JPH09278740A - Light-color alpha-sulfofatty acid alkyl ester salt and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject nearly white compound improved in quality at increased formation rate in reduced cost through aging process in the presence of a specific discoloration inhibitor. SOLUTION: This nearly white light-color compound is obtained through a sulfonating gas introduction process designed to bring (A) a saturated fatty acid alkyl ester of the formula R1 CH2 COOR2 (R1 is a 6-24C alkyl; R2 is a 1-6C alkyl) into contact with (B) a sulfonating gas and the succeeding aging process designed to eliminate SO3 from the resultant SO3 bimolecular adduct. In this case, at least the aging process is conducted in the presence of one kind of discoloration inhibitor selected from the group consisting of (C) alkyl sulfate, polyoxyethylene alkyl ether sulfate, α-sulfofatty acid alkyl ester salt, α- olefinsulfonic acid salt, straight-chain aykylbenzene sulfonic acid salt, inner olefinsulfonic acid salt and polystyrenesulfonic acid salt and the group consisting of (D) sodium hydroxide, potassium hydroxide and lithium hydroxide.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an α-sulfofatty acid alkyl ester salt and a process for producing the same, and more particularly to a light-colored α-sulfofatty acid alkyl ester salt having a color close to white and a process for producing the same.

[0002]

BACKGROUND OF THE INVENTION α-Sulfo fatty acid alkyl ester salt
One of its uses is a surfactant, especially
Has high detergency, good biodegradability, environmental impact
The performance as a cleaning material is highly evaluated due to its low
Have been. This α-sulfo fatty acid alkyl ester salt
SO fatty acid alkyl ester _ThreeSulfonated by
And then neutralized with alkali
It is.

[0003] The sulfonation mechanism of fatty acid alkyl esters is described in Smith and Stirton: JAO.
CS vol. 44, P. 405 (1967) and Schmi
d, Baumann, Stein, Dolhaine: Proceeding of the W
orld Surfactants Congress Munchen, vol. Two,
P. 105, Gel-nhausen, Kurle (1984) and H.
Yoshimura: Oil Chemistry (JJOCS), 41, 10 (199
As shown in 2), the reaction proceeds according to the following reaction scheme.

[0004]

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In this sulfonation reaction, when the fatty acid alkyl ester is reacted with SO ₃ , it is efficient if the SO ₃ directly reacts with the α-position of the fatty acid ester to produce α-sulfo fatty acid alkyl ester. Actually, a reaction such as insertion into the alkoxy group occurs first, and SO ₃
A one-molecule adduct (hereinafter abbreviated as a one-molecule adduct) is produced. In the next step, it further reacts with SO ₃ to introduce a sulfone group at the α-position, thereby producing a SO ₃ biadduct (hereinafter abbreviated as a biadduct). Subsequently, SO ₃ inserted into the alkoxy group is eliminated to form an α-sulfofatty acid alkyl ester.

[0006] Here, the reaction proceeds rapidly until the above-mentioned step of forming the bimolecular adduct, but SO ₃ is eliminated from the bimolecular adduct to form an α-sulfofatty acid alkyl ester. Since it is very slow, it is necessary to use an excessive amount of sulfonation gas such as SO ₃ gas in the actual reaction. Further, it is necessary to promote the reaction from the saturated fatty acid alkyl ester to the bimolecular adduct formation step while introducing the sulfonated gas, and then provide an aging step to promote the elimination of SO ₃ .

In order to obtain the α-sulfofatty acid alkyl ester salt, the α-sulfofatty acid alkyl ester salt is obtained from the α-sulfofatty acid alkyl ester by neutralizing with an alkali after the aging step. However, the α-sulfofatty acid alkyl ester produced by the conventional method is markedly colored, and thus the α-sulfofatty acid alkyl ester salt obtained after alkali neutralization is also colored. When used as a detergent material, since the α-sulfofatty acid alkyl ester salt cannot be made into a product in a colored state, before or after this neutralization step, a bleaching step under severe conditions with hydrogen peroxide or the like is required. It is generally done.

That is, a conventional α-sulfofatty acid alkyl ester salt is produced through a sulfonation reaction of a fatty acid alkyl ester by a sulfonating gas introduction step and an aging step, followed by a neutralization step by alkali neutralization and a bleaching step. Is done. Then, during these steps, a part of the ester bond is cleaved, so that the by-production of α-sulfofatty acid or α-sulfofatty acid disoda is unavoidable. Since the above-mentioned by-products have low detergency as a detergent active ingredient and poor water solubility, when these substances are produced in large amounts, it is possible to efficiently obtain α-sulfofatty acid alkyl ester salts suitable for detergents. Becomes difficult. Therefore,
The bleaching step which is not directly related to the production of the α-sulfofatty acid alkyl ester salt is preferably simplified or omitted as much as possible because the production of these by-products can be prevented.

On the other hand, one of the causes of the coloring of the α-sulfofatty acid alkyl ester described above is due to the presence of an excessive sulfonated gas. It has also been confirmed that this coloring proceeds particularly during the aging step. However, it is essential that this ripening step be performed sufficiently to suppress by-products. That is, the α-sulfofatty acid alkyl ester is converted into an α-sulfofatty acid alkyl ester salt by neutralization with an alkali after the aging step, and at this time, when the above-mentioned bimolecular adduct remains,
For example, the reaction shown in the following (II) occurs by alkali neutralization of sodium hydroxide or the like, and α-sulfofatty acid disoda having poor detergency and water solubility is produced. That is, when the SO ₃ elimination reaction in the aging step is insufficient and the neutralization is performed in a state where the bimolecular adduct is present in a large amount in the sulfonation reaction product, α-sulfofatty acid disoda is generated, It becomes difficult to obtain physical properties as a surfactant, for example, preferable detergency and penetrating power. Therefore, the most desired α
-The method for producing a sulfo fatty acid alkyl ester salt is a method capable of sufficiently performing the aging step, increasing the reaction rate, and simplifying or omitting the bleaching step. This is a method capable of producing an α-sulfofatty acid alkyl ester salt from an α-sulfofatty acid alkyl ester not containing.

[0010]

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Regarding the method for obtaining this light-colored α-sulfofatty acid alkyl ester salt, an inorganic sulfate (Japanese Patent Application Laid-Open No.
-43716), fatty acid amides (WO 90039)
67, pyridine (DE 4030852), thiodiglycol diester (DE Publication 422).
(4735 gazette), etc., the method of performing a sulfonation reaction in the coexistence is proposed. However, when a fatty acid amide is used, a sufficient effect cannot be obtained unless the addition amount is large, and when pyridine is used, there is a problem in terms of odor,
Further, other methods have not always been satisfactory in terms of reaction rate and color tone improving effect.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a light-colored .alpha.-sulfofatty acid alkyl ester salt having a near-white color and a method for producing the same.

[0013]

Means for Solving the Problems The present inventors have found that, when a sulfonation reaction of a saturated fatty acid alkyl ester is carried out, at least during the aging step thereof, a specific coloring inhibitor is allowed to coexist with the α-sulfofatty acid alkyl ester. Found that the production speed of
The present invention has been completed.

That is, a saturated sulfonic acid alkyl ester represented by the following general formula (I) and a sulfonation gas introducing step of bringing the sulfonation gas into contact with each other, and an SO ₃ bimolecular adduct after the sulfonation gas introducing step In the method for producing an α-sulfofatty acid alkyl ester salt having a aging step of desorbing SO ₃ , at least the aging step is carried out in the presence of at least one coloring inhibitor selected from the following Group A or Group B: This is the means for solving the above problems. _{R 1 CH 2 COOR 2 ··· (} I) ( wherein, R ₁ represents an alkyl group having 6 to 24 carbon atoms, R ₂ represents an alkyl group having 1 to 6 carbon atoms) A groups: alkyl sulfates , Polyoxyethylene alkyl ether sulfate, α-sulfo fatty acid alkyl ester salt,
α-Olefin sulfonate, linear alkyl benzene sulfonate, inner olefin sulfonate, polystyrene sulfonate Group B: sodium hydroxide, potassium hydroxide, lithium hydroxide

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The method for producing an α-sulfofatty acid alkyl ester salt of the present invention comprises a sulfonating gas introduction step, an aging step,
It consists of a neutralization step, in particular the color tone of the α-sulfofatty acid alkyl ester obtained after the aging step is improved,
As a result, a pale white α-sulfofatty acid alkyl ester salt can be obtained. This α-sulfofatty acid alkyl ester salt and its production method include a sulfonation gas introduction step of bringing a saturated fatty acid alkyl ester represented by the following general formula (I) into contact with a sulfonation gas, and the sulfonation gas introduction step. after the SO ₃ bimolecular adduct and a ripening step of the SO ₃ desorbed α-
In the method for producing a sulfo fatty acid alkyl ester salt, at least the aging step is performed in the presence of at least one coloring inhibitor selected from the following Group A or Group B. _{R 1 CH 2 COOR 2 ··· (} I) ( wherein, R ₁ represents an alkyl group having 6 to 24 carbon atoms, R ₂ represents an alkyl group having 1 to 6 carbon atoms) A groups: alkyl sulfates , Polyoxyethylene alkyl ether sulfate, α-sulfo fatty acid alkyl ester salt,
α-Olefin sulfonate, linear alkyl benzene sulfonate, inner olefin sulfonate, polystyrene sulfonate Group B: sodium hydroxide, potassium hydroxide, lithium hydroxide

In the above-mentioned saturated fatty acid alkyl ester, the fatty acid residue has 6 to 24 carbon atoms, the alcohol residue has 1 to 6 carbon atoms, and the total carbon number of both is 9 to 26. The alkyl esters of saturated fatty acids include animal fats and oils derived from beef tallow, fish oil, etc., vegetable fats and oils derived from coconut oil, palm oil, soybean oil, etc., and synthetic fatty acids derived from the oxo process of α-olefins. Any of alkyl esters and the like may be used, and there is no particular limitation. These include, for example, methyl or ethyl laurate, methyl or ethyl palmitate, methyl or ethyl stearate, methyl or ethyl hardened tallow fatty acid, methyl or ethyl hardened fish oil fatty acid, methyl or ethyl coconut fatty acid, -Methyl or ethyl fatty acid fatty acid; methyl or ethyl fatty acid palm kernel oil; These saturated fatty acid alkyl esters may be used alone or in a mixture, but the iodine value is preferably 0.5 or less, more preferably 0.1 or less, because the lower the iodine value, the more difficult it is to color during the production process. .

The amount of the coloring inhibitor selected from the above-mentioned group A or group B is 0.1 with respect to the fatty acid alkyl ester.
It is 1 to 10% by weight, preferably 1 to 5% by weight. If the amount is greater than this range, the amount of the coloring inhibitor mixed into the product may increase, and the performance of the surfactant may decrease. If it is less than 0.1, the effect of improving the color tone is hardly recognized. Since the coloring inhibitor is preferably added from the viewpoint of operability from the viewpoint of operability, it is customary to mix it before introducing the sulfonation gas, but even if it is added and mixed after the sulfonation gas introduction step, that is, before the aging step. The progress of coloring during the aging step can be suppressed.

The coloring inhibitor contained in the group A is an organic sulfate or an organic sulfonate, and specific examples thereof include the following (1) to (7). (1) Alkyl sulphate (2) Polyoxyethylene alkyl ether sulphate (average alkyl group carbon number 8-20, ethylene oxide (EO)
Average addition mole number 1 to 20) (3) α-sulfo fatty acid alkyl ester salt (average fatty acid residue carbon number 6 to 24, ester alkyl group carbon number 1
~ 6) (4) α-Olefin sulfonate (average carbon number 8 ~ 2
2) (5) Linear alkylbenzene sulfonate (average carbon number of alkyl group is 1 to 20) (6) Inner olefin sulfonate (average carbon number 8)
-22) (7) Polystyrene sulfonate (average molecular weight 500-50,
000) In the color suppressor included in the group A, an alkali metal such as sodium or potassium is usually suitable as a counter ion forming a salt. The coloring inhibitor contained in the group B is an alkali metal hydroxide, and specific examples thereof include sodium hydroxide, potassium hydroxide and lithium hydroxide.

The sulfonation method of the present invention can be applied to any of the sulfonation methods such as the thin film sulfonation method and the batch sulfonation method, but the batch sulfonation method is preferable in consideration of the color tone of the α-sulfo fatty acid ester. In consideration of cost and the like at the production level, the thin film sulfonation method is preferable. As the sulfonation gas, SO ₃ gas, fuming sulfuric acid and the like are used, but SO ₃ gas is preferable, and usually an inert gas such as air or nitrogen having a concentration of 3 to 5 is used.
SO ₃ gas diluted to 30% by volume is used, and SO ₃ is used in an amount of 1.0 to 1.5 times mol, preferably 1.1 to 1.3 times mol of the raw material saturated fatty acid ester. If the molar ratio is less than 1.0 times, the sulfonation reaction does not proceed sufficiently. If the molar ratio exceeds 1.5 times, the sulfonation reaction becomes more intense, so that coloring due to local heat becomes remarkable, and the light-colored target product is It is not preferable in terms of obtaining.

The reaction temperature in the sulfonation gas introduction step may be a temperature at which the saturated fatty acid alkyl ester has fluidity. Generally, a temperature from the freezing point to a temperature 100 ° C. higher than the freezing point is applied. It is preferably from the freezing point to a temperature 70 ° C. higher than the freezing point. The reaction time at this time varies depending on the sulfonation method.
It is about 30 seconds and about 10 to 120 minutes in the batch sulfonation method.

In the aging step for advancing the SO ₃ elimination reaction from the bimolecular adduct, the reaction temperature is 70 to 90.
C is appropriate. If it is lower than this, the reaction does not proceed rapidly, and if it is higher, the product is markedly colored. The reaction time at this time is preferably 10 to 120 minutes.

In order to use the α-sulfofatty acid alkyl ester formed after the aging step as a surfactant, a neutralization step with an alkali is required. This neutralization step is
The reaction mixture of the sulfo fatty acid alkyl ester and the alkali is preferably carried out in an acidic or weakly alkaline range, and when it is carried out under strong alkaline, the ester bond may be easily broken. As the alkali used, for example, an alkali metal hydroxide, ammonia, ethanolamine or the like is used. Before or after this neutralization step, a bleaching step can be performed, if necessary.

A summary of the embodiments of the present invention is as follows. In the present invention, the coloring inhibitor selected from the above-mentioned Group A or Group B may be present at least in the aging step, and is preferably 0.1 to the saturated fatty acid alkyl ester and the saturated fatty acid alkyl ester. 1
A method of performing a maturing step of desorbing SO ₃ from a bimolecular adduct after contacting a mixture with 0% by weight of the coloring inhibitor with SO ₃ gas at a reaction temperature equal to or higher than the freezing point of the saturated fatty acid alkyl ester. Is used.

In the coloring inhibitor used in the present invention, the group A is an organic sulfate or an organic sulfonate, and specifically, the following (1) to (7) are preferably used. it can. (1) Alkyl sulphate (2) Polyoxyethylene alkyl ether sulphate (average alkyl group carbon number 8-20, ethylene oxide (EO)
Average addition mole number 1 to 20) (3) α-sulfo fatty acid alkyl ester salt (average fatty acid residue carbon number 6 to 24, ester alkyl group carbon number 1
~ 6) (4) α-Olefin sulfonate (average carbon number 8 ~ 2
2) (5) Linear alkylbenzene sulfonate (average carbon number of alkyl group is 1 to 20) (6) Inner olefin sulfonate (average carbon number 8)
-22) (7) Polystyrene sulfonate (average molecular weight 500-50,
000) In the color suppressor included in the group A, an alkali metal such as sodium or potassium is usually suitable as a counter ion forming a salt. The coloring inhibitor contained in the group B is an alkali metal hydroxide, and specific examples thereof include sodium hydroxide, potassium hydroxide and lithium hydroxide. The amount of the coloring inhibitor added is 0.1 to 10% by weight, more preferably 1% by weight, based on the saturated fatty acid alkyl ester.
~ 5% by weight.

As the sulfonation gas, SO ₃ gas is preferable, and SO ₃ gas diluted with an inert gas such as air or nitrogen to a concentration of 3 to 30% by volume is particularly preferably used. The reaction temperature of the sulfonation gas introduction step is carried out at a temperature equal to or higher than the freezing point of the saturated fatty acid alkyl ester, more preferably from the freezing point to 70 ° C. higher than the freezing point. The reaction temperature in the aging step is preferably 70 to 90 ° C. The iodine value of the saturated fatty acid alkyl ester of the raw material is
It is preferably 0.5 or less, more preferably 0.1 or less.

After the aging step, neutralization with an alkali under acidic or weakly alkaline conditions gives an α-sulfofatty acid alkyl ester salt suitable as a surfactant. The α-sulfofatty acid alkyl ester salt obtained by the production method of the present invention is produced through an aging step carried out in the presence of at least the coloring inhibitor selected from Group A or Group B, preferably the saturated fatty acid alkyl ester. And 0.1 to 1 relative to the saturated fatty acid alkyl ester
After contacting a mixture of 0% by weight of the coloring inhibitor with SO ₃ gas at a reaction temperature equal to or higher than the freezing point of the saturated fatty acid alkyl ester, at least through an aging step of desorbing SO ₃ from the bimolecular adduct. It is manufactured.

[0027]

EXAMPLES The present invention will be described in more detail below with reference to examples.
However, the technical scope of the present invention is limited by this.
Not. (Examples 1 to 7, Comparative Examples 1 to 3) Iodine value of 0.08 is shown.
Methyl myristate (raw material) as shown in Table 1 and Table 2
Mixed with various coloring inhibitors (added to anything for Comparative Example 1)
No), jacket cooling, 300 ml glass with stirrer
Using a reactor, while maintaining the temperature at 80 ℃, N _Twogas
1.2 times mol of anhydrous sulfuric acid gas diluted to 20% by volume with
(For methyl myristate) at a constant rate for 60 minutes
Then, after introducing the entire amount, continue stirring for 30 minutes while maintaining the temperature at 85 ° C.
Methyl α-sulfomyristate (α-sulfo fatty acid
Alkyl ester) was prepared. In Tables 1 and 2, the coloring
The amount of inhibitor added is based on methyl myristate (raw material)
Weight percentage.

(Examples 8 to 10) Using a continuous thin film type sulfonation apparatus made of stainless steel, methyl laurate / methyl myristate / methyl palmitate (mixing weight ratio 3/6 / 1) Mixed solution (raw material)
With SO ₃ gas diluted to 5% by volume with dry air,
The sulfonation gas introduction step was performed under the condition of a reaction temperature of 80 ° C. This reaction product was sampled in a 300 ml glass container, and 5% by weight of the coloring inhibitor shown in Table 3 was added to the equivalent amount of the starting material of the sampled reaction product at 85 ° C.
An aging step was performed under the condition of 60 minutes to produce α-sulfofatty acid alkyl ester.

The above Examples 1 to 10 and Comparative Examples 1 to 3
In, the reaction rate of the raw material was determined, and the color tone of the obtained α-sulfofatty acid alkyl ester was measured as follows. After the aging step under the above conditions, the color tone was adjusted to 4 by adding a 5% by weight ethanol solution of α-sulfofatty acid alkyl ester.
Measurement was carried out with a Klett photometer using a No. 42 blue filter with an optical path length of 0 mm.

The results are shown together in Tables 1 to 3. In Examples 1 to 10 according to the present invention, the effect of improving the color tone of the α-sulfofatty acid alkyl ester was found as compared with Comparative Examples 1 to 3. In addition, in Examples 1 to 7 and Comparative Examples 1 to 3 by the same raw material and experimental method, in Examples 1 to 7, the reaction rate of the raw materials was high and the production rate of α-sulfofatty acid alkyl ester was increased. Was confirmed. Further, in Examples 8 to 10, it was confirmed that the effect of improving the color tone of the α-sulfofatty acid alkyl ester can be obtained even when the coloring inhibitor is added before the aging step. When the α-sulfofatty acid alkyl esters of Examples 1 to 10 and Comparative Examples 1 to 3 thus obtained were each neutralized by a conventional method, the color tone did not change.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

INDUSTRIAL APPLICABILITY According to the present invention, a saturated fatty acid alkyl ester is sulfonated in the presence of a specific organic sulfate, organic sulfonate or alkyl metal hydroxide. The speed can be increased, and a light-colored α-sulfofatty acid alkyl ester salt close to white can be obtained. Therefore, the bleaching step can be simplified or omitted as necessary, the production of by-products can be suppressed, and the quality and cost can be improved.

Claims (2)

[Claims] 1. A sulfonation gas introduction step of bringing a saturated fatty acid alkyl ester represented by the following general formula (I) into contact with a sulfonation gas, and an SO ₃ bimolecular adduct after the sulfonation gas introduction step. In the method for producing an α-sulfofatty acid alkyl ester salt having a aging step of desorbing SO ₃ , at least the aging step is performed in the presence of at least one coloring inhibitor selected from the following Group A or Group B: And a method for producing a light-colored α-sulfofatty acid alkyl ester salt. _{R 1 CH 2 COOR 2 ··· (} I) ( wherein, R ₁ represents an alkyl group having 6 to 24 carbon atoms, R ₂ represents an alkyl group having 1 to 6 carbon atoms) A groups: alkyl sulfates , Polyoxyethylene alkyl ether sulfate, α-sulfo fatty acid alkyl ester salt,
α-Olefin sulfonate, linear alkyl benzene sulfonate, inner olefin sulfonate, polystyrene sulfonate Group B: sodium hydroxide, potassium hydroxide, lithium hydroxide 2. A sulfonation gas introducing step of bringing a saturated fatty acid alkyl ester represented by the following general formula (I) into contact with a sulfonation gas, and a SO ₃ bimolecular adduct after the sulfonation gas introducing step. An α-sulfofatty acid alkyl ester salt produced through at least a aging step of desorbing SO ₃ , wherein at least the aging step is the presence of at least one coloring inhibitor selected from the following Group A or Group B: A light-colored α-sulfofatty acid alkyl ester salt produced by the following process. _{R 1 CH 2 COOR 2 ··· (} I) ( wherein, R ₁ represents an alkyl group having 6 to 24 carbon atoms, R ₂ represents an alkyl group having 1 to 6 carbon atoms) A groups: alkyl sulfates , Polyoxyethylene alkyl ether sulfate, α-sulfo fatty acid alkyl ester salt,
α-Olefin sulfonate, linear alkyl benzene sulfonate, inner olefin sulfonate, polystyrene sulfonate Group B: sodium hydroxide, potassium hydroxide, lithium hydroxide