JPH07286030A - Continuous purification of epoxy resin - Google Patents

Abstract

PURPOSE:To provide a purification process whereby the mixing, separation and removal can be performed continuously and efficiently in the production of an epoxy resin by using a centrifuge having a separation tank having a shearing part in its inside. CONSTITUTION:This purification process is the one comprising continuously feeding a mixed solution containing a crude epoxy resin obtained by reacting a phenol with an epihalohydrin in the presence of an alkali catalyst and an organic solvent and water into a centrifuge having a cylindrical hollow separation tank having a rotary haft in the axial direction and having a disc or doughnut as a shearing part coaxial with the rotary shaft inside the tank, and continuously discharging the purified epoxy resin and the treated water from the centrifuge. It is desirable that the above mixed solution is continuously fed into the centrifuge from the inside shell, the purified epoxy resin is discharged from the centrifuge through the outside shell, and the mixed solution containing the unpurified crude epoxy resin is brought into countercurrent contact with the water in the tank.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of reacting phenols with epihalohydrin in the presence of an alkali metal hydroxide in the production of an epoxy resin, and then the residual alkali metal hydroxide and a by-produced alkali salt by the reaction. The present invention relates to a continuous purification method for an epoxy resin, which comprises efficiently performing continuous mixing, separation and removal by a centrifugal separator having a separation tank having a shearing portion inside in the step of washing and removing the water with water.

[0002]

2. Description of the Related Art Epoxy resins are usually prepared by reacting phenols with epihalohydrin in the presence of an alkali metal hydroxide and then dissolving them in a hydrophobic organic solvent to form unreacted alkali metal hydroxides and by-products. The obtained alkaline salt can be obtained by removing the alkali salt out of the system.

If a small amount of the inorganic ions based on the unreacted alkali metal hydroxide and the by-produced alkali salt remain in the epoxy resin, the quality of the epoxy resin is significantly deteriorated, and its removal is important.

Conventionally, in this purification method, the reaction product solution was washed by stirring and mixing with a large amount of water in a reaction product solution / water = 100/100 to 100/50 in a mixing tank. , After that, rinse water is separated by standing or
A method of obtaining a purified epoxy resin by centrifuging and then removing the solvent or dehydrating the water content in the solution and then performing microfiltration is used.

[0005]

However, for example, in the case where the reaction product solution and a large amount of water are stirred and mixed and then allowed to stand and separate, the reaction product solution and the water in which the alkali or the like is washed by the stir and mix are left to stand and separate. At the time of cleaning, the layer of washing water becomes a state in which the resin solution is contained in the gap between the water bubbles and the water bubbles, oil / water separation cannot be sufficiently performed, and impurities are not sufficiently removed to maintain the quality of the epoxy resin. In addition, it was necessary to repeat the water washing process. On the other hand, when the reaction product solution and a large amount of water are stirred and mixed and then centrifuged, the oil-water separation and the impurity removal are not sufficient in this case as well, and there is a problem that washing and separation must be repeated. Was.

The problem to be solved by the present invention is to efficiently wash and separate unreacted alkali metal hydroxide and by-produced alkali salt in a crude epoxy resin as a reaction product with a small amount of water. An object of the present invention is to provide a method for purifying an epoxy resin, which is excellent in the effect of removing impurities and has a significantly low content of impurities.

[0007]

In view of the above-mentioned conventional techniques, the present inventors have made earnest studies, and as a result, have found that the above-mentioned problems can be solved by the method described below, and have completed the present invention.

That is, the present invention is a mixed solution (A) of a crude epoxy resin obtained by reacting a phenol with epihalohydrin in the presence of an alkali catalyst, and an organic solvent,
It has a cylindrical hollow separation tank for water (B) and has an axis of rotation in the axial direction, and a disk-shaped or donut-shaped object coaxial with the rotation axis is provided inside the separation tank as a shearing part. The present invention relates to a method for continuously purifying an epoxy resin, which comprises continuously introducing the purified epoxy resin and treated water into the centrifuge, and continuously discharging the purified epoxy resin and the treated water from the centrifuge.

In the present invention, the reaction of phenols with epihalohydrin is similar to the production of known and commonly used epoxy resins, and the method is not particularly limited. For example, the reaction of addition of epihalohydrin to phenols in the presence of an alkali catalyst is carried out. After that, a method of producing a glycidyl ether group by performing a desalting reaction to obtain a target crude epoxy resin can be mentioned.

Examples of the epihalohydrin used in the present invention include epichlorohydrin, epibromohydrin and β-methylepichlorohydrin.
Preferred is epichlorohydrin.

The phenols used in the present invention are not particularly limited, but for example, divalent phenols such as hydroquinone, resorcin, catechol and dinaphthol, bisphenol A, bisphenol F, bisphenol S, bisphenol AD, tetrabromobisphenol. A and other bisphenols, biphenols such as tetramethylbiphenol, phenol novolac, cresol novolac, bisphenol A novolac, bisphenol F novolac and other novolac resins obtained from form aldevid, mononaphthol novolac, dinaphthol novolac, bis −
(2,7-dihydroxynaphthyl) -1,1-methane,
Naphthol novolak resin obtained from naphthols such as (2-hydroxynaphthyl) -1- (2,7-dihydroxynaphthyl) -1-methane, bis- (2-hydroxynaphthyl) -1,1-methane and formaldehyde, or , Dinaphthol novolac, bis- (2,7-dihydroxynaphthyl) -1,1-methane, (2-hydroxynaphthyl) -1- (2,7-dihydroxynaphthyl) -1-methane, bis- (2-hydroxy) Naphthyl)
Polyfunctional naphthols such as -1,1-methane, phenol, cresol, bisphenols, and polyglycidyl ethers of hydroxyl group-containing compounds, which are reaction products of naphthols with unsaturated alicyclic hydrocarbons such as dicyclopentadiene, Can be mentioned.

The alkali catalyst used in the reaction of the phenols with the epihalohydrin in the present invention is not particularly limited, but examples thereof include sodium hydroxide, potassium hydroxide and lithium hydroxide. Of these, sodium hydroxide and hydroxide are preferred. Potassium is preferred.

The organic solvent used in the present invention is not particularly limited as long as it is a hydrophobic organic solvent which dissolves an epoxy resin but is insoluble or hardly soluble in water, and is preferably methyl ethyl ketone, methyl isobutyl ketone or the like. There are ketone solvents, aromatic solvents such as toluene, xylene, and benzene. Further, the amount used is not particularly limited as long as the resin solution can have fluidity,
Crude epoxy resin / organic solvent = 100/2 on a weight basis because of its excellent fluidity and separation performance in a centrifuge.
It is preferably from 00 to 100/50.

Further, the continuous centrifugal separator used in the present invention has a cylindrical hollow separation tank having an axis of rotation in the axial direction, and a disk shape coaxial with the rotation axis inside the separation tank. An object or a donut-shaped object is provided as a shearing portion, and specifically, the one shown in the cross-sectional view of FIG. 1 can be mentioned. In the present invention, by disposing a shearing disk-shaped or donut-shaped shearing site in the separation tank, the resin cleaning efficiency is significantly improved, and the residual inorganic ion content in the purified epoxy resin product is 1 ppm.
It is possible to:

Further, the shearing portion to be disposed in the separation tank is a disk-shaped object or a donut-shaped object coaxial with the separation tank, and either one of them may be disposed. However, a disk-shaped object and a donut-shaped object may be arranged. In the latter case, it is preferable to form a plurality of shearing portions that are alternately stacked. Further, the disk-shaped product and the donut-shaped product may be fixed to the central axis and not accompanied by rotation of the separation tank, or may be completely fixed to the separation tank and rotated together with the separation tank. May be The method of introducing the mixed solution (A) and water (B) into the centrifuge and the method of discharging the purified product are not particularly limited, but the mixed solution (A) is separated from the separation tank in terms of excellent cleaning efficiency. Injecting and purifying the product purified from the inner shell, that is,
It is preferable to always introduce the mixed solution (A) containing unpurified crude epoxy resin and water (B) so that they are in countercurrent contact with each other in the tank.

More specifically, for example, referring to FIG. 1, a mixed solution (A) (heavy liquid) of a crude epoxy resin containing impurities such as water-soluble alkali metal hydroxide and alkali salt and an organic solvent. And does not dissolve in the mixed solution (A),
In addition, water (B) (light liquid) having different specific gravity is introduced into the cylindrical hollow separation tank shown in A of FIG. Is rotated in the circumferential direction of the shaft, and this rotational force and the internal first
B (disk shape) and B '(doughnut shape) in the figure
Is mixed by the shearing site shown in Fig. 1, and after mixing is separated by centrifugal force due to rotation in the separation chamber shown in Fig. 1C to remove impurities, and the purified heavy liquid, which is an epoxy resin solution, removes impurities from the outer shell. The method of discharging the contained light water (treated water) from the inner shell is mentioned.

The rotational speed of the centrifugal separator is not particularly limited, but it is preferably 1000 to 3000 rpm from the viewpoint that the effect of the present invention is remarkable.

Further, the centrifugal separator used in the present invention is the first
It is not limited to the single tank type represented by the drawing, but has a plurality of separation tanks in which shearing portions are arranged in the axial direction, particularly 2
Those having up to 6 stages are preferable because the cleaning effect is remarkably excellent. In this case, the structure is not particularly limited, but in order to make the cleaning effect and the separation efficiency remarkably remarkable, the crude epoxy resin-containing solution solution (A) is introduced from the inner shell at the bottom of the uppermost separation tank. , Passed through the shearing site and fed into the separation chamber, then through the outlet located at the upper or lower part of the outer shell of the separation chamber to the next lower separation tank, and also introduced from the inner shell at the bottom of the separation tank in the next separation tank. The same separation as in the case of the uppermost separation tank is performed and finally discharged from the outer shell of the lowermost separation tank, while water (B) is discharged.
Is finally introduced from the bottom of the lowermost separation tank, and after washing the resin, it is sequentially transferred to the upper separation tank through the passage provided in the inner shell of each separation tank, and finally to the uppermost. It is preferable to have a structure in which the treated water is discharged from the upper part of the inner shell of the upper separation tank.

As such a centrifugal separator, for example, as a single tank horizontal type, a Ultrex centrifugal extraction device manufactured by Hitachi, Ltd., and a vertical 1- to 6-stage type Robertate centrifugal extractor manufactured by Robatel Co. are cited. To be

In the present invention, the mixing ratio of the mixed solution (A) of the crude epoxy resin and the organic solvent and the water (B) is not particularly limited and, of course, a large amount of water is used to obtain a cleaning effect. Although it may be improved, in the present invention the washing efficiency is significantly improved because it has a shearing site in the separation tank, and the unreacted alkali metal hydroxide and by-produced alkali salt are efficiently prepared from the reaction product. Since it can be separated and removed, the amount of water (B) used can be kept very small. Specifically, mixed solution (A) / water (B) = 100/30 to 100 /
The range of 5 is mentioned.

In particular, when the centrifugal separator having the above-mentioned multi-stage separation layers is used, the unpurified epoxy resin solution and water are always brought into contact with each other in a countercurrent direction in the tank, that is, purified in each separation tank. Since the reaction product solution being prepared has a structure that finally comes into contact with fresh water near the outlet, the amount of water used can be significantly reduced.

[0022]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto.

Synthesis Example 1 Tetrabrom bisphenol A (15 kgs), epichlorohydrin (4.9 kgs) and toluene (9.0 kg) were placed in a 50 liter reactor equipped with a stirrer, a heating medium, a cooling medium, a temperature indicator, a dropping tank and a cooling condenser.
After being dissolved in s, 21.0 kgs of 20% aqueous sodium hydroxide solution was added dropwise at 80 ° C. over 5 hours while stirring,
React for another hour, then discard the aqueous layer ,. 27 kgs of an epoxy resin toluene solution was obtained.

Synthesis Example 2 32 kgs of an epoxy resin toluene solution was obtained in the same manner as in Synthesis Example 1, except that the amount of toluene was 14 kgs.

Synthesis Example 3 In the same apparatus as in Synthesis Example 1, 5 kgs of o-cresol novolac resin was dissolved in 20 kgs of epichlorohydrin, and 11 kgs of 20% NaOH was added at 70 ° C. for 3 hours. Then, the mixture was stirred at the same temperature for 1 hour, allowed to stand still for liquid separation, and the aqueous layer was discarded. Then, the excess epichlorohydrin was recovered by distillation, and methyl isobutyl ketone (MiB
K) dissolved in 11 parts to obtain 18 parts of epoxy resin MiBK solution.

Example 1 27 kg of the epoxy resin toluene solution obtained in Synthesis Example 1
s and 1.4 kgs of water, resin solution / water = 100/5 to 2
With a weight of 0, a 4-stage vertical Robertel centrifugal extractor (a disk-shaped shearing part and a donut-shaped shearing part are alternated for each tank
The resin solution after purification and the treated water were discharged. The rotation of the centrifuge at this time is 150
It was adjusted to 0 rpm. Toluene and water were removed from the purified resin solution under reduced pressure to obtain 18 kgs of purified epoxy resin. Then, the yield of the obtained epoxy resin purified product,
The amount of free chlorine, free sodium and epoxy equivalent were determined.
The results are shown in Table-1.

Examples 2 to 12 Purified epoxy resin products were obtained in the same manner as in Example 1 except that the epoxy resin solution used, the washing conditions and the separation conditions were in accordance with Table-1 to Table-4.

Then, the yield, free chlorine amount, free sodium, and epoxy equivalent of the obtained epoxy resin refined product were determined. The results are shown in Table-1 to Table-4.

Examples 13 to 15 Epoxy was carried out in the same manner as in Example 1 except that the centrifugal extractor was a single tank horizontal type Ultrex centrifugal extractor, which was connected in series in four stages, and the washing conditions and separation conditions were in accordance with Table-5. A purified resin product was obtained.

Then, the yield, free chlorine amount, free sodium, and epoxy equivalent of the obtained purified epoxy resin product were determined. The results are shown in Table-5.

Examples 16 to 21 Using the epoxy resin MiBK solution obtained in Synthesis Example 3,
A purified epoxy resin product was obtained in the same manner as in Example 1 except that the washing conditions and the separation conditions were in accordance with Table-6 to Table-7.

Then, the yield, free chlorine amount, free sodium, and epoxy equivalent of the obtained purified epoxy resin product were determined. The results are shown in Table-6 to Table-7.

Comparative Example 1 27 kg of the epoxy resin toluene solution obtained in Synthesis Example 1
s was washed with 1.4 kgs of water in a 50 liter reactor, the aqueous layer was discarded, and toluene and water were removed from the resin solution under reduced pressure to obtain a purified epoxy resin product.

Then, the yield, free chlorine amount, free sodium, and epoxy equivalent of the obtained epoxy resin purified product were determined. The results are shown in Table-8.

Comparative Examples 2 to 6 Purified epoxy resin products were obtained in the same manner as in Comparative Example 1 except that the epoxy resin solution used, the washing conditions and the separation conditions were in accordance with Table-8 to Table-9.

Then, the yield, free chlorine amount, free sodium, and epoxy equivalent of the obtained purified epoxy resin product were determined. The results are shown in Table-8 to Table-9.

Comparative Example 7 27 kgs of an epoxy resin toluene solution obtained by the same method as in Synthesis Example 1 was washed with 1.4 kgs of water in a reactor of 50 liters, and then there was no shearing site in the separation tank. After centrifuging with a centrifuge and discarding the aqueous layer, toluene and water were removed from the resin solution under reduced pressure to obtain a purified epoxy resin product.

Then, the yield, free chlorine amount, free sodium, and epoxy equivalent of the obtained purified epoxy resin product were determined. The results are shown in Table-10.

Comparative Examples 8 to 15 Purified epoxy resin products were obtained in the same manner as in Comparative Example 1 except that the epoxy resin solution used, the washing conditions and the separation conditions were in accordance with Table-8 to Table-9.

Then, the yield, free chlorine amount, free sodium, and epoxy equivalent of the obtained epoxy resin purified product were determined. The results are shown in Table-10 to Table-12.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

[Table 6]

[0047]

[Table 7]

[0048]

[Table 8]

[0049]

[Table 9]

[0050]

[Table 10]

[0051]

[Table 11]

[0052]

[Table 12]

[0053]

According to the present invention, the unreacted alkali metal hydroxide and the by-produced alkali salt in the reaction product crude epoxy resin can be efficiently washed and separated with a small amount of water. Further, it is possible to provide a method for purifying an epoxy resin, which has a markedly excellent effect of removing impurities and in which the content of impurities is significantly reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an example of a centrifugal separator used in the purification step of the purification method of the present invention.

[Explanation of symbols]

 A: Cylindrical hollow separation tank B: Shearable portion (disk-shaped object) B ': Shearable portion (donut-shaped object) C: Separation chamber

Claims (8)

[Claims] 1. A mixed solution (A) of a crude epoxy resin obtained by reacting a phenol with epihalohydrin in the presence of an alkali catalyst and an organic solvent, and water (B), with a rotating shaft in the axial direction. It has a cylindrical hollow-shaped separating tank having and continuously introduces a disk-shaped object or a donut-shaped object coaxial with the rotating shaft into the centrifugal separator provided as a shearing part inside the separating tank. And then continuously discharging the purified epoxy resin and the treated water from the centrifuge. 2. The continuous purification method according to claim 1, wherein the mixed solution (A) is continuously supplied from the inner shell of the centrifugal separator to the separation tank, and the purified epoxy resin is discharged from the outer shell of the separation tank. 3. The continuous purification method according to claim 2, wherein the centrifugal separator has a coaxial separation tank in a vertical direction of 2 to 6 stages. 4. The rotation speed of the separation tank of the centrifugal separator is 100.
The continuous purification method according to claim 2 or 3, which is 0 to 3000 rpm. 5. The mixing ratio of the mixed solution (A) and the water (B) is, on a weight basis, the mixed solution (A) / water (B) = 100.
It is / 30-100 / 5, The continuous purification method as described in any one of Claims 1-4. 6. The mixed solution (A) comprises a crude epoxy resin,
The abundance ratio with the organic solvent is reaction product / organic solvent = 100/200 to 100/50 on a weight basis.
The continuous purification method according to any one of 1. 7. The phenols are bisphenols or substituted phenol novolacs.
The described continuous purification method. 8. The organic solvent is a hydrophobic solvent.
~ 7 continuous purification method.