Acoustic components, ultrasonic transducers, ultrasonic probes, and ultrasonic diagnostic equipment

Abstract

To provide a resin composition capable of evenly dispersing particles and improving resistance to short circuit, cutting workability and production efficiency of a cured material, and an ultrasonic transducer including the cured material of the resin composition, an acoustic member, an ultrasonic probe and an ultrasonic diagnostic apparatus.SOLUTION: A resin composition used for manufacture of an acoustic member used for an ultrasonic probe, comprises a thermosetting resin, and two or more types of particles dispersed in the thermosetting resin. The two or more types of particles include heavy particles other than metallic particles, having larger density than that of the thermosetting resin, and light particles having smaller density than that of the thermosetting resin. A total of contents of the heavy particles and light particles to the total volume of the cured materials of the resin composition is 10 volume% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin composition, an acoustic component, an ultrasonic transducer, an ultrasonic probe, and an ultrasonic diagnostic apparatus. [Background technology]

[0002] Ultrasound probes, which are connected to or configured to communicate with ultrasound diagnostic equipment, are used to obtain diagnostic images of the shape and movement of biological tissues through a simple operation of applying them to the body surface or inserting them into the body.

[0003] An ultrasonic transducer comprises a piezoelectric material that transmits and receives ultrasonic waves, an acoustic lens that is in close contact with the body, an acoustic matching layer placed between them, and a backing material placed on the side of the piezoelectric material opposite to the body. The acoustic matching layer is a component that changes the acoustic impedance difference between the piezoelectric material and the acoustic lens so that the ultrasonic waves are reduced. The acoustic matching layer makes it less likely for the ultrasonic waves to be reflected between the piezoelectric material and the body, thereby improving the accuracy of the diagnostic image. The backing material is a component that attenuates the ultrasonic waves transmitted from the piezoelectric material on the side opposite to the body. Various materials are known to be used as such acoustic matching layers and backing materials.

[0004] For example, Patent Document 1 discloses an acoustic matching layer formed by providing a pair of limiting materials of a constant height on a piezoelectric plate, applying molten resin of the same material as the limiting materials, and pressing the molten resin from above. According to Patent Document 1, by providing limiting materials and pressing molten resin of the same material onto them, the thickness of the acoustic matching layer is uniform and has little variation, resulting in excellent cost-effectiveness and improved transmit / receive characteristics of the ultrasonic probe.

[0005] Furthermore, Patent Document 2 describes the resonant frequency f of a piezoelectric vibrator. r and anti-resonance frequency f aAn acoustic matching layer is disclosed in which a plate-like body with a thickness set to λ / 4 of the frequency between (where λ is the wavelength corresponding to that frequency) is attached to a piezoelectric transducer, and a solid resin layer formed on the radiating surface side by applying and solidifying a liquid resin is also disclosed. Patent Document 2 states that by making the acoustic matching layer a multilayer structure and polishing the solid resin layer in such a way as to correct the bandwidth characteristics caused by the plate-like body which is the first layer, the bandwidth characteristics can be improved and the productivity of the ultrasonic transducer can be improved.

[0006] Furthermore, it is known that the acoustic impedance of acoustic matching layers and backing materials can be adjusted by mixing particles into resin materials such as epoxy resin.

[0007] For example, Patent Document 3 discloses an ultrasonic transducer device having an acoustic damping material containing 25-45% by weight of tungsten particles, 15-35% by weight of silicone particles, and 40-60% by weight of epoxy. Patent Document 3 states that by including tungsten particles and silicone particles in the acoustic damping material, it was possible to reduce acoustic impedance while maintaining the degree of acoustic damping.

[0008] Furthermore, Patent Document 4 discloses a matching layer comprising a composite material containing a matrix material into which a plurality of first heavy particles and a plurality of second light particles are incorporated, wherein the plurality of first heavy particles and the plurality of second light particles have a density between approximately 100% and approximately 200% of the desired composite density of the plurality of first heavy particles and the matrix material. Patent Document 4 states that the acoustic impedance can be controlled by incorporating heavy particles and light particles into the matching layer and adjusting the heavy particle content. Patent Document 4 also states that epoxy resin is used as the matrix material and is cured at room temperature. Furthermore, Patent Document 4 states that tungsten particles, lead zirconate titanate (PZT) particles, gold particles and platinum particles are used as heavy particles, and silicon carbide particles and alumina particles are used as light particles. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2000-115893 [Patent Document 2] Japanese Patent Application Publication No. 03-172096 [Patent Document 3] Japanese Patent Publication No. 2005-177479 [Patent Document 4] Japanese Patent Publication No. 2012-235524 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, tungsten particles, as described in Patent Documents 3 and 4, have a higher density than the resin material. Therefore, when the resin material is heated to cure, the viscosity of the resin decreases before thermal curing, which can cause the particles to settle. When particles settle, they are not uniformly dispersed within the matching layer, which may lead to variations in acoustic impedance between areas with a high particle density and areas with a low particle density. In addition, because tungsten particles are metallic particles, the machinability of the cured product may decrease.

[0011] Furthermore, although tungsten is a metal with high electrical resistance, attempting to increase the output of ultrasonic probes or increase the operating voltage could lead to a short circuit.

[0012] Furthermore, as described in Patent Document 4, attempting to cure the resin material at room temperature suppresses the decrease in resin viscosity, but it increases the curing time and reduces production efficiency. Moreover, since the multiple first heavy particles and multiple second light particles each have a higher density than the matrix material (resin material), there is a risk of particle sedimentation occurring within the matching layer.

[0013] The present invention has been made in view of the above circumstances, and aims to provide a resin composition that can obtain a cured product in which particles are uniformly dispersed, and further improve the short-circuit resistance, cut-processability, and production efficiency of the cured product, as well as an acoustic member, an ultrasonic transducer, an ultrasonic probe, and an ultrasonic diagnostic device containing the cured product of the resin composition. [Means for solving the problem]

[0014] To solve the above problems, a resin composition according to one embodiment of the present invention is a resin composition used in the manufacture of an acoustic component used in an ultrasonic probe, comprising a thermosetting resin and two or more types of particles dispersed in the thermosetting resin, wherein the two or more types of particles include heavy particles, which are particles other than metal particles and have a density greater than that of the thermosetting resin, and light particles, which have a density less than that of the thermosetting resin, and the total content of the heavy particles and the light particles relative to the total volume of the cured product of the resin composition is 10% by volume or more.

[0015] Furthermore, an acoustic member according to one embodiment of the present invention for solving the above problems is an acoustic member used in an ultrasonic transducer, and is an acoustic member that includes a cured product of the resin composition.

[0016] Furthermore, an ultrasonic transducer according to one embodiment of the present invention, which solves the above problems, is an ultrasonic transducer that includes the above-mentioned acoustic member.

[0017] Furthermore, an ultrasonic probe according to one embodiment of the present invention, which solves the above problems, is an ultrasonic probe that includes the ultrasonic transducer described above.

[0018] Furthermore, an ultrasonic diagnostic apparatus according to one embodiment of the present invention for solving the above problems is an ultrasonic diagnostic apparatus that includes the ultrasonic probe. [Effects of the Invention]

[0019] The present invention provides a resin composition that can obtain a cured product with uniformly dispersed particles, thereby improving the short-circuit resistance, cut-processability, and production efficiency of the cured product, as well as an acoustic member, an ultrasonic probe, and an ultrasonic diagnostic device containing the cured product of the resin composition. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 is a cross-sectional view showing an example of the overall structure of an ultrasonic transducer according to one embodiment of the present invention. [Figure 2] Figure 2 shows the configuration of an ultrasound diagnostic device. [Modes for carrying out the invention]

[0021] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments.

[0022] 1.Resin composition The present invention relates to a resin composition for use in an acoustic component included in an ultrasonic transducer, which will be described later. The resin composition according to one embodiment of the present invention comprises a thermosetting resin and two or more types of particles dispersed in the thermosetting resin.

[0023] 1-1.Thermosetting resin Thermosetting resins are resins that harden when heated. Examples of thermosetting resins include epoxy resins, urethane resins, and silicone resins. Of these, thermosetting resins preferably contain epoxy resin. By including epoxy resin in the thermosetting resin, it is possible to improve the chemical resistance during cleaning of ultrasonic transducers while making it less likely for the cured resin composition (hereinafter simply referred to as "cured product") to warp deformation or fracture due to shrinkage of the resin composition during hardening. Furthermore, by including epoxy resin in the thermosetting resin, it is possible to easily adjust the sound velocity and acoustic impedance in the cured product, and when the cured product is used as an acoustic matching layer, it is possible to reduce ultrasonic propagation loss. In addition to these properties, by including epoxy resin in the thermosetting resin, it is possible to suppress the expansion of the cured product due to changes in ambient temperature during the manufacture of ultrasonic transducers, and the expansion of the cured product due to the heat generated by the piezoelectric material during the use of ultrasonic transducers. This makes it less likely for the piezoelectric material to be damaged due to the expansion of the cured product.

[0024] Examples of epoxy resins include: Glycidyl ether type epoxy resins, including bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, Hydrophthalic acid type epoxy resins, dimer acid type epoxy resins, and other glycidyl ester type epoxy resins, Aromatic amine type epoxy resins, glycidylamine type epoxy resins such as aminophenol type epoxy resins including triglycidyl-p-aminophenol, Biphenyl novolac epoxy resins such as phenol novolac type epoxy resins and cresol novolac type epoxy resins This includes phosphorus-modified epoxy resins, liquid crystalline epoxy resins, biphenyl aralkyl type epoxy resins, cyanuric acid type epoxy resins, cyclic aliphatic epoxy resins, naphthalene skeleton type epoxy resins, and long-chain aliphatic epoxy resins. Examples of commercially available epoxy resins include jER828 (manufactured by Mitsubishi Chemical Corporation).

[0025] Of these, from the viewpoint of improving the storage stability of the resin composition, the epoxy resin is preferably a glycidyl ether type epoxy resin, a glycidyl ester type epoxy resin, or a glycidylamine type epoxy resin.

[0026] Examples of polyurethane resins include well-known polyurethane resins. Polyol compounds that make up polyurethane resins include polyester polyols, polyether polyols, polycarbonate polyols, polyolefin polyols (including polyols obtained by hydrogenating polydiene polyols), polybutadiene polyols, polyisoprene polyols, and acrylic resin polyols.

[0027] Examples of silicone resins include room-temperature curing silicone rubber, heat-curing silicone rubber, condensation reaction type silicone rubber powder, and addition reaction type silicone rubber. Specifically, these include methyl silicone resin, methylphenyl silicone resin, organic resin-modified silicone resin, and silicone oligomers having alkoxy groups such as methoxy groups and ethoxy groups, as well as reactive functional groups such as epoxy groups, methacrylic groups, and mercapto groups.

[0028] Thermosetting resins may be two-component types in which the main component and the hardener are mixed during curing, or they may be one-component types.

[0029] The viscosity of the thermosetting resin (main component in the case of a two-component type) at 25°C is not particularly limited, but is preferably 1 Pa·s to 30 Pa·s, more preferably 8 Pa·s to 20 Pa·s, and even more preferably 12 Pa·s to 15 Pa·s. If it is 1 Pa·s or higher, the heavy particles and light particles described later will not settle easily when the resin composition is heated (cured), and if it is 30 Pa·s or lower, the coatability of the resin composition of the present invention on the piezoelectric material of an ultrasonic probe can be improved. In this specification, "coatability" means the ease with which the resin composition can be applied to a substrate such as a piezoelectric material. Furthermore, the viscosity may be adjusted by mixing multiple thermosetting resins, by adding a reactive diluent such as an epoxy resin diluent, or by adding a solvent. However, from the viewpoint of suppressing the aggregation of heavy or light particles and reducing the drying effort after application to improve production efficiency, it is preferable that the thermosetting resin does not contain a reactive diluent or a solvent. The viscosity can be measured using a rotational viscometer, a vibratory viscometer, or the like. In this embodiment, the viscosity is measured using a rheometer (Anton Paar, MCR102).

[0030] The weight-average molecular weight (Mw) of the thermosetting resin before curing is not particularly limited, but is preferably between 150 and 50,000, and more preferably between 200 and 30,000. Within this range, if the weight-average molecular weight (Mw) is 150 or higher, the volatilization of the thermosetting resin before curing is further suppressed, thereby improving the durability of the cured product. Furthermore, if the weight-average molecular weight (Mw) is 50,000 or lower, the coatability of the resin composition can be further improved without excessively increasing the viscosity of the thermosetting resin. The weight-average molecular weight (Mw) is measured using gel permeation chromatography (GPC) with polystyrene as the standard.

[0031] The density of the thermosetting resin before curing is not particularly limited, as long as it is smaller than the heavy particles (described later) and larger than the light particles. From the viewpoint of making it easier to adjust the acoustic impedance, the density of the thermosetting resin is 1.0 g / cm³. 3It is preferably 1.4 g / cm or less, more preferably 1.1 g / cm or more and 1.3 g / cm or less. When the density of the thermosetting resin is 1.0 g / cm or more, a more sufficient acoustic impedance can be obtained to suppress the reflection of ultrasonic waves in the ultrasonic transducer. When the density of the thermoplastic resin is 1.4 g / cm or less, the decrease in acoustic impedance due to the decrease in the speed of sound in the cured product of the resin composition can be more sufficiently suppressed. Further, when the density of the thermosetting resin before curing is 1.1 g / cm or more and 1.3 g / cm or less, more particles among the particles contained in the thermosetting resin can cause interference sedimentation, so that it becomes easier to disperse in the thermosetting resin. 3 It is preferably below, and more preferably 1.1 g / cm or more and 1.3 g / cm or less. 3 It is preferably 1.3 g / cm or more, 3 and more preferably below. When the density of the thermosetting resin is 1.0 g / cm or more, a more sufficient acoustic impedance can be obtained to suppress the reflection of ultrasonic waves in the ultrasonic transducer. When the density of the thermoplastic resin is 1.4 g / cm or less, the decrease in acoustic impedance due to the decrease in the speed of sound in the cured product of the resin composition can be more sufficiently suppressed. Further, when the density of the thermosetting resin before curing is 1.1 g / cm or more and 1.3 g / cm or less, more particles among the particles contained in the thermosetting resin can cause interference sedimentation, so that it becomes easier to disperse in the thermosetting resin. 3 By being 1.0 g / cm or more, a more sufficient acoustic impedance can be obtained to suppress the reflection of ultrasonic waves in the ultrasonic transducer. When the density of the thermoplastic resin is 1.4 g / cm or less, the decrease in acoustic impedance due to the decrease in the speed of sound in the cured product of the resin composition can be more sufficiently suppressed. 3 By being below, the decrease in acoustic impedance due to the decrease in the speed of sound in the cured product of the resin composition can be more sufficiently suppressed. Further, when the density of the thermosetting resin before curing is 1.1 g / cm or more and 1.3 g / cm or less, more particles among the particles contained in the thermosetting resin can cause interference sedimentation, so that it becomes easier to disperse in the thermosetting resin. 3 It is preferably 1.3 g / cm or more, 3 and when it is below, among the particles contained in the thermosetting resin, more particles can cause interference sedimentation, so that it becomes easier to disperse in the thermosetting resin.

[0032] In this embodiment, the curing agent undergoes a crosslinking reaction with the thermosetting resin and cures the thermosetting resin by being heated at a temperature of 50 °C or higher and 200 °C or lower.

[0033] Examples of the curing agent for curing the epoxy resin among the thermosetting resins include amine-based curing agents, imidazole-based curing agents, imidazolium salt-based curing agents,triazine trithiol-based curing agents, thiol-based curing agents, acid anhydride-based curing agents, and the like.

[0034] Examples of amine-based curing agents include linear aliphatic polyamines such as diethylenetriamine, triethylenetetramine, dipropylenediamine, diethylaminopropylamine, 2,2'dimethyl-4,4'methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexaneamine), and 3,3'-dimethyl-diaminodicyclohexylmethane; cyclic aliphatic polyamines such as N-aminoethylpiperazine, mensendiamine, and isophoronediamine; aromatic amines such as m-xylenediamine, metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone; polyamide resins; piperidine; N,N-dimethylpiperazine; triethylenediamine; 2,4,6-tris(dimethylaminomethyl)phenol; benzyldimethylamine; 2-(dimethylaminomethyl)phenol; and trisdimethylaminomethylphenol.

[0035] Examples of imidazole-based curing agents include imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, and 1-benzyl-2-methylimidazole.

[0036] Examples of imidazolium salt-based curing agents include 1-cyanoethyl-2-undecylimidazolium trimellitate.

[0037] Examples of thiol-based curing agents include hydrocarbon-type thiol-based curing agents such as 1,4-butanedithiol and 1,6-hexanedithiol. Ether-type thiol curing agents such as 3,6-dioxa-1,8-octanedithiol and 3,4-dimethoxybutane-1,2-dithiol, Alcohol-type thiol curing agents such as 1,3-dimercapto-2-propanol and 2,3-dimercapto-1-propanol, This includes things like:

[0038] Examples of acid anhydride-based curing agents include phthalic anhydride, trimellitic anhydride, methyltetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, and methylhexahydrophthalic acid.

[0039] Of these, amine-based or imidazole-based curing agents are preferred from the viewpoint of further improving heat resistance and chemical resistance. Examples of commercially available amine-based curing agents include jER Cure 113 (manufactured by Mitsubishi Chemical Corporation). Examples of imidazole-based curing agents include Cureazole 2E4MZ and Cureazole 1B2MZ (both manufactured by Shikoku Chemicals Co., Ltd.).

[0040] Isocyanate compounds can be used as curing agents for urethane resins. An isocyanate compound is a compound having two or more isocyanate groups in its molecule. Examples of isocyanate compounds include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), phenylene diisocyanate, xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI), cyclohexane diisocyanate, lysine ester diisocyanate, lysine ester triisocyanate (LDI), undecane triisocyanate, hexamethylene triisocyanate, triphenylmethane triisocyanate, and polymers, derivatives, modified forms, hydrogenated forms of the above isocyanate compounds.

[0041] The amount of hardener is not particularly limited. When using commercially available thermosetting resins, the amount specified for each product can be used.

[0042] Glass transition temperature T of thermosetting resin after curing g1The temperature is not particularly limited, but is preferably 80°C to 200°C, and more preferably 100°C to 180°C. g1 If the temperature is 80°C or higher, the glass transition temperature of the resin composition T g1 Because this can be enhanced, it is possible to suppress the hardening of the resin composition when applying it. Furthermore, the above T g1 If the temperature is 100°C or higher, the chemical resistance of the cured product can be further improved. g1 If the temperature is 200°C or lower, the time required for the resin composition to harden can be shortened. Furthermore, the above T g1 By keeping the temperature below 180°C, the temperature difference required for the resin composition to return to room temperature after curing is reduced, making it less likely for warping deformation to occur due to the difference in the coefficient of linear expansion between the resin composition and the substrate to which the resin composition is coated. The above glass transition temperature is measured using a differential scanning calorimeter "Diamond DSC" (manufactured by PerkinElmer) under heating and cooling conditions with a temperature rise / fall rate of 10°C / min and a heating range from 0°C to 150°C.

[0043] 1-2. Particles The resin composition according to this embodiment contains two or more types of particles. These two or more types of particles include heavy particles with a density greater than that of the thermosetting resin and light particles with a density less than that of the thermosetting resin.

[0044] In the invention described in Patent Document 4, two or more types of particles are mixed in the resin. However, since the density of these particles is greater than the density of the resin, when the viscosity of the thermosetting resin decreases during heat curing, the particles tend to settle, and significant particle settling occurs during heating. When settling occurs, the particles are unevenly distributed within the cured material. Therefore, when the cured material is used as an acoustic component of an ultrasonic probe, there is a risk that variations in acoustic impedance may occur between areas with a high particle concentration and areas with a low particle concentration.

[0045] Furthermore, if only particles with a density lower than that of the resin are included, the particles will float to the surface during thermal curing, resulting in an uneven distribution of particles within the resin. This causes variations in the acoustic impedance within the matching layer, similar to the case of sedimentation.

[0046] In contrast, the above-mentioned resin composition incorporates particles with a density greater than the resin and particles with a density less than the resin into the resin, causing interference sedimentation within the resin. This suppresses particle sedimentation during heating and improves the dispersibility of particles in the cured product.

[0047] Interference sedimentation is a phenomenon in which particles settle while being influenced by other particles that are settling simultaneously. When interference sedimentation occurs, the settling velocity of a particle is slower than the settling velocity when it settles without being influenced by other particles. In the resin composition according to the present invention, heavy particles tend to settle, while light particles tend to float, so the particles interfere with each other, making it difficult for particles to settle and float. Therefore, the resin can be cured before variations in the amount of particles present occur due to settling and floating, and the dispersibility of particles in the cured product can be easily improved.

[0048] Furthermore, as described in Patent Document 4, curing a thermosetting resin at room temperature results in less decrease in viscosity and suppression of particle sedimentation compared to curing by heating. However, the time required for the thermosetting resin to cure is longer than when curing by heating, which leads to a problem of reduced production efficiency.

[0049] In contrast, the above-mentioned resin composition can suppress particle sedimentation during heating, as described above, thus enabling curing by heating while suppressing particle sedimentation. This shortens the curing time compared to curing at room temperature, thereby improving production efficiency.

[0050] 1-2-1. Heavy particles Heavy particles are particles other than metal particles that have a higher density than thermosetting resins.

[0051] In a resin composition, only one type of heavy particle may be included, or two or more types may be included. From the viewpoint of making it easier to adjust the viscosity of the resin composition, it is preferable to include two or more types.

[0052] As described in Patent Document 3, when metal particles such as tungsten particles are used, the ductility of the metal particles can cause clogging of the blade, chipping of the blade, and deformation of the cured resin composition when attempting to cut it, potentially reducing the cutting performance. Furthermore, the electrical conductivity of the metal particles may reduce the short-circuit resistance of the acoustic component. Although tungsten is a material with high electrical resistance as a metal, acoustic components used in ultrasonic probes require higher short-circuit resistance than conventional materials in order to accommodate increased output and higher operating voltages of ultrasonic probes.

[0053] Furthermore, because metals have relatively high surface free energy, they have low affinity with resins, which have relatively low surface free energy. Therefore, metal particles such as tungsten particles are thought to be prone to settling in resin compositions. In contrast, inorganic materials other than metals have relatively low surface free energy, and therefore, particles of inorganic materials other than metals are thought to be less prone to settling than metal particles.

[0054] Therefore, by using particles other than metal particles as heavy particles, both cut-processability and short-circuit resistance can be improved. Furthermore, by using particles other than metal as heavy particles, the surface energy of the particles can be lowered, improving dispersibility with thermosetting resins.

[0055] Examples of such heavy particle materials include ferrite, tungsten oxide, aluminum oxide, titanium oxide, tantalum oxide, niobium oxide, and zirconium oxide. Of these, the heavy particle material is preferably a metal oxide from the viewpoint of further improving dispersibility in thermosetting resins, more preferably ferrite or tungsten oxide from the viewpoint of further improving the machinability of the cured resin composition, and even more preferably ferrite.

[0056] From the viewpoint of further improving short-circuit resistance, heavy particles are preferably insulators or semiconductors. Examples of insulators include ferrite, aluminum oxide, titanium oxide, niobium oxide, zirconium oxide, etc. Examples of semiconductors include tungsten oxide, etc. In this specification, "a particle is an insulator or semiconductor" means that the volume resistivity of the particle is 0.1 Ω·cm or more. Furthermore, "a particle is an insulator" means that the volume resistivity of the particle is 10 6 This means it is greater than or equal to Ω·cm.

[0057] The density of heavy particles is not particularly limited as long as it is greater than that of the thermosetting resin, but it is preferably 2 to 9 times the density of the thermosetting resin, and more preferably 3 to 7 times. If it is 2 times or more, the density of the resin composition can be increased further, making it easier to adjust to the desired acoustic impedance, and if it is 3 times or more, the density of the resin composition can be increased even further, making it easier to adjust to the desired acoustic impedance. If it is 9 times or less, sedimentation of heavy particles becomes less likely, and if it is 7 times or less, sedimentation of heavy particles becomes even less likely.

[0058] From the perspective of making it easier to satisfy these conditions, heavy particles have a density of 3.0 g / cm³. 3 More than 10.0g / cm 3 Preferably, it is 3.5 g / cm³. 3 More than 7.2g / cm 3 Preferably, it is 4.0 g / cm³. 3 More than 7.0g / cm 3It is more preferable that it be less than 4.0 g / cm³. 3 More than 6.0g / cm 3 It is even more preferable that the following is the case: 3.5 g / cm³ 3 This allows for easier interference sedimentation with lighter particles, resulting in a density of 7.2 g / cm³. 3 The following conditions make it more difficult for heavier particles to settle.

[0059] The shape of the heavy particles is not particularly limited and may be spherical or amorphous. From the viewpoint of making it difficult for the heavy particles to settle, it is preferable that the heavy particles include amorphous particles. Irregularly shaped particles have a larger surface area than spherical particles of the same mass and are more likely to come into contact with each other. Therefore, when heavy particles include amorphous particles, interference settling due to contact with light particles becomes more likely. This makes it difficult for the particles to settle. In this specification, "irregularly shaped particles" means particles that have irregularities on their surface, for example, particles with a sphericity of 0.9 or less. Whether or not heavy particles are amorphous can be determined, for example, by observation images taken with a scanning electron microscope (SEM).

[0060] The particle size of the heavy particles is not particularly limited, but it is preferable that the heavy particles include particles with a particle size of 0.1 μm or more and 25.0 μm or less, more preferably particles with a particle size of 0.5 μm or more and 22.5 μm or less, and more preferably particles with a particle size of 0.8 μm or more and 20.0 μm or less. Since there is a positive correlation between the viscosity of the resin containing the particles and the specific surface area of ​​the particles, including particles with a particle size of 0.1 μm or more in the heavy particles makes it easier to adjust the viscosity of the resin composition by reducing the total specific surface area of ​​the heavy particles, thereby improving the coatability of the resin composition. Furthermore, including particles with a particle size of 25.0 μm or less makes it easier to cut the cured resin composition. In addition, including particles with a particle size within the above range makes it easier to adjust the acoustic impedance of the cured product. The particle size and particle size distribution are measured by cutting the cured resin composition and processing the image of the cross-section.

[0061] When a cured resin composition is used as an acoustic matching layer, it is preferable to appropriately adjust the particle size of the heavy particles according to the center frequency of the ultrasonic transducer. For example, when the thickness of the acoustic matching layer in the direction of ultrasonic propagation is set to 1 / 4 of the wavelength, it is preferable that the particle size of the heavy particles be smaller than the above thickness. Specifically, when the sound velocity in the acoustic matching layer is 2500 m / sec for ultrasonic waves with a frequency of 10 MHz, the thickness of the acoustic matching layer in the direction of ultrasonic propagation is set to 62.5 μm. In this case, it is preferable that the particle size of the heavy particles contained in the resin composition (acoustic matching layer) is 62.5 μm or less. From the viewpoint of making it difficult to attenuate ultrasonic waves, the heavy particles should have a particle size (d) such that the cumulative value in the volume-based particle size distribution obtained by the above measurement method is 90%. 90 Preferably, the wavelength of the heavy particles is 1 / 8 or less of the wavelength of the ultrasound. This further suppresses the absorption or scattering of ultrasound by the heavy particles, thus making it less likely for the ultrasound to attenuate.

[0062] When using a cured resin composition as a backing material, the heavy particles have a particle size (d) such that the cumulative value in the volume-based particle size distribution obtained by the above measurement method is 10%. 10 It is preferable that the heavy particles have a particle size (d 10 If the backing material contains particles whose wavelength is 1 / 8 or more of the wavelength of the ultrasound, the heavy particles in the backing material will be more likely to absorb or scatter the ultrasound, thus making it easier to attenuate the ultrasound.

[0063] Heavy particles are defined as particles with a particle size (d) at which the cumulative value in the volume-based particle size distribution obtained by the above measurement method becomes 10%. 10 The particle size (d) is 0.5 μm or larger, and the cumulative value of the above is 90%. 90 It is preferable that the particles include those with a diameter of 22.5 μm or less. 10 By including particles that are 0.5 μm or larger, the coatability of the resin composition can be further improved, d 90By including particles with a particle size of 22.5 μm or less, the machinability of the cured resin composition can be further improved. Furthermore, by including heavy particles having the above-mentioned particle size distribution, it becomes easier to adjust the acoustic impedance of the cured product. From the above viewpoint, d 10 0.8 μm or larger, d 90 It is more preferable that the particles include a size of 20.0 μm or less, d 10 It is 1.0 μm or larger, d 90 It is even more preferable that the material contains particles with a diameter of 18.0 μm or less.

[0064] The particle size (d) of heavy particles at which the cumulative value in the volume-based particle size distribution obtained by the above measurement method becomes 50% 50 ) is not particularly limited, but heavy particles are as described above d 50 It is preferable that the material contains particles with a diameter of 22.5 μm or less, preferably particles with a diameter of 0.5 μm or more and 22.5 μm or less, more preferably particles with a diameter of 0.8 μm or more and 20.0 μm or less, even more preferably particles with a diameter of 1.0 μm or more and 15.0 μm or less, and particularly preferably particles with a diameter of 1.0 μm or more and 14.0 μm or less. 50 Including particles with a diameter of 0.5 μm or more can further improve the coatability of the resin composition, and including particles with a diameter of 22.5 μm or less can further improve the cut-processability of the cured resin composition. Furthermore, heavy particles are as described above d 50 Including particles within the above range makes it easier to adjust the acoustic impedance of the cured product. When the cured resin composition is used as an acoustically matching layer, from the viewpoint of making it difficult to attenuate ultrasound, heavy particles are d 50 It is preferable that it contains particles of 22.5 μm or less.

[0065] The heavy particle content is not particularly limited, but is preferably 1% to 30% by volume, more preferably 5% to 20% by volume, and even more preferably 5% to 15% by volume, relative to the total volume of the cured resin composition. If the content is 1% or more by volume, interference sedimentation with light particles can be easily caused, and if it is 30% or less by volume, sedimentation of heavy particles can be made difficult.

[0066] 1-2-2. Light particles Light particles are particles with a lower density than thermosetting resins. Examples of such light particle materials include silicone rubber and hollow glass beads. When a cured resin composition is used as a backing material, the light particle material is preferably an organic material from the viewpoint of easily attenuating ultrasonic waves. Examples of the above organic materials include silicone rubber.

[0067] In a resin composition, only one type of light particle may be included, or two or more types may be included. From the viewpoint of making it easier to adjust the viscosity of the resin composition, it is preferable to include two or more types.

[0068] The density of the light particles is not particularly limited as long as it is lower than that of the thermosetting resin, but it is preferably 0.4 times or more and less than 1 time, and more preferably 0.8 times or more and less than 1 time, relative to the density of the thermosetting resin. If it is 0.4 times or more, the light particles will be less likely to float in the resin composition, and if it is 0.8 times or more, the light particles will be even less likely to float in the resin composition. Furthermore, if it is less than 1 time, it will be easier to adjust to the desired acoustic impedance.

[0069] From the perspective of making it easier to meet these conditions, light particles have a density of 0.5 g / cm³. 3 More than 1.2g / cm 3 Preferably, it contains particles that are as follows: 0.8 g / cm³ 3 More than 1.2g / cm 3 It is more preferable to include the following particles: 0.5 g / cm³ 3By including particles of the above size, lighter particles are less likely to float within the resin composition, resulting in a density of 1.2 g / cm³ or less. 3 This makes it easier to induce interference sedimentation with heavier particles.

[0070] The shape of the light particles is not particularly limited; they may be spherical or irregular in shape. From the viewpoint of increasing the surface area of ​​the light particles and making them less likely to settle, it is preferable that the light particles include irregularly shaped particles. Irregularly shaped particles have a larger surface area than spherical particles of the same mass, and are more likely to come into contact with each other. Therefore, by including irregularly shaped particles in the light particles, interference settling due to contact with heavy particles becomes more likely. This makes it less likely for the particles to settle. Whether or not the heavy particles are irregular in shape can be determined, for example, by observation images taken with a scanning electron microscope (SEM).

[0071] The particle size of the light particles is not particularly limited, but it is preferable that the light particles include particles with a particle size of 0.1 μm or more and 25.0 μm or less, more preferably particles with a particle size of 0.5 μm or more and 22.5 μm or less, and even more preferably particles with a particle size of 0.8 μm or more and 20.0 μm or less. Including particles with a particle size of 0.1 μm or more can further improve the coatability of the resin composition, and including particles with a particle size of 25.0 μm or less can further improve the cut-processability of the cured resin composition. In addition, by including light particles with particle sizes within the above ranges, it is possible to adjust the acoustic impedance. The particle size is measured by cutting the cured resin composition and processing the image of the cross-section.

[0072] When using a cured resin composition as an acoustically matching layer, from the viewpoint of reducing ultrasonic attenuation, the light particles should have a particle size (d) such that the cumulative value in the volume-based particle size distribution obtained by the above measurement method is 90%. 90 Preferably, the wavelength of the particles is 1 / 8 or less of the wavelength of the ultrasound. This further suppresses the absorption or scattering of ultrasound by light particles, thus making it less likely for the ultrasound to attenuate.

[0073] When using a cured resin composition as a backing material, the light particles have a particle size (d) such that the cumulative value in the volume-based particle size distribution obtained by the above measurement method is 10%. 10 It is preferable that the particles have a particle size (d) of 1 / 8 or more of the wavelength of the ultrasound. 10 If the backing material contains particles whose wavelength is 1 / 8 or more of the wavelength of the ultrasound, the heavy particles in the backing material will be more likely to absorb or scatter the ultrasound, thus making it easier to attenuate the ultrasound.

[0074] Light particles are defined as particles with a particle size (d) such that the cumulative value in the volume-based particle size distribution obtained by the above measurement method is 10%. 10 The particle size (d) is 0.5 μm or larger, and the cumulative value of the above is 90%. 90 It is preferable that the particles include those with a diameter of 22.5 μm or less. 10 By including particles that are 0.5 μm or larger, the coatability of the resin composition is further enhanced, d 90 By including particles with a particle size of 22.5 μm or less, the machinability of the cured resin composition can be further improved. Furthermore, by including light particles having the above-mentioned particle size distribution, it becomes easier to adjust the acoustic impedance of the cured product. From the above viewpoint, d 10 0.8 μm or larger, d 90 It is more preferable that the particles include a size of 20.0 μm or less, d 10 It is 1.0 μm or larger, d 90 It is even more preferable that the material contains particles with a diameter of 18.0 μm or less.

[0075] For light particles, the particle size at which the cumulative value in the volume-based particle size distribution obtained by the above measurement method becomes 50% (d 50 ) is not particularly limited, but light particles are as described above d 50 However, it is preferable to include particles that are 22.5 μm or less, more preferably to include particles that are 0.5 μm or more and 22.5 μm or less, more preferably to include particles that are 0.8 μm or more and 20.0 μm or less, even more preferably to include particles that are 1.0 μm or more and 15.0 μm or less, and particularly preferably to include particles that are 1.0 μm or more and 14.0 μm or less.50 Including particles with a diameter of 0.5 μm or more can further improve the coatability of the resin composition, and including particles with a diameter of 22.5 μm or less can further improve the cut-processability of the cured resin composition. In addition, light particles are d 50 By including particles within the above range, it becomes easier to adjust the acoustic impedance.

[0076] Light particles are defined as particles with a particle size (d) such that the cumulative value in the volume-based particle size distribution is 50% or higher than that of heavy particles. 50 ) preferably contains small particles, and the above d 50 It is preferable that the value is small. Here, "light particles are more d than heavy particles." 50 "Contains small particles" means that when light particles contain multiple types of particles made of different materials, at least one of these particles contains d 50 However, the d of the entire heavy particle 50 This means that it is smaller than d. Also, "light particles are smaller than heavy particles." 50 "Small" means that d refers to the entire range of light particles. 50 However, d, which targets heavy particles as a whole 50 This means smaller than d of light particles. 50 Because the particles are smaller than heavy particles, when the cured material is used as an acoustically matching layer, even if the light particle material is an organic material that easily attenuates ultrasound, it can reduce the attenuation of ultrasound.

[0077] Furthermore, the above d of light particles 50 The above d of heavy particles 50 By being smaller than d, the sedimentation of heavy particles can be suppressed more effectively. This is because there is a positive correlation between the specific surface area of ​​the particles and the viscosity of the solvent (thermosetting resin) containing the particles. Specifically, as the particle size decreases, the specific surface area of ​​the particles increases, and consequently the viscosity of the resin containing the particles increases, thus reducing the d of light particles. 50By making the particles smaller than the heavy particles, interference sedimentation can be induced while increasing the viscosity of the thermosetting resin. This allows for more effective suppression of heavy particle sedimentation (see "Journal of the Japan Society of Powder Technology, Vol. 27 No. 3 (1990), Particle Dispersion, Aggregation and Concentrated Slurry Behavior, Arakawa").

[0078] Furthermore, the above d of light particles 50 The above d of heavy particles 50 Being smaller than the heavy particles can suppress the formation of irregularities on the surface of the cured resin composition, thereby improving the appearance quality. Although the reason for this is not entirely clear, it is thought that when light particles are smaller than heavy particles, the heavy particles can more effectively suppress the lifting of the light particles, making it more difficult for the light particles to orient themselves on the surface of the resin composition, and thus suppressing the formation of irregularities.

[0079] The content of light particles is not particularly limited, but is preferably 1% to 30% by volume, more preferably 5% to 20% by volume, and even more preferably 7% to 20% by volume, relative to the total volume of the cured resin composition. If the content is 1% or more by volume, interference sedimentation with heavy particles can be easily caused, and if it is 30% or less by volume, the light particles can be made less likely to float.

[0080] The content of light particles is preferably between 0.3 and 3 times the content of heavy particles. By adjusting these ratios, interference sedimentation between heavy and light particles can be facilitated, thereby further improving the dispersibility of particles in the resin.

[0081] In this embodiment, the total content of heavy and light particles relative to the total volume of the cured resin composition is 10% by volume or more. Having a total content of 10% by volume or more makes it easier to adjust the acoustic impedance of the cured product, allowing for sufficient interference sedimentation between the heavy and light particles to improve dispersibility. Furthermore, having a total content of 10% by volume or more increases the total specific surface area of ​​the particles, thereby increasing the viscosity of the resin composition and making particle sedimentation less likely. The total content of heavy and light particles is preferably 10% by volume or more and 50% by volume or less, and more preferably 15% by volume or more and 35% by volume or less. Having a total content of heavy and light particles of 50% by volume or less suppresses an excessive increase in the viscosity of the resin composition and ensures fluidity, making it easier to apply to piezoelectric materials. The total content of heavy and light particles should be adjusted so that the acoustic impedance of the acoustic member falls within the range described later. The above content may be calculated by cutting the cured resin composition and measuring the amount of heavy and light particles contained in the cross-section by image processing of the captured image, or by performing compositional analysis using SEM-EDX or the like.

[0082] In this embodiment, by creating a calibration curve relating the content of heavy and light particles to the acoustic impedance of the cured resin composition, it is possible to determine the content of heavy and light particles that will yield the desired acoustic impedance.

[0083] Furthermore, heavy and light particles may be surface-treated to further improve their dispersibility. Examples of such surface treatment methods include treatment with a solution (primer) containing a known silane coupling agent, and plasma treatment.

[0084] 1-2-3. Physical properties of resin compositions Glass transition temperature T of the cured resin composition according to this embodiment g2 The glass transition temperature T is not particularly limited, but is preferably 80°C or higher. g2If the temperature is 80°C or higher, it is possible to suppress the hardening of the resin composition when applying it. Furthermore, the above T g2 If the temperature is 100°C or higher, the chemical resistance of the cured product can be further improved. g2 If the temperature is 200°C or lower, the time required for the resin composition to harden can be shortened. Furthermore, the above T g2 By keeping the temperature below 180°C, the temperature difference between curing and returning to room temperature is reduced. This minimizes the difference in linear expansion between the resin composition and the substrate to which the resin composition is coated, thus reducing the likelihood of warping deformation that occurs when the cured product is cooled. The glass transition temperature of the resin composition is measured in the same manner as the glass transition temperature of the thermosetting resin described above.

[0085] The resin composition according to this embodiment can be manufactured by mixing the thermosetting resin, the heavy particles, and the light particles. The method of mixing these is not particularly limited, but from the viewpoint of minimizing the inclusion of air bubbles in the resin composition, it is preferable to stir in a vacuum. When mixing, stirring may be performed while cooling to suppress a rapid rise in the temperature of the resin composition.

[0086] 2. Acoustic components An acoustic member according to one embodiment of the present invention is an acoustic member used in an ultrasonic probe, and includes a cured product of the above-mentioned resin composition.

[0087] In this embodiment, the acoustic component may be the acoustic matching layer of an ultrasonic probe, a backing material, or a material used for other purposes.

[0088] The acoustic impedance of the acoustic member according to this embodiment is preferably 1.7 MRayls to 15.0 MRayls, and more preferably 2.5 MRayls to 4.5 MRayls. Being within this range reduces the difference between the acoustic impedance of the acoustic member and the acoustic impedance of the acoustic lens of the ultrasonic probe, making it difficult to reflect ultrasonic waves. In this embodiment, by including two or more types of particles, including heavy particles and light particles, in the resin composition, the acoustic impedance of the acoustic member can be adjusted to the above range while suppressing the sedimentation and buoyancy of the particles.

[0089] The acoustic component according to this embodiment may be manufactured by curing a resin composition applied to a substrate, or by curing a block formed from the resin composition.

[0090] When applying the above resin composition, the viscosity of the resin composition is preferably 1 Pa·s or more and 500 Pa·s or less, and more preferably 2 Pa·s or more and 150 Pa·s or less. A viscosity of 1 Pa·s or more can further suppress particle sedimentation, and a viscosity of 500 Pa·s or less can further improve the applicability. The viscosity can be adjusted by adjusting the content of thermosetting resin, heavy particles, and light particles, respectively, and by controlling the temperature when applying the resin composition.

[0091] The method for applying the above resin composition is not particularly limited, but can be appropriately selected from known methods. Examples of methods for applying the above resin composition include inkjet coating, die coating, bar coating, blade coating, and screen printing.

[0092] The temperature at which the above resin composition is applied is not particularly limited and is set appropriately depending on the application method and purpose. For example, when using a blade application method, it is preferable to adjust the coater temperature so that it is within ±5°C of the temperature at which the viscosity of the resin composition becomes 1 Pa·s or more and 500 Pa·s or less, and it is more preferable to adjust the coater temperature so that it is within ±5°C of the temperature at which the viscosity of the resin composition becomes 2 Pa·s or more and 150 Pa·s or less. By doing so, the thickness of the acoustic member in the direction of ultrasonic wave propagation can be adjusted to, for example, 10 μm or more and 500 μm or less.

[0093] Furthermore, from the viewpoint of further improving coatability, it is preferable that the above temperature is higher than room temperature (25°C) and lower than the curing temperature of the resin composition. A temperature higher than room temperature reduces the viscosity of the resin composition, making it easier to apply, and a temperature lower than the curing temperature suppresses the curing of the resin composition during application.

[0094] The substrate to which the above resin composition is applied is not particularly limited, but for example, a piezoelectric material.

[0095] Alternatively, from the viewpoint of easily performing maintenance such as cleaning, it is preferable to use a substrate that allows for the release of hardened acoustic components from the mold. By using such a substrate, for example, when one matching layer is bonded to another matching layer that has been partially micro-processed, these matching layers can be detached from the substrate as a whole, making it easy to maintain and replace the acoustic components. Examples of such substrates include those containing Teflon (Teflon is a registered trademark of Chemours).

[0096] Furthermore, the acoustic member according to this embodiment may contain a resin composition with a different composition from the above-mentioned resin composition and may be applied on top of an acoustic member with a different function. This makes it possible to laminate various acoustic members without using an adhesive, thus reducing the attenuation of ultrasonic waves caused by the adhesive.

[0097] Furthermore, the above-mentioned acoustic component may be molded into a block. A method for molding it into a block is, for example, carried out according to the following procedure.

[0098] (1) A 3mm thick silicone rubber sheet is cut to a size of 100mm square, and the cut-out silicone rubber sheet is placed on a glass plate whose surface has been treated with a water-repellent coating. (2) Next, the resin composition is poured into the cut-out portion of the silicone rubber sheet. (3) A glass plate, prepared separately and whose surface has been treated with a water-repellent coating, is placed on top. (4) The product created in (3) is heated to harden the resin composition, and then the hardened product is released from the silicone.

[0099] When an acoustic component is manufactured by coating it with the above-mentioned resin composition, the thickness in the direction of ultrasonic wave propagation is preferably 10 μm or more. When the thickness is 10 μm or more, it is easier to adjust the acoustic impedance of the acoustic component to the above-mentioned range. From the above viewpoint, the thickness of the acoustic component in the direction of ultrasonic wave propagation is preferably 10 μm or more and 500 μm or less, and more preferably 15 μm or more and 300 μm or less. When the thickness is 500 μm or less, the coated resin composition becomes less susceptible to deformation due to the effects of gravity.

[0100] Furthermore, when manufacturing an acoustic component by molding a resin composition into a block, the thickness is preferably 3000 μm or less. When the thickness is 3000 μm or less, heat is more easily transferred uniformly to the inside of the resin during the heat curing of the resin composition, thereby improving the dispersion of particles within the resin composition during curing. As a result, it becomes easier to adjust the acoustic impedance to a desired range. From the above viewpoint, the thickness of the acoustic component in the direction of ultrasonic wave propagation is preferably 100 μm or more and 3000 μm or less. When the thickness is 100 μm or more, damage to the cured resin composition can be suppressed when the cured product is demolded.

[0101] 3. Ultrasonic transducer 3-1. Configuration of an ultrasonic transducer An ultrasonic transducer according to one embodiment of the present invention is an ultrasonic transducer used in an ultrasonic probe, and includes the above-mentioned acoustic member.

[0102] Figure 1 is a cross-sectional view showing an example of the overall structure of an ultrasonic transducer 100 according to one embodiment of the present invention.

[0103] As shown in Figure 1, the ultrasonic transducer 100 includes a backing material 110, an electrical terminal output section 120, a piezoelectric material 130, an acoustic matching layer 140, and an acoustic lens 150. Each component will be described below with reference to the drawings.

[0104] 3-1-1. Backing material In this embodiment, the backing material 110 includes the acoustic member described above. The backing material 110 is also a member for supporting the electrical terminal extraction portion 120 and the piezoelectric material 130, which will be described later, and functions as a member for attenuating ultrasonic waves directed from the piezoelectric material 130 toward the back side.

[0105] In this embodiment, the backing material 110 is composed of a single layer, but the backing material 110 may be composed of multiple layers.

[0106] The thickness of the backing material 110 in the direction of ultrasonic wave propagation is appropriately selected according to the material and the wavelength of the ultrasonic waves emitted by the ultrasonic transducer.

[0107] 3-2. Electrical terminal extraction section The electrical terminal extraction section 120 is a component for transmitting signals to the piezoelectric material 130 via signal electrodes 160a and 160b, and for receiving signals from the piezoelectric material 130 via signal electrodes 160a and 160b. The electrical terminal extraction section 120 is positioned between the backing material 110 and the piezoelectric material 130, which will be described later. It is also electrically connected to an external power supply, diagnostic device, etc.

[0108] 3-3. Piezoelectric materials The piezoelectric material 130 is positioned on the electrical extraction section 120 (in this embodiment, on the electrical terminal extraction section 120 via the signal electrode 160a) and has the function of transmitting and receiving ultrasonic waves.

[0109] The center frequency of the ultrasonic waves emitted by the piezoelectric material 130 is not particularly limited, but is, for example, between 1 MHz and 20 MHz.

[0110] The thickness of the piezoelectric material 130 in the direction of ultrasonic wave propagation is appropriately selected depending on the type of ultrasonic transducer and the frequency at which the ultrasonic transducer oscillates, but is, for example, between 50 μm and 400 μm.

[0111] Examples of the piezoelectric material 130 mentioned above include piezoelectric ceramics such as lead zirconate titanate (PZT); piezoelectric single crystals such as lead niobate magnesium oxide / lead titanate solid solution (PMN-PT) and lead niobate zinc oxide / lead titanate solid solution (PZN-PT); and composite piezoelectric materials obtained by combining these materials with polymer materials.

[0112] Furthermore, the multiple signal electrodes 160a and 160b arranged on both sides of the piezoelectric material 130 are electrodes for applying voltage to the piezoelectric material 130. The signal electrodes 160a and 160b are not particularly limited as long as they are electrically connected to the electrical terminal extraction section 120 described above and are capable of sufficiently exchanging signals with the piezoelectric material 130, and can be layers made of gold, silver, copper, etc.

[0113] In this embodiment, the ultrasonic transducer has a piezoelectric material 130 that transmits and receives ultrasonic waves, but it may also have a piezoelectric material for transmitting ultrasonic waves and a piezoelectric material for receiving ultrasonic waves. These piezoelectric materials may be arranged in a stack or in parallel. From the viewpoint of saving space, it is preferable that these piezoelectric materials be arranged in a stack.

[0114] 3-4.Acoustic matching layer In this embodiment, the acoustic matching layer 140 includes the acoustic member described above. The acoustic matching layer 140 is a layer placed on the piezoelectric material 130 (in this embodiment, on the signal electrode 160b of the piezoelectric material 130) and is a layer for matching the acoustic characteristics between the piezoelectric material 130 and the acoustic lens 150. The acoustic matching layer 140 may consist of a single layer, but is usually composed of multiple layers with different acoustic impedances. The number of layers in the acoustic matching layer is not particularly limited, but is preferably two or more, and more preferably four or more. As shown in Figure 1, in this embodiment, the acoustic matching layer 140 is a laminate including a first acoustic matching layer 140a, a second acoustic matching layer 140b, a third acoustic matching layer 140c, and a fourth acoustic matching layer 140d.

[0115] The acoustic impedance of each layer constituting the acoustic matching layer 140 can be adjusted by changing the type and amount of thermosetting resin, heavy particles, and light particles in the resin composition constituting each layer. Note that each acoustic matching layer 140a, 140b, and 140c may contain the same resin composition or different resin compositions. Furthermore, the thickness of each layer may be the same or different.

[0116] The thickness of each acoustic matching layer in the direction of ultrasonic propagation is not particularly limited. From the viewpoint of easily adjusting the acoustic impedance to a desired range, it is known that the thickness is preferably 1 / 4 the wavelength of the ultrasonic wave. However, when there are two or more acoustic matching layers, it is more preferable that the thickness of each layer be 1 / 8 to 1 / 4 the wavelength of the ultrasonic wave. This shortens the time from when the piezoelectric material stops vibrating until ultrasonic waves are received (reverberation time) and makes it less likely for the sensitivity and signal strength of the received ultrasonic waves to decrease. From the viewpoint of easily satisfying these conditions, the thickness of each acoustic matching layer is preferably 10 μm to 500 μm, more preferably 15 μm to 500 μm, and even more preferably 15 μm to 250 μm.

[0117] 3-5. Acoustic Lenses The acoustic lens 150 is a component for focusing the ultrasonic waves transmitted from the piezoelectric material 130. As shown in Figure 1, in this embodiment, the acoustic lens 150 is a cylindrical acoustic lens that extends in the Y direction and protrudes in the Z direction in Figure 1. The shape of the cross-section perpendicular to the X direction is the same for all of them. The acoustic lens 150 focuses the ultrasonic waves emitted by each piezoelectric material 130a in the Z direction and emits them outside the ultrasonic transducer 100.

[0118] The acoustic lens 150 is made of a material having acoustic properties suitable for the object being tested, such as a living organism. For example, it is preferable that the acoustic lens 150 is made of a material having an acoustic impedance relatively close to that of the object being tested, such as silicone rubber.

[0119] 3-2. Method for Manufacturing an Ultrasonic Transducer The method for manufacturing the ultrasonic transducer described above is not particularly limited, and any method that allows for the above-described structure is acceptable. An example is shown below, but is not limited to this.

[0120] The method for manufacturing the ultrasonic transducer in this embodiment includes the steps of forming a backing material 110 on the back side of the piezoelectric material 130, forming an acoustic matching layer 140 on the piezoelectric material 130, and bonding the acoustic matching layer 140 and the acoustic lens 160 together.

[0121] 3-2-1. Process for forming the backing material In this process, a backing material 110 is formed on the back surface of the piezoelectric material 130 with respect to the direction in which ultrasonic waves are transmitted.

[0122] In this embodiment, the resin composition is molded into a block and adhered to the back side of the piezoelectric material 130 to form the backing material 110. The method for molding the resin composition into a block may be the same as the method described for the acoustic member described above. The method for applying the resin composition is not particularly limited, but can be appropriately selected from known methods. Examples of methods for applying the resin composition include inkjet coating, die coating, bar coating, blade coating, and screen printing.

[0123] Alternatively, the resin composition may be applied to a substrate that can release the formed backing material 110, and the substrate may be bonded to the piezoelectric material 130 to form the backing material 110 on the back side of the piezoelectric material 130.

[0124] Alternatively, the resin composition may be applied to the back surface of the piezoelectric material 130, and then the resin composition may be cured to form the backing material 110.

[0125] The method for curing the above resin composition is not particularly limited. From the viewpoint of suppressing curing shrinkage of the resin composition, it is preferable to pre-cur the resin composition at a temperature lower than the glass transition temperature, and then heat-cur it at a temperature higher than the glass transition temperature.

[0126] 3-2-2. Process of bonding the acoustic matching layer In this process, an acoustic matching layer 140 is formed on the surface of the piezoelectric material 130 in the direction in which ultrasonic waves are transmitted.

[0127] In this embodiment, this process can be carried out in the following procedure.

[0128] (1) After applying the resin composition onto the substrate, the resin composition is cured, (2) the cured resin composition is released from the substrate, (3) the cured material is cut to a size that can be placed on the piezoelectric material 130, and (4) the cured material is adhered to the piezoelectric material 130.

[0129] In (1) above, when the acoustic matching layer 140 is a laminate of multiple acoustic matching layers, the process of applying an uncured resin composition onto the cured resin composition and curing it is repeated. The substrate on which the resin composition is applied is not particularly limited, as long as it can release the cured product. The method of applying the resin composition is the same as the process of forming the backing material, so a detailed explanation is omitted.

[0130] As described above, by directly applying and curing the acoustic matching layer onto a cured resin composition, an acoustic matching layer can be formed without using adhesive materials such as adhesives between the layers of the acoustic matching layer. This makes it possible to further reduce ultrasonic propagation loss at the adhesive interface between the adhesive and the matching layer, which is caused by the difference in acoustic impedance between the adhesive and the matching layer.

[0131] In (3) above, the method for cutting the cured material is not particularly limited and can be done by known methods.

[0132] In (4) above, the method for bonding the cured product to the piezoelectric material 130 is not particularly limited, and for example, it can be bonded using a known adhesive.

[0133] In this embodiment, the resin composition may be applied directly to the piezoelectric material 130 and then cured to form an acoustically matching layer.

[0134] Alternatively, the above resin composition may be molded into a block and bonded to the surface of the piezoelectric material 130 in the direction in which ultrasonic waves are transmitted.

[0135] 3-2-3. Process of bonding the acoustic matching layer and the acoustic lens. In this process, the acoustic lens 160 is bonded onto the matching layer 140. The method of bonding the acoustic lens is not particularly limited; it may be bonded using a known adhesive, or it may be bonded with an adhesive layer 140 placed in between.

[0136] 4. Ultrasonic probes and ultrasound diagnostic equipment The ultrasonic transducer described above can be used in, for example, an ultrasonic probe 10 or an ultrasonic diagnostic device 1, as shown in Figure 2. The ultrasonic diagnostic device 1 includes an ultrasonic probe 10 equipped with the ultrasonic transducer 100 described above, a main unit 11, a connector unit 12, a display 13, and the like.

[0137] The ultrasonic probe 10 only needs to include the ultrasonic transducer (not shown) and is connected to the main body 11 via a cable 14 connected to the connector 12.

[0138] An electrical signal (transmission signal) from the main unit 11 is transmitted to the piezoelectric material of the ultrasonic probe 10 via the cable 14. This transmission signal is converted into ultrasound by the piezoelectric material and transmitted into the object under inspection. The transmitted ultrasound is reflected within the object under inspection. A portion of the reflected wave is received by the piezoelectric material, converted into an electrical signal (received signal), and transmitted to the main unit 11. The received signal is converted into image data in the main unit 11 of the ultrasound diagnostic device 1 and displayed on the display 13.

[0139] The ultrasonic diagnostic apparatus equipped with the ultrasonic transducer of the above embodiment offers high directivity and enables accurate diagnosis. Furthermore, the ultrasonic transducer is highly durable and can withstand impacts such as drops, making it suitable for use in ultrasonic diagnostic apparatuses in various fields. [Examples]

[0140] 1. Manufacturing of acoustic components In this embodiment, the materials used in the manufacture of the cured resin composition (hereinafter referred to as the acoustic component) are shown below.

[0141] 1-1.Thermosetting resin 1-1-1. Main ingredient • Epoxy resin main component (Mitsubishi Chemical Corporation, jER828, density: 1.17 g / cm³) 3 , viscosity: 12.0Pa·s or more and 15.0Pa·s or less)

[0142] 1-1-2. Hardener Epoxy resin curing agent 1 (Mitsubishi Chemical Corporation, jER Cure 113, curing start temperature 152°C) Epoxy resin curing agent 2 (Mitsubishi Chemical Corporation, ST12, curing temperature 75°C)

[0143] 1-3. Heavy particles · Ferrite powder 1 (Mn-Zn Ferrite-based particles, density: 4.9 g / cm 3 ) · Ferrite powder 2 (JFE Chemical Corporation, KNI-106, density: 5.15 g / cm 3 ) · Tungsten oxide powder (Allied Material Co., Ltd., F1-WO3, density: 7.2 g / cm 3 ) · Tungsten powder 1 (Nippon Shinku Metal Co., Ltd., W-5, density: 19.3 g / cm 3 ) · Tungsten powder 2 (Nippon Shinku Metal Co., Ltd., W-2KD, density: 19.3 g / cm 3 )

[0144] 1-4. Light particles · Silicone rubber powder (Shin-Etsu Chemical Co., Ltd., KMP-605, density: 0.99 g / cm 3 )

[0145] The viscosity of the main material was measured using a rheometer (Anton Paar, MCR102).

[0146] The particle sizes of the heavy and light particles were measured using a laser diffraction / scattering particle size distribution measuring device. Based on the particle size distribution obtained by the measurement, the d 10 , d 50 , d 90 were calculated respectively.

[0147] Hereinafter, resin compositions were manufactured and applied in Experiments 1 to 15. The "volume parts" of the heavy and light particles shown below mean the volume with respect to the volume of the cured resin composition. Tables 1 and 2 summarize the conditions of Experiments 1 to 15.

[0148] <Experiment 1> The epoxy resin main component, epoxy resin hardener 1, and the particle size (d) at which the cumulative value in the volume-based particle size distribution is 50% 50 Ferrite powder 1, which had been classified so that its particle size was between 5.5 μm and 6.4 μm, and silicone rubber powder were placed in a disposable cup and thoroughly mixed using a vacuum stirring device (Thinky Co., Ltd., ARV-310). At this time, the mixture was prepared so that the content of heavy and light particles relative to the total volume of the cured product obtained after curing (hereinafter referred to as the volume filling rate) was 10.0% for ferrite powder 1 and 5.0% for silicone rubber powder. To suppress the heat generated by the friction between the particles during mixing, the disposable cup was slowly cooled while stirring to obtain resin composition 1.

[0149] The volume filling ratios mentioned above were calculated by cutting the cured resin composition and measuring the amount of heavy and light particles contained in the cross-section by processing the captured images.

[0150] After stirring, the resulting resin composition 1 was applied to a glass substrate with a water-repellent surface to a thickness of 50 μm using an applicator (manufactured by Coating Tester Co., Ltd.). The thickness was adjusted by changing the width between the blade of the applicator and the glass substrate. During application, the temperature was adjusted so that the viscosity of the resin composition was 14 Pa·s.

[0151] <Experiment 2> The obtained resin composition 2 was applied in the same manner as in Experiment 1, except that ferrite powder 1 was replaced with ferrite powder 2.

[0152] <Experiment 3> Resin composition 3 was applied in the same manner as in Experiment 1, except that the volume filling rate of ferrite powder 1 and the volume filling rate of silicone rubber powder were changed to 12.5%.

[0153] <Experiment 4> Resin composition 4 was applied in the same manner as in Experiment 1, except that ferrite powder 1 was replaced with tungsten oxide powder.

[0154] <Experiment 5> Resin composition 5 was applied in the same manner as in Experiment 1, except that the volume filling rate of ferrite powder 1 was changed to 1.5% and the constant volume filling rate of silicone rubber powder was changed to 8.5%.

[0155] <Experiment 6> Resin composition 6 was applied in the same manner as in Experiment 1, except that the volume filling rate of ferrite powder 1 was 5.0% and the volume filling rate of silicone rubber powder was 10.0%.

[0156] <Experiment 7> Resin composition 7 was applied in the same manner as in Experiment 1, except that the volume filling rate of ferrite powder 1 was changed to 11.5% and the volume filling rate of silicone rubber powder was changed to 13.5%.

[0157] <Experiment 8> Resin composition 8 was applied in the same manner as in Experiment 1, except that the volume filling rate of ferrite powder 1 was changed to 19.0% and the volume filling rate of silicone rubber powder was changed to 16.0%.

[0158] <Experiment 9> The resin composition 9 was applied in the same manner as in Experiment 6, except that it was applied so that the thickness of the acoustic component was 10 μm.

[0159] <Experiment 10> A 3mm thick silicone rubber sheet was cut into a 100mm square shape, and the cut-out silicone rubber sheet was placed on a glass plate whose surface had been treated with a water-repellent coating. Next, the resin composition obtained in Experiment 1 was poured into the cut-out portion of the silicone rubber sheet. Then, another glass plate, which had been prepared separately and whose surface had also been treated with a water-repellent coating, was placed on top.

[0160] <Experiment 11> The resin composition 11 was applied in the same manner as in Experiment 1, except that the volume filling rate of ferrite powder 1 was changed to 5.0% and the volume filling rate of silicone rubber powder to 1.0%.

[0161] <Experiment 12> A thermosetting resin comprising an epoxy resin main component and an epoxy resin curing agent 2, and a particle size (d) such that the cumulative value in the volume-based particle size distribution is 50%. 50 Ferrite powder 1, which had been classified so that its particle size was between 5.5 μm and 6.4 μm, was placed in a disposable cup and thoroughly mixed using a vacuum stirring device (Thinky Co., Ltd., ARV-310). The ferrite powder 1 was mixed so that its volume filling rate was 3.0%. To suppress the heat generated by the friction between the particles during mixing, the disposable cup was slowly cooled while stirring to obtain resin composition 12.

[0162] After stirring, the obtained resin composition 11 was applied to a glass substrate whose surface had been treated with a water-repellent coating using an applicator (manufactured by Coating Tester Co., Ltd.) to a thickness of 50 μm. During this process, the coating was carried out while adjusting the temperature so that the viscosity of the resin composition was 14 Pa·s.

[0163] <Experiment 13> The resin composition was applied in the same manner as in Experiment 13, except that a thermosetting resin containing epoxy resin and epoxy resin curing agent 1 was used.

[0164] <Experiment 14> The resin composition 14 was applied in the same manner as in Experiment 11, except that the ferrite powder 1 was replaced with tungsten powder 1 with a volume filling rate of 10.0%, and an additional 5.0 parts by volume of silicone rubber was added.

[0165] <Experiment 15> The resin composition 15 was applied in the same manner as in Experiment 13, except that tungsten powder 1 was replaced with tungsten powder 2.

[0166] 1-5.Curing Under the conditions of experiments 1 to 15 described above, the coated or molded resin compositions 1 to 15 were placed in a constant temperature bath and pre-cured in environments of 40°C, 60°C, 80°C, and 100°C, respectively. The pre-curing times were 12 hours or more at 40°C, 6 hours at 60°C, 4 hours at 80°C, and 2 hours at 100°C. Subsequently, the pre-cured materials obtained at each pre-curing temperature were heat-cured for 4 hours at 150°C to produce acoustic components 1 to 15.

[0167] 2. Evaluation <Settlement Assessment> The obtained acoustic materials were observed in cross-section at each temperature during pre-curing, and the presence or absence of sedimentation of heavy and light particles was evaluated according to the following criteria. ○ No particle sedimentation was observed. × Particle sedimentation has been observed, making the product unsuitable for use.

[0168] <Production Speed> Regarding the production speed of acoustic components, the time from the start of mixing the thermosetting resin, heavy particles, and light particles until the completion of heat curing at the highest curing temperature at which the above-mentioned sedimentation evaluation was successful was defined as "the time required to manufacture acoustic components," and was evaluated according to the following criteria. ○ The time required for the final curing process is less than 8 hours. △ The time required for the final curing process is between 8 and 12 hours. × The time required for the final curing process is more than 12 hours.

[0169] <Cutability> Acoustic components were cut 200 times at 50 μm intervals with a cutting distance of 10 mm using a dicing saw (DISCO Corporation, (DAD3350)) and a dicing blade with a width of 25 μm, and evaluated according to the following criteria. ○ No deformation occurs in the acoustic component during cutting. × The acoustic component may deform during cutting, making it impossible to cut correctly.

[0170] <Short-circuit resistance> An acoustic member was incorporated into an ultrasonic probe as an acoustic matching layer and operated, and the short-circuit resistance was evaluated according to the following criteria. ○ Operates normally without problems × Malfunction due to short circuit occurs

[0171] <Acoustic impedance> The sound velocity c in the acoustic member was measured at 25 °C using a single-around sound velocity measuring device (UVM-2, manufactured by Ultrasonic Industry Co., Ltd.) according to the method described in JIS Z2353-2003. Next, the density ρ of the acoustic member was measured using a density measuring device (AG245, manufactured by METTLER TOLEDO). The above density measuring device calculates the density ρ of the acoustic member according to the following formula (1). In formula (1), A is the mass of the acoustic member in the air, B is the mass of the acoustic member in the substitution liquid, ρ0 is the density of the substitution liquid, and ρ L is the density of air. In this example, pure water was used as the substitution liquid. Based on the obtained sound velocity c and density ρ, the acoustic impedance Z was calculated according to the following formula (2). ρ=(A / (A-B))(ρ0-ρ L )+ρ L (1) Z=ρc (2)

[0172] <Glass transition point> Using a differential scanning calorimeter "Diamond DSC" (manufactured by PerkinElmer), 3.0 mg of the sample was sealed in an aluminum pan, and the temperature was varied in the order of heating, cooling, and heating. During the first heating, the temperature was raised from room temperature (25 °C) to 200 °C at a heating rate of 10 °C / min, and 150 °C was maintained for 5 minutes. During cooling, the temperature was lowered from 200 °C to 0 °C at a cooling rate of 10 °C / min, and the temperature of 0 °C was maintained for 5 minutes. In the measurement curve obtained during the second heating, the shift of the baseline was observed, and the intersection of the extension line of the baseline before the shift and the tangent line showing the maximum slope of the baseline shift portion was defined as the glass transition point (Tg). An empty aluminum pan was used as a reference.

[0173] 〈Overall evaluation〉 The appearance of the acoustic components was visually observed, and the overall evaluation of the sedimentation evaluation, production rate, cleavage resistance, and short-circuit resistance was performed according to the following criteria. ○ No irregularities were observed on the surface of the acoustic component, and one or fewer "X" marks were found in the evaluations of sedimentation, production speed, cleavage, and short-circuit resistance. △ Although irregularities are observed on the surface of the acoustic component, there are no quality issues, and one or fewer of the following evaluations (sedimentation evaluation, production speed, cleavage, short-circuit resistance) are marked with an "X". × The acoustic component has an undesirable degree of unevenness on its surface, or it has two or more "×" marks in the evaluation of sedimentation, production speed, cleavage, and short-circuit resistance.

[0174] [Table 1]

[0175] [Table 2]

[0176] [Table 3]

[0177] [Table 4]

[0178] In acoustic components 1-10, no particle sedimentation was observed at each pre-curing temperature, showing better results than acoustic components 11-14. This is thought to be because interference sedimentation occurred in the resin composition containing heavy and light particles, making particle sedimentation less likely. Furthermore, in experiments 1, 3-10, the overall evaluation, including the appearance of the acoustic components, was better. 50 is heavy particle d 50 This is likely because being smaller allowed for an improvement in the appearance quality of the acoustic components.

[0179] On the other hand, in acoustic member 11, the total volume filling rate of heavy and light particles is less than 10%, which is thought to be the reason why interference sedimentation between heavy and light particles was less likely to occur. In acoustic members 12 and 13, a resin composition containing only heavy particles and no light particles was used, so interference sedimentation did not occur, and the particles settled. In particular, the curing agent contained in acoustic member 13 has a high curing temperature, so it takes a long time to cure, which is thought to have made sedimentation more likely to occur before curing. Furthermore, in acoustic member 14, the specific surface area of ​​the tungsten particles contained in the resin composition is smaller than that of acoustic member 15, so the viscosity of the resin composition was lower, which is thought to have made sedimentation more likely than in acoustic member 15.

[0180] Furthermore, acoustic components 1-10 showed better results than acoustic components 14 and 15 in terms of cutability and short-circuit resistance. This is thought to be because the heavy particles were made of particles other than metal particles, which made them less prone to chipping and less conductive. [Industrial applicability]

[0181] The resin composition according to the present invention can produce a cured product in which particles are uniformly dispersed, and can improve the short-circuit resistance, cut-processability, and production efficiency of the cured product. Therefore, acoustic members cured from the above resin composition are useful, for example, in the field of ultrasound diagnostics. [Explanation of Symbols]

[0182] 10. Ultrasound diagnostic equipment 11 Main body 12 Connector section 13 displays 14 Cables 100 Ultrasonic Transducers 100a Ultrasound Probe 110 Backing material 120 Electrode terminal extraction section 130 Piezoelectric material 140 Acoustic matching layer 140a First acoustic matching layer 140b Second acoustic matching layer 140c Third Acoustic Matching Layer 140d Fourth acoustic matching layer 150 Acoustic Lenses 160a, 160b signal electrode

Claims

1. An acoustic member used in an ultrasonic transducer, comprising a cured resin composition, The aforementioned resin composition, A thermosetting resin selected from the group consisting of epoxy resins, urethane resins, and silicone resins, The thermosetting resin contains two or more types of particles dispersed in it, The two or more types of particles mentioned above are Heavy particles, which are particles other than metal particles, have a higher density than the aforementioned thermosetting resin, It includes light particles with a density lower than that of the thermosetting resin, The total content of the heavy particles and light particles relative to the total volume of the cured resin composition is 10% by volume or more. The content of the light particles is 0.3 times or more and 3 times or less by volume compared to the content of the heavy particles. The glass transition temperature of the cured product of the resin composition is 80°C or higher. The acoustic matching layer or backing material of the ultrasonic transducer, Acoustic components.

2. The light particles have a particle size (d) such that the cumulative value in the volume-based particle size distribution is 50% of that of the heavy particles. ５０ The acoustic member according to claim 1, wherein the ) is small.

3. The aforementioned heavy particles have a density of 3.5 g / cm³. ３ 7.2g / cm or more ３ The following particles: The acoustic member according to claim 1 or 2.

4. The acoustic member according to any one of claims 1 to 3, wherein the heavy particle is a particle made of an insulator or semiconductor material.

5. The heavy particles have a particle size (d) such that the cumulative value in the volume-based particle size distribution is 10%. １０ ) is 0.5 μm or larger, and the particle size (d) is such that the cumulative value is 90% ９０ The acoustic member according to any one of claims 1 to 4, comprising particles having a diameter of 22.5 μm or less.

6. The light particles are defined as having a particle size (d) such that the cumulative value in the volume-based particle size distribution is 10%. １０ ) is 0.5 μm or larger, and the particle size (d) is such that the cumulative value is 90% ９０ The acoustic member according to any one of claims 1 to 5, comprising particles whose diameter is 22.5 μm or less.

7. The acoustic member according to any one of claims 1 to 6, wherein the thickness of the cured material in the direction of ultrasonic wave propagation is 10 μm or more.

8. The acoustic member according to any one of claims 1 to 7, wherein the thickness of the cured material in the direction of ultrasonic wave propagation is 3,000 μm or less.

9. An ultrasonic transducer used in an ultrasonic probe, comprising an acoustic member as described in any one of claims 1 to 8.

10. An ultrasonic probe comprising the ultrasonic transducer described in claim 9.

11. An ultrasonic diagnostic apparatus comprising the ultrasonic probe described in claim 10.

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