JPH05220143A - Acoustic medium - Google Patents

Abstract

PURPOSE:To provide the acoustic medium which has a shape retaining property and resilience and adequate elasticity without being affected by moisture and has the excellent acoustic characteristics to be used for ultrasonic diagnoses and ultrasonic treatments. CONSTITUTION:The gelatinous acoustic medium is obtd. by crosslinking and molding a compsn. contg. a rubbery elastic body, such as natural rubber or synthetic rubber, contg. double bonds within the molecule, an oily material dissolving the rubbery elastic body and org. peroxide by means, such as heating. The medium has acoustic characteristics similar to a living body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic medium used for performing in-vivo image diagnosis, livestock meat quality diagnosis, or treatment using ultrasonic waves.

[0002]

2. Description of the Related Art Heretofore, diagnosis using an ultrasonic diagnostic apparatus has been actively performed in order to diagnose abnormalities in internal tissues of a living body and pulsation of blood flow. In such ultrasonic diagnosis, ultrasonic pulses generated from a diagnostic device are applied to the body of the subject through a probe (probe) in close contact with the living body surface of the subject, and the reflected wave from the body is detected. ing. At this time, if the probe and the living body surface are not sufficiently adhered to each other at the time of diagnosis and an air layer or the like is present, the irradiated ultrasonic waves are greatly attenuated and an accurate diagnosis cannot be performed. A method of applying an oily material such as paraffin or polyethylene glycol, a paste-like material, or a jelly-like material to the surface of a living body to improve adhesion is adopted.

However, in the above method, the subject's living body surface is sticky and uncomfortable, and the oily substance is liable to flow, so that it cannot be applied uniformly and the diagnostic result tends to vary. I have. In addition, when diagnosing a region close to the body surface in ultrasonic diagnosis, it is necessary to move the focal region of the ultrasonic pulse emitted from the probe to the diagnosis region.

Therefore, a paste-like or jelly-like material that does not have a shape-retaining property and is easily flowable has poor handleability, so that an acoustic medium having a shape-retaining property and a thickness that can be freely changed is developed. Is desired.

In order to solve such a problem, a gel-like material having shape-retaining property, flexibility and moderate elasticity has been proposed as an acoustic medium for ultrasonic diagnosis in recent years. Examples of the material of such a medium include an aqueous gel containing an aqueous polymer substance and water described in JP-A-59-82838 and JP-A-1-146234, and JP-A-1.
For example, there is a polyurethane gel having a liquid segment in its internal structure, which is described in Japanese Patent Publication No. 304109.

However, although the drawbacks of the conventional oily substance, paste-like substance and jelly-like substance are solved in the acoustic medium using the above gel-like substance, the water-containing gel contains water because it contains water. However, there is a problem in storage such that the moisture content in the medium changes due to volatilization of contained moisture and the influence of humidity in the atmosphere and the flexibility is lost. Also, the raw materials that can be used for polyurethane gel are limited,
The fact is that practically useful ones have not yet been developed.

On the other hand, when used for the purpose of ultrasonic therapy, ultrasonic waves are applied to the affected area to cause local temperature rise, local circulation promotion, cell membrane permeability increase, etc., and thus analgesic effect, anti-inflammatory effect,
It is used for the treatment of chronic painful diseases for the purpose of relieving muscle spasms. Even in the application for such treatment, the ultrasonic energy cannot be sufficiently irradiated into the body of the subject unless the probe of the ultrasonic treatment device is in close contact with the living body. As with the case of using the shaped product, there are various problems.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of conventional acoustic media, and has shape retention, flexibility, and appropriate elasticity without being affected by moisture. Moreover, it is an object of the present invention to provide an acoustic medium having excellent acoustic characteristics.

[0009]

The inventors of the present invention have made extensive studies to achieve the above object, and as a result, contain an oily substance instead of an aqueous gel containing water and suppress blooming. The present inventors have found that a specific oily gel composition has excellent shape-retaining properties and acoustic properties, and completed the present invention.

That is, the present invention is obtained by crosslinking and molding a composition containing a rubber-like elastic material having a double bond in the molecule, an oily component that dissolves the rubber-like elastic material, and an organic peroxide. An acoustic medium is provided.

The acoustic medium of the present invention comprises a natural rubber, a synthetic isoprene rubber, a butadiene rubber, a styrene-butadiene rubber as a gel skeleton which imparts high elasticity, shape retention and flexibility.
Double bond in the molecule of acrylonitrile rubber, acrylonitrile-butadiene rubber, chloroprene rubber, styrene-chloroprene rubber, isobutylene-isoprene rubber, styrene-isoprene rubber, styrene-butadiene-styrene rubber, styrene-isoprene-styrene rubber, acrylic rubber, etc. A rubber-like elastic body having is used. Among these elastic bodies, it is preferable to use synthetic rubber, particularly butadiene rubber, isoprene rubber, and styrene-butadiene rubber, from the viewpoint of shape retention, flexibility and material stability. In these rubber-like elastic bodies, the double bond in the molecule undergoes a crosslinking reaction with the organic peroxide described later to form a gel, and has good elasticity and shape retention.

The amount of the oily substance contained in and held in the rubber-like elastic body is arbitrary depending on desired acoustic characteristics, gel strength, elastic modulus and the like. In the acoustic medium of the present invention, the rubber-like elastic body 3 is used. It is preferable to add about 100 parts by weight to about 150 parts by weight. Specific examples of the oily substance to be contained include vegetable oils such as olive oil and castor oil, mineral oils such as liquid paraffin and process oil, diethyl sebacate, dioctyl phthalate, dioctyl adipate, ethyl cinnamate, ethyl phenylacetate, and olein. Ester oils such as ethyl acidate and benzyl benzoate, animal oils such as squalane and squalene, and liquid emulsifiers are used.

The acoustic characteristics of the acoustic medium of the present invention can be arbitrarily changed depending on the purpose of use, but since the object is a living body in ultrasonic diagnostic and therapeutic applications, the acoustic characteristics are basically the same. It is preferable to match the characteristics of water. That is, the internal sound velocity of the acoustic medium at about 20 ° C is about 1
500 m / sec, acoustic impedance of about 1.5 × 10 ⁶
It is preferable to adjust it to be about kg / m ² · sec, and the attenuation rate for ultrasonic diagnosis differs depending on the diagnosis site, but from the viewpoint of increasing attenuation to reduce multiple echoes, it is about 0 to 0. Adjust to a range of 3.0 dB / cm · MHz, and for ultrasonic treatment, the attenuation rate is 0 to 1.5 dB / cm in order to reduce the loss of ultrasonic energy.
-The range of MHz is preferable. Therefore, in the acoustic medium of the present invention, the internal sound velocity at room temperature is 1300 to 160.
0 m / sec, acoustic impedance 1.0 to 1.7 × 10
⁶ kg / m ² · sec, attenuation rate 0 to 3.0 dB / cm · M
Those of Hz are preferred.

The above-mentioned acoustic characteristics depend on the acoustic characteristics of the rubber-like elastic material and the acoustic characteristics of the oily substance, and are particularly susceptible to the oily substance. Therefore, for ultrasonic diagnosis or ultrasonic therapy, it is preferable to use one or two or more oily substances that have similar acoustic characteristics to the living body. As a conventional oily substance, it usually has a slower sound speed than water, and since the attenuation of ultrasonic waves is relatively large,
In ultrasonic diagnosis, it has been difficult to obtain an acoustic medium that has a speed of sound close to that of water that can be applied to a site such as the eyeball, and the attenuation of ultrasonic waves is close to zero. As the oily component that dissolves the rubber-like elastic body, which is one of the features of the present invention, dibasic acid esters such as diethyl sebacate, dibutyl sebacate, and dioctyl adipate have little attenuation of ultrasonic pulses, and are rubbery. It is preferable because the elastic body has excellent solubility, the solution viscosity after dissolution is low, and the workability is good. In addition, it has a benzene ring in the molecule of ethyl cinnamate, ethyl phenylacetate, benzyl benzoate, benzyl butyl phthalate, etc.
An organic compound having a specific gravity of 0.95 or more is preferable because it has an internal sound velocity close to that of water and an acoustic impedance close to that of water.

In the present invention, the rubber-like elastic body and the oily substance contain an organic peroxide, and these are crosslinked and gelled to obtain an acoustic medium. Examples of the organic peroxide used include methyl ethyl ketone peroxide, cyclohexanone peroxide, cumene hydroperoxide, dicumyl peroxide, acetyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexano. And t-butyl peroxybenzoate, peracetic acid, a low molecular weight copolymer peroxide of a vinyl monomer and oxygen, etc., and 0.05 to 40 parts by weight with respect to 100 parts by weight of the rubber-like elastic material. Add in the range of parts by weight. Further, a crosslinking reaction accelerator such as cobalt naphthenate or tin octenoate can be added if necessary.

The above components are gelled to obtain the acoustic medium of the present invention. For gelation, it is usually necessary to perform a heating operation under oxygen exclusion (or in an inert gas atmosphere) from the viewpoint of crosslinking efficiency. preferable. In addition, since the acoustic medium of the present invention is cross-linked and gelled by the organic peroxide as in the above-mentioned constitution, the oily substance is not liberated unlike the conventional oily gel composition, and therefore, it can be easily handled. It does not pollute and cause discomfort.

However, if the above-mentioned acoustic medium of the present invention is left as it is for a long period of time on paper or a vinyl chloride sheet, the oily substance in the acoustic medium is transferred to the paper or vinyl chloride sheet to cause stains. Since the sheet may swell or be swollen, it is necessary to store the sheet in a predetermined case after use to prevent migration of the oily component. As a method for preventing the migration of the oily component, there is a method of coating the surface of the acoustic medium with an oil resistant plastic film such as polyamide or polyurethane.

Such an oil-resistant plastic film is immiscible with the oily components constituting the acoustic medium, and when the plastic film material is dissolved in a solvent to apply or coat it on the surface of the acoustic medium. It is necessary to use a solvent that does not mix with the oily component.
The solvent used in this case is preferably a mixed solvent of a lower alcohol and an organic solvent, and an especially preferable oil-resistant plastic is an alkoxymethylated polyamide.

When the surface of the acoustic medium is covered with the oil resistant plastic film, in order to prevent abnormal pulses and ghosts, air and the like should be completely prevented from entering between the acoustic medium surface and the plastic film. It is necessary to bring them into close contact, and as a preferable coating method, a method of immersing an acoustic medium in a solution of oil-resistant plastic and drying, or a method of applying the oil-resistant plastic solution to the acoustic medium once or plural times and drying, Examples of the method include spray coating and drying. The thickness of the oil-resistant plastic film thus formed is usually 1 in order not to impair the acoustic characteristics.
The thickness is from 0 to 300 μm, preferably from 20 to 150 μm.

Further, in the acoustic medium of the present invention, in order to adjust the attenuation rate of ultrasonic pulses, inorganic fillers such as calcium carbonate, kaolin, silica and titanium oxide, glass beads, polystyrene and polymethylmethacrylate are used. Fibers such as plastic beads, rayon, and polyester can also be appropriately mixed. Further, since a rubber-like elastic body and an oily substance are used in the present invention, heat deterioration, oxidative deterioration, light deterioration and the like are likely to occur, and it is preferable to add various antiaging agents for the purpose of preventing them. If necessary, various pigments, fragrances, viscosity imparting agents, and various oily rubbers as gel strength enhancers can be added.

Next, an example of a method for producing the acoustic medium of the present invention will be shown below.

First, the rubber-like elastic material is dissolved in an oily substance at room temperature or under heating, if necessary, in an inert gas atmosphere, and a predetermined amount of organic peroxide is added to the resulting solution at a temperature not higher than its decomposition temperature. After adding at temperature and mixing uniformly, degassing treatment is carried out so that air bubbles do not enter the solution. If degassing is insufficient and air bubbles remain inside, when molded into an acoustic medium,
Ultrasonic waves are scattered and absorbed in the bubble portion to be attenuated, resulting in an unclear image or abnormal pulses or ghosts, which is not preferable.

The degassed solution is poured into a mold having a predetermined shape or formed into a film, and the rubber-like elastic material is subjected to crosslinking treatment under an oxygen-blocking condition to gelate the solution. The conditions for the cross-linking treatment are the type of rubber-like elastic body and the type of organic peroxide used,
Although it depends on the amount, it is usually 1 to 36 at 60 to 250 ° C.
It is performed by arbitrarily selecting it within a heating condition of about 0 minutes. The thus-obtained acoustic medium of the present invention is cut as it is or cut into an arbitrary shape, and if necessary, the surface thereof is coated with the above-mentioned oil-resistant plastic film for use.

[0024]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 480 g of diethyl sebacate was mixed with butadiene rubber (styrene content 24%, Mooney viscosity [ML1 + 4, 100 ° C.]).
32) 120 g was finely chopped and blended, heated to 100 ° C. in a nitrogen gas atmosphere and stirred to be completely dissolved to obtain a viscous solution.

The obtained viscous solution was cooled to 40 ° C. or lower, 2 g of paste-like benzoyl peroxide (BPO content 50% by weight, dispersion medium: dioctyl phthalate) was added, and sufficiently stirred, This is a mold (10 cm x
(10 cm × 2 cm) and then degassed.

After the degassing process, under a nitrogen gas atmosphere, 12
The viscous solution in the mold was gelated by heating at 0 ° C. for 2 hours to obtain the acoustic medium of the present invention.

The obtained gel-like acoustic medium is flexible and elastic, and hardly absorbs water even when the gel is soaked in water for one day and night, and it is preserved even if left at 60 ° C. for 7 days. The shape was sufficiently maintained, and blooming of the oily substance was not observed.

Further, the acoustic medium of the present invention having the shape shown in FIG. 1 has very good adhesion to the living body surface, and the acoustic characteristics are such that the internal sound velocity is 1394 m / sec and the acoustic in-piece dance is 1.34.
× 10 ⁶ kg / m ² · sec, attenuation rate 0.21 dB / cm ·
Ultrasonic diagnosis of the thyroid gland was performed at MHz, and a clear image with few multiple reflections was obtained.

Example 2 500 g of liquid paraffin was mixed with isoprene rubber (cis 1,
4-bond 98%, Mooney viscosity [ML1 + 4, 100 ° C]
90) 60 g was finely chopped and blended, heated to 100 ° C. under a nitrogen gas atmosphere and stirred to completely dissolve, then 25 g of calcium carbonate was added and sufficiently stirred to obtain a viscous solution. ..

The resulting viscous solution was cooled to 40 ° C. or lower, 4 g of lauroyl peroxide in paste form (content and dispersion medium were the same as in Example 1) was added, and the mixture was sufficiently stirred and then the Example. An acoustic medium of the present invention was obtained by using the same mold as in 1.

The obtained acoustic medium also has substantially the same physical properties as in Example 1, and when it is used as an acoustic coupler, it has very good adhesion to the living body surface, and the acoustic characteristics are that the internal sound velocity is 1396 m.
/ Sec, acoustic in-piece dance 1.12 × 10 ⁶ kg /
It had m ² · sec and an attenuation rate of 1.1 dB / cm · MHz, and when used for ultrasonic diagnosis, a clear image was obtained.

Example 3 To a mixed solution of 250 g of ethyl cinnamate and 250 g of ethyl phenylacetate, 100 g of styrene-butadiene rubber (the same as in Example 1) was finely chopped and blended, and the mixture was heated to 100 ° C. under a nitrogen gas atmosphere and stirred. It was completely dissolved to obtain a viscous solution.

The viscous solution obtained was cooled to 40 ° C. or lower, and pasty benzoyl peroxide (Example 1
(Same as the above), and after thoroughly stirring the mixture, cast it in a mold (10 cm x 10 cm x 0.5 cm) for degassing, and then coat the solution surface with a polyester film and air. After shutting off, the same gelling treatment as in Example 1 was performed to obtain the acoustic medium of the present invention.

The obtained gel composition also has substantially the same physical properties as in Example 1, and when used as an acoustic coupler, it has very good adhesion to the surface of the living body and the acoustic characteristics are that the internal sound velocity is 1476.
m / sec, acoustic in-piece dance 1.45 × 10 ⁶ kg
/ M ² · sec, attenuation rate 0.24B / cm · MHz,
When used for ultrasonic diagnosis, clear images were obtained.

Example 4 The acoustic medium obtained in Example 1 was dipped in an alkoxymethylated polyamide solution (solid content concentration 20% by weight, methanol / toluene mixed solvent = 50/20% by weight), immediately taken out and air dried. Then, an acoustic medium having a 30 μm thick oil-resistant plastic film layer on its surface was obtained.

The acoustic characteristics of this acoustic medium were almost the same as those of Example 1, and even after leaving them on paper or vinyl chloride sheet at 40 ° C. for 7 days, no migration of the oily component was confirmed.

Example 5 The acoustic medium obtained in Example 2 was used as a polyurethane resin solution (concentration of solid content 20% by weight, toluene / ethyl acetate mixed solvent =
(50/20% by weight), immediately taken out and air dried to obtain an acoustic medium having a 50 μm thick oil-resistant plastic film layer on the surface.

The acoustic characteristics of this acoustic medium were almost the same as those of Example 2, and the recording medium was allowed to stand on paper or vinyl chloride sheet at 40 ° C. for 7 days, but no migration of oily components was confirmed.

[0040]

EFFECT OF THE INVENTION Since the acoustic medium of the present invention has the above-mentioned constitution, it is excellent in shape-retaining property, flexibility and moderate elasticity, and the oily substance contained therein does not bloom over time. .. Further, since this medium absorbs almost no moisture, it is not affected by moisture in the atmosphere, does not need to be specially sealed and has stable quality. Further, since it has acoustic characteristics close to those of a living body, it also exhibits excellent effects when used as an acoustic medium for ultrasonic diagnosis or ultrasonic treatment.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a molded body of an acoustic medium of the present invention.

[Explanation of symbols]

 1 Acoustic medium

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuo Horiuchi 1-2-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Inventor Yuichi Inoue 1-2-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Inventor Mitsuru Konno 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (5)

[Claims] 1. An acoustic medium obtained by crosslinking and molding a composition containing a rubber-like elastic material having a double bond in the molecule, an oily component that dissolves the rubber-like elastic material, and an organic peroxide. 2. The internal sound velocity at room temperature is 1300 to 160.
0 m / sec, acoustic impedance 1.0 to 1.7 × 10
⁶ kg / m ² · sec, attenuation rate 0 to 3.0 dB / cm · M
The acoustic medium according to claim 1, which has a frequency of Hz. 3. The oily component is a dibasic acid ester, or has a benzene ring in the molecule and has a specific gravity of 0.95 at 25 ° C.
The acoustic medium according to claim 1, containing any of the above organic compounds. 4. The acoustic medium according to claim 1, containing at least one selected from an inorganic filler, a plastic bead, a fiber and the like as an attenuation adjusting agent. 5. The acoustic medium according to claim 1, wherein the surface is covered with an oil resistant plastic film.