JPS61145172A - Production of epoxy resin - Google Patents

Abstract

PURPOSE:The reaction product between 2,6-xylenol and formaldehyde in the presence of a catalyst is allowed to react with a phenol and the resultant resin is epoxydized to obtain the titled resin free from gels with a combination of high thermal resistance and high water resistance. CONSTITUTION:In the presence of a basic catalyst, 2,6-xylenol is allowed to react with formaldehyde. The resultant 2,6-dimethyl-4-methylolphenol is allowed to react with a phenol or alkylbenzene, preferably mesitylene, at a ratio of 1mol of the phenold to 2-3mol of 2,6-dimethyl-4-methylolphenol, at 80-130 deg.C in the presence of an acidic catalyst to give a phenol-novolak resin of the formula (R is H, halogen, phenyl; n is 1, 2; m, p is 0, 1-3) and the novolak resin is epoxidized with epihalohydrin in the presence of a basic catalyst to give the objective resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a new and useful method for producing an epoxy resin. , 2. A polyepoxy compound consisting of 6-xylenol, formaldehyde, phenols or alkylbenzenes, and shrimp halohydrin (epoxidizing agent), which provides a cured product with excellent heat resistance, electrical properties, chemical resistance, etc. Regarding the manufacturing method.

The epoxy resin obtained by the method of the present invention is
It can be widely used as a sealant for electrical and electronic parts, a matrix for carbon fiber reinforced plastics (CFRP), paints, and adhesives.

[Prior Art and Problems to be Solved by the Invention] Various compounds such as glycidyl ether type or glycidyl ester type are known as polyfunctional epoxy compounds for use in epoxy resins. Regarding polyfunctional epoxy compounds, there is no one that satisfies all of the above-mentioned various uses in terms of properties such as curing properties and curing speed, and even though there are various types of them. In the end, the actual situation is that the types and physical properties are not necessarily sufficient.

Incidentally, in the case of a bifunctional epoxy compound obtained by reacting bisphenol A and epichlorohydrin in the presence of an aqueous sodium hydroxide solution, the heat distortion temperature is low;
However, if stored at high temperatures for a long time, the bending strength will also decrease.
Moreover, the method described in U.S. Pat. Nos. 2,857,362 and 3,013,087, which has the general formula % [ Although the polyepoxy compounds obtained in small amounts improve the drawbacks of the above-mentioned difunctional epoxy compounds, such polyepoxy compounds have the following drawbacks.

That is, it contains 1 to 6% by weight of gelled material (gel body) and has a hydrolyzable chlorine content of 1 to 2 times J! ’%.

Here, when the amount of gel body becomes large, the mechanical strength and heat resistance of the cured product obtained are impaired; on the other hand, when the hydrolyzable chlorine content is too low, the electrical properties of the cured product are impaired, and the lamination The disadvantage is that it corrodes the metals that are sealed.

[Means for solving problems]

However, the inventors of the present invention have conducted intensive studies in view of the various shortcomings in the prior art as mentioned above, and have found 2.
Using 6-xylenol as a raw material, it is reacted with formaldehyde in the presence of a basic catalyst to produce 2,6-dimethyl-
4-methylolphenol is synthesized, and then phenol atfc is reacted with alkylbenzenes to obtain a trinuclear or tetranuclear phenol novolak resin, which is then epoxidized with epihalohydrin to form a gel body. The present invention was completed by discovering that a novolak-type epoxy resin containing almost no hydrolyzable chlorine and having a hydrolyzable chlorine content of 0.1% by weight or less and having both high heat resistance and water resistance can be obtained. I ended up letting it happen.

That is, unexploded HA undergoes 2,6-
By reacting xylenol and formaldehyde, 2,6
-Dimethyl-4-methylolphenol is obtained, and then this is reacted with a hexaphenol or alkylbenzene in the presence of an acidic catalyst to obtain a phenol novolac resin represented by the general formula, which is then reacted with a basic catalyst. The present invention provides a method of producing an epoxy resin having the general formula % (%) by epoxidizing it with epichlorohydrin in the presence of %.

The above general formula (
The epoxy resin represented by III), that is, the so-called novolac type epoxy resin, is produced by combining, for example, a phenol compound (phenol novolak resin) represented by the above-mentioned general formula CI) and an epihalohydrin such as epichlorohydrin in the presence of an alkaline compound. 5E is produced by reaction.

Here, the phenol compound represented by the above general formula (I) is a resolized product of 2,6-xylenol, that is, 2,6-dimethyl-4-methylolphenol and an aromatic compound such as phenols or alkylbenzenes. It is prepared by condensing phenols in the presence of an acidic catalyst, but typical phenols include 0-cresol, p-cresol,
．． 3-xylenol, 2,5-xylenol, 2,3.
5-) Limethylphenol, 2-ethylphenol, 4
-Ethylphenol, 2-butylphenol, 4-butylphenol or reso, II/Vyfl; Jnie 1)
,A7. ．． 1, -86 to 7C/-A-1B-, V/-y
, □゛3.5-xylenol, 3-ethylphenol, 2-phenylphenol, 4-phenylphenol t fcJri 2- .

Examples include muphenol. Among these, particularly preferred are 0-cresol or 3,5-xylenol, while representative alkylbenzenes include p-xylene, durene, mesitylene, etc., and particularly preferred are mesitylene. Ru.

Further, typical epihalohydrins mentioned above include epichlorohydrin, epibromohydrin, and mixtures thereof, and epichlorohydrin is particularly preferred.

The novolac type epoxy resin obtained by carrying out the method of the present invention can be easily obtained by reacting the above-mentioned phenol compound and epihalohydrin in the presence of an alkaline compound. Therefore, the reaction at this stage is carried out in the same manner as in the production of conventional epoxy resins.

In other words, a phenol compound (phenol novolak resin) is prepared in advance with epihalohydrin, an epoxidizing agent, in an amount of about 2 to 10 moles per hydroxyl group in the phenol compound, or acetaton,
In the form of a solution to which a water-soluble solvent such as l-propatol or methanol is added, if necessary, after nitrogen substitution, an equivalent amount or a slight excess of one hydroxyl group in the phenol compound is added. The reaction is carried out in the temperature range of 20 to 120°C in the presence of a large amount of an alkaline compound as a basic catalyst in the form of a solid or highly concentrated aqueous solution, and by-product water and salts are removed from the system. , it is possible to obtain a novolak type epoxy resin, which is the target resin, and has a structure represented by the above-mentioned general formula (m).

Also, phenolic compounds (phenol nobosic resin)
2,6-dimethyl-4- used in the preparation of
Methylolphenol can be obtained by a conventional method, and the basic catalyst (alkaline compound) used in this case is a hydroxide in the alkaline range such as lithium hydroxide, sodium hydroxide or potassium hydroxide, or Alkaline compounds such as alkali metals such as sodium silicate or sodium aluminate, which are used in the preparation of the target resin (novolac type epoxy resin) by epoxidation of the phenolic compound (phenol novolak resin) mentioned above. can be applied as is.

The thus obtained 2,6-dimethyl-4-methylolphenol and the above-mentioned 1! To prepare a novolak type epoxy resin, which is a phenol compound, by reacting phenols or alkylbenzenes in the presence of an acidic catalyst, 2 to 3 moles of 2.6-dimethyl are added per mole of phenols or alkylbenzenes. -4-
The reaction can be carried out using methylolphenol at a temperature range of 80 to 130°C. Typical acidic catalysts used in this case include inorganic acids such as sulfuric acid or sulfuric acid, or organic acids such as oxalic acid. There is.

〔Effect of the invention〕

Thus, the novolac type epoxy resin obtained by the method of the present invention (1) contains almost no gelled product (gel body), and (2) has a hydrolyzable chlorine content of 0.1.
The cured product of this novolac type epoxy resin has a remarkable effect that is less than % by weight (3) has a high heat distortion temperature, that is, has excellent heat resistance; (4) It has a slow effect such as low water absorption, therefore excellent electrical properties, and (5) good chemical resistance.

Next, the present invention will be explained in detail with reference to Examples, Application Examples, and Comparative Application Examples. In the following, all parts and percentages are based on weight unless otherwise specified.

Example 1 1229 of 2.6-xylenol was dissolved in 110 g of Kizilol and 1229 of 2.6-xylenol was dissolved in 1 of aqueous 60% formaldehyde.
059'Ik was added and the mixture was heated to 40°C. Next, 36% sodium hydroxide aqueous solution 1009 was added under stirring so that the temperature in the system gradually increased to 60°C, and the mixture was heated over a period of 5 to 8 hours to increase the formaldehyde concentration.
That is, the reaction was continued at 60° C. until the amount of formaldehyde remaining was 1.2%.

Thereafter, approximately 90 g of 50% sulfuric acid was mixed in to adjust the pH to 4.5-4.8, and the aqueous layer was allowed to stand to separate, then washed twice with water. ，
A quidylol solution of 6-dimethyl-4-methylolphenol was obtained.

Next, 1089 of 〇-cresol was added to a quidylol solution containing 3049 of 2,6-dimethyl-4-methylolphenol, 11 of oxalic acid was added, and the mixture was kept under reflux for 3 hours. The reaction was continued.

Approximately 36 g of the aqueous phase was then separated from the reaction mixture, which was heated to 190° C. under reflux cooling of the Quizilol,
Distillation was continued until no more water was produced, then first under normal pressure and then under slow reduced pressure (30 mHg).
), distillation was continued until the temperature (internal temperature) of the reaction mixture reached 210°C. Both distillation operations took a total of 2 hours.

Subsequently, it was cooled to 190°C to obtain 376 g of novolac resin, but the free cresol content in this resin was 0.0
Although it was less than 5%, no free 2,6-xylenol was observed.

The novolak resin obtained here has the following structure: 2-methyl-4,6-bis(3,5-dimethyl-4
It was a trinuclear compound called phenol (=hydroxybenzyl).

Next, 9259 epichlorohydrin was added to this novolac resin 1259, and 105 g of a 48% sodium hydroxide aqueous solution was added dropwise over 2 hours while stirring while boiling. During that time, water was removed from the system to continue the reaction. .

Thereafter, the sodium chloride was removed and the mother liquor was concentrated to obtain a pale yellow target resin.

The novolac type epoxy resin thus obtained had an epoxy equivalent of 191 and a hydrolyzable chlorine content of α1%.

Note that no gelled product was observed on liquid chromatography.

Hereinafter, this resin will be abbreviated as resin (11).

Example 2 2,6-dimethyl-4 obtained in the same manner as Example 1
- 1229 g of 3,5-xylenol was added to a solution of kyzyrol containing 456 g of methylolphenol;
Further, 159 oxalic acid was added and boiled under reflux for 6 hours to continue the reaction.

Subsequently, the reaction was continued by azeotropic dehydration with quijirole at 1?01 C"! until about 549 aqueous layers were separated.

Next, firstly, Kijiroru was distilled and recovered under normal pressure, and then 3
2.) Continue the reaction under reduced pressure of 0fILHg until the reaction temperature reaches 230°C.
After cooling at 1° C., 524 g of novolak resin was obtained.

The novolak resin obtained here is 3,5-dimethyl-2
It was a sclerotium compound called 4.6-tris(3,5-dimethyl-4-hydroxybenzyl)phenol.

Subsequently, 9259 epichlorohydrin was added to 161 g of this novolac resin, and the mixture was boiled and stirred to reduce the amount to 48%.
105 g of an aqueous sodium hydroxide solution was added dropwise over 2 hours. During that time, water was removed from the system.

Thereafter, sodium chloride was separated from the reaction mixture,
On the other hand, the mother liquor was concentrated to a pale yellow color with an epoxy equivalent of 22
A target resin of 0 was obtained. Hereinafter, it will be abbreviated as resin (2), and the hydrolyzable chlorine content of this resin was 0.1%.

In addition, the presence of a gelatinized product was not observed at all on liquid chromatography.

Example 3 2,6-dimethyl-4 obtained in the same manner as in Example 1
- 120 g of mesitylene was added to a quidylol solution containing 4569 of methylolphenol, and an additional 98 g of mesitylene was added.
1009% sulfuric acid was added, reacted at 80°C for 4 hours, cooled, neutralized with an aqueous sodium hydroxide solution, and the aqueous layer was separated to obtain 1.3.3-)dimethyl-2, 3929. 4°6-tris(3,5-dimethyl-4-hydroxybenzyl)benzene was obtained.

Next, 6009 epichlorohydrin was added to 174 g of this novolak resin, and while stirring the mixture, 48% sodium hydroxide aqueous solution 1059 was added dropwise over 2 hours, and water was removed from the system during the reaction.

After that, sodium chloride was separated from the reaction mixture,
When MIBK was recovered after dissolving it in methyl in butyl ketone (MIBK) and washing with water, the epoxy equivalent was 255.
A target epoxy resin was obtained in which the content of hydrolyzable chlorine was Q.08%. Hereinafter, it will be abbreviated as resin (3), but when this product was subjected to liquid chromatography, no gelled product was observed.

Application Examples 1 to 3 and Comparative Application Example 1.2 1 of each epoxy resin obtained in each of the above Examples
Anhydrous Methyl Nasic R (MA
N) and N,N-dimethylbenzylamine (BD) as a curing accelerator were mixed separately at 70°C, and then each mixture was defoamed under a reduced pressure of 10 mHg for 10 minutes, and then poured into a casting plate. Injected into manufacturing mold and heated to 80℃
It was precured for 3 hours at 150°C, then completely cured at 200°C for 3 hours.

For comparison, "Epicron N-680J [0-cresol novolac type epoxy resin manufactured by Inu Nippon Ink Chemical Industry ■; epoxy equivalent = 220]" and "Epicron N-710J phenol novolac type epoxy resin manufactured by the same company. A casting plate was obtained in the same manner as in each application example of the present invention except that a resin (epoxy equivalent = 210) was used.

When the physical properties of each cast plate were evaluated, the results shown in Table 1 were obtained.

Claims (1)

[Claims] 2,6-xylenol and formaldehyde are reacted in the presence of a basic catalyst, and then the 2,6-xylenol thus obtained is
, 6-dimethyl-4-methylolphenol is reacted with phenols or alkylbenzenes in the presence of an acidic catalyst to produce the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [ I ] [However, R in the formula shall each represent a hydrogen atom, a halogen atom, a phenyl group, or an alkyl group of C_1 to C_4, n is an integer of 1 or 2, and m and p are each an integer of 0 or 1 to 3. . ] A method for producing an epoxy resin, which comprises obtaining a phenol novolak resin represented by the following formula, and then epoxidizing this phenol novolak resin with epihalohydrin in the presence of a basic catalyst.