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JP2016046811

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DESCRIPTION JP2016046811
Abstract: A composition for an acoustic wave probe capable of significantly improving the
hardness and mechanical strength of a silicone resin while keeping the amount of acoustic wave
attenuation low, the silicone resin for an acoustic wave probe using the same, and the acoustic
wave probe , An acoustic wave measurement device and an ultrasonic diagnostic device. 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 silica
particles having an average primary particle size of less than 12 nm. It is a composition. The
acoustic matching layer 2 contains 10% by mass or more of a silicone resin for acoustic wave
probe, which is obtained by curing reaction of the composition for acoustic wave probe. The
composition for acoustic wave probe is also used as a material of the acoustic lens 1. [Selected
figure] Figure 1
Composition for acoustic wave probe, silicone resin for acoustic wave probe using the same,
acoustic wave probe and ultrasonic probe, acoustic wave measurement device, ultrasonic
diagnostic device, photoacoustic wave measurement device, and ultrasonic endoscope
[0001]
The present invention relates to a composition for an acoustic wave probe and a silicone resin for
an acoustic wave probe using the same, 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.
04-05-2019
1
[0002]
In an acoustic wave measuring apparatus, an acoustic wave probe is used which irradiates an
acoustic wave to an object or a part (hereinafter simply referred to as an object), receives a
reflected wave (echo), and outputs a signal. The electric signal converted from the reflected wave
received by the acoustic wave probe is displayed as an image. Thereby, the inside of the object is
visualized and observed.
[0003]
As the acoustic wave, an appropriate frequency is selected according to an object to be examined,
measurement conditions, and the like, such as an ultrasonic wave and a photoacoustic wave. 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 measuring apparatus receives an acoustic wave emitted
from the inside of the subject by the photoacoustic effect and displays it as an image. The
photoacoustic effect is an acoustic wave (typical) when the subject 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. ) Is a
phenomenon that occurs. Since the acoustic wave measuring apparatus transmits and receives
acoustic waves to and from a living body to be examined, it is required to satisfy requirements
such as matching of acoustic impedance with the living body and reduction of acoustic wave
attenuation.
[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
and receives ultrasonic waves, and an acoustic lens that is a portion in contact with a living body.
The ultrasonic wave oscillated from the piezoelectric element passes through the acoustic lens
and is incident on 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 wave is reflected on the living body surface, so the ultrasonic wave is not efficiently
incident in the living body and high resolution is obtained. Is difficult. In addition, in order to
transmit and receive ultrasonic waves with high sensitivity, it is desirable that the amount of
04-05-2019
2
ultrasonic attenuation of the acoustic lens be small. For this reason, as one of the materials of the
acoustic lens, silicone resin having a small amount of ultrasonic attenuation is close to the
acoustic impedance of a living body (1.4 to 1.7 × 10 6 kg / m 2 / sec). Mainly used.
[0005]
For example, in Patent Document 1 etc., it is proposed that a silicone based rubber
(organopolysiloxane), a butadiene based rubber or the like be a main component and an
inorganic filler such as silica be blended as a composition for an acoustic lens. Further, since the
acoustic lens is used in contact with the subject, the acoustic lens is required to have mechanical
strength that can withstand long-term use. Therefore, in Patent Document 2, as a composition for
an acoustic lens satisfying acoustic lens characteristics (acoustic impedance, ultrasonic
attenuation amount, mechanical strength, etc.), a composition containing a powder such as
silicone rubber, ytterbium oxide and silica particles is proposed. It is done.
[0006]
JP, 2010-213983, A JP, 2009-072605, A
[0007]
Silicone resins are soft alone and have low mechanical strength.
Therefore, for the purpose of improving hardness and mechanical strength, while increasing the
molecular weight of the vinyl silicone resin at both ends, inorganic filler such as silica (also
referred to as inorganic filler) or vinyl group-containing resin (also referred to as reinforcing
agent) The formulation of) is being carried out. However, in order to achieve the required
mechanical strength, the addition amount of the inorganic filler and the vinyl group-containing
resin to the silicone resin inevitably increases, and conversely, the silicone resin becomes large in
acoustic wave attenuation. was there. Therefore, it has been difficult for conventional silicone
resins to satisfy all of high resin hardness and mechanical strength and reduction of acoustic
wave attenuation at high levels. Therefore, in the present invention, in view of the abovementioned circumstances, a composition for an acoustic wave probe which can greatly improve
the hardness and mechanical strength of a silicone resin while keeping the acoustic wave
attenuation amount low, and an acoustic wave using the same It is an object of the present
invention to provide a silicone resin for probe, an acoustic wave probe, an acoustic wave
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measurement apparatus and an ultrasonic diagnostic apparatus.
[0008]
Another object of the present invention is to provide an ultrasonic probe which can use
capacitive micromachined ultrasonic transducers (cMUT: Capacitive Micromachined Ultrasonic
Transducers) having insufficient sensitivity as a transducer array for ultrasonic diagnosis.
Further, a composition for an acoustic wave probe capable of improving the sensitivity in a
photoacoustic wave measurement apparatus in which the sensitivity is low because the amount
of ultrasonic waves generated by the photoacoustic wave is small and observation of the deep
part of the human body is difficult. And providing a silicone resin for an acoustic wave probe. In
addition to this, it is possible to improve the sensitivity in an ultrasonic endoscope in which the
sensitivity is low because the signal line cable is longer than that for body surface, and it is
difficult to improve the sensitivity in terms of structure, physical characteristics, and process
suitability. It is an object of the present invention to provide a possible composition for an
acoustic wave probe and a silicone resin for an acoustic wave probe.
[0009]
As a result of examining the silicone resin composition for the composition for acoustic wave
probes, the present inventors have found that silica particles having a specific average primary
particle diameter in the composition for acoustic wave probes (hereinafter, also simply referred
to as silica) It has been found that the above-mentioned problems can be solved by containing
the above, and the present invention has been made based on this finding.
[0010]
The above problems are solved by the following means.
<1> Composition for Acoustic Wave Probe Containing Polysiloxane Mixture Having Vinyl Group,
Polysiloxane Having Two or More Si-H Groups in Molecular Chain, and Polysiloxane Mixture
Including Silica Particles having an Average Primary Particle Size of Less than 12 nm object. The
composition for acoustic wave probes as described in <1> which contains 0.1-30 mass parts of
silica particles whose average primary particle diameter is less than 12 nm in a total of 100 mass
parts of a <2> polysiloxane mixture. 10 to 99.4 parts by mass of a polysiloxane having a vinyl
group and 0.5 to 0.5 part of a polysiloxane having two or more Si-H groups in a molecular chain
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in 100 parts by mass of a total of the <3> polysiloxane mixture The composition for acoustic
wave probes as described in <1> or <2> which contains 90 mass parts. The composition for
acoustic wave probes as described in any one of <1>-<3> by which the silica particle whose <4>
average primary particle diameter is less than 12 nm is surface-treated by the silane compound.
The composition for acoustic wave probes as described in any one of <1>-<4> by which the silica
particle whose <5> average primary particle diameter is less than 12 nm is surface-treated by the
trimethylsilylation agent. The composition for acoustic wave probes as described in any one of
<1>-<5> in which the polysiloxane which has a <6> vinyl group has a phenyl group. The
composition for acoustic wave probes as described in any one of <1>-<6> whose mass mean
molecular weights of the polysiloxane which has a <7> vinyl group are 10,000-200,000. The
composition for acoustic wave probes as described in any one of <1>-<7> whose mass mean
molecular weights of the polysiloxane which has a <8> vinyl group are 30,000-150,000. The
composition for acoustic wave probes as described in any one of <1>-<8> in which the
polysiloxane which has a 2 or more Si-H group in a <9> molecular chain has a phenyl group. The
composition for an acoustic wave probe according to any one of <1> to <9>, containing 0.00001
to 0.01 parts by mass of platinum or a platinum compound with respect to 100 parts by mass of
the <10> polysiloxane mixture. object. The silicone resin for acoustic wave probes which
hardened the composition for acoustic wave probes as described in any one of <11> <1>-<10>.
The acoustic wave probe which has an acoustic lens which consists of silicone resin for acoustic
wave probes as described in <12> <11>, and at least 1 selected from the group which consists of
an acoustic matching layer. An ultrasonic probe comprising: a capacitive micromachined
ultrasonic transducer as an <13> ultrasonic transducer array; and an acoustic lens comprising
the silicone resin for an acoustic wave probe according to <11>.
The acoustic wave measuring apparatus provided with the acoustic wave probe as described in
<14> <12>. <15> An ultrasound diagnostic apparatus comprising the acoustic wave probe
according to <12>. The photoacoustic wave measuring apparatus provided with the acoustic lens
which comprises the silicone resin for acoustic wave probes as described in <16> <11>. <17> An
ultrasound endoscope comprising an acoustic lens comprising the silicone resin for an acoustic
wave probe according to <11>.
[0011]
In the description of the present invention, unless otherwise noted, when a plurality of groups
with the same symbol are present in the general formula representing a compound, these may be
the same or different from each other, and the group specified by each group (For example, an
alkyl group) may further have a substituent. Moreover, "Si-H group" means a group having three
bonding hands on a silicon atom, but the description of the bonding hand is omitted and the
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notation is simplified. 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.
[0012]
According to the present invention, a composition for an acoustic wave probe capable of greatly
improving the hardness and mechanical strength of a silicone resin while maintaining low
attenuation of acoustic wave (particularly preferably ultrasonic wave), and acoustic wave using
the same It is possible to provide a silicone resin for probe, an acoustic wave probe, an acoustic
wave measurement device and an ultrasonic diagnostic device. In addition, it is possible to
provide an ultrasonic probe using cMUT as a transducer array for ultrasonic diagnosis, a
photoacoustic wave measuring apparatus, and a silicone resin for an acoustic wave probe
capable of improving the sensitivity in an ultrasonic endoscope.
[0013]
Such an effect is considered to be due to the fact that silica particles having a small average
primary particle diameter in a specific range function as a stopper for micro cracks generated
when mechanical stress is applied to the silicone resin for an acoustic wave probe. In particular,
since the distance between particles is reduced due to the small average primary particle
diameter, it is considered that the function as a stopper is more exhibited and the tear strength of
the silicone resin is significantly improved. As a result, it is considered that the increase in the
amount of acoustic wave attenuation is suppressed, and the hardness and mechanical strength of
the silicone resin for an acoustic wave probe are improved.
[0014]
It is a perspective transmission figure about an example of a convex type ultrasonic probe which
is one mode of an acoustic wave probe.
[0015]
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<< Composition for Acoustic Wave Probe >> The composition for acoustic wave probe of the
present invention (hereinafter, also simply referred to as a composition).
) Is 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 silica particles having an average primary particle size of less than 12 nm. It is
a composition.
[0016]
The content of silica particles having an average primary particle diameter of less than 12 nm in
a total of 100 parts by mass of the polysiloxane mixture is preferably 0.1 to 30 parts by mass,
more preferably 1 to 25 parts by mass, and 5 to 20 parts by mass Is more preferred. In addition,
the content of the vinyl group-containing polysiloxane in the total 100 parts by mass of the
polysiloxane mixture is preferably 10 to 99.4 parts by mass, and the polysiloxane having two or
more Si-H groups in the molecular chain The content is preferably 0.5 to 90 parts by mass. The
content of the vinyl group-containing polysiloxane is more preferably 50 to 90 parts by mass,
and the content of the polysiloxane having two or more Si-H groups in the molecular chain is
more preferably 1 to 50 parts by mass. preferable. In addition, a polysiloxane mixture is a
mixture which does not contain the catalyst which carries out the cross-linking polymerization
(hardening) of the polysiloxane which has a vinyl group, and the polysiloxane which has two or
more Si-H groups in a molecular chain. Thus, the polysiloxane mixture contains silica particles
having an average primary particle size of less than 12 nm, but no catalyst. Moreover, the total of
100 parts by mass of the polysiloxane mixture means that the total of the individual components
contained in the polysiloxane mixture is 100 parts by mass.
[0017]
Each of the above-mentioned polysiloxanes contained in the polysiloxane mixture may be any
polysiloxane as long as it has two or more Si-H groups in a vinyl group or a molecular chain.
However, 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 preferable.
Therefore, in the present invention, a polyorganosiloxane having vinyl groups (A), a
polyorganosiloxane having two or more Si-H groups in the molecular chain (B) and an average
primary particle diameter in the polyorganosiloxane mixture A composition containing at least
silica particles (C) of less than 12 nm as a component is preferred. In the following detailed
04-05-2019
7
description, the polysiloxane mixture contains a polyorganosiloxane (A) having a vinyl group and
a polyorganosiloxane (B) having two or more Si-H groups in the molecular chain, which is a
preferred embodiment. Describe what you are doing. However, each polysiloxane contained in
the polysiloxane mixture is not limited to the polysiloxanes (A) and (B).
[0018]
<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.
[0019]
The polyorganosiloxane (A) having a vinyl group is hydrosilylated, for example, 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 reaction) forms a crosslinked (cured) structure.
[0020]
The content of the vinyl group in the polyorganosiloxane (A) is not particularly limited. From the
viewpoint of forming a sufficient network with each component contained in the acoustic wave
probe composition, for example, the content of the vinyl group is preferably 0.01 to 5 mol%, and
preferably 0.05 to 2 mol. % Is more preferable. Here, the content of the vinyl group is the mol%
of the vinyl group-containing siloxane unit when the total unit constituting the
polyorganosiloxane (A) is 100 mol%. For example, in the case where the Si̶O units constituting
the main chain and all the Si atoms of the terminal Si have one vinyl group, this is 100 mol%.
04-05-2019
8
[0021]
Moreover, it is preferable that polyorganosiloxane (A) has a phenyl group, and content of the
phenyl group of polyorganosiloxane (A) is not specifically limited. From a viewpoint of
mechanical strength when it is set as silicone resin for acoustic wave probes, it is 1-80 mol%, for
example, preferably 2-40 mol%. Here, content of a phenyl group is mol% of a phenyl group
containing siloxane unit when all units which comprise polyorganosiloxane (A) are 100 mol%.
For example, in the case where the Si̶O units constituting the main chain and all the Si atoms of
the terminal Si have one phenyl group each, it is 100 mol%. In addition, a unit means Si-O unit
which comprises a principal chain, and Si of the terminal.
[0022]
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).
200-3000 are preferable, 400-2000 are more preferable, and, as for a specific gravity, 0.9-1.1
are preferable from the point of an improvement of the mechanical characteristics of the above,
hardness, chemical stability, etc.
[0023]
The mass average molecular weight of the polyorganosiloxane having a vinyl group is preferably
10,000 to 200,000, more preferably 30,000 to 150,000, in view of mechanical strength,
hardness, and ease of processing. More preferably, 000 to 120,000. For example, GPC apparatus
HLC-8220 (manufactured by Tosoh Corp.) is used as mass average molecular weight, and toluene
(manufactured by Shonan Wako Pure Chemical Industries, Ltd.) is used as an eluent, and TSKgel
(registered trademark) G3000HXL + TSKgel (registered trademark) as a column. It can measure
using RI detector using G2000HXL, the temperature of 23 degreeC, and the conditions of flow
volume 1mL / min.
[0024]
The kinematic viscosity at 25 ° C. is preferably 1 × 10 <−5> to 10 m <2> / s, more preferably
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9
1 × 10 <−4> to 1 m <2> / s, 1 × 10 <−3> It is further preferable that ∼0.5 m <2> / s. The
kinematic viscosity can be determined by measurement at a temperature of 25 ° C. using a
Ubbelohde viscometer (for example, product name SU manufactured by Shibata Kagaku Co., Ltd.)
according to JIS Z8803.
[0025]
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).
[0026]
<img class = "EMIRef" id = "352462511-00003" />
[0027]
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 further have a substituent.
[0028]
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 ndecyl.
[0029]
04-05-2019
10
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 6membered ring, more preferably a 5- or 6-membered ring. Examples of the cycloalkyl group
include cyclopropyl, cyclopentyl and cyclohexyl.
[0030]
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.
[0031]
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.
[0032]
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.
[0033]
R <a2> and R <a3> each is 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 a methyl group, a vinyl group or a phenyl group preferable. Among them, a methyl group
is preferable as R <a2>, and a phenyl group is preferable as R <a3>. Moreover, it is preferable
that both R <a3> in repetition of x1 is a phenyl group.
04-05-2019
11
[0034]
The integer of 1-3000 is preferable and, as for x1, the integer of 5-1000 is more preferable. The
integer of 1-3000 is preferable and, as for x2, the integer of 40-1000 is more preferable.
[0035]
For example, all polyorganosiloxanes having a vinyl group at both molecular chain terminals are
DMS series (for example, DMS-V31, DMS-V31S15, DMS-V33, DMS-V35, DMS- under the trade
name of Gelest, Inc.). V35R, DMS-V41, DMS-V42, DMS-V46, DMS-V51, DMS-V52), PDV series (for
example, PDV-0341, PDV-0346, PDV-0535, PDV-0541, PDV-1631, PDV- 1635, PDV-1641, PDV2335), 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.
[0036]
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.
[0037]
<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).
) 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 the polyorganosiloxane having at least two vinyl
groups.
[0038]
The polyorganosiloxane (B) has a linear structure and a branched structure, and is preferably a
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12
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.
[0039]
Moreover, it is also preferable that polyorganosiloxane (B) has a phenyl group, and content of a
phenyl group is not specifically limited. From the viewpoint of mechanical strength when it is
used as a silicone resin for an acoustic wave probe, for example, it is 20 to 80 mol%, preferably
30 to 70 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).
[0040]
1,300 g / mol or less is preferable and, as for Si-H equivalent of polyorganosiloxane (B), 500 g /
mol or less is more preferable. Moreover, 50 g / mol or more is preferable and, as for this Si-H
equivalent, 100 g / mol or more is more preferable.
[0041]
In the present invention, it is preferable that both of the polyorganosiloxanes (A) and (B) have a
phenyl group in order to improve the mutual compatibility. The silicone resin for a silicone
acoustic wave probe of the present invention can increase the speed of sound and increase the
hardness and specific gravity by having a bulky phenyl group. Therefore, the acoustic impedance
can be increased.
[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]
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13
<img class = "EMIRef" id = "352462511-00004" />
[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 <b6>) 2 (R <b5>) Represents.
R <b5> and R <b6> each independently represent a hydrogen atom, an alkyl group, a cycloalkyl
group or an aryl group.
R <b3> and R <b4> each independently represent a hydrogen atom, an alkyl group, a cycloalkyl
group, an alkenyl group, an aryl group or -O-Si (R <b8>) 2 (R <b7>). R <b7> and R <b8> 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, a plurality of R <b1>, a plurality of R <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 And a plurality of R
<b8> may be the same as or different from each other, and each group of R <b1> to R <b8> may
be further substituted with a substituent. However, it has two or more Si-H groups in the
molecular chain.
[0045]
The alkyl group and cycloalkyl group in R <b1> and R <b2> are synonymous with the alkyl group
and cycloalkyl group in R <a2> and R <a3>, and their preferred ranges are also the same. The
alkyl group, cycloalkyl group and alkenyl group in R <b3> and R <b4> are the same as the alkyl
group, cycloalkyl group and alkenyl group in R <a2> and R <a3>, and the preferred range is also
the same. is there. 6-12 are preferable, as for carbon number of the aryl group in R <b1> -R <b4>,
6-10 are more preferable, and 6-8 are more preferable. Examples of the aryl group include
phenyl group, tolyl group and naphthyl group.
[0046]
The alkyl group, cycloalkyl group and aryl group in R <b5> and R <b6> of -O-Si (R <b6>) 2 (R
<b5>) 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.
04-05-2019
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[0047]
The alkyl group, cycloalkyl group, alkenyl group and aryl group in R <b7> and R <b8> of -O-Si (R
<b8>) 2 (R <b7>) are R <b3> and R <b4 It is synonymous with the alkyl group in>, 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
<b6>) 2 (R <b5>), 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.
R <b3> and R <b4> each is preferably a hydrogen atom, an alkyl group, an alkenyl group, an aryl
group or -O-Si (R <b8>) 2 (R <b7>), and a hydrogen atom having 1 to 4 carbon atoms Alkyl
group, a vinyl group, a phenyl group or -O-Si (CH3) 2H is more preferable.
[0049]
Among them, R <b1> and R <b2> are preferably a hydrogen atom, an alkyl group or an aryl
group, more preferably a hydrogen atom or an alkyl group, and still more preferably a hydrogen
atom or a methyl group.
Further, a combination of R <b1> with a hydrogen atom and R <b2> with a methyl group is
preferable. R <b3> is preferably a hydrogen atom, an alkyl group, an alkenyl group, an aryl group
or -O-Si (R <b8>) 2 (R <b7>), more preferably a hydrogen atom or an alkyl group, and a hydrogen
atom Particularly preferred.
[0050]
R <b4> is preferably a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or -O-Si (R
<b8>) 2 (R <b7>), more preferably a hydrogen atom, an alkyl group or an aryl group, A hydrogen
atom, a methyl group or a phenyl group is more preferable, a methyl group or a phenyl group is
more preferable, and a phenyl group is particularly preferable.
04-05-2019
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[0051]
y1 is preferably an integer of 1 or more.
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.
[0052]
As a combination of R <b1> to R <b3>, R <b1> is 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 is preferred, and R <b1> is a C1-C4 alkyl group, R <b2> is a C1-C4 alkyl
group, and R <b3> is a combination of hydrogen atoms.
[0053]
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%) and
HMS-501 (MeHSiO: 50-55 mol%), HMS-991 (Si) which is a methylhydrosiloxane polymer
(trimethylsiloxy terminated) -H equivalent 67 g / mol) and HPM-502 (Si-H equivalent 165 g /
mol) (all trade names) which are methylhydrosiloxane-phenylmethyl siloxane copolymer
(hydrogen terminated).
Here, mol% of MeHSiO is synonymous with what multiplied 100 by y2 / (y1 + y2) in the
preferable combination of said R <b1> -R <b3>.
[0054]
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.
[0055]
04-05-2019
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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).
[0056]
Average composition formula (b): [Ha (R <b6>) 3-a SiO 1/2] y3 [SiO 4/2] y4
[0057]
Here, R <b6> 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.
[0058]
The alkyl group, cycloalkyl group, alkenyl group and aryl group for R <b6> 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.
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.
[0059]
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
the following general formula (Bb) are more preferable.
04-05-2019
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[0060]
<img class = "EMIRef" id = "352462511-000005" />
[0061]
In the general formula (Bb), * means to bond to at least the Si atom of siloxane.
[0062]
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) (C6H3Si) O]: 99-100 mol%).
[0063]
The polyorganosiloxane (B) having two or more Si-H groups in the molecular chain used 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.
[0064]
<Silica (C) having an average primary particle size of less than 12 nm> The silica particles (C)
having an average primary particle size of less than 12 nm used in the present invention improve
the hardness and mechanical strength of the obtained silicone resin, particularly tear strength It
is a component added for the purpose of improvement.
[0065]
In the present invention, by reducing the average primary particle diameter of the silica particles
(C) to less than 12 nm, it is possible to suppress an increase in the amount of acoustic wave
attenuation and to improve the tear strength of the silicone resin. I think that the.
04-05-2019
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That is, it is thought that the crack of the silicone resin by mechanical stress is suppressed by the
fine silica particle (C) functioning as a stopper.
In particular, since the distance between 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 tear
strength of the silicone resin is significantly improved.
[0066]
Examples of the silica particles (C) include fumed silica, calcined silica, precipitated silica, and
vinyl group-containing silicone resin.
The silica particles (C) may be used alone or in combination of two or more.
[0067]
The average primary particle diameter of the silica particles (C) in the present invention is less
than 12 nm from the viewpoint of suppressing an increase in the acoustic wave attenuation of
the silicone resin and improving the tear strength, preferably more than 3 nm and less than 12
nm, 3 nm More than 10 nm is more preferable.
The average primary particle size is described in the catalog of the manufacturer of silica
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 given to a silica particle (C), the average primary
particle diameter in the state by which surface treatment was carried out is meant.
[0068]
The silica particles (C) used in the present invention preferably have a specific surface area of 50
04-05-2019
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to 400 m <2> / g, and 100 to 400 m <2> / g, from the viewpoint of improving the hardness and
mechanical strength of the obtained silicone resin. More preferable.
[0069]
The silica particles (C) used in the present invention are preferably silica particles whose surface
has been surface-treated.
As surface treatment, silica particles treated with saturated fatty acid or silane are preferable, and
among them, silica particles treated with silane are preferable.
[0070]
In the silane treatment, it is preferable to treat the surface of the silica particles with a silane
coupling agent. Among them, silane coupling agents having a hydrolyzable group are preferable
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 reacts with the hydroxyl group on the surface of the silica particle
by dehydration condensation reaction, thereby surface modification of the silica particle is
performed, and a silicone resin is obtained. Hardness and mechanical strength 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 silica particles is surface-modified to be hydrophobic,
the affinity between the silica particles (C) and the polyorganosiloxanes (A) and (B) becomes
good, and the hardness and the machine of the obtained silicone resin are obtained. It is
preferable because the strength is improved.
[0071]
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 (DDS),
trimethylchlorosilane, phenyltrichlorosilane, etc. Chlorosilane; hexamethyldisilazane (HMDS).
04-05-2019
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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 silica particle (C) used in the present invention is preferably a silica particle whose surface is
treated with a silane compound, more preferably a silica particle treated with a trialkylsilylating
agent, and a silica particle treated with a trimethylsilylating agent More preferable. 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. Moreover, as the trialkylsilylating agent, for example, trimethylchlorosilane,
hexamethyldisilazane (HMDS) described in the above-mentioned silane coupling agent,
trimethylmethoxysilane which is a silane coupling agent in which a functional group is
substituted by an alkyl group Can be mentioned.
[0073]
Examples of commercially available silane coupling agents include hexamethyldisilazane (HMDS)
(trade name: HEXAMETHYLDISILAZANE (SIH 611 0.1), manufactured by Gelest). The silanol
group (Si-OH group) present on the surface of the silica particle is covered with a trimethylsilyl
group by the reaction with hexamethyldisilazane (HMDS), and the surface of the silica particle is
modified to be hydrophobic.
[0074]
Commercially available silica particles (C) include, for example, Aerosil (registered trademark) R
812 (average primary particle diameter 7 nm, HMDS surface treatment) and Aerosil (registered
trademark), all of which are hydrophobic fumed silica manufactured by Nippon Aerosil Co., Ltd. )
R812S (average primary particle diameter 7 nm, HMDS surface treatment), Aerosil (registered
trademark) RX300 (average primary particle diameter 7 nm, HMDS surface treatment), Aerosil
(registered trademark) RX 380 S (average primary particle diameter 5 nm, HMDS surface
treatment), Aerosil (registered trademark) R976S (average primary particle diameter 7 nm, DDS
surface treatment) or hydrophilic fumed silica manufactured by Nippon Aerosil Co., Ltd., Aerosil
04-05-2019
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(registered trademark) 300 (average primary particle diameter 7 nm), Aerosil (Registered
trademark) 300 CF (average primary particle diameter 7 nm), Aero Le (R) 380 (average primary
particle diameter 7 nm) can be mentioned.
[0075]
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 silica
particles (C) is small and the gaps between the polyorganosiloxanes (A) and (B) are closely
packed, the polyorganosiloxanes (A) and (B) Movement of the molecular chain 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.
[0076]
<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 average primary In addition to silica particles (C)
having a particle size of less than 12 nm, platinum catalysts for addition polymerization reaction,
curing retarder, solvent, dispersant, pigment, dye, antistatic agent, antioxidant, flame retardant,
thermal conductivity An enhancer etc. can be mix | blended suitably.
[0077]
-Catalyst-As a catalyst, for example, platinum or a platinum-containing compound (hereinafter,
also referred to as a platinum compound).
Can be mentioned. Any platinum or platinum compound can be used. Specifically, platinum black,
platinum supported on silica, carbon black or the like, chloroplatinic acid or alcohol solution of
chloroplatinic acid, complex salt of chloroplatinic acid and olefin, complex salt of chloroplatinic
acid and vinylsiloxane, etc. Can be mentioned. The catalyst may be used alone or in combination
of two or more.
04-05-2019
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[0078]
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.
[0079]
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).
[0080]
When the catalyst is contained in the composition for an acoustic wave probe of the present
invention, the content of the catalyst is preferably 0.00001 to 0.05 parts by mass with respect to
100 parts by mass of the polysiloxane mixture from the viewpoint of reactivity. .0000 to 0.01
parts by mass is more preferable, 0.00002 to 0.01 parts by mass is further preferable, and
0.00005 to 0.005 parts by mass is particularly preferable.
[0081]
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.
[0082]
04-05-2019
23
-Curing Retarder-In the present invention, a curing retarder for the curing reaction can be
suitably used.
The curing retarder is used for the purpose of delaying a platinum-catalyzed addition curing
reaction, and examples thereof include low molecular weight vinylmethylsiloxane homopolymer
(trade name: VMS-005, manufactured by Gelest). The curing rate, ie, the working time can be
adjusted by the content of the curing retarder.
[0083]
<Composition for Acoustic Wave Probe and Method for Producing Silicone Resin for Acoustic
Wave Probe> The composition for acoustic wave probe of the present invention can be prepared
by a known method. For example, the component which comprises the composition for acoustic
wave probes can be obtained by knead | mixing with the kneader, a pressure kneader, a Banbury
mixer (continuous kneader), and the kneading | mixing apparatus of 2 rolls. The order of mixing
of the components is not particularly limited. From the viewpoint of obtaining a uniform
composition, first, the average primary particle diameter of the polyorganosiloxane (A) having a
vinyl group and the polyorganosiloxane (B) having two or more Si-H groups in the molecular
chain It is preferable to set it as the polyorganosiloxane mixture which disperse | distributed the
silica particle (C) below 12 nm. Thereafter, a catalyst is added to the polyorganosiloxane mixture
in which the silica particles (C) are dispersed, and the composition for an acoustic wave probe
can be produced by degassing under reduced pressure.
[0084]
By curing the composition for acoustic wave probe of the present invention thus obtained, the
silicone resin for acoustic wave probe of the present invention can be obtained. Specifically, for
example, a silicone resin for an acoustic wave probe can be obtained by heat curing at 20 to 200
° C. for 5 to 500 minutes.
[0085]
<Mechanical Strength and Acoustic Wave Properties of Silicone Resin> The mechanical strength
04-05-2019
24
and acoustic wave properties of the silicone resin are 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. [Hardness] With respect to a silicone
resin sheet having a thickness of 2 mm, in accordance with JIS K6253-3 (2012), the type A
durometer hardness is measured using a rubber hardness tester (for example, a trade name "RH201A" manufactured by Excell Co.) . The hardness is preferably 20 or more, and more preferably
30 or more. Note that the practical upper limit is 80 or less. By being in the said range, since the
deformation | transformation at the time of incorporating and using it as a part of acoustic wave
probe can be prevented, it is preferable.
[0086]
[Tension test] The breaking strength and the elongation (elongation) of a silicone resin sheet
having a thickness of 1 mm are measured according to JIS K6251. The tensile breaking strength
is preferably 2.0 MPa or more, and the tensile breaking elongation is preferably 300% or more.
In addition, a realistic upper limit is 10 MPa or less in tensile strength at break, and 1500% or
less in tensile strength at break.
[0087]
[Tear Strength Test] A 2 mm-thick silicone resin sheet was prepared according to JIS K6252
(2007) to prepare a trouser-type test piece, and the tear strength was measured. The tear
strength is preferably 20 N / cm or more, and more preferably 30 N / cm or more. In addition, a
realistic upper limit is 100 N / cm or less.
[0088]
[Williams abrasion test] With respect to a silicone resin sheet of 20 mm long × 20 mm wide ×
10 mm thick, the weight before and after the test is measured according to JIS K 6264-2 using a
Williams abrasion tester. The mass loss (%) calculated from the following equation is evaluated as
the amount of wear of the Williams [%].
04-05-2019
25
[0089]
(Mass of silicone resin sheet before test-Mass of silicone resin sheet after test) / Mass of silicone
resin sheet before test x 100
[0090]
1% or less is preferable, 0.7% or less is more preferable, 0.5% or less is more preferable, and the
smaller the value is, the more preferable.
[0091]
[Acoustic impedance] With respect to a silicone resin sheet having a thickness of 2 mm, an
electronic densitometer (for example, Alpha Mirage Co., Ltd.) according to the density
measurement method of Method A (substitution method in water) described in JIS K7112
(1999). Manufactured by a trade name "SD-200L").
The sound velocity of the acoustic wave was measured and measured at 25 ° C. using a singlearound sound velocity measuring apparatus (for example, manufactured by Ultrasonic Industry
Co., Ltd., trade name “UVM-2”) in accordance with JIS Z 2353 (2003). The acoustic impedance
is determined from the product of density and sound velocity.
[0092]
[Acoustic wave (ultrasonic wave) attenuation, sensitivity] 5 MHz sine wave signal (one wave)
output from an ultrasonic oscillator (for example, function generator, product name "FG-350"
manufactured by Iwatsu Measurement Co., Ltd.) Is input to an ultrasonic probe (for example,
manufactured by Japan Probe Co., Ltd.), and an ultrasonic pulse wave having a center frequency
of 5 MHz is generated in water from the ultrasonic probe.
The amplitude of the generated ultrasonic waves before and after passing through a 2 mm thick
silicone resin sheet was measured by an ultrasonic receiver (for example, an oscilloscope
manufactured by Matsushita Electric Industrial Co., Ltd., trade name "VP-5204A"). Measure the
acoustic wave (ultrasonic) attenuation of each sheet by measuring in an environment of water
temperature 25 ° C. and comparing the acoustic wave (ultrasonic) sensitivity. The acoustic wave
(ultrasound) sensitivity is a numerical value given by the following formula. In the following
04-05-2019
26
formula, Vin represents a voltage peak value of an input wave having a half width of 50 nsec or
less by the ultrasonic oscillator. Vs represents a voltage value obtained when the generated
acoustic wave (ultrasonic wave) passes through the sheet and the ultrasonic wave receives the
acoustic wave (ultrasound) reflected from the opposite side of the sheet.
[0093]
Acoustic wave (ultrasonic) sensitivity = 20 x Log (Vs / Vin)
[0094]
In the evaluation system of the present invention, the acoustic wave (ultrasound) sensitivity is
preferably -72 dB or more, and more preferably -71 dB or more.
[0095]
The composition for an acoustic wave probe of the present invention is useful for a medical
member, and can be preferably used, for example, in an acoustic wave probe or an acoustic wave
measurement device.
The acoustic wave measuring apparatus according to the present invention is not limited to an
ultrasonic diagnostic apparatus or a photoacoustic wave measuring apparatus, and refers to an
apparatus that receives an acoustic wave reflected or generated by an object and displays it as an
image or a signal intensity.
In particular, the composition for acoustic wave probe according to the present invention is
provided between the acoustic lens of the ultrasonic diagnostic apparatus or between the
piezoelectric element and the acoustic lens to have the role of matching the acoustic impedance
between the piezoelectric element and the acoustic lens. Acoustic matching layer material,
photoacoustic wave measuring device and acoustic lens material in ultrasound endoscope and
acoustic probe in ultrasound probe with Capacitive Micromachined Ultrasonic Transducers
(cMUT) as ultrasound transducer array It can be suitably used as a material of a lens or the like.
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-2003169802, or the like, JP-A-2013-202050 , Preferably applied to an acoustic wave measuring
apparatus such as a photoacoustic wave measuring apparatus described in Japanese Patent
Application Laid-Open Nos. 2013-188465, 2013-180330, 2013-158435, 2013-154139 etc. Be
04-05-2019
27
done.
[0096]
<< 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. 1 below. 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
as it is.
[0097]
-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. The configuration of the ultrasonic probe 10 is, as shown in FIG. 1, 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 in contact with a living body being a subject)
There is. 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.
[0098]
<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 expansion and contraction.
, Ultrasonic waves are generated.
[0099]
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.
04-05-2019
28
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.
[0100]
<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. .
[0101]
<Acoustic Matching Layer> The acoustic matching layer 2 is provided to reduce the difference in
acoustic impedance between the piezoelectric element layer 3 and the subject and efficiently
transmit and receive ultrasonic waves.
The composition for an ultrasonic 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 composition of the acoustic matching layer It can be preferably used as a material.
The acoustic matching layer of the present invention preferably contains 10% by mass or more
of a silicone resin for an acoustic wave probe obtained by curing reaction of the composition for
an acoustic wave probe of the present invention.
[0102]
<Acoustic Lens> The acoustic lens 1 is provided for focusing ultrasonic waves in the slice
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29
direction using refraction to improve resolution. And intimately contacting the living body as the
subject, and matching the ultrasonic wave with the acoustic impedance of the living body (in the
human body, 1.4 to 1.7 × 10 6 <6> kg / m 2> · sec); It is required that the ultrasonic attenuation
amount of the acoustic lens 1 itself is small. That is, as the material of the acoustic lens 1,
ultrasonic waves are transmitted / received by using a material whose sound velocity is
sufficiently smaller than the sound velocity of the human body and attenuation of ultrasonic
waves is small, and whose acoustic impedance is close to the value of human skin. The sensitivity
is improved. The composition for acoustic wave probes which is a composition for ultrasonic
probes of the present invention can be preferably used also as an acoustic lens material.
[0103]
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 subject. At the time of reception, the piezoelectric element layer 3 is vibrated
by a reflection signal (echo signal) from the subject, and the vibration is electrically converted
into a signal to obtain an image.
[0104]
In particular, an acoustic lens obtained from the composition for an ultrasonic 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. Hereinafter, an
apparatus in which an acoustic lens obtained from the composition for an ultrasonic probe of the
present invention exerts a function particularly against the conventional problems will be
described in detail. In addition, the composition for ultrasonic probes of this invention shows the
outstanding effect also to apparatuses other than describing below.
[0105]
-Ultrasonic probe provided with cMUT (capacitive micromachine ultrasonic transducer)-When
using the cMUT device described in JP 2006-157320 A, JP 2011-71842 A etc. for a transducer
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30
array for ultrasonic diagnosis, in general In general, its sensitivity is lower than that of a
piezoelectric ceramic (PZT) based transducer. However, by using an acoustic lens obtained from
the composition 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 low-cost ultrasonic probe with higher mass
productivity and lower cost than the piezoelectric ceramic probe.
[0106]
-Photoacoustic wave measuring device by optical ultrasonic imaging-Photoacoustic imaging (PAI:
Photo Acoustic Imaging) described in Japanese Patent Application Laid-Open No. 2013-158435
and the like irradiates light (electromagnetic wave) to the inside of a human body and the
irradiated light 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 an acoustic lens
obtained from the composition for an acoustic wave probe of the present invention, it is possible
to exhibit an effective effect on this problem.
[0107]
-Ultrasonic endoscope-The ultrasonic wave in the ultrasonic endoscope described in Japanese
Patent Application Laid-Open No. 2008-311700, etc., has a long signal line cable compared to
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.
[0108]
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 inserted into the body and used, the installation space of the transducer
is narrow, and it is difficult to install an amplifier circuit, an AD conversion IC, etc. on the tip of
the transducer. Second, the piezoelectric single crystal employed in the transducer in the
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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.
[0109]
However, by using an acoustic lens obtained from the composition for an acoustic wave probe of
the present invention, it is possible to improve the sensitivity of an endoscopic ultrasonic
transducer. In addition, even when using the same ultrasonic transmission frequency (for
example, 10 MHz), the effectiveness is particularly effective when using an acoustic lens obtained
from the composition for an acoustic wave probe of the present invention in an ultrasonic
transducer for endoscopes. It is exhibited.
[0110]
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.
[0111]
[Example 1] 79.6 parts by mass of vinyl-terminated polydimethylsiloxane (manufactured by
Gelest, trade name "DMS-V42", weight average molecular weight 72,000), methylhydrosiloxanedimethylsiloxane copolymer (manufactured by Gelest, trade name) “HMS-301”, mass average
molecular weight 2,000, methyl hydrosiloxane ratio 27 mol%) 2.4 parts by mass, fumed silica
(manufactured by Nippon Aerosil Co., Ltd., trade name “Aerosil RX 300”, average primary
particle diameter 7 nm, hexamethyl) 18 parts by mass of disilazane (HMDS) surface treatment
was kneaded with a kneader for 2 hours to obtain a uniform paste. To this, 500 ppm of platinum
catalyst solution (Gelest, trade name "SIP 6821.3") is added and mixed, then degassed under
reduced pressure, put in a 150 mm x 150 mm metal mold, and heat treated at 60 ° C for 3
hours A silicone resin sheet having a thickness of 1 mm and 2 mm, respectively, was obtained.
04-05-2019
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[0112]
[Examples 2 to 18 and Comparative Examples 1 to 3] A predetermined silicone resin was
prepared in the same manner as in Example 1 except that the composition and composition of
the polysiloxane mixture of Example 1 were changed as shown in Tables 1 and 2 below. I got a
sheet.
[0113]
<Evaluation of mechanical strength and ultrasonic characteristics> The following evaluations
were performed on the silicone resin sheets of Examples 1 to 18 and Comparative Examples 1 to
3.
[0114]
[Hardness] The obtained silicone resin sheet having a thickness of 2 mm was measured using a
rubber hardness tester (trade name “RH-201A” manufactured by Excell Co., Ltd.) according to
JIS K6253-3 (2012) and using a rubber hardness tester (trade name “RH-201A”). did.
[0115]
[Tensile test] The breaking strength and the elongation of the obtained 1 mm-thick silicone resin
sheet were measured according to JIS K6251.
[0116]
[Tear strength test] With respect to the obtained silicone resin sheet having a thickness of 2 mm,
a trousers type test piece was produced according to JIS K6252 (2007), and tear strength was
measured.
[0117]
[Williams Wear Test] In each of Examples 1 to 18 and Comparative Examples 1 to 3, test pieces
of 20 mm × 20 mm × 10 mm were similarly produced.
About the obtained test piece, the mass before and after the test is measured using a Williams
abrasion tester (No. 275) manufactured by Yasuda Seiki Seisakusho in accordance with JIS
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33
K6264-2, and the mass loss (%) is calculated from the following formula did.
In Tables 1 and 2 below, the mass loss was described as the amount of wear of the Williams [%].
[0118]
(Mass of silicone resin sheet before test-Mass of silicone resin sheet after test) / Mass of silicone
resin sheet before test x 100
[0119]
[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 ° C. according to JIS Z 2353 (2003) using a singlearound 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
[0120]
[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"). According to
the above, the acoustic wave (ultrasonic wave) attenuation amount of each sheet was compared
by measuring in an environment with a water temperature of 25 ° C. and comparing the
acoustic wave (ultrasonic wave) sensitivity.
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The acoustic wave (ultrasound) sensitivity is a numerical value given by the following formula.
In the following formula, Vin represents a voltage peak value of an input wave having a half
width of 50 nsec or less by the ultrasonic oscillator. Vs represents a voltage value obtained when
the generated acoustic wave (ultrasonic wave) passes through the sheet and the ultrasonic wave
receives the acoustic wave (ultrasound) reflected from the opposite side of the sheet.
[0121]
Acoustic wave (ultrasonic) sensitivity = 20 x Log (Vs / Vin)
[0122]
The obtained results are summarized and shown in Tables 1 and 2 below.
In Tables 1 and 2 below, mass average molecular weights of the polyorganosiloxanes (A) and (B)
are simply described as molecular weights. Moreover, the kind of each component described the
brand name.
[0123]
[0124]
[0125]
<Note to Table> [Polyorganosiloxane component (A)] DMS (trade name) manufactured by Gelest,
PDV (trade name) series · DMS-V 31: trade name, vinyl-terminated polydimethylsiloxane, weight
average molecular weight 28 DMS-V35: trade name, vinyl-terminated polydimethylsiloxane,
weight average molecular weight 49, 500 DMS-V42: trade name, vinyl-terminated
polydimethylsiloxane, weight average molecular weight 72,000, DMS-V46: trade name, Vinylterminated polydimethylsiloxane, mass-average molecular weight 117,000. DMS-V52: trade
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35
name, vinyl-terminated polydimethylsiloxane, mass-average molecular weight 155,000 PDV0541: trade name, vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymer, mass Average
molecular weight 60,000, Amount of phenyl siloxane: 5 mol% PDV-0535: trade name, vinylterminated diphenylsiloxane-dimethylsiloxane copolymer, weight average molecular weight 47,
500, amount of diphenyl siloxane 5 mol% PDV-1641: trade name, vinyl-terminated diphenyl
siloxane-dimethylsiloxane copolymer Weight average molecular weight 55,000, diphenylsiloxane
content 16 mol% PDV-1635: trade name, vinyl-terminated diphenyl siloxane-dimethylsiloxane
copolymer, weight average molecular weight 35, 300, diphenyl siloxane content 16 mol% PDV1631: trade name, Vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymer, weight
average molecular weight 19,000, diphenylsiloxane content 16 mol% [polyorganosiloxane
component B) All HMS (trade name) and HPM (trade name) series HMS-064 manufactured by
Gelest, Inc .: trade name, methylhydrosiloxane-dimethylsiloxane copolymer, weight average
molecular weight 60,000, methylhydrosiloxane ratio 6 mol% HMS-301: trade name,
methylhydrosiloxane-dimethylsiloxane copolymer, weight average molecular weight 2,000,
methylhydrosiloxane ratio 27 mol% HMS-501: trade name methylhydrosiloxane-dimethylsiloxane
copolymer, weight average molecular weight 1,1, 100, Si-H equivalent 135 g / mol HMS-991:
trade name, methyl hydrosiloxane polymer, weight average molecular weight 1,600, Si-H
equivalent 67 g / mol HPM-502: trade name, methyl hydrosiloxane-phenyl ester Chilsiloxane
copolymer, mass average molecular weight 4,500, Si-H equivalent 165 g / mol [silica particles
(C)] all are fumed silica manufactured by Nippon Aerosil Co., Ltd., Aerosil (trade name) series (in
the above table "Aerosil" Is omitted.
· · Aerosil RX 300: trade name, average primary particle diameter 7 nm, hexamethyldisilazane
(HMDS) surface treatment · Aerosil RX 200: trade name, average primary particle diameter 12
nm, HMDS surface treatment · Aerosil RX 380 S: trade name, average primary particle diameter 5
nm, HMDS surface treatment · Aerosil R976S: trade name, average primary particle diameter 7
nm, dimethyldichlorosilane (DDS) surface treatment · Aerosil 300: trade name, average primary
particle diameter 7 nm, no surface treatment · Aerosil 200: trade name, average Primary particle
diameter 12 nm, no surface treatment Combustion method and dry silica manufactured by Asahi
Kasei Wacker Silicone Co., Ltd., HDK (trade name) series ("HDK" is omitted in the above table).
) · HDK H 20: trade name, average primary particle diameter 10 nm, HMDS surface treatment
[0126]
As shown in Tables 1 and 2, the silicone resins for acoustic wave probes of Examples 1 to 12 all
had resin hardness, tensile strength at break, tear strength while maintaining acoustic wave
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36
(ultrasonic wave) sensitivity of -72 dB or more. And it turned out that it is excellent in abrasion
resistance. Moreover, silicone resin for acoustic wave probes of Examples 13 to 18 in which
silicone has a phenyl group has high acoustic impedance in addition to acoustic wave (ultrasonic
wave) sensitivity, resin hardness, tensile strength at break, tear strength and abrasion resistance.
It turned out to have. In particular, it was found that the silicone resins for acoustic wave probes
of Examples 15 to 18 in which both the polyorganosiloxanes (A) and (B) have a phenyl group
have better acoustic impedance. On the other hand, the silicone resins for acoustic wave probes
of Comparative Examples 1 to 3 did not have sufficient tear strength and wear resistance.
[0127]
From this result, it is understood that the composition for acoustic wave probe of the present
invention is useful for a medical member. The silicone resin of the present invention can also be
suitably used 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.
[0128]
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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