JPH0211594A - Purification of sucrose fatty ester - Google Patents

Abstract

PURPOSE:To improve purification efficiency of the subject ester without using a solvent by treating a mixture containing a sucrose fatty ester prepared by the aqueous solvent method with an acidic water, adding a neutral water to the resultant precipitate, carrying out separation by an ultrafiltration membrane, bringing the residual aqueous solution into contact with a reverse osmosis membrane for concentration. CONSTITUTION:To a reaction mixture containing unreacted sucrose, unreacted fatty methyl ester, catalyst, soap, fatty acid and sucrose fatty ester, an acidic aqueous solution of lactic acid, etc., with pH3.0-5.5 is added so that water/ reaction mixture is 5-40 (weight ratio). The resultant precipitate is dissolved in a neutral water with 6.2-8.2pH at 40-60 deg.C and forced to permeate through an ultrafiltration membrane with 1000-100000 differential molecular weight composed of a polysulfone-based resin, etc., under pressure to separate unreacted sucrose and salts produced from the catalyst. The residual aqueous solution is brought into contact with a reverse osmosis membrane with 60 differential molecular weight composed of a polyether-based resin under pressure, thus obtaining the objective ester concentrate.

Description

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

The present invention relates to a method for producing ta of sucrose fatty acid ester, and more specifically to a method for purifying crude sucrose fatty acid ester synthesized by an aqueous medium method using only water without using any solvent.

[Prior Art] (Background) Currently, sucrose fatty acid esters (
(hereinafter also abbreviated as IE)) is industrially known as sucrose and C8-C2
2 with higher fatty acid methyl ester in a solvent (dimethylformamide, dimethyl sulfoxide, etc.) under an appropriate catalyst (solvent method: Japanese Patent Publication No. 35-13102)
Alternatively, sucrose and fatty acid soap can be made into a molten mixture using water without using a solvent, and then reacted with higher fatty acid methyl ester in the presence of a catalyst (water medium method: Japanese Patent Publication No. 51-1
No. 4495). However, in either of these two synthetic methods, the reaction mixture contains
In addition to the target SH, unreacted sugar, unreacted fatty acid methyl ester, residual catalyst, soap, M! Contains impurities such as fatty acids, and among these impurities, impurities whose content exceeds the specified amount must be removed before becoming a product.In particular, among the above impurities, unreacted sugar must be removed. Removal is of paramount importance due to the large amount. (Problems with the Prior Art) By the way, as a means of removing unreacted sugar from the reaction mixture of SE, it is possible to add a solvent to the reaction mixture by taking advantage of the fact that ordinary solvents have almost no ability to dissolve sucrose. In addition,
Conventionally, a method of removing contaminating unreacted sugars as a precipitate has been commonly used. However, apart from small-scale factories, in factories involved in the production of SH on an industrial scale, there are inconveniences in handling solvents, such as the trouble of recovering solvents, the risk of fire, and occupational health issues for workers. There are things that stand out. However, since there are no other effective means, solvents are still used to remove unreacted sugars, as shown in, for example, Japanese Patent Publication No. 42-11588 and Japanese Patent Publication No. 48-10.
No. 448 specifies that solvents such as butyl alcohol, toluene, methyl ethyl ketone, ethyl acetate, etc. are effective for purification including removal of unreacted sugars. For reference, the disadvantages associated with handling solvents are listed below. ■ Risk of explosion or fire. ■ Explosion-proof 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 effect of residual solvent remaining in product SE. ■ An increase in fixed costs due to the negative impact on employees' health and the increase in shifts as a countermeasure.

[Problem to be solved by the invention]

Under these circumstances, there is a long-awaited development of a technology that can synthesize and purify SE completely solvent-free, that is, without using any solvent other than water during synthesis or purification. The problem to be solved by the present invention is to establish a technique for purifying SE without using any solvent.

[Means for Solving the Problems] ([Required) In order to solve the above problems, 1. Powdered SE according to the present invention
The purification method is based on unreacted Si! After treating the reaction mixture containing sugar, unreacted fatty acid methyl ester, catalyst 1 soap, fatty acid, etc. with acidic water and dissolving the resulting precipitate cake in neutral water. , the unreacted sucrose and the salt generated from the catalyst are separated by contacting with an ultrafiltration membrane by passing through the membrane together with water, and the remaining sucrose fatty acid ester, unreacted fatty acid methyl ester, and soap are separated. The present invention is characterized in that an aqueous solution containing the four fatty acids is brought into contact with a reverse osmosis membrane and concentrated. Below, important matters related to the invention will be described in detail in separate sections. (a Water-based method SE synthesis reaction mixture) In the synthesis of SE using the water-based method, sucrose methyl ester, fatty acids, and soap are usually heated together with water to form an emulsion, and then the water is distilled off under reduced pressure. Then, an alkali catalyst such as potassium carbonate is added, and the temperature is further increased and heated under reduced pressure to complete the reaction. The reaction mixture obtained here has approximately the following composition. Unreacted sucrose = 1-80% Unreacted fatty acid methyl ester = 0.5-10% Catalyst (K
2 as CO3) = 0.05-7% soap = 2-60
96 Fatty acid = 0.5 to 10% Sucrose fatty acid ester = 15 to 95% Potassium carbonate (KzCO3) is typical as a catalyst used in the above water-mediated SE synthesis. Catalyst 1 used for example, sodium carbonate or sodium alkoxide can also be used. The types of soaps and fatty acid residues of fatty acids need only correspond to the above-mentioned fatty acid methyl esters. (b. Precipitation of SE with acidic water) When carrying out this step, which is the first step of the invention, acidic water is added to the SE-containing reaction mixture of the water medium method at a ratio of water: reaction mixture = 5: l to 40: l. (!i weight standard,
More preferably, water:reaction mixture is added and dissolved in a ratio of 20:1 (based on weight). Since SE is easily hydrolyzed in alkaline conditions, to prevent hydrolysis, acidic water is quickly added to the reaction mixture to reduce the pl(
Adjust the rA to 3.0 to 5.5, preferably around pH 5.5. At this time, as the acid, organic acids such as lactic acid and acetic acid, and inorganic acids such as hydrochloric acid and sulfuric acid are used, but they are not limited to those exemplified on the side.
It is preferable that the temperature of the acidic water be controlled at about 10°C to 40°C. If the temperature of the acidic water exceeds 40°C, there is a risk of acid decomposition of the SE if the operation takes a long time, even over several months. Not only that, but the viscosity increases, making it difficult to operate. On the other hand, in order to maintain a low temperature of 10°C or less, it is necessary to install a refrigerator, which loses economic efficiency. Therefore, normally 10 above
It is preferable to operate within the range of .degree. C. to 40.degree. C., particularly around room temperature. By adding acidic water, some of the SE contained in one reaction mixture is eluted into the water phase, but most of the SE precipitates in the form of a cake. Dissolve in water, heat if necessary, and prepare an impure SE solution for the subsequent ultrafiltration step. In addition, when precipitating SE with one or more acidic waters, SE
Since it is necessary to remove contaminants in the cake, residual unreacted sugar, and salt by-produced by neutralization of the catalyst from the SE cake as much as possible, the target SE cake is It is desirable that the particles be finely divided into particles as small as possible.The purpose of this fine-graining is 1. This can be efficiently achieved using a fragmentation device such as Mycolloider, in which both the unreacted sugar and the salt derived from the catalyst are transferred from the precipitated SH cake into the acidic aqueous phase. In this case, it is unavoidable that some SE will elute into the acidic water phase, albeit in a substantially small amount. This is significant, so it can be effectively suppressed by relatively increasing the diester or triester content. (C ultrafiltration) (C-I M theory) SEs combine with each other under certain conditions in an aqueous solution. It is a well-known fact (Published by the applicant company (Sugar Ester Story), p. 102) that an aggregate of high-molecular-weight micelle structures is created by SE. There are various types of monoesters, such as monoesters, diesters, and triesters, in which one to three C8-C22 fatty acid residues are bonded to the oxygen atom of the hydroxyl group. Although they are larger than esters, the degree of micelle formation in water is small, so they form relatively low molecular weight (small molecular diameter) micelle aggregates.On the contrary, diesters and triesters In spite of its relatively low wood-philicity, it has extremely high micelle-forming ability, so it forms SE micelles with extremely large molecular weight (that is, large molecular diameter) in water.Commercially available SE is produced as a single monoester. It is commonly used that the monoester content is 1, for example 70% or 50%.
, 30%... As a result of repeated research aimed at solving the above problems, the present inventors found that, for example, SE with a high monoester content of 70%
Compared to SH, which has a low monoester content of 50%,
Since SE aggregates with a lower molecular weight are produced, the microscopic diameter of the aggregates is correspondingly smaller, and therefore, it passes through an ultrafiltration membrane with a fixed pore size than an SE with a monoester content of 50%. Therefore, it has an undesirable tendency to easily pass through the membrane together with unreacted sugars and by-product salts from the catalyst (formed when the catalyst is neutralized with acid). I learned. Therefore, as a countermeasure to this problem, the present inventors proposed that a filtration membrane with a small molecular weight cutoff (i.e., a small pore size) should be used to remove unreacted sugars, catalyst-derived salts, etc. from impure SE with a high monoester content. It is better to select SH with a low monoester content, and conversely
In this case, it has been found that it is convenient to select a filtration membrane with a large molecular weight cut-off (that is, a large pore size) in order to speed up the processing speed. In addition, one of the inventors said that among the substances contained in the reaction mixture, unreacted fatty acid methyl ester. As the kings of soap and fatty acids exist in a state encapsulated in the micellar structure aggregate of SE, it is virtually impossible to separate the kings of SE and these kings by filtration, as shown by many experimental results. Confirmed from. Thus, from many experimental results, the conclusion was that there are two types of impurities that can pass through a filtration membrane (with an appropriate molecular weight cutoff) together with water using pressure as a driving source: unreacted sugars and salts derived from catalysts. And on the other hand. Substances that are incorporated into the high molecular weight micelle aggregate and cannot pass through the filtration membrane include SE, unreacted fatty acid methyl ester, soap, and free fatty acids. The present inventor skillfully utilizes these facts and selects a filtration membrane with an appropriate molecular weight cutoff to eliminate the king of unreacted sugars and catalyst-derived salts in the SE reaction mixture. It was successfully separated and removed from fatty acid methyl ester, soap, and fatty acid. (c-2 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 the substance is as follows. O Sucrose = 342 0 Unreacted fatty acid methyl ester/stearic acid methyl ester = 2!300 Catalyst (K
When using salt/lactic acid generated by neutralizing zCO3) →
Potassium lactate = 128 When using acetic acid → Potassium acetate = 88 QSE (as a monomer that does not form micelle aggregates) Life sucrose monostearate = 800 Sucrose distearate) = 958 Sugar tristearate = 1118 Note that there is no significant difference in molecular weight of other fatty acid esters such as myristate, palmitate, arachinate, and behenate. ○Soap・Sodium stearate=298・Potassium stearate=314 0Fatty acid・Stearin m=278 0Water=18 By the way, the apparent molecular weight of the aggregate of SE micellar structure is
(hereinafter referred to as the molecular weight of the SE micelle aggregate) can be experimentally assumed as follows. 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 %. ◇Molecular weight (eoo) of monoester monomer x t. We, oo. As 100% diester. ◇Molecular weight of diester monomer (950) 110-8,5
80 tri, as 100% ester. ◇Triester molecular weight (1,118)XIO-11,
It becomes 180. Since the actual SE is a mixture of monoester, diester, and triester, the average molecular weight of the SE micelle aggregate may be defined as the molecular weight. (c-3il! Fractional molecules m of the membrane) Selection of a membrane suitable for the purpose of the invention is carried out as follows. First, for an ultrafiltration membrane with a molecular weight cut-off of 200, an aqueous solution is added to one membrane. Even if the reaction mixture is supplied under pressure to remove unreacted parts and salts generated from the catalyst (KzC(h)), the filtration membrane can only separate the salts with a molecular weight cutoff of 2.
Water with a molecular weight lower than 00, and sucrose with a molecular weight of 342, which is only the salt generated from the catalyst (KzC(h), with a molecular weight of 0 cutoff of 20G, do not pass through the filtration membrane at all.
Unreacted parts cannot be separated and removed by SE. Next, in the case of a filtration membrane with a molecular weight cutoff of 5,000. The salts from the catalysts each have a molecular weight of 5,000
Because it is smaller, it can easily pass through the micropores of the filtration membrane. S
E constitutes the above-mentioned micelle aggregate. Assuming that the number of micelles is 10, for example, the molecular weight of the SE micelle aggregate is estimated to be e,ooo or more. Therefore, if the molecular weight cutoff of the filtration membrane is greater than 5,000,
It is presumed that the micellar fruit aggregates cannot pass through the micropores, and this assumption has been experimentally confirmed. Finally, we also investigated the case of a filtration membrane with a molecular fraction Ik of 1,000, and the results were as expected. As described above, by appropriately selecting the molecular weight cutoff of the ultrafiltration membrane, impurities including unreacted parts in the SE reaction mixture can be removed. Conditions) SE, soap,
When attempting to separate unreacted fatty acid methyl ester and fatty acid, the filtration membrane must have an appropriate molecular weight cutoff. ■ 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. [Phase] Must be available at an economical price. etc. In recent years, there have been remarkable advances in the technology for producing ultrafiltration membranes, and as will be described later, some commercially available membranes can be found that satisfy the above conditions. (Actual practice of c-5 ultrafiltration) The composition of the reaction mixture suitable for carrying out this step is described by Ohie, S.K.
15% to 95%, unreacted portion 1% to 80%. Unreacted fatty acid methyl ester s%~10%, catalyst (K2COs) 0.05%~7%1 soap 2%~6o
%, and the fatty acid content is within the range of 0.5 to 10%. From the reaction mixture with this composition, unreacted parts and catalyst (K2
When attempting to remove by ultrafiltration the king of salts produced by the neutralization reaction between C84) and an acid, the fatty acid residues constituting the fatty acid methyl ester in the reaction mixture have a carbon number of Ca
It is preferable that the material is saturated between t and CN. 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 the maximum filtration rate can be obtained when the temperature is within the temperature range of O. That is, by adjusting the il! supertemperature to 40-80°C, optimally around 50°C, For reasons described below, unreacted sugar and catalyst (K2C
The king of salts derived from O3) passes through the filter membrane most efficiently together with water. The reason for this is that at 40-80°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 It is presumed that this is because it becomes difficult to resist the resistance of SH, making it easier for unreacted sugars and the like to pass through. As is known, an SE aqueous solution generally exhibits its maximum viscosity between 40 and θoC (see above, p. 103), which suggests that it can have its maximum molecular weight within that temperature range. , also from this fact. This can explain the reason why unreacted sugars etc. show the maximum passing rate in the range of 40 to 60°C. Thus, the aqueous reaction mixture solution containing SE maintained at 40 to BO°C was pumped to l −20 Kg/c+a2
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 in practical terms.Practical membranes that are suitable are polysulfone membranes reinforced with a support layer. Or a membrane made of polyvinylidene fluoride. Both types of filtration membranes are currently commercially available and have excellent heat resistance, acid resistance, and alkali resistance, are resistant to external physical forces, and do not allow microorganisms to 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 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 and by-product salts is not impaired. The molecular weight cutoff of the membrane that satisfies the desired condition of high filtration rate is preferably within the range of 1,000 to 100,000, and in particular, there is no leakage of SH, and it may be suitable for industrial use. It has been discovered that a filtration membrane with a molecular weight cut-off of 1 s, ooo is most preferable as one suitable for large-scale processing. 5. With molecular weight cut-offs exceeding Goo, SE leakage occurs, albeit slightly, and conversely, s, oo
o For unvortexed molecular weight cut-off membranes, i! ! Overspeed is reduced. However, in either case, it does not bring about such a disadvantage that it is not industrially profitable. Among currently commercially available filtration membranes, those suitable for the purpose of the invention include, for example, among the ultrafiltration membranes sold by Toshi Engineering ■, the product name (TERP-E-57) (polyvinylidene fluoride type); (TERP-HF-10)> (Polysulfone-based) and ((TERP-HF-100>
(polysulfone type), etc. The above filtration membrane (TERP-HF-10) (molecular weight cutoff = 1
0.000 ultrafiltration membrane), if the composition of the aqueous solution (pH-7.5) of the SE reaction mixture is as shown in Table-1 below, the temperature is 50°C and the driving pressure is 5.0 Kg/am''G. The rate of separation of unreacted sugars when increased reached 5.0 Kg-sugar/hour with an ultrafiltration membrane (1 unit/ton) with an effective area of 8 rn''. This is an industrially sufficient separation rate. Moreover, the rate of separation of the salt by-product from the catalyst was also sufficient. Incidentally, the removal rate of unreacted sugars and salts from the catalyst can be sufficiently increased by adjusting the number of times the liquid passes through the filtration membrane.
Water films are extremely advantageous for industrialization. Thus, by using an ultrafiltration membrane, unreacted sugars and catalyst (K2C) can be industrially and easily removed from the SE reaction mixture.
It is now possible to remove the king of by-product salts from O3) together with water, and in this way, unreacted sugars and by-product salts from the catalyst can be removed using only water (without using any solvent). The purpose is achieved. (d Reverse Osmosis) The residual liquid (SE, unreacted fatty acid methyl ester, unreacted fatty acid methyl ester, The composition of the aqueous solution (containing a preparative mixture of soap and fatty acids) is often in the range of approximately 1% to 4% solids and 98% to 88% water, therefore, as is, it is difficult to obtain a powdered SE. It is clear that the energy cost for dehydration is excessive. However, as a result of research, the present inventors have found that the use of reverse osmosis membranes enables extremely low-cost dehydration and concentration, and that the above problems can be solved industrially. The conditions that the reverse osmosis membrane used here must meet are: ■ It must allow only water to pass through from the aqueous solution after ultrafiltration. ■ Do not deteriorate due to bacterial growth. ■ Must be heat resistant and alkali resistant. ■ Excellent water removal ability ■ Long service life. As a result of research, the present inventors have found that polyether membranes in particular are reinforced with polysulfone supports. It has been found that a reverse osmosis membrane made of a so-called composite membrane and having a molecular weight cutoff of 60 is suitable. A commercially available product suitable for this purpose is, for example, PEC100O sold by Toshi Engineering. The above reverse osmosis membrane is preheated to a temperature of 40°C to 60°C. When an aqueous solution to be treated whose pH is adjusted to a pH range of 8.2 to 8.2 is brought into contact with the solution under pressure, effective dehydration can be carried out. At this time, if the pH is less than 8.1, SE will precipitate and block the pores of the reverse osmosis membrane, making it impossible for only water to pass through the pores. Conversely, if p)I exceeds 8.3, fatal SH hydrolysis will occur. It should not be made more alkaline than this. When the temperature drops below 40°C, the rate at which water molecules pass through the pores of the reverse osmosis membrane decreases rapidly. On the other hand, if the temperature exceeds 60°C, there is a concern that SH may be hydrolyzed, especially when subjected to long-term reverse osmosis, and this should also be avoided. Furthermore, these optimum operating conditions of 40°C to 60°C also
Similar to the ultrafiltration temperature described above, this is a condition discovered by the present inventors. The pressure as a driving source is industrially preferably 50 kg.
/ce2G -95kg/cm2G There is. Under these conditions, the approximate water removal rate is 0 per meter of reverse osmosis membrane.
．． 0B to 0.8 kg water/min, which is a large value on an industrial scale. Under the above preferred conditions, the aqueous solution containing the pre-mouth mixture is dehydrated to a water content of 60-96%. Hya until the solid content is 40-4%. If necessary, use a concentration method other than reverse osmosis membrane, such as evaporation under vacuum. By using the a reduction method etc., the above value is
Can be concentrated to higher concentrations.

[Effect]

The aqueous method SE synthesis reaction mixture contains, in addition to the target SE, unreacted sugar, unreacted fatty acid methyl ester, and residual catalyst 1.
When acidic water is added to this impure reaction mixture, which contains impurities such as soap, tidal fatty acids, etc. Unreacted sugars dissolve and migrate into the aqueous phase, leaving behind unreacted fatty acid methyl esters and by-product salts derived from the catalyst. Impurities such as soap and free fatty acids precipitate together with SE in the form of a cake. When this cake is redissolved in neutral water and brought into contact with an ultrafiltration membrane with an appropriate molecular weight cutoff, some remaining unreacted sugars and by-product salts derived from the catalyst pass through the membrane together with water. removed. When this permeate is treated with a reverse osmosis membrane, a purified SE concentrate is obtained which is contaminated with small amounts of unreacted fatty acid methyl esters, soaps and fatty acids. (Margin below)

【Example】

Hereinafter, the embodiments and effects of the invention will be explained with reference to examples, but the examples are of course for illustrative purposes only. It does not limit the connotation or extension of the inventive idea. According to the conventional method (aqueous synthesis), potassium carbonate (K
2 CO3) and sodium stearate were added and heated under reduced pressure to obtain a reaction mixture having the composition shown in Table 2 below. After adding water at 50°C and dissolving it, p)I was adjusted to neutrality with a caustic soda solution. The obtained neutral aqueous solution was filtered using the ultrafiltration membrane (trade name (T)) mentioned above.
ERP-E-5)> (molecular weight cut off 5,000) was sent to a spiral-shaped 4" cylindrical unit with a membrane surface a8rn' equipped with a 4" cylindrical unit with a membrane surface a8rn'. The operating conditions at this time were: Delivery pressure = 8, 5 kg/em2 G ~9, 2k
g/cm2 G liquid feeding temperature=53. Add 4,100 kg of hydrochloric acid to 100 kg of the reaction mixture at 0°C to 53.5°C.
The purified white SE cake was collected by filtration. Nine hours after the start of liquid passage, the amount of SiM sugar dissolved in the filtrate discharged from the ILI membrane was 49% of the unreacted sugar originally contained in one reaction mixture. Also, the leakage of SH into the filtrate was only 0.3z compared to the amount originally contained in the reaction mixture. Furthermore, 52% of the amount of salt originally contained in one reaction mixture was removed into the filtrate. By the above operations, the liquid volume of the concentrated reaction mixture is 2
,000 kg, and the amount of filtrate that passed through the filtration membrane was 2,200 kg. Next, add 2,200 kg of the above concentrate to 2,200 kg of the above concentrate.
g of deionized water was added, stirred at 50° C. for 60 minutes to dissolve, and after adjusting the pH to 7.4, it was again fed to the above-mentioned filtration membrane. When the operation was carried out under approximately the same conditions as described above, 848 kg of concentrated liquid was obtained after 8 hours of liquid passage. The composition of this concentrate is shown in Table 3 below. (Margin below) Table 3 From these results, in addition to recovering 8S% or more of the target sucrose stearate, 80% of the unreacted sugar,
Approximately 88% of the salt was found to be removed in each case. However, unreacted methyl stearate is the king of stearic acid and stearate. It was not removed because it was associated with sucrose stearate. Next, 1,510 kg of the above reconcentrate was poured into reverse osmosis 11i2 (product name (PE1) sold by Toshi Engineering Co., Ltd.
000) Molecular weight cut off = BO) was supplied at a temperature of 50° C. to a spiral-shaped cylindrical unit with a membrane surface of A8. The operating conditions at this time are Table 4: Feeding pressure = 57kg/cm2c ~ 59kg/cm2G
The pH of the solution was 7.8. After 7 hours, the amount of concentrated liquid concentrated with the reverse osmosis membrane was 700
The composition of this concentrate was as shown in Table 4 below, and it was confirmed that approximately half of the water in the concentrate could be removed through the reverse osmosis membrane. Ta. (Left below) Deauta. Thus, it has been found that only approximately half of the water in the concentrate can be removed through the reverse osmosis membrane.

【Effect of the invention】

As explained above, the method for purifying sucrose fatty acid esters according to the present invention involves sequentially combining sucrose fatty acid ester precipitation with acidic water, ultrafiltration, and reverse osmosis. It is possible to provide a technology for economically purifying sucrose fatty acid ester from a water-based sucrose fatty acid ester synthesis reaction mixture without using any solvent, and has the following specific effects. It has great industrial value because of its performance. ■ It is possible to purify sucrose fatty acid ester using inexpensive water without using any solvents in either synthesis or purification. ■ Since no organic solvents are used, there is no need for expensive explosion-proof electrical equipment. ■ Since no organic solvents are used, there is no concern about explosions or fires caused by solvents. ■ Since no organic solvent is used, there is no risk of the solvent getting mixed into the product. ■ Since no organic solvents are used, there is no negative impact on employees due to solvent vapors. ■ For the above reasons, it is extremely easy to create an industrial-scale plant. ■ It is possible to create a safe and low-cost plant. Patent applicant Daiichi Kogyo Seiyaku Co., Ltd.

Claims (1)

[Claims] 1. Unreacted sucrose, unreacted fatty acid methyl ester,
The aqueous method sucrose fatty acid ester-containing reaction mixture containing catalyst, soap, fatty acids, etc. is treated with acidic water, the resulting precipitate cake is dissolved in neutral water, and then brought into contact with an ultrafiltration membrane to remove the untreated water. The sucrose from the reaction and the salt produced from the catalyst are separated by passing through the membrane together with water, and the aqueous solution containing the remaining sucrose fatty acid ester, unreacted fatty acid methyl ester, soap, and fatty acid is inverted. A method for purifying sucrose fatty acid ester, which comprises concentrating it by contacting it with a permeable membrane. 2 The composition of the reaction mixture is: Unreacted sucrose = 1-80% Unreacted fatty acid methyl ester = 0.5-10% Catalyst (K
_2CO_3) = 0.05-7% soap = 2-60
% fatty acid = 0.5 to 10% sucrose fatty acid ester = 15 to 95%. 3. The manufacturing method according to claim 1, wherein the liquid property of the sucrose fatty acid ester-containing reaction mixture is adjusted to a pH of 3.0 to 5.5 with an acid selected from the group consisting of lactic acid, acetic acid, sulfuric acid, and hydrochloric acid. . 4. The temperature of the aqueous solution of the sucrose fatty acid ester-containing reaction mixture is 40°C to 60°C, and the amount of water added to the reaction mixture is such that water/reaction mixture = 5 to 40 (by weight). 1. The manufacturing method described in 1. 5 The ultrafiltration membrane is composed of polysulfone-based or polyvinylidene fluoride-based resin, and has a molecular weight cut-off of 1.0
2. The manufacturing method according to claim 1, wherein the amount is from 00 to 100,000. 6. The manufacturing method according to claim 1, wherein the pressure during ultrafiltration is 1 to 20 kg/cm^2. 7. The manufacturing method according to claim 1, wherein the pH of the filtrate during ultrafiltration is 6.2 to 8.2. 8. Claim 1 or 2, wherein the fatty acid residue constituting the fatty acid methyl ester has 16 to 22 carbon atoms, and the fatty acid residues of the soap and fatty acid are common to the fatty acid residue constituting the fatty acid methyl ester. Manufacturing method described. 9. The manufacturing method according to claim 1, wherein the reverse osmosis membrane is made of a polyether resin and has a molecular weight cut off of 60. 10 Pressure during reverse osmosis is 50-65kg/cm^2G
The manufacturing method according to claim 1. 11. The manufacturing method according to claim 1, wherein the aqueous solution of the reaction mixture that has not passed through the reverse osmosis membrane is concentrated to form a slurry.