JP2008279326A - Microbubble-containing liquid composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microbubble-containing liquid composition with an excellent stability of a microbubble which is an extremely fine bubble, and a microbubble stabilizer and a manufacturing method of the microbubble-containing liquid composition. <P>SOLUTION: This microbubble-containing liquid composition comprises: (A) a surfactant with a 12 to 18C perfluoroalkyl group; (B) a surfactant with a 6 to 10C perfluoroalkyl group; and bubbles. The microbubble stabilizer comprises the (A) and (B) components. The manufacturing method of the microbubble-containing liquid composition comprises the process of mixing the bubble in a liquid 4 containing the (A) and (B) components. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fine bubble-containing liquid composition.

  Various researches (for example, Non-Patent Document 1) have been conducted on the technology for miniaturizing bubbles, and 60 to 10 μm bubbles are used for fishery techniques such as aquaculture, and 10 to 3 μm bubbles are used for medical techniques such as ultrasound contrast agents. It has been put into practical use. If the bubbles are further refined, it is considered that the gas / liquid surface area per unit volume increases, the residence time in the liquid phase increases, the gas pressurizing effect in the bubbles, and the high gas dissolving power. Utilizing these properties, applications such as water purification, microbial culture, and chemical reaction between gas and liquid are expected.

  By further increasing the gas / liquid interface area by increasing the concentration of such fine bubbles, and by sufficiently diffusing the fine bubbles by prolonging the lifetime of the fine bubbles, an improvement in the effect in the above application can be expected. Examples of a technique for further miniaturizing the bubbles include a method of applying ultrasonic waves to electrolyzed water (for example, Patent Document 1) and a method of crushing fine bubbles in electrolyte-containing water (for example, Patent Document 2). Patent Document 3 also describes an example in which a porous material is dissolved to generate gas in water containing sodium dodecyl sulfate. However, the methods of Patent Documents 1 and 2 can obtain only a very low concentration of bubble-containing liquid, and the method of Patent Document 3 has a problem that the life of fine bubbles is short and the bubbles are enlarged when collecting the bubble-containing liquid. It was.

  As a technique related to fine bubbles having a high concentration and a long lifetime, an ultrasonic contrast agent technique can be exemplified. For example, Patent Documents 4 and 5 disclose ultrasonic contrast agents that are long-lived and high-density fine bubbles by using a specific surfactant. Patent Documents 6 and 7 disclose the use of a fluorosurfactant, but there is no description of the cell diameter when a fluorosurfactant is used, and the effect of mixing specific components is not expected. It was not. In any case, the ultrasonic contrast agent method can obtain only a small amount of the bubble-containing liquid composition at one time, and cannot be used industrially.

As described above, an industrially effective method for collecting fine bubbles has not been realized. In consideration of industrial use such as industry and agriculture, there is a demand for a microbubble-containing liquid containing fine bubbles that can be continuously collected, which cannot be achieved by the above-described technology.
JP 2003-334548 A JP 2005-245817 A JP 2005-169359 A JP-A-8-176017 Japanese National Patent Publication No. 8-502979 JP-T-9-501164 JP-T-2001-517192 "Chapter 6 of Bubble Engineering", Editor: Ishii Ikuo

  The present invention provides a fine bubble-containing liquid composition which is extremely fine bubbles and excellent in stability of the fine bubbles.

The present invention relates to a fine bubble-containing liquid composition containing the following component (A), component (B) and bubbles.
(A) A surfactant having a C12-18 perfluoroalkyl group.
(B) A surfactant having a C 6-10 perfluoroalkyl group.

Moreover, this invention relates to the microbubble stabilizer containing the following (A) component and (B) component.
(A) A surfactant having a C12-18 perfluoroalkyl group.
(B) A surfactant having a C 6-10 perfluoroalkyl group.

Moreover, this invention is a manufacturing method of the fine bubble containing liquid composition including the process of mixing gas in a liquid, Comprising: The said liquid contains the following (A) component and (B) component The fine bubble containing liquid composition The present invention relates to a method for manufacturing a product.
(A) A surfactant having a C12-18 perfluoroalkyl group.
(B) A surfactant having a C 6-10 perfluoroalkyl group.

  According to the fine bubble-containing liquid composition and the fine bubble stabilizer of the present invention, it is possible to collect very fine bubbles and stable fine bubbles. Moreover, according to the manufacturing method of the liquid composition containing fine bubbles of the present invention, the fine bubbles can be efficiently produced.

The present invention relates to a fine bubble-containing liquid composition containing a component (A), a component (B) and bubbles.
(A) A surfactant having a C12-18 perfluoroalkyl group.
(B) A surfactant having a C 6-10 perfluoroalkyl group.

  The fine bubbles in the present invention preferably represent bubbles having an average bubble diameter of 5 μm or less, more preferably 3 μm or less, from the viewpoint of more manifesting the effects of the present invention. The lower limit of the average bubble diameter is not particularly limited, but from the viewpoint of ease of handling, it preferably represents a bubble of 0.01 μm or more, and more preferably represents a bubble of 0.05 μm or more. In addition, the average bubble diameter of a bubble can be measured with the measuring method described in the Example here.

  According to the present invention, a fine bubble-containing liquid composition in which bubbles are extremely fine and the bubbles exist for a long time can be collected. In general, bubbles are thermodynamically unstable, causing coalescence of bubbles to coalesce, contraction in which gas dissolves from the bubble into the surrounding liquid, and conversely, surrounding dissolved gas is taken into the bubble. It is known to cause growth. Especially in the case of fine bubbles, the internal pressure of bubbles with a diameter of around 1 μm, for example, due to the action of Laplace pressure due to interfacial tension increases from several to several tens of atmospheres. It has only a lifetime.

  The reason why the effect of the present invention is manifest is not clear, but it is considered that the inherently unstable fine bubbles are stabilized by the component (A) and this stabilization is efficiently performed by the component (B). It is done.

  That is, the component (A) of the present invention has a high Kraft point and is thermodynamically concentrated at the bubble interface, so a rigid membrane (for example, “Colloidal Science II-Associated Colloids and Thin Films”, 1995, Chapter 9, p295), so that the coalescence of fine bubbles is suppressed, or the formed rigid membrane suppresses gas permeability, thereby reducing the gas permeability from the inside of the bubbles to the liquid. It is considered that the life has been extended in order to suppress the dissolution of gas.

  However, since the component (A) has low solubility in the liquid and the adsorption rate at the bubble interface is slow, coalescence and contraction occur before the component (A) forms a rigid film. Therefore, since the component (B) is adsorbed early and suppresses coalescence and shrinkage of the fine bubbles, and the component (A) can exist as fine bubbles until the rigid film is formed, the effect of the present invention is achieved. It is considered to be expressed. In addition, the component (A) dissolved in the liquid decreases by adsorbing to the bubble interface film, but the component (B) becomes (A) because the component (A) and the component (B) are present at a specific ratio. It is considered that the effect of the present invention is further manifested by solubilizing the component or forming mixed micelles and efficiently dissolving the component (A) to promote adsorption of the component (A).

<Surfactant having a perfluoroalkyl group>
Component (A) and component (B) of the present invention are surfactants having a perfluoroalkyl group.

  Preferred surfactants having a perfluoroalkyl group of the present invention include anionic fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphate monoesters; Cationic fluorosurfactants such as trimethylammonium salts; amphoteric fluorosurfactants such as perfluoroalkylbetaine and perfluoroalkylsulfobetaine; nonionics such as perfluoroalkylamine oxide and perfluoroalkylethanol ethylene oxide adducts Fluorinated surfactants. Among these, an anionic fluorosurfactant is preferable from the viewpoint of a balance between water solubility and bubble stability, and perfluoroalkylcarboxylate is more preferable.

  Examples of the counter ion of the anionic surfactant include alkali metal ions such as sodium and potassium, alkaline earth metal ions such as magnesium and calcium, ammonium ions, and primary to tertiary ammonium ions. From the viewpoint of water solubility, monovalent ions are preferable, and alkali metal ions and ammonium ions are more preferable. In particular, ammonium ions are preferable from the viewpoint of a balance between water solubility and stability.

<(A) component>
(A) component of this invention is a surfactant which has a C12-C18 perfluoroalkyl group, and it is preferable that carbon number is 12-16 from a water-soluble viewpoint. In addition, the component (A) of the present invention is preferably a surfactant having a C 12-18 perfluoroalkyl group from the viewpoint of water solubility and bubble stability. Furthermore, a linear perfluoroalkyl group is more preferable from the viewpoint of bubble stability. In particular, it is preferable that the hydrophobic group is composed of a linear perfluoroalkyl group alone. In addition, (A) component may be used independently according to a use, or (A) component may be mixed and used.

<(B) component>
Component (B) of the present invention is a surfactant having a perfluoroalkyl group having 6 to 10 carbon atoms, and preferably 8 to 10 carbon atoms from the viewpoint of water solubility. The component (B) of the present invention is preferably a surfactant having a perfluoroalkyl group from the viewpoint of efficiently dissolving the component (A) and from the viewpoint of bubble stability. In addition, (B) component may be used independently according to a use, or (B) component may be mixed and used.

<Fine bubble-containing liquid composition>
The fine bubble-containing liquid composition of the present invention comprises (A) a surfactant having a C12-18 perfluoroalkyl group and (B) a C6-10 perfluoroalkyl group. And a surfactant having The weight ratio of the component (A) to the component (B) is preferably (A) / (B) = 1/5 to 1/100 from the viewpoint of obtaining finer bubbles. More preferably, (A) / (B) = 1/5 to 1/50, still more preferably (A) / (B) = 1/10 to 1/40, and particularly preferably (A) / (B) = 1/15 to 1/40.

  The total amount of the component (A) and the component (B) in the fine bubble-containing liquid composition is preferably 0.001 to 10% by weight from the viewpoint of finer and higher concentration of the bubbles of the present invention. More preferably, it is 0.005-1 weight%, More preferably, it is 0.005-0.1 weight%.

  Examples of the main component of the liquid constituting the fine bubble-containing liquid composition of the present invention include water, fats and oils, and organic solvents. Water is preferable from the viewpoint of finer bubbles and longer life.

<Bubble>
The gas constituting the bubbles used in the present invention is appropriately selected, and examples thereof include air, nitrogen gas, oxygen gas, ozone gas, methane gas, hydrogen gas, and carbon dioxide gas. Air, nitrogen gas, oxygen gas, ozone gas, methane, and hydrogen gas are preferable from the viewpoint of finer bubbles, higher concentration, and longer life, and air is preferable from the viewpoint of simplicity.

<Fine bubble stabilizer>
The fine bubble stabilizer of the present invention contains the following components (A) and (B).
(A) A surfactant having a C12-18 perfluoroalkyl group.
(B) A surfactant having a C 6-10 perfluoroalkyl group.

  The fine bubble stabilizer of the present invention may be only the components (A) and (B), or may contain those listed as the main components of the liquid.

<Method for producing fine bubble-containing liquid composition>
The fine bubble-containing liquid composition of the present invention is obtained by a step of mixing a gas into a liquid containing the following components (A) and (B).
(A) A surfactant having a C12-18 perfluoroalkyl group.
(B) A surfactant having a C 6-10 perfluoroalkyl group.

  The liquid used in the present invention contains the component (A), the component (B) of the present invention, and the main component of the liquid. Specific examples of the liquid used in the present invention include a surfactant aqueous solution when the main component of the liquid is water.

  The temperature of the liquid during the production is preferably about room temperature from the viewpoint of obtaining fine bubbles, specifically 5 to 35 ° C is preferable, and 10 to 30 ° C is more preferable.

<Process for mixing gas into liquid>
Examples of the process of mixing the gas into the liquid include, for example, Gas-Liquid 2 described in Ikuo Ishio, “Foam Engineering”, Chapter 6, pages 424-425 (March 25, 2005, published by Techno System Co., Ltd.). A layer fluid mixing / shearing method, a pore method, a pressure control method, a gas-liquid two-phase fluid mixing / shearing method, an ultrasonic method, and the like can be used. From the viewpoint of obtaining a high-concentration microbubble-containing composition, a gas-liquid two-layer fluid mixing / shearing method, a pore method, and a pressure control method are preferable, and a pore method and a pressure control method are more preferable. The gas-liquid two-layer fluid mixing / shearing method, the pore method, and the pressure control method will be described below.

<Gas-liquid two-layer fluid mixing / shear method>
In the case of employing the gas-liquid two-phase fluid mixing / shearing method, the step of mixing the gas into the liquid can be performed before or after the liquid feed pump or in the liquid feed pump. When gas is mixed in the liquid before the liquid feed pump and in the liquid feed pump, the gas can be forcibly mixed by applying pressure to the gas. As another method, self-sufficiency can be mixed using negative pressure. When gas is mixed after the pump, the gas is forcibly mixed by applying pressure to the gas. The mixed gas is sent as a coarse bubble to the generator together with the liquid, and is generally caused to collide with a rotating body or a protrusion by the generator, or is crushed by the shearing force of the liquid to which rotation is applied, and microbubbles are formed. obtain.

  From the viewpoint of increasing the concentration of fine bubbles, it is preferable to use the Venturi tube method described in JP-A-2003-230824. In this case, a gas pressurized from the needle just before the venturi tube having the throttle portion is mixed, and after the high-speed fluid passes through the throttle portion in the venturi tube, the gas is taken in using a shock wave generated in the pressure release process. Is crushed to obtain microbubbles.

<Pore method>
In the case of adopting the pore method, the step of mixing the gas into the liquid can be performed by mixing the gas into the liquid through the pores such as the porous membrane. Specifically, for example, the liquid is brought into contact with one of the porous membranes, and the other side of the porous membrane is brought into contact with the pressurized gas, so that the gas is porous through the pores of the porous membrane. It passes through the holes and is mixed into the liquid. When the porous membrane is tubular, the liquid can be continuously flowed in one direction in the tube of the tubular porous membrane, and gas can be injected from outside the tube through the pores of the porous membrane. .

  Examples of the gas pressurization method include a method of forcibly filling a gas in the sealed space, and a method of compressing the air with a piston after filling the gas in the sealed space. The pressure is appropriately set, but 1 to 10 MPa is preferable, and 2 to 5 MPa is more preferable.

  Regarding the pore diameter of the porous membrane, it is preferable that the pore diameter is uniform from the viewpoint of collecting a uniform bubble diameter, and from the viewpoint of collecting a finer bubble-containing liquid composition, the smaller pore diameter is preferable. . Therefore, the average pore diameter of the porous membrane is preferably 0.01 to 1 μm, more preferably 0.05 to 0.2 μm, and still more preferably 0.05 to 0.1 μm. The average pore diameter of the porous membrane can be determined by measuring with a mercury porosimeter.

  Preferred examples of the porous film having pores include glass, ceramics, silicon, and polymers, and glass (porous glass) is more preferred. The porous glass can be produced by utilizing microphase separation of glass as in, for example, Japanese Patent No. 1504002 and Japanese Patent No. 1518989. The shape of the porous glass may be tubular or flat. As a commercially available porous glass, for example, an SPG film manufactured by SPG Techno Co., etc. can be suitably used.

  From the viewpoint of finer bubbles in the present invention, it is preferable to further apply ultrasonic treatment at the “step of mixing gas into the liquid” in the pore method. This is presumed that the bubbles can be further miniaturized by applying bubbles such as ultrasonic waves to the pore system so that the bubbles are detached from the porous membrane at an early stage.

  As a method for applying the ultrasonic treatment of the present invention, for example, it can be carried out in a treatment liquid stored in a treatment layer equipped with an ultrasonic generator. It can be performed by immersing the unit of “the step of mixing gas into”.

  The transmission frequency and output, which are the conditions for ultrasonic treatment, are selected as appropriate. The oscillation frequency is preferably 20 to 200 kHz, and the output is preferably 20 to 400 W.

  The treatment liquid stored in the treatment layer provided with the ultrasonic generator is appropriately selected, and examples thereof include water and alcohol, and water is preferable from the viewpoint of economy.

<Pressure control method>
In the case of adopting the pressure control method, the step of mixing the gas into the liquid is, for example, dissolving the gas in the liquid under pressure and then reducing the pressure to generate the gas from the supersaturated dissolved gas. Specifically, for example, (1) a method using a gas-liquid mixing pump such as a vortex pump and pressurizing a liquid and gas sucked from the pump suction side while mixing and stirring, and (2) a dissolution tank is provided. After the gas is dissolved in the liquid by pressurization, a method of reducing the pressure of the liquid and (3) a method of generating the dissolved gas as bubbles in the liquid by releasing it into the atmosphere can be employed. In addition, in these methods, the timing which contains said (A) component and (B) component in a liquid should just be before depressurizing and generating gas from the supersaturated dissolved gas. Therefore, it may be before or after gas is mixed into the liquid under pressure and dissolved.

  The pressure of pressurization by these methods is appropriately set, but it is preferably high pressure from the viewpoint of finer bubbles and higher concentration, preferably 0.2 to 10 MPa, more preferably 0.5 to 10 MPa. .

The average bubble diameter of the bubbles in the fine bubble-containing liquid composition of the present invention is the average bubble diameter based on the number, and can be controlled by appropriately selecting the liquid component, the step of mixing gas into the liquid, and the like. The average cell diameter is preferably 5 μm or less, more preferably 3 μm or less. The lower limit of the average cell diameter is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.05 μm or more from the viewpoint of ease of handling. From this viewpoint, the average bubble diameter of the bubbles is preferably 0.01 to 5 μm, and more preferably 0.05 to 3 μm.
In addition, the average bubble diameter of a bubble can be measured with the measuring method described in the Example here.

  The lifetime of the bubbles in the fine bubble-containing liquid composition of the present invention is the time required for spontaneous disappearance of the bubble-derived white turbidity, and is controlled by appropriately selecting the liquid component and the step of mixing the gas into the liquid. it can. The lifetime of the bubbles is preferably 1 minute or longer, more preferably 3 minutes or longer, and further preferably 4 minutes or longer. Here, the average lifetime of bubbles can be measured by the measurement method described in the examples.

The concentration of bubbles in the fine bubble-containing liquid composition of the present invention is the number of bubbles present in 1 mL, and can be controlled by appropriately selecting the liquid component, the step of mixing gas into the liquid, and the like. A preferable bubble concentration is 1 × 10 ⁷ cells / mL or more. Here, the bubble concentration can be measured by the measurement method described in the examples.

  The fine bubble-containing liquid composition of the present invention can be applied to various uses such as cosmetics, agriculture, food, and the like by having a fine and durable effect.

  Hereinafter, the present invention will be described by way of examples. In the following examples and comparative examples,% means% by weight. Moreover, the physical-property evaluation described in the Example and the comparative example was implemented in accordance with the following method.

<Evaluation of bubble diameter>
The fine bubble-containing liquid composition discharged from each device was directly collected in a 1 L (liter) beaker, and the bubble diameter was evaluated in the following cases.
(1) Immediately after discharge of the liquid containing bubbles, bubbles rise (8 cm / 5 seconds), the liquid phase becomes transparent, and a cloudy state due to bubbles cannot be obtained.
(2) After discharging the liquid containing bubbles, a white turbid liquid with dispersed bubbles can be obtained once, but the white turbid part immediately rises (8 cm / 3 min or more) and finally the liquid phase becomes transparent.
(3) After discharging the liquid containing bubbles, a cloudy liquid with dispersed bubbles is obtained, and the white cloudy part floats very slowly (8 cm / 3 minutes or less) or does not float but can be observed with a microscope.

  In the case of (1), since the ascent speed is very high, it is apparent from the following Stokes formula that the distance is 100 μm or more. Therefore, the bubble diameter in the result in the case of (1) was evaluated as 100 μm or more.

  The Stokes equation is as shown in (Expression 1).

[Where r is the bubble radius, Δρ is the density difference between air and water (substantially the density of water), g is the acceleration of gravity, η is the viscosity of water, and v is the rising speed of the bubbles. ]
In the case of (2), as a result of converting the ascent rate of 8 cm / 3 minutes to the bubble diameter from the Stokes' formula, it is found that it is 25 μm or more. Therefore, the bubble diameter in the result in the case of (2) was evaluated to be 25 μm or more.

In the case of (3), since the ascent was very slow, it was difficult to use the Stokes equation. Therefore, the bubble diameter was evaluated by the following method.
(Light scattering diffraction method)
The bubble diameter was measured using a LA-910 (Horiba Seisakusho) light scattering diffraction particle size measuring apparatus. The liquid composition containing fine bubbles discharged from each device was collected in a 1 L beaker. In order to obtain a bubble concentration suitable for measurement, the liquid composition containing fine bubbles collected using a dropper was gently poured into a batch measurement cell, and diluted to about ½ in the cell using ion-exchanged water. The relative refractive index, which is a necessary variable for measurement, was set to “0.76”, which is the relative refractive index of gas with respect to water.

In Examples 5 to 8, the bubble diameter was evaluated by the following method.
(Microscopy)
Observation with a microscope (Digital Microscope VHX-100 manufactured by Keyence Corporation) was performed. When bubbles were observed, the bubbles in the observation field (677 μm × 508 μm) were two-colored with the software attached to the microscope, and the area of each bubble was calculated. The number-based distribution was calculated by converting the area of each of the obtained bubbles into an equivalent circle diameter, and the average bubble diameter was calculated.

  It should be noted that the time required for measuring the bubble diameter immediately after discharging the bubble-containing liquid was 3 minutes.

(Examples 1-4, Comparative Examples 1-3)
This will be described with reference to the drawings. In the following drawings, the same parts are denoted by the same reference numerals, and description of the repeated parts may be omitted.

  As shown in FIG. 1, a fine bubble-containing liquid composition was collected using a venturi-type microbubble generator described in Japanese Patent Application Laid-Open No. 2003-230824. Specifically, fine bubbles were generated using an acrylic resin Venturi tube 1 having an inner diameter of 8 mm and a throttle portion having an inner diameter of 3 mm. The gas was supplied at a rate of 0.4 L / min from a needle 2 having an inner diameter of 0.8 mm arranged immediately before the venturi pipe 1 from a gas supply pipe 2b using a compressor 2a. The liquid was supplied from the liquid supply pipes 3a and 3b using the pump 3 and circulated through the surfactant aqueous solution 4 at 8 L / min until microbubbles were generated. The obtained fine bubble-containing liquid composition 5 was collected in a 1 L beaker from the collection pipe 5a. The ambient temperature was 25 ° C.

  Table 1 shows the surfactant composition of the surfactant aqueous solution and the bubble diameter (light scattering diffraction method) in the collected fine bubble-containing liquid composition. When the activator having the composition shown in Examples 1 to 4 in Table 1 was used, the liquid discharged from the venturi tube became cloudy and it was difficult to visually confirm the bubbles. When the bubble diameter was measured by a light scattering diffraction method, the average bubble diameter was 5 μm or less in all cases.

  Examples 2 to 4 are cases where the ratio (A) / (B) of Example 1 was changed to increase the weight ratio of the component (B). Compared to Example 1, it contained finer bubbles.

  The comparative example 1 is a case where surfactant is not contained (only ion-exchange water). As a result, only bubbles that float immediately after discharge were obtained, and a liquid composition containing fine bubbles as in the present invention could not be obtained.

  Comparative Examples 2 and 3 are cases where each component of the activator is alone. In the case of only component (B) (Comparative Example 2), a cloudy liquid was once obtained, but the floating of 8 cm bubbles was confirmed within 3 minutes. When the bubble diameter was calculated based on the Stokes equation (Equation 1), it was found to be 25 μm or more. In the case of only the component (A), a cloudy liquid was obtained and the bubble was slowly rising, and the bubble diameter was measured by a light scattering diffraction method to find a large bubble of about 10 μm.

(Examples 5-8, Comparative Example 4)
A porous glass membrane (SPG techno SPG membrane: 5 × 125 mm: pore diameter 0.08 μm) shown in FIG. 2 is pumped into the inner passage 3c of the pipe 6 at a flow rate of 6 L / min with a surfactant 3. It supplied from the piping 3a. Gas was injected from the pressure cylinder 2d and the air supply pipe 2b to the outside of the porous membrane tube at 3 MPa from the gas injection unit 17 through the glass porous membrane 6 into the inner passage 3c. Using this apparatus, the bubble-containing liquid composition was discharged to the pipes 3a and 5a by the pore method (porous membrane method) at an environmental temperature of 25 ° C. The pipe 3a is a circulation circuit, and the pipe 5a is a bubble collecting circuit. The obtained fine bubble-containing liquid composition 5 was collected in a 1 L beaker from the collection pipe 5a. Table 2 shows the experimental conditions and the bubble diameter (microscopic method) in the obtained fine bubble-containing liquid composition.

  Example 5 is a case where a bubble-containing liquid was discharged by this apparatus using the composition of Example 1. The discharged liquid became cloudy and it was difficult to visually confirm the bubbles. When the bubble diameter was measured by a microscopic method, it contained 3 μm or less and finer bubbles than the venturi method.

  Example 6 is a case where vibrations derived from ultrasonic waves (40 kHz, 55 W) were further applied to the entire apparatus as shown in FIG. 3 under the same conditions as in Example 5. The entire apparatus is immersed in water 8 in the water tank 7 and ultrasonic waves (40 kHz, 55 W) are applied to the water from the ultrasonic transmitter 9 to separate fine bubbles generated inside the glass porous membrane tube 6 by vibration. And released. Otherwise, bubbles were generated in the same manner as in Example 5. Since the outside of the tubular porous membrane is covered with the gas phase, the ultrasonic wave does not reach the liquid phase inside the porous membrane, and the action of the ultrasonic wave in this experiment gives vibration to the entire device. It is thought that it is only. As a result, it can be seen that a fine bubble-containing liquid composition in which the bubbles were further refined as compared with Example 5 was obtained.

  Examples 7 and 8 are cases where the weight ratio of the component (B) was increased by changing the weight ratio (A / B) of the component (A) and the component (B) in the surfactant composition of Example 6. It can be seen that a fine bubble-containing liquid composition in which bubbles are further refined than in Example 6 is obtained.

  Comparative Example 2 is a case where no surfactant is contained (only ion-exchanged water). As a result, only bubbles that float immediately after discharge were obtained, and the fine bubble-containing liquid composition as in the present invention could not be obtained.

(Examples 9 to 13, Comparative Example 5)
As shown in FIG. 4, bubbles were generated by adding a surfactant from between a pressure dissolution tank and a nozzle of a pressure increase / decrease control type microbubble generator (AWAWA manufactured by Resource Development Co., Ltd.). Specifically, ion exchange water 10 is flowed at 8 L / min, air is mixed at 0.2 L / min from the air supply pipe 2 b by the gas-liquid mixing pump 12, and the gas mixed in the dissolution tank 13 is dissolved at 0.8 MPa. After that, the ion-exchanged water was supplied toward the nozzle 15 in the discharge water tank 16. On the other hand, the surfactant aqueous solution 11 was mixed with the plunger pump 14 at 1 L / min and 1 MPa, and the pressure was released to the atmospheric pressure with the nozzle 15 to generate bubbles. At this time, the flow rate in the pipe after mixing the surfactant aqueous solution was 8 L / min, and there was no change before and after mixing. The microbubble-containing liquid composition 5 for evaluation was sampled in a 1 L beaker from the sampling pipe 5a. Table 2 shows the experimental conditions and the bubble diameter (light scattering diffraction method) in the obtained fine bubble-containing liquid composition.

  From the results shown in Table 2, it can be seen that a fine bubble-containing liquid composition containing fine bubbles is obtained. On the other hand, in the case where the surfactant is not added, it can be seen that the fine bubble-containing liquid composition as in the present invention cannot be obtained.

When the bubble lifetime in the bubble-containing liquid composition of Example 11 was measured using the method described in “Evaluation of bubble lifetime” below, the lifetime of the bubbles was 14 minutes. Furthermore, when the bubble concentration was measured using the method described in “Evaluation of bubble concentration” below, the bubble concentration was 2 × 10 ⁷ / mL. In other examples, a bubble-containing liquid composition having a similar bubble concentration can be obtained with a similar bubble lifetime.

<Evaluation of bubble life time>
The lifetime of bubbles was evaluated by the clouding time. That is, when the bubble-containing liquid that is clouded with bubbles is measured with a spectrophotometer, the bubbles are scattered and the transmitted light is reduced. Therefore, the scattered component is measured as the absorbance. Therefore, the bubble-containing liquid immediately after ejection is injected into the optical cell having an optical path length of 1 cm with a dropper, and the absorbance at 660 nm is measured by a time scan with a spectrophotometer (Hitachi U-2000A), and the absorbance is 0.2 or less. The time was defined as the lifetime of bubbles.

<Evaluation of bubble concentration>
The concentration of bubbles in the present invention was calculated by the following formula 2 using the absorbance measured in the “evaluation of bubble lifetime” described in the previous term.

In the formula, D is absorbance, N is the number of particles per unit volume, and d is the particle diameter. In addition, said numerical formula 2 is calculated | required according to the following. According to the document of D.H.Melik and H.S.Fogler Journal of Colloid and Interface Science 92 (1983) 161, the absorbance is derived from the relationship of Equation 3 from the particle concentration and particle radius.

In the formula, D is the absorbance, L is the optical path length, N is the number of particles per unit volume, and r is the particle radius. Q is a scattering efficiency, which is a function having the particle radius r, the refractive index ratio m of the particle to the medium, and the incident light wavelength λ as variables. The scattering efficiency Q is fixed at λ = 660 nm, m = 0.75 (refractive index of air / refractive index of water = 1.00 / 1.33), and when Q is numerically calculated, the effective scattering area πr2Q (μm ² ), the relationship of the bubble diameter d (μm) and the formula 4 is obtained. Even when other gases are used, the same is obtained by fixing the refractive index of air to 1.00.

Here, log is a common logarithm. By substituting Equation 4 into Equation 3 and expressing the number of bubbles per unit volume as L = 1 cm = 10 ⁴ μm, Equation 2 can be obtained.

  From the above results, it can be seen that according to the production method of the present invention, a fine bubble-containing liquid composition containing a high concentration of fine bubbles having a long life can be collected. Thus, the effect of fine bubbles can be further improved by the fine bubble-containing liquid composition as compared with the conventional case.

FIG. 1 is an explanatory view of a venturi-type bubble generation method in one embodiment of the present invention. FIG. 2 is an explanatory diagram of a bubble generation method for injecting gas into an aqueous surfactant solution from the outside of the porous membrane in another embodiment of the present invention. FIG. 3 is an explanatory diagram of a method of generating bubbles while applying ultrasonic waves in addition to the method of FIG. FIG. 4 is an explanatory view of a method for generating bubbles when releasing pressure of a gas dissolved in a pressurized liquid in still another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Venturi pipe 2 Gas supply needle 2a Compressor 2b Gas supply pipe 3 Pump 3a Liquid supply pipe 3b Circulation pipe 4 Surfactant aqueous solution 5 Fine bubble-containing liquid composition 5a Collection pipe 6 Glass porous membrane pipe 3c Inner passage 2d Pressure cylinder 7 Water tank 8 Water 9 Ultrasonic transmitter 10 Ion exchange water 11 Surfactant aqueous solution 12 Gas-liquid mixing pump 13 Pressure dissolution tank 14 Plunger pump 15 Nozzle 16 Discharge water tank 17 Gas injection unit

Claims (5)

A fine bubble-containing liquid composition containing the following component (A), component (B) and bubbles.
(A) A surfactant having a C12-18 perfluoroalkyl group.
(B) A surfactant having a C 6-10 perfluoroalkyl group.   The fine bubble-containing liquid composition according to claim 1, wherein the weight ratio of the component (A) to the component (B) is in the range of (A) / (B) = 1/5 to 1/100.   The fine bubble-containing liquid composition according to any one of claims 1 to 3, wherein the surfactant of the component (A) and the component (B) is an anionic fluorosurfactant. The fine bubble stabilizer containing the following (A) component and (B) component.
(A) A surfactant having a C12-18 perfluoroalkyl group.
(B) A surfactant having a C 6-10 perfluoroalkyl group. A method for producing a fine bubble-containing liquid composition comprising a step of mixing a gas into a liquid,
The manufacturing method of the fine bubble containing liquid composition in which the said liquid contains the following (A) component and (B) component.
(A) A surfactant having a C12-18 perfluoroalkyl group.
(B) A surfactant having a C 6-10 perfluoroalkyl group.

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