JP2011072702A - Acoustic lens for ultrasonic probe, and ultrasonic probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic lens for an ultrasonic probe, having excellent acoustic characteristic and durability, and also to provide the ultrasonic probe using the lens. <P>SOLUTION: The ultrasonic probe 1 contains metal oxide particles with silica coated thereon and silicone rubber. In the probe 1, the content of the metal oxide particles is 15-50 mass.%. The ultrasonic probe 1 includes an acoustic matching layer 8 and the acoustic lens 9 for the ultrasonic probe which are arranged on piezoelectric elements having electrodes 2 and a piezoelectric material 5 on a backing material 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an acoustic lens for an ultrasonic probe used for an ultrasonic probe that transmits and receives ultrasonic waves to perform ultrasonic inspection, and an ultrasonic probe using the same, and particularly to a living body. The present invention relates to an acoustic lens for an ultrasonic probe used for an ultrasonic probe and an ultrasonic probe (ultrasonic probe) using the same.

  An ultrasonic inspection apparatus that performs an inspection using ultrasonic waves transmits ultrasonic waves to a subject, receives reflected ultrasonic waves (echoes) of the ultrasonic waves, and images the inside of the subject based on the reflected waves. It is designed to be visualized. An ultrasonic probe is used to transmit ultrasonic waves and receive reflected sound waves. An ultrasonic probe generally includes a backing material, a piezoelectric body, an acoustic matching layer, and an acoustic lens.

  The backing material absorbs unnecessary ultrasonic waves radiated to the back surface of the piezoelectric body and suppresses excessive vibration. The piezoelectric body is vibrated by an applied voltage to generate an ultrasonic wave, and has a function of receiving a vibration of the ultrasonic wave to generate a voltage corresponding to the sound pressure, and is used in a state where an electrode is added. The acoustic matching layer is a layer that has an acoustic impedance between the acoustic impedance of the subject and the acoustic impedance of the piezoelectric body and matches the acoustic impedance in order to efficiently propagate ultrasonic waves to the subject. The acoustic lens is a layer having a function of converging the ultrasonic beam.

  An ultrasonic probe is a laminated structure having a structure in which the above-described backing material, piezoelectric body, acoustic matching layer, and acoustic lens are laminated in this order, and these layers are generally integrated by adhesion. Yes. Therefore, each layer of the ultrasonic transducer member is required to have various characteristics depending on the application.

  Applications of the ultrasonic probe include a fish finder and a diagnostic device for living bodies.

Among these applications, particularly when used in a diagnostic apparatus for living bodies, it is known that the acoustic lens particularly needs to have the following characteristics because it corresponds to a portion used in close contact with the living body. It has been.
1. In order to reduce the reflection of the ultrasonic wave between the living body and the living body, the acoustic impedance is close to that of the living body.
2. In order to increase sensitivity, the water reduction rate of sonic waves is small.
3. In order to obtain a convex shape, the sound speed is equal to or lower than the sound speed in the living body.
4). In order to cope with various shapes of the acoustic lens, the moldability is high.
5). It is chemically and physically stable for medical applications that come into contact with living organisms.
6). In order to prevent deformation due to pressure at the time of contact with a living body, it has a certain hardness or more.

  The following techniques are known as comprehensively improving these characteristics.

  For example, it contains 40% by mass or more of silicone rubber and has 15 to 60% by mass of zinc oxide powder (see Patent Document 1), 40% by mass or more of silicone rubber, and 12 to 56% by mass of oxidation. One containing ytterbium powder is known (see Patent Document 2).

  In these, the use of zinc oxide powder or ytterbium oxide powder coated with a silicone resin, and an acoustic lens containing silica powder are disclosed.

  However, these acoustic lenses also improve the above-mentioned characteristics relatively, but are insufficient in durability, such as deformation and deterioration of the acoustic characteristics, especially when used repeatedly. It was difficult to achieve both.

JP 2005-125071 A JP 2009-72605 A

  An object of the present invention is to provide an acoustic lens for an ultrasonic probe having excellent acoustic characteristics and excellent durability, and an ultrasonic probe using the same.

  The above object of the present invention is achieved by the following means.

  1. An acoustic lens for an ultrasonic probe, comprising metal oxide particles coated with silica and silicone rubber.

  2. 2. The acoustic lens for an ultrasonic probe according to 1 above, wherein the content of the metal oxide particles is 15 to 50% by mass.

  3. 3. The backing material, a piezoelectric element having an electrode and a piezoelectric material provided on the backing material, an acoustic matching layer provided on the piezoelectric element, and the superstructure described in 1 or 2 provided on the acoustic matching layer An ultrasonic probe comprising an acoustic lens for an acoustic probe.

  By the above means of the present invention, an acoustic lens for an ultrasonic probe having excellent acoustic characteristics and excellent durability and an ultrasonic probe using the same can be provided.

It is a schematic sectional drawing of the example of the preferable aspect of the ultrasonic probe of this invention. It is a conceptual diagram which shows the structure of the principal part of the example of the ultrasonic image detection apparatus which comprises the ultrasonic probe of this invention. It is sectional drawing of the example of the ultrasonic probe of this invention. It is the schematic of the example of the ultrasonic image detection apparatus which comprises the ultrasonic probe of this invention. It is a figure which shows the structure of the principal part of the example of the ultrasonic image detection apparatus which comprises the ultrasonic probe of this invention.

  The present invention is an acoustic lens for an ultrasonic probe, characterized by containing silica-coated metal oxide particles and silicone rubber.

  In the present invention, an ultrasonic probe having high acoustic characteristics and excellent durability can be obtained by using an acoustic lens containing metal oxide particles coated with silica and silicone rubber.

(Acoustic lens for ultrasonic probe)
The acoustic lens for an ultrasonic probe of the present invention (hereinafter also simply referred to as an acoustic lens) contains metal oxide particles coated with silica and silicone rubber.

  Silicone rubber is a rubbery silicone resin having a plurality of siloxane bonds which are Si-O bonds.

  As the rubbery silicone resin, those having dimethylpolysiloxane as a main component are preferable, and those having a polymerization degree of 3000 to 10,000 are preferably used.

  Moreover, what further contains a silicone compound represented by the following general formula (1) is also preferably used.

General formula (1)
R ¹ (R ¹ ₂ SiO) _X (R ¹ R ² SiO) _Y SiR ¹ ₃
(R ¹ is a monovalent hydrocarbon group or hydrogen atom, R ² is an alkyl group, a polyether group, X is an integer of 0 or more, and Y is an integer of 1 or more).

  Silicone rubber can be obtained as a commercial product. For example, KE742U, KE752U, KE931U, KE941U, KE951U, KE96U, KE850U, KE555U, KE575U, etc. manufactured by Shin-Etsu Chemical Co., Ltd., TSE221-3U, TE221 -4U, TSE2233U, XE20-523-4U, TSE27-4U, TSE260-3U, TSE-260-4U, SH35U, SH55UA, SH831U, SE6749U, SE1120USE4704U manufactured by Dow Corning Toray can be used.

  As content of silicone rubber, it is preferable that it is 40 mass% or more with respect to an acoustic lens, and it is especially preferable from a surface of acoustic characteristics and durability that it is 40-80 mass%.

(Metal oxide particles coated with silica (hereinafter simply referred to as silica-coated metal oxide particles))
In the present invention, the silica-coated metal oxide particles are metal oxide particles having silica on the surface thereof. Examples of the metal oxide used for the silica-coated metal oxide particles include TiO ₂ , SnO ₂ , ZnO, Bi ₂ O ₃ , WO ₃ , ZrO ₂ , Fe ₂ O ₃ , MnO ₂ , Y ₂ O ₃ , MgO, BaO. , Yb ₂ O ₃ . Among these, ZnO, TiO ₂ , and Fe ₂ O ₃ are preferably used from the viewpoint of acoustic characteristics.

  Silica-coated metal oxide particles are obtained by bringing these metal oxide particles into contact with a silica film-forming composition containing silicic acid, water, alkali and an organic solvent, and selectively depositing silica on the surface of the metal oxide. It can be obtained by crushing. In order to deposit selectively, it is preferable that the water / organic solvent ratio is in the range of 0.1 to 10 by volume and the silicon concentration is in the range of 0.0001 to 5 mol / liter.

  The average particle diameter of the silica-coated metal oxide particles is preferably 1 to 200 nm, and particularly preferably 5 to 20 nm. The average particle diameter is a value obtained by measuring the particle diameter for 100 particles and calculating the number average of these values. The particle diameter is an average value of the maximum diameter and the minimum diameter of the particles obtained from an image obtained by electron microscope observation.

  The thickness of the silica coating of the silica-coated metal oxide particles is preferably from 0.1 to 100 nm, and particularly preferably from 1 to 25 nm.

  The content of the silica-coated metal oxide particles is preferably 10 to 60% by mass and particularly preferably 15 to 50% by mass from the viewpoint of acoustic characteristics.

  Silica-coated metal oxide particles can be obtained as commercial products, and Maxlite ZS-64 (silica-coated zinc oxide) manufactured by Showa Denko KK, Maxlite TS-043 (Silica-coated oxide manufactured by Showa Denko KK). Titanium) or the like can be used.

  An acoustic lens for an ultrasonic probe is a molded product having the shape of an acoustic lens by mixing and kneading silicone rubber and silica-coated oxide particles, adding a vulcanizing agent to the kneaded product, and performing vulcanization molding. Further, it is prepared by performing two vulcanizations as necessary. As the vulcanizing agent, for example, a peroxide-based vulcanizing agent such as 2,5-dimethyl-2,5-ditertiary butyl peroxyhexane, p-methylbenzoyl peroxide, ditertiary butyl peroxide may be used. it can. The amount of the peroxide-based vulcanizing agent is preferably 0.3 to 2% by mass with respect to the silicone rubber in the acoustic lens composition, for example. Further, a vulcanizing agent other than the peroxide-based vulcanizing agent may be used.

  When the silicone rubber and the silica-coated oxide particles are mixed, it is preferable to remove moisture from the metal oxide particles by heating or the like. The temperature for vulcanization molding is preferably in the range of 100 to 200 ° C.

  The acoustic lens for an ultrasonic probe of the present invention may contain silica powder as long as the effects of the present invention are not impaired. As content of the silica powder contained, it is preferable that it is 20 mass% or less with respect to an acoustic lens. Moreover, you may contain the following additives in the range of about 5 mass% or less. For example, titanium oxide, alumina, cerium oxide, iron oxide, barium sulfate, organic fillers, coloring pigments, and the like can be given.

  The reason why the above configuration of the present invention exhibits high acoustic characteristics and excellent durability is not clear, but is presumed as follows. Dispersed silica-coated metal oxide particles have a high affinity for silicone rubber, so the adhesion between the silicone rubber and the particles is large. It is presumed that the deterioration does not occur, the external force is prevented from being concentrated locally, and the external force is dispersed and absorbed in the acoustic lens.

(Ultrasonic probe)
The ultrasonic probe of the present invention includes a backing layer, a piezoelectric element having an electrode and a piezoelectric body provided on the backing layer, an acoustic matching layer provided on the piezoelectric element, and provided on the acoustic matching layer. And an acoustic lens for an ultrasonic probe according to the present invention.

  FIG. 1 shows a schematic cross-sectional view of an example of a preferred embodiment of the ultrasonic probe of the present invention.

  The ultrasonic probe 1 has a transmission piezoelectric element 12 in which an electrode 2 is attached to a transmission piezoelectric material 5 on a backing layer 6, and has an intermediate layer 7 on the transmission piezoelectric element 12. The receiving piezoelectric element 13 having the electrode 2 attached to the receiving piezoelectric material 11 is provided on the layer 7, and the acoustic matching layer 8 and the acoustic lens 9 are further provided thereon.

(Backing layer)
The backing layer is an ultrasonic absorber that supports the piezoelectric element and can absorb unnecessary ultrasonic waves. The backing material used for the backing layer is natural rubber, ferrite rubber, a material obtained by press molding powders of tungsten oxide, titanium oxide, ferrite, etc. into epoxy resin, vinyl chloride, polyvinyl butyral (PVB), ABS resin, polyurethane (PUR), polyvinyl alcohol (PVAL), polyethylene (PE), polypropylene (PP), polyacetal (POM), polyethylene terephthalate (PET), fluororesin (PTFE) polyethylene glycol, polyethylene terephthalate-polyethylene glycol copolymer, etc. A plastic resin or the like can be used.

  A preferable backing material is made of a rubber-based composite material and / or an epoxy resin composite material, and the shape thereof can be appropriately selected according to the shape of the piezoelectric body or the probe head including the piezoelectric body.

  As the rubber-based composite material, a material containing a rubber component and a filler is preferable. A hardness from A70 in a spring hardness tester (durometer hardness) according to JIS K6253 to D70 in a type D durometer. In addition, various other compounding agents can be added as necessary. Examples of rubber components include ethylene propylene rubber (EPDM or EPM), hydrogenated nitrile rubber (HNBR), chloroprene rubber (CR), silicone rubber, EPDM and HNBR blend rubber, and EPDM and nitrile rubber (NBR) blend rubber. NBR and / or HNBR and high styrene rubber (HSR) blend rubber, EPDM and HSR blend rubber, and the like are preferable. More preferably, ethylene propylene rubber (EPDM or EPM), hydrogenated nitrile rubber (HNBR), EPDM and HNBR blend rubber, EPDM and nitrile rubber (NBR) blend rubber, NBR and / or HNBR and high styrene rubber (HSR) ) Blend rubber, EPDM and HSR blend rubber, and the like. As the rubber component of the present invention, one of rubber components such as vulcanized rubber and thermoplastic elastomer may be used alone, but a blend rubber obtained by blending two or more rubber components such as a blend rubber is used. Also good.

  The filler to be added to the rubber component can be selected in various forms together with the blending amount from those usually used to those having a large specific gravity. For example, zinc oxide, white titanium, bengara, ferrite, alumina, tungsten trioxide, yttrium oxide and other metal oxides, calcium carbonate, hard clay, diatomaceous earth clays, calcium carbonate, barium sulfate and other metal salts, glass Examples include powders, various fine metal powders such as tungsten and molybdenum, and various balloons such as glass balloons and polymer balloons. These fillers can be added at various ratios, preferably 50 to 3000 parts by weight, more preferably about 100 to 2000 parts by weight, or about 300 to 1500 parts by weight with respect to 100 parts by weight of the rubber component. preferable. These fillers may be added alone or in combination of two or more.

  Other compounding agents can be added to the rubber-based composite material as necessary. Examples of such compounding agents include vulcanizing agents, cross-linking agents, curing agents, auxiliaries, and deterioration inhibitors. , Antioxidants, colorants and the like. For example, carbon black, silicon dioxide, process oil, sulfur (vulcanizing agent), dicumyl peroxide (Dicup, crosslinking agent), stearic acid and the like can be blended. These compounding agents are used as necessary, but the amount used is generally about 1 to 100 parts by mass with respect to 100 parts by mass of the rubber component, but may be appropriately changed depending on the overall balance and characteristics. You can also.

  As an epoxy resin composite agent, it is preferable to contain an epoxy resin component and a filler, and various compounding agents can be added as necessary. The epoxy resin component includes, for example, bisphenol A type, bisphenol F type, resol novolak type, novolac type epoxy resin such as phenol-modified novolak type, naphthalene structure-containing type, anthracene structure-containing type, fluorene structure-containing type, etc. Type epoxy resin, hydrogenated alicyclic epoxy resin, liquid crystalline epoxy resin and the like. Although the epoxy resin component of this invention may be used independently, you may mix and use two or more types of epoxy resin components like a blend resin.

  As the filler added to the epoxy component, any of those similar to the filler mixed with the rubber component to composite particles prepared by pulverizing the rubber-based composite agent can be preferably used. Examples of the composite particles include particles in which silicone rubber is filled with ferrite and pulverized with a pulverizer to a particle size of about 200 μm.

  When using an epoxy resin composite agent, it is necessary to add a crosslinking agent, for example, a chain aliphatic polyamine such as diethylenetriamine, triethylenetetramine, dipropylenediamine, diethylaminopropylamine, N-aminoethylpiperazine, Cycloaliphatic polyamines such as mensendiamine, isophoronediamine, aromatic amines such as m-xylenediamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, polyamide resin, piperidine, NN-dimethylpiperazine, triethylenediamine, 2, Secondary and tertiary amines such as 4,6-tris (dimethylaminomethyl) phenol, benzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2-methylimidazole, 2-ethylimid Sols, imidazoles such as 1-cyanoethyl-2-undecylimidazolium trimellitate, liquid polymercaptan, polysulfide, phthalic anhydride, negligible trimellitic acid, methyltetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, methylbutyrate Examples of the acid anhydride include tenenyltetrahydrophthalic anhydride and methylhexahydrophthalic acid.

  The thickness of the backing material is preferably about 1 to 10 mm, particularly preferably 1 to 5 mm.

(Piezoelectric element)
The piezoelectric element according to the present invention has an electrode and a piezoelectric material, and is an element capable of converting an electrical signal into mechanical vibration and converting mechanical vibration into an electrical signal and transmitting and receiving ultrasonic waves. The piezoelectric material is a material containing a piezoelectric body capable of converting an electrical signal into mechanical vibration and converting mechanical vibration into an electrical signal. As the piezoelectric body, it is possible to use piezoelectric ceramics such as lead zirconate titanate (PZT) ceramics and PbTiO ₃ ceramics, organic polymer piezoelectric materials such as polyvinylidene fluoride (PVDF), crystal, and Rochelle salt. The thickness of the piezoelectric material is generally in the range of 100 μm to 500 μm. Piezoelectric material is used as a piezoelectric element with electrodes on both sides.

(electrode)
Materials used for electrodes applied to piezoelectric materials include gold (Au), platinum (Pt), silver (Ag), palladium (Pd), copper (Cu), aluminum (Al), nickel (Ni), tin (Sn) etc. are mentioned.

  As a method for attaching an electrode to a piezoelectric material, for example, a base metal such as titanium (Ti) or chromium (Cr) is formed to a thickness of 0.02 to 1.0 μm by sputtering, and then the above metal element is mainly used. Examples thereof include a method of forming a metal material composed of a metal to be used and an alloy thereof, and further forming a part of an insulating material to a thickness of 1 to 10 μm by a sputtering method or other appropriate methods as necessary.

  Electrodes can be formed by screen printing, dipping, or thermal spraying using a conductive paste in which fine metal powder and low-melting glass are mixed, as well as sputtering. The electrode is provided on the entire surface of the piezoelectric body or a part of the piezoelectric body surface on the piezoelectric material according to the shape of the probe.

  It is a preferable aspect that the piezoelectric element and the backing material are laminated via an adhesive layer. As an adhesive for forming the adhesive layer, an epoxy-based adhesive can be used.

  An electrode is in contact with a part of the surface on the backing material side of the piezoelectric element and a part of the surface on the acoustic matching layer side, and includes a part where the backing material and the electrode are laminated via the adhesive layer 11. In some cases.

(Acoustic matching layer)
The acoustic matching layer according to the present invention matches the acoustic impedance between the piezoelectric element and the subject and is made of a material having an acoustic impedance intermediate between the piezoelectric element and the subject. Materials used for the acoustic matching layer include aluminum, aluminum alloy (for example, AL-Mg alloy), magnesium alloy, macor glass, glass, fused quartz, copper graphite, polyethylene (PE), polypropylene (PP), and polycarbonate (PC). , ABC resin, polyphenylene ether (PPE), ABS resin, AAS resin, AES resin, nylon (PA6, PA6-6), PPO (polyphenylene oxide), PPS (polyphenylene sulfide: glass fiber can be included), PPE (polyphenylene ether) ), PEEK (polyetheretherketone), PAI (polyamideimide), PETP (polyethylene terephthalate), PC (polycarbonate), epoxy resin, urethane resin, etc., preferably epoxy Zinc oxide as a filler in the thermosetting resin butter, and the like, titanium oxide, silica, alumina, iron oxide, ferrite, tungsten oxide, ytterbium, can be used after molded put barium sulfate, tungsten, molybdenum or the like.

  The acoustic matching layer may be a single layer or a plurality of layers, but preferably has two or more layers. The layer thickness of the acoustic matching layer needs to be determined to be λ / 4 where λ is the wavelength of the ultrasonic wave. If this is not satisfied, a plurality of unnecessary spurious noises appear at frequency points different from the original resonance frequency, and the basic acoustic characteristics greatly vary. As a result, reverberation time increases and sensitivity and S / N decrease due to waveform distortion of the reflected echo are undesirable. The thickness of such an acoustic matching layer is generally in the range of 30 μm to 500 μm.

  In the ultrasonic probe of the present invention, both transmission and reception of ultrasonic waves may be performed by a single piezoelectric element, but a piezoelectric element including a transmitting piezoelectric element and a receiving piezoelectric element is preferably used. It is done. The arrangement of the transmitting piezoelectric element and the receiving piezoelectric element may be either an arrangement in which the piezoelectric elements are arranged in the vertical direction or an arrangement in which the piezoelectric elements are arranged in parallel with each other.

  The thickness of the piezoelectric element for transmission and the piezoelectric element for reception in the case of lamination is preferably 40 to 150 μm.

  The ultrasonic probe of the present invention can be used for various types of ultrasonic image detection devices. FIG. 2 is a conceptual diagram showing the configuration of the main part of an example of an ultrasonic image detection apparatus including the ultrasonic probe of the present invention.

  For example, the ultrasonic image detection apparatus transmits an ultrasonic wave to a subject such as a living body, and an ultrasonic probe (probe) in which piezoelectric elements that receive ultrasonic waves reflected by the subject as echo signals are arranged. ). In addition, an electric signal is supplied to the ultrasonic probe to generate an ultrasonic wave, and a transmission / reception circuit that receives an echo signal received by each piezoelectric element of the ultrasonic probe and transmission / reception control of the transmission / reception circuit are performed. A transmission / reception control circuit is provided.

  Furthermore, an image data conversion circuit that converts echo signals received by the transmission / reception circuit into ultrasonic image data of the subject is provided. Further, a display control circuit for controlling and displaying a monitor with the ultrasonic image data converted by the image data conversion circuit and a control circuit for controlling the entire ultrasonic image detection apparatus are provided.

  A transmission / reception control circuit, an image data conversion circuit, and a display control circuit are connected to the control circuit, and the control circuit controls operations of these units. Then, an electrical signal is applied to each piezoelectric material of the ultrasonic probe, ultrasonic waves are transmitted to the subject, and reflected waves generated by acoustic impedance mismatch inside the subject are received by the ultrasonic probe. To do.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. In the examples, “parts” represents “parts by mass” unless otherwise specified.

Example 1
(Preparation of sheets 1-7)
Moisture adhering to ZnO particles coated with silica with an average particle size of 30 nm (ZS-64, manufactured by Showa Denko KK) thinly on a stainless steel pad, placed in a high temperature bath at 140 ° C. and dried for 4 hours. Etc. were evaporated.

  At this time, the mass was reduced by 0.4% by mass before and after drying.

  100 parts by mass of dimethylpolysiloxane (silicone rubber-1) having a viscosity of 530 cSt and a vinyl group content of 0.2 mol%, both ends of molecular chain being blocked with dimethylvinylsilyl groups as silicone rubber, organopolysiloxane 20 parts by mass and 65 parts by mass of ZnO particles coated with the sufficiently dried silica were mixed and kneaded using a 6-inch double roll kneader to prepare rubber composition-1.

  Next, 100 parts by mass of this rubber composition-1 is roll-mixed with 0.5 parts by mass of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a vulcanizing agent to form a molding compound. The molding compound-1 was press-molded at 165 ° C. for 10 minutes, and further subjected to secondary vulcanization at 200 ° C. for 2 hours to produce a sheet 1. In addition, as thickness of the sheet | seat 1, the thing of 1 mm, 2 mm, and 3 mm was produced, respectively, in order to use for the below-mentioned measurement.

  In the following manner, the value of the acoustic impedance and the attenuation factor were measured and used as an index for evaluating the acoustic characteristics.

  The density of the sheet 1 at 25 ° C. is obtained according to JIS, C-2123, and the sound velocity at 25 ° C. of the sheet 1 is measured with a sound velocity measuring device / sing-around type sound velocity measuring device UVM-2 type [trade name, manufactured by Ultrasonic Industries, Ltd.]. The sheet was measured at a measurement frequency of 5 MHz, and the acoustic impedance of the sheet was determined from this product.

  Further, the sheet 1 is filled with water at 25 ° C. in a water tank, and ultrasonic waves of 15 MHz are generated in water by an ultrasonic pulser / receiver JPR-10C [manufactured by Japan Probe Co., Ltd.] before and after the ultrasonic waves permeate the sheet. When the magnitude of the amplitude of was measured, the amount of ultrasonic attenuation in water at 25 ° C. was −6 db / mm.

  The acoustic impedance is generally 1.20 MRayls or more, and the ultrasonic attenuation is 14 db / mm or less in a practically satisfactory range.

  Similarly, silicone rubber, particles to be added, and the contents of each were listed in Table 1 to prepare sheets 2 to 7, and the same evaluation was performed.

(Production of sheet comparison 1 to comparison 4)
Example 1 silicone rubber-1, which is the same base as in Example 1, 20 parts by mass of organopolysiloxane-1 in 100 parts by mass, 31 parts by mass of fumed silica, and 65 parts by mass of quartz powder having an average particle diameter of 1.4 μm In the same manner as in Example 1, Sheet Comparison 1 was produced.

  The specific gravity was 1.40, the acoustic impedance was 1.41 MRayls, and the ultrasonic attenuation was -19 db / mm.

  In the production of the sheet 1, a sheet comparison 2 was produced in the same manner as the sheet 1 except that No. 1 zinc white (0.4 μm) was used instead of ZS-64.

  In the production of the sheet 1, a sheet comparison 3 was produced in the same manner as the sheet 1 except that zinc oxide particles (FINEX-30, manufactured by Sakai Chemical Co., Ltd.) were used instead of ZS-64.

In the production of the sheet 1, a sheet comparison 4 was produced in the same manner as the sheet 1 except that instead of ZS-64, a silicone resin-coated Yb ₂ O ₃ (ytterbium oxide described in JP2009-72605A) was used. did.

(Durability evaluation)
As described below, the hardness of the acoustic lens was measured, and an aging test was performed, which was used as an index of durability.

(Hardness strength change, aging test)
For the sheets 1 to 7 and comparisons 1 to 4, the hardness was measured according to JIS K6253.

  Next, the aging conditions were 230 ° C. for 24 hours, the hardness after aging was measured, the change in rubber strength was expressed as a relative value when the hardness before aging was 100, and the results are shown in Table 1.

  With respect to the sheets 1 to 7 and the comparisons 1 to 4, the rubber aging test was evaluated according to the method described in JIS K6257. Shown as a relative value when pre-aging is 100.

  The aging condition was 230 ° C. for 24 hours. For rubber hardness and aging test, 103 or less is a practically good range.

  The measurement results are shown in Table 1.

  From Table 1, it can be seen that the acoustic lens of the present invention maintains excellent acoustic characteristics and is excellent in durability.

Example 2
(Production of ultrasonic probe)
(Production of receiving piezoelectric element)
As the piezoelectric material, a polyvinylidene fluoride film was used, and aluminum electrodes were applied to both surfaces of the film by vapor deposition. A high voltage power supply device HARb-20R60 (manufactured by Matsusada Precision Co., Ltd.) and a needle electrode were used, and 2.0 MV / Corona discharge polarization treatment was performed in an electric field of m to produce a receiving piezoelectric element.

(Production of transmitting piezoelectric element)
Component raw materials CaCO ₃ , La ₂ O ₃ , Bi ₂ O ₃ and TiO ₂ , and subcomponent raw materials MnO are prepared, and for the component raw materials, the final composition of the components is (Ca _0.97 La _0.03 ) Weighed to be Bi _4.01 Ti ₄ O ₁₅ .

  Next, pure water was added, mixed in a ball mill containing zirconia media in pure water for 8 hours, and sufficiently dried to obtain a mixed powder. The obtained mixed powder was temporarily molded and calcined in air at 800 ° C. for 2 hours to prepare a calcined product. Next, pure water was added to the obtained calcined material, finely pulverized in a ball mill containing zirconia media in pure water, and dried to prepare a piezoelectric ceramic raw material powder. In the fine pulverization, the piezoelectric ceramic raw material powder having a particle diameter of 100 nm was obtained by changing the pulverization time and pulverization conditions. 6% by mass of pure water as a binder is added to each piezoelectric ceramic raw material powder having a different particle diameter, press-molded to form a plate-shaped temporary molded body having a thickness of 100 μm, and this plate-shaped temporary molded body is vacuum-packed and then 235 MPa. It shape | molded by the press with the pressure of. Next, the molded body was fired. The final sintered body had a thickness of 20 μm. The firing temperature was 1100 ° C., respectively. An electric field of 1.5 × Ec (MV / m) or more was applied for 1 minute to perform polarization treatment, and a transmitting piezoelectric element was produced.

(Ultrasonic probe)
Next, according to a conventional method, as shown in FIG. 3, a backing layer 6, a transmission flexible substrate 15, the transmission piezoelectric element 12, the intermediate layer 7, a reception piezoelectric element 13, a reception flexible substrate 16, and an acoustic matching layer are provided. The layers were stacked in the order of 8. Note that a ferrite rubber having a thickness of 3 mm was used as the backing layer. As the intermediate layer, a layer having a thickness of 0.145 mm obtained by mixing 1200 parts by mass of ferrite with 100 parts by mass of the epoxy resin was used, and as the acoustic matching layer, a layer having an epoxy resin thickness of 0.110 mm was used. These were laminated and each element was diced with a dicer. Furthermore, the acoustic lens 9 was molded by press molding Compound 1 produced in the same manner as in Example 1 under the same conditions using a mold. The acoustic lens 9 produced in this manner was laminated on the acoustic matching layer 8 to produce the ultrasonic probe 1 shown in FIG.

  Using this, an image of a living body was observed by the ultrasonic image detection apparatus having the configuration shown in FIGS. 4 and 5. As a result, a clear image could be obtained.

DESCRIPTION OF SYMBOLS 1 Ultrasonic probe 2 Electrode 5 Transmission piezoelectric material 6 Backing layer 7 Intermediate layer 8 Acoustic matching layer 9 Acoustic lens 10 Ultrasonic transducer 11 Reception piezoelectric material 12 Transmission piezoelectric element 13 Reception piezoelectric element 15 Transmission flexible Base 16 Receiving flexible base 31 Ultrasonic image display device 33 Cable 41 Operation input unit 42 Transmission circuit 43 Reception circuit 44 Image processing unit 45 Display unit 46 Control unit 100 Ultrasonic image detection device

Claims (3)

  An acoustic lens for an ultrasonic probe, comprising metal oxide particles coated with silica and silicone rubber.   The acoustic lens for an ultrasonic probe according to claim 1, wherein the content of the metal oxide particles is 15 to 50% by mass.   The backing material, a piezoelectric element having an electrode and a piezoelectric material provided on the backing material, an acoustic matching layer provided on the piezoelectric element, and the acoustic matching layer provided on the acoustic matching layer. An ultrasonic probe comprising an acoustic lens for an ultrasonic probe.

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