JPH0253792A - Method for purifying sucrose ester of fatty acid - Google Patents

Abstract

PURPOSE:To enable purification simply by water without using a purifying solvent and reduce cost by regulating a reaction mixture to a pH within a neutral region, then adding water, a neutral salt and sucrose, then dissolving the formed precipitates in water and ultrafiltering the resultant solution. CONSTITUTION:A reaction mixture containing the objective sucrose ester of a fatty acid is regulated to a pH within a neutral region (preferably pH6.2-8.2) and water, a neutral salt and sucrose are then added to form precipitates, which are subsequently dissolved in water. The resultant solution is then ultrafiltered to purify the objective ester. Furthermore, the composition of the above- mentioned reaction mixture is 1.0-80.0% unreacted sucrose, 0.5-10.0% unreacted methyl ester of the fatty acid, 0.05-7.0% catalyst, 1.0-10.0% soap, 0.5-10.0% fatty acid, 3.0-60.0% volatiles and 15.0-95.0% sucrose ester of the fatty acid. The reaction mixture after regulation of the pH is preferably heated to 50-80 deg.C.

Description

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

The present invention relates to an industrial method for purifying sucrose fatty acid ester. More specifically, the present invention relates to a technique for industrially refining crude sucrose fatty acid ester into high-quality sucrose fatty acid ester without using an organic solvent for purification.

[Conventional technology]

(Background) Today, sucrose fatty acid esters (
(hereinafter abbreviated as << S E >) is industrially produced by combining sucrose and higher fatty acid methyl esters of 08 to 022 in a solvent (
(dimethylformamide, dimethyl sulfoxide, etc.) under an appropriate catalyst (solvent method, Japanese Patent Publication No. 1973-
13102) or by using water without using a solvent to form a molten mixture of sucrose and fatty acid 6% 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 is obtained by However, in both of these two synthetic methods, in addition to the desired SH, unreacted sugars and
Contains impurities such as unreacted fatty acid methyl ester, residual catalyst, soap, free fatty acids, and volatile matter, and any impurities that exceed the specified amount must be removed before becoming a product. Of the above-mentioned impurities, the removal of residual solvent (volatile matter) associated with the solvent method is particularly important, as regulations have become stricter in recent years. Note) According to the US FDA standards, the allowable residual dimethyl sulfoxide during SE is 2 ppm or less (Fed
,Regist,, 51(214), 40180-1
). Therefore, large amounts of organic solvents have traditionally been used for the purpose of "removing the residual reaction solvent from crude SE," but the heavy use of such solvents has the following significant disadvantages for the industrial production of SH. bring profit. ■ 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 SH. ■ An increase in fixed costs due to an increase in the number of shifts required to prevent negative health effects on employees. Under these circumstances, there has been a pressing need in the industry to develop a technology that eliminates the need for the use of organic solvents during SE purification. (Problems of the Prior Art) Therefore, purification methods that do not use organic solvents have been studied for a long time.For example, (1) a precipitation method of SE using an aqueous solution (British Patent No. 809,815 (+95
9)) (2) A method of precipitation of SE using a general neutral salt aqueous solution (Japanese Patent Publication No. 1988-8850) 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, unreacted sugars do not decompose, 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. According to the more recent Japanese Patent Publication No. 51-2!3417,
The property that a mixed solution of water and a "refined solvent" (especially referred to as such to distinguish it from a reaction solvent) separates into a light liquid layer (upper layer) and a heavy liquid layer (lower layer) is utilized. In other words, generally a heavy liquid The layer (lower layer) contains a lot of water, so
Hydrophilic unreacted sugars, catalyst-derived salts, etc. are dissolved in this heavy liquid layer (lower layer). On the other hand, the light liquid layer (upper layer) contains a large amount of purified solvent. Less polar substances such as SE, fatty acids, and unreacted fatty acid methyl esters dissolve 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 for the purpose of removing trace amounts of reaction solvent. Thus, in order to make purification of crude SE using water industrially possible, it is essential to develop a purification method that completely removes the solvent and does not cause loss of sugar or product SH. (Principle of the Invention) As described above, in order to make purification of crude SE with water industrially possible, it is necessary to completely remove the solvent and to make the product S
The major premise is to develop a purification method that does not cause loss of H.

[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 solvent for producing J#. The objective is to solve all the dark problems caused by the use of purified solvents. [Means for solving the problem] [Contents] a: Background of the invention b: a Essential C: Skeleton of the invention d: Synthesis of SH by solvent method e: Hydration f: Salting out g: Ultrafiltration (a) Background) Therefore, the present inventors aimed to (a) not only minimize the amount of SE dissolved in the aqueous phase side, but also reduce the amount to zero if possible to precipitate the entire amount of SE, and (α) reduce the amount of unreacted sugar. As a result of many salting-out experiments aimed at solving the three problems of avoiding decomposition and (c) separating the residual reaction solvent from SE by dissolving it outside the aqueous phase, we found that sucrose and When the neutral salt is dissolved in the aqueous solution of the reaction mixture, under the appropriate combination of PI3 temperature, neutral salt and sucrose concentration, and water amount, not only will substantially all of the SE precipitate;
Surprisingly, we discovered a convenient phenomenon in which the reaction solvent was dissolved in areas other than unreacted axes in the aqueous phase. Therefore, by taking advantage of this phenomenon and repeating the precipitation operation with a neutral salt and sucrose aqueous solution after dissolving the precipitated SE in water, the remaining volatile matter ( The remaining reaction solvent) can be completely transferred into the aqueous phase, and SE can be industrially produced in a purified state by redissolving the SE slurry precipitated above in water and ultrafiltering it. became clear. (b Overview) The present invention is based on the above discovery, and includes a reaction mixture containing unreacted sugars, unreacted fatty acid methyl esters, catalysts, soaps, fatty acids, and volatile components in addition to the target cibosugar fatty acid ester. The gist is a method for purifying sucrose fatty acid ester, which is characterized by adjusting p)I in the neutral range, neutralizing the precipitate produced by adding water, a neutral salt, and sucrose, and ultrafiltering the precipitate. . (Skeleton of the Invention C) Therefore, the present invention consists of the following steps. (I) Removal of impurities from the crude SE reaction mixture (
salting out process). (II) Impure SH purification step (ultrafiltration step). Below, we will discuss various matters related to the invention. (d. Synthesis of SH by a solvent method) In the synthesis of SH by a solvent method, 1. Usually, a mixture of sucrose and fatty acid methyl ester is added to a reaction solvent 1, for example, dimethyl sulfoxide, in an amount several times the total amount of these. It can be easily reduced to 90% by dissolving it and keeping it at 80-80°C for several hours in a vacuum of around 20-30 Torr in the presence of an alkaline catalyst such as potassium carbonate (K2GO3).
An SE reaction mixture is produced at the above reaction rate (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 hydrochloric 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
= 0.05-7% soap =1.
0-10% fatty acid = 0.5-10
% volatile content (residual reaction solvent) = S, O ~ 30% At this time, the ester distribution of SH is monoester lO ~ 75%
(Diester or higher is 80 to 25z). The fatty acid roots mainly contained in each of fatty acid methyl ester, soap, and fatty acid are saturated and have a common carbon number of C+6 to C22. (e 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, the ratio is as follows. Water: Reaction mixture-20: l (weight ratio)...
(2) Add to the ratio of formula and adjust the pH to 6.2 to 8.2.
．． The pH is preferably 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 an excess of water is added to the extent that the reaction solvent is Removal of water during recovery of reactive sugars and the like requires a great deal of energy cost, resulting in loss of economic efficiency. Furthermore, the pH of the aqueous solution is preferably adjusted between p) 18.2 and 8.2 in order to avoid decomposition of the desired SH. At a hydrogen ion concentration of pH 8.2 or higher, the pH of the aqueous solution cannot be determined using an alkali. There is a concern that SE decomposition may occur, and even in a weakly acidic region of pH 8.2 or less, for example at 90°C.
Exposure to higher temperatures may cause acid decomposition. (f Salting out) The pH-adjusted aqueous solution of the SE reaction mixture as described in 1 below,
Maintain the temperature as much as possible at 50-80°C and add neutral salt and sucrose. In this case, the neutral salt to be added is first calculated by the following formula (
It is preferable that 3) is satisfied. = 0.015 to 0.12 (weight ratio)...
(3) Here, total amount of base = neutral salt to be added + amount of base formed from catalyst (4) Total amount of sugar = amount of sucrose to be added + Amount of unreacted sugar from the beginning...
・・・・・・・・・(5) Next, the amount of sucrose that should be added is:
It is preferable that it is determined by the following formula (6). = 0.025 to 0.20 (weight ratio)...
...(6) Furthermore, in addition to both of the above equations, it is preferable that the weight ratio of the total amount of hydrochloric acid to the total amount of sugar also satisfies the following equation (7). The present inventors obtained S
When an aqueous solution containing a H precipitate is heated to 50-80°C, even if the composition of volatiles (residual reaction solvent) contained in the SE reaction mixture varies greatly from 3.0 to 30.0%. It has been found that almost all of the SE is precipitated regardless of whether the neutral salt added is lactate, acetate, common salt or Glauber's salt. This phenomenon is a unique phenomenon that has not been known until now, and has important value for the purpose of the invention. By cleverly utilizing this fact, ■ Total sucrose (total sugar) including unreacted sugar ■ Volatiles ■ Salt derived from the catalyst ■ Surroundings of added neutral salts migrate to the aqueous phase and precipitate. SE cake (i.e.
This makes it possible to separate it from the slurry (sludge-like slurry). The attached FIG. 1 is a ternary graph showing this phenomenon in more detail. In this figure, the weight of SE dissolved in the aqueous phase - Y [gl, the weight of precipitated SE = X [g] The total SE (X + Y) [gl] 2-2 ratio of SE = φ [%], φ is defined by the following formula (8). Here, the following conditions: Temperature = 80°C, PH-7,5 Water: Reaction mixture = 7.4: 1 (weight ratio) Fatty acid residue = Stearic acid Composition of the reaction mixture = la Fatty m ester = 29% unreacted sugar
= 35% Unreacted fatty acid methyl ester = 2% Salt derived from catalyst = 1% Soap = 3% Fatty acid = 1% Volatile matter (residual reaction solvent) = 29% Ester distribution in SE: Monoester = 73% or more diester =27%, how the value of φ changes is shown by triangular coordinates. Here, the total salt is the amount defined by formula (4), and the total sugar is the amount defined by formula (5). It is expressed as water amount, total base amount, total sugar amount - 100%. The shaded part in Figure 1 is the formula (3) discovered by the inventors.
), equation (6), and equation (7) at the same time. By determining the amount of dissolved neutral salt and sucrose that falls within this shaded area, it is possible to precipitate substantially φ→0, that is, approximately the entire amount of SE, and the precipitated SE can be collected by filtration. Or, by centrifugation, volatiles dissolved in the aqueous phase (
(residual reaction mixture) and molecule i (ie, completely removing contaminating volatile components). (The following is a blank space) (g Ultrafiltration) In the salting-out step, the SE precipitated approximately in its entirety from the aqueous reaction mixture solution by the addition of neutral salts and sucrose is in a water-containing state, that is, in a slurry ( It is in the form of a slurry. Although this is a relatively small amount, it still contains impurities such as volatile matter, salts, and sucrose.As a result of intensive research into the purification method of this impure slurry, the inventor found that it can be purified by ultrafiltration. It was found that good results could be obtained. 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, so SE micelles of relatively low molecular weight (small molecular diameter) aggregate. 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. In reprint SE, the monoester is not produced as a single product, but is usually produced as a mixed composition with a monoester content of, for example, 70%, 50%, 30%, etc. The present inventors found that, for example, SE with a high monoester content of 70% creates SE aggregates with lower molecular weight than SE with a low monoester content of 50%, so the Small microscopic diameter and therefore monoester content of 50% for ultrafiltration membranes with constant pore size
Therefore, it easily passes through the membrane together with unreacted sugars, by-products from the catalyst (catalysts are neutralized with acid to form salts), volatile components, etc. I learned that this has an undesirable tendency. 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). We found that, in the case of SE with a low monoester content, it is convenient to select a filtration membrane with a high molecular weight cutoff (i.e., a large pore size) 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, stone cake, 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 SE from its champions 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 sucrose containing unreacted sugars, salts derived from catalysts, added neutral salts, and volatile components (such as dimethyl sulfoxide and dimethyl formamide, S
A substance that is highly polar, highly water-soluble, and has a high affinity for sucrose, which was used as a solvent during the synthesis of E. Substances that cannot pass through include SE, unreacted fatty acid methyl esters, soaps, and 'Mra fatty acids. This process skillfully utilizes these facts and selects an ultrafiltration membrane with an appropriate molecular weight cutoff to remove unreacted sugars, catalyst-derived salts, and volatile components that are present in the salting-out precipitate. The purpose is to separate and remove SE, unreacted fatty acid methyl ester, soap, and fatty acids from the 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. ○ Sucrose = 342 0 Unreacted fatty acid methyl ester Stearic acid methyl ester = 280 0 When using hydrochloric acid generated by neutralization of catalyst (K2CO3) → Potassium lactate; 128 When using acetic acid → Potassium acetate = 98 0 Volatile Dimethyl sulfoxide = 78 Dimethyl formamide = 73 0SE (as a monomer that does not form micelle aggregates) Sucrose monostearate = 600 Sucrose distearate) = 858 Sucrose tristearate = 1118 0 Sodium soap stearate = 288 Stearin Potassium acid = 314 0 fatty acid stearic acid; 276 0 water = 18 By the way, the appearance of the aggregate of the SE micelle structure is the molecular weight (
(hereinafter referred to as the molecular weight of the SE micelle aggregate) is assumed as follows. Since SE in an actual aqueous solution forms a micelle aggregate in water, for example, when the number of micelle associations of SE is 10, the molecular weight of the micelle aggregate is monoester 10.
Assuming 0%, ◇ Molecule of monoester monomer fi (eoo) x 10
=8,000 Assuming 100% diester ◇Molecular weight of diester monomer (850)XIO-8,5
As 80 triester 100% ◇triester monomolecule-1(1,118)XIO-11
, 160 Since actual 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 an aqueous solution state is supplied to the ice membrane under pressure to remove salts and volatile components generated from unreacted sugars and the catalyst (K2CO3), The ultrafiltration membrane can separate water with a molecular weight lower than the molecular weight cutoff of 200 of the ultrafiltration membrane,
Sucrose with a molecular weight of 342, which is larger than the 0 cut-off molecular weight of 200, which is only the salt and volatile components generated from the catalyst (K2CO3), does not pass through the ultrafiltration membrane at all, so unreacted sugar cannot be separated and removed from the SE. Next, in the case of an ultrafiltration membrane with a molecular weight cutoff 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 8,000 or more, so if the molecular weight cutoff of the filtration membrane is greater than 5,000, the micelle aggregate will form micropores. It is assumed that it is impassable, and this assumption has been confirmed experimentally. Separately, we also investigated the case of a filtration membrane with a molecular weight cutoff of 1,000, 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 (K2CO
The salt by-produced from 2) and the volatile matter are treated as SE, soap,
When attempting to separate unreacted fatty acid methyl ester and fatty acid, the conditions that the ultrafiltration membrane must meet are as follows:
If several molecules have an appropriate molecular weight cut-off, ■ they should 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. ■ 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. (Experiment of ultrafiltration) When carrying out this step, water, preferably deionized water, is added to the precipitate generated in the above-mentioned salting out step, and water/precipitate = 5 to 4
0 (weight ratio), more preferably, water/precipitate = 20 (weight ratio). 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 H6.2 to 8.2, adjust it to within the neutral range using an appropriate acid or alkali (pH
If the pH is less than 6.2, the micelle aggregate of SE becomes low-molecular and loss due to leakage increases, and if the pH exceeds 8.2, hydrolysis of the SE itself tends to proceed. ). 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. 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 to 60°C, preferably about 50°C,
For the reasons described below, sucrose containing unreacted sugar, catalyst (K2CO
2) By-product salts derived from the filter, added neutral salts, and volatile components (dimethyl sulfoxide and dimethyl formamide) pass 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 gigantic, resulting in a decrease in the total number of micelle aggregates.
This is presumed to be due to the fact that substances that are not originally involved in the formation of micelle aggregates, such as unreacted sugars, are less susceptible to SH resistance, making it easier for unreacted sugars to pass through. Incidentally, as is well known, an SE aqueous solution generally exhibits its maximum viscosity between 40 and 60°C (see above, p. 103), which means that the micelle aggregate can have its maximum molecular weight within that temperature range. This fact suggests that 40 to 80℃
It is possible to explain the reason why unreacted sugars etc. show the maximum passing rate in the range of . Thus, the reaction mixture aqueous solution containing SE maintained at 40-60°C was pumped at 1-20 Kg/c+m2.
Pressurize to G and apply pressure as a driving source, pH 8.2
Contact with the ultrafiltration membrane in the hydrogen ion concentration range of ~8.2. Cellulose-based membranes are not only physically weak but also easily attacked by microorganisms, so they are not very desirable for practical purposes.Polysulfone reinforced with a support layer is preferable for practical purposes. or polyvinylidene fluoride. Both of these types of filtration membranes are currently commercially available, and the ice membrane is not only heat resistant, acid resistant, and alkali resistant, but also resistant to physical external forces and does not allow microorganisms to grow on the membrane surface. do not have. As mentioned above, when determining the molecular weight cutoff of a filtration membrane, S
Unreacted sugars, etc. are efficiently separated without H leakage,
It is important to select a product that also has a high filtration rate. As a result of investigation, the inventors found that there is no leakage of SH and the separation of unreacted sugars, by-product salts, and volatile components is not impaired. ,
Moreover, it is preferable that the molecular weight cutoff of the membrane is within the range of 1,000 to 100,000, which satisfies the cold condition of high filtration rate, and that there is no leakage of SH, and that it is suitable for industrial use. It has been discovered that a filtration membrane with a molecular fraction i of 5,000 is most suitable for processing on a large scale. If the molecular weight cut-off exceeds 5,000, SE leakage occurs, albeit slightly;
For membranes with a molecular weight cut-off of less than 100%, cancer hyperactivity is reduced. However, in either case, it does not bring about such a disadvantage that it is not industrially profitable. Among the currently reprinted filtration membranes, one suitable for the purpose of the invention is, for example, the ultrafiltration membrane sold by Toshi Engineering ■, which has the trade name <<TERP-E-5>> (polyvinylidene fluoride). ,((TERP-OF-10>>
(Polysulfone type) and <<TERP-) IF-100
>> (Polysulfone type) etc. According to the above filtration membrane ((TERP-HF-10>> (ultrafiltration membrane with molecular weight cutoff=10.000), p) l=
7.5, when the composition in the aqueous solution is as shown in Table 1 below, the temperature is 50
℃, and the driving pressure was increased to 5.0 Kg/crn'G, the separation rate of unreacted sugar was determined by the ultrafiltration membrane (with an effective area of 8 m').
(per unit), 4.7 Kgφ sugar/sugar amount time 7
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 unreacted sugars, salts and volatile components from the catalyst can be sufficiently increased by adjusting the number of times the liquid is passed through the filtration membrane. In this way, by using an ultrafiltration membrane, unreacted sugars, catalyst (K
It is now possible to remove the by-product salts and volatile components from K2CO2) together with water, and in this way, unreacted sugars and catalysts can be removed using only wood and without using any solvents.
The objective of removing by-product salts and volatiles from 3) is achieved. Through the above ultrafiltration process, impurities such as volatile matter, sucrose, and salts are removed from the aqueous solution of the salting-out precipitate.
E can usually be recovered in the form of an aqueous solution with a solids concentration of 1 to 10%, but if the solids content exceeds 7%, the limit I
I! This is not very preferable because the amount of water and impurities that permeate through the membrane decreases, and in practical terms, a solids concentration in the range of 4 to 6% is preferable for industrial operations. The SE in the rootstock state is approximately slurry-like, and can be concentrated to a solid concentration of about 10 to 40% using, for example, a vacuum compressor, if necessary.

[Effect]

After adding acid to the SE generation reaction mixture containing unreacted sugar, unreacted fatty acid methyl ester catalyst, stone age, fatty acid, and volatile matter (residual reaction solvent) to adjust the pH to a neutral range, water, neutral When salt and sucrose are added and salted out at an appropriate temperature, SE, unreacted fatty acid methyl ester, stone grains, and fatty acids precipitate, and the volatile components (remaining reaction solvent) migrate to the aqueous phase. , residual volatiles can be removed without using any organic solvents. In particular, equation (3), equation (6
) and formula (7), the residual solvent can be removed with virtually no loss of SE. Then, after dissolving the salting-out precipitate described in -h in ice, the limit of 11! By subjecting it to the distillation process, impurities such as volatile matter included in the main precipitation, unreacted sugar, added neutral salts, and salts produced by neutralization of the catalyst are removed, and the purified SE is Since it becomes a slurry, it becomes possible to industrially produce purified sugar fatty acid ester without using any refining solvent.

【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. (Leaving space below) "Souji Konren" After distilling off the reaction solvent from the solvent method SE reaction mixture represented by the composition shown in Table 2 below, the residual liquid was neutralized with lactic acid, and then 100 kg of dried dry matter and 1,000 kg of water were added. was added and dissolved. (Margins below) Table 2: Ester distribution Dimonoester 70%, diester or more 30%. Herbal dimethyl sulfoxide (hereinafter the same). To this aqueous solution, 982.5 kg of salt and 97.6 kg of 50% potassium lactate were added, heated to 75°C, and the precipitated cake (weight 80 kg, moisture 45%) was filtered out, and then heated to 80° C. under vacuum. When the composition of the solid obtained by drying at ℃ was investigated, it was as shown in Table 3 below. Table 3 Table 4 In addition, when the SEI in the filtrate filtered from the cake was measured by gel filtration chromatography (GPC) method (see page B3 of the above publication), the presence of SE was not observed at all.
Moreover, 95% of the reaction solvent dimethyl sulfoxide was removed. Example-2 The solid content composition of the cake (weight eokg) filtered in Example-1 is as shown in Table-3. Water was added to this cake to prepare an aqueous solution having the composition shown in Table 4 below. Margin below C) After adjusting this aqueous solution to p) 17.3, heat it to 50 ° C.
Toshi Engineering ■ Sakasaki's ultrafiltration membrane (TERP
-ES-5>> (fractionated molecules 435,000) installation 2
The liquid was sent to a spiral type 4-inch cylindrical pressure filtration unit with a membrane surface of 18 mm under the following conditions. Liquid feeding pressure = 7.2 to 9.8 kg/c + s2G temperature =
51.2°C to 53.0°C Filtration membrane discharge rate = 2.1 to 4.6 (kg/min) Filtration membrane circulation rate = 20.5 to 23.2 (kg/min) 1
After 0 hours, the dissolved components of 580 kg of the obtained concentrated solution were analyzed and the results were as shown in Table 5 below. Table 5 Table 6 Example 3 580 kg of the concentrate obtained in Example 2 was added with 3.
000 kg was added and treated under substantially the same conditions as in the previous example, and a concentrated solution of M1 composition shown in Table 6 below was obtained. (Margin below)

【Effect of the invention】

As explained below, the present invention provides a means for industrially producing purified sucrose fatty acid ester from a solvent method reaction mixture without using a purification solvent. It has such great effects. (1) It becomes possible to purify SH using only inexpensive water. (2) There is no need to worry about solvent explosion or fire. There is no need for expensive explosion-proof electrical equipment. (3) There is no concern that the purification solvent will mix into the product. (4) Improving the sanitary environment at @ba. (5) It can be industrialized at low cost. 4 Figure + Simple explanation of rti 1'I] Figure 1 is a triangular graph showing the relationship between the changes in each stitch of water 1 total sugar and total salt and S E 4F dissolved in the aqueous phase. Figure 1 Patent applicant No.- Kogyo Seiyaku Co., Ltd. Total salt ('/,) 7 Total salt ◆ Total tf machine = 100

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,
1. A method for purifying sucrose fatty acid ester, which comprises dissolving a precipitate produced by adding water, a neutral salt, and sucrose in water, and then ultrafiltering the precipitate. 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. 2. The method according to claim 1, wherein: 0-10.0% fatty acid = 0.5-10.0% volatile content = 3.0-50.0% sucrose fatty acid ester = 15.0-95.0%. 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. Claim 1 or 3, wherein the neutral salt and sucrose are added to the aqueous solution of the reaction mixture after pH adjustment according to the following relationship:
Method described. Total salt amount/water amount + total salt amount + total sugar amount = 0.015 to 0
．． 12 and total sugar amount/water amount + total salt amount + total sugar amount = 0.025 to 0
．． 20 and total amount of salt/total amount of sugar = 0.4 to 0.8 where, total amount of salt = amount of neutral salt to be added + amount of salt produced by neutralization of catalyst Total amount of sugar = amount of SHORT to be added Amount of sugar + amount of unreacted sugar from the beginning 7 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. 8 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. 9. The method according to claim 1 or 2, wherein the volatile component (residual reaction solvent) in the reaction mixture is dimethyl sulfoxide or dimethylformamide. 10 The neutral salt added to the reaction mixture is common salt, mirabilite,
7. The method according to claim 1, wherein the salt is selected from the group consisting of potassium lactate and potassium acetate. 11. The method according to claim 1, wherein the ultrafiltration membrane is made of a polysulfone-based or polyvinylidene fluoride-based resin. 12 The molecular weight cutoff of the ultrafiltration membrane is 1,000-100
,000. 13 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. 14 The pH of the aqueous solution of the reaction mixture during ultrafiltration is 6.
2. The method according to claim 1, wherein the molecular weight is between 2 and 8.2. 15 The temperature of the aqueous solution of the reaction mixture during ultrafiltration is 40
15. The method according to claim 1 or 14, wherein the temperature is ~60C.