JPH10249176A - Method for diluting surfactant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to efficiently dilute a surfactant compsn. having a high viscosity or the surfactant compsn. of the viscosity increasing at the time the compsn. is diluted with an aq. solvent without using intricate devices and a metering pump having good accuracy and without the occurrence of gelatinization and blob-like lumpy materials. SOLUTION: After the aq. solvent is charged into a stirring tank 1 having a stirrer 9, a content liquid 4 consisting of the aq. solvent is circulated by a circulating pipe 2 while the liquid is kept stirred. The surfactant comps. of the high viscosity and/or the viscosity increased in a dilution process is so supplied to a circulating device 3 that the ratio of the supply flow rate thereof and the delivery flow rate of the content liquid from the one end 2a of the pipe attains >=1:2. In addition, the content liquid 4 and the surfactant compsn. are mixed by adding shearing force of >=10m/s at the speed at the front end of the stirring vanes disposed at the circulating device 3 thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surfactant composition having a high viscosity and a method of diluting a surfactant composition which becomes highly viscous when diluted with an aqueous solvent. Despite the use of simple equipment, the composition can be efficiently diluted without generating lumps or gelling, and can be manufactured by diluting the surfactant composition or compounding the product. The present invention relates to a method for diluting a surfactant composition suitable for producing fiber detergents such as dishwashing detergent, vegetable detergent, shampoo, rinse, clothing detergent, softener and the like.

[0002]

2. Description of the Related Art Conventionally, a high-viscosity fluid, a fluid that is thickened and gelled by contact with an aqueous solvent, and a low-viscosity fluid are supplied from separate pipes to supply both. Numerous methods for continuously mixing and diluting with a concentrated shearing device such as a homomixer after the confluence have been studied. For example, Japanese Patent Application Laid-Open No. 7-34089 discloses a method in which a high-concentration surfactant and an aqueous diluent are used. A method of diluting a high-concentration surfactant by making the same into a thin film and continuously feeding them into a mixer having high rotation and strong shearing force has been proposed. However, the mixer used here has a problem that not only the apparatus for forming the thin film becomes complicated, but also the processing capacity is limited due to the narrow interval between the processing liquids.

Japanese Patent Application Laid-Open No. Hei 8-196883 discloses that a high-viscosity fluid and a low-viscosity fluid are supplied from separate pipes so that they are combined, and then the average residence time is determined by a mixer provided downstream thereof. A method of continuously diluting by stirring for 4 seconds or more has been proposed. However, in the case of this proposal, it is not necessary to use a complicated device as in the above proposal, but the residence time in the mixer is long, so that the capacity of the mixer to be used must be increased, which is accompanied by As a result, it is necessary to increase the power of the driving unit, and there is a problem that the processing capacity is naturally limited.

Further, in the case of the above proposals, a continuous dilution in which a high-concentration surfactant or a high-viscosity fluid and an aqueous diluent or a low-viscosity fluid are simultaneously supplied at a ratio of a target dilution concentration and mixed. Since the method is adopted, an accurate metering pump is required in order to obtain a diluent having a predetermined concentration with high accuracy.

The present invention has been made in view of the above circumstances, and is intended to provide a high-viscosity surfactant composition or a surfactant composition which becomes highly viscous when diluted with an aqueous solvent, using a complicated apparatus and an accurate It is an object of the present invention to provide a method for diluting a surfactant composition that can be efficiently diluted without using a good metering pump and without causing gelation or lumpy lump.

[0006]

Means for Solving the Problems and Embodiments of the Invention The present inventor has conducted intensive studies in order to solve the above problems, and as a result,
A stirring tank equipped with a stirrer, and a circulation pipe having both ends communicating with the stirring tank and a mixing circulating device having stirring blades interposed therebetween, and the content liquid in the stirring tank is introduced into the circulation device. Using a mixing device that sends out and mixes and then returns to the stirring tank, the content liquid in the stirring tank made of an aqueous solvent is circulated at a predetermined delivery flow rate through the pipe while stirring in the stirring tank. A surfactant composition having a high viscosity when diluted with a high-viscosity surfactant composition or an aqueous solvent is supplied to the circulation device at a supply flow rate which is a predetermined ratio with respect to the above-mentioned delivery flow rate. By mixing the composition and the content liquid under a predetermined shearing force and then returning the mixed solution to the stirring tank, the surfactant composition can be efficiently and easily diluted or a product can be compounded. This led to the present invention.

That is, according to the above method, the above-mentioned surfactant composition is gradually supplied into the circulation device at a predetermined speed, and firstly, under a shearing force capable of sufficiently stirring the high-viscosity material in the circulation device. Since it is mixed with the content liquid that is an aqueous solvent and is dispersed in the content liquid, the interface area is increased when returned to the stirring tank, and such a surfactant composition dispersion liquid is used. By stirring in a stirring tank that allows a sufficient residence time, the surfactant composition can be uniformly dissolved and uniformly dispersed in the content liquid in the stirring tank. Then, by further circulating the content liquid in the stirred tank uniformly dissolved or uniformly dispersed, and by using the surfactant composition as a diluent for diluting the surfactant composition, the surfactant composition is gradually diluted. As the dilution progresses, the surfactant composition becomes more compatible with the diluent and becomes more dilutable.

Accordingly, the present invention provides a method for diluting a surfactant composition having a high viscosity and / or a surfactant composition which becomes highly viscous when diluted with an aqueous solvent, with an aqueous solvent.
A stirrer provided with a stirrer, a circulation pipe having both ends communicating with the stirrer, and a mixing circulator having a stirring blade interposed therebetween. The content liquid in the stirring tank is sent out, the content liquid is mixed by the stirring blades of the circulation device, and the content liquid is passed through the inside of the pipe from the discharge port of the circulation device and the other end of the pipe. Using a mixing device to be returned into the stirring tank, after charging the aqueous solvent in the stirring tank, and circulating the content liquid composed of the aqueous solvent through the pipe while stirring in the stirring tank, The surfactant composition is supplied to a circulation device so that the ratio of the supply flow rate to the content liquid delivery flow rate from one end of the pipe is 1: 2 or more, and the content liquid and the surfactant composition are supplied. And the above stirring blades It provides a dilution method detergent composition characterized by mixing by adding 10 m / s or more shear as an end speed.

Now, the present invention will be described in further detail. The method for diluting a surfactant composition of the present invention is a method for diluting a surfactant composition having a high viscosity or a surfactant composition which becomes highly viscous in a dilution process with an aqueous system. Upon dilution with the solvent, while stirring the content liquid in the stirring tank composed of the aqueous solvent in the stirring tank, by a mixing device including a stirring tank equipped with a stirrer and a circulation pipe provided with a circulation device for mixing. Circulating from the stirring tank to the circulating device, circulating from the circulating device to the stirring tank, and supplying the surfactant composition into the circulating device at a supply flow rate that is a predetermined ratio with respect to the content liquid sending flow rate, After mixing the content liquid and the surfactant composition by applying a predetermined shearing force, the mixed liquid is returned from the circulation device to the stirring tank, and further circulated in the circulation pipe system as the content liquid. The above surfactant composition By using as a diluent, is to gradually diluted with batchwise said surfactant composition.

Here, the above-mentioned surfactant composition is a high-viscosity surfactant composition or a surfactant composition which increases in viscosity during a dilution process. "Material" means a B-type rotational viscometer at 30 rpm
When the viscosity at the 10th rotation is measured by rotating at
It means a surfactant composition having a temperature of at least 00 cP (dilution temperature). In the following, “viscosity” means the viscosity according to the above measurement method. In addition, the term “surfactant composition that increases the viscosity in the dilution process” refers to the peak viscosity (maximum value) in the dilution process of sequentially diluting the surfactant composition with an aqueous solvent before dilution, according to a conventional method. It means a surfactant composition having a viscosity of 10 times or more.

The type of the surfactant composition to be diluted by the dilution method of the present invention is not particularly limited as long as the surfactant composition has a high viscosity or becomes highly viscous when diluted with an aqueous solvent. Rather, the high-viscosity surfactant compositions include, for example, those composed of only a surfactant, a high-concentration aqueous solution of a surfactant having a surfactant concentration of 30% (% by weight, hereinafter the same) or more. Surfactants, surfactant compositions in which a thickener such as ethanol is blended with a high-concentration surfactant aqueous solution, or mixed with a higher alcohol or a water-soluble solvent. As a surfactant composition that can be made high in viscosity, for example, a surfactant that thickens and gels in the process of successively adding an aqueous solvent, a surfactant aqueous solution of high concentration, or a thickener such as ethanol Surface activity containing A composition can include those comprising a high viscosity at the process. Specific examples of such surfactants include anionic surfactants such as polyoxyethylene lauryl ether sulfate and lauryl sulfate, cationic surfactants such as dialkylammonium salt and monoalkylammonium salt, and polyoxyethylene. Examples include nonionic surfactants such as lauryl ether and fatty acid diethanolamide.
These can be used alone or in combination of two or more. In the case of the dilution method of the present invention, it is particularly effective to use polyoxyethylene lauryl ether sulfate, dialkylammonium salt, and polyoxyethylene lauryl ether.

As the aqueous solvent used as a diluent for the above-mentioned surfactant composition, a normal dilute solution can be used. As such an aqueous solvent, not only water but also, for example, a surfactant, ethanol And propylene glycol and the like containing a relatively low concentration.
In the case of the present invention, the above-mentioned aqueous solvent may be appropriately blended with various additives usually blended in the final product within a range that does not impair the effects of the present invention.

Next, an apparatus used in the dilution method of the present invention will be described with reference to the drawings. In the figure, reference numeral 1 denotes a stirring tank, and 2 denotes a circulation pipe provided with a mixing circulating device 3 provided with stirring blades (not shown). And the other end 2b
Is immersed in the content liquid 4 accommodated in the stirring tank 1, and by the operation of the circulation device 3, the content liquid 4 in the stirring tank 1 flows from one end 2 a of the circulation pipe 2 into the circulation device 3. And is subjected to a mixing action by a stirring blade (not shown) in the circulating device 3, and then passes through the circulating pipe 2 from the discharge port of the circulating device 3 and from the other end 2b to the stirring tank 1
Circulate back in. Here, the circulation pipe 2
It is sufficient if piping is provided so that the content liquid 4 in the stirring tank 1 can be circulated between the stirring tank 1 and the circulation device 3. In consideration of suppressing the bubbling of 4, it is desirable to immerse the other end 2 b of the circulation pipe 2 in the content liquid 4 as described above. Further, as will be described later, the circulation device 3 circulates the content liquid 4 by a discharge mechanism (not shown). In this case, the means for controlling the flow rate is not particularly limited. By interposing the circulation flow control valve 2c downstream of the device 3, the circulation flow (delivery flow) in the circulation pipe 2 can be suitably controlled.

In the drawing, reference numeral 5 denotes a supply device for supplying the surfactant composition from a storage tank or line (not shown) into the circulation device 3, and one end of a supply pipe 6 is connected to the supply device 5. At the same time, the other end of the supply pipe 6 is connected to the circulation pipe 2 at a position upstream of the position where the circulation device 3 is provided, and the surfactant composition is supplied to the supply device 5.
Is supplied to the circulation pipe 2 through the supply pipe 6 and then into the circulation device 3. If the above-mentioned line has a supply capacity, the supply device 5 is unnecessary.

The stirring tank 1 is provided with a stirrer 9 comprising a stirring blade 7 and a motor 8 serving as stirring power for rotating the stirring blade 7. Here, in the case of the present invention, the capacity of the stirring tank 1 is not particularly limited, but in consideration of the production efficiency when manufacturing a final product, the stirring tank 1
Is preferably about 1 to 10 kiloliters, because it can be used as both a storage tank and a product mixing tank for a diluted product (the above surfactant composition diluted to the final target concentration). The stirrer 9 does not require any special device, and the stirring blade 7 may have a normal stirring force and a shearing force. For example, a general stirring blade such as a paddle or a propeller may be used. Can be used.

The circulating device 3 includes a stirring blade and a discharge mechanism (not shown).
The content liquid 4 is circulated at a predetermined flow rate in the mixing device A comprising the stirring tank 1 and the circulation pipe 2 in which the circulation device 3 is interposed, by appropriately using the circulation flow rate control valve 2c. Examples of an apparatus provided with such a discharge mechanism include a turbo pump and a line mixer.

The stirring blades of the circulation device 3 include:
Those having a tip speed of 10 m / s or more, preferably 20 m / s or more are used. If the speed is too slow, the surfactant composition cannot be dispersed in the content liquid. That is, in the case of the present invention, as described above, first, the surfactant composition is mixed with the content liquid 4 which is initially an aqueous solvent in the circulation device 3, and the surfactant composition is mixed with the aqueous solvent ( Content liquid)
In order to obtain a uniform solution or a uniform dispersion in a stirring tank, it is desirable to finely disperse the surfactant composition in this step as much as possible.
Therefore, it is necessary to use a stirring blade of the circulation device 3 that can secure the above-mentioned blade tip speed and apply a sufficient shearing force. As the circulation device 3, for example, a turbo pump is used. In this case, an open impeller or a semi-open impeller is preferably used as the stirring blade having such a blade tip speed and a shearing force. The capacity of the circulating device 3 is not particularly limited, but is desirably, for example, a capacity such that the residence time of the circulating liquid can be secured for 0.1 second or more.

The supply device 5 is required to be able to supply the surfactant composition into the circulation device 3 at a predetermined speed even if the surfactant composition is already of high viscosity. In order to dilute in a batch manner until the target dilution concentration is reached, it is sufficient that a predetermined amount corresponding to the target dilution concentration with respect to the amount of the aqueous solvent charged in the stirring tank 1 can be finally supplied. A high-precision pump such as a plunger is not required, and a general device such as a gear, a rotary, or a snake pump can be used. In addition,
The supply pipe 6 may be provided so that the surfactant composition can be supplied from the supply device 5 into the circulation device 3. In the case of the present invention, the content of the surfactant composition in the circulation device 3 is reduced. When the surfactant composition is supplied into the circulation device 3 from the suction side of the circulation device 3, it is supplied from the suction side of the circulation device 3 because the dispersion having the increased interfacial area dispersed therein is returned to the stirring tank. Preferably, the other end of the supply pipe 6 is
As described above, one end 2a of the normal circulation pipe 2 is connected to the upstream side of the position where the circulation device 3 is provided.
It is preferable that one end 2a of the circulation pipe 2 is connected to the vicinity of the circulation device 3 (near the supply port).

According to the dilution method of the present invention, a predetermined amount of the aqueous solvent is first charged into the stirring tank 1 using the mixing device A, and the surfactant composition is charged from a storage tank or line (not shown). An amount capable of supplying a predetermined amount corresponding to the target dilution concentration with respect to the aqueous solvent amount into the circulation device 3 is prepared. Here, the target dilution concentration is not particularly limited, but is usually 30% or less as a surfactant concentration.
If the target dilution concentration is too high, the liquid in the mixing device may gel, and circulation may be difficult. In addition, in the case of the present invention, the dilution temperature is not particularly limited, but it is preferable that the dilution temperature is equal to or higher than the solidification temperature of the usually supplied surfactant composition. If the dilution temperature is lower than the above-mentioned temperature, the surfactant composition may be solidified when it comes into contact with an aqueous solvent. Therefore, it is desirable that the stirring tank 1, the storage tank, and the circulation device 3 are temperature-controlled at the dilution temperature.

Next, the circulating device 3 is operated to activate the stirring tank 1.
Initially, the supply device 5 is operated while circulating the content liquid 4 which is the aqueous solvent at a predetermined delivery flow rate, and the surfactant composition in the storage tank is circulated in the circulation device 3 at a predetermined supply flow rate. To supply. Here, in the dilution method of the present invention, it is important that the content liquid delivery flow rate and the surfactant composition supply flow rate are such that the delivery flow rate is 2 times or more, particularly 5 to 15 times the supply flow rate by weight. is there. If the delivery flow rate ratio is too small, the concentration of the surfactant in the mixing device A becomes high, which may cause gelation. That is, in the dilution method of the present invention, in the mixing step in the circulation device, the two are mixed by applying the above-described shearing force, and the mixed dispersion is discharged from the discharge port of the circulation device into the circulation pipe. In this case, it is necessary to dilute the high-viscosity surfactant composition or the high-viscosity surfactant composition to a fluid viscosity, and the viscosity at the discharge port is 3000 cP or less, particularly 50 cP.
It is desirable to be 0 cP or less. Here, since a normal surfactant has a high viscosity region at a concentration of 30 to 60%, in order to dilute to such a viscosity, at the discharge port of the circulation device, the surfactant concentration is reduced to a low viscosity of 30% or less. A content liquid (diluent) amount that can be diluted up to the region is required, and from this, the above-mentioned delivery flow rate / supply flow rate ≧ 2 (weight ratio) is calculated. The upper limit of the ratio is not particularly limited, but in consideration of the pump capacity of the circulation device and the residence time of the content liquid and the surfactant composition in the circulation device, the ratio is not more than 20 times. Desirably.

In the present invention, the surfactant composition can be intermittently supplied as long as the ratio between the content liquid delivery flow rate and the surfactant composition supply flow rate is within the above range. Considering, for example, the easiness of uniformly dissolving and dispersing the surfactant, it is desirable to continuously supply the surfactant composition.

Here, the flow rate of the content liquid and the flow rate of the surfactant composition are not particularly limited as long as the above-mentioned ratio is satisfied. (Amount of liquid in tank) / (Content liquid delivery flow rate)
= 5 to 50 (minutes), and particularly preferably about 10 to 20 minutes. If the content liquid delivery flow rate is too low, the temperature of the circulating liquid may increase due to stirring heat, and if it is too high, it may be difficult to uniformly disperse the surfactant. The residence time of the content liquid and the surfactant composition in the circulation device is preferably about 0.1 to 5 seconds. If the residence time is too long, the temperature may increase due to the heat of stirring. If the residence time is too short, it may be difficult to uniformly disperse the surfactant.

In the mixing step in the circulating apparatus, the mixed dispersion in which the surfactant composition is dispersed in the content liquid is returned to the stirring tank via the circulating pipe, so that the residence time can be sufficiently increased in the stirring tank. Is performed, and the surfactant composition is uniformly dissolved or uniformly dispersed. In this case, the stirring power may be a normal stirring power, and for example, it is preferable that the dispersed surfactant (composition) does not float or settle, and the entire liquid in the tank flows.

Further, the surfactant composition can be diluted to a target concentration by continuing the above steps until the above-mentioned predetermined amount of the surfactant composition in the storage tank is supplied into the circulation device. . In addition, the supply time of the surfactant composition is not particularly limited, and can be appropriately selected depending on the capacity of the stirring tank 1, the surfactant concentration before and after dilution, and the like. In addition, in the case of the dilution method of the present invention, after the supply of the surfactant composition is completed, depending on the state of the liquid, circulation / stirring may be further continued as necessary to allow more uniform dissolution and uniform dispersion. .

According to the above-mentioned method, a predetermined ratio of the surfactant composition and the content liquid in the stirring tank composed of an aqueous solvent are mixed in a circulation device, and the surfactant composition in a high viscosity state is mixed with the aqueous composition. After dispersing in the solvent, the surfactant composition having an increased interfacial area is stirred in a stirring tank that can take a sufficient residence time, so that the surfactant composition can be uniformly dissolved or uniformly dispersed in the content liquid. . The present invention provides a batch-type dilution method for repeatedly circulating the content liquid in which the surfactant composition is uniformly dissolved or uniformly dispersed from the stirring tank, and repeatedly diluting the surfactant composition at a predetermined ratio. As the dilution proceeds, the concentration of the surfactant in the diluent (the circulating content liquid) increases, and the affinity between the surfactant composition and the diluent increases. The surfactant composition can be diluted, and the surfactant composition can be efficiently diluted without generating lumps or gelling despite using simple equipment.

The surfactant composition diluent diluted by the dilution method of the present invention is prepared by diluting the surfactant composition at the time of its production or blending various additives after the dilution for commercialization. It can be suitably used in the manufacture of products, and such products include, for example, liquid detergents such as dishwashing detergents, vegetable detergents, shampoos, detergents for clothing, cosmetics such as rinses, and fibers such as softeners. Finishing agents and the like. When the above-mentioned product is manufactured, various additives that are usually added to the product may be previously added to the above-mentioned aqueous solvent as described above, and various additives may be added to the diluent of the above-mentioned surfactant composition. An agent can be blended, mixed and stirred by a conventional method to produce a product.

[0027]

According to the method for diluting a surfactant composition of the present invention, a surfactant composition having a high viscosity or a surfactant composition which becomes highly viscous when diluted with an aqueous solvent can be produced by a complicated method. Even without using an apparatus and a high-precision metering pump, dilution can be performed efficiently without causing gelation or lumpy lump. Therefore, the present invention is suitable as a method for producing a high-viscosity surfactant-containing composition used as a fiber finish such as a hair rinse, cream, emulsion, liquid detergent, and softener.

[0028]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Examples 1 to 5 and Comparative Examples 1 and 2] A turbo pump having an open stirring blade (impeller) was used as a circulation device (circulation pump) of the mixing device A shown in FIG. The above three types of aqueous solvents were diluted to the dilution temperatures shown in Table 1 when a paddle stirring tank having a capacity of 1000 liters was used as the aqueous solvent and three types of purified water 5% ethanol aqueous solution 5% propylene glycol aqueous solution were used. While circulating 500 liters of any of the above at the delivery flow rate (relative to the supply rate) shown in Table 1 by the turbo pump, the surfactant composition having the dilution temperature shown in Table 1 was stirred with an impeller (impeller) as shown in Table 1. The surfactant was supplied into the turbopump at a rate of 5 kg / min for 10 minutes from near the suction of the turbopump rotated at the impeller peripheral speed shown, and the surfactant composition was diluted with an aqueous solvent. After dispersion diluted to a target dilution and, without supplying a surfactant composition, further circulated by 5 minutes turbo pump, and followed by stirring, to obtain a diluted mixture of the surfactant composition. The diluted product of the obtained surfactant composition was sampled from the upper, middle, and lower stages of the stirring tank, and each sample was visually observed and evaluated according to the following evaluation criteria. In each of Examples and Comparative Examples, the dilution method (the above conditions) ) Were the same, the evaluation results did not change even when any of the three aqueous solvents was used. The results are also shown in Table 1. In the table,% means% by weight. <Evaluation Criteria> ：: Uniform dissolution or uniform dispersion [No lumps are visually observed] △: Gel particles of about 100 microns exist [Lummers disappear after standing for about 10 minutes] (within allowable range) ×: Several millimeters With gel particles (out of tolerance)

[0030]

[Table 1]

[Embodiment 6] Using the above turbo pump,
Using a paddle stirring tank having a capacity of 10 kiloliters as a stirring tank, 5 kiloliters of a 5% aqueous solution of sodium toluenesulfonate (aqueous solvent) at 25 ° C was circulated by the turbo pump at a delivery flow rate of 600 kg / min.
Suction of the above turbo pump in which a stirring blade (impeller) is rotated at a peripheral speed of 30 m / s with a 60% aqueous solution of sodium lauryl ether sulfate (surfactant composition) at 25 ° C. and 60% polyoxyethylene (EO = 3). After supplying the surfactant composition from the vicinity to the turbo pump at 200 kg / min for 10 minutes and diluting the surfactant composition with an aqueous solvent to disperse and dilute to a target dilution concentration, the surfactant composition is further supplied without supplying the surfactant composition. By circulating and stirring with a turbo pump for minutes, a diluted product of the surfactant composition was obtained, and the diluted product of the surfactant composition was evaluated in the same manner as described above. Uniform dissolution was observed. Therefore, according to the present invention, it is not only possible to perform a large amount of treatment in a short time as compared with the conventional dilution method, but also the stirring tank can be used also as a storage tank or a mixing tank for the diluted product, which is efficient. Admitted.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a mixing device illustrating an example of a mixing device used in the present invention.

[Explanation of symbols]

 A mixing device 1 stirring tank 2 circulation pipe 3 circulation device 4 contents liquid

Claims (1)

[Claims] 1. A method for diluting a surfactant composition having a high viscosity and / or a surfactant composition which becomes highly viscous when diluted with an aqueous solvent with an aqueous solvent, comprising: A circulating pipe having both ends communicating with the stirring tank and a mixing circulating device provided with stirring blades, and the liquid in the stirring tank is introduced into the circulating device from one end of the pipe. The mixing is performed in which the content liquid is mixed by the stirring blades of the circulation device, and the content liquid is returned from the other end of the pipe into the stirring tank through the discharge port of the circulation device. Using the device, after charging the aqueous solvent in the stirring tank, while circulating the content liquid comprising the aqueous solvent through the pipe while stirring in the stirring tank, the surfactant composition in the circulation device Object, its supply flow rate And the content liquid delivery flow rate from one end of the pipe is supplied so as to be 1: 2 or more, and the content liquid and the surfactant composition are supplied as a blade tip speed of the stirring blade of 10 m / s or more. A method for diluting a surfactant composition, which comprises mixing by adding a shear force of