JPH0471929B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a liquid epoxy resin composition having good curability and storage stability. [Background of the Invention] Epoxy resin compositions have little shrinkage during curing, resulting in a cured product with little internal distortion, high mechanical strength, and excellent electrical insulation, heat resistance, water resistance, and chemical resistance. It is used in a wide variety of applications, including as impregnating, casting, and molding materials. However, when an epoxy resin composition contains a curing catalyst, its viscosity increases if it is left at room temperature for several days, making it unusable. In a heated state, the composition polymerizes more rapidly and gels at 60° C. in several tens of hours. Such properties have been a major obstacle in methods in which a large amount of the liquid composition is stored in a tank and used repeatedly for impregnation, especially under heating. Therefore, if an attempt is made to extend the pot life by reducing the amount of curing catalyst added, the curability will be insufficient and the properties of the cured product (eg, heat distortion temperature and mechanical properties) will deteriorate. It has been impossible to achieve both curability and storage stability by simply adjusting the amount of curing catalyst added.
Therefore, in order to achieve both curability and storage stability of epoxy resin compositions, research into latent curing accelerators has been actively conducted in various places. As a result, organic acid salts of amines or quaternary ammonium (for example, Japanese Patent Publication No. 49-25000; Japanese Patent Publication No. 37-7136),
Intermolecular coordination compounds of amines (e.g., U.S. Pat.
3347827; No. 3395121; No. 3065195; French Patent No. 2001238), intramolecular coordination compounds of amines (for example, USSR Patent No. 204573), combinations of amines with aldehydes or ketones; Reaction products (e.g., U.S. Pat. Nos. 3,291,776; 3,401,146
No. 3310602; Japanese Patent Publication No. 45-1756), urea derivatives and dicyandiamide (e.g.
U.S. Patent No. 3294749; No. 3227679),
Compounds with hydrazino group (Special Publication No. 48-82000)
No. Publication; West German Patent Publication No. 2355121), borate (for example, U.S. Patent No. 3269960; Japanese Patent Publication No. 47
-26397; Japanese Patent Publication No. 47-26378), ferrocene (e.g., Japanese Patent Publication No. 45-37867), phosphorus compounds (e.g., Japanese Patent Publication No. 47-26398), or microencapsulation of amines (e.g., Japanese Patent Publication No. 47-26398); Patent No. 3,395,105), adsorption of amines by molecular sieves (eg, US Pat. No. 3,417,046), etc. have been proposed. All of these had insufficient curability and storage stability. In particular, liquid epoxy resin compositions for impregnation and casting have been insufficiently compatible with curability and storage stability. Therefore, when using a liquid epoxy resin composition for coil impregnation, etc., a method has also been proposed in which a curing catalyst is attached to the object to be impregnated prior to the impregnation operation, and the impregnation is performed to cure the object.
However, such methods are complicated and involve many steps, and the properties of the cured product vary due to variations in the curing catalyst and peeling, and the curing catalyst is dissolved in the liquid epoxy resin composition to be stored. death,
The composition had drawbacks such as a shortened pot life. [Object of the Invention] An object of the present invention is to provide an epoxy resin composition for impregnation that is liquid at 40° C. and has excellent curability and storage stability without the above-mentioned drawbacks. [Summary of the Invention] The present invention is characterized by: (A) a base resin composition of an alicyclic epoxy resin or a polyfunctional epoxy resin containing an alicyclic epoxy resin and a polycarboxylic acid anhydride; (B) a lower alkyl monomer; A hydroxyl group-containing compound selected from adducts of carboxylic acids and epoxy resins or phenols, with an OH content of 0.05 to 0.4% by weight based on component (A), (C) Na, K, Li, Ba An alkali metal or alkaline earth metal hydroxide or alkoxy compound selected from (3-7a) x 10 ^-3 to (5-7a) x 10 ^- with respect to the component (A), based on the metal amount of the compound. ³ % by weight [where a is the OH content (weight%) of the component (B)], but does not contain an amine curing agent, and is liquid at 40°C for impregnation. In the resin composition. Examples of the epoxy resin used in the epoxy resin composition of the present invention include diglycidyl ether of bisphenol A, butadiene diepoxide, 3,4-epoxycyclohexylmethyl-(3,4-epoxy)cyclohexanecarboxylate, and vinylcyclohexene. Dioxide,
4,4'-di(1,2-epoxyethyl) diphenyl ether, 4,4'-(1,2-epoxyethyl)
Biphenyl, 2,2-bis(3,4-epoxycyclohexyl)propane, diglycidyl ether of resorcinol, diglycidyl ether of phloroglucin, diglycidyl ether of methylphloroglucin, bis(2,3-epoxycyclopentyl) ether, 3 -(3,4-epoxy)cyclohexane-5,5-spiro(3,4-epoxy)
-cyclohexane-m-dioxane, bis-(3,
4-epoxy-6-methylcyclohexyl)adibate, N,N'-m-phenylenebis(4,5
- Bifunctional epoxy resin such as epoxy-1,2-cyclohexanedicarboximide, triglycidyl ether of para-aminophenol, polyallyl glycidyl ether, 1,3,5-tri(1,2-epoxyethyl)benzene, 2, 2′,
Tri- or higher functional epoxy such as 4,4'-tetraglycidoxybenzophenone, tetraglycidoxytetraphenylethane, polyglycidyl ether of phenol formaldehyde novolak, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane Resin is used. Among the above epoxy resins, an alicyclic epoxy resin or a polyfunctional epoxy resin containing an alicyclic epoxy resin is used. Particularly useful are alicyclic epoxy resins such as 3,4-epoxycyclohexylmethyl-(3,4-epoxy)cyclohexenecarboxylate and vinylcyclohexene dioxide, and diglycidyl ether of bisphenol A. In addition, the epoxy resin has low viscosity, heat resistance,
Contains polycarboxylic acid anhydride to improve electrical insulation. Examples of such acid anhydrides include polycarboxylic anhydrides well known as curing agents for epoxy resins, such as phthalic anhydride, itaconic anhydride, succinic anhydride, citraconic anhydride, alkenyl acid anhydride, dodecenylsuccinic anhydride, and anhydride. Tricarballylic acid, maleic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, pyromellitic anhydride, cyclopentanetetracarboxylic anhydride, benzophenonetetracarboxylic anhydride, ethylene glycol bistrimeritate, glycerin tristrimeritate , maleic anhydride adduct of methylcyclopentadiene, chlorendic anhydride, alkylated endoalkylenetetrahydrophthalic anhydride, methyl 2-substituted butenyltetrahydrophthalic anhydride, and the like. Among these, liquid acid anhydrides such as a maleic anhydride adduct of methylcyclopentadiene, methyltetrahydrophthalic anhydride, and methylhexahydrophthalic anhydride are useful. As the curing catalyst for component (C) in the present invention,
A hydroxide or alkoxy compound of an alkali metal or alkaline earth metal selected from Na, K, Li, and Ba, the amount of which is the metal amount of the compound, based on the resin component of (A) (3-7a ) × 10 ^-3 ~ (5-
7a) × 10 ^-3 % by weight [However, a is the component (B) described below.
OH content (wt%)]. If the amount exceeds the above range, the storage stability will decrease, and if it is outside the range, the curing property will decrease and the heat distortion temperature will decrease.
A cured product cannot be obtained at 100℃ or higher. The hydroxyl group-containing compound serving as the curing catalyst for component (B) of the present invention is an adduct of a lower alkyl monocarboxylic acid and an epoxy resin or a phenol. The compound has an OH content of 0.05 to 0.4% by weight, particularly 0.08 to 0.37% by weight based on the resin component (A).
is preferred. If the amount of the hydroxyl group-containing compound is too large, storage stability tends to be insufficient, whereas if it is too small, curability tends to be insufficient. Although the curing mechanism of the epoxy resin composition of the present invention is not precisely known, it is thought to proceed through a push-pull reaction as shown in the figure below. X: Compound containing a hydroxyl group Y: Alkali metal or/and alkaline earth metal The epoxy resin composition of the present invention can be used by adding known additives, fillers, pigments, or solvents, etc., as necessary. . [Examples of the Invention] Next, the present invention will be specifically explained with reference to Examples. Example 1 3,4-epoxycyclohexylmethyl-(3,
258 g (1.0 mol) of 4-epoxy)cyclohexanecarboxylate and 267 g (1.5 mol) of a maleic anhydride adduct of methylcyclopentadiene were mixed to obtain an epoxy resin composition. Next, add the epoxy resin composition [] to []
Adduct of 25.8 g (0.10 mol) and acetic acid 12.0 g (0.20 mol) [] and sodium methylate []
were mixed at a predetermined mixing ratio to obtain an epoxy resin composition []. When this [] was stored at 40°C, the change in viscosity over time was measured to determine the shelf life, and the results are shown in Figure 1. In addition, the shelf life was defined as the time (in days) until the viscosity reached 10 times the initial value. Curve 1 in Figure 1 shows the OH content.
0.37% by weight, curve 2 is 0.28% by weight, curve 3 is 0.20
% by weight, curve 4 is 0.14% by weight, curve 5 is 0.08% by weight. Next, the epoxy resin composition [] was heated to 160℃ for 5 minutes.
The mixture was heated to 170° C. for 5 hours to obtain a cured product. The heat distortion temperature of this cured product was measured in accordance with JISK-6911. The results are shown in FIG. In addition, the second
The symbols in the figure are the same as in FIG. From FIG. 1 and FIG. 2, it can be seen that when the Na ⁺ content and the hydroxyl group content are reduced, the shelf life is extended, but the curing property is insufficient, and the heat distortion temperature tends to be lowered. On the other hand, it is clear that as the Na ⁺ content and hydroxyl group content increase, the shelf life becomes shorter. Example 2 172 g (0.5 mol) of diglycidyl ether of bisphenol A as epoxy resin, 3,4-epoxycyclohexylmethyl-(3,4-epoxy)
The procedure of Example 1 was repeated except that 129 g (0.5 mol) of cyclohexane carboxylate was used, and FIGS. 3 and 4 were obtained. Examples 3 to 9 The epoxy resin composition of Example 1 [] was mixed with an acetic acid adduct [] or phenol, and an alkali metal or/and an alkaline earth metal in the proportions shown in Table 1, and then heated with a shell life. The deformation temperature was measured. The results are shown in Table 1.

[Table] Examples 10 to 11, Comparative Examples 1 to 3 Epoxy resin compositions having the blending ratios shown in Table 2 were prepared, and the shelf life and heat distortion temperature were measured. The results are shown in Table 2. In Table 2, [ ] indicates anhydride methyltetrahydrophthalic acid, and [ ] indicates anhydride methylhexahydrophthalic acid. Table 2 shows that the epoxy resin composition of the present invention has a better balance between storage stability and curability than the comparative example. In addition, in Example 1, acetic acid (CH _3
CH3 ( _CH2 )COOH, _CH3 ( _CH2 ) ₃
The shelf life and heat distortion temperature of the epoxy resin composition of the present invention prepared in the same manner as in Example 1 except that COOH or CH ₃ (CH ₂ ) ₅ COOH was used are also shown in FIGS. 1 and 2. Almost the same results were obtained. In addition, in Example 10, except that sodium methylate was changed to sodium phenolate,
The shell life and heat distortion temperature of the epoxy resin composition prepared in the same manner as in Example 10 also gave almost the same results as in Example 10. Comparative Example 4 An epoxy resin composition prepared in the same manner as in Example 9 except that 54.8 g of diaminophenylmethane was added had a shelf life of 1 hour at 40°C.

〔Effect of the invention〕

As is clear from the examples above, the epoxy resin composition containing a compound containing a hydroxyl group and an alkali metal or/and an alkaline earth metal has both storage stability and curability.

[Brief explanation of the drawing]

Figures 1 and 3 are shelf life characteristic diagrams for Na ⁺ content of epoxy resin compositions according to examples of the present invention, and Figures 2 and 4 are thermal deformation characteristic diagrams for Na ⁺ content. be.

Claims (1)

[Claims] 1(A) A base resin composition of an alicyclic epoxy resin or a polyfunctional epoxy resin containing an alicyclic epoxy resin and a polycarboxylic acid anhydride, (B) a lower alkyl monocarboxylic acid and an epoxy An adduct with a resin or a hydroxyl group-containing compound selected from phenols with an OH content of 0.05 to 0.4% by weight based on component (A); (C) an alkali selected from Na, K, Li, and Ba; The metal or alkaline earth metal hydroxide or alkoxy compound is (3-7a) x 10 ^-3 to (5-7a) x 10 ^-3 % by weight based on the component (A) in terms of the metal amount of the compound [ An epoxy resin composition for impregnation that is liquid at 40° C., characterized in that it does not contain an amine curing agent.