JP2000287988A - Cavitation suppressant, acoustic coupler and ultrasonic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need for using a physical means such as a pump or the like by incorporating at least one chemical to reduce oxygen molecules. SOLUTION: An acoustic cavitation suppressant is composed of a composition containing at least one reducing agent to remove oxygen molecules from a liquid in which the suppression of generation of cavitation is desired. There is no special limitation for this substance to reduce oxygen molecules. However, it is desirable to incorporate at least one compound containing an enol form hydroxyl group in the ring. When air saturated water containing sodium ascorbate of a 1M concentration is radiated with ultrasonic an acoustic strength of 0 to 6 w/cm2, light scattering occurs at about 2 w/cm2 or higher, when sodium ascorbate is contained. When sodium ascorbate is not contained, light scattering occurs only at 5 w/cm2 or higher. Thus the strength of ultrasonic that produces cavitation can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for suppressing cavitation in a liquid, an acoustic coupling material containing the composition, and an ultrasonic transducer containing the acoustic coupling material.

[0002]

2. Description of the Related Art It is known that a cavitation phenomenon occurs when a liquid is irradiated with ultrasonic waves. Cavitation is the generation of bubbles in a narrow sense, but often includes the phenomenon of collapse of the bubbles after generation. In particular, it is known that cavitation exhibits a chemical and mechanical action under the condition in which bubbles are crushed and exerts an effect on the vicinity of the bubbles, and is used for accelerating a chemical reaction, homogenating biological tissues, and the like. However, if cavitation is generated at an unintended part, the following problem occurs. 1) Corrosion or destruction of the device 2) Obstruction of the arrival of ultrasonic energy at the target site For example, in ultrasonic treatment using cavitation, region A in FIG.
Should produce cavitation, but in areas B and C, cavitation should not occur.

[0003] As a measure for preventing the above-mentioned problems from occurring, the conventional methods include: 1) deaeration of a liquid;
2) Apply pressure. In these methods, if dissolved gas is present in the liquid, cavitation is extremely likely to occur due to bubbles originating from the gas.Therefore, the dissolved gas is removed by removing the dissolved gas from the liquid or increasing the pressure to remove the dissolved gas. This is to make it difficult to generate bubbles as a source.

[0004]

As described above, in an apparatus using ultrasonic waves, as a method of suppressing the generation of cavitation in a liquid, a method of preventing generation of bubbles from a dissolved gas has been used. Was. In these methods, it is necessary to include deaeration means or a pressurization means such as a pump in order to perform deaeration or pressurization by physical means. Is subject to restrictions. The present invention relates to a composition capable of suppressing the generation of cavitation without including physical means such as a pump in an apparatus, an acoustic coupling material including the composition, and an ultrasonic transducer including the acoustic coupling material. The purpose is to provide. It is another object of the present invention to reduce the size of the apparatus and the energy used when suppressing the generation of cavitation using a physical means such as a pump.

[0005]

In order to achieve the above object, the present invention provides a composition containing at least one chemical substance that reduces oxygen molecules, an acoustic coupling material containing the composition, and the acoustic coupling. It is an ultrasonic transducer containing a material. Usually, the dissolved gas contained in the liquid subjected to the ultrasonic irradiation is a component contained in the atmosphere. Nitrogen is the most abundant component in the atmosphere, but there is no known chemical that can efficiently react with dissolved nitrogen and be removed from the liquid. For this reason, as shown in the prior art, means for removing dissolved gas contained in the liquid by physical means or pressurizing the liquid is required. We have shown that the rapid progress of the cavitation process requires the involvement of oxygen molecules and oxygen-derived short-lived species. The present inventor has found that it can be suppressed, and reached the present invention. That is, the acoustic cavitation inhibitor of the present invention is composed of a composition containing at least one reducing agent that removes oxygen molecules from the liquid in which cavitation is to be suppressed. The substance that reduces oxygen is not particularly limited, but preferably contains at least one compound having an enol-type hydroxyl group in the ring.

[0006] When a reducing agent having low solubility in a target liquid is used, the reducing agent is solubilized by micelles formed by a surfactant or encapsulated in liposomes, or pseudo-dissolved using lipoprotein to form a liquid. It can be used by being dispersed. In addition, a reducing agent such as an unsaturated fatty acid that generates a short-lived species after binding to oxygen can be used together with a short-lived species capturing agent represented by carnodin, alcohol, and the like. When evaporation of a liquid serving as a solvent can be a problem, such as when the solvent is used for a long time, a water-soluble polymer or the like can be added.

[0007] The acoustic coupling material of the present invention is characterized in that the composition containing the cavitation inhibitor of the present invention is sealed in a bag made of a material having high ultrasonic permeability, for example, polyethylene, silicone rubber, or latex rubber. And In order to prevent the temperature of the liquid or gel in the bag from rising, a cooling unit using a refrigerant or a Peltier element can be provided. Further, a configuration may be adopted in which the composition containing the cavitation inhibitor in the bag is circulated.

[0008] The ultrasonic transducer of the present invention comprises the acoustic coupling material of the present invention. There is no particular limitation on the shape and the like.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, Test Examples and Examples of the cavitation inhibitor of the present invention will be specifically described, but the present invention is not limited to these Examples.

Test Example 1 Cavitation Inhibition Effect of Sodium Ascorbate in Liquid The effect of sodium ascorbate to suppress cavitation in water was measured using an apparatus having the structure shown in FIG. A glass test tube 11 containing a sample 10 is placed in an acrylic water tank 5 filled with degassed water 12, and 1 MHz ultrasonic waves are irradiated from an ultrasonic transducer 6 for 2 minutes. During the ultrasonic irradiation, the laser receiver 8 detects the scattering intensity of the laser light 7 emitted from the semiconductor laser oscillator 2 having a wavelength of 780 nm by the sample 10. When the intensity of the scattered light was higher than the noise level, it was determined that cavitation was generated. FIG. 3 shows an example of the test result. Ultrasonic waves were applied to air-saturated water containing sodium ascorbate at a concentration of 1 M and air-saturated water not containing ascorbic acid at a sound intensity of 0 to 6 W / cm 2. When sodium ascorbate is not included, light scattering occurs at 2 W / sq cm or more, whereas when ascorbic acid is included, light scattering occurs only at 5 W / sq cm or more. from this result,
It can be seen that the sodium ascorbate of the present invention increases the ultrasonic intensity causing cavitation by about 2.5 times. An experiment was performed using acetonitrile and pyridine instead of water as the solvent, and similar results were obtained.

Embodiment 1 Acoustic Coupling Material One embodiment of the present invention is shown in FIG. In 1 liter of pure water, 100 g of sodium ascorbate and 20 g of polyvinyl alcohol are dissolved in a rubber container 13 made of latex. When used in combination with an ultrasonic irradiation source, it is fixed to the ultrasonic irradiation source using the mounting hook 14.

Embodiment 2 Ultrasonic Transducer One embodiment of the present invention is shown in FIG. 0.25 liter of pure water, 25 g of sodium ascorbate, polyvinyl alcohol
The solution in which 5 g is dissolved is injected into the latex rubber bag 17 from the liquid inlet / outlet 18-a or 18-b attached to the transducer body 22. The injected solution is circulated by the pump 20. When circulating, a constant temperature device can be used to maintain the temperature of the solution properly.

[0013]

As described above, according to the present invention,
Cavitation generation in a liquid can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of regions where cavitation should occur and regions where cavitation should not occur in ultrasonic treatment using cavitation.

FIG. 2 is a diagram showing a configuration of an apparatus used for measuring an acoustic cavitation suppression effect in a liquid.

FIG. 3 is a graph showing experimental results on acoustic cavitation suppression by sulfite.

FIG. 4 is a diagram showing an example of an acoustic coupling material according to the present invention.

FIG. 5 is a diagram showing an example of an ultrasonic transducer according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Power supply 2 ... Laser oscillator 3 ... Sine wave generator 4a, 4b ... Amplifier 5 ... Water tank 6 ... Ultrasonic transducer 7 ... Laser light 8 ... Laser receiver 9 ... Computer for signal processing 10 ... Sample 11 ... Glass test tube 12 ... Deaerated water 13 ... Latex rubber container 14a, b, c, d ... Mounting hook 15 ... Liquid inlet / outlet 16 ... Bubble expelling opening 17 ... Latex rubber bag 18a, b ... Liquid inlet / outlet 19 ... Bag fixing device 20 ... Pump 21: Pump control device 22: Transducer body.

Claims (5)

[Claims] 1. A cavitation inhibitor comprising at least one substance capable of reducing oxygen. 2. The cavitation inhibitor according to claim 1, wherein the substance capable of reducing oxygen contains at least one compound having an enol-type hydroxyl group in the ring. 3. The cavitation inhibitor according to claim 2, wherein the compound having an enol-type hydroxyl group in the ring is ascorbic acid or a salt of ascorbic acid. 4. An acoustic coupling material comprising the inhibitor according to claim 1. 5. An ultrasonic transducer comprising the acoustic coupling material according to claim 4.