JPH0559153A - Epoxy resin curing agent - Google Patents

Abstract

PURPOSE:To obtain the subject curing agent, containing a specific acid anhydride and methylnorbornenedicarboxylic anhydride and useful for molding, coating materials, etc., excellent in heat resistance and mechanical strength. CONSTITUTION:The objective curing agent containing (A) 5-(2,4- dioxotetrahydro-3-furanylmethyl)-5-norbornene-2,3-dicarboxylic anhydride expressed by the formula and (B) methylnorbornene-2,3-dicarboxylic anhydride. Furthermore, the blending ratio (A/B) of the components (A) and (B) is preferably (5/95)-(95/5) weight ratio of the components (A/B) and the curing agent is preferably blended so as to provide 0.7-1.2mol acid anhydride groups based on 1 equiv. epoxy group in the epoxy resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin curing agent, and more particularly to an epoxy resin curing agent containing two alicyclic carboxylic acid anhydrides.

[0002]

2. Description of the Related Art The use of alicyclic dicarboxylic acid anhydrides as epoxy resin curing agents is 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), norbornane dicarboxylic acid anhydride or methyl norbornane dicarboxylic acid anhydride (Japanese Patent Publication No. 62- No. 47891) is known.

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

[0004] In recent years, the demand for heat resistance has increased with the advancement of technology for electronic devices and the like, and acid anhydride type curing agents such as pyromellitic acid anhydride and benzophenonetetracarboxylic acid anhydride have been developed. Was done. However, although the cured product obtained using these has excellent heat resistance, it has a working defect that the curing agent has a high melting point and is difficult to mix with an epoxy resin.

Further, a novel compound, 5- (2,4-dioxotetrahydro-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic acid 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 is hard and brittle, mechanical properties such as bending strength are slightly inferior.

[0006] Therefore, an object of the present invention is to provide an epoxy resin curing agent in which the above-mentioned drawbacks are improved.

[0007]

The present invention provides (A) 5- (2,4-dioxotetrahydro-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic anhydride (hereinafter referred to as MNTC And (B) methylnorbornene-2,3-dicarboxylic acid anhydride (hereinafter sometimes abbreviated as MeNA).

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

[0009]

[Chemical 1] It has the structure shown by. This compound is a mixture of 5-methylenenorbornane-2,3-dicarboxylic acid anhydride, or 1-methylnorbornene-2,3-dicarboxylic acid anhydride and / or 5-methylnorbornene-2,3-dicarboxylic acid anhydride and anhydride. It can be easily prepared by reacting with maleic acid. The reaction is presumed to proceed according to the following formula. This is a kind of ene synthesis, and the ene synthesis itself is described, for example, in Japanese Examined Patent Publication No. 58-51955.

[0010]

[Chemical 2] 5-methylene norbornane-2,3-dicarboxylic acid anhydride is
5-Methylnorbornene-2,3-dicarboxylic acid anhydride and /
Alternatively, it can be prepared by isomerization of 1-methylnorbornene-2,3-dicarboxylic acid 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 or positional isomerization. Although 5-methylenenorbornane-2,3-dicarboxylic acid anhydride has two types of endo form and exo form, either of them may be used in the present invention. It is also possible to use a mixture of both.

1-Methylnorbornene-2,3-dicarboxylic acid anhydride and 5-methylnorbornene-2,3-dicarboxylic acid anhydride (hereinafter sometimes abbreviated as 1-MeNA and 5-MeNA, respectively) are known. Is. Each of these two acid anhydrides has two stereoisomers, an endo isomer and an exo isomer, and either of them can be used. 1-MeNA and 5-MeNA that are raw materials can be produced, for example, as follows. That is, 1-methylcyclopentadiene (abbreviated as 1-MeCPD) and 2-
Methylcyclopentadiene (abbreviated as 2-MeCPD)
When reacted with maleic anhydride (Diels-Alder reaction), the endo form of 1-MeNA from 2-MeCPD becomes 2-
5-MeNA endo form is produced from MeCPD. 1-M
eCPD and 2-MeCPD are usually obtained as a mixture of the two, and it is not necessary to separate the two for the purposes here. The mixture of 1-MeNA and 5-MeNA thus obtained was subjected to the isomerization described below to obtain the en
The do-form produces an exo-form of 5-methylenenorbornane-2,3-dicarboxylic acid anhydride via the 5-MeNA exo-form, while the 5-MeNA endo-form directly produces 5-methylene. The endo form of norbornane-2,3-dicarboxylic acid anhydride is produced. In addition, some 5-MeNA endo-forms have 5-MeNA e
The exo form of 5-methylenenorbornane-2,3-dicarboxylic acid anhydride is produced via the xo form. In addition, 1-MeNA endo
When the body is heated in the absence of 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 acid anhydride. Methylnorbornene-2,3-dicarboxylic acid anhydride is generally commercially available, and it is also possible to use this one.

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 Bronsted acids such as 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, and carboxylic acids such as maleic acid. Examples of the acid include Lewis acids other than the above, such as aluminum chloride and boron fluoride. Further, since an acid anhydride such as maleic anhydride can react with water to generate an acid, the isomerization reaction may proceed even if an acid anhydride is used instead of the acid. Bronsted acid is preferably used. The amount of acid used is methylnorbornene-2,3-
About 0.01 to 5% by weight, especially about about 5% by weight of dicarboxylic acid anhydride
It is preferably 0.02 to 3% by weight. The temperature during heating is preferably about 120 to 250 ° C, especially about 150 to 230 ° C. The isomerization reaction by heating can be carried out batchwise or continuously. In the case of a batch system, the reaction time is preferably about 30 minutes to 10 hours, particularly about 1 to 5 hours.

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

In the above, 1-methylnorbornene-2,3-dicarboxylic acid anhydride and / or 5-methylnorbornene-
Isomerization of 2,3-dicarboxylic anhydride to give 5 as an intermediate
-Methylene norbornane-2,3-dicarboxylic acid anhydride was made once and then MNTC was made by ene synthesis. However, this isomerization and ene synthesis may be performed as one operation. That is, 1-methylnorbornene
Isomerization and ene synthesis occur sequentially by heating -2,3-dicarboxylic acid anhydride and / or 5-methylnorbornene-2,3-dicarboxylic acid anhydride in the presence of maleic anhydride.

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

The structure of this compound can be identified by infrared absorption spectrum (IR), ¹ H-NMR and the like. For example, in the IR of the compound, 1770 to 1780
peak due to C = O stretching of the carboxylic acid anhydride in cm ^-1 and 1850 cm ^-1 is observed. Further, in ¹ H-NMR, a peak of 6 H due to three —CH ₂ — at δ 1.8 to 2.2 (the starting material 1- or 5-methylnorbornene-2,3
-Only 2H for dicarboxylic acid anhydride and 4H for 5-methylenenorbornane-2,3-dicarboxylic acid anhydride), but 5H peak due to five> CH- at δ 2.8-3.6 (starting material In each case, only 3 or 4H is observed), and a peak of 1H due to = CH- of the norbornene ring is observed at δ 5.5 to 5.6, while a peak of methyl group (1- or 5-of the starting material) is observed. Methylnorbornene-2,3-dicarboxylic anhydride is observed for 3H) and vinylidene peak (starting material 5-methylenenorbornane-2,3-dicarboxylic anhydride is observed for 2H) is not observed.

Next, the component (B) methylnorbornene-2,3-
The dicarboxylic acid anhydride itself is known and, as a starting material for synthesizing the component (A), endo isomers and exo isomers exist in each of the two structural isomers described above. In the present invention, all of these isomers can be used as the component (B).

The preferable mixing ratio of (A) and (B) in the epoxy resin curing agent of the present invention is (B) 5 to 95 parts by weight, more preferably 95 to 5 parts by weight of (A). Is
(A) 80 to 5 parts by weight, (B) 20 to 95 parts by weight. (A)
If it is less than 5 parts by weight, the heat resistance of the cured product will not be improved so much, and if it exceeds 95 parts by weight, the heat resistance will be high but the mechanical strength will decrease.

The epoxy resin curing agent of the present invention comprises the component (A)
It can be produced by mixing and (B). For example, a method of mixing by dry blending, or 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 using the epoxy resin curing agent of the present invention is a compound having two or more epoxy groups in the molecule, for example, polyhydric phenol such as bisphenol A or 1,4-butanediol. Compounds such as polyglycidyl ethers of polyhydric alcohols such as phthalic acid, polyglycidyl esters such as hexahydrophthalic acid, amines, amides and compounds with heterocyclic nitrogen bases N-
Glycidyl derivatives, alicyclic epoxy resins, phenol novolac epoxy resins, orthocresol novolac epoxy resins, and the like.

The curing agent is preferably added in such a manner that the acid anhydride group is 0.3 to 1.5 mol, and particularly 0.7 to 1.2 mol, relative to 1 equivalent of the epoxy group of the above epoxy resin. Is preferred.

The above-mentioned curing agent and epoxy resin can be mixed by an appropriate means and cured preferably at 50 to 200 ° C. For example, at 80-120 ℃ for 1-3 hours, then 150-180
It is particularly preferred that it be cured 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 a tertiary amine, a tertiary amine salt, a quaternary ammonium salt, an imidazole, a metal salt or the like is cured. It is preferable to use an accelerator together because the curing time can be shortened.

The epoxy resin curing composition of the present invention comprises, in addition to the above components, conventional additives such as asphalt, quartz powder, mica, glass fiber, fibrin, talc, clay, kaolin, bentonite, calcium carbonate, Fillers such as hydrated alumina or metal powder such as 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.) and the like.

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

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 mean% by weight and parts by weight, respectively.

[0028]

[Reference Example 1] equipped with a reflux condenser, a thermometer, and a stirrer
In a 500 ml four-necked flask, 300 g of endo-methylnorbornene-2,3-dicarboxylic anhydride (consisting of 58.5% 1-methyl and 41.5% 5-methyl) and 0.15 g paratoluenesulfonic acid were placed. Was introduced and reacted at 180 ° C. for 3 hours with stirring. Simple distillation yielded 287 g of a pale yellow, transparent liquid, which was separated from the catalyst and by-products which were heavies.
When the composition of this liquid was analyzed by gas chromatography, 8.8% endo-5-methylenenorbornane-2,3-dicarboxylic acid anhydride, 63.5% exo-5-methylenenorbornane-2,3-dicarboxylic acid anhydride, And unreacted methylnorbornene-2,3-dicarboxylic acid anhydride 27.7%. 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 to 1780 cm ^-1 and 1850 cm
A peak due to C = O stretching of the carboxylic acid anhydride was observed at ^-1 . In ¹ H-NMR, δ 4.8-5.
2 due to H ₂ C = C <(this peak is not observed in the starting material methylnorbornene-2,3-dicarboxylic acid anhydride) at δ 1.8 due to —CH ₂ — (2H for starting material) is 2.8-3.6
A peak due to the proton bonded to the tertiary carbon atom of the norbornane ring was observed at. = CH of norbornene ring
No peak due to − was observed.

300 equipped with reflux condenser, thermometer, stirrer
Put 44.5g of the pale yellow transparent liquid obtained above and 49.0g of maleic anhydride into a four-necked 4-ml flask, and place at 180 ℃.
And stirred for 6 hours. Next, under the pressure of 5 mmHg, the kettle temperature
After simple distillation until the temperature reached 180 ℃ and unreacted 5-methylenenorbornane-2,3-dicarboxylic anhydride, methylnorbornene-2,3-dicarboxylic anhydride and maleic anhydride were removed, 21.0 g of crude The product was obtained. To the crude product in the reaction vessel was added 45 g of methyl isobutyl ketone,
After dissolution at 0 ° C., the mixture was slowly cooled to room temperature to obtain 7.3 g of a white solid. The analysis results of the solid are shown in Tables 1 and 2.

[0030]

[Table 1]

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

[0032]

[Table 2] From the above, this solid was found to be 5- (2,4-dioxotetrahydro).
-3-furanylmethyl) -5-norbornene-2,3-dicarboxylic acid anhydride (MNTC) was identified.

[0033]

Reference Example 2 Volume 3 equipped with reflux condenser and stirrer
Introduce 98 g of maleic anhydride and 100 g of benzene as a solvent into a 4-liter four-necked flask, while maintaining the internal temperature at 20 to 25 ° C., a hydrocarbon fraction having the following composition obtained with a steam cracker: 14000 g Was added dropwise over 1 hour. Then, the internal temperature was gradually raised to 80 ° C., and the Diels-Alder reaction was carried out at 80 ° C. for 3 hours. Unreacted components were distilled off from the reaction product by distillation to obtain 176 g of a liquid mixture of dicarboxylic acid anhydrides. Then, the mixture of the dicarboxylic acid anhydride obtained above was added to 170
After heating for 3 hours at ℃, the stereoisomerization reaction from the endo-form to the corresponding exo-form was performed, and then purified by vacuum distillation to yield 165 g of a pale yellow transparent liquid based on the diolefin component yield. Obtained at 93%.

By analyzing the above liquid product with a gas chromatograph, the composition of endo-1-methyl-5-norbornene-2,3-dicarboxylic acid anhydride was 17.0.
%, Endo-5-methyl-5-norbornene-2,3-dicarboxylic acid anhydride is 31.7%, exo-5-methyl-5-norbornene-2,3-dicarboxylic acid anhydride is 31.5%. Yes, bicyclo [2.2.2] -5-octene-2,3-dicarboxylic acid anhydride
9.7%, 3-ethyl-Δ ⁴ -tetrahydrophthalic anhydride was 4.2% and 4-ethyl-Δ ⁴ -tetrahydrophthalic anhydride was 5.9%.

[0035]Hydrocarbons obtained with steam crackers
Fraction composition  Methylcyclopentadiene 4.6% 1,3-Cyclohexadiene 0.6% 1,3-Hexadiene 0.2% 2-Ethyl-1,3-butadiene 0.3% C₆~ C₇Olefin, paraffin 6.2% Benzene 54.6% Toluene 33.5%

[0036]

Example 1 30 parts of the crude product of MNTC obtained in Reference Example 1 and MeNA (trademark; Kayahard MCD; manufactured by Nippon Kayaku Co., Ltd .; endo-1-methylnorbornene-2,3-dicarboxylic acid anhydride) Substance 47.0% by weight, endo-5-methylnorbornene-2,3-dicarboxylic acid anhydride 17.0% by weight, exo-5-methylnorbornene-2,3-dicarboxylic acid anhydride 21.0% by weight, en
70 parts of do-norbornene-2,3-dicarboxylic acid anhydride 11.3% by weight and exo-norbornene-2,3-dicarboxylic acid anhydride 3.7% by weight are put in an oven at 80 ° C. and mixed by heating. An epoxy resin curing agent was produced by homogenizing.

Next, an epoxy resin (trademark; Epicoat 8)
28, Yuka Shell Co., Ltd.) 100 parts, 85 parts of the epoxy resin curing agent obtained above, and 0.5 parts of 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Co., Ltd.) as a curing accelerator are blended at room temperature. did. This compound was cured at 100 ° C. for 2 hours and then at 170 ° C. for 15 hours to obtain a cured product. The heat distortion temperature (HDT) and bending strength of this cured product were measured according to JIS K6911. The results are shown in Table 3.

[0038]

Examples 2 to 4 and Comparative Examples 1 and 2 Compounds were prepared in the same manner as in Example 1 except that the composition and blending amount (parts by weight) of the epoxy resin curing agent were as shown in Table 3, under the same conditions. A curing reaction was performed. The heat distortion temperature (HDT) and bending strength of the obtained cured product were measured in the same manner as in Example 1. The results are shown in Table 3.

[0039]

[Examples 5 and 6 and Comparative Example 3] Kayahard MCD was used as a reference to obtain the single yellow transparent liquid (MeNA, purity about 10).
In the same manner as in Example 1 except that the composition and blending amount of the epoxy resin curing agent were as shown in Table 3, and the curing reaction was performed under the same conditions. The heat distortion temperature (HDT) and bending strength of the obtained cured product were measured in the same manner as in Example 1. The results are shown in Table 3.

[0040]

[Table 3]

MeNA-a: Kayahard MCD MeNA-b: MeNA obtained in Reference Example 2 1) Unit: parts by weight 2) Parts by weight based on 100 parts by weight of epoxy resin 3) Unit: kg / mm ^{2 From} Table 3, Example 1 containing both MNTC and MeNA
The epoxy resin curing agents Nos. 6 to 6 have improved heat resistance as compared with Comparative Examples 1 and 3 using MeNA alone, and have improved mechanical strength as compared to Comparative Example 2 using MNTC alone. I understand that

[0042]

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

Front page continued (72) Inventor Hiro Ueno 1-3-1 Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Prefecture Tonen Corporation Research Institute

Claims (2)

[Claims] 1. (A) 5- (2,4-dioxotetrahydro-3-
An epoxy resin curing agent containing (furanylmethyl) -5-norbornene-2,3-dicarboxylic acid anhydride and (B) methylnorbornene-2,3-dicarboxylic acid anhydride. 2. The epoxy resin curing agent according to claim 1, which comprises (A) and (B) in a weight ratio of 5:95 to 95: 5.