JP3425247B2 - Concentration method of surfactant solution - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for concentrating a surfactant solution such as an .alpha.-sulfofatty acid alkyl ester salt.

[0002]

2. Description of the Related Art Anionic surfactants are industrially provided as an aqueous solution obtained by neutralization. Generally, it is desirable that the AI concentration (concentration of active ingredient) of the surfactant solution is as high as possible from the economical point of view of manufacturing equipment, transportation and packaging materials, and from the viewpoint of handling property, a lower viscosity is preferable. Is required. For this reason, it is advantageous to use a surfactant such as alkylbenzene sulfonate as a high-concentration slurry.

However, in general, when a high-concentration slurry containing a surfactant in an amount of 50% by weight or more is used, the viscosity increases, which causes troubles in handling. Therefore, alkylbenzene sulfonates, α-olefin sulfonates, polyoxyethylenes have hitherto been used. Various techniques for reducing the viscosity of highly concentrated slurries such as alkyl ether sulfate have been proposed. For example, a method of adding an inorganic salt of halogen such as sodium chloride (US
P3954679), a method of adding polyethylene glycol (JP-A-50-116383),
A method of adding excess alkali and alkylene oxide (Japanese Patent Publication No. 55-16504).

However, since the α-sulfofatty acid alkyl ester salt has a behavior greatly different from that of the alkylbenzene sulfonate, the viscosity of the high-concentration slurry cannot be effectively reduced even by using these conventional techniques. It had been.

That is, the viscosity of the aqueous solution of α-sulfofatty acid alkyl ester salt rapidly increases from a concentration of about 20 to 30% by weight or more, and when the concentration further increases, a gel is formed and the fluidity is completely lost. Even there. When this solution is further concentrated, the viscosity starts to decrease from a concentration of about 50% by weight, and becomes a state of fluidity of 300 to 400 poise at about 60% by weight, but thereafter the viscosity increases again. Initially, it gradually changes to a solid α-sulfofatty acid alkyl ester salt.

However, the α-sulfofatty acid alkyl ester salt obtained by neutralizing the α-sulfofatty acid alkyl ester has good hard water resistance, very good detergency, and mild to the skin. Since it is useful as a cleaning surfactant, it has been desired to have a technique for lowering the viscosity of a high-concentration slurry like other anionic surfactants.

Regarding this problem, Japanese Patent Publication No. 4-232
It has been found from the publication No. 0 that a slurry having a low viscosity and easy to handle can be obtained by controlling the amounts of the α-sulfofatty acid alkyl ester salt and the lower alcohol sulfate within a certain range, which has been solved. Further, the α-sulfofatty acid alkyl ester salt has another technical problem to be solved.

Unlike higher alcohols and α-olefins, the α-sulfofatty acid alkyl ester has a slow sulfonation reaction rate, and therefore is sulfonated under severe reaction conditions in order to obtain a predetermined sulfonation reaction rate. Will be required. The sulfonated product thus obtained, namely α-
Sulfo fatty acid alkyl ester salt is markedly colored and a light colored product cannot be obtained. Therefore, various bleaching methods have been proposed. According to the method of bleaching in the presence of a lower alcohol as proposed in JP-B-1-41138, the color tone of α-sulfofatty acid alkyl ester salt is significantly improved. It became possible to do.

However, since the product obtained by the above method contains a lower alcohol and further has an offensive odor, in order to use it as an activator, the α-sulfofatty acid alkyl ester salt after bleaching is converted into a lower alcohol. It was necessary to remove less than the desired amount and deodorize.

As described above, the aqueous solution of α-sulfo fatty acid alkyl ester salt obtained through the sulfonation / bleaching / neutralization process is required to have a high concentration and to remove alcohol and deodorize. Since a technology for lowering the viscosity of fatty acid alkyl ester salt high-concentration slurry was developed, in principle, it is possible to perform concentration treatment and dealcoholization treatment like other anionic surfactants such as linear alkylbenzene sulfonate. It has become possible.

However, if an anionic surfactant solution such as an aqueous solution of α-sulfofatty acid alkyl ester salt is attempted to be concentrated or alcohol is removed by using a forced agitation thin film evaporator, there is a problem that equipment cost increases. there were.

On the other hand, as an inexpensive concentration method, an evaporation method and a flash evaporation method are known, but they are not always efficient, and particularly when the aqueous solution of α-sulfofatty acid alkyl ester salt is concentrated and alcohol is removed. Did not get satisfactory results.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to efficiently concentrate a surfactant solution by a flash evaporation method which is inexpensive in equipment.

[0014]

The method for concentrating a surfactant solution according to the present invention is such that, when the surfactant solution is concentrated, the raw material surfactant solution is flash-evaporated and separated into an evaporate and a concentrate. , Recycle flash method in which a part of the recovered concentrate is circulated, mixed with the raw material surfactant solution and again subjected to flash evaporation, and the mixture of the raw material surfactant solution and the circulating substance is maintained at a temperature above the boiling point. However, it is characterized in that the concentration treatment is performed by setting the recycling ratio, which is expressed as the ratio (circulation amount / supply amount) of the supply amount of the raw material surfactant solution and the circulation amount of the concentrate, to 8 or more.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to an example of an aqueous solution of an α-sulfofatty acid alkyl ester salt.
As the fatty acid alkyl ester used as the starting material for the sulfonation, those represented by the following general formula (I) are preferable, and saturated fatty acid alkyl esters are preferable.

[0016]

Embedded image RCH ₂ COOR ′ (I) (R: C 6-20, preferably 10-16, straight-chain or branched alkyl or alkenyl group R ′: C 1-6, preferably 1- 3 straight-chain or branched alkyl group)

This fatty acid alkyl ester is a fatty acid derived from animal fats and oils derived from beef tallow, fish oil, lanolin, etc., a fatty acid derived from vegetable fats and oils derived from coconut oil, palm oil, soybean oil, etc., and α-olefins. Any of synthetic fatty acid esters derived from the oxo method may be used,
There is no particular limitation. Further, specific examples thereof include methyl laurate, ethyl or propyl, methyl palmitate or ethyl, methyl stearate or ethyl, hardened tallow fatty acid methyl or ethyl, coconut oil fatty acid methyl or ethyl, palm oil fatty acid methyl or ethyl, hardened. Examples include fish oil fatty acid methyl or ethyl, lanolinate methyl or ethyl, and the like. These may be used alone or as a mixture, and in order to improve the color tone of the sulfonated product, the iodine value is preferably as low as possible, preferably a fatty acid alkyl ester having an iodine value of 1 or less is used. .

The sulfonation of fatty acid alkyl ester is
A sulfonating agent, for example, anhydrous sulfuric acid diluted with an inert gas, is used at a molar ratio of 1.0 to 2.0, usually 50 to 100.
It is carried out at a temperature of ° C. As the sulfonation method, any of a thin film type sulfonation method, a tank type sulfonation method and the like can be adopted, but it is preferable to carry out the sulfonation reaction using a falling film reactor or a multistage sulfonation cascade.

Next, the sulfonated product is aged to complete the sulfonation. This aging is 10-80 at 60-100 ° C.
It is preferable to carry out by stirring for a minute. The aging is preferably carried out by keeping the sulfonated crude product in the loop reactor, a cascade of stirring tanks or a vertical aging pipe with a stirrer for the above period of time.

The bleaching treatment is carried out by directly treating the α-sulfofatty acid ester obtained by the sulfonation treatment (including the aging step) or by neutralizing the α-sulfofatty acid ester salt and then treating it with a bleaching agent. be able to.

Bleaching is carried out by adding hydrogen peroxide in the presence of alcohol, and the amount of lower alcohol sulfate by-produced is controlled so as to be 5 to 15% by weight with respect to the α-sulfofatty acid alkyl ester salt. To do.

The hydrogen peroxide used in the present invention includes
It is possible to use industrially supplied 35%, 50%, 60%, etc. hydrogen peroxide water, and normally 35% hydrogen peroxide water is suitable in terms of handleability and storage.

The amount of hydrogen peroxide (H ₂ O ₂ ) added during the bleaching treatment is preferably 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, relative to 100 parts by weight of the sulfonated fatty acid alkyl ester. Parts by weight. If this amount is less than 0.5 part by weight, the bleaching effect is not sufficient. On the other hand, even if the amount exceeds 10 parts by weight, the bleaching effect does not change, but rather the volume of the bleaching mixture increases due to decomposition of hydrogen peroxide.

As the alcohol coexisting during the bleaching treatment of the present invention, those having 1 to 12 carbon atoms are used, and specifically, methyl alcohol, ethyl alcohol, n- or iso-propyl alcohol, n-, iso-. Or t
ert-butyl alcohol, 1,2,3-pentanol, hexanol, glycerin, ethylene glycol,
Linear or branched monohydric or polyhydric alcohols such as octyl alcohol and lauryl alcohol can be used.

The amount of these alcohols used is 0.5 with respect to 100 parts by weight of α-sulfofatty acid alkyl ester.
-30 parts by weight is suitable, and preferably 1-20 parts by weight. If the amount used is less than 0.5 parts by weight, the bleaching effect due to the addition is not sufficient, while if the amount used is large, it causes a decrease in the purity of the sulfonic acid, so 20 parts by weight or less is suitable. By adding alcohol, the viscosity of the bleaching mixture is lowered, and the freezing point is also lowered.
Easy to handle.

The bleached product is neutralized with, for example, a 5 to 50 wt% aqueous solution of sodium hydroxide or potassium hydroxide to obtain an α-sulfofatty acid alkyl ester salt aqueous solution. The obtained α-sulfofatty acid alkyl ester salt aqueous solution has a low AI concentration, contains a large amount of lower alcohol, and has an odor.

Therefore, in the present invention, the recycle flash method is used for concentration and removal of lower alcohol (typically up to 1% by weight) while improving odor.

The raw material aqueous surfactant solution to be concentrated is 30 to 5 parts by weight of α-sulfofatty acid alkyl ester salt.
5% by weight, preferably 5 to 15% by weight of a lower alcohol sulfate and 8 to 40% by weight of an alcohol having 1 to 12 carbon atoms based on the α-sulfofatty acid alkyl ester salt. This component adjustment can be performed by adjusting the amount of alcohol added during bleaching, or may be performed by adding each component prior to concentration.

By adjusting the composition of the raw material surfactant aqueous solution as described above, the lower alcohol can be efficiently removed and deodorized without passing through the high viscosity region at the time of removing the lower alcohol, and the AI concentration can be increased to be concentrated. can do.

FIG. 1 is an explanatory view showing a recycle flash evaporation method adopted in the present invention. The raw material surfactant aqueous solution is heated to a boiling point or higher by the heater 11, and is flushed into the flash can 15 through the pressure control valve 13. The pressure at the flush outlet may be normal pressure, but is preferably pressurized. By applying pressure, evaporation inside the heater 11 is suppressed, and flash evaporation becomes efficient. A nozzle or the like may be attached to the flash outlet to atomize the lower alcohol to more efficiently evaporate the lower alcohol.

When flushed in the flash can 15, water and lower alcohol are evaporated, condensed in the condenser 19 and collected as condensed water. On the other hand, the concentrate is collected from the bottom of the flash can 15. In the present invention, a part of the concentrate is circulated in the circulation loop by the circulation pump 17 and mixed with the supplied raw material surfactant aqueous solution, and the mixture is heated to the boiling point or higher by the heater 11.
Flash can 1 again via pressure control valve 13
Flush within 5. The boiling point of the mixture varies depending on the pressure to be heated, but the heater 11
Then, it is important to heat so that the temperature of the mixture becomes higher than the boiling point. If this temperature does not reach the boiling point, a large amount of lower alcohol remains and odor remains, and the viscosity of the obtained concentrate is high, and sufficient concentration cannot be achieved.

When the amount of the raw material surfactant aqueous solution supplied for flash evaporation is the supply amount and the amount of the circulating concentrate is the circulation amount, the recycling ratio is defined by the following mathematical expression 1. It

[0033]

[Equation 1]

That is, the recycling ratio is the mixing ratio of the raw material surfactant aqueous solution and the circulating concentrate in the mixture subjected to flash evaporation.

In the present invention, it is important that this recycling ratio is 8 or more. By setting the recycling ratio to 8 or more, stable operation can be performed in a low viscosity range without passing through a high viscosity range, a lower alcohol content is small, an odor is improved, and a sufficiently concentrated α is obtained. An aqueous sulfofatty acid alkyl ester salt solution is obtained.

In the above description, the concentration of the α-sulfofatty acid alkyl ester salt aqueous solution has been described, but the concentration method of the present invention is not limited to this and can be used for concentration of other surfactant solutions. .

[0037]

According to the present invention, the surfactant solution can be efficiently concentrated by carrying out the recycle flash evaporation at a recycle ratio of 8 or more and at a temperature of the boiling point or higher.
The recycle flash evaporator has low equipment cost and running cost, and this method is an industrially excellent concentration method.

The method of the present invention is preferably used for the concentration of an aqueous solution of an α-sulfofatty acid alkyl ester salt containing a lower alcohol having 1 to 12 carbon atoms and a lower alcohol sulfate, which is inevitably mixed in the bleaching step. As a result, a highly concentrated aqueous solution of α-sulfofatty acid alkyl ester salt having no alcohol, odor, low viscosity and easy handling can be obtained.

[0039]

【Example】

Examples 1 to 5 Palm oil fatty acid methyl ester obtained by transesterifying palm oil with methyl alcohol was subjected to fractional distillation to obtain C ₁₂ , C ₁₄ and C.
_16, to obtain a saturated fatty acid methyl esters of C _18. C ₁₈ was hydrogenated by a conventional method to give an iodine value of 0.2. These are C _12:10 , C ₁₄ : 25, C ₁₆ : 55,
C ₁₈ : Saturated fatty acid methyl ester (iodine value = 0.4) mixed at a ratio of 10% by weight was used in a flow-through type thin film reactor to react with SO ₃ gas diluted with dehumidified air to a reaction molar ratio of 7%. Sulfonation was performed under the conditions of (SO ₃ / saturated fatty acid ester) = 1.2 and reaction temperature of 80 ° C. to obtain a sulfonated crude product. The obtained sulfonated crude product was introduced into a loop type aging tube with a double tube type jacket having an average residence time of 20 minutes. Three loop-type aging pipes were continuously connected, the average residence time was 60 minutes, and in order to maintain sufficient stirring and constant temperature, the loop-type aging pipe was flowed at a linear velocity of 0.16 m / sec. The actual temperature was 78 to 82 ° C. with respect to the set temperature of 80 ° C. to carry out a controlled aging reaction to complete the sulfonation to obtain α-sulfofatty acid methyl ester.

After introducing 30 parts by weight of methanol with respect to 100 parts by weight of the obtained α-sulfofatty acid methyl ester, 8.6 parts by weight of this mixture and 35% hydrogen peroxide solution were added.
The mixture was introduced into a continuous loop reactor equipped with a mixing mixer and a heat exchanger, and bleaching was performed at 80 ° C. for an average residence time of 20 minutes,
Further, under the same conditions, the bleaching was carried out by continuously introducing them into the loop reactors of the second and third stages.

Next, 13.6% NaOH aqueous solution and the above bleaching product were introduced into a loop-type continuous neutralization apparatus equipped with a mixing mixer and a heat exchanger to adjust the pH to 7, and α was used as a neutralization product. An aqueous sulfo fatty acid alkyl ester salt solution was obtained.

Using this α-sulfofatty acid alkyl ester salt aqueous solution as a raw material surfactant aqueous solution, recycle flash evaporation was carried out in the apparatus shown in FIG. 1 to remove and concentrate lower alcohols.

The composition of the raw material surfactant aqueous solution was adjusted and concentrated under various flash conditions. The results are shown in Table 1.
It was shown to. The color tone was measured by preparing a 5% aqueous solution as an α-sulfofatty acid alkyl ester salt, and using Klett Su.
It was measured with a photometer manufactured by Mmmerson and shown as a measured value.

[0044]

[Table 1]Table 1: Concentration conditions and evaluation results                                    Example Comparative example  Example   1 1 2 2 3 4 5 Raw surfactant aqueous solution   α-SF (wt%) *¹40 40 40 45 50 55 45   Lower alcohol sulfate (wt%) 3 3 3 4 4 4 4   Lower alcohol (wt%) 12 12 12 10 10 12 14 Color tone 70 70 70 75 80 80 72 Flash condition   Heater temperature (℃) 120 90 120 120 120 120 140   Liquid temperature before flash (℃) 105 85 105 120 120 120 140   Recycle ratio 10 10 6 10 12 15 10   Heater internal pressure Normal pressure Normal pressure Normal pressure Pressurization Pressurization Pressurization Boiling point (℃) 105 105 105 120 120 120 140 Concentrate   α-SF *¹(wt%) 60 55 57 68 72 75 70   Lower alcohol (wt%) 0.9 3.5 2.7 0.7 0.6 0.5 0.6   Color tone 45 60 53 45 47 43 45   Odor ○ × × ○ ○ ○ ○ Viscosity (poise at 90 ℃) 70 200 250 40 20 65 35 Overall evaluation ○ × × ○ ○ ○ ○   * 1) α-SF: α-sulfofatty acid methyl ester sodium

[Brief description of drawings]

FIG. 1 is an explanatory view showing a recycle flash evaporation method of the present invention.

[Explanation of symbols]

11 heater 13 Pressure control valve 15 flash cans 17 Circulation pump 19 condenser

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Nagai 1-3-7 Honjo, Sumida-ku, Tokyo Inside Lion Co., Ltd. (56) Reference JP-A-5-49801 (JP, A) JP-A 54-29877 (JP, A) JP-A-6-184600 (JP, A) Actual development 1-122803 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01D 1/00 B01D 3/06 C11D 1/28

Claims (2)

(57) [Claims] 1. When the surfactant solution is concentrated, the raw material surfactant solution is flash-evaporated to separate it into an evaporate and a concentrate, and a part of the recovered concentrate is circulated to make the raw material surface active agent. Using the recycle flash method of mixing with the agent solution and subjecting it to flash evaporation again, while maintaining the temperature of the mixture of the source surfactant solution and the circulating material at a temperature above the boiling point, circulating the supply amount of the source surfactant solution and the concentrate. A method for concentrating a surfactant solution, which comprises performing a concentration treatment by setting a recycling ratio expressed as a ratio (circulation amount / supply amount) to 8 or more. 2. A raw material surfactant solution comprises an α-sulfofatty acid alkyl ester salt as a surfactant and a carbon number of 1 to 1.
The method for concentrating a surfactant solution according to claim 1, which comprises 12 alcohols and water.