JP3128152B2 - Epoxy resin curing agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin curing agent, and more particularly, to an epoxy resin curing agent containing two kinds of alicyclic carboxylic anhydrides.

[0002]

BACKGROUND OF THE INVENTION The use of alicyclic dicarboxylic anhydrides as epoxy resin curing agents has been known in the art. For example, hexahydrophthalic anhydride is currently widely used as an epoxy resin curing agent. In addition, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride (Japanese Patent Publication No. 39-14521), norbornanedicarboxylic anhydride or methylnorbornanedicarboxylic anhydride (Japanese Patent Publication No. No. 47891) is known.

However, these dibasic acid anhydrides including hexahydrophthalic anhydride, which is widely used, have a problem that the heat resistance of the cured product is insufficient.

[0004] In recent years, the technology of electronic devices and the like has been advanced, and the demand for heat resistance has been increasing. Therefore, acid anhydride-based curing agents such as pyromellitic anhydride and benzophenonetetracarboxylic anhydride have been developed. Was done. However, cured products obtained using these materials are excellent in heat resistance, but have a disadvantage in operation that the melting point of the curing agent is high and mixing with an epoxy resin is difficult.

Further, a novel compound, 5- (2,4-dioxotetrahydro-3-furanylmethyl) norbornane-2,3-dicarboxylic anhydride, previously filed by the present inventors (Japanese Patent Application No. 3-15763). Is easy to handle and gives a cured product with excellent heat resistance as an epoxy resin curing agent. However, since the cured product is hard and brittle, its mechanical properties such as bending strength are slightly inferior.

Therefore, an object of the present invention is to provide an epoxy resin curing agent in which the above-mentioned disadvantages are improved.

[0007]

The present invention relates to (A) 5- (2,4-dioxotetrahydro-3-furanylmethyl) norbornane-2,3-dicarboxylic anhydride (hereinafter, referred to as:
HMNTC), and (B) methyltetrahydrophthalic anhydride (hereinafter Me
(May be abbreviated as THPA).

First, the component (A) will be described. The HMNTC used in the present invention has the following formula (Formula 1):

[0009]

Embedded image It has the structure shown by. This compound has 5- (2,4-
It can be easily prepared by hydrogenating dioxotetrahydro-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic anhydride (hereinafter sometimes referred to as MNTC). MNTC is 5-methylenenorbornane-
2,3-dicarboxylic anhydride or 1-methylnorbornene
It can be prepared by reacting -2,3-dicarboxylic anhydride and / or 5-methylnorbornene-2,3-dicarboxylic anhydride with maleic anhydride. Here, 5-methylenenorbornane-2,3-dicarboxylic anhydride, one of the raw materials, has a very high reactivity due to having a double bond at the terminal, and easily reacts with maleic anhydride to form 5- ( Produces 2,4-dioxotetrahydro-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic anhydride. The reaction is presumed to proceed as in the following equation. This is a kind of ene synthesis, and the ene synthesis itself is described in, for example, Japanese Patent Publication No. 58-51955.

[0010]

Embedded image 5-methylenenorbornane-2,3-dicarboxylic anhydride is
5-methylnorbornene-2,3-dicarboxylic anhydride and / or
Alternatively, it can be prepared by isomerization of 1-methylnorbornene-2,3-dicarboxylic anhydride in the presence of an acid catalyst. Here, “isomerization” broadly includes structural isomerization and stereoisomerization, and does not have a narrow meaning such as geometric isomerization and positional isomerization. There are two types of 5-methylenenorbornane-2,3-dicarboxylic anhydride, endo-form and exo-form, either of which may be used. Mixtures of the two can also be used.

1-methylnorbornene-2,3-dicarboxylic anhydride and 5-methylnorbornene-2,3-dicarboxylic anhydride (hereinafter sometimes abbreviated as 1-MeNA and 5-MeNA, respectively) are known per se. It is. Each of these two acid anhydrides has two stereoisomers, an endo form and an exo form, and either of them can be used. 5-MeNA and 1-MeNA as raw materials can be produced, for example, as follows. That is, 1-methylcyclopentadiene (abbreviated as 1-MeCPD) and 2-methylcyclopentadiene
Methylcyclopentadiene (abbreviated as 2-MeCPD)
When reacted with maleic anhydride (Diels-Alder reaction), 1-MeCPD converts 1-MeNA endo form to 2-
An endo body of 5-MeNA is generated from MeCPD. 1-M
eCPD and 2-MeCPD are usually obtained as a mixture of the two, and there is no need to separate them for the purposes herein. When a mixture of 1-MeNA and 5-MeNA thus obtained is subjected to isomerization described later,
The do form produces the exo form of 5-methylenenorbornane-2,3-dicarboxylic anhydride via the exo form of 5-MeNA, while the endo form of 5-MeNA directly Produces the endo form of norbornane-2,3-dicarboxylic anhydride. Also, some 5-MeNA endo-forms are 5-MeNA e
The exo form of 5-methylenenorbornane-2,3-dicarboxylic anhydride is formed via the xo form. In addition, 1-MeNA endo
When the body is heated in the absence of an acid as described below, 5-MeNA
It isomerizes to the exo form, but does not further isomerize to the exo form of 5-methylenenorbornane-2,3-dicarboxylic anhydride. Methylnorbornene-2,3-dicarboxylic anhydride is generally commercially available, and it is also possible to use this.

The isomerization reaction is carried out by using 5-methylnorbornene-2,3
-It can be carried out by heating dicarboxylic anhydride and / or 1-methylnorbornene-2,3-dicarboxylic anhydride in the presence of an acid. The acid used for the isomerization reaction is not particularly limited, and various known acids can be used. Examples include Brönsted acids, for example, aromatic sulfonic acids such as benzenesulfonic acid, paratoluenesulfonic acid, and paraxylene-2-sulfonic acid; mineral acids such as sulfuric acid and hydrochloric acid; heteropolyacids such as molybdic acid; Acids and Lewis acids other than the above, such as aluminum chloride and boron fluoride. Further, an acid anhydride such as maleic anhydride can react with water to generate an acid. Therefore, even if an acid anhydride is used instead of an acid, the isomerization reaction may proceed. Preferably, a Bronsted acid is used. The amount of acid used is methylnorbornene-2,3-
About 0.01 to 5% by weight, especially about
The content is preferably set to 0.02 to 3% by weight. The temperature during the heating is preferably about 120-250 ° C, especially about 150-230 ° C. The isomerization reaction by heating can be performed in any of a batch system and a continuous system. The reaction time is preferably about 30 minutes to 10 hours, especially about 1 to 5 hours in the case of a batch system.

The reaction between 5-methylenenorbornane-2,3-dicarboxylic anhydride and maleic anhydride is such that both react with 0.5 to 5
Twice the molar ratio, preferably about 160-220 ° C. for about 2
It is performed by heating and stirring for ~ 24 hours. This reaction may be performed in the presence of any catalyst. As a catalyst,
Lewis acids such as aluminum chloride and boron fluoride are preferred, but not limited thereto. This reaction does not require the use of a solvent, but can be performed in any solvent. Preferred solvents include chlorobenzene, xylene, mesitylene, triethylbenzene and the like.

In the above, 1-methylnorbornene-2,3-dicarboxylic anhydride and / or 5-methylnorbornene-
2,3-dicarboxylic anhydride isomerized to give 5
It has been described that -methylenenorbornane-2,3-dicarboxylic anhydride is prepared once, and then MNTC is prepared by ene synthesis. However, this isomerization and ene synthesis may be performed as one operation. That is, 1-methylnorbornene
By heating -2,3-dicarboxylic anhydride and / or 5-methylnorbornene-2,3-dicarboxylic anhydride in the presence of maleic anhydride, isomerization and ene synthesis occur sequentially.

After the above reaction, the product is preferably subjected to a purification treatment. Purification may be performed by removing unreacted raw materials by simple distillation or the like, and then recrystallizing the obtained crude product. Recrystallization solvents include, but are not limited to, acetic anhydride and ketone solvents such as methyl isobutyl ketone.

5- (2,4-dioxotetrahydro-3-furanylmethyl) -5-norbornene obtained as described above
-HMNTC used in the present invention can be obtained by hydrogenating 2,3-dicarboxylic anhydride (MNTC).

The hydrogenation method is not particularly limited, and can be carried out by various known methods. For example, a method of performing catalytic hydrogenation on MNTC, a method of applying a combination of hydrogen iodide and red phosphorus or a combination of sodium and alcohol, and the like are included, but not limited thereto. A preferred method is hydrogenation by catalytic hydrogenation. Catalytic hydrogenation is usually
The MNTC is carried out by contacting with hydrogen while heating, preferably in the presence of a hydrogenation catalyst. Preferred catalysts include, but are not limited to, palladium, cobalt, nickel, platinum and the like. A carrier may be used in combination. The heating temperature is preferably about 80-300 ° C, more preferably about 120-250 ° C. The hydrogen pressure at the time of the hydrogenation reaction is preferably about 10 to 150 kg / cm ² G. The reaction time is preferably about 1 to 10 hours, more preferably about 2 to 6 hours. No solvent is required during the hydrogenation reaction, but the reaction raw materials and products are solid at room temperature,
In addition, a solvent such as tetrahydrofuran may be used in order to smoothly carry out the hydrogenation reaction.

The MNT obtained by the above-mentioned synthesis method
It is also possible to subject C to hydrogenation without isolation or after a simple purification operation to obtain HMNTC.

After the above reaction, the product may be subjected to a purification treatment. The purification treatment can be performed, for example, by recrystallization using a solvent such as methyl isobutyl ketone.

HMNTC can be identified by measuring means such as IR and NMR. For example, IR of the compound
, Peaks at 1770 to 1780 cm ^-1 and 1850 cm ^-1 due to C = O stretching of the carboxylic anhydride are observed. In ¹ H-NMR, four-
CH ₂ - due to peak 8H min (starting material 5- (2,4
Dioxotetrahydro-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic anhydride for 6 hours, 5-methylenenorbornane-2,3-dicarboxylic anhydride for 4 hours, 1-minute
Alternatively, only 2H is observed for 5-methylnorbornene-2,3-dicarboxylic anhydride), but the peak 6H due to six> CH— at δ 2.0 to 3.6 (starting material 5- (2,
For 4-dioxotetrahydro-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic anhydride, 5H min, 5-methylenenorbornane-2,3-dicarboxylic anhydride and 5-methylnorbornene-2,3-dicarboxylic anhydride For dicarboxylic anhydride, 4H min.
3H for methylnorbornene-2,3-dicarboxylic anhydride
Minutes are observed). On the other hand, a peak at δ 5.5 to 5.6 due to = CH- of the norbornene ring (starting material 5- (2,4-dioxotetrahydro-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic anhydride and 1H for 5-methylnorbornene-2,3-dicarboxylic anhydride
Min, 1H-methylnorbornene-2,3-dicarboxylic anhydride is observed for 2H), peak of vinylidene (5-methylenenorbornane-2,3-dicarboxylic anhydride as starting material is observed for 2H) And no methyl group peak (observed for 3H in the case of starting 1- or 5-methylnorbornene-2,3-dicarboxylic anhydride).

Next, the component (B) methyltetrahydrophthalic anhydride itself is known and can be produced by a conventionally known method. Methyltetrahydrophthalic anhydride includes isomers represented by the following formula (Formula 3). These isomers may be used alone or as a mixture.

[0022]

Embedded image (A) in the epoxy resin curing agent of the present invention and
The preferred compounding ratio of (B) is (A) 95 to 5 parts by weight.
(B) 5 to 95 parts by weight, more preferably (A) 80 to 5 parts by weight and (B) 20 to 95 parts by weight. When (A) is less than 5 parts by weight, the heat resistance of the cured product is not so much improved, and when it exceeds 95 parts by weight, the heat resistance is high but the mechanical strength is reduced.

The epoxy resin curing agent of the present invention comprises the component (A)
And (B). For example, a method of mixing by dry blending or a method of heating and melt-mixing can be used. Further, the components (A) and (B) may be separately added to the epoxy resin and mixed.

The epoxy resin which can be cured by using the epoxy resin curing agent of the present invention is a compound having two or more epoxy groups in a molecule, for example, a polyhydric phenol such as bisphenol A or 1,4-butanediol. Polyglycidyl ethers of polyhydric alcohols such as phthalic acid, polyglycidyl esters such as hexahydrophthalic acid, amines, amides and compounds having a heterocyclic nitrogen base N-
Glycidyl derivatives, alicyclic epoxy resins, phenol novolak epoxy resins, orthocresol novolak epoxy resins, and the like.

The curing agent is preferably blended so that the acid anhydride groups are in an amount of 0.3 to 1.5 moles, more preferably 0.7 to 1.2 moles, per equivalent of the epoxy group of the epoxy resin. Is preferred.

The above-mentioned curing agent and epoxy resin can be mixed by an appropriate means, and can be cured preferably at 50 to 200 ° C. For example, at 80-120 ° C for 1-3 hours, then 150-180
It is particularly preferred to cure at 10 ° C for 10 to 20 hours.

Further, the epoxy resin composition containing the epoxy resin curing agent of the present invention can be cured as it is, but it is possible to cure tertiary amine, tertiary amine salt, quaternary ammonium salt, imidazole, metal salt and the like. It is preferable to use an accelerator together since the curing time can be shortened.

The epoxy resin cured composition of the present invention may contain, in addition to the above components, conventional additives such as asphalt, quartz powder, mica, glass fiber, cellulose, talc, clay, kaolin, bentonite, calcium carbonate, Fillers such as metal powders such as hydrated alumina or aluminum, dyes or pigments, molding lubricants, flame retardants (antimony trioxide, red phosphorus, etc.), organic solvents (eg, xylene, toluene,
Methyl ethyl ketone, methyl isobutyl ketone, etc.).

The cured epoxy resin composition of the present invention can be used as a material for heat-resistant casting or molding or as a paint, a varnish for lamination or impregnation.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0031]

EXAMPLES In the following examples,% and parts refer to% by weight and parts by weight, respectively.

[0032]

Reference Example 1 A reflux condenser, a thermometer, and a stirrer were provided.
In a 500 ml four-necked flask, 300 g of endo-methylnorbornene-2,3-dicarboxylic anhydride (consisting of 58.5% of 1-methyl and 41.5% of 5-methyl) and 0.15 g of paratoluenesulfonic acid Was introduced and stirred at 180 ° C. for 3 hours to cause a reaction. Simple distillation yielded 287 g of a pale yellow clear liquid separated from the catalyst and heavy by-products.
Analysis of the composition of this liquid by gas chromatography showed that 8.8% of endo-5-methylenenorbornane-2,3-dicarboxylic anhydride, 63.5% of exo-5-methylenenorbornane-2,3-dicarboxylic anhydride, And 27.7% of unreacted methylnorbornene-2,3-dicarboxylic anhydride. The structure of the product was identified by infrared absorption spectrum (IR), ¹ H-NMR and the like. For example, in the IR of the compound, 1770-1780 cm ^-1 and 1850 cm
^{At -1} , a peak due to C = O stretching of the carboxylic anhydride was observed. Further, in ¹ H-NMR, δ 4.8 to 5.
2 shows a peak attributable to H ₂ C = C <(this peak is not observed in the starting material methylnorbornene-2,3-dicarboxylic anhydride), while a peak attributable to —CH ₂ — at δ 1.8 corresponds to a peak 4H. (2H min in the starting material), δ 2.8-3.6
A peak due to a proton bonded to the tertiary carbon atom of the norbornane ring was observed. = CH on norbornene ring
No peak due to-was observed.

Next, 270 g of the pale yellow transparent liquid obtained above and 294 g of maleic anhydride were placed in a 1000 ml four-necked flask equipped with a reflux condenser, a thermometer and a stirrer.
Stirred at 80 ° C. for 6 hours. Next, simple distillation was performed under a pressure of 5 mmHg until the kettle temperature reached 180 ° C., and unreacted 5-methylenenorbornane-2,3-dicarboxylic anhydride and methylnorbornene-2,3-dicarboxylic anhydride were obtained. After removal of the maleic anhydride, 126 g of product were obtained.

The structure of this compound was identified by infrared absorption spectrum (IR) and ¹ H-NMR. For example, in the IR of the compound, 1770-1780 cm ^-1 and 1850
At cm ⁻¹ , a peak due to C ＝ O stretching of the carboxylic anhydride was observed. In ¹ H-NMR, δ 1.8 to
Three -CH ₂ 2.2 - peak 6H fraction resulting from (2H minutes in 1- or 5-methyl-norbornene-2,3-dicarboxylic acid anhydride starting material, 5-methylene-2,3-dicarboxylic anhydride Is only observed for 4H), but δ
2.8 to 3.6, 5H peaks due to five> CH— (4H min for the starting materials 5-methylenenorbornane-2,3-dicarboxylic anhydride and 5-methylnorbornene-2,3-dicarboxylic anhydride, Only 1H is observed in 1-methylnorbornene-2,3-dicarboxylic anhydride), and a peak 1H due to = CH- of the norbornene ring is observed in δ 5.5 to 5.6, while a peak of a methyl group is observed. (Observed for 3H in the starting 1- or 5-methylnorbornene-2,3-dicarboxylic anhydride) and the peak of vinylidene (2H in the starting 5-methylenenorbornane-2,3-dicarboxylic anhydride). Min observed) was not observed. From these results, it was found that the product was 5- (2,4-dioxotetrahydro-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic anhydride.

In a 500 ml autoclave equipped with a stirrer, 120 g of the product obtained above and 2.4 g of palladium catalyst
Was charged with tetrahydrofuran 120g of (5% by weight of metallic palladium supported) and as a solvent, after replacing the inside of the autoclave with hydrogen, and heated to 120 ° C. under a hydrogen pressure of 80kg / cm ² G, 4 hours hydrogen under stirring An addition reaction was performed. After completion of the reaction, the catalyst was removed by filtration under reduced pressure. Then, the mixture was gradually heated at normal pressure to raise the temperature to 150 to 170 ° C. (it becomes a solid if not heated), and normal pressure distillation was performed. The solvent tetrahydrofuran was completely distilled off under reduced pressure, and 112 g
Was obtained. The results of analysis of this product are shown in Table 1.

[0036]

[Table 1]

From the above, the product of the present example was found to be 5- (2,4-
Dioxotetrahydro-3-furanylmethyl) norbornane-2,3-dicarboxylic anhydride.
The product before hydrogenation, 5- (2,4-dioxotetrahydro
-3- Furanylmethyl) -5-norbornene-2,3-dicarboxylic anhydride had an iodine value of 88.2. The reduction of the iodine number to 2.6 in the product after hydrogenation supports the above conclusion.

[0038]

Example 1 The final product (HMN) obtained in the reference example
TC) and 30 parts of methyltetrahydrophthalic anhydride (MeTHPA, a mixture of a 3-methyl form and a 4-methyl form;
Trademark: Pentahard 5000, manufactured by Tonen Chemical Co., Ltd.) 70
The parts were placed in an oven at 100 ° C. and mixed by heating to obtain an epoxy resin curing agent.

Next, an epoxy resin (trademark; Epicoat 8)
28, 100 parts of Yuka Shell Co., Ltd.), 85 parts of the epoxy resin curing agent obtained above, and 0.5 parts of 2-ethyl-4-methylimidazole (manufactured by Shikoku Chemicals) as a curing accelerator at room temperature. did. This composition was cured at 100 ° C. for 2 hours and subsequently at 170 ° C. for 15 hours to obtain a cured product. With respect to this cured product, the heat distortion temperature (HDT) and the bending strength were measured in accordance with JIS K6911. Table 2 shows the results.

[0040]

Examples 2 to 4 and Comparative Examples 1 and 2 The curing reaction was carried out under the same conditions as in Example 1 except that the composition and amount of the epoxy resin curing agent were as shown in Table 2. Was. About the obtained hardened | cured material, heat distortion temperature (HDT) and bending strength were measured like Example 1. FIG. Table 2 shows the results.

[0041]

[Table 2]

From Table 2, it can be seen that the epoxy resin curing agents of Examples 1-4 containing both HMNTC and MeTHPA are Me
Heat resistance is improved compared to Comparative Example 1 using THPA alone, and Comparative Example 2 using HMNTC alone was used.
It can be seen that the mechanical strength is improved as compared with.

[0043]

The cured product using the epoxy resin curing agent of the present invention has excellent heat resistance and mechanical strength.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroshi Ueno 1-3-1, Nishitsurugaoka, Oi-machi, Iruma-gun, Saitama Prefecture (56) References JP-A-55-98223 JP-A-3-243617 (JP, A) JP-A-3-252418 (JP, A) JP-A-3-277622 (JP, A) JP-A-4-202419 (JP, A) JP-A-5-205 202019 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 59/42

Claims (2)

(57) [Claims] (A) 5- (2,4-dioxotetrahydro-3-)
An epoxy resin curing agent comprising (furanylmethyl) norbornane-2,3-dicarboxylic anhydride and (B) methyltetrahydrophthalic anhydride. 2. The epoxy resin curing agent according to claim 1, wherein (A) and (B) are contained in a weight ratio of 5:95 to 95: 5.