JPH06287277A - Curing agent for epoxy resin and curing accelerator for epoxy resin - Google Patents

Abstract

(57) [Summary] [Structure] An imidazole compound and a compound represented by the general formula: (R is a hydrogen atom or a hydroxyl group, M is a hydrogen atom, an alkali metal or NH ₄ , and n is 0 to 3) A curing agent for an epoxy resin and an epoxy compound, which are obtained by reacting with a phosphonic acid Curing accelerator for resin. [Effect] When mixed with an epoxy resin, the storage stability period can be greatly extended, and the epoxy resin is suitably used for various uses.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a novel curing agent for epoxy resin and curing accelerator for epoxy resin, more specifically,
When mixed with an epoxy resin, the storage stability period (pot life) can be greatly extended, and imidazole-based epoxies suitable for use in various applications where epoxy resins are used, including epoxy resin adhesives. The present invention relates to a curing agent for resins and a curing accelerator for epoxy resins.

[0002]

2. Description of the Related Art Conventionally, epoxy resins have excellent adhesiveness to metals and the like, and cured products thereof have excellent electrical insulation properties, chemical resistance, heat resistance, mechanical strength, etc. Electrical insulation, adhesives, paints, laminates and FR
Widely used in various fields for applications such as P resins. This epoxy resin, which is in a liquid state or a thermoplastic state at room temperature, becomes a cured product having a three-dimensional structure by reacting with a curing agent for an epoxy resin. It is known that the properties of the cured resin are greatly influenced by the curing agent, and various curing agents have been used for industrial purposes so far. By the way, the adhesive can be roughly classified into a one-pack type and a two-pack type depending on the method of use. In the former one-pack type, a commercially available adhesive is directly attached to an adherend, and heating, pressurizing, leaving, etc. It is an adhesive that can be bonded together.
On the other hand, the two-component type is an adhesive that can be adhered by mixing the main agent and the curing agent (or catalyst) at the time of use, and then applying the mixture to an adherend and heating, pressurizing or leaving it to stand. Epoxy type and urethane type adhesives are usually two-component type, and although this two-component type is laborious and inefficient from the viewpoint of work, it has excellent adhesive strength, thermal characteristics, electrical characteristics, etc. of the cured product. Since it has many aspects, it is widely used in the fields of electric parts, automobiles, and aircraft. However, the two-pack type adhesive has a drawback that the pot life, that is, the time for maintaining the usable state of the adhesive prepared for application is short and the working efficiency is poor.
For example, for an adhesive having a pot life of 2 hours, it is necessary to mix the main agent and the curing agent four times during the working time of 8 hours a day. By the way, an imidazole compound is often used as a curing agent for epoxy resin or a curing accelerator for epoxy resin which is used together with an acid anhydride curing agent. As a means for extending the storage stability period (pot life) when this imidazole compound is mixed with an epoxy resin, for example, a reaction product of an imidazole compound and an aliphatic monocarboxylic acid such as acetic acid ( JP-B-42-11500, JP-A-55-50021), a reaction product of an imidazole compound and an aliphatic hydroxymonocarboxylic acid such as lactic acid (JP-B-42-11).
It is known to use a reaction product of an imidazole compound and an aromatic hydroxymonocarboxylic acid such as salicylic acid (JP-A-2-84426). However, such a reaction product of an imidazole compound and an organic carboxylic acid, when mixed with an epoxy resin, has the effect of slightly extending the storage stability period, but is not sufficient and not always satisfactory. .

[0003]

Under the above circumstances, the present invention provides a curing agent for an imidazole-based epoxy resin, which can significantly extend the storage stability period when mixed with an epoxy resin. It is made for the purpose of providing a curing accelerator for an epoxy resin.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to develop a curing agent for an epoxy resin and a curing accelerator for an epoxy resin having the above-mentioned preferable properties, and as a result, the imidazole compound has been obtained. When a compound obtained by reacting a specific phosphonic acid with an epoxy resin is mixed with an epoxy resin, the storage stability period is significantly extended, for example, it shows storage stability at a temperature of 40 ° C. for 3 months or more. The present invention has been found, and the present invention has been completed based on this finding. That is, the present invention is a compound of the general formula

[0005]

[Chemical 3]

(R is a hydrogen atom or a hydroxyl group, M is a hydrogen atom, alkali metal or NH ₄ , and n is an integer of 0 or 1 to 3) To provide a curing agent for an epoxy resin comprising the above compound, and a curing accelerator for an epoxy resin comprising the compound obtained by reacting an imidazole compound with a phosphonic acid represented by the general formula [1] Is. Hereinafter, the present invention will be described in detail. The imidazole compound used in the present invention has a general formula

[0007]

[Chemical 4]

(In the formula, R ¹ , R ² , R ³ and R ⁴ are each a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group or an aryl group, and they may be the same or different. May also be included).
Specific examples of such imidazole compounds include imidazole, 2-methylimidazole, 2-ethylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole. , 2-heptadecyl imidazole, 1-vinyl-2-methyl imidazole, 1
-Vinyl-2-ethylimidazole, 2-cyclohexylimidazole, 2-cyclohexyl-4-methylimidazole, 2,5-dichloro-4-ethylimidazole, 1-methylimidazole and the like, but not limited to these. Absent. On the other hand, as the phosphonic acids to be reacted with the imidazole compound, general formula

[0009]

[Chemical 5]

A structure represented by the formula (R, M and n in the formula have the same meanings as described above) is used. Examples of the phosphonic acids represented by the general formula [1] include ethylidene diphosphonic acid, hydroxyethylidene diphosphonic acid, propylidene diphosphonic acid, hydroxypropylidene diphosphonic acid, butylidene diphosphonic acid, and hydroxybutylidene diphosphonic acid. And the like, and their alkali metal salts and ammonium salts. The curing agent for an epoxy resin and the curing accelerator for an epoxy resin of the present invention are composed of a compound obtained by reacting the imidazole compound with a phosphonic acid, and, for example, in a solvent such as an aqueous medium, imidazole. The system compound and the phosphonic acid are used at a molar ratio of 1: 0.5 to 1: 2, reacted at a temperature of about 0 to 80 ° C. for an appropriate time, and allowed to stand or cooled if necessary to form crystals. It can be obtained by a method such as precipitation, or by distilling off the solvent to precipitate crystals and collecting the crystals.

As the uncured epoxy resin to which the curing agent for epoxy resin and curing accelerator for epoxy resin of the present invention can be applied, for example, bisphenol A-epichlorohydrin resin, polyfunctional epoxy resin, alicyclic epoxy resin, Examples thereof include those having at least two epoxy groups in one molecule such as brominated epoxy resin and epoxy novolac resin. When the curing agent for an epoxy resin and the curing accelerator for an epoxy resin of the present invention are blended with the uncured epoxy resin, the storage stability period of the conventional imidazole compound and an organic carboxylic acid (acetic acid, lactic acid,
It is significantly longer than when a reaction product with salicylic acid) is blended. For example, when the conventional reaction product is blended, the viscosity is extremely increased within a storage period of one day, whereas the compound obtained by reacting the imidazole compound with the phosphonic acid is blended. , Storage stability at a temperature of 40 ° C. for 3 months or more. The curing agent for the epoxy resin and the curing accelerator for the epoxy resin of the present invention,
Suitable for applications where epoxy resin is cured, such as epoxy resin adhesives, semiconductor encapsulants, varnishes for laminated boards for printed wiring boards, powder coatings, liquid coatings, casting materials, inks, etc. be able to.

[0012]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. Example 1 Production of a reaction product of 2-methylimidazole (2MZ) and hydroxyethylidene diphosphonic acid Dequest 2010 (manufactured by Monsanto Co., aqueous solution of 60 wt% hydroxyethylidene diphosphonic acid) 41.9 g,
Charge 10 g of 2-methylimidazole (2MZ), and
2MZ was completely dissolved by heating to 0 ° C. Water was distilled off from this solution using an evaporator, and the resulting crystals were dried in vacuum to completely remove water. As a result, 35.14 g of a reaction product (2MZ / hydroxyethylidene diphosphonic acid molar ratio 1/1, reaction 2MZ content in the product 28.3 wt%, m.
p.192-202 ° C) was obtained.

Comparative Example 1 Preparation of reaction product of 2MZ and acetic acid (prepared according to Japanese Examined Patent Publication No. 42-11500) 82 g (1 mol) of 2MZ was stirred, and 90 g of glacial acetic acid.
(1.5 mol) was added over 10 minutes. After being kept at 60 to 80 ° C. for 1 hour, it was cooled to obtain 172 g of a reaction product (2MZ content 47.7 wt%, liquid product). Comparative Example 2 Production of Reaction Product of 2MZ and Lactic Acid
-11500) 2MZ 82g (1 mol) with stirring, 90% lactic acid 1
75 g (1.75 mol) was added in 10 minutes. 60 ~
The reaction mixture (2MZ
257 g of a liquid product having a content of 31.9 wt% was obtained.

Example 2 100 parts by weight of uncured epoxy resin (Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) was added to the reaction products obtained in Example 1 and Comparative Examples 1 and 2 in an amount of 2 MZ to 2 parts by weight. The storage stability period of the adhesive compounded as described above was determined by measuring the viscosity at 40 ° C. The storage stability period is
It was a period until the initial viscosity of the adhesive became twice as high. The results are shown below. Storage stability period of blended product Example 1 100 days or more Comparative example 1 1 day Comparative example 2 1 day Further, the viscosity measurement curve of the blended product of Example 1 is shown in FIG.

Example 3 To 100 parts by weight of an uncured epoxy resin (Epicoat 828), an adhesive prepared by compounding the reaction products obtained in Example 1 and Comparative Examples 1 and 2 so that 2 MZ was 2 parts by weight was prepared. Then, it was applied to a raw cloth, adhered to an JIS H-4000 aluminum plate, heat-cured at 200 ° C. for 1 hour and 30 minutes, and then evaluated by hand peeling. As a result, raw cloth was destroyed in all three types. From this, it was confirmed that there was no adverse effect on the adhesive strength.

[0016]

The epoxy resin curing agent and the epoxy resin curing accelerator of the present invention are composed of a compound obtained by reacting an imidazole compound and a phosphonic acid, and when mixed with an epoxy resin. , Can greatly extend the storage stability period, and is suitable for applications such as epoxy resin adhesives, semiconductor encapsulants, varnishes for laminates for printed wiring boards, powder coatings, casting materials, inks, etc. Used.

[Brief description of drawings]

FIG. 1 is a graph of a case where a curing agent (or a curing accelerator) for an epoxy resin of the present invention is blended with an uncured epoxy resin.
3 is an example viscosity measurement curve.

Claims (2)

[Claims] 1. An imidazole compound and a compound represented by the general formula: (R in the formula is a hydrogen atom or a hydroxyl group, M is a hydrogen atom, an alkali metal or NH ₄ , and n is an integer of 0 or 1 to 3) A compound obtained by reacting with a phosphonic acid A curing agent for epoxy resin. 2. An imidazole compound and a compound represented by the general formula: (R in the formula is a hydrogen atom or a hydroxyl group, M is a hydrogen atom, an alkali metal or NH ₄ , and n is an integer of 0 or 1 to 3) A compound obtained by reacting with a phosphonic acid A curing accelerator for epoxy resin.