JPH0259593A - Purification of sucrose fatty acid ester - Google Patents

Abstract

PURPOSE:To recover the subject ester in high efficiency using exclusively water without using a purification solvent by adjusting a reaction mixture containing unreacted sugar, etc., to neutral state and forming a precipitate by the addition of water and a neutral salt. CONSTITUTION:Sucrose is recovered by adjusting the pH of (A) a reaction mixture to neutral state, adding (B) water and (C) a neutral salt to the mixture, adding water to the resultant precipitate to form an aqueous solution, subjecting the solution to ultrafiltration and contacting the aqueous layer free from the precipitate with a reverse osmosis membrane. The component A is preferably composed of (i) 1.0-80.0% of unreacted sucrose, (ii) 0.5-10.0% of unreacted fatty acid methyl ester, (iii) 0.05-7.0% of catalyst, (iv) 1.0-10.0% of soap, (v) 0.5-10.0% of fatty acid, (vi) 3.0-30.0% of volatile component and (vii) 15.0-95.0% of sucrose fatty acid ester wherein the main fatty acid radicals of the components (ii), (iv) and (v) have common saturated fatty acid radicals having 16-22C atoms and the component (vi) is dimethyl sulfoxide.

Description

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

The present invention mainly relates to an industrial purification method of sucrose fatty acid ester. More specifically, the present invention relates to a technique for industrially refining high-quality sucrose fatty acid ester and recovering unreacted sugar in the reaction mixture without using an organic solvent for purification.

[Conventional technology]

(Background) Currently, sucrose fatty acid esters (
Hereafter (abbreviated as S E >>), industrially, 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 a molten mixture of sucrose and fatty acid soap using ice 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 synthetic methods, in addition to the target SE, the reaction mixture contains unreacted sugar, unreacted fatty acid methyl ester, residual catalyst, soap, M
Contains impurities such as free fatty acids and volatile matter, and among these impurities, impurities whose content exceeds the specified amount must be removed before becoming a product.In particular, among the above impurities, the former Removal of residual solvent (volatile matter) associated with the solvent method of
This is extremely important as regulations have become stricter in recent years (1). Note) According to the US FDA standards, the allowable residual dimethyl sulfoxide during SE is 2 ppm or less (Fed
, Regjst, , 51(214), 40180-1
). Furthermore, another important problem in the industrial production of SH is the problem of recovering unreacted sugar. That is, as is well known,
The reaction rate of sucrose during SE synthesis is low, and does not reach 50% even in the dimethylformamide method (see page 35 of Sugar Ester Story (1984), published by the applicant company), so unreacted sucrose is not recovered. This industry will not survive. Therefore, large amounts of organic solvents have conventionally been used for the dual purpose of removing residual reaction solvent from crude SE and recovering unreacted sugars, but the heavy use of such solvents has hindered the industrial production of SE. , resulting in significant disadvantages such as: ■ Risk of explosion or fire. ■ Explosion-proofing of electrical equipment in preparation for ■ above. ■ Seal the manufacturing equipment in preparation for the above ■. ■ The entire building will be made into a fire-resistant structure in preparation for ■ above. ■ Increase in fixed costs due to ■, ■, and ■ above. ■ Increased cost due to solvent wastage. ■ Negative effects due to residual solvent remaining in product SE. (Φ An increase in fixed costs due to an increase in the number of shifts to prevent negative effects on employees' health. For this reason, the use of organic solvents during SE refining and sugar recovery is unnecessary. The development of this technology has been a pressing need in the industry. (Problems with the conventional technology) Therefore, purification methods that do not use organic solvents have been studied for some time, and some representative examples include: (1) #-based aqueous solution Method for precipitation of SH by (British patent 80
9,815 (1859)) (2) A method of precipitation of SE in a general neutral salt aqueous solution (Japanese Patent Publication No. 42-8850) is known. However, when an aqueous hydrochloric acid solution is added to the reaction mixture as in method (1), SE is immediately precipitated, but unreacted sucrose is easily decomposed and converted into glucose and fructose, and even at low temperatures ( Even if the reaction is carried out at a temperature of 0 to 5°C, decomposition cannot be avoided, making it difficult to recover and reuse unreacted sugar. Furthermore, even if an aqueous solution of a neutral salt such as common salt or mirabilite is added to the reaction mixture as in method (2), SE will immediately precipitate. In this case, decomposition of unreacted reactants does not occur, but the monoester, which is a useful component in SE, is dissolved in the aqueous phase, which not only causes a large loss but also increases the It becomes a hindrance when you want to get SE. Furthermore, according to the more recent Japanese Patent Application Laid-Open No. 51-29417, a mixed solution of water and a "purified solvent" (especially called that to distinguish it from a reaction solvent) is formed into a light liquid layer (upper layer) and a heavy liquid layer (lower layer).
The property of phase separation is utilized. That is, since the heavy liquid layer (lower layer) generally contains a large amount of water, hydrophilic unreacted sugars, catalyst-derived salts, etc. are dissolved in this heavy liquid layer (lower layer). On the other hand, since the light liquid layer (upper layer) contains a large amount of purified solvent, substances with low polarity such as SE, fatty acids, and unreacted fatty acid methyl esters are dissolved in this light liquid layer. However, reaction solvents such as dimethyl sulfoxide dissolve in the lower heavy liquid layer, but unfortunately they also dissolve in the upper light liquid layer, so it is impossible to completely separate the reaction solvent using this method alone. It is. Therefore, a very large amount of purified solvent is required just to remove a small amount of reaction solvent. In this way, in order to make it possible to industrially produce crude SE using water, it is essential to develop a purification method that completely removes the solvent and does not cause loss of sugar or product SE. becomes. (Principle of the Invention) As described above, in order to make the purification of crude SH using wood and the recovery of unreacted sugar industrially possible, it is necessary to completely remove the reaction solvent and the purification solvent, and to reduce the loss of sugar and product SE. The main premise is to develop a purification method that does not cause this. However, when purifying the reaction mixture based on this principle, S
Since the basic method is to utilize the solubility difference between E and unreacted sucrose, it is inevitable that a large amount of unreacted sugar will migrate to the water side, and without refining and recovering this dissolved sugar, the wood industry will not be able to do so. This method is economically and socially unviable, and therefore, an important issue of the invention is how effectively to recover the sugar that has migrated to the aqueous phase during purification.

[Problem to be solved by the invention]

Therefore, the problem to be solved by the present invention is to develop a technique for industrially obtaining purified SE without using a purification solvent, and to efficiently remove unreacted sugars from the reaction mixture. The objective is to solve the problems caused by the use of purified solvents by developing means for their recovery.

[Means to solve the problem]

[Contents] a: History of the invention b: @Required C: Skeleton of the invention d: Synthesis of SE by solvent method e: Hydration f: Salting out g: Reverse osmosis h: Ultrafiltration (a History of the invention) Therefore, the present invention By (a) minimizing SE stars dissolved in the aqueous phase, (a) avoiding decomposition of unreacted sugars, and (c) dissolving the remaining reaction solvent outside the aqueous phase, Separate from SE. (=) As a result of conducting many salting-out experiments with the goal of efficiently recovering unreacted sugars in the filtrate (or supernatant) from which the above precipitate was separated, we found that neutral salts were reacted with When dissolved in an aqueous solution of the mixture under a suitable pH combination of temperature, neutral salt concentration and water amount, in many cases not only almost the entire amount of SE precipitates, but surprisingly, the water We have discovered a convenient phenomenon in which the reaction solvent dissolves outside the unreacted sugar moieties in the phase. Therefore, take advantage of this phenomenon. After dissolving the precipitated SE in water again, the precipitation operation with a neutral salt aqueous solution is repeated to completely remove the remaining volatile components (residual reaction solvent) into the aqueous phase while minimizing the loss of SH. The unreacted sugar in the SE reaction mixture can be efficiently recovered in a purified state by contacting the residual liquid after removing the upper precipitate with a suitable reverse osmosis membrane. (b Overview) The present invention is based on the above discovery, and includes a reaction mixture containing, in addition to the target sucrose fatty acid ester, unreacted sugar, unreacted fatty acid methyl ester, catalyst 1 soap, fatty acid, and volatile matter. Adjust the pH to a neutral range, add water and a neutral salt, filter out the precipitate, add water, dissolve the precipitate, ultrafiltrate the aqueous solution, and remove the precipitate from the water. The gist of the present invention is a method for purifying sucrose fatty acid ester, which is characterized by recovering silica by bringing the phase side into contact with a reverse osmosis membrane. (Skeleton of the Invention C) Therefore, the present invention consists of the following steps. (1) Removal of impurities from the crude SE reaction mixture (
salting out process). (H) Concentrate unreacted sucrose in the crude SE reaction mixture 1
Recovery process (reverse osmosis process). (m) Purification step (ultrafiltration step) of impure SE. Various matters related to the first invention will be discussed below. (d Synthesis of SH by solvent method) Usually in the synthesis of SE by solvent method. A mixture of sucrose and fatty acid methyl ester is added and dissolved in a reaction solvent, such as dimethyl sulfoxide, in an amount several times the total amount of these, and potassium carbonate (KzC03) is added.
In the presence of alkaline catalyst of '8, vacuum 20-30To
By holding at 80 to 90°C for several hours near rr,
An SE reaction mixture is easily produced with a reaction rate of 80% or more (based on fatty acid methyl ester). Next, in order to eliminate the activity of the alkaline catalyst in the SE reaction mixture, an equivalent amount of an organic acid such as lactic acid or acetic acid or a mineral acid such as TM acid or sulfuric acid is added to the SE reaction composition. This neutralization converts the catalyst into a potassium salt such as potassium lactate. Finally, the reaction solvent, such as dimethyl sulfoxide, is distilled off under vacuum, resulting in a composition (reaction mixture after neutralization and distillation) approximately having the following composition range. Sucrose fatty acid ester = 15-74% unreacted sugar
= 1.0-80% unreacted fatty acid methyl ester = 0.5-10% neutral salt derived from potassium carbonate
= O, OS~7% soap =1.
0-10% fatty ribs = 0.5-10
% volatile content (residual reaction solvent) = 0.3-30% At this time, the ester distribution of SE is monoester 10-75%
(Diester or higher is 90-25z). The fatty acid roots mainly contained in each of fatty acid methyl ester, 6-brass, and fatty acid are saturated and have a common carbon number of CI6 to C22. (e Addition of water) Next, water was added to the above reaction mixture, water: reaction mixture = 5:l to 40:l (weight ratio)... (1
), more preferably, water:reaction mixture = 20:1 (weight ratio)... (2) and the pH is adjusted to 8.2 to 8. 2. The pH is preferably 7.5. In this case, the water addition ratio is outside the above range. For example, 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. On the other hand, if too much water is added so that the ratio of water to reaction mixture exceeds 40, the viscosity will decrease and subsequent operations will be easier, and the desired reaction solvent will be Although removal is carried out suitably, on the other hand, a large amount of energy cost is required to remove water when recovering unreacted sugars, etc., resulting in a loss of economic efficiency. Furthermore, in order to avoid decomposition of the target SE, the aqueous solution is preferably adjusted between p) 18.2 and 8.2,
Under hydrogen ion concentrations of pH 8.2 or higher, there is a risk of quantitative decomposition of SH due to alkali;
Even in the weakly acidic range of 8.2 or less, there is a risk of acid decomposition when exposed to high temperatures of, for example, 90° C. or higher. (f Salting out) The aqueous solution of the SE reaction mixture prepared as described above is maintained at 50 to 80° C., and a neutral salt is further added thereto. Based on the results of numerous experiments, the present inventors found that when an aqueous solution containing precipitated SE obtained by adding a neutral salt is heated to 50 to 80°C, SE elutes into the aqueous phase. The amount of volatile matter (residual reaction solvent) contained in the reaction mixture can be kept to a minimum even if the M1 ratio of the volatile matter (residual reaction solvent) is 3.0 to 30.
We found that most of the SE precipitates even when it varies significantly from 0%. This phenomenon in which SE precipitates and volatile components migrate to the aqueous phase only by the addition of a neutral salt is a unique phenomenon, and the purpose of the invention is to remove volatile components from the reaction mixture without using water. Therefore, it has important significance. Now, 11 of SE dissolved in the ice phase side = Y [gl Weight of precipitated SE = X [gl Total SE E (X + Y)
[g], and the weight ratio of SH dissolved in the aqueous phase = φ[1], then φ is defined by the following formula (3). Here, the following sample reaction mixture (dry matter) was dissolved in 20 times the amount (weight ratio) of water (pH 7,8) and heated to 75°C to determine the fatty acid residue; SE in the stearic acid sample. ii (dry matter) l.6 Sucrose fatty acid ester = 94% (Ester distribution: monoester = 73%, diester or higher = 27%) Unreacted fatty acid methyl 6 ester -25 Stone hydroxide 2% Fatty acid = 1% Others = 1% When neutral salt is added to this at various concentrations, the added salt becomes table salt,
When using nitric acid, potassium lactate, or potassium acetate, the results shown in Table 1 below are generally obtained. (Left below) Table 1: Total salt = salt derived from catalyst + added neutral salt As is clear from the above table, the value of φ decreases as the amount of total salt increases, but 3.5% If it exceeds 7.0, the decreasing trend will be gradual.
It can be seen that this value does not become smaller even if it increases to 5% or more. The above tendency is based on the fact that the amount ratio of volatile components (residual reaction solvent) contained in the initial reaction mixture is 3.0 to 30.0%.
It was also confirmed that even if there was a drastic change, there would be almost no effect. In other words, in such a ternary SE-water monosalt system, even if the amount of volatile matter changes significantly and the type of neutral salt added changes, the value of φ depends only on the total salt concentration. It is decided. The reason for this is not yet clear, but it is certain that mH is intertwined with the degree of formation of SE micelles and the so-called salting-out effect exerted by salt. The degree of the above salting-out effect, in other words, the value of φ is 5E(
7) Although it varies somewhat depending on the ester distribution and the type of fatty acid residue in the SE, the tendency that the minimum value of φ does not decrease even when the total base amount exceeds 6% (84% water) is the same. Conversely, if the amount is less than 6% (94% water),
The value of φ increases. undesirable as it increases the dissolution loss of SE, therefore φ
In order to reduce the value of , the dissolution loss of SH to the aqueous layer side can be minimized by keeping the salting at 6% (34% water) or less. (g reverse osmosis) << g-1 overview) Next, the by-product salt from the sucrose and catalyst (K2 GO3) separated into water and J(separated from the SE synthesis reaction mixture by the above salting process) and the salt Selectively separates only sucrose from an aqueous solution containing neutral salts and volatile components added for analysis.
Recovery is an important condition for achieving the purpose of the invention. However, the inventors have found that the use of reverse osmosis is particularly effective for this purpose. If a reverse osmosis membrane with a molecular weight cutoff in the range of 150 to 200 is selected, unreacted sugars (molecules 1342) and SE (molecular weight 600 or more) that flowed to the filtrate during the salting out process in the previous stage will be It is expected that both of them should be filtered out without any problem. On the other hand, if the molecular weight cutoff of the membrane is smaller than 150 to 200,
By-product salt 1 from the catalyst, for example potassium lactate (molecule 112
8), added neutral salts and volatile components, such as dimethyl sulfoxide (molecular weight 78), will pass through the fine pores of the reverse osmosis membrane without any problem. As a result of many experiments based on this estimation, we found that the sucrose that had undergone the previous salting-out treatment, the by-product salt from the catalyst, the neutral salts and volatile components added during salting-out, and
In some cases, an aqueous solution containing a small to trace amount of SE may be heated to a temperature of 40°C.
When brought into contact with a reverse osmosis membrane with a molecular weight cut-off of around 150-200 at ~60°C under a pressure greater than that during ultrafiltration as a driving source, by-product salts from the catalyst,
The added neutral salts and volatile components can easily pass through the fine pores of the reverse osmosis membrane along with water.This reverse osmosis operation removes impure sucrose aqueous solution (in some cases, a small amount of SE) is separated from low molecular weight substances such as water, by-product salts from the catalyst, neutral salts added during salting out, and volatile components, and is in the form of a concentrated raw sugar aqueous solution. Then, the obtained raw sugar aqueous solution is dissolved in fresh water again,
By subjecting it to the same reverse osmosis treatment again (or again and again),
A more pure cibosugar aqueous solution can be obtained. In the above, the temperature of the aqueous solution to be treated that is supplied to the reverse osmosis membrane is important in order to expect good results.If the temperature drops below 40℃, the treatment capacity will drop significantly, so it is not practical. It is preferable to select a temperature of 40° C. or higher; however, if the temperature exceeds 60° C., problems with the heat resistance of the reverse osmosis membrane will occur, so it is wise to perform the treatment at a temperature below the upper limit temperature. In addition, the pH of the L water distribution solution is also important in practice,
A pH in the range of 8.2 to 8.2 is preferable because it is less likely to affect the quality of sucrose. (g-2 Reverse Osmosis Membrane) A large number of industrial reverse osmosis membranes, which have been advanced in recent years, are commercially available from various companies. Among these membranes, crosslinked polyamide-based reverse osmosis membranes are examples of membranes that are excellent in durability, heat resistance, acid resistance, alkali resistance, bacteria resistance, and pressure resistance. As an example of this type of membrane, for example, reverse osmosis membrane manufactured by Toshi Engineering ■Hanuri, trade name <(SU-2)
00>) and the like have a value near the aforementioned molecular weight cutoff of 200, which satisfies the purpose of the present invention. Generally speaking, in the case of a reverse osmosis membrane with a molecular weight cut-off of around 200, the solute concentration in the supplied aqueous solution should be kept at an upper limit of 20%, preferably about 15% as an upper limit. It is possible to demonstrate a unique processing method. If the solute concentration exceeds 20%, it becomes difficult for water, by-product salts from the catalyst, and volatile matter to pass through the micropores of the reverse osmosis membrane, making it necessary to increase the driving pressure accordingly. , as a result, the membrane surface planting has to be widely used, and also,
It is extremely uneconomical as it requires a large amount of power. On the other hand, if the solute concentration is about 8 to 15%, industrial separation of sucrose is fully possible.
In the case of an aqueous solution with the composition of 2, the separation rate of sucrose is p) 1
7.5. Temperature 50℃, driving pressure 56.0kg/crn'G
(1') Tofi, effective area per l unit 8rn
''s reverse osmosis membrane <<5U-200>) reached the following values, and similar results were obtained with similar membranes from other companies. In all cases, dissolved SE could be recovered together with sucrose at a high yield. (Leaving space below) Table 2 In the above reverse osmosis treatment, the sucrose-containing aqueous solution from which by-product salts from the catalyst, added neutral salts, and the dominant volatile components have been sufficiently removed by one repetition of reverse osmosis membrane treatment is It is possible to maintain a sugar concentration of about 15 to 20%. Obtaining an aqueous sugar solution with a concentration of 20% or more is not only technically difficult, but also less economical. Therefore, if a sugar concentration higher than the above is desired, the sugar can be concentrated to the desired concentration, for example 50% or more, using a conventional concentrator 1, for example, a multi-vacuum can. (h Ultrafiltration) In the salting-out step, a large proportion of the 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 still contains impurities such as volatile matter, 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 ultrafiltrating it. S
It is well known that E coalesces with each other under certain conditions in an aqueous solution to form a micellar aggregate of polymeric particles (see 10, supra).
(See page 2). By the way, the type of SE is SE:! Those in which 1 to 3 fatty acid residues are bonded to any of the oxygen atoms of the three primary hydroxyl groups of a sugar molecule are called monoesters, diesters, and triesters, respectively. As is well known, although monoesters have greater wood-philicity than diesters and triesters, they have a lower degree of micelle formation in water, so they aggregate with relatively low molecular weight (small molecular diameter) SE micelles. form the body. On the other hand, diesters and triesters have relatively low hydrophilicity 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 not produced as a single monoester, but are usually produced as a mixed composition with a monoester content of, for example, 70%, 50%, 30%, etc. The present inventors have found that, for example, SE with a 70% higher monoester content creates SE aggregates with lower molecular weight than SE with a lower monoester content of 50%, so the Small microscopic diameter and therefore monoester content of 50% for ultrafiltration membranes with constant pore size
Therefore, it passes through the membrane together with unreacted sugars, by-product salts from the catalyst (salts obtained by neutralizing the catalyst with acid), volatile components, etc. I learned that it has an undesirable tendency to be easy to use. Therefore, the present inventors
As a countermeasure against this, if you want to remove unreacted sugars, catalyst-derived salts, volatile components, etc. from impure SE with a high monoester content, it is recommended to select a filtration membrane with a small molecular weight cutoff (i.e., a small pore size). In the case of SH with a low monoester content, we found that it is convenient to select a filtration membrane with a large molecular weight cutoff (i.e., a large pore size) to speed up the processing speed. . In addition, the inventors found that among the substances contained in one reaction mixture, unreacted fatty acid methyl ester, soap, and the king of fatty acids exist in a state encapsulated in the micelle structure aggregate of 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
Impurities that can pass through with water include unreacted sugars, salts derived from catalysts, added neutral salts, and volatile components (highly polar substances such as dimethyl sulfoxide and dimethyl formamide, which were used as solvents during SE synthesis). On the other hand, substances that are incorporated into high molecular weight micelles and cannot pass through the filtration membrane are SE, unreacted fatty acids. methyl ester,
These include soaps and free fatty acids. This process cleverly utilizes these facts and selects an ultrafiltration membrane with an appropriate molecular weight cutoff to eliminate unreacted sugars, catalyst-derived salts, and volatile components that are present in the two-salting precipitate. SE, separation of unreacted fatty acid methyl esters, soap and fatty acids from surroundings;
This is what we are trying to remove. (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 weight of these single substances related to the invention is , as follows. ○ Sucrose = 342 0 Unreacted fatty acid methyl ester Stearic acid methyl ester = 290 0 When using hydrochloric acid generated by neutralization of the catalyst (K2CO2) → Potassium lactate = 128 When using acetic acid → Potassium acetate = 98 0 Volatile Dimethyl sulfoxide = 78 Dimethyl formamide = 73 0 SE (as a monomer that does not form micelle aggregates) Sucrose monostearate = 600 Sucrose distearate = 858 Sucrose tristearate = 1118 0 Sodium soap stearate; 288 Stearic acid Potassium = 314 0 Fatty acid stearic acid = 276 0 Water = 18 By the way, the appearance of the micellar structure aggregate of SE is the molecule fi
Regarding t (hereinafter referred to as (molecular weight of SE micelle aggregate)), it is assumed as follows. Since SE in an actual aqueous solution forms a micelle aggregate in water, for example, when the number of SE micelles is 10, the molecular weight of the micelle aggregate is 100% of the monoester.
As a %. ◇ Monoester monomer molecule fa (eoo) x 10
=e,oo. As 100% diester ◇ Molecular weight of diester tJA polymer (850) XIO-8
,580 Triester 100% ◇Molecular weight of Triester (1,116)XIO=11,
180 Since an actual SE is a mixture of monoesters, diesters, and triesters, it is best to define the molecular weight of a micelle aggregate of SE as its homogeneous molecular weight. (Molecular weight cutoff of ultrafiltration membrane) Selection of a membrane suitable for the purpose of the invention is carried out as follows. First, in the case of a filtration membrane with a molecular weight cutoff of 200, even if the reaction mixture in an aqueous solution state is supplied to one membrane under pressure to remove salts and volatile components generated from unreacted sugars and the catalyst (K2CO2), The ultrafiltration membrane can only separate water, salts generated from the catalyst (K2 CO3), and volatile components with a molecular weight lower than the molecular weight of the ultrafiltration membrane, which has a molecular weight cutoff of 200. Since sucrose with a larger molecular weight of 342 does not pass through the ultrafiltration membrane at all, unreacted sugar cannot be separated and removed from the SE. Next, in the case of an ultrafiltration membrane with a molecular weight cut-off of 5,000,
Sucrose, salts from the catalyst and volatiles each have a molecular weight of 5.
,000, it can easily pass through the micropores of the ultrafiltration membrane. SE constitutes the above-mentioned passing micelle aggregate,
Assuming that the number of micelle associations is, for example, 10, the molecular weight of the SE micelle aggregate is estimated to be more than e,ooo, so if the molecular weight cutoff of the filtration membrane is greater than 5,000, the micelle aggregate will form micropores. It is presumed that it cannot pass, but
This assumption was confirmed experimentally. Separately, the case of a filtration membrane with a molecular weight cutoff of 1,000 was also investigated, and the results were as expected. In this way, by appropriately selecting the molecular weight cutoff of the ultrafiltration membrane, it is possible to remove impurities including unreacted sugars from impure SE. (Conditions that the ultrafiltration membrane should have) Unreacted sugar contained in the SE reaction mixture and catalyst (K2C
The king of the salt by-produced from O:l) and the volatile matter is SE,
When attempting to separate unreacted fatty acid methyl esters and fatty acids from the surrounding area, the ultrafiltration membrane must have the following conditions: If the membrane has an appropriate molecular weight cutoff, ■ Physical external force. be resistant to. ■ Must be heat resistant and not decomposed by microorganisms. ■ Appropriate molecular weight cutoff and large processing capacity. ■ Long service life. ■ Must be available at an economical price. etc. Since there have been significant advances in technology in the production of ultrafiltration membranes in recent years, there are commercially available membranes that meet the above conditions. (Actual ultrafiltration) When carrying out this step, water, preferably deionized water, is added to the precipitate generated in the salting out step described in E at a ratio of water/precipitate = 5 to 40.
(weight ratio), more preferably, water/precipitate = 20 (weight ratio), and after dissolving it, it is contacted with an ultrafiltration membrane. At this time, the pH of the aqueous solution should be approximately within the neutral range in the first neutralization step, but if for some reason the pH of the aqueous solution changes.
) If it is not within the range of I 8.2 to 8.2, adjust it to within the neutral range using an appropriate acid or alkali (p
) Below 16° and 2, the SE micelles aggregate becomes low-molecular and the loss due to leakage increases, and when the pH exceeds 6.2,
Hydrolysis of SE itself becomes more likely to proceed. ). The temperature of the aqueous solution during cancer treatment is preferably 80°C or lower, regardless of the type of fatty acid methyl ester; if the temperature exceeds the same temperature, there is a concern that SE will decompose. Nagisa et al. It has been found that maximum filtration rates are obtained when within the temperature range of 60°C. That is, when the filtration temperature is adjusted to 40-60°C, preferably about 50°C,
For the reasons described below, sucrose containing unreacted sugar, catalyst (K2C
By-product salts derived from O3), added neutral salts, and volatiles (dimethyl sulfoxide and dimethyl formamide) are surrounded by:
It passes through the filtration membrane most efficiently together with water. The reason for this is that in the temperature range of 40 to 60°C, the molecules of SE micelle aggregates become large, resulting in a decrease in the total number of micelle aggregates, which contributes to the formation of original micelle aggregates such as unreacted sugars. This is presumed to be due to the fact that the substances that do not react are less susceptible to the resistance of SH, and unreacted sugars and the like become easier to pass through. Incidentally, as is well known, SE aqueous solutions generally exhibit maximum viscosity between 40 and 80°C (see above, p. 03), which is because the micelle aggregates have the maximum molecular weight within that temperature range. This fact suggests that 40 to 8
It is possible to explain the reason why unreacted sugars etc. exhibit the maximum passing rate in the 0°C range. Thus, the reaction mixture aqueous solution containing SE maintained at 40-60°C was pumped at 1-20 Kg/c+s2.
Pressurize to G and apply pressure as a driving source, pH 8,
It is brought into contact with an ultrafiltration membrane in a hydrogen ion concentration range of 2 to 8.2. As a filtration membrane, cellulose-based membranes are not only physically weak, but also easily attacked by microorganisms.
Practically preferred membranes, which are less desirable in practice, are membranes made of polysulfone or polyvinylidene fluoride reinforced with a support layer. Both of these types of filtration membranes are currently commercially available, and one membrane not only has excellent heat resistance, acid resistance, and alkali resistance, but is also resistant to external physical forces, and does not allow microorganisms to grow on the membrane surface. . As mentioned above, when determining the fractional molecule-1 of the filtration membrane,
It is important to select a filter that can perform SE without leaking and has a high filtration rate. As a result of investigation, the inventors determined that the molecular weight cutoff for a membrane that satisfies the desired conditions of no leakage of SH, no loss of separation of unreacted sugars, by-product Jfl, and volatile components, and a high filtration rate. ,1,0
A molecular weight cut-off of 5,000 is preferable, and a molecular weight cut-off of 5,000 is preferable, and particularly, it does not leak SE and is suitable for processing on an industrial scale.
We have found that a filtration pattern of 1 is most preferable. 5,00
A membrane with a molecular weight cut-off of more than 0 will cause SH leakage, albeit slightly, while a membrane with a molecular weight cut-off of less than s, ooo will reduce the filtration rate. However, in either case, there are filtration membranes that are currently commercially available that do not bring about disadvantages that are unprofitable from an industrial standpoint, and that are suitable for the purpose of the invention. Among filtration membranes, product name ((TERP-E-5>)
(Polyvinylidene fluoride), ((TERP-HF-1
0>> (Polysulfone type) and (TERP-HF-
100)) (polysulfone type), etc. According to the above filtration membrane <<TERP-HF-10>> (ultrafiltration membrane with molecular weight cutoff = 10,000), 1. For example, when the composition of the aqueous solution is as shown in Table 3 below, the temperature is 50°C and the driving pressure is 5. The rate of separation of unreacted sugars when increased to .0 Kg/crn'G reached 4.7 Kg·sugar/hour with a critical slumber membrane (per 1 unit) having an effective area of 8 ml. This was an industrially sufficient separation rate, and the rate of separation of salts and volatile components by-produced from the catalyst was also sufficient. Incidentally, the removal rate of salts and volatile components from the unreacted side and the catalyst can be sufficiently increased by adjusting the number of times the liquid is passed through the filtration membrane. Table 3 (Set of reaction mixture and its aqueous solution J&) In this way, by using an ultrafiltration membrane, unreacted sugar, catalyst (K2 C03
), it is now possible to remove by-product salts and volatile components from the catalyst (K2 CO3) all at once together with water. The purpose of removing raw salt and volatiles is achieved. Through the above ultrafiltration process, high-purity SE from which impurities such as volatile matter, sucrose, and salts contained in the salting-out precipitate have been removed is usually recovered in the form of an aqueous solution with a solid content concentration of 1 to 10%. However, if the solid content exceeds 7%, the amount of water and impurities that permeate through the ultrafiltration membrane will decrease, so it is not preferable. Desirable for industrial operations. The thus purified SE in a water-containing state has a substantially slurry-like form, and can be concentrated to a solid concentration of about 10 to 40% using, for example, a vacuum C condenser, if necessary.

[Effect]

SE containing unreacted tongs, unreacted fatty acid methyl esters, catalyst 1 soap, fatty acids and volatiles (residual reaction solvent)
After adding acid to the resulting reaction mixture to adjust P)l in the neutral range, water and a neutral salt are added and salted out at an appropriate temperature, resulting in SE
, unreacted fatty acid methyl ester, soap, and fatty acid precipitate, unreacted sugars migrate into the aqueous phase, and volatile components (residual reaction solvent) also migrate into the aqueous phase, so no organic solvent is used at all. Residual volatiles and sugars can be removed without washing. Thus, by subjecting the aqueous phase to reverse osmosis treatment, unreacted sugar can be recovered as a highly purified sugar solution. After dissolving the above-mentioned salting-out precipitate in water, by subjecting it to an ultrafiltration step, the volatile matter contained in the main precipitate can be removed.
Impurities such as unreacted sugars, added neutral salts, and salts by-produced by neutralizing the catalyst are removed, resulting in a purified SE slurry.

【Example】

Hereinafter, embodiments of the invention will be specifically explained using Examples, but each example is of course for illustration only and has no direct relation to the technical scope of the invention. Example-1 The reaction solvent was distilled off from the solvent method SE reaction mixture represented by the composition shown in Table 4 below, and the residue was neutralized with lactic acid, and then 2,000 kg of water was added to 100 kg of the dried dry matter and dissolved. . Table 4 (blank below) Main ester distribution: 50% monoester, 50% diester or higher. l dimethyl sulfoxide (the same applies hereinafter). To this aqueous solution, 253 kg of 50% potassium lactate was added, heated to 75°C, heated to A temperature, and the precipitated cake (123.0 kg of balls, water 48.1%) was collected by filtration, and then heated under vacuum for 80°C. The M1 composition of the solid obtained by drying at °C was as shown in Table 5 below. Table 5: Heat the aqueous solution containing p) 17.7) to 55°C and use reverse osmosis II with a pump pressure of 80Kg/crn'G! 2 (<<Product Name<<5O-200>>; Molecular Weight Cutoff: 200) under the following conditions into two cylindrical reverse osmosis units (each 4"φ x 1 meter, cancer surface Mi8rn') equipped with Discharge rate of aqueous solution passing through the membrane = 4.8 to 8.2 cycles/min Circulation rate around the reverse osmosis membrane = 18 to 20 cycles/min Supply time =
The composition of the sugar and salt enriched liquid that was concentrated without passing through the membrane for about 6 hours is shown in Table 6 below. Table 6 The SE content in the filtrate filtered from the cake is
Gel filtration chromatography (GPC) method (cited above, 63)
(see page), the loss of SH is 1 of the initial amount.
．． It was 5%. Next, the salting-out filtrate (2,230 kg: remaining sucrose from which SE was precipitated by salting out, class 111, and volatile components) Next, 2000 kg of water was added to the aqueous solution shown in Table 6, and under conditions of approximately When treated with a reverse osmosis membrane, an aqueous solution with the composition shown in Table 7 below was obtained. As a result of treatment with a reverse osmosis membrane, an aqueous solution having the composition shown in Table 8 below was obtained. (Left below is the margin) Lactic acid potassium salting out cake of Example 1 (water content: 411.11;
The solid content composition is listed in Table 5 above) 123.0Kg
3,200 kg of wood was added to the mixture, the pH was adjusted to 7.7, and the mixture was stirred at a temperature of 55°C for about 1 hour to prepare an aqueous solution having a solute concentration of 2% as shown in Table 9 below. Table 9 About 14 hours after the start of liquid passage, the composition of the dissolved components in 1.003 kg of the concentrate that did not pass through the membrane was as shown in Table 10 below. Table 10 This aqueous solution was applied to the ultrafiltration membrane manufactured by Higashi Engineering ■Hanuri <<TERP-ES-5)) (molecular weight cut off 5
The liquid was sent to a spiral-shaped cylindrical pressure filtration unit (8 m2) equipped with 000) under the following conditions. Temperature: 54-55°C Pressure = 8.5-9.8 Kg/c + Discharge rate from 12G filtration membrane = 3.1-5.7 Kg/min Circulation rate at filtration membrane =
22.0 to 22.3 Kg/min [Effect of the invention] As explained above, the present invention provides the following advantages:
By making industrial purification possible without using a purification solvent and providing a means for recovering unreacted sugars in the reaction mixture, the following significant effects are achieved. (1) It becomes possible to purify SH using only inexpensive water. (2) There is no need to worry about solvent explosion or fire, so there is no need for an expensive explosion-proof ventilator. (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.

Claims (1)

[Claims] 1. In addition to the target sucrose fatty acid ester, unreacted sugar,
Adjusting the reaction mixture containing unreacted fatty acid methyl ester, catalyst, soap, fatty acid and volatiles to a pH in the neutral range,
The feature is that water is added to the precipitate generated by adding water and a neutral salt to form an aqueous solution, which is ultrafiltered, and the aqueous phase side from which the precipitate has been removed is brought into contact with a reverse osmosis membrane to recover sucrose. A method for purifying 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 = 1. 0 to 10.0% Fatty acid = 0.5 to 10.0% Volatile content (residual reaction solvent) = 3.0 to 30.0% Sucrose fatty acid ester = 15.0 to 95.0% The method described in 1. 3 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. 4. The method according to claim 1 or 2, wherein the volatile component (residual reaction solvent) in the reaction mixture is dimethyl sulfoxide or dimethylformamide. 5. The method according to claim 1, wherein the reaction mixture after pH adjustment is heated to 50-80°C. 6 The acid used to adjust the pH of the reaction mixture is lactic acid,
2. 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 weight ratio of the reaction mixture to the water added to it is 1
2. The method according to claim 1, wherein the ratio is 5 to 1:40. 8. The method according to claim 1, 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. The method according to claim 1, wherein the ultrafiltration membrane is made of a polysulfone-based or polyvinylidene fluoride-based resin. 10 The molecular weight cutoff of the ultrafiltration membrane is 1,000-100
,000. 11 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. 12 The pH of the reaction mixture aqueous solution during ultrafiltration is 6.2.
8.2. 13. The method according to claim 1, wherein the reverse osmosis membrane has a molecular weight cutoff of 150 to 200. 14. The method of claim 1, wherein the reverse osmosis is carried out within a temperature range of 40-60<0>C. 15. The method according to claim 1 or 15, wherein the reverse osmosis is carried out in a pH range of 6.2 to 8.2. 16. The method according to claim 1 or 14, wherein the reverse osmosis membrane is made of crosslinked polyamide plastic. 17 Sucrose concentration in the feed solution to the reverse osmosis membrane is 10 to 20
%.