial curing reaction is carried out, and a crosslinker proportion above this value is required to obtain the desired cured solid.

(4) Selection of curing reaction temperature ``It is more advantageous in terms of reaction temperature to use a poly(halomethyl) aromatic compound as a crosslinking agent and a Lewis acid such as aluminum chloride as a catalyst. In general, the temperature is 50°C or higher, preferably 70°C or higher. However, some poly(halomethyl) aromatic compounds are highly toxic, and there are disadvantages in terms of equipment design and operation, such as the generation of hydrogen halide as a result of the reaction.

A poly(hydroxymethyl) aromatic compound is used as a crosslinking agent,
When carried out without solvent using a protonic acid as a catalyst, one reaction starts at around 70°C and becomes noticeable at around 120°C. In this case, the progress of the reaction is accompanied by the generation of water vapor and an increase in the viscosity of the reactants. In order to obtain a dense, pore-free product, a lower reaction rate is preferable, and the reaction can be accelerated by increasing the temperature.

The resulting solid becomes porous.

Since the reactivity varies depending on the type of raw material and crosslinking agent, and is also influenced by the crosslinking agent/raw material molar ratio, the appropriate reaction temperature also differs depending on the type and composition of the raw material. The heating temperature to obtain an infusible cured product is
Generally from 70℃ to 300℃1 preferably from 110℃
A suitable temperature is 250°C. In order to obtain a dense, pore-free product, it is better to cure, in particular using a heating temperature of 100 to 150°C, followed by a further post-curing treatment at 200°C or higher.

Regarding the reaction treatment temperature, another thing to consider is that the temperature to be selected differs depending on the purpose of the reaction treatment. When using the composition of the present invention, a final heat-resistant resin molded product can be obtained directly from the composition, and an intermediate condensation reaction product (B-stage resin) that still has meltability can be produced.

After molding, this is sometimes subjected to heat treatment (hardening treatment) again to obtain an infusible, heat-resistant cured product. In principle, the B-stage resin can be prepared by stopping the reaction before an infusible cured product is reached, or by reducing the molar ratio of the crosslinking agent to the raw material to less than the minimum crosslinking ratio. reach your goal. In this case, the product is still in a molten state, so unlike when directly producing a cured product, even if the reaction temperature is high and bubbles are generated frequently, this will not cause any problems. . Therefore, when curing an intermediate condensation reaction product, the possible temperature range is wider on the high temperature side compared to when directly producing a cured product.

(5) Selection of catalyst As the reaction catalyst, either Lewis acid or protonic acid can be used. Therefore, the selection should be made depending on the raw material composition and the reaction method.

When using a solution method using a poly(halomethyl) aromatic compound as a crosslinking agent, a Lewis acid such as aluminum chloride may be suitable; when using a poly(hydroxymethyl) aromatic compound as a crosslinking agent, a protonic acid is more suitable. The preference is clear. When using the latter catalyst without a solvent, the amount of catalyst is influenced by the reactivity of the raw material and the reaction temperature. Generally, 0.2% by weight or more is required, preferably 1 to 10% by weight, based on the raw material. The upper limit of the amount added is about 7% by weight in the case of a pure naphthalene compound; addition of more than this increases the reaction rate so much that it becomes difficult to handle. Lewis acids and protonic acids include conventionally known ones, such as aluminum chloride, boron fluoride,
Various examples include sulfuric acid and organic sulfonic acids.

(6) Preparation and properties of intermediate condensation reaction product (B-stage resin) Whether the thermosetting composition is used as a binder for various composite materials or cured alone and used as a molded product, it can be used as a raw material. Rather than using the composition directly, it is more convenient to use, as a binder or molding material, an intermediate condensation reaction product in which the reaction has proceeded to some extent but has not yet resulted in an infusible cured product.

Generally, a resin precursor (intermediate condensation reaction product) at a stage of meltability and solubility before reaching an infusible cured product is called an 8-stage resin.

Broadly speaking, there are the following methods for producing B-stage C0PNA resin. One method is to heat a raw material composition containing the amount of crosslinking agent and catalyst required for final curing, and then stop the heating in a shorter reaction time than it takes to produce an infusible cured product to stop the reaction. The appropriate reaction time for this purpose varies depending on the composition of the raw material composition and the reaction temperature. The B-stage resin produced in this manner can be turned into an infusible cured product by simply heating it after molding. The next method is to heat a mixed raw material having a crosslinking agent/raw material molar ratio around the minimum crosslinking ratio value to sufficiently advance the reaction, and then add the crosslinking agent required for final curing. The advantage of this method is that there is a wide range of choices in setting the reaction temperature and reaction time in the first stage. The last method is to reduce the amount of catalyst.

This is a method of producing B-stage resin by increasing the reaction temperature. When molding and curing this B-stage resin, it is easier to harden the molded product by adding a catalyst to the resin prior to molding. Whichever method you choose,
The raw material composition when the final cured product is reached falls within the composition range described above. The reaction temperature for obtaining the B-stage resin is generally 70-300°C, preferably 90-300°C.
The temperature is 250°C.

B-stage resin of C0PNA resin is methanol, n-
Insoluble in hexane, etc. Pyridine, quinoline.

It is soluble in tetrahydrofuran, etc., but very difficult to dissolve in benzene. The B-stage resin taken out at the beginning of the reaction is
It is pasty at room temperature. As the reaction progresses, the softening temperature gradually increases. In order to use it as a binder or adhesive for various composite materials, it is easy to use one that becomes completely fluid in the temperature range of 70 to 120°C, and for a single molded product.

It is more convenient to have a melt viscosity that can be cast at 80 to 150°C after further reaction. In cases where heat molding is applied using powder.

Furthermore, those with higher melt viscosity are easier to handle. Furthermore, since the B-stage resin is soluble in various solvents as described above, it is also possible to apply it to a base material in a solution state and dry it to form it into a film. When molding B-stage resins, it is advantageous to add aggregate.

(7) Curing Treatment The thermosetting composition of the present invention can be cured by heating it to 70 to 350°C in air or in an inert gas. Although it does not dissolve at all in solvents such as methanol and hexane, it can be cured by heating it in air or in an inert gas. After passing through an infusible cured product that contains a small amount of components soluble in pyridine-5-quinoline and swells in benzene, it is completely converted into an infusible and insoluble cured product. In order to preferably produce a completely infusible and insoluble cured product from a thermosetting composition, (i) the thermosetting composition must be heated to 100 to 350°C;
(1) a method of heating at the same temperature, preferably 150 to 300°C; (ii) a curing step of heating the thermosetting composition to 100 to 200°C, preferably 110 to 150°C to cure it; and the obtained cured product. (iii) heating the thermosetting composition,
A method of continuously raising the temperature to 50 to 300° C. or the like is adopted. From the viewpoint of the ease of manufacturing the final cured product and the quality of the final cured product obtained, it is advantageous to employ the method (ii) described above. In particular, when using naphthalene oil as a raw material, if you try to cure the naphthalene oil at 100 to 200°C to convert it into a completely infusible and insoluble cured product, the naphthalene oil contains low-molecular-weight aromatic compounds with low reactivity. In many cases, it takes an extremely long time.

In such cases, naphthalene oil should be heated to 100 to 200℃.
It is advantageous to perform a post-curing treatment in which the cured product is further heated for a short time to a temperature of 150 to 350° C. after the cured product is heated at a temperature of 150 to 350°C.

〔effect〕

The composition of the present invention shown above, that is, a composition consisting of a raw material containing naphthalene and/or alkylnaphthalene as a main component, a crosslinking agent having two or more substituted functional groups, and an acid catalyst, and its intermediate condensation reaction product is characterized in that it is easy to control the structure of the resulting cured resin.

The most important feature of the C0PNA resin obtained from the composition of the present invention is that it exhibits extremely excellent heat resistance even though it is a resin that can be produced extremely easily and at low cost. When the weight change is measured with a thermobalance at a heating rate of about 10℃/min, it is 400℃ regardless of whether it is in air or an inert atmosphere.
Weight change below °C does not exceed 2%. Further, in an inert atmosphere, a large weight loss is observed between 480°C and 600°C, but the weight loss at 550°C is only about 50%. These properties are comparable to bismaleimide resin, which is currently considered to be an excellent heat-resistant resin, and the C0PNA resin of the present invention can be called a general-purpose heat-resistant resin that has not existed before in view of the raw materials and ease of curing reaction. Can be done.

In the composition for C0PNA resin of the present invention, 100 to 3
The molded product obtained by curing at 50° C. is an electrical insulator. This characteristic is maintained even at 450°C and
The specific resistance gradually decreases at a processing temperature of ℃ or higher.

If an intermediate condensation reaction product, which is a precursor of C0PNA resin, is thinly applied to aluminum foil and cooled without heat curing, it can be peeled off from the foil and a film-like molded product can be obtained.
By heating this, a film-like C0PNA resin can be obtained. On the other hand, if the resin is heated and cured while being applied, a resin coating that is firmly bonded to the aluminum foil can be obtained. Therefore, the intermediate condensation reaction product of the C0PNA resin precursor can be used in heat-resistant baking paints.

By pouring the intermediate condensation reaction product into a mold made of silicone rubber or heat-pressing it as a powder, a molded product made of resin alone can be obtained.6According to preliminary research, intermediate condensation reaction products can be used as a binder for carbon fibers and glass fibers. Therefore, the glass fiber/C0PNA resin composite material or the carbon fiber/C0PNA resin composite material has a wide range of applications as an inexpensive insulating material with excellent heat resistance. Of course, the aggregate is not limited to these fiber materials. By adding granular, flaky, or fibrous ceramics, carbonaceous materials, or organic materials as aggregates to the composition of the present invention and curing the composition, a cured molded product with high strength can be obtained. In this case, the molded body using the carbonaceous aggregate becomes a precursor of an excellent carbon molded body as it is. When evaluating C0PNA resin as a carbon precursor with or without aggregate, the most interesting thing is that by selecting the raw material used and the molar ratio with the crosslinking agent, it is possible to use precursors with different structures quite arbitrarily. The scales are prepared.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 P-xylylene glycol (PXG) and p-toluenesulfonic acid (PTS) were blended with naphthalene in the proportions shown in Table 1, mixed in a mortar, placed in a test tube, and while flowing nitrogen gas, Heated.

Table-1 PXG/naphthalene molar ratio: 1.0 PTS: 5 wj% of the total mixture amount At a heating temperature of 120°C, it hardens to the extent that it remains slightly elastic in 20 hours, and at a heating temperature of 150°C, it becomes grayish-white after about 1 hour of heating. A completely cured resin was obtained.

For the purpose of preparing a B-stage resin, it is preferable to employ heating at a temperature of about 120°C. Further, in this heating process, naphthalene sublimes by about 20%, so the actual reacting PXG/naphthalene molar ratio is about 1.25.

Next, in the above, the B-stage resin was prepared by heating at 120°C for 3 hours, and after curing by heating at 150°C for 1 hour, the temperature was further increased to 300°C at a heating rate of 5°C/min. The temperature was raised to a higher temperature and held at this temperature for 1 hour to perform a post-curing treatment. In this way, a grayish-black cured product was obtained. In order to investigate the heat resistance of the obtained cured product, thermogravimetric analysis was performed by heating it in air at a temperature increase rate of 10°C/min.
Until then, almost no weight loss was observed, and a weight loss of about 15% occurred at 500°C. In addition, the post-curing treatment was performed 2 times.
The cured product obtained at 00°C for 1 hour also showed similar thermogravimetric analysis results, but in this case, its heat resistance was
It showed a tendency to be slightly inferior to the cured product obtained by post-curing at 300° C. for 1 hour. In addition, both of these cured products are methanol and hexane.

It showed insolubility in solvents such as tetrahydrofuran, pyridine, and quinoline.

Example 2 In Example 1, solid fine powder of the B-stage resin (intermediate condensation reaction product) obtained by heating at 120°C for 3 hours was uniformly coated on the surface of carbon fiber paper, and carbon was further applied on the coated surface. The fiber papers were stacked and heated under a press pressure of 80 kg/al in steps of 110°C, 130°C, and 160°C for a total of 100 minutes, and then the molded body was removed from the press. The obtained molded body was then post-cured at 300° C. for 1 hour. In this way, a carbon fiber C0PNA resin composite with excellent heat resistance and mechanical strength could be obtained.

Claims (1)

[Scope of Claims] (1) A relationship between a raw material mainly composed of naphthalene and/or alkylnaphthalene and a crosslinking agent mainly composed of an aromatic compound having at least two hydroxymethyl groups or halomethyl groups. Formula 1.1×1/n≦(W_2/W_1)×(a/b)≦6
×1/n (where W_1 is the weight of the raw material, W_2 is the weight of the crosslinking agent, a is the molecular weight or average molecular weight of the raw material, b
represents the molecular weight or average molecular weight of the crosslinking agent, n is the number of hydroxymethyl groups or halomethyl groups bonded to 1 mole of the aromatic compound as the crosslinking agent, and is an integer of 2 or more). A method for producing a thermosetting aromatic resin, which comprises heating this mixture to 70 to 300°C in the presence of an acid catalyst to produce a thermosetting substance consisting of an intermediate condensation reaction product of the mixture. (2) The method according to claim 1, wherein the crosslinking agent is di(hydroxymethyl)benzene. (3) A raw material containing naphthalene and/or alkylnaphthalene as a main component and a crosslinking agent containing an aromatic compound having at least two hydroxymethyl groups or halomethyl groups as a main component using the relational formula 1.1×1 /n≦(W_2/W
_1)×(a/b)≦6×1/n (where W_1 is the weight of the raw material, W_2 is the weight of the crosslinking agent, a is the molecular weight or average molecular weight of the raw material, and b is the molecular weight or average of the crosslinking agent. n is the number of hydroxymethyl groups or halomethyl groups bonded to 1 mole of the aromatic compound as a crosslinking agent, and is an integer of 2 or more. 1. A method for producing a heat-resistant aromatic resin, which comprises heating at 70 to 350° C. in the presence of a heat-resistant aromatic resin to produce an infusible cured product. (4) heating the mixture to 70 to 300°C in the presence of an acid catalyst to produce a thermosetting substance consisting of an intermediate condensation reaction product of the mixture; The method according to claim 3, which comprises a step of heating to 100 to 200°C to produce an infusible cured product, and a post-curing step of heating the cured product to 150 to 350°C. (5) The method according to claim 4, wherein the step of producing the infusible cured product is carried out in the presence of aggregate. (6) The method according to any one of claims 3 to 5, wherein the infusible cured product is substantially solvent-insoluble. (7) Using the relational formula (W_2/W_1) x (a /b)≦0.5 (where W_1 is the weight of the raw material, W_2 is the weight of the crosslinking agent, a is the molecular weight or average molecular weight of the raw material, and b is the molecular weight or average molecular weight of the crosslinking agent). After the mixture is heated and reacted at 70 to 300°C in the presence of an acid catalyst, the crosslinking agent is added to the obtained product according to the relational expression 0.55≦(W_2/W_1)×( a/b)≦3.0(
In the formula, W_1, W_2, a and b have the same meanings as above. (8) A mixture or intermediate condensation of naphthalene and/or a raw material mainly composed of naphthalene, a crosslinking agent mainly composed of an aromatic compound having at least two hydroxymethyl groups or halomethyl groups, and an acid catalyst The relationship between the raw material and the crosslinking agent in the mixture is 1.1×1/n≦(W_2/W_1)×(a/b)≦6
×1/n (where W_1 is the weight of the raw material, W_2 is the weight of the crosslinking agent, a is the molecular weight or average molecular weight of the raw material, b
represents the molecular weight or average molecular weight of the crosslinking agent, and n is the number of hydroxymethyl groups or halomethyl groups bonded to 1 mole of the aromatic compound as the crosslinking agent, and is an integer of 2 or more). A thermosetting composition characterized by: (9) The composition according to claim 8, wherein the mixture or intermediate condensation reaction product thereof is combined with aggregate.