JPH02164887A - Purification of powdery high-hlb sucrose fatty acid ester - Google Patents

Abstract

PURPOSE:To purify the title water-soluble compound without using an organic solvent by adjusting a synthetic reaction mixture of sucrose fatty acid ester containing unreacted substances by water medium method to neutral pH, adding a neutral salt to the mixture, washing formed precipitate with acidic water and bringing the washed solution into contact with an ultrafilter. CONSTITUTION:A synthetic reaction mixture of sucrose fatty acid ester containing the aimed substance of sucrose fatty acid ester, unreacted sugar, unreacted fatty acid methyl ester, catalyst, soap and fatty acid by water medium method is adjusted to a neutral range, preferably pH6.2-8.2 and heated to preferably 50-80 deg.C. Then the mixture is blended with water and a neutral salt (preferably salt, Glauber's salt, potassium lactate or potassium acetate) and formed precipitate is washed with acidic water (preferably pH3.5-6.5 at 10-40 deg.C). The washed solution is brought into contact with an ultrafilter to recover the aimed water-soluble aimed ester.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for purifying high HLB sucrose fatty acid esters. More specifically, the present invention relates to a method for purifying high HLB sucrose fatty acid ester and recovering it in an aqueous state without using any organic solvent in either the reaction step or the purification step. be.

[Conventional technology]

(Background) Currently, sucrose fatty acid esters (
Hereinafter (abbreviated as (S E ))), sucrose and 0
8 to C22 higher fatty acid methyl ester is reacted with a suitable catalyst in a solvent (dimethylformamide, dimethyl sulfoxide, etc.) (solvent method: Japanese Patent Publication No. 35-13
102) Or by making sucrose into a molten mixture with fatty acid soap using water without using a solvent, and then reacting it with higher fatty acid methyl ester in the presence of a catalyst (water medium method: Japanese Patent Publication No. 14485/1985). It has been obtained. However, in both of these two synthesis methods, the reaction mixture contains, in addition to the target SH, unreacted sugars, unreacted fatty acid methyl esters, residual catalysts, soaps, free fatty acids, etc. Among these impurities, impurities that exceed a specified amount must be removed before becoming a product. In particular, the former solvent method requires complicated steps to remove high-boiling polar solvents such as DMF, whose regulations have become particularly strict in recent years. On the other hand, according to the latter aqueous method, there is no fear that the reaction solvent will be mixed into the reaction mixture, but since it contains a large amount of impurities, a large amount of organic solvent (hereinafter referred to as However, the use of crude solvents brings about many industrial disadvantages as described below. ■ Risk of explosion or fire. ■ Explosion-proofing of electrical equipment in preparation for ■ above. ■ Sealing the manufacturing equipment in preparation for the second ■. ■ The entire building will be made into a fire-resistant structure in preparation for ■ above. ■ Increase in fixed costs due to ``Second ■, ■, ■. ■ 1 increase in cost due to solvent loss. ■ Negative effects due to residual solvent remaining in product SE. ■ An increase in the number of shifts due to the negative impact on employees' health, and furthermore, an increase in the number of shifts and an increase in costs due to the lack of prevention. These disadvantages due to the use of f8 media are particularly significant obstacles when industrial production of SE is intended. Therefore,
The development of purification techniques that eliminate the need for purification solvents during SE purification is a pressing need in the industry. (Problems with the prior art) Therefore, purification methods that do not use organic solvents have been studied. For example, (1) SE precipitation method using an acidic aqueous solution (British Patent No. 809,815 (L959)
)) (2) A method of precipitation of SE using a general neutral salt aqueous solution (Japanese Patent Publication No. 42-8850) is known. (Margin below)

[Problem to be solved by the invention]

Therefore, the problem to be solved by the present invention is to solve the problem without using any solvent in the reaction process or the purification process.
By developing a technique to obtain high HLBSE in purified aqueous solution, all the problems caused by the use of reaction and purification solvents are solved. (Concept of the Invention) Therefore, the present inventor aimed to (a) minimize the amount of SE dissolved in the aqueous phase, (σ) avoid decomposition of unreacted sugars, and (c) purify high HLB SE. As a result of conducting many salting-out experiments with the goal of solving the following three points: recovering the neutral salt in an aqueous state, we found that when the neutral salt was dissolved in the aqueous solution of the reaction mixture, the neutral salt We found a favorable phenomenon in which not only a large proportion of SE precipitates under a combination of concentration and water amount, but also salts derived from the catalyst dissolve in the aqueous phase in addition to unreacted axes. . Then, after dissolving the precipitated SE in water again, the reprecipitation operation with an aqueous solution of a neutral salt is repeated, and after removing the remaining unreacted sugar contained in the SE, this By adding acidic water with an appropriate pH to the precipitate and stirring, the high H in the precipitate can be removed.
The LB content moves into the acidic aqueous phase, and the remaining precipitate contains low HL.
It was found that the B component remained. Incidentally, recovery of the high HLB-3H that migrated into the aqueous phase was impossible using conventional techniques, but as a result of research, the inventor found that such recovery could be done in the form of an aqueous solution by using an ultrafiltration membrane. We have discovered that this is industrially possible. In this way, it is possible to (1) remove impurities from the SE reaction mixture without using any organic solvents, (2) obtain a water-soluble SE with a high HLB, and further improve the SE.
It has become industrially possible to separate waste materials according to their uses. (Summary) The present invention is based on the above-mentioned discovery, and a reaction mixture containing the target sucrose fatty acid ester, unreacted sugar, unreacted fatty acid methyl ester, catalyst, soap, and fatty acid in a neutral region. The method is characterized by adjusting the pH to a pH of The summary is a method for purifying water-soluble high HLB sucrose fatty acid ester. (Skeleton of the Invention) Therefore, the present invention consists of the following steps. CI) Removal of impurities from the crude SE reaction mixture (
salting out process). (II) Step of washing impure SE precipitate (fractionation step). (]II) High HLB-3E recovery process (ultrafiltration process)
. Below, we will discuss various matters related to the invention. (Aqueous medium method SE synthesis reaction mixture) The method for producing SE by water medium method synthesis is a method in which sucrose is made into a molten mixture with fatty acid soap in the presence of water, and then reacted with higher fatty acid methyl ester in the presence of a catalyst. (Japanese Patent Publication No. 51-14485, etc.) Its characteristic is that the reaction mixture contains more soap than the mixture synthesized by the solvent method, but has the advantage that it does not contain any residual reaction solvent. be. The SE reaction mixture synthesized by the aqueous method generally has a composition in the following range. Sucrose fatty acid ester = 15-74% unreacted sugar
= 1.0-80% unreacted fatty liquor methyl ester - 0.5-10% neutral 1 derived from potassium carbonate
=0.05~7% soap -10
~50% fatty acids -0.5~10%
At this time, the ester distribution of SH is monoester 10~
75% (diester or higher is 90-25%). The fatty acid roots mainly contained in each of fatty acid methyl esters, soaps, and fatty acids are saturated and have a common CI
6~G2? It has a carbon number of (Addition of water) Next, water was added to the above reaction mixture, water: reaction mixture = 5:1 to 40:1 (weight ratio)... (1
), more preferably water:reaction mixture = 20:l (weight ratio) (2)
In addition to adding to the formula ratio, the pH is set to 6.2 to 6.2, preferably pH 7.5. In this case, the water addition ratio is outside the above range, e.g.
If the ratio of water to reaction mixture is less than 5, the resulting aqueous solution will have a high viscosity, making subsequent operations substantially difficult. Conversely, the quantitative ratio of water and reaction mixture is 40.
If too much water is added, the viscosity will be reduced and subsequent operations will be easier, but on the other hand, a large amount of energy will be required to remove the water when recovering unreacted sugar, etc. As a result, economic efficiency will be lost. Furthermore, the pH of the aqueous solution is preferably adjusted to between pH 2 and 8.2 in order to avoid decomposition of the target SH. At a hydrogen ion concentration of pH 6.2 or higher, quantitative There is a risk of SE decomposition occurring, and even in a weakly acidic range of pH 6.2 or lower, if exposed to high temperatures of 90°C or higher, for example, there is a risk of acid decomposition. (Salting out) If the pH is adjusted as described above, An aqueous solution of the SE reaction mixture was
Maintain the temperature at 50-80°C as much as possible and add neutral salt. The present inventors found that when an aqueous solution containing a precipitate of SE obtained by adding a neutral salt was heated to 50 to 80°C, the added neutral salt was converted into milk salt, acetate, common salt, or Glauber's salt. In any case, by setting the concentration of neutral salt to 6%,
We have discovered a phenomenon in which a large proportion of SE precipitates. This phenomenon is unique and has important value for the purpose of the invention. By cleverly utilizing this fact, ■ Total sucrose including unreacted sugar (total axis) ■ Salt derived from the catalyst ■ Added neutral salt moves to the aqueous phase, and the precipitated SE is cake (i.e.
This makes it possible to separate it from the slurry (sludge-like slurry). Table 1 shows this phenomenon in more detail. In the same table, the weight of SE dissolved in the aqueous phase M = Y [g] The weight of precipitated SH = X [g] The total SE (X + Y) [g] If the weight ratio of dissolved SH=φ [%], φ is defined by the following formula (3). At this time, the ester distribution in SE is monoester = 7
3%, diester or more = 27%. Table 1 Here, the following conditions: Temperature = 75°C, pH = 7.8, Water: 5E = 20: l (weight ratio) Fatty acid residue = Composition of stearic acid SH Sucrose fatty acid ester = 84% Unreacted Fatty acid methyl ester = 2% Soap = 2% Fatty acid = 1% Others = 1% Zero total salt = salt from catalyst + added neutral salt By determining the amount of dissolved neutral salt in this way, φ = By filtering or centrifuging the precipitated SE, sucrose, neutral salts, etc. dissolved in the aqueous phase can be removed. Can be removed. (Washing) In the salting-out step, a large proportion of SE precipitated from the aqueous reaction mixture solution by the addition of a neutral salt is in a water-containing state, that is, in the form of a slurry. This product contains impurities such as salts and sucrose, although in relatively small amounts. As a result of intensive research into a method for purifying this impure slurry, the inventor found that good results could be obtained by washing it with acidic water. That is, the impure SE slurry was adjusted to pH=3.0 to 5.5.
Impurities are eluted by washing with acidic water adjusted to . The acids used here are suitably mineral acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid and lactic acid, but are not limited to those listed separately as long as they are edible. Note that the temperature of the acidic water is suitably 10 to 40°C. By washing under such conditions, impurities desired to be removed from the cake side (sugar, added neutral salt, salt derived from the catalyst, etc.) can be transferred to the aqueous phase side. During the above cleaning operation, if the temperature of the acidic water exceeds 40℃, if the operation lasts for a long time, for example, several months,
Not only is there a concern about acid decomposition of SE, but the viscosity increases by 1, making operation difficult. On the other hand, maintaining a low temperature of 10° C. or less requires a refrigerator that is not economical. Therefore, it is generally preferable to operate at a temperature of 10 to 40°C, especially around room temperature. In addition, when washing the SE cake with this acidic water,
Only the unreacted sugar contained in this cake, the added neutral salt, and the salt by-produced by neutralization of the catalyst are SE.
It is desirable that the SE cake be shredded in the acidic water to the smallest possible particle size in order to liberate the particles of impurities that it contains, as they need to be removed from the cake. This purpose can be efficiently achieved, for example, by a fragmentation device such as a dispersion mixer (for example, manufactured by Tokushu Kiki Kogyo ■ (Homo Mixer)), a homogenizer, or a colloid mill (for example, under the trade name (Mycolloider)). The sugar, the salt derived from the catalyst, and the neutral salt are all transferred from the precipitated SH cake into the acidic aqueous phase. At this time, a remarkable phenomenon occurs in which high HLB-3E from the precipitate begins to dissolve into the acidic water side. This high HLB
The dissolution tendency of -SE in water changes depending on factors such as the temperature and pH of the system, but for example, when P)l is about 3.5 at room temperature, it is as shown in the attached Figure 1. Here, since high HLB-3E has high water solubility, it is tentatively named (water-soluble S E )) and is given a symbol of 'Y'. Y has a high HLB and therefore exhibits high water solubility. For this reason, it does not precipitate even in acidic aqueous solutions and normally dissolves in the solutions. In contrast, low HLI3-5E has low water solubility and therefore generally tends to precipitate at a certain acidity. Therefore, we tentatively name it (precipitability S E )) and give it the symbol X''. It is a triangular coordinate that represents the sum of 100%. In the figure, point M represents the composition of the original sample SE.
The points represent the composition of precipitated SE with low HLB SE. Point Y is a high HLB SE and represents the composition of water-soluble SE. The subscript 1.2.3 represents the different SEs of the ester distribution. For example, in the same figure, the ester distribution M2 (monoester - 73%, diester = 22%, triester = 5
If an aqueous solution of pH 3.5 is added to the SE sample with %) so that the SE concentration is 3%, uSE will be (X2) with the ester distribution (monoester = 88%, diester =
25%, triester = 7%);
Y2) Water-soluble S with an ester distribution (monoester = 84%, diester - 13%, triester - 3%)
It is shown that it is divided into E. Weights of x2 and Y2 to be divided, ie WN2 and WY2
From the properties of triangular coordinates, WN2 = TIX7 + VY2...""" (a) WY
2・72M2-Wx2・x2x2・・・・・・(b)(
However, Y2 M2 is the distance between point M2 and point Y2,
M2 is the distance between point X2 and point M2, WM24t M2
(r) - weight, WX2 is the weight of x2, VY2 is the weight of Y2, however, the weight is the value as a dry product) It is determined by solving the binary equations (a) and (b). Thus, SEs with a relatively high monoester content (i.e., SEs with high HLB) are more soluble in acidic water,
By cleverly utilizing the property that relatively low monoester SEs (i.e., low HLB SEs) tend to exist on the precipitation side, we can quantitatively divide SEs into high-HLB and low-HLB SEs. Can be divided. In addition, - the higher the monoester content in SE in the crotch meat, the more SE (
If the amount of 5E(Y) increases and vice versa, the amount of 5E(
A tendency for the amount of Y) to decrease was also discovered. Thus, the acidic aqueous solution obtained in the main washing step contains a relatively large amount of high HL]3-3E, and therefore has a low HLB SE.
Filter or centrifuge the precipitate SE, which mainly consists of SE. The obtained filtrate (or supernatant) contains, in addition to the high HLB SE, smaller amounts of salt, sucrose, etc., and therefore needs to be further purified. (Ultrafiltration) Therefore, the present inventors conducted intensive studies on means for removing small amounts of salt and sucrose contaminating the above-mentioned high HLB-3E-containing impure filtrate. I found it useful for this purpose. It is known that SEs coalesce with each other under certain conditions in an aqueous solution to form an aggregate of high molecular weight micelle structures (see p. 102 of the above publication). By the way, regarding the types of SE, monoesters, diesters, and triesters are those in which 1 to 3 fatty acid residues are bonded to each of the oxygen atoms of the three primary hydroxyl groups of the sucrose molecule. It's called ester. As is well known, although monoesters have greater hydrophilicity than diesters and triesters, the degree of micelle formation in water is small, resulting in relatively low molecular weight (small molecular diameter) SE micelle aggregates. form. On the other hand, diesters and triesters have relatively low phyllophilicity but have extremely high micelle-forming ability, so they form SE micelle aggregates with extremely large molecular weights (ie, large molecular diameters) in water. Commercially available SEs are rarely produced as a single monoester, and are usually produced as a mixed composition with a monoester content of, for example, 70%, 50%, or 30%·φ·. The present inventors have found that, for example, SE with a high monoester content of 70% creates SE aggregates with lower molecular weight than SH with a low monoester content of 50%, so that the aggregate size increases accordingly. Small microscopic diameter and therefore monoester content of 50% for ultrafiltration membranes with constant pore size
Therefore, it is undesirable that it tends to pass through the membrane together with unreacted sugars and by-product salts from the catalyst (salts obtained by neutralizing the catalyst with acid). I learned that I have a tendency. Therefore, as a countermeasure to this problem, the present inventors have proposed that when it is desired to remove unreacted sugars, catalyst-derived salts, etc. from impure SE with a high monoester content,
It is better to select a filtration membrane (with small pore size), and
On the contrary, in the case of SH having a low monoester content, it has been found that it is convenient to select a filtration membrane with a high molecular weight cutoff (that is, a large pore size) in order to speed up the processing speed. In addition, the inventors believe that among the substances contained in the reaction mixture, unreacted fatty acid methyl ester, soap, and fatty acid kings exist in a state encapsulated in the micelle structure aggregate of SE, so that SE It has also been confirmed from many experimental results that it is virtually impossible to separate these kings by means of filtration. From many experiments, we can conclude that ultrafiltration membranes (with an appropriate molecular weight cutoff) using pressure as a driving source
The impurities that can pass through the water together with the water are sucrose containing unreacted sugar, salts derived from the catalyst, and added neutral salts; Substances that cannot pass through include SE, unreacted fatty acid methyl ester, soap, and free fatty acids. This process cleverly utilizes these facts and selects an ultrafiltration membrane with an appropriate molecular weight cutoff to convert unreacted sugars and catalyst-derived salts into SE and unreacted fatty acid methyl esters. , to separate and remove soap and fatty acids from their surroundings. (Molecular weight of the substance to be filtered) In order to select an ultrafiltration membrane with an appropriate molecular weight cutoff, it is necessary to know the approximate molecular weight of the substance to be filtered. The molecular weights of these single substances relevant to the invention are as follows. ○ Citrus sugar = 342 0 Fatty acid methyl ester of water reaction Stearic acid methyl ester = 280 0 When using hydrochloric acid generated by neutralization of catalyst CK2C03) → Lactobutyric potassium = 128 When using acetic acid → Potassium acetate = 88 0 Medium -56.5 03E (as a monomer that does not form micelle aggregates) Cibosugar monostearate -600 Cibosugar distearate -858 Sucrose tristearate) = 11160 Sodium soap stearate; 288 Stearic acid Potassium = 314 0 Fatty acid stearic acid = 276 0 Water - 18 By the way, the appearance of the SE micellar structure aggregate is the molecular weight (
The following (referred to as (SE micelle aggregate - f amount)) is assumed as follows. Since SE in an actual aqueous solution forms a micelle aggregate in water, for example, if the number of SE micelles is 10, the molecular weight of the micelle aggregate is 100% of the monoester.
As % ◇ Molecular weight of monoester monomer (600) x 10 = e
,oo. Assuming 100% diester, ◇Molecular weight of diester monomer (850)XIO=6.
580 triester As 100%, ◇triester molecular weight (1,116)XIO=11,
Since 160 ml of SE is a mixture of monoester, diester, and triester, it is better to define the average molecular weight as the molecular weight of the SE micelle aggregate. (Molecular weight cutoff of ultrafiltration membrane) A membrane suitable for the purpose of the invention is selected as follows. First, with a filtration membrane with a molecular weight cutoff of 200, even if the reaction mixture in the aqueous solution state is supplied to the water membrane under pressure to remove the salts generated from the unreacted side and the catalyst (K2CO3), it will not reach its limit. What can be separated by the filtration membrane are water and catalyst (K2C
O3). Sucrose with a molecular weight of 342, which is larger than the molecular weight cutoff of 200, does not pass through the ultrafiltration membrane at all, so the unreacted side cannot be separated and removed by SE. Next, in the case of an ultrafiltration membrane with a molecular weight cutoff of 5,000,
Since the sucrose and the salt from the catalyst each have a molecular weight of less than 5.000, they can easily pass through the micropores of the ultrafiltration membrane. SE constitutes the above-mentioned micelle aggregate, and assuming that the number of micelle associations is, for example, IQ(P), the molecular weight of the SE micelle aggregate is estimated to be e, ooo or more, so the molecular weight cutoff of the filtration membrane is It is presumed that the micelle aggregate cannot pass through the micropores when the is larger than 5,000, and this assumption has been confirmed experimentally. The results were as expected. In this way, by appropriately selecting the molecular weight cutoff of the ultrafiltration membrane, it becomes possible to remove impurities including unreacted side from impure SE. (Conditions that the ultrafiltration membrane should have) The unreacted side contained in the SE reaction mixture and the catalyst (K2CO
When attempting to separate the salt by-produced from 3) from SE, unreacted fatty acid methyl ester, and four fatty acid groups, the ultrafiltration membrane should be used under suitable conditions. If it has a molecular weight cut-off: ■ It must be resistant to physical external forces. ■ Must be heat resistant and not decomposed by microorganisms. ■ Appropriate molecular weight cutoff and large processing capacity. ■ Long service life. ■ Availability of economical pricing offers. etc. Since there have been significant advances in technology in the production of ultrafiltration membranes in recent years, there are commercially available products that meet the above conditions. (Ultrafiltration conditions) The aqueous solution containing water-soluble (Y) obtained in the previous step is neutralized by adding an alkali prior to the main ultrafiltration, and the liquid is adjusted to pH 6.
Adjust the pH to 2 to 8.2, preferably around 7.5. When the pH of the neutralizing solution exceeds 8.2, SE decomposition progresses,
Furthermore, if the pH is less than 6.2, it becomes difficult to form SE micelles, which is undesirable as SE may come out of the ultrafiltration membrane or clog the pores. The temperature of the aqueous solution during filtration is preferably 80° C. or lower, regardless of the type of fatty acid methyl ester; if it exceeds the same temperature, there is a concern that SE will decompose. The inventors have found that maximum filtration rates are obtained when the temperature is particularly within the temperature range of 40-60<0>C. In other words, the overtemperature is 4
When adjusted to 0 to 60°C, preferably about 50°C, unreacted sugars, salts from the catalyst (K2CO3), and added neutral salts pass through the filter membrane most efficiently together with water, for reasons described below. The reason for this is that at 40 to 60°C, the molecules of SE micelle aggregates become gigantic, resulting in a decrease in the total number of micelle aggregates, and substances that are not originally involved in the formation of micelle aggregates, such as unreacted sugars, are This is thought to be due to the fact that it becomes difficult to resist the SH resistance, making it easier for unreacted sugars, etc. to pass through. It is known that an aqueous SE solution generally exhibits its maximum viscosity between 40 and 60°C (Page 103 of the IH publication), which suggests that it can have its maximum molecular weight within that temperature range. This fact also explains why unreacted sugars etc. show the maximum passing rate in the range of 40 to eo'c. Thus, the reaction mixture aqueous solution containing SE maintained at 40-60°C was pumped at 1-20 Kg/cm2G.
Pressure is applied as a driving source to pH 6.2~
It is brought into contact with an ultrafiltration membrane in a hydrogen ion concentration range of 8.2. As a filtration membrane, a cellulose-based membrane is not only physically weak but also easily attacked by microorganisms, so it is not very desirable for practical purposes. Practically preferred is PQ made of polysulfonic acid or polyvinylidene fluoride reinforced with a support layer. Both of these types of filtration membranes are currently commercially available, and have excellent heat resistance, tolerance, and alkali resistance, are resistant to external physical forces, and, moreover, microorganisms do not grow on the membrane surface. As mentioned above, when determining the molecular weight cutoff of a filtration membrane, S
Unreacted sugars, etc. are efficiently separated without leaking E.
It is also important to select one that has a filtration rate within the same range. As a result of study, the inventors found that the molecular weight cut-off of the membrane was 1. A filtration membrane with a molecular weight cut off of 5,000 is most preferable because it is preferably within the range of 000 to 100,000, and in particular, it does not leak SE and is suitable for processing on an industrial scale. I discovered that. Membranes with a molecular weight cut-off of more than 5,000 cause SH leakage, albeit slightly, while membranes with a molecular weight cut-off of less than 5,000 reduce the filtration rate. However, in either case, it does not bring about such a disadvantage that it is not industrially profitable. Among currently commercially available filtration membranes, one suitable for the purpose of the invention is, for example, the product name ((TERP-E-5>>(Polyvinylidene fluoride) ), <<TERP-HF-10))
(Polysulfone-based) and <<TERP-) IF-10
0>> (polysulfone type), etc. Through the above ultrafiltration treatment, impurities such as sucrose and salts are removed from the pickling solution of the salting-out precipitate, resulting in high purity, high HLB.
-3E (Y) is usually recovered in the form of a 5-15% aqueous solution. The monoester content of this high HLB-3E(Y) is such that, for example, in the example shown in the attached Figure 1, the crude SE, which initially had a monoester content of 73%, is changed to a high HLB-3E(Y) with a monoester content of 84% by pickling. 5E and monoester content 68
% low HLB-3E. Such high HL
B-3E was previously thought to be impossible to produce industrially.

[Effect]

After adding acid to the sucrose fatty acid ester production reaction mixture containing unreacted sugar, unreacted fatty acid methyl ester, catalyst, soap, and fatty acid to be synthesized using the aqueous medium method and adjusting the pH to a neutral range, water, neutral When the solution is salted out at an appropriate temperature, sucrose fatty acid ester, unreacted fatty acid methyl ester, soap, and fatty acid are precipitated, and a large proportion of SE can be recovered as a precipitated phase. Next, this precipitate is washed with acidic water, and the washing liquid is ultrafiltered to remove contaminating sucrose in the precipitate that has migrated into the washing liquid, added neutral salts, and by-products due to neutralization of the catalyst. A highly purified aqueous solution of HLB-3E from which impurities such as I and the like are removed is obtained. In this way, it becomes possible to purify an aqueous SE having a high HLB value without using a negative solvent.

【Example】

Hereinafter, embodiments of the invention will be specifically explained using Examples, but each example is of course for illustrative purposes and has no direct relation to the technical scope of the invention. After neutralizing the filtration medium method SE reaction mixture with lactic acid as shown in Table 2 below, add 2.000 kg of water to 100 kg of dried dry matter.
g was added and dissolved. 100 kg of salt was added to this aqueous solution, heated to 80°C, the precipitated cake was filtered, and the solid content was 45°C.
Got % cake. Table-2 Table-3 This ester distribution: 65% monoester, 35% diester or higher. To the above cake, add room temperature hydrochloric acid water (pH 3,8) 2,00
When 0 kg was added, SE was immediately precipitated as a white precipitate. Then, an acidic aqueous solution (p) 13.8) containing this precipitate
After thoroughly stirring the mixture using a homomixer (described above), the precipitate was collected by filtration. This precipitate was washed twice by adding aqueous acetic acid and adjusted to p) 17.5 with caustic soda. The precipitate contained 32% solids, and the dried material was It had the composition shown in Table 3. (Left below) On the other hand, the amount of filtrate produced when the precipitate was washed with acidic water amounted to about 6,000 kg by the above operation. The solid content contained in this B, 000 kg of filtrate is shown in Table 4 below.
It was as follows. Table 4 6,000 kg of this filtrate was adjusted to pi (7.5) and an ultrafiltration membrane manufactured by Toshi Engineering ■
5>> (molecular weight cut off 5,000) was sent to a spiral type (4" x 1 m) cylindrical pressure filtration unit with a membrane area of 80 m' under the following conditions: Temperature = 48°C to 50°C, filtration. Ejection rate from the membrane = 35-45 (kg / min), circulation rate of the filtration membrane = 200-220 (kg / min), after about 145 minutes, 170 kg of concentrated solution was added to 5820 K of water
After stirring, the solution was sent to the ultrafiltration membrane again under the same conditions. As a result of repeating this operation four times, the composition of the concentrated liquid (dry state) was as shown in Table 5 below. Table 5 In this way, in the ester distribution in the initial reaction mixture, monoester Contains i85.0% (diester or more 35
%) increased to monoester content 79.0%,
The SE showed a correspondingly high HLB value.

【Effect of the invention】

As explained below, the present invention enables the production of a purified water-soluble sucrose fatty acid ester with a high HLB without using any solvent from a sucrose fatty acid ester reaction mixture using an aqueous medium method. It has the following great effects. (1) Sucrose fatty acid ester can be purified using only inexpensive water. (2) There is no need to worry about solvent explosion or fire, and therefore there is no need for expensive explosion-proof electrical equipment. (3) There is no concern that the reaction solvent or purification solvent will mix into the product. (4) Improving the sanitary environment in the workplace. (5) It can be industrialized at low cost. (Margin below)

[Brief explanation of the drawing]

FIG. 1 is a ternary graph showing the relationship between the ester composition of SH and its solubility in intoxicants.

Claims (1)

[Claims] 1. In addition to the target sucrose fatty acid ester, unreacted sugar,
The aqueous sucrose fatty acid ester synthesis reaction mixture containing unreacted fatty acid methyl ester, catalyst, soap, and fatty acid is adjusted to a pH in the neutral range, and the resulting precipitate is acidified by adding water and neutral salts. A purification method comprising washing with water and bringing the washing liquid into contact with an ultrafiltration membrane to recover a water-soluble high HLB sucrose fatty acid ester. 2 The composition of the reaction mixture is: Unreacted sucrose = 1.0-80.0% Unreacted fatty acid methyl ester = 0.5-10.0% Catalyst = 0.05-7.0% Soap = 0. The method according to claim 1, wherein the fatty acid content is 5 to 60.0% and fatty acid = 0.5 to 10.0%. 3. The method according to claim 1, wherein the reaction mixture is adjusted to a pH of 6.2 to 8.2. 4. The method according to claim 1, wherein the reaction mixture after pH adjustment is heated to 50-80°C. 5. The method according to claim 1, wherein the weight ratio of water added to the reaction mixture and the reaction mixture is water:reaction mixture = 5:1 to 40:1. 6 The acid used to adjust the pH of the reaction mixture is lactic acid,
4. The method according to claim 1, wherein the acid is any acid selected from the group consisting of acetic acid, hydrochloric acid and sulfuric acid. 7 The fatty acid radical mainly contained in each of the fatty acid methyl ester, soap, and fatty acid in the reaction mixture has a carbon number of 1.
3. A method according to claim 1 or 2, having from 6 to 22 common saturated fatty acid roots. 8. The method according to claim 1 or 6, wherein the neutral salt added to the reaction mixture is any salt selected from the group consisting of common salt, mirabilite, potassium lactate, and potassium acetate. 9 Ester distribution of sucrose fatty acid ester is 10 to 75% as monoester content (diester or more is 80%
25%). 10. The method according to claim 1, wherein the acidic water has a pH value of 3.0 to 5.5. 11. Claim 1, wherein the temperature of the acidic water is 10 to 40°C.
or the method described in 10. 12. The method according to claim 1, wherein the ultrafiltration membrane is made of a polysulfone-based or polyvinylidene fluoride-based resin. 13 The molecular weight cutoff of the ultrafiltration membrane is 1,000-100
13. The method of claim 12, wherein the amount is 0.000. 14 The pressure as a driving source during ultrafiltration is 1.0 to 2.
The method according to claim 1, wherein the amount is 0.0 kg/cmG. 15 The pH of the reaction mixture aqueous solution during ultrafiltration is 6.2
8.2. 16 The temperature of the reaction mixture aqueous solution during ultrafiltration is 40~
The method according to claim 1 or 15, wherein the temperature is 60°C.