Composition for acoustic wave probe, and acoustic wave probe

Abstract

To provide a composition for an acoustic wave probe which has a low attenuation rate even in a low frequency region of an acoustic wave and is excellent in mechanical strength, and an acoustic wave probe using the same.SOLUTION: A composition for an acoustic wave probe, in which constituent materials of the composition for an acoustic wave probe include resins and silica particles, the resins are addition reaction type silicone resins, the silica particles include large-diameter silica particles and small-diameter silica particles, the large-diameter silica particles have a mean primary-particle size of 0.1 μm or more and 10 μm or less, and the small-diameter silica particles have a mean primary-particle size of 10nm or more and 25nm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composition for an acoustic wave probe and an acoustic wave probe using the same. [Background technology]

[0002] An acoustic wave measurement device, which is an example of a non-destructive testing device, is equipped with an acoustic wave probe that irradiates an acoustic wave toward an object to be measured, receives reflected waves (echoes) reflected according to the structure of the object to be tested, and outputs a measurement signal. The measurement signal converted from the reflected waves received by such an acoustic wave probe is output as, for example, an image. This allows the internal structure of the object to be observed non-destructively.

[0003] The acoustic wave to be irradiated during measurement may be, for example, an ultrasonic wave or a photoacoustic wave, and an appropriate wavelength range is selected depending on the constituent material of the object to be measured, the measurement conditions, and the like. For example, an ultrasound diagnostic device that uses ultrasound (generally with a frequency of 20 kHz or higher), which is an example of acoustic waves, irradiates ultrasound toward the inside of a subject to be measured, receives the ultrasound reflected by tissue inside the subject, and outputs an image of the ultrasound.

[0004] In such an ultrasound diagnostic device, ultrasonic waves are transmitted and received via an acoustic wave probe. A typical acoustic wave probe is provided with a piezoelectric element that performs electroacoustic conversion. An acoustic matching layer and an acoustic lens are provided in this order on the ultrasonic wave transmitting / receiving surface side (measurement object side) of the piezoelectric element. Meanwhile, a backing material is provided on the back side (power supply side), which is the opposite side from the measurement object side. An adhesive layer may also be provided between each component.

[0005] Among the components of such acoustic wave probes, the acoustic lens functions to increase the resolution of the region of interest in the same way as it focuses the ultrasonic waves emitted from the piezoelectric element. The characteristics required of such an acoustic lens include low attenuation of ultrasonic waves during transmission, low reflectance of ultrasonic waves from the emitting surface, and excellent mechanical strength and wear resistance.

[0006] Materials that satisfy the required characteristics of such an acoustic lens have so far been based on the acoustic impedance of the living body (1.4 × 10 6 ~1.7×10 6 kg / m 2 Silicone resin, which has a low ultrasonic attenuation rate close to 1 / s, has been mainly used. However, acoustic lenses made only from silicone resin are particularly poor in strength and abrasion resistance, so it has been common to improve these properties by adding fillers such as metals and oxides.

[0007] However, there are concerns that adding fillers can attenuate sound vibrations and degrade the acoustic properties of the acoustic lens, so in recent years, the particle size and composition of the fillers to be added have been investigated.

[0008] For example, Patent Document 1 proposes a technology that uses nanoparticle-sized silica to improve the hardness and mechanical strength of the resulting silicone resin while maintaining a low amount of attenuation of acoustic vibrations. Also, Patent Document 2 proposes a technology that uses zinc oxide or ytterbium oxide, which have a higher density than silica, as a constituent material of the filler to reduce the attenuation rate of the acoustic lens and bring the acoustic impedance closer to that of a living body. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2016-046811 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-125071 Summary of the Invention [Problem to be solved by the invention]

[0010] However, the above-mentioned techniques have not been able to adequately meet the recent demand for further improvement in acoustic properties. In particular, there is a demand for compositions for acoustic wave probes that have a low acoustic wave attenuation rate even in the low frequency range of acoustic waves (e.g., 10 MHz or less), and for acoustic wave probes using such compositions. There is also a demand for further improvement in mechanical strength.

[0011] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a composition for an acoustic wave probe that has a low attenuation rate even in the low frequency range of acoustic waves and excellent mechanical strength, and an acoustic wave probe using the same. [Means for solving the problem]

[0012] In order to solve the above problems, the composition for an acoustic wave probe and the acoustic wave probe according to one embodiment of the present invention propose the following means. (1) A first aspect of the present invention provides a composition for an acoustic wave probe, comprising a resin and silica particles, the resin being an addition reaction type silicone resin, the silica particles being composed of large-sized silica particles and small-sized silica particles, the large-sized silica particles having an average primary particle diameter of 0.1 μm or more and 10 μm or less, and the small-sized silica particles having an average primary particle diameter of 10 nm or more and 25 nm or less.

[0013] (2) Aspect 2 of the present invention is the composition for an acoustic wave probe of Aspect 1, wherein the large-diameter silica particles are contained in an amount of 20 parts by mass or more and 40 parts by mass or less, and the small-diameter silica particles are contained in an amount of 20 parts by mass or more and 40 parts by mass or less, when the resin is taken as 100 parts by mass.

[0014] (3) A third aspect of the present invention is a composition for an acoustic wave probe according to the first or second aspect, wherein the attenuation rate for a sound wave having a frequency of 7.5 MHz is less than 2.8 dB / cm.

[0015] (4) A fourth aspect of the present invention relates to a composition for an acoustic wave probe according to any one of the first to third aspects, wherein the hardness measured using a Type A durometer in accordance with JIS K6253-3:2012 is in the range of 30 or more and 60 or less.

[0016] (5) A fifth aspect of the present invention is the acoustic wave probe composition of any one of the first to fourth aspects, further comprising 3 parts by mass or less of a colorant per 100 parts by mass of the resin. (6) An acoustic wave probe according to a sixth aspect of the present invention is formed using the composition for an acoustic wave probe according to any one of the first to fifth aspects. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a composition for an acoustic wave probe that has a low attenuation rate even in the low frequency range of acoustic waves and has excellent mechanical strength and abrasion resistance, and an acoustic wave probe using the same. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram illustrating the configuration of an acoustic wave probe according to an embodiment of the present invention. [Figure 2] FIG. 1 is an explanatory diagram for explaining an evaluation method of an acoustic lens in an example. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an acoustic wave probe composition and an acoustic wave probe according to one embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is specifically described to provide a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified. Furthermore, the drawings used in the following description may show essential parts enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as those in reality.

[0020] [Composition for acoustic wave probe] The acoustic wave probe composition according to one embodiment of the present invention is a constituent material for each component of an acoustic wave probe described below, and is particularly suitable as a constituent material for an acoustic lens that constitutes an acoustic wave probe. In the following description, an example is given in which the acoustic wave probe composition is used as a constituent material for an acoustic lens. The composition for an acoustic wave probe according to this embodiment contains at least a resin and silica particles.

[0021] (resin) The resin may be an addition reaction type silicone resin that undergoes polymerization by an addition reaction. The silicone resin is not particularly limited, but examples thereof include dimethyl silicone, methyl phenyl silicone, phenyl silicone, modified silicone, etc. Among these, dimethyl silicone and methyl phenyl silicone are preferred.

[0022] Of these silicone resins, the resin of this embodiment is preferably a cured product of an addition reaction type liquid silicone resin. Here, addition reaction type liquid silicone resins are classified into one-component type and two-component mixed type, and when the addition reaction type liquid silicone resin is a two-component mixed type, the cured product refers to the entire product obtained by curing the mixture of the two components. By using such an addition reaction type silicone resin, it is possible to suppress the generation of outgassing during curing.

[0023] In the following description, when simply referred to as "silicone resin," it refers to the cured product as described above, i.e., the silicone resin after polymerization, and when referred to as "liquid silicone resin," it refers to a silicone resin oligomer that is an uncured (unpolymerized) silicone resin as a raw material, such as the addition reaction type liquid silicone resin described above. In other words, the "liquid silicone resin" in this embodiment is a precursor of the silicone resin as a cured product.

[0024] (silica particles) Silica particles act as a filler. Fillers are components added to improve the strength and abrasion resistance of acoustic lenses and to adjust the density of the acoustic lens. However, adding fillers causes particle interfaces, which are the source of diffuse reflection of sound waves, to be included within the acoustic lens. Therefore, even though it is necessary to add fillers for the purposes of improving strength and adjusting density, there is a problem in that the transmitted sound waves are reflected at the particle interfaces where the sound vibrations are attenuated, resulting in a deterioration of acoustic characteristics.

[0025] As a result of further research to solve the above problems, the inventors discovered that even when the acoustic lens contains particle interfaces inside it, by adding a filler, it is possible to suppress the reflection of sound waves at the particle interfaces and the attenuation of sound vibrations in the low frequency band, for example, below 10 MHz, by using multiple types of silica particles with different average primary particle sizes.

[0026] Based on the above findings, in this embodiment, the silica particles are composed of large-diameter silica particles and small-diameter silica particles. Among these, the large-sized silica particles are those having an average primary particle diameter of 0.1 μm to 10 μm, preferably 0.5 μm to 5 μm, and the small-sized silica particles are those having an average primary particle diameter of 10 nm to 25 nm, preferably 11 nm to 22 nm, more preferably 12 nm to 18 nm.

[0027] The average primary particle diameter of the large-diameter silica particles is determined based on the value described in the product catalog, safety data sheet, or the like. If the value cannot be obtained from the catalog, a value measured by a known method may be used. For example, the particle diameter at a cumulative percentage of 50% (D50) in the cumulative particle size distribution of the silica particles obtained by measurement using a laser diffraction particle size distribution analyzer may be used.

[0028] The average primary particle diameter of the small-diameter silica particles is determined based on the value described in the product catalog, safety data sheet, or the like. If the value cannot be obtained from the catalog, a value measured by a known method may be used. For example, the particle diameter of the primary particles may be measured by image analysis of a TEM photograph obtained by an electron microscope, and the average particle diameter of the obtained primary particles may be used.

[0029] The large-diameter silica particles and the small-diameter silica particles having the above-mentioned range of average primary particle diameter are easy to handle, for example, they are easy to mix with liquid silicone resin in the manufacturing process, and the viscosity of the silicone resin composition obtained by them is also relatively easy to adjust.Since the silicone resin composition adjusted to a suitable viscosity is easy to defoam, by using this silicone resin composition, it is possible to obtain a cured product with few voids, such as an acoustic lens.

[0030] The amounts of the large-diameter silica particles and the small-diameter silica particles may be such that, when the silicone resin (resin) is taken as 100 parts by mass, the large-diameter silica particles are contained in an amount of 20 parts by mass to 40 parts by mass, preferably 25 parts by mass to 35 parts by mass, and the small-diameter silica particles are contained in an amount of 20 parts by mass to 40 parts by mass, preferably 25 parts by mass to 35 parts by mass.

[0031] The fine silica particles, such as small-diameter silica particles, whose average primary particle diameter is nano-order, have low particle bulk density, so when they are added to liquid silicone resin, it takes time and effort to mix them.In addition, because these particles have a large specific surface area, when they are added to liquid silicone resin, they will extremely deteriorate the fluidity of liquid silicone resin, and cause the viscosity of silicone resin composition to increase significantly.Therefore, if the silica particles are too fine, they need to be reduced in amount as filler in order to achieve a viscosity that can be mixed with liquid silicone resin.

[0032] However, even if the amount of silica particles is adjusted to a level that allows mixing with a liquid silicone resin, the cured product obtained from such a silicone resin composition may have insufficient defoaming (poor defoaming), which may lead to deterioration of acoustic properties.

[0033] Usually, when a powdered filler is blended into a liquid silicone resin, air may be mixed in with the filler. Although such air is generally removed in the mixing process or degassing process, if the viscosity of the silicone resin composition is high, air may remain in the silicone resin composition. If the liquid silicone resin is cured in this state, there is a risk of numerous voids being formed in the cured product. The voids formed in this way become the source of sound wave reflection within the cured acoustic lens, attenuating sound vibrations and causing deterioration of acoustic properties. Therefore, in order to obtain an acoustic lens with excellent acoustic properties, it was necessary to further reduce the amount of silica particles blended so as to prevent voids from forming within the acoustic lens.

[0034] Furthermore, sound waves propagate within an acoustic lens by vibrating the silicone resin, but when a filler is added, the vibration of the silicone resin is suppressed by contact with the filler particles. This effect becomes more pronounced the greater the contact surface area between the particles and the silicone resin, resulting in attenuation of sound vibrations. Because small-diameter silica particles have a larger specific surface area than large-diameter silica particles, even with the same blending amount, they tend to attenuate sound vibrations more, degrading acoustic properties. Therefore, to obtain an acoustic lens with excellent acoustic properties, it was necessary to limit the blending amount of silica particles so as to minimize interference with the vibration of the silicone resin.

[0035] As described above, when using fine silica particles, the amount of silica particles to be blended must be reduced from the viewpoints of ease of manufacturing and maintaining and improving acoustic properties, making it difficult to design a composition with a high degree of freedom as a filler.

[0036] In this embodiment, by combining large silica particles having an average primary particle diameter of 0.1 μm or more and 10 μm or less with small silica particles having an average primary particle diameter of 10 nm or more and 25 nm or less, it becomes possible to design the composition with a high degree of freedom in terms of improving strength and abrasion resistance, adjusting density, etc., while maintaining good acoustic properties.

[0037] The shape of the silica particles is not particularly limited, but spherical shapes are preferred in that they have less of an effect on viscosity increase when the liquid silicone resin and the silica particles are mixed, making the mixing process easier and preventing poor degassing.

[0038] (Other ingredients) Furthermore, the acoustic lens may further contain components other than those described above, as necessary, such as a colorant, a crosslinking agent, a platinum catalyst, a curing accelerator, a curing retarder, a solvent, a dispersant, an antistatic agent, an antioxidant, a flame retardant, and a thermal conductivity improver.

[0039] Among these, colorants are components that are blended for the purpose of identification and confirmation of cleanliness. Examples of such colorants include pigments and dyes such as carbon and titanium oxide. These components may be used alone or in combination of two or more. The content of the colorant is not particularly limited, but is preferably 3 parts by mass or less, and preferably 2.5 parts by mass or less, per 100 parts by mass of the silicone resin.

[0040] (hardness) The acoustic wave probe composition of this embodiment has a hardness (A hardness) measured using a Type A durometer in accordance with JIS K6253-3:2012 in the range of 30 to 60, preferably 40 to 50. When the A hardness is within the above range, when the acoustic wave probe composition is used as a constituent material of an acoustic lens, an acoustic lens having good shape retention properties, acoustic properties, and abrasion resistance can be obtained.

[0041] (density) The composition for an acoustic wave probe of this embodiment has a density measured by an underwater displacement method of 1.0 to 1.4 g / cm 3or less, preferably 1.1 to 1.4 g / cm 3 or less, more preferably 1.2 to 1.4 g / cm 3 If the density is within the above-mentioned range, the excellent acoustic properties required when the acoustic wave probe composition is used as a constituent material of an acoustic lens are satisfied, and a good acoustic lens can be obtained.

[0042] (tensile strength) The tensile strength of the acoustic wave probe composition of this embodiment is such that the minimum value when the tensile strength is measured n times (for example, n = 3) is 2.0 MPa or more. By setting the minimum value to 2.0 MPa or more, when the acoustic probe composition is used as a constituent material of an acoustic lens, an acoustic lens with high mechanical strength and excellent abrasion resistance can be obtained. Furthermore, a high-quality product can be obtained by ensuring that the variation in each measurement value is within ±20% of the average value of the n measurements.

[0043] (acoustic characteristics) The acoustic properties of an acoustic lens can be evaluated, for example, by the attenuation rate of acoustic vibrations. The attenuation rate of the composition for an acoustic wave probe of this embodiment for sound waves with a frequency of 7.5 MHz is less than 2.8 dB / cm. With such an attenuation rate, when the composition for an acoustic wave probe is used as a constituent material of an acoustic lens, the amount of attenuation of sound vibrations propagating within the acoustic lens can be kept small, and the acoustic lens will exhibit excellent acoustic properties.

[0044] [Method of manufacturing a composition for an acoustic wave probe] An example of a method for producing the composition for an acoustic wave probe of this embodiment will be described. Note that the method for producing the composition for an acoustic wave probe of this embodiment is not limited to the procedure described below, and the composition can be produced by any process.

[0045] (Step of obtaining composition material for acoustic wave probe (before curing)) First, a two-component liquid silicone resin, large-diameter silica particles, small-diameter silica particles, and other components (colorant, crosslinker, platinum catalyst, curing accelerator, curing retarder, solvent, dispersant, antistatic agent, antioxidant, flame retardant, thermal conductivity improver, etc.) as needed are prepared and weighed out in appropriate amounts to achieve a predetermined blending ratio. The weighing can be performed by a known method, and the blending ratio of each component may be in accordance with the content of the resin composition for an acoustic wave probe described above.

[0046] Next, the weighed components are mixed to prepare an acoustic wave probe composition material. The large-diameter silica particles and small-diameter silica particles having the average primary particle diameter ranges described above are easy to handle, and are easy to mix with a liquid silicone resin during the manufacturing process, and the viscosity of the acoustic wave probe composition obtained is also relatively easy to adjust. Acoustic wave probe compositions adjusted to a suitable viscosity are easily defoamed, so by using such an acoustic wave probe composition material, an acoustic wave probe composition, such as an acoustic lens, with fewer voids such as air bubbles can be formed.

[0047] The mixing method in the above-mentioned step is not particularly limited and can be performed by a known method, such as stirring and mixing with a rotor, mixing with a planetary stirring mixer, mixing with a homogenizer, etc.

[0048] Such mixing is preferably carried out under reduced pressure. By continuing mixing under reduced pressure and degassing, bubble entrapment is suppressed, the added filler is uniformly dispersed and maintained, and a composition for an acoustic wave probe can be suitably obtained. Note that the reduced pressure during the degassing may be any degree of vacuum that can be achieved by a general vacuum degassing machine.

[0049] (Step of curing the composition material for the acoustic wave probe) Next, the acoustic wave probe composition material formed as described above is molded into a predetermined shape and then cured (polymerized) by an addition reaction of the liquid silicone resin. The cured product, such as an acoustic wave probe composition, obtained in this manner, such as an acoustic lens, is almost free of bubbles (voids) and exhibits excellent acoustic properties.

[0050] The method for molding and curing the acoustic wave probe composition material is not particularly limited and can be performed by a known method. For example, it is preferable to produce the acoustic wave probe composition material by casting it into a mold of any shape and then heating it to initiate addition polymerization and curing it. The heating temperature and curing time at this time may be appropriately set depending on the curing temperature of the silicone resin used.

[0051] (Optional processing steps) In addition to the steps listed in the above-described manufacturing method, other steps may be included as necessary. As long as the acoustic properties are not affected, various treatment steps may be performed to improve chemical resistance, water resistance, abrasion resistance, adhesiveness, etc.

[0052] When the acoustic wave probe composition is cut out and molded into a desired shape, it is preferable to mold it by casting it into a mold that has been prepared in advance to match the shape and size of the desired molded product.

[0053] [Acoustic wave probe] The acoustic wave probe composition of the above-described embodiment can be suitably used as a constituent material of an acoustic wave probe, for example, as an acoustic lens. FIG. 1 is a schematic diagram showing the configuration of an acoustic wave probe according to one embodiment of the present invention. The acoustic wave probe 10 has, in order from the ultrasonic wave transmitting / receiving surface side (measurement target side), an acoustic lens 1, an acoustic matching layer 2, a piezoelectric element 3, and a backing material 4, and further has a housing 5 that houses these.

[0054] By forming the acoustic lens 1 using the acoustic wave probe composition of the above-described embodiment, the acoustic wave probe 10 has high ultrasonic wave propagation efficiency, thereby enabling ultrasonic diagnosis with clear images.

[0055] Although one embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Example]

[0056] As examples, compositions for acoustic wave probes according to the present invention and comparative examples were prepared and the physical properties of the cured products were examined. (Example 1 of the present invention) The silicone resin used was 50 parts by mass of a two-component silicone resin mixture, Liquid A (KE-1031-A, manufactured by Shin-Etsu Chemical Co., Ltd.) and 50 parts by mass of Liquid B (KE-1031-B, manufactured by Shin-Etsu Chemical Co., Ltd.). The fillers used were 25 parts by mass of a large-diameter filler (SC2500-SQ, manufactured by Admatechs Co., Ltd., spherical silica (average primary particle diameter 0.5 μm)) and 25 parts by mass of a small-diameter filler (AEROSIL® R8200, manufactured by Nippon Aerosil Co., Ltd., fumed silica (average primary particle diameter 12 nm)). Furthermore, 0.16 parts by mass of acetylene black (Li-400, manufactured by Denka Co., Ltd.) and 2 parts by mass of titanium dioxide (AEROSIL® TiO2NKT90, manufactured by Nippon Aerosil Co., Ltd.) were used as colorants.

[0057] (Example 2 of the present invention) The procedure was the same as in Inventive Example 1, except that 25 parts by mass of a large-diameter filler (SC6500-SQ: manufactured by Admatechs Co., Ltd., spherical silica (average primary particle diameter 1.9 μm)) was used instead of the large-diameter filler in Inventive Example 1.

[0058] (Example 3 of the present invention) This example is the same as Inventive Example 1 except that the coloring agents (acetylene black and titanium dioxide) were omitted from Inventive Example 1.

[0059] (Example 4 of the present invention) This example was the same as Inventive Example 1, except that 25 parts by mass of silica having an average primary particle diameter of 20 nm (AEROSIL (registered trademark) NX 90 S: manufactured by Nippon Aerosil Co., Ltd., fumed silica (average primary particle diameter 20 nm)) was used instead of the small diameter filler of Inventive Example 1.

[0060] (Example 5 of the present invention) This example was the same as Inventive Example 1, except that 25 parts by mass of silica having an average primary particle diameter of 16 nm (AEROSIL (registered trademark) NX 130: manufactured by Nippon Aerosil Co., Ltd., fumed silica (average primary particle diameter 16 nm)) was used instead of the small diameter filler of Inventive Example 1.

[0061] (Example 6 of the present invention) This example is the same as Example 1 of the present invention, except that 25 parts by mass of silica (3SQ-3C: manufactured by Admatechs Co., Ltd., spherical silica (average primary particle diameter 0.3 μm)) having an average primary particle diameter of 0.3 μm was used instead of the large diameter filler in Example 1 of the present invention.

[0062] (Comparative Example 1) This example is the same as Inventive Example 1, except that 25 parts by mass of silica having an average primary particle diameter of more than 25 nm (AEROSIL (registered trademark) RX 50: manufactured by Nippon Aerosil Co., Ltd., fumed silica (average primary particle diameter 40 nm)) was used instead of the small diameter filler of Inventive Example 1.

[0063] (Comparative Example 2) This example was the same as Inventive Example 1, except that the small-diameter filler of Inventive Example 1 was replaced with 25 parts by mass of silica having an average primary particle diameter of less than 10 μm (AEROSIL (registered trademark) 300: manufactured by Nippon Aerosil Co., Ltd., fumed silica (average primary particle diameter 7 nm)).

[0064] (Comparative Example 3) This example was the same as Inventive Example 1 except that the small diameter filler was omitted from Inventive Example 1 and only 50 parts by mass of the large diameter filler was used.

[0065] Comparative Example 4 This example was the same as Inventive Example 1 except that the large diameter filler was omitted from Inventive Example 1 and only 50 parts by mass of small diameter filler was used.

[0066] (Comparative Example 5) This example was the same as Inventive Example 1, except that instead of the small-diameter filler in Inventive Example 1, 25 parts by mass of spherical silica having an average primary particle diameter of more than 25 nm (AEROSIL (registered trademark) NAX 50: manufactured by Nippon Aerosil Co., Ltd., fumed silica (average primary particle diameter 30 nm)) was used.

[0067] The following items were inspected and measured using the samples of Examples 1 to 6 of the present invention and Comparative Examples 1 to 5 described above. (a) Appearance inspection: The composition for an acoustic wave probe was visually inspected, and when no aggregates were observed, it was marked with "O"; when aggregates were observed, it was marked with "X." (b) Density: A 2 mm thick composition for an acoustic wave probe was cut into a size of 40 mm × 40 mm, and the density (g / cm) was measured by the water displacement method. 3 ) was sought. (c) Hardness: The hardness (A hardness) of the composition for an acoustic wave probe was measured using a type A durometer in accordance with JIS K6253-3:2012. (d) Attenuation rate: Acoustic wave probe compositions with a thickness of 1 mm (t1) and 3 mm (t2) were prepared as measurement samples 1a and 1b, respectively. As shown in Fig. 2, measurement samples 1a and 1b were sandwiched between probe 20 and probe 30, and ultrasonic waves with a transmission frequency of 7.5 MHz were emitted from probe 20. The intensities I1 and I2 of the transmitted waves received by probe 30 were determined, and the attenuation rate (dB / cm) was calculated based on the following formula (1). Decay rate = 20 log (I1 / I2) / (t2-t1) (1) The measurements were carried out by applying ultrasonic gel between the probe 20 and the measurement sample and between the probe 30 and the measurement sample to prevent air from getting in. (e) Tensile strength: Tensile strength (MPa) was measured using a precision universal testing machine (Shimadzu Corporation, AGS-X) tensile testing machine in accordance with JIS K6254. Measurements were performed three times for each sample, and the average value was taken as the tensile strength. In addition, the tensile strength was judged as follows: if the three measurements were within ±20% of the average value, it was marked as ◯ (no variation); if even one measurement was outside ±20% of the average value, it was marked as × (variation present); and if the measurement value was less than 2.0 MPa, it was marked as ×, indicating insufficient strength.

[0068] The composition of each sample, as well as the test and measurement results, are summarized in Table 1. [Table 1]

[0069] According to the results shown in Table 1, the compositions for acoustic wave probes of Examples 1 to 6 of the present invention, which combined large-diameter fillers and small-diameter fillers, had no problems with appearance or density, and the A hardness was in the range of 39 to 55 and the attenuation rate was in the range of 2.56 to 2.77 (dB / cm), which were all within a good range. In addition, the tensile strength was also 2.0 MPa or more, with no variation, and was a good result.

[0070] On the other hand, in Comparative Example 1, which used silica particles with an average primary particle size of 40 nm, exceeding 25 nm, the attenuation rate was 2.89 (dB / cm), which was larger than any of the Examples of the present invention, and the tensile strength was 1.28, which was smaller than any of the Examples of the present invention. Furthermore, in Comparative Example 2, in which silica particles having an average primary particle size of less than 10 μm were used, mixing was not possible and a composition for an acoustic wave probe could not be obtained. In addition, Comparative Example 3, which contained only large diameter fillers, had a hardness of 33, which was smaller than any of the invention examples, and an extremely large damping factor of 3.24. Furthermore, the tensile strength was 1.09, which was smaller than any of the invention examples, and the variation was also large. Furthermore, Comparative Example 4, which contained only small diameter fillers, had an attenuation rate of 2.84 (dB / cm), which was greater than any of the invention examples, and the tensile strength also had a large variation. Furthermore, in Comparative Example 5, which used silica particles with an average primary particle size of 30 nm, which is greater than 25 nm, the tensile strength was 1.93, which was smaller than any of the Examples of the present invention.

[0071] From the results of the above examples, it was confirmed that by combining large-diameter fillers having an average primary particle diameter of 0.1 μm or more and 10 μm or less with small-diameter fillers having an average primary particle diameter of 10 nm or more and 25 nm or less, it is possible to obtain a composition for acoustic wave probes that has good moldability, high Type A durometer hardness, low attenuation rate, and excellent tensile strength, and an acoustic wave probe using the same. [Industrial Applicability]

[0072] The acoustic wave probe composition of the present invention and the acoustic wave probe using the same can realize, for example, an ultrasonic diagnostic device equipped with an ultrasonic probe that has excellent ultrasonic propagation characteristics, high mechanical strength, and high abrasion resistance, and therefore has industrial applicability. [Explanation of symbols]

[0073] 1...Acoustic lens 1a...Measurement sample 2…Acoustic matching layer 3...Piezoelectric element 4...Backing material 5. Housing 10...Acoustic wave probe 20…Probe

Claims

1. Contains a resin and silica particles, the resin is an addition reaction type silicone resin, The silica particles are composed of large-diameter silica particles and small-diameter silica particles, The composition for an acoustic wave probe, wherein the large-diameter silica particles have an average primary particle diameter of 0.1 μm or more and 10 μm or less, and the small-diameter silica particles have an average primary particle diameter of 10 nm or more and 25 nm or less.

2. 2. The composition for acoustic wave probes according to claim 1, wherein the large-diameter silica particles are contained in an amount of 20 parts by mass or more and 40 parts by mass or less, and the small-diameter silica particles are contained in an amount of 20 parts by mass or more and 40 parts by mass or less, when the resin is taken as 100 parts by mass.

3. 3. The composition for an acoustic wave probe according to claim 1, wherein the composition has an attenuation rate of less than 2.8 dB / cm for a sound wave having a frequency of 7.5 MHz.

4. The composition for an acoustic wave probe according to claim 1 or 2, wherein the hardness measured using a type A durometer in accordance with JIS K6253-3:2012 is in the range of 30 or more and 60 or less.

5. The composition for an acoustic wave probe according to claim 1 or 2, further comprising 3 parts by mass or less of a colorant when the resin is taken as 100 parts by mass.

6. An acoustic wave probe, which is formed using the composition for an acoustic wave probe according to claim 1 or 2.

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