JPS58173116A - Removal of trace halogen contained in epoxy resin - Google Patents

Abstract

PURPOSE:To lower the halogen content of an epoxy resin effectively, by reacting the resin prepared from an epihalohydrin with an organic acid silver salt in an amount nearly equivalent to the halogen groups contained in trace in the epoxy resin and then filtering off the formed precipitate. CONSTITUTION:An epoxy resin of a polyglycidyl ether type is prepared by reacting an epihalohydrin (e.g., epichlorohydrin) with a polyhydricphenol (e.g., bisphenol A) in the presence of an alkali. Then, the total amount of hydrolyzable and nonhydrolyzable halogen groups contained in the produced epoxy resin is measured, for example, by a flask combustion method. Then, the epoxy resin is purified by dissolving, if necessary, the resin in an organic solvent (e.g., toluene) and reacting it with an organic acid silver salt (e.g., silver nitrate, silver lactate) in an amount nearly equivalent to the halogen groups, and filtering off the formed precipitate after completion of the reaction.

Description

[Detailed description of the invention] The invention relates to epoxy resins.

Generally, a polyglycidyl ether type epoxy resin is obtained by the reaction of epihydrin and polyphenol, but no matter how the reaction is controlled, hydrolyzable or non-hydrolyzable halide is inevitably present as an impurity. The amount of p-gen groups included was extremely difficult to remove. Furthermore, there are many uses in which the trace amount of halogen groups present as a serious defect, and there has recently been a particular demand for the removal of these halogen groups. For example, in the electronics industry, when epoxy resin-based paste is used as a thick film material, even the presence of a small amount of halogen groups can cause performance deterioration during long-term use.

Conventionally, it has been common practice to wash polyphenol glycyl ether type epoxy resins produced by normal methods with an alkaline aqueous solution; It has no effect on removing halogen groups. It is known that under severe conditions such as the pressure Kutzker test, not only hydrolyzable halogen groups but also non-hydrolyzable halogen groups are decomposed to generate halogen ions.

Therefore, it is necessary to remove as much as possible not only hydrolyzable halogen groups but also non-hydrolyzable halogen groups, which cause the generation of such ionic impurities in the resin. However, until now, no suitable method has been found for this purpose.

The present inventors focused on these points and, as a result of various studies, found that after reacting an approximately equivalent amount of organic acid silver with a trace amount of halogen group contained in the epoxy resin, the precipitate formed was removed. The inventors have discovered that epoxy resins can be purified by removing the epoxy resin, and have accomplished the present invention.

The purification method of the present invention is effective in removing hydrolyzable and non-hydrolyzable halogen groups, and deterioration during long-term use is a problem in various applications of epoxy resins. The benefits to electronics-related applications such as this are immeasurable.

The epoxy resin used in the present invention is a polyglycyl ether type resin obtained by a method of reacting polyphenol and epihalohydrin in the presence of an alkali.

In this case, the polyphenol is bisphenol A
1 Bisphenol F1 At least one selected from the group consisting of bisphenols such as phenolphthalein and polyphenols such as novolaks and polyvinylphenols. The epihalohydrin includes at least 1 to 11 compounds selected from the group consisting of epichlorohydrin, epibromohydrin, dichlorohydrin, those that generate epihalohydrin such as dibromohydrin, and derivatives thereof such as β-alkyl epihalohitin. It is.

A polyglycyl ether type epoxy resin of polyphenol obtained from polyphenol and epihalohydrin necessarily contains a small amount of halogen group. This is due to by-products generated by various side reactions, such as those where the epoxy group of epihalohydrin is cleaved and bonded with bisphenol A, resulting in a halogen group at the end, or when this compound is further reacted with epihalohydrin. There is. Among the halogen groups contained in the polyglycyl ether of polyphenols, those that are hydrolyzed by o and 1 are defined as hydrolyzable halogen groups, and strong halogen groups that are not hydrolyzed even by carcass treatment are called non-hydrogen groups. It is called a hydrolyzable halogen group. However, even with so-called non-hydrolyzable halogen groups, hydrolysis may progress gradually over time depending on treatment in water at 125°C for 1 to 7 days (pressure test). As is known, the difference in reactivity between the two halogen groups is not so absolute. The sum of hydrolyzable and non-hydrolyzable halogen groups, that is, the total amount of halogen groups, is measured by the oxygen flask combustion method. That is, the resin is completely combusted in a flask filled with oxygen, the generated halogen is absorbed into an absorption liquid, and then quantified as halogen ions.

The total amount of halogen groups referred to here refers to the amount of halogens bonded as part of the resin, and does not include the amount of ionic halogens due to impurities such as inorganic salts such as alkali halides. It is something. The amount of ionic hydrogen is usually determined by extracting it from the resin with water. Generally, halogens in epoxy resins become more difficult to remove in the order of ionic, hydrolyzable, and non-hydrolyzable. In general, it is easy to reduce the content of ionic nitrogen to 10ppm or less by sufficiently washing with water, and the epoxy resin of the present invention is designed to maintain this level before and after the treatment of the present invention. It shall be thoroughly washed with water.

In order to carry out the purification of the present invention, inorganic impurities containing chloride ions, such as salt, and organic impurities containing chloride ions, such as unreacted shrimp halohydrin, must be removed by filtration, washing with water, etc. It is desirable to remove and purify as much as possible in advance by a conventional method such as distillation.

The soluble organic acid silver used in the present invention refers to C2 to (lo
It is a silver salt of at least one organic acid selected from the group of aliphatic to aromatic mono- and dicarboxylic acids and their oxyacids. Among these, it is preferable to appropriately select one that has good compatibility with the skeleton epoxy resin because the reaction with the halogen group can proceed more smoothly.

The total amount of halogen groups contained in the epoxy resin used in the present invention varies greatly depending on the type of polyphenol, molecular weight, oxidation value, manufacturing conditions (including conventional purification methods), etc., but is 100 ppm or less. It is extremely difficult to reduce the content to 100 ppm or less, preferably 50 ppm or more by applying the purification method of the present invention.
It has become possible to reduce the amount to less than ppnn.

The purification method of the present invention provides for such an epoxy resin,
This is a method in which an approximately equivalent amount of organic acid silver salt is added and reacted with the rogene group, and then the precipitate that is deposited is filtered and removed. It is not preferable to use a large excess of organic acid silver salt because a large amount remains. If such a reaction between a halogen group and a silver salt of an organic acid is carried out at a high temperature of 160°C or higher, the epoxy group may be consumed, so it is not preferable.
It is desirable to carry out the heating at 120°C. In this case, an appropriate solvent may be used to reduce the viscosity of the system and make it easier to react.

As the solvent, aromatic hydrocarbons such as benzene, toluene, xylene, etc. are preferable. As the halogen group of such an epoxy resin reacts with the silver salt of an organic acid, no.
A precipitate consisting mainly of silver halogenide is successively deposited, and the number of halogen groups decreases. By removing the precipitate after the completion of the reaction, the amount of logen groups in the epoxy resin can be reduced.

If the V filtration is performed using ordinary P paper, the removal of the precipitate is somewhat insufficient or insufficient, and it is desirable to use a membrane or mesh with a pore diameter of about 0.3 to 3 μm. During filtration, an appropriate solvent may be used for rounding to lower the viscosity, or heating may be used.

In the purification method of the present invention, (1) the reaction proceeds homogeneously in an organic solvent system, (2) the -logen forms an insoluble precipitate that can be easily removed by filtration, and (2) the conventional method It is possible to remove all halogen groups, including non-hydrolyzable halogen groups, which were thought to be impossible to remove; ■The purification reaction is carried out under mild, approximately neutral conditions; It can be carried out without deteriorating the quality of the epoxy resin, and ■ Even if a small amount of organic acid silver salt, which is a halogen group removal agent, remains unreacted, it has almost no adverse effect on the properties of the resin. is % mold.

The epoxy resin subjected to the purification treatment of the present invention has a reduced halogen content to a high level that exceeds the limits of conventional methods, and is suitable for various applications in the electronics field, such as sealing, thick film materials, and painting. Extremely useful for use, casting, etc.
This is a stutter that has been long awaited in the industry.

Example 1 Bisphenol A diglycidyl ether type epoxy resin (viscosity 140 voids/25°C, epoxy equivalent weight 190, molecular weight 380, hydrolyzable chlorine group 160 pp
m, total chlorine group content LOOOppm) 100 parts (
200 parts of toluene was added to the solution (the same applies hereinafter) and dissolved in a bath.
Add 0.47 parts of silver acetate to this and react under reflux for 4 hours. - After leaving it overnight, if you heat it with regular paper, colloidal floating matter will remain and the system will be slightly warm. Add this to 0
．． The system becomes completely transparent after pressure filtration using a 45μ pore size Teflon membrane. Completely remove toluene by vacuum distillation.

The obtained epoxy resin had a viscosity of 165° C., an epoxy equivalent of 204, a molecular weight of 417, a hydrolyzable chloro group content of 35 ppm, and a total chloro group content of 110 ppm.

If necessary, it is possible to further reduce the chloro group content in each by approximately half by repeating the above operation.

Example 2 Polyglycyl ether of novolak obtained by condensation reaction of phenol formaldehyde under acidic conditions (
Viscosity 14 voids 152°C, epoxy equivalent 175, molecular weight 5601, hydrolyzable chloro group content 540 ppm, total ol group content 2200 ppm) 600 parts of benzene was added to 100 parts and dissolved, and 1.35 parts of silver lactate was added to this. 1 part and reacted under reflux for 8 hours. - After being left overnight, the system becomes completely transparent when the precipitate is removed by filtration through ordinary P paper and then pressure filtration using a Teflon membrane with a pore size of 045 μm. Benzene is completely removed by vacuum distillation. The obtained epoxy resin had a viscosity of 16 voids at 152°C,
Epoxy equivalent weight 180, molecular weight 57o1, hydrolyzable chlorine group content 46 ppm, total chlorine group content 124 ppm
Met. In short, by repeating the above operation,
It is possible to approximately halve the respective chloro group content.

Comparative Example 1 For 100 parts of the untreated epoxy resin of Example 1, 10
Add 1 part of aqueous solution of caustic soda (by weight) to 1 part at 90℃
Let the reaction take place while stirring vigorously. Then at 100℃ 4
After completely removing water under reduced pressure of 0 wHf, sodium chloride is removed by heating at 100°C.

The obtained epoxy resin had a viscosity of 248 voids/25°C, an epoxy equivalent of 264, a molecular weight of 543, and a hydrolyzable chloro group content of 75 m) T) m-Total chlorine group content of 915 p
It was pm. In this way, treatment with an aqueous alkali solution is effective in reducing the content of hydrolyzable chlorine groups, and repeated treatments can further reduce the content, but the content of non-hydrolyzable chlorine groups is reduced. shows almost no effect.

Patent creator: Sumitomo Bakelite Co., Ltd. 98-

Claims (1)

[Claims] Patented for reacting a small amount of halogen groups contained in an epoxy resin obtained by the reaction of shrimp halohydrin and polyphenol with a small amount of organic acid silver, and then removing the precipitate formed by F. Method for purifying epoxy resin.