JP3128148B2 - 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) -5-norbornene-2,3-dicarboxylic anhydride, which was previously filed by the present inventors (Japanese Patent Application No. 2-413585) is easy to handle and gives a cured product with excellent heat resistance as an epoxy resin curing agent.
Since the cured product has the property of being hard and brittle, the 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-
Epoxy containing dioxotetrahydro-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic anhydride (hereinafter abbreviated as MNTC) and (B) methyltetrahydrophthalic anhydride A resin curing agent is provided.

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

[0009]

Embedded image It has the structure shown by. This compound is obtained by reacting 5-methylenenorbornane-2,3-dicarboxylic anhydride or 1-methylnorbornene-2,3-dicarboxylic anhydride and / or 5-methylnorbornene-2,3-dicarboxylic anhydride with anhydride. It can be easily prepared by reacting with maleic acid. 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, for example, in 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. Both of these two acid anhydrides have two stereoisomers, an endo form and an exo form, and both 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
-Dicarboxylic anhydride and / or 1-methylnorbornene-2,3-dicarboxylic anhydride can be carried out by heating 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.

The structure of the compound can be identified by infrared absorption spectrum (IR), ¹ H-NMR, or the like. For example, in the IR of the compound, 1770
Peak due to C = O stretching of ~1780cm ^-1 4 and 1850 cm ^-1 in the carboxylic anhydride is observed.
Further, in ¹ H-NMR, a peak 6H due to three —CH ₂ — at δ 1.8 to 2.2 ( ¹ -M of the starting material) was obtained.
Alternatively, in the case of 5-methylnorbornene-2,3-dicarboxylic anhydride, 2H content, 5-methylenenorbornane-2,3
-Only 4H is observed with dicarboxylic anhydride)
Has a peak 5H due to five> CH- at δ 2.8-3.6 (neither 4H nor 3H is observed in the starting material) and δ 5.5-5. 6 Norubo <br/> Le Ne peak 1H fraction resulting from = CH- the down ring is observed, while the peak of the methyl group (starting material 1- or 5-
No methylhydrobornene-2,3-dicarboxylic anhydride is observed for 3 H) and no peak of vinylidene (starting material 5-methylenenorbornane-2,3-dicarboxylic anhydride is observed for 2 H).

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.

[0018]

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 such that the acid anhydride group is 0.3 to 1.5 mol, and particularly 0.7 to 1.2 mol, per 1 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, followed by 150-18
It is particularly preferred to cure at 0 ° 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 epoxy resin cured composition of the present invention can be used as a material for heat-resistant casting or molding or as a paint, laminating or impregnating varnish.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0027]

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

[0028]

[Reference Example] 5 equipped with a reflux condenser, thermometer and stirrer
In a 00 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 product structure has an infrared absorption spectrum (I
R), ¹ H-NMR and the like. For example, in the IR of the compound, peaks at 1770 to 1780 cm ⁻¹ and 1850 cm ⁻¹ due to C ＝ O stretching of the carboxylic anhydride were observed. In ¹ H-NMR, a peak attributable to H ₂ C = C <in δ 4.8 to 5.2 (this peak is not observed in the starting material methylnorbornene-2,3-dicarboxylic anhydride) has a δ 1.8 to 4H (starting material: 2H) due to —CH ₂ — and a peak due to a proton bonded to the tertiary carbon atom of the norbornane ring at δ 2.8 to 3.6. No peak due to = CH- of the norbornene ring was observed.

300 equipped with a reflux condenser, thermometer and stirrer
44.5 g of the pale yellow transparent liquid obtained above and 49.0 g of maleic anhydride were placed in a 4-ml four-necked flask at 180 ° C.
For 6 hours. Next, under a pressure of 5 mmHg,
Simple distillation was performed until the temperature reached 180 ° C to remove unreacted 5-methylenenorbornane-2,3-dicarboxylic anhydride, methylnorbornene-2,3-dicarboxylic anhydride and maleic anhydride. The product was obtained. To the crude product in the reaction vessel was added 45 g of methyl isobutyl ketone, and
After dissolving at ℃, the mixture was slowly cooled to room temperature to obtain 7.3 g of a white solid. The results of analysis of the solid are shown in Tables 1 and 2.

[0030]

[Table 1]

1) δ (unit: ppm), the value in parentheses is the area intensity expressed by the number of corresponding protons 2) By FD-MS

[0032]

[Table 2] From the above, this solid is 5- (2,4-dioxotetrahydro
-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic anhydride (MNTC).

[0033]

Example 1 30 parts of the MNTC crude product obtained in the Reference Example was mixed with methyltetrahydrophthalic anhydride (MeT
HPA, a mixture of a 3-methyl form and a 4-methyl form, trade name;
70 parts of Pentahard 5000 (manufactured by Tonen Chemical Co., Ltd.) was placed in an oven at 80 ° C. and mixed by heating to obtain an epoxy resin curing agent.

Next, an epoxy resin (trade name; Epicoat)
828, manufactured by Yuka Shell Co.) 100 parts, 85 parts of the epoxy resin curing agent obtained above, and 2-ethyl-4 as a curing accelerator.
-0.5 part of methylimidazole (manufactured by Shikoku Chemicals Co., Ltd.) was blended at room temperature. This composition was cured at 100 ° C. for 2 hours and subsequently at 170 ° C. for 15 hours to obtain a cured product. About this hardened | cured material, JISK6911
The heat distortion temperature (HDT) and the flexural strength were measured according to. Table 3 shows the results.

[0035]

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 the amount of the epoxy resin curing agent were as shown in Table 3. Was. About the obtained hardened | cured material, heat distortion temperature (HDT) and bending strength were measured like Example 1. FIG. Table 3 shows the results.

[0036]

[Table 3]

According to Table 3, the epoxy resin curing agents of Examples 1 to 4 containing both MNTC and MeTHPA are MeT
It can be seen that the heat resistance is improved compared to Comparative Example 1 using HPA alone, and the mechanical strength is improved compared to Comparative Example 2 using HPNT alone.

[0038]

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 containing (furanylmethyl) -5-norbornene-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.