JP2688985B2 - Method for purifying high HLB sucrose fatty acid ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the invention]

TECHNICAL FIELD The present invention relates to an industrial purification method for high HLB sucrose fatty acid ester. More specifically, the present invention relates to a technique for industrially obtaining a hydrate of a high HLB sucrose fatty acid ester without using an organic solvent for purification.

[Prior art]

(1) Background Currently, sucrose fatty acid ester (hereinafter also abbreviated as << SE >>) useful as a surfactant is industrially used as sucrose and C8-C2.
Whether the higher fatty acid methyl ester of 2 is reacted in the presence of a suitable catalyst in a solvent (dimethylformamide, dimethylsulfoxide, etc.) (solvent method: JP-B-35-13102),
Alternatively, sucrose is made into a molten mixture with fatty acid soap using water without using a solvent, and then reacted with a higher fatty acid methyl ester in the presence of a catalyst (water medium method: JP-B-51-14485).
No.). However, by any of these two synthetic methods, in the reaction mixture, unreacted sugar other than the target SE, unreacted fatty acid methyl ester, residual catalyst, soap,
Contaminants such as free fatty acids and volatile matter are contained. Of these contaminants, impurities with a content exceeding the specified amount must be removed before commercialization. Of the above contaminants, the removal of residual solvent (volatile matter) associated with the former solvent method is extremely important only for the recent regulations ( ^Note) . Note) According to the US FDA standard, the residual dimethyl sulfoxide allowable in SE is 2 ppm or less (Fed.Regist., 51
(214), 40160-1). Therefore, conventionally, "removal of residual reaction solvent from crude SE"
For the purpose of a large amount of organic solvents (eg butanol, toluene, methyl ethyl ketone, methyl acetate, etc.)
1588, 48-10448, etc.) has been commonly used, but the heavy use of such a solvent brings a significant disadvantage to the industrial production of SE as described below. Explosion, fire hazard. Explosion-proof electrical equipment provided above. Sealing of the production equipment provided above. The fire-resistant structure of the whole building prepared above. Above, due to rising fixed costs. Cost increase due to solvent wear. Negative effect due to residual solvent remaining in product SE. The negative impact on employee health, and the rise in fixed costs associated with the increase in the number of shifts to prevent it. Under such circumstances, the development of a technique that makes it unnecessary to use an organic solvent during SE purification has been an urgent need in the art. (2) Problems of the prior art By the way, purification methods that do not use an organic solvent have been studied in the past, and as typical ones, (1) a method for precipitating SE using an acidic aqueous solution (UK Patent 809,81
5 (1959)) (2) SE precipitation method using general neutral salt aqueous solution
-8850) is known. However, like method (1), when an aqueous hydrochloric acid solution is added to the reaction mixture, the more SE is precipitated, the more unreacted sucrose is easily decomposed and converted into glucose and fructose. Decomposition cannot be avoided even if it is carried out at a low temperature (0 to 5 ° C). Therefore, it becomes very difficult to recover and reuse the unreacted sugar. Also, as in method (2), SE is immediately precipitated even when an aqueous solution of a neutral salt such as salt or sodium sulfate is added to the reaction mixture. In this case, the unreacted sugar is not decomposed, but the useful monoester in SE is dissolved in the aqueous phase side, which not only causes a large loss but also has a large demand in recent years. It is an obstacle when it is desired to obtain a sucrose fatty acid ester having a high HLB value * (hereinafter also referred to as << high HLB-SE >>), which is the object of the invention. * Hydrophilic-new oily balance. It takes a value in the range of approximately 1 to 20. The larger the value, the stronger the hydrophilicity. Furthermore, according to the more recent JP-A-51-29417, for purification, water and a "purification solvent" (to distinguish from a reaction solvent,
The property that a mixed solution with (particularly so called) is separated into a light liquid layer (upper layer) and a heavy liquid layer (lower layer) is used. That is, since the heavy liquid layer (lower layer) generally contains a large amount of water, hydrophilic unreacted sugars, salts derived from the catalyst, etc. are dissolved in this heavy liquid layer (lower layer), while the light liquid layer (upper layer). Since a large amount of purified solvent is contained in (), substances with small polarity such as SE, fatty acids, and unreacted fatty acid methyl ester are dissolved in this light liquid layer, so the two are separated by phase separation. . In this case, it is soluble in the reaction solvent such as dimethyl sulfoxide and the lower heavy liquid layer, but unfortunately, it is also soluble in the upper light liquid layer, so the reaction solvent can be completely separated only by this method. Is impossible. Therefore, a very large amount of a purified solvent is required only for removing a trace amount of the reaction solvent. Thus, in order to industrially enable the purification of crude SE with water, it is a major premise to develop a purification method in which the removal of the solvent is complete and the sugar and the product SE are not lost. , Such a method has not been developed yet. [Problems to be solved by the invention] Accordingly, the problem to be solved by the present invention is to use not only a solvent for purification but industrially, not only unreacted sugar in the SE reaction mixture, but also a residual solvent and a catalyst. To solve all the problems caused by the use of purified solvent by developing the technology for obtaining purified HLB-SE in a water-containing form, which is free of by-product salts and other contaminants. Is.

Configuration of the Invention

[Means for Solving the Problems] (1) Concept Therefore, the present inventor aims to solve the above problems by (a)
Not only to suppress the amount of SE dissolved in the water phase side to the minimum, but to set the amount to zero to precipitate the total amount of SE if possible,
Many salting-out experiments were conducted with the goal of solving (3) the separation of unreacted sugar from the SE by (c) avoiding the decomposition of unreacted sugar and (c) dissolving the remaining reaction solvent outside the aqueous phase. As a result, when sucrose and a neutral salt were dissolved in an aqueous solution of a reaction mixture, it was surprisingly found that SE was not dissolved in water under the appropriate combination of pH, temperature, neutral salt and sucrose concentration and amount. Not only is the total amount precipitated without elution into the phase, but a convenient phenomenon in which not only unreacted sugar but also salts derived from the catalyst to be removed are eluted in the aqueous phase. I found it. After re-dissolving the SE precipitated here in water and repeating the re-precipitation operation with a neutral salt and an aqueous sucrose solution, the SE
By maintaining the precipitation state without transfer to the aqueous phase, and by adding acidic water having an appropriate pH to the precipitate to wash it, the high HLB fraction and soluble impurities in the residual precipitate are acidic water. Phase transitions to high purity low
It was found that the HLB fraction remained. Furthermore, it was also found that the recovery of high HLB-SE transferred to the aqueous phase here becomes industrially possible by the addition of fatty acid. Thus, (1) removing impurities from the SE reaction mixture without using any organic solvent. (2) It has become industrially possible to obtain water-containing SE with high HLB, and eventually to separate SE according to the application, but these have been regarded as impossible in the past. That was something I could not predict. (2) Outline The present invention is based on the above findings, and in addition to the target sucrose fatty acid ester, a reaction mixture containing unreacted sugar, unreacted fatty acid methyl ester, catalyst, soap, fatty acid, and volatile matter. Adjust the pH to a neutral range, wash the precipitate produced by adding water, neutral salt and sucrose with acidic water,
The gist is a method for obtaining a hydrous high-HLB sucrose fatty acid ester, which is characterized in that a fatty acid is added to a washing liquid to neutralize a precipitate. Therefore, the present invention comprises the following steps. (I) A step of removing impurities from the crude SE reaction mixture (a step of salting out the crude SE). (II) A step of washing the impure SE precipitate (sorting step). (III) A step of recovering high HLB-SE in a precipitated state (reprecipitation step of high HLB-SE by addition of fatty acid). Hereinafter, important matters relating to the invention will be described separately. (3) Synthesis of SE by Solvent Method In the synthesis of SE by the solvent method, usually, a mixture of sucrose and fatty acid methyl ester is added to a reaction solvent in several times the total amount thereof, for example, dimethylsulfoxide, Dissolve and hold at 80-90 ° C for several hours in vacuum around 20-30 Torr in the presence of alkaline catalyst such as potassium carbonate (K2C03), so that the reaction rate is 90% or more (fatty acid methyl ester standard) easily. An SE reaction mixture forms. Next, 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 mixture in an equivalent amount in order to eliminate the activity of the alkaline catalyst in the SE reaction mixture. By this neutralization, the catalyst changes into neutral salts corresponding to potassium lactate and the like. Finally, when the reaction solvent such as dimethyl sulfoxide is distilled off under vacuum, a mixture having the following composition range (a reaction mixture after neutralization and distillation) is obtained. Sucrose fatty acid ester = 15 to 95% Unreacted sugar = 1.0 to 80% Unreacted fatty acid methyl ester = 0.5 to 10% Neutral salt derived from potassium carbonate = 0.05 to 7% Soap = 1.0 to 10% Fatty acid = 0.5 to 10 % Volatile matter (remaining reaction solvent) = 3.0 to 30% At this time, the ester distribution of SE is 10 to 75 monoesters.
% (90 to 25% for diester or higher). The fatty acid root mainly contained in each of the fatty acid methyl ester, soap and fatty acid is saturated and has a common carbon number of C16 to C22. (4) Water Next, water is added to the above reaction mixture, and water: reaction mixture = 5: 1 to 40: 1 (weight ratio) (1) More preferably, water: Reaction mixture = 20: 1 (weight ratio) (2) Add to the ratio of the formula and adjust the pH to 6.2-8.2, preferably pH
7.5 In this case, when the water addition ratio is out of the above range, for example, when the ratio of water to the reaction mixture is less than 5,
The viscosity of the obtained aqueous solution becomes large, and subsequent operations become substantially difficult. Conversely, the ratio of water to the reaction mixture is
When excess water is added to the extent of exceeding 40, the viscosity becomes small and the subsequent operation becomes easy, and the desired reaction solvent can be suitably removed, but unreacted sugar, etc. When recovering water, a large amount of energy cost is required to remove water, resulting in loss of economic efficiency. Furthermore, the pH of the aqueous solution is preferably adjusted to pH 6.2 to 8.2 in order to avoid the decomposition of the target SE. pH8.2
Under the above hydrogen ion concentration, the quantitative
There is a concern that SE may be decomposed, and there is a risk of acid decomposition when exposed to a high temperature of 90 ° C or higher even in a weakly acidic range of pH 6.2 or lower. (5) Salting out The aqueous solution of the SE reaction mixture, the pH of which has been adjusted as described above, is kept at 50 to 80 ° C as much as possible, and a neutral salt and sucrose are further added. In this case, the neutral salt to be added preferably first satisfies the following formula (3). here, Then, the amount of sucrose to be added should be determined by the equation (6). Further, in addition to both of the above formulas, it is preferable that the weight ratio of the total salt amount and the total sugar amount also satisfies the following formula (7). The present inventors heated an aqueous solution containing a precipitate of SE obtained by adding a neutral salt and sucrose to 50 to 80 ° C. so as to satisfy the above three formulas (3), (6) and (7). It has been found that when the temperature is raised, the total amount of SE precipitates approximately approximately regardless of whether the added neutral salt is lactate, acetate, salt or salt cake. This phenomenon is a unique phenomenon that has not been known so far, and has important value for the purpose of the invention. By skillfully utilizing this fact, the total sucrose including unreacted sugar (total sugar), the volatile component of the catalyst, and the added neutral salt are transferred to the water phase and the precipitated SE cake It becomes possible to separate from (that is, slurry slurry). By the way,
Since the liquid property at this time is not acidic, sucrose is not decomposed, and therefore, it is easy to recover and reuse it if necessary. The attached FIG. 1 is a part of a ternary graph showing this phenomenon in more detail. In this figure, the weight of SE dissolved in the aqueous phase side = Y [g] The weight of precipitated SE = X [g] The total SE (X + Y) [g] dissolved in the aqueous phase side If SE weight ratio = φ [%], φ is defined by the following equation (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 reaction mixture sucrose fatty acid ester = 29% unreacted sugar = 35% unreacted Reaction fatty acid methyl ester = 2% Catalyst-derived salt = 1% Soap = 3% Fatty acid = 1% Volatile content (remaining reaction solvent) = 29% Ester distribution in SE: monoester = 65% Diester or more = 35% , Φ shows how the value of φ changes. Here, the total salt is represented by the formula (4), and the total sugar is represented by the formula (5).
It is the amount defined by each, and is expressed as water amount + total salt amount + total sugar amount = 100%. And the shaded area in Fig. 1 is
Expression (3) Expression (6) and Expression (7) discovered by the present inventors
Is an area that simultaneously satisfies. By determining the amount of neutral salt and sucrose dissolved so as to fall within the shaded area, substantially φ = 0, that is, approximately the entire amount of SE can be precipitated, and the precipitated SE is collected by filtration. Alternatively, sucrose, volatile matter, neutral salts and the like dissolved on the aqueous phase side can be removed by centrifugation. (6) Washing In the salting-out step, the SE that has been approximately and totally precipitated from the aqueous solution of the reaction mixture by the addition of neutral salt and sucrose is in a water-containing state, that is, in the form of slurry. is there. Although it is a relatively small amount, it still contains impurities such as volatile matter, salts and sucrose. As a result of extensive research on the method for purifying this impure sludge, the inventor has found that good results can be obtained by washing it with acidic water. That is, impurities are removed by washing the impure SE slurry with acidic water adjusted to pH = 3.0 to 5.5. Suitable acids used here are, for example, mineral acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid and lactic acid, but the edible acids are not limited to those exemplified above. The temperature of the acidic water is suitably 10-40 ° C. By washing under such conditions, the impurities desired to be removed from the cake side (that is, volatile matter, total sugar, added neutral salt, salt derived from catalyst, etc.) can be transferred to the aqueous phase side. . In the above washing operation, when the temperature of the acidic water is 40 ° C or higher, when the operation takes a long time, for example, several months,
Not only is there concern over acid decomposition of SE, the viscosity will increase, making operation difficult. On the other hand, maintaining a low temperature of 10 ° C. or less requires refrigerator equipment that is economically negligible. Therefore, it is usually preferable to operate at 10 to 40 ° C, especially near room temperature. When washing the SE cake with this acidic water,
Volatile components (reaction solvent) contained in this cake, unreacted sugar, added neutral salt and salt by-produced by neutralization of the catalyst need to be removed from the SE cake as much as possible.
The SE cake to be treated is preferably shredded in the acidic water to have a particle size as small as possible in order to easily release impurities contained in the SE cake. The purpose is
For example, it can be efficiently achieved by a fragmentation device such as a dispersion mixer (for example, “Homomixer” manufactured by Tokushu Kikai Kogyo Co., Ltd.), a homogenizer or a colloid mill (for example, trade name “Mycoloider”), and volatile matter (reaction solvent). ), Unreacted sugar, catalyst-derived salt and neutral salt all migrate from the precipitated SE cake into the acidic aqueous phase. At this time, high from the sediment
A remarkable phenomenon occurs where HLB SE begins to dissolve in the acidic water side. The tendency of this high HLB-SE to dissolve in water changes depending on factors such as the temperature and pH of the system.
When the pH is around 3.5, it is as shown in Figure 2. Here, since SE with high HLB has high water solubility, it is tentatively named as “water-soluble SE”, and the name is “Y”.
give. Y has a high HLB and therefore exhibits high water solubility. Therefore, it does not precipitate even in an acidic aqueous solution, and normally dissolves in the solution. On the contrary, low HLB SE has low water solubility, so
Generally, it tends to precipitate under a certain acidic hydrogen ion concentration. So, let's tentatively name it "precipitable SE",
Give "X" as a sign. X has a low HLB and is therefore likely to precipitate from acidic aqueous solutions. The above-mentioned FIG. 2 is a part of the triangular coordinate diagram in which the total of the monoester, diester and triester is expressed as 100%. In the figure, point M represents the composition of the original sample SE. Point X represents the composition of precipitable SE with a low HLB SE. Point Y is SE of high HLB and represents the composition of water-soluble SE. The subscripts 1, 2, and 3 represent SEs having different ester distributions. Now, for example, in the figure, the ester distribution M2 (monoester = 73%, diester = 22%, triester = 5)
% So that the SE sample with 3% has a SE concentration of 3%
When an aqueous solution of 3.5 is added, the SE is an ester distribution (precipitable SE (X2)) (monoester = 68%, diester = 25%,
Triester = 7%) and an ester distribution of water-soluble SE (Y2) (monoester = 84%, diester = 13%, triester = 3%). The weight of the divided X2 and Y2 is WM2 ＝ WX2 ＋ WY2 …… (a) (However, ▲ ▼ is the distance between M2 point and Y2 point, ▲
▼ is the distance between X2 point and M2 point, WM2 is the weight of M2, WX2 is
The weight of X2 and WY2 are the weight of Y2, but the weight of dry matter is the above. ) Is obtained by solving both equations (a) and (b)
And WY2 are required. Thus, SE having a relatively high monoester content (that is, SE having a high HLB) is more easily dissolved in acidic water, and SE having a relatively low monoester (that is, SE having a lower HLB) is
By taking advantage of the property of being easily present on the precipitation side, SE can be quantitatively divided into those with high HLB and those with low HLB. In general, the higher the monoester content in SE, the greater the amount of SE (Y) dissolved in water, and vice versa, the amount of SE (Y) dissolved in water decreases. Trends were also discovered. Then, how much SE of an arbitrary composition dissolves in acidic water can be determined by substituting the values of φ given in the data of Fig. 2 into equations (a) and (b) and calculating WX and WY.
It can be quantitatively obtained by solving the value of. Thus, since the acidic aqueous solution obtained in the main washing step contains a relatively large amount of high HLB-SE, it is separated from precipitated SE mainly composed of low HLB SE by filtration or centrifugation. The obtained filtrate (or supernatant) contains a small amount of residual volatile components (dimethyl sulfoxide and the like), salts, sucrose and the like in addition to SE having a high HLB. (7) Reprecipitation and Purification with Fatty Acid Therefore, the present inventors have found that the high HLB SE (that is, water-soluble S
As a result of earnest studies for the purpose of obtaining the precipitate of E), it was found that this object can be effectively achieved by adding a fatty acid to the filtrate. It is known that SE aggregates with each other in an aqueous solution under certain conditions to form a high molecular weight micellar structure assembly (ibid.
See page 102). By the way, those of SE type or those in which 1 to 3 fatty acid residues are bonded to the oxygen atoms of the three primary hydroxyl groups of the molecule of sucrose are called monoester, diester and triester, respectively. ing. As is well known, monoesters have a higher hydrophilicity than diesters and triesters, but the degree of micelle formation in water is small, so that a relatively low molecular weight (small molecular diameter) SE micelle aggregate is used. To form. On the contrary, since diesters and triesters have relatively high hydrophilicity but very high micelle forming ability, they form SE micelle aggregates having extremely large molecular weight (that is, large molecular diameter) in water. Based on the above facts, the inventors of the present invention have inferred that SE having high HLB and high hydrophilicity (that is, water-soluble SE having a monoester content of more than about 80%) has a hydrophobic property such as fatty acid in water. Upon contact with a volatile substance, an SE micelle aggregate different from the normal micelle structure is formed, and the aggregate is further aggregated,
It was presumed that it would become huge and could no longer exist in an aqueous solution state, and that SE and fatty acid would eventually coalesce and precipitate. If this estimation is correct, it should be possible to expect that water-soluble SE that cannot be easily separated by ordinary means can be precipitated on an industrial scale by making good use of this precipitation phenomenon. Therefore, as a result of various studies based on the above concept, a new finding that high HLB-SE is selectively precipitated by fatty acid has been obtained. Below, the details of this new finding will be explained by sectioning them. (A) Precipitation Phenomenon of High HLB-SE by Addition of Fatty Acid According to the above assumptions, the inventors have found that water-soluble SE (80% or more of monoester, and therefore diester and triester total 20
%, When fatty acid is added to an aqueous solution containing
At room temperature to 90 ° C and pH = 3.0 to 5.5, the fatty acid floats in the aqueous solution at the beginning of the addition, but it immediately grows into a precipitate or melt, and finally precipitates at the bottom of the container. I found the amazing fact that it comes. The bottom precipitate consisted of a large amount of high HLB-SE and a mixture of fatty acids in an amount close to that added. The amount of this precipitate produced is
Generally, the higher the temperature of the aqueous solution (in the range of room temperature to 90 ° C), the lower the pH (in the range of pH = 3.0 to 5.5), and the larger the amount of fatty acid added (within a certain range). The amount of dissolved water-soluble SE is higher (1).
It was also found that the lower the proportion of monoester contained in the water-soluble SE (at 80% or more of monoester), the higher the respective proportion. Regarding the above phenomenon, it is presumed that the higher the temperature, the more the amount of precipitate increases because the melting of fatty acids promotes the unification of SE and fatty acids. The amount of precipitation is reduced to a fraction. However
From the viewpoint of the stability of SE against temperature, it is preferable that the temperature is as low as possible, and thus it is not preferable to raise the temperature indefinitely.
Therefore, experimentally, a temperature in the range of approximately 50 to 80 ° C. gives favorable results satisfying both the amount of precipitation and the stable retention of SE. By the way, since the melting point of C20 arachidic acid is 77 ° C,
This upper limit temperature value is equal to or higher than the melting point of the normal fatty acid which constitutes SE. The lower the pH, the greater the amount of precipitate. As is well known, SE is much more stable in the acidic pH range rather than the alkaline pH range. However, if the acidity is too strong, the stability of SE will be impaired, so it is advisable to set the pH to a weakly acidic range of 3.0 to 5.5. In the pH range of this range, the lower the pH, the greater the amount of precipitate produced. In order to obtain a large amount of precipitate, a weak acidic region of about pH 3.5 to 4.0 is suitable, considering other conditions. The required amount of fatty acid to be added is
Depends on the amount and concentration of SE. So, strictly speaking,
The amount of fatty acid added and the amount of precipitation do not necessarily correlate, but the tendency is that the more fatty acid is added, the more precipitation often occurs. However, addition of an excessively large amount of fatty acid generally increases the amount of precipitate produced, but on the other hand, it increases the amount of fatty acid as an impurity, which causes an undesirable result that the purity of the obtained high HLB-SE is lowered. If the water-soluble SE (high HLB-SE) is excessively dissolved, both the viscosity and the specific gravity of the aqueous solution become too large, making it difficult to separate the precipitate. Therefore, for example, when stearic acid is a constituent fatty acid of SE, the concentration of the aqueous solution SE = about 2.0% is preferable in terms of separation efficiency. In general, when the content of monoester is 80% or less, SE does not maintain its water solubility when the pH is in the acidic range, and it partially precipitates. According to the experience of the inventors, in many cases, when the monoester is 80% or more (thus, the total of diester and triester is 20% or less), pH = 3.5 to 4.0.
It is to some extent water-soluble. When the monoester content is 90% or more, SE is more surely water-soluble and does not precipitate even in the above acidic region. Next, regarding the amount of precipitation, SE, which also has a low monoester content (at a monoester content of> 80%), has a higher precipitation amount. That is, the higher the content of diester or triester (provided that the content of diester + triester is <20%), the greater the amount of precipitation. The above findings lead to the following technologies for recovering water-soluble SE. (B) Recovery Technology of Water-Soluble SE by Addition of Fatty Acid It has hitherto been industrially not easy to obtain water-soluble SE (containing a large amount of monoester and having a high HLB value) without using a solvent. However, if the phenomenon discovered by the above-mentioned inventors is used effectively, a harmless substance (that is, fatty acid)
Is added, it is highly soluble in water without using a solvent.
The prospect for a new industrial technology of recovering HLB-SE as a precipitate opens up. Hereinafter, a technique for recovering water-soluble high HLB-SE mainly containing stearic acid as a constituent fatty acid will be described. However, this technique is not limited to the addition of stearic acid, and the addition of other fatty acids can also be used for industrial purposes. Can be implemented in a simple manner. However, in order not to complicate the problem, it is desirable to add a fatty acid of the same kind as the constituent fatty acid of SE. (A) The acidic aqueous solution obtained in the pickling step of the crude product containing SE containing high HLB-SE (water-soluble SE) contains a large amount of high HLB-SE and a smaller amount of residual volatile matter (DMSO), Also includes salt and sucrose.
This acidic aqueous solution is maintained at pH 3.0 to 5.5, and preferably heated to 50 ° C to 80 ° C so that the SE concentration is 1.0 to 4.0%, more preferably 2%. (B) Addition amount of fatty acid When stearic acid (or a fatty acid similar thereto) is added to the above acidic aqueous solution, water-soluble SE having a high HLB value starts to aggregate around the fatty acid, and finally coalesces, A precipitate is formed. The amount of fatty acid to be added is preferably in the following range. However, considering the two points of the obtained high HLB-SE purity and the recovery rate of high HLB-SE, the preferable addition amount of fatty acid is Range. (C) pH of aqueous solution When adding fatty acid, it was mentioned above that pH should be adjusted to 3.5-5.5 by adding an appropriate acid to the target high HLB-SE-containing aqueous solution. Is preferable in several respects. In terms of the stability of SE, excessive alkaline pH should be avoided most, and conversely, strong acidity is not preferable because it causes the decomposition of SE. SE is stable in a short time if the pH is in the weak acid range of 3.5 to 4.0. This pH range is also preferable from the viewpoint of increasing the precipitation amount of high HLB-SE (water-soluble SE). In addition, if the pH is 3.5 to 4.0, there is less risk of causing metal corrosion of the separator for the formed precipitate.
(However, the use of hydrochloric acid or high temperature sulfuric acid as a pH adjuster should be avoided). Next, the pH-weakened aqueous solution is stirred to complete the precipitation. This agitation is preferably strong, and the time is about 10 minutes. The precipitate thus separated contains approximately 80% water and 20% water.
Contains solids of. The composition ratio of the dry solid content excluding the contained water is Often takes a moderate value. (D) Washing the precipitate The combined precipitate of high HLB-SE and fatty acid that was precipitated by the above fatty acid addition is a small amount of residual volatile matter (DMSO of reaction solvent), salts, sucrose, etc. other than water. Although it is accompanied by impurities, it is separated from the aqueous solution (supernatant) layer by subsequent washing with acidic water, and the impurities (volatile matter, volatile matter,
The content of (salt, sucrose, etc.) is reduced, and the purity is improved. The post-washing operation can be repeated twice or more, if desired, to further improve the purity of high HLB-SE. (E) Recovery rate Due to the above operations, high HL that was originally present in the water-soluble state
B-SE can be recovered as a precipitate at a high rate of 85% to 95%. And the obtained high HLB-SE containing precipitate has a solid content of 5 to 5.
After being filtered and recovered as a 20% precipitate, it is neutralized and redissolved in water, and if necessary, for example, a powdery product is subjected to a drying step if desired.

[Action]

Unreacted sugar, unreacted fatty acid methyl ester, catalyst,
High with soap, fatty acids and volatiles (remaining reaction solvent)
After adding acid to the HLB-SE formation reaction mixture to adjust the pH to a neutral range, water, neutral salt and sucrose are added and salted out at an appropriate temperature to obtain high HLB-sucrose fatty acid ester, unreacted. Since the fatty acid methyl ester, soap, and fatty acid of (1) are precipitated and the volatile content (remaining reaction solvent) moves to the aqueous phase side, the residual volatile content can be removed without using any organic solvent. In particular, by operating so as to satisfy the conditions of the formulas (3), (6) and (7), the residual solvent can be removed in a state where the loss of the sucrose fatty acid ester is substantially zero. Next, this precipitate is washed with acidic water, the fatty acid is added to the washing liquid to separate the generated precipitate, and contaminating volatile components, sucrose, added neutral salts and salts by-produced by neutralization of the catalyst, etc. High HLB with solid content 5-20% with impurities removed
A precipitate of sucrose fatty acid ester is obtained. Since it is acidic as it is, it can be neutralized to obtain a hydrous high HLB sucrose fatty acid ester.
Thus, industrial purification of hydrous sucrose fatty acid ester having a high HLB value becomes possible without using any purification solvent. Incidentally, in the above pickling step, the sucrose fatty acid ester remaining on the precipitation side is a high-purity low HLB-sucrose fatty acid ester, and therefore the high HLB of the crude sucrose fatty acid ester also serves as a refinement of the crude sucrose fatty acid ester. The purpose of separating into those with low HLB will be achieved together.

【Example】

Hereinafter, modes and effects of the invention will be described with reference to examples, but the examples are, of course, for the purpose of description, and are not intended to limit or limit the inventive idea. Example Solvent-processed sucrose fatty acid ester represented by the composition in Table 1 below The residue obtained by distilling off the reaction solvent from the reaction mixture was neutralized with lactic acid, and dried to dry matter (dry matter) 100 kg and water 1,000
kg was added and dissolved. 62.5 kg of sucrose and 9% of 50% potassium lactate in the above aqueous solution
7.6 kg was added, the temperature was raised to 75 ° C., the temperature was raised, the precipitated cake was filtered off, dried under vacuum at 80 ° C., and the composition of the solid matter was examined. The water content in the cake was 45%. The amount of sucrose fatty acid ester in the filtrate separated by filtration from the cake was measured by gel filtration chromatography (GPC) method (see page 63 above), and no sucrose fatty acid ester was found. In addition, 95% of the reaction solvent dimethyl sulfoxide was removed. Next, suspend the cake (weight 80 kg) in Table 2 above in 400 kg room temperature acetic acid water with a pH of 3.5, and chop it with a homomixer for 10
After stirring for a minute, an operation of collecting the finely divided precipitate by filtration and washing it with acetic acid water again was repeated 4 times in total. The composition of the obtained filtrate (pH 3.5) is shown in Table 3 below. After adjusting the pH of the aqueous solution in Table 3 (390 kg) to 3.5 with acetic acid,
Heat to ℃, add stearic acid 0.78kg to this, then
Stir well for a minute. When the stirring was stopped, 54.1 kg of hydrous precipitate was separated from the supernatant. The composition of the powder obtained by drying a part of this precipitate was as shown in Table 4 below. While stirring 54.0 kg of the water-containing precipitate shown in Table 4, pH was adjusted to 7.8 by adding caustic soda while stirring to obtain a neutral high HLB sucrose fatty acid ester aqueous solution. When a part of this aqueous solution was dried under vacuum, the following table-
A hydrous high HLB-sucrose fatty acid ester having a composition of 5 as described above and a monoester content of about 89.0% was obtained. (The water content was 80 wt.% And the solid content was 20 wt.%.) The remaining precipitate obtained by washing and purifying the sucrose fatty acid ester shown in Table 2 was a low HLB-sucrose fatty acid ester having a monoester content of 67%. Thus, according to this example, the sucrose fatty acid ester originally present in the reaction mixture was separated into the high HLB product and the low HLB product.

【The invention's effect】

As described above, the present invention does not use a refining solvent from the solvent-processed high HLB-sucrose fatty acid ester reaction mixture, and industrially purifies the water-containing high HLB sucrose fatty acid ester and also By enabling the separation of HLB / high HLB-sucrose fatty acid ester, it is possible to industrially exert the following large direct and indirect effects. (1) It becomes possible to purify powdery high HLB / high HLB-sucrose fatty acid ester using only inexpensive water. (2) Able to separate low HLB / high HLB-sucrose fatty acid ester. (3) There is no fear of explosion or fire of the solvent, so that expensive electric equipment of explosion-proof specification is not required. (4) There is no concern that the purification solvent will be mixed into the product. (5) Improve the workplace hygiene environment. (6) It can be industrialized at low cost.

[Brief description of the drawings]

FIG. 1 is a ternary graph showing the relationship between changes in water, total sugar and total salt and the amount of sucrose fatty acid ester dissolved in the aqueous phase, and FIG. 2 is the ester composition of sucrose fatty acid ester. FIG. 3 is a ternary graph showing the relationship between the solubility in water and acidic water.

Claims (18)

(57) [Claims] 1. An unreacted sugar, an unreacted fatty acid methyl ester, a catalyst, a soap, in addition to a target sucrose fatty acid ester.
The reaction mixture containing fatty acid and volatile matter is adjusted to a pH in the neutral range, and the precipitate produced by adding water, neutral salt and sucrose is washed with acidic water, and the fatty acid is added to the washing solution for precipitation. A method for purifying a high HLB sucrose fatty acid ester, which comprises neutralizing the precipitate and not spray-drying after the neutralization. 2. The composition of the reaction mixture is as follows: sucrose fatty acid ester = 15.0 to 95.0% unreacted sucrose = 1.0 to 80.0% unreacted fatty acid methyl ester = 0.5 to 10.0% catalyst = 0.05 to 7.0% soap = 1.0 The method according to claim 1, wherein -10.0% fatty acid = 0.5-10.0% volatile content = 3.0-30.0%. 3. The method according to claim 1, wherein the reaction mixture is adjusted to pH 6.2 to 8.2. 4. The method according to claim 1, wherein the pH-adjusted reaction mixture is heated to 50 to 80 ° C. 5. The weight ratio of water to reaction mixture added to the reaction mixture is water: reaction mixture = 5: 1 to 40: 1.
The described method. 6. The method according to claim 1, wherein the neutral salt and sucrose are added to the reaction mixture after pH adjustment according to the following relational expression. And, And, Here, total salt amount = neutral salt amount to be added + salt amount produced by neutralization of catalyst Total sugar amount = sucrose amount to be added + unreacted sugar amount from the beginning 7. The acid used to adjust the pH of the reaction mixture comprises:
4. The method according to claim 1, which is any one of acids selected from the group consisting of lactic acid, acetic acid, hydrochloric acid and sulfuric acid. 8. The method according to claim 1 or 2, wherein the fatty acid roots mainly contained in each of the fatty acid methyl ester, soap and fatty acid in the reaction mixture have a common saturated fatty acid root having 16 to 22 carbon atoms. 9. The method according to claim 1, wherein the component of the volatile matter (remaining reaction solvent) in the reaction mixture is dimethyl sulfoxide or dimethylformamide. 10. The method according to claim 1 or 6, wherein the neutral salt added to the reaction mixture is any salt selected from the group consisting of sodium chloride, mirabilite, potassium lactate and potassium acetate. 11. The method according to claim 1 or 2, wherein the ester distribution of the sucrose fatty acid ester is 10 to 75% (90 to 25% of diester or more) as a monoester content. 12. The method according to claim 1, wherein the pH of the acidic water is 3.0 to 5.5. 13. The pH of the washing liquid to which fatty acid is added is 3.0 to
The method of claim 1 which is 5.5. 14. The temperature of the washing liquid added with fatty acid is 50 to 50.
The method according to claim 1 or 13, which is 80 ° C. 15. The method according to claim 1 or 2, wherein the high HLB sucrose fatty acid ester contains 80% or more of monoester (the total amount of diester and triester is 20% or more). 16. A high content of a washing liquid containing a fatty acid.
The method according to claim 1, 13 or 14, wherein the concentration of the HLB sucrose fatty acid ester is 1 to 4%. 17. The method according to claim 1, wherein the type of the fatty acid is the same as or similar to the constituent fatty acid of the sucrose fatty acid ester. 18. A sucrose fatty acid ester of high HLB dissolved in a washing liquid containing a fatty acid, which is 1/4 to 1/30
18. A method according to any of claims 1, 13, 14, 16 or 17, wherein an amount of fatty acid is added.