JPH03135935A - Production of oligoethylene glycol - Google Patents

Abstract

PURPOSE:To industrially simply obtain the title high-quality compound with the average number of recurring oxyetylene units specified by mixing an oligoethylene glycol with such average number exceeding the specified level mentioned above with a specific hydrocarbon followed by distillation and then phase separation of the distillate. CONSTITUTION:(a) An oligoethylene glycol (OEG) with the average number of oxyethylene units exceeding 3 is mixed with (b) a 14-20C chain or alicyclic saturated hydrocarbon at the weight ratio a/b = pref. (10 : 1) - (1 : 1) followed by distillation pref. at 100 - 200 deg.C under a reduced pressure of 5 - 20mmHg. The resulting mixed distillate is put to phase separation, thus advantageously obtaining, using a simple distillation unit, the objective greatly high-quality OEG free from discoloration and scorching odor with said average number the recurring units being > 3 but < 6 (esp. a high-boiling OEG like tetraethylene glycol), useful as a raw material for e.g. unsaturated polyester resins.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention is useful as a raw material for unsaturated polyester resins, etc., and contains more than 3 oxyethylene groups and less than 6, which is substantially difficult to distill by simple methods. This invention relates to a method for producing certain high-quality oligoethylene glycols by distillation.

“Prior art” Oligoethylene glycols with a low degree of polycondensation (hereinafter referred to as OE
Even if one tries to simply distill a mixture of (abbreviated as G), the OEG that can be obtained is at most triethylene glycol, which has three oxyethylene groups, and even if one attempts to obtain glycols with more than three oxyethylene groups from Kuroshio, it is difficult to obtain a color-free product. In order to obtain it, it is necessary to use a very special Kuroshio device,
The above OEG obtained by simple distillation is naturally colored,
Moreover, a so-called burnt odor remained.

However, the above-mentioned OEGs have various uses as mentioned above, and depending on these uses, it is required to change the molecular weight distribution of polyethylene glycol with a relatively low degree of polycondensation, which is produced by the known polyaddition of ethylene oxide. It may be done. In addition, if the product becomes colored after being used for a long time or stored for a long period of time, decolorization and purification may be required.

Furthermore, for example, it is virtually impossible to obtain OEG with a higher molecular weight from the residue obtained by distilling ethylene glycol, diethylene glycol, and triethylene glycol by hydration of ethylene oxide, respectively, by simple distillation.

For the above reasons, even if one attempts to achieve the above objective by lowering the apparent boiling point by distilling the above OEG by coexisting with a second component that is mutually soluble, this method does not achieve the objective of lowering the boiling point. However, this Kuroshio method does not fully achieve its purpose because the distilled components mix with each other to form a homogeneous solution.

``Problem to be solved'' However, when considered comprehensively as a method for obtaining OEG with an average repeating unit number of oxyethylene groups of more than 3 and less than 6, it goes without saying that distillation is an irreplaceable method. Nor.

On the other hand, if the above OEG coexists with components that do not dissolve in each other in the liquid and gas phases, the partial pressure occupied by OEG during the Kuroshio will become part of the pressure inside the Kuroshio device, and therefore the pressure will be reduced substantially. It was expected that the same effect as distilling OEG at higher temperatures would be obtained.

Therefore, as a result of intensive study on other components that do not dissolve with this OEG and can withstand the above-mentioned distillation, in other words, as a result of studying to obtain the above-mentioned OEG by distillation using an industrially simple method, we found that If hydrocarbons are coexisted and distilled, OEG with deteriorated quality can be converted into OEG that can withstand use.
EG, or a specific OEG with a changed molecular weight distribution from OEG having a high molecular weight distribution, and the above-mentioned hydrocarbons can both be distilled easily without any of the above-mentioned alterations, and the distilled OEG and the above-mentioned hydrocarbons. The inventors have discovered that they do not dissolve in each other and that by phase-separating them, an extremely high-quality OEG with no coloration or burnt odor can be obtained, and the present invention has been achieved.

[Means for solving the problem] That is, it is obtained by distilling a mixture of oligoethylene glycols having an average repeating unit number of oxyethylene groups of more than 3 and a linear or alicyclic saturated hydrocarbon having 14 to 20 carbon atoms. A method for producing oligoethylene glycols having an average repeating unit number of oxyethylene groups of more than 3 and less than 6, characterized by phase separation from a mixed distillate.

In the method of the present invention, any OEG before the Kuroshio current may be used as long as the above-mentioned average number of repetitions exceeds 3. However, if this repeating unit is too high, the OEG before the Kuroshio current may not be used. , substantially black-water-resistant, and therefore it is preferred to use an OEG having an average number of repeating units of less than about 8. In addition, if the number of repeating units is 3 or less,
Since it can be obtained by simple distillation without using the method of the present invention,
However, it is not necessary to use it in the method of the present invention.

It is essential that the above-mentioned specific hydrocarbons to be coexisted are those that are present after the Kuroshio curvature and do not substantially dissolve in each other with OEG, and furthermore, do not have a boiling point significantly higher than that of the OEG to be obtained. This is essential. The hydrocarbons satisfying these conditions are preferably saturated chain or saturated alicyclic hydrocarbons having 12 to 30 carbon atoms, and the above-mentioned hydrocarbons having 14 to 20 carbon atoms are particularly preferred.

These hydrocarbons include chain hydrocarbons such as tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, and eicosane, and alicyclic hydrocarbons such as octylcyclohexane, undecylcyclohexane, dodecylcyclohexane, and decylcyclooctane. I can give an example. These can be used alone or as a mixture of two or more.

The OEGs with an average repeating unit number of oxyethylene groups exceeding 3 used in the method of the present invention may be any OEGs as long as the average molecular weight exceeds the molecular weight of triethylene glycol, that is, 150, but if this molecular weight is too high, If the molecular weight is large, even if the above-mentioned hydrocarbons are used for distillation, the amount of OEGs that can be distilled in parallel becomes extremely small. Therefore, it is preferable that the average molecular weight is less than 500.

These OEGs include those that are relatively low molecular weight portions of polyethylene glycol that require some kind of treatment;
Kurobe residue containing tetraethylene glycol or pentaethylene glycol, etc., which is produced as a by-product during the production of ethylene glycols, or residue from Kuroshio Current collection for reuse of ethylene glycol recovered during the production of polyethylene terephthalate using ethylene glycol. Examples of ingredients etc.

Next, embodiments of the method of the present invention will be described.

If OEGs and hydrocarbons, which are raw materials such as those mentioned above, are allowed to coexist in a normal distiller and heated at a desired degree of vacuum, OEG and hydrocarbons will simultaneously have a molecular weight distribution different from that of the distiller. By vaporizing and cooling these,
Both are obtained as liquids without any coloration.

The degree of reduced pressure during distillation varies depending on the average number of repeating units of oligoethylene groups in the raw material OEG used and the type of hydrocarbons coexisting, but in order to obtain an odorless product with a low degree of coloration, it is preferably 5 m + + + Hg to 20 mm 1 G.
The degree of depressurization should be taken at a certain level. At this degree of pressure reduction, the Kuroshio temperature is about 100 to 200'C.

The Kuroshio method of the present invention is not particularly limited and can be carried out either batchwise or continuously.

As described above, these liquids obtained in this manner do not dissolve in each other but separate into two phases, so that the target OEG and hydrocarbons are separated by phase separation using a known method. It goes without saying that the separated hydrocarbons can be recycled to the distillation system and reused.

The solubility of the above-mentioned hydrocarbons in the obtained OEG is extremely low, so it is not essential to carry out purification operations such as washing. The product can be produced by adsorption treatment with water, or by extracting trace amounts of the hydrocarbons with low boiling point hydrocarbons such as n-hexane or cyclohexane.

"Example j" The method of the present invention will be explained in more detail below by giving Examples and Comparative Examples, but the method is not limited to these.In addition, in the following description, things indicated by 2 are not particularly specified. Weight 2 is shown unless otherwise noted.

Example 1 In an IA distiller equipped with a distiller, a cooler, and a liquid-liquid separator, 500 g of an oligoethylene glycol mixture consisting of 18% triethylene glycol, tetraethylene glycol 76X, and 6z of high-boiling glycols higher than pentaethylene glycol were added. 80 g of hexadecane with a purity of 98% was added, and the hydrocarbons distilled together were separated in a liquid-liquid separator and returned to the distillation system for distillation. Under a reduced pressure of lOmmHg, 1
The portion obtained in the range 27-130'c weighed 278g.

Analysis of this portion by gas chromatography revealed that it consisted of 7.1% triethylene glycol, 92.0% tetraethylene glycol, 0.9% pentaethylene glycol, and 0.5% hexadecane.

The mixed hexadecane was removed by heating this part to 130'C under a reduced pressure of 5 mynHg.
The hue of this product was 10 or less on the AP)IA (hue display method based on the American Public Health Association) display, and was nearly colorless and transparent, and was odorless.

The front portion during this distillation weighed 150 g, and the residue remaining in the distiller was 60 g.

Example 2 Triethylene glycol 8 was added to the Kuroshio device similar to Example 1.
%, tetraethylene glycol 75% and oligoethylene glycols higher than pentaethylene glycol 17%
and 80 g of a hydrocarbon mixture consisting of 31% hexadecane, 45% heptadecane, and 24% octadecane were put into a distiller, and the hydrocarbons distilled together were separated in a liquid-liquid separator and returned to the distillation system while distilling. went. The portion obtained in the range of 140-145° C. under a reduced pressure of 7-10 Hg weighed 384 g.

Analysis of this glycol component revealed that triethylene glycol was 3.2%, tetraethylene glycol was 85.0%,
It was found to consist of 10.8% pentaethylene glycol and 1.0% hexaethylene glycol.

The front portion during this distillation weighs 75g, and the residue weighs 40g.
Met.

This target area contained trace amounts of hydrocarbons, so
After extraction with 30 mα of n-hexane, n-hexane was removed under reduced pressure.

The hue of the obtained target product was 10 or less on the APHA scale, and was substantially colorless and transparent.

Example 3 The residue obtained by removing ethylene glycol, diethylene glycol, and triethylene glycol from the reaction product obtained by adding ethylene oxide to water (triethylene glycol 8%, tetraethylene glycol 85%, glycols higher than pentaethylene glycol) ) and 80 g of a saturated alicyclic hydrocarbon mixture consisting of 40% decylcyclohexane, 30% undecylcyclohexane and 30% dodecylcyclohexane were placed in the distiller described in Example 1, and both The distilled hydrocarbons were separated in a liquid-liquid separator and returned to the distiller during the front section. 9-109-1O under reduced pressure, 13
The volume obtained in the range 0-135°C was 373 g.

The composition of this glycol component is 3.5% triethylene glycol, 95.4% tetraethylene glycol, and 1.1% high-boiling glycol higher than pentaethylene glycol.
%Met.

The front portion during this distillation weighs 75g, and the residue weighs 49g.
Met.

This target area contained trace amounts of hydrocarbons, so
Adsorption and filtration were carried out using about 2 g of active substance to obtain a substantially colorless, transparent and odorless target product having an APHA value of IO or less.

Comparative Example 1 When the method described in Example 1 was carried out without the coexistence of hexadecane, no glycols having a molecular weight greater than tetraethylene glycol were distilled out.

Furthermore, the temperature was increased at the same degree of vacuum, and the temperature of the distiller was raised to 200.
Although a foam mainly consisting of tetraethylene glycol was obtained at temperatures above .degree. C., the hue was API (A) 150 or higher, and there was a significant burnt odor.

"Effects of the Invention" By using the method of the present invention, oligoethylene glycols having a high boiling point such as tetraethylene glycol, which was previously thought to be practically impossible, can be obtained even using a simple Kuroshio apparatus.

Claims (1)

[Claims] 1. Mixed distillation obtained by distilling a mixture of oligoethylene glycols having an average repeating unit number of oxyethylene groups exceeding 3 and a linear or alicyclic saturated hydrocarbon having 14 to 20 carbon atoms. A method for producing oligoethylene glycols having an average number of repeating units of oxyethylene groups of more than 3 and less than 6, characterized by phase separation from a substance. 2. The manufacturing method according to claim 1, characterized in that a mixture in which the weight ratio of the oligoethylene glycols and the hydrocarbons is 10/1 to 1/1 is distilled. 3. The manufacturing method according to claim 1 or 2, characterized in that the mixture is distilled at a temperature range of 100 to 200°C.