JPS61111319A - Production of brominated novolak epoxy resin - Google Patents

Abstract

PURPOSE:To produce the titled resin excellent, especially, in curability and suitable as a flame retardant, chiefly, for electrical insulation laminates, by reacting a brominated phenol novolak resin with an epihalohydrin in the presence of a basic compound. CONSTITUTION:A brominated phenol novolak resin of formula I (wherein R is H or CH3, n is 0.1-15 and p is 1-2) is reacted with an epihalohydrin of formula II (wherein R is as defined above and X is a halogen) in the presence of a basic compound (e.g., NaOH) according to a usual manner to produce a brominated novolak epoxy resin of formula III (wherein R, n and p are as defined above). According to a conventional process, the preparation of a resin excellent in properties of a cured product, such as heat resistance and moisture resistance has been limited because the epoxy equivalent weight increases with an increasing MW. According to the present process, a resin excellent in curability and suitable, chiefly, as a flame retardant for electrical insulation laminates can be obtained because the epoxy equivalent weight does not increase so markedly.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a novel and useful method for producing a brominated novolac type epoxy resin, and more particularly, to a method for producing a novel and useful brominated novolac type epoxy resin, and more particularly, The present invention relates to a method for producing a resin which has particularly excellent curability and is suitable mainly as a flame retardant for electrically insulating laminates.

This type of brominated nogelac-type epoxy resin is used as an agent to impart flame retardancy or heat resistance to electrical insulating materials, such as in phenolic resin laminates and epoxy resin laminates. It is widely used in various fields.

[The problem that the prior art and the invention are trying to solve] By the way, in the conventional brominated epoxy resins, the hydroxyl group of phenol is located at the 4 position other than the 2 position, or the 2 position is and 40 positions are brominated, and the general formula is as follows.

...y] Such a brominated epoxy resin is generally prepared as follows. That is, (a) phenol is reacted with formalin or formaldehyde in the presence of an acidic catalyst to form phenol/nodelac at
A method of synthesizing Noblak resin, then brominating this Noblak resin with bromine in a solvent, and then reacting the obtained brominated Noblak resin with shrimp chlorohydrin in the presence of a basic catalyst, or (b) Bromophenol (a mixture of 4-bromophenol and 2-bromophenol), formalin or paraformaldehyde is reacted in the presence of an acidic catalyst, and then the bromopurple-colored nogelac type phenol resin thus obtained is reacted with formalin or paraformaldehyde. (method of reacting epichlorohydrin with epichlorohydrin in the presence of a basic catalyst).

Among these, in the case of the (&) method, since phenol is trifunctional, when the formaldehyde/phenol molar ratio (F/'P) exceeds 0.85, three-dimensionally cross-linked Therefore, there is a limit to increasing the molecular weight by increasing F/P.

In addition, when changing this F/P within 0.85 to prepare various brominated novolac type epoxy resins from low molecular weight products to high molecular weight products, and then epoxidizing each novolac resin, the molecular weight There is a remarkable tendency for the epoxy equivalent to increase with increasing (
b) In the case of the method, since bromophenol is difunctional, no dregs are observed even if the molar ratio of formaldehyde/bromophenol (F/B) is 0.95 or more. , therefore high molecular weight bromination? Although lac-type resins are easily obtained, since a mixture of 2-bromophenol and 4-bromophenol is used, when such brominated nodela resins are subjected to 4-oxygenation, it is difficult to increase the molecular weight. Accordingly, the tendency for the epoxy equivalent to increase becomes significant.

By the way, the heat resistance and moisture resistance of the cured product of this brominated noblack type epoxy resin are related to both the molecular weight and the epoxy equivalent, and in general, the higher the molecular weight, the lower the epoxy equivalent. It is known that these physical properties are improved.

However, when the molecular weight is increased according to conventional methods, the epoxy equivalent weight usually increases significantly, so brominated epoxy resins with excellent curing properties such as lucid heat resistance and moisture resistance are used. However, as a result of intensive study by the present inventors in view of the various drawbacks in the prior art as described above, (replacement)
By using a specific phenol that has bromine at the 2-position relative to the phenol's hydroxyl group, the rate of increase in epoxy equivalent is small even when the molecular weight is increased, resulting in improved curing properties, especially heat resistance and moisture resistance. The present invention was completed by discovering a brominated I-oxy resin with excellent properties.

That is, the present invention has the general formula %, which consists of reacting a brominated phenol noblack resin represented by the general formula % (1) with an epihalohydrin represented by the general formula in the presence of a basic catalyst. A method for producing a brominated nogelac-type epoxy resin represented by the formula %() is provided.

Here, typical bromophenols used as raw materials for the above-mentioned brominated phenol/noblack resin include 2-bromophenol, 2-bromo-m-cresol, 6-bromo-m-cresol, and 2-bromo-m-cresol. -3,5-*Cresol etc., but by reacting such bromophenols with formalin or nolaformaldehyde in the presence of an acidic catalyst, bromination as shown in the above general formula [■] can be achieved. Lac resin is obtained. In this case, among the bromophenols, 2-bromophenol is particularly preferred.

When carrying out the uninvented method, there is nothing to preclude the use of 4-bromophenol in combination with the bromophenols listed above in the preparation of the brominated phenol/noblack resin, but such In this case, the content of 4-bromophenol must be less than 5% by weight of the above-mentioned bromophenols.

On the other hand, typical epihalohydrins include epichlorohydrin, γ-methylepichlorohydrin, epibromohydrin, r-methylepibromohydrin, and mixtures thereof, with epichlorohydrin being particularly preferred.

To carry out the method of the present invention, the above-mentioned brominated phenol noblack resin and epihalohydrino may be reacted in the presence of a basic catalyst according to a conventional method.

In other words, a brominated phenol noblack resin is added with about 4 to 20 moles of epihalohydrin per hydroxyl group contained in the resin, and a water-soluble solvent such as methanol, ingrono-4-nol, or acetone. After dissolving the resin in a solution containing nitrogen and performing Nt exchange with an inert gas such as nitrogen gas as necessary, the hydroxyl group 1 of the resin
A basic catalyst in the form of a solid or a highly aqueous solution is added in an amount equivalent to or slightly in excess of 20
At a temperature of ~120℃, usually F! By reacting for 10 to 15 hours and then removing by-produced water and salt, the desired resin represented by the above-mentioned general formula CI[l] can be obtained.

Typical basic catalysts used here include Kti, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, or potassium hydroxide, or alkali metal salts such as sodium silicate or sodium aluminate. When preparing the target resin according to the method of the present invention,
Along with the above-mentioned brominated phenolic resins, known and commonly used resins such as bis(4-hydroxyphenyl) dimethyl-methane, bis(4-hydroxyphenyl)methane, resorcinol, hydroquinone or one other type of resin, etc. There is no hindrance to further improving the various physical properties of the objective resin of the present invention by reacting the above polyhydric phenols in combination.

Thus, the brominated Norac type epoxy resin obtained by the method of the present invention can be used in practice with other types of polyglycinoleruthyl polyhydric phenols or polyhydric alcohols, epoxidized fatty acids or As long as it does not deviate from the purpose of the present invention, the use in combination with known and commonly used polyoxy resins such as its derivatives, epoxidized diene polymers, cyclohexene epoxide derivatives, dicycloenzoene epoxide, etc. is not prohibited in any way. It's not a thing.

〔Example〕

Next, the present invention will be specifically explained using Examples, Comparative Examples, and Application Examples.

Example 1 In a reactor equipped with a thermometer, stirrer and condenser, 1
73I of 2-bromophenol was added, and 73. P and 2 g of oxalic acid were sequentially added and reacted at 90°C for 4 hours, then at 100°C for 8 hours, and then heated to 150°C for dehydration.
A brominated phenol Norac resin of 18211 was obtained.

Next, 64,711 epichlorohydrin was added to this resin, and 901 of a 48% sodium hydroxide aqueous solution was added.
The reaction was continued at 80°C for 8 to 10 hours while water was removed from the system, and then the sodium chloride was removed from the reaction mixture while the mother liquor was concentrated to give the pale yellow target resin 2259. I got it.

The engineering equivalent of this resin is 285, the melting point by the ring and ball method (the same applies hereinafter) is 105°C, and the average number of nuclei is 9 to 10.
It was.

Example 2 In a reactor similar to Example 1, 17 of 2-bromophenol was added.
311 was charged, 371 formalin 6591 and hydrochloric acid 2I were added and reacted at 100°C for 15 hours, and then the hydrochloric acid aqueous solution was neutralized and dehydrated to obtain 180# brominated phenol nogelac resin. .

After that, 6479 epichlorohydrin was added to this resin, and 2II of triethylbenzylammonium chloride was added and reacted at 40°C.
90 Jil of an aqueous sodium hydroxide solution was added at 80° C. and reacted for 6 hours, then washed with water and excess epichlorohydrin was recovered to obtain the target resin 2251.

This resin has an epoxy equivalent weight of 265, a melting point of 85°C,
and the average number of nuclei was 5 to 6. Comparative Example 1 Example except that a mixture consisting of 1151 of 2-bromophenol and 58.9 of p-bromophenol was used as the bromophenol. Similarly to 2, the epoxy equivalent is 280, the melting point is 87°C, and the average number of nuclei is 5 to 5.
Six control brominated Norac-type epoxy resins were obtained.

Comparative Example 2 659 of 37 formalin was added to 149 g of 2-bromophenol, and 2I! The reaction was continued at 80°C for 6 hours and then at 160°C for 4 hours, and then the unreacted phenol was removed to recover 5619 2-bromophenol and 103I phenol-noblack resin. Nine points.

This resin was then dissolved in n-butanol and bromine 1601 was introduced to obtain 182I brominated phenol noblack resin.

Next, 6471 epichlorohydrin was added to this brominated novolac resin, 90.9% of 48% sodium hydroxide aqueous solution was added, and the reaction was carried out at 80°C for 6 hours. Excess epichlorohydrin was recovered by distillation, and methyl isobutyl ketone was recovered. Then, after washing with water, methyl isobutyl keto/ was recovered to obtain 230# brominated noblack type phenolic resin for control.

This resin has an epoxy equivalent weight of 285, a melting point of 84°C,
Moreover, the average number of nuclear bodies was 5 to 6.

1 Comparative Example 3 Phenol 119II and 37 width formalin 7211
and oxalic acid 211 were added and reacted at 80°C for 6 hours,
After further maintaining the temperature at 160° C. for 4 hours, unreacted phenol 271 was recovered to obtain a phenol noblack resin of 103.9.

This resin was then dissolved in n-butanol and 160.
Bromine of 9 was introduced to obtain 18219 of brominated phenol noblack resin.

After that, 6471 epichlorohydrin was added thereto, and 48% sodium hydroxide aqueous solution 9011 was added thereto, and the reaction was carried out at 80°C for 6 hours. A control brominated tumelac type phenolic resin having an average number of nuclei of 9 to 10 was obtained.

Example 3 The epoxy equivalent was 284, the melting point was 105°C, and the average number of nuclei was 9 to 10. Resin was obtained.

Actual flow side 4 Same as Example 2 except that 74511 r-methylepichlorohydrin was used instead of epichlorohydrin, with a nixie equivalent of 280, a melting point of 82°C, and an average number of nuclei of 5 to 6. 230 g of the desired resin was obtained.

To 100 parts by weight of each of the brominated norac type phenolic resins obtained in the above Examples and Comparative Examples, 55 parts of tetrahydroheptalic anhydride was added as a curing agent, and benzyldimethyl was added as a curing accelerator. Various resin compositions to which 0.5 parts by weight of amine were added were added to 15 parts by weight of each resin composition.
Each cured product was obtained by heat curing at 0° C. for 2 hours and then at 195° C. for 4 hours.

JISK-6911 for each cured product
Performance was evaluated according to the following.

The results are summarized in Table 1.

〔Effect of the invention〕

In the resin obtained by the method of the present invention, the average number of nuclei (corresponding to the molecular weight) increases, and even if the melting point increases, the epoxy equivalent does not become so high. In the case of the resin obtained in Example 3, it is known that the epoxy equivalent weight increases significantly as the average number of nuclei increases and the melting point increases.

In addition, as seen for example between Example 1 and Comparative Example 3, in the case of the same molecular weight, a resin using 2-bromophenol and a weight mixture of 2-bromophenol and 4-bromophenol It is also known that the epoxy equivalent weight is lower than for resins using mixtures with a 2:1 ratio.

Furthermore, from the results in Table 1, it can be seen that grades with relatively low molecular weights, such as those in Example 2 and Comparative Examples 1 or 2, have relatively small differences in performance (cured physical properties) but have higher molecular weights. For example, in the case of Example 1t7' (Comparative Example 3), the difference in cured physical properties is significant.

The advantage of the method of the present invention that the epoxy equivalent does not become so high even when the molecular weight is increased in this way is that it leads to improvements in the properties of the cured product, so the effects of the present invention are immeasurable. I can say it.

Claims (1)

[Claims] General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼... [I] However, R in the formula represents a hydrogen atom or a methyl group, and n is 0 or a number from 1 to 15. It is assumed that p is an integer and p is 1 or 2. Brominated phenol/novolak resin shown by the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ [II] However, R in the formula represents a hydrogen atom or a methyl group, and X represents a halogen atom. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼...[III] However, R in the formula is a hydrogen atom or shall represent a methyl group, n shall be 0 or an integer from 1 to 15, and p shall be 1 or 2. A method for producing a brominated novolak epoxy resin shown in