JP2017012436

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DESCRIPTION JP2017012436
Abstract: The present invention provides a silicone resin for an acoustic wave probe which has an
acoustic impedance close to that of a living body and reduced acoustic wave attenuation and is
excellent in hardness and mechanical strength. Further, the present invention provides an
acoustic wave probe, an ultrasonic probe, an acoustic wave measurement device, an ultrasonic
diagnostic device, a photoacoustic wave measurement device, an ultrasonic endoscope, and a
composition for an acoustic wave probe using this resin. A polymer comprising an aggregate
having an average particle diameter of 200 nm to 10 μm and containing at least one inorganic
oxide, and a polymer constituting a resin component is represented by the following formula (1)
in a molecular chain: A silicone resin having at least two structural units is used as a silicone
resin for an acoustic wave probe, particularly as an acoustic lens 1. [Selected figure] Figure 1
Composition for acoustic wave probe, silicone resin for acoustic wave probe, acoustic wave probe
and ultrasonic probe, acoustic wave measurement apparatus, ultrasonic diagnostic apparatus,
photoacoustic wave measurement apparatus and ultrasonic endoscope
[0001]
The present invention relates to a composition for an acoustic wave probe, a silicone resin for an
acoustic wave probe, an acoustic wave probe and an ultrasonic probe. Furthermore, the present
invention relates to an acoustic wave measurement device, an ultrasonic diagnostic device, a
photoacoustic wave measurement device, and an ultrasonic endoscope.
[0002]
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In an acoustic wave measuring apparatus, an acoustic wave probe is used which irradiates an
acoustic wave to a test subject, receives a reflected wave (echo), and outputs a signal. The
electrical signal converted from the reflected wave received by the acoustic wave probe is
displayed as an image. Thereby, the inside of a test subject is visualized and observed.
[0003]
As the acoustic wave, one having an appropriate frequency is selected from an ultrasonic wave, a
photoacoustic wave, and the like according to an object to be detected, a measurement condition,
and the like. For example, the ultrasound diagnostic apparatus transmits ultrasound toward the
inside of the subject, receives ultrasound reflected by the tissue inside the subject, and displays
the ultrasound as an image. The photoacoustic wave measurement apparatus receives an
acoustic wave emitted from the inside of the test object by the photoacoustic effect, and displays
it as an image. The photoacoustic effect is an acoustic wave (a subject that absorbs the
electromagnetic wave, generates heat, and thermally expands when the subject is irradiated with
an electromagnetic wave pulse such as visible light, near infrared light, or microwave). Typically,
this is a phenomenon in which ultrasonic waves are generated. Since the acoustic wave
measuring apparatus transmits and receives acoustic waves to and from the living body to be
tested, requirements such as matching of the acoustic impedance with the living body (typically a
human body) and reduction of the acoustic wave attenuation amount are required. It is required
to meet.
[0004]
For example, a probe for an ultrasonic diagnostic apparatus (also referred to as an ultrasonic
probe), which is a type of acoustic wave probe, includes a piezoelectric element that transmits /
receives ultrasonic waves and an acoustic lens that is a portion in contact with a living body. The
ultrasonic wave emitted from the piezoelectric element passes through the acoustic lens and is
incident on the living body. If the difference between the acoustic impedance (density × sound
velocity) of the acoustic lens and the acoustic impedance of the living body is large, the
ultrasonic wave is reflected on the surface of the living body, so that it does not efficiently enter
the living body. Therefore, it is difficult to obtain good resolution. In addition, in order to transmit
and receive ultrasonic waves with high sensitivity, it is desirable that the amount of ultrasonic
attenuation of the acoustic lens be small. For this reason, as one of the materials of the acoustic
lens, it is close to the acoustic impedance of the living body (in the case of the human body, 1.4
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to 1.7 × 10 6 <6> kg / m 2> / sec), and the ultrasonic attenuation amount is Small silicone resins
are used.
[0005]
As a composition for an acoustic lens, for example, Patent Document 1 describes that an
inorganic filler (alumina or titanium oxide powder) and a thermoplastic resin powder such as
nylon powder are added to a silicone rubber compound. Also, U.S. Pat. No. 5,959,015 is directed
to making a cured silicone product comprising an organopolysiloxane containing silicon-bonded
alkenyl groups, an organohydrogenpolysiloxane containing silicon-bonded hydrogen atoms, an
alumina filler, a polyether and a hydrogenation catalyst. Silicone compositions have been
described.
[0006]
Japanese Patent Application Laid-Open No. 62-11897 Patent Document No. 2004-533515
[0007]
Silicone resins are soft alone and have low mechanical strength.
Therefore, in order to improve the hardness and mechanical strength, the inorganic filler (also
referred to as inorganic filler) and the vinyl group-containing resin (also referred to as
reinforcing agent) are blended while increasing the molecular weight of the vinyl silicone resin at
both ends. It is done. However, in order to achieve the required mechanical strength, the amount
of addition of the inorganic filler and the vinyl group-containing resin to the silicone resin is
necessarily large, and conversely, the silicone resin becomes large in acoustic wave attenuation.
Therefore, resin hardness, mechanical strength, and acoustic wave required for the acoustic wave
probe are required for the acoustic wave probe prepared from the composition for acoustic lens
of Patent Document 1 and the silicone composition described in Patent Document 2 above. It is
difficult to satisfy all of the attenuation reductions at high levels. In view of the above situation,
the present invention is for an acoustic wave probe having an acoustic impedance close to that of
a living body and reduced acoustic wave attenuation, and excellent in hardness and mechanical
strength (tensile modulus, tensile elongation at break and tensile durability) An object is to
provide a silicone resin. In addition, it is suitably used for preparation of an acoustic wave probe,
an ultrasonic probe, an acoustic wave measurement device, an ultrasonic diagnostic device, a
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photoacoustic wave measurement device, an ultrasonic endoscope, and a silicone resin for an
acoustic wave probe using this resin. An object is to provide a composition for an acoustic wave
probe.
[0008]
In addition, to improve sensitivity in an ultrasonic probe, a photoacoustic wave measuring
apparatus, and an ultrasonic endoscope that use capacitive micromachined ultrasonic
transducers (cMUTs: cacMUT: ultrasonic transducers for ultrasonic diagnosis) It is also an object
of the present invention to provide an acoustic wave probe composition and a silicone resin for
an acoustic wave probe that can
[0009]
As a result of intensive studies, the present inventors have found that the silicone resin contains
a specific structural unit, and contains at least one type of inorganic oxide, and an aggregate
having an average particle diameter within a specific range. It has been found that the silicone
resin to be used has an acoustic impedance close to that of a living body, has a reduced amount
of acoustic wave attenuation, is excellent in hardness and mechanical strength, and can be
suitably used for an acoustic wave probe.
The present invention was made based on this finding.
[0010]
The above problems are solved by the following means. The polymer which comprises the
aggregate which is an average particle diameter of 200 nm-10 micrometers which comprises <1>
at least 1 sort of inorganic oxides, and which comprises a resin component is represented by
following formula (1) to a molecular chain Silicone resin for an acoustic wave probe having at
least two structural units. <img class = "EMIRef" id = "410531845-00003" />
[0011]
The silicone resin for acoustic wave probes as described in <1> whose average particle diameter
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of a <2> aggregate is 200 nm-5 micrometers. The silicone resin for acoustic wave probes as
described in <1> or <2> whose average primary particle diameter of <3> inorganic oxide is less
than 100 nm. The silicone resin for acoustic wave probes as described in any one of <1>-<3>
whose average primary particle diameter of <4> inorganic oxide is less than 25 nm. The silicone
resin for acoustic wave probes as described in any one of <1>-<4> by which the <5> inorganic
oxide is surface-treated by the silane compound. <6> Any one of <1> to <5>, wherein the
inorganic oxide is selected from the group consisting of magnesium oxide, titanium oxide, iron
oxide, zinc oxide, zirconium oxide, barium oxide, tin oxide and ytterbium oxide Silicone resin for
an acoustic wave probe as described in.
[0012]
A composition containing a polysiloxane mixture having a <7> vinyl group, a polysiloxane having
two or more Si-H groups in a molecular chain, and a polysiloxane mixture containing at least one
inorganic oxide is cured and reacted. The silicone resin for acoustic wave probes as described in
any one of <1>-<6>. The silicone resin for acoustic wave probes as described in <7> in which a
<8> composition contains 0.1-20 mass parts of at least 1 type of modified silicone dispersing
agent in 100 mass parts of polysiloxane mixtures. <9> The silicone resin for acoustic wave probe
according to <8>, wherein the modified silicone dispersant is a polyether modified or
polyglycerin modified silicone. The silicone resin for acoustic wave probes as described in <8> or
<9> whose HLB value of a <10> modified silicone dispersing agent is 2-5. The silicone resin for
acoustic wave probes as described in any one of <7>-<10> in which a <11> composition contains
10-60 mass parts of inorganic oxides in 100 mass parts of polysiloxane mixtures. The <12>
composition contains 10 to 99.4 parts by mass of a polysiloxane having a vinyl group, and
polysiloxane having two or more Si-H groups in a molecular chain in 100 parts by mass of the
total of the polysiloxane mixture. Silicone resin for acoustic wave probes as described in any one
of <7>-<11> which contains 0.5-90 mass parts. The silicone resin for acoustic wave probes as
described in any one of <7>-<11> in which a <13> aggregate is obtained by the mechanical
dispersion process in a mixture. The silicone resin for acoustic wave probes as described in any
one of <7>-<13> whose mass mean molecular weights of the polysiloxane which has a <14> vinyl
group are 20,000-200,000. The silicone resin for acoustic wave probes as described in any one
of <7>-<14> whose mass mean molecular weights of the polysiloxane which has a <15> vinyl
group are 40,000-150,000. The acoustic wave as described in any one of <7>-<15> in which a
<16> composition contains 0.00001-0.05 mass part of platinum or a platinum containing
compound with respect to 100 mass parts of polysiloxane mixtures. Probe silicone resin.
[0013]
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<17> An acoustic wave probe having at least one member selected from the group consisting of
an acoustic lens and an acoustic matching layer, comprising the silicone resin for an acoustic
wave probe according to any one of <1> to <16>. . The ultrasonic probe provided with the
acoustic lens which comprises the silicone resin for acoustic wave probes as described in any one
of <18> capacitive micromachined ultrasonic transducer | vibrator and <1>-<16>. The acoustic
wave measuring device provided with the acoustic wave probe as described in <19> <17>. <20>
An ultrasound diagnostic apparatus comprising the acoustic wave probe according to <17>. The
photoacoustic wave measuring apparatus provided with the acoustic lens which comprises the
silicone resin for acoustic wave probes as described in any one of <21> <1>-<16>. The ultrasonic
endoscope provided with the acoustic lens which consists of silicone resin for acoustic wave
probes as described in any one of <22> <1>-<16>. <23> A composition for acoustic probe
comprising a polysiloxane mixture having a vinyl group, a polysiloxane having two or more Si̶H
groups in a molecular chain, and a polysiloxane mixture containing at least one inorganic oxide,
A silicone resin for an acoustic wave probe, which is produced by curing and reacting a
composition for an acoustic probe, contains an aggregate comprising at least one inorganic oxide,
and the average particle diameter of the aggregate is 200 nm to 10 μm. Probe composition.
[0014]
In the description of the present invention, when groups having the same symbol are present in
the general formula, they may be identical to or different from one another unless otherwise
noted, and groups specified by each group (for example, alkyl groups) May be further substituted
by a substituent. Moreover, in description of this invention, "-" is used in the meaning included
including the numerical value described before and after that as a lower limit and an upper limit.
In addition, the mass mean molecular weight in this invention is a measured value (polystyrene
conversion) by gel permeation chromatography (GPC) unless there is particular notice.
[0015]
The silicone resin for an acoustic wave probe according to the present invention has an acoustic
impedance close to that of a living body, a reduced amount of acoustic wave (particularly
preferably ultrasonic wave) attenuation, and excellent hardness and mechanical strength. The
silicone resin for an acoustic wave probe of the present invention can be suitably used for an
acoustic wave probe, an ultrasonic probe, an acoustic wave measurement device, an ultrasonic
diagnostic device, a photoacoustic wave measurement device, and an ultrasonic endoscope.
Moreover, the composition for acoustic wave probes of this invention can be used suitably for
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preparation of the silicone resin for acoustic wave probes which has the said outstanding
performance. Furthermore, if the silicone resin for an acoustic wave probe of the present
invention is used, the sensitivity of the acoustic wave probe, the acoustic wave measurement
device, the photoacoustic wave measurement device, and the ultrasonic diagnostic device can be
improved.
[0016]
It is a perspective transmission figure of an example of the convex type | mold ultrasonic probe
which is one aspect | mode of an acoustic wave probe.
[0017]
<Composition for Acoustic Wave Probe> The composition for acoustic wave probe of the present
invention (hereinafter, also simply referred to as a composition).
And the like) is a composition for an acoustic wave probe containing a polysiloxane mixture
having a vinyl group, a polysiloxane having two or more Si-H groups in a molecular chain and a
polysiloxane mixture containing at least one inorganic oxide. . The silicone resin of the present
invention is preferably prepared by curing the composition of the present invention.
[0018]
In the present invention, the content of polysiloxane having a vinyl group is preferably 10 to
99.4 parts by mass in the total 100 parts by mass of the above-mentioned polysiloxane mixture,
and has two or more Si-H groups in the molecular chain. The content of polysiloxane is
preferably 0.5 to 90 parts by mass. In addition, as for content of the polysiloxane which has a
vinyl group, 50-90 mass parts is more preferable, and content of the polysiloxane which has 2 or
more Si-H group in a molecular chain is 0.5-50 mass parts Is more preferred. 10 to 60 parts by
mass is preferable, 20 to 50 parts by mass is more preferable, 25 to 45 parts by mass is more
preferable, and 25 to 35 parts by mass is 100 parts by mass of the polysiloxane mixture in total.
Particularly preferred. In addition, a polysiloxane mixture is a mixture which does not contain the
catalyst which carries out the cross-linking polymerization of the polysiloxane which has a vinyl
group, and the polysiloxane which has two or more Si-H groups in a molecular chain. Therefore,
the polysiloxane mixture includes the non-catalyst inorganic oxide and the dispersant which is an
optional component described later.
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[0019]
Each of the above-mentioned polysiloxanes contained in the polysiloxane mixture has a vinyl
group or two or more Si-H groups in the molecular chain, and forms a structural unit represented
by the following formula (1) by hydrosilylation Any polysiloxane may be used as long as it is
suitable. <img class = "EMIRef" id = "410531845-00004" />
[0020]
In the present invention, a polyorganosiloxane (A) having a vinyl group and a polyorganosiloxane
(B) having two or more Si-H groups in the molecular chain are preferred. Therefore, in the
present invention, a polyorganosiloxane having a vinyl group (A), a polyorganosiloxane having
two or more Si-H groups in a molecular chain (B), and at least one inorganic substance in a
polyorganosiloxane mixture It is preferable to contain at least an oxide. In the following detailed
description, polyorganosiloxane (A) having a vinyl group and polyorganosiloxane (B) having two
or more Si-H groups in a molecular chain, which are preferred embodiments, are described.
However, the present invention is not limited to the embodiments described below.
[0021]
<Polyorganosiloxane (A) having a vinyl group> The polyorganosiloxane (A) having a vinyl group
used in the present invention (hereinafter, also simply referred to as polyorganosiloxane (A). )
Have two or more vinyl groups in the molecular chain. The polyorganosiloxane (A) having a vinyl
group is, for example, a polyorganosiloxane (a) having a vinyl group at least at both molecular
chain terminals (hereinafter, also simply referred to as polyorganosiloxane (a)), or a molecular
chain. Polyorganosiloxane (b) having at least two -O-Si (CH3) 2 (CH = CH2) in (hereinafter, also
simply referred to as polyorganosiloxane (b). Can be mentioned. Among them,
polyorganosiloxane (a) having vinyl groups at least at both molecular chain terminals is
preferable. The polyorganosiloxane (a) is preferably linear, and the polyorganosiloxane (b) is a
poly having -O-Si (CH 3) 2 (CH = CH 2) bonded to the Si atom constituting the main chain.
Organosiloxanes (b) are preferred.
[0022]
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The polyorganosiloxane (A) having a vinyl group is hydrosilylated by the reaction with a
polyorganosiloxane (B) having two or more Si-H groups in the presence of a platinum catalyst.
This hydrosilylation reaction (addition curing reaction) forms a crosslinked structure.
[0023]
The content of the vinyl group in the polyorganosiloxane (A) is not particularly limited. In
addition, from a viewpoint of forming a sufficient network between each component contained in
the composition for acoustic wave probes, it is 0.01-5 mol%, for example, Preferably it is 0.05-2
mol%. Here, the content of the vinyl group is mol% of the vinyl group-containing siloxane unit
when the total unit constituting the polyorganosiloxane (A) is 100 mol%, and the Si̶O unit
constituting the main chain And 100 mol% if all Si atoms of the terminal Si are substituted with
at least one vinyl group. In addition, a unit means Si-O unit which comprises a principal chain,
and Si of the terminal.
[0024]
The degree of polymerization and specific gravity are not particularly limited. In addition, silicone
resin for acoustic wave probes obtained (hereinafter, also simply referred to as silicone resin).
The degree of polymerization is preferably 200 to 3,000, more preferably 400 to 2,000, and the
specific gravity is preferably 0.9 to 1.1, from the viewpoint of improvement in mechanical
strength, hardness, chemical stability and the like.
[0025]
The mass average molecular weight of the polyorganosiloxane (A) having a vinyl group is
preferably 20,000 to 200,000, more preferably 40,000 to 150,000, from the viewpoint of
mechanical strength, hardness, and processability. And 45,000 to 120,000 are more preferable.
[0026]
The mass average molecular weight is prepared, for example, using GPC apparatus HLC-8220
(manufactured by Tosoh Corp.), using toluene (manufactured by Shonan Wako Pure Chemical
Industries, Ltd.) as an eluent and TSKgel (registered trademark, Tosoh Corp.) G3000HXL +
TSKgel as a column. (Registered trademark, Tosoh Corporation) G2000HXL can be used for
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measurement at a temperature of 23 ° C. and a flow rate of 1 mL / min using an RI detector.
[0027]
The kinematic viscosity at 25 ° C. is preferably 1 × 10 <−5> to 10 m <2> / s, more preferably
1 × 10 <−4> to 1 m <2> / s, 1 × 10 <−3> It is further preferable that ∼0.5 m <2> / s.
[0028]
The polyorganosiloxane (a) having a vinyl group at least at both molecular chain terminals is
preferably a polyorganosiloxane represented by the following general formula (A).
[0029]
<img class = "EMIRef" id = "410531845-000005" />
[0030]
In formula (A), R <a1> represents a vinyl group, and R <a2> and R <a3> each independently
represent an alkyl group, a cycloalkyl group, an alkenyl group or an aryl group.
Each of x1 and x2 independently represents an integer of 1 or more.
Here, the plurality of R <a2> and the plurality of R <a3> may be the same or different from one
another.
Moreover, each group of R <a2> and R <a3> may be further substituted by a substituent.
[0031]
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.
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The alkyl group is, for example, methyl group, ethyl group, n-propyl group, isopropyl group, nbutyl group, isobutyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-decyl group It
can be mentioned.
[0032]
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 are more preferable.
The cycloalkyl group is preferably a 3-, 5- or 6-membered ring, more preferably a 5- or 6membered ring. Examples of the cycloalkyl group include cyclopropyl group, cyclopentyl group
and cyclohexyl group.
[0033]
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 group,
allyl group and butenyl group.
[0034]
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 group, tolyl
group and naphthyl group.
[0035]
These alkyl group, cycloalkyl group, alkenyl group and aryl group may have a substituent. Such
substituents include, for example, halogen atoms, alkyl groups, cycloalkyl groups, alkenyl groups,
aryl groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, silyl groups and
cyano groups. As a group which has a substituent, a halogenated alkyl group is mentioned, for
example.
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[0036]
An alkyl group, an alkenyl group, or an aryl group is preferable, R <a2> and R <a3> have a C1-C4
alkyl group, a vinyl group, or a phenyl group is more preferable, and a methyl group or a vinyl
group is more preferable. Among them, a methyl group is preferable, R <a2> is preferably a
methyl group or a vinyl group, and a methyl group is particularly preferable.
[0037]
The integer of 200-3000 is preferable and, as for x1, the integer of 400-2000 is more preferable.
The integer of 1-1000 is preferable and, as for x2, the integer of 40-700 is more preferable.
[0038]
Polyorganosiloxanes having vinyl groups at least at both molecular chain ends are, for example,
trade names manufactured by Gelest, DMS series (eg, DMS-V31, DMS-V31S15, DMS-V33, DMSV35, DMS-V35R, DMS) -V41, DMS-V42, DMS-V46, DMS-V51, DMS-V52), trade names made by
Gelest, PDV series (for example, PDV-0341, PDV-0346, PDV-0535, PDV-0541, PDV- 1631, PDV1635, PDV-1641, PDV-2335, PMV-9925, PVV-3522, FMV-4031, EDV-2022). In addition, since
fumed silica is mix | blended beforehand, DMS-V31 S15 does not need kneading | mixing in a
special apparatus.
[0039]
As the polyorganosiloxane (A) having a vinyl group in the present invention, only one type may
be used alone, or two or more types may be used in combination.
[0040]
<Polyorganosiloxane (B) having two or more Si-H groups in the molecular chain>
Polyorganosiloxane (B) having two or more Si-H groups in the molecular chain used in the
present invention Also simply referred to as polyorganosiloxane (B).
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) Have two or more Si-H groups in the molecular chain. By having two or more Si-H groups in the
molecular chain, it is possible to crosslink a polyorganosiloxane having at least two
polymerizable unsaturated groups.
[0041]
The polyorganosiloxane (B) has a linear structure and a branched structure, and is preferably a
linear structure. The mass average molecular weight of the linear structure is preferably 500 to
100,000, and more preferably 1,500 to 50,000, from the viewpoint of mechanical strength and
hardness.
[0042]
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).
[0043]
<img class = "EMIRef" id = "410531845-000006" />
[0044]
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>) Represents.
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 and y2 each
independently represent an integer of 0 or more. Here, a plurality of R <b1>, a plurality of R
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<b2>, a plurality of R <b3>, a plurality of R <b4>, a plurality of R <b5>, a plurality of R <b6> and a
plurality of R <b7 In each group,> may be the same as or different from each other, and 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.
[0045]
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
range is also the same. is there. The alkyl group, cycloalkyl group, alkenyl group and aryl group
for R <b3> have the same meanings as the alkyl group, cycloalkyl group, alkenyl group and aryl
group for R <a2> and R <a3>, and the preferred range is also the same. It is.
[0046]
The alkyl group, cycloalkyl group and aryl group in R <b4> and R <b5> of -O-Si (R <b5>) 2 (R
<b4>) are alkyls in R <b1> and R <b2> It is synonymous with a group, a cycloalkyl group, and an
aryl group, and its preferable range is also the same.
[0047]
The alkyl group, cycloalkyl group, alkenyl group and aryl group in R <b6> and R <b7> of -O-Si (R
<b7>) 2 (R <b6>) is an alkyl group in R <b3> It is synonymous with a cycloalkyl group, an alkenyl
group and an aryl group, and its preferable range is also the same.
[0048]
R <b1> and R <b2> each is preferably a hydrogen atom, an alkyl group, an aryl group or -O-Si (R
<b5>) 2 (R <b4>), and is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms A phenyl
group or -O-Si (CH3) 2H is more preferable, and a hydrogen atom or a methyl group is more
preferable.
R <b3> is preferably a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or -O-Si (R
<b7>) 2 (R <b6>), and a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, vinyl A
group, a phenyl group or -O-Si (CH3) 2H is more preferable, and a hydrogen atom or a methyl
group is more preferable.
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[0049]
The integer of 0-2000 is preferable, the integer of 0-50 is more preferable, the integer of 0-30 is
further more preferable, and 0 is especially preferable.
The integer of 2-2000 is preferable, the integer of 2-50 is more preferable, and the integer of 230 is still more preferable. The integer of 5-2000 is preferable, the integer of 7-1000 is more
preferable, 10-50 are further more preferable, and the integer of 15-30 is especially preferable.
[0050]
As a combination of R <b1> to R <b3>, R <b1> is an alkyl group having 1 to 4 carbon atoms, R
<b2> is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R <b3> is A hydrogen
atom or a combination of a C1-C4 alkyl group is preferable, R <b1> is a C1-C4 alkyl group, R
<b2> is a C1-C4 alkyl group, R <b3> is hydrogen A combination of atoms is more preferred.
Further, a combination of R <b1> and R <b2> with a methyl group and R <b3> with a hydrogen
atom is particularly preferable. In this preferable combination, the content of the hydrosilyl
group represented by y2 / (y1 + y2) is preferably more than 0.2 and 1.0 or less, more preferably
0.4 or more and 1.0 or less, and 1.0 Is particularly preferred.
[0051]
The polyorganosiloxane (B) having a linear structure is, for example, HMS-064 (MeHSiO: 5-7
mol%), which is a methylhydrosiloxane-dimethylsiloxane copolymer (trimethylsiloxane end)
manufactured by Gelest, HMS- 082 (MeHSiO: 7-8 mol%), HMS-301 (MeHSiO: 25-30 mol%), HMS501 (MeHSiO: 50-55 mol%), HMS-992 (MeHSiO: 100 mol%). Here, mol% of MeHSiO is
synonymous with y2 / (y1 + y2) × 100.
[0052]
Both linear and branched structures preferably have no vinyl group from the viewpoint of
preventing the progress of the crosslinking reaction in the molecule, and particularly those
having a branched structure do not have a vinyl group. Is preferred.
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[0053]
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 polyorganosiloxane (B) having a branched
structure is preferably one represented by the following average composition formula (b).
[0054]
Average composition formula (b): [H a (R <b8>) 3-a SiO 1/2] y3 [SiO 4/2] y4
[0055]
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 represent an integer of 1 or more.
[0056]
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 range is also the same. It is.
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, and more preferably more than 0.1 and less than 0.4.
[0057]
On the other hand, when the polyorganosiloxane (B) having a branched structure is represented
by a chemical structural formula, a polyorganosiloxane in which ̶O̶Si (CH 3) 2 (H) is bonded
to the Si atom constituting the main chain is preferable. Those having a structure represented by
04-05-2019
16
the following general formula (Bb) are more preferable.
[0058]
<img class = "EMIRef" id = "410531845-000007" />
[0059]
In the general formula (Bb), * means to bond to at least the Si atom of siloxane.
[0060]
The polyorganosiloxane (B) having a branched structure is, for example, HQM-107 (trade name,
manufactured by Gelest, hydrogenated Q resin), HDP-111 (trade name, manufactured by Gelest,
polyphenyl- (dimethylhydroxy) siloxane (Hydrogen end), [(HMe2SiO) (C6H5Si) O]: 99-100 mol%).
[0061]
The polyorganosiloxane (B) having two or more Si-H groups in the molecular chain in the present
invention may be used alone or in combination of two or more.
Moreover, you may use combining the polyorganosiloxane (B) of a linear structure, and the
polyorganosiloxane (B) of a branched structure.
[0062]
<Inorganic oxide> The inorganic oxide in the present invention is a component to be added for
the purpose of improving the hardness and mechanical strength of the silicone resin to be
obtained, in particular, improving the tensile strength.
[0063]
The average primary particle diameter of the inorganic oxide in the present invention is
preferably less than 100 nm, more preferably less than 25 nm, still more preferably less than 20
nm, from the viewpoint of suppressing the increase in acoustic wave attenuation of the silicone
04-05-2019
17
resin and improving the tensile strength. Particularly preferred is less than 15 nm.
The lower limit is not particularly limited, but it is practical to exceed 3 nm.
The smaller the average primary particle diameter is in the above range, the higher the tensile
strength and the better the acoustic wave sensitivity, which is preferable.
This is considered to be due to the fact that the fine inorganic oxide functions as a stopper to
suppress the occurrence of cracks in the silicone resin by mechanical stress.
In particular, since the distance between the inorganic oxide particles is reduced due to the small
average primary particle diameter, it is presumed that the function as a stopper is more exhibited
and the tensile strength of the silicone resin is significantly improved.
[0064]
The average primary particle size is described in the catalog of the manufacturer of the inorganic
oxide particles. However, those in which the average primary particle diameter is not described
in the catalog or those newly manufactured can be determined by averaging the particle
diameters measured by Transmission Electron Microscopy (TEM). That is, for one particle of an
electron micrograph taken by TEM, the minor axis and the major axis are measured, and the
average value is determined as the particle size of one particle. In the present specification, the
particle sizes of 300 or more particles are averaged to obtain an average primary particle size.
Moreover, when the surface treatment mentioned later is performed to inorganic oxide particle,
the average primary particle diameter in the surface-treated state is meant.
[0065]
The specific gravity of the inorganic oxide particles in the present invention is not particularly
limited, but is preferably 2.0 or more and 10.0 or less, the lower limit is more preferably 3.5 or
more, and particularly preferably 5.0 or more. Specifically, an inorganic oxide selected from the
group consisting of magnesium oxide, titanium oxide, iron oxide, zinc oxide, zirconium oxide,
barium oxide, tin oxide and ytterbium oxide is preferred, and titanium oxide, zinc oxide,
04-05-2019
18
zirconium oxide, oxide More preferred is an inorganic oxide selected from the group consisting
of barium, tin oxide and ytterbium oxide, more preferred is an inorganic oxide selected from the
group consisting of zinc oxide, zirconium oxide, barium oxide, tin oxide and ytterbium oxide, and
oxidized Zinc is particularly preferred. This is because the inorganic oxide particles having a
larger specific gravity can increase the acoustic impedance with a smaller addition amount, and
can be closer to the value of the human body.
[0066]
Only one inorganic oxide particle may be used alone, or two or more inorganic oxide particles
may be used in combination.
[0067]
The inorganic oxide particles in the present invention preferably have a specific surface area of
50 to 400 m <2> / g, more preferably 100 to 400 m <2> / g, from the viewpoint of improving
the hardness and mechanical strength of the obtained silicone resin.
[0068]
The inorganic oxide particle in the present invention is preferably an inorganic oxide particle in
which the surface of the particle is treated, and more preferably an inorganic oxide particle
which is surface-treated with a silane (silicon) compound.
By treating the surface of the inorganic oxide particles with a silane compound, the interaction
with the silicone resin becomes strong, and the affinity with the silicone resin becomes high, so
the finely dispersed inorganic oxide particles having a small average primary particle diameter
can be obtained. Will be possible.
For this reason, it is considered that the inorganic oxide fine particles more function as a stopper
when mechanical adaptability is applied, and the hardness and mechanical strength of the
silicone resin are improved. The surface treatment method may be any conventional method.
Examples of the method of surface treatment with a silane compound include a method of
surface treatment with a silane coupling agent and a method of coating with a silicone
compound. In the present invention, a method of surface treatment with a silane coupling agent
is preferred.
04-05-2019
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[0069]
(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 mechanical strength of
the silicone resin. The hydrolyzable group in the silane coupling agent is hydrolyzed by water to
become a hydroxyl group, and the hydroxyl group is subjected to dehydration condensation
reaction with the hydroxyl group on the surface of the inorganic oxide particle to perform
surface modification of the inorganic oxide particle, The hardness and mechanical strength of the
obtained silicone resin are improved. Examples of the hydrolyzable group include an alkoxy
group, an acyloxy group, and a halogen atom. In addition, when the surface of the inorganic
oxide particles is surface-modified to be hydrophobic, the affinity between the inorganic oxide
particles and the polyorganosiloxanes (A) and (B) becomes good, and the hardness of the
obtained silicone resin and It is preferable because mechanical strength is improved.
[0070]
As a silane coupling agent having a hydrophobic group as a functional group, for example,
methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane,
methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltriol Alkoxysilanes
such as methoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane,
decyltrimethoxysilane; methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane,
chlorosilanes such as phenyltrichlorosilane, hexasilane Methyl disilazane (HMDS) is mentioned.
[0071]
Also, as a silane coupling agent having a vinyl group as a functional group, for example,
methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane,
methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane,
vinyltriethoxy And silanes, vinyltrimethoxysilane, alkoxysilanes such as
vinylmethyldimethoxysilane; vinyltrichlorosilane, chlorosilanes such as
vinylmethyldichlorosilane; and divinyltetramethyldisilazane.
[0072]
The inorganic oxide particles surface-treated with a silane coupling agent are preferably
inorganic oxide particles treated with a trialkylsilylating agent, and more preferably inorganic
oxide particles treated with a trimethylsilylating agent.
04-05-2019
20
As a silane compound, the said silane coupling agent and the silane coupling agent by which the
functional group in the silane coupling agent was substituted by the alkyl group are mentioned,
for example.
Further, as the trimethylsilylating agent, for example, trimethylchlorosilane described in the
above-mentioned silane coupling agent, hexamethyldisilazane (HMDS), and
trimethylmethoxysilane which is a silane coupling agent in which a functional group is
substituted by an alkyl group are mentioned. Be
[0073]
Examples of commercially available silane coupling agents include hexamethyldisilazane (HMDS)
(trade name: HEXAMETHYLDISILAZANE (SIH 611 0.1), manufactured by Gelest). The hydroxyl
group present on the inorganic oxide particle surface is covered with a trimethylsilyl group by
the reaction with hexamethyldisilazane (HMDS), and the inorganic oxide particle surface is
modified to be hydrophobic.
[0074]
(Ii) Silicone Compound The silicone compound covering the inorganic compound particles (C)
may be a polymer composed of siloxane bonds. As the silicone compound, for example, a silicone
compound in which all or a part of the side chain or end of the polysiloxane is a methyl group, a
silicone compound in which a part of the side chain is a hydrogen atom, all or one of a side chain
or an end The modified silicone compound which introduce | transduced organic groups, such as
an amino group and an epoxy group, into the part, The silicone resin which has a branched
structure is mentioned. The silicone compound may have a linear or cyclic structure.
[0075]
Examples of silicone compounds in which all or part of the side chains and ends of the
polysiloxane are methyl groups include, for example, polymethylhydrosiloxane (hydrogen end),
polymethylhydrosiloxane (trimethylsiloxy end), polymethylphenylsiloxane ( Hydrogenterminated), monomethylpolysiloxanes such as polymethylphenylsiloxane (trimethylsiloxyterminated), for example dimethylpolysiloxanes (hydrogen-terminated), dimethylpolysiloxanes
04-05-2019
21
(trimethylsiloxy-terminated), dimethylpolysiloxanes such as cyclic dimethylpolysiloxane It can be
mentioned.
[0076]
Examples of silicone compounds in which part of the side chain is a hydrogen atom include
methylhydrosiloxane-dimethylsiloxane copolymer (trimethylsiloxy-terminated),
methylhydrosiloxane-dimethylsiloxane copolymer (hydrogen-terminated),
polymethylhydrosiloxane (hydrogen-terminated) , Polymethylhydrosiloxane (trimethylsiloxyterminated), polyethylhydrosiloxane (triethylsiloxy-terminated), polyphenyl(dimethylhydrosiloxy) siloxane (hydrogen-terminated), methylhydrosiloxanephenylmethylsiloxane copolymer (hydrogen-terminated), methylhydro Siloxane-octylmethyl
siloxane copolymer terpolymers may be mentioned.
[0077]
Moreover, as modified silicone which introduce | transduced the organic group, an amino group,
an epoxy group, a methoxy group, a (meth) acryloyl group, a phenol group, carboxylic acid
anhydride group, a hydroxy group, a mercapto group, a carboxy group, a hydrogen atom is
mentioned, for example. Reactive silicones introduced with organic groups of, for example,
polyether, aralkyl, fluoroalkyl, long chain alkyl, long chain aralkyl, higher fatty acid ester, higher
fatty acid amide, non-reactive silicone modified with polyether methoxy Be
[0078]
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 fixed time and filtering.
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 hardness and the machine
of the obtained silicone resin are obtained. Strength is improved.
04-05-2019
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[0079]
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-terminated).
[0080]
The vinyl group possessed by the polyorganosiloxane (A) and the Si-H group possessed by the
polyorganosiloxane (B) are usually reacted stoichiometrically at 1: 1.
However, in the present invention, since the average primary particle diameter of the inorganic
oxide particles is small and the gaps between the polyorganosiloxanes (A) and (B) are closely
packed, the polyorganosiloxanes (A) and (B) The movement of the molecular chains of is limited.
Therefore, in order for all vinyl groups to react with Si-H groups, the equivalent of Si-H groups in
polyorganosiloxane (B) to vinyl groups in polyorganosiloxane (A) is vinyl group: Si- The H group
is preferably 1: 1.1 to 1: 8, more preferably 1: 1.2 to 1: 5.
[0081]
<Other components> The composition for an acoustic wave probe of the present invention
comprises a polyorganosiloxane (A) having a vinyl group, a polyorganosiloxane (B) having two or
more Si-H groups in a molecular chain, and an inorganic oxide In addition to substances,
platinum catalysts for addition polymerization reaction, curing retarders, solvents, dispersants,
pigments, dyes, antistatic agents, antioxidants, flame retardants, thermal conductivity improvers,
etc. can be appropriately blended. .
[0082]
<Catalyst> As the catalyst, for example, platinum or a platinum-containing compound
(hereinafter, also referred to as "platinum compound").
Can be mentioned. Any platinum or platinum compound can be used. Specifically, platinum black,
platinum supported on inorganic oxide or carbon black, etc., chloroplatinic acid or alcohol
04-05-2019
23
solution of chloroplatinic acid, complex salt of chloroplatinic acid and olefin, chloroplatinic acid
and vinylsiloxane Complex salts etc. may be mentioned. The catalyst may be used alone or in
combination of two or more.
[0083]
The content of the catalyst can be appropriately set in the range of the amount of catalyst. The
catalyst is necessary in the hydrosilylation reaction where the Si-H group of polyorganosiloxane
(B) is added to the vinyl group of polyorganosiloxane (A). By the addition curing reaction by
hydrosilylation, the polyorganosiloxane (A) is crosslinked by the polyorganosiloxane (B) to form a
silicone resin. Here, the catalyst may be contained in the acoustic wave probe composition of the
present invention, or may be brought into contact with the acoustic wave probe composition
without being contained in the acoustic wave probe composition. The latter is preferred.
[0084]
Examples of commercially available platinum catalysts include platinum compounds (trade name:
PLATINUM CYCLOVINYLMETHYLSILOXANE COMPLEX IN CYCLIC METHYL VINYLSILOX ANES
(SIP 6832.2), Pt concentration 2% by mass, manufactured by Gelest).
[0085]
When a catalyst is present in the composition for an acoustic wave probe of the present
invention, the amount of catalyst present is 0.00001 to 0.05 mass as Pt based on 100 parts by
mass of the polysiloxane mixture from the viewpoint of reactivity. A part is preferable, 0.000010.01 mass part is more preferable, 0.00002-0.01 mass part is further more preferable, 0.000050.005 mass part is especially preferable.
[0086]
In addition, the curing temperature can be adjusted by selecting an appropriate platinum
catalyst.
For example, platinum-vinyldisiloxane is used for room temperature cure (RTV) below 50 ° C
and platinum-cyclic vinylsiloxane is used for high temperature cure (HTV) above 130 ° C.
04-05-2019
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[0087]
<Dispersing Agent> In order to control the average particle size of the aggregate comprising at
least one inorganic oxide contained in the silicone resin, the composition of the present invention
preferably contains at least one dispersing agent.
The dispersant is not particularly limited, but a modified silicone dispersant is preferred.
Examples of the modified silicone dispersant include polyether modified or polyglycerin modified
silicone. A commercial item can be used in the present invention. Specific examples of the
polyether modified dispersant include KF-6028 (trade name, manufactured by Shin-Etsu
Chemical Co., Ltd.). Specific examples of polyglycerin-modified silicone include KF-6104 (trade
name, manufactured by Shin-Etsu Chemical Co., Ltd.).
[0088]
In the present invention, the HLB (Hydrophile-Lipophile Balance) value of the dispersant is
preferably 2 to 5, more preferably 2 to 4.5, and particularly preferably 3 to 4.5. When the HLB
value is in the above range, the affinity between the inorganic oxide and the polyorganosiloxane
can be enhanced, and the aggregation diameter of the inorganic oxide can be more strictly
controlled. The HLB value can be determined by the Griffin method described in the section of
Examples described later.
[0089]
One dispersant may be used alone, or two or more dispersants may be used in combination.
When using it in combination of 2 or more types, the HLB value of a dispersing agent means the
average value of the HLB value of each dispersing agent. The content of the dispersant is not
particularly limited, but is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 15 parts by
mass, and particularly preferably 0.1 to 12 parts by mass in 100 parts by mass of the
polysiloxane mixture. preferable.
[0090]
04-05-2019
25
<Method of Producing a Composition for an Acoustic Wave Probe> The composition for an
acoustic wave probe of the present invention can be prepared by a conventional method. For
example, it is preferable to obtain by carrying out the mechanical dispersion process of the
component which comprises the composition for acoustic wave probes. Specific examples of the
mechanical dispersion treatment include dispersion treatment performed using a bead mill,
shaker mill, ball mill, hyper mixer, roll mill, ultrasonic homogenizer, and the like. The order of
mixing of the components is not particularly limited. From the viewpoint of obtaining a uniform
composition, at least one of a polyorganosiloxane (A) having a vinyl group and a
polyorganosiloxane (B) having two or more Si-H groups in a molecular chain is first provided. It
is preferable to set it as the polyorganosiloxane mixture which disperse | distributed the
inorganic oxide of this. Thereafter, a catalyst is added to the polyorganosiloxane mixture in which
the inorganic oxide is dispersed, and degassing under reduced pressure, whereby a composition
for an acoustic wave probe can be prepared.
[0091]
<Silicone Resin for Acoustic Wave Probe> <Structural Unit> The silicone resin for acoustic wave
probe of the present invention can be obtained by curing the composition for acoustic wave
probe of the present invention obtained in this manner. The silicone resin for an acoustic wave
probe according to the present invention contains an aggregate comprising at least one inorganic
oxide, and the polymer constituting the resin component has a structural unit represented by the
following formula (1) as a molecular chain Have at least two. Here, an aggregate comprising at
least one inorganic oxide is one in which primary particles (preferably nanoparticles) such as
inorganic oxide are aggregated to form secondary particles. In the present invention, aggregates
of inorganic oxides are preferred. <img class = "EMIRef" id = "410531845-00008" /> Specifically,
for example, a silicone resin for an acoustic wave probe is obtained by heat curing reaction at 20
to 200 ° C for 5 minutes to 500 minutes. Can.
[0092]
<Average Particle Size of Aggregate> The average particle size of the aggregate is 200 nm to 10
μm. When the average particle diameter is in the above range, the acoustic wave sensitivity can
be enhanced while maintaining the hardness and mechanical strength (tensile modulus, tensile
elongation at break and tensile durability). If the average particle diameter is less than 200 nm,
that is, if the inorganic oxide is dispersed too much in the silicone resin, the interaction between
the agglomerated particles becomes weak, and the hardness and mechanical strength of the
04-05-2019
26
silicone resin are deteriorated. On the other hand, if the average particle diameter exceeds 10
μm, that is, if the inorganic oxide is made to aggregate in the silicone resin, attenuation due to
absorption and scattering of acoustic waves occurs strongly, and the amount of acoustic wave
attenuation increases. I can not get enough sensitivity.
[0093]
The average particle diameter is preferably in the range of 200 nm to 5 μm, and more
preferably in the range of 200 nm to 4 μm. By being in the said range, the sensitivity of an
acoustic wave can be kept higher.
[0094]
The average particle diameter of the aggregates is within the above range depending on, for
example, the dispersion method in the above-mentioned composition for acoustic wave probe,
the presence or absence of a dispersant, the average primary particle diameter of inorganic oxide
and the presence or absence of surface treatment It can be set appropriately. In addition, the
average particle size of the aggregates can be measured by the measurement method described
in the section of Examples described later.
[0095]
<Mechanical Strength and Acoustic Wave Properties of Silicone Resin for Acoustic Wave Probe>
The mechanical strength and acoustic wave characteristics of the silicone resin for acoustic wave
probe will be described in detail below. Here, the acoustic wave characteristics will be described
for ultrasonic characteristics. However, the acoustic wave characteristic is not limited to the
ultrasonic wave characteristic, and relates to an acoustic wave characteristic of an appropriate
frequency which is selected according to an object to be examined, a measurement condition, and
the like.
[0096]
[Hardness] The hardness is preferably 25 or more, and more preferably 40 or more. Note that
04-05-2019
27
the practical upper limit is 80 or less. By being in the said range, the deformation |
transformation at the time of incorporating and using as a part of acoustic wave probe can be
prevented. In addition, the hardness of a silicone resin sheet can be calculated | required by the
measuring method as described in the term of an Example.
[0097]
[Tensile Test] The tensile modulus is preferably 1.2 MPa or more, and the tensile elongation at
break is preferably 300% or more. The practical upper limit is 10 MPa or less for the tensile
modulus of elasticity and 1500% or less for the tensile elongation at break. The tensile modulus
of elasticity and the tensile elongation at break of the silicone resin sheet can be determined by
the measurement method described in the section of Examples.
[0098]
[Tensile Durability] A dumbbell-shaped test piece is manufactured according to JIS K6251 (2010)
using a silicone resin sheet having a thickness of 1 mm. Under the same conditions as in the
tensile test, the film is pulled to a tensile elongation of 100%, held in a pulled state for 24 hours,
stopped pulling, and allowed to stand for 24 hours. The acoustic wave (ultrasonic wave)
attenuation amount and sensitivity test described later are performed to determine the difference
in sensitivity of the silicone resin sheet before and after the endurance test. The difference is
preferably less than 0.8 dB, more preferably less than 0.3 dB, and particularly preferably less
than 0.1 dB.
[0099]
[Acoustic Impedance] The acoustic impedance of the silicone resin sheet of the present invention
is preferably as close as possible to that of a living organism (1.4 to 1.7 × 10 6 <6> kg / m 2> /
sec), and 1.1 to 1. 8 × 10 <6> kg / m <2> / sec is preferable, 1.1 to 1.7 × 10 <6> kg / m <2> /
sec is more preferable, 1.2 to 1.6 × 10 <6> kg / m <2> / sec is particularly preferable. In
addition, the acoustic impedance of a silicone resin sheet can be calculated | required by the
method as described in the term of the Example.
[0100]
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[Acoustic Wave (Ultrasonic) Sensitivity] In the evaluation system of the present invention, the
acoustic wave (ultrasonic) sensitivity is preferably -72 dB or more, more preferably -71 dB or
more. In addition, the acoustic wave (ultrasonic wave) sensitivity of a silicone resin sheet can be
calculated | required by the method as described in the term of the Example.
[0101]
The silicone resin for an acoustic wave probe of the present invention is useful as a medical
member, and can be preferably used, for example, in an acoustic wave probe or an acoustic wave
measurement apparatus. The acoustic wave measurement apparatus according to the present
invention is not limited to an ultrasonic diagnostic apparatus or a photoacoustic wave
measurement apparatus, and refers to an apparatus that receives an acoustic wave reflected or
generated from an object to be detected and displays it as an image or signal intensity. . In
particular, the silicone resin for an acoustic wave probe according to the present invention is
provided between an acoustic lens of an ultrasonic diagnostic apparatus or between a
piezoelectric element and an acoustic lens and has a role of matching the acoustic impedance
between the piezoelectric element and the acoustic lens. Materials of acoustic matching layer,
materials of acoustic lens in photoacoustic wave measuring apparatus and ultrasonic endoscope,
and materials of acoustic lens in ultrasonic probe having a capacitive micromachined ultrasonic
transducer (cMUT) as an ultrasonic transducer array It can be used suitably. Specifically, the
silicone resin for an acoustic wave probe of the present invention may be, for example, an
ultrasonic diagnostic apparatus described in JP-A-2005-253751, JP-A-2003-169802, or the like,
JP-A-2013-202050 Preferred for the acoustic wave measuring apparatus such as the
photoacoustic wave measuring apparatus described in Japanese Patent Application Laid-Open
Nos. 2013-188465, 2013-180330, 2013-158435, 2013-154139 etc. Applied.
[0102]
<Acoustic Wave Probe (Probe)> The structure of the acoustic wave probe of the present
invention will be described in more detail based on the structure of the ultrasonic probe in the
ultrasonic diagnostic apparatus described 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 ultrasound probe can be applied to the acoustic wave probe.
04-05-2019
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[0103]
<Ultrasonic probe> The ultrasonic probe 10 is a main component of an ultrasonic diagnostic
apparatus, and has a function of generating an ultrasonic wave and transmitting and receiving an
ultrasonic beam. 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 detected) ing. In
recent years, in order to receive high-order harmonics, a transmitting ultrasonic transducer
(piezoelectric element) and a receiving ultrasonic transducer (piezoelectric element) are made of
different materials and have a laminated structure. Is also proposed.
[0104]
<Piezoelectric Element Layer> The piezoelectric element layer 3 is a portion that generates
ultrasonic waves, and electrodes are attached to both sides of the piezoelectric element, and
when voltage is applied, the piezoelectric element repeatedly vibrates by expansion and
contraction. Ultrasonic waves are generated.
[0105]
As materials for constituting the piezoelectric element, quartz, single crystals such as LiNbO 3,
LiTaO 3, and KNbO 3, thin films such as ZnO and AlN, and sintered bodies such as Pb (Zr, Ti) O 3
series are subjected to polarization processing. So-called ceramic inorganic piezoelectric
materials are widely used.
In general, piezoelectric ceramics such as PZT: lead zirconate titanate having high conversion
efficiency are used. In addition, the piezoelectric element that detects the received wave on the
high frequency side needs sensitivity with a wider bandwidth. For this reason, an organic
piezoelectric material using an organic polymer substance such as polyvinylidene fluoride (PVDF)
is used as a piezoelectric element suitable for high frequency and wide band. Furthermore,
Japanese Patent Application Laid-Open No. 2011-071842 or the like uses MEMS (Micro Electro
Mechanical Systems) technology that exhibits excellent short pulse characteristics and wide band
characteristics, is excellent in mass productivity, and provides an array structure with less
characteristic variation. cMUT is described. In the present invention, any piezoelectric element
material can be preferably used.
04-05-2019
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[0106]
<Backing Material> The backing material 4 is provided on the back surface of the piezoelectric
element layer 3 and suppresses the extra vibration to shorten the pulse width of the ultrasonic
wave, thereby contributing to the improvement of the distance resolution in the ultrasonic
diagnostic image. .
[0107]
<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 silicone resin for an acoustic wave probe according to the present invention has a small
difference from the acoustic impedance (1.4 to 1.7 × 10 6 <6> kg / m 2> / sec) of a living body,
and thus the material of the acoustic matching layer It can be preferably used as The acoustic
matching layer used in the present invention preferably contains 10% by mass or more of a
silicone resin for an acoustic wave probe obtained by curing and reacting the composition for an
acoustic wave probe of the present invention.
[0108]
<Acoustic Lens> The acoustic lens 1 is provided for focusing ultrasonic waves in the slice
direction using refraction to improve resolution. In addition, the body is closely attached to a
living body to be examined, and the ultrasonic wave is matched with the acoustic impedance of
the living body (for the human body, 1.4 to 1.7 × 10 6 <6> kg / m 2> / sec) The ultrasonic
attenuation amount of the acoustic lens 1 itself is required to be small. That is, as the material of
the acoustic lens 1, the sound velocity is sufficiently smaller than the sound velocity of the
human body, the attenuation of the ultrasonic wave is small, and if the acoustic impedance is
close to the value of the skin of a living body such as the human body, the transmission and
reception sensitivity of the ultrasonic wave Will be better. The silicone resin for an acoustic wave
probe of the present invention can be preferably used also as an acoustic lens material. The
acoustic lens used in the present invention preferably contains 10% by mass or more of a silicone
resin for an acoustic wave probe obtained by curing and reacting the composition for an acoustic
wave probe of the present invention.
04-05-2019
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[0109]
The operation of the ultrasonic probe 10 having such a configuration will be described. A voltage
is applied to electrodes provided on both sides of the piezoelectric element to cause the
piezoelectric element layer 3 to resonate, and an ultrasonic signal is transmitted from the
acoustic lens to the test object. At the time of reception, the piezoelectric element layer 3 is
vibrated by a reflection signal (echo signal) from the test object, and the vibration is electrically
converted into a signal to obtain an image.
[0110]
In particular, the acoustic lens comprising the silicone resin for acoustic wave probe of the
present invention can confirm a remarkable sensitivity improvement effect at a transmission
frequency of ultrasonic waves of about 5 MHz or more as a general medical ultrasonic
transducer. In particular, at the transmission frequency of ultrasonic waves of 10 MHz or more, a
particularly remarkable sensitivity improvement effect can be expected. An apparatus in which
an acoustic lens comprising the silicone resin for an acoustic wave probe of the present invention
exerts a function will be described in detail below. In addition, the acoustic lens which comprises
the silicone resin for acoustic wave probes of this invention shows the outstanding effect also
with apparatuses other than the following described.
[0111]
<Ultrasonic probe provided with cMUT (capacitive micromachine ultrasonic transducer)> When
using the cMUT device described in Japanese Patent Application Laid-Open Nos. 2006-157320
and 2011-71842 for a transducer array for ultrasonic diagnosis, it is general In general, its
sensitivity is lower than that of a piezoelectric ceramic (PZT) based transducer. However, by
using the acoustic lens comprising the silicone resin for an acoustic wave probe of the present
invention, it is possible to compensate for the lack of sensitivity of the cMUT. This allows the
sensitivity of the cMUT to be close to the performance of a conventional transducer. In addition,
since the cMUT device is manufactured by the MEMS technology, it is possible to provide a lowcost ultrasonic probe with higher mass productivity and lower cost than the piezoelectric ceramic
probe.
[0112]
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<Photoacoustic Wave Measurement Device by Photo-Ultrasonic Imaging> Photo-ultrasound
imaging (PAI: Photo Acoustic Imaging) described in JP-A-2013-158435 or the like is light
irradiated and irradiated with light (electromagnetic wave) inside the human body. The
ultrasound image generated when the human body tissue adiabatically expands is displayed or
the signal intensity of the ultrasound is displayed. 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 the acoustic lens including the
silicone resin for an acoustic wave probe of the present invention, it is possible to exhibit an
effective effect on this problem.
[0113]
<Ultrasonic Endoscope> The ultrasonic wave in the ultrasonic endoscope described in Japanese
Patent Application Laid-Open No. 2008-311700 and the like has a long signal line cable in
comparison with the body surface transducer due to its structure, so cable loss The problem is to
improve the sensitivity of the transducer. Moreover, it is said that there is no effective sensitivity
improvement means to this subject by the following reasons.
[0114]
First, in the case of an ultrasonic diagnostic apparatus for body surface, an amplifier circuit, an
AD conversion IC, etc. can be installed at the tip of the transducer. On the other hand, since the
ultrasonic endoscope is used by being inserted into the body, there is no installation space for
the transducer, and installation at the tip of the transducer is difficult. Second, the piezoelectric
single crystal employed in the transducer in the ultrasonic diagnostic apparatus for body surface
is difficult to apply to a transducer having a transmission frequency of 7 to 8 MHz or more in
terms of its physical characteristics and process suitability. . However, since ultrasound for
endoscopes is generally a probe with a transmission frequency of 7 to 8 MHz or more of
ultrasound, it is also difficult to improve sensitivity by a piezoelectric single crystal material.
[0115]
However, by using the acoustic lens comprising the silicone resin for acoustic wave probe of the
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present invention, it is possible to improve the sensitivity of the endoscope ultrasonic transducer.
In addition, even when using the same ultrasonic transmission frequency (for example, 10 MHz),
it is particularly effective when using an acoustic lens comprising the silicone resin for an
acoustic wave probe of the present invention in an ultrasonic transducer for an endoscope. Is
demonstrated.
[0116]
Hereinafter, the present invention will be described in more detail based on an embodiment
using an ultrasonic wave as an acoustic wave. Note that the present invention is not limited to
ultrasonic waves, and audio waves of audible frequencies may be used as long as appropriate
frequencies are selected according to an object to be detected, measurement conditions, and the
like.
[0117]
[Example 1] 69.3 parts by mass of vinyl-terminated polydimethylsiloxane (component (A) in
Table 1 below, manufactured by Gelest, trade name "DMS-V42", weight average molecular weight
72,000), methylhydrosiloxane polymer ( Component (B) in Table 1 below, manufactured by
Gelest, trade name "HMS-992", mass average molecular weight 1,900 0.7 parts by mass,
magnesium oxide (specific gravity 3.6, average primary particle diameter 23 nm, hexamethyl) 30
parts by mass of disilazane (HMDS) surface treatment was stirred at a temperature of 30 ° C. for
30 minutes with a bead mill (zirconia beads φ0.5 mm) to prepare a paste (polysiloxane mixture)
in which the components were uniformly dispersed. To this, 0.05 parts by mass of a platinum
catalyst solution (Gelest, trade name "SIP 6832.2", Pt concentration 2% by mass) is added and
mixed, and then defoamed under reduced pressure (0.5 KPa), longitudinal It was placed in a
metal mold of 150 mm × 150 mm × 1 mm depth and heat treated at 60 ° C. for 3 hours to
produce a silicone resin for acoustic wave probe (a sheet of 150 mm × 150 mm × 1 mm
thickness). A silicone resin for acoustic wave probe (a sheet of 150 mm long × 150 mm wide ×
2 mm thick) was similarly produced except that a metal mold of 150 mm long × 150 mm wide
× 2 mm deep was used. Hereinafter, the silicone resin for an acoustic wave probe thus produced
is referred to as a "silicone resin sheet".
[0118]
[Examples 2 to 21] A predetermined silicone resin sheet was produced in the same manner as in
Example 1 except that the composition of the polysiloxane mixture of Example 1 was changed to
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the composition described in Table 1 below.
[0119]
Comparative Example 1 69.3 parts by mass of vinyl-terminated polydimethylsiloxane
(manufactured by Gelest, trade name “DMS-V42”, weight average molecular weight 72,000),
methylhydrosiloxane polymer (manufactured by Gelest, trade name “HMS- 992 ′ ′, mass
average molecular weight 1,900) 0.7 parts by mass, and 30 parts by mass of magnesium oxide
(specific gravity 3.6, average primary particle diameter 330 nm) were kneaded with a kneader
for 30 minutes to obtain a uniform paste.
To this, 0.05 parts by mass of a platinum catalyst solution (manufactured by Gelest, “SIP
6832.2”, Pt concentration 2% by mass) is added and mixed, then degassed under reduced
pressure, put in a 150 mm × 150 mm metal mold, It heat-processed at 3 degreeC for 3 hours,
and produced the predetermined silicone resin sheet.
[0120]
Comparative Examples 2 to 4 A predetermined silicone resin sheet was produced in the same
manner as Comparative Example 1 except that the composition of the polysiloxane mixture of
Comparative Example 1 was changed to the composition shown in Table 1 below.
[0121]
Comparative Example 5 69.3 parts by mass of vinyl-terminated polydimethylsiloxane
(manufactured by Gelest, “DMS-V42”, weight average molecular weight 72,000),
methylhydrosiloxane polymer (manufactured by Gelest, “HMS-992”, mass 0.7 parts by mass of
an average molecular weight of 1,900) and 30 parts by mass of zinc oxide (specific gravity 5.6,
average primary particle diameter 75 nm) previously mixed in a mortar for 5 minutes are mixed
in a kneader for 30 minutes. The resultant was thermally cured with a platinum catalyst to
prepare a predetermined silicone resin sheet.
[0122]
Comparative Examples 6 to 12 A predetermined silicone resin sheet was obtained in the same
manner as Comparative Example 1 except that the composition of the polysiloxane mixture of
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Comparative Example 1 was changed to the composition described in Table 1 below.
In Comparative Example 11, instead of the magnesium oxide of Comparative Example 1, alumina
and nylon powder (manufactured by Toray Industries, Inc., trade name "SP-500", average particle
diameter 500 nm) were used in combination.
Nylon powder is also listed in the inorganic oxide line for convenience. Further, the agglomerated
particle size is the particle size of the agglomerate comprising alumina and nylon powder.
[0123]
<Method of Measuring Average Particle Size of Aggregate> The cross section of the prepared
silicone resin sheet was measured by SEM (Scanning Electron Microscope) to obtain an
observation image of an inorganic oxide aggregate in silicone. The image was binarized to
determine the equivalent circle diameter. Specifically, the measurement was performed at a
magnification of 5000, and the circle equivalent diameter of 100 aggregates in the observation
field of view was determined by one measurement. The measurement was repeated five times in
the same manner, and the average value of the equivalent circle diameters obtained was taken as
the average particle size of the aggregates. In Table 1 below, the average particle size of the
aggregates is described as the aggregated particle size. In addition, SEM used the Hitachi HighTechnologies company make, brand name SU-8030 SEM.
[0124]
<Method of Measuring HLB Value> The HLB value was calculated by the Griffin method using the
following equation. HLB value = 20 × (sum of the formula weight of the hydrophilic part of
polyether modified silicone) / (molecular weight of polyether modified silicone)
[0125]
<Evaluation of mechanical strength and ultrasonic characteristics> The silicone resin sheets of
Examples 1 to 21 and Comparative Examples 1 to 12 were evaluated as follows.
[0126]
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[Hardness] With respect to the obtained silicone resin sheet having a thickness of 2 mm, the type
A durometer hardness was measured using a rubber hardness meter ("RH-201A" manufactured
by Excell Co., Ltd.) according to JIS K6253-3 (2012).
[0127]
[Tensile Test] A dumbbell-shaped test piece was produced from the obtained silicone resin sheet
having a thickness of 1 mm in accordance with JIS K6251 (2010), and the tensile elastic modulus
and the tensile elongation at break were measured.
[0128]
[Sound Attenuating Tensile Durability Test] A dumbbell-shaped test piece was produced
according to JIS K6251 (2010) using a silicone resin sheet having a thickness of 1 mm.
Under the same conditions as in the tensile test, the film was pulled to a tensile elongation of
100%, held in a pulled state for 24 hours, then stopped pulling and allowed to stand for 24
hours.
The acoustic wave (ultrasonic wave) attenuation amount and sensitivity test described later were
conducted to determine the difference in sensitivity of the silicone resin sheet before and after
the endurance test.
Those with a difference of less than 0.1 dB "A", those with less than 0.3 dB "B", those with less
than 0.8 dB "C", 0.8 dB or more, or those that break during endurance test Let D be "D". Here, the
smaller the difference, the better the tensile durability, "C" indicates usable, and "D" indicates
unusable.
[0129]
[Acoustic Impedance] The obtained silicone resin sheet having a thickness of 2 mm was
subjected to an electron densitometer (alpha mirage) according to the density measurement
method of Method A (substitution method in water) described in JIS K7112 (1999). It measured
using company make and brand name "SD-200L"). Ultrasonic speed of sound is measured at 25
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° C. according to JIS Z 2353 (2003) using a single-around sound speed measuring device
(manufactured by Ultrasonic Industry Co., Ltd., trade name “UVM-2 type”), and the measured
density and speed of sound The acoustic impedance was determined from the product of
[0130]
[Acoustic wave (ultrasonic wave) sensitivity] Ultrasonic probe (one wave) of a 5 MHz sine wave
signal (one wave) output from an ultrasonic oscillator (function generator, product name: "FG350" manufactured by Iwatsu Measurement Co., Ltd.) An ultrasonic pulse wave having a center
frequency of 5 MHz was generated in water from an ultrasonic probe. The amplitude of the
generated ultrasonic waves before and after passing through the obtained 2 mm thick silicone
resin sheet was measured using an ultrasonic wave receiver (manufactured by Matsushita
Electric Industrial Co., Ltd., an oscilloscope, trade name "VP-5204A"). Thus, the measurement was
made in an environment of water temperature 25 ° C., and the acoustic wave (ultrasonic wave)
attenuation was compared by comparing the acoustic wave (ultrasonic wave) sensitivity. As for
the acoustic wave (ultrasonic wave) sensitivity, the generated acoustic wave (ultrasonic wave)
passes through the sheet with respect to the voltage peak value Vin of the input wave having a
half width of 50 nsec or less by the ultrasonic oscillator, and The voltage value obtained when
the ultrasonic wave generator receives the reflected acoustic wave (ultrasound) is Vs, and the
voltage is calculated according to the following equation.
[0131]
Acoustic wave (ultrasonic) sensitivity = 20 x Log (Vs / Vin)
[0132]
The obtained results are summarized and shown in Table 1 below.
In Table 1 below, the mass average molecular weights of the polyorganosiloxane components (A)
and (B) are simply described as molecular weights, and the type of each component is a trade
name.
[0133]
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[0134]
[0135]
[0136]
[0137]
[0138]
<Notes to Table> [Inorganic Oxide] · HMDS: Means that the inorganic oxide is surface-treated
with HMDS (hexamethyldisilazane).
"None": means that the surface of the inorganic oxide is not treated.
"≧ 30 (Comparative Example 12)" means that the average primary particle diameter was 30 μm
or more.
[Polyorganosiloxane component (A)] · DMS-V42: trade name, vinyl-terminated
polydimethylsiloxane manufactured by Gelest, mass average molecular weight 72,000 · DMSV31: trade name, vinyl-terminated polydimethylsiloxane manufactured by Gelest, mass Average
molecular weight 28,000 DMS-V35: trade name, vinyl-terminated polydimethylsiloxane
manufactured by Gelest, weight average molecular weight 49,500 DMS-V46: trade name, vinylterminated polydimethylsiloxane manufactured by Gelest, mass average molecular weight 117,
000 DMS-V 52: trade name, vinyl-terminated polydimethylsiloxane manufactured by Gelest,
weight average molecular weight 155,000 PDV-0535: trade name, vinyl-terminated
diphenylsiloxane-dimethylsiloxane copolymer manufactured by Gelest, weight average Amount
47,500 PDV-1635: trade name, manufactured by Gelest vinyl-terminated diphenylsiloxanedimethylsiloxane copolymer, weight average molecular weight 35, 300 [polyorganosiloxane
component (B)] HMS-992: trade name, manufactured by Gelest Methylhydrosiloxane polymer,
weight average molecular weight 1,900 [dispersant] · KF-6104: trade name, Shin-Etsu Chemical
polyglyceryl-3 polydimethylsiloxyethyl dimethicone, HLB value 4.5 · KF-6028: trade name,
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Shinetsu PEG-9 polydimethylsiloxyethyl dimethicone manufactured by Kagaku Co., Ltd., HLB
value 4.0 · "-": means not contained in the composition for acoustic probe.
[0139]
As apparent from Table 1, the silicone resin for acoustic wave probe of Examples 1 to 21 has an
acoustic impedance close to that of a living body, and all have an acoustic wave (ultrasonic wave)
sensitivity of -72 dB or more.
Since the sensitivity is -72 dB or more, it can be seen that the acoustic wave attenuation is
reduced.
Furthermore, the silicone resin for acoustic wave probes of Examples 1 to 21 is also excellent in
hardness, tensile elastic modulus, tensile elongation at break and tensile durability. On the other
hand, at least one of the above-mentioned performances is inferior to silicone resin for acoustic
wave probes of comparative examples 1-12.
[0140]
From this result, it is understood that the composition for acoustic wave probe of the present
invention is suitable for a medical member. Further, it is understood that the silicone resin for an
acoustic wave probe of the present invention can be suitably used also for an acoustic lens and /
or an acoustic matching layer of an acoustic wave probe, and an acoustic wave measurement
device and an ultrasonic diagnostic device. In particular, the composition for an acoustic wave
probe and the silicone resin for an acoustic wave probe are used for the purpose of improving
sensitivity in an ultrasonic probe, a photoacoustic wave measuring apparatus and an ultrasonic
endoscope using cMUT as a transducer array for ultrasonic diagnosis. It can be used suitably.
[0141]
1 acoustic lens 2 acoustic matching layer 3 piezoelectric element layer 4 backing material 7
housing 9 code 10 ultrasonic probe (probe)
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