JPH044216A - Novolak resin of phenols and curing agent for epoxy resin - Google Patents

Abstract

PURPOSE:To obtain a novolak resin of phenols, having a specific structural formula, excellent in heat resistance with low water absorptivity and capable of providing cured products of an epoxy resin suitable as insulating materials, etc., by adding and blending thereof as a curing agent with the epoxy resin. CONSTITUTION:A novolak resin of phenols is obtained by reacting a phenylphenol (preferably o-phenylphenol) with formaldehyde at a ratio of preferably 0.5-1.0mol formaldehyde to 1mol phenylphenol in the presence of an acid catalyst such as hydrochloric acid in a solvent such as benzene. The aforementioned resin has a structural expressed by the formula (n is 0-30, preferably 2-15) with <=20wt.%, preferably <=15wt.% content of a phenylphenolic novolak resin (n is 0).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a phenolic novolak resin, and the resin of the present invention is useful as a curing agent for epoxy resins.

[Conventional technology]

In general, phenolic resins are good for adhesion, chemical resistance, electrical properties,
Due to its excellent mechanical properties and heat resistance, it is widely used as a curing agent for electrical insulation materials, adhesives, etc.

Particularly, in the field of IC sealants, phenolic resins are used as curing agents for epoxy resins. This is because phenolic resins are more advantageous than other curing agents in terms of heat resistance and water absorption.

[Problem to be solved by the invention]

However, even if this phenolic resin is used and cured, its water absorption is still insufficient.

That is, in surface mounting accompanying the recent development of electronic materials, heat resistance sufficient to withstand the harsh temperature conditions of immersing the cured product in a solder bath is not satisfied. Moreover, in the nada bath, moisture that has entered the cured product evaporates explosively, causing destruction of the cured product. Therefore, keeping the water absorption of the cured product low is an extremely important issue as well as heat resistance.

[Means to solve the problem]

In order to solve these problems, the present inventors have made intensive studies and found that by converting phenylphenol into a novolak and using a novolac resin with less low molecular weight components as a curing agent for epoxy resin, the heat resistance can be improved. The present inventors have discovered that it is possible to obtain a cured epoxy resin with good water absorption properties, and have completed the present invention.

That is, the present invention provides a phenylphenol novolak resin represented by the general formula [I] (in which the average value of n is 0 to 30), in which the content of the 7-enylphenol novolak resin where n = O is 20% by weight. % or less, and a curing agent for epoxy resin made from the same.

When the phenolic novolak resin of the present invention is used as a curing agent for epoxy resin, it has a particularly high water absorption property compared to a cured epoxy resin obtained by using conventional phenolic resin as a curing agent for epoxy resin. This provides a highly advantageous cured epoxy resin product.

The n = O component in the phenolic novolak resin of the present invention is 20% by weight or less, preferably 15% by weight.
It is as follows.

When the content of the component where n=o exceeds 20% by weight, the number of functional groups decreases, which does not meet the objective of the present invention, which is to maintain heat resistance.

Further, the average value of n in the phenylphenol novolac resin represented by the general formula [I] is 0 to 30, preferably 2 to 20, and more preferably 2 to 15.

Examples of the phenylphenol component in the above general formula [■] include ornophenylphenol, paraphenylphenol, and metaphenylphenol, but ornophenylphenol is preferably used for the purpose of reducing the amount of low molecular weight substances in the present invention.

The phenolic novolac resin of the present invention can be produced, for example, in the following manner.

That is, it can be obtained by dehydrating and condensing phenylphenols and formaldehyde in the presence of an acid catalyst, extracting the low molecular weight substances with hot water, and removing the low molecular weight substances.

As the acid catalyst, known hydrochloric acid, sulfuric acid, p-toluenesulfonic acid can be used, and the reaction is preferably carried out in a solvent such as benzene or toluene.

The reaction temperature can be carried out in the range of 50 to 100°C.

The amount of reaction between phenylphenols and formaldehyde is preferably such that formaldehyde is used in a molar ratio of 05 to 10 per mole of phenylphenols, and the acid catalyst is preferably used in a ratio of 01 to 10 per mole of phenylphenols. .

After the reaction is completed, the used catalyst is removed by washing with water or the like, the solvent and phenylphenols are distilled off under reduced pressure, and the low molecular weight substances are further removed with hot water to obtain the phenolic novolak resin of the present invention.

The phenolic novolak resin of the present invention is used in fields where heat resistance and particularly low water absorption are required, specifically in the fields of insulating materials, laminates, sealing materials, etc. Cresol novolac epoxy resin, phenol novolac epoxy resin It can be used as a curing agent for epoxy resins such as novolac type epoxy resins such as, bisphenol epoxy resins such as bisphenol A type epoxy resins, etc.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 170 g (1 mol) of orthophenylphenol and 2 paraformaldehyde were placed in a glass container equipped with a thermometer and a stirrer.
4 g (o, s mol) and 150 mol of hidruene were charged, and the mixture was stirred at a bath temperature of 80° C. under a nitrogen atmosphere.

1 g of P-1 sulfonic acid was gradually added while being careful not to generate heat.

After the addition, the reaction was continued for 10 hours while keeping the bath temperature at 80°C, and then the reaction was completed.

After that, Toluene 300II! /, wash with water,
Returned to neutral.

The organic layer was concentrated under reduced pressure to obtain 175 g of product. Furthermore,
The obtained product was washed five times with 500Q: hot water. During this washing, the product was stirred to disperse it as much as possible, and the hot water was removed by decantation.

The softening temperature (JI
S K2425 ring and ball method) is the hydroxyl equivalent (g/m
o+) was 180.

Example 2 In Example 1, the amount of paraformaldehyde was changed to 18 g.
Product (B) was obtained in the same manner as in Example 1 except that (0.6 mol) was used.

The softening temperature of the product (B) is 93°C, and the hydroxyl equivalent is 17
It was 8.

Example 3 A bioacid (C) was obtained in the same manner as in Example 1 except that paraphenylphenol was used in place of orthophenylphenol.

The softening temperature of the product (C) is 103°C, and the hydroxyl equivalent is 1
It was 78.

Comparative Example In Example 1, product (D) was obtained without performing the extraction operation with hot water.

The softening temperature of the product (D) is 90°C, and the hydroxyl equivalent is 1i1
It was 78.

Products (A) and CB obtained in Examples 1 to 3 and Comparative Examples
As a result of GPC analysis of >, (C), and (D), -
] The content of the component n = O in the phenylphenol novolank resin and the average value of n were as follows.

(A) 13 4.2 (B) 18 3.
5(C) 18 3
．． 7(D)25 3.1 The analysis conditions are as follows.

GPC device: Takasugi Seisakusho (fy Ram: TSK-G-3000XL (1 piece) +
TSK-G-2000XL (2 bottles) Solvent: Tetrahydrofuran 1-/min Detection: UV (254 nm) Commercially available ortho-cresol novolac type epoxy resin (manufactured by Nippon Kayaku, EOCN1020, Evo-"f)
- Equivalent (g/rnol) 200, Softening temperature 67
The products (A), (B), and (C) obtained in Example 1.2.3 were blended with 2-methylimidazole as a curing accelerator and heat-cured.

As an applied comparative example, the product obtained in Example 1.2.3 (
Instead of A), (B), and (C), the product (D) obtained in the comparative example at the compounding ratio (parts by weight) shown in Table 1, and a commercially available phenol novolac resin (manufactured by Nippon Kayaku ■, Softening temperature 85
C. and hydroxyl equivalent (g/rnol) 105).

The measurement sample was a composition with the amount shown in Table 1 at 70°C.
After roll mixing at ~80°C for 15 minutes, it was cooled, pulverized (formed into tablets), and further formed into ridges and post-cured using a transfer molding machine.

Post-cure conditions Temperature: 180° C. Glass transition temperature (Tg), heat distortion temperature (HDT), and water absorption of the cured product after 28 hours or more were measured, and the results are shown in Table 1.

The measurement conditions for glass transition temperature, heat distortion temperature, and water absorption are as follows.

Glass transition temperature thermomechanical measuring device (TMA): Vacuum Riko TM-7000 Heating rate: 2°C/min Heat deformation temperature JIS K7207 Water absorption rate Test piece Diameter 50III + Thickness 3m
Disc conditions Water absorption rate (weight %) based on weight increase after boiling in water at 100°C for 50 hours [Effects of the invention] As is clear from Table 1, the phenolic novolak type resin of the present invention has a Since it provides a cured epoxy resin that achieves low water absorption while retaining the heat resistance of phenolic resin, it is mainly useful as a curing agent for epoxy resins, and is useful in industrial fields where low water absorption is required. Great value.

Claims (2)

[Claims] (1) General formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[I] (In the formula, the average value of n is 0 to 30.) In the phenylphenol novolac resin, n = 0 phenylphenol A phenolic novolak resin, characterized in that the content of the novolak resin is 20% by weight or less. (2) A curing agent for epoxy resin, comprising the phenolic novolac resin according to claim 1.