JP2014210726A - METHOD FOR PRODUCING α-SULFO-FATTY ACID ALKYL ESTER SALT - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an α-sulfo-fatty acid alkyl ester salt capable of easily producing a sufficiently light colored α-sulfo-fatty acid alkyl ester salt.SOLUTION: There is provided a method for producing an α-sulfo-fatty acid alkyl ester salt which comprises: a step of reacting a fatty acid alkyl ester with a sulfonating agent to obtain a sulfonated product; a step of reacting the sulfonated product with a lower alcohol to obtain an esterified product; and a step of neutralizing the esterified product with an alkaline substance, wherein before the neutralization step, the method comprises a step of irradiating the sulfonated product or the esterified product with ultraviolet rays having a wavelength in the range of 280 to 400 nm in the presence of at least one inorganic powder of an inorganic silicon compound and an inorganic sulfate compound.

Description

  The present invention relates to a method for producing an α-sulfo fatty acid alkyl ester salt which produces an α-sulfo fatty acid alkyl ester salt using a fatty acid alkyl ester as a raw material.

α-Sulfo fatty acid alkyl ester salts are used as surfactants, and are particularly used in various detergents because of their high detergency, good biodegradability and little impact on the environment.
The production method of the α-sulfo fatty acid alkyl ester salt includes a sulfonation step in which the fatty acid alkyl ester is sulfonated with a sulfonating agent, and an esterification in which a lower alcohol is added to the sulfonated product obtained in the sulfonation step. A method having a step and a neutralization step of neutralizing an esterified product obtained in the esterification step with an alkaline substance is known (for example, see Patent Documents 1 and 2).

By the way, in a sulfonation process, in order to produce | generate a colored substance as a by-product, the sulfonated product obtained by the sulfonation process is colored. For this reason, in order to obtain an α-sulfo fatty acid alkyl ester salt having a light color and a good color tone, it was sometimes bleached with hydrogen peroxide after the neutralization step (Patent Document 3).
However, hydrogen peroxide is highly reactive and difficult to handle, and bleaching with hydrogen peroxide causes a decomposition reaction and by-produces short-chain fatty acids and methyl esters, resulting in a strong odor. There was. Therefore, there has been a demand for a method for lightening α-sulfo fatty acid alkyl ester salts that do not use hydrogen peroxide.

Patent Document 4 discloses a method for lightening the α-sulfo fatty acid alkyl ester salt by removing impurities from the fatty acid alkyl ester using an adsorbent and then adding a color inhibitor in the sulfonation step. .
Patent Document 5 discloses a method for irradiating a higher alcohol alkoxylate sulfate salt with ultraviolet light in the presence of titanium oxide as a method for improving the color tone of the higher alcohol alkoxylate sulfate salt.

Japanese Patent Laid-Open No. 9-278739 JP 2001-64248 A JP 9-12533 A JP 2005-171137 A Japanese Patent Laid-Open No. 10-168053

However, the method described in Patent Document 4 is insufficient in lightening the α-sulfo fatty acid alkyl ester salt.
Moreover, since the high concentration α-sulfo fatty acid alkyl ester salt has low transparency, even if the method described in Patent Document 5 is applied to the α-sulfo fatty acid alkyl ester salt, it cannot be lightened. If the α-sulfo fatty acid alkyl ester salt is diluted, the transparency is improved and it can be lightened by ultraviolet irradiation, but it needs to be concentrated again and is wasteful and impractical.
The subject of this invention is providing the manufacturing method of the alpha-sulfo fatty-acid alkylester salt which can manufacture easily the alpha-sulfo fatty-acid alkylester salt fully lightened.

  The method for producing an α-sulfo fatty acid alkyl ester salt of the present invention comprises a sulfonation step of reacting a fatty acid alkyl ester with a sulfonating agent to obtain a sulfonated product, and an ester obtained by reacting the sulfonated product with a lower alcohol to obtain an esterified product. And a neutralization step of neutralizing the esterified product with an alkaline substance, and before the neutralization step, the sulfonated product or the esterified product is added with at least one inorganic silicate compound or inorganic sulfate compound. In the presence of the powder, an ultraviolet irradiation step of irradiating ultraviolet rays having a wavelength in the range of 280 to 400 nm is included.

  According to the method for producing an α-sulfo fatty acid alkyl ester salt of the present invention, a sufficiently light-colored α-sulfo fatty acid alkyl ester salt can be easily produced.

The method for producing an α-sulfo fatty acid alkyl ester salt of the present invention includes a sulfonation step, an esterification step, an ultraviolet irradiation step, and a neutralization step.
Hereinafter, each step will be described.

<Sulfonation step>
The sulfonation step is a step of sulfonating a fatty acid alkyl ester with a sulfonating agent to obtain a sulfonated product containing an α-sulfo fatty acid alkyl ester.
The fatty acid alkyl ester to be sulfonated is a compound represented by the following general formula (I).
R ¹ —CH ₂ —COOR ² (I)

In the formula (I), R ¹ may be linear or branched, and is preferably an alkyl group having 6 to 24 carbon atoms, and more preferably a linear chain having 10 to 18 carbon atoms. An alkyl group is more preferred.
In formula (I), R ² may be linear or branched and is preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 or 2 carbon atoms. preferable.

The fatty acid of the fatty acid alkyl ester may be any of animal fats and oils such as beef tallow and fish oil; vegetable oils and fats such as coconut oil, palm oil and soybean oil; and synthetic fatty acid alkyl esters derived from the oxo method of α-olefins. There is no particular limitation.
Specific examples of fatty acid alkyl esters include methyl laurate, ethyl or propyl; methyl myristate, ethyl or propyl; methyl palmitate, ethyl or propyl; methyl stearate, ethyl or propyl; methyl beef tallow fatty acid methyl, ethyl or propyl Examples include: hardened fish oil fatty acid methyl, ethyl or propyl; coconut oil fatty acid methyl, ethyl or propyl; palm oil fatty acid methyl, ethyl or propyl; palm kernel oil fatty acid methyl, ethyl or propyl;
These fatty acid alkyl esters may be used alone or in combination of two or more.

It is known that the higher the degree of unsaturation of the fatty acid alkyl ester as the raw material, the higher the degree of coloring of the α-sulfo fatty acid alkyl ester salt as the final product. For this reason, a fatty acid alkyl ester whose iodine value has been reduced by hydrogenation is usually used.
The iodine value of the fatty acid alkyl ester is preferably from 0.01 to 0.3, more preferably from 0.02 to 0.2. If the iodine value is 0.3 or less, it becomes easier to obtain a lighter α-sulfo fatty acid alkyl ester salt. Moreover, the odor derived from the impurities contained in the fatty acid alkyl ester can also be suppressed.
The lower the iodine value of the fatty acid alkyl ester, the easier it is to obtain a light α-sulfo fatty acid alkyl ester salt. However, the higher the amount of hydrogenation, the longer the time required for hydrogenation and the higher the productivity. In addition, excessive hydrogenation is expensive. Therefore, considering the balance between color tone and cost, the iodine value is preferably 0.01 or more.
In addition, when using a different kind of fatty acid alkyl ester together as a raw material, it is preferable that the iodine value of a mixture is in the said range.

  The iodine value of the fatty acid alkyl ester is a value obtained by converting the amount of halogen that reacts with 100 g of the fatty acid alkyl ester into the number of grams of iodine, and is measured according to the standard oil analysis test method 2.3.4.1-1996. .

As the sulfonating agent, a sulfonated gas can be used, and specific examples include SO ₃ gas and fuming sulfuric acid. Among them, SO ₃ gas is preferred, usually, SO ₃ gas diluted to a concentration 3-30% by volume with an inert gas such as air or nitrogen is used.

As the sulfonation method, any sulfonation method such as a thin film type sulfonation method or a batch type sulfonation method may be used.
In addition, as the sulfonation reaction method, methods such as a tank reaction, a film reaction, and a tube-type gas-liquid mixed phase reaction are used. In particular, in the batch sulfonation method, a tank reaction is suitable.
Hereinafter, an example of a method for sulfonating a fatty acid alkyl ester by a tank type reaction will be described.

  First, a fatty acid alkyl ester is charged into a tank reactor and stirred to obtain a mixture. Next, a sulfonated gas is introduced into the mixture, preferably at a constant flow rate, and a plurality of bubbles are generated from the gas sparger and dispersed in the mixture by the rotation of a stirrer to perform a sulfonation reaction.

  The introduction amount of the sulfonated gas is preferably 1.0 to 1.5 times mol, more preferably 1.1 to 1.3 times mol of the fatty acid alkyl ester. If the introduction amount of the sulfonated gas is 1.0 times mol or more, the sulfonation reaction proceeds sufficiently. On the other hand, if the introduction amount of the sulfonated gas is 1.5 times mol or less, the runaway of the sulfonation reaction can be suppressed, so that coloring due to local heat is suppressed and a light-colored target product is easily obtained. .

  The reaction temperature for introducing the sulfonated gas may be any temperature at which the fatty acid alkyl ester has fluidity. Generally, the temperature from the freezing point of the fatty acid alkyl ester to a temperature 100 ° C. higher than the freezing point is applied. Preferably, the temperature is from the freezing point to a temperature 70 ° C. higher than the freezing point. The reaction time for sulfonation is about 10 to 240 minutes.

When sulfonation is performed by the thin film sulfonation method, for example, the following is performed.
The cylindrical reaction tube is heated, and the fatty acid alkyl ester is allowed to flow along the inner wall of the reaction tube from above the reaction tube. At the same time, a sulfonation gas is supplied into the reaction tube from above the reaction tube and brought into contact with the fatty acid alkyl ester to carry out the sulfonation reaction.

The amount of sulfonated gas introduced and the reaction temperature in the thin film sulfonation method are the same as in the case of the tank reaction described above.
The reaction time is preferably 5 to 30 seconds.

When the fatty acid alkyl ester and the sulfonated gas come into contact with each other in the sulfonation step, first, a reaction in which SO ₃ is inserted into the alkoxy group of the fatty acid alkyl ester occurs, and a single-molecule adduct with one molecule of SO ₃ added is generated. Furthermore, it reacts with SO ₃ and a sulfone group is introduced at the α-position to form a bimolecular adduct having bimolecular SO ₃ added thereto. Finally, SO ₃ inserted into the alkoxy group is eliminated, and the following general formula (II ) (Α-sulfo fatty acid alkyl ester). In addition to the α-sulfo fatty acid alkyl ester, the sulfonated product obtained in the sulfonation step contains a bimolecular adduct of SO ₃ , an unreacted fatty acid alkyl ester, and other by-products.
R ¹ —CH (SO ₃ H) —COOR ² (II)
[(II) wherein, ^{R 1} is the same as ^{R 1} in formula (I), ^{R 2} is the same as ^{R 2} in formula (I). ]

The sulfonation step may have an aging operation as necessary after the gas contact operation. From the viewpoint of improving the yield of the α-sulfo fatty acid alkyl ester salt, it is preferable to have an aging operation.
The aging operation is a step of promoting the desorption of SO ₃ from the bimolecular adduct generated by the gas contact operation while maintaining the predetermined temperature after the gas contact operation.
The aging operation is performed, for example, by stirring in a reactor in which the fatty acid alkyl ester and the sulfonated gas are contacted in the tank-type reaction described above. For example, when a film type reaction, a tube-type gas-liquid mixed phase reaction, or the like is used for the sulfonation reaction method, the sulfonated product is transferred to another tank-type reactor and subjected to an aging operation.

The reaction temperature (aging temperature) in the aging operation is preferably 70 to 90 ° C. If the aging temperature is 70 ° C. or higher, the reaction proceeds rapidly. On the other hand, if the aging temperature is 90 ° C. or lower, the coloring of the product can be more effectively suppressed.
The reaction time (aging time) in the aging operation is preferably 10 to 120 minutes.

<Esterification process>
The esterification step is a step in which a lower alcohol is reacted with the sulfonated product obtained in the sulfonation step.
As described above, the sulfonated product obtained in the sulfonation step includes, in addition to the α-sulfo fatty acid alkyl ester, a bimolecular adduct of SO ₃ , an unreacted fatty acid alkyl ester, and other by-products. ing. In particular, since neutralization of the bimolecular adduct results in an α-sulfo fatty acid dialkali salt that does not contribute to the cleaning effect, it is necessary to reduce the content of the bimolecular adduct as much as possible in the detergent application. By having an esterification step, an α-sulfo fatty acid alkyl ester can be generated from the bimolecular adduct, the content of the bimolecular adduct can be lowered, and further the yield of the α-sulfo fatty acid alkyl ester salt can be improved. .
The esterification step is performed, for example, by adding a lower alcohol to the sulfonated product and stirring it while maintaining a predetermined temperature.

As a lower alcohol used for an esterification process, C1-C6 alcohol is preferable and C1-C2 alcohol is more preferable. Among them, the lower alcohol preferably has the same carbon number as that of the alcohol residue of the starting fatty acid alkyl ester.
The addition amount of the lower alcohol is preferably 0.5 to 4 parts by mass with respect to 100 parts by mass of the sulfonated product. If the addition amount of the lower alcohol is 0.5 parts by mass or more, the esterification reaction proceeds sufficiently. Even if the addition amount of the lower alcohol exceeds 4 parts by mass, further esterification reaction hardly proceeds.

The reaction temperature in the esterification step is preferably 50 to 100 ° C.
The reaction time in the esterification step is preferably 5 to 60 minutes.

<Ultraviolet irradiation process>
The ultraviolet irradiation step is a step of irradiating the sulfonated product or the esterified product with ultraviolet rays in the presence of inorganic powder before the neutralization step. By this step, the sulfonated product or esterified product is lightened. Since sulfonated products and esterified products have low viscosity and can be lightened by irradiating the sulfonated product or esterified product with ultraviolet rays, the resulting α-sulfo fatty acid alkyl ester salt can also be lightened. On the other hand, when the neutralized product after the neutralization step having high viscosity and low transparency is irradiated with ultraviolet rays, it is difficult to lighten the α-sulfo fatty acid alkyl ester salt.
In the case of irradiating the sulfonated product with ultraviolet rays, the ultraviolet ray may be irradiated after the sulfonation step and before the esterification step. In the case of irradiating the esterified product with ultraviolet rays, the ultraviolet rays are applied after the esterification step and before the neutralization step. May be irradiated.

The ultraviolet rays in the present invention are in the wavelength range of 280 to 400 nm. In the present invention, the ultraviolet ray in the wavelength range of 280 to 400 nm is an ultraviolet ray containing at least a part of light rays in the wavelength range of 280 to 400 nm. Simultaneously with the ultraviolet light, the sulfonated product or the esterified product may be irradiated with light having a wavelength outside the above range. However, it is preferable to irradiate only light having a wavelength in the range of 280 to 400 nm because light having a wavelength outside the above range hardly contributes to lightening.
As the ultraviolet ray used in the present invention, UV-B having a wavelength of 280 to 315 nm is preferable because the effect of lightening the sulfonated product or esterified product is high. In order to irradiate UV-B, a UV-B lamp may be used.

When irradiating UV-B, the irradiation time of ultraviolet rays is preferably 1 to 10 hours. 50-100 degreeC is preferable and the temperature at the time of irradiation has more preferable 60-90 degreeC. If the temperature at the time of ultraviolet irradiation is not less than the lower limit, the handling property of the sulfonated product or esterified product at the time of ultraviolet irradiation can be improved, and if it is not more than the upper limit, coloring by heat can be suppressed and the color can be lighter.
In addition, the irradiation amount of an ultraviolet-ray changes with kinds and content of the coloring substance in a sulfonated substance or esterified substance, and cannot be specified.

  The method of irradiating with ultraviolet rays is not particularly limited. For example, the method of irradiating ultraviolet rays toward the liquid surface of the sulfonated product or esterified product while stirring in a stirring tank, the ultraviolet irradiation device is submerged in the sulfonated product or esterified product. Examples include a method of irradiating ultraviolet rays from the liquid, and a method of irradiating ultraviolet rays in a route through which the sulfonated product or esterified product circulates.

The inorganic powder in the present invention is particles composed of at least one of an inorganic silicic acid compound and an inorganic sulfuric acid compound.
In addition, the inorganic powder in the present invention is insoluble in the α-sulfo fatty acid alkyl ester.
Here, “insoluble” means that 100 g of α-sulfo fatty acid alkyl ester after sulfonation adjusted to 50 ° C. is placed in a 1 L beaker, 10 g of inorganic powder is added, and a precipitate is formed after stirring. It is to appear cloudy.

Examples of the inorganic silicate compound include silicate, orthosilicate, aluminosilicate (zeolite, etc.) and the like.
Examples of the inorganic sulfuric acid compound include sodium sulfate, potassium sulfate, magnesium sulfate and the like.

<Neutralization process>
The neutralization step is a step of neutralizing the esterified product with an alkaline substance. By performing the neutralization step, an α-sulfo fatty acid alkyl ester salt is produced from the α-sulfo fatty acid alkyl ester in the esterified product.

Neutralization can be performed, for example, by bringing an esterified product into contact with an alkaline substance.
Examples of the alkaline substance are those capable of forming a target salt, for example, hydroxides of alkali metals (Group 1 elements) such as sodium hydroxide, carbonates of alkali metals, alkaline earth metals (second Group element) hydroxide, ammonia, ethanolamine and the like.
Examples of the alkali metal include potassium and sodium, and examples of the alkaline earth metal include calcium and magnesium.
Among these, an aqueous solution of sodium hydroxide is preferable as the alkaline substance.

The neutralization temperature in the neutralization step is preferably 30 to 140 ° C.
The neutralization time in the neutralization step is preferably 10 to 60 minutes.
The pH during neutralization is preferably in the acidic or weak alkaline range, specifically in the range of pH 4 to 9, in order to prevent hydrolysis of the produced α-sulfo fatty acid alkyl ester salt.
If neutralization is performed at a pH outside the above range, the ester bond of the α-sulfo fatty acid alkyl ester salt may be easily cleaved.

<Bleaching process>
The production method of the α-sulfo fatty acid alkyl ester salt may have a bleaching step of bleaching the α-sulfo fatty acid alkyl ester salt with hydrogen peroxide as necessary. However, it is preferable not to have a bleaching step from the viewpoint of suppressing by-products that emit odors.

<Effect>
In the method for producing the α-sulfo fatty acid alkyl ester salt, the sulfonated product or esterified product can be lightened by irradiating the sulfonated product or esterified product with ultraviolet rays having the specific wavelength. The α-sulfo fatty acid alkyl ester salt obtained by esterifying and neutralizing the lightened sulfonated product and the α-sulfo fatty acid alkyl ester salt obtained by neutralizing the lightened esterified product are suppressed in coloring. Therefore, according to this production method, a sufficiently light-colored α-sulfo fatty acid alkyl ester salt can be produced. Moreover, the production method is simple because it does not require a dilution operation for lightening.

(Examples 1-5)
Methyl palmitate (product name: Pastel M-16, manufactured by Lion Corporation) and methyl stearate (product name: Pastel M-180, manufactured by Lion Corporation) were mixed at a ratio shown in Table 1. Subsequently, the iodine value was further reduced to 0.3 by further hydrogenation treatment by a conventional method, and a fatty acid methyl ester was obtained.
500 g of the fatty acid methyl ester is charged into a tank-type sulfonation reactor, and a sulfonation gas is added at a reaction molar ratio (SO ₃ / fatty acid methyl ester) = 1.2 and reacted at 80 ° C. for 240 minutes to obtain a sulfonated product. Obtained. The sulfonated product was aged at 80 ° C. for 1 hour to obtain an aged product. Thereafter, 3 parts by mass of methanol was added to 100 parts by mass of the aged product and reacted at 80 ° C. for 60 minutes to obtain an esterified product.
10 parts by mass of the additive (inorganic powder) shown in Table 1 was added to 100 parts by mass of the esterified product with respect to the obtained esterified product. Then, ultraviolet rays were irradiated for 4 hours at 80 ° C. using a UV-B lamp (manufactured by Sankyo Electric Co., Ltd., wavelength range 280 to 400 nm, peak wavelength 306 nm) to obtain an α-sulfo fatty acid alkyl ester-containing treated product. .
The obtained α-sulfo fatty acid alkyl ester-containing treatment product is simultaneously and continuously charged with a sodium hydroxide aqueous solution in the vicinity of the stirring blade of the mixer, mixed by stirring and neutralized to obtain an α-sulfo fatty acid alkyl ester salt ( Neutralized product) was obtained.
At that time, the neutralized product was adjusted to have a pH of 7.0 and a solid content concentration of 70% by mass to obtain an α-sulfo fatty acid alkyl ester salt-containing treated product.
The color of the obtained α-sulfo fatty acid alkyl ester salt-containing processed product was measured by the following method. The measurement results are shown in Table 1.

<Color measurement method>
The measurement sample of the α-sulfo fatty acid alkyl ester salt-containing treatment product was dissolved in water so that the solid concentration was 5% by mass, and the insoluble matter was filtered. . The color was measured with a Kret photoelectric meter using a 42 blue filter. The higher the numerical value obtained by measurement, the more colored.

  In the table, MS-3A is aluminosilicate (trade name Molecular Sieve 3A powder, pore diameter 0.3 nm, manufactured by Union Showa Co., Ltd.), and MS-5A is aluminosilicate (Union Showa Co., Ltd., trade name Molecular Sieve 5A). Powder, pore diameter 0.5 nm), MS-13X is aluminosilicate (Union Showa Co., Ltd., trade name Molecular Sieve 13X powder, pore diameter 1 nm), and sodium sulfate is sodium sulfate.

(Comparative Examples 1-12)
Except having changed manufacturing conditions like Tables 2-4, it carried out similarly to Examples 1-5, and obtained the alpha-sulfo fatty-acid alkylester salt containing processed material. In the obtained α-sulfo fatty acid alkyl ester salt-containing processed product, the color was measured in the same manner as in the above example. The measurement results are shown in Tables 2-4.
In Table 3, “TMU” refers to tetramethylurea, and “DMF” refers to dimethylformamide.

(Examples 6 to 7)
Methyl palmitate (product name: Pastel M-16, manufactured by Lion Corporation) and methyl stearate (product name: Pastel M-180, manufactured by Lion Corporation) were mixed at a ratio shown in Table 5. Subsequently, the iodine value was reduced to 0.5 by further hydrogenation by a conventional method, and purification was performed to obtain a fatty acid methyl ester.
Fatty acid methyl ester is supplied to the flow-down type thin film reactor, and SO ₃ gas diluted to 7% by volume with dehumidified air is supplied so that the reaction molar ratio (SO ₃ / fatty acid methyl ester) is 1.2. did.
Under the conditions, sulfonation reaction was performed at 80 ° C. for 10 seconds to obtain a sulfonated product.
The sulfonated product was aged at 80 ° C. for 1 hour to obtain an aged product. Thereafter, 3 parts by mass of methanol was added to 100 parts by mass of the aged product and reacted at 80 ° C. for 60 minutes to obtain an esterified product.
10 parts by mass of the additive (inorganic powder) shown in Table 5 was added to 100 parts by mass of the esterified product with respect to the obtained esterified product. Then, ultraviolet rays were irradiated for 4 hours at 80 ° C. using a UV-B lamp (manufactured by Sankyo Electric Co., Ltd., wavelength range 280 to 400 nm, peak wavelength 306 nm) to obtain an α-sulfo fatty acid alkyl ester-containing treated product. .
The obtained α-sulfo fatty acid alkyl ester-containing treatment product is simultaneously and continuously charged with a sodium hydroxide aqueous solution in the vicinity of the stirring blade of the mixer, mixed by stirring and neutralized to obtain an α-sulfo fatty acid alkyl ester salt ( Neutralized product) was obtained.
At that time, the α-sulfo fatty acid alkyl ester salt-containing treated product was obtained by adjusting the pH of the neutralized product to 7.0 and adjusting the solid content concentration to 70% by mass.
In the obtained α-sulfo fatty acid alkyl ester salt-containing processed product, the color was measured in the same manner as in Examples 1 to 5. Table 5 shows the measurement results.

(Comparative Examples 13-14)
An α-sulfo fatty acid alkyl ester salt-containing treated product was obtained in the same manner as in Examples 6 and 7 except that ultraviolet rays were not irradiated. In the obtained α-sulfo fatty acid alkyl ester salt-containing processed product, the color was measured in the same manner as in the above example. Table 5 shows the measurement results.

(Examples 8 to 9)
Methyl palmitate (product name: Pastel M-16, manufactured by Lion Corporation) and methyl stearate (product name: Pastel M-180, manufactured by Lion Corporation) were mixed at a ratio shown in Table 6. Subsequently, the iodine value was further reduced to 0.1 by further hydrogenation treatment by a conventional method to obtain a fatty acid methyl ester.
Fatty acid methyl ester is charged into a tank-type sulfonation reactor, a sulfonation gas is added at a reaction molar ratio (SO ₃ / fatty acid methyl ester) = 1.2, and the mixture is reacted at 80 ° C. for 240 minutes for sulfonation, A sulfonated product was obtained. An esterified product was obtained from this sulfonated product in the same manner as in Examples 1-5.
10 parts by mass of the additive (inorganic powder) shown in Table 6 was added to 100 parts by mass of the esterified product with respect to the obtained esterified product. Then, ultraviolet rays were irradiated for 4 hours at 80 ° C. using a UV-B lamp (manufactured by Sankyo Electric Co., Ltd., wavelength range 280 to 400 nm, peak wavelength 306 nm) to obtain an α-sulfo fatty acid alkyl ester-containing treated product. .
Subsequently, it neutralized similarly to Examples 1-5, and the alpha-sulfo fatty-acid alkylester salt containing processed material was obtained. In the obtained α-sulfo fatty acid alkyl ester salt-containing processed product, the color was measured in the same manner as in the above example. Table 6 shows the measurement results.

(Comparative Examples 15 to 16)
An α-sulfo fatty acid alkyl ester salt-containing treated product was obtained in the same manner as in Examples 8 and 9 except that ultraviolet rays were not irradiated. In the obtained α-sulfo fatty acid alkyl ester salt-containing processed product, the color was measured in the same manner as in the above example. Table 6 shows the measurement results.

(Comparative Examples 17-21)
In the same manner as in Examples 8 to 9, esterified products were obtained. 10 mass parts of additives shown in Table 7 were added to 100 mass parts of the esterified product with respect to the esterified product. Then, ultraviolet rays were irradiated for 4 hours at 80 ° C. using a sterilizing lamp (manufactured by Sankyo Electric Co., Ltd., wavelength range 250 to 260 nm) to obtain an α-sulfo fatty acid alkyl ester-containing treated product. Subsequently, it neutralized similarly to Examples 1-5, and the alpha-sulfo fatty-acid alkylester salt containing processed material was obtained. In the obtained α-sulfo fatty acid alkyl ester salt-containing processed product, the color was measured in the same manner as in the above example. Table 7 shows the measurement results.

In Examples 1 to 9, in which the esterified product was irradiated with ultraviolet rays using a UV-B lamp in the presence of an inorganic silicic acid compound or an inorganic sulfuric acid compound, the α-sulfo fatty acid alkyl ester salt-containing treated product could be sufficiently lightened. did it.
Comparative Examples 2-7, 13-16, which were not irradiated with ultraviolet light, Comparative Examples 1, 8-12, which were not present with an inorganic silicic acid compound or inorganic sulfuric acid compound when irradiated with ultraviolet light by a UV-B lamp, instead of a UV-B lamp In Comparative Examples 17 to 21 using a sterilizing lamp, lightening of the α-sulfo fatty acid alkyl ester salt-containing treated product was insufficient.

(Comparative Examples 22-23)
In the same manner as in Examples 8 to 9, esterified products were obtained. Next, the esterified product was added simultaneously and continuously with the aqueous sodium hydroxide solution in the vicinity of the stirring blade of the mixer, mixed by stirring and neutralized to obtain an α-sulfo fatty acid alkyl ester salt (neutralized product). . At that time, the pH of the neutralized product was adjusted to 7.0, and the solid content concentration was adjusted to the value shown in Table 8.
Next, 10 parts by mass of the additive (inorganic powder) shown in Table 8 was added to 100 parts by mass of the neutralized product with respect to the obtained neutralized product. Then, ultraviolet rays are irradiated for 4 hours at 80 ° C. using a UV-B lamp (manufactured by Sankyo Electric Co., Ltd., wavelength range 280 to 400 nm, peak wavelength 306 nm) to obtain an α-sulfo fatty acid alkyl ester salt-containing treated product. It was. In the obtained α-sulfo fatty acid alkyl ester salt-containing processed product, the color was measured in the same manner as in Examples 1 to 5. Table 8 shows the measurement results.

  In Comparative Example 22 in which UV-B was irradiated to a high-concentration neutralized product, the additive was not added and the color was the same as that of the neutralized product that was not irradiated with ultraviolet rays. It was enough. In Comparative Example 23 in which UV-B was irradiated on a low-concentration neutralized product, the neutralized product was lightened, but it was inefficient because it had to be concentrated again.

Claims (1)

A sulfonation step of reacting a fatty acid alkyl ester with a sulfonating agent to obtain a sulfonated product, an esterification step of reacting the sulfonated product with a lower alcohol to obtain an esterified product, and neutralizing the esterified product with an alkaline substance A sum process,
Before the neutralization step, an ultraviolet irradiation step of irradiating the sulfonated product or the esterified product with ultraviolet rays having a wavelength of 280 to 400 nm in the presence of at least one inorganic powder of an inorganic silicate compound and an inorganic sulfate compound. A method for producing an α-sulfo fatty acid alkyl ester salt.