JPH08198811A - Method for producing polyglycerin fatty acid ester - Google Patents

Abstract

(57) [Summary] [Purpose] When a polyglycerin fatty acid ester is produced by esterifying polyglycerol and a fatty acid,
Disclosed is a method for stably producing a product having a desired esterification rate by suppressing the distillation of fatty acids out of the reaction system. [Structure] When a polyglycerin and a fatty acid having 8 to 22 carbon atoms are subjected to an esterification reaction to produce a polyglycerin fatty acid ester, a reactor having a packed column connected to the upper side is used to remove the fatty acid from the reaction system. The reaction is carried out while purging the by-product water from the top of the packed column while suppressing the distillation of [Effect] The above object is achieved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a polyglycerin fatty acid ester. Specifically, polyglycerin and fatty acid having 8 to 22 carbon atoms are used as raw materials, and polyglycerin fatty acid ester (hereinafter abbreviated as PoGE).
To a method for stably producing

[0002]

2. Description of the Related Art Conventionally, PoGE is known as a highly safe surfactant approved as a food additive,
It is mainly used as an emulsifying agent and a solubilizing agent for foods, and further, it has been attempted to be used for cosmetics, foods, detergents for foods, and oral compositions.

As a method for producing PoGE having such a purpose, for example, as described in Japanese Patent Laid-Open No. 63-68541, a reactor equipped with a plurality of condensers is usually used, A method of performing an esterification reaction of glycerin and a fatty acid is known. According to the method described in this publication, the reactivity of the esterification reaction is good, and the amount of 180-
The esterification reaction can be carried out under a temperature condition of 260 ° C. while distilling off the by-product water out of the reaction system.

However, in this esterification reaction, since the entire amount of the gas volatilized from the reactor is introduced to the outside of the system and condensed, the vapor of the raw material fatty acid contained in the volatile gas is by-produced. Entrained in water, cooled and solidified after the condenser, and attached to the pipe of the reactor, causing trouble. Further, when the fatty acid is distilled out of the reaction system, the molar ratio of polyglycerin and the fatty acid is changed, which causes a problem that PoGE having a target esterification rate cannot be obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to carry out an esterification reaction of polyglycerin and fatty acid to produce PoGE.
When producing, suppresses the distillation of fatty acids out of the reaction system,
It is intended to provide a method for stably producing a polyglycerin fatty acid ester having a desired esterification rate.

[0006]

In order to solve the above problems, in the invention of claim 1, polyglycerin is reacted with a fatty acid having 8 to 22 carbon atoms to produce a polyglycerin fatty acid ester. In the method, in order to produce a polyglycerin fatty acid ester by carrying out a reaction while purging by-product water from the top of the packed tower using a reactor having a packed tower connected to the upper part, a means is taken. is there.

Hereinafter, the present invention will be described in detail. In the method of the present invention, polyglycerin and a fatty acid having 8 to 22 carbon atoms are used as raw materials. The raw material polyglycerin is (1) a method in which a catalyst such as sodium hydroxide is added to glycerin and the polycondensation reaction is carried out at a high temperature of 180 ° C or higher under an inert gas stream such as nitrogen. (2) Glycerin is added to glycidol And (3) ring-opening polymerization of glycidol. The polyglycerin that can be used in the method of the present invention generally has an average degree of polymerization (n) of 4 to 15 and a hydroxyl value of 8.
45 to 1100.

The raw material fatty acid may be a saturated or unsaturated fatty acid having 8 to 22 carbon atoms, a linear fatty acid, a fatty acid having a side chain or a hydroxy group-substituted fatty acid. When the fatty acid has 8 to 22 carbon atoms, the performance of the finally obtained polyglycerin fatty acid ester as a surfactant is excellent, but when it is less than 8 or exceeds 22 carbon atoms, It is not preferable because the performance of the finally obtained product as a surfactant does not become excellent.

Specific examples of fatty acids include caprylic acid and 2
-Ethylhexanoic acid, capric acid, undecyl acid, undecylenic acid, lauric acid, dodecyl acid, tridecyl acid,
Isotridecanoic acid, myristic acid, pentadecyl acid, palmitic acid, palmitoleic acid, heptadecyl acid, stearic acid, isostearic acid, linoleic acid, linolenic acid, nonadecanoic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, behenic acid, cetrainic acid , Erucic acid,
Examples thereof include ricinoleic acid, lignoceric acid, and hydroxytearic acid.

Among these fatty acids, when a saturated fatty acid such as stearic acid, palmitic acid, behenic acid, etc. is used, it is easy to solidify by cooling, so that the object of the present invention can be effectively achieved.

When the polyglycerol and the fatty acid are subjected to an esterification reaction, the fatty acid is usually added in an amount of 0.01 to 17 moles, preferably 0.1 to 1 mole of polyglycerin.
It is 13 mol. When the esterification reaction is carried out according to the method of the present invention, since the raw material fatty acid does not distill out of the reaction system, the raw material can be maintained at a predetermined molar ratio during the reaction, and thus the desired initial setting can be easily performed. PoGE having an equivalence ratio corresponding to the esterification rate of is obtained.

The esterification reaction of the polyglycerin with the fatty acid can be carried out in the absence of a catalyst, but it is preferable to use an alkali catalyst. Usable alkali catalysts include alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium and potassium, and their usual esterifications such as oxides, hydroxides, alcoholates, carbonates and bicarbonates. What is used for the reaction can be used without limitation. When the alkali catalyst is used, the amount is up to 5% by weight based on the total amount of polyglycerin and fatty acid within the range used for usual esterification reaction.

In the method of the present invention, the esterification reaction is carried out using a reactor having a packed column connected to the upper part thereof. The reactor is equipped with a heating medium circulation jacket that can adjust the internal temperature, and
A vertical reaction tank equipped with a stirrer is preferable, and a packed column is connected to the upper part thereof. The packed tower, during the esterification reaction is performed,
Most of the fatty acid, which is vaporized from the reaction tank and accompanied by fatty acids, is condensed and refluxed selectively into the reactor, and water by-produced in the esterification reaction is purged (distilled) from the tower top. Fulfill the function of

The packed column is composed of a plurality of stages equipped with a jacket for circulating a heat medium capable of adjusting the temperature in the packed column. The number of theoretical plates varies depending on the set temperature of the packed column, the packing rate of the packing, the amount of vapor circulated in the packed column, etc., but usually at least one plate is required, and preferably 3 to 20 plates.
When the number of stages is small, the fatty acid is not sufficiently refluxed, the fatty acid is cooled and solidified after the first stage condenser and adheres to the pipe, and is blocked in a pipe having a small diameter. , Can not be maintained accurately. On the contrary, if the theoretical plate number is large, the pressure loss at the time of purging (distilling) the by-produced water becomes large, and it becomes difficult to separate the fatty acid and the by-produced water in the packed column.

The packed column can be variously changed depending on the size of the reaction tank, the molar ratio of the raw materials, the reaction temperature and the like, and the L / D thereof can be selected within the range of 3 to 25. It is preferable that the packed column is filled with the packing inside, and a condenser is arranged in series at the top of the column. Examples of the filler include Raschig ring, Berlu saddle, McMahon, Canon, Stepman, Through the packing, Dixon packing, Interlocks saddle, Lessing ring, Terralette packing and the like. The filling rate of the packing material in the packed tower can be changed depending on the size of the packed tower, L / D, pressure loss, etc., and can be selected in the range of 5 to 50%.

The cooler arranged in series at the top of the packed tower is
It acts to cool and condense by-product water purged (distilled) from the top of the packed column and light boiling substances produced as by-products. By-product water will be cooled and discharged as waste water / waste.

The esterification reaction according to the method of the present invention is usually carried out by charging a reactor with polyglycerin, a fatty acid and a catalyst and heating them with stirring. The heating temperature at this time is usually in the range of 180 to 270 ° C., and the pressure is usually atmospheric pressure. The reaction time is selected in the range of several hours to tens of hours depending on the type of raw material, the presence or absence of a catalyst, the type of catalyst, the reaction temperature and the like.

The esterification reaction proceeds to a considerable level immediately after the start of the reaction, and the conversion rate of the raw material is 90 at the initial stage of this reaction.
% Or more, and by-product water corresponding to this conversion rate is generated. In order to complete the reaction of the reaction system which has reached a considerable conversion rate, it is preferable to raise the reaction temperature from the initial temperature of the reaction to a high temperature side to carry out the reaction. The completion of the esterification reaction can be confirmed by analyzing the reactor contents at each stage.

During the esterification reaction according to the method of the present invention, an inert gas may be passed through the reaction system. Nitrogen is a typical example of the inert gas, and the amount thereof is preferably in the range of 0.5 to 20 liters / hr per liter of the reaction liquid. Nitrogen functions as a carrier for water produced as a by-product, but if the flow rate is too large, it becomes difficult to reflux the fatty acid in the packed column.

When an inert gas is circulated in the reaction system, water produced as a byproduct of the esterification reaction is entrained by the inert gas, and the purge (distillation) can be promoted from the top of the packed column.

In the esterification reaction, by-product water is purged (distilled) from the packed tower while suppressing the distillation of fatty acids out of the reaction system.
It is necessary to carry out the reaction while. That is, by controlling the temperature of the packed tower filled with the packing, the by-product water having a low boiling point evaporated from the reactor is led to the top of the packed tower, and most of the fatty acids entrained in the by-product water (99% The above) is refluxed in the reactor to distill the fatty acid out of the reaction system to less than 1%.

To do this, there are differences depending on the structure of the packed tower, the thermal efficiency, the size of the packing, the packing rate, etc.
According to the experiments conducted by the present inventors, the temperature at the top of the packed column is 70
It is necessary to adjust to ~ 120 ° C. In order to adjust the temperature at the top of the packed tower to the above range, it is preferable to adjust the temperature of the heat medium passed through the jacket of the packed tower, and the temperature of the heat medium is 50 to 2
The temperature is preferably 00 ° C, particularly preferably 60 to 150 ° C.

The polyglycerin fatty acid ester (PoGE) obtained by the method of the present invention has different products depending on the combination of raw materials and the molar ratio. Some are mixed with water and taken out of the reactor, for example as a 40% by weight aqueous solution, some are taken out of the reactor at a temperature at which they exhibit fluidity, and some are taken with a flaker. It can be taken out from the reactor by pulverizing it into powder after cooling and solidifying.

Polyglycerin fatty acid ester is a highly safe nonionic surfactant approved as a food additive and is used as a raw material for emulsifiers, antifogging agents, pharmaceuticals, food additives and cosmetics. It

[0025]

INDUSTRIAL APPLICABILITY The method of the present invention has the following advantageous effects, and its industrial utility value is extremely large. 1. According to the method of the present invention, since a reactor having a packed column connected to the upper portion is used as a reactor for carrying out the esterification reaction, water by-produced in the esterification reaction is purged (distilled) out of the reaction system. Is easy. 2. In the case of the method of the present invention, the reaction is performed while purging by-product water from the packed column while suppressing the distillation of fatty acids out of the reaction system by the packed column connected to the upper part of the reactor. The raw material molar ratio does not change, and PoGE can be stably produced. 3. According to the method of the present invention, the fatty acids entrained in the by-product water are refluxed to the reactor in the packed column, so that they do not adhere to the pipes or block even small pipes.

[0026]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[Example 1] A packed reactor (23 mmφ x 200 m) with 6 theoretical plates was installed above a cylindrical reactor having a capacity of 2 torr equipped with a nitrogen inlet tube, a thermometer, a heating jacket, and a stirrer.
m) were connected to each other, and the packed column was packed with Dickson packing in an amount corresponding to 30% by volume with respect to this volume, and a condenser was arranged in series at the top of the packed column.

To the above reactor, 540 g of polyglycerin (average degree of polymerization 10, hydroxyl value: 888 mg KOH / g) and 960 g of stearic acid (theoretical esterification rate 39.5%) were charged and mixed. The internal temperature of the reactor was raised to 240 ° C, and the top temperature of the packed column was kept at 101 ° C. When the temperature inside the reactor reached 240 ° C, 0.36 millitorr of 10% by weight sodium hydroxide aqueous solution was added, and the temperature was adjusted to 5 at this temperature.
The time esterification reaction was performed. Subsequently, in order to complete the esterification reaction, the internal temperature of the reactor was raised to 260 ° C. in 20 minutes, and this temperature was maintained for 2 hours to complete the esterification reaction.

During this time, the gas discharged from the top of the packed column was condensed to 30 ° C. or lower by a cooler. After finishing the esterification reaction, cool the internal temperature of the reactor,
When the reaction product (PoGE) was recovered, it was 1440 g, and the esterification rate of this PoGE was 39.0%, which was close to the theoretical value. In addition, when the packed column and the inside of the condensation system were inspected, adhesion of stearic acid was not recognized.

[Comparative Example 1] In the example described in Example 1, a reactor in which the packed column of the reactor used in the same example was not packed was used, and the kind of raw material, the charged amount, the reaction temperature,
Regarding the reaction time and the like, the esterification reaction was carried out in the same manner as in the same example. After completion of the reaction, the esterification rate of the obtained PoGE was 33.5%, which was lower than the theoretical value. Also, when the inside of the packed column and the condensation system were inspected, stearic acid was found to have adhered.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C07C 69/675 69/732 Z 9546-4H // C07B 61/00 300

Claims (4)

[Claims] 1. A method for producing a polyglycerin fatty acid ester by reacting polyglycerin with a fatty acid having 8 to 22 carbon atoms, in which a by-product water is charged using a reactor having a packed tower connected to the upper part thereof. A method for producing a polyglycerin fatty acid ester, which comprises carrying out the reaction while purging from the top of the tower. 2. The production method according to claim 1, wherein the reaction is carried out while suppressing the distillation of the fatty acid out of the reaction system. 3. The method according to claim 1, wherein the reaction is carried out while suppressing the distillation of the fatty acid out of the reaction system to less than 1% of the raw material fatty acid. 4. A packed column having 3 to 20 theoretical plates is used, and any one of claims 1 to 3 is used.
The manufacturing method according to item.