JP7416530B2 - Method for producing polyglycerin fatty acid ester - Google Patents

Description

The present invention relates to a method for producing polyglycerol fatty acid ester.

In the production process of polyglycerol fatty acid ester, the reaction is carried out at high temperature, so the polyglycerol fatty acid ester contains odor substances after the reaction is completed. Polyglycerin fatty acid esters used in cosmetics and foods are required to have good odor. Therefore, after the completion of the reaction, a deodorizing process is performed by steam deodorization or increasing the amount of nitrogen to drive out the odor substances, thereby improving the odor of the polyglycerol fatty acid ester. As reported in Non-Patent Document 1, steam deodorization is also generally performed on fats and oils that are esterified products of glycerin and fatty acids. However, adding a deodorizing step has the problem of increasing the number of manufacturing steps after the reaction is completed. Furthermore, deodorization requires depressurization and heating, which may worsen the odor depending on the conditions. Furthermore, as reported in Non-Patent Document 2, activated carbon is known to have the ability to remove odors and colors. It is known that in the synthesis of polyglycerol fatty acid esters, the odor after the reaction can be improved by treating the reaction solution. This method also has the problem of requiring activated carbon filtration treatment, which increases the number of manufacturing steps.

In Patent Document 1, it is reported that microbubbles containing nitrogen suppress deterioration of fats and oils due to oxidation. This report does not describe the temperature conditions for supplying microbubbles, nor does it mention odor suppression. No reports have been found of suppressing odors by expelling odorous substances during the reaction.

Takeyuki Hamamoto et al., Journal of the Japan Oil Chemists' Society, Volume 48, No. 10, 1123-1131 (1999) Written by Taro Yoshikura, Life Hygiene, Volume 41, No. 5, 161-173 (1997)

Japanese Patent Application Publication No. 2018-65979

An object of the present invention is to provide a method for producing a polyglycerol fatty acid ester in which odor after the reaction is suppressed without increasing the number of production steps when polyglycerin and fatty acids are reacted.

As a result of extensive research in order to solve the above problems, the present inventors discovered that when reacting polyglycerin and fatty acids, by supplying inert gas as microbubbles to the high temperature reaction solution of 180 to 270°C. It was discovered that a polyglycerin fatty acid ester with suppressed odor could be obtained after the reaction was completed.

That is, the present invention provides a method for producing a polyglycerin fatty acid ester in which a polyglycerin having an average degree of polymerization calculated from a hydroxyl value of 2 to 20 is reacted with a fatty acid having a carbon number of 8 to 22. The present invention relates to a method for producing polyglycerol fatty acid ester, characterized in that the temperature is 180 to 270°C, and microbubbles containing an inert gas are supplied.

The present invention also relates to a method for producing polyglycerol fatty acid ester, characterized in that the inert gas contained in the microbubbles is nitrogen.

According to the present invention, a polyglycerin fatty acid ester with suppressed odor after the reaction can be produced without going through a complicated purification process such as a deodorizing process. Furthermore, the polyglycerol fatty acid ester produced according to the present invention has a good odor and is therefore useful in the fields of foods and cosmetics.

Embodiments for carrying out the present invention will be described in more detail below, but the scope of the present invention is not limited to these embodiments, and modifications may be made without departing from the spirit of the present invention. Also belongs to the present invention.

The polyglycerin used in the present invention has an average degree of polymerization calculated from the hydroxyl value of 2 to 20. In this specification, the average degree of polymerization (n) calculated from the hydroxyl value is a value calculated by a terminal analysis method, and is calculated from the following formulas (Formula 1) and (Formula 2).
(Formula 1) Molecular weight = 74n + 18
(Formula 2) Hydroxyl value = 56110 (n+2)/molecular weight The hydroxyl value is a numerical value that is an indicator of the number of hydroxyl groups contained in an esterified product, and free hydroxyl groups contained in 1 g of an esterified product are converted into acetyl groups. The number of milligrams of potassium hydroxide required to neutralize the acetic acid required to convert Calculated in accordance with the Act, 2013 Edition.

The fatty acid used in the present invention is a saturated or unsaturated fatty acid having 8 to 22 carbon atoms, and its structure may be linear or branched. Examples include caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, behenic acid, and erucic acid. These fatty acids may be used alone or in combination of two or more.

The esterification reaction between polyglycerin and fatty acid is preferably carried out in the presence of a catalyst in order to speed up the reaction rate. Although acid catalysts can also be used, alkaline catalysts are usually used. Examples of alkali catalysts that can be used include alkali metals such as lithium, sodium, and potassium, alkaline earth metals such as magnesium and potassium, and oxides, hydroxides, alcoholates, carbonates, and bicarbonates thereof. When an alkali catalyst is used, the amount is within the range used in normal esterification reactions, and is 5% by weight or less based on the total amount of polyglycerin and fatty acid.

The esterification reaction according to the method of the present invention is carried out by charging polyglycerin, a fatty acid, and a catalyst, supplying nitrogen, and heating while stirring. The heating temperature at this time is in the range of 180 to 270°C. Volatile odor components are more likely to be distilled out as the temperature is higher, and temperatures lower than 180°C are not preferred because the efficiency of distilling odor decreases. On the other hand, if the temperature is higher than 270° C., even if the odor components are distilled out, the raw materials are likely to be oxidized and thermally decomposed during the reaction, which is not preferable because the odor will worsen.

In the present invention, the esterification reaction is performed using a reactor equipped with a microbubble generator for supplying microbubbles, a distillation tube, and a stirrer. Although the material and shape of the reactor are not limited, a vertical reactor equipped with a heating jacket that can adjust the internal temperature is preferred.

There are various microbubble generation methods of the microbubble generator, such as an ejector method, a pressurized dissolution method, a cavitation method, a swirling flow method, an ultrasonic method, and an ultrafine pore method.Which method is used in the present invention? You can.

The inert gas supplied in the present invention may be nitrogen, carbon dioxide, helium, argon, or a mixture thereof, but nitrogen is preferred from the viewpoint of cost effectiveness. The flow rate of the inert gas supplied per liter of reaction liquid is preferably 0.001 to 1 L/min. Although odor is suppressed by setting the flow rate of the inert gas to 0.001 L/min or more, the odor suppressing effect is not significantly improved even if the inert gas is supplied at a flow rate exceeding 1 L/min.

Although specific examples are shown below, the present invention is not limited to the following examples.

[Example 1]
In a 1 L reactor equipped with a microbubble generator, a distillation tube, a thermometer, a heating jacket, and a stirrer, 96.9 g of polyglycerin (average degree of polymerization 2, hydroxyl value 1352), 644.2 g of oleic acid, and water were placed. 0.07 g of sodium oxide was charged and stirred and mixed. Nitrogen was blown into the reactor at a rate of 0.4 L/min from a microbubble generator, and the internal temperature of the reactor was raised to 227°C. The reaction was continued at this temperature until the acid value became 5 or less. The acid value of the obtained polyglycerol fatty acid ester was 5.0. The acid value was measured according to the standard oil and fat analysis test method. Note that the acid values in Examples 2 and 3 and Comparative Examples 1 and 2 were calculated in the same manner.

[Example 2]
Polyglycerin fatty acid ester was obtained in the same manner as in Example 1 except that the reaction temperature was 250° C. in the esterification reaction of polyglycerin and oleic acid. The acid value of the obtained polyglycerin fatty acid ester was 5.0.

[Example 3]
In the same reactor as in Example 1, 253.1 g of polyglycerin (average degree of polymerization 10, hydroxyl value 888), 504.1 g of isostearic acid, and 0.35 g of sodium hydroxide were charged and mixed with stirring. Nitrogen was blown into the reactor at a rate of 0.4 L/min from a microbubble generator, and the internal temperature of the reactor was raised to 250°C. The reaction was carried out at this temperature until the acid value became 0.5 or less. The acid value of the obtained polyglycerin fatty acid ester was 0.2.

[Comparative example 1]
The microbubble generator used in Example 1 was changed to a glass tube (φ5 mm). The amounts of polyglycerin, oleic acid, and sodium hydroxide charged were the same as in Example 1, and the reaction was carried out at 227° C. while supplying nitrogen from a glass tube at a rate of 0.4 L/min. The acid value of the obtained polyglycerin fatty acid ester was 4.9.

[Comparative example 2]
The microbubble generator used in Example 3 was changed to a glass tube (φ5 mm). The amounts of polyglycerin, isostearic acid, and sodium hydroxide charged were the same as in Example 3, and the reaction was carried out at 250° C. while supplying nitrogen at a rate of 0.4 L/min from a glass tube. The acid value of the obtained polyglycerol fatty acid ester was 0.2.

(Odor evaluation)
40g of each of the polyglycerin fatty acid esters synthesized in Examples 1 to 3 and Comparative Examples 1 and 2 was weighed into a 140mL mayonnaise bottle, heated at 50°C for 30 minutes, and used as an odor evaluation sample. The odor score ranged from 1 to 5, and the odor intensity was evaluated in 0.5 increments, assuming that the larger the value, the stronger the odor intensity. The evaluation was performed by four evaluators with the names of the samples to be evaluated hidden, and the average value was taken as the odor score. The results are shown in Table 1.

It can be seen that even when the average degree of polymerization of polyglycerin and the type of fatty acid are different, odor was suppressed in the example in which microbubbles containing an inert gas were supplied to the reaction liquid compared to the comparative example.

Claims (2)

In the method for producing polyglycerin fatty acid ester in which polyglycerin with an average degree of polymerization calculated from the hydroxyl value of 2 to 20 is reacted with a fatty acid having 8 to 22 carbon atoms, the temperature at which the polyglycerin and fatty acid are reacted is 180 to 270°C. A method for producing polyglycerol fatty acid ester, which is characterized by supplying microbubbles containing an inert gas during the reaction. 2. The method for producing polyglycerol fatty acid ester according to claim 1, wherein the inert gas contained in the microbubbles is nitrogen.