JP2003282983A - Polyurethane elastomer piezoelectric element, pressure- sensitive sensor and contact sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric element composed of a polyurethane elastomer, and a pressure-sensitive sensor and a contact sensor which have the piezoelectric element. <P>SOLUTION: This polyurethane elastomer piezoelectric element is characterized in that the polyurethane elastomer into which a fullerenol is introduced is installed. It may be possible that polyurethane elastomer into which the fullerenol is introduced has a film type form. The pressure-sensitive sensor and the contact sensor are characterized in that the polyurethane elastomer piezoelectric element is used as a piezoelectric element. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane elastomer piezoelectric element utilizing the piezoelectric effect of a fullerenol-introduced polyurethane elastomer, a pressure-sensitive sensor and a contact sensor.

[0002]

2. Description of the Related Art Conventionally, a polyurethane elastomer actuator based on the electrostrictive effect has been characterized not by a driving method in a solvent but by driving in the atmosphere by applying an electric field. Further, an actuator using a ceramic or a polymer material is used. In contrast to the high driving voltage of several tens of kV, the polyurethane elastomer actuator has a large bending displacement at a relatively low voltage of several kV.

However, from the viewpoint of practical use, the polyurethane elastomer actuator needs to be driven at a low voltage of 1 kV or less like a polymer gel actuator or a mechanochemical element using a conductive polymer. Becomes

However, such an actuator mechanism of a polyurethane elastomer is caused by an electrostrictive effect based on voltage application, and so far, a piezoelectric effect which is integrated with the electrostrictive effect has been developed in the polyurethane elastomer. There was nothing. Therefore, a piezoelectric element made of polyurethane elastomer has not been developed.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a piezoelectric element composed of polyurethane elastomer. Another object of the present invention is to provide a pressure sensor and a contact sensor having a piezoelectric element composed of polyurethane elastomer.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that polyurethane elastomers in which fullerenol is used as a curing agent are introduced into polyurethane elastomers that can be deformed by electric field orientation. The present invention has been completed, and it was found that the film composed of can exhibit a piezoelectric effect, and that a piezoelectric element composed of a polyurethane elastomer can be effectively used as a piezoelectric element.

That is, the present invention is a polyurethane elastomer piezoelectric element characterized by being composed of a polyurethane elastomer into which fullerenol has been introduced. The polyurethane elastomer piezoelectric element may be a film or sheet composed of a polyurethane elastomer into which fullerenol has been introduced.

The present invention also provides a pressure-sensitive sensor and a contact sensor, wherein the above-mentioned polyurethane elastomer piezoelectric element is used as the piezoelectric element.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION [Polyurethane Elastomer Piezoelectric Element] The polyurethane elastomer piezoelectric element of the present invention comprises:
It is formed by a fullerenol-introduced polyurethane elastomer in which fullerenol is introduced into a polyurethane elastomer that can be deformed by electric field orientation. Therefore, in the polyurethane elastomer piezoelectric element, an electric potential is developed on the surface by the action of pressure such as pressurization and stretching, and the piezoelectric effect can be exhibited. This is because the fullerenol has a hydroxyl group formed in a star shape,
It is considered that the polymer chains constituting the polyurethane elastomer are sterically (three-dimensionally) cross-linked by the star-shaped hydroxyl groups to increase the tensile strength. Specifically, by introducing fullerenol into the polyurethane elastomer, the crosslinking of the polyurethane elastomer is promoted, the density of the three-dimensional network structure is increased, and the interaction between the molecular chains of the polyurethane elastomer is strengthened. It is considered that due to the conformational change of the molecular chain with respect to pressure, orientation accompanied by order occurs, and as a result, the piezoelectric effect is exhibited.

Examples of polyurethane elastomers containing fullerenol include, for example, Japanese Patent No. 3026066.
JP-A-7-240544 and JP-A-8-3
35726, JP-A-2000-101159, JP-A-2000-101160, and JP-A-2000.
-49397 gazette etc. using polyisocyanate (especially organic polyisocyanate) as a raw material of a polyurethane elastomer, a polyol (especially high molecular weight polyol), and a chain extender as needed, and using fullerenol as a hardening agent. It can be prepared by Specifically, for the polyurethane elastomer, for example, a method in which a polyisocyanate and a polyol are reacted by a conventionally known method and then a chain extender or the like is reacted therewith, or the above-mentioned components (polyisocyanate, polyol, chain extension) are used. It can be prepared by preparing a urethane prepolymer by a so-called one-shot method in which agents and the like) are simultaneously reacted in a predetermined ratio, and then adding fullerenol to carry out a reaction (particularly a curing reaction).

In the urethane prepolymer, the ratio of polyisocyanate to polyol (NCO / OH) is
It is preferably in the range of 1.5 to 9 (molar ratio).

(Polyisocyanate) The polyisocyanate may be one having two or more isocyanate groups in the molecule, and examples thereof include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate and 2,4. , 4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate, 1,
3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1-methyl-2,4-cyclohexane diisocyanate, 1-methyl-2,6- Cyclohexane diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, m-phenylene diisocyanate, p-phenylene diisocyanate, 1,5
-Naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-
Toluidine diisocyanate, dianidine diisocyanate, 4,4′-diphenyl ether diisocyanate, 1,3-xylylene diisocyanate, ω, ω′-
Diisocyanate-1,4-diethylbenzene, polymethylene polyfernyl polyisocyanate, and isocyanurate-modified products of these polyisocyanates,
Examples include carbodiimide-modified products and burette-modified products. The polyisocyanates may be used alone or in combination of two or more.

As the (polyol) polyol, polymer polyols such as polyester-based polyols, polyether-based polyols, polycarbonate-based polyols and polybutadiene-based polyols can be preferably used. The polyols may be used alone or in combination of two or more. In addition, as the polymer polyol,
It is also possible to use a polymer polyol obtained by appropriately blending these exemplified polymer polyols with a polyolefin polyol.
The polyols may be used alone or in combination of two or more.

The polyester-based polyol is, for example, a condensate of polycarboxylic acid and low-molecular polyol,
Some have a weight average molecular weight of 500 to 10,000. Specifically, poly (ethylene adipate) (“PEA”),
Poly (diethylene adipate) (“PDA”), Poly (propylene adipate) (“PPA”), Poly (tetramethylene adipate) (“PBA”), Poly (hexamethylene adipate) (“PHA”), Poly (neopene pliers) Renadipate) (“PNA”), 3-methyl-1,
Polyol consisting of 5-pentanediol and adipic acid, random copolymer of PEA and PDA, PEA and PP
A random copolymer of A, a random copolymer of PEA and PBA, a random copolymer of PHA and PNA, or a caprolactone polyol obtained by ring-opening polymerization of ε-caprolactone, β-methyl-δ-valerolactone is ethylene. Polyol and the like obtained by ring-opening with glycol (all of these have a weight average molecular weight of 500 to 100).
00 is preferable). Each component (polycarboxylic acid, low molecular weight polyol, etc.) for preparing the polyester-based polyol can be used alone or in combination. Further, examples of the polyester-based polyol include a copolymer of at least one acid component of the following acid components and at least one glycol component of the glycol components.

Acid component: terephthalic acid, isophthalic acid, phthalic anhydride, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecane diacid, dimer acid (mixture), paraoxybenzoic acid, trimellitic acid anhydride, ε-caprolactone , Β-methyl-δ valerolactone.

Glycol component: ethylene glycol, propylene glycol, 1,4-butanediol, 1,5
-Pentanediol, 1,6-hexanediol, 2,
2-dimethyl-1,3-propanediol, 1,9-nonanediol, methyloctanediol, neopentyl glycol, polyethylene glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol, pentaerythritol, 3-methyl-1. , 5-pentanediol.

As the polyether polyol, for example, an alkylene oxide (eg, ethylene oxide, propylene oxide, etc.) can be obtained by ring-opening addition polymerization using a polyhydric alcohol (eg, diethylene glycol) which is an active hydrogen compound as an initiator. it can. Specifically, polyether-based polyols include, for example, polytetramethylene glycol (“PTMG”), polypropylene glycol (“PPG”), polyethylene glycol (“PEG”), polyoxymethylene, propylene oxide and ethylene oxide. And copolymers thereof are included. Further, the polyether polyol may be one prepared by cationic polymerization of tetrahydrofuran and having a weight average molecular weight of 500 to 5,000.
Specifically, polytetramethylene ether glycol (“PTMG”), which is a homopolymer of tetrahydrofuran.
Examples of tetrahydrofuran include copolymers with alkylene oxides (for example, copolymers of tetrahydrofuran and propylene oxide, copolymers of tetrahydrofuran and ethylene oxide, etc.). The weight average molecular weight of each of these polyether polyols is preferably 500 to 10,000. Each component (such as alkylene oxide) for preparing the polyether polyol can be used alone or in combination.

As the polycarbonate-based polyol,
Conventionally known polyol (polyhydric alcohol) and phosgene,
Obtained by condensation with chloroformic acid ester, dialkyl carbonate or diallyl carbonate, various molecular weights are known. Particularly preferred as such a polycarbonate-based polyol is one using 1,6-hexanediol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, or 1,5-pentanediol as the polyol. And its weight average molecular weight is in the range of about 500 to 10,000. Examples of the polycarbonate-based polyol include poly (hexanediol carbonate),
Examples thereof include poly (nonane diol carbonate). Each component for preparing the polycarbonate-based polyol can be used alone or in combination.

As the polybutadiene-based polyol, a hydroxyl group-containing liquid diene-based polymer can be used. As the hydroxyl group-containing liquid diene polymer, weight average molecular weight: 600 to 3000, average number of hydroxyl groups (number of functional groups):
It is preferably 1.7 to 3.0, for example, having 4 to 4 carbon atoms.
Polymers or copolymers of 12 diene components, and further copolymers of these diene components (monomers) with copolymerizable monomers (for example, α-olefin addition polymerization monomers having 2 to 22 carbon atoms) The butadiene-based polymer may be modified to have a hydroxyl group at the terminal.
Specifically, as the polybutadiene-based polyol, butadiene homopolymer, isoprene homopolymer, butadiene-styrene copolymer, butadiene-isoprene copolymer, butadiene-acrylonitrile copolymer, butadiene-2-ethylhexyl acrylate copolymer, butadiene-n-octadecyl acrylate copolymer, etc. Examples of the butadiene-based polymer of 1 are modified with a hydroxyl group at the terminal. Of these hydroxyl group-containing liquid diene polymers, the liquid diene polymer can be produced, for example, by reacting a conjugated diene monomer in a liquid reaction medium by heating in the presence of hydrogen peroxide.

As the polyol as a raw material of the polyurethane elastomer, a polyolefin polyol obtained by hydrogenating the liquid hydroxyl group-containing liquid diene polymer (saturated double bond) may be used.

(Chain extender) As a chain extender, any chain extender may be used, as long as it is used, and it is generally used when extending the chain of the urethane prepolymer. Examples of the chain extender include low molecular weight polyol compounds and polyamine compounds. The chain extender may be used alone or in combination of two or more. As the low molecular weight polyol compound as a chain extender, primary polyol, secondary polyol, 3
Any of the class polyols may be used, but the diols are preferred. Specifically, low molecular weight polyol compounds include trimethylolpropane (“TMP”), ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Hexanediol, propylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-pentanediol, 2,3-pentanediol, 2,5-hexane Diol, 2,4-hexanediol, 2-ethyl-
1,3-hexanediol, cyclohexanediol,
2-ethyl-2- (hydroxymethyl) -1,3-propanediol and the like can be mentioned. Further, as the polyamine compound, diamine, triamine, tetraamine, etc., 1
Any of primary amine, secondary amine, and tertiary amine can be used. Specifically, as the polyamine compound, an aliphatic amine such as hexamethylenediamine,
Alicyclic amines such as 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 4,4'-methylenebis-2-chloroaniline, 2,2 ', 3,3'-tetrachloro-4,4 ′ -Diaminophenylmethane, 4,4′-
Examples include aromatic amines such as diaminodiphenyl, 2,4,6-tris (dimethylaminomethyl) phenol, and the like. As the chain extender, low molecular weight polyol compounds (particularly diols) are suitable.

In the present invention, as a method for mixing the urethane prepolymer and the chain extender to extend the chain of the urethane prepolymer, the mixing ratio of the chain extender to the urethane prepolymer, the reaction temperature, It can be carried out by a known method including the reaction time and the like.

(Fullerenol) Fullerenol
ol) is a fullerene (C ₆₀ ) into which a hydroxyl group has been introduced, and the hydroxyl group is usually introduced into the fullerene in a star-like form. The number of hydroxyl groups in fullerenol is not particularly limited, but is preferably 2 or more (for example, 2 to 20) per molecule. In the present invention, the fullerenol is 1
It preferably has 5 to 18 hydroxyl groups per molecule, and more preferably 8 to 15 (particularly 10 to 1).
It is preferable to have the hydroxyl group of 2).
The site in which the hydroxyl group is introduced in fullerene is not particularly limited.

The fullerenol can be used alone or in combination of two or more kinds.

Such fullerenol is obtained, for example, by adding sulfuric acid (especially fuming sulfuric acid) to fullerene to carry out a sulfonation reaction to obtain a sulfonated fullerene, and further hydrolyzing the sulfonated fullerene. It can be prepared. Specifically, in the sulfonation reaction, the ratio of fullerene to fuming sulfuric acid can be selected from the range of about 15 ml of fuming sulfuric acid to 1 g of fullerene. The sulfonation reaction time is 1
~ 4 weeks can be selected. On the other hand, the hydrolysis reaction time can be selected from the range of 1 to 3 days.

(Additive) The polyurethane elastomer is
It may contain various additives and the like. Examples of such additives include plasticizers, flame retardants, fillers, stabilizers,
Colorants and the like can be mentioned. As the plasticizer, a nonionic plasticizer is preferable. Specifically, examples of the plasticizer include dioctyl phthalate (“DOP”), dibutyl phthalate (“DBP”), dioctyl adipate (“DO”).
A "), triethylene glycol dibenzoate, tricresyl phosphate, dioctyl phthalate, fatty acid ester of pentaerythritol, dioctyl sebacate,
Diisooctyl azelate, dibutoxyethoxyethyl adipate and the like can be used.

[Fullerenol-Introduced Polyurethane Elastomer] In the present invention, it is sufficient that fullerenol is introduced into the polyurethane elastomer. For example, fullerenol can be introduced into the polyurethane elastomer by using it as a curing agent. That is, as described above, the urethane prepolymer can be reacted with fullerenol to prepare a fullerenol-introduced polyurethane elastomer. The proportion of fullerenol is 0.05 to 2% by weight (preferably 0.08 to 1% by weight, more preferably 0.1%) based on the total amount of urethane prepolymer (solid content).
˜0.5 wt%). Even if the proportion of fullerenol is less than 0.05% by weight based on the total amount of urethane prepolymer (solid content), it is 2
Even if it exceeds the weight%, the piezoelectricity is lowered.

The fullerenol-introduced polyurethane elastomer may be used alone or in combination of two or more kinds.

The method for producing the fullerenol-introduced polyurethane elastomer by reacting the urethane prepolymer with fullerenol is not particularly limited, and for example, a mixture of the urethane prepolymer and fullerenol is heated to give the urethane prepolymer. And a fullerenol are reacted with each other. The reaction temperature is, for example, 80 to 150.
It can be selected from the range of about 0 ° C (preferably 85 to 100 ° C). The reaction time is, for example, 3
It can be selected from the range of about 0 minutes to 2 hours (preferably 1 hour 30 minutes to 2 hours).

In the present invention, as the curing agent, a curing agent known or commonly used as a curing agent for polyurethane or polyurethane elastomer can be used together with the fullerenol. As such a known or commonly used curing agent, a low molecular weight polyol compound, polyamine compound or the like exemplified in the section of the chain extender can be used.

[Method for Manufacturing Piezoelectric Element] The method for manufacturing the polyurethane elastomer piezoelectric element of the present invention (that is, the polyurethane elastomer piezoelectric element having the fullerenol-introduced polyurethane elastomer) is not particularly limited. When it has a film shape, a sheet shape or a thin film shape, it can be produced by molding the fullerenol-introduced polyurethane elastomer into a film shape, a sheet shape or a thin film shape. That is, a polyurethane elastomer piezoelectric element composed of the fullerenol-introduced polyurethane elastomer of the present invention (may be referred to as "fullerenol-introduced polyurethane elastomer piezoelectric element") is in a film form or a sheet form (particularly in a film form).
Alternatively, it may be in the form of a thin film.

Specifically, when the fullerenol-introduced polyurethane elastomer is formed into a film, a sheet, or a thin film (for example, a thickness of about 0.01 to 1 mm), a mold release agent is used in this molding method. If so, the mold release agent can be removed after molding. The removal of the mold release agent of the molded polyurethane elastomer is sufficient by the usual wet cleaning, but for example, as surface modification for applying electrodes, ion treatment such as plasma treatment by glow discharge or corona discharge treatment is performed. -It is preferable to remove impurities such as a release agent using electrons and ultraviolet rays.

Electrodes (thickness: about 0.05 to 10 μm) may be formed on one or both sides of the piezoelectric element made of the fullerenol-introduced polyurethane elastomer. Examples of the material of the electrode include gold, platinum, aluminum,
Indium metal, indium oxide, stannic oxide, IT
In addition to metal compounds such as O and silver and metal compounds such as alloys, conductive resins such as polyaniline and elastomer rubber, carbon, and the like can be used. Further, a conductive resin or conductive elastomer in which a metal compound such as gold or platinum is dispersed in a resin can also be used. Examples of the method for forming the electrode include an ion plating method and plasma CVD.
A method, an ion sputter coating method, a vacuum vapor deposition method, a screen printing, an ion beam assist method, an ionization vapor deposition method and the like can be adopted.

[Pressure Sensitive Sensor, Contact Sensor, etc.] In the fullerenol-introduced polyurethane elastomer piezoelectric element of the present invention, piezoelectricity is exhibited by pressurization and stretching, and the piezoelectric effect is effectively exhibited. Therefore, the fullerenol-introduced polyurethane elastomer piezoelectric element of the present invention can be suitably used as a piezoelectric element in various sensors such as a pressure sensor and a contact sensor.

As the pressure sensor or the contact sensor, for example, as shown in FIG. 4, the row electrode side sheet-like base material 2 having the row electrodes 21 and the pressure sensitive conductive layer 22 for the row electrodes is used.
And the column-electrode-side sheet-like substrate 3 having the column electrode 31 and the column-electrode pressure-sensitive conductive layer 32, each sheet-like substrate (2,
The surface of the pressure-sensitive conductive layer (22, 32) formed in 3) may be laminated so that the surfaces thereof face each other. Specifically, the row electrode-side sheet-shaped base material 2 having the row electrodes 21 and the row electrode pressure-sensitive conductive layer 22 is printed on the row electrode-side sheet-shaped base material 2 at regular intervals. It can be prepared by forming the row electrode pressure-sensitive conductive layer 22 by applying a fullerenol-introduced polyurethane elastomer by printing or the like so as to surround the row electrode 21. Also, the column electrode 3
The column-electrode-side sheet-shaped substrate 3 having the 1 and column-electrode pressure-sensitive conductive layers 32 is formed by forming the column electrodes 31 on the column-electrode-side sheet-shaped substrate 3 at regular pitch intervals by printing or vapor deposition. Further, it can be produced by applying a fullerenol-introduced polyurethane elastomer by printing or the like so as to surround the column electrodes 31 to form the column electrode pressure-sensitive conductive layer 32.

When the pressure sensitive conductive layer 22 for the row electrodes and the pressure sensitive conductive layer 32 for the column electrodes are formed by printing with the fullerenol-introduced polyurethane elastomer, various printing methods (for example, a screen printing method) are adopted. be able to. Of course, when the row electrode pressure-sensitive conductive layer 22 and the column electrode pressure-sensitive conductive layer 32 are formed from the fullerenol-introduced polyurethane elastomer, any method other than printing can be used as long as it can form various patterns. Any method (for example, a vapor deposition method) can be adopted.

The pressure-sensitive conductive layer 2 for the row electrode is thus formed.
Since the pressure-sensitive conductive layer 32 for 2 and column electrodes can be formed by printing a fullerenol-introduced polyurethane elastomer, it can be formed not only on a flat surface but also on a curved surface that is three-dimensionally bent. Therefore, the sensor of the pressure sensor or the contact sensor of the present invention can be formed not only in the form of a line or a plane, but also in the form of a curved surface curved three-dimensionally. Therefore, the sensor of the pressure-sensitive sensor or the contact sensor of the present invention can be used by being attached to, for example, a portion having a curved shape curved three-dimensionally in the arm (arm) of the robot.

The pressure-sensitive sensor and contact sensor of the present invention can also be used as a pressure distribution sensor for detecting pressure distribution.

[0039]

According to the polyurethane elastomer piezoelectric element of the present invention, the piezoelectric effect can be effectively exhibited even if the polyurethane elastomer is used. Therefore, the polyurethane elastomer piezoelectric element is extremely useful as a piezoelectric element in a pressure sensor and a contact sensor.

[0040]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Preparation Example 1 of Fullerenol Fullerene 3
g and 45 ml of fuming sulfuric acid are mixed and stirred at 67 ° C. for 1 to 4 weeks to carry out a sulfonation reaction, further, distilled water is added, and stirred at 85 ° C. for 3 days to carry out a hydrolysis reaction. To prepare fullerenol.

(Example 1) Poly-3 methyl-1,5-pentane adipate polyol having an average molecular weight of 2,945 (PMPA, manufactured by Kuraray Co., Ltd., trade name "Kurapol P"
3010 "), and 10.8 parts by weight of paraphenylene diisocyanate (PPDI, manufactured by DuPont, trade name" HIREN ") to 100 parts by weight, and under a nitrogen stream,
The reaction was carried out at 5 ° C for 2 hours to obtain a urethane prepolymer having a terminal isocyanate group.

The fullerenol obtained in Preparation Example 1 of the fullerenol was added to the urethane prepolymer in a proportion of 0.25% by weight based on the total amount of the urethane prepolymer (solid content) and mixed, and the mixture was preheated to 110 ° C. Pour into a 0.2 mm thick mold that has been kept warm, and keep it at 110 ° C for 24 hours.
A fullerenol-introduced polyurethane elastomer in which fullerenol was introduced was prepared by allowing the mixture to stand in an oven for a period of time to carry out a curing reaction.

The above-mentioned fullerenol-introduced polyurethane elastomer was cast into a film having a thickness of 200 μm by a casting method to prepare a film-like fullerenol-introduced polyurethane elastomer to prepare a fullerenol-introduced polyurethane elastomer piezoelectric element.

(Evaluation of Piezoelectric Property) The fullerenol-introduced polyurethane elastomer piezoelectric element prepared in Example 1 was pressed, and the induced voltage generated when this was pressed was measured to evaluate the piezoelectricity at the time of pressing. The measurement result is shown in FIG.

Specifically, a fullerenol-introduced polyurethane elastomer piezoelectric element (film) is provided with a weight (weight 0).
˜3 kg) and pressurizing, the voltage (mV) generated on both surfaces of the piezoelectric element with respect to the load (g) at the time of pressurizing is measured, and when the pressurizing is removed (released), The voltage (mV) generated on both surfaces is measured to find the relationship between the load (g) when pressure is applied or the load (g) that is pressed when pressure is released and the voltage (mV) generated on both surfaces of the piezoelectric element. The graph is shown in FIG.

As shown in FIG. 1, it was confirmed that when the filmy fullerenol-introduced polyurethane elastomer according to Example 1 was pressed, an induced voltage was generated on the surface of the film. It was also confirmed that an induced voltage was generated on the surface of the film even when the pressure was released.

The fullerenol-introduced polyurethane elastomer piezoelectric element prepared in Example 1 was stretched,
The induced voltage generated during this stretching was measured to evaluate the piezoelectricity during stretching, and the measurement results are shown in FIG.

Specifically, the fullerenol-introduced polyurethane elastomer piezoelectric element (film) is stretched 1.5 times, and the voltage (m) generated on both surfaces of the piezoelectric element during stretching.
The time (second) change of V) was measured, and the result is shown in FIG.

From FIG. 2, it was confirmed that even when the film was stretched, a potential having a fast response was regularly induced on the film surface as shown in FIG. 2, and a typical piezoelectric effect was exhibited.

Accordingly, the fullerenol-introduced polyurethane elastomer piezoelectric element of the example is amplified by amplifying the voltage generated by pressurization and stretching and subjecting it to appropriate signal processing to obtain various types of flexible and flexible peculiar to polyurethane elastomers. It can be applied as a pressure sensor or a contact sensor.

(Example 2) 3 g of fullerene and 45 ml of fuming sulfuric acid were mixed and stirred at 67 ° C. for 1 to 4 weeks to carry out a sulfonation reaction. Further, distilled water was added, and the mixture was stirred at 85 ° C. for 3 days. Then, a hydrolysis reaction was performed to prepare three types of fullerenol having different numbers of hydroxyl groups introduced into the molecule.

A fullerenol-introduced polyurethane elastomer in which fullerenol was introduced was prepared in the same manner as in Example 1 using these three types of fullerenol having different numbers of hydroxyl groups, and the fullerenol-introduced polyurethane elastomer was further used. A film-like fullerenol-introduced polyurethane elastomer piezoelectric element was produced in the same manner as in Example 1.

The induced voltage generated when a constant pressure (200 g) was applied to the fullerenol-introduced polyurethane elastomer piezoelectric element (in the form of a film) was measured to determine the piezoelectricity due to the difference in the number of hydroxyl groups contained in fullerenol. The evaluation was performed and the measurement results are shown in FIG. Specifically, a weight (200 g) is put on a fullerenol-introduced polyurethane elastomer piezoelectric element (film) and pressure is applied, and the voltage (mV) generated on both surfaces of the piezoelectric element at the time of pressurization (load 200 g) is measured. Then, a graph of the relationship between the number of hydroxyl groups contained in fullerenol and the voltage (mV) generated on both surfaces of the piezoelectric element by pressurization (200 g) is shown in FIG.
In the graph shown in FIG. 3, the horizontal axis represents the transmittance (%
As shown in T), the lower transmittance corresponds to a fullerenol-introduced polyurethane elastomer piezoelectric element due to the larger number of fullerenol hydroxyl groups, while the higher transmittance corresponds to the smaller number of fullerenol hydroxyl groups. It corresponds to a fullerenol-introduced polyurethane elastomer piezoelectric element.

From FIG. 3, it was confirmed that the larger the number of hydroxyl groups contained in fullerenol, the larger the induced voltage.

[Brief description of drawings]

FIG. 1 is a load (g) when pressure is applied to a piezoelectric element according to an embodiment or a load (g) that is pressed when pressure is released.
It is a figure which shows the graph of the relationship between the voltage (mV) produced on both surfaces of a piezoelectric element.

FIG. 2 is a diagram showing a graph of time (second) change of voltage (mV) generated on both surfaces of the piezoelectric element when the piezoelectric element according to the example is stretched.

FIG. 3 is a graph showing the relationship between the number of hydroxyl groups contained in fullerenol and the voltage (mV) generated on both surfaces of the piezoelectric element when pressure is applied (200 g) when the piezoelectric element according to the example is pressurized. FIG.

FIG. 4 is a schematic sectional view partially showing an example of the pressure-sensitive sensor of the present invention.

[Explanation of symbols]

1 Pressure sensor 2-line electrode side sheet-like substrate 21 row electrode 22 Pressure-sensitive conductive layer for row electrode 3 row electrode side sheet-like substrate 31 column electrodes Pressure-sensitive conductive layer for 32 column electrodes

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Claims (4)

[Claims] 1. A polyurethane elastomer piezoelectric element comprising a polyurethane elastomer in which fullerenol is introduced. 2. The polyurethane elastomer piezoelectric element according to claim 1, which is a film or sheet composed of a polyurethane elastomer into which fullerenol has been introduced. 3. A pressure sensitive sensor, wherein the polyurethane elastomer piezoelectric element according to claim 1 is used as the piezoelectric element. 4. A contact sensor, wherein the polyurethane elastomer piezoelectric element according to claim 1 or 2 is used as the piezoelectric element.