JP2010182994A - Organic piezoelectric element, ultrasonic vibrator, and ultrasonic probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic piezoelectric material for forming an ultrasonic vibrator suited for high frequency and broad band, to provide an ultrasonic vibrator using the same, and to provide an ultrasonic probe using the same. <P>SOLUTION: The organic piezoelectric material is used for an ultrasonic vibrator with an electrode formed on the surface of the organic piezoelectric material, wherein the organic piezoelectric material contains a material which can form a covalent bond with the electrode metal of electrode and in addition, the material which can form a covalent bond with the electrode metal is covalently bonded with the electrode metal. From the organic piezoelectric material, an ultrasonic vibrator can be obtained that can give excellent adhesive strength easily without involving a complicated process like surface processing, and excellent adhesion with the electrode metal, excellent resistance against electrode separation due to friction during the operation, good prevention of peeling which may be caused even by weak friction during processing, excellent processability, and excellent piezoelectricity, and the ultrasonic probe using the ultrasonic vibrator can be made as well. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic piezoelectric material for constructing an ultrasonic transducer suitable for a high frequency and a wide band, an ultrasonic transducer using the organic piezoelectric material, and an ultrasonic probe using the organic piezoelectric material.

  Ultrasound is generally referred to as a sound wave of 16 kHz or higher, and can be examined non-destructively and harmlessly, so that it is applied to various fields such as defect inspection and disease diagnosis. . For example, an ultrasonic diagnosis that scans the inside of a subject with ultrasound and images the internal state of the subject based on a reception signal generated from a reflected wave (echo) of the ultrasound from the inside of the subject. There is a device. In this ultrasonic diagnostic apparatus, an ultrasonic probe that transmits and receives ultrasonic waves to and from a subject is used. As this ultrasonic probe, a transducer that generates a received signal by receiving a reflected wave of an ultrasonic wave generated by a difference in acoustic impedance inside a subject is generated by mechanical vibration based on a transmission signal. An ultrasonic transmitting / receiving element configured to be provided is used.

  In recent years, harmonic imaging that forms an image of the internal state in the subject using the harmonic frequency component, not the frequency (fundamental frequency) component of the ultrasound transmitted from the ultrasound probe into the subject ( (Harmonic Imaging) technology is being researched and developed. In this harmonic imaging technique, (1) the side lobe level is smaller than the fundamental frequency component level, the S / N ratio (signal to noise ratio) is improved, and the contrast resolution is improved. Increasing the beam width narrows and the lateral resolution is improved. (3) Since the sound pressure is small and the fluctuation of the sound pressure is small at a short distance, multiple reflections are suppressed. (4) Focus It has various advantages such as a greater depth speed compared to the case where the further attenuation is the same as the fundamental wave and the high frequency is the fundamental wave.

  This ultrasonic probe for harmonic imaging requires a wide frequency band from the frequency of the fundamental wave to the frequency of the harmonic, and its lower frequency range is used for transmission to transmit the fundamental wave. Is done. On the other hand, the frequency region on the high frequency side is used for reception for receiving harmonics (see, for example, Patent Document 1).

  The ultrasonic probe disclosed in Patent Document 1 receives an ultrasonic wave that is applied to a subject, transmits an ultrasonic wave into the subject, and is reflected and returned within the subject. It is an acoustic probe. The ultrasonic probe transmits a fundamental wave composed of ultrasonic waves having a predetermined center frequency, which is composed of a plurality of arranged first piezoelectric elements having a predetermined first acoustic impedance, into the subject. , And a first piezoelectric layer responsible for receiving the fundamental wave of the ultrasonic waves reflected back within the subject. Further, a higher harmonic wave of ultrasonic waves reflected and returned from the subject, which includes a plurality of second piezoelectric elements arranged with a predetermined second acoustic impedance smaller than the first acoustic impedance. A second piezoelectric layer responsible for receiving waves is provided. The second piezoelectric layer is overlaid on the entire surface of the first piezoelectric layer on the side where the ultrasonic probe is applied to the subject. Therefore, the ultrasonic probe can transmit and receive ultrasonic waves in a wide frequency band with such a configuration.

The fundamental wave in harmonic imaging is preferably a sound wave having the narrowest possible bandwidth. The piezoelectric element responsible for this is a so-called polarization treatment of a single crystal such as quartz, LiNbO ₃ , LiTaO ₃ , KNbO ₃ , a thin film such as ZnO or AlN, or a sintered body such as Pb (Zr, Ti) O _3. Ceramic inorganic piezoelectric materials are widely used. Piezoelectric elements that detect received waves on the high frequency side require a wider bandwidth sensitivity, and these inorganic materials are not suitable. As a piezoelectric element suitable for a high frequency and a wide band, an organic piezoelectric body using an organic polymer material such as polyvinylidene fluoride (hereinafter also abbreviated as “PVDF”) is known (see, for example, Patent Document 2). Compared to inorganic piezoelectric materials, this organic piezoelectric material has greater flexibility, and can be made into any shape and form, making it easier to reduce the thickness, area, and length. Have.

  As the surface electrode formed on the organic piezoelectric body, various metals (including alloys) can be used as long as the material has excellent conductivity. The surface electrode material prepared in a film shape can be bonded to the piezoelectric material, and the surface electrode can be formed and bonded to the piezoelectric material by forming the film surface electrode on the surface of the piezoelectric material. It can be done at the same time. The surface electrode is formed by an electroless plating method, a sputtering method, or a vapor deposition method capable of simultaneously forming the surface electrode itself and bonding it to the piezoelectric material.

  However, it is known that a piezoelectric body mainly composed of polyvinylidene fluoride has a very weak adhesion to the electrode metal, and the electrode is peeled off during operation to cause peeling even when the friction is weak. It is difficult to process, and when a vibrator containing an organic piezoelectric material is cut into a plurality of vibrators of an appropriate shape using a device such as a dicing saw, There has been a problem that peeling is likely to occur when a vibration is applied by applying a voltage due to the piezoelectric effect.

  When applying an electrode to the organic piezoelectric material, complicated processes such as oxidizing the surface of the organic piezoelectric material or applying a coupling agent to form a layer (for example, refer to Patent Document 3) are required to improve adhesion. Proposed. There are a method in which a conductive adhesive is applied to both surfaces of the piezoelectric body and the electrode is adhered, and a method in which a silver paste is directly applied to the surface of the piezoelectric body as an electrode, but the adhesive strength is weak and the impact is weak.

  There has been a demand for an improved method for easily obtaining excellent adhesive strength without going through complicated steps such as surface treatment.

Japanese Patent Laid-Open No. 11-276478 Japanese Patent Application Laid-Open No. 60-217674 Japanese Patent Application Laid-Open No. 5-42674

  The present invention has been made in view of the above problems, and an object of the present invention is to solve the above problems and easily obtain excellent adhesive strength without going through complicated steps such as surface treatment. Excellent adhesion to the electrode, excellent resistance to electrode peeling due to friction during operation, excellent suppression of delamination generation even with weak friction during processing, excellent workability, excellent piezoelectricity, high frequency and wide bandwidth An organic piezoelectric material for forming a suitable ultrasonic transducer, an ultrasonic transducer using the organic piezoelectric material, and an ultrasonic probe using the organic piezoelectric material.

  The above object of the present invention can be achieved by the following constitution.

  1. An organic piezoelectric material used in an ultrasonic vibrator having an electrode formed on the surface of an organic piezoelectric material, wherein the organic piezoelectric material contains a material capable of forming a covalent bond with the electrode metal of the electrode, and the electrode metal An organic piezoelectric material, wherein a material capable of forming a covalent bond with the electrode metal is covalently bonded to the electrode metal.

  2. 2. The organic piezoelectric material according to 1 above, containing 0.01 to 5% by mass of a material capable of forming a covalent bond with the electrode metal.

  3. The organic piezoelectric material comprises polyvinylidene fluoride, a polymer of vinylidene fluoride and trifluoroethylene, a polymer of vinylidene fluoride, trifluoroethylene, and monofluoroethylene, and vinylidene fluoride, trifluoroethylene, and methyl methacrylate. Said 1 characterized in that it is at least one selected from polymers, polymers of vinylidene fluoride, trifluoroethylene and vinyl acetate, cellulosic derivatives, and polyurea polymers and polymer copolymers. Or the organic piezoelectric material of 2.

  4). 4. The organic piezoelectric material as described in 3 above, wherein the organic piezoelectric material contains vinylidene fluoride as a main component.

  5. 5. The organic piezoelectric material according to any one of 1 to 4, wherein the material capable of forming a covalent bond with the electrode metal includes a mercapto group as a functional group.

  6). The material capable of forming a covalent bond with the electrode metal is a mercapto compound represented by the following general formula (I), or at least one selected from 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane. 6. The organic piezoelectric material according to any one of 1 to 5, which is a mercapto-based silane coupling agent.

  7). Any one of the above 1 to 6, wherein the electrode metal is a metal of Al, Zn, Fe, Ni, Cr, Sn, Cu, Ag, or Au, or an alloy containing the metal as a main component. 2. The organic piezoelectric material according to item 1.

  8). 8. The organic piezoelectric material as described in 7 above, wherein the electrode metal is a metal or alloy containing Au as a main component.

  9. An ultrasonic vibrator using the organic piezoelectric material according to any one of 1 to 8 above.

  10. An ultrasonic probe comprising an ultrasonic transmission transducer and an ultrasonic reception transducer, wherein the ultrasonic transducer described in the above item 9 is used as an ultrasonic reception transducer. Sonic probe.

  According to the present invention, excellent adhesive strength can be easily obtained without complicated processes such as surface treatment, excellent adhesion to electrode metal, excellent resistance to electrode peeling due to friction during operation, and processing. Organic piezoelectric material for forming an ultrasonic transducer suitable for high-frequency and broadband, excellent in suppressing the generation of delamination even when weak friction is performed, excellent in workability, excellent in piezoelectricity, and using this An ultrasonic transducer and an ultrasonic probe using the same can be provided.

  Hereinafter, although the best mode for carrying out the present invention will be described, the present invention is not limited to these.

  The present invention relates to an organic piezoelectric material used for an organic piezoelectric material and an ultrasonic vibrator formed by forming an electrode on the surface thereof, and a material capable of forming a covalent bond with an electrode metal of the electrode on the organic piezoelectric material. It is characterized by containing.

  In the present invention, in particular, by including a material capable of forming a covalent bond with the electrode metal of the electrode in the organic piezoelectric material, excellent adhesive strength can be easily obtained without going through complicated steps such as surface treatment. Excellent adhesion to electrode metal, excellent resistance to electrode peeling due to friction during operation, excellent suppression of delamination due to weak friction during processing, excellent workability, excellent piezoelectricity, high frequency -An organic piezoelectric material for forming an ultrasonic transducer suitable for a wide band can be obtained.

  The present invention will be described in more detail.

(Organic piezoelectric material)
The organic piezoelectric material of the present invention can be employed regardless of whether it is a low-molecular material or a high-molecular material. Compound etc. are mentioned. If it is a polymer organic piezoelectric material, for example, polyvinylidene fluoride, a polymer of vinylidene fluoride and trifluoroethylene, a polymer of vinylidene fluoride, trifluoroethylene, and monofluoroethylene (also referred to as vinyl fluoride), Polymers of vinylidene fluoride, trifluoroethylene, and methyl methacrylate, polymers of vinylidene fluoride, trifluoroethylene, and vinyl acetate, or odd-numbered nylons such as nylon 9 and nylon 11, aromatic nylon, and alicyclic Examples thereof include nylon (registered trademark) such as nylon, polyhydroxycarboxylic acid such as polylactic acid, polyhydroxybutyrate, cellulose derivatives, polyurea polymers, polymer copolymers, and the like.

  The organic piezoelectric material is preferably a polymer organic piezoelectric material, particularly a polymer material mainly composed of vinylidene fluoride, from the viewpoint of good piezoelectric properties, processability, availability, and the like.

Specifically, it is preferably a homopolymer of polyvinylidene fluoride having a CF ₂ group having a large dipole moment or a copolymer having vinylidene fluoride as a main component. In addition, tetrafluoroethylene, trifluoroethylene, hexafluoropropane, chlorofluoroethylene, etc. can be used as the second component in the copolymer.

  For example, in the case of vinylidene fluoride / trifluoride ethylene copolymer, since the electromechanical coupling constant (piezoelectric effect) in the thickness direction varies depending on the copolymerization ratio, the former copolymerization ratio is 60 to 99 mol%. It is preferable that it is 85-99 mol%.

  A polymer containing 85 to 99 mol% of vinylidene fluoride and 1 to 15 mol% of perfluoroalkyl vinyl ether, perfluoroalkoxyethylene, perfluorohexaethylene, etc. is composed of an inorganic piezoelectric element for transmission and an organic piezoelectric element for reception. In combination with the element, it is possible to suppress the transmission fundamental wave and increase the sensitivity of harmonic reception.

  Since the organic piezoelectric material can be made thinner than an inorganic piezoelectric material made of ceramics, it can be made into a vibrator corresponding to transmission and reception of higher frequencies.

The organic piezoelectric material of the present invention preferably has a relative dielectric constant of 10 to 50 at the thickness resonance frequency. The relative dielectric constant can be adjusted by adjusting the number, composition, polymerization degree, etc. of polar functional groups such as CF ₂ groups and CN groups contained in the compound constituting the organic piezoelectric material, and polarization treatment described later.

  In general, the organic piezoelectric material is used as an organic piezoelectric material film in a vibrator. However, the organic piezoelectric material film of the present invention can be configured by laminating a plurality of polymer materials. In this case, as the polymer material to be laminated, in addition to the above polymer material, the following polymer material having a relatively low relative dielectric constant can be used in combination (in the following examples, the numerical values in parentheses are , Indicating the relative dielectric constant of the polymer material (resin)).

  For example, methyl methacrylate resin (3.0), acrylonitrile resin (4.0), acetate resin (3.4), aniline resin (3.5), aniline formaldehyde resin (4.0), aminoalkyl resin ( 4.0), alkyd resin (5.0), nylon-6-6 (3.4), ethylene resin (2.2), epoxy resin (2.5), vinyl chloride resin (3.3), chloride Vinylidene resin (3.0), urea formaldehyde resin (7.0), polyacetal resin (3.6), polyurethane (5.0), polyester resin (2.8), polyethylene (low pressure) (2.3), Polyethylene terephthalate (2.9), polycarbonate resin (2.9), melamine resin (5.1), melamine formaldehyde resin (8.0), cellulose acetate (3.2), acetic acid Sulfonyl resin (2.7), styrene resins (2.3), styrene butadiene rubber (3.0), styrene resin (2.4), it can be used polytetrafluoroethylene (2.0) or the like.

The polymer material having a low relative dielectric constant is preferably selected in accordance with various purposes such as adjusting the piezoelectric characteristics or imparting the physical strength of the organic piezoelectric film. .
(Material that can form a covalent bond with the electrode metal)
The organic piezoelectric material of the present invention contains a material capable of forming a covalent bond with the electrode metal of the electrode, and is further covalently bonded to the electrode metal.

  In the present invention, the material capable of forming a covalent bond with the electrode metal is not particularly limited as long as it is a material capable of forming a covalent bond with the electrode metal, but from the point that the mercapto group is firmly bonded to the electrode metal, Compounds and mercapto-based silane coupling agents are preferred, and preferred examples include mercapto compounds represented by the above general formula (I) or the following mercapto-based silane coupling agents.

  The mercapto compound represented by the general formula (I) used in the present invention will be described.

  In the general formula (I), Q represents an atomic group necessary for forming a 5-membered heterocyclic ring optionally having a substituent or a 5-membered heterocyclic ring condensed with a benzene ring.

  Examples of the 5-membered heterocyclic ring formed by Q in the general formula (I) include an imidazole ring, a triazole ring, a tetrazole ring, a thiazole ring, a thiadiazole ring, an oxazole ring, an oxadiazole ring, a benzimidazole ring, and a naphtho ring. Examples thereof include an imidazole ring and a benzoxazole ring. Examples of the substituent for Q include an alkyl group, an alkoxy group, an aryl group, a sulfonyl group, a carbonyl group, a carboxyl group, a carbonamide group, a carboxylic acid ester group, an amino group, and a sulfonamide group.

  Among the mercapto compounds represented by the general formula (I), a mercaptotetrazole compound is preferable. For example, a mercapto compound represented by the following general formula (II) can be preferably used.

In the general formula (II), Y represents a hydrogen atom, amino group, alkyl group, alkenyl group, cycloalkyl group, aryl group, -CONHR ³² group, -COR ³³ group, -NHCOR ³⁴ group or -HNSO ₂ R ³⁴ group. Etc. Examples of R ³² , R ³³ , R ³⁴ , R ³⁵ , and R ³⁶ include an alkyl group, an alkenyl group, a cycloalkyl group, and an aryl group.

  Although the preferable example of the mercapto compound represented with general formula (I) or (II) which can be used for this invention below is shown, this invention is not limited to this.

  Of the compounds represented by the general formulas (I) and (II), mercaptotetrazole compounds represented by ME-1 to ME-11 are particularly preferable.

  Examples of the mercapto-based silane coupling agent used in the present invention include 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 6-mercaptohexatrimethoxysilane. In the mercapto-based silane coupling agent, the size of the bonding group R that bonds the mercapto group and the silicon atom is preferably 2 to 30 carbon atoms of R. 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane can be preferably used.

  The material capable of forming a covalent bond with the electrode metal is preferably contained in an amount of 0.01 to 5% by mass with respect to the organic piezoelectric material.

(Method for producing organic piezoelectric film)
(Stretched film formation)
When the organic piezoelectric material of the present invention is used as a vibrator, it is generally formed in a film shape and then a surface electrode for inputting an electric signal.

  For film formation, a general method such as a melting method or a casting method can be used. In the case of a polyvinylidene fluoride-trifluoroethylene copolymer, it is known that it has a crystalline form with spontaneous polarization only when it is made into a film, but in order to further improve the characteristics, a process for aligning the molecular arrangement should be added. Is useful. Examples of means include stretching film formation and polarization treatment.

  Various known methods can be adopted for the method of stretching film formation. For example, a solution obtained by dissolving the above polymer material in an organic solvent such as ethyl methyl ketone (MEK) is cast on a substrate such as a glass plate, and the solvent is dried at room temperature to obtain a film having a desired thickness. The film is stretched to a predetermined length at room temperature. The stretching can be performed in a uniaxial / biaxial direction so that the organic piezoelectric film having a predetermined shape is not broken. The draw ratio is 2 to 10 times, preferably 2 to 6 times.

  In the vinylidene fluoride-trifluoroethylene copolymer and / or vinylidene fluoride-tetrafluoroethylene copolymer, the melt flow rate at 230 ° C. is 0.03 g / min or less. More preferably, a high-sensitivity piezoelectric thin film can be obtained by using a polymer piezoelectric body of 0.02 g / min or less, more preferably 0.01 g / min.

(Ultrasonic transducer)
The ultrasonic transducer is manufactured by forming electrodes on both sides or one side of an organic piezoelectric material film (layer) and polarizing the organic piezoelectric material film.

(electrode)
In the present invention, as the electrode metal, an electrode may be formed using Al, Zn, Fe, Ni, Cr, Sn, Cu, Ag, or Au metal, or an alloy mainly composed of these metals. it can. More preferably, the electrode metal is a metal or alloy containing Au as a main component.

  In forming the electrode, first, a base metal such as nickel (Ni), Au, titanium (Ti), or chromium (Cr) is formed to a thickness of 0.02 to 0.1 μm by sputtering. Thereafter, a metal material mainly composed of the above metal element and a metal material thereof, and further, if necessary, a partial insulating material is formed to a thickness of 0.02 to 1 [mu] m by sputtering or other suitable method. In addition to sputtering, these 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.

(Polarization treatment)
Furthermore, an ultrasonic vibrator (piezoelectric element) can be obtained by supplying a predetermined voltage between the electrodes formed on both surfaces of the organic piezoelectric material film to polarize the organic piezoelectric material film.

  As a polarization treatment method in the polarization treatment, a conventionally known method such as a DC voltage application treatment, an AC voltage application treatment, or a corona discharge treatment can be applied.

  For example, in the case of the corona discharge treatment method, the corona discharge treatment can be performed by using a commercially available device comprising a high voltage power source and electrodes.

  Since the discharge conditions vary depending on the equipment and the processing environment, it is preferable to select the conditions as appropriate. The voltage of the high voltage power source is preferably -1 to -20 kV, the current is 1 to 80 mA, the distance between the electrodes is preferably 1 to 10 cm, and the applied voltage is preferably 0.5 to 2.0 MV / m. .

  As the electrodes, needle-like electrodes, linear electrodes (wire electrodes), and mesh-like electrodes that have been conventionally used are preferable, but the invention is not limited thereto.

(Ultrasonic probe)
In the present invention, both transmission and reception of ultrasonic waves may be performed by a single transducer, but more preferably, the transducers are configured separately for transmission and reception in the probe.

  The piezoelectric material constituting the transmitting vibrator may be a conventionally known ceramic inorganic piezoelectric material or an organic piezoelectric material.

  The ultrasonic probe of the present invention is a probe for an ultrasonic medical image diagnostic apparatus including an ultrasonic transmission transducer and an ultrasonic reception transducer, and the ultrasonic transducer of the present invention is a probe. The ultrasonic receiving vibrator can be used (hereinafter, the ultrasonic vibrator of the present invention is also referred to as the ultrasonic receiving vibrator of the present invention).

  In the ultrasonic probe of the present invention, the ultrasonic receiving transducer of the present invention can be arranged on or in parallel with the transmitting transducer.

  As a more preferred embodiment, the structure for laminating the ultrasonic receiving transducer of the present invention on the ultrasonic transmitting transducer is good, and in this case, the ultrasonic receiving transducer of the present invention is another high-frequency transducer. You may laminate | stack on the vibrator | oscillator for transmission in the form joined together on the molecular material (The polymer (resin) film, for example, polyester film) whose relative dielectric constant is comparatively low as a support body. In this case, it is preferable that the film thickness of the receiving vibrator and the other polymer material be matched to a preferable receiving frequency band in terms of probe design. Considering a practical ultrasonic medical diagnostic imaging apparatus and biological information collection from a practical frequency band, the film thickness is preferably 40 to 150 μm.

  The probe may be provided with a backing layer, an acoustic matching layer, an acoustic lens, and the like. Also, a probe in which vibrators having a large number of piezoelectric materials are two-dimensionally arranged can be used. A plurality of two-dimensionally arranged probes can be sequentially scanned to form a scanner.

(Ultrasonic medical diagnostic imaging equipment)
The ultrasonic probe according to the present invention can be used for various types of ultrasonic diagnostic apparatuses. For example, an ultrasonic probe (probe) in which piezoelectric transducers that transmit ultrasonic waves to a subject such as a patient and receive ultrasonic waves reflected by the subject as echo signals is arranged is provided. An ultrasonic medical image diagnostic apparatus is preferred. 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 vibrator of the ultrasonic probe, and transmission / reception control of the transmission / reception circuit It is preferable that a transmission / reception control circuit for performing the above is provided.

  Further, the display control unit includes an image data conversion circuit that converts the echo signal received by the transmission / reception circuit into ultrasonic image data of the subject, and controls and displays the monitor with the ultrasonic image data converted by the image data conversion circuit. An ultrasonic medical image diagnostic apparatus including a circuit and a control circuit that controls the entire ultrasonic medical image diagnostic apparatus is preferable.

  In such an ultrasonic medical image diagnostic apparatus, a transmission / reception control circuit, an image data conversion circuit, and a display control circuit are connected to a control circuit, and the control circuit controls operations of these units. Then, an electrical signal is applied to each piezoelectric vibrator of the ultrasonic probe to transmit an ultrasonic wave to the subject, and the reflected wave caused by acoustic impedance mismatch inside the subject is detected by the ultrasonic probe. Receive at.

  The transmission / reception circuit corresponds to “means for generating an electrical signal”, and the image data conversion circuit corresponds to “image processing means”.

  According to the ultrasonic diagnostic apparatus as described above, by utilizing the characteristics of the ultrasonic receiving vibrator excellent in piezoelectric characteristics and heat resistance of the present invention and suitable for high frequency and wide band, the image quality and its An ultrasonic image with improved reproduction and stability can be obtained.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1
<< Production of organic piezoelectric material >>
Polyvinylidene fluoride copolymer powder (weight average molecular weight 290,000) having a molar ratio of vinylidene fluoride (VDF) to trifluoroethylene (3FE) of 75:25 was dried at 50 ° C. for 12 hours in a vacuum oven. Next, 70 g of this powder, ethyl methyl ketone (MEK), dimethylformamide (a material capable of forming a covalent bond with the electrode metal according to the present invention of the type and addition amount shown in Table 1) heated to 50 ° C. A solution dissolved in 630 g of a 9: 1 mixed solvent of DMF) was cast on a glass plate. Thereafter, the solvent was dried at 55 ° C. to obtain a film (organic piezoelectric material film) having a thickness of about 140 μm. The film was stretched 4 times at room temperature, then heat treated at 135 ° C. for 1 hour while maintaining the stretched length, and then naturally cooled to obtain organic piezoelectric materials 1 to 22, respectively. The film thickness after heat treatment was 43 μm.

<Production of ultrasonic transducer>
The surface of the obtained organic piezoelectric materials 1 to 22 (film) is nickel-treated with a vacuum vapor deposition device JEE-420 (manufactured by JEOL Datum) so that the surface resistance is 1Ω or less (0.1 μm) Then, gold was deposited (0.2 μm) to obtain a sample with a surface electrode.

  Subsequently, the electrode was subjected to a polarization treatment while applying an AC voltage of 0.1 Hz at room temperature. The polarization treatment was performed from a low voltage, and the voltage was gradually applied until the electric field between the electrodes finally reached 100 MV / m. Ultrasonic transducer samples 1 to 22 were obtained.

<Evaluation>
(Adhesiveness)
Adhesion was measured by a 90 degree peel test.

Specifically, after reinforcing Kapton tape (Kapton R electrical insulation tape, manufactured by Permacel) is applied to one side of the ultrasonic transducer sample, an epoxy adhesive is applied onto the other surface electrode. The glass substrate and the ultrasonic element sample with the reinforcing Kapton tape attached thereto were pressure-bonded at 15 × 10 ⁵ Pa / cm ² using a pressure jig and dried at 50 ° C. Using force gauge ZP-20N (manufactured by Imada Co., Ltd.), the adhesive strength between the organic piezoelectric film and the electrode when peeled together with the reinforcing Kapton tape is measured, and the adhesion is evaluated according to the following evaluation criteria. went.
Evaluation criteria A: 20000 Pa / cm or more B: 15000 Pa / cm or more and less than 20000 Pa / cm C: 10,000 Pa / cm or more and less than 15000 Pa / cm D: 5000 Pa / cm or more and less than 10000 Pa / cm The results are shown in Table 1.

  As is apparent from Table 1, in the case of the present invention, excellent adhesive strength can be easily obtained without going through complicated steps such as surface treatment, and it is extremely excellent in adhesion between the organic piezoelectric material and the electrode metal. You can see that

  In the case of the present invention, excellent adhesive strength can be easily obtained without going through complicated steps such as surface treatment, excellent adhesion to electrode metal, excellent resistance to electrode peeling due to friction during operation, An organic piezoelectric material used to form an ultrasonic transducer suitable for high frequency and wide band, with excellent suppression of delamination generation even with weak friction during processing, excellent workability, excellent piezoelectricity, and its use It can be seen that an ultrasonic transducer and an ultrasonic probe using the same can be provided.

Claims (10)

  An organic piezoelectric material used in an ultrasonic vibrator having an electrode formed on the surface of an organic piezoelectric material, wherein the organic piezoelectric material contains a material capable of forming a covalent bond with the electrode metal of the electrode, and the electrode metal An organic piezoelectric material, wherein a material capable of forming a covalent bond with the electrode metal is covalently bonded to the electrode metal.   2. The organic piezoelectric material according to claim 1, comprising 0.01 to 5 mass% of a material capable of forming a covalent bond with the electrode metal.   The organic piezoelectric material comprises polyvinylidene fluoride, a polymer of vinylidene fluoride and trifluoroethylene, a polymer of vinylidene fluoride, trifluoroethylene, and monofluoroethylene, and vinylidene fluoride, trifluoroethylene, and methyl methacrylate. The polymer, a polymer of vinylidene fluoride, trifluoroethylene, and vinyl acetate, a cellulose-based derivative, and a polymer of polyurea, and at least one selected from a polymer copolymer, 3. The organic piezoelectric material according to 1 or 2.   The organic piezoelectric material according to claim 3, wherein the organic piezoelectric material contains vinylidene fluoride as a main component.   The organic piezoelectric material according to any one of claims 1 to 4, wherein the material capable of forming a covalent bond with the electrode metal includes a mercapto group as a functional group. The material capable of forming a covalent bond with the electrode metal is a mercapto compound represented by the following general formula (I), or at least one selected from 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane. It is a mercapto type | system | group silane coupling agent, The organic piezoelectric material of any one of Claims 1-5 characterized by the above-mentioned.

  7. The electrode metal according to claim 1, wherein the electrode metal is Al, Zn, Fe, Ni, Cr, Sn, Cu, Ag, or Au, or an alloy containing the metal as a main component. 2. The organic piezoelectric material according to item 1.   The organic piezoelectric material according to claim 7, wherein the electrode metal is a metal or an alloy containing Au as a main component.   An ultrasonic transducer using the organic piezoelectric material according to claim 1.   An ultrasonic probe comprising an ultrasonic transmission transducer and an ultrasonic reception transducer, wherein the ultrasonic transducer according to claim 9 is used as an ultrasonic reception transducer. Ultrasonic probe.