JP2000119244A - Production of alpha-sulfofatty acid alkyl ester salt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an α-sulfofatty acid alkyl ester salt, hardly causing corrosion of an apparatus and capable of continuously operating the apparatus for a long period. SOLUTION: When the neutralization reaction product of an α-sulfofatty acid alkyl ester is mixed with an α-sulfofatty acid alkyl ester in a premixer 2 to prepare preliminary mixed slurry and the preliminary mixed slurry is neutralized, in a neutralization mixer 4, with an alkaline aqueous solution fed from an alkaline aqueous solution feed line 5, either one or both of the following treatments A and B are carried out: (A) a temperature in preparation of the preliminary mixed slurry is controlled to <=60 deg.C; and (B) at least contact face with the preliminary mixed slurry is formed from ceramics and/or polytetrafluoroethylene in a production apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an α-sulfofatty acid alkyl ester salt, and more particularly, to a method in which corrosion of an apparatus hardly occurs and a long-term continuous operation is possible.

[0002]

2. Description of the Related Art Alpha-sulfofatty acid alkyl ester salts are used as surfactants, and are particularly highly evaluated for their performance as detergent materials because of their high detergency, good biodegradability and little impact on the environment. ing. However,
Conventionally, there have been the following problems in producing an α-sulfofatty acid alkyl ester salt by neutralizing the α-sulfofatty acid alkyl ester using an aqueous alkali solution. That is, at the time of neutralization, the ester bond of the α-sulfofatty acid ester salt is cleaved, and a water-insoluble α-sulfofatty acid dialkali salt is by-produced. In addition, since the viscosity of a high concentration neutralization reaction product (slurry of α-sulfofatty acid alkyl ester salt) exhibits a specific behavior, the viscosity of the neutralization reaction product obtained in a certain concentration range increases, and Becomes difficult.

[0003] In order to solve these problems,
Various neutralization methods as described below have been proposed. (1) In order to avoid cleavage of the ester bond, a method of neutralizing with a relatively low-concentration aqueous alkali solution, and heating the neutralized slurry to concentrate and increase the concentration (Japanese Patent Application Laid-Open No. SHO 51-51)
-41675). (2) a sulfonated fatty acid ester in the presence of an alcohol of C ₁ ~ _4, and neutralized in two steps with caustic solution, the method of obtaining a high concentration neutralized slurry (JP 57-74
No. 62). (3) By including a predetermined amount of lower alcohol sulfate in the neutralization reaction product, the concentration of the activator can be reduced to 40-6.
Method for preparing a slurry having a low viscosity of 5% by weight
No. 74195).

(4) A method of obtaining a highly concentrated neutralized slurry by a simple concentration operation after neutralization with an alkoxide solution (Japanese Patent Laid-Open No.
290842). (5) The carbon chain length of the fatty acid component of the ester sulfonate salt is limited to C _{16 to} C ₁₈ , and a viscosity reducing agent and water are added at the start of the neutralization reaction to improve the concentration of the neutralization reaction product and decrease the viscosity. A method of obtaining a highly concentrated neutralized slurry by a neutralization method in which the addition of a viscosity reducing agent and water is gradually reduced (Japanese Patent Laid-Open No. 61-118355). (6) A method of obtaining a high-concentration neutralized slurry by neutralizing sulfonic acid with an alkaline substance while adjusting the pH in the presence of water or a neutralization reaction product (Japanese Unexamined Patent Publication No. Hei 5-506439, Japanese Unexamined Patent Publication No. JP-A-5-507777).

[0005]

However, the method described in the above (1) requires a concentration step, which complicates the operation and makes the handling difficult in the concentration step due to an increase in viscosity. was there.
The method described in the above (2) significantly improves the suppression of by-product α-sulfofatty acid dialkaline salt and the increase in the concentration of the slurry, but requires a solvent recovery step since a relatively large amount of alcohol is used. The operation was complicated. Since the method described in the above (4) uses alcohol similarly to the method described in the above (2), there is a problem that an alcohol removing step is required and the operation is complicated. In the methods described in the above (3) and (5), since an additive is used,
There was a limit in increasing the concentration of the main component. Furthermore, the method described in the above (6) has the advantage that it can be directly neutralized and does not require a concentration step or an additive, but the suppression of by-products of α-sulfofatty acid dialkaline salt was not sufficient. In addition, there is a problem that by-concentration of high concentration locally produces by-products of an adhesive α-sulfofatty acid dialkaline salt, which adheres to the neutralization device, and therefore, long-term continuous operation is difficult. .

In order to solve these problems, the present inventors disclosed in Japanese Patent Laid-Open Publication No. Hei 10-53794 that a neutralization reaction product was added to an α-sulfofatty acid alkyl ester and the mixture was sufficiently mixed with, for example, a mixer. To make a high-concentration pre-mixed slurry and neutralize it with a high-concentration aqueous alkali solution.

FIG. 1 shows an example of a neutralizing device used in this method. Hereinafter, a description will be given together with a neutralization operation example. First, an aqueous slurry of α-sulfofatty acid alkyl ester salt (neutralization reaction product) is sent from the recycling line 10.
Is supplied to the premixer 2. Next, the α-sulfofatty acid alkyl ester is supplied from the α-sulfofatty acid alkyl ester supply line 1, and the two are sufficiently mixed in the premixer 2 to form a premixed slurry. The premixed slurry is sent from the premixed slurry supply line 3 to the neutralization mixer 4, and an alkali aqueous solution is supplied from the alkaline aqueous solution supply line 5 to the neutralization mixer 4 for neutralization.
At this time, the neutralization mixer 4 or the recycling line 10
The pH of the neutralized reaction product is measured by a pH measuring means provided in the above section, and an alkaline aqueous solution is supplied while adjusting the supply amount so that the pH falls within a predetermined range.

The neutralized reaction product is withdrawn from the neutralized reaction product withdrawal line 6 by the action of a recycle pump 7 and a withdrawal pump 8, and a part of the neutralized reaction product is discharged to the outside through a discharge line 9, and the remainder is discharged. After being cooled to a predetermined temperature by the heat exchanger 11 by the recycle line 10, it is recycled to the premixer 2 at a fixed ratio, and the above-mentioned operations of adjusting and neutralizing the premixed slurry are repeated. As described above, in the neutralization device, a neutralization loop system including the premixed slurry supply line 3, the neutralization mixer 4, the neutralized material extraction line 6, and the recycle line 10 from the premixer 2 is formed.

According to this method, a high-concentration slurry composed of a high-purity α-sulfofatty acid alkyl ester salt can be obtained with little by-product of the α-sulfofatty acid dialkaline salt. In addition, long-term operation can be performed without the attachment of α-sulfofatty acid dialkaline salt to a neutralization device or the like. Furthermore, there is an advantage that a step of adding and recovering a third component such as a solvent or a viscosity reducing agent, and a step of concentration by using a low-concentration aqueous alkali solution are not required at all. However, when this method was actually performed, corrosion occurred in the premixer 2, the premixed slurry supply line 3, the pump, and the like. For this reason, it is necessary to frequently wash the neutralizing device, and there is a problem that the durability of the neutralizing device is reduced, so that long-term continuous operation is difficult.

The present invention has been made in view of the above circumstances, and has as its object to provide a method for producing an α-sulfofatty acid alkyl ester salt which can be operated continuously for a long period of time. Further, upon neutralization of the α-sulfofatty acid alkyl ester,
It is an object to provide a device in which corrosion of the device hardly occurs. Furthermore, it is possible to solve the above-mentioned problems and to obtain a high-concentration slurry of α-sulfofatty acid alkyl ester salt with a small amount of by-products of α-sulfofatty acid dialkaline salt, and to obtain α-sulfofatty acid alkyl ester salt in a high concentration. -An object of the present invention is to provide a method which does not require the addition of a third component such as a solvent or a viscosity reducing agent or the concentration step by using a low-concentration aqueous alkali solution, without adhesion of a sulfo fatty acid dialkaline salt.

[0011]

In order to solve the above-mentioned problems, in the present invention, a premixed slurry is prepared by mixing a neutralization reaction product of α-sulfofatty acid alkyl ester and α-sulfofatty acid alkyl ester. Then, in neutralizing this pre-mixed slurry, the temperature during the following (A) and (B) (A) pre-mixed slurry adjustment is controlled to 60 ° C. or less. (B) In the manufacturing apparatus, at least the contact surface with the premixed slurry is formed from ceramics and / or polytetrafluoroethylene. A method for producing an α-sulfofatty acid alkyl ester salt, characterized by carrying out either one or both treatments, is a means for solving the above problems.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The production method of the present invention is to obtain, for example, an α-sulfofatty acid alkyl ester salt by sequentially performing the following steps (a) to (d). (A) a sulfonating gas introduction step of bringing a fatty acid alkyl ester into contact with a sulfonating gas; (B) Aging step. (C) an esterification step of esterification with a lower alcohol. (D) a neutralization step of neutralizing with an alkali to obtain an α-sulfofatty acid alkyl ester salt from the α-sulfofatty acid alkyl ester.

The steps (a) to (c) are steps for producing an α-sulfofatty acid alkyl ester from a fatty acid alkyl ester. That is, regarding the sulfonation mechanism of fatty acid alkyl ester, Smith and Stirto
n: JAOCS vol. 44, p. 405 (1967) and
Schmid, Baumann, Stein, Dolhaine: Proceeding of
the World Surfactants Congress Munchen, vol.
2, p. 105, Gelnhausen, Kurle (1984) and H. Yoshimura: Oil Chemistry (JJOCS), 41, 10 (1
992), the reaction proceeds according to the following reaction scheme.

[0014]

Embedded image

As shown in this reaction scheme,
When a fatty acid alkyl ester is sulfonated, a reaction in which SO ₃ is inserted into an alkoxy group occurs first, and a single molecule SO ₃ adduct is produced. Then, in the next stage, it is further introduced sulfonic group into position by reaction with SO ₃ alpha, SO ₃ bimolecular adduct is produced. Finally, the SO ₃ inserted into the alkoxy group is eliminated to produce an α-sulfofatty acid alkyl ester.

Since the reaction rate of this reaction is slow as a whole, as described above, the fatty acid alkyl ester is brought into contact with a sulfonating gas such as SO ₃ gas. (B) aging step is provided, and (c) in the esterification step,
The remaining SO ₃ biadduct is esterified with a lower alcohol, and the elimination of SO ₃ inserted into the alkoxy group is promoted to obtain an α-sulfofatty acid alkyl ester.

Preferred examples of the conditions in each of the steps (a) to (d) are shown below. (A) Sulfonated gas introduction step In the present invention, a fatty acid alkyl ester represented by the following general formula (I) R ¹ CH ₂ COOR ² (I) is preferably used. Formula (I)
Wherein R ¹ represents an alkyl group having 6 to 24 carbon atoms, preferably 12 to 18 carbon atoms, and R ² represents 1 to 6 carbon atoms, preferably 1 to
3 represents an alkyl group. The iodine value of the fatty acid alkyl ester is 0.5 or less, preferably 0.1 or less. By using a compound having an iodine value of 0.5 or less, an effect is obtained that the α-sulfofatty acid alkyl ester is hardly colored.

Fatty acid alkyl esters 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 .; synthetic fatty acid alkyls derived from the oxo process of α-olefins. Ester and the like may be used, and there is no particular limitation. In particular,
Methyl, ethyl or propyl laurate; methyl, ethyl, or propyl myristate; methyl, ethyl, or propyl palmitate; methyl, ethyl, or propyl stearate; methyl, ethyl, or propyl hardened tallow fatty acid; 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, and the like. These may be used alone or in combination of two or more. Can be used.

Examples of the sulfonated gas include SO ₃ gas, fuming sulfuric acid and the like, and preferably, SO ₃ gas is used. Concentration 3 with dehumidified air or inert gas such as nitrogen
It is common to use SO ₃ gas diluted to ３０30% by volume. SO ₃ is one of the raw material fatty acid alkyl esters.
0 to 2.0 times mol, preferably 1.0 to 1.5 times mol,
More preferably, it is used in an amount of 1.05 to 1.3 times mol.
If it is less than 1.0 mole, the sulfonation reaction does not sufficiently proceed, and if it exceeds 2.0 moles, the sulfonation reaction becomes more intense, so that coloring due to local heat is likely to occur,
It is inconvenient.

The reaction system is not particularly limited, and a system such as a tank type reaction, a film reaction, a tube type gas-liquid multi-phase flow reaction and the like are applied. The sulfonation method is not particularly limited, and a thin film type sulfonation method, a batch type sulfonation method and the like are applied. When importance is placed on the color tone of the α-sulfo fatty acid alkyl ester, a batch-type sulfonation method is desirable, but when importance is attached to the cost at the production level, a thin-film sulfonation method is desirable. The reaction temperature is a temperature at which the fatty acid alkyl ester has fluidity. Generally, it is higher than the melting point of the fatty acid alkyl ester, preferably from the melting point to a temperature 70 ° C. higher than the melting point. The reaction time depends on the sulfonation method,
For example, it takes about 5 to 120 seconds for the thin film type sulfonation method and about 10 to 120 minutes for the batch type sulfonation method.

(B) Aging step The temperature of the aging step is suitably from 70 to 100 ° C. 70 ° C
If the temperature is lower than this, the reaction does not proceed quickly, and if the temperature is higher than 100 ° C., the color may be easily formed. Reaction time is 1 to 120
Minutes.

It is preferable that at least the aging step (b) is performed in the presence of a coloring inhibitor. As a coloring inhibitor,
Various types proposed by the present applicant can be used. For details of effective coloring inhibitors, refer to Japanese Patent Application No. 08-2.
No. 4433, Japanese Patent Application No. 08-336077, Japanese Patent Application No. 08
-340149, Japanese Patent Application No. 08-340148, Japanese Patent Application No. 08-340147, Japanese Patent Application No. 08-342244.
JP-A-09-216861, JP-A-09-2682
No. 16862, JP-A-09-216863, and the like. Among these, JP-A-09-21
It is preferable to use an inorganic sulfate having a monovalent metal ion and having an average particle size of 250 μm or less, which is disclosed in JP-A-68663. Inorganic sulfate has a high coloring suppression effect, is often inexpensive, and is a component that is added to detergents.
There is no need to remove from sulfo fatty acid alkyl ester salts (products).

The inorganic sulfate is not particularly limited as long as it is a powdery anhydrous salt having a monovalent metal ion, and examples thereof include sodium sulfate, potassium sulfate, and lithium sulfate. The inorganic sulfate having an average particle size of 250 μm or less, preferably 50 μm or less is used. During the reaction, the inorganic sulfate hardly dissolves in the reaction solution to the extent that its surface is slightly dissolved, and is dispersed in the reaction solution. Therefore, by using such an inorganic sulfate having a small particle size, the contact area is increased, the dispersibility is improved, and the effect can be further enhanced. The amount of the coloring inhibitor added is
The amount is 0.1 to 20% by weight, preferably 2 to 10% by weight, based on the fatty acid alkyl ester as the raw material. 0.1% by weight
If it is less than the above, the effect of addition cannot be obtained.

The inorganic sulfate (coloring inhibitor) may be present at least in (b) the aging step. Therefore, in order to simplify the operation, it is customary to add an inorganic sulfate to the fatty acid alkyl ester and to subject the mixture to the (a) sulfonating gas introduction step. An inorganic sulfate can be added between the step (b) and the aging step.

(C) Esterification Step The lower alcohol used in the esterification step preferably has 1 to 6 carbon atoms, which is the same as the carbon number of the alcohol residue of the fatty acid alkyl ester as the raw material, but is not particularly limited. . The lower alcohol is 0.5 to 5.0 moles, preferably 0.8 to 2.0 moles per mole of the bimolecular adduct in the reaction solution.
It is used in a molar amount of 0 times. The reaction temperature is 50 to 100 ° C, preferably 50 to 90 ° C, and the reaction time is 5 to 120 minutes.

(D) Neutralization Step In the present invention, except for the treatments (A) and (B) described later, for example, the neutralization apparatus shown in FIG. A pre-mixed slurry is prepared by mixing a crude α-sulfofatty acid alkyl ester, that is, a sulfonated product of a fatty acid alkyl ester, and an aqueous slurry of a neutralization reaction product, that is, an α-sulfofatty acid alkyl ester salt. Is added to obtain a neutralized reaction product. As a result of the study by the present inventors, it has been found that the above-mentioned corrosion of the apparatus occurs because the premixed slurry is an acidic slurry having a pH of 1 to 2. The present inventors have found that corrosion can be prevented by controlling at least the temperature at the time of adjusting the premixed slurry or selecting the material of the device that comes into contact with the premixed slurry, and completed the present invention. Was.

Hereinafter, description will be made using the apparatus shown in FIG. That is, since the sulfonated fatty acid alkyl ester obtained through the above steps (a) to (c) does not contain water, it has no corrosiveness. Therefore, corrosion does not occur in the α-sulfofatty acid alkyl ester supply line 1. But,
In the premixer 2, since the sulfonated product and the neutralization reaction product containing water are mixed, the premixed slurry becomes a highly corrosive acidic premixed slurry by the action of the water. For this reason, the premixer 2 in contact with the premixed slurry,
Corrosion easily occurs in the premixed slurry supply line 3, the pump, and the like. On the other hand, since the premixed slurry is neutralized in the neutralization mixer 4, the apparatus subsequent to the neutralization mixer 4 is hardly corroded.

Therefore, in the present invention, at least one of the following two processes is employed. (A) The temperature at the time of adjusting the premixed slurry in the premixer 2 is controlled to 60 ° C. or less. (B) In a device such as a pre-mixer 2, a pre-mixed slurry supply line 3, a pump, etc., which makes contact with the pre-mixed slurry, at least a contact surface with the pre-mixed slurry is
It is composed of ceramics and / or polytetrafluoroethylene (Teflon).

In the processing method (A), by controlling the temperature during the mixing operation in the premixer 2, the premixer 2, the premixed slurry supply line 3,
It is possible to keep the temperature of the premixed slurry in contact with a pump or the like at a low temperature and prevent such corrosion. If the temperature exceeds 60 ° C., corrosion tends to occur rapidly. In addition, the temperature at the time of preparing the premixed slurry can be controlled by, for example, adjusting the speed at which the α-sulfofatty acid alkyl ester and the neutralization reaction product are fed into the premixer 2, for example. Alternatively, a cooling device can be provided in the premixer 2 to control the temperature. Or
It can be controlled by adjusting the temperatures of the α-sulfofatty acid alkyl ester and the neutralization reaction product, respectively. According to this method, since the material of the device is not limited, the conventional device can be applied as it is.

In the treatment method (B), when the contact surface of the apparatus with the premixed slurry is made of ceramics, for example, a method of coating or lining this contact surface with alumina, silica, etc., a method of glass lining, Alternatively, there is a method in which a stirring blade or the like is made of ceramics. When the contact surface is made of polytetrafluoroethylene, for example, there is a method of coating this contact surface with Teflon or lining with Teflon. Whether to use ceramics or polytetrafluoroethylene is selected depending on the shape of an apparatus for performing the treatment. In this method, since the temperature at the time of adjusting the premixed slurry is not limited, the production efficiency can be improved. In addition, although the effects can be obtained by using the processing methods (A) and (B) alone, when these methods are combined,
Needless to say, the highest corrosion prevention effect can be obtained.

The premixed slurry has a weight of 5 to 25 times, preferably 10 to 20 times the total weight of the acid (α-sulfofatty acid alkyl ester) and the aqueous alkali solution added during neutralization.
Mix and adjust twice the weight of the neutralization reaction product. When the weight is less than 5 times, the effect of suppressing by-products is small, and when the weight exceeds 25 times, the production efficiency is reduced. The activator concentration (active ingredient concentration (AI concentration)) in the neutralization reaction product is 60 to 80.
% By weight, preferably 62 to 75% by weight. The activator concentration is the total concentration of the α-sulfofatty acid alkyl ester salt and the by-product α-sulfofatty acid dialkali salt. When the viscosity is out of this range, the viscosity of the slurry is significantly increased, or in the range where the viscosity of the slurry is low, the concentration of the activator is significantly lowered. When the viscosity of the slurry is high, handling becomes difficult. On the other hand, when the concentration of the activator is low, the production efficiency is disadvantageously reduced. In the device shown in FIG.
As the pre-mixer 2, a stack mixer, a pipeline mixer, a vortex pump, or the like is preferable because of its high mixing efficiency.

As the alkali used for neutralization, for example, aqueous solutions of alkali metals, alkaline earth metals, ammonia and ethanolamine are used. The concentration of the alkaline aqueous solution is 15
To about 50% by weight. If less than 15% by weight,
It may be difficult to adjust the concentration of the neutralization reaction product to the above range. If it exceeds 50% by weight, it may be difficult to adjust the concentration of the neutralization reaction product to the above-mentioned range, which makes handling difficult. Neutralization is performed when the pH of the neutralization reaction product of the α-sulfofatty acid alkyl ester and the alkali is in an acidic or weakly alkaline range (pH 4 to 4).
It is preferable to carry out in step 9). In the case of strong alkali, the ester bond may be easily broken. The neutralization temperature is 30 to 140 ° C., and the neutralization time is 10 to 60 minutes. In this example, since the manufacturing efficiency is good,
A loop system in which the neutralization reaction product is recycled and neutralized continuously by using a device in which a neutralization loop system is formed has been adopted. However, the present invention is not limited to this, and the neutralization reaction product is not recycled. A batch method or the like can be adopted.

If necessary, before or after the (d) neutralization step, a treatment for improving the color tone of the α-sulfofatty acid alkyl ester salt to a color close to white can be performed. The treatment for improving color tone includes, for example, a bleaching treatment using a bleaching agent such as hydrogen peroxide, and is preferably performed after the (d) neutralization step. Then, (d) the neutralization reaction product after the neutralization step is formed into a predetermined shape such as particles by a conventional method to obtain a product.

The embodiments of the present invention are summarized as follows. (1) In the treatment method (A), the temperature at the time of preparing the premixed slurry is, for example, a rate at which the α-sulfofatty acid alkyl ester and the neutralization reaction product are fed into the premixer.
It can be controlled by adjusting each. Alternatively, a cooling device can be provided in the premixer to control the temperature. Alternatively, it can be controlled by adjusting the temperature of the α-sulfofatty acid alkyl ester and the neutralization reaction product, respectively. (2) In the treatment method (B), when the contact surface of the apparatus with the premixed slurry is made of polytetrafluoroethylene, there is a method of coating the contact surface with Teflon or lining with Teflon. (3) The premixed slurry is a neutralization reaction product having a weight of 5 to 25 times, preferably 10 to 20 times the weight of the total of the acid (α-sulfofatty acid alkyl ester) and the aqueous alkali solution added during the neutralization. Adjust by mixing. (4) Activator concentration in the neutralization reaction product (active ingredient concentration (A
I concentration)) is from 60 to 80% by weight, preferably from 62 to 75% by weight.
% By weight. (5) The concentration of the aqueous alkali solution used for neutralization is 15 to 50.
% By weight.

[0035]

EXAMPLES (Examples 1-8, Comparative Examples 1-8: preliminary temperature control effect of the mixed _{slurry) C 14: C 16 = 2} : 8 saturated fatty acid methyl ester (average molecular weight = 264, iodine value =
0.05), 5% by weight of fine powdered sodium sulfate (coloring inhibitor) was added to the fatty acid methyl ester, and 8% by volume of N ₂ gas was added while maintaining the reaction temperature at 80 ° C. using a tank reactor.
1.2 mol of SO ₃ gas (relative to fatty acid methyl ester) was introduced at a constant speed for 60 minutes. After the introduction, an aging reaction was performed for 30 minutes while maintaining the temperature at 80 ° C.
4 parts by weight of methanol was added to 00 parts by weight, and an esterification reaction was carried out for 20 minutes while stirring at a temperature of 80 ° C.

The sulfonated product (α-sulfofatty acid alkyl ester) after esterification was converted to 34% by weight using a glass-lined neutralizing device similar to that shown in FIG.
Neutralized with aqueous sodium hydroxide. That is, at the start of neutralization, a neutralization reaction product having an activator concentration of about 70% by weight is introduced into the neutralization loop system shown in FIG. 1 and recycled by the recycle pump 7 at a flow rate of 150 kg / hr. went. Then, the sulfonated product was added thereto at 7.5.
kg / hr, premixer 2 (vortex pump)
To prepare a premixed slurry.
Further, the premixed slurry (acidic slurry) is sent to a neutralization mixer 4 (vortex pump), and a 34% by weight aqueous sodium hydroxide solution is introduced into the neutralization mixer 4 at a rate of 2.5 kg / hr to neutralize the slurry. The reaction was performed.

Then, a test piece of 20 mm × 60 mm × 2 mm was set at two places of the premixer A (premixer 2) and the piping section B (premixed slurry supply line 3) shown in FIG. The state of corrosion after two weeks, one month, and two months of operation was examined. Tables 1 and 2 show the results of the corrosion experiments. In Tables 1 and 2, the study points are
The position of the test piece is indicated, and the handling substance is a premixed slurry that is a cause of corrosion. The used material indicates the material of the test piece, and the mixing temperature indicates the mixing temperature in the premixer 2. That is, the temperatures of the premixer A and the pipe portion B are lower than the mixing temperature. The results of the corrosion test show the results after two weeks of operation for those with severe corrosion, and the results after two months of operation for those that did not corrode. For the corroded one, the weight of the test piece was measured, and this was converted into the corrosion rate per year and shown. Also, observe the state of corrosion from the appearance,
As a comprehensive evaluation, x was marked when corrosion was observed, and o was marked when corrosion was not observed.

[0038]

[Table 1]

[0039]

[Table 2]

(Examples 9 to 12, Comparative Examples 9 to 16: Effect of Material of Apparatus) Corrosion experiments were performed in the same manner as in Examples 1 to 8 except that the mixing temperature in the premixer 2 was kept constant at 80 ° C. Was. However, the test piece of the example is a stainless steel SUS304 having a surface coated with Teflon or a ceramic (high-purity ceramic: 6).
0% alumina) was used. Tables 3 and 4 show the results of the corrosion experiments.

[0041]

[Table 3]

[0042]

[Table 4]

From the results shown in Tables 1 and 2, it was clarified that corrosion can be prevented by controlling the temperature of the premixed slurry to 60 ° C. or less. It should be noted in these results that no corrosion occurred at 60 ° C., but significant corrosion occurred at 70 ° C. That is, 60
This shows that a sharp change occurs at the value of ° C., and the critical significance of numerical limitation in the present invention is clear. Also, from the results in Tables 3 and 4, even if the temperature of the premixed slurry (acid slurry) exceeds 60 ° C., the contact surface of the device with the premixed slurry is formed from ceramics or polytetrafluoroethylene. By doing so, it became clear that corrosion could be prevented.

[0044]

As described above, the method for producing an alkyl ester of α-sulfofatty acid of the present invention provides
Neutralization reaction product of sulfo fatty acid alkyl ester and α-
In preparing a pre-mixed slurry by mixing a sulfo fatty acid alkyl ester and neutralizing this pre-mixed slurry, the following (A) and (B): (A) controlling the temperature at the time of preparing the pre-mixed slurry to 60 ° C. or less. I do. (B) In the manufacturing apparatus, at least the contact surface with the premixed slurry is formed from ceramics and / or polytetrafluoroethylene. By performing one or both of the above processes, corrosion of the device can be prevented. As a result, by-products of the α-sulfofatty acid dialkaline salt are reduced, and a highly concentrated slurry of the α-sulfofatty acid alkyl ester salt of high purity can be obtained. No need to add and recover a third component such as a solvent or a viscosity reducing agent or a concentration step by using a low-concentration aqueous alkali solution. A method for producing an α-sulfofatty acid alkyl ester salt capable of continuous operation can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a neutralization device used in the present invention.

[Explanation of symbols]

1. .alpha.-sulfo fatty acid alkyl ester supply line, 2.
... Premixer, 3 ... Premixed slurry supply line, 4
... neutralization mixer, 5 ... alkaline aqueous solution supply line, 6 ...
Neutralization reaction product withdrawal line, 7: recycle pump, 8: withdrawal pump, 9: discharge line, 10: recycle line, 11: heat exchanger.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahisa Yoshiya 1-3-7 Honjo, Sumida-ku, Tokyo Inside Lion Corporation (72) Inventor Seiji Matoba 1-3-7, Honjo, Sumida-ku, Tokyo No. Within Lion Corporation (72) Inventor Yozo Miyawaki 1-3-7 Honjo, Sumida-ku, Tokyo F-Term within Lion Corporation (reference) 4H003 AB21 FA03 FA08 4H006 AA02 AC61 BB61 BC31 BC51 BD82 BD83 BE43

Claims (1)

[Claims] 1. A premix slurry is prepared by mixing a neutralization reaction product of an α-sulfofatty acid alkyl ester with an α-sulfofatty acid alkyl ester, and the premixed slurry is neutralized by the following (A) (B) (A) The temperature at the time of adjusting the premixed slurry is controlled to 60 ° C. or less. (B) In the manufacturing apparatus, at least the contact surface with the premixed slurry is formed from ceramics and / or polytetrafluoroethylene. A process for producing an α-sulfofatty acid alkyl ester salt, wherein one or both of the above treatments are performed.