JPS636572B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for removing organic chlorine groups contained as impurities in epoxy compounds. [Prior Art] Generally, industrially useful thermosetting resins or epoxy compounds as modifiers thereof are mainly produced by reacting epichlorohydrin or a substance with the same effect with a compound having active hydrogen. However, it has been said that the epoxy compound obtained by such a method inevitably contains an aliphatic primary chloro group as an impurity due to a side reaction. Normally, even if you try to reduce this value by changing reaction conditions, the limit is 1000 ppm at most, and when applied to the electronics field, depending on the conditions, it may hydrolyze and liberate a large amount of chlorine ions, which may significantly reduce its reliability. It was hot. Therefore,
A significant reduction in organic chlorine groups contained as impurities in epoxy compounds has long been desired in such application fields. Conventionally, harmful ionic impurities such as cations such as alkali metal ions, anions such as halogen ions, and nitrate ions can be easily removed by ordinary purification methods such as washing with water, and therefore, they have not been used for electronics. It has also been adjusted to below 10ppm. However, it is completely impossible to reduce the above-mentioned organic chlorine groups by such a conventional method, and the problem in purifying epoxy compounds has traditionally been the reduction of these organic chlorine groups. The conventional method is to decompose organic chlorine groups by adding a small amount of alcoholic caustic solution as a processing agent to an epoxy compound and allowing the reaction to occur under relatively mild conditions such that the coexisting epoxy groups are hardly consumed. The conventional method has been to convert the chlorine into chlorine ions and then remove and purify them using conventional methods.
In this method, only easily hydrolyzable groups present in a small proportion of about 20% of the total chloro groups are primarily removed. The more severe the above reaction conditions are, the more chloro groups can be decomposed, but at the same time, a large amount of epoxy groups are consumed, resulting in significant deterioration of the epoxy compound itself and the loss of practicality. reach. It should be noted that the difficulty in hydrolyzing the organic chlorine group as an impurity in an epoxy compound is relative, and the degree of difficulty is considered to be almost continuous over a considerable range. Therefore, the more severe the test conditions for molded products using epoxy compounds, the more the amount of organic chlorine groups that are hydrolyzed increases. On the other hand, due to recent remarkable developments in the electronics industry, transistors, LSIs, and super LSIs
Their evolution shows no signs of stopping, and with the rapid increase in the degree of circuit integration in these semiconductor devices and components, their reliability has become increasingly required. Furthermore, a strong correlation has been observed between the reliability and the content of organic chlorine groups. Therefore, at first, only ionic chlorine was targeted as the chlorine to be removed from epoxy compounds, but then it came to include easily hydrolyzable organic chlorine groups, and even more. Recently, the range has been gradually expanded to include those that are more difficult to hydrolyze. Nowadays, it has become necessary to significantly reduce the total amount of organic chloro groups contained as impurities in epoxy compounds used in such fields. That is, the total amount of organic chlorine groups contained as impurities in the epoxy compound is required to be 600 ppm or less, preferably 300 ppm or less, but it has been extremely difficult to obtain this level in the past. [Purpose of the Invention] The present invention was developed as a result of research aimed at finding an effective method for reducing organic chlorine groups, which had previously been considered impossible due to these points. As a result, they found that it is possible to purify epoxy compounds without altering their quality, and based on this knowledge, they conducted various studies and completed the present invention. [Structure of the Invention] The present invention is a purification process characterized in that an epoxy compound is subjected to a contact reaction with metallic sodium powder in an amount of 1.0 to 8.0 times the mole of organic chlorine groups as an impurity, and the chloride ions are once converted into chloride ions, which are then removed by a conventional method. It's a method. In addition, the above reaction conditions are 0 to 60℃
It is desirable that the conditions are relatively mild. Furthermore, it is desirable that an active hydrogen-containing compound as a reaction aid coexists with metallic sodium.
Note that it is necessary that the reaction system described above be sufficiently dehydrated in advance in order for the metallic sodium to function effectively without being consumed by reaction with water. usually
Preferably, the reaction system is dehydrated to a moisture content of 0.5% or less. The method for quantifying organic chlorine groups of the present invention is determined by subtracting the amount of chlorine ion from the total amount of chlorine. The total amount of chlorine is determined by completely burning the epoxy compound in an oxygen oven to form chloride ions, which are then determined by a conventional quantitative method using silver nitrate. The amount of chlorine ions is determined by dissolving the epoxy compound in toluene, extracting it with water, and then using the extracted water with a conventional quantitative method. The epoxy compound of the present invention is obtained by condensing epichlorohydrin and an active hydrogen compound in the presence of caustic alkali. As for this type of epoxy compound, those with an average number of epoxy groups of 2 or more per molecule are usually used as thermosetting epoxy resins, and those with an average number of epoxy groups of 1 to 2 or more are used as thermosetting epoxy resins. Those having the above are used as modifiers, reactive diluents, etc. for the above-mentioned epoxy resins. In addition, active hydrogen compounds used as raw materials for epoxy compounds include phenolic OH groups, alcoholic OH groups,
It has one or more groups per molecule, such as a carboxyl group, a primary to secondary amino group, and a mercaptan group. As raw materials for the epoxy resin of the present invention, polyphenol-based materials are particularly preferred. The monofunctional epoxy compound used as the reactive diluent preferably has a low viscosity at room temperature and a boiling point of 200°C or higher.
For example, glycidyl esters of liquid fatty acids such as isostearic acid, olephiic acid, and lauric acid, and glycidyl ethers of alkylphenols are often used. These epoxy compounds, especially epoxy resins, are often important in the electronics field because of their excellent curability and well-balanced physical properties after curing. However, the above-mentioned epoxy compounds essentially contain aliphatic primary chloro groups due to side reactions, and the amount thereof ranges from 1000 ppm to several thousand ppm. This chlor group gradually decomposes and liberates chloride ions when boiled in high-pressure water, although there are some differences in the difficulty of hydrolyzing it. The chlorine ions generated in this way corrode the aluminum wiring when epoxy resin is used in direct or indirect contact with semiconductors such as LSIs and VLSIs, so This is a major cause of a significant decrease in reliability, such as the occurrence of abnormalities during timed energization tests. Therefore, when epoxy resins are used in such fields, it is strongly desired that the amount of organic chlorine, which is a source of chlorine ion generation, be reduced as much as possible. Note that for the above purpose, aromatic nuclear-substituted halogen groups are not included as organic chlorine groups. For the purpose of the present invention, the amount of organic chlorine groups contained in the epoxy compound must be reduced to 600 ppm or less, preferably 300 ppm or less, and the purification method of the present invention reduces this. It provides an effective means to achieve this goal. The metallic sodium used in the present invention is rapidly stirred in a molten state in an inert solvent having a boiling point higher than its melting point, such as toluene or xylene, to disperse it into small particles, and the diameter of the small particles is It is preferable that the diameter is 0.2 mm or less because the surface area is large and reactivity is high. When the epoxy compound has a high viscosity, it is preferably dissolved in an inert solvent such as toluene or xylene, and then reacted with the metal sodium particles. Since the reaction takes place on the surface of the solid and liquid, it is desirable that the reaction be sufficiently stirred. As for the reaction conditions, it is preferable that the amount of metallic sodium is 1.0 to 8.0 times, preferably 2.0 to 4.0 times, by mole relative to the organic chlorine group contained in the epoxy compound. If the amount is less than this, the effectiveness of removing organic chlorine groups will be significantly reduced, and if it is more than this, unreacted metal sodium may remain or epoxy groups may be consumed by side reactions, which is not preferable. It is preferable to conduct the reaction under mild conditions of 0° to 60°C. If the temperature is lower than this, the reaction will be extremely slow, and if the temperature is lower than this, the reaction will be intense and side reactions will easily occur, so both are undesirable. Usually metallic sodium is used for 5 to 50 hours.
Preferably, the reaction proceeds while gradually disappearing over 10 to 30 hours. At this time, since hydrogen is generated by a trace amount of active hydrogen groups or water present in the system, the resin can be decolorized and become lighter in color. Since there is a risk of ignition when metallic sodium comes into contact with a large amount of water, it is necessary to strictly control the water content in the reaction system. Moreover, it is preferable to carry out the reaction in a stream of dry air or inert gas. When organic chlorine groups come into contact with metallic sodium, they are decomposed and converted into chloride ions. Once in the form of chlorine ions, it can be easily removed by conventional purification methods such as washing with water or adsorption with ion exchange resins, activated carbon, silica gel, etc. In this case, sodium ions are also generated along with chlorine ions, so both must be removed by conventional methods. Note that the same effect can be obtained by using an alkali metal such as metallic lithium or metallic potassium instead of or together with metallic sodium. However, from the viewpoint of ease of handling and cost, metal sodium or a material mainly composed of sodium metal is most suitable. It may also be used in the form of an amalgam. Washing with water is particularly excellent as a method for removing ionic impurities such as chloride ions and sodium ions, and washing with water may be used in combination with the above-mentioned adsorption method. In the case of washing with water, since the system is initially alkaline, it is preferable to first wash with water containing a small amount of an acid salt such as acidic sodium phosphate to neutralize the system, and then wash with water. Metallic sodium reacts violently, but because it is a solid, the reaction only occurs on its surface, so the reaction progresses slowly. In order to improve this, a reagent that easily reacts with metallic sodium and whose reaction product is active and easily reacts with organic chlorine groups may be used as a reaction aid. As such a reaction aid, a compound having active hydrogen that easily reacts with metallic sodium is preferred. Examples include compounds having active hydrogen such as methyl acetoacetate and dimethyl malonate, mercaptans such as lauryl mercaptan, and quaternary alcohols such as quaternary butyl alcohol. These additives as reaction aids may be used after their active hydrogen groups are reacted with metallic sodium in advance in an organic solvent to react partially or completely. The amount of these active hydrogen-containing compounds to be used is desirably such that the molar ratio of active hydrogen to metallic sodium is within the range of 0.01 to 1.0.
If the amount is less than this, the effect of the addition of the active hydrogen compound will hardly be recognized, and if it is more than this, the purification effect will be significantly reduced, so neither is preferable. [Effects of the Invention] According to the method of the present invention, it is possible to significantly reduce organic chlorine groups contained as impurities in epoxy compounds without deteriorating their properties, which was thought to be difficult to achieve with conventional methods. This method makes it possible to significantly improve the purity of epoxy compounds, and is suitable as an industrial method for purifying epoxy compounds. The highly purified epoxy compound obtained by the method of the present invention is extremely useful for providing highly reliable semiconductor products, particularly in the electronics field. [Example] Examples will be described below. Example 1 200 parts of epoxidized novolak (weight, same below)
is dissolved in 400 parts of anhydrous toluene. Next, the particle size is 0.1
~ Add 0.285 parts of toluene dispersion of metallic sodium powder of ~0.5 mm as metallic sodium and stir at room temperature for 15 minutes.
Most of the metallic sodium dissolves after stirring for a period of time. This is washed twice with a 2% (wt) NaH ₂ PO ₄ aqueous solution and then twice with pure water. then dried
Add 5 parts of OH type strongly basic anion exchange resin and 2 parts of dried H type strongly acidic cation exchange resin and stir at room temperature for 3 hours. Remove the ion exchange resin,
The solvent was removed under vacuum to obtain purified epoxy resins shown in Table 1. Reference example 1 Epoxidized Novolac 200 used in Example 1
10 parts of 0.1N-alcoholic potassium hydroxide solution
1 part and 400 parts of toluene were added, and the reflux reaction was carried out for 15 minutes.
After washing the system with water, 10 parts of a 0.1N alcoholic potassium hydroxide solution was further added and the mixture was refluxed for 15 minutes. The system was washed with water and the solvent was removed under reduced pressure to obtain the purified resin shown in Table 1. Reference example 2 Epoxidized novolac 200 used in Example 1
20 parts of 1N-alcoholic caustic potash and 400 parts of toluene were added to the reactor and reacted under reflux for 30 minutes.The system was then washed with water and the solvent was removed under reduced pressure to obtain the purified resins shown in Table 1. Example 2 200 parts of epoxidized bisphenol F are dissolved in 400 parts of anhydrous xylene. Then methyl acetoacetate
Add 0.06 parts and uniformly dissolve, then add 0.37 parts of metallic sodium powder in the same form as in Example 1, and stir at room temperature for 8 hours, most of the metallic sodium will dissolve. This is an OH type strongly basic anion exchange resin.
Add 15 parts and 5 parts of H-type strongly acidic cation exchange resin, and stir at room temperature for 3 hours. The ion exchange resin was removed and the solvent was removed in vacuum to obtain purified epoxy resins shown in Table 2.

【table】

[Table] Example 3 For 200 parts of lauric acid glycidyl ester,
Add 0.300 part of metallic sodium in the same form as in Example 1, and stir at 35-40°C for 5 hours to react. This is washed with water in the same manner as in Example 1, and ionic impurities are adsorbed and removed using an ion exchange resin. The properties of the obtained glycidyl oleate are shown in Table 3.

【table】

【table】

Claims (1)

[Scope of Claims] 1. A method for purifying an epoxy compound, which comprises contacting the epoxy compound with metal sodium powder in an amount of 1.0 to 8.0 times the molar amount of organic chlorine groups as an impurity to form chlorine ions, which are then removed. 2. The purification method according to claim 1, wherein the reaction temperature is 0° to 60°C. 3 The reaction system contains metallic sodium as a reaction aid.
3. The purification method according to claim 1 or 2, further comprising adding a compound having active hydrogen in an amount of 0.01 to 1.0 times the mole.