JPH06104715B2 - Hardener composition for epoxy resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a curing agent composition for an epoxy resin having improved compatibility with an epoxy resin and storage stability.

[Prior Art] Generally, a cured epoxy resin has good electrical and mechanical properties, and therefore, a cast product of an electrical or electronic product,
It is applied to a wide range of applications such as impregnated products, painted products, laminates, and adhesives.

5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride (hereinafter abbreviated as "MCTC") is already used as a kind of tetrabasic acid anhydride. It is known (Japanese Patent Application Laid-Open No. 55-30406), and an epoxy resin curing agent composition containing such an acid anhydride as a constituent component has a high crosslink density, and thus provides a cured resin product having excellent heat resistance ( JP-A-56-20024).

[Problems to be Solved by the Invention] However, the tetrabasic acid anhydride is inferior in workability due to its relatively high melting point, and has low compatibility with a resin when used as an epoxy resin curing agent, Moreover, the epoxy resin begins to partially cure during heating and melting, and it is difficult to obtain a uniform cured product.

Further, a liquid curing agent composition for an epoxy resin comprising MCTC and a specific dibasic acid anhydride provides a cured product excellent in heat resistance and mechanical properties, but it is stable in storage as a curing agent composition. They tend to lack sex.

The present inventors have improved such drawbacks and improved workability by lowering the melting point, and further have compatibility with resins when applied as a component of a curing agent composition for epoxy resins and As a result of intensive studies to improve its storage stability, it was found that by treating such an acid anhydride with a specific resin, a predetermined effect was obtained, and the present invention was completed based on this finding. It was

That is, an object of the present invention is to provide a novel curing agent composition for an epoxy resin, which has excellent compatibility with the epoxy resin and has improved storage stability.

[Means for Solving Problems] A curing agent composition for an epoxy resin according to the present invention is characterized by containing MCTC modified with an alkyl-substituted aromatic hydrocarbon resin.

Here, the alkyl-substituted aromatic hydrocarbon resin (hereinafter referred to as “modified resin”) means toluene, o-, m-, p.
-Xylene, ethylbenzene or the like alone or a mixture thereof and mesitylene, pseudocumene or the like, an isomer having 9 carbon atoms such as an aromatic hydrocarbon or the like exemplified alone or a mixture thereof is appropriately selected, and this is reacted with an aldehyde. It is a general term for resins obtained at most.

Examples of applicable aldehydes include aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, aromatic aldehydes such as benzaldehyde, and heterocyclic aldehydes such as furfural.

As a method of modifying MCTC with the resin, a prescribed amount of MCTC
A method of stirring the modified resin and the modified resin under heating can be presented, but the method is not limited to this as long as a predetermined effect is exhibited.

The processing conditions are 10% above the melting point of MCTC.
It is preferable to carry out the treatment for about minutes to 10 hours.

The compounding ratio of MCTC and modified resin is MCTC: modified resin = 99: 1.
~ 30: 70 is preferable, and more preferably 95: 5 to 50:
Fifty. If the compounding ratio of MCTC is less than this range, the heat resistance and mechanical properties of the epoxy resin cured product obtained by applying the curing agent composition for the epoxy resin containing the modified product as a component tend to decrease. Yes, on the contrary, if there are many,
The improvement in storage stability of the curing agent composition for epoxy resin tends to be insufficient.

The novel epoxy resin curing agent composition according to the present invention is a composition comprising MCTC modified with an alkyl-substituted aromatic hydrocarbon resin as an essential component, and optionally other carboxylic acid anhydrides. Of these, a composition that exhibits a liquid state at 25 ° C. is preferable.

Such other carboxylic acid anhydride is sufficient as long as it exhibits a predetermined effect in combination with the modified MCTC, specifically, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride. Acid, methyl hexahydrophthalic anhydride, methyl nadic acid anhydride,
Dodecyl succinic anhydride, chlorendic anhydride, trimellitic anhydride, polyazelaic anhydride, pyromellitic dianhydride, benzophenonetetracarboxylic anhydride, ethylene glycol bis (anhydrotrimellitate) and the like are exemplified, and the above One or more acid anhydrides are used in combination.

Among them, 3-methyltetrahydrophthalic anhydride, 4-
Methyltetrahydrophthalic anhydride such as methyltetrahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, methylhexahydrophthalic anhydride such as 4-methylhexahydrophthalic anhydride, methylnadic acid anhydride, dodecenylsuccinic anhydride and Acid anhydrides that are liquid at room temperature, such as their structural isomers or stereoisomers, are recommended.

In this case, the blending ratio (weight basis) of the modified MCTC and the liquid dibasic acid anhydride is preferably 10:90 to 70:30. When the ratio of the modified MCTC exceeds the above range, a liquid composition at room temperature cannot be obtained. On the contrary, when the ratio is small, the heat resistance of the obtained cured product is insufficient.

Further, in addition to amine compounds such as tertiary amines and imidazoles, known curing accelerators such as phenols can be appropriately added to the curing agent composition.

As the tertiary amine, lauryldimethylamine, dimethylbenzylamine, dimethylaminomethylphenol, 2,4,6-tris (N, N-dimethylaminomethyl) phenol (hereinafter referred to as "DMP-30"), 1 Examples include 8,8-diazabicyclo (5,4,0) undecene-7 and the like.

Further, as imidazoles, 2-ethyl-4-methylimidazole (hereinafter referred to as "2E4MZ"), 2-methylimidazole, 1-benzyl-2-methylimidazole, 2-undecylimidazole, 2-phenylimidazole, 1-Cyanoethyl-2-ethyl-4-methylimidazole and the like are exemplified.

Further, Lewis acid salts, organic acid salts, and modified products of these amine compounds by adduct formation are also suitable compounds.

The acid anhydride type curing agent composition for epoxy resin thus obtained is bisphenol A, bisphenol F, bisphenol S, resorcinol, hexahydrobisphenol A, polypropylene glycol, neopentyl glycol, tetrabromobisphenol A, bisphenol hexafluoroacetone, etc. And a diglycidyl ether type obtained from epichlorohydrin, a diglycidyl ester type obtained from phthalic acid and the like and epichlorohydrin,
It is suitable as a known epoxy resin curing agent composition such as phenol novolac type, cresol novolac type, glycidyl amine type, cycloaliphatic type, heterocyclic type and halogenated type.

The preferable amount of the acid anhydride-based curing agent composition according to the present invention to be mixed with the epoxy resin is an amount corresponding to 0.5 to 1.5 equivalents of the acid anhydride equivalent per epoxy equivalent of the epoxy resin.

The epoxy resin composition to which the curing agent composition according to the present invention is applied, as necessary, other additives such as asphalt, quartz powder, mica, glass fiber, fibrin, talc, clay, kaolin, bentonite, carbonic acid. Fillers such as calcium, barium sulfate, magnesium oxide, boron nitride, titanium oxide, metal powder such as hydrated alumina or aluminum powder, dyes or pigments, molding oil lubricants, flame retardants such as antimony trioxide or red phosphorus, xylene. ,
Solvents such as toluene, methyl ethyl ketone or ethyl isobutyl ketone, and other general-purpose modifiers can also be added, and are used as materials for heat- and moisture-resistant casting or molding, or general or special paints, or laminating or impregnating varnishes. Can be used.

[Examples] The present invention will be described in more detail with reference to the following examples.

Examples 1 to 3 (1) MCTC and m-xylene-formaldehyde resin (manufactured by Mitsubishi Gas Chemical Co., Inc., in a separable flask equipped with a stirrer,
The product name "Nikanor LL") was charged and modified under predetermined conditions. Table 1 shows the denaturing conditions and the softening temperatures of the obtained modified products (modified product numbers ~). The softening temperature was measured by the ring and ball method.

(2) 100 parts by weight of Epicoat 828 (liquid epoxy resin, epoxy equivalent 190, manufactured by Shell Chemical Co., Ltd.) was mixed with a predetermined amount of the modified product obtained in (1) above as a curing agent, and the mixture was heated at 70 to 100 ° C
After heating and mixing with, the mixture was cooled to around 50 ° C. Next, 0.5 part by weight of DMP-30 as a curing accelerator was added and mixed, and the state of the system at that time was observed to evaluate the compatibility with the liquid epoxy resin. The results obtained are shown in Table 1.

(3) Further, the epoxy resin composition thus obtained was cured at 150 ° C. for 5 hours and then at 200 ° C. for 5 hours, and the physical properties of the cured product were measured. The evaluation methods are shown below, and the results obtained are shown in Table 1.

Heat distortion temperature: According to JIS K-6911.

Bending strength: According to JIS K-6911.

Comparative Example 1 The melting point of MCTC is 167 to 169 ° C. Liquid epoxy resin 10
When 70 parts by weight of MCTC was mixed with 0 parts by weight and heated and mixed according to Example 1, MCTC was not dissolved and the system became cloudy.
Also, when the mixture was heated and mixed at 170 ° C., and once homogenized, and then cooled to around 60 ° C., MCTC crystals were precipitated and the system likewise became cloudy. Therefore, the cured physical properties of the epoxy resin composition could not be evaluated.

Examples 4 to 11 (1) A separable flask equipped with a stirrer was charged with a predetermined amount of a predetermined alkyl-substituted aromatic hydrocarbon resin modified product (modified product number ~) and a dibasic acid anhydride liquid at room temperature, and the amount was 150
Prepare a curing agent composition for epoxy resin (curing agent numbers (1) to (8)) that is liquid at room temperature by mixing at 30 ° C for 30 minutes, and under this temperature condition at 20 ° C until crystals precipitate. The storage stability was evaluated by observing the number of days. The results obtained are shown in Table 2.

(2) The cured physical properties of the epoxy resin composition prepared by applying the thus obtained curing agent composition were evaluated.
The evaluation methods are shown below, and the results obtained are shown in Table 3.

Flexural modulus: Complies with JIS K-6911.

Pressure cooker test: 121 ℃, 2.2atm condition,
The weight increase rate after 24 hours was measured.

Dielectric loss tangent: Measured at 50 Hz according to JIS K-6911.

Comparative Example 2 The storage stability of a curing agent composition (curing agent number (9)) containing MCTC unmodified with the resin was evaluated according to Example 4. The results obtained are shown in Table 2. Further, Table 3 shows the physical properties of a cured product prepared by applying this product.

Comparative Example 3 Table 3 shows the cured physical properties of the epoxy resin composition prepared by blending RIKACID MH-700 (4-methylhexahydrophthalic anhydride: manufactured by Shin Nippon Rika Co., Ltd.).

Reference example An example of application to an epoxy powder coating is shown below.

Epicoat 1004 (Shell Chemical Co., epoxy equivalent 92
5), the modified product obtained in Example 1, 1-cyanoethyl-2-methylimidazolium trimellitate (manufactured by Shikoku Kasei Co., Ltd., trade name "CUREZOL 2MZ-CNS") as a curing accelerator, and a leveling agent Modaflow (manufactured by Monsanto Co.) and a predetermined amount of titanium oxide as a filler were mixed and pre-mixed and melt-mixed at 100 ° C. with an extruder (co-kneader PL-46 manufactured by Buss Co., Switzerland) with a hammer mill. After crushing, a powder coating was produced by sieving with a 200-mesh wire mesh.

The obtained powder coating material was applied and the zinc phosphate-treated steel plate was electrostatically coated (under an applied voltage of −50 kV, a film thickness of 60 μm). Then, baking was performed at 180 ° C. for 20 minutes, and various physical properties of the baked coating film were measured. The evaluation methods are shown below, and the results obtained are shown in Table 4.

Adhesion: In conformity with JIS K-5400, make a cross-cut, press commercially available cellophane tape on it, and peel it off (number of passes /
Go board number).

Erichsen: Depends on extrusion distance.

Impact resistance: Conforms to JIS K-5400.

The measurement condition is 1/2 inch φ × 1 kg.

Flex resistance: conforms to JIS K-5400.

The measurement condition is 4 mm × 180 °.

Boiling resistance: Visual observation of the coating film after immersion in boiling water for 3 hours.

For comparison, the physical properties of the coating film obtained when unmodified MCTC was applied as a curing agent are also shown in Table 4 as "Reference Comparative Example".

From the above results, the powder coating film obtained by applying the product of the present invention as a curing agent is excellent in flexibility, mechanical properties and the like.

EFFECTS OF THE INVENTION The modified MCTC according to the present invention has a low softening temperature, and a curing agent composition for an epoxy resin containing such a modified product as an essential component has a high compatibility with the epoxy resin and is stable in storage. It has excellent properties.

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-56-20024 (JP, A) JP-A-55-36406 (JP, A) JP-A-58-89612 (JP, A) JP-A-59- 33323 (JP, A) JP 61-78842 (JP, A) JP 62-50323 (JP, A) JP 57-84844 (JP, A)

Claims (2)

[Claims] 1. A 5- (2,5-dioxotetrahydrofuryl) -3 modified with an alkyl-substituted aromatic hydrocarbon resin.
-Methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride as an essential component, a curing agent composition for an epoxy resin. 2. A curing agent composition for an epoxy resin according to claim 1, which is liquid at 25 ° C.