JP2010232278A - Organic piezoelectric material and ultrasonic probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic piezoelectric material having a piezoelectric property and pyroelectricity, especially high in orientation and thermally stable, and an ultrasonic probe using the same. <P>SOLUTION: The organic piezoelectric material contains a compound containing at least one of a repetitive unit represented by a formula (1) with a glass transition temperature not lower than 100°C and not higher than 130°C. In the formula, Q represents a polymer main chain. A<SB>1</SB>represents an alkylene group and an oxyalkylene group, and A<SB>1</SB>, A<SB>2</SB>represent mesogen groups. Y represents a divalent linking group selected from among a urea group, a thiourea group, a urethane group, a thiourethane group, an amide group, a thioamide group, a carbonate group, a sulfonamide group, and a sulfondiamide group. Z represents a group selected from among a heterocyclic group, an aromatic group, and an aliphatic group of a carbon number 1-25. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic piezoelectric material and an ultrasonic probe, and more particularly to an organic piezoelectric material containing a compound having a mesogenic group and an ultrasonic probe using the organic piezoelectric material.

  Conventionally, acoustic devices such as microphones and speaker diaphragms, various thermal sensors, pressure sensors, measuring devices such as infrared detectors, ultrasonic probe, vibration that detects mutations such as genes and proteins with high sensitivity Organic piezoelectric materials having piezoelectricity and pyroelectricity that can be used to convert heat and mechanical stimulation into electrical energy, such as sensors, are known.

As the pyroelectric material, a so-called inorganic material in which a single crystal such as quartz, LiNbO ₃ , LiTaO ₃ , KNbO ₃ , a thin film such as ZnO or AlN, or a sintered body such as Pb (Zr, Ti) O ₃ is subjected to polarization treatment. Piezoelectric materials are widely used. However, these inorganic piezoelectric materials have characteristics such as high elastic stiffness, high mechanical loss coefficient, high density and high dielectric constant.

  On the other hand, organic piezoelectric materials such as polyvinylidene fluoride (hereinafter abbreviated as “PVDF”) and polycyanovinylidene (hereinafter abbreviated as “PVDCN”) have also been developed (for example, see Patent Document 1). This organic piezoelectric material is excellent in workability such as thin film and large area, can be made in any shape and shape, and has features such as low elastic modulus and low dielectric constant, so it can be used as a sensor. When considering the use of, it has a feature that enables highly sensitive detection. On the other hand, organic piezoelectric materials have low heat resistance and lose their pyroelectric properties at high temperatures, and the physical properties such as elastic stiffness are greatly reduced.

  In contrast to these limitations, polyurea resin compositions composed of urea bonds have a large dipole moment of urea bonds and are excellent in temperature characteristics as resins. Therefore, various studies have been made as organic piezoelectric materials. . For example, there is a so-called vapor deposition polymerization method in which a polyurea film is formed by simultaneously evaporating a diisocyanate compound such as 4,4′-diphenylmethane diisocyanate (MDI) and a diamine compound such as 4,4′-diaminodiphenylmethane (MDA). It is disclosed (for example, see Patent Documents 2 and 3). However, the polyurea resin composition prepared by the vapor deposition polymerization method described in these documents has a non-uniform molecular weight of the oligomer or high molecular weight product. In this state, the polyurea resin composition is formed. For this reason, the dipole moment of the urea bond cannot be fully utilized, and further improvement has been demanded as an organic piezoelectric material.

  There are reports that use a ferroelectric liquid crystal compound as a piezoelectric material (see, for example, Patent Documents 4 and 5). However, in the previous reports, the types of polarization groups in liquid crystal molecules are limited, and spontaneous polarization and piezoelectricity are known. However, no material satisfying the performance required as a piezoelectric material has been found yet.

JP-A-6-216422 JP-A-2-284485 Japanese Patent Laid-Open No. 5-31399 JP 7-115230 A Japanese Patent Laid-Open No. 8-254691

  The present invention has been made in view of the above-mentioned problems and circumstances, and the object thereof is an organic piezoelectric material having piezoelectricity and pyroelectricity that has excellent piezoelectric characteristics and can convert heat and mechanical stimulation into electrical energy. In particular, it is to provide an organic piezoelectric material having high orientation and being thermally stable, and an ultrasonic probe using the same.

The above object of the present invention can be achieved by the following configuration.
1. An organic piezoelectric material comprising a compound containing at least one repeating unit represented by the following general formula (1) and having a glass transition temperature of 100 ° C. or higher and 130 ° C. or lower.

[In the formula, Q represents a polymer main chain. A ₁ represents an alkylene group, an oxyalkylene group or a mesogenic group, and A ₂ represents a mesogenic group. Y represents a divalent linking group selected from a urea group, a thiourea group, a urethane group, a thiourethane group, an amide group, a thioamide group, a carbonate group, a sulfonamide group, and a sulfondiamide group. Z represents a group selected from an aliphatic group having 1 to 25 carbon atoms, an aromatic group, and a heterocyclic group. ]
2. Y in the general formula (1) is a urea group, a thiourea group, a thiourethane group, an amide group, a thioamide group, a sulfonamide group, or a sulfondiamide group, and an electromechanical coupling constant is 0.2 or more and 0.4 or less. 2. The organic piezoelectric material according to 1, wherein
3. 3. The organic piezoelectric material according to 1 or 2, wherein Z in the general formula (1) is a substituent containing an asymmetric carbon.
4). 4. The organic piezoelectric material according to any one of 1 to 3, comprising a compound represented by the general formula (1) and a low-molecular liquid crystal compound.
5). 5. The organic piezoelectric material according to 4, wherein the low-molecular liquid crystal compound is a compound represented by the following general formula (2).

[Wherein R ₂₁ represents an aliphatic group having 1 to 20 carbon atoms, and X represents a single bond or an oxygen atom. A ₂₁ represents a mesogenic group, and Z ₂ represents a group selected from an aliphatic group having 1 to 25 carbon atoms, an aromatic group, and a heterocyclic group. ]
6). 6. The organic piezoelectric material according to 5, wherein Z ₂ in the general formula (2) is a substituent containing an asymmetric carbon.
7). An ultrasonic probe comprising an ultrasonic transmission vibrator and an ultrasonic vibrator using the organic piezoelectric material according to any one of 1 to 6 as an ultrasonic reception vibrator. An ultrasonic probe.
An ultrasonic image detection apparatus comprising the ultrasonic probe according to 8.7.

  According to the present invention, an organic piezoelectric material having excellent piezoelectric properties and capable of converting heat and mechanical stimulation into electric energy and having piezoelectricity and pyroelectricity, in particular, has high orientation and is thermally stable. The material and the ultrasonic probe using the same could be provided.

It is a conceptual diagram which shows the structure of the principal part of an ultrasonic medical image diagnostic apparatus. It is a schematic cross section of an example of an ultrasonic probe.

  Next, the best mode for carrying out the present invention will be described, but the present invention is not limited thereto.

  The present invention can provide an organic piezoelectric material that is excellent in piezoelectricity and pyroelectricity and has improved conventional problems by using a compound containing at least one repeating unit represented by the general formula (1). In addition, the piezoelectric film of the present invention, which contains a compound containing at least one repeating unit represented by the general formula (1), has high orientation and is excellent only in piezoelectricity and pyroelectricity. However, since it is thermally stable, it can be effectively used as a highly versatile film.

<Compound containing at least one repeating unit represented by the general formula (1)>
In the general formula (1), Q represents a polymer main chain, and examples thereof include at least one selected from (Q-1) to (Q-11). Note that * represents the point of attachment to _{A 1.}

  Q is preferably (Q-1), (Q-2), (Q-5), (Q-6), or (Q-11), and more preferably (Q-1), (Q- 5) and (Q-11).

A ₁ represents an alkylene group or an oxyalkylene group. The A _1, when the alkylene group is preferably a linear or branched alkylene group having 1 to 10 carbon atoms, in the case of the oxyalkylene group, oxyethylene group, oxypropylene group, is oxybutylene group 1 Five linked groups are preferred.

A ₂ represents a mesogenic group. The mesogenic group in the present invention is a rigid unit essential for a compound exhibiting liquid crystallinity, and refers to a group in which two or more ring structures are connected directly or with a bonding group.

The mesogenic group represented by A ₂ is, for example, a group represented by the following formulas (A-1) to (A-49). In addition, the case where part of carbon in the benzene ring in the formula is replaced with nitrogen, halogen, or hydroxyl group is included.

(A-1) ~ in (A-49), _{A 1} and Y have the same meanings as _{A 1,} and Y in the general formula (1). W represents —COO—, —COS—, —CO—, —O—, —S—, —NHCONH—, —NHCSNH—, —CONH—, —NHCOO—, —NHCOS—, —SO ₂ —NH—, — NHSO ₂ NH— and —OCOO— are represented. A plurality of W in the same molecule may be the same or different.

  Preferred mesogenic groups are the following formulas (a-1) to (a-33).

  Y in the general formula (1) represents a divalent linking group selected from a urea group, a thiourea group, a urethane group, a thiourethane group, an amide group, a thioamide group, a carbonate group, a sulfonamide group, and a sulfonamide group.

  Y is preferably a urea group, a thiourea group, or a sulfone diamide group, and more preferably a thiourea group or a sulfone diamide group.

  Z in the general formula (1) represents a group selected from an aliphatic group, an aromatic group, and a heterocyclic group. The “aliphatic group” in the present specification represents a substituted or unsubstituted alkyl group, halogenated alkyl group, or cycloalkyl group. Specifically, an alkyl group having 1 to 25 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, cyclohexyl group, octyl group, decyl group, dodecyl group, octadecyl group) Groups), halogenated alkyl groups (trifluoromethyl group, perfluorooctyl group, etc.), and cycloalkyl groups (cyclohexyl group, cyclopentyl group, etc.).

  Specific examples of the aromatic group include a phenyl group and a naphthyl group. Specific examples of the heterocyclic group include a pyridyl group, a thiazolyl group, an oxazolyl group, an imidazolyl group, a furyl group, a pyrrolyl group, a pyrazinyl group, and a pyrimidinyl group. Group, pyridazinyl group, selenazolyl group, sriphoranyl group, piperidinyl group, pyrazolyl group, tetrazolyl group and the like.

  These groups are further substituted, for example, a halogen atom (chlorine atom, bromine atom, iodine atom, fluorine atom, etc.), alkoxy group (methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, (Hexyloxy group, cyclohexyloxy group etc.), aryloxy group (phenoxy group etc.), alkoxycarbonyl group (methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group etc.), aryloxycarbonyl group (phenyloxycarbonyl group etc.) ), Acyl group (acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propiyl) Aminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group (acetamide group, propionamide group, butanamide group, hexaneamide group, benzamide group, etc.), sulfonyl Group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino) Group, anilino group, 2-pyridylamino group, etc.), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group and the like.

  Z preferably represents a substituent containing an asymmetric carbon, and is not particularly limited as long as it is a substituent containing at least one asymmetric carbon. Preferably, the following general formula (3) or general formula ( It is a substituent represented by 4).

In the general formula (3), * represents an asymmetric carbon atom. R ₄₁ , R ₄₂ and R ₄₃ each represent a hydrogen atom or a substituent, but they are not the same group.

Examples of substituents represented by R ₄₁ , R ₄₂ and R ₄₃ include alkyl groups having 1 to 25 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group). Etc.), halogenated alkyl group (trifluoromethyl group, perfluorooctyl group etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group etc.), alkynyl group (propargyl group etc.), glycidyl group, acrylate group, methacrylate group, aromatic Group (phenyl group, etc.), heterocyclic group (pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, triphoranyl group, piperidinyl group, pyrazolyl group , Tetrazolyl group, etc.), halogen atom (chlorine atom, bromine source) , Iodine atom, fluorine atom, etc.), alkoxy group (methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group etc.), aryloxy group (phenoxy group etc.), alkoxy Carbonyl group (methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, etc.), aryloxycarbonyl group (phenyloxycarbonyl group, etc.), sulfonamide group (methanesulfonamide group, ethanesulfonamide group, butanesulfonamide group) Hexanesulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group) Group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, phenylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), urethane group (methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, phenylureido group, 2 -Pyridylureido group, etc.), acyl group (acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl) Group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group (acetamido group) Propionamide group, butanamide group, hexaneamide group, benzamide group, etc.), sulfonyl group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group ( Amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, anilino group, 2-pyridylamino group, etc.), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group, oxamoyl group, etc. Can do. Further, these groups may be further substituted with these groups.

R ₄₁ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group, an ethyl group, a trifluoromethyl group, or a halogen atom, and still more preferably a methyl group, a trifluoromethyl group, a fluorine atom. Is an atom. R ₄₂ is preferably a methyl group, ethyl group, isopropyl group, n-butyl group, tert-butyl group, hexyl group, octyl group, dodecyl group or the like. R ₄₃ is preferably a hydrogen atom.

In the general formula (4), * represents an asymmetric carbon atom. R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , and R ₅₅ each represent a hydrogen atom or a substituent, but R ₅₁ and R ₅₃ , and R ₅₂ , R _54, and R ₅₅ are not the same group. Examples of the substituent represented by R ₅₁ , R ₅₂ , R ₅₃ , R ₅₄ , R ₅₅ are specific examples of the substituent represented by R ₄₁ , R ₄₂ , R ₄₃ in the general formula (3). The substituents mentioned are mentioned.

R ₅₁ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group, an ethyl group, a trifluoromethyl group, or a halogen atom, still more preferably a methyl group, a trifluoromethyl group, or fluorine. Is an atom. R ₅₃ is preferably a hydrogen atom. R ₅₂ is preferably an alkyl group having 1 to 12 carbon atoms or a structure represented by the general formula (4). R ₅₄ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group, an ethyl group, a trifluoromethyl group, or a halogen atom, and still more preferably a methyl group, an ethyl group, or a trifluoro group. A methyl group and a fluorine atom. R ₅₅ is preferably a hydrogen atom or a fluorine atom.

  Specific examples of the polymer containing at least one repeating unit represented by the general formula (1) are given below, but the present invention is not limited to these.

  The compound represented by the general formula (1) can be synthesized by a known method. As specific synthesis examples, JP-A-2-124995, JP-A-2-232208, JP-A-5-132558, 5th edition Experimental Chemistry Vol. 14, Polymer Chemistry; It can be synthesized by referring to the method described on page 430 (Maruzen).

<Low molecular liquid crystal compounds>
Moreover, the organic piezoelectric material of the present invention preferably contains a compound containing one or more repeating units represented by the general formula (1) and a low-molecular liquid crystal compound.

  The low molecular liquid crystal compound in the present invention is defined as a compound different from a high molecular polymer generally called a high molecular liquid crystal, and preferably has a molecular weight of 100 to 1,000. The low molecular liquid crystal may be in any phase, but preferably has a nematic phase or a smectic phase.

  Specific examples of liquid crystalline compounds include the liquid crystals described in Chapter 3 of “Molecular Structure and Liquid Crystallinity” (Liquid Crystal Handbook Editorial Committee, Liquid Crystal Handbook, Maruzen, 2000), and “Liquid Crystal Device Handbook” ( And those described in pages 154 to 192 and pages 715 to 722 of the Japan Society for the Promotion of Science 142nd edition, Nikkan Kogyo Shimbun, 1989).

  In the present invention, the low molecular liquid crystal compound is preferably a ferroelectric molecular liquid crystal compound. Examples of ferroelectric low-molecular liquid crystal compounds include Schiff base ferroelectric liquid crystals, azo ferroelectric liquid crystals, azoxy ferroelectric liquid crystals, biphenyl ferroelectric liquid crystals, ester ferroelectric liquid crystals, or Examples thereof include a phenylpyrimidine-based ferroelectric liquid crystal, a ferroelectric low-molecular liquid crystal compound into which a ring substituent such as halogen or cyano group is introduced, and a ferroelectric low-molecular liquid crystal compound having a heterocyclic ring. Specific examples include compounds (1) to (13) described in paragraph Nos. 0024 to 0027 of JP-A-5-261180.

  These compounds are representative of low-molecular liquid crystal compounds, and low-molecular liquid crystal compounds that can be used in the present invention are not limited to these structures. Moreover, these low molecular liquid crystal compounds may be used individually by 1 type, and may use 2 or more types together.

<Compound represented by formula (2)>
The low molecular liquid crystal compound used in the present invention is more preferably a compound represented by the general formula (2).

In the general formula (2), R ₂₁ represents an aliphatic group having 1 to 20 carbon atoms. In the present specification, the aliphatic group means an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, or an aralkyl group, each of which is substituted or unsubstituted.

Specific examples of the aliphatic group represented by R ₂₁ include an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, and a cyclohexane having 5 to 10 carbon atoms. An alkenyl group, a C2-C20 alkynyl group, a C7-C20 aralkyl group, etc. are mentioned. These groups may have a substituent or a halogen atom at an arbitrary position. Specific examples of the substituent include an alkyl group, a cyano group, an alkoxy group, a hydroxy group, an amino group, a carboxyl group, a carbooxy group, Aromatic groups, heterocycles, aryloxy groups, acyloxy groups, carbamoyloxy groups, alkoxycarbonyloxy groups, and aryloxycarbonyloxy groups can be mentioned.

The aliphatic group represented by R ₂₁ is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 4 to 20 carbon atoms.

X represents a single bond or an oxygen atom. In the present invention, the single bond means that R ₂₁ and A ₂₁ are directly bonded.

A ₂₁ represents a mesogenic group. The mesogenic group represented by A ₂₁ has the same meaning as the mesogenic group represented by A ₂ in the general formula (1). (Including W, it is synonymous.)
Z ₂ represents a group selected from an alkyl group having 1 to 25 carbon atoms, a cycloalkyl group, an aromatic group, and a heterocyclic group. Examples of the alkyl group having 1 to 25 carbon atoms include (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, cyclohexyl group, octyl group, decyl group, dodecyl group, octadecyl group) Group), halogenated alkyl group (trifluoromethyl group, perfluorooctyl group etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group etc.), aromatic group (phenyl group, naphthyl group etc.), heterocyclic group (pyridyl group) Group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, sriphoranyl group, piperidinyl group, pyrazolyl group, tetrazolyl group and the like. These groups are further substituted with other substituents such as halogen atoms (chlorine atom, bromine atom, iodine atom, fluorine atom, etc.), alkoxy groups (methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy). Group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy group (phenoxy group etc.), alkoxycarbonyl group (methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group etc.), aryloxycarbonyl group (phenyloxycarbonyl) Group), acyl group (acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, Propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group (acetamide group, propionamide group, butanamide group, hexaneamide group, benzamide group, etc.) Sulfonyl group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (amino group, ethylamino group, dimethylamino group, butylamino group, A cyclopentylamino group, anilino group, 2-pyridylamino group, etc.), a cyano group, a nitro group, a sulfo group, a carboxyl group, a hydroxyl group and the like.

Z ₂ is preferably a substituent containing an asymmetric carbon. The substituent containing an asymmetric carbon represented by Z ₂ is not particularly limited as long as it is a group containing at least one asymmetric carbon, but preferably the following general formula (5) or general formula (6) It is a substituent represented by these.

In the general formula (5), * represents an asymmetric carbon atom. R ₆₁ , R ₆₂ and R ₆₃ each represent a hydrogen atom or a substituent, but each does not become the same group. Specific examples of the substituent represented by R ₆₁ , R ₆₂ and R ₆₃ include the substituents mentioned as examples of the substituent represented by R ₄₁ , R ₄₂ and R ₄₃ in the general formula (3). It is done.

R ₆₁ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group, an ethyl group, a trifluoromethyl group, or a halogen atom, and still more preferably a methyl group, a trifluoromethyl group, a fluorine atom. Is an atom. R ₆₂ is preferably a methyl group, ethyl group, isopropyl group, n-butyl group, tert-butyl group, hexyl group, octyl group, decyl group, dodecyl group, octadecyl group or the like. R is preferably a hydrogen atom.

In the general formula (6), * represents an asymmetric carbon atom. R ₇₁ , R ₇₂ , R ₇₃ , R ₇₄ and R ₇₅ each represent a hydrogen atom or a substituent, but R ₇₁ and R ₇₃ , and R ₇₂ , R ₇₄ and R ₇₅ are not the same group. Specific examples of the substituent represented by R ₇₁ , R ₇₂ , R ₇₃ , R ₇₄ and R ₇₅ are as examples of the substituent represented by R ₄₁ , R ₄₂ and R ₄₃ in the general formula (3). The substituents mentioned are mentioned.

R ₇₁ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group, an ethyl group, a trifluoromethyl group, or a halogen atom, still more preferably a methyl group, a trifluoromethyl group, or fluorine. Is an atom. R ₇₂ is preferably methyl, ethyl, isopropyl, n-butyl, tert-butyl, hexyl, octyl, decyl, dodecyl, octadecyl, or the like. R ₇₃ is preferably a hydrogen atom. R ₇₄ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group, an ethyl group, a trifluoromethyl group, or a halogen atom, and still more preferably a methyl group, an ethyl group, or a trifluoro group. A methyl group and a fluorine atom. R ₇₅ is preferably a hydrogen atom or a fluorine atom.

  The compound represented by the general formula (2) can be synthesized by a known method. For example, it can be synthesized by referring to the methods described in JP-A-61-47427, JP-A-5-119304 and the like.

  Specific examples of the compound represented by formula (2) are shown below, but the present invention is not limited thereto.

  In the present invention, the mixing ratio of the compound containing one or more repeating units represented by the general formula (1) and the low molecular liquid crystal compound or the compound represented by the general formula (2) is preferably general. The ratio of the low molecular liquid crystal compound or the compound represented by the general formula (2) to the compound containing one or more kinds of repeating units represented by the formula (1) is 0 to 50%, more preferably 0 to 30%. . If it is 50% or more, the film-forming property deteriorates and a problem arises in heat resistance.

<Organic piezoelectric material>
The organic piezoelectric material of the present invention is formed by forming a film containing a compound containing at least one repeating unit represented by the general formula (1) or by repeating the repeating unit represented by the general formula (1). An organic piezoelectric film is formed by forming a film containing a compound containing at least one compound and the compound represented by the general formula (2), or by further subjecting the general film to a polarization treatment. can do.

  In the organic piezoelectric film, when a stress is applied to the piezoelectric film, charges of opposite signs appear in proportion to both ends of the piezoelectric film, that is, an electric polarization phenomenon occurs, and conversely, the piezoelectric material is transmitted. It has the property (piezoelectric performance) that a distortion proportional to the occurrence of the electric field (applying an electric field) is generated. In particular, in the organic piezoelectric film made of the organic piezoelectric material of the present invention, the polarization due to orientation freezing of the dipole moment of the side chain of the compound containing at least one repeating unit represented by the general formula (1) is large. A piezoelectric effect occurs.

  On the other hand, when energy (heat) is applied to the piezoelectric film, the magnitude of spontaneous polarization in the piezoelectric film changes accordingly. At this time, the surface charge existing on the surface of the piezoelectric film so as to neutralize the spontaneous polarization cannot respond to the energy change as quickly as the spontaneous polarization. There is a charge corresponding to the change in spontaneous polarization. The generation of electricity associated with this energy change is called pyroelectricity. In particular, in the organic piezoelectric film made of the organic piezoelectric material of the present invention, polarization due to orientation freezing of the dipole moment of the main chain or side chain of the polymer Results in greater pyroelectric performance.

(Method of forming organic piezoelectric film)
The organic piezoelectric film is preferably formed by coating. Examples of the coating method include spin coating, solvent casting, melt casting, melt press, roll coating, flow coating, printing, dip coating, and bar coating.

  In the present invention, preferably, the compound represented by the general formula (1) is applied or formed in a temperature range in which the liquid crystal phase is exhibited or the compound represented by the general formula (2) is in a temperature range in which the liquid crystal phase is exhibited. It is preferable that the formed film may be further subjected to a polarization treatment described later.

(Polarization treatment)
As a polarization processing method in the polarization processing according to the present invention, various conventionally known methods can be applied.

  For example, in the case of the corona discharge treatment method, the corona discharge treatment can be performed by using a commercially available device comprising a high voltage power source and electrodes.

  Since the discharge conditions vary depending on the equipment and processing environment, it is preferable to select the conditions as appropriate. However, the voltage of the high voltage power source is −1 to −20 kV, the current is 1 to 80 mA, and the distance between the electrodes is 1 to 10 cm. The applied voltage is preferably 0.5 to 2.0 MV / m.

  As the electrodes, needle-like electrodes, linear electrodes (wire electrodes), and mesh-like electrodes that have been conventionally used are preferable, but the invention is not limited thereto.

  In addition, since heating is performed during corona discharge, it is necessary to install a heater via an insulator under the electrode in contact with the substrate manufactured according to the present invention.

  In the present invention, when the corona discharge treatment is performed as the polarization treatment in the state where the solvent of the coating solution remains, it is sufficient to remove the volatile components of the solvent in order to avoid the danger of flammable explosion. It is necessary for safety to carry out with ventilation.

(substrate)
As the substrate, the selection of the substrate differs depending on the application and use method of the organic piezoelectric film of the present invention. It may be a plastic plate or film such as polyimide, polyamide, polyimide amide, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polycarbonate resin, cycloolefin polymer. The surface may be covered with aluminum, gold, copper, magnesium, silicon or the like. A single crystal plate or film of aluminum, gold, copper, magnesium, silicon alone, or a rare earth halide may also be used.

Further, it may be formed on a multilayer piezoelectric element. As a method of using a multilayer for stacking piezoelectric elements, there is a method in which the organic piezoelectric film of the present invention is superposed on a ceramic piezoelectric element via an electrode. PZT is used as the ceramic piezoelectric element, but in recent years, one containing no lead has been recommended. PZT is preferably within the range of the formula of Pb (Zr _1-X Ti _X ) O ₃ (0.47 ≦ X ≦ 1). As deleading, natural or artificial quartz, lithium niobate (LiNbO ₃ ), potassium niobium tantalate [K (Ta, Nb) O ₃ ], barium titanate (BaTiO ₃ ), lithium tantalate (LiTaO ₃ ), or strontium titanate (SrTiO ₃ ). The composition of various ceramic materials can be selected as appropriate in terms of performance.

<Ultrasonic transducer>
The ultrasonic transducer according to the present invention is characterized by using an organic piezoelectric film formed using the organic piezoelectric material of the present invention. The ultrasonic transducer is preferably an ultrasonic receiving transducer used in an ultrasonic medical diagnostic imaging device probe including an ultrasonic transmitting transducer and an ultrasonic transmitting transducer. .

  In general, an ultrasonic vibrator has a pair of electrodes sandwiched between layers (or films) made of a film-like piezoelectric material (also referred to as “piezoelectric film”, “piezoelectric film”, or “piezoelectric layer”). An ultrasonic probe is configured by arranging a plurality of transducers, for example, one-dimensionally.

  Then, a predetermined number of transducers in the major axis direction in which a plurality of transducers are arranged is set as the aperture, and the plurality of transducers belonging to the aperture are driven to focus the ultrasonic beam on the measurement site in the subject. And has a function of receiving reflected echoes of ultrasonic waves emitted from the subject by a plurality of transducers belonging to the aperture and converting them into electrical signals.

  Hereinafter, each of the ultrasonic wave receiving transducer and the ultrasonic wave transmitting transducer according to the present invention will be described in detail.

<Ultrasound receiving transducer>
An ultrasonic receiving transducer according to the present invention is a transducer used in a probe for an ultrasonic medical image diagnostic apparatus, and is formed using the organic piezoelectric material of the present invention as a piezoelectric material constituting the transducer. An organic piezoelectric film is used.

The organic piezoelectric material or the organic piezoelectric film used for the ultrasonic receiving vibrator preferably has a relative dielectric constant of 10 to 50 at the thickness resonance frequency. The relative dielectric constant is adjusted by adjusting the number, composition, degree of polymerization, etc. of the polar functional groups such as the substituent R, CF ₂ group, and CN group of the compound constituting the organic piezoelectric material, and the polarization treatment described above. Can be done by.

<Transmitter for ultrasonic transmission>
The ultrasonic transmission vibrator according to the present invention is preferably made of a piezoelectric material having an appropriate relative dielectric constant in relation to the reception vibrator. Moreover, it is preferable to use a piezoelectric material excellent in heat resistance and voltage resistance.

  Various known organic piezoelectric materials and inorganic piezoelectric materials can be used as the ultrasonic transmitting vibrator constituent material.

  As the organic piezoelectric material, a polymer material similar to the above-described organic piezoelectric material for constituting an ultrasonic receiving vibrator can be used.

Inorganic materials include quartz, lithium niobate (LiNbO ₃ ), potassium tantalate niobate [K (Ta, Nb) O ₃ ], barium titanate (BaTiO ₃ ), lithium tantalate (LiTaO ₃ ), or titanate Lead zirconate (PZT), strontium titanate (SrTiO ₃ ), barium strontium titanate (BST), or the like can be used. PZT is preferably Pb (Zr _1-n Ti _n ) O ₃ (0.47 ≦ n ≦ 1).

<electrode>
The piezoelectric (body) vibrator according to the present invention is manufactured by forming electrodes on both surfaces or one surface of a piezoelectric film (layer) and polarizing the piezoelectric film. The electrode is formed using an electrode material mainly composed of gold (Au), platinum (Pt), silver (Ag), palladium (Pd), copper (Cu), nickel (Ni), tin (Sn), or the like. .

  In forming the electrode, first, a base metal such as titanium (Ti) or chromium (Cr) is formed to a thickness of 0.02 to 1.0 μm by a sputtering method, and then a metal mainly composed of the above metal elements and those A metal material made of the above alloy, and further, if necessary, a part of insulating material is formed to a thickness of 1 to 10 μm by sputtering or other suitable methods. In addition to sputtering, these electrodes can be formed by screen printing, dipping, or thermal spraying using a conductive paste in which fine metal powder and low-melting glass are mixed.

  Furthermore, a piezoelectric element is obtained by supplying a predetermined voltage between the electrodes formed on both surfaces of the piezoelectric film to polarize the piezoelectric film.

(Ultrasonic probe)
The ultrasonic probe according to the present invention is a probe for an ultrasonic diagnostic imaging apparatus including an ultrasonic transmission transducer and an ultrasonic reception transducer. The ultrasonic receiving vibrator according to the above is used.

  In the present invention, both transmission and reception of ultrasonic waves may be performed by a single transducer, but more preferably, the transducers are configured separately for transmission and reception in the probe.

  The piezoelectric material constituting the transmitting vibrator may be a conventionally known ceramic inorganic piezoelectric material or an organic piezoelectric material.

  In the ultrasonic probe according to the present invention, the ultrasonic receiving transducer of the present invention can be arranged on or in parallel with the transmitting transducer.

  As a more preferred embodiment, the structure for laminating the ultrasonic receiving transducer of the present invention on the ultrasonic transmitting transducer is good, and in this case, the ultrasonic receiving transducer of the present invention is another high-frequency transducer. You may laminate | stack on the vibrator | oscillator for transmission in the form joined together on the molecular material (The polymer (resin) film, for example, polyester film) whose relative dielectric constant is comparatively low as a support body. In this case, it is preferable that the film thickness of the receiving vibrator and the other polymer material be matched to a preferable receiving frequency band in terms of probe design. Considering a practical ultrasonic medical diagnostic imaging apparatus and biological information collection from a practical frequency band, the film thickness is preferably 40 to 150 μm.

  The probe may be provided with a backing layer, an acoustic matching layer, an acoustic lens, and the like. Also, a probe in which vibrators having a large number of piezoelectric materials are two-dimensionally arranged can be used. A plurality of two-dimensionally arranged probes can be sequentially scanned to form a scanner.

(Ultrasonic medical diagnostic imaging equipment)
The ultrasonic probe according to the present invention can be used for various types of ultrasonic diagnostic apparatuses. For example, it can be suitably used in an ultrasonic medical image diagnostic apparatus as shown in FIG.

  FIG. 1 is a conceptual diagram showing a configuration of a main part of an ultrasonic medical image diagnostic apparatus according to an embodiment of the present invention. This ultrasonic medical diagnostic imaging apparatus transmits an ultrasonic wave to a subject such as a patient, and an ultrasonic probe in which piezoelectric vibrators that receive ultrasonic waves reflected by the subject as echo signals are arranged. (Probe). In addition, an electric signal is supplied to the ultrasonic probe to generate an ultrasonic wave, and a transmission / reception circuit that receives an echo signal received by each piezoelectric vibrator of the ultrasonic probe, and transmission / reception control of the transmission / reception circuit A transmission / reception control circuit is provided.

  Furthermore, an image data conversion circuit that converts echo signals received by the transmission / reception circuit into ultrasonic image data of the subject is provided. Further, a display control circuit for controlling and displaying the monitor with the ultrasonic image data converted by the image data conversion circuit and a control circuit for controlling the entire ultrasonic medical image diagnostic apparatus are provided.

  A transmission / reception control circuit, an image data conversion circuit, and a display control circuit are connected to the control circuit, and the control circuit controls operations of these units. Then, an electrical signal is applied to each piezoelectric vibrator of the ultrasonic probe to transmit an ultrasonic wave to the subject, and the reflected wave caused by acoustic impedance mismatch inside the subject is detected by the ultrasonic probe. Receive at.

  The transmission / reception circuit corresponds to “means for generating an electrical signal”, and the image data conversion circuit corresponds to “image processing means”.

  According to the ultrasonic diagnostic apparatus as described above, by utilizing the characteristics of the ultrasonic receiving vibrator excellent in piezoelectric characteristics and heat resistance of the present invention and suitable for high frequency and wide band, the image quality and its An ultrasonic image with improved reproduction and stability can be obtained.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to these.

Example 1
(Production of organic piezoelectric film)
The compound represented by the general formula (1) shown in Table 1 or the low molecular weight compound and the compound represented by the general formula (2) shown in Table 1 on a 25 μm polyimide film on which aluminum has been vapor-deposited in advance is subjected to a dry film pressure. Was applied to a thickness of 7 μm and dried to obtain organic piezoelectric film-1 to organic piezoelectric film-20.

  In the same manner, Comparative Organic Piezoelectric Films A to C were produced using Comparative-A, Comparative-B, and Comparative-C shown below instead of the compound represented by the general formula (1).

(Evaluation of organic piezoelectric film)
The obtained organic piezoelectric film was evaluated for piezoelectric characteristics while being heated to room temperature and 100 ° C. by a resonance method. The results are shown in Table 1. In addition, a piezoelectric characteristic is shown as a relative value with the value measured at room temperature for the comparative organic piezoelectric film-A as 100%.

  In Table 1, the percentage display of the low molecular liquid crystal compound or the compound represented by the general formula (2) is a low molecular liquid crystal compound or a compound containing at least one repeating unit represented by the general formula (1). The mass% of the compound represented by General formula (2) is represented.

  As is apparent from the results shown in Table 1, it can be seen that the piezoelectric characteristics of the organic piezoelectric film formed by the compound of the present invention are superior to those of the comparative example.

Example 2
(Preparation and evaluation of ultrasonic probe)
<Preparation of ultrasonic transducer for transmission>
Component raw materials CaCO ₃ , La ₂ O ₃ , Bi ₂ O ₃ and TiO ₂ , and subcomponent raw materials MnO are prepared, and for the component raw materials, the final composition of the components is (Ca _0.97 La _0.03 ) Weighed to be Bi _4.01 Ti ₄ O ₁₅ .

  Next, pure water was added, mixed in a ball mill containing zirconia media in pure water for 8 hours, and sufficiently dried to obtain a mixed powder. The obtained mixed powder was temporarily molded and calcined in air at 800 ° C. for 2 hours to prepare a calcined product.

  Next, pure water was added to the obtained calcined material, finely pulverized in a ball mill containing zirconia media in pure water, and dried to prepare a piezoelectric ceramic raw material powder. In the fine pulverization, the piezoelectric ceramic raw material powder having a particle diameter of 100 nm was obtained by changing the pulverization time and pulverization conditions.

  6% by mass of pure water as a binder is added to each piezoelectric ceramic raw material powder having a different particle diameter, press-molded to form a plate-shaped temporary molded body having a thickness of 100 μm, and this plate-shaped temporary molded body is vacuum-packed and then 235 MPa. It shape | molded by the press with the pressure of.

  Next, the molded body was fired.

  The final sintered body had a thickness of 20 μm.

  The firing temperature was 1100 ° C. An electric field of 1.5 × Ec (MV / m) or more was applied for 1 minute to perform polarization treatment.

<Production of ultrasonic transducer for reception>
A piezoelectric material 1 was produced by bonding the organic piezoelectric film-1 produced in Example 1 and a polyester film having a thickness of 50 μm with an epoxy adhesive.

  Thereafter, electrodes were provided in the same manner as described above, and polarization treatment was performed, so that the receiving ultrasonic transducer 1 was manufactured.

  In the same manner for the other organic piezoelectric films 2 to 20 and the comparative organic piezoelectric films A to C, the receiving ultrasonic transducers 2 to 20 and the comparative receiving ultrasonic transducers A to C were produced.

(Ultrasonic probe)
Next, according to a conventional method, a substrate is provided on the transmission ultrasonic transducer, the reception ultrasonic transducer is laminated on the substrate, and a backing layer and an acoustic matching layer are installed as shown in FIG. Then, an ultrasonic probe 1 was produced.

  Similarly, ultrasonic probes 2 to 20 and comparative ultrasonic probes A to C were prepared using the other organic piezoelectric films 2 to 20 and the comparative piezoelectric films A to C.

  An ultrasonic image detection apparatus having the configuration shown in FIG. 2 incorporating these ultrasonic probes 1 to 20 and comparative ultrasonic probes A to C was produced.

(Reception sensitivity evaluation)
The reception sensitivity was measured as follows.

  For the measurement of the reception sensitivity, when the reception sensitivity immediately after driving each of the ultrasonic probes 1 to 20 is 100, the relative reception sensitivity after driving for 30 minutes was evaluated. When the relative sensitivity was 97% or more of the reference, evaluation was evaluated as ◯, 95% or more and less than 97% as Δ, and less than 95% as ×.

As a condition for receiving sensitivity, a fundamental frequency f _{1 of} 5 MHz is transmitted, and a receiving relative sensitivity of 10 MHz as a receiving second harmonic f ₂ , 15 MHz as a third harmonic, and 20 MHz as a fourth harmonic is obtained. Receiving sensitivity.

  For the relative sensitivity of reception, a sound intensity measurement system Model 805 (1 to 50 MHz) manufactured by Sonora Medical System, Inc. (2021 Miller Drive Longmont, Colorado (0501 USA)) was used.

  The obtained results are shown in Table 1 above.

  From the above results, it can be seen that the ultrasonic probe provided with the ultrasonic transducer of the present invention is an organic piezoelectric material having high reception sensitivity characteristics, high orientation and thermal stability. .

DESCRIPTION OF SYMBOLS 1 Organic piezoelectric material 2 Electrode 5 Transmission piezoelectric material 6 Backing layer 7 Substrate 8 Acoustic matching layer 9 Acoustic lens 10 Ultrasonic transducer 11 Receiving organic piezoelectric material 12 Transmitting ultrasonic transducer 13 Receiving ultrasonic transducer 20 Super Acoustic probe

Claims (8)

An organic piezoelectric material comprising a compound containing at least one repeating unit represented by the following general formula (1) and having a glass transition temperature of 100 ° C. or higher and 130 ° C. or lower.

[In the formula, Q represents a polymer main chain. A ₁ represents an alkylene group, an oxyalkylene group or a mesogenic group, and A ₂ represents a mesogenic group. Y represents a divalent linking group selected from a urea group, a thiourea group, a urethane group, a thiourethane group, an amide group, a thioamide group, a carbonate group, a sulfonamide group, and a sulfondiamide group. Z represents a group selected from an aliphatic group having 1 to 25 carbon atoms, an aromatic group, and a heterocyclic group. ] Y in the general formula (1) is a urea group, a thiourea group, a thiourethane group, an amide group, a thioamide group, a sulfonamide group, or a sulfondiamide group, and an electromechanical coupling constant is 0.2 or more and 0.4 or less. The organic piezoelectric material according to claim 1, wherein: The organic piezoelectric material according to claim 1 or 2, wherein Z in the general formula (1) is a substituent containing an asymmetric carbon. The organic piezoelectric material according to claim 1, comprising a compound represented by the general formula (1) and a low-molecular liquid crystal compound. The organic piezoelectric material according to claim 4, wherein the low-molecular liquid crystal compound is a compound represented by the following general formula (2).

[Wherein R ₂₁ represents an aliphatic group having 1 to 20 carbon atoms, and X represents a single bond or an oxygen atom. A ₂₁ represents a mesogenic group, and Z ₂ represents a group selected from an aliphatic group having 1 to 25 carbon atoms, an aromatic group, and a heterocyclic group. ] The organic piezoelectric material according to claim 5, wherein Z ₂ in the general formula (2) is a substituent containing an asymmetric carbon. An ultrasonic probe including an ultrasonic transmission transducer and an ultrasonic transducer using the organic piezoelectric material according to any one of claims 1 to 6 as an ultrasonic reception transducer. Characteristic ultrasonic probe. An ultrasonic image detection apparatus comprising the ultrasonic probe according to claim 7.

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