JP4873966B2 - Ultrasonic transducer - Google Patents

Description

  The present invention relates to an ultrasonic transducer that transmits ultrasonic waves in a gas or receives ultrasonic waves that propagate in the gas.

  The conventional ultrasonic transducer 50 is configured as shown in FIG. In the figure, a piezoelectric body 51 is bonded to a case 53 via a bonding means 55. The case is made of a metal material such as stainless steel. An acoustic matching member 52 is further joined to the case 53 via a joining means 54.

  The piezoelectric body 51 converts an electrical signal into mechanical vibration. This mechanical vibration is transmitted as ultrasonic waves into the gas via the acoustic matching member 52. In order to efficiently transmit vibration generated in the piezoelectric body 51 to the gas, it is necessary to consider acoustic impedance.

  The acoustic impedance Z of the object is defined by the sound speed C and the density ρ as shown in Expression (10).

Z = ρ × C (10)
The acoustic impedance Z _P of the piezoelectric body 51 that is the vibration generating means is 30 × 10 6 kg / (m ² s), and the acoustic impedance Z _A of a gas that is an ultrasonic radiation medium, for example, air, is 400 kg / (m ² s). ) And very different.

  The ultrasonic waves are reflected on the boundary surfaces having different acoustic impedances, and the intensity of the transmitted ultrasonic waves is weakened and cannot be transmitted efficiently.

An acoustic matching member is used to solve this problem, and is formed between the piezoelectric body and the radiation medium. Acoustic impedance Z _M of the acoustic matching member, by satisfying the following relation (11), ultrasonic wave is efficiently transmitted to the radiation medium.

Z _M = (Z _P × Z _A ) ^(1/2) (11)
This optimum value is about 11 × 10 4 kg / (m ² s). As can be seen from the equation (11), the acoustic matching member is required to be solid, low in density and low in sound speed. Conventionally, a dry gel is used as this type of material. A method for producing this dry gel is disclosed in Patent Document 1. Further, Patent Document 2 discloses an ultrasonic vibrator using a silica dry gel.
Japanese Patent Laying-Open No. 2005-8424 JP 2002-262394 A

  However, since the case 53 is made of a metal material such as stainless steel in the conventional configuration, the thermal expansion coefficient is as high as 17.8 ppm / ° C. On the contrary, the silica dry gel used as the acoustic matching member 52 is several ppm / ° C. or less. For this reason, when a silica dry gel is joined to the case 53, the case 53 expands and contracts due to a change in temperature of the use environment. However, the silica dry gel is difficult to expand and contract, so that the silica dry gel may be cracked. For this reason, the operation | movement of the ultrasonic transducer | vibrator had the subject that it was not stabilized. In addition, since the thermal expansion coefficient of the piezoelectric body is 7.5 ppm / ° C., the same problem occurs even when a silica dry gel is joined.

  An object of the present invention is to solve the above-mentioned conventional problems and to provide an ultrasonic transducer having an acoustic matching member made of silica dry gel that operates stably even with respect to temperature changes in the use environment.

  In order to solve the above-mentioned conventional problems, the ultrasonic transducer of the present invention has flexibility by devising a silica dry gel material used for an acoustic matching member.

  Flexibility can be obtained by making the organosilane compound, which is a silica dry gel material, contain a hydrolyzable organic group and a non-hydrolyzable organic group directly bonded to the same silicon.

  The ultrasonic transducer | vibrator of this invention can provide a softness | flexibility to the silica dry gel used for an acoustic matching member. Therefore, even if the case expands or contracts due to temperature changes in the usage environment, the silica dry gel follows the expansion and contraction.Therefore, it has the effect of preventing its own damage, and the ultrasonic vibrator operates stably over a wide temperature range. can do.

The ultrasonic transducer of the first invention is an acoustic transducer comprising a silica dry gel obtained by polymerizing and drying an organosilane compound in which a hydrolyzable organic group and a non-hydrolyzable organic group are directly bonded to the same silicon. and a matching member and the piezoelectric, the organosilane compound is the formula (5), that contains at least one of the formulas (6), a copolymer of the compound represented by the formula (7) . As a result, flexibility can be imparted to the silica dry gel, and the acoustic matching member using the silica gel will follow the expansion and contraction even if the bonded member expands and contracts due to temperature changes in the usage environment. This has the effect of preventing damage to itself, and the ultrasonic transducer has the effect of being able to operate stably over a wide temperature range. Furthermore, when the dried gel is used while being adhered to the base material, the adhesion with the adherend layer can be improved, and the acoustic matching member using this is more difficult to peel off than the joined member and operates stably. be able to.

  The ultrasonic vibrator of the second invention is obtained by polymerizing an organosilane compound with a compound represented by the formula (1) or a partially hydrolyzed polymer of the compound represented by the formula (1) and drying the organosilane compound. An acoustic matching member containing a silica dry gel and a piezoelectric body are provided.

  As a result, a silica dry gel having both strength and flexibility can be obtained, and the acoustic matching member using the silica gel can follow the expansion and contraction even if the bonded member expands and contracts due to temperature changes in the usage environment. Therefore, it has an effect of preventing its own damage, and the ultrasonic transducer has an effect of being able to operate stably in a wide temperature range.

  An ultrasonic transducer according to a third aspect of the present invention is a wet gel obtained by polymerizing an organosilane compound with a compound represented by the formula (1) or a partially hydrolyzed polymer of the compound represented by the formula (1). An acoustic matching member and a piezoelectric body containing a silica dry gel obtained by polymerizing and drying an organosilane compound in which the hydrolyzable organic group and the non-hydrolyzable organic group are directly bonded to the same silicon. Is provided.

  As a result, a silica dry gel having both strength and flexibility can be obtained, and the acoustic matching member using the silica gel can follow the expansion and contraction even if the bonded member expands and contracts due to temperature changes in the usage environment. Therefore, it has an effect of preventing its own damage, and the ultrasonic transducer has an effect of being able to operate stably in a wide temperature range.

The ultrasonic vibrator according to the fourth invention comprises an organosilane compound in which a hydrolyzable organic group and a non-hydrolyzable organic group are directly bonded to the same silicon, a compound represented by the formula (1) and its hydrolysis An acoustic matching member containing a silica dry gel of 0.1 wt% to 10 wt% with respect to the total of the condensed polymers and a piezoelectric body are provided. As a result, flexibility can be effectively imparted to the silica dry gel, and the acoustic matching member using the silica gel can be expanded or contracted even if the bonded member expands or contracts due to a change in the temperature of the usage environment. Since it follows, it has the effect of preventing its own damage, and the ultrasonic transducer has the effect of being able to operate stably over a wide temperature range.

  An ultrasonic vibrator according to a fifth aspect of the invention includes a silica dry gel in which an organosilane compound is polymerized with a compound containing at least one of the formula (2) or the formula (3) to have a molecular weight of 200 or more. An acoustic matching member and a piezoelectric body are provided. As a result, the silica dry gel can be surely imparted with flexibility, and the acoustic matching member using the silica dry gel follows the expansion and contraction even when the bonded member expands and contracts due to the temperature change of the use environment. Therefore, it has an effect of preventing its own damage, and the ultrasonic transducer has an effect of being able to operate stably in a wide temperature range.

  An ultrasonic transducer according to a sixth aspect of the present invention includes an acoustic matching member containing an organosilane compound and a silica dry gel that is a linear polysiloxane diol represented by the formula (4), and a piezoelectric body. As a result, flexibility can be imparted to the silica dry gel, and the acoustic matching member using the silica gel will follow the expansion and contraction even if the bonded member expands and contracts due to temperature changes in the usage environment. This has the effect of preventing damage to itself, and the ultrasonic transducer has the effect of being able to operate stably over a wide temperature range.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited by the embodiment of the present invention.

(Embodiment 1)
FIG. 1 shows a cross-sectional view of an ultrasonic transducer 1 according to the first embodiment.

  In FIG. 1, the acoustic matching member 2 and the piezoelectric body that is the member 3 to be joined are joined together by an adhesive that is the joined body 4. Opposing electrodes 5 and 6 are formed on the piezoelectric body. The electrode is formed by heating and baking a conductive paste such as silver or gold. The electrodes 5 and 6 and the electrode leads 7 and 8 are electrically joined by solder or silver solder. As the acoustic matching member 2, a soft silica dry gel was used.

  Hereinafter, a method for producing a silica dry gel will be described with reference to FIG.

  FIG. 2 shows a manufacturing process flow of the silica dry gel in the first embodiment.

  In FIG. 2, the silica dry gel manufacturing process is formed by the I raw material preparation process 9, the II gelation process 10, the III reconstruction process 11, the IV hydrophobization process 12, and the V drying process 13. The steps 9 to 13 will be described in detail below.

I Raw material preparation process 9
In this step, an organosilane compound that is a main raw material of silica dry gel and water, a reaction solvent, and a catalyst for hydrolyzing the compound are added to make a mixed solution that is a starting raw material. The organosilane compound has a structure as shown in the conceptual diagram of molecular arrangement shown in FIG. 3, for example. In the figure, the non-hydrolyzable organic group 15 is directly bonded to the silicon 16 and is not hydrolyzed with other organosilane compounds. The hydrolyzable organic group 17 is also directly bonded to the silicon 16, and is hydrolyzed and polymerized with other organosilane compounds by hydrolysis. The following can be illustrated as such a structure.

  Formula (2) comprises one non-hydrolyzable organic group 10, and formula (3) comprises a hydrolyzed polymer of a compound comprising two non-hydrolyzable organic groups 10, and has a molecular weight of 200 or more. Siloxane. Formula (4) shows a linear polysiloxane diol having two non-hydrolyzable organic groups 10.

R ¹ in the formula (1) is not particularly limited, but for example, those having an alkyl group having 1 to 4 carbon atoms as a main raw material are used.

R ^{2 in} Formula (2), Formula (3), and Formula (4) is not particularly limited, and examples thereof include substituted or unsubstituted monovalent hydrocarbon groups having 1 to 8 carbon atoms. Specifically, alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group and octyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; 2-phenylethyl group, Aralkyl groups such as 3-phenylpropyl group; aryl groups such as phenyl group and tolyl group; alkenyl groups such as vinyl group and allyl group; chloromethyl group, γ-chloropropyl group, 3,3,3-trifluoropropyl A halogen-substituted hydrocarbon group such as a group; substituted hydrocarbon groups such as γ-methacryloxypropyl group, γ-glycidoxypropyl group, 3,4-epoxycyclohexylethyl group, γ-mercaptopropyl group, etc. Can do. Among these, an alkyl group having 1 to 4 carbon atoms and a phenyl group are preferable from the viewpoint that synthesis is easy, availability, and hardness does not decrease excessively.

  Accordingly, the organotrialkoxysilane of formula (2) includes methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,3,3-trifluoropropyltrimethyl. A methoxysilane etc. can be illustrated.

Examples of the diorganodialkoxysilane of formula (3) include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and methylphenyldimethoxysilane.
These organosilane compounds may contain compounds represented by the formulas (5), (6), and (7).

R ⁴ in the formula (5) is a substituted or unsubstituted hydrocarbon group having 1 to 9 carbon atoms.

R ⁵ in the formula (6) is at least one selected from the group consisting of an epoxy group, a glycidyl group, and a hydrocarbon group containing at least one of them (for example, γ-glycidoxypropyl group, etc.). At least one of the groups.

R ⁶ in formula (7) is a hydrocarbon group containing an alkoxysilyl group and / or a halogenated silyl group, for example, a trimethoxysilylpropyl group, a dimethoxymethylsilylpropyl group, a monomethoxydimethylsilylpropyl group, a triethoxysilylpropyl group Group, diethoxymethylsilylpropyl group, ethoxydimethylsilylpropyl group, trichlorosilylpropyl group, dichloromethylsilylpropyl group, chlorodimethylsilylpropyl group, chlorodimethoxysilylpropyl group, dichloromethoxysilylpropyl group, etc. One type.

  In addition, the starting material for obtaining a dry gel according to the present invention is, for example, tetramer represented by the formula (1), which is composed only of the hydrolyzable organic group 17 as shown in the molecular arrangement conceptual diagram shown in FIG. An alkoxysilane may be contained. Examples of these include tetramethoxysilane and tetraethoxysilane.

  The compounds, polymers or copolymers represented by the formulas (2) to (7) exemplified above are all components that soften the dried gel and make it difficult to break. By polymerizing the compounds represented by the formulas (2) and (3) so as to have a molecular weight of 200 or more, the effect of softening the gel obtained is increased. For example, even when the compounds represented by the formulas (2) and (3) are used, the effect of softening the dried gel is small when a monomer having a low molecular weight is used. The compound represented by the formula (4) also has a great softening effect, and particularly when used simultaneously with the tetraalkoxysilane represented by the formula (1), it is easy to copolymerize (crosslink) with this. Easy to control. A copolymer of the compounds represented by the formulas (5), (6) and (7) has a great effect on softening the gel. The structure represented by the formula (5) has an effect of giving the copolymer great flexibility. The structure part represented by the formula (6) improves the adhesion to the adherend layer when the dry gel is adhered to a substrate. In addition, in order to bridge | crosslink the structure part represented by Formula (5) or Formula (6), and another organosilane, the structure part represented by Formula (7) is an essential component.

  The concentration contained in the dry gel of the compound or polymer or copolymer represented by the formulas (2) to (7) is not particularly specified, but is 0.01% to 20% by weight. Is preferred. If the concentration of this component is too low, it will not be possible to prevent dry gel cracking or peeling when using a substrate. On the other hand, if it is too high, the strength decreases and shrinkage occurs when the wet gel is dried. For these reasons, the concentration of this compound is more preferably 0.1% by weight to 10% by weight.

  As the catalyst, a general organic acid, inorganic acid, organic base, or inorganic base is used. Examples of organic acids include acetic acid and citric acid, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, organic bases such as piperidine, and inorganic bases such as ammonia. In addition, use of an imine type such as piperidine is more preferable from the viewpoint of reducing capillary force because of the effect of increasing the pore diameter.

  Solvents include lower alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol and diethylene glycol, mono- or diethers of ethylene glycol and diethylene glycol, lower ketones such as acetone, lower ethers such as tetrahydrofuran and 1,3-dioxolane. A water-soluble organic solvent is used. In addition, when a gel is formed by hydrolysis or condensation polymerization of the first gel raw material, water necessary for hydrolysis is also added.

  The compounds shown above are stirred and mixed to prepare raw materials. FIG. 5 is a conceptual diagram of the organosilane compound at this time. In FIG. 5, a triangle (Δ) indicates an organosilane compound 14 having a non-hydrolyzable organic group 15, and a square (□) indicates an organosilane compound 18 having only a hydrolyzable organic group 17, (a) Shows the state of the gel raw material solution 19 in which these organosilane compounds, catalyst and solvent are dispersed. These organosilane compounds are hydrolyzed by a catalyst and polymerized. FIG.5 (b) has shown the superposition | polymerization conceptual diagram of the polymerized organosilane compound. As shown in this figure, the gel raw material solution 19 is polymerized and dried through the wet gel 20 to form a silica dry gel.

II Gelation process 10
In this step, following the raw material preparation step 9, a catalyst is added to the prepared mixed solution to promote hydrolysis polymerization to form a solid skeleton of the gel, thereby forming a wet gel in which the gel contains a solvent. It is. In order to promote gelation, a catalyst is added and the solution temperature is increased as necessary. The catalyst is omitted because it is exemplified in the raw material preparation step. Note that the catalyst need not be divided and added in the raw material preparation step 9 and the gelation step 10, and the raw material preparation step 9 and the gelation step 10 may be performed at a time.

III reconstruction process 11
In this step subsequent to the gelation step 10, a new solid skeleton is formed while part of the solid skeleton of the wet gel formed in the gelation step 10 is decomposed. Specifically, first, a restructuring raw material solution is prepared by adding and mixing a restructuring raw material for the restructuring step, a restructuring catalyst and water, and, if necessary, a solvent. The obtained wet gel is immersed. The density of the silica dry gel can be adjusted by the treatment time and treatment temperature in this step. As the reconstruction catalyst or organosilane compound used in the reconstruction step, those exemplified in the gelation step 10 can be used, but it is not particularly necessary to be the same as that in the gelation step. For the purpose of stopping the reaction after enhancing the gel skeleton, the reaction is stopped by replacing the reconstituted raw material solution with, for example, isopropyl alcohol.

IV hydrophobization process 12
In this step following the reconstruction step 11, a hydrophobic group is introduced by reacting the surface of the wet gel obtained up to the reconstruction step 11 with a hydrophobizing solution in which a hydrophobizing agent is dissolved in a solvent.

  The hydrophobizing agent used in the present invention is preferably a silylating agent from the viewpoint of high reactivity, and examples thereof include silazane compounds, chlorosilane compounds, alkylsilanol compounds and alkylalkoxysilane compounds.

  In the case of a silazane compound, a chlorosilane compound, or an alkylalkoxysilane compound, these silylating agents react with silanol groups on the gel surface after being directly or hydrolyzed to the corresponding alkylsilanol. Further, when alkylsilanol is used as a silylating agent, it reacts with the silanol group on the surface as it is.

  Among these, chlorosilane compounds and silazane compounds are particularly preferred because of their high reactivity during hydrophobization and availability, and because they are easily available and do not generate gases such as hydrogen chloride and ammonia during hydrophobization. Alkyl alkoxysilanes are particularly preferably used.

  Specifically, chlorosilane compounds such as trimethylchlorosilane, methyltrichlorosilane and dimethyldichlorosilane, silazane compounds such as hexamethyldisilazane, methoxytrimethylsilane, ethoxytrimethylsilane, dimethoxydimethylsilane, dimethoxydiethylsilane and diethoxydimethylsilane There are silylating agents represented by silanol compounds such as alkylalkoxysilane compounds, trimethylsilanol and triethylsilanol. If these are used, hydrophobization can be promoted by introducing an alkylsilyl group such as a trimethylsilyl group into the wet gel surface.

  Further, if a fluorinated silylating agent is used as the hydrophobizing agent, the hydrophobicity becomes strong and is very effective.

In addition, as hydrophobizing agents, alcohols such as ethanol, propanol, butanol, hexanol, heptanol, octanol, ethylene glycol and glycerol, carboxylic acids such as formic acid, acetic acid, propionic acid and succinic acid can also be used. . These are hydrophobized by reacting with the hydroxyl groups on the gel surface to form ethers or esters, but the reaction is relatively slow and requires high temperature conditions.

  The hydrophobization process is a treatment to prevent the final dried gel from absorbing moisture. After the gel is put into the silane coupling solution, the silane treatment reaction is stopped by replacing the solution with, for example, isopropyl alcohol. Let

V drying process 8
In this step, the solvent is removed from the wet gel obtained up to the hydrophobization step to obtain a silica dry gel 1.

  As a drying method for removing the solvent from the wet gel, there are (1) natural drying method and (2) special drying method.

  (1) The natural drying method is the most common and simple drying method, in which a wet gel containing a solvent is allowed to stand to evaporate and remove the solvent in a liquid state. Most preferable from the viewpoint. From the viewpoint of productivity, the natural drying method includes heat-drying for heating the wet gel or vacuum drying for reducing the wet gel below atmospheric pressure.

  The heating temperature is not particularly limited as long as the solvent evaporates.

  When drying, if the gel density is low, the gel may temporarily shrink and crack due to capillary forces proportional to the surface tension of the solvent in the gel. For this reason, the solvent for drying is preferably a hydrocarbon-based solvent having a low surface tension at the boiling point, and particularly inexpensive hexane, pentane or a mixture thereof is preferable. On the other hand, from the viewpoint of safety, drying from alcohols such as isopropanol, ethanol and butanol, and further from a mixed solvent of water and an organic solvent is preferable. Therefore, the stress at the time of drying can be reduced by substituting the solvent shown above according to the purpose with the solvent used at the time of forming the wet gel, and the wet gel is hardly broken at the time of drying.

  (2) There are two special drying methods: supercritical drying and freeze drying.

  In supercritical drying, the solvent can be removed in a supercritical state without passing through a liquid state, so that there is no generation of capillary force that forms a gas-liquid interface. For this reason, a wet gel becomes difficult to crack at the time of drying. Examples of supercritical fluids used for drying include water, alcohol, and carbon dioxide. Carbon dioxide, which is supercritical at the lowest temperature and is harmless, is often used.

  Specifically, first, liquefied carbon dioxide is introduced into the pressure vessel, and the wet gel solvent in the pressure vessel is replaced with liquefied carbon dioxide. Next, the pressure and temperature are raised to a critical point or higher to achieve a supercritical state, and carbon dioxide is gradually released while maintaining the temperature to complete drying.

  Freeze-drying is a drying method in which the solvent in the wet gel is frozen and the solvent is removed by sublimation. Since it does not go through a liquid state and does not produce a gas-liquid interface in the gel, capillary force does not work. For this reason, the shrinkage | contraction of the gel at the time of drying can be suppressed.

  The solvent used in the freeze-drying method is preferably a solvent having a high vapor pressure at the freezing point, and examples thereof include tertiary butanol, glycerin, cyclohexane, cyclohexanol, para-xylene, benzene, and phenol. Among these, tertiary butanol and cyclohexane are particularly preferable because of high vapor pressure at the melting point.

  At the time of lyophilization, it is effective to replace the solvent in the wet gel with a solvent having a high vapor pressure at the above-mentioned freezing point. In addition, it is more preferable to use a solvent having a high vapor pressure at the freezing point as the solvent used for the gelation because the solvent replacement can be omitted and efficient production becomes possible.

  Drying may be performed after the hydrophobizing step or may be performed before the hydrophobizing step. In the case of hydrophobizing after the drying step, hydrophobic groups are introduced on the surface of the dried gel by exposing the dried gel to the vapor of the hydrophobizing agent, not in the solution. Therefore, the amount of solvent used can be reduced.

  As the hydrophobizing agent used at this time, the above-mentioned hydrophobizing agents can be used, but chlorosilane compounds such as trimethylchlorosilane and dimethyldichlorosilane are most preferable because of their high reactivity. When using a hydrophobizing agent other than the chlorosilane compound, it is also effective to use a catalyst that can be introduced in a gaseous state, such as ammonia or hydrogen chloride.

  Further, when hydrophobizing in the gas phase, the temperature during hydrophobizing can be increased without being limited by the boiling point of the solvent or hydrophobizing agent. Therefore, hydrophobization in the gas phase is effective for speeding up the reaction. Moreover, if the wet gel is a thin film or powder, the penetration of the hydrophobizing agent vapor is easy, and the thin film is more preferable because the effect of reducing the amount of solvent is great.

  Since the acoustic matching member including the silica dried gel formed as described above is imparted with flexibility, even if the piezoelectric body that is the bonded member 3 due to temperature change expands and contracts, the flexible acoustic matching member By expanding and contracting following this expansion and contraction, it becomes possible to prevent its own destruction. As a result, the ultrasonic transducer 1 of the present invention can operate stably over a wide temperature range.

(Embodiment 2)
FIG. 6 is a conceptual diagram of an organosilane compound in a silica dry gel production process according to the second embodiment of the present invention. FIG. 2A shows a gel raw material solution 21 prepared by first preparing a raw material with an organosilane compound 18 composed only of hydrolyzable organic groups 17 in the raw material adjusting step 9 and dispersing it into a II gel. In step 10, gelation is performed. Next, in FIG. 2B, the organosilane compound 14 having the non-hydrolyzable organic group 15 and the hydrolyzable organic group 15 are added to the wet gel 22 formed in the I raw material adjustment step 9 and the II gelation step 10. Hydrolysis is performed by adding a reconstituted solution 23 in which an organosilane compound 18 having only groups 17 is mixed and dispersed. In this way, a wet gel 24 produced by hydrolysis and polymerization (crosslinking) as shown in FIG. Since the organosilane compound, catalyst, and solvent used in the I raw material preparation step 9 and the III reconstruction step 11 are the same as those in the first embodiment, the description thereof is omitted.

  As described above, a silica dry gel having both strength and flexibility is obtained, and the acoustic matching member using the silica dry gel expands and contracts even if the bonded member expands and contracts due to temperature changes in the usage environment. Therefore, there is an effect of preventing damage to itself, and the ultrasonic transducer can operate stably in a wide temperature range.

(Embodiment 3)
FIG. 7 shows a cross-sectional view of the bending strength measuring jig 25 for silica dry gel. In the figure, a cylindrical silica gel 26 produced by the same method as in the first embodiment is placed on a measuring table 27 of a bending strength measuring jig 25, and a pressing rod 28 is moved vertically at a constant speed. Then, the bending strength at that time was measured. FIG. 8 shows the measurement results of the bending strength of the silica dry gel.

In the figure, the horizontal axis represents the density of the silica dry gel 26 sample, and the vertical axis represents the elastic modulus calculated from the bending strength of the silica dry gel 26 sample. In the same figure, a dotted line 29 is a silica dry gel sample prepared only with the organosilane compound described in the formula (1) described in the conventional example, and a solid line 30 is a silica dry gel imparting flexibility to the silica dry gel of the present invention. Gel samples are shown. Compared to the conventional example, the dry gel of the present invention has a small elastic modulus and is flexible. This flexibility is due to the fact that the silica dry gel follows the expansion and contraction even when the bonded member expands and contracts due to changes in temperature, etc., and therefore has the effect of preventing its own damage, and the ultrasonic vibrator is stable over a wide temperature range. Can operate.

(Embodiment 4)
FIG. 9 shows a cross-sectional view of the ultrasonic transducer 31 according to the fourth embodiment of the present invention, and FIG. 10 is a process diagram of the ultrasonic transducer 31. Hereinafter, the manufacturing process of the ultrasonic transducer 31 will be described. Step (a) is a step of forming the acoustic matching member 2 and is omitted because it is the same as in the first embodiment. The step (b) is a step of printing the adhesive as the joining member 4 on the surface of the electrode 33 formed of the baked silver of the piezoelectric body 32 and the top outer wall surface of the ceiling-like cylindrical metal case as the joined member 3. It is. Printing is not limited as long as the adhesive can be printed to a predetermined thickness such as screen printing, gravure printing, and transfer. The celestial cylindrical case is a metal case, and may be anything such as iron, brass, copper, aluminum, stainless steel, an alloy thereof, or a metal obtained by plating the surface of these metals.

  The piezoelectric body 32 printed with the adhesive as the joining member 4 is placed on the inner wall surface of the ceiling-shaped cylindrical metal case as the joined member 3, and the acoustic matching member 2 is opposed to the piezoelectric body 32 on the outer wall surface of the top. paste. In such a state, the adhesive is cured while applying pressure. The adhesive is not particularly limited, such as an epoxy resin, a phenol resin, or a cyanoacrylate resin.

  In the step (c), the dome-shaped cylindrical metal case joined by the adhesive and the terminal plate 36 having the conductive means 35 inserted are joined by welding. The terminal plate 36 includes an electrode terminal 37 and an electrode terminal 38 and is electrically insulated by a terminal plate insulating portion 39. The conductive means 35 is composed of an elastic body such as silicon rubber, butadiene rubber, or elastomer, and a conductive body, and electrically connects the electrode 34 and the electrode terminal 38. The electrode 33 and the covered cylindrical case which is the joined member 3 and the electrode terminal 37 are electrically connected.

  An inert gas was injected into the sealed space 40 formed by the heavenly cylindrical metal case and the terminal plate 36 when the celestial cylindrical metal case and the terminal plate 36 were welded to manufacture the ultrasonic transceiver 31. The inert gas is not limited as long as it is a gas that does not react with the silver electrode, such as helium gas and nitrogen gas. By inserting an inert gas into the celestial cylindrical case at the time of welding, the piezoelectric body 32 provided with the silver electrode is isolated from the external environment, the electrical connection is stabilized over a long period of time, and long-term reliability is ensured.

  In the ultrasonic vibrator configured as described above, since the acoustic matching member including the silica dried gel formed as described above is given flexibility, the piezoelectric body that is the bonded member 3 due to a temperature change is expanded and contracted. Even so, it is possible for the flexible acoustic matching member to expand and contract following this expansion and contraction, thereby preventing its own destruction. As a result, the ultrasonic transducer 1 of the present invention can operate stably over a wide temperature range and can be used over a long period of time.

  As described above, the ultrasonic transducer according to the present invention can impart flexibility to the silica dried gel used for the acoustic matching member. Therefore, even if the case expands or contracts due to temperature changes in the usage environment, the silica dry gel follows the expansion and contraction.Therefore, it has the effect of preventing its own damage, and the ultrasonic vibrator operates stably over a wide temperature range. Therefore, it can be applied to flow meters such as gas and water.

Sectional drawing of the ultrasonic transducer | vibrator in Embodiment 1 of this invention Manufacturing process diagram of silica dried gel in Embodiment 1 of the present invention Molecular arrangement conceptual diagram of organosilane compound in Embodiment 1 of the present invention Molecular arrangement conceptual diagram of organosilane compound in Embodiment 1 of the present invention Conceptual diagram of organosilane compound in silica dry gel production process in Embodiment 1 of the present invention Conceptual diagram of organosilane compound in silica dry gel production process in Embodiment 2 of the present invention Cross section of a jig for measuring the bending strength of a dried gel according to Embodiment 3 of the present invention The characteristic figure which shows the bending strength measurement result of the dry gel in Embodiment 3 of this invention Sectional drawing of the ultrasonic transducer | vibrator in Embodiment 4 of this invention Process drawing which shows the manufacturing method of the ultrasonic transducer | vibrator in Embodiment 4 of this invention. Cross-sectional view of a conventional ultrasonic transducer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic vibrator 2 Acoustic matching member 15 Non-hydrolyzable organic group 16 Silicon 17 Hydrolyzable organic group

Claims (6)

A hydrolyzable organic group and a non-hydrolyzable organic group directly bonded to the same silicon, and an acoustic matching member made of a silica-dried gel obtained by polymerizing and drying, and a piezoelectric body ,
The said organosilane compound is an ultrasonic transducer | vibrator containing the copolymer of the compound represented by at least one of Formula (5) and Formula (6), and Formula (7) .
Formula (5) CH2 = CR3 (COOR4)
Formula (6) CH2 = CR3 (COOR5)
Formula (7) CH2 = CR3 (COOR6)
However, R3 is a hydrogen atom and / or a methyl group, R4 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 9 carbon atoms, R5 is an epoxy group, a glycidyl group, or a hydrocarbon group containing at least one of them. At least one group selected from the group consisting of R6 is a hydrocarbon group containing an alkoxysilyl group and / or a halogenated silyl group. The ultrasonic transducer according to claim 1, further comprising a gel obtained by polymerizing and drying a compound represented by formula (1) or a partially hydrolyzed polymer of the compound represented by formula (1).
Formula (1) Si (OR1) 4 In the presence of a wet gel obtained by polymerizing a compound represented by the formula (1) or a partially hydrolyzed polymer of the compound represented by the formula (1), the hydrolyzable organic group and the non-hydrolyzable organic 3. The ultrasonic transducer according to claim 2, wherein an organosilane compound directly bonded to the same silicon is polymerized and dried. The organosilane compound in which the hydrolyzable organic group and the non-hydrolyzable organic group are directly bonded to the same silicon is 0.1% relative to the total of the compound represented by the formula (1) and its hydrolytic condensation polymer. The ultrasonic vibrator according to claim 2 or 3, wherein the weight is 10% by weight to 10% by weight. The ultrasonic transducer according to claim 1, wherein the organosilane compound is obtained by polymerizing a compound containing at least one of the formula (2) or the formula (3) to have a molecular weight of 200 or more.
Formula (2) R2Si (OR1) 3
Formula (3) (R2) 2Si (OR1) 2 The ultrasonic vibrator according to any one of claims 1 to 4, wherein the organosilane compound is a linear polysiloxane diol represented by the formula (4).
Formula (4) HO ((R2) 2SiO) nH

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