JPS6226646B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an epoxy compound (glycidyl ether) with a reduced content of hydrolyzable chlorine.

Various methods are known for producing epoxy compounds by synthesizing halohydrin ether from monohydric or polyhydric alcohol and epihalohydrin, and dehydrohalogenating this with alkali metal hydroxide.
It is difficult to completely perform dehydrohalogenation in the step, and as a result, halohydrin ether remains in the product, which causes a decline in the performance, particularly the electrical performance, of the cured product.

Recently, performance requirements for cured epoxy resin products have been increasing, and there is an urgent need to develop a method for producing epoxy compounds with less residual halohydrin ether.

The reaction formula for producing an epoxy compound is as follows, taking chlorine and sodium hydroxide as an example.

Typical acid catalysts include boron trifluoride compounds, particularly ether complexes of boron trifluoride; in this case, epichlorohydrin is usually used in an amount of 0.9 to 1.5 mol per equivalent of alcoholic hydroxyl group; All of it is consumed. The chlorohydrin ether thus obtained needs to be ring-closing epoxidized with an alkali metal hydroxide as efficiently as possible.

The ring-closing step is usually carried out at 60 to 90°C using an aqueous sodium hydroxide solution with a concentration of 10 to 50% in a ratio of 1.1 to 2 sodium hydroxide molecules per chlorohydrin ether group. At this time, no reaction solvent is used, or toluene,
When ring-closing chlorohydrin ether by dissolving it in a hydrophobic solvent such as xylene, it is difficult to reduce the content of hydrolyzable chlorine, which indicates the presence of residual chlorohydrin ether, to 0.1% or less, especially 0.05% or less. Therefore, if strict conditions are used here, side reactions may occur. Another method is to use a water-soluble solvent such as acetone or alcohol instead of a hydrophobic solvent in order to increase contact between chlorohydrin ether and sodium hydroxide; use a large amount of
Hydrolyzable chlorine is 0.1% if it is not used for a long time.
This makes it difficult to treat wastewater containing large amounts of water-soluble solvents (separation of water and water-soluble solvents requires energy-intensive methods such as distillation), and the epoxy compounds end up being This makes the manufacturing process cost high.

In addition, there are some compounds, such as glycidyl ethers of long-chain aliphatic alcohols, whose hydrolyzable chlorine content is extremely difficult to reduce even when a water-soluble solvent is used.

As a result of intensive research on such a ring-closing process, the present inventors have found that if a halohydrin ether is dehydrohalogenated with an aqueous alkali metal hydroxide solution in the presence of a quaternary ammonium salt or a quaternary ammonium base, They have discovered that the hydrolyzable chlorine content can be easily reduced to 0.05% or less under mild conditions, and have completed the present invention.

Monohydric or polyhydric alcohols that are the starting materials for synthesizing halohydrin ethers include, for example, methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol,
2-ethylhexyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, allyl alcohol, benzyl alcohol, polyalkylene glycol monoalkyl ether such as polyethylene glycol-monomethyl ether, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, 1,4- Ethylene oxide or propylene oxide adducts of butanediol, 1,6-hexanediol, neopentyl glycol, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, hydrogenated bisphenol A, bisphenol A and bisphenol F, etc. Examples of epihalohydrin include epichlorohydrin and epibromohydrin.

In addition, the quaternary ammonium salt and quaternary ammonium base used in the present invention include:
Typical examples include tetraalkylammonium halides or hydroxides, including:
Examples include benzyltriethylammonium chloride, benzyltributylammonium chloride, tetrabutylammonium bromide, trioctylmethylammonium chloride, tetramethylammonium chloride, and tetramethylammonium hydroxide. Others, N
-Alkylpyridinium halides or hydroxides or N-alkylpicolinium halides or hydroxides can also be used, examples of which include N-laurylpyridinium chloride, N-benzylpicolinium chloride, and the like.

In the present invention, a halohydrin ether synthesized from alcohol and epihalohydrin is prepared by removing unreacted epihalohydrin, if any, and then using a hydrophobic solvent such as xylene, toluene, benzene, etc. as necessary. Dilute with a ketone solvent such as methyl ethyl ketone or methyl isobutyl ketone, then add 0.01 to 3% by weight of a quaternary ammonium salt or base based on halohydrin ether, and then dilute with sodium hydroxide at a concentration of 10 to 50%. Aqueous solution per halohydrin group
Use in a proportion such that 1.1 to 1.5 NaOH molecules are used and stir at 60 to 90°C for 1 to 5 hours. Then, the aqueous layer is separated and removed, optionally diluted with a hydrophobic solvent, neutralized and washed with water and a weak acid such as _NaH2PO4 , and optionally distilled under reduced pressure to remove the hydrophobic solvent _. A purified epoxy compound is thereby obtained.

The process of the invention provides an epoxy compound with simple and inexpensive treatment and post-treatment methods and with a significantly reduced hydrolyzable chlorine content.

Next, the present invention will be specifically explained using examples.
Hereinafter, all % means "% by weight".

[Example 1] Polypropylene glycol 400 with hydroxyl equivalent weight 200
g (1 mol) to which 0.85 g of boron trifluoride ether complex was added, and 241 g of epichlorohydrin at 60±2℃ was added.
(2.6 mol) was added dropwise over 3 hours while being careful not to generate heat, and the temperature was maintained at the same temperature for 1 hour after dropping. Since the epoxy equivalent is infinite, epichlorohydrin completely disappeared, and the measured chlorohydrin equivalent was 356.

Next, tetrabutylammonium bromide 4.5
After adding 288 g of 30% NaOH aqueous solution (1.2 times equivalent to chlorohydrin group) at 60°C over 1 hour, the temperature was maintained for 2 hours after the dropwise addition.
After that, discard the aqueous layer, add 300g of toluene, and add water.
After neutralizing and washing with 200 g and NaH ₂ PO ₄ , toluene was removed under reduced pressure and filtered to obtain an epoxy compound with the following properties.

Epoxy equivalent: 320 Hydrolyzable chlorine: 0.01% [Comparative example 1] Epichlorohydrin adduct (chlorohydrin equivalent: 356) prepared under exactly the same charge weight and reaction conditions as in Example 1 was added with 286 g of a 30% NaOH aqueous solution (1.2 times the chlorohydrin group). equivalent amount) was added dropwise over 1 hour at 60°C, and after the dropwise addition, the same temperature was maintained for 2 hours, and the hydrolyzable chlorine was measured to be 0.95%. Therefore, 48 g of a 30% NaOH aqueous solution (0.2 times equivalent to the chlorohydrin group) was added and the mixture was maintained at 60° C. for 4 hours. Thereafter, the aqueous layer was discarded, 300 g of toluene was added, and the same treatment as in Example 1 was carried out to obtain an epoxy compound having the following properties.

Epoxy equivalent: 322 Hydrolyzable chlorine: 0.12% [Example 2] Add 0.69 g of boron trifluoride ether complex to 316 g (2 mol) of decyl alcohol, and add 213 g (2.3 mol) of epichlorohydrin at 70 ± 2°C, taking care not to generate heat. The temperature was maintained at the same temperature for 1 hour after the dropwise addition. Since the epoxy equivalent was infinite, epichlorohydrin had completely disappeared, and when the chlorohydrin equivalent was measured, it was 306.

Next, 5.3 g of benzyltriethylammonium chloride was added, and then 187 g of a 48% NaOH aqueous solution (1.3 times equivalent to the chlorohydrin group) was added dropwise at 60°C over 1 hour, and after the dropwise addition, the same temperature was maintained for 2 hours. After that, 300 g of water was added to dissolve and discard the precipitated NaCl, and after neutralization and washing with 300 g of water and NaH ₂ PO ₄ , 200 g of toluene was added for azeotropic dehydration, the toluene was removed under reduced pressure, and the mixture was filtered. An epoxy compound having the following property values was obtained.

Epoxy equivalent: 266 Hydrolyzable chlorine: 0.03% [Comparative example 2] To the epichlorohydrin adduct (chlorohydrin equivalent: 306) prepared under exactly the same charge weight and reaction conditions as in Example 2, 188 g of a 48% NaOH aqueous solution (1.3 Double equivalent amount) was added dropwise at 80° C. over 1 hour, and after the dropwise addition, the same temperature was maintained for 2 hours, and the hydrolyzable chlorine was measured and found to be 2.1%. So, when I kept it at 80℃ for another 2 hours and measured it, it still remained.
It was 1.6%.

[Comparative Example 3] 53 g of isopropyl alcohol was added to the epichlorohydrin adduct (chlorohydrin equivalent: 306) prepared under exactly the same charge weight and reaction conditions as in Example 2, and after uniformly mixing, 48% NaOH aqueous solution 187
g (1.3 times equivalent to chlorohydrin group) to 80
Dropped at ℃ for 1 hour, kept at the same temperature for 2 hours, and measured hydrolyzable chlorine: 1.2%
It was hot. Therefore, when it was further held at 80°C for 2 hours and measured, it was still 0.85%.

Claims (1)

[Claims] 1 A halohydrin ether prepared from a monohydric or polyhydric alcohol and an epihalohydrin is hydroxylated in the presence of a quaternary ammonium salt or a quaternary ammonium base after removing unreacted epihalohydrin, if any. A method for producing an epoxy compound, which comprises dehydrohalogenating with an alkali metal aqueous solution and performing ring-closing epoxidation.