JP2018143703A - Resin material for acoustic wave probe, resin mixture for acoustic wave probe, acoustic lens, acoustic wave probe, acoustic wave measuring instrument, ultrasonograph, photoacoustic wave measuring instrument, and ultrasonic endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin sheet having excellent chemical resistance and further, reducing an acoustic wave attenuation even under high frequency (e.g., 10 MHz).SOLUTION: The resin material for acoustic wave probes is used, the resin material for acoustic wave probes formed by including a resin obtained by connecting a resin (a) including a structural unit having a fluorine atom, and a resin (b) including a structural unit having polysiloxane bond. A ratio of a content mass mb of the resin (b) to a content mass ma of the resin (a) is ma:mb=30:70-70:30, and a gel fraction is 80 mass% or more. The density is 1.05 g/cmor more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resin material for an acoustic wave probe, a resin mixture for an acoustic wave probe, an acoustic lens, an acoustic wave probe, an acoustic wave measuring device, an ultrasonic diagnostic device, a photoacoustic wave measuring device, and an ultrasonic endoscope.

  In an acoustic wave measuring apparatus, an acoustic wave probe that irradiates an object to be examined or a part (hereinafter also simply referred to as an object), receives a reflected wave (echo), and outputs a signal is used. The electric signal converted from the reflected wave received by the acoustic wave probe is displayed as an image. Thereby, the inside of the test object is visualized and observed.

As the acoustic wave, one having an appropriate frequency such as an ultrasonic wave and a photoacoustic wave is selected according to a test object and / or measurement conditions.
For example, the ultrasonic diagnostic apparatus transmits an ultrasonic wave toward the inside of the subject, receives the ultrasonic wave reflected by the tissue inside the subject, and displays it as an image. The photoacoustic wave measuring apparatus receives an acoustic wave radiated from the inside of the subject to be examined by the photoacoustic effect and displays it as an image. The photoacoustic effect means that when a test object is irradiated with an electromagnetic pulse such as visible light, near-infrared light, or microwave, the test object absorbs the electromagnetic wave, generates heat, and thermally expands. This is a phenomenon in which ultrasonic waves are typically generated.
Since the acoustic wave measuring device transmits and receives acoustic waves to and from a living body to be examined, requirements such as acoustic impedance matching with a living body (typically a human body) and reduction of acoustic wave attenuation are required. It is required to satisfy.

  For example, a probe for an ultrasonic diagnostic apparatus (also referred to as an ultrasonic probe), which is a kind of acoustic wave probe, includes a piezoelectric element that transmits and receives ultrasonic waves and an acoustic lens that is a part that contacts a living body. The ultrasonic wave oscillated from the piezoelectric element passes through the acoustic lens and enters the living body. If the difference between the acoustic impedance (density x speed of sound) of the acoustic lens and the acoustic impedance of the living body is large, the ultrasonic waves are reflected on the surface of the living body, so that the ultrasonic waves are not efficiently incident on the living body. Therefore, it is difficult to obtain a good resolution. In order to transmit and receive ultrasonic waves with high sensitivity, it is desired that the acoustic lens has a small ultrasonic attenuation.

For this reason, as one of the materials of the acoustic lens, a silicone resin that is close to the acoustic impedance of a living body (1.4 to 1.7 × 10 ⁶ kg / m ² / sec in the case of a human body) and has a small ultrasonic attenuation amount is used. It is used. Further, the ultrasonic probe is used repeatedly. Therefore, in particular, an acoustic lens that comes into contact with a subject to be examined needs to be sterilized with a chemical every time it is used, and chemical resistance is required. For example, Patent Document 1 discloses an acoustic lens capable of maintaining wear resistance while suppressing the influence on characteristics such as acoustic characteristics and chemical resistance, and is a fluorine-based adhesive for a silicone substrate. An acoustic lens of an ultrasonic probe formed of a material containing resin particles is described.

JP 2012-95178 A

  The acoustic lens described in Patent Document 1 has a certain effect in improving chemical resistance. However, since the acoustic lens is a simple mixture of a silicone resin and a fluororesin, the silicone resin and the fluororesin are not compatible with each other and the acoustic wave attenuation is increased.

In view of the above situation, the present invention is formed into a sheet shape, so that the acoustic impedance is close to the value of a living body, excellent in chemical resistance, and further, the acoustic wave attenuation is reduced even at a high frequency (for example, 10 MHz). It is an object of the present invention to provide a resin material for an acoustic wave probe that can provide a resin sheet.
Moreover, this invention makes it a subject to provide the resin mixture for acoustic wave probes used for preparation of said resin material for acoustic wave probes.
The present invention also provides an acoustic lens, an acoustic probe, an acoustic wave measuring device, an ultrasonic diagnostic device, a photoacoustic wave measuring device, and an ultrasonic endoscope using the above acoustic wave resin material as a constituent material. The task is to do.

The above problem has been solved by the following means.
<1>
A resin material for an acoustic wave probe comprising a resin in which a resin (a) containing a structural unit having a fluorine atom and a resin (b) containing a structural unit having a polysiloxane bond are bonded.
<2>
The resin material for an acoustic wave probe according to <1>, wherein the ratio of the mass mb of the resin (b) to the mass ma of the resin (a) is ma: mb = 30: 70 to 70:30.
<3>
Resin (a) is a polyvinylidene fluoride, a polymer containing a fluorinated styrene structural unit, a polymer containing a fluorinated alkyl (meth) acrylate structural unit, a polymer containing a fluorinated alkyl group-containing styrene structural unit, and a fluororubber The resin material for acoustic wave probes according to <1> or <2>, which is at least one of the above.
<4>
The resin material for an acoustic wave probe according to any one of <1> to <3>, wherein the gel fraction is 80% by mass or more.
<5>
The resin material for acoustic wave probes according to any one of <1> to <4>, wherein the density is 1.05 g / cm ³ or more.
<6>
<1> to <5>, comprising a resin (a) containing a structural unit having a fluorine atom, a resin (b) containing a structural unit having a polysiloxane bond, and a radical generator. The resin mixture for acoustic wave probes used for the resin material for acoustic wave probes of description.
<7>
An acoustic lens comprising the resin material for an acoustic wave probe according to any one of <1> to <5>.
<8>
An acoustic wave probe having the acoustic lens according to <7>.
<9>
An acoustic wave measuring apparatus provided with the acoustic wave probe as described in <8>.
<10>
An ultrasonic diagnostic apparatus comprising the acoustic wave probe according to <8>.
<11>
A photoacoustic wave measuring apparatus provided with the acoustic lens as described in <7>.
<12>
An ultrasonic endoscope comprising the acoustic lens according to <7>.

In this specification, when there are a plurality of substituents, linking groups, repeating structures, etc. (hereinafter referred to as substituents, etc.) indicated by a specific symbol, or when a plurality of substituents etc. are specified simultaneously, there is a special notice. As long as there is no, each substituent etc. may mutually be same or different. The same applies to the definition of the number of substituents and the like. Further, when a plurality of substituents and the like are close to each other (especially when they are adjacent to each other), they may be connected to each other to form a ring unless otherwise specified. Further, a ring such as an aliphatic ring, an aromatic ring, or a hetero ring may be further condensed to form a condensed ring.
In the present specification, when the number of carbon atoms of a certain group is defined, this number of carbons means the total number of carbon atoms in the group. That is, when this group is a form further having a substituent, it means the total number of carbon atoms including this substituent.
Moreover, the group (for example, alkyl group) specified by each group may further have a substituent. Further, “Si—H group” means a group having three bonds in addition to —H on a silicon atom, but the description of these bonds is omitted and the notation is simplified.
Further, in the present specification, “to” is used in the sense of including the numerical values described before and after it as the lower limit and the upper limit.

In addition, unless otherwise indicated, the mass average molecular weight in this specification is a measurement value (polystyrene conversion) of gel permeation chromatography (GPC).
Specifically, the GPC apparatus HLC-8220 (manufactured by Tosoh Corporation) is prepared, the tetrahydrofuran (Wako Pure Chemical Industries, Ltd.) is used as an eluent, and TSKgel (registered trademark) G3000HXL + TSKgel (registered) is used as a column. (Trademark) G2000HXL can be used and measured using an RI detector under conditions of a temperature of 23 ° C. and a flow rate of 1 mL / min.

  The resin sheet produced using the resin material for acoustic wave probes of the present invention has an acoustic impedance close to that of a living body, excellent chemical resistance, and the acoustic wave attenuation is reduced even at high frequencies. In addition, the resin sheet prepared using the resin material for acoustic wave probes prepared using the resin mixture for acoustic wave probes of the present invention has an acoustic impedance close to that of a living body, excellent chemical resistance, and even at high frequencies. The acoustic wave attenuation is reduced. The acoustic lens, acoustic wave probe, acoustic wave measuring device, ultrasonic diagnostic device, photoacoustic wave measuring device, and ultrasonic endoscope of the present invention contain the resin material for an acoustic wave probe having the above-described excellent performance. .

It is a perspective transmissive view about an example of a convex type ultrasonic probe which is one mode of an acoustic wave probe.

<< Resin material for acoustic wave probe >>
The resin material for an acoustic wave probe of the present invention contains a resin in which a resin (a) containing a structural unit having a fluorine atom and a resin (b) containing a structural unit having a polysiloxane bond are bonded. Hereinafter, the “resin material for acoustic wave probes” is also simply referred to as “resin material”. “Resin (a) containing a structural unit having a fluorine atom” is also simply referred to as “resin (a)” or “fluororesin (a)”. The resin (b) containing a structural unit having a polysiloxane bond is also simply referred to as “resin (b)” or “silicone resin (b)”. A resin in which “a resin (a) containing a structural unit having a fluorine atom and a resin (b) containing a structural unit having a polysiloxane bond” is bonded is also simply referred to as a composite resin.
The resin material for an acoustic wave probe of the present invention may be in the form of a composite resin, or in addition to the composite resin, filler, catalyst, solvent, dispersant, pigment, dye, antistatic agent, flame retardant, thermal conductivity improvement It may be in a form containing a conventional component or an optional component that exhibits an additional action such as an agent. When the resin material for an acoustic wave probe of the present invention is composed of two or more kinds of components, it is usually preferable to have a composition form in which the respective components are uniformly mixed.
The shape of the acoustic wave probe resin material of the present invention is not particularly limited. It may be mixed with a solvent or the like to have fluidity, or may be in the form of pellets.

The resin material for an acoustic wave probe of the present invention is formed by molding this resin material into a sheet shape, thereby reducing acoustic impedance close to the value of a living body, reduction of acoustic wave attenuation (especially acoustic wave attenuation at high frequencies) and chemical resistance. Therefore, it is possible to obtain a resin sheet that is excellent in any of the characteristics, and it can be suitably used as a constituent material of members constituting the acoustic wave probe. The reason for this is not clear, but the bonding between the resin (a) and the resin (b) not only suppresses phase separation of the two resins, but also causes crystallization of the resin (a). By being suppressed, it is considered that sound wave scattering is suppressed and acoustic wave sensitivity is improved.
Hereinafter, the resin sheet obtained from the resin material for acoustic wave probes of the present invention is also referred to as “resin sheet for acoustic wave probes” to “resin sheet”.

1. Composite resin in which resin (a) containing structural unit having fluorine atom and resin (b) containing structural unit having polysiloxane bond are combined The composite resin used in the resin material of the present invention is resin (a) and resin As long as it is a compound in which (b) is bound, it is not particularly limited.

(1) Resin containing a structural unit having a fluorine atom (a)
Resin (a) containing the structural unit which has a fluorine atom is not specifically limited as long as it has a structural unit which has a fluorine atom as a structural unit which comprises resin.
Examples of the structural unit having a fluorine atom include the following three structures k-1 to k-3.

In the above formula, R ^{1 to} R ⁹ represent a hydrogen atom, a halogen atom or an alkyl group, and R ^f1 and R ^f2 represent an alkyl group substituted with a fluorine atom or an aryl group substituted with a fluorine atom. X represents —O— or —C (═O) O—.

The halogen atom in R ^{1 to} R ⁹ is preferably a fluorine atom, a chlorine atom or a bromine atom, more preferably a fluorine atom or a chlorine atom, and even more preferably a fluorine atom.
Alkyl group in R ¹ to R ⁹ has a carbon number of 1 to 10, more preferably 1 to 4, 1 or 2 is more preferred. Examples include methyl, ethyl, propyl, butyl and hexyl.
This alkyl group may be substituted with a fluorine atom. For the alkyl group substituted with a fluorine atom, the fluorination rate calculated from the following formula (1) is preferably 0.10 to 1, and more preferably 0.60 to 1. Of these, a perfluoroalkyl group having a fluorination rate of 1 is most preferable.
Fluorination rate = number of fluorine atoms in alkyl group substituted with fluorine atoms /
Number of hydrogen atoms in alkyl group before substitution with fluorine atom Formula (1)

R ^{1 to} R ³ are preferably a halogen atom or a hydrogen atom, more preferably a fluorine atom or a chlorine atom, and even more preferably a fluorine atom.
R ⁴ , R ⁵ , R ⁷ and R ⁸ are preferably a hydrogen atom or a halogen atom, more preferably a hydrogen atom or a fluorine atom, and even more preferably a hydrogen atom.
R ⁶ and R ⁹ are preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom or a methyl group.

The aspect of the alkyl group substituted with the fluorine atom in the above R ^{1 to} R ⁶ is preferably applied to the alkyl group substituted with the fluorine atom in R ^f1 and R ^f2 .
R ^f1 and ring configuration the number of carbon atoms of the aryl group substituted with a fluorine atom in ^{R f2} is 6-12 preferably 6 to 10 is more preferable. Specific examples include phenyl, naphthyl and anthracenyl substituted with a fluorine atom. The fluorination rate calculated from the following formula (2) for the aryl group substituted with a fluorine atom is preferably 0.10 to 1, and more preferably 0.60 to 1. Of these, a perfluoroaryl group having a fluorination rate of 1 is most preferable.
Fluorination rate = number of fluorine atoms of aryl group substituted with fluorine atoms /
Number of hydrogen atoms of aryl group before substitution with fluorine atom Formula (2)

The fluororesin (a) may contain one type or two or more types of structural units having the fluorine atom, and may contain other structural units other than the structural unit having the fluorine atom (hereinafter referred to as “other units”). It may be referred to as “structural unit”.
In addition, content of the structural unit which has the said fluorine atom among all the structural units which comprise a fluororesin (a) is although it does not specifically limit, 10-90 mass% is preferable and 30-70 mass% is more preferable.

Other structural units are not particularly limited, and examples thereof include an olefin component, a (meth) acrylic acid component, and a (meth) acrylic acid alkyl ester component.
Olefin means a hydrocarbon composed of carbon atoms and hydrogen atoms and having at least one polymerizable unsaturated double bond. Specific examples include alkenes such as ethene, isopropene, and isobutene, and vinyl compounds such as styrene.
The alkyl in the (meth) acrylic acid alkyl ester preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and still more preferably 1 to 3 carbon atoms.

The fluorine content in the fluororesin (a) (the number of moles of fluorine atoms in 1 g of the fluororesin (a)) is not particularly limited as long as the fluorine content in the composite resin satisfies the preferred range described below.
Specifically, 0.002 to 0.200 mol / g is preferable, 0.006 to 0.100 mol / g is more preferable, and 0.010 to 0.040 mol / g is more preferable.

  From the viewpoint of chemical resistance and ease of mixing with a silicone resin, the mass average molecular weight of the fluororesin (a) is preferably 5,000 or more, more preferably 10,000 to 500,000, and more preferably 30,000 to 200. Is more preferred.

The fluororesin (a) may have a radical reactive group. The radical reactive group is not particularly limited as long as it has a polymerizable carbon-carbon double bond, and examples thereof include vinyl, allyl, (meth) acryl, and styryl.
Although this radical reactive group may have either a structural unit having a fluorine atom or another structural unit, it is preferable that the other structural unit has from the viewpoint of ease of synthesis. As a constituent component constituting the other structural unit having a radical reactive group, a (meth) acrylic acid alkyl ester having an alkyl portion having a radical reactive group is preferable, and examples thereof include allyl (meth) acrylate.
When the fluororesin (a) has a radical reactive group, the reaction with the silicone resin (b) described later is more likely to proceed, and a bond is more formed between the fluororesin (a) and the silicone resin (b). In view of acoustic wave sensitivity, the gel fraction can be further improved.

  Specific examples of the fluororesin (a) include polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene, chlorotrifluoroethylene-ethylene copolymer, polytetrafluoroethylene, tetrafluoroethylene-fluorinated alkyl vinyl ether copolymer. , Tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, polymer containing a fluorinated styrene structural unit, polymer containing a fluorinated alkyl (meth) acrylate structural unit, containing a fluorinated alkyl group Examples thereof include polymers containing styrene structural units and fluororubber.

Here, fluororubber means what shows the property of rubber among fluororesins. Examples include vinylidene fluoride rubber, tetrafluoroethylene-propylene rubber, and tetrafluoroethylene-fluorinated alkyl vinyl ether rubber, with vinylidene fluoride rubber being preferred.
The vinylidene fluoride rubber includes a rubber that is a copolymer of vinylidene fluoride and a structural unit selected from tetrafluoroethylene and hexafluoropropylene. Specific examples include a vinylidene fluoride-hexafluoropropylene copolymer and a vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer.

The polymer containing a fluorinated styrene structural unit means a polymer containing, as a structural unit, styrene in which at least one hydrogen atom on a benzene ring in styrene is substituted with a fluorine atom. As the fluorination rate, the description of the fluorination rate in the aryl group of R ^f2 can be preferably applied, and among them, pentafluorostyrene is preferable.
The polymer containing a fluorinated alkyl (meth) acrylate structural unit contains, as a structural unit, an alkyl (meth) acrylate in which at least one hydrogen atom of the alkyl group in the alkyl (meth) acrylate is substituted with a fluorine atom. It means a polymer. As the fluorination rate, the description of the fluorination rate in the alkyl group of R ^f1 can be preferably applied, and trifluoroethyl (meth) acrylate can be preferably applied.
The polymer containing a fluorinated alkyl group-containing styrene structural unit means a polymer containing, as a structural unit, styrene in which at least one hydrogen atom on the benzene ring in styrene is substituted with a fluorinated alkyl group. As the fluorination rate of the fluorinated alkyl group, the description of the fluorination rate in the alkyl group of R ^f1 can be preferably applied, and examples thereof include 4-trifluorostyrene and 3,5-ditrifluorostyrene.
The polymer containing the fluorinated styrene structural unit, the polymer containing the fluorinated alkyl (meth) acrylate structural unit, and the polymer containing the fluorinated alkyl group-containing styrene structural unit are homopolymers and copolymers. Either may be sufficient. In the case of a copolymer, the structural unit constituting the copolymer is preferably the other structural unit having the radical reactive group, and more preferably a (meth) acrylic acid alkyl ester in which the alkyl part has a radical reactive group. .

  The fluororesin (a) includes polyvinylidene fluoride (PVDF), a polymer containing a fluorinated styrene structural unit, a polymer containing a fluorinated alkyl (meth) acrylate structural unit, and a polymer containing a fluorinated alkyl group-containing styrene structural unit. At least one selected from a coalescence and a fluororubber is preferable. From the viewpoint of chemical resistance and reactivity with a silicone resin during mixing, a polymer containing a fluorinated styrene structural unit, a fluorinated alkyl (meth) acrylate structural unit At least one selected from a polymer containing fluorinated alkyl group-containing styrene structural units and a fluororubber, a polymer containing fluorinated styrene structural units, and a fluorinated alkyl (meth) acrylate structural unit. More preferably, at least one selected from a polymer and fluororubber is included. More preferably containing rubbers.

(2) Resin (b) containing a structural unit having a polysiloxane bond
The resin (b) containing a structural unit having a polysiloxane bond is not particularly limited as long as it has a structural unit having a polysiloxane bond as a structural unit constituting the resin. The polysiloxane bond may be introduced into any of the main chain and / or the side chain in the structural unit, but is preferably introduced into the main chain.
The silicone having a polysiloxane bond is composed of a first silane (for example, a first silicon-containing group such as a first alkoxysilyl group or a first hydroxysilyl group) and a second silane (for example, a second alkoxysilyl group or a second hydroxy). From a reaction with a second silicon-containing group, such as a silyl group.
The silicone resin (b) used in the present invention is not particularly limited, and examples thereof include silicone rubber and silicone resin, and silicone rubber is preferably used.

  Silicone rubber is obtained by curing a silicone rubber composition using a curing agent. A normal thing can be used as this hardening | curing agent. For example, when curing by a hydrosilylation reaction, a platinum group metal catalyst is used as a curing agent for a silicone rubber composition containing a polyorganosiloxane having a vinyl group and a polyorganosiloxane having a Si-H group, In the case of peroxide crosslinking, a peroxide is used as a curing agent.

  Specific examples of the silicone resin (b) include KE series manufactured by Shin-Etsu Chemical Co., Ltd., TSE series manufactured by Momentive, and ELASTSIL series manufactured by Asahi Kasei Wacker Silicone. Specific examples of these are shown below by product names.

KE series manufactured by Shin-Etsu Chemical Co., Ltd. KE931-U, KE941-U, KE951-U, KE961-U, KE971-U, KE981-U, KE961T-U, KE971T-U, KE871C-U, KE742-U, KE752- U, KE762-U, KE772-U, KE782-U, KE850-U, KE870-U, KE880-U, KE890-U
・ Momentive TSE series TSE2267U, TSE2277U, TSE2287U, TSE2297U
ELASTSIL series EL1301, EL1401, EL1501, EL1601, EL1701, EL1801, EL4300, EL4406, EL4500, EL4610, EL4710, EL4810, EL3530, EL3630, EL3730, EL7101, EL7153, EL7210, R401 / 10-90 manufactured by Asahi Kasei Wacker Silicone

As the silicone resin (b), it is also preferable to use the polyorganosiloxane (A) having the vinyl group before curing. Since the polyorganosiloxane (A) has a vinyl group, the reaction between the fluororesin (a) and the silicone resin (b) easily proceeds, and the gel fraction of the composite resin obtained by the reaction is further improved. This is preferable from the viewpoint of wave sensitivity.
In addition, the silicone resin (b) may be synthesized by a reaction between the polyorganosiloxane (A) having the following vinyl group and the polyorganosiloxane (B) having two or more Si—H groups in the molecular chain. it can. In this case, it is preferable that a vinyl group remains in the silicone resin.

<Polyorganosiloxane having vinyl group (A)>
The polyorganosiloxane (A) having a vinyl group (hereinafter also simply referred to as polyorganosiloxane (A)) has two or more vinyl groups in the molecular chain.
As the polyorganosiloxane (A) having a vinyl group, for example, a polyorganosiloxane (a) having vinyl groups at least at both ends of the molecular chain (hereinafter, also simply referred to as polyorganosiloxane (a)), or in the molecular chain. And polyorganosiloxane (b) having at least two —O—Si (CH ₃ ) ₂ (CH═CH ₂ ) (hereinafter also simply referred to as polyorganosiloxane (b)). Among these, polyorganosiloxane (a) having vinyl groups at least at both ends of the molecular chain is preferable.
The polyorganosiloxane (a) is preferably linear, and the polyorganosiloxane (b) is a polyorganosiloxane in which —O—Si (CH ₃ ) ₂ (CH═CH ₂ ) is bonded to Si atoms constituting the main chain. Organosiloxane (b) is preferred.

  The polyorganosiloxane (A) having a vinyl group is hydrosilylated by reaction with a polyorganosiloxane (B) having two or more Si—H groups in the presence of a platinum catalyst. A crosslinked structure is formed by this hydrosilylation reaction (addition curing reaction).

The vinyl group content of the polyorganosiloxane (A) is not particularly limited. From the viewpoint of forming a sufficient network with each component contained in the composition for acoustic wave probes, for example, the content of vinyl groups is preferably 0.01 to 5 mol%, and 0.05 to 2 mol. % Is more preferable.
The polyorganosiloxane (A) preferably has a phenyl group, and the content of the phenyl group is not particularly limited. From the viewpoint of mechanical strength when a silicone resin for acoustic wave probes is used, for example, the phenyl group content is preferably 1 to 80 mol%, more preferably 2 to 40 mol%.

Here, the content of the vinyl group is the mol% of the vinyl group-containing siloxane unit when all the units constituting the polyorganosiloxane (A) are 100 mol%, and the Si—O unit constituting the main chain. And when all the Si atoms of the terminal Si are substituted with at least one vinyl group, it becomes 100 mol%.
Similarly, the phenyl group content is the mol% of the phenyl group-containing siloxane unit when the total units constituting the polyorganosiloxane (A) are 100 mol%, and the Si—O unit constituting the main chain and When all the Si atoms of the terminal Si are substituted with at least one phenyl group, it becomes 100 mol%.
In addition, a unit means the Si-O unit which comprises a principal chain, and terminal Si.

  The degree of polymerization and specific gravity are not particularly limited. The degree of polymerization is preferably 200 to 3000, more preferably 400 to 2000, and the specific gravity is 0.9 to 1 from the viewpoint of improving the mechanical strength, hardness, chemical stability, etc. of the silicone resin for acoustic wave probes obtained. .1 is preferred.

  The weight average molecular weight of the polyorganosiloxane having a vinyl group is preferably 10,000 to 200,000, more preferably 20,000 to 200,000, from the viewpoint of mechanical strength, hardness, and ease of processing. 000 to 150,000 is more preferable, and 40,000 to 120,000 is particularly preferable.

Kinematic viscosity at 25 ° C. is preferably ^{1 × 10 -5 ~10m 2 / s} , more preferably ^{1 × 10 -4 ~1m 2 / s} , 1 × 10 -3 ~0.5m 2 / s is more preferable.
The kinematic viscosity can be determined according to JIS Z8803 by measuring at a temperature of 23 ° C. using an Ubbelohde viscometer (for example, trade name SU, manufactured by Shibata Chemical Co., Ltd.).

  The polyorganosiloxane (a) having vinyl groups at least at both ends of the molecular chain is preferably a polyorganosiloxane represented by the following general formula (A).

In the general formula (A), R ^a1 represents a vinyl group, and R ^a2 and R ^a3 each independently represents an alkyl group, a cycloalkyl group, an alkenyl group, or an aryl group. x1 and x2 each independently represents an integer of 1 or more. Here, each group of R ^a2 and R ^a3 may be further substituted with a substituent.

1-10 are preferable, as for carbon number of the alkyl group in R ^{< a2>} and R ^<a3> , 1-4 are more preferable, 1 or 2 is more preferable, and 1 is especially preferable. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-hexyl, n-octyl, 2-ethylhexyl and n-decyl.

3-10 are preferable, as for carbon number of the cycloalkyl group in R ^{< a2>} and R ^<a3 >, 5-10 are more preferable, and 5 or 6 is still more preferable. The cycloalkyl group is preferably a 3-membered ring, 5-membered ring or 6-membered ring, more preferably a 5-membered ring or 6-membered ring. Examples of the cycloalkyl group include cyclopropyl, cyclopentyl, and cyclohexyl.

2-10 are preferable, as for carbon number of the alkenyl group in R ^{< a2>} and R ^<a3 >, 2-4 are more preferable, and 2 is more preferable. Examples of the alkenyl group include vinyl, allyl, and butenyl.

6-12 are preferable, as for carbon number of the aryl group in R ^{< a2>} and R ^<a3 >, 6-10 are more preferable, and 6-8 are more preferable. Examples of the aryl group include phenyl, tolyl, and naphthyl.

These alkyl group, cycloalkyl group, alkenyl group and aryl group may have a substituent. Examples of such a substituent include a halogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a silyl group, and a cyano group.
Examples of the group having a substituent include a halogenated alkyl group.

R ^a2 and R ^a3 are preferably an alkyl group, an alkenyl group or an aryl group, more preferably an alkyl group having 1 to 4 carbon atoms, a vinyl group or a phenyl group, and further preferably a methyl group, a vinyl group or a phenyl group.
In particular, R ^a2 is preferably a methyl group, and R ^a3 is particularly preferably a phenyl group. More preferably, both R ^{a3 in} the repetition of x2 are phenyl groups.

x1 is preferably an integer of 1 to 3000, and more preferably an integer of 5 to 1000.
x2 is preferably an integer of 1 to 3000, and more preferably an integer of 40 to 1000.

Polyorganosiloxane having vinyl groups at least at both ends of the molecular chain is, for example, a trade name, DMS series (for example, DMS-V31, DMS-V31S15, DMS-V33, DMS-V35, DMS-V35R, DMS, manufactured by Gelest). -V41, DMS-V42, DMS-V46, DMS-V51, DMS-V52), product names made by Gelest, PDV series (for example, PDV-0341, PDV-0346, PDV-0535, PDV-0541, PDV- 1631, PDV-1635, PDV-1641, PDV-2335, PMV-9925, PVV-3522, FMV-4031, and EDV-2022).
In addition, since DMS-V31S15 is previously blended with fumed silica, kneading with a special apparatus is unnecessary.

  As the polyorganosiloxane (A) having a vinyl group, only one kind may be used alone, or two or more kinds may be used in combination.

<Polyorganosiloxane (B) having two or more Si-H groups in the molecular chain>
The polyorganosiloxane (B) having two or more Si-H groups in the molecular chain (hereinafter also simply referred to as polyorganosiloxane (B)) has two or more Si-H groups in the molecular chain. .
By having two or more Si—H groups in the molecular chain, a polyorganosiloxane having at least two polymerizable unsaturated groups can be crosslinked.

The polyorganosiloxane (B) has a linear structure and a branched structure, and a linear structure is preferable.
The mass average molecular weight of the linear structure is preferably from 500 to 100,000, more preferably from 1,500 to 50,000, from the viewpoint of mechanical strength and hardness.

The polyorganosiloxane (B) preferably has a phenyl group, and the content of the phenyl group is not particularly limited. From the viewpoint of mechanical strength when a silicone resin for an acoustic wave probe is used, it is, for example, 1 to 80 mol%, preferably 10 to 60 mol%.
Here, the content of the phenyl group is a content calculated by replacing the polyorganosiloxane (A) with the polyorganosiloxane (B) in the content of the phenyl group in the polyorganosiloxane (A).

It is preferable that both the polyorganosiloxanes (A) and (B) have a phenyl group in order to improve compatibility.
Since the silicone resin (b) has a bulky phenyl group, the speed of sound can be increased and the hardness and specific gravity can be increased. Therefore, the acoustic impedance can be increased efficiently. As a result, the amount of zinc oxide added can be reduced, and the acoustic wave sensitivity can be maintained high.

  The polyorganosiloxane (B) having a linear structure having two or more Si-H groups in the molecular chain is preferably a polyorganosiloxane represented by the following general formula (B).

In the general formula (B), R ^b1 and R ^b2 each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or —O—Si (R ^b5 ) ₂ (R ^b4 ). R ^b4 and R ^b5 each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group. R ^b3 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, or —O—Si (R ^b7 ) ₂ (R ^b6 ). R ^b6 and R ^b7 each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group or an aryl group. y1 represents an integer of 0 or more, and y2 represents an integer of 1 or more. Here, each group of R ^{b1 to} R ^b7 may be further substituted with a substituent. However, it has two or more Si-H groups in the molecular chain.

The alkyl group, cycloalkyl group and aryl group in R ^b1 and R ^{b2 have the same meanings as} the alkyl group, cycloalkyl group and aryl group in R ^a2 and R ^a3 , and the preferred ranges are also the same. The alkyl group, cycloalkyl group, alkenyl group and aryl group in R ^{b3 have the same meanings as} the alkyl group, cycloalkyl group, alkenyl group and aryl group in R ^a2 and R ^a3 , and the preferred ranges are also the same.

The alkyl group, cycloalkyl group and aryl group in R ^b4 and R ^b5 of —O—Si (R ^b5 ) ₂ (R ^b4 ) have the same ^{meanings as} the alkyl group, cycloalkyl group and aryl group in R ^b1 and R ^b2 . The preferred range is also the same.

The alkyl group, cycloalkyl group, alkenyl group and aryl group in R ^b6 and R ^b7 of —O—Si (R ^b7 ) ₂ (R ^b6 ) are the same as the alkyl group, cycloalkyl group, alkenyl group and aryl group in R ^b3 . It is synonymous and the preferable range is also the same.

R ^b1 and R ^b2 are a hydrogen atom, an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms, more preferably methyl), an aryl group (preferably phenyl), or —O—Si (R ^b5 ) ₂ (R ^b4 ). (preferably _{-O-Si (CH 3) 2} H) is preferably a hydrogen atom, more preferably an alkyl group or an aryl group, a hydrogen atom or an alkyl group is particularly preferred.
R ^b3 represents a hydrogen atom, an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms, more preferably methyl), an alkenyl group (preferably vinyl), an aryl group (preferably phenyl), or —O—Si (R ^b7 ). ₂ (R ^b6 ) (preferably —O—Si (CH ₃ ) ₂ H) is preferable, and a hydrogen atom or an aryl group is more preferable.

When R ^b3 is a phenyl group, R ^b1 is preferably a hydrogen atom, more preferably R ^b1 is a hydrogen atom, and it is more preferable that the following condition is satisfied.
1) One R ^{b2 in} the repetition of y1 is a hydrogen atom, the remaining R ^b2 is an alkyl group, and R ^{b2 in} the repetition of y2 is an alkyl group, and R ^b3 is a phenyl group 2) y1 is 0, R ^{b2 in} the repetition of y2 is an alkyl group, R ^b3 is a phenyl group 3) y1 is 0, and R ^{b2 in} the repetition of y2 is —O—Si (R ^b5 ) ₂ (R ^b4 ) in ^{still R b3} is a phenyl group, in the above ^3), when in ^{R b4} is a hydrogen atom, and ^{R b5} is an alkyl group, in which preferable.

y1 is preferably an integer of 0 to 2000, more preferably an integer of 0 to 50, and still more preferably an integer of 0 to 30.
y2 is preferably an integer of 2 to 2000, more preferably an integer of 2 to 50, and still more preferably an integer of 2 to 30.
y1 + y2 is preferably an integer of 5 to 2000, more preferably an integer of 7 to 1000, still more preferably 10 to 50, and particularly preferably an integer of 15 to 30.

As a combination of R ^{b1 to} R ^b3 , R ^b1 is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ^b2 is an alkyl group having 1 to 4 carbon atoms, and R ^b3 is a combination of hydrogen atoms, and R ^b1 is A combination of an alkyl group having 1 to 4 carbon atoms, R ^b2 being an alkyl group having 1 to 4 carbon atoms, and R ^b3 being a hydrogen atom is more preferable.
In this preferable combination, the content of the hydrosilyl group represented by y2 / (y1 + y2) is preferably more than 0.1 and 1.0 or less, more preferably more than 0.2 and 1.0 or less, more preferably 0.4 And more preferably 1.0 or less.
Here, when any of R ^{b1 to} R ^b3 is a phenyl group, y2 / (y1 + y2) is particularly preferable, and when any of R ^{b1 to} R ^b3 is not a phenyl group, y2 / (y1 + y2) is , More than 0.4 and less than 0.6 is particularly preferable.

The polyorganosiloxane (B) having a linear structure is, for example, a methylhydrosiloxane-dimethylsiloxane copolymer (trimethylsiloxane terminated) manufactured by Gelest, HMS-064 (MeHSiO: 5-7 mol%), HMS- 082 (MeHSiO: 7-8 mol%), HMS-301 (MeHSiO: 25-30 mol%), HMS-501 (MeHSiO: 50-55 mol%), HPM-502 (MeHSiO: MeHSiO: methylhydrosiloxane-phenylmethylsiloxane copolymer) 45-50 mol%) and HMS-991 (MeHSiO: 100 mol%) which is a methylhydrosiloxane polymer.
Here, mol% of MeHSiO is synonymous with y2 / (y1 + y2) × 100.

The branched polyorganosiloxane (B) having two or more Si—H groups in the molecular chain has a branched structure and two or more hydrosilyl groups (Si—H groups).
The specific gravity is preferably 0.9 to 0.95.
The branched structure polyorganosiloxane (B) is preferably represented by the following average composition formula (b).

Average composition formula (b): [H _a (R ^b8 ) _3-a SiO _1/2 ] _y3 [SiO _4/2 ] _y4

Here, R ^b8 represents an alkyl group, a cycloalkyl group, an alkenyl group or an aryl group, a represents 0.1 to 3, and y3 and y4 each independently represents an integer of 1 or more.

The alkyl group, cycloalkyl group, alkenyl group and aryl group in R ^{b8 have the same meanings as} the alkyl group, cycloalkyl group, alkenyl group and aryl group in R ^a2 and R ^a3 , and the preferred ranges are also the same.
a is preferably 1.
The content of the hydrosilyl group represented by a / 3 is preferably more than 0.1 and less than 0.6, more preferably more than 0.1 and less than 0.4.

On the other hand, when the polyorganosiloxane (B) having a branched structure is represented by a chemical structural formula, a polyorganosiloxane in which —O—Si (CH ₃ ) ₂ (H) is bonded to Si atoms constituting the main chain is preferable. Those having a structure represented by the following general formula (Bb) are more preferable.

  In the general formula (Bb), * means that it is bonded to at least a Si atom of siloxane.

Examples of the branched polyorganosiloxane (B) include HQM-107 (trade name, manufactured by Gelest, hydrogenated Q resin), HDP-111 (trade name, manufactured by Gelest, polyphenyl- (dimethylhydroxy) siloxane. (Hydrogen end), [(HMe ₂ SiO) (C ₆ H ₅ Si) O]: 99-100 mol%).

  The polyorganosiloxane (B) having two or more Si—H groups in the molecular chain may be used alone or in combination of two or more. Further, a linear polyorganosiloxane (B) and a branched polyorganosiloxane (B) may be used in combination.

The silicone resin (b) preferably has a radical reactive group. The radical reactive group is not particularly limited as long as it has a polymerizable carbon-carbon double bond, and examples thereof include vinyl and allyl.
When the silicone resin (b) has a radical reactive group, the reaction with the aforementioned fluororesin (a) is more likely to proceed, and a bond is more formed between the fluororesin (a) and the silicone resin (b). In view of acoustic wave sensitivity, the gel fraction can be further improved.
Therefore, the silicone resin (b) is preferably a polyorganosiloxane (A) having a vinyl group or a silicone resin synthesized using a polyorganosiloxane (A) having a vinyl group. The polyorganosiloxane (A) having a group is more preferable.

  From the viewpoint of reducing the acoustic attenuation, the mass average molecular weight of the silicone resin (b) is preferably 1000 or more, more preferably 10,000 to 1,000,000, and even more preferably 50,000 to 500,000.

(3) Composite resin In the composite resin, the ratio of the mass mb of the silicone resin (b) to the mass ma of the fluororesin (a) is preferably ma: mb = 30: 70 to 70:30, 35:65 -65: 35 is more preferable, and 40: 60-60: 40 is still more preferable. By setting the content mass ratio within the above range, the compatibility between the fluororesin (a) and the silicone resin (b) can be further increased, and the acoustic wave sensitivity of the resin sheet obtained from the resin material of the present invention can be further increased. it can.
Here, the content mass ma of the fluororesin (a) and the content mass mb of the silicone resin (b) in the composite resin can be calculated from, for example, the charged amount (mass ratio) at the time of synthesis.

  The fluorine content in the composite resin is preferably 0.001 to 0.100 mol / g, more preferably 0.003 to 0.050 mol / g, and still more preferably 0.005 to 0.020 mol / g. By setting the fluorine content within the above range, the compatibility of the fluororesin (a) and the silicone resin (b) can be further increased, and the acoustic wave sensitivity of the resin sheet obtained from the resin material of the present invention can be further increased. . Moreover, since the polymer density is relatively high, the acoustic impedance of the resin sheet obtained from the resin material of the present invention can be further increased. Here, the fluorine content is the number of moles of fluorine atoms per 1 g of the composite resin, and can be calculated by, for example, the formulas described in the examples.

The composite resin may have structural units other than the fluororesin (a) and the silicone resin (b) (hereinafter referred to as other structural units).
Other structural units can be introduced without particular limitation as long as the effects of the present invention are exhibited. For example, in addition to the fluororesin (a) and the silicone resin (b), a bond is formed with both. Examples of the compound include a component derived from a (meth) acrylate monomer.
In the composite resin, the proportion of other structural units is preferably 0 to 30% by mass, and more preferably 0 to 20% by mass.

  The composite resin used for this invention may be used individually by 1 type, and may be used in combination of 2 or more type. Further, the fluororesin (a) and the silicone resin (b) in the composite resin used in the present invention may be one kind or two or more kinds, respectively.

  The resin material for an acoustic wave probe of the present invention preferably has a gel fraction of 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. A practical upper limit is 100% by mass. The higher the gel fraction, the more the fluororesin (a) and the silicone resin (b) are bonded, and the higher the molecular weight, the lower the solubility in the solvent. Since the resin fraction for acoustic wave probe of the present invention has a gel fraction within the above range, the resin (a) and the resin (b) can be effectively mixed and mixed. The acoustic wave sensitivity of the resin sheet obtained from the resin material can be further increased.

The acoustic impedance of the resin sheet obtained from the resin material of the present invention is preferably close to that of a living body, and more preferably 1.3 Mrayls, that is, 1.3 × 10 ⁶ kg / m ² / s or more. Therefore, the density of the resin material for the acoustic wave probe of the present invention is preferably 1.05 g / cm ³ or more 2.00 g / cm ³ or less, 1.10 g / cm ³ or more 1.80 g / cm ^3, more preferably less 1.20 g / cm ³ or more and 1.60 g / cm ³ or less is more preferable. Here, the density value is a value obtained by rounding off the third decimal place. The density of the resin material for acoustic wave probes of the present invention can be measured, for example, by the method described in Examples described later, or calculated from the density of each resin.

(Synthesis of composite resin)
Examples of the synthesis of the composite resin used in the present invention include a method of forming a bond by reacting the fluororesin (a) and the silicone resin (b) in the presence of a radical generator. Although the reaction is not clear, H in the fluororesin (a) and H of the methyl group in the silicone resin (b) are eliminated as a radical to form a bond, or H in the fluororesin (a) is a radical. It is considered that a bond is formed between the fluororesin (a) and the silicone resin (b) by forming a bond with the unreacted vinyl group in the silicone resin (b), and a composite resin is obtained. When the fluororesin (a) and / or the silicone resin (b) has a radical reactive group (vinyl group, allyl group, etc.), this radical reactive group is preferentially involved in bond formation.

  As radical generators, aromatic ketones, onium salt compounds, organic peroxides, thio compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, acylphosphine oxide compounds, borate compounds, azinium compounds, metallocene compounds, active esters A thermal radical generator such as a compound, a compound having a carbon halogen bond, an azo compound, or a bibenzyl compound is preferably used.

Specific examples of the thermal radical generator include Irgacure 184, Irgacure 369, Irgacure 379, Irgacure 651, Irgacure 907, Irgacure 819 (manufactured by BASF), Darocur 4265, Darocur TPO (and above, Merck). Perhexa H, Perhexa HC, Perhexa C, Perhexa V, Perhexa 22, Perbutyl H, Parkyl D, Perbutyl P, Perbutyl C, Perbutyl D, Perhexyl D, Perhexa 25B, Perhexin 25B, Parroyl L, Nipper BW, Nipper BMT-K40, Niper BMT-M, Perbutyl PV, Perhexa 25O, Peroc O, Perhexyl O, Perbutyl O, Perbutyl L, Perbutyl 355, Perhexyl I, Perbutyl I, Perbuchi E, Perhexa 25Z, Perbutyl A, Perhexyl Z, Perbutyl ZT, Perbutyl Z (or more, all trade name, manufactured by Nippon Oil & Fats Co., Ltd.) and the like.
One radical generator may be used alone, or two or more radical generators may be used in combination.

The reaction condition of the fluororesin (a) and the silicone resin (b) in the presence of a radical generator is that a bond is formed between the fluororesin (a) and the silicone resin (b), and a composite resin is obtained. There is no particular limitation.
Specifically, it can be obtained by kneading the resin mixture for an acoustic wave probe of the present invention to be described later with a kneader, a pressure kneader, a Banbury mixer (continuous kneader), or a two-roll kneader while heating. it can.
Examples of the heating and kneading conditions include a mode of kneading at 50 to 200 ° C. for 10 minutes to 10 hours.

(4) Other additives The resin material for an acoustic wave probe of the present invention appropriately contains a filler, a catalyst, a solvent, a dispersant, a pigment, a dye, an antistatic agent, a flame retardant, a thermal conductivity improver, a curing retarder, and the like. Can be blended.

− Filler −
The resin material for an acoustic wave probe of the present invention can produce a resin sheet having excellent characteristics without containing an inorganic filler, but may contain a filler.
The filler can be used without particular limitation as long as it is a filler used in a resin material for an acoustic wave probe, and specifically includes inorganic compound particles.
Examples of inorganic compounds in the inorganic compound particles include silicon oxide (silica), silicon carbide, boron nitride, alumina, barium sulfate, cerium oxide, calcium carbonate, aluminum nitride, calcium oxide, vanadium oxide, silicon nitride, barium carbonate, titanium carbide, Examples include titanium nitride, copper oxide, zirconium carbide, tungsten carbide, magnesium oxide, titanium oxide, iron oxide, zinc oxide, zirconium oxide, barium oxide, tin oxide and ytterbium oxide, silica, silicon carbide, boron nitride, alumina, sulfuric acid Any one selected from the group consisting of barium and cerium oxide is preferable, any one selected from the group consisting of silica, alumina, barium sulfate and cerium oxide is more preferable, and silica is more preferable.

  When the acoustic wave probe resin material contains inorganic compound particles, the acoustic impedance and mechanical strength (tear strength, hardness, etc.) of the acoustic wave probe resin can be improved.

  The average primary particle diameter of the inorganic compound particles is preferably more than 16 nm and less than 100 nm, more preferably 5 nm to 90 nm, more preferably 10 nm from the viewpoint of suppressing an increase in acoustic wave attenuation of the resin for acoustic wave probes and improving the tear strength. -80 nm is more preferable, and 15 nm to 70 nm is particularly preferable.

Here, the average primary particle diameter means a volume average particle diameter. The volume average particle diameter can be measured, for example, by using a laser diffraction / scattering particle size distribution measuring apparatus (for example, trade name “LA910” manufactured by Horiba, Ltd.). In the present specification, those whose average primary particle diameter is not described in the catalog or those newly produced are average primary particle diameters determined by the above measurement method.
Here, the average primary particle diameter of the inorganic compound particles means the average primary particle diameter in a surface-treated state.

  Inorganic compound particles may be used alone or in combination of two or more.

Inorganic compound particles, from the viewpoint of improving the hardness and / or mechanical strength of the resin for an acoustic wave probe obtained, the specific surface area is preferably 1~400m ² / g, more preferably 5 to 200 m ² / g, 10 to 100 m ² / g is particularly preferred.

The inorganic compound particles are preferably treated (modified) on the surface of the particles, and more preferably surface-treated with a silane compound.
By subjecting the inorganic compound particles to a surface treatment with a silane compound, the interaction with the polymer used in the present invention having a siloxane bond is strengthened and the affinity is increased. It seems that fine dispersion is possible. For this reason, it is considered that the inorganic compound fine particles exhibit a function as a stopper when mechanical adaptability is applied, and the hardness and mechanical strength of the acoustic wave probe resin are improved.
The surface treatment method may be a normal method. Examples of the surface treatment method with a silane compound include a method of surface treatment with a silane coupling agent and a method of coating with a silicone compound.

(I) Silane coupling agent The silane coupling agent is preferably a silane coupling agent having a hydrolyzable group from the viewpoint of improving the hardness and / or mechanical strength of the acoustic wave probe resin. The hydrolyzable group in the silane coupling agent is hydrolyzed with water to become a hydroxyl group, and this hydroxyl group undergoes a dehydration condensation reaction with a hydroxyl group on the surface of the inorganic compound particle, whereby the surface modification of the inorganic compound particle is performed and obtained. The hardness and / or mechanical strength of the acoustic wave probe resin is improved. Examples of the hydrolyzable group include an alkoxy group, an acyloxy group, and a halogen atom.
In addition, if the surface of the inorganic compound particles is hydrophobically modified, the affinity between the inorganic compound particles and vinyl silicone and hydrosilicone is improved, and the hardness and mechanical strength of the resulting acoustic wave probe resin are improved. Therefore, it is preferable.

  Examples of the silane coupling agent having a hydrophobic group as a functional group include methyltrimethoxysilane (MTMS), dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n -Alkoxysilanes such as propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane and decyltrimethoxysilane; such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane and phenyltrichlorosilane Chlorosilane; and hexamethyldisilazane (HMDS).

  Examples of the silane coupling agent having a vinyl group as a functional group include methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, and vinyltriethoxy. Silanes, alkoxysilanes such as vinyltrimethoxysilane and vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane and vinylmethyldichlorosilane; and divinyltetramethyldisilazane.

As the silane coupling agent, a trialkylsilylating agent is preferable, and a trimethylsilylating agent is more preferable.
As a silane compound, the silane coupling agent by which the functional group in the said silane coupling agent and a silane coupling agent was substituted by the alkyl group is mentioned, for example.
Examples of the trimethylsilylating agent include trimethylchlorosilane and hexamethyldisilazane (HMDS) described in the above silane coupling agent and methyltrimethoxysilane (silane coupling agent in which a functional group is substituted with an alkyl group). MTMS) and trimethylmethoxysilane.

Examples of commercially available silane coupling agents include hexamethyldisilazane (HMDS) (trade name: HEXAMETHYLDISILAZANE (SIH6110.1) and manufactured by Gelest).
Hydroxyl groups present on the surface of inorganic compound particles are covered with trimethylsilyl groups by reaction with hexamethyldisilazane (HMDS), methyltrimethoxysilane (MTMS), trimethylmethoxysilane, etc., and the surface of inorganic compound particles is modified to be hydrophobic. Is done.
In the present invention, the silane coupling agent may be used alone or in combination of two or more.

(Ii) Silicone Compound The silicone compound that coats the inorganic compound particles may be a polymer composed of siloxane bonds.
Examples of the silicone compound include a silicone compound in which all or part of the side chain and / or terminal of polysiloxane is a methyl group, a silicone compound in which part of the side chain is a hydrogen atom, side chain and / or terminal Examples thereof include a modified silicone compound in which an organic group such as an amino group and / or an epoxy group is introduced into all or a part of the above, and a silicone resin having a branched structure. The silicone compound may have a linear or cyclic structure.

  Examples of silicone compounds in which all or part of the side chain and / or terminal of polysiloxane are methyl groups include polymethylhydrosiloxane (hydrogen terminal), polymethylhydrosiloxane (trimethylsiloxy terminal), and polymethylphenyl. Monomethyl polysiloxanes such as siloxane (hydrogen terminated) and polymethylphenylsiloxane (trimethylsiloxy terminated), for example dimethylpolysiloxane (hydrogen terminated), dimethylpolysiloxane (trimethylsiloxy terminated) and dimethylpolysiloxane such as cyclic dimethylpolysiloxane Examples include siloxane.

  Examples of silicone compounds in which a part of the side chain is a hydrogen atom include methylhydrosiloxane-dimethylsiloxane copolymer (trimethylsiloxy-terminated), methylhydrosiloxane-dimethylsiloxane copolymer (hydrogen-terminated), and polymethylhydrosiloxane (hydrogen-terminated). Polymethylhydrosiloxane (trimethylsiloxy-terminated), polyethylhydrosiloxane (triethylsiloxy-terminated), polyphenyl- (dimethylhydrosiloxy) siloxane (hydrogen-terminated), methylhydrosiloxane-phenylmethylsiloxane copolymer (hydrogen-terminated), methylhydro Mention may be made of siloxane-octylmethylsiloxane copolymers and methylhydrosiloxane-octylmethylsiloxane-dimethylsiloxane terpolymers.

  Examples of the modified silicone introduced with an organic group include, for example, amino group, epoxy group, methoxy group, (meth) acryloyl group, phenol group, carboxylic anhydride group, hydroxy group, mercapto group, carboxy group and / or hydrogen. Reactive silicones incorporating atomic organic groups and non-reactives modified with, for example, polyethers, aralkyls, fluoroalkyls, long chain alkyls, long chain aralkyls, higher fatty acid esters, higher fatty acid amides and / or polyether methoxys Examples include silicone.

The inorganic compound particles coated with the silicone compound can be obtained by a conventional method. For example, it can be obtained by mixing and stirring inorganic compound particles in dimethylpolysiloxane for a certain time and filtering.
In addition, when reactive modified silicone is used as the silicone compound, the organic group reacts with the hydroxyl group on the surface of the inorganic compound particle, whereby the surface modification of the inorganic compound particle is performed, and the obtained acoustic probe resin Hardness and / or mechanical strength are improved.

  Examples of commercially available silicone compounds include methyl hydrogen silicone oil (MHS) (trade name: KF-99, manufactured by Shin-Etsu Chemical Co., Ltd.), which is polymethylhydrosiloxane (trimethylsiloxy terminal).

The degree of surface modification of the inorganic compound particles, that is, the degree of hydrophobicity of the inorganic compound particles can be examined by the following degree of methanol hydrophobicity.
The inorganic compound particles preferably have a methanol hydrophobization degree calculated by the following methanol titration test of 40 to 80% by mass, more preferably 50 to 80% by mass, and 60 to 80% by mass. Is more preferable. Here, the greater the degree of methanol hydrophobization, the higher the hydrophobicity, and the smaller the degree, the higher the hydrophilicity.
50 ml of ion-exchanged water and 0.2 g of inorganic compound particles as a sample are put in a beaker and the temperature is 25 ° C., and methanol is dropped from a burette to a place where the sample is stirred with a magnetic stirrer. Xg) is measured. The degree of hydrophobization of methanol is calculated from the following formula.

  Methanol hydrophobicity (mass%) = {X / (50 + X)} × 100

  When the degree of methanol hydrophobization is within the above preferred range, an increase in viscosity of the acoustic probe resin material can be suppressed, and a decrease in acoustic wave sensitivity of the acoustic probe resin sheet can be suppressed.

The sphericity of the Wardel in the primary particles of the inorganic compound particles is preferably 0.7 to 1, more preferably 0.8 to 1, and still more preferably 0.9 to 1.
Here, “Wadell's sphericity” (see Chemical Engineering Handbook, published by Maruzen Co., Ltd.) is the sphericity of a particle ((diameter of circle equal to the projected area of the particle) / (minimum circumscribing the projected image of the particle) It is an index measured by (diameter of circle), and the closer this index is to 1.0, the closer the particle is to a true sphere.
For example, an SEM (Scanning Electron Microscope) photograph can be used for measurement of Wardel's sphericity (hereinafter also simply referred to as sphericity). Specifically, for example, about 100 primary particles are observed from the SEM photograph, and their sphericity is calculated. The average value obtained by dividing the total calculated sphericity by the number of observed primary particles is defined as sphericity.

When the sphericity of the Wardel is within the above preferable range, it is considered that the acoustic wave sensitivity is improved because the area of the acoustic wave that hits the inorganic compound particles is reduced when the acoustic wave is irradiated onto the resin sheet for acoustic wave probes. In particular, in the range of a specific average primary particle diameter possessed by the inorganic compound particles, the acoustic wave sensitivity is more effectively improved, so that the shape of the inorganic compound particles is preferably spherical, and more preferably spherical. preferable.
In the present specification, the “true sphere” includes a slightly distorted sphere having a Wadel sphericity in the range of 0.9 to 1.

Among inorganic compound particles, silica particles are produced by combustion method silica obtained by burning a silane compound (that is, fumed silica), deflagration method silica obtained by explosively burning metal silicon powder, Wet silica obtained by neutralization of sodium silicate and mineral acid (obtained by hydrolysis of precipitated silica, synthesized by alkali, gel silica by acidic) and hydrocarbyloxysilane Sol-gel method silica (so-called Stöber method).
Explosive methods and sol-gel methods are preferable as the method for producing true spherical silica particles, which are preferable.

The sol-gel method is a hydrophilic spherical silica consisting essentially of SiO ₂ units by hydrolyzing and condensing hydrocarbyloxysilane (preferably tetrahydrocarbyloxysilane) or a partial hydrolysis condensation product thereof or a combination thereof. This is a method for obtaining particles.
In addition, the hydrophobization treatment on the surface of the silica particle is performed on the surface of the hydrophilic spherical silica particle by R ³ ₃ SiO _1/2 unit (R ³ is the same or different, and is a substituted or unsubstituted 1 to 20 carbon atom number. (Hydrovalent hydrocarbon group) can be introduced.
Specifically, for example, it can be carried out by the methods described in JP2007-99582A and JP2014-114175A.

− Catalyst −
Examples of the catalyst include platinum or a platinum-containing compound (hereinafter also simply referred to as a platinum compound). Any platinum or platinum compound can be used.
Specifically, platinum black or platinum supported on an inorganic compound or carbon black, chloroplatinic acid or an alcohol solution of chloroplatinic acid, complex salt of chloroplatinic acid and olefin, complex salt of chloroplatinic acid and vinylsiloxane Etc. A catalyst may be used individually by 1 type and may be used in combination of 2 or more type.

The catalyst is necessary in the hydrosilylation reaction in which the Si—H group of the hydrosilicone is added to the vinyl group of the vinylsilicone. As the hydrosilylation reaction (addition curing reaction) proceeds, the vinyl silicone is crosslinked with the hydrosilicone to form a silicone resin.
Here, the catalyst may be contained in the resin material for acoustic wave probes of the present invention, or when being molded using the resin material for acoustic wave probes without being contained in the resin material for acoustic wave probes. You may make it contact with the resin material for acoustic wave probes. The latter is preferred.

  Commercially available platinum catalysts include, for example, platinum compounds (trade names: PLATINUM CYCLOVINYLMETHYLSILOXIPANE COMPLEX IN CYCLIC METHYLTYLINTYLINTLETLITELXYLITELXYLITELXYLITELXYLITELMETLITELMETLITELXYLETLITELETLETLETLETLETLETLETLETLETTLETH Pt concentration of 3% by mass, both manufactured by Gelest).

  When the catalyst is contained in the resin material for acoustic wave probes of the present invention, the content of the catalyst is not particularly limited, but from the viewpoint of reactivity, it is 0.00001 to 100 mass parts of the polysiloxane mixture. 0.05 mass part is preferable, 0.00001-0.01 mass part is more preferable, 0.00002-0.01 mass part is further more preferable, and 0.00005-0.005 mass part is especially preferable.

  Further, the curing temperature can be adjusted by selecting an appropriate platinum catalyst. For example, platinum-vinyldisiloxane is used for room temperature curing (RTV) at 50 ° C. or lower, and platinum-cyclic vinylsiloxane is used for high temperature curing (HTV) at 130 ° C. or higher.

− Cure retarder −
In the present invention, a curing retarder for the curing reaction can be appropriately used. The curing retarder is used for the purpose of delaying the addition curing reaction, and examples thereof include a low molecular weight vinylmethylsiloxane homopolymer (trade name: VMS-005, manufactured by Gelest).
The curing rate, that is, the working time can be adjusted by the content of the curing retarder.

<< Resin mixture for acoustic wave probe >>
The resin mixture for an acoustic wave probe of the present invention comprises a resin (a) containing a structural unit having a fluorine atom, a resin (b) containing a structural unit having a polysiloxane bond, and a radical generator.
The resin (a) containing a structural unit having a fluorine atom, the resin (b) containing a structural unit having a polysiloxane bond, and the radical generator are a resin containing a structural unit having a fluorine atom in the resin material for acoustic wave probes ( The description of a), the resin (b) containing a structural unit having a polysiloxane bond, and a radical generator is preferably applied.
Although content in particular of the radical generator in a mixture is not restrict | limited, 0.01-10 mass parts is preferable with respect to a total of 100 mass parts of fluororesin (a) and silicone resin (b), and 0.1-3 Part by mass is more preferable.
The resin mixture for acoustic wave probes of the present invention is suitably used for producing the resin material for acoustic wave probes of the present invention.

<Resin material for acoustic wave probe and method for producing resin sheet for acoustic wave probe>
The resin material for an acoustic wave probe of the present invention can be prepared by an ordinary method when it contains the above components in addition to the composite resin.
For example, the composite resin and the other components that may be contained can be obtained by kneading with a lab plast mill, kneader, pressure kneader, Banbury mixer (continuous kneader) or a two-roll kneading apparatus. . It can also be obtained by kneading the other components together with the fluororesin (a), the silicone resin (b) and the radical generator. The mixing order of each component is not particularly limited.

  An acoustic wave probe resin sheet can be obtained by, for example, hot pressing the thus obtained resin material for an acoustic wave probe of the present invention. There is no restriction | limiting in particular as the method of a hot press, It can carry out by a conventional method. For example, the aspect which heat-presses by the pressure of 5-30 MPa for 1 to 10 minutes at 80-300 degreeC using apparatuses, such as MINI TEST PRESS MP-WNL (the Toyo Seiki company make, brand name), is mentioned.

<Acoustic wave characteristics of resin sheet for acoustic wave probe>
The acoustic wave probe resin sheet is obtained by molding the acoustic wave probe resin of the present invention by hot pressing or the like.
Below, it describes in detail about the acoustic wave characteristic of the resin sheet for acoustic wave probes.
Here, the acoustic wave characteristic describes the ultrasonic characteristic. However, the acoustic wave characteristic is not limited to the ultrasonic characteristic, but relates to the acoustic wave characteristic of an appropriate frequency selected according to the object to be examined and the measurement conditions.

[Acoustic impedance]
Acoustic impedance is preferably close to the acoustic impedance of the living body, more preferably ^{1.10~1.75 × 10 6 kg / m 2} / sec, 1.20~1.70 × 10 6 kg / m 2 / sec Is more preferable, 1.25 to 1.65 × 10 ⁶ kg / m ² / sec is particularly preferable, and 1.30 to 1.60 × 10 ⁶ kg / m ² / sec is most preferable.
The acoustic impedance can be obtained by the method described in the example section.

[Acoustic wave (ultrasonic wave) attenuation, sensitivity]
It can be determined by the method described in the Examples section.
In the evaluation system of the present invention, the acoustic wave (ultrasonic wave) sensitivity is preferably −70 dB or more, and more preferably −68 dB or more.

The resin material for acoustic wave probes of the present invention is useful for medical members, and can be preferably used for, for example, acoustic wave probes and acoustic wave measuring apparatuses. The acoustic wave measuring apparatus of the present invention is not limited to an ultrasonic diagnostic apparatus or a photoacoustic wave measuring apparatus, but refers to an apparatus that receives an acoustic wave reflected or generated by an object and displays it as an image or signal intensity.
In particular, the resin material for an acoustic wave probe according to the present invention is provided between the acoustic lens of the ultrasonic diagnostic apparatus or the piezoelectric element and the acoustic lens, and has a role of matching the acoustic impedance between the piezoelectric element and the acoustic lens. Acoustic matching layer material, acoustic lens material in a photoacoustic wave measuring device or ultrasonic endoscope, and acoustic in an ultrasonic probe comprising a capacitive micromachined ultrasonic transducer (cMUT) as an ultrasonic transducer array It can be suitably used for a lens material or the like.
Specifically, the resin material for an acoustic wave probe of the present invention includes, for example, an ultrasonic diagnostic apparatus described in JP-A-2005-253751, JP-A-2003-169802, and JP-A-2013-202050. Preferred for acoustic wave measuring devices such as photoacoustic wave measuring devices described in Japanese Patent Laid-Open No. 2013-188465, JP 2013-180330, JP 2013-158435, 2013-154139, etc. Applied.

<< Acoustic wave probe (probe) >>
The configuration of the acoustic wave probe of the present invention will be described in more detail below based on the configuration of the ultrasonic probe in the ultrasonic diagnostic apparatus shown in FIG. In addition, an ultrasonic probe is a probe which uses an ultrasonic wave especially as an acoustic wave in an acoustic wave probe. Therefore, the basic structure of the ultrasonic probe can be applied to the acoustic wave probe as it is.

− Ultrasonic probe −
The ultrasonic probe 10 is a main component of the ultrasonic diagnostic apparatus, and has a function of generating ultrasonic waves and transmitting / receiving ultrasonic beams. As shown in FIG. 1, the configuration of the ultrasonic probe 10 is provided in the order of the acoustic lens 1, the acoustic matching layer 2, the piezoelectric element layer 3, and the backing material 4 from the tip (surface contacting the living body to be examined). ing. In recent years, for the purpose of receiving high-order harmonics, a transmitting ultrasonic transducer (piezoelectric element) and a receiving ultrasonic transducer (piezoelectric element) are made of different materials to form a laminated structure. Has also been proposed.

<Piezoelectric element layer>
The piezoelectric element layer 3 is a part that generates ultrasonic waves, and electrodes are attached to both sides of the piezoelectric element. When a voltage is applied, the piezoelectric element repeatedly vibrates and expands and expands to generate ultrasonic waves. To do.

As a material constituting the piezoelectric element, a crystal, a single crystal such as LiNbO ₃ , LiTaO ₃ and KNbO _3, a thin film such as ZnO and AlN, and a sintered body such as a Pb (Zr, Ti) O ₃ system were subjected to polarization treatment, So-called ceramic inorganic piezoelectric materials are widely used. In general, piezoelectric ceramics such as PZT: lead zirconate titanate with high conversion efficiency are used.
In addition, a piezoelectric element that detects a received wave on the high frequency side needs sensitivity with a wider bandwidth. For this reason, an organic piezoelectric body using an organic polymer material such as polyvinylidene fluoride (PVDF) is used as a piezoelectric element suitable for a high frequency and a wide band.
Furthermore, Japanese Patent Application Laid-Open No. 2011-071842 uses MEMS (Micro Electro Mechanical Systems) technology that exhibits an excellent short pulse characteristic and a wide band characteristic, which is excellent in mass productivity and has a small characteristic variation. cMUT is described.
In the present invention, any piezoelectric element material can be preferably used.

<Backing material>
The backing material 4 is provided on the back surface of the piezoelectric element layer 3, and reduces the pulse width of the ultrasonic wave by suppressing excessive vibration, thereby contributing to the improvement of the distance resolution in the ultrasonic diagnostic image.

<Acoustic matching layer>
The acoustic matching layer 2 is provided in order to reduce the difference in acoustic impedance between the piezoelectric element layer 3 and the test object and to efficiently transmit and receive ultrasonic waves.
The resin material for an acoustic wave probe of the present invention is preferably used as a material for an acoustic matching layer because the difference from the acoustic impedance of a living body (1.4 to 1.7 × 10 ⁶ kg / m ² / sec) is small. Can do. The acoustic matching layer preferably contains 10% by mass or more of the resin material for acoustic wave probes of the present invention.

<Acoustic lens>
The acoustic lens 1 is provided to focus the ultrasonic wave in the slice direction using refraction and improve the resolution. In addition, the ultrasonic wave is brought into close contact with the living body to be examined and the ultrasonic wave is matched with the acoustic impedance of the living body (1.4 to 1.7 × 10 ⁶ kg / m ² / sec in the human body), and the acoustic lens 1 The ultrasonic attenuation amount of the device itself is required to be small.
That is, the acoustic lens 1 is made of a material whose sound velocity is sufficiently smaller than the sound velocity of the human body, the attenuation of the ultrasonic wave is small, and the acoustic impedance is close to the value of the human skin. Sensitivity is improved.
The resin material for acoustic wave probes of the present invention can be preferably used as an acoustic lens material.

  The operation of the ultrasonic probe 10 having such a configuration will be described. A voltage is applied to the electrodes provided on both sides of the piezoelectric element to resonate the piezoelectric element layer 3, and an ultrasonic signal is transmitted from the acoustic lens to the object to be examined. At the time of reception, the piezoelectric element layer 3 is vibrated by a reflected signal (echo signal) from the subject to be examined, and this vibration is electrically converted into a signal to obtain an image.

In particular, the acoustic lens obtained from the resin material for acoustic wave probes of the present invention can confirm a remarkable sensitivity improvement effect at an ultrasonic transmission frequency of about 5 MHz or more as a general medical ultrasonic transducer. Particularly significant sensitivity improvement effect can be expected at an ultrasonic transmission frequency of 10 MHz or more.
Hereinafter, an apparatus in which the acoustic lens obtained from the resin material for an acoustic wave probe of the present invention exhibits a function with respect to conventional problems will be described in detail.
In addition, the resin material for acoustic wave probes of the present invention exhibits an excellent effect even for apparatuses other than those described below.

-Ultrasonic probe with cMUT (capacitive micromachined ultrasonic transducer)-
When the cMUT device described in JP 2006-157320 A, JP 2011-71842 A, or the like is used for a transducer array for ultrasonic diagnosis, it is generally compared with a transducer using general piezoelectric ceramics (PZT). Specifically, the sensitivity becomes low.
However, by using an acoustic lens obtained from the resin material for acoustic wave probes of the present invention, it is possible to compensate for the lack of sensitivity of cMUT. Thereby, the sensitivity of the cMUT can be brought close to the performance of the conventional transducer.
Since the cMUT device is manufactured by the MEMS technology, it is possible to provide an ultrasonic probe having a higher productivity and a lower cost than the piezoelectric ceramic probe to the market.

− Photoacoustic wave measurement device using photoacoustic imaging −
Photoacoustic imaging (PAI) described in Japanese Patent Application Laid-Open No. 2013-158435 or the like is a supersonic wave generated when a human body tissue is adiabatically expanded by irradiating light (electromagnetic waves) into the human body. Displays the image of the sound wave or the signal strength of the ultrasonic wave.
Here, since the sound pressure of the ultrasonic wave generated by light irradiation is very small, there is a problem that it is difficult to observe the deep part of the human body.
However, by using an acoustic lens obtained from the resin material for acoustic wave probes of the present invention, an effective effect can be exhibited for this problem.

− Ultrasound endoscope −
Since the ultrasonic wave in the ultrasonic endoscope described in Japanese Patent Application Laid-Open No. 2008-311700 is longer in structure than the body surface transducer due to its structure, the sensitivity of the transducer is improved due to the cable loss. It is a problem. Moreover, it is said that there is no effective sensitivity improvement means for this problem for the following reasons.

First, in the case of an ultrasonic diagnostic apparatus for the body surface, an amplifier circuit, an AD conversion IC, etc. can be installed at the tip of the transducer. On the other hand, since an ultrasonic endoscope is used by being inserted into the body, the installation space for the transducer is narrow, and it is difficult to install an amplifier circuit, an AD conversion IC, or the like at the tip of the transducer.
Secondly, the piezoelectric single crystal employed in the transducer in the ultrasonic diagnostic apparatus for the body surface is difficult to apply to a transducer having an ultrasonic transmission frequency of 7 to 8 MHz or more due to its physical characteristics and process suitability. . However, since endoscope ultrasonic waves are generally probes having an ultrasonic transmission frequency of 7 to 8 MHz or higher, it is difficult to improve sensitivity using a piezoelectric single crystal material.

However, the sensitivity of the endoscope ultrasonic transducer can be improved by using an acoustic lens obtained from the resin material for acoustic wave probes of the present invention.
Even when the same ultrasonic transmission frequency (for example, 10 MHz) is used, the present invention is particularly effective when an acoustic lens obtained from the resin material for an acoustic wave probe of the present invention is used in an ultrasonic transducer for an endoscope. Demonstrated.

  Hereinafter, the present invention will be described in more detail based on examples using ultrasonic waves as acoustic waves. Note that the present invention is not limited to ultrasonic waves, and an acoustic wave having an audible frequency may be used as long as an appropriate frequency is selected in accordance with the object to be examined and measurement conditions. Hereinafter, room temperature means 25 ° C.

[Example]
<Production of resin sheet>
(1) Synthesis of silicone rubber 95 parts by mass of vinyl-terminated polydimethylsiloxane DMS-V41 (trade name, manufactured by Gelest), 5 parts by mass of methylhydrosiloxane-dimethylsiloxane copolymer HMS-301 (trade name, manufactured by Gelest), platinum A silicone rubber was synthesized by mixing 0.03 part by mass of catalyst SIP6830.3 (trade name, manufactured by Gelest Co., Ltd.) into a resin material, and subjecting this resin material to a heat press treatment and heat curing at 150 ° C. for 5 minutes. .
(2) Synthesis of fluororesin With respect to 90 parts by mass of trifluoroethyl methacrylate, 10 parts by mass of allyl methacrylate, and 200 parts by mass of propylene glycol-1-monomethyl ether-2-acetate, dimethyl 1 , 1′-Azobis (1-cyclohexanecarboxylate) (manufactured by Wako Pure Chemical Industries, Ltd.) (1.0 part by mass) was added and reacted at 90 ° C. for 2 hours. Thereafter, 1.0 part by mass of dimethyl 1,1′-azobis (1-cyclohexanecarboxylate) (manufactured by Wako Pure Chemical Industries, Ltd.) was added and reacted at 90 ° C. for 2 hours. Furthermore, 1.0 part by mass of dimethyl 1,1′-azobis (1-cyclohexanecarboxylate) (manufactured by Wako Pure Chemical Industries, Ltd.) was added and reacted at 90 ° C. for 2 hours. By adding the reaction solution to 1000 mL of methanol, fluororesin a-1 was obtained as a white solid.
In the same manner as the fluororesin a-1, fluororesins a-2 and a-3 and a pentafluorostyrene polymer described in Table 1 below were synthesized.

(3) Heat-kneading and molding Daiel G-801 (trade name, manufactured by Daikin) 80 parts by mass, 19 parts by mass of the silicone rubber synthesized above, perbutyl H (trade name, t-butyl hydroperoxide, manufactured by NOF Corporation) One part by mass was kneaded at 200 ° C. for 2 hours with a lab plast mill (manufactured by Toyo Seiki Co., Ltd.). Thereafter, the kneaded resin material was subjected to a heat press treatment, and a resin sheet No. 60 having a length of 60 mm, a width of 60 mm, and a thickness of 2 mm was obtained. 101 was produced.
Here, the heat press treatment is performed by filling a resin material in a mold, and using a “MINI TEST PRESS MP-WNL” manufactured by Toyo Seiki Co., Ltd., setting the press temperature to 200 ° C. and pressing at 10 MPa for 5 minutes. A film was formed.
Resin sheet No. 1 was changed except that the silicone resin, fluororesin and additives were changed to the types and blending ratios shown in Table 1 below. In the same manner as the production of 101, resin sheet No. 102-115 and c11-c18 were produced.

<Evaluation of physical properties, ultrasonic characteristics and chemical resistance>
The following evaluation was performed about the resin sheets 101-115 and c11-c18 produced above.

1. Fluorine content The fluorine content in the composite resin constituting the resin sheet was calculated by one of the following formulas.
Fluorine content (mol / g) = (n _F / M _F ) × m _F / 100
In the above _formula, n _{F, M} F and _{m F} show the following respectively.
n _F : number of fluorine atoms in repeating unit of fluororesin (a) M _F : molecular weight of repeating unit of fluororesin (a) m _F : mass blending ratio of fluororesin (a)

Fluorine content (mol / g) = (mass _F × 0.01 / 18.9) × m _F
/ 100
In the above formula, mass _F and m _F represent the following.
mass _F : Fluorine concentration (mass% of fluorine atoms in the fluororesin (a))
m _F : Mass blending ratio of fluororesin (a)

2. Gel fraction A sample (sheet) having a thickness of 2 mm obtained by cutting out 100 mg from the resin sheet prepared above was taken out after being immersed in 10 g of tetrahydrofuran at room temperature for 24 hours, and dried at 100 ° C. for 2 hours. The gel fraction was measured by the following formula from the sample mass m ₀ before immersion and the sample mass m ₂₄ after immersion and drying.
Gel fraction (mass%) = m ₂₄ / m ₀ × 100

3. Density With respect to the obtained resin sheet having a thickness of 2 mm, an electronic hydrometer (trade name, manufactured by Alpha Mirage Co., Ltd.) is used in accordance with the density measurement method of A method (underwater substitution method) described in JIS K7112 (1999). “SD-200L”).
Here, when the resin sheet contains no component other than the composite resin, the density measured by the above method corresponds to the density of the composite resin.

4). Acoustic wave (ultrasonic) sensitivity A 10 MHz sine wave signal (1 wave) output from an ultrasonic oscillator (Iwatsu Measurement Co., Ltd., function generator, product name “FG-350”) is an ultrasonic probe (Japan probe) And an ultrasonic pulse wave having a center frequency of 10 MHz was generated from the ultrasonic probe in water. The magnitude of amplitude before and after the generated ultrasonic wave passes through the obtained resin sheet having a thickness of 2 mm is measured by an ultrasonic receiver (Matsushita Electric Industrial Co., Ltd., oscilloscope, trade name “VP-5204A”). The attenuation of the acoustic wave (ultrasonic wave) of each material was compared by measuring in an environment with a water temperature of 25 ° C. and comparing the acoustic wave (ultrasonic wave) sensitivity.
The acoustic wave (ultrasonic wave) sensitivity is a numerical value given by the following calculation formula.
In the following calculation formula, Vin represents a voltage peak value of an input wave generated by the ultrasonic oscillator and having a half-value width of 50 nsec or less. Vs represents a voltage value obtained when the generated acoustic wave (ultrasonic wave) passes through the sheet and the ultrasonic oscillator receives the acoustic wave (ultrasonic wave) reflected from the facing surface of the sheet. The higher the acoustic wave (ultrasonic wave) sensitivity, the smaller the acoustic wave (ultrasonic wave) attenuation amount.
Acoustic wave (ultrasound) sensitivity = 20 x Log (Vs / Vin)

The acoustic wave (ultrasonic wave) sensitivity was evaluated according to the following evaluation criteria. In this test, an evaluation “C” or higher is an acceptable level.
(Evaluation criteria)
AA: -64 dB or more A: -66 dB or more and less than -64 dB B: -68 dB or more and less than -66 dB C: -70 dB or more and less than -68 dB D: less than -70 dB

5. Acoustic impedance For the obtained resin sheet having a thickness of 2 mm, an electronic hydrometer (manufactured by Alpha Mirage Co., Ltd.) is used in accordance with the density measurement method of A method (underwater substitution method) described in JIS K7112 (1999). Name “SD-200L”). The ultrasonic sound velocity was measured at 25 ° C. using a sing-around sound velocity measuring device (trade name “UVM-2 type” manufactured by Ultrasonic Industry Co., Ltd.) according to JIS Z2353 (2003), and the measured density and sound velocity were measured. The acoustic impedance was obtained from the product. The acoustic impedance was evaluated according to the following evaluation criteria. In this test, an evaluation “C” or higher is an acceptable level.
(Evaluation criteria)
A: 1.30 × 10 ⁶ kg / m ² / s or more and less than 1.60 × 10 ⁶ kg / m ² / s B: 1.20 × 10 ⁶ kg / m ² / s or more 1.30 × 10 ⁶ kg / M ² / s or 1.60 × 10 ⁶ kg / m ² / s or more and less than 1.70 × 10 ⁶ kg / m ² / s C: 1.10 × 10 ⁶ kg / m ² / s or more 1. Less than 20 × 10 ⁶ kg / m ² / s or 1.70 × 10 ⁶ kg / m ² / s or more and less than 1.75 × 10 ⁶ kg / m ² / s D: 1.10 × 10 ⁶ kg / m ² / S or less than 1.75 × 10 ⁶ kg / m ² / s

6). Chemical Resistance The obtained resin sheet having a thickness of 2 mm was immersed in a 20% hydrochloric acid aqueous solution, heated at 80 ° C. for 2 hours, and the mass change before and after drying was measured. An evaluation “C” or higher is an acceptable level.
(Evaluation criteria)
A: Mass change less than 2% B: Mass change from 2% to less than 5% C: Mass change from 5% to less than 10% D: Mass change of 10% or more

  The composition, physical properties and evaluation results of the resin sheet are summarized in Table 1 below.

<Notes on Table 1>
(Fluororesin (a))
PVDF: polyvinylidene fluoride, mass average molecular weight 180,000, Daidell G-801 manufactured by Aldrich, trade name, vinylidene fluoride rubber, manufactured by Daikin, fluorine concentration 66% by mass (fluorine concentration is the fluorine atom in the resin) (The same applies hereinafter)
Daiel G-901: trade name, vinylidene fluoride rubber, manufactured by Daikin, fluorine concentration 70.5% by mass
Daiel LT-252: Vinylidene fluoride rubber, manufactured by Daikin, fluorine concentration of 66.5% by mass
Fluorine resin a-1: trifluoroethyl methacrylate / allyl methacrylate copolymer
(90/10), weight average molecular weight 100,000
Fluorine resin a-2: trifluoroethyl methacrylate / allyl methacrylate copolymer
(70/30), weight average molecular weight 120,000
Fluororesin a-3: Pentafluorostyrene / allyl methacrylate copolymer
(90/10), weight average molecular weight 100,000
In addition, the number in the parenthesis of fluorine-containing resin a-1 to a-3 shows the mass ratio of each structural unit.
Pentafluorostyrene polymer, weight average molecular weight 110,000
(Silicone resin (b))
Silicone rubber: Silicone rubber DMS-V41 synthesized above: trade name, vinyl-terminated polydimethylsiloxane, mass average molecular weight 62,700, manufactured by Gelest (additive)
Perbutyl H: trade name, t-butyl hydroperoxide, manufactured by NOF Corporation Perbutyl D: trade name, di-tert-butyl peroxide, manufactured by NOF Corporation VAm-110: trade name, 2,2′-azobis (N-butyl 2-methylpropionamide), silica manufactured by Wako Pure Chemical Industries, Ltd .: trade name “Aerosil R974”, manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter 12 nm, dimethyldichlorosilane surface treatment.
“-”: Indicates that the component is not contained.

From Table 1, resin sheet No. using the resin material for acoustic wave probes of the present invention. 101 to 115 show that the acoustic impedance is close to the value of the living body, the acoustic wave attenuation is reduced even at a high frequency, and the chemical resistance is excellent.
On the other hand, resin sheet No. using the resin material for acoustic wave probes of the comparative example. c11 and c12 do not have a fluororesin (a) in the resin. This resin sheet No. c11 is inferior in acoustic impedance and chemical resistance, and resin sheet No. 1 containing silica particles. c12 was inferior in acoustic wave sensitivity.
In addition, a resin sheet No. using a resin material for a comparative acoustic wave probe was used. c13 and 15-17 do not have silicone (b) in the resin. These resin sheets No. Each of c13 and 15-17 was inferior in acoustic wave sensitivity and acoustic impedance.
Resin sheet No. using a resin material for comparison acoustic wave probe. c14 and no. c18 consists of a mixed resin of a fluororesin (a) and a silicone resin (b). This resin sheet No. c14 and no. c18 was inferior in acoustic wave sensitivity.

  From this result, it can be seen that the resin material for acoustic wave probes of the present invention is useful for medical members. Moreover, it turns out that the resin material for acoustic wave probes of this invention can be used suitably also for the acoustic lens of an acoustic wave probe, an acoustic wave measuring apparatus, and an ultrasonic diagnostic apparatus. In particular, the resin material for an acoustic wave probe of the present invention is preferably used for the purpose of improving sensitivity in an acoustic wave probe, a photoacoustic wave measuring apparatus, and an ultrasonic endoscope that use cMUT as an ultrasonic diagnostic transducer array. Can do.

DESCRIPTION OF SYMBOLS 1 Acoustic lens 2 Acoustic matching layer 3 Piezoelectric element layer 4 Backing material 7 Case 9 Code 10 Ultrasonic probe (probe)

Claims (12)

  A resin material for an acoustic wave probe comprising a resin in which a resin (a) containing a structural unit having a fluorine atom and a resin (b) containing a structural unit having a polysiloxane bond are bonded.   2. The resin material for an acoustic wave probe according to claim 1, wherein the ratio of the mass mb of the resin (b) to the mass ma of the resin (a) is ma: mb = 30: 70 to 70:30.   The resin (a) is a polyvinylidene fluoride, a polymer containing a fluorinated styrene structural unit, a polymer containing a fluorinated alkyl (meth) acrylate structural unit, a polymer containing a fluorinated alkyl group-containing styrene structural unit, and fluorine. The resin material for an acoustic wave probe according to claim 1, wherein the resin material is at least one kind of rubber.   The resin material for an acoustic wave probe according to any one of claims 1 to 3, wherein the gel fraction is 80% by mass or more. The resin material for an acoustic wave probe according to any one of claims 1 to 4, wherein the density is 1.05 g / cm ³ or more.   The resin (a) including a structural unit having a fluorine atom, the resin (b) including a structural unit having a polysiloxane bond, and a radical generator, according to any one of claims 1 to 5. The resin mixture for acoustic wave probes used for the resin material for acoustic wave probes.   An acoustic lens comprising the resin material for an acoustic wave probe according to claim 1.   An acoustic wave probe comprising the acoustic lens according to claim 7.   An acoustic wave measuring apparatus comprising the acoustic wave probe according to claim 8.   An ultrasonic diagnostic apparatus comprising the acoustic wave probe according to claim 8.   A photoacoustic wave measuring apparatus comprising the acoustic lens according to claim 7. An ultrasonic endoscope comprising the acoustic lens according to claim 7.

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