JPH0375563B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing an epoxy resin that essentially does not contain halogen groups. (Prior Art) Conventionally, in the electronics field, epoxy resin compositions have been widely applied for resin sealing, thick film materials, coatings, encapsulation, adhesives, resists, and the like. Moreover, as electronic circuits become more precise and finer due to the development of LSIs in recent years, the performance of resin-based materials used in combination with these circuits has also been affected, especially due to long-term heat resistance, moisture resistance deterioration, and the generation of harmful gases. It has become more stringent than ever to suppress the corrosion of metals. On the other hand, among various epoxy resins, polyphenol polyglycidyl ether type resins have the best balance in both performance and workability and are widely used in the electronics field. However, in the polyglycidyl ether type epoxy resin of polyphenol, as long as it is based on the conventional reaction between polyphenol and epihalolidone, there is inevitably a small amount (about several hundred ppm) of by-products. The biggest drawback has been that it contains hydrolyzable or non-hydrolyzable halogen groups, which is the main cause of performance deterioration under severe packaging conditions. Once generated, the halogen group forms a part of the resin itself, so it is essentially impossible to remove it using normal purification methods such as extraction, washing with water, washing with alkaline water, and distillation. It cannot be avoided as long as it depends on the situation. (Problems to be Solved by the Invention) As a result of various studies on these points, the present inventors found that no halogen group is generated as a side reaction,
Therefore, a new synthetic route for a polyglycidyl ether type epoxy resin of polyphenol which essentially does not contain halogen groups was discovered, and the present invention was accomplished. That is, in the present invention, bisphenols are reacted with allyl halide in the presence of caustic alkali until as many phenolic OH groups as possible are etherified. By introducing an allyl group and then epoxidizing the obtained polyallylated bisphenols using an organic peracid, an epoxy resin essentially free of halogen groups is to be obtained. (Means for Solving the Problems) In the present invention, when performing epoxidation with an organic peracid, it is undesirable to contain groups that are easily oxidized, so bisphenols such as bisphenol A, bisphenol S, bisphenol ketone, bisphenol ester, bisphenol ether and the like are preferred. Furthermore, since allylated bisphenols have a polymerizable allyl group, they have the advantage of being available in various degrees of polymerization. In order to obtain a semi-solid to solid resin, a resin mainly composed of oligomers or polymers with a degree of polymerization of 1.5 to 100 is preferable. The degree of polymerization of polyallylated bisphenol can be obtained by adjusting the allylation conditions and the allylic polymerization reaction. One of the features of the present invention is that epoxy resins having various molecular weights and different molecular weight distributions can be easily obtained even if the same intermediate is used as a base. As described above, the epoxy resin of the present invention has nuclear substitution type epoxy groups in addition to ether type, compared to the so-called "epibis type" epoxy resin obtained by reacting bisphenols as raw materials with epichlorohydrin. The main structural differences are that it is more polyfunctional, and that it essentially does not contain organic halogen groups as impurities, but instead contains ether-type and nuclear-substituted allyl groups. These allyl groups are polymerizable and do not exhibit any negative effects unlike the hydrolyzable or non-hydrolyzable organic halogen groups that are naturally included in conventional products. . There was a time when it was thought that there would be no practical problem if the hydrolyzable halogen groups were removed and purified to a certain level by washing with alkaline water, but recently the demands on the performance of resins in the electronics field have become increasingly strict. As time progressed, this became insufficient, and it has now become necessary to reduce even non-hydrolyzable halogen groups. Furthermore, it has been impossible to significantly reduce even the so-called non-hydrolyzable halogen groups by simply washing with alkaline water without causing deterioration of the resin. It is desirable that the epoxy resin for electronics has a halogen content of 30 ppm or less (preferably 10 ppm or less), and since the epoxy resin of the present invention essentially does not contain halogen, up to this level, unreacted allyl halide can be vacuum distilled. This can be easily achieved through ordinary purification steps such as distillation and washing with water. The industrial benefits of the epoxy resin of the present invention are immeasurable when compared to conventional methods, which could only yield products containing several hundred ppm or more of halogen, no matter how much they were purified. It's so big that it doesn't exist. Of course, there is no problem with other ionic impurities. The bisphenols used in the present invention have the general formula It is necessary that X is a group that is not easily oxidized by organic peracids. For this purpose, −CH ₂ −, −S−, −SO−, −NH
−, −CH ₂ −O−CH ₂ −, −O−CO−NH ₂ −, −
Groups such as CO-- _NH2- are undesirable. For the purposes of this invention, X is

[Formula] -SO ₂ -, -O-, -CO-, -CO-O-, etc. are preferred. If X is a group that is easily oxidized, it is undesirable because the organic peracid will be consumed excessively during epoxidation or the molecule will be cleaved. In addition, for the above 4,4' dihydroxy compound, some 2,2', 2,4', 3,3', 2,3', 3,
Isomers such as 4′ may also be used in combination. The polyallylated bisphenols used in the present invention are usually produced by reacting the above-mentioned bisphenols with allyl halide in the presence of caustic alkali to convert the phenolic OH into allyl ether, and also to undergo Claisen rearrangement. A substituted allyl group is also introduced. Theoretically, up to 6.0 allyl groups can be introduced per molecule, and for the purpose of the present invention, 2.5 allyl groups can be introduced per molecule.
In order to obtain a polyfunctional product, it is necessary to introduce at least 4.0 (preferably 4.0 or more). Furthermore, it is necessary that the polyallylated bisphenols used in the present invention contain as few free phenolic OH groups as possible. If a large amount of free phenolic OH groups remain, it is extremely disadvantageous because the functionality decreases and an abnormally large amount of peracid is consumed during epoxidation with an organic peracid. Note that free phenolic OH groups remaining in the polyallylated bisphenol may be eliminated by reacting with a lower alkyl halide, lower fatty acid, or the like. In the present invention, residual phenolic OH groups are
The number is preferably 0.2/nucleus or less. In the polyallylated bisphenols of the present invention, polymerization by allyl groups hardly occurs under normal production conditions. However, when a semi-solid to solid epoxy resin is intended, it is desirable that the number average degree of polymerization is 1.5 to 100 (preferably 3.0 to 50). If the molecular weight increases more than this, it becomes difficult to control the reaction, which is not preferable. Polymerization of the polyallylated bisphenols of the present invention can usually be carried out by polymerization of allyl groups. That is, the mixture may be stirred in the air at a high temperature (for example, 200° C. or higher) or polymerized in a solution using a radical polymerization initiator. However, since polyallylated bisphenols are polyfunctional, unless the polymerization reaction is appropriately suppressed or the reaction is stopped at a low polymerization rate and the polymer is separated, there is a risk of producing a large amount of gelled product. Therefore, it is undesirable. As long as the polyallylated bisphenols used in the present invention satisfy the above requirements, they can be used in almost the same way regardless of the manufacturing method. In the present invention, polyallylated bisphenols (including oligomers and polymers) are epoxidized with an organic peracid. Peracetic acid is the most suitable organic peracid, but
perbenzoic acid monoperphthalic acid (including m and p isomers), trifluoroperacetic acid, perpropionic acid,
Perbutyric acid, monopersuccinic acid, etc. may also be used. Alternatively, it may be used in the form of a mixed solution of 20 to 35% hydrogen peroxide and a desirable lower fatty acid such as formic acid or acetic acid. If the reaction temperature is high, there is a risk of explosion, so 50
It is preferable to carry out the reaction at a temperature below .degree. C. (preferably at room temperature or below). (Example) Example 1 125 parts of bisphenol S and 80 parts of caustic soda were dissolved in 1000 parts of ethyl cellosolve, and 56.5 parts of allyl chloride was added dropwise at 80°C for 1 hour under reflux and stirring, and then some of the solvent was distilled off. While heating, raise the temperature to 220℃. Next, the distilled solvent is returned to the system, and 76.5 parts of allyl chloride is again added dropwise at 80°C over 1 hour. Next, add 0.2 parts of benzoyl peroxide,
After polymerizing at 80°C for 1 hour, the salt was removed by washing with water, and the solvent was removed under reduced pressure (yield: 240 parts). The obtained polyallylated bisphenol is solid at room temperature, number average degree of polymerization: 4.7, number of allyl groups/molecule: 10.2, free phenolic OH group/
Nucleus: 0.2. 110 parts of polyallylated bisphenol is dissolved in 500 parts of methyl acetate, and 110 parts of peracetic acid is added at 0°C and reacted until almost consumed. Next, it is purified by water washing and vacuum distillation (yield:
(103 parts) The obtained epoxy resin was solid at room temperature, had a softening point of 80°C, had an epoxy equivalent of 180, and number of epoxy groups/molecule: 8.8. In addition, the total halogen content (oxygen cylinder method) is
It was 25ppm. (Effects of the Invention) The epoxy resin of the present invention has the following characteristics. Those based on polymers are solid, and as the molecular weight increases, the number of epoxy groups and allyl groups (per molecule), that is, the functionality tends to increase. (This is different from Epibis type and epoxidized novolac type.) Even if the molecular weight becomes high, the softening point does not increase too much, and solubility and compatibility with other polymers do not deteriorate. Contains essentially no organic halogen groups. Therefore, the epoxy resin of the present invention is essentially different from conventional epoxy resins, and has extremely high industrial value because its characteristics can be utilized particularly in the field of application to the electronics industry.

Claims (1)

[Scope of Claims] 1 Polyallylated bisphenol obtained by reacting bisphenols represented by the formula [] with allyl halide in the presence of caustic alkali is further polymerized with an allyl group by heating or using a radical polymerization initiator. In the method of epoxidizing oligomers or polymers with a number average degree of polymerization of 1.5 to 100 obtained by epoxidizing with an organic acid, polyallylated bisphenols have an average of 2.5 or more allyl groups per bisphenol molecule and are free. A method for producing a semi-solid to solid epoxy resin, characterized in that a resin containing as little phenolic OH group as possible is used. X: [Formula] -SO ₂ -, -O-, -CO- COO-.