JPH0694498B2 - Acid anhydride composition and curing agent composition for epoxy resin - Google Patents

Description

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

[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.

Tetrabasic acid anhydrides represented by the following general formulas (I) and (II) are already known (Japanese Patent Publication No. 2986/44, British Patent 944,721), and such acid anhydrides are The curing agent composition for an epoxy resin, which is a constituent component, provides a cured resin product having excellent heat resistance because of its high crosslink density.

(In the formula, R ¹ and R ² represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.) [Problems to be Solved by the Invention] However, the tetrabasic acid anhydride has a relatively high melting point. The workability is poor because it is high, the compatibility with the resin is low when used as an epoxy resin curing agent, and the epoxy resin begins to partially react and cure with the tetrabasic anhydride during heating and melting at high temperature. , It is difficult to obtain a homogeneous mixture.

Further, a liquid curing agent composition for an epoxy resin comprising a tetrabasic acid anhydride represented by the general formula (I) and a specific dibasic acid anhydride (JP-A-58-136619) has heat resistance and Although it provides a cured product having excellent mechanical properties, it tends to lack storage stability as a curing agent composition.

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 diligent studies to improve its storage stability, by using such an acid anhydride in combination with a specific resin, it was found that a predetermined effect was obtained, and the present invention was completed based on this finding. I arrived.

That is, the present invention provides an acid anhydride composition having improved workability while maintaining the original properties of the acid anhydride,
An object of the present invention is to provide a novel curing agent composition for an epoxy resin, which has excellent compatibility with an epoxy resin and has improved storage stability.

[Means for Solving Problems] The acid anhydride-based composition according to the present invention is a tetrabasic acid anhydride represented by the general formula (I) and / or a tetrabasic acid represented by the general formula (II). It is characterized by containing an acid anhydride (hereinafter collectively referred to as "tetrabasic acid anhydride") and an aromatic hydrocarbon-formaldehyde resin.

(In the formula, R ¹ and R ² represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.) In the present invention, the aromatic hydrocarbon-formaldehyde resin means toluene, o-, m-, p-xylene. , Ethylbenzene and the like alone or a mixture thereof and mesitylene,
Alkyl-substituted aromatic hydrocarbon-formaldehyde resin obtained by appropriately selecting an aromatic hydrocarbon or the like exemplified by isomers having 9 carbon atoms such as prodcumene or a mixture thereof and reacting this with formaldehyde Is a general term for.

As a method of preparing the acid anhydride composition according to the present invention, a method of stirring a predetermined amount of a tetrabasic acid anhydride and an aromatic hydrocarbon-formaldehyde resin under heating can be presented, but it has a predetermined effect. As long as it is not limited to this.

As the treatment conditions, it is preferable to perform the treatment at a temperature slightly higher than the melting point of the tetrabasic acid anhydride for about 10 minutes to 10 hours.

The blending ratio (weight) of both is preferably tetrabasic acid anhydride: aromatic hydrocarbon-formaldehyde resin = 99: 1 to 30:70, and more preferably 95: 5 to 50:50. When the compounding ratio of the tetrabasic acid anhydride is less than this range,
There is a tendency that the heat resistance and mechanical properties of the resin cured product obtained by applying the epoxy resin cured product composition obtained by applying the acid anhydride composition as a curing agent composition,
On the contrary, when the amount is large, the workability of the acid anhydride composition and the storage stability of the curing agent composition for epoxy resin to which this composition is applied tend to be insufficiently improved.

The curing agent composition for a novel epoxy resin according to the present invention,
The above acid anhydride composition is an essential component.

Such aromatic hydrocarbon-formaldehyde resin is 300 to 1
It is desirable that the resin has a molecular weight of about 000 and becomes a liquid at 90 ° C. or lower and has an oxygen content of 8 to 15%.
The oxygen content is a value obtained by directly analyzing oxygen or by analyzing carbon and hydrogen by elemental analysis and calculating the rest as oxygen atoms.

The presence of oxygen in the aromatic hydrocarbon-formaldehyde resin indicates that the bond between the aromatic hydrocarbon nucleus and the nucleus is an ether bond [-CH ₂ OCO _2- ] or an acetal bond [-CH ₂ (OCH ₂ ).
nOCH _2- ] or a methylol group [-CH ₂ OH] or a methoxymethyl group [-CH ₂ OC] present as a side chain of the nucleus
H ₃ ].

Such an aromatic hydrocarbon-formaldehyde resin containing an oxygen-containing group not only dissolves an acid anhydride and an epoxy resin well, but also reacts well with a tetrabasic acid anhydride in the presence of a catalyst or a slight acid catalyst. Can form an ester to reduce the crystallization temperature of the tetrabasic anhydride.

By introducing an aromatic nucleus into the tetrabasic anhydride,
The solubility of the tetrabasic acid anhydride in the curing agent composition or the epoxy resin composition is further improved, and a uniform state can be maintained for a long period of time.

Further, the curing agent composition for epoxy resin according to the present invention,
It is a composition prepared by blending other carboxylic acid anhydride as needed, and is preferably a liquid composition at 25 ° C.

Such other carboxylic acid anhydride is sufficient as long as it exhibits a predetermined effect in combination with the acid anhydride composition according to the present invention, specifically, phthalic anhydride, tetrahydrophthalic anhydride, hexahydro. Phthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic acid anhydride, dodecylsuccinic anhydride, chlorendic acid anhydride, trimellitic anhydride, polyazelaic anhydride, pyromellitic anhydride, benzophenone Tetracarboxylic acid anhydride, ethylene glycol bis (anhydrotrimellitate) and the like are exemplified, and one or more of the above 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 or mixtures thereof, are recommended.

In this case, the blending ratio (weight basis) of the acid anhydride composition according to the present invention to the liquid dibasic acid anhydride is preferably
It is from 10:90 to 70:30. When the ratio of the acid anhydride composition according to the present invention 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 the imidazoles, 2-ethyl-4-methylimidazole (hereinafter referred to as "2E4MZ"), 2-methylimidazole, 1-benzyl-3-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.

A preferable amount of the acid anhydride-based curing agent composition of the present invention to be mixed with the epoxy resin is an amount corresponding to 0.5 to 1.5 equivalents of 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 the other additives as required, asphalt, quartz powder, mica, organic fibers, inorganic fibers, talc, viscosity, kaolin, bentonite, carbonic acid. Calcium, barium sulfate, magnesium oxide, boron nitride, titanium oxide, filler such as metal powder such as hydrated alumina or aluminum powder, dye or pigment, molding lubricant, flame retardant such as antimony trioxide or red phosphorus, xylene , Materials such as toluene, methyl ethyl ketone or methyl isobutyl ketone, and other general-purpose modifiers can be added for heat- and moisture-resistant casting or molding, or
It can be used as a general or special coating material or a material for a varnish for lamination or impregnation.

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

Examples 1 to 3 (1) 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid dianhydride (hereinafter abbreviated as "TDA") in a separable flask equipped with a stirrer. ) And m-xylene-formaldehyde resin (manufactured by Mitsubishi Gas Chemical Co., Inc., trade name “Nikanol LL”) were charged and an acid anhydride composition was prepared under predetermined conditions. Table 1 shows the preparation conditions and the softening temperature of the obtained acid anhydride-based composition (composition number to). 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 acid anhydride composition obtained in (1) above as a curing agent,
After heating and mixing at 100 to 130 ° C, the mixture was cooled to around 80 ° 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 TDA has a melting point of 202 to 203 ° C. Liquid epoxy resin 100
When 80 parts by weight of TDA was mixed in parts by weight and heated and mixed according to Example 1, TDA was not dissolved and the system became cloudy. Also, 2
When the mixture was heated and mixed at 05 ° C, homogenized once, and then cooled to around 80 ° C, TDA 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 acid anhydride composition (composition number ~) and a dibasic acid anhydride liquid at room temperature in predetermined amounts, and the mixture was heated at 150 ° C for 30 minutes. Mixing is performed to prepare a curing agent composition (curing agent numbers (1) to (8)) for an epoxy resin that is liquid at room temperature, and the number of days until crystals are deposited under the temperature condition of 20 ° C. By observing,
The storage stability was evaluated. 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 In accordance with Example 4, the storage stability of the cured composition containing TDA (curing agent number (9)) was evaluated. 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 According to Example 4, 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.) are shown in Table 3. Show.

Example 12 (1) As an acid anhydride, 85% by weight of TDA and 5,6,9,10-tetracarboxytricyclo- (6.2.2.0 ^2,7 ) -dodeca-2,
An acid anhydride-based composition (compositional part) was obtained in the same manner as in Example 2 except that a mixed acid anhydride consisting of 15% by weight of 11-diene dianhydride was used. The softening temperature of this composition is 113.
It was ℃.

(2) When the compatibility of the acid anhydride-based modified component () with the liquid epoxy resin was evaluated according to Example 2, a transparent and uniform epoxy resin composition was obtained.

(3) According to Example 2, the physical properties of the cured product of the epoxy resin composition according to (2) above were measured, and the heat distortion temperature was 201 ° C and the bending strength was 11.5 kg / mm ^2. It was

Example 13 An epoxy resin curing agent composition which was liquid at room temperature was prepared according to Example 5 except that the acid anhydride composition obtained in Example 12 was used. When the storage stability of the composition at 20 ° C. was evaluated, no crystal precipitation was observed even after 50 days.

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

Epicoat 1004 (Shell Chemical Co., epoxy equivalent 925)
On the other hand, the acid anhydride composition obtained in Example 1 was used as a curing agent, and 1-cyanoethyl-2-methylimidazolium trimellitate (manufactured by Shikoku Chemicals Co., Ltd., trade name "CUREZOL 2MZ" as a curing accelerator. -CNS ") was mixed with Modaflow (manufactured by Monsanto) as a leveling agent and titanium oxide as a filler in predetermined amounts, and the mixture was pre-mixed with an extruder (Bus Co., Ltd., Cokneader PL-46 type). The mixture was melt-mixed at 100 ° C., crushed with a hammer mill, and sieved with a 200-mesh wire net to produce a powder coating.

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 for 20 minutes, and various physical properties of the baked coating film were measured. The evaluation method is shown below, and the obtained results are
Shown in the table.

Adhesion: In conformity with JIS K-5400, make a grid pattern, 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 films obtained when TDA was applied as a curing agent are also shown in Table 4 as "Reference Comparative Examples".

From the following 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 acid anhydride composition according to the present invention has a low softening temperature, and the epoxy resin effect agent composition containing the modified product as a constituent has high compatibility with the epoxy resin and is stable in storage. It has excellent properties.

 ─────────────────────────────────────────────────── --Continued from the front page Examiner Yoshihiro Fuji (56) References JP-A-58-136619 (JP, A) JP-A-61-155421 (JP, A) JP-A-63-132912 (JP, A) US Patent 4451637 (US, A) US Patent 3422076 (US, A)

Claims (3)

[Claims] 1. A tetrabasic acid anhydride represented by the general formula (I) and / or a tetrabasic acid anhydride represented by the general formula (II) and an aromatic hydrocarbon-formaldehyde resin. A featured acid anhydride composition. [In the formula, R ¹ and R ² are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ] 2. A tetrabasic acid anhydride represented by the general formula (I) and / or a tetrabasic acid anhydride represented by the general formula (II) and an aromatic hydrocarbon-formaldehyde resin. A curing agent composition for an epoxy resin, comprising an acid anhydride composition. [In the formula, R ¹ and R ² are the same or different and each represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ] 3. A curing agent composition for an epoxy resin according to claim 2, which is liquid at 25 ° C.