JPH0759622B2 - Epoxy resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to an epoxy resin composition which is cured by an acid anhydride containing an epoxy resin and a specific methyltetrahydrophthalic anhydride.

[Prior Art] Methyltetrahydrophthalic anhydride (hereinafter abbreviated as Me-THPA) is well known as a curing agent for epoxy resins, and a liquid one at room temperature is generally used.

The Me-THPA liquid at such room temperature, 4-methyl - △ ⁴ - tetrahydro - cis, cis - phthalic anhydride (hereinafter, 4Me- △ ⁴ abbreviated -THPA) sulfuric acid, phosphoric acid, BF ₃ Complexity A mixture of structural isomers having different double bond positions in a cyclohexene ring, which is obtained by heating a structural isomerization reaction by heating in the presence of an acid catalyst such as lux, AlCl ₃ , or a cation exchange resin, is known. Patent No. 2,959,599). In this case, the isomer mixture is 4Me-Δ ⁴ -THPA
When 4-methyl - △ ³ - tetrahydro - cis, cis - phthalic anhydride, 4-methyl - △ ² - tetrahydro - cis, cis - phthalic anhydride and / or 4-methyl - △ ¹ - tetrahydro - cis, cis - It is a mixture with phthalic anhydride.

Also, cis-3-methyl-Δ ⁴ -tetrahydro-cis,
Cis - phthalic anhydride (hereinafter, cis-3Me- △ ⁴ abbreviated -THPA) to Yotsute to heating in the presence or absence of a basic catalyst, the movement of the double bond of the cyclohexene ring without stereoscopic isomer mixture obtained by the isomerization reaction are known, the stereoisomeric mixtures, cis-3Me- △ ⁴ -TH
PA and trans-3-methyl - △ ⁴ - tetrahydro - cis, cis - phthalic anhydride (hereinafter, trans-3Me- △ ⁴ -TH
It is known that it is a mixture of PA and liquid at room temperature (for example, JP-A-54-22499).

Further 4Me- △ ⁴ -THPA and 3-methyl - △ ⁴ - tetrahydro - cis, cis - structuring isomerized as described above a mixture of phthalic anhydride (e.g., JP-B-45-15495), or three-dimensional There is known a method of improving the liquid stability of an isomer mixture by isomerizing (for example, Japanese Patent Publication No. 54-151941).

Further, it is also known to liquefy a structural isomer mixture obtained by moving the double bond of Me-THPA by heating in the presence of a stereoisomerization catalyst (for example, JP-A-55).
-89277 publication).

[Problems to be solved by the invention]

However, the isomer mixture obtained by the structural isomerization reaction as described above is inferior in moisture absorption stability after being mixed with an epoxy resin, and there is a drawback that crystals are precipitated due to moisture absorption or turbidity occurs. It was Further, the isomer mixture obtained by the stereoisomerization reaction is excellent in moisture absorption stability after mixing with the epoxy resin, but the isomer mixture obtained by the structural isomerization reaction is colorless or pale yellow. On the other hand, it is yellow to brown, which not only lowers the commercial value but also deteriorates the hue of the cured epoxy resin. Further, for example, the isomer mixture obtained by stereoisomerizing the structural isomer pair mixture disclosed in JP-A-55-89277 is yellow to brown, and the starting material Me is used.
-THPA composition (4Me- △ ^4- THPA and cis-3Me- △ ^4- THP
Depending on the mixing ratio of A), the hue of the epoxy resin cured product is not uniform, and when the interior of the cured product is cut and viewed, the central part appears reddish and the physical properties of the cured product are partially different I got it.

The present invention provides an epoxy resin composition containing a light-colored liquid Me-THPA at room temperature, which has excellent moisture absorption stability of an epoxy compound and which has a uniform hue of an epoxy cured product.

[Means for solving problems]

The present invention relates to (A) epoxy resin and (B) 4Me-Δ ⁴
-THPA and / or cis-3Me- △ ⁴ a stereoisomeric mixture of -THPA obtained by heating treatment in the presence of a structured isomerization catalyst,
The present invention relates to an epoxy resin composition containing an acid anhydride mixture that is liquid at room temperature.

In the present invention, the epoxy resin is a compound having two or more epoxy groups in the molecule, such as bisphenol A.
Those obtained by the reaction of polyhydric phenols such as with epichlorohydrin, those obtained by reacting polyhydric alcohols such as 1,4-butanediol with epichlorohydrin, polybasic acids such as phthalic acid, hexahydrophthalic acid, etc. N-glycidyl derivatives of polyglycidyl esters, amines, amides or compounds having a heterocyclic nitrogen base of
(3 ', 4'-epoxycyclohexylmethyl) -3,4-
There are alicyclic epoxy resins such as epoxycyclohexanecarboxylate.

The acid anhydride mixture in the present invention can be obtained as follows.

^{4Me- △ 4 -THPA, cis-3Me-} △ 4 -THPA or mixtures thereof is first presence or stereoisomeric mixture heated in the absence of solid isomerization catalyst is obtained. It is then heated in the presence of a structural isomerization catalyst. If this order is reversed, it is not possible to obtain an acid anhydride mixture which achieves the object of the present invention.

As the stereoisomerization catalyst, a basic catalyst is used, for example, hydroxides, oxides, alcoholates, phenolates, etc. of alkali metals such as sodium, potassium and lithium, N, N-
Examples include tertiary amines such as dibutylaniline, N, N-diethylaniline and dimethylaminoethanol, and quaternary ammonium salts such as triethylbenzylammonium chloride.

Examples of the structural isomerization catalyst include sulfuric acid, phosphoric acid, polyphosphoric acid, paratoluenesulfonic acid, BF ₃ -etherate, BF ₃
An acidic catalyst such as phenolate, AlCl ₃ , TiCl ₄ , ZnCl ₄ , cation exchange resin is used. Further, catalysts such as palladium catalysts and ruthenium catalysts which simultaneously perform structural isomerization and disproportionation are also known (US Pat. No. 2,764,597), but these catalysts are also structural isomerization catalysts of the present invention. Included.

4Me- △ by ⁴ -THPA and / or cis-3Me- △ ⁴ -THPA heat treatment in the presence or absence of steric isomerization catalyst, occurs stereoisomerization, low acid anhydride melting point than the raw material It becomes a mixture (stereoisomer mixture).

As a stereoisomer of 4Me- △ ^4- THPA, 4-methyl- △
⁴ - tetrahydro - cis, trans - phthalic anhydride is considered, as stereoisomers of cis-3Me- △ ⁴ -THPA is
trans-3Me- △ ⁴ -THPA, cis-3-methyl - [delta ⁴ - tetrahydro - cis, trans - phthalic anhydride and trans-3-methyl - [delta ⁴ - tetrahydro - cis, trans - phthalic anhydride can be considered.

4Me- △ ⁴ -THPA and / or cis-3Me- △ ⁴ presence or an acid anhydride mixture obtained by the heat treatment in the absence of -THPA stereoisomeric catalyst (mixture of stereoisomers) structured isomerization When heated in the presence of a catalyst, at least a part of the acid anhydride contained in the acid anhydride mixture moves a double bond in the structure to become a structural isomer, and thus the number of isomers increases, and An acid anhydride mixture with a lower melting point is obtained. The melting point of the finally obtained acid anhydride mixture is adjusted so as to be liquid at room temperature at most.

Heating in the presence of a stereoisomerization catalyst or a structural isomerization catalyst
It is preferably carried out at 100 to 250 ° C, especially 150 to 200 ° C.
Is preferably carried out in. Heating in the absence of a stereoisomerization catalyst is preferably carried out at 150-250 ° C, especially
It is preferably carried out at 180 to 230 ° C. If this temperature is too low, the heat treatment is insufficient and sufficient isomerization cannot be performed,
If it is too high, high molecular weight by-products are likely to be produced.

Also, the stereoisomerization catalyst and the structural isomerization catalyst are 4M each.
It is preferably used in an amount of 0.05 to 5% by weight based on e-Δ ⁴ -THPA, cis-3Me-Δ ⁴ -THPA or a mixture thereof. If this amount is too small, the heat treatment time becomes long, and if it is too large, a high molecular weight by-product is likely to be produced.

Further, the heating in the presence of the stereoisomerization catalyst or the structural isomerization catalyst may be carried out usually 0.5 to 20 hours, preferably 3 to 10 hours.

The acid anhydride mixture (stereoisomer mixture) obtained by the heat treatment in the presence or absence of the stereoisomerization catalyst has a stereoisomerization catalyst and, if necessary, a high molecular weight of After separation of by-products, it is subjected to heating in the presence of a structural isomerization catalyst.

The acid anhydride mixture obtained by heating in the presence of a structural isomerization catalyst is used as an acid anhydride mixture which is the component (B) of the present invention after the heating is completed and the catalyst and the like are removed by distillation or the like. It

(B) an acid anhydride mixture is a component of the present invention, a raw material 4Me- △ ⁴ -THPA and cis-3Me- △ ⁴ cycloaliphatic dicarboxylic acid anhydrides other than -THPA, aromatic dicarboxylic acid anhydrides May be obtained from the beginning of the production or during the production thereof, or may be obtained by adding them after the reaction is completed. Examples of such dicarboxylic acid anhydrides include tetrahydrophthalic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, hexahydrophthalic anhydride,
Examples include methylhexahydrophthalic anhydride and phthalic anhydride. Such an operation is carried out within a range consistent with the object of the present invention.

It is a raw material of the acid anhydride mixture which is the component (B) of the present invention.
4Me- △ ⁴ -THPA and cis-3Me- △ ⁴ -THPA but are blended in any ratio, in terms of coloration of hygroscopic stability and the composition of the epoxy resin composition, 4Me- △ ⁴ -THPA100~ It is particularly preferable to add 20 wt% and cis-3Me-Δ ⁴ -THPA of 0 to 80 wt%.

In the present invention, the epoxy resin as the component (A) and the acid anhydride mixture as the component (B) are mixed at an appropriate ratio so that the acid anhydride group is 0.8 to 1 equivalent to 1 equivalent of the epoxy group. It is preferable to blend in.

A curing accelerator can be added to the epoxy resin composition according to the present invention. As the curing accelerator, 2-ethyl-4-methylimidazole, cyanoethyl-2-ethyl-4-methylimidazole, 1-benzyl 2-methylimidazole, 1-methylimidazole, 1,2-dimethylimidazole, benzyldimethylamine, N, N-Dimethylaniline, Tris (dimethylaminomethyl) phenol, 1,8-
Tertiary amines such as diazabicyclo (5,4,0) undecene-7, 2-ethylhexanoate salts of such tertiary amines,
Tertiary amine salts such as phenol salts, oleate salts, formate salts, acetate salts, quaternary ammonium salts such as tetramethylammonium chloride, benzyltriethylammonium chloride, tin octylate, zinc octylate, sodium methoxide, cobalt, nickel. Examples of the metal include metal salts such as metal acetylacetone complex salts. The curing accelerator is 0.1 to 8% by weight with respect to the epoxy resin as the component (A).
It is preferably used, and particularly preferably 0.3 to 5% by weight.

Reactive diluents, plasticizers, fillers, dyes, flame retardants and the like can be appropriately added to the epoxy resin composition according to the present invention.

〔Example〕

Next, examples of the present invention will be described. Hereinafter, parts and% mean parts by weight and% by weight, respectively, unless otherwise specified.

To manufacture 1 four-necked flask of Example 1-5 (1) an acid anhydride mixture, in proportions shown in Table 1 4Me- △ ⁴ -T
HPA (melting point 64 ℃) and cis-3Me- △ ^4- THPA (melting point 61 ℃)
Then, 1000 parts were taken together, 1 part of dimethylaminoethanol was added, and the mixture was heated and stirred at 170 ° C. for 3 hours.

From the reaction solution, 500 g was taken and distilled under reduced pressure at 3 mmHg to obtain a stereoisomer mixture, and the properties and hue at room temperature were observed. Further, the following epoxy resin composition was subjected to moisture absorption stability, a coloring test of an epoxy resin cured product, and a measurement of melting point or crystallization days at -15 ° C. The results are shown in Table 1.

Further, 2.5 parts of polyphosphoric acid was added to the remaining reaction solution, and the mixture was heated and stirred at 170 ° C. for 5 hours to carry out structural isomerization. This reaction solution
The mixture was distilled under reduced pressure at 3 mmHg to obtain an acid anhydride mixture, and the properties and hue at room temperature were observed. Furthermore, the following moisture absorption stability of the epoxy resin composition, a color test of the cured epoxy resin and
It was used for measurement of the number of crystallization days at 15 ° C. The results are shown in Table 1.

(2) Moisture absorption stability test of epoxy resin composition Epoxy resin (Epicoat 828, trade name of Yuka-Ciel Epoxy Co., Ltd.) 80 parts, epoxy resin (Araldite DY
022, trade name of Ciba Geigy Co., Ltd.) and 20 g from a mixture of 20 parts and 100 parts of the acid anhydride mixture in a 50 ml beaker, 40
It was left for 24 hours in a thermo-hygrostat kept at 90 ° C and 90% RH, and the presence of crystals and the presence of cloudiness were visually observed.

The case where there was no crystal precipitation and cloudiness was evaluated as ◯, the case where crystal precipitation was slightly along the beaker wall was evaluated as Δ, and the case where crystal precipitation spreads to the liquid surface and there was cloudiness was evaluated as x.

(3) Coloring test of cured epoxy resin 80 parts of epoxy resin (Epicoat 828), 20 parts of brominated epoxy resin (BROC, trade name of Nippon Kayaku Co., Ltd.), titanium white 5
And 3 parts of Erosil (trade name of Nippon Aerosil Co., Ltd.) are mixed in a mortar to prepare a solution A.

Liquid B is a mixture of 100 parts of the acid anhydride mixture and 2 parts of cyanoethyl-2-ethyl-4-methyl-imidazole (2E4MZ-CN, trade name of Shikoku Kasei Co., Ltd., curing accelerator).

A composition is obtained by mixing 60 parts of solution B with 108 parts of solution A, and 30 g of the composition is weighed in a pudding cup.

After curing by heating at 80 ° C. for 3 hours and then at 105 ° C. for 3 hours, the cured product was taken out from the pudding cup and cut in half, and the hue of the cross section was visually observed.

○ that the whole is colorless to pale yellow and has a uniform hue,
△ is the one with a slightly reddish color in the central part and a pale yellow color with a non-uniform hue around it, and X is the one with a distinct red color in the central part and a pale yellow color around the periphery and a non-uniform hue. evaluated.

(4) Measurement of the number of days of crystallization at -15 ° C Place the acid anhydride mixture in a test tube with a diameter of 10 mm and a height of 10 cm for about 8 minutes, then close the stopper and place it in a constant temperature bath set at -15 ° C. , The number of days until the crystals started to precipitate was examined.

Comparative Examples 1 to 5 (1) Production of Acid Anhydride Mixture 1 In a four-necked flask, at a ratio shown in Table 2, 4Me-Δ ⁴ -T.
HPA (melting point 64 ℃) and cis-3Me- △ ^4- THPA (melting point 61 ℃)
Then, 1000 parts were added together, 3 parts of polyphosphoric acid was added, and the mixture was heated and stirred at 170 ° C. for 5 hours.

From the reaction solution, 500 g was taken and distilled under reduced pressure at 3 mmHg to obtain a stereoisomer mixture, and the properties and hue at room temperature were observed.

Further, the epoxy resin composition was subjected to moisture absorption stability, a coloring test of the cured epoxy resin, and measurement of the melting point or the number of days of crystallization at -15 ° C. The results are shown in Table 2.

Further, 2.5 parts of dimethylaminoethanol was added to the remaining reaction solution, and the mixture was heated and stirred at 170 ° C. for 3 hours to carry out stereoisomerization.

This reaction liquid was distilled under reduced pressure at 3 mmHg to obtain an acid anhydride mixture,
The properties and hue at room temperature were observed. Furthermore, the moisture absorption stability of the epoxy resin composition, the coloring test of the cured epoxy resin, and the crystallization days at -15 ° C were measured. The results are shown in Table 2.

(2) The moisture absorption stability test of the epoxy resin composition and the coloring test of the cured epoxy resin composition were performed in the same manner as in Examples 1-5.

[Effects of the Invention] The epoxy resin composition according to the present invention has excellent moisture absorption stability, and since the acid anhydride mixture contained in the composition is liquid and light colored at room temperature, it can be used to adjust the epoxy resin composition. Will be preferable.

Further, the epoxy resin composition according to the present invention does not have a reddish color due to partial burning in the cured product because the curing reaction proceeds uniformly. Therefore, it is possible to obtain a cured product having uniform physical properties such as electric resistance and mechanical properties such as moisture resistance and heat resistance.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-55-89277 (JP, A) JP-A-54-22491 (JP, A) JP-A-55-122775 (JP, A) JP-A-55- 90528 (JP, A) JP 61-130331 (JP, A) JP 57-198725 (JP, A) US Patent 2959599 (US, A)

Claims (1)

[Claims] (1) Epoxy resin (A) and (B) 4-methyl-Δ ⁴ -tetrahydro-cis, cis-
Phthalic acid and / or cis-3-methyl anhydride - △ ⁴ - tetrahydro - cis, cis - obtained by heating the stereoisomeric mixture of phthalic anhydride in the presence of a structured isomerization catalyst, exhibiting the liquid state at room temperature An epoxy resin composition comprising an acid anhydride mixture.