Backing material, ultrasonic probe, ultrasonic diagnostic device, and curable resin composition

Abstract

Provided are a backing material for an ultrasonic probe, an ultrasonic probe, an ultrasonic diagnostic device, and a curable resin composition, the backing material comprising thermally conductive particles and a resin, the resin comprising any one of the following (A)-(C): (A) a reaction cured product of an epoxy resin having a polyurethane structure and a polyamine compound; (B) a reaction cured product of an epoxy resin and a polyamine compound and having a polyether structure; and (C) a reaction cured product of a polyisocyanate compound and a polyamine compound, the loss tangent of the resin in the range of 0-50 DEG C is 0.06 or more, the loss tangent in the range of-20-110 DEG C is less than 1.50, the storage modulus of the backing material in the range of 0-50 DEG C is 1000 MPa or more, and the content of the resin in the backing material is 25-50 vol%.

Description

Technical Field

[0001] The present invention relates to a backing material, an ultrasonic probe, an ultrasonic diagnostic device and a curable resin composition. Background Art

[0002] Ultrasonic measurement devices use an ultrasonic probe that irradiates an object or part under examination (hereinafter referred to as the object), receives reflected waves (echoes), and outputs signals. The electrical signals converted from the reflected waves received by the ultrasonic probe are displayed as images. This allows visualization of the interior of the object under examination.

[0003] During diagnosis, the ultrasonic probe drives the piezoelectric element by, for example, bringing the acoustic lens side of the ultrasonic probe into contact with the subject, thereby sending an ultrasonic signal from the front surface of the piezoelectric element into the subject. The ultrasonic signal is focused to the desired position in the subject by electronic focusing based on the driving timing of the piezoelectric element and focusing based on the acoustic lens. At this time, by controlling the driving timing of the piezoelectric element, the ultrasonic signal can be sent to the desired range in the subject, and by receiving and processing the echo signal from the subject, an ultrasonic image (tomographic image) of the desired range can be obtained. The driving of the piezoelectric element also emits an ultrasonic signal on the back side. Therefore, by configuring a backing material on the back side of the piezoelectric element and using the backing material to absorb (attenuate) the ultrasonic signal to the back side, the adverse effect of sending the normal ultrasonic signal into the subject together with the ultrasonic signal (reflected signal) from the back side is avoided.

[0004] In addition to the above-mentioned high ultrasonic attenuation, the backing material is also required to have all the characteristics such as high heat dissipation that can effectively release the heat released from the piezoelectric element when driving the ultrasonic probe, and processability that can suppress the occurrence of deformation, breakage, etc. while obtaining the backing material of the ultrasonic probe with high productivity.

[0005] Conventionally, there is known a technique for imparting high heat dissipation properties to a backing material by adding a thermally conductive filler.

[0006] For example, Patent Document 1 describes an acoustic backing composition comprising an ethylene-vinyl acetate copolymer containing 20 to 80% by weight of vinyl acetate and a thermally conductive filler. Furthermore, Patent Document 2 describes a material used as a backing material (backing material) for an ultrasonic probe, comprising a main material composed of nitrile rubber, butyl rubber, or polyurethane rubber, and a thermally conductive filler composed of aluminum nitride, silicon carbide, copper, boron nitride, or graphite.

[0007] Previous technical literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-033801

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2000-165995 Summary of the Invention

[0011] Technical issues to be solved by the invention

[0012] As a result of research, the present inventors have discovered that while the acoustic backing composition described in Patent Document 1 can provide an acoustic backing material that exhibits both high heat dissipation and high ultrasonic attenuation, it suffers from insufficient strength due to the softness of the ethylene-vinyl acetate copolymer, making processing difficult and presenting problems in its use as a backing material. Furthermore, the back-supporting material (backing material) described in Patent Document 2 also achieves both high heat dissipation and high ultrasonic attenuation, but is difficult to process due to the softness and difficult-to-process nature of the rubber material, thus still presenting problems in its use as a backing material.

[0013] The present invention aims to provide a backing material that combines excellent ultrasonic attenuation and excellent processability, wherein heat dissipation is enhanced by incorporating thermally conductive particles, and an ultrasonic probe and ultrasonic diagnostic device comprising the backing material. Furthermore, the present invention aims to provide a curable resin composition suitable for forming the backing material.

[0014] Means for solving technical problems

[0015] The above-mentioned problems of the present invention are solved by the following means.

[0016] [1]

[0017] A backing material for an ultrasonic probe comprising thermally conductive particles and a resin.

[0018] The resin includes any one of the following (A) to (C):

[0019] (A) a reaction-cured product of an epoxy resin having a polyurethane structure and a polyamine compound;

[0020] (B) a reaction-cured product of an epoxy resin and a polyamine compound, and a reaction-cured product having a polyether structure; and

[0021] (C) a cured product of a reaction of a polyisocyanate compound and a polyamine compound,

[0022] The resin has a loss tangent of 0.06 or more in the range of 0 to 50°C and a loss tangent of less than 1.50 in the range of -20 to 110°C.

[0023] The storage modulus of the backing material in the range of 0 to 50°C is 1000 MPa or more.

[0024] The content of the resin in the backing material is 25 to 50% by volume.

[0025] [2]

[0026] The backing material according to [1], wherein

[0027] The thermally conductive particles include at least one of metal particles and ceramic particles.

[0028] 〔3〕

[0029] An ultrasonic probe comprising the backing material described in [1] or [2].

[0030] [4]

[0031] An ultrasonic diagnostic device using the ultrasonic probe described in [3].

[0032] 〔5〕

[0033] A curable resin composition for forming the backing material described in [1] or [2],

[0034] The curable resin composition includes the thermally conductive particles and any one of the following (a) to (c) as a resin component:

[0035] (a) a combination of an epoxy resin having a polyurethane structure and a polyamine compound;

[0036] (b) a combination of an epoxy resin and a polyamine compound, wherein at least one of the epoxy resin and the polyamine compound has a polyether structure; and

[0037] (c) a combination of a polyisocyanate compound and a polyamine compound,

[0038] The viscosity of the curable resin composition is 5000 Pa·s or less under the conditions of 25° C. and a shear rate of 0.01 / s.

[0039] In the present invention, a numerical range expressed using “to” means a range including the numerical values ​​described before and after “to” as the lower limit and the upper limit.

[0040] Effects of the Invention

[0041] The backing material of the present invention has heat dissipation properties by incorporating thermally conductive particles, and is excellent in ultrasonic attenuation and processability.

[0042] Furthermore, the ultrasonic probe and ultrasonic diagnostic apparatus of the present invention include a backing material having the above-mentioned properties.

[0043] Furthermore, the curable resin composition of the present invention is suitable for forming the above-mentioned backing material. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a perspective view of an example of a convex ultrasonic probe, which is one form of an ultrasonic probe. DETAILED DESCRIPTION

[0045] 〔Backing material〕

[0046] The backing material of the present invention is a backing material for an ultrasonic probe comprising thermally conductive particles and a resin.

[0047] The resin includes any one of the following (A) to (C):

[0048] (A) a reaction-cured product of an epoxy resin having a polyurethane structure and a polyamine compound;

[0049] (B) a reaction-cured product of an epoxy resin and a polyamine compound, and a reaction-cured product having a polyether structure; and

[0050] (C) a cured product of a reaction of a polyisocyanate compound and a polyamine compound,

[0051] The resin has a loss tangent of 0.06 or more in the range of 0 to 50°C and a loss tangent of less than 1.50 in the range of -20 to 110°C.

[0052] The storage modulus of the backing material in the range of 0 to 50°C is 1000 MPa or more.

[0053] The content of the resin in the backing material is 25 to 50% by volume.

[0054] The reasons why the backing material of the present invention is excellent in ultrasonic attenuation and processability are not clearly understood in detail, but are considered as follows.

[0055] The backing material of the present invention, as a backing material for an ultrasonic probe comprising thermally conductive particles and a resin having specific viscoelastic properties, can exhibit high heat dissipation properties based on the thermally conductive particles, and exhibit excellent ultrasonic attenuation and excellent processability. Specifically, the resin can exhibit excellent ultrasonic attenuation by having a loss tangent of 0.06 or more in the range of 0 to 50°C. It is believed that if an ultrasonic wave is irradiated on a resin having such properties, the energy of the vibration is absorbed by the polymer molecular chains constituting the resin and consumed as its own kinetic energy, and the ultrasonic wave disappears. Furthermore, the resin has a loss tangent of less than 1.50 in the range of -20 to 110°C, so that even if the temperature of the resin increases during processing such as cutting, it is not easy to soften, etc., and the storage modulus of the backing material in the range of 0 to 50°C is 1000 MPa or more, so that it is not easy to produce positional displacement caused by the stress applied during processing, thereby being able to exhibit excellent processability.

[0056] The present inventors have also discovered that the aforementioned resins having specific viscoelastic properties can be achieved by using specific amounts of resins selected from the following: (A) a reaction-cured product of an epoxy resin having a polyurethane structure and a polyamine compound, (B) a reaction-cured product of an epoxy resin and a polyamine compound having a polyether structure, and (C) a reaction-cured product of a polyisocyanate compound and a polyamine compound. The reason why resins containing any of these (A) to (C) possess these specific viscoelastic properties is unclear, but it is believed that these reaction-cured products (A) to (C) have numerous polar functional groups (urethane bonds, ether bonds, urea bonds) in their molecular chains and exhibit strong intermolecular interactions.

[0057] Hereinafter, the backing material of the present invention will be described in detail.

[0058] (Loss tangent of resin)

[0059] The resin contained in the backing material of the present invention has a loss tangent of 0.06 or more in the range of 0 to 50° C. and a loss tangent of less than 1.50 in the range of −20 to 110° C.

[0060] The loss tangent in the range of 0 to 50°C being 0.06 or more means that the minimum value of the loss tangent in the range of 0 to 50°C is 0.06 or more.

[0061] The minimum value of the loss tangent in the range of 0 to 50°C is not particularly limited as long as it is 0.06 or higher, but is usually 0.40 or lower. The minimum value of the loss tangent in the range of 0 to 50°C may be in the range of 0.06 to 0.40, preferably 0.06 to 0.30, more preferably 0.06 to 0.20, further preferably 0.06 to 0.15, and particularly preferably 0.06 to 0.12.

[0062] The loss tangent in the range of -20 to 110°C is less than 1.50 means that the maximum value of the loss tangent in the range of -20 to 110°C is less than 1.50.

[0063] The maximum value of the loss tangent in the range of -20 to 110°C is not particularly limited as long as it is less than 1.50, but is usually 0.10 or greater. The maximum value of the loss tangent in the range of -20 to 110°C may be in the range of 0.10 to 1.50, preferably 0.10 to 1.25, more preferably 0.10 to 1.00, further preferably 0.10 to 0.75, and particularly preferably 0.10 to 0.55.

[0064] The loss tangent of the resin is measured by the method described in the Examples below. The "loss tangent in the range of 0 to 50°C" and "loss tangent in the range of -20 to 110°C" are values ​​obtained by rounding off the measured values ​​to the third decimal place.

[0065] (Storage modulus of backing material)

[0066] The backing material of the present invention has a storage modulus of 1000 MPa or more in the range of 0 to 50°C.

[0067] The storage modulus in the range of 0 to 50° C. being 1000 MPa or more means that the minimum value of the storage modulus in the range of 0 to 50° C. is 1000 MPa or more.

[0068] The minimum value of the storage modulus in the range of 0 to 50° C. is preferably 2000 MPa or more, more preferably 2500 MPa or more, further preferably 3000 MPa or more, and particularly preferably 3300 MPa or more.

[0069] Typically, the minimum value of the storage modulus in the range of 0 to 50°C is less than 8000 MPa. That is, the minimum value of the storage modulus in the range of 0 to 50°C may be in the range of 1000 MPa or more and less than 8000 MPa, preferably 2000 MPa or more and less than 8000 MPa, more preferably 2500 MPa or more and less than 8000 MPa, further preferably 3000 MPa or more and less than 8000 MPa, and particularly preferably 3300 MPa or more and less than 8000 MPa.

[0070] The storage elastic modulus of the backing material is measured by the method described in the examples described later.

[0071] (Attenuation rate of backing material)

[0072] The attenuation rate of the backing material of the present invention is preferably greater than 0.8dB / (mm·MHz), more preferably greater than 2.5dB / (mm·MHz), further preferably greater than 3.0dB / (mm·MHz), especially preferably greater than 3.5dB / (mm·MHz), and most preferably greater than 4.0dB / (mm·MHz).

[0073] The attenuation rate of the backing material is measured by the method described in the examples described later.

[0074] <Resin>

[0075] The resin contained in the backing material of the present invention contains any one of the following (A) to (C).

[0076] (A) a reaction-cured product of an epoxy resin having a polyurethane structure and a polyamine compound;

[0077] (B) a reaction-cured product of an epoxy resin and a polyamine compound, and a reaction-cured product having a polyether structure; and

[0078] (C) Cured product of reaction of a polyisocyanate compound and a polyamine compound.

[0079] In addition, when the reaction-cured product of an epoxy resin having a polyurethane structure and a polyamine compound contains a polyether structure, it is classified as (A) above, not (B) above. Therefore, the epoxy resin in the reaction-cured product of (B) above does not have a polyurethane structure.

[0080] Furthermore, when the reaction-cured product of the polyisocyanate compound and the polyamine compound contains a polyether structure, it is also classified as the above-mentioned (C).

[0081] From the viewpoint of further improving processability, the resin contained in the backing material of the present invention preferably contains the above-mentioned (C).

[0082] [(A) Cured product of reaction between epoxy resin having polyurethane structure and polyamine compound]

[0083] (Epoxy resin with polyurethane structure)

[0084] Regarding epoxy resins having a polyurethane structure, any epoxy resin having a polyurethane structure and epoxy groups can be used without particular limitation. The number of epoxy groups possessed by epoxy resins having a polyurethane structure is generally 2 or more, preferably 2 to 4, and more preferably 2 to 3. Commercially available epoxy resins having a polyurethane structure generally have a number average molecular weight of 200 to 20,000, for example. Specifically, the following epoxy resins can be cited.

[0085] ADEKA RESIN EPU-6, ADEKA RESIN EPU-7N, ADEKA RESIN EPU-11F, ADEKA RESIN EPU-15F, ADEKA RESIN EPU-1395, ADEKA RESIN EPU-73B, ADEKA RESIN EPU-17, ADEKA RESIN EPU-17T-6, ADEKA RESIN EPU-1001 (all product names, manufactured by ADEKA CORPORATION), EPOXY 802-30CX, EPOXY 803, EPOXY 820-40CX, EPOXY 830, EPOXY 834, EPOXY 840, EPOXY 815, EPOXY 837, EPOXY 810ST, EPOXY 505-15 (all product names, manufactured by Mitsui Chemicals, Inc.), and the like.

[0086] Among these, ADEKA RESIN EPU-7N, ADEKA RESIN EPU-11F, or EPU-17 (all product names, manufactured by ADEKA CORPORATION) is preferred because of its excellent miscibility with thermally conductive particles.

[0087] The epoxy equivalent weight of the epoxy resin having a polyurethane structure is not particularly limited, but is preferably 170 to 2000 g / mol, more preferably 200 to 500 g / mol. The epoxy equivalent weight refers to the mass (g) of the epoxy resin having a polyurethane structure per 1 mol of epoxy groups.

[0088] The viscosity of the epoxy resin having a polyurethane structure at 25°C is not particularly limited, but is preferably 200 to 200,000 mPa·s, more preferably 600 to 30,000 mPa·s. The viscosity is a value measured by the method described in the Examples below. The viscosity in (A) to (C) below also has the same meaning.

[0089] (Polyamine compound)

[0090] As the polyamine compound that reacts with the epoxy resin having a polyurethane structure, any polyamine compound having two or more amino groups can be used without particular limitation, but polyamine compounds generally used as curing agents for epoxy resins are preferably used.

[0091] The polyamine compound may be any of an aliphatic polyamine compound {a chain aliphatic polyamine compound having an amino group bonded to an aliphatic chain (wherein the chain aliphatic polyamine compound does not have a ring structure), a cyclic aliphatic polyamine compound having an amino group bonded to an aliphatic ring directly or via an aliphatic chain (wherein the cyclic aliphatic polyamine compound may have a nitrogen atom constituting an amino group as a ring-constituting atom of the aliphatic ring), an aliphatic polyamine compound having an aromatic ring (an aliphatic polyamine compound having an amino group bonded to an aliphatic chain or an aliphatic ring and having an aromatic ring)} and an aromatic polyamine compound (a polyamine compound having an amino group bonded directly to an aromatic ring), or a mixture thereof. Aliphatic polyamine compounds are preferred due to their excellent reactivity. The polyamine compound may have a ring structure as described above. In addition to nitrogen atoms, it may contain heteroatoms such as oxygen atoms and sulfur atoms, and may have a polyether structure. As the polyether structure, a polyether structure having a number average molecular weight of 200 to 6000 is preferably cited.

[0092] The number of amino groups in the polyamine compound is preferably 2 or 3.

[0093] A polyamine compound may have two or more amino groups as long as they are amino groups having active hydrogen. Specifically, they may be at least one of an unsubstituted amino group (-NH2) and a monosubstituted amino group having one active hydrogen, preferably an unsubstituted amino group (-NH2). Furthermore, a monosubstituted amino group having one active hydrogen may be incorporated into the compound in a >NH configuration. Furthermore, in addition to the two or more amino groups (amino groups having active hydrogen) of the polyamine compound, the polyamine compound may also have a disubstituted amino group (amino group not having active hydrogen).

[0094] The number of active hydrogen atoms derived from the amino group in the polyamine compound may be 2 or more, preferably 3 to 6, and more preferably 4 to 6.

[0095] Among them, the polyamine compound preferably has two or more unsubstituted amino groups (—NH 2 ), and more preferably has two or three unsubstituted amino groups (—NH 2 ).

[0096] The polyamine compound may be a low molecular weight compound or a high molecular weight compound.

[0097] Specific examples of the polyamine compound include the following compounds.

[0098] For example, examples of the chain aliphatic polyamine compound include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine, diethylaminopropylamine, hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, etc. In addition, examples of the chain aliphatic polyamine compound containing an oxygen atom include chain aliphatic polyamine compounds having a polyalkylene oxide structure such as a polyethylene oxide structure and a polypropylene oxide structure, such as Jeffamine D-230, Jeffamine D-400, Jeffamine D-2000, Jeffamine T-403, and Jeffamine T-5000 (all product names, manufactured by Huntsman Co., Ltd.).

[0099] Examples of the cyclic aliphatic polyamine compound include N-aminoethylpiperazine, 4,4′-methylenebis(2-methylcyclohexane-1-amine), methylenediamine, isophoronediamine, bis(4-aminocyclohexyl)methane, and 1,3-bisaminomethylcyclohexane.

[0100] Examples of aliphatic polyamine compounds having an aromatic ring (a polyamine compound having an aromatic ring and an amino group bonded to an aliphatic chain or an aliphatic ring) include meta-xylylenediamine, Gascamine 240, and Gascamine 328 (all product names, manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0101] Examples of the aromatic polyamine compound include metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Examples include ELASMA 250P, ELASMA 650P, ELASMA 1000P, and POREA SL-100A (all product names, manufactured by KUMIAI CHEMICAL INDUSTRY CO., LTD.).

[0102] Among these polyamine compounds, from the perspective of good reactivity and excellent intermolecular interaction, it is preferred to include an aliphatic polyamine compound having an aromatic ring. In particular, from the perspective of further improving ultrasonic attenuation and processability in the embodiment comprising the reaction cured product (A), it is preferred to include an aliphatic polyamine compound having an aromatic ring and a chain aliphatic polyamine compound having no aromatic ring.

[0103] The amino group equivalent of the polyamine compound is not particularly limited, but is preferably 30 to 12,000 g / mol, more preferably 30 to 3,000 g / mol, and even more preferably 30 to 1,200 g / mol. The amino group equivalent refers to the mass (g) of the polyamine compound per 1 mol of amino groups.

[0104] The polyamine compound may be solid or liquid at 25° C. When the polyamine compound is liquid at 25° C., the viscosity of the polyamine compound at 25° C. is not particularly limited, but is preferably 1 to 30,000 mPa·s, more preferably 3 to 30,000 mPa·s, and even more preferably 3 to 20,000 mPa·s.

[0105] [(B) Reaction Cured Product of Epoxy Resin and Polyamine Compound, Having a Polyether Structure]

[0106] As the reaction cured product of (B), any reaction cured product can be used without particular limitation as long as it is a reaction cured product of an epoxy resin and a polyamine compound having two or more amino groups and has a polyether structure.

[0107] The reaction-cured product (B) can be obtained by any of the following: a reaction of an epoxy resin having a polyether structure with a polyamine compound not having a polyether structure, a reaction of an epoxy resin not having a polyether structure with a polyamine compound having a polyether structure, or a reaction of an epoxy resin having a polyether structure with a polyamine compound having a polyether structure. The polyether structure possessed by the reaction-cured product thus obtained is generally a polyether structure having a number average molecular weight of 200 to 6000. Of these, the reaction-cured product (B) is preferably a reaction-cured product of an epoxy resin having a polyether structure with a polyamine compound not having a polyether structure, or a reaction-cured product of an epoxy resin not having a polyether structure with a polyamine compound having a polyether structure. From the viewpoint of exhibiting a more preferred viscosity as a curable resin composition, a reaction-cured product of an epoxy resin not having a polyether structure with a polyamine compound having a polyether structure is more preferred.

[0108] (Epoxy resin)

[0109] The number of epoxy groups contained in the epoxy resin is usually 2 or more, preferably 2 to 4, and more preferably 2 to 3.

[0110] Examples of commercially available epoxy resins having a polyether structure generally include epoxy resins having a polyether structure with a number average molecular weight of 200 to 6000, and specifically, the following epoxy resins can be mentioned.

[0111] DENACOL EX-851, DENACOL EX-832, DENACOL EX-101, DENACOL EX-103 (all product names, manufactured by Nagase ChemteX Corporation), DER 732 (product name, manufactured by Dow Chemical Company), ADEKA RESIN EP-4000 (product name, manufactured by ADEKA CORPORATION), and the like.

[0112] From the viewpoint of excellent mechanical strength, it is preferable to have a bisphenol structure, and ADEKA RESIN EP-4000, DENACOL EX-103, and the like are preferred.

[0113] Examples of epoxy resins not having a polyether structure include bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol E epoxy resins, and novolac epoxy resins. Bisphenol A epoxy resins are preferred because the resulting reaction cured product has excellent mechanical strength.

[0114] The epoxy equivalent of the epoxy resin is not particularly limited, but is preferably 160 to 550 g / mol, more preferably 160 to 400 g / mol, and even more preferably 165 to 230 g / mol. The epoxy equivalent refers to the mass (g) of the epoxy resin per 1 mol of epoxy groups.

[0115] The viscosity of the epoxy resin at 25° C. is not particularly limited, but is, for example, preferably 700 to 20,000 mPa·s, more preferably 1,000 to 20,000 mPa·s, and even more preferably 1,000 to 15,000 mPa·s.

[0116] (Polyamine compound)

[0117] Examples of the polyamine compound for obtaining the reaction cured product of (B) include polyamine compounds that react with the epoxy resin having a polyurethane structure in (A), and the preferred range is the same.

[0118] Examples of commercially available polyamine compounds having a polyether structure generally include polyamine compounds having a number average molecular weight of 200 to 6000, and specific examples thereof are as follows.

[0119] Among the polyamine compounds reacting with the epoxy resin with a polyurethane structure in the aforementioned (A), for example, JEFFAMINE D-230, JEFFAMINE D-400, JEFFAMINE D-2000, JEFFAMINE T-403, JEFFAMINE T-5000 (all product names, manufactured by HUNTSMAN) etc. can be preferably enumerated. In order to adjust the average molecular weight and adjust the mechanical strength of the obtained reaction cured product, it is also preferred to use a variety of them in combination. For example, by mixing JEFFAMINE D-400 and JEFFAMINE D-2000 or mixing JEFFAMINE D-230 and JEFFAMINE T-5000, preferred mechanical strength can be obtained, and these are all product names manufactured by HUNTSMAN.

[0120] [(C) Reaction Cured Product of Polyisocyanate Compound and Polyamine Compound]

[0121] (Polyisocyanate compound)

[0122] As the polyisocyanate compound, any polyisocyanate compound having two or more isocyanate groups can be used without particular limitation. For example, various polyisocyanate compounds used in the production of polyurethane and polyurea can be preferably used.

[0123] The polyisocyanate compound may be any of an aliphatic isocyanate compound (a compound in which an isocyanate group is bonded to an aliphatic chain or aliphatic ring) and an aromatic isocyanate compound (a compound in which an isocyanate group is bonded to an aromatic ring), or a mixture thereof. The polyisocyanate compound may have a ring structure.

[0124] The number of isocyanate groups in the polyisocyanate compound is preferably 2 or 3, more preferably 2.

[0125] Examples of the polyisocyanate compound include diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), meta-xylylenediisocyanate (XDI), norbornane diisocyanate (NBDI), and 1,4-bis(isocyanatomethyl)cyclohexane (1,4-H6XDI).

[0126] Furthermore, from the viewpoint of low reactivity and long pot life when preparing a reaction cured product, an aliphatic polyisocyanate compound is preferred, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), meta-xylylenediisocyanate (XDI), norbornane diisocyanate (NBDI) or 1,4-bis(isocyanatomethyl)cyclohexane (1,4-H6XDI) is more preferred, and meta-xylylenediisocyanate (XDI) or norbornane diisocyanate (NBDI) is even more preferred.

[0127] Furthermore, from the viewpoint of further improving ultrasonic attenuation properties, it is preferred that an aliphatic polyisocyanate compound having an aromatic ring and an aromatic polyisocyanate compound be contained.

[0128] The isocyanate group equivalent weight of the polyisocyanate compound is not particularly limited, but is preferably 50 to 500 g / mol, more preferably 50 to 250 g / mol. The isocyanate group equivalent weight refers to the mass (g) of the polyisocyanate compound per 1 mol of isocyanate groups.

[0129] The polyisocyanate compound may be solid or liquid at 25° C. When the polyisocyanate compound is liquid at 25° C., the viscosity of the polyisocyanate compound at 25° C. is not particularly limited, but is preferably, for example, 1 to 30,000 mPa·s, more preferably 3 to 30,000 mPa·s, and even more preferably 3 to 20,000 mPa·s.

[0130] (Polyamine compound)

[0131] Examples of the polyamine compound for obtaining the reaction cured product of (C) include polyamine compounds that react with the epoxy resin having a polyurethane structure in (A). Unless otherwise specified, the preferred range can be adopted.

[0132] As the polyamine compound, among the polyamine compounds that react with the epoxy resin having a polyurethane structure in (A), aromatic polyamine compounds having a polyether structure such as ELASMER 250P, ELASMER 650P, ELASMER 1000P, and POREA SL-100A (all product names, manufactured by KUMIAI CHEMICAL INDUSTRY CO., LTD.) are preferred because of their low reactivity and long pot life when a cured product is produced.

[0133] The content of the reaction-cured product of any one of (A) to (C) in the resin contained in the backing material of the present invention is not particularly limited as long as the effects of the present invention are exhibited. For example, it can be 15% by volume or more, preferably 20% by volume or more, more preferably 30% by volume or more, further preferably 50% by volume or more, and particularly preferably 70% by volume or more. It is also preferred that the entire resin contained in the backing material of the present invention consists of any one of (A) to (C) above.

[0134] The content of the resin in the backing material is 25 to 50% by volume, preferably 30 to 50% by volume.

[0135] Thermally conductive particles

[0136] As thermally conductive particles, as long as they have thermal conductivity (preferably thermal conductivity of 30W / m·K or more), any of inorganic particles and organic particles can be used, and thermally conductive particles that impart heat dissipation to the backing material can be used without particular restriction. The shape of the particles is not particularly limited, and particles of various shapes such as irregular shape, spherical, fibrous, fibrous with branches, and flat plate can be used. If the shape is spherical, the filling rate can be improved, so it is preferred. On the other hand, if the shape is anisotropic, such as fibrous or flat, the particle contact can be increased, heat dissipation can be improved, so it is preferred. Moreover, in the case of irregularly shaped particles, ultrasound can be reflected randomly, so it is preferred from the perspective of being able to improve the ultrasonic attenuation of the backing material.

[0137] Examples of the inorganic particles include metal particles made of silver, copper, gold, aluminum, iron, brass, tungsten, molybdenum, zinc, etc. Among these, particles of tungsten or molybdenum are preferred due to their low electrical conductivity.

[0138] Furthermore, oxides, carbides, or nitrides of the above-mentioned metal particles can also be preferably used. For example, aluminum trioxide (aluminum oxide, sapphire), zinc oxide, aluminum nitride, tungsten carbide, or molybdenum carbide is preferred.

[0139] Furthermore, inorganic particles such as silicon carbide and boron nitride can also be preferably used.

[0140] That is, as the inorganic particles, metal particles, ceramic particles, etc. can be preferably used.

[0141] Examples of organic particles include graphite, carbon nanotubes, and diamond, of which diamond is preferred due to its low electrical conductivity.

[0142] The thermal conductivity of the thermally conductive particles is preferably 30 W / m·K or higher.

[0143] The surface of the metal particles can be surface treated. As surface treatment, UV (ultraviolet) surface treatment, plasma surface treatment, corona surface treatment, silane coupling treatment, titanium coupling treatment, aluminum coupling treatment, phosphoric acid treatment etc. can be enumerated. By surface treatment, the functional group on the particle surface can be changed, the dispersibility of the particle in the resin can be improved, and the thermal conductivity and ultrasonic attenuation of the variation based on the interparticle distance can be realized.

[0144] The thermally conductive particles preferably include at least one of metal particles and ceramic particles.

[0145] The particle size of the thermally conductive particles is not particularly limited. From the perspective of maintaining a low viscosity of the curable resin composition described below while maintaining high mechanical strength of the backing material (cured product) of the present invention, the particle size of the thermally conductive particles is preferably 1 to 300 μm, more preferably 5 to 100 μm, and even more preferably 8 to 30 μm.

[0146] The “particle size” of the thermally conductive particles is a number average particle size, and is a value measured by the method described in Examples below.

[0147] The proportion of the thermally conductive particles in the total amount of the components other than the resin in the backing material is preferably 50% by volume or more, more preferably 60% by volume or more, and even more preferably 65% ​​by volume or more. All components other than the resin in the backing material of the present invention are also preferably thermally conductive particles.

[0148] The content of the thermally conductive particles in the backing material is, for example, preferably 30 to 60% by volume, more preferably 30 to 55% by volume, and even more preferably 30 to 50% by volume.

[0149] In addition, the thermally conductive particles may be used alone or in combination of two or more. In the present invention, when two or more thermally conductive particles are contained, the ratio and content of the thermally conductive particles refer to the total amount thereof.

[0150] <Other ingredients>

[0151] The backing material of the present invention may contain other components in addition to the above-mentioned resin and thermally conductive particles.

[0152] As other components, hollow particles are preferably included. By including hollow particles, ultrasonic attenuation can be further improved. As hollow particles, commonly used hollow particles for the purpose of improving the effect of sound wave attenuation or ultrasonic attenuation can be used without particular limitation. Any of hollow glass particles and hollow resin particles can be used, and hollow resin particles are preferably used.

[0153] Preferred examples of hollow particles include glass capsules, hollow silica, cenospheres, phenolic resin microcapsules, urea resin microcapsules, plastic microcapsules such as polymethyl methacrylate capsules, and thermally expandable microcapsules.

[0154] In addition, as hollow particles, plastic microcapsules whose surfaces are coated with inert inorganic powders such as calcium carbonate can be used, for example, MFL-81GCA, MFL-SEVEN, MFL-HD30CA, MFL-HD60CA, MFL-100MCA (all product names, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) of the Matsumoto Microsphere series.

[0155] In addition, the hollow particles may be used alone or in combination of two or more kinds. In the present invention, when two or more kinds of hollow particles are contained, the content of the hollow particles refers to the total amount thereof.

[0156] The particle size of the hollow particles is not particularly limited. From the perspective of maintaining the mechanical strength of the backing material (cured product) of the present invention while suppressing the viscosity of the curable resin composition described later to a low level, the particle size of the hollow particles is preferably 1 to 300 μm, more preferably 5 to 100 μm, and even more preferably 20 to 80 μm.

[0157] The "particle size" of the hollow particles has the same meaning as the "particle size" of the thermally conductive particles described above. That is, the "particle size" of the hollow particles is a number average particle size, which is a value measured by the method described in the Examples below.

[0158] As other components, a dispersant, a diluent, a colorant, a viscosity modifier, a plasticizer, a curing accelerator, etc. may be contained.

[0159] The content of other components in the backing material can be set to 10 to 20% by volume, for example.

[0160] As a preferred embodiment of the backing material of the present invention, for example, there can be cited a backing material for an ultrasonic probe comprising a resin containing any one of the above-mentioned (A) to (C) and thermally conductive particles, wherein the resin has the above-mentioned specific viscoelastic properties, the backing material is a backing material having a specific storage modulus, and contains the above-mentioned hollow particles.

[0161] In this embodiment, the content of each component in the backing material is that of the resin is 25 to 50 volume %, preferably 30 to 50 volume %, the content of the thermally conductive particles is preferably 30 to 60 volume %, more preferably 30 to 55 volume %, further preferably 30 to 50 volume %, and the content of the hollow particles is preferably 10 to 20 volume %.

[0162] <Curable resin composition>

[0163] The backing material of the present invention is preferably formed using the curable resin composition of the present invention.

[0164] The curable resin composition of the present invention is a curable resin composition for forming the backing material of the present invention.

[0165] The curable resin composition includes thermally conductive particles and any one of the following (a) to (c) as a resin component:

[0166] (a) a combination of an epoxy resin having a polyurethane structure and a polyamine compound;

[0167] (b) a combination of an epoxy resin and a polyamine compound, wherein at least one of the epoxy resin and the polyamine compound has a polyether structure; and

[0168] (c) a combination of a polyisocyanate compound and a polyamine compound,

[0169] The viscosity of the curable resin composition is 5000 Pa·s or less under the conditions of 25° C. and a shear rate of 0.01 / s.

[0170] The resin component in the curable resin composition of the present invention and the above-mentioned (a) to (c) respectively correspond to the resin and (A) to (C) in the backing material of the present invention by forming the backing material of the present invention.

[0171] Therefore, the description of the epoxy resin and polyamine compound having a polyurethane structure in (A) can be applied to the epoxy resin and polyamine compound having a polyurethane structure in (B). The description of the epoxy resin and polyamine compound in (B) can be applied to the epoxy resin and polyamine compound in (B). The description of the polyisocyanate compound and polyamine compound in (C) can be applied to the polyisocyanate compound and polyamine compound in (C).

[0172] In addition, in the combination of an epoxy resin having a polyurethane structure and a polyamine compound, if at least one of the epoxy resin having a polyurethane structure and the polyamine compound contains a polyether structure, it is classified as (a) above, not (b) above. Therefore, the epoxy resin in (b) above does not have a polyurethane structure.

[0173] Furthermore, in the combination of a polyisocyanate compound and a polyamine compound, when at least one of the polyisocyanate compound and the polyamine compound contains a polyether structure, it is classified as the above-mentioned (c) instead of the above-mentioned (b).

[0174] In addition, regarding the mixing ratio of the epoxy resin with a polyurethane structure and the polyamine compound in the above (a), it can be appropriately adjusted so that the backing material of the present invention obtained as a resin containing the above (A) shows specific viscoelastic properties and shows a specific storage modulus as a backing material. This is also the same for the above (b) and (c). That is, regarding the mixing ratio of the epoxy resin and the polyamine compound (wherein, at least one of the above epoxy resin and the above polyamine compound has a polyether structure) in the above (b), it can be appropriately adjusted so that the backing material of the present invention obtained as a resin containing the above (B) shows specific viscoelastic properties and shows a specific storage modulus as a backing material. Regarding the mixing ratio of the polyisocyanate compound and the polyamine compound in the above (c), it can be appropriately adjusted so that the backing material of the present invention obtained as a resin containing the above (C) shows specific viscoelastic properties and shows a specific storage modulus as a backing material.

[0175] The thermally conductive particles in the curable resin composition of the present invention correspond to the thermally conductive particles in the backing material of the present invention. Therefore, the description of the thermally conductive particles in the backing material of the present invention can be applied to the thermally conductive particles in the curable resin composition of the present invention.

[0176] Furthermore, the curable resin composition of the present invention may also contain other components described in the backing material of the present invention.

[0177] (Viscosity of Curable Resin Composition)

[0178] The viscosity of the curable resin composition of the present invention is 5000 Pa·s or less under the conditions of 25° C. and a shear rate of 0.01 / s.

[0179] The viscosity of the curable resin composition of the present invention is measured by the method described in Examples below.

[0180] Since the curable resin composition of the present invention satisfies the above-mentioned specific viscosity (viscosity), it has fluidity sufficient to flow into a mold and can be molded into a desired shape.

[0181] The viscosity of the curable resin composition of the present invention at 25° C. and a shear rate of 0.01 / s is preferably 3000 Pa·s or less, more preferably 2000 Pa·s or less, further preferably 1000 Pa·s or less, and particularly preferably 800 Pa·s or less.

[0182] The contents of the thermally conductive particles and the resin component in the curable resin composition of the present invention are not particularly limited as long as the backing material of the present invention can be obtained.

[0183] The content of any one of (a) to (c) in the resin component of the curable resin composition of the present invention is not particularly limited as long as the effects of the present invention are exhibited. For example, it may be 15% by volume or more, preferably 20% by volume or more, more preferably 30% by volume or more, further preferably 50% by volume or more, and particularly preferably 70% by volume or more. The upper limit is not particularly limited and can be 100% by volume or less.

[0184] The content of the resin component in the curable resin composition of the present invention is preferably 25 to 50% by volume, more preferably 30 to 50% by volume.

[0185] The proportion of the thermally conductive particles in the curable resin composition of the present invention in the total amount of components other than the resin component is preferably 50% by volume or more, more preferably 60% by volume or more, and even more preferably 70% by volume or more. All components other than the resin component in the curable resin composition of the present invention are also preferably thermally conductive particles.

[0186] The content of the thermally conductive particles in the curable resin composition of the present invention is, for example, preferably 30 to 60% by volume, more preferably 30 to 55% by volume, and even more preferably 30 to 50% by volume.

[0187] Furthermore, when the curable resin composition of the present invention contains the above-mentioned other components, the content of the other components in the curable resin composition of the present invention can be set to 10 to 20% by volume, for example.

[0188] Preferred embodiments of the curable resin composition of the present invention include, for example, a resin component comprising any one of (a) to (c) and thermally conductive particles, wherein the curable resin composition has the specific viscoelastic properties described above and contains the hollow particles.

[0189] In this embodiment, among the contents of the various components in the curable resin composition, the content of the resin component is preferably 25 to 50 volume %, more preferably 30 to 50 volume %, the content of the thermally conductive particles is preferably 30 to 60 volume %, more preferably 30 to 55 volume %, further preferably 30 to 50 volume %, and the content of the hollow particles is preferably 10 to 20 volume %.

[0190] <Method for manufacturing backing material>

[0191] The curable resin composition of the present invention can be prepared by a conventional method.

[0192] For example, the curable resin composition of the present invention can be obtained by mixing the thermally conductive particles and the resin component comprising any one of (a) to (c), and other suitable components in a kneading device such as a rotation / revolution mixer, a kneader, a pressure kneader, a Banbury mixer (continuous kneader), or a twin-roll mixer. The order in which the components are mixed is not particularly limited. The mixing conditions are not particularly limited, as long as the thermally conductive particles and other suitable components are dispersed in the resin component.

[0193] The backing material of the present invention can be obtained by curing the curable resin composition of the present invention thus obtained. The curing conditions can be adjusted according to the chemical reaction of the resin components contained in the curable resin composition of the present invention. For example, the backing material can be obtained by heating and curing at 20-200°C for 5-500 minutes.

[0194] The shape of the backing material is not particularly limited. For example, the backing material can be made into a shape preferred for the backing material using the mold during the curing process. Alternatively, the backing material can be obtained in sheet form and cut into the desired shape using cutting or the like.

[0195] Furthermore, the backing material of the present invention has excellent processability, and therefore, even when cut into a desired shape at a pitch of μm order, a desired backing material can be produced while suppressing deformation, breakage, and the like.

[0196] The backing material of the present invention is suitable for medical components, and can be preferably used in, for example, acoustic wave probes and acoustic wave measuring devices, and can be preferably used in ultrasonic probes and ultrasonic diagnostic devices. Furthermore, the acoustic wave measuring device in the present invention is not limited to ultrasonic diagnostic devices or photoacoustic wave measuring devices, but refers to a device that receives acoustic waves reflected or generated by an object and displays them as an image or signal intensity.

[0197] In particular, the backing material of the present invention can be preferably used as a backing material for an ultrasonic probe, a backing material in a photoacoustic wave measuring device or an ultrasonic endoscope, and a backing material in an ultrasonic probe having a capacitive micromachined ultrasonic transducer (cMUT: Capacitive Micromachined Ultrasonic Transducers) as an ultrasonic transducer array.

[0198] Specifically, the backing material of the present invention is preferably used in acoustic wave measuring devices such as ultrasonic diagnostic devices described in Japanese Patent Application Laid-Open No. 2003-169802 and photoacoustic wave measuring devices described in Japanese Patent Application Laid-Open No. 2013-202050 and Japanese Patent Application Laid-Open No. 2013-188465.

[0199] <<Acoustic Probe>>

[0200] according to Figure 1 The structure of the ultrasonic probe in the ultrasonic diagnostic device described in [ 1 ] is described in more detail below, and the structure of the acoustic wave probe using the backing material of the present invention is described in more detail below. Furthermore, an ultrasonic probe refers to a probe that uses ultrasound as a sound wave, particularly among acoustic wave probes. Therefore, the basic structure of an ultrasonic probe can be directly applied to an acoustic wave probe.

[0201] Ultrasonic probe

[0202] according to Figure 1 The structure of the ultrasonic probe in the ultrasonic diagnostic apparatus described in is described below in more detail.

[0203] The ultrasonic probe 10 is a main component of the ultrasonic diagnostic apparatus, which has the function of transmitting and receiving ultrasonic beams while generating ultrasonic waves. Figure 1 As shown, an acoustic lens 1, an acoustic matching layer 2, a piezoelectric element layer 3, and a backing material 4 are provided in this order from the distal end (the surface in contact with the living organism being examined). Furthermore, in recent years, a technology has been proposed for the purpose of receiving higher harmonics, in which the transmitting ultrasonic transducer (piezoelectric element) and the receiving ultrasonic transducer (piezoelectric element) are constructed of different materials and formed into a stacked structure.

[0204] <Piezoelectric element layer>

[0205] The piezoelectric element layer 3 is a portion that generates ultrasonic waves. Electrodes are attached to both sides of the piezoelectric element. When voltage is applied, the piezoelectric element repeats expansion and contraction and vibrates, thereby generating ultrasonic waves.

[0206] Piezoelectric elements are widely made of inorganic piezoelectric ceramics, made by polarizing single crystals such as quartz crystal, LiNbO3, LiTaO3, and KNbO3, thin films of ZnO and AlN, and sintered bodies of Pb(Zr, Ti)O3. Piezoelectric ceramics such as PZT (lead zirconate titanate) are commonly used, offering excellent conversion efficiency.

[0207] Furthermore, piezoelectric elements that detect high-frequency reception waves need to have sensitivity over a wider bandwidth. Therefore, organic piezoelectrics made of organic polymers such as polyvinylidene fluoride (PVDF) are used as piezoelectric elements suitable for high frequencies and wide bandwidths.

[0208] Japanese Patent Application Laid-Open No. 2011-071842 describes a cMUT utilizing MEMS (Micro Electro Mechanical Systems) technology, which can achieve an array structure exhibiting excellent short pulse and broadband characteristics, excellent mass productivity, and little characteristic variation.

[0209] In the present invention, any piezoelectric element material can be preferably used.

[0210] <Backing material>

[0211] The backing material 4 is provided on the back surface of the piezoelectric element layer 3 and reduces the pulse width of ultrasonic waves by suppressing unnecessary vibrations, thereby contributing to improving the distance resolution in ultrasonic diagnostic images.

[0212] In the ultrasonic probe of the present invention, the backing material 4 comprises the backing material of the present invention. The backing material of the present invention exhibits excellent ultrasonic attenuation and processability, and also exhibits high heat dissipation due to the thermally conductive particles. Therefore, by using the backing material or the curable resin composition of the present invention, the backing material 4 can be produced with high productivity while suppressing deformation and breakage during operation of the ultrasonic probe. This backing material 4 suppresses unwanted vibrations radiating from the piezoelectric element layer 3 to the back side and effectively dissipates heat released from the piezoelectric element layer 3.

[0213] Acoustic Matching Layer

[0214] The acoustic matching layer 2 is provided to reduce the difference in acoustic impedance between the piezoelectric element layer 3 and the object under examination and to efficiently transmit and receive ultrasonic waves.

[0215] Acoustic lens

[0216] The acoustic lens 1 is provided to focus ultrasound in the slice direction by utilizing refraction to improve resolution. Furthermore, it needs to be in close contact with the living body to be examined, and the ultrasound waves need to be matched to the acoustic impedance of the living body (1.4 to 1.7 Mrayl for the human body).

[0217] That is, by using a material having a sound velocity sufficiently lower than that of the human body and an acoustic impedance close to the value of human skin as the material of the acoustic lens 1 , the ultrasonic wave transmission and reception sensitivity becomes good.

[0218] The operation of the ultrasonic probe 10 with this structure will be described. Voltage is applied to electrodes on both sides of the piezoelectric element layer 3, causing the piezoelectric element layer 3 to resonate and transmitting an ultrasonic signal from the acoustic lens 1 to the subject. During reception, the reflected signal (echo signal) from the subject causes the piezoelectric element layer 3 to vibrate, which is then electrically converted into a signal, thereby obtaining an image.

[0219] -Ultrasonic probe equipped with cMUT (capacitive micromachined ultrasonic transducer)-

[0220] When the cMUT devices described in Japanese Patent Application Laid-Open Nos. 2006-157320 and 2011-71842 are used in an ultrasonic transducer array, their sensitivity is generally lower than that of a transducer using a conventional piezoelectric ceramic (PZT).

[0221] Furthermore, since the cMUT device is manufactured using MEMS technology, it is possible to provide the market with an ultrasonic probe that is more easily mass-producible and less expensive than a piezoelectric ceramic probe.

[0222] -Photoacoustic wave measurement device using photoacoustic wave imaging-

[0223] Photoacoustic imaging (PAI) described in Japanese Patent Application Laid-Open No. 2013-158435 and the like displays an image obtained by imaging ultrasound waves, which are generated when light (electromagnetic waves) is irradiated into the human body and human tissues adiabatically expand due to the irradiated light, or displays the signal intensity of ultrasound waves.

[0224] -Ultrasound endoscope-

[0225] The ultrasonic endoscope described in Japanese Patent Application Laid-Open No. 2008-311700 and the like includes an insertion portion inserted into the body and an operation portion connected to the proximal end of the insertion portion. An ultrasonic probe is provided at the distal end of the insertion portion.

[0226] By using a backing material including the backing material of the present invention as a backing material constituting an ultrasonic probe, unnecessary vibration applied to the ultrasonic endoscope can be suppressed, thereby improving the acoustic characteristics of the ultrasonic endoscope.

[0227] Example

[0228] Hereinafter, the present invention will be described in further detail with reference to Examples, but the present invention is not to be construed as being limited thereto.

[0229] Example

[0230] <1> Preparation of backing material composition

[0231] Compositions for backing materials (curable resin compositions) having the compositions described in Table 1-1 and Table 1-2 (hereinafter collectively referred to as “Table 1”) were prepared.

[0232] Specifically, the resin raw materials, thermally conductive particles (WC-3 and SiC-1), and hollow particles (B-1) were weighed at the content ratios listed in Table 1 and mixed using a rotation / revolution mixer (product name: Awatori Nentaro Vacuum Type ARV-310, manufactured by THINKY CORPORATION) to prepare backing material compositions Nos. 101 to 125 and C01 to C18.

[0233] <2>Preparation of backing material sheet

[0234] The backing material composition prepared above was poured into a square mold with a side of 30 mm and the desired depth, heated at 80°C for 18 hours, and then heated at 150°C for 1 hour to cure. This produced square backing material sheets with a side of 30 mm and the desired thickness, which were used for the following measurements and evaluations. Backing material sheets Nos. 101 to 125 represent the backing materials of the present invention, and backing material sheets Nos. c01 to c18 represent comparative backing materials.

[0235] The depth of the die used and the thickness of the obtained sheets were 2 mm or 0.5 mm, respectively.

[0236] <3> Measurement and evaluation

[0237] The following measurements and evaluations were performed on the backing material composition and the backing material sheet. The results are shown in Table 1.

[0238] (1) Determination of storage modulus

[0239] Test pieces were prepared by cutting a 0.5 mm thick square sheet of backing material into 5 mm wide strips. The storage modulus of these test pieces was measured using an ITK DVA-225 dynamic viscoelasticity measuring instrument (IT Measurement Control Co., Ltd.) under the following conditions: a 20 mm inter-chuck distance, a heating rate of 2°C / minute, a measurement temperature range of -150°C to 250°C, and a frequency of 5 Hz.

[0240] The minimum value of the storage modulus (hereinafter also simply referred to as “elastic modulus”) within the range of 0 to 50° C. was determined and evaluated based on the following criteria.

[0241] -Evaluation Criteria (Elastic Modulus)-

[0242] S: The elastic modulus is 3300 MPa or more and less than 8000 MPa.

[0243] A: The elastic modulus is 3000 MPa or more and less than 3300 MPa.

[0244] B: The elastic modulus is 2500 MPa or more and less than 3000 MPa.

[0245] C: The elastic modulus is 2000 MPa or more and less than 2500 MPa.

[0246] D: The elastic modulus is 1000 MPa or more and less than 2000 MPa.

[0247] E: Elastic modulus is less than 1000 MPa.

[0248] (2) Attenuation rate

[0249] The intensity of the reflected echo was measured using a sing-around sound velocity measuring device (manufactured by ULTRASONIC ENGINEERING CO., LTD., product name: "Ultrasonic Sound Velocity Measuring Device UVM-2") according to the method described in JIS (Japanese Industrial Standards) Z 2354 (2012). The measurement used a 2 MHz measurement probe in 25°C water, and a 2 mm thick backing material sheet was used as the measurement test piece. The attenuation rate was calculated based on the difference in intensity between the presence and absence of the reflected echo and the thickness of the test piece, and evaluated according to the following criteria.

[0250] -Evaluation Criteria (Degradation Rate)-

[0251] S: The attenuation rate exceeds 4.0 dB / (mm·MHz).

[0252] A: The attenuation rate exceeds 3.5 dB / (mm·MHz) and is 4.0 dB / (mm·MHz) or less.

[0253] B: The attenuation rate exceeds 3.0 dB / (mm·MHz) and is 3.5 dB / (mm·MHz) or less.

[0254] C: The attenuation rate exceeds 2.5 dB / (mm·MHz) and is 3.0 dB / (mm·MHz) or less.

[0255] D: The attenuation rate exceeds 0.8 dB / (mm·MHz) and is 2.5 dB / (mm·MHz) or less.

[0256] E: Attenuation rate is 0.8 dB / (mm·MHz) or less.

[0257] (3) Viscosity

[0258] The viscosity of the backing material composition was measured using a HAAKE MARS 40 rheometer (product name, manufactured by Thermo Fisher Scientific Inc.) under the conditions of temperature: 25°C, shear rate: 0.01 / sec, sensor: C35 2° / Ti, measurement mode: oscillation mode, frequency: 0.03 Hz, and evaluated according to the following criteria.

[0259] -Evaluation Criteria (Viscosity)-

[0260] S: Viscosity is 800 Pa·s or less.

[0261] A: The viscosity is more than 800 Pa·s and 1000 Pa·s or less.

[0262] B: The viscosity is more than 1000 Pa·s and is 2000 Pa·s or less.

[0263] C: The viscosity is more than 2000 Pa·s and is 3000 Pa·s or less.

[0264] D: The viscosity is more than 3000 Pa·s and 5000 Pa·s or less.

[0265] E: Viscosity exceeds 5000 Pa·s.

[0266] (4) Processability

[0267] Using an automatic dicing saw DAD321 (product name, manufactured by DISCO Corporation) and a 0.03mm thick diamond blade, a cross-cut was performed on a 0.5mm thick backing material sheet to form grooves with a width of 30μm and a depth of 200μm. This formed a grid with a grid size of 200μm × 200μm, 20 vertical × 20 horizontal (400 squares in total). The grids formed by this cross-cutting were observed under a microscope, and the number of broken and / or collapsed squares among the 400 squares was counted. The workability was evaluated according to the following criteria.

[0268] -Evaluation Criteria (Workability)-

[0269] S: A square that is not damaged and / or collapsed.

[0270] A: The number of broken and / or collapsed squares is 1 or more and 4 or less.

[0271] B: The number of broken and / or collapsed squares is 5 or more and 20 or less.

[0272] C: The number of broken and / or collapsed squares is 21 or more and 40 or less.

[0273] D: The number of broken and / or collapsed squares is 41 or more and 80 or less.

[0274] E: There are 81 or more squares in a broken and / or collapsed state.

[0275]

[0276]

[0277] Notes

[0278] (Resin raw materials)

[0279] R-1 to R-23 and PR-1 to PR-10: These are R-1 to R-23 and PR-1 to PR-10 described in Tables A-1 to A-3 (hereinafter collectively referred to as "Table A"), and are prepared by mixing the main agent and the curing agent in the mixing ratio described in Table A.

[0280] S-1, SE-1, RB-1, EV-1, NBR-1, and IR-1: S-1, SE-1, RB-1, EV-1, NBR-1, and IR-1 listed in Table C below

[0281] (Thermal conductive particles)

[0282] WC-3: Tungsten carbide particles, WC100S (product name), manufactured by ALMT Corp., particle size 10 μm

[0283] SiC-1: Silicon carbide particles, SSC-A15 (product name), manufactured by Shinano Electric Refining Co., Ltd., particle size 17 μm

[0284] (Hollow particles)

[0285] B-1: Hollow resin particles, Matsumoto Microsphere MFL-HD60CA (product name), manufactured by Matsumoto Yushi Seiyaku Co., Ltd., plastic microcapsules with a surface coated with calcium carbonate powder. The value varies depending on the type of backing material sheet (No. 101 to 125, c01 to c18), but the particle size of all sheets is within the range of 50 to 70 μm.

[0286] The particle sizes of the thermally conductive particles and hollow particles are number average particle sizes measured by the following method. Furthermore, the presence of hollow particles in the backing material sheet as hollow particles was confirmed by cutting the backing material sheet with a razor and observing the cross-section using a Miniscope TM4000 (product name, manufactured by Hitachi High-Tech Corporation) desktop microscope.

[0287] (Measurement of number average particle size of particles)

[0288] The number average particle size of the particles was determined by observing the end surface of the backing material sheet in a field of view containing 500 or more particles using a scanning electron microscope (SU8030 (product name) manufactured by Hitachi High-Tech Corporation). 500 particles were randomly selected from the particles in the field of view, and the particle sizes of these particles were measured and calculated.

[0289] Backing material sheets whose end faces could not be observed using a scanning electron microscope were observed using ice embedding transmission electron microscopy. Ice embedding was performed using a Vitrobot Mark IV (product name) manufactured by FEI. Using a transmission electron microscope (JEM-2010 (product name) manufactured by JEOL Ltd.), 500 particles were randomly selected from the field of view, and their particle sizes were measured and calculated.

[0290] When the particles were not perfectly round, particles having a maximum ratio of longitudinal to transverse diameter of 0.7 or greater were extracted and measured.

[0291] The contents of the resin raw material, the thermally conductive particles (WC-3 and SiC-1), and the hollow particles (B-1) are content ratios based on volume.

[0292] Tan δmin (0-50° C.): represents the minimum value of the loss tangent of the resin in the range of 0-50° C. measured by the following method.

[0293] Tan δmax (-20 to 110° C.): indicates the maximum value of the loss tangent of the resin within the range of -20 to 110° C., measured by the following method.

[0294] E' (0 to 50°C): shows the evaluation result regarding the minimum value of the storage modulus of the backing material sheet in the range of 0 to 50°C measured and evaluated as described above.

[0295] [Measurement of the loss tangent of resin]

[0296] (1) Preparation of resin sheets

[0297] The resin raw materials R-1 to R-23 and PR-1 to PR-10 were measured at the mixing ratios listed in Table A for the main agent and curing agent, mixed using a rotary / revolving mixer (product name: Awatori Nentaro Vacuum Type ARV-310, manufactured by THINKY CORPORATION), and molded into sheets with a length of 30 mm, a width of 5 mm, and a thickness of 0.5 mm. The sheets were then cured at 100°C for 2 hours and then at 150°C for 2 hours to produce resin sheets.

[0298] Regarding the resin raw materials S-1, SE-1, RB-1, EV-1, NBR-1 and IR-1, the resin raw materials were directly put into a rotation / revolution mixer (product name: Awatori Nentaro vacuum type ARV-310, manufactured by THINKY CORPORATION), formed into a sheet with a length of 30 mm, a width of 5 mm, and a thickness of 0.5 mm, and cured at 100°C for 2 hours, and then cured at 150°C for 2 hours to produce a resin sheet.

[0299] (2) Evaluation of viscoelasticity of resin sheets

[0300] The loss tangent of the produced resin sheet was measured using a dynamic viscoelasticity measuring apparatus ITK DVA-225 (product name, manufactured by IT Measurement Control Co., Ltd.) under the conditions of an inter-chuck distance of 20 mm, a heating rate of 2°C / min, a measurement temperature range of -150°C to 250°C, and a frequency of 5 Hz.

[0301]

[0302]

[0303]

[0304] [Table C]

[0305] Table C

[0306]

[0307] Notes

[0308] The main agent and curing agent in Table A are shown in Table B.

[0309] The mix ratio of the main agent and the curing agent is based on mass.

[0310] A blank column in a row for the main agent and curing agent in the table indicates that the agent is not contained.

[0311] The functional group equivalent refers to the mass (g) of the compound per 1 mol of functional groups (epoxy groups, isocyanate groups, or amino groups), and the unit is g / mol.

[0312] Viscosity is the viscosity at 25°C, expressed in mPa·s. This value was measured using a HAAKE MARS 40 rheometer (product name, manufactured by Thermo Fisher Scientific Inc.) under the conditions of 25°C, a shear rate of 0.01 / s, a sensor of C35 2° / Ti, an oscillation mode, and a frequency of 0.03 Hz. In the case of a solid at 25°C, it is indicated as "solid" in the table.

[0313] Polymer MDI stands for polymethylene polyphenylene polyisocyanate, and refers to a mixture of 4,4'-MDI and a high molecular weight polyisocyanate.

[0314] As shown in Table 1, comparative backing material sheets No. c01-c03, c05, and c08-c10 do not meet the requirements of the present invention in terms of a resin loss tangent of less than 0.06 within the temperature range of 0-50°C. These comparative backing material sheets No. c01-c03, c05, and c08-c10 have low attenuation rates and poor ultrasonic attenuation. Furthermore, comparative backing material sheet No. c06 does not meet the requirements of the present invention in terms of a resin loss tangent of 1.50 or greater within the temperature range of -20-110°C. This comparative backing material sheet No. c06 also has poor processability. Furthermore, comparative backing material sheet No. c04 does not meet the requirements of the present invention in terms of a resin loss tangent of less than 0.06 within the temperature range of 0-50°C and a resin loss tangent of 1.50 or greater within the temperature range of -20-110°C. The comparative backing material sheet No. c04 has poor ultrasonic attenuation and processability. In terms of the storage modulus of the backing material in the range of 0 to 50°C being less than 1000 MPa, the comparative backing material sheet No. c07 does not meet the requirements of the present invention. The comparative backing material sheet No. c07 has poor processability. Furthermore, in terms of the resin content in the backing material being 20% ​​by volume, the comparative backing material sheet No. c17 does not meet the requirements of the present invention. The comparative backing material sheet No. c17 has poor processability. In terms of the resin content in the backing material being 55% by volume, the comparative backing material sheet No. c18 does not meet the requirements of the present invention. The comparative backing material sheet No. c18 has poor processability.

[0315] Furthermore, the comparative backing material sheets Nos. c11 to c16, which used silicone resin, silicone resin-modified epoxy resin, EPDM (ethylene-propylene) rubber, ethylene-vinyl acetate copolymer, liquid nitrile rubber, or isoprene rubber as known base materials for the backing material, did not meet the requirements of the present invention because the storage modulus of the backing material within the range of 0 to 50°C was less than 1000 MPa, and in Nos. c11, c12, c15, and c16, the loss tangent of the resin within the range of 0 to 50°C was further less than 0.06. These comparative backing material sheets Nos. c11 to c16 also had poor processability.

[0316] On the other hand, it was found that backing material sheets Nos. 101 to 125, which satisfied the requirements of the present invention, were excellent in both ultrasonic attenuation and processability.

[0317] Furthermore, among backing material sheets No. 101 to 125 that satisfy the requirements of the present invention, even in the backing material sheets not containing hollow particles, both ultrasonic attenuation and processability are excellent, and the effects of the present invention are achieved.

[0318] The present invention has been described in conjunction with its embodiments, but unless otherwise specified, the invention is not intended to be limited to any of the details described, and should be interpreted broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

[0319] This application claims priority based on Japanese Patent Application No. 2023-052936 filed in Japan on March 29, 2023, the contents of which are hereby incorporated by reference as a part of the description in this specification.

[0320] Explanation of symbols

[0321] 1-Acoustic lens, 2-Acoustic matching layer, 3-Piezoelectric element layer, 4-Backing material, 7-Shell, 9-Cord, 10-Ultrasonic probe.

Claims

1. A backing material for an ultrasonic probe comprising thermally conductive particles and a resin. The resin includes any one of the following (A) to (C): (A) a reaction-cured product of an epoxy resin having a polyurethane structure and a polyamine compound; (B) a reaction-cured product of an epoxy resin and a polyamine compound, wherein the reaction-cured product has a polyether structure; and (C) a cured product of a reaction of a polyisocyanate compound and a polyamine compound, The resin has a loss tangent of 0.06 or more in the range of 0 to 50°C and a loss tangent of less than 1.50 in the range of -20 to 110°C. The storage modulus of the backing material in the range of 0 to 50° C. is above 1000 MPa. The content of the resin in the backing material is 25 to 50 volume %.

2. The backing material according to claim 1, wherein The thermally conductive particles include at least one of metal particles and ceramic particles. 3 . An ultrasonic probe comprising the backing material according to claim 1 . 4 . An ultrasonic diagnostic apparatus using the ultrasonic probe according to claim 3 .

5. A curable resin composition for forming the backing material according to claim 1 or 2, The curable resin composition includes the thermally conductive particles and any one of the following (a) to (c) as a resin component: (a) a combination of an epoxy resin having a polyurethane structure and a polyamine compound; (b) a combination of an epoxy resin and a polyamine compound, wherein At least one of the epoxy resin and the polyamine compound has a polyether structure; and (c) a combination of a polyisocyanate compound and a polyamine compound, The viscosity of the curable resin composition is 5000 Pa·s or less under the conditions of 25° C. and a shear rate of 0.01 / s.

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