JPH0710967A - Curative for epoxy resin, and epoxy resin composition - Google Patents

Abstract

PURPOSE:To improve interlaminar adhesive properties by compounding an epoxy resin with a curative contg., in a specified ratio, a specific trifunctional compd., a specific difunctional compd., and specific tetra- or higher functional compds. CONSTITUTION:A monosubstd. phenol (e.g. ethylphenol) is reacted with formaldehyde in the presence of a basic catalyst to give a dimethylol deriv. of the phenol. After being washed with water to remove impurities, the deriv. is mixed with a specified amt. of a phenol compd. and thermally reacted with it in the presence of an acid catalyst to give a curative of the formula (wherein A is the residue of the monosubstd. phenol; and B1 and B2 are each the residue of the phenol compd.) which comprises 25wt.% or higher trifunctional compd., 10wt.% or lower difunctional compd., and 65wt.% or lower tetra- or higher functional compds. A soln. contg. an epoxy resin compsn. comprising an epoxy resin and the curative is impregnated into a glass fabric to give a prepreg, which is laminated and pressed under heating to give an epoxy resin laminate having excellent interlaminar adhesive properties.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a curing agent for epoxy resin and an epoxy resin composition suitable for glass epoxy resin laminate.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of electronic equipment, printed wiring boards are required to have high density and high reliability. In particular, various characteristics when absorbing moisture tend to affect the quality to a greater extent than in the past, and a higher level of measling resistance is required. Further, it is necessary to improve the properties such as adhesion to metal or moldability such as impregnation failure due to thickening.

As an epoxy curing agent satisfying such characteristics, 3 having 3 reaction points with an epoxy group in one molecule
Hardeners containing functional compounds have been devised. For example, in JP-A-62-86941, an alkyl group of 1 to
An alkylphenol novolac resin containing a trifunctional compound, which is obtained by obtaining a resolized product from three alkylphenols and formaldehyde and adding a phenol to the methylol group of the resolated product, is described.

[0004]

However, although the above alkylphenol novolac resin has a small amount of binuclear components, it contains a large amount of tetranuclear or higher components, so that the wettability or evenness during impregnation is extremely poor. As a result, there is a drawback that cured product characteristics such as interlayer adhesion represented by peel strength and interlayer peel strength cannot be sufficiently obtained.

[0005]

The inventors of the present invention have found that even in a novolak resin containing a trifunctional compound having a specific structure, the content of the bifunctional compound and the tetrafunctional or higher compound is contained. However, it has been found that, when used as an epoxy resin curing agent, a remarkable difference occurs in terms of technical effects due to the difference from the conventional one.

When a mixture of a trifunctional compound having a specific structure and a compound having a functionality of 4 or more and a compound having a tetrafunctionality or more within a specific range is used as an epoxy resin curing agent, the above problems are solved. After finding out that, the present invention has been completed.

That is, the epoxy resin curing agent of the present invention comprises a trifunctional compound (I) having a structure in which a phenol (B) is bonded to a mono-substituted phenol (A) through two methylene bonds, and a mono-substituted compound (I). Obtained from a bifunctional compound (II) having a structure in which a phenol (B) is bonded to the phenol (A) through one methylene bond, and a monosubstituted phenol (A) and / or a phenol (B). In the epoxy resin curing agent containing a tetrafunctional or higher compound (III), the content of the trifunctional compound (I) is 25% by weight or more based on the whole, and the bifunctional compound (II) is contained. Epoxy resin, which is a mixture of compounds having a ratio of 10% by weight or less with respect to the whole, and a total (III) content of the tetrafunctional or higher functional compounds is 65% by weight or less with respect to the whole. Which is a curing agent.

The epoxy resin composition for glass epoxy laminates of the present invention contains an epoxy resin and a curing agent.
Trifunctional compound (I) having a structure in which phenols (B) are bonded to mono-substituted phenols (A) via two methylene bonds, and phenol through mono-substituted phenols (A) via one methylene bond Epoxy resin containing bifunctional compound (II) having a structure to which group (B) is bound and compound (III) having four or more functional groups obtained from monosubstituted phenols (A) and / or phenols (B) A curing agent, the content of the trifunctional compound (I) is 25% by weight or more of the whole, and the content of the bifunctional compound (II) is 10% by weight or less of the whole, and An epoxy resin composition comprising an epoxy resin curing agent having a total (III) content of the tetra- or higher-functional compound of 65% by weight or less based on the whole.

The present invention provides an epoxy resin composition suitable for an epoxy resin laminate comprising a curing agent for epoxy resin and a substrate such as glass, which gives a cured product having excellent peel strength and delamination strength. It is a thing. Moreover, they have also been found to give cured products having excellent adhesion to metals, resistance to measling, and good moldability.

The epoxy resin curing agent of the present invention has three acidic hydroxyl groups which are reaction points with the epoxy group and have a structure in which the phenols (B) are bonded to the mono-substituted phenols (A) through two methylene bonds. Having trifunctional compound (I)
Is characterized by a high content rate of. The trifunctional compound (I) can be represented by, for example, a structure represented by the following general formula (I).

[0011]

Embedded image Formula (I): B ₁ —CH ₂ —A—CH ₂ —B ₂

[In the general formula (I), A is a skeleton derived from a monosubstituted phenol (A), and B ₁ and B ₂ are skeletons derived from a phenol (B) which may be the same or different. Is. A, B ₁ and B ₂ are not all the same. ]

The epoxy resin curing agent of the present invention is a bifunctional compound having a structure in which, in addition to the above trifunctional compound (I), a monosubstituted phenol (A) is bound with a phenol (B) through one methylene bond. It contains a compound (II) and a tetra- or higher functional compound (III) obtained from a mono-substituted phenol (A) and / or a phenol (B).

The above-mentioned bifunctional compound (II) has two acidic hydroxyl groups which are reaction points with the epoxy group, and the monosubstituted phenols (A) have the phenols (B) via one methylene bond. It is a compound with a bonded structure. Four
The functional or higher compound (III) is an aggregate of compounds having a structure in which four or more mono-substituted phenols (A) or phenols (B) are bonded via a methylene bond.

As the above-mentioned mono-substituted phenols (A) for obtaining the epoxy resin curing agent in the present invention, any conventionally known one can be used, and the o / m of the phenol nucleus can be used.
There are monovalent phenols in which any one of the / p positions is substituted with a substituent. For example, alkylphenols such as cresol, ethylphenol, tertiary butylphenol, nonylphenol, and octylphenol, halogenated phenols, phenylphenols. , Aminophenol, etc.

However, in order to more selectively obtain the trifunctional compound (I) having three acidic hydroxyl groups which are reaction points with the epoxy group in one molecule, the mono-substituted phenols (A) are o Alternatively, it is suitable to use phenols having a substituent that does not react with aldehydes at the p-position. Further, from the viewpoint of resin viscosity and compatibility with epoxy resin, as the phenols (A), alkylphenols having an alkyl group having 1 to 5 carbon atoms are suitable. Further, these alkylphenols are not limited to one kind in use, and two or more kinds can be used in combination.

Further, the phenols (B) for obtaining the epoxy resin curing agent of the present invention are not particularly limited, but examples thereof include phenol, cresol, xylenol, bisphenol A and various substituted phenols. When using these phenols 1
It is not limited to only one kind, and two or more kinds can be used in combination. From the viewpoint of removing unreacted substances at the end of the reaction, phenol, cresol and the like, which can be easily removed by vacuum distillation, are suitable.

Formaldehyde is suitable for use in donating a methylene bond for binding the monosubstituted phenols (A) and the phenols (B), and typical sources include formalin and paraformaldehyde.

First, when preparing the epoxy resin curing agent of the present invention, it is preferable to carry out the production by adopting a method and conditions that increase the content of the trifunctional compound (I). Hereinafter, a typical method for obtaining the epoxy curing agent of the present invention will be described.

First, the above-mentioned p-substituted phenol (A)
And formaldehyde are reacted under a basic catalyst to form a dimethylol derivative of p-substituted phenol. This time,
The molar ratio of formaldehyde to p-substituted phenol is 0.5 to 4.0, preferably 1.0 to 3.0.

The catalyst is not particularly limited as long as it produces a methylol body, and representative ones are alkali metals and alkaline earth metals such as sodium hydroxide, potassium hydroxide and barium hydroxide. And hydroxides thereof, ammonia, tertiary amines, hexamethylenetetramine, sodium carbonate and the like.

The dimethylol-mono-substituted phenol may be a mixture of two or more different mono-substituted phenols.

Next, the obtained dimethylol-monosubstituted phenol-containing methylol compound is neutralized and washed with water as necessary to remove salts and other impurities, and then the phenols (B) are reacted with each other. At this time, the compounding ratio of the p-substituted phenols (A) and the phenols (B) is not particularly limited, but a molar ratio B / A = 0.5 to 5 is preferable, and a molar ratio B / A is more preferable. A = 1 to 3 is preferable. Within this range, the reaction is easily controlled, the yield of the trifunctional compound is increased, and the unreacted residual phenols (B)
Also few.

Further, when reacting the phenols (B), heat treatment may be carried out or a catalyst may be used, if necessary. The catalyst is not particularly limited as long as it can form a methylene bond, and representative ones include inorganic acids such as hydrochloric acid, sulfuric acid, sulfonic acid, oxalic acid,
Organic acids such as acetic acid, Lewis acids, or 2 such as zinc acetate
There are valent metal salts and the like.

From the viewpoint of reaction control, the reaction may be carried out in the presence of various solvents. After completion of the reaction, the unreacted formaldehyde, phenols, solvents and the like are removed by a conventional method such as atmospheric distillation or vacuum distillation, and the content of the trifunctional compound is higher than that of the conventional epoxy resin curing agent of the present invention. To get

In order to obtain the epoxy resin curing agent of the present invention in which the content of the trifunctional compound is higher than in the prior art, the first step reaction in obtaining the methylol body containing dimethylol-monosubstituted phenol is carried out at a higher temperature than in the prior art. With a short time,
The method of dividing the dehydration step after the second step reaction in which phenols (B) is added into several steps and gradually raising the temperature for each step to boil is particularly excellent. .

Whether or not the obtained composition contains the trifunctional compound in a specific ratio can be confirmed by a known and commonly used analytical means. As the analysis method,
For example, gel permeation chromatography (GP
C), nuclear magnetic resonance spectrum (NMR) and the like. Usually, their weight ratio is often measured from the peak area of GPC.

The thus-obtained product contains a larger amount of the trifunctional compound (I) in which three substantial phenol nuclei are linked by a methylene bond, and the bifunctional compound (II) component, and It is a mixture containing various tetrafunctional or higher compound (III) components.

In the present invention, the bifunctional compound (I
If the component (I) is too much, the heat resistance and the like will be poor, and the effects of the invention will be difficult to manifest. Therefore, the content is preferably 10% by weight or less based on the whole amount. Further, when the amount of the compound (III) having tetrafunctionality or more is too large, the adhesiveness, moldability, etc. are remarkably deteriorated and the effect of the present invention is not exhibited.
The content is preferably 5% by weight or less. In the composition, the effect of the present invention is remarkably exhibited.
This is a case where a large amount of the functional compound (I) is contained, and the total 25
The effect is confirmed when the content is at least wt%.

Mixtures of polyfunctional compounds obtained with different mono-substituted phenols (A) and different phenols (B) may be further mixed to prepare the composition of the present invention.

These trifunctional compounds, bifunctional compounds and tetrafunctional or higher functional compounds should be isolated and used as an epoxy resin curing agent, not as a composition (as an aggregate of compounds). You can also

The epoxy resin for obtaining the epoxy resin composition of the present invention is not particularly limited, and several kinds of epoxy resins may be used without any problem. The epoxy resin referred to here is a compound having one or more oxirane rings in one molecule, and typical examples thereof include bisphenol A type epoxy resin, polyphenol type epoxy resin, aliphatic epoxy resin, aromatic ester type. Epoxy resin, cycloaliphatic ester type epoxy resin,
Examples include aliphatic ester type epoxy resins, ether ester type epoxy resins, non-glycidyl type epoxy resins such as epoxidized soybean oil, and halogen-substituted products thereof such as bromine and chlorine.

The mixing ratio of the epoxy resin and the curing agent of the present invention is not particularly limited, but the functional group ratio between the epoxy groups of the epoxy resin and the phenolic hydroxyl group in the curing agent is usually 0. It is preferable to set the weight ratio so that the weight ratio is 8 to 1.2, especially 1.

When curing the epoxy resin composition of the present invention, various accelerators generally used for curing epoxy compounds can be used as needed. Examples thereof include imidazole and its derivatives, phosphine compounds, amines, and BF ₃ amine compounds.

Furthermore, the solvent used in the epoxy resin composition of the present invention is not particularly limited, and various solvents can be used if necessary. For example, acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N, N-dimethylformamide, methanol, ethanol and the like can be mentioned, and these solvents are appropriately 2 kinds or more. It is also possible to use it as a mixed solvent of.

If desired, various additives, flame retardants, fillers, etc. can be added to the epoxy resin composition of the present invention.

The epoxy resin composition of the present invention can be used not only for laminated boards but also for semiconductor encapsulating materials, casting materials, housings, floor materials and the like.

[0038]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. Hereinafter, "%" means "% by weight" and "part" means "part by weight".

Synthesis Example 1 To 150 parts of p-tert-butylphenol (hereinafter referred to as pTBP), 217 parts of 41.5% formalin and 0.15 part of sodium hydroxide were added, and the mixture was mixed at 60 ° C. for 5 minutes.
Reacted for hours. Next, add sulfuric acid to the resin solution to adjust the pH to 7
After adjusting to ± 1, water was further added and the system was stirred for a while, and then the separated aqueous layer was removed to obtain a methylol body containing a dimethylol body of pTBP. Next, set the system temperature to 5
Lowered to below 0 ℃, 282 parts phenol, 2.8 oxalic acid
After adding parts, the temperature was raised and the reaction was carried out at the reflux temperature for 2 hours.

After completion of the reaction, the temperature was raised to 130 ° C. under normal pressure while removing water, and the mixture was further reacted at the boiling point temperature for 2 hours. After completion of the reaction, the temperature was raised to 150 ° C. while removing water under normal pressure, and the temperature was further increased to 2 at the boiling point of the mixture.
Reacted for hours. 18 while removing water again under normal pressure
The temperature was raised to 0 ° C., unreacted phenol was removed under reduced pressure, and a composition containing a trifunctional compound was obtained.

The content of each functional compound component of the compound was determined by the peak area ratio of GPC according to the following conditions. Device: Tosoh Corp. Column: Showa Denko KK, SHODEX 803/8
02/802

Identification of peaks: compounds with tetrafunctionality or higher ... all peaks before retention time of 31 minutes trifunctional compounds ... 〃 peaks between 31 and 33 minutes bifunctional compounds ... 〃 Peak between 33 and 34 minutes As a result, the content of the trifunctional compound in the obtained composition is 35%, and the content of the bifunctional compound is 4%. The content was 61%.

Hereinafter, this composition is abbreviated as "H-1".

Synthetic Example 2 To 150 parts of pTBP, 217 parts of 41.5% formalin and 0.3 part of triethylamine were added and reacted in the same manner as in Synthetic Example 1 to obtain a methylol compound containing a pTBP dimethylol compound. Next, the system temperature is lowered to 50 ° C. or lower, and
-/ P-cresol (m-content 60% product) 216 parts, phenol 94 parts, and oxalic acid 3.0 parts were added and reacted in the same manner as in Synthesis Example 1 to obtain a composition containing a trifunctional compound. It was The content of trifunctional compound in this composition is 28%,
The content of the bifunctional compound was 8%, and the content of the tetrafunctional or higher-functional compound component was 64%.

Hereinafter, this composition is abbreviated as "H-2".

Synthesis Example 3 To 122 parts of p-ethylphenol, 217 parts of 41.5% formalin and 0.12 part of sodium hydroxide were added,
The reaction was carried out in the same manner as in Synthesis Example 1 to obtain a p-ethylphenol / dimethylol compound. Next, the temperature of the system was lowered to 50 ° C. or lower, 282 parts of phenol and 1.8 parts of oxalic acid were added and reacted in the same manner as in Synthesis Example 1 to obtain a composition containing a trifunctional compound. In this composition, the content of the trifunctional compound was 32%, the content of the bifunctional compound was 10%, and the content of the tetrafunctional or higher-functional compound was 58%.

Hereinafter, this composition is abbreviated as "H-3".

Synthesis Example 4 150 parts of pTBP, 40 parts of water and 8 parts of sodium hydroxide
50 parts, and after uniformly dissolving at 70 to 80 ° C., 50
It was cooled to 0 ° C. and 203 parts of 37% formalin was added. Fifty
The reaction was carried out at ℃ for 7 hours. Next, hydrochloric acid was added to this resin solution to adjust the pH to 7, and the resin solution was washed with 50 parts of water 8 times to obtain a pTBP resolated product. Then phenol 23
5 parts and 0.3 parts of oxalic acid were added and the temperature was raised, and the reaction was carried out at 100 ° C. for 10 hours. After completion of the reaction, the temperature was raised to 180 ° C. while removing water under normal pressure, and unreacted components were removed under reduced pressure. Thus, the novolak resin described in JP-A-63-254123 was obtained. The content of the trifunctional compound in this composition is 12%, and the content of the bifunctional compound is 1
0%, and the content of tetrafunctional or higher compound components is 78.
%Met.

Hereinafter, this composition is abbreviated as "H-4".

Synthesis Example 5 8 parts of sodium hydroxide was added to 108 parts of orthocresol, 203 parts of 37% formalin was added at 50 ° C., and the mixture was reacted at the same temperature for 6 hours. Next, hydrochloric acid was added to the resin solution to adjust the pH to 7, and the resin solution was washed 3 times with 50 parts of water to obtain an orthocresol resol compound. Next, 235 parts of phenol and 0.3 part of oxalic acid are added and the temperature is raised to 100 ° C.
Was reacted for 10 hours. After completion of the reaction, the temperature was raised to 180 ° C. while removing water under normal pressure, and unreacted components were removed under reduced pressure. Thus, the novolak resin described in JP-A-63-254123 was obtained. The content of the trifunctional compound in this composition is 7%, the content of the bifunctional compound is 8%, and the content of the tetrafunctional or higher functional compound component is 85%.
Met.

Hereinafter, this composition is abbreviated as "H-5".

Examples 1 to 3 and Comparative Examples 1 to 2 Epiclon 1121 [Dainippon Ink and Chemicals, Inc. brominated epoxy resin: epoxy equivalent 490] 100 parts of H-1 to H5 as a curing agent The compositions were formulated in the proportions shown in Table 1, respectively. At this time, Epicron 1121 and each curing agent were dissolved in methyl ethyl ketone before use. Next, 0.2 parts of 2-ethyl-4-methylimidazole (hereinafter abbreviated as 2E4MZ) as an accelerator was added to each of them, and the nonvolatile content of the solution was adjusted to 55% with methyl ethyl ketone. And the mixed solution of Comparative Examples 1-2 was prepared.

Thereafter, each mixed solution was impregnated in glass cloth and dried at 160 ° C. for 3 minutes to obtain a prepreg. Eight sheets of this prepreg were superposed, 35 μm of copper foil was superposed on both sides thereof, and heat and pressure molding was performed at 170 ° C. and a pressure of 40 kgf / cm ^{2 for} 1 hour to produce a double-sided copper clad laminate having a thickness of 1.5 mm.

Next, the laminated plate was subjected to an etching treatment to remove the copper foil, and then each physical property test was performed, and the results shown in Table 1 were obtained.

[0055]

[Table 1]

* 1: The appearance of the prepreg was visually judged. ◎: Very good ○: Good △: Slightly bad ×: Bad * 2: Temperature rising speed 3 ° C / min

* 3: Pressure cooker test (PC
In T), the test piece was treated in steam at 120 ° C. for a predetermined time. Solder resistance test is conducted in a 260 ° C solder bath after PCT treatment.
It was immersed in sec and evaluated. The evaluation was carried out by visually judging the appearance of the test piece, especially the presence or absence of a measling.

◯: No abnormality at all Δ: Slight measling occurred ×: Mesling present

As can be seen by comparing Example 1 and Comparative Example 1 in Table 1, even if a composition containing the same trifunctional compound was obtained using the same raw material, it was used as a curing agent for the epoxy resin. In the case of the presence of the trifunctional compound, it is understood that the one containing a larger amount of the trifunctional compound is more excellent in the prepreg appearance, the strength, and the moisture resistance / solder resistance.

[0060]

The curing agent for an epoxy resin of the present invention has a structure in which a phenol (B) is bonded to a mono-substituted phenol (A) through two methylene bonds and has an acidic hydroxyl group capable of reacting with an epoxy group. Since it contains a trifunctional compound having three in a specific ratio, a prepreg having an excellent appearance can be obtained, as compared with a conventional curing agent having a small content ratio thereof.
When the epoxy resin is cured, it has a particularly remarkable effect of giving a cured product excellent in terms of peel strength, interlayer adhesion represented by delamination strength, moisture resistance and solder resistance.

Claims (5)

[Claims] 1. A trifunctional compound (I) having a structure in which a phenol (B) is bonded to a mono-substituted phenol (A) through two methylene bonds, and a mono-substituted phenol (A).
A bifunctional compound (II) having a structure in which phenols (B) are bound to each other via one methylene bond, and a mono-substituted phenols (A) and / or a tetrafunctional or more functional group obtained from phenols (B). In the epoxy resin curing agent containing the compound (III), the content of the trifunctional compound (I) is 25% by weight or more of the whole, and the content of the bifunctional compound (II) is the whole. And 10% by weight or less, and the total content of the tetrafunctional or higher compounds (III) is 65% by weight or less of the total, a mixture of compounds, an epoxy resin curing agent. 2. The curing agent according to claim 1, wherein compound (I) is a compound obtained by reacting dimethylol-monosubstituted phenols with phenols (B). 3. A mono-substituted phenol (A) is an alkylphenol having a substituent having 1 to 5 carbon atoms,
The curing agent according to claim 1, wherein the phenol (B) is phenol and / or cresol. 4. The curing agent according to claim 1, wherein the mono-substituted phenol (A) is ethylphenol. 5. An epoxy resin composition comprising an epoxy resin and a curing agent, wherein the curing agent is a trifunctional structure in which a phenol (B) is bonded to a mono-substituted phenol (A) through two methylene bonds. -Functional compound (I), bifunctional compound (II) having a structure in which phenols (B) are bonded to mono-substituted phenols (A) via one methylene bond, mono-substituted phenols (A) and / In addition, tetrafunctional or higher functional compounds (II) consisting of phenols (B)
I), the content of the trifunctional compound (III) is 25% by weight or more of the whole, and the content of the bifunctional compound (II) is 10% by weight or less of the whole,
An epoxy resin composition for glass epoxy laminates, which comprises an epoxy resin curing agent having a total (III) content of the tetra- or higher-functional compounds of 40% by weight or less based on the whole.