JPS636571B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing chlorine groups contained as impurities in epoxy compounds.

In general, epoxy compounds are obtained by the reaction of epichlorohydrin or its equivalent substance with a compound having an active hydrogen group;
Methods based on peracid oxidation of carbon double bonds, ○C, and others.

The epoxy compounds obtained by these methods are extremely useful as raw materials for thermosetting resins, and many of them are in practical use. However, it contains aliphatic primary chlorine groups as impurities due to side reactions, and the value usually reaches 1000 ppm or more, and depending on the conditions, it can be hydrolyzed to liberate chloride ions, which can be used in electronics. It has long been desired to reduce this amount as much as possible in applications such as industrial use.

Conventionally, a small amount of alcoholic caustic solution is added to the epoxy compound as a processing agent, heated at 50 to 100°C for several to several tens of minutes, and reacted to form free chlorine ions, which are then removed by washing with water. has been taken. In this method, of all the chlorine groups, only the easily hydrolyzable chlorine groups present in a relatively small proportion are mainly removed, and the hardly hydrolyzable chlorine groups, which account for the majority, remain as they are. This is undesirable since a large amount of epoxy groups will be consumed at the same time if the treatment is performed under harsher conditions in order to further remove the epoxy groups. In addition, in electronics applications, it is necessary to remove hydrolyzable chlorine groups, including those that are difficult to hydrolyze.

On the other hand, with the recent remarkable development of the electronics industry, it has evolved into transistors, ICs, LSIs, and VLSIs, and the degree of circuit integration in these semiconductor devices has rapidly increased. Regulations on the amount of alcohol are gradually becoming stricter. This trend is explained by the fact that the test method initially targeted only relatively easily hydrolyzable chloride groups, such as those that liberate chloride ions by boiling in methanolic caustic solution for 15 minutes, but recently it has changed. This is clear from the fact that chlorine groups, which are quite difficult to hydrolyze, are now being targeted, which can easily be ionized by boiling with ethanolic caustic alkali in dioxane solution for 30 to 60 minutes.

In this way, there has been a need for a purification method that removes hydrolyzable chlorine groups, including chlorine groups that are quite difficult to hydrolyze, while minimizing the consumption of coexisting epoxy groups. .

The present inventors conducted various researches in an attempt to improve the conventional purification method, which has not been able to sufficiently remove harmful impurities without altering the epoxy compound containing resin and reactive diluent.
We learned that treatment with a solid treatment agent such as OH-type anion exchange resin is effective. (Reference Patent Application No. 58-159040) Through further detailed study,
We found that a sufficiently dried strongly basic ion exchange resin that retains OH ions or anions with the same efficacy is particularly effective.
Based on these findings, various studies have been carried out and the present invention has been completed.

The objective is to improve the reliability of epoxy resin compositions used in the electronics industry by providing an effective means for removing organic chlorine groups, including impurities in epoxy compounds, including those that are difficult to hydrolyze. The aim is to significantly improve the

Conventionally, epoxy compounds contain at least 1000 ppm of chloro groups as impurities, and it has been difficult to reduce this by examining reaction conditions, but by applying the purification method of the present invention, Purity can be significantly increased to 600 ppm or less, preferably 300 ppm or less.

In the electronics industry, the fewer chloro groups in an epoxy resin, the more advantageous it is in terms of reliability, and the method of the present invention is extremely useful for this purpose.

The method for quantifying total chlorine of the present invention involves completely burning an epoxy compound in an oxygen oven to form chlorine ions, which are then determined by a conventional quantitative method using silver nitrate. The amount of organic chlorine groups is obtained by subtracting the amount of chlorine ions from the total amount of chlorine. The amount of chlorine ion is extracted from the resin with water, and the extracted water is determined by a conventional method. In general, ionic impurities such as chloride ions can be easily reduced to 10 ppm or less by washing with water, so they are generally hardly contained in resins used for electronics.

The present invention provides a method for removing chloro groups contained as impurities by dissolving an epoxy compound in an organic solvent and contacting it with a strongly basic anion exchange resin. This is a method for purifying an epoxy compound, characterized in that each exchange resin has been adjusted in advance to have a water content of 0.5% (by weight, the same hereinafter).

In this case, the anion exchange resin may contain one or more anions having the same effect as OH ions, such as CN ions, SCN ions, OCN ions, etc., instead of or in addition to OH ions. Further, in this case, an H-type cation exchange resin may be used in combination with the above-mentioned anion exchange resin. It is preferable to use various types of ion exchange resins in combination in this way because it is possible to further enhance the purification effect.

The strongly basic ion exchange resin used in the present invention is
It has a skeleton of crosslinked polystyrene resin, and a quaternary ammonium group is directly bonded to a phenyl nucleus.

They are called OH type, CN type, etc. depending on the type of anion adsorbed by ionic bond.

For the purpose of the present invention, the chloro group in the epoxy compound is brought into contact with a strongly basic anion exchange resin of the type that retains the OH type and/or anion with the same potency as the OH type, and the chlor group in the ion exchange resin is
The purpose is to exchange the harmful chloro group with a harmless OH group and/or an equally harmless group by carrying out a substitution reaction with an ion or an anion having the same potency.

The purification reaction of the present invention is schematically represented by the following formula.

-X+-Cl→-Cl+-X However, X: -OH and/or a group having the same effect as this: Ion exchange resin body: Epoxy compound body The mechanism of this reaction is as follows.

irreversible reaction, Heterogeneous reactions between solid and liquid, Exchange reaction of X ion/−Cl group between / Therefore, the following condition adjustments are required.

○The relationship between A and X is stable, and hydrolysis and release of ions are unlikely to occur. For this purpose, OH, CN, OCN, SCN, SH, S, etc. are suitable for X.

○B The stability of the ion exchange resin is -X<
- Must be Cl. For that reason, X is OH,
CN, OCN, SCN, SH, S etc. are suitable.

○C The molar ratio of -X/-Cl is in large excess, that is, from 2/1 to 30/1.

○D Do not contain compounds with active hydrogen such as H ₂ O and R-OH.

○E-X must be properly moistened or penetrated with solvent.

○F −Cl must be sufficiently diluted with a solvent and have a low viscosity.

○G The system is sufficiently stirred and there is sufficient contact between the two.

That is, when converting a chloro group contained in an epoxy compound into an OH group and/or a group having the same effect through a substitution reaction, the above conditions must be met in order for this reaction to proceed smoothly. Preferably. For this purpose, OH ions and/or
The molar ratio between the sum of anions having the same potency as OH ions, that is, the total exchange capacity, and the chlorine groups to be removed contained in the epoxy compound needs to be as large as 2/1 or more. .
If the amount is less than this, the reaction becomes extremely slow and the substitution rate decreases, which is not preferable. If the ratio is greater than 30/1, the reaction will be somewhat faster, but the loss of the epoxy compound that is adsorbed to the ion exchange resin will increase, the amount of solvent used will be excessive, and the loss of the expensive ion exchange resin will increase. Undesirable.
The ion exchange resin used must be completely dehydrated. i.e. acetone, dioxane,
After being immersed in a hydrophilic solvent such as methanol for a long time,
Filter the solvent and store it in a vacuum desiccator between room temperature and 50℃.
It is desirable to leave it for a long time under heating until it dries thoroughly. Moisture content is 0.5% (weight, same below)
The content below is preferably 0.1% or less. If the water content is higher than this, the above-mentioned exchange reaction becomes somewhat difficult to occur, and the desired removal of organic chlorine groups becomes somewhat difficult to achieve, which is not preferable. In this case, the moisture in the reaction system must be dried to the same level, so both the epoxy resin and the solvent must be
It is necessary that the water be sufficiently dehydrated to a moisture content of 0.5% or less, preferably 0.1% or less.
As an example, trace amounts of water can be removed by dissolving an epoxy resin in a dehydrated aromatic hydrocarbon and distilling the resulting azeotrope. By removing water from the system in this way, the removal rate of chlorine groups is at least 10 to
It is possible to improve by 30%. Furthermore, since the reaction is a heterogeneous reaction that occurs only at the solid-liquid interface, in order to facilitate mutual contact, the particle size of the ion exchange resin is made small to increase the surface area, and a solvent is used to bind the epoxy resin. It is preferable to accelerate the reaction by lowering the viscosity and increasing the agitation. Mild reaction conditions are preferable because the selectivity of the reaction tends to be greater. i.e. room temperature to 50℃
A reaction time of 10 to 100 hours at a slightly lower temperature is suitable. High temperatures of 50° C. or higher are not preferred because side reactions tend to occur. Temperatures below 10°C are not preferred because the reaction becomes slow.

Therefore, the features of the purification reaction of the present invention are as follows.

Since the chlorine ions to be removed are not in a free state but are solidified by binding to the ion exchange resin, they can be easily and reliably removed by filtration.

OH ions, CN ions, OCN ions, SCN ions, etc. as reaction reagents are not in a free state but are bound to solid ion exchange resin as a carrier, so they are hydrophobic and contain almost no water or alcohol. It can work effectively even in organic solvent systems.

By reacting for a long time under mild conditions, it is possible to adjust the reaction so that it selectively proceeds with the substitution of Cl groups as the main reaction.

Hydrophobic solvents are preferred for use in the present invention because they are difficult to absorb water and are easily compatible with the anion exchange resin itself since it is completely dry. Moreover, it is preferable that the solvent does not contain active hydrogen that easily reacts with epoxy groups.

That is, hydrocarbon solvents such as benzene, toluene, xylene, cyclohexane, tetralin, and decalin are suitable. However, solvents that are easily deteriorated by strong alkalis, such as esters and ketones, are undesirable. Note that the solvent used needs to be of high purity and does not contain halogen compounds or halogen ions as impurities.

The epoxy compound of the present invention is obtained by condensing epichlorohydrin and an active hydrogen compound in the presence of caustic alkali.
This type of epoxy compound can be divided into monofunctional ones with one epoxy group/molecule and polyfunctional ones with two or more epoxy groups, and the type of active hydrogen compound, i.e., alcohols. There are two classifications based on phenols, carboxylic acids, amines, mercaptans, etc. Among them, polyfunctional ones are generally used as epoxy resins, and monofunctional ones are used as reactive diluents for epoxy resins. Among these, typical epoxy resins are polyglycidyl ether type polyphenols. In addition,
Even if they are multifunctional, they are liquid, low viscosity, and low volatile, such as polyglycidyl ethers of polyols such as glycol, glycerin, and pentol, and polyglycidyl ethers of polyacids such as adipic acid, sebacic acid, and dimer acid. Diel esters and the like are also used as reactive diluents. Monofunctional reactive diluents are liquids with low viscosity at room temperature and have low volatility, i.e. boiling point of 200°C.
The above are preferable, and both higher aliphatic hydrocarbon-based glycidyl ether type and glycidyl ester type are equally usable.

Many of the above types of epoxy compounds are particularly important in the field of epoxy resins. One of the reasons for this is that it has excellent curability and physical properties after curing.

However, the above-mentioned type of epoxy compound essentially contains an aliphatic primary chloro group due to a side reaction. When this chlorine group is boiled with caustic alkali or high-pressure water, it gradually decomposes to liberate chloride ions. The chlorine ions generated in this way may corrode the aluminum wiring of LSIs and VLSIs, and may cause abnormalities to occur during long-term energization tests under high humidity, reducing reliability. It is desired that the amount of chlorine ions generated be as small as possible. To this end, it is necessary to minimize the amount of all chloro groups, mainly organic chlorine groups, which cause this. Note that all the chloro groups do not contain aromatic nuclear-substituted halogen groups. In addition, chlorine ions can be easily removed to less than 10 ppm by washing with water.

In response to such demands, the method of the present invention is effective in greatly reducing the amount of chloro groups as impurities and increasing the purity of the epoxy resin while keeping the other properties of the epoxy resin as unchanged as possible.

Examples will be explained below.

Example 1 Epoxidized novolac (chlor group, 1000 ppm,
Epoxy equivalent, 190, viscosity 75 poise/25℃, number average molecular weight, 680) is dissolved in 800 g of anhydrous toluene, and 400 g of toluene is distilled off under reduced pressure (moisture
0.02%). Next, OH-type strongly basic anion exchange resin powder (exchange capacity: 1 milliequivalent/1 ml, particle size 30 to
300 microns, moisture: 0.2%) was added to the above epoxy resin solution and stirred at 50°C for 20 hours.

Next, the exchangeable resin powder is separated, washed with toluene, and desolventized in vacuum. The obtained epoxidized novolac had a chlorine group content of 450 ppm, an epoxy equivalent of 210, a viscosity of 100 poise/25°C, a number average molecular weight of 780,
The yield was 96% by weight, and there was almost no change in the appearance or color tone of the resin.

Note that it is extremely difficult to reduce the chloro groups in this epoxy resin to such a level by adjusting only the reaction conditions. Therefore, when the obtained highly purified epoxidized novolak was combined with silver powder and used as a conductive mount resin composition, a remarkable difference in reliability was observed compared to the untreated one.

Reference Example 1 For 200 g of epoxidized novolac of Example 1, 10 ml of 0.1N alcoholic potassium hydroxide solution,
Add 400 ml of toluene and carry out reflux reaction for 15 minutes. After washing the system with water, 4 ml of 0.1N alcoholic potassium hydroxide solution was added and the mixture was refluxed for 15 minutes. Rinse the system with water,
Remove solvent. The obtained epoxidized novolac had a chloro group content of 920 ppm, and other physical properties were not significantly different from the original resin. By this treatment, the easily hydrolyzable chlorine groups were almost completely hydrolyzed, and the molecular weight, epoxy equivalent, number average molecular weight, viscosity, etc. of the epoxy resin were not significantly different from the original. It should be noted that this level of removal of chlorine groups is insufficient for use in electronics.

Reference Example 2 For 200 g of epoxidized novolac of Example 1, 20 ml of 1N-alcoholic caustic potassium and dioxane
Add 400 ml and react under reflux for 30 minutes, then remove the solvent under reduced pressure.

The obtained epoxidized novolak had a chloro group content of 650 ppm, an epoxy equivalent of 1130, a softening point of 102°C, and a number average molecular weight of 1210. Although the amount of chloro groups has been reduced to an almost satisfactory value, a large amount of epoxy groups are consumed, which is not desirable.

Example 2 Glycidyl ester of _C12 aliphatic monocarboxylic acid (chloro group 1800 ppm, epoxy equivalent 245,
Viscosity 7.0 centipoise/25℃, boiling point 280℃, number average molecular weight 250, water 0.3%), SCN type strong basic ion exchange resin beads: 80 mol%
SCN type with residual OH type (total exchange capacity of both ions 4 milliequivalents/ml, particle size 0.1
~0.4mm, moisture 0.05%) 20g was added, 80 hours, 30
Stir at °C.

Next, the exchangeable resin beads are separated, washed several times with toluene, and desolventized in vacuum. The obtained monoepoxy ester has a chloro group content of 320 ppm, an epoxy equivalent of 265, a viscosity of 7.3 centipoise/25°C, and a boiling point.
275℃, number average molecular weight 255, yield 95% by weight,
There was almost no change in appearance except that the color tone of the resin became slightly lighter.

Note that it is extremely difficult to reduce the chloro groups in this epoxy resin to such a level by adjusting only the reaction conditions. Therefore, the highly purified epoxy compound obtained is extremely useful as a highly purified reactive diluent compared to an untreated epoxy compound. That is, when used in combination with the highly purified epoxy resin of Example 1, it is extremely reliable as a resin for semiconductor processing such as semiconductor encapsulation and chip mounting.

Example 3 Bisphenol F type epoxy resin (chlor group:
760ppm; Epoxy equivalent: 185; Viscosity 40 poise 25
℃; Number average molecular weight: 410) is dissolved in 800 g of anhydrous xylene (moisture 0.01%), and 400 g of xylene is distilled off under reduced pressure to dehydrate. (Moisture in the system: 0.05%)
Next, OCN type strongly basic anion exchange resin beads (exchange capacity: 1.5 milliequivalents/ml; particle size 0.1 to 0.3 mm,
Add 200 ml (water content 0.1%) to the above epoxy resin solution and stir at room temperature for 95 hours. Next, the exchangeable resin beads are removed and the solvent is removed in vacuum. The obtained epoxy resins had no major differences in other properties except that the chloro groups were 270 ppm. Note that it is extremely difficult to synthesize such a highly pure resin using conventional methods.

Claims (1)

[Claims] 1. A method for removing chloro groups contained as impurities by dissolving an epoxy compound in an organic solvent and contacting it with an OH-type strongly basic anion exchange resin, the method comprising: A method for purifying an epoxy compound, characterized in that the organic solvent and anion exchange resin are both adjusted in advance to have a water content of 0.5% (by weight, the same hereinafter) or less. 2. The purification method according to claim 1, wherein the anion exchange resin retains at least one anion selected from the group of OH ions, CN ions, SCN ions, and OCN ions. . 3 Reaction temperature is 10 to 50℃, reaction time is 5 to 50℃.
Claim 1 or 2 which is 100 hours
Purification method described in section. 4. The amount of the anion exchange resin used is such that the molar ratio of the chloro group of the epoxy compound to the total amount of anions it possesses is 2/1 to 30/1. , the method according to item 2 or 3. 5 Claims 1, 2, and 3 in which an H-type cation exchange resin is also used in the reaction.
or the method described in paragraph 4.