JPH07206767A - Production of polyglycerol ester of fatty acid - Google Patents

Abstract

PURPOSE:To recover unreacted polyglycerol and reutilize the recovered polyglycerol as a raw material for esterification thereof with a fatty acid in producing a polyglycerol ester of the fatty acid (PoGE). CONSTITUTION:This method for producing a polyglycerol ester of a fatty acid comprises carrying out the liquid-liquid extraction of a reactional mixture prepared by esterifying a polyglycerol with a fatty acid by using an organic solvent and water, using the resultant aqueous solution for the treatment with an anion exchange resin and thereby substantially completely removing the PoGE contained in a very small amount. As a result, the high-purity polyglycerol is recovered and reutilized as a raw material for the esterification.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polyglycerin fatty acid ester (hereinafter referred to as PoGE).
More specifically, the present invention provides a method for industrially advantageously and easily recovering highly pure polyglycerin from a reaction mixture containing PoGE produced by an esterification reaction of polyglycerin and a fatty acid. is there.

[0002]

2. Description of the Related Art PoGE is a highly safe surfactant approved as a food additive. It is mainly used as an emulsifying agent and solubilizing agent for foods, and in recent years, its application has spread to fields such as cosmetics and pharmaceuticals. PoGE
Is usually produced by esterifying a fatty acid and polyglycerin. PoGE has a wide range of HLB (from hydrophilic to hydrophobic) by selecting the degree of polymerization of the polyglycerin part that is a hydrophilic group, the type of the fatty acid part that is a hydrophobic group, and the degree of esterification. Hydro
philic-Lipophilic Balanc
e) is a compound of choice. Glycerin fatty acid esters, lecithin and the like have been used as relatively inexpensive and general-purpose emulsifiers for foods, but they are oil-soluble and therefore disadvantageous in forming emulsions having a high water content.
On the other hand, PoGE has a major feature that it can obtain the most suitable ones depending on the application, from those which are not readily soluble in water (high HLB) to those which are oil-soluble (low HLB).

PoGE, which is easily water-soluble, is obtained by reacting an excess amount of polyglycerin with a fatty acid to produce a large amount of monoester. Therefore, unreacted polyglycerin remains in the reaction mixture. PoG
Even when E remains unreacted polyglycerin, it may not cause any trouble when used as an emulsifier, etc., but depending on the application, it is necessary to separate polyglycerin to obtain high-purity PoGE. It is industrially preferable that the polyglycerin separated here is recovered and reused in the esterification reaction.

As a method for separating PoGE and polyglycerin, there is a method of liquid-liquid extraction using a poorly water-miscible organic solvent and water as an extractant. In this method, PoGE is added to the organic solvent phase.
To extract polyglycerin into the aqueous phase. However, in the liquid-liquid extraction, it is inevitable that the above aqueous phase contains a small amount of PoGE because there is mutual dissolution to some extent. Therefore, if the aqueous solution obtained by this liquid-liquid extraction is used as it is as a raw material for the esterification reaction, the Po
There is a drawback that GE becomes an impurity. In particular, when reused as a raw material for a reaction for producing PoGE having different fatty acids, PoGE composed of different fatty acids is mixed, which is not preferable.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a method for industrially advantageously recovering highly pure polyglycerin by substantially completely removing PoGE contained in the aqueous solution. .

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, by treating the aqueous solution with an anion exchange resin, it was found that highly pure polyglycerin can be recovered, The present invention has been completed.

According to the present invention, a fatty acid and polyglycerin are subjected to an esterification reaction, the resulting reaction mixture is subjected to liquid-liquid extraction using a poorly water-soluble organic solvent and water as an extractant, and PoGE is added to the organic solvent phase. , Polyglycerin is extracted into the aqueous phase, the liquid is separated, and then the aqueous solution obtained in the liquid-liquid extraction step is brought into contact with the anion exchange resin. Upon contact with the anion exchange resin, PoGE in the aqueous solution is decomposed into polyglycerin and fatty acid, and the fatty acid produced by the decomposition is adsorbed by the anion exchange resin. Then, the aqueous solution after the treatment with the anion exchange resin is dehydrated, whereby purified polyglycerin having an extremely low PoGE content can be recovered.

The present invention will be described in detail below. In the present invention, polyglycerin having an average degree of polymerization of 4 to 14 and a hydroxyl value of 800 to 1100 is usually used. As the fatty acid, a C8 to C22 saturated or unsaturated fatty acid is usually used, and for example, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, erucic acid, etc. are used. The amount of fatty acid used varies depending on the type of polyglycerin produced and HLB, but is usually 0.01 to
It is used in a range of 10 times by mole, preferably 0.1 to 1.0 times by mole. If too much fatty acid is used with respect to polyglycerin, PoG with a high monoester content
If E is not generated or is too small, the amount of PoGE itself generated is small and the subsequent separation step is inefficient, which is not economically advantageous.

The esterification reaction of polyglycerin with a fatty acid proceeds without a catalyst, but it may be carried out in the presence of an alkali catalyst. As the alkali catalyst, for example, N
Examples thereof include aOH, K ₂ CO ₃ , KOH, Na ₂ CO ₃ . The amount of the alkali catalyst used is 5 × 10 ⁻⁷ to 1 mol times, preferably 5 × 10 ^{−6 to} 0.
It is 1 mol times. The esterification reaction is usually performed by supplying polyglycerin, a fatty acid, and a catalyst to a reactor, stirring and mixing, and heating at a predetermined temperature for a certain time while removing water generated by the esterification reaction from the system. The reaction temperature is usually 180 to 260 ° C., preferably 200 to 250 ° C. The reaction pressure conditions are reduced pressure or normal pressure, and the reaction time is 0.5 to 15 hours.

In the reaction of the present invention, a solvent may be used, but usually polyglycerin is also used as a solvent. The water-miscible organic solvent is not particularly limited as long as it can be separated from water, for example, hydrocarbons such as heptane, octane, xylene, toluene, methyl ethyl ketone, ketones such as methyl isobutyl ketone, methyl acetate, ethyl acetate. , Esters such as ethyl propionate, halogenated hydrocarbons such as dichloromethane, chloroform and carbon tetrachloride, C4 or higher alcohols such as n-butyl alcohol and isobutyl alcohol, and particularly the above alcohols from the viewpoint of safety. Is preferred.

The liquid-liquid extraction method may be a batch method or a continuous method, and the separation of the organic solvent phase and the aqueous phase may be a static method or a centrifugal method. The amount of water used as the extractant is 0.1 with respect to the organic solvent also used as the extractant.
It is 10 to 10 times by weight, preferably 0.5 to 3 times by weight. If the amount of water is too small, the extraction efficiency will be poor, and if it is too large, it will take time to remove water in the subsequent step, which is inefficient. The amount of the extractant used in the reaction mixture is preferably 5 to 20 times the volume of the reaction mixture 1.

The extraction temperature may be a temperature at which PoGE in the organic solvent phase does not precipitate, and is usually 10 to 90 ° C, preferably 40 to 90 ° C. After the extraction, in order to form the interface between the organic solvent phase and the aqueous phase satisfactorily and quickly, a salting-out agent such as sodium chloride or potassium lactate is added in an amount of 0.1.
Extraction is preferably carried out under the condition of containing 10%.

After extraction, the aqueous solution obtained by liquid separation may be directly subjected to the subsequent treatment with an anion exchange resin. However, after removing the organic solvent contained in the aqueous solution, anion exchange is performed. It may be subjected to treatment with a resin. The concentration of polyglycerin in the aqueous solution used for the treatment with the anion exchange resin is usually 1 to 90% by weight, but it is preferably 30 to 50% by weight in the operation of the treatment step. When the concentration of polyglycerin becomes high, the viscosity of the aqueous solution becomes high, the diffusion into the anion exchange resin becomes insufficient, and the decomposition efficiency of PoGE and the operability of the treatment process decrease. Conversely, if the concentration of polyglycerin is too low, it takes time to remove water from the aqueous solution obtained after the treatment step, which is inefficient.

As the anion exchange resin, any one can be used as long as it has an anion exchange ability, and any one such as a strong basic anion exchange resin and a weak basic anion exchange resin can be used. The treatment method is arbitrary such as passing through a column or stirring with suspension, and the treatment temperature is usually in the range of 10 to 90 ° C. By the treatment, most of PoGE contained in the aqueous solution is decomposed. In addition, PoG in the aqueous solution used for this treatment
The content of E is usually preferably 0.1 to 10% by weight.

When an alkali catalyst is used in the esterification reaction and a salting-out agent is used in the extraction, the salt is contained in the aqueous solution, but if desired, the anion exchange resin may be used. These salts can be removed by subsequent treatment with a cation exchange resin. Further, purification means such as activated carbon treatment may be added before or after the treatment with the anion exchange resin.

The aqueous solution subjected to the above ion exchange resin treatment usually has a water content of 0.1% by weight by a thin film evaporator or the like.
It is dehydrated until it becomes below. The polyglycerin thus obtained has a very low PoGE content and is purified, and can be effectively reused as a raw material for the esterification reaction.

[0017]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 Polyglycerin (average degree of polymerization: 10.9, average molecular weight: 82)
5, 12.7 kg of hydroxyl value 888 mg KOH / g) and 1.3 kg of stearic acid (the molar ratio of polyglycerin and stearic acid is 1: 0.26) were charged into a stirring reactor equipped with a heating jacket, and the temperature was increased to 240 ° C. After the temperature was raised, 3.5 ml of a 10 wt% NaOH aqueous solution (5 × 10 ⁻⁴ mol times with respect to polyglycerin) was added, and the reaction was continued for 2.5 hours while distilling generated water out of the system, and further 260 ° C. The reaction was carried out for 2.5 hours. The polyglycerin stearic acid ester in the reaction mixture obtained by this method was 30% (monoester content 90%), and the unreacted polyglycerin was 70%.

Subsequently, the reaction mixture was used as an extractant with isobutyl alcohol and water in a weight ratio of 1: 2, and the polyglycerin stearic acid ester and unreacted polyglycerin were extracted from the reaction mixture using a mixer-settler type extractor. Under a condition of an extraction temperature of 80 ° C., a salting out agent of 200
Liquid-liquid extraction was performed in the presence of 0 ppm potassium lactate.

Water was removed from the aqueous solution obtained by the above liquid-liquid extraction step using a thin film evaporator to obtain 9.7 kg of polyglycerin. When this polyglycerin was analyzed by liquid chromatography, 1.0% of polyglycerin stearic acid ester was contained as an impurity.

A 30% by weight aqueous solution of the above polyglycerol was applied to a column of a weakly basic anion exchange resin at 60 ° C.
Liquid was passed at SV (space velocity) 2. Column has a diameter of 83 m
800 ml of Diaion WA-30 (diaion is a registered trademark of Mitsubishi Kasei Co., Ltd.) swollen with water is filled with m and 1000 mm in length. The aqueous solution flowing out from the column was dehydrated by a thin film evaporator until the water content became 0.1% or less, and the obtained polyglycerin was analyzed by liquid chromatography to determine the PoGE content by the area ratio. The results are shown in Table-1.

Comparative Example 1 The same purification treatment as in Example 1 was carried out except that a strongly acidic cation exchange resin (Diaion PK-216) was used instead of the anion exchange resin. The results are shown in Table-1.

Example 2 Polyglycerin containing 2.7% polyglycerin stearate was passed through a column of a strongly basic anion exchange resin (Diaion PA-308) as a 30% by weight aqueous solution at 50 ° C. and SV1. Liquor The column has a diameter of 22 mm,
Diamond ion PA-330 mm long and swollen with water
60 ml of 308 is filled. The aqueous solution flowing out from the column was supplied to a rotary evaporator and dehydrated to obtain polyglycerin, which was analyzed in the same manner as in Example 1. The results are shown in Table-1.

[0024]

[Table 1]

Since no fatty acid was detected in the polyglycerin after the treatment with the anion exchange resin, it is considered that the fatty acid produced by the decomposition of PoGE was adsorbed by the ion exchange resin.

[0026]

According to the present invention, since PoGE, which is an impurity in unreacted polyglycerin, is substantially completely removed, highly pure polyglycerin can be recovered, and this polyglycerin can be used as a raw material for the esterification reaction. Since it can be reused as, it is industrially advantageous.

Claims (1)

[Claims] 1. A method for obtaining a polyglycerin fatty acid ester from a reaction mixture obtained by reacting polyglycerin with a fatty acid, wherein the reaction mixture is subjected to liquid-liquid extraction using an organic solvent and water as an extractant. Glycerin was extracted into the aqueous phase and polyglycerin fatty acid ester was extracted into the organic solvent phase, and in recovering polyglycerin from the aqueous solution obtained in this extraction step, the aqueous solution was contacted with an anion exchange resin and then dehydrated to obtain poly A method for producing a polyglycerin fatty acid ester, which comprises recovering glycerin.